BIOLOGICALDENITRIFICATION OF

DRINKING WATER FOR

RURAL COMMUNITIES

*•••'• •

• • ; j / / ^ j ^ j / \ / - j r-Vj/£ . ' • J J J ^> JJJ J ~L*S I ' •—' 1

J JOANN SILVERSTEIN AND GARY CARLSON

9 DEPT. OF CIVIL, ENVIRONMENTAL &

J ARCHITECTURAL ENGINEERING

• UNIVERSITY OF COLORADO, BOULDER• . ' • .• . -• . ' . . : ' .

MAY 1999

EXECUTIVE SUMMARY

This is the second volume of the Final Project Report of the project:"Demonstration of the Biological Denitrification of Drinking Water for RuralCommunities," co-sponsored by National Rural Electric CooperativeAssociation (NRECA) and the Electric Power Research Institute (EPRI)through the EPRI Community Environmental Center (CEC), Project # WO-2662-84. Other sponsors were: the National Water Research Institute(NWRI), the State of Colorado through its Department of Local Affairs, theTown of Wiggins, Colorado, the University of Colorado and NitrateRemoval Technologies, LLC, of Golden, Colorado.

There were two themes in the demonstration goals. One was toinvestigate the technical performance of a packed bed biofilmdenitrification process for drinking water treatment, that had beendeveloped and tested by Dr. JoAnn Silverstein and colleagues at theUniversity of Colorado in laboratory and pilot-scale research, at full scaleduring long-term operation. The second aspect of the demonstration wasto obtain information to evaluate the operability of the process in a ruralcommunity typical of those with drinking water supplies most commonlyimpacted by ground water nitrate contamination. We anticipated thatknowledge gained in support of both of these goals was important fortimely development of process equipment for the novel drinking watertreatment process that would be available to small drinking water utilitiesin rural areas.

Three criteria governed design and operation of the demonstration facilitylocated in the Town of Wiggins, Colorado, including monitoring and dataanalysis. These were: (1) technical reliability of the denitrification processand resulting consistency of product drinking water quality, (2) operabilityof the process in a rural community affording limited operator attention andlow tolerance for equipment failure, and (3) reasonable cost comparedwith other methods for nitrate removal from drinking water. This Volume 2report addresses the performance of the demonstration of the drinkingwater denitrification process at Wiggins, Colorado with respect to thosecriteria. The earlier Volume 1 report (Silverstein, July 1997) describes thedenitrification project background, specifications of process equipment atthe Wiggins, Colorado demonstration facility, start up operations and planfor monitoring the water quality at the demonstration plant.

LEGAL NOTICE

This report was prepared by the organization(s) named below as anaccount of work sponsored by the Electric Power Research Institute, Inc. (EPRI).Neither EPRI, members of EPRI, the organization(s) named below, nor anyperson acting on their behalf: (a) makes any warranty, express or implied, withrespect to the use of any information, apparatus, method or process disclosed inthis report or that such use may not infringe on privately owned rights; or (b)assumes any liabilities with respect to the use of, or for damages resulting fromthe use of, any information, apparatus, method, or process disclosed in thisreport.

The University of Colorado (preparer of this report)

TABLE OF CONTENTS

Page

EXECUTIVE SUMMARY i

INTRODUCTION

Operations 1Maintenance 5Process Water Quality Monitoring 10

RESULTS

Nitrate 16Dissolved Organic Carbon 23Nitrite 33Dissolved Oxygen 36pH 42Turbidity 49Bacteria

Total Coliform and E. coli MPN 619 Heterotrophic Plate Count (HPC) 63^ Chlorine Demand 66^ Total Trihalomethane Formation Potential (TTHMFP) 68w Manganese 709 Color and Odor 71g Operations Data

Denitrifying Biotower Air Scour 72

•

•9 DISCUSSION

ftw Effects of Process Scale-Up 76• Drinking Water Quality 79• Carbon Substrate: HFCS vs. Acetic Acid 81A Dissolved Oxygen 83^ Equipment Modifications 85• Operability 86

•

• CONCLUSIONS 89

• REFERENCES 90

TABLE OF CONTENTS (cont'd)

COST AND ENERGY USE EVALUATION

COMMERCIALIZATION

ACKNOWLEDGEMENTS

APPENDIX A: MONITORING DATA

APPENDIX B: COST SURVEY RESULTS

Page

92

101

102

FIGURES

1. Denitrification System Schematic2. Nitrate Mass Loading During Demonstration3. Dynamics of Biotower Hydraulic Characteristics4. Nitrate in Well Water and Denitrification System Influent5. Biotower Influent and Effluent Nitrate6. Denitrification Performance in Each Biotower7. Nitrate Profile from Well to System Effluent8. DOC in Well Water and Denitrification System Influent9. Biotower Influent and Effluent DOC10. Roughing Filter Influent and Effluent DOC11. Slow Sand Filter Influent and Effluent DOC12. DOC in Well Water and Denitrification System Effluent13. Biotower Effluent Nitrite14. System Nitrite Profiles15. DO in Well Water and Denitrification System Influent16. Effluent DO from Biotowers 1 and 217. Roughing Filter Influent and Effluent DO18. Slow Sand Filter Influent and Effluent DO19. DO in Well Water and Denitrification System Effluent20. pH in Well Water and Denitrification System Influent21. Roughing Filter Influent and Effluent pH22. Slow Sand Filter Influent and Effluent pH23. pH of Well Water and Denitrification System Effluent

Page

2581719212225272931323435373839404143454647

IV

FIGURES (cont'd)

24. Turbidity Profiles for Well Water and Biotower Effluent25. Roughing Filter Influent and Effluent Turbidity26. Slow Sand Filter Influent and Effluent turbidity27. Turbidity of Well Water and Denitrification System Effluent28. Turbidity Profile from Well Water to Denitrification System Effluent29. Continuous System Effluent Turbidity - June 199730. Continuous Effluent turbidity - July 199731. Continuous Effluent Turbidity - August 199732. Continuous Effluent Turbidity - September 199733. Continuous Effluent Turbidity - October 199734. System Profiles for Total Coliform Bacteria MPN35. System Profiles for Total Coliform MPN after Pre-Chlorination36. System Profiles for Heterotrophic Plate Count37. Well Water and System Effluent TTHMFP38. Denitrification Recovery after Air Scour39. Biotower Effluent Turbidity after Air Scour40. Relation between DOC and Nitrate Consumption41. Effect of Influent DO on Denitrification42. Time profiles of Influent DO and Denitrification43. Correlation Between Influent and Effluent Nitrate44. Effect of Plant Size on Unit Ion Exchange Costs45. Effect of Plant Size on Unit Reverse Osmosis Costs

Page

50515354555657585960616264697374828485889798

TABLES

1. Well Water and Denitrification System Influent Water Quality2. Biotower Air Scour Operations Summary3. Slow Sand Filter Maintenance and Scraping4. Denitrification System Sample Locations5. Denitrification System Monitoring6. Statistics for Well Water and System Influent Nitrate7. Statistics for System Influent and Effluent Nitrate8. Statistics for Nitrate Removal through Each Unit Process9. Statistics for Well Water And System Influent DOC10. Statistics for Biotower Influent and Effluent DOC11. Statistics for Roughing Filter Influent and Effluent DOC12. Statistics for Slow Sand Filter Influent and Effluent DOC

Page

479101118202226272930

v

TABLES (cont'd)

Page

13. Statistics for DOC Profiles from Well Water to System Effluent 3214. Statistics for Nitrite Occurrence 3315. Statistics for Well Water and System Effluent DO 4216. Statistics for Well Water and Biotower Effluent pH 4417. Statistics for Well Water and System Effluent pH 4718. Statistics for Well Water and Biotower Effluent Turbidity 4919. Statistics for Roughing Filter Influent and Effluent Turbidity 5220. Statistics for Slow Sand Filter Influent and Effluent Turbidity 5221. Statistics for Effect of Denitrification Processes on Turbidity 5522. Statistics for Total Coliform MPN Data 6223. Statistics for Heterotrophic Plate Count CFU Data 6424. Results of 24-hour Chlorine Demand Tests 6625. Statistics for 24-hour Chlorine Demand 6726. Statistics for TTHMFP Analyses for Well Water and System Effluent 6827. Manganese Content of Biofilm and Sand Solids 7028. Denitrification Statistics Immediately After Air Scour 7329. Scale-Up of Biotower Physical and Hydraulic Parameters 7730. Scale-Up of Filter Physical and Hydraulic Parameters 7831. Quality of Well Water and Denitrified Product Water 8032. Nitrate Removal Processes Used by Utilities Surveyed 9533. Statistics for Cost Data from Utility Survey 9734. Published Cost Estimates for IX, RO and Denitrification 99

VI

• INTRODUCTION•£

This demonstration of drinking water denitrification in the Town of Wiggins,9 Colorado was a culmination of over 8 years of laboratory research and£ field testing to develop a biological denitrification process for drinking waterA treatment especially for operation by small utilities. This technology was_ developed by Dr. JoAnn Silverstein at the University of Colorado, Boulder* and was patented on October 28,1997 (US Patent No. 5,681,471) with• the laboratory research as a basis. Detailed description of the packed-f tower biofilm denitrification process and the pilot facility as well as theA rationale for a demonstration at full scale in a rural venue is contained in

Volume I of the report of this demonstration (Silverstein, 1997). Support for^ the demonstration was provided by the Electric Power Research Institute£ (EPRI) through its Community Environmental Center (CEC), the NationalA Rural Electric Cooperative Association (NRECA), the National Water- Research Institute (NWRI), the State of Colorado Department of Local* Affairs, the Town of Wiggins, Colorado, the University of Colorado and• Nitrate Removal Technologies, LLC.

• The demonstration at Wiggins had three goals:

• 1. Full-scale operation to evaluate the feasibility of applying the novelA drinking water denitrification process developed at the University of^ Colorado to drinking water treatment in a rural community with limited^ operator attention.•f 2. Long-term comprehensive monitoring of process and product water^ quality characteristics in order to specify the denitrification system^ performance reliably under realistic operating conditions.

•f 3. Evaluation and modification of full-scale process equipment designed* using parameters that were based on bench-scale research.

• OPERATIONS•Aw The demonstration was conducted at a pilot facility built in the Town ofw Wiggins, Colorado. Construction of the Wiggins demonstration plant with a9 capacity of 38 liters per minute (10 GPM) was completed in July 1996. TheA hydraulic capacity of the denitrifying Biotowers was 76 Ipm (20 GPM);

however the overall plant capacity was constrained by the slow sand filter™ which had a capacity of 38 Ipm. The flow schematic of the denitrification• and filtration polishing processes is shown in Figure 1. Each Biotower had9 a packed bed volume of 1.35 m3 giving a total denitrification reactor^ volume of 2.7 m3. Biofilm attachment was initiated in the denitrifying

Biotowers by recirculating a suspended flocculant biomass culture that

had been enriched from creek sediment at the University of ColoradoEnvironmental Engineering labs. A suspension containing approximately 1kg of biomass solids (0.4 g-MLVSS/liter-media, dry weight) wasrecirculated through the Biotowers for 48 hours. No external water flow orchemical addition occurred during recirculation. After 48 hours thebiomass suspension was drained and flow-through operation commencedon September 29,1996 at a reduced flow rate of 19.4 Ipm (5 GPM). Theflow rate was increased in steps to 57 Ipm (15 GPM) by mid-December1996. Flow splitting of the 57 Ipm denitrified water to maintain a flow of 38Ipm to the slow sand filter was found to be very difficult with the existingpump, so in April 1997 the influent flow rate was reduced to 38 Ipm (10GPM). The demonstration plant was operated continuously at this flowrate between April 14 and October 31,1997, a period of 184 days.

Figure 1. Denitrification System Configuration & Sampling Points

Denitrifying DenitrifyingBiotower 1 Biotower 2

RoughingFilter

OBiotower #2 Effluent

©Well + MFCS

OWell

© Biotower #1Effluent

© Slow SandFilter Reservoir

©RoughingFilterEffluent

Slow Sand Flfter® SlowSand FilterEffluent

•

The well water influent from the Town of Wiggins had water qualitycharacteristics as summarized in column 2 of Table 1. Selected influentwater quality characteristics were changed as the result of chemicaladdition as described below and the changes have been shown in column3 of Table 1. The Town of Wiggins water system chlorine contact tank wasupstream of the denitrification process, and at times the chlorine residualin the influent water was observed to be very high (> 10 mg/L as Cl). Forthat reason, sodium thiosulfate (Na2S2O3) was used to dechlorinate at acontinuous concentration of 30 mg/L. The nitrate concentration in the wellsat the Town of Wiggins was relatively low, varying between 6 and 9 mg/LNO3-N with an average of 6.7 mg/L NO3-N. In January 1997 it wasdecided to augment the nitrate in the influent in order to make a convincingdemonstration for small utilities with serious nitrate contamination of theirwater supplies. Nitrate was added from a stock solution of KNO3 to obtaina total influent nitrate-nitrogen concentration of 20 mg/L NO3-N. Inaddition, phosphorus was found to be limiting in the raw well water andwas added for an influent concentration range of 2 - 3 mg/L PO4-P.

The carbon source for denitrification was com syrup. Food grade comsyrup was obtained in bulk from two sources: GTC Nutrition Company(Johnstown, Colorado) and Liquid Sugars, Inc. (Denver, Colorado), ashigh-fructose com syrup (MFCS), a mixture of approximately 52% fructoseand 48% glucose. Several factors motivated use of com syrup instead ofthe carbon source used for process development, acetic acid(CH3COOH). One was cost. The price of com syrup was approximately$0.10/kg, whereas food-grade glacial acetic acid was much moreexpensive: $0.50/kg. In addition, as is discussed in Volume 1 or this report(Silverstein, 1997) a failure of the carbon dosing pump in August 1996resulted in a severe process upset after the influent pH dropped to 4.8 formore than 24 hours. After lab testing, it was confirmed that thedenitrification occurred in the biofilm as well with com syrup as withacetate. In addition, com syrup is less corrosive than acetic acid. Thecombination of feasibility, avoidance of denitrification process upsets andcost led to the decision to switch to com syrup as the carbon source forthe denitrifying bacteria. Unfortunately we underestimated the difficultiesassociated with using com syrup, as will be discussed later in this report.

In April 1997 the flow was increased to 38.8 Ipm (10 GPM) and theprocesses were operated continuously at the same flow rate and influentwater quality composition. Biotower nitrate mass loading from October 2,1996 to October 31, 1997 is shown in Figure 2. After April 14, the influentflow rate and nitrate concentration were stable at 38 Ipm and 19.6 mg/LNO3-N, respectively, yielding a system nitrate mass loading rate of 1.07kg-N/day (0,4 kg-N/m3/day). During the period of stable operation fromApril to November 1997, HFCS was added to the well water to obtain an

influent dissolved organic carbon (DOC) concentration of 34.1 + 7.9 mg/Lto obtain an average carbon:nitrogen ratio (C:N) of 1.74:1.

Dissolved oxygen (DO) concentration was relatively high in the well waterafter detention in the air-pressurized equalization tank (3.3 + 1.5 mg/L).Although denitrification is suppressed in an aerobic environment, noattempt was made to strip oxygen from the influent water. Instead, it wasassumed that a fraction of the influent DOC substrate (MFCS) would beused by aerobic bacteria near the entrance to the Biotowers, as had beenobserved in laboratory operation of the denitrifying Biotowers (Hogrewe,1990). Thus the anoxic environment necessary for denitrification would beestablished quickly. The HFCS addition was increased over thedenitrification requirement to accommodate aerobic consumptionassuming an average DO of 3 mg/L.

Table 1. Water Quality Characteristics in Drinking Water Supply Wells for theTown of Wiggins and in Denitrification System Influent after Chemical Addition

Constituent

Nitrate-nitrogen (NO3-N)Nitrite-nitrogen (NO2-N)Dissolved Organic Carbon (DOC)Dissolved Oxygen (DO)Free Chlorine (Cl)Sulfate (SO/")Phosphorus (PO4-P)Alkalinity (CaCO3)Hardness (CaCO3)Total Dissolved SolidsDissolved Iron1

pH (pH units)Temperature range (°C)Turbidity (NTU)Total Colifomn Bacteria (MPN/100ml)E. coll Bacteria (MPN/100 ml)Chlorine DemandTotal Trihalomethane FormationPotential (|ig/L)

Well WaterConcentration

(mg/L)*6.7+1.3

n.d.2.3 ± 6.23.3 ±1.50.5 -101

470 .n.d.

235-243200n.a.n.d.

7,26 ± 0.0513-180.20

20±343

n.d.0.5 - 1 .83

73.1 ±13.2

Biotower InfluentConcentration

(mg/L)2-*19.6 + 2.4

n.d.34.1 +7.93.3 + 1.5

n.d.500

1.5-2250200n.a.n.d.

7.26 + 0.0513-180.20n.d.

n.d.n.a.n.a.

*except noted units1 after chlorination in Town water supply system equalization tank2atter dechlorination and addition of DOC, NO3-N and PO4-P3raw well water (before chlorination and dechlorination)n.d. = not detected; n.a. = not available

4

••••

Figure 2. Nitrate mass loading to denitrifying Biotowersthroughout demonstration (Oct. 1996 to Nov. 1997)

The results presented in this report are focused on those obtained during the longperiod of stable operation at 38 Ipm, from April 15 - October 31,1997.

MAINTENANCE

BIOTOWER AIR SCOUR. Routine operation of the packed towerbiofilm denitrification process includes regular fluidization of theBiotower media bed by air (air scour) to remove excess biomass.During air scour, flow to the Biotowers stops and approximately 15% ofthe water in the towers is drained off. Air is added, decreasing thedensity of the water and allowing downward fluidization of the buoyantpolypropylene packing media with attached biofilm. Tumbling causes afraction of the biomass to be released into the water. The wastebiomass suspension is drained while the bed is still fluidized to preventit from being trapped in while the bed is reforming. In previousdenitrification process development research, it was found that athydraulic and mass loading rates similar to those used in thedemonstration, fluidization of the Biotowers every 21 days for a periodof 5 - 15 minutes was sufficient to maintain evenly disbursed plug flow,avoiding channelization and short circuiting. The airflow rate range

specified in early research was 0.31 - 0.46 m3-air/m2-cross-sectionarea/min (1 -1.5 ft3/ft2/min) for bed depths ranging from 1.8 to 3.7 m (6-12ft) (Cookef a/., 1991; deMendonca and Silverstein, 1992;Hogrewe, 1990; Rogers, 1990).

Air scour operations during the demonstration differed from the abovein two ways both of which turned out to be significant. First, there wasnot a compressor available to generate the minimum air flow ratepreviously determined. The portable compressor used for air scourgenerated a maximum airflow rate of 0.085 m3/min (3 cfm) with theBiotower static pressure at 69 kPa-gage (10 psig). Since the Biotowercross section area was 0.65 m2 (7 ft2), this produced a column air flowloading of only 0.13 m3/m2/min, less than 50% of the airflow rate usedin the development research. Second, the frequency of air scouring atthe Wiggins plant was much less than was used in previous operationat pilot-scale. Regular air scour was only begun 48 days after steadystate flow at 38 Ipm and influent nitrate concentration of 20 mg/L NO3-N. This was 226 days after inoculation of the columns, during whichthey had received flows varying from 19 to 57 Ipm and influent NO3-Nfrom 6.7 to 20 mg/L. Fifty one days passed before the next air scour(July 11, 1997) and From May through October 1997, the Biotowerswere air scoured every 25 - 26 days. Table 2 is a summary of air scouroperations throughout the demonstration.

Another change from earlier research was the column packing media.In laboratory and pilot-scale investigations, the high porosity mediawere spherical (Tri-Packs®, Jaeger Products, Inc., Houston, Texas).The Biotowers at the Wiggins facility were packed with cylindricalmedia (Nor-Pac®, NSW Corp., Roanoke, Virginia. Both the Jaeger Tri-Packs and Nor-Pac media had very similar packing characteristics.Both were polypropylene, slightly buoyant with a specific gravity ofapproximately 0.96, and packed porosity of 0.94. Nominal diameter ofthe Nor-Pac cylinders was 3.8 cm (1.5 inch); the Jaeger Tri-Packsspheres were 5 cm (2 inch). The specific surface areas were 45 m2/m3

and 43 m2/m3 for the Nor-Pac and Tri-Packs media, respectively. Bothmedia afforded similar flow-through denitrification performance.Because the Nor-Pac media were significantly less expensive than theTri-Packs, it was decided to use them at the Wiggins plant. Later it wasdiscovered that the spherical shape of the Tri-Packs media enabledeasy fluidization, whereas the Nor-Pac media cylinders that wereformed by extrusion had plastic pieces extending from both ends ofeach cylindrical particle that acted like hooks. The extensions caughtother media particles, locking them together and many of the lockedmedia particle aggregates were not separated during air scouring,eventually leading to clogging problems.

6

Table 2. Biotower Air Scour Operations Summary

OPERATION INTERVAL(days)

SCOUR DATE

SCOURDURATION

(min)

AIRFLOW*

(Ipm (cfm))COMMENTS

37.9 !pm (10gpm) normal 48

5/1 9/97 (firstair scour)

10 85(3)

Significantly more biomassremoved from lead tower,both black and cream-colored. Gage pressure atBiotower inlet after scourwas 69 kPa (10 psi).

37.9 Ipm (10 51gpm) normal

7/11/97 5 85(3)Same biomass differencesas in 5/19 scour. Biotowerinlet gage pressure afterscour was 57 kPa (8.3 psi).

37.9 Ipm (10 25 -gpm) normal

8/7/97 4 85(3)

Gage pressure at Biotowerinlet after scour was 48 kPa(6.9 psi). Measured fillingtime for Biotower 1 was 1 2minutes. Filling time forboth columns was 34minutes,

37,9 Ipm (10 26gpm) normal

9/4/97 4 85(3)Gage pressure at Biotowerinlet after scour was 61 kPa(8.8 psi). Fill time forBiotower 1 was 13 minutes;for both Biotowers, 33minutes.

37.9 Ipm (10 25gprn) normal

10/1/97 1.5 85(3)Gage pressure at Biotowerinlet after scour was 48 kPa(7.0 psi). Fill time forBiotower 1 was 13 minutes;for both Biotowers, 31minutes.

* Biotower back-pressure at time of air scour ranged from 69 -83 kPa-gage (10 to12psig)

7

The combined effects of low airflow, inadequate fluidization and infrequentair scouring caused severe clogging and probably flow channelization inthe reactors, resulting in significantly reduced Biotower residence times.Figure 3 is a comparison of the Biotower empty bed contact time (EBCT)which was 34 minutes and the actual time to fill the Biotowers just after airscour. Biotower 1, the first reactor in the sequence, received the heaviestcarbon and nitrogen loading. By the time the first measurement was takenafter the July 11 air scour, the fill time had already been reduced to 13minutes (38% EBCT). Detention time was maintained in Biotower 2 untilthe August 8 air scour, when the fill time was reduced to 22 minutes.

Ei-

7/1 1/978/5/97

8/30/97

EBCT

Biotower 2

Biotower 1

9/24/97

Figure 3. Hydraulic characteristics of Biotowers. Design empty bed contacttime (EBCT) was 34.4 minutes. Detention times for Biotowers 1 and 2 areestimated from time required for filling each reactor just after air scour onJuly 11, Augusts, September5 and October 1,1997..

SLOW SAND FILTER. The slow sand filter was scraped three timesduring normal operation at 38 Ipm and 20 mg/L influent NOa-N: once onApril 29, after 102 days of operation, again after 123 days operation, onAugust 29, and a third time on October 30, after 62 days operation. Table3 has descriptions of the scraping operations throughout thedemonstration (October 1996 - November 1997).

Table 3. Slow sand filter maintenance, including scraping.

•

Date

10/15/96

11/3/96

12/22/96

1/16/97

4/28/97

8/29/97

10/31/97

Interval(days)

22

19

49

25

102

123

63

Sand Removed

None Slow sand filter was drained.Short run time due to largeamount of solids pushed throughSSF when recirculation began.

100 Ibs. (topy2")

Top sand layer was very dark inolor. The dried schmutzdecke

was light brown/cream color.Approx. 100Ibs. (top W)

The top sand layer (top 1/2") wasvery dark. After scraping, thereappeared to be random blackspots in filter bed. This may beMn precipitating out and that'fingering1' may be occurringthrough bed.

None

Approx. 100Ibs. (top 1/2")

Approx. 100Ibs. (top 1/2")

None

Comments

Drained slow sand filter. The filterhad not reached terminalneadloss, however, it was feltthat until we achieved acceptabledenitrification performance thefilter would not be used. Shortlyafter phosphorus was added tothe system the filter was broughtaack online.Slow sand filter was restartedonce complete denitrification hadbeen achieved in the system.This was one month after startingsupplemental phosphorusaddition.Top sand layer was very dark incolor. The dried schmutzdeckewas light brown/cream color.Samples of sand were takenback to the laboratory formanganese analysis.End of test.

9

PROCESS WATER QUALITY MONITORING

Monitoring served several purposes. First, denitrification systemeffluent data relevant to finished drinking water quality were generatedin order to evaluate process reliability in producing consistently potablewater. Second, data were collected at intermediate points in theprocess train to provide insight on individual process behavior andequipment performance. Third, frequent sampling indicated howprocess monitoring during actual operation could be specified. Forexample, some water quality characteristics were found to have verylow variability, for example, pH, alkalinity, sulfate, so that monitoringfrequency could be decreased in actual drinking water treatmentoperation. Other parameters such as influent dissolved oxygen werequite variable, but the variability had little effect on denitrification. Onthe other hand, Biotower effluent dissolved oxygen was a usefulindicator of denitrification. Development of a reliable but cost-effectivesampling and analyses scheme for monitoring actual operation of thedenitrification process is ongoing, and the demonstration monitoringprogram has provided some benchmarks for that. Seven samplingpoints were used for monitoring during operation of the denitrificationprocess from April through October 1997. Locations of the samplingpoints shown in Figure 1 and referred to throughout this document aregiven in Table 4. The demonstration monitoring procedure is presentedin Table 5.

Table 4. Denitrification process sampling.

Sample Designation Sample Location (on Figure 1)Raw Town of Wiggins well water (1)Raw + HFCS System influent water after chemical

addition (NaSO3, HFCS, N, and P) (2)Biotower #1 effluent Exit pipe from Biotower #1 (3)Biotower #2 effluent Exit pipe from Biotower #2 (4)Roughing filter effluent Surge tank below roughing filter (5)Slow sand filter Influent Reservoir over sand bed (6)Slow sand filter effluent Stand pipe collecting filter underdrain (7)

AIR SCOUR MONITORING. We had found previously thatdenitrification performance was recovered in pilot-scale Biotowersimmediately after air scour (Mendonca and Silverstein, 1992). Specialanalyses were done after air scour of the Biotowers in the Wigginsfacility in order to evaluate process performance just after this regularmaintenance procedure at full scale. Samples for nitrate, nitrite, DOCturbidity, pH and DO were collected and analyzed at points 4,

10

(Biotower 2 effluent) and 7 (slow sand filter effluent) just after re-startof continuous flow and at 60, 120, 180, 240, 300, and 360 minuteslater.

Table 5. Denitrification process monitoring

Water Quality ParameterNitrate-nitrogen (NO3-N)Nitrite-nitrogen (NO2-N)Dissolved organic carbon(DOC)Dissolved oxygen (DO)PHSystem turbidity1

Product water turbidity2

Total Coliform BacteriaE. coll BacteriaHeterotrophic PlateCount (HPC) BacteriaChlorine DemandTotal TrihalomethaneFormation Potential

JJTHMFP)3 _,Biotower headlessColor4

Odor4

Biomass and sandmanganese content

Sample Location(s)1,2,3,4,5,71,2,3,4,5,7

1,2,3,4,5,6,7

1,2,3 ,4 ,5 ,6 ,71,2,3,4,5,6,71,2,3,4,5,6,7

7

1,4,5,71,4,5,71,4,5,7

2,72,7

277

5, 6

Sample Frequency2/week*2/week*2/week*

2/week*2/week*

twice/week*on-line

1 /month*1 /mo nth1 /month

1 /month*1 /month*

2/month*111

^Minimum frequency. Often took 1 extra sample/period1Discrete samples (Model 2100A, Hach Co., Loveland, Colorado)2On-lineturbidimeter (Model 1720C, Hach Co., Loveland, Colorado)3Chloroform, dichlorobromoform, chlorodibromoform and bromoform410/15/97

ANALYTICAL METHODS

Several constituents were measured at the Wiggins site: influent flowrate, dissolved oxygen, turbidity, pH, Biotower headloss andtemperature.

11

Influent Flow RateInfluent flow was monitored continuously just after the main system pumpat the building inlet pipe using an in-line digital flow meter. The metermonitored flow continuously and also cumulative flow.

Dissolved Oxygen (DO)Dissolved oxygen and temperature were measured using atemperature-compensated meter and field probe (YS1 Model 52,Yellow Springs, OH). System samples at points 2, 3, and 4 werecollected using Teflon tubes (0.64 cm ID) which ran from valves in thepipes to the analytical area at the demonstration facility. For probemeasurements (temperature, DO, pH) a clean 1-liter polypropylenewas allowed to overflow for at least three volumes before taking theprobe measurement.

TurbidityTurbidity was measured by two methods. Discrete samples werecollected at points throughout the system several time a week andanalyzed on-site using aturbidimeter (Model 2100A, Hach ChemicalCo., Loveland, Colorado). In addition an on-line turbidimeter (Model1720C, Hach Chemical Co., Loveland, Colorado) was used forcontinuous monitoring of finished water turbidity from June 25 toOctober 31, 1997.

PHSample pH was measured by using a combination electrode (Model8104BN; Orion Research Inc., Boston, MA) in conjunction with a OrionModel 720A pH meter. Sample collection followed the same procedureas described for DO.

Biotower HeadlossBiotower headless was monitored using a dial pressure gage mountedin the pipe at the inlet to Biotower 1. Dynamic head through theBiotower system varied from 48 to 69 kPa-gage (6.9 -10 psig) justafter air scour. Before air scour, the maximum Biotower systemdynamic pressure was 83 kPa-gage (12 psig).

Sample Collection ProceduresOther chemical analyses were performed at the EnvironmentalEngineering laboratories at the University of Colorado, Boulder. Thesewere prepared to maintain water quality during transport and storage.All samples for lab chemical analyses collected at the Wiggins facilitywere immediately filtered through a 0.22 u,m filters (GSWP 047 00,Millipore, Bedford, MA) at the plant site to filter sterilize them beforetransport to the laboratory. After filtration, samples were transferred

12

from glass vials into smaller 250-ml polypropylene sample bottleswhich were packed in a container containing a reusable cold-pack andtransported back to the laboratory for chemical analyses.

Nitrate-nitrogen (NO3-N) and Nitrite-nitrogen (NO2-N)Nitrate and nitrite concentrations were determined by ionchromatography (Model 300 DX, Dionex Corp., Sunnyvale, CA).Samples were pre-filtered through a 0.22 fim filter (GSWP 04700,Millipore, Bedford, MA). The samples were then diluted 10:1 due tothe high levels of sulfate present in the water. The samples were thenfiltered through a silver filter (#39637 Dionex Corp.) to remove anychloride in samples. The samples were then refrigerated at 4°C untilanalyses were performed. The 1C column used was a AS9-SC with aAG9-SC guard column. The eluant used was a boric acid, according tothe 1C manufacturer's operating instructions. Standard curves weregenerated during each sample run using standards of 0.25, 0.50, 0.75,1.0, and2.5mg/LNO3-N.

Dissolved Organic CarbonDOC analysis followed Standard Method 505A and was measured bya Shimadzu Carbon Analyzer (Model TOC-5000, Shimadzu ScientificInstruments, Kyoto, Japan) equipped with an automatic sampler(Model ASI-5000) using a standard-sensitivity catalyst. After pre-filtration, the samples were acidified to pH 2.5 -3.0 using 2N HCI.

Coliform and E. coli Bacteria MPN TestsMPN tests for total coliform and E. coli bacteria were performed at theBoulder County Health Department Laboratories using the multipletube lactose fermentation method followed by confirmed test for E. coli,both done as described in Methods 9221 C and E in Standard Methods(APHA, 1992). Samples of water were collected in sterile 1 -liter bottlesobtained from the Health Department Laboratories just before leavingthe Wiggins site. The samples were transported immediately to theHealth Department Laboratories (approximately 1.5 hours) for analysis.The following are the laboratory sample ID numbers for each sampleanalyzed:

Date

7/23/977/31/978/14/979/1 6/9710/15/97

RawWater(1)10421091121714101590

BiotowerEffluent(4)10501088122814131594

RoughFilter Effl.(5)10491089121614141591

SSFEffluent.(7)10481090122914121593

13

Heterotrophic Plate Count (HPC)HPC tests were performed by Accu-Labs Research, Inc., Golden, CO.Sampling and transportation procedure was the same as for totalcoliform and E. col! MPN analyses as described above. The laboratoryjob numbers for each analysis batch is given below:

Sample Date

6/4/977/23/978/14/979/16/9710/15/97

Lab JobNumber1592016981174551811518787

Total Trihalomethane Formation Potential (TTHMFP)

After pre-filtration through a 0.22 }im filter, the samples were placed in 1 5-ml serum vials and sealed with Teflon-faced caps. Each sample wasadjusted to pH 7.1 using phosphate buffer. Chlorine was added to obtain a3:1 ratio of Cl2:DOC. The sample reaction vials were incubated at 23°C for96 hours and then quenched with sodium thiosulfate. A duplicate samplereaction vial was analyzed for free chlorine to assure total THM formationpotential (TTHMFP) was measured. Extraction of THM compounds wasperformed according to EPA Method 501 .2 by using methyl tert-buty! ether(MTBE). THM species formed in the 96-hour test were analyzed using aHewlett-Packard 5890 Series II Gas Chromatograph equipped with a DB11 .5 micron column (J&W Scientific) utilizing an electron capture detectorand autosampler, Analytes were chloroform (CHCI3), dichlorobromoform(CHCI2Br), chlorodibromoform (CHC!Br2), and bromoform (CHBr3) andTHM was calculated as the sum of these four species..

Chlorine Demand TestOf particular interest in monitoring chlorine demand was the addition ofchlorine-demanding compounds to the well water during thedenitrification process. For that reason, chlorine demandmeasurements were made of well water and the slow sand filtereffluent product water. Pre-filtered samples were placed into 73-mlserum vials and sealed with Teflon-faced caps. Five to six vials wereused for each sample corresponding to four to five different chlorinedoses and one blank. In addition, duplicate samples were used todetermine the actual chlorine dose at the beginning of the experiment.Chlorine doses ranged from as low as 1 mg-Cla/l to as high as 16 mg-Cla/l. The samples were allowed to incubate at 23 °C for 24 hours inthe absence of light. After 24 hours the samples were analyzed for free

14

chlorine residual using a spectrophotometer and DPD colorimetricreagent (Model DR/2000, Hach Chemical Co., Loveland, CO).

Quality Control/Quality AssuranceField Measurements. pH and DO meters were calibrated before each

day's measurements using standard buffers (pH 7.01 and pH 10.0) andwater saturated air, respectively. Turbidimeters were calibrated usingsealed turbidity standards provided by the manufacturer (Hach ChemicalCo., Loveland, CO).

Laboratory Chemical Analyses. New standard curves for 1C and TOCanalytes (nitrate, nitrite, TOC) were made every time a batch of sampleswas analyzed. Bot the 1C and TOC analyzer had autosamplers, allowingfor intermittent placement of blanks and standards throughout each run. Inaddition sample duplicates and standard spikes were used to insureanalytical accuracy. Analyses for TTHMFP and chlorine demand all weremade using duplicate samples.

Microbial Analyses. Most probable number (MPN) measurements fortotal coliform, E. cotfand heterotrophic plate count (HPC) were made byindependent laboratories each with internal QA/QC procedures.

15

e•• RESULTS

Monitoring data have been separated into sections for nitrate, nitrite, DOC,dissolved oxygen, turbidity, bacteria, TTHMFP, chlorine demand,bioreactor pressure, and slow sand filter headless. The graphs and figuresin this section of the report are summaries of the monitoring data. For themost part, these summaries focus on the period when the entiredenitrification demonstration system was operating at 38 1pm and 20 mg/Linfluent NO3-N, that was collected from mid-April to November 1 999. Rawdata for each analyte and water quality parameter are given in theappendices, presented by collection date. Data for special operatingprocedures such as air-scour and chlorine demand are separated intosections based on the date the test or procedure was performed.

Nitrate (NO3~)

Nitrate was, of course, the key parameter in indicating system^ performance. During operation of the denitrification Biotowers at the• Wiggins facility from October 1 996 to April 1 997 flow and loading changedf significantly, encompassing influent flow rates of 19, 28, 38 and 57 Ipm. In^ addition, the influent nitrate concentration increased by a factor of almost^ three in January 1997, from 6.7 to 19.6 mg-N/L. As shown in Figure 2, the0 overall nitrate loading to the Biotowers varied significantly during this9 period. Finally, especially with the increase in nitrate loading, the systemA probably was phosphorus deficient at least from January to March 1 997

when supplemental phosphate was added. For these reasons, the nitrate• data presented below focus on the performance of the Biotower system• from mid-April to November 1997, when mass nitrate loading and flow ratef were constant and nutrient addition was sufficient for stable denitrification.A Variations in the well water and supplemented influent nitrate™ concentrations are shown in Figure 4. Biotower influent and effluent nitrate9 concentrations are shown in Figure 5, and denitrification performance isA summarized in Table 7.

16

30

25- -

£c.

0)ocooffl 10(0

5 - -

» Weil Water

o Wei I Water + Nitrate

10 mg-N/L MCL

****

1-Apr 2-May 2-Jun 3-Jul 3-Aug 3-Sep 4Oct 4-Nov

Date

Figure 4. Nitrate concentrations of Wiggins well water and system influent fromApril 15, 1997 to Oct 31, 1997 after nitrate addition. Lines are 14-day movingaverages.

Key Points:

1. Wiggins well water had a relatively constant nitrate concentrationbetween 6 mg-N/L and 7 mg-N/L. During this period, nitrate levelsexceeded or met the MCL four times: April 23, June 26, August 29,and Septembers.

2. Nitrate concentrations after the addition of nitrate were variable,ranging from 15 mg-N/L to 25 mg-N/L.

17

3. Statistical analysis (Kolmogorov-Smirnov Normality Test) indicatedthat Wiggins well water nitrate values were not normally distributed(a = 0.05). Upon careful examination of the data, it was felt that thedata was approximated by a normal distribution and was treated asnormally distributed data. System influent nitrate data was normallydistributed.

4. Average nitrate concentrations for Wiggins well water and afternitrate addition from April 15 - October 31, 1997are given below:

Table 6. Average well water and system influent nitrateconcentrations. Data are means ± one standard deviation.

Nitrate-nitrogenWater Source (mg-N/L)

Wiggins Well Water 6.8 ± 1.3

System Influent (after 19.6 + 2.4NO3 addition)

The average value of 19.6 mg-N/L after the addition of nitrate isvery close to the target influent nitrate value of 20.0 mg-N/L.

5. The average system influent nitrate concentration, after addingnitrate, had twice the variability as Wiggins well water nitrate levels,although as a percentage of the mean, the standard error for thesupplemented influent was only 12%; whereas the standard errorfor the well water nitrate levels was 19%. In general, we weresuccessful at maintaining the target dose of 20 mg-N/L in spite offluctuations in the well water concentration.

6. Not surprisingly, a t-test comparing mean nitrate values of wellwater and nitrate-supplemented influent water indicated that theinfluent nitrate concentration was significantly greater than the wellwater nitrate levels (a = 0.05).

18

CJucoo

30

2 5 - -

20--

5 10(0

5 -•

BioTower Influent

BioTower Effluent

10mg-IM/LMCL

0

1-Apr 2-May 2-Jun 3-Jul 3-Aug 3-Sep 4-Oct 4-Nov

Date

Figure 5. Biotower influent and Biotower effluent nitrate concentrations from April.15, 1997 to October 31,1997. Lines are 14-day moving averages.

Key Points:

1. Figure 5 shows that effluent nitrate from the Biotowers had somevariability on the order of ± 2 mg-N/L. However the trend linerepresenting the 14-day moving average shows a graduallyincreasing effluent nitrate levels, especially after August 1997.Possible explanations for the gradual decrease in denitrificationperformance will be discussed later in this report.

2. Effluent nitrate concentration exceeded the 10 mg-N/L maximumcontaminant level (MCL) for nitrate-nitrogen only 5 times during theentire period from April 15, 1997 to October 31, 1997. Two of theseoccurrences were due to failure of the MFCS pump so that theBiotowers received no carbon substrate (July 14, July 18).

19

3. Some of the variability in effluent nitrate concentration was causedby MFCS dosing problems. On the following seven dates, MFCSdosing system was not working properly resulting not in a completefailure, but in an abnormally low influent DOC concentration andhence insufficient carbon for the denitrifying bacteria: May 5, May 7,May 23, July 14, July 15, July 18, Sept. 3.

4. Average nitrate concentrations for both Biotower influent andeffluent are given below:

• Table 7. Average system influent and system effluent nitrateconcentrations and nitrate removal from April 15 - October 31,1997 (mean ± one standard deviation).

NitrateConcentration

(mg-N/L)

Biotower Influent 19.6 ± 2.4

Biotower Effluent 5.0 ± 3.1

Average Nitrate 14.9 ± 3.1Removal (ANO3-N)

The standard error of the mean effluent nitrate is much higher(62%) than that for the influent nitrate (12%), indicating that systemperformance was more variable than the chemical addition to theinfluent. In combining the influent and effluent variances for thevariance for nitrate removal, the effluent nitrate concentrationvariance dominates, so that the standard error for the averagenitrate removal value is 20%. It is important to note that carbon wasnot added in sufficient quantity to achieve 100% removal. Althoughestimating the exact carbon:nitrogen (C:N) ratio for denitrification isespecially difficult for a fermentable substrate like MFCS, theamount dosed into the influent was calculated to achieve aneffluent concentration of approximately 4 mg/L NO3-N. In the firstthree months of operation (roughly, April 15 - July 15, 1997) thiswas achieved consistently except when the carbon dosing pumpfailed. However, the gradual decrease in performance in thesecond half of operations probably was due to more complicatedfactors that will be discussed later. Finally, some of the error may

20

6.

be ascribed to measurement error due to the required dilution of thesamples analyzed in the ion chromatograph. After dilution, thedetection limit of the 1C was approximately 0.1 mg/L NO3-N.

The average nitrate removal was 14.9 mg-N/L during the periodfrom April 15, 1997 to October 31, 1997. On an average basis, thiswas very close to the objective ANO3-N of 16 mg-N/L.

Statistical analysis (Kolmogorov-Smirnov Normality Test) indicatedthat both data sets were normally distributed. A t-test indicated asignificant difference between mean effluent and mean influentnitrate concentrations (a = 0.05).

100

T3CD

CDo3"5

CDO

CD0_

90 -

80 -

70 -

60 -

50 -

40 -

30 -

20 -

10 -

03/23/97

Biotower 1

Biotower 2

Total

5/12/97 7/1/97 8/20/97 10/9/97 11/28/97

Figure 6. Denitrification performance (% nitrate destroyed) in eachBiotower. Trend lines are 14-day moving averages.

Key Points:

1. Figure 6 shows that the distribution of nitrate removal shiftedaround August from the bulk of denitrification occurring in Biotower1 to equal distribution of denitrification performance betweenBiotower 1 and 2. Reduction in denitrification in Biotower 1occurred at the same time that extreme channelization andreduction in hydraulic retention time was observed.

21

System Performance

As expected, denitrification did occur only in the anoxic Biotowers, asindicated by Figure 7. Average nitrate removal in the individualBiotowers, Roughing Filter and Slow Sand filter is given in Table 8.

o

CD

25.0 i

20.0 -

15.0 -

10.0 -

5.0 -

0.0

Figure 7. Nitrate concentration profile from wells through Biotower-Roughing Filter-Slow Sand Filter Sequence from April 15 - Oct. 31, 1997.Error bars are ± one standard deviation.

Table 8. Nitrate removal (ANO3-N) through process sequence, April15 - Oct. 31, 1997. Data are mean ± one standard deviation.

Unit ProcessBiotower 1

Biotower 2

Roughing Filter

Slow Sand Filter

ANO3-N

9.6 ±3.8

4.8 ± 2.7

0.8 + 2.2

0.0+2.4

22

e

Key Points:

f 1 . On average, twice as much nitrate was removed in Biotower 1^ compared with Biotower 2, although from Figure 6, the^ denitrification became more balanced between the two Biotowers9 during the last two months of operation.

•A 2. There were occasional samples of the roughing filter and slow sand

filter effluent which showed "negative" nitrate removal (nitrateformation). This concentration is within the measurement error ofthe ion chromatograph.

Dissolved Organic Carbon (DOC)

The dynamics of organic matter is critical to the function of thedenitrification system. First, most natural ground water is very low insoluble organic material and so biodegradable carbon/energy substratemust be provided forthe denitrifying bacteria. Even if the substrate issupplied sparingly, there will be residual carbon in the Biotower effluent.Also a second concern is the soluble fraction of effluent DOC from theBiotowers that is comprised of soluble metabolic by-products from thebacteria and soluble and colloidal organic compounds sloughed from thebiofilm as cells decay and lyse or biofilm matrix is sheared off. Thisresidual organic material must be removed to maintain water quality in thefinished water, minimize chlorine demand and reduce biofilm growth in thewater distribution system. The roughing filter was designed to removesoluble and colloidal organic material from the Biotowers as well as

ft particulates. Also, the roughing filter protects the slow sand filter from9 overloading with organic compounds which would cause rapid build-up off headless. The roughing filter is also a packed tower biofilm reactor that

operates as a downflow trickling filter. As the Biotower effluent passes* over media, organic compounds are sorbed and biodegraded by bacteriaft living in the biofilm. Unlike the denitrifying Biotowers, the environment isf highly aerobic, which no doubt enhanced the organic carbon removal in^ the roughing filter. A significant fraction of dissolved organic material, as* well as particulate matter, was removed in the slow sand filter. Resultsft which show the dynamics of dissolved organic carbon from the wells as itft passes through the denitrifying Biotowers, the roughing filter, and the slowf sand filter are presented below.

•ii§

23

t

9

Biotowers

Addition of an organic carbon/energy source for the denitrifying bacteriadrives the denitrification reaction in the Biotowers, and is one of the largestanticipated costs of biological denitrification of drinking water. As wasdiscussed in the Operations section, a major change from earlier labresearch and the demonstration at Wiggins was switching thecarbon/energy source from acetic acid to com syrup (MFCS). Theimportant parameter for specifying system operation is the ratio of carbonadded to nitrate-nitrogen destroyed, or the C:N ratio. This ratio is useful forcomparing substrate utilization efficiency, indicating the mass of organiccarbon which must be supplied to destroy a unit mass of nitrate-nitrogen.For acetate, Cook et al. (1992) found that the C:N ratio to insure sufficientcarbon/energy substrate for the denitrifying bacteria in the Biotowersystem was 1.5:1. Preliminary lab tests on bench-top biofilm reactors weredone in August 1996 when we were considering substituting MFCS foracetate. The results indicated that the appropriate C:N ratio for HFCS wascloser to 2:1.

A surrogate measurement to indicate com syrup used was dissolvedorganic carbon. Because there was very little organic matter in theWiggins well water, DOC was expected to correlate closely with the massof com syrup. Laboratory analyses indicated that the carbon content ofHFCS was 0.36 g-DOC/ml-HFCS, similar to what would be expected for ahexose mixture. Use of DOC to indicate whether all the HFCS had beenconsumed in the Biotowers was more problematic. The specificcomposition of the Biotower effluent DOC could not be determined, withrespect to HFCS, fermentation products or other soluble microbialproducts released from the biofilm. Thus in Figure 8, the influent DOClevel is probably an accurate reflection of HFCS addition to the influent.However, the DOC for the well water is probably not hexose, but rathernatural organic matter (NOM) sloughed from the soil in the aquifer and/orwell casing.

24

•60

50 -

40 -

OO)

OoQ

30 4-

20 -

10 --

o Well Water 4-MFCS

• Well Water

0

1-Apr 2-May 2-Jun 3-Jul 3-Aug 3-SepDate

4-Oct 4-Nov

Figure 8. DOC concentration of Wiggins well water and system influentafter HFCS addition from April 15 to October 31, 1997. Lines are 14-daymoving averages.

99

Key Points:

1. Influent DOC concentration from well before HFCS addition wasrelatively consistent at approximately 2.5 mg-C/L This is not surprisingconsidering it is a groundwater source, where low variability in waterquality is to be expected.

99999999

System influent DOC concentration had a relatively large variability.This variability is most prominent in April and May due to HFCSdosing problems including pump clogging and HFCS crystallization.Influent DOC variability decreased dramatically after the installationof a new HFCS dosing pump on July 21.

The trend in the 7-day moving average for system influent DOCfrom April to July was decreasing influent DOC concentrations. Thiswas done because we were concerned that too much carbon wasbeing added, resulting in occasional sulfide odors, not in the water

25

*•^ itself, but in the off gas from the Biotower. Over-addition of carbon9 poses a nuisance risk in the Biotowers. An excess of corn syrupf combined with high sulfate concentrations can lead to enrichment_ for sulfate reducing bacteria (SRB). As a precaution, carbon was• never added in high enough concentration to completely destroy• nitrate. A low nitrate residual prevents a population of SRB fromf establishing. However, by August 1997, the C:N ratio had beenA reduced too severely, limiting denitrification, as low as 1.2:1. After

that, the HFCS dose was gradually increased back to 2:1.

•9 4. For comparison, average well water and system influent DOCg concentrations were calculated. The following table summarizes the^ results:

•^ Table 9. Average DOC concentration values for Wiggins well water• and after HFCS addition (system influent) from April 15 to Octoberf 31,1997. Data are mean value ± one standard deviation

ftw Soluble organic matter• (mg-DOC/L)

•f Well Water 2.3 ± 0.80

9 System Influent 34.1 ±7.9ft after HFCS Addition

ft

•9 5. Statistical analysis indicated that Wiggins well water data were£ normally distributed whereas the Biotower influent DOC data was£ not normally distributed (a = 0.05). Therefore a Mann-Whitney rank

Sum test was used to compare median DOC values. Notft surprisingly, results indicated that there was a statistical differenceft between Wiggins well water DOC and Biotower influent DOC (a =

0.05).

6. The average amount of HFCS added was approximately 32 mg-C/Lduring 7 months of operation from April 15, 1997 to Oct 31, 1997.

§

26

9ft

60

50 -

40 -•

oen,§ 30 -fooo

20 -•

10 --

o BioTower Influent

• BioTower Effluent

1-Apr 2-May 2-Jun 3-Jul 3-Aug

Date

3-Sep 4-Oct 4-Nov

Figure 9. DOC concentration of Biotower influent and Biotower effluent fromApril 15,1997toOct31,1997. Lines are 14-day moving averages.

Key Points:

1. As shown in Figure 9, Biotower effluent DOC concentration "mimics"the Biotower influent DOC concentration, i.e. as influent DOCdecreases so does effluent DOC and vice versa for increasing influentDOC concentration.

2. For comparison purposes, average Biotower influent and effluent DOCconcentrations are summarized in Table 10.

Table 10. Biotower influent and effluent DOC from Apr. 15 toOct. 31, 1997. Data are mean ± one standard deviation.

Water Source

Biotower Influent

Biotower Effluent

Soluble organic matter(mg-DOC/L)

34.1 ±7.9

7.7 ±3.5

27

3. Statistical analysis indicated that Biotower effluent DOC values werenormally distributed whereas DOC values for Biotower influent werenot normally distributed (a = 0.05). Therefore, a Mann-Whitney rankSum test was used to compare median values. Results indicated thatthere was a statistically significant difference between Biotower influentand effluent DOC concentrations (a = 0.05).

4. The relatively large variation of average values for both Biotowerinfluent and effluent DOC concentrations can be somewhat misleadingbecause MFCS was intentionally decreased (April - July) thenincreased (August - October) during the demonstration which wouldhave increased the variance in influent DOC. Also, the DOC measuredin the Biotower effluent is complex, consisting of soluble microbialproducts and compounds originating from the biofilm matrix. Probablyalmost all the HFCS DOC was highly biodegradable hexose which wasconsumed. So the effluent DOC does not represent excess HFSC, butwas organic matter that must be removed in the downstream filterpolishing system. The average DOC net removal between theBiotower influent and effluent was 26.4 ± 6.2 mg/L. However, thedifference between influent and effluent DOC concentrations is not areliable estimate of HFCS used in denitrification.

5. As shown in Figure 9, effluent DOC increased when influent DOC(HFCS) increased. However, during this same period (August -November 1997) nitrate removal decreased, as shown in Figure 5.Apparently, the increased DOC was moving through the Biotowerswithout being used for denitrification. This may have been due to flowchannelization accompanying decreased hydraulic retention time in theBiotowers, as shown in Figure 3.

Roughing Filter

Removal of soluble and colloidal organic carbon by-products from thedenitrifying Biotowers was an important function of the roughing filterduring development and pilot testing of the denitrification process. Theroughing filter provided a reliable buffer between the Biotowers and theslow sand filter, reducing DOC from 6 - 8 mg/L in the Biotower effluent to 3-4 mg/L in the slow sand filter influent reservoir. On average an additional1 mg/L DOC was removed in the slow sand filter (Cook eta!., 1991). Theresults at Wiggins, shown in Figure 10, were somewhat different. Onaverage the DOC removal in the roughing filter during operation from Aprilthrough October 1997 was 2.2 + 1.9 mg/L.

28

20

18 -

16 -

14 -

12 -

OJ£10-1-og f

6 -•

0 -1

o Roughing Filter Influent

• Roughing Filter Effluent

1-Apr 2-May 2-Jun 3-Ju! 3-Aug

Date

3-Sep 4-Oct 4-Nov

Figure 10. DOC concentration of roughing filter influent (Biotower effluent) androughing filter effluent from April 15,1997 to Oct31,1997. Lines are 14-daymoving averages.

Key Points:

1. DOC data for the roughing filter are summarized for the seven monthsof operation from April through October 1997 in Table 11.

Table 11. Roughing filter influent and effluent DOC and DOC removal.Data are mean ± one standard deviation.

DOC (mg/L)

Roughing filter influent

Roughing Filter Effluent

DOC Removal

7.7 ±3.5

5.5 + 2.0

2.2 + 1.9

29

c

2. DOC removal in the roughing filter was highly variable. DOC removalduring the first 31/2 months appears to be less than the DOC removalduring the last 31/2 months on average. This difference, however, wasnot statistically significant (a = 0.05)

3. The variance in the data is quite large for each measurement. Thislarge variance makes it nearly impossible to draw any conclusions tothe effectiveness of the roughing filter for DOC removal during thedemonstration. However an F-test of variance for the roughing filterinfluent and effluent DOC showed that the variance in the influent DOCwas significantly higher than the effluent (a = 0.05). The low variabilityin the roughing filter DOC suggests that this process did significantlyimprove the consistency of the water quality sent to the slow sand filter,with respect to organic carbon composition, probably improving theperformance of the slow sand filter. This is consistent with observationsin earlier pilot testing.

4. During September and October, the organic carbon influent to theroughing filter increased. So much so that clogging of the media wasobserved, accompanied by flooding of the filter media. The roughingfilter media was cleaned twice during this period to maintainperformance. Excess biomass in the filter probably accounted for theincreased DOC removal observed during this time, compared withlower DOC removal in April.

Slow Sand Filter

Significant DOC was removed in the slow sand filter, as shown inTable 12 and Figure 11.

Table 12. Slow sand filter influent and effluent DOC and DOCremoval during April through October 1997. Date are average values± one standard deviation.

DOC Concentration(mg/L)

SSF Influent 5.5+2.0

SSF Effluent 3.1 ±0.8

DOC Removal 2.2 + 2.1

• 30

e

10

9 --

8 -

7 --

3- 6 4oen

o§ 44

•3 _.

2 -•

1

0

1-Apr

Slow Sand Filter Influent

Slow Sand Filter Effluent

2-May 2-Jun 3-Jul 3-Aug 3-Sep 4-Oct 4-Nov

Date

Figure 11. DOC concentration of slow sand filter influent (roughing filtereffluent) and slow sand filter effluent from April through October 1997. Linesare 14-day moving averages.

Key Points:

•••tftft

Statistical analysis indicated that both slow sand filter influent andeffluent DOC data sets were not normally distributed (a = 0.05). AMann-Whitney Rank Sum Test was used to compare median values.Results indicated that there was a statistically significant differencebetween the median DOC value for the influent water to the slow sandfilter and the median DOC value for slow sand filter effluent (a = 0.05).

The average removal of 2.2 mg-C/L is similar to the observed DOCremoval within the roughing filter.

As discussed above, the DOC concentration of the slow sand filterinfluent (roughing filter effluent) was quite variable: standard error =36%. However the variability in slow sand filter effluent DOC wassignificantly lower as determined by an F-test (a = 0.05).

31

The effluent DOC from the denitrification system is compared with the DOC inWiggins well water in Figure 12 and Table 13.

10

9 -•

oO)

o5 +

4 4

1 - -

0 J

1-Apr

••: YV^

o Well Water

• System Effluent

2-May 2-Jun 3-Jul 3-Aug 3-Sep

Date

4-Oct 4-Nov

Figure 12. Comparison of DOC concentration of system effluent (slow sand filtereffluent) and Wiggins well water from April through October 1997. Lines are 14-daymoving averages.

Table 13. System contribution of DOC during denitrification. Data for wellwater, system effluent and DOC addition are averages ± one standarddeviation.

DOC Concentration

Wiggins Well Water

System Effluent

DOC Added to Well Water

2.3 ±0.8

3.1 ±0.8

0.9 + 0.9

Key Points:

1. On average, the difference between Wiggins well water DOCconcentration and DOC in the system effluent was relatively low: 0.9

32

mg/L. Statistical analysis indicated that both data sets were normally• distributed and that the difference between mean DOC values wereft statistically significant (a = 0.05).

9 2. Note that the standard deviation of both Wiggins well water and• system effluent DOC values are the same, indicating acceptableft consistency in the denitrified and polished product water.

3. The DOC in the finished water did increase after denitrification,• compared with the well water. This may have been due to the difficultyft in controlling the carbon dose using MFCS. At the pilot Biotower^ operation in Brighton, Colorado, where acetate was used as the• carbon-energy substrate, the DOC of the effluent water was not9 significantly different from the influent well water (Cook eta!., 1991).

•J Nitrite (NO2')ft Nitrite (NO2~) is an intermediate in the denitrification reaction, and a9 number of factors has been associated with nitrite formation, particularlyft insufficient carbon (Silverstein and Oh, 1998, Oh and Silverstein, 1999). Inft drinking water denitrification, nitrite will eventually be re-oxidized to nitrate

during chlorination, increasing chlorine demand and reducing overall• system performance. Nitrite production can probably be minimized by• proper operation of the Biotower process, as was observed during theft Wiggins demonstration. The Biotower effluent nitrite profile for operation at^ 38 Ipm and 20 mg/L NO3-N is shown in Figure 12. In general very little

nitrite remained in the Biotower effluent when the HFCS was dosed9 adequately to the influent water. High nitrite values in early June and inft July coincided with failures of the HFCS dosing pump, as suggested by£ the low influent DOC values in Figure 7. After a new pump was installed

on July 21 , the nitrite levels were consistently low, less than 1 mg/L NO2-9 N. Average nitrite concentrations throughout the system are shown in9 Figure 13; system nitrite statistical data are given in Table 14.

•ftTable 14. Biotower 2 effluent nitrite levels before and after installation of

9 the new HFCS dosing pump.9ft Effluent NO2-N May 14 - July 23 July 23 - Oct. 30

ftw Average (mg/L) 2,0 1.49ft Standard Deviation (mg/L) 2.3 1.4

ft_ Number of samples 26 36

33

1-Apr 2-May 2-Jun 3-Jul 3-Aug 3-Sep

Date4-Oct 4-Nov

Figure 13. Biotower effluent nitrite concentration from May through October 1997.Line is a 14-day moving average.

Key Points:

1. Wiggins well water had no nitrite present. During the period of April toNovember 1997, the Biotower effluent nitrite concentration variedsignificantly, ranging from 0.2 mg/L to 6.0 mg/L NO2-N.

2. Incidents of high nitrite concentration in the Biotower effluent diddecrease after the installation of a new MFCS dosing pump on July21, 1997.

3. From May 14 to July 23, effluent nitrite from the Biotower exceeded1 mg/L NO2-N in 58% of the 26 samples. After July 23, Biotowereffluent nitrite exceeded 1 mg/L NO2-N in 47% of the 36 samples.

34

O

3.50 i

3.00 -

2.50 -

2.00 -

Jl 1.50 -£! 1.00-z

0.50 -

0.00

All Data m Data After New Pump

Biotower 1 Biotower 2 Roughing Slow SandFilter Filter

Figure 14. Comparison of average effluent nitrite concentration values afterBiotower and filter processes for entire data collection period (May 14 - Oct.30, 1997) and period after installation of more reliable HFCS dosing pump(July 23 - Oct. 30, 1997). Error bars are ± one standard deviation.

Key Points:

1. A two-tailed t-test comparing the effluent nitrite mean values beforeand after control of carbon dosing indicated that effluent nitrite diddecrease although not at the 0.05-level of significant (a = 0.09). Inaddition, an F-test of variances in mean nitrite concentrations for thetwo periods showed that the variability of the Biotower effluent nitritedecreased significantly after installation of the new carbon pump,controlling HFCS dosing.

ftftftftftftftftftft

35

Dissolved Oxygen (DO)

Dissolved oxygen monitoring proved to be useful for interpretingperformance of the Biotowers and the roughing filter particularly. Also,because anoxic water is considered undesirable, evaluation of systemeffluent dissolved oxygen provides insights into one overall effect of thedenitrification processes on finished water quality.

Biotowers

In general, denitrification is suppressed in the presence of dissolvedoxygen. However, in a thick biofilm such as the biomass present in theBiotowers, transport of dissolved oxygen is slow enough to insure thepresence of anoxic regions in spite of the presence of measurabledissolved oxygen in the bulk liquid. Both in lab and pilot experiments, itwas observed that denitrification was obtained with influent dissolvedoxygen levels as high as 5 mg/L (Cook et al., 1991; Hogrewe, 1990). Thestrategy employed during the Wiggins operation was to add enough MFCSto allow for aerobic uptake of substrate while consuming the averageinfluent dissolved oxygen, at a C:DO ratio of 1:1. The average well waterdissolved oxygen concentration was 3.3 mg/L, but was highly variable withwell water DO levels frequently as high as 5 mg/L after the pressurizedequalization tank upstream of the denitrification system. Throughout theApril - November 1997 operation, the Biotower effluent dissolved oxygenlevel averaged 0.6 mg/L with very low variability. The standard deviationfor that period was 0.2 mg/L, almost the detection level of the DO meter (±0.1 mg/L). The variability of the influent dissolved oxygen compared withconsistently low levels in the Biotower effluent is shown in Figure 15.

36

10

9 --

£ 6-fG)o§ 5O

a) 4en>*xO 3•o0)> 2o

o Hotowsr Influent

t Biotcwsr Effluent

•*\ ****** -*t T^W^W^V .

1-fvfey 2-Jul 2-Aug

Date

2-Sep 3-Ctt 3-Ncv

Figure 15. Dissolved Oxygen levels in system influent water and Biotowereffluent from May to November 1997. Lines are 14-day moving averages.

Key Points:

Dissolved oxygen concentrations in the influent water variedsignificantly, ranging from 1.4 to 6.1 mg-O2/L This large variabilityis due to the chlorine contact tank used at Wiggins that includes anair reservoir under pressure. Depending on pumping of main well,the contact time between the water and the pressurized air-blanketvaried from a few minutes to several hours, resulting in differentdissolved oxygen concentrations.

Dissolved oxygen concentrations in the effluent water was veryconstant with an average concentration of 0.6 mg/L± 0.2 mg/L DO.

37

CD

E

3.5

3.0 -

2.5 -

f;2.(Hx0 1.5 H0

•| 1.0 HCOCO

b °-5

0.0

Biotower 1

Biotower 2

30-Apr 19-Jun 8-Aug 27-Sep 16-Nov

Figure 16. Effluent dissolved oxygen from each biotower: 1 = first in series;2 - second in series, from May 14 - Oct. 30, 1997. Trend lines are 14-daymoving averages.

Key Points:

1. It is suggestive that the rise in effluent dissolved oxygen fromBiotower 1 coincides almost exactly with the decrease indenitrification in Biotower 1 shown in Figure 7. Like the trend toincreasing effluent DOC (Figure 9), the increasing DO in theBiotower 1 effluent may be evidence of increased channelization inthe clogged biofilm reactor.

Roughing Filter

The denitrified effluent from the Biotowers is distributed in a thin film overthe roughing filter packing media, where the anoxic water is quicklyoxygenated. Figure 17 has dissolved oxygen profiles of roughing filterinfluent and effluent water from May to November 1997.

38

en

c©O)

XOT3ID

~OCOCO

b

12

10 -

4 -

2 -

0

Influent

Effluent Media Washed

30-Apr 19-Jun 8-Aug 27-Sep 1 G-Nov

Figure 17. Roughing filter influent and roughing filter effluent dissolvedoxygen concentrations from May 14, 1997 to October 31,1997.

Key Points:

Dissolved oxygen concentration in the roughing filter influentaveraged approximately 0.6 mg-O2/L and had a very low variability.

Dissolved oxygen in the roughing filter effluent was consistentlygreater than 7 mg/Lfrom May 14, 1997 to August 1, 1997,indicating that oxygen transfer to the thin liquid film was veryefficient. Roughing filter effluent DO began declining significantly inAugust reaching 2.7 mg/L August 29. This decrease was probablythe direct indication of severe disruption of thin film flow. In fact"ponding" and overflow of influent water was observed that day.The roughing filter was unpacked and the biomass was manuallywashed off the media on September 1, 1997. After cleaning, theeffluent dissolved oxygen rebounded to a value of 8.0 mg/L.However, dissolved oxygen began to decline again quickly to 3.4mg/L less than a month later. The media within the roughing filter

39

was removed once again and washed on September 27. Thedissolved oxygen concentration rebounded again this time to avalue of 8.2 mg/L, but again decreased steadily to a value 2.6 mg/Lin a month. As before, after media washing on Oct. 26, dissolvedoxygen in the roughing filter increased to saturation levels again.Clogging of the roughing filter is consistent with increased DOC inthe roughing filter influent during Aug. - Oct. as shown in Figure 9.

Slow Sand Filter

Dissolved oxygen was consumed in the slow sand filter, as can beseen in the influent and effluent profiles in Figure 18.

10

9

8-t

c 7tnD)

x" 6O

CD 5

"o xco 4CO

b3-:

2v

1 •;

Roughing Filter MediaWash Scoured

Roughing Filter

-e-SlowSand Filter

• Slow Sand Filter

1-Jun 2-Jul 2-Date

2- 3-Oct 3-Nov

Figure 18. Slow sand filter reservoir and slow sand filter effluent dissolvedoxygen concentrations from May 14 to October 31, 1997. Slow sand filtereffluent line is the 14-day moving average of DO sample measurements.

40

Key Points:

1. Dissolved oxygen concentration in the slow sand filter effluentaveraged 3.75 mg/L and had a low variability - standard deviationwas 0.4 mg/L DO. Effluent dissolved oxygen was not dependent onbed scraping. The sand bed was scraped on July 23, August 29,and October 30, 1997. When the roughing filter was performing wellas a thin film reactor and the effluent dissolved oxygenconcentration was over 7 mg/L, over 4 mg/L DO was removed inthe slow sand filter. This is consistent with DOC removal of over 2mg/L in the slow sand filter.

Finished Water DO

The dissolved oxygen profiles in the Town of Wiggins water supplywells and the effluent from the slow sand filter are compared in figure19. Statistical data are given in Table 15.

10

9

8

7

6

5

4

3

2

1

o Wiggins Well Water

• System Effluent

5/1 6/1 7/2 8/2

Date

9/2 10/3 11/3

Figure 19. Wiggins well water and system effluent dissolved oxygenconcentration from May 14, 1997 to October 31, 1997. Lines are 14-daymoving averages.

41

*

— Key Points:

•9 1 . The "well" DO concentration actually was measured after an air-9 pressurized equalization tank and therefore varies greatly dependingA on the distribution system demand. However, the dissolved oxygen

concentration in the system (slow sand filter) effluent was fairly stable,9 probably due to stable reoxygenation of water in the roughing filter and£ consistent oxygen demand in the slow sand filter.

•f Table 15. Well water and system (slow sand filter) effluent

dissolved oxygen from May 14 to Oct. 31 , 1997. Data are mean ±* one standard deviation.•A Dissolved Oxygen

Well Water 3.3 ±1.5

System Effluent 3.75 ± 0.4

Interestingly the average system influent and effluent oxygenconcentrations were similar. Statistical analysis indicated that bothdata sets were not normally distributed. Thus, a Mann-Whitney rankSum Test was performed on the data to compare median values.Results indicated that the median DO value for the system effluentDO was significantly higher than the median DO value for Wigginswell water. Since some dissolved oxygen is desirable, thedenitrification system also improved the well water quality.

PH

Overall, the biological denitrification process and following filtrationprocesses did not have a strong effect on water pH, a very beneficialresult. The alkalinity of the well water averaged 230 mg/L as CaCO3,indicating that there was some acid buffering capacity in the system.Denitrification actually adds alkalinity to the water. However CO2 isalso generated during oxidation of the organic carbon whichcontributes acidity to the water. The pH of the water in the Biotowersappeared to be dominated by COa that would remain in solution in theanoxic closed environment. However, as soon as the water reachedthe roughing filter, where supersaturated CO2 would be stripped in thethin film reactor, the pH rose to reflect the alkalinity addition from

42

denitrification. Overall, the change was very small, as is shown in thefollowing results.

Biotowers

Well water and Biotower effluent pH profiles are compared in Figure20, with statistics shown in Table 16.

7,8 --

7.6

7.4 +

7.2 -•

7 • •

6.8 -;

6,6 -•

6.4-;

6.2 -:

6

1-Apr

• Wiggins Well Water

o BioTower Effluent

2-May 2-Jun 3-Jul 3-Aug

Date

3-Sep 4-Oct 4-Nov

Figure 20. Wiggins well water and Biotower effluent pH from April 15 to October31,1997. Trend lines are 14-day moving averages.

Key Points:

1. The well water had a very stable pH averaging approximately 7.3with a low variability.

43

9 2. The Biotower effluent pH decreased to 7.1, probably reflecting9 supersaturation with biologically-produced COa- The Biotowerf effluent pH also had a low variability.

9 Table 16. pH statistics for Wiggins well water and Biotower effluent• from April 15 to October 31, 1997. Data are mean ± one standardf deviation.

I &• Well Water 7.26 ± 0.05'

^ Biotower Effluent 7,06 ± 0.6

9 3. Statistical analysis of data indicated that the variances between the9 data were different. Therefore, a Mann-Whitney Rank Sum Testf was used to compare the median pH values for both data sets.^ Results indicated that there was a statistically significant difference* between median pH values. Considering only the nitrate reduction9 reaction, pH and alkalinity both increase during denitrification.f However, carbon dioxide also is formed during heterotrophicf denitrification. In a system open to the atmosphere, this CO2 will be

off-gassed. However in the closed slightly pressurized Biotowers,9 the water is super-saturated with CO? formed during nitrate9 respiration, suppressing pH. The rise in pH during passage throughf the roughing filter shown below in Figure 21, supports the^ explanation of lower pH after Biotower denitrification due to* supersaturation of the water with CO2-

9 Roughing Filter

mJust as oxygen transfer into the anoxic Biotower effluent was achieved

9 rapidly in the roughing filter, CO2 was striped from the supersaturated9 air, as is shown in the pH profiles in Figure 21.

44

e

Roughing Filter influent

Roughing Filter Influent

9/3 10/4 11/4

Figure 21. Biotower effluent pH and roughing filter effluent pH from March 15 toOctober 31,1997. Roughing filter influent line is a 14-day moving average.

Key Points:

Values of pH in the roughing filter influent (Biotower effluent)averaged 7.06 with a standard deviation of 0.6.

From April 15 to July 15, the roughing filter effluent pH rangedbetween 7.4 and 7.7. pH then decreased slightly to approximately7.2 by the first week of August and remained steady until August29. Probably the decrease in effluent pH values was a result ofinterruption of thin film flow and decrease of CO2 stripping into theair. First there was visible clogging of the roughing filter culminatingin water spilling out the top of the reactor. Second, the pH decreasecoincided exactly with the dissolved oxygen decrease, both effectsof inhibited gas transfer. The media within the roughing filter wasremoved and the biomass was washed off on September 1, 1997.After repacking the roughing filter with cleaner media, the effluentpH rebounded to a value of 7.7. pH steadily declined to a value of7.1 on September 24, 1997. The media in the roughing filter wasremoved once again and washed on September 27, 1997. Valuesof pH rebounded again this time to a value of 7.7. Once again, pH

45

decreased steadily to a value of 7.05 on October 28, 1997. Themedia was washed again on October 29,1997 with pH valuesrebounding to a value of 7.8 on October 30, 1997. This trend wasidentical to the DO fluctuations during August 15 - October 31.

Slow Sand Filter

Slow sand filter pH profiles are given in Figure 22.

7.8 -:

7.6 - -

7.4 - :

7.2

7

6.8 -;

6.6 -:

6.4

6.2 4-

6 -*

Roughing FilterMedia Wash

—•— SSF Reservdr

• • ^ • •SSF Effluent

1-Apr 2-May 2-Jun 3-JuI 3-Aug 3-Sep 4-Oct 4-Nov

Date

Figure 22. Slow sand filter reservoir and slow sand filter effluent pHvalues from April 15 to October 31, 1997. Lines pass through all throughdata points.

Key Points:

2.

Values of pH in the slow sand filter effluent averaged approximately7.4 ± 0.09. The slow sand filter effluent pH had the samefluctuations as effluent pH from the roughing filter. Effluent pH wasnot dependent on bed scrapping. The sand bed was scraped onJuly 23, August 29, and October 30, as indicated in Figure 22.

The pH did not change significantly from the roughing filter effluentto the slow sand filter effluent. Even the pH variations resulting from

46

roughing filter clogging and washing were translated to the effluentwithout significant dampening.

Finished Water pH

The pH profiles in the Town of Wiggins water supply and the systemeffluent are presented in Figure 23, with statistical data in Table 17.

xn.

7.8 --

7.6 •-

7.4 -:

7.2 --

7 • •

6.8 ••

6.6 - •

6.4--

6.2 - -

• Wiggins Well Water

o System Effluent

1-Apr 2-May 2-Jun 3-Jul 3-Aug

Date

3-Sep 4-Oct 4-Nov

Figure 23. Wiggins well water and system effluent pH values from April 15 toOctober 31, 1997. Lines are 14-day moving averages.

.Table 17. Well water and system effluent average pH values from May14 to October 31, 1997. Data are mean values ± one standarddeviation.

Well Water

System Effluent

7.26 ± 0.05

7.40 ± 0.09

47

Key Points:

2.

The average system influent and effluent pH values were similar,7.26 and 7.4 for the well water and system effluent, respectively.However, statistical analysis indicated that the small differencebetween the mean pH value for the system effluent and the wellwater was significant, probably due to the effect of denitrification.

There was not a significant difference between the variability of theaverage pH values of the well water and denitrified effluent.

48

Turbidity

Based on experience with earlier pilot testing of the packed tower denitrificationprocess, we expected water turbidity to rise after denitrification and then to bereduced significantly during pre-filtration in the roughing filter and slow sandfiltration (Cooket al., 1991; Hogrewe, 1990). The up-flow packed bed Biotowerwas developed intentionally to minimize generation of particulate material duringoperation. The main purpose of the roughing filter was to reduce both organicand particulate loading to the slow sand filter. In general the turbidity addition andremoval in the demonstration processes at Wiggins functioned as expected, as isshown in the following figures and tables. The major difference between earlierpilot testing and the Wiggins demonstration was that the slow sand filter was thesignificant process for turbidity removal, especially attenuating turbidity spikesfrom the Biotowers. Average effluent turbidity from the slow sand filter over sevenmonths operation was 0.4 NTU with a standard deviation of 0.16 NTU - excellentperformance for any filter, and especially a slow sand filter. On the other hand,not as much turbidity removal was achieved in the roughing filter as wasanticipated, as will be discussed below. Turbidity data from discrete samplestaken regularly for the Biotowers, roughing filter and slow sand filter arepresented first in this section. Results of on-line measurement of slow sand filter(system) effluent turbidity are at the end.

Biotowers

Turbidity profiles for well water and effluent from the Biotowers are inTable 18 and Figure 24.

• Table 18. Well water and Biotower effluent turbidity values from April15 to October 31, 1997. Statistics are means ± one standarddeviation.

Turbidity (NTU)

Well Water 0.19 ±0.08

Biotower Effluent 2.52 ±1.13

49

5 --

4 - -

f-

24-

1 • •

• Well Water

o BloTower Effluent

1 -Apr 2-May 2-Jun 3-Jul 3-Aug 3-Sep 4-Oct

Date

4-Nov

Figure 24. Turbidity profiles of Wiggins well water and Biotower effluent fromApril 15 to October 22,1997. Lines are 14-day moving averages.

Key Points:

1. Influent turbidity of the well water, measured after the pressurizedequalization tank, was both low and very consistent: 0.19 ± 0.08NTU. This characteristic was not surprising given the groundwatersource - wells extracting water from a depth of 30 to 45 m.

2. Turbidity increased after denitrification in the Biotowers to 2.52 NTUand was quite variable, with a standard deviation of 1.52 NTU.Turbidity variation in the Biotower effluent appeared to be cyclicwith a periodicity of almost two months between high and lowvalues. The variations did not seem to correlate with either DOCloading, air scouring, or nitrate removal variation in the Biotowers.The highest turbidity values did occur in the summer months andmay reflect increased bacteria growth in the Biotowers when thewater temperature increased by as much as 2 °C.

50

Roughing Filter

Influent and effluent turbidity profiles for the roughing filter during theperiod from April 15 to October 31, 1997 are presented in Figure 25and Table 19.

5 --

4 --

2 --

1

o Roughing Filter Influent

• Roughing Filter Effluent

1 -Apr 2-May 2-Jun 3-Jul 3-Aug

Date

3-Sep 4-Oct 4-Nov

Figure 25. Turbidity of process water entering biological roughing filter andturbidity of effluent water from April 15 to October 22, 1997. Lines are 14-daymoving averages.

Key Points:

1. The variation of roughing filter effluent turbidity tracks the influentvariation almost perfectly, as can be seen in figure 25. This resultwas very different from the experience in pilot operation, when itwas found that the roughing filter almost completely attenuatedturbidity spikes from the Biotower that were as high as 10 NTU. Theroughing filter did not attenuate the fluctuations in influent turbidity.

51

2. As was the case for Biotower effluent turbidity, there was nocorrelation between DOC removal and turbidity reduction throughthe biological roughing filter.

Table 19. Roughing filter influent and effluent turbidity and turbidityremoval (A Turbidity) from April 15 to October 31, 1997. Data aremeans ± one standard deviation.

_ Turbidity (NTU)

Roughing Filter Influent 2.52 + 1.13*

Roughing Filter Effluent 1.67 + 0.80

-A Turbidity 0.86 + 0.80

3. Results indicate that the biological roughing filter on average0 removed 0.86 NTU units of turbidity. This represents an averagef turbidity reduction of 34%. However, statistical analysis (t-test)

indicated that there was not a significant difference between* roughing filter influent and effluent turbidity values (o=0.05)9 probably due to the large variance for both mean turbidity values.9 As has been stated above, the roughing filter was not effective in£ attenuating turbidity spikes from the Biotower effluent,

9 Slow Sand Filter

•f The slow sand filter was very efficient at removing turbidity throughout. operation, during variation of influent turbidity from 1 to 3 NTU. Table^ 20 and Figure 26 show turbidity results from April 15 to October 31,• 1997.

*f -Table 20. Slow sand filter influent and effluent average turbidity valuesf from April 29 to October 31 , 1 997. Data are means ± one standard

deviation.99 _ Turbidity (NTU)

9 Slow Sand Filter Influent 1.63 ± 0.7599 Slow sand Filter Effluent 0.40 + 0.16•

A Turbidity 1.25 ±0.67

52

5 --

2- 3 - -

2--

o Slow Sand Filter Influent

• Slow Sand Filter Effluent

1.0 NTU Standard

O / 00

o o"

01-Apr 2-May 2-Jun 3-Jul 3-Aug 3-Sep 4-Oct 4-Nov

Date

Figure 26. Turbidity of influent and effluent slow sand filter process waterturbidity from April 29 to October 22, 1997. Lines are 14-day moving averages.

Key Points:

2.

It is quite evident from the graph that the slow sand filter producedlow turbidity water and was very reliable. The effluent from the slowsand filter never exceeded the 1 .0 NTU standard and was less than0.5 NTU for the majority of the filter run. In fact the average effluentturbidity was 0.4 NTU with a standard deviation of 0.16 NTU.

The slow sand filter was able to attenuate the large fluctuations ininfluent turbidity ranging from 1 .0 NTU to well over 5.0 NTU.

3. Results indicate that the slow sand filter on average removed 1.25NTU units of turbidity. Statistical analysis indicated that thisremoval was significant (o=0.05), approximately an averageturbidity reduction of 77%.

53

4. When compared to results from the roughing filter, the slow sandfilter removed approximately 50% of the effluent turbidity from theBiotower, whereas the roughing filter removed 34%. The totalturbidity removal in the filtration polishing process wasapproximately 84% (2.5 to 0.4 NTU).

Finished Water Turbidity

Although significant turbidity, on average over 2.5 NTU, was addedduring denitrification through the dense biofilm in the Biotowerreactors, the denitrified water was polished very effectively. During theseven months of operation at 38 Ipm, the slow sand filter effluent neverexceeded 1 NTU, with 90% of the 68 samples less than 0.5 NTU. Wellwater and denitrification system effluent turbidity data are comparedbelow in Table21 and Figure 27. And the turbidity profile from the wellthrough the denitrification Biotower-roughing filter-slow sand filtersystem is shown in Figure 28.

1.8 --

1.6 - -

1.4 - -

1.2 - -

• Well Water

o System Effluent

1.0 NTU Standard

0.8 --

0.6 - -

0.4 --

0.2 - •

0

1-Apr 2-May 2-Jun 3-Ju| 3-Aug 3-Sep 4-Oct 4-Nov

Date

Figure 27. Turbidity of system effluent (slow sand filter effluent) and Wigginswell water from April 29 to October 22, 1997, Lines are 14-day movingaverages.

54

Table 21. Average turbidity values for Wiggins well water, systemeffluent and turbidity increase resulting from treatment (+A Turbidity)from April 29 to October 31, 1997.

Turbidity (NTU)

Well Water

System Effluent

+A Turbidity

0.20 ± 0.08

0.40 ±0.16

0.19 + 0.19

^ .*N

^V^^

<$&

^

&

^

o^

-^

*°"

Figure 28. Turbidity profile of denitrification system from well water througheffluent from each process. Bars are averages of data from April 29 toOctober 22,1997. Error bars are ± one standard deviation.

Key Points:

1. On average, the net turbidity increase from well to product waterwas only 0.2 NTU. Statistical analysts using a t-test indicated thatthe increase was significant (a = 0.05).

55

Continuous Effluent Turbidity

On-line measurement of slow sand filter effluent turbidity began onJune 25, 1997 and continued through the end of the demonstrationOctober 22, 1997. The data from Figures 29 - 33 reinforce theconsistency in the discrete measurements of effluent turbidity.Furthermore, the slow sand filter ripened very quickly after scraping, sothat the effluent turbidity was less than 0.5 NTU in less than 24 hours.In real operations, only half (or less) of the filter would be scraped atanytime, but the rapid resumption of performance after scraping isfurther evidence of the reliability of the slow sand filter.

1.8 -;

1.6 - j

1.4 -

P 1.2 +• 1.0 NTU Standard

•= 12.a3 0.8 4-H

0.6 -;

0.4 -;

0.2 --

0

^

„ \- „ • - *XTime

Figure 29. Continuous effluent turbidity measurement in June 1997.

Key Points:

Turbidity never exceeded 1.0 NTU during the fraction of themonth monitored (6/25 - 6/30/97)

56

2.

3.5

The Biotower was not air-scoured and the slow sand filterwas not scraped during June.

3 --

2.5

2 --

1.5 --

•••

••

1 ---

0.5 - -

BioTower Air-Scour

1.0 NTU Standard

Purnp Failure - «

. .

Time

Figure 30. Continuous effluent turbidity measurement in July 1997.

Key Points:

1.

2.

3.

Gaps in on-line turbidity data due to power surges that shutdown on-line turbidity measurement and a computer datastorage fault.

Turbidity peak of 1 NTU on 7/10/97 occurred after normal airscour of the Biotower resulting in a turbidity spike of 8.3 NTUin the Biotower effluent. Clearly the slow sand filter was veryeffective at dampening the influent turbidity spike.

Peak effluent turbidity of 3 NTU occurred immediately afterscraping slow sand filter. However, after 3.5 hours, slowsand filter effluent turbidity was reduced to below 1 NTU,indicating rapid ripening of the sand bed.

57

D

Z_

'•DlaD

o -

4.5 -

4 -

3.5 -

3 -

2.5 -

2 -

1.5 -

1 -

0.5 -

0 -

.

BloTowerAir-Scour

-

1.0 NTU Standard"

*

•I••"s^

^-S i

Time

Figure 31. Continuous effluent turbidity measurement in August1997.

Key Points:

1. Gaps in on-line turbidity measurement were due to powerfailures.

2. Turbidity spike on 8/8/97 was probably an instrument failure.

58

H.3 -

4 -

3.5 -

3 -

2.5 -

2 -

1.5-

1 -

0.5 -

n .

Turbidity spike from large amount ofair-scoured biomassfrom roughing filter 'accidentally pumped Into slow sand fillerreservoir (1 to 2% solids in slurry)

1.0 NTU Standard

**AVfcJ) i .^.»initi««ftn'««KHiiii ,,MMtf *»-

vCP

^ \^- \^- A£> \^-

Time

Figure 32. Continuous effluent turbidity measurement in September1997.

Key Points:

Effluent turbidity throughout the month was less than 0.5NTU until operational error on 9/27/97.

On 9/27/97 scoured biomass from the cleaning of theroughing filter was accidentally pumped into the slow sandfilter reservoir. It was estimated that the solids concentrationof the suspension was 1% (10,000 mg/L). In spite of theextremely high influent solids loading, the peak effluentturbidity was only 4 NTU, and effluent water quality wasrestored to less than 1 NTU in four hours.

59

2

1.8 -

1.6 --

1.4 --

1.2- 1.0 NTU Standard

--. \ \,

X X ^Time

Figure 33. Continuous effluent turbidity measurement in October1997.

Key Points:

1. Except for 2 one-hour periods, effluent turbidity in Octoberwas less than 0.5 NTU.

2. Slow sand filter bed was scraped on October 29. By October31, effluent turbidity was consistently less than 0.3 NTU.

60

Bacterial Water Quality

Coliform Bacteria

Well water and effluent from Biotower 2, the roughing filter and theslow sand filter were sampled monthly from June through October1997 for enumeration of total coliform bacteria by the multiple tubefermentation technique that gave most probable number estimates(MPN). A total of six system profiles for coliform bacteria were made.In confirmed tests made at the same time, fecal coliform bacteria (E.coll) were never detected at any point in the system. Effluent totalcoliform MPN values were quite high between June and August -averaging over 105 MPN/100 ml. Pre-chlorination of the roughing filtersurge tank was begun on August 29, 1997 to reduce the high numberof total coliform bacteria. Chlorine (NaOCl) was dosed into theroughing filter effluent at a concentration of 1.5 mg/L CI2. After that,system effluent MPN values for total coliform bacteria were on theorder of 103 to 104. Results of total coliform tests before pre-chlorination began are presented in Figure 34, and those after pre-chlorination in Figure 35. Data are summarized in Table 22.

oo

oCD

CD

~oO"co•4— '

OH

1.E+08 y1.E+07 -1.E+06 -1.E+05 -1.E+04 -1.E+03 -1.E+02 --1.E+01 -1.E+00 --

T

KH\<y

&

Figure 34. Total coliform bacteria profiles through denitrificationsystem. Coliform bacteria were detected only once in the well water inthe four samples from June through August 1997. Data are averagesof the four samples. Error bars are + one standard deviation.

61

_ i .[_-rwu -

? 1.E+07 -~z. 1.E+06 -Q_ ,_

"~" -I p C\A

-J- 1 p_i_mQJ l.t + UO

S 1.E+02-m 1.E+01 -

"i F_i_nn

' , ", •, • / i*f,

•~> *p»-*-.• )"

. f ,

, •V;< „

Sv

oO"co"oI-

^ .0X <aN

Figure 35. Total coliform bacteria profiles through denitrification systemafter pre-chlorination began on August 29, 1997. Data are averages oftwo samples made Sept. 16 and Oct. 15. No coliform bacteria weredetected in well water in those two samples.

Table 22. Summary of Total Coliform bacteria MPN tests from Junethrough October 1997. Data are averages for sample period for eachsample point ± one standard deviation for June - August samples.

June -August(no ore-

WellWater

17.5*

BiotowerEffluent

MPN

5.1 (±7,2)xlO6

RoughingFilter Effluent/100ml

6:52 (±6.5)xlO5

Slow SandFilter Effluent

2.45 (±1.7)x105

chlorination)Sept. & Oct.(pre- BDLchlorination)Total coliform bacteria detected in only one sample: 70/100 ml

2.1 x107 1.6x10e 4,7x10'

62

Key Points:•A 1. The data indicate that total coliform bacteria numbers increase^ dramatically after water passes through the biological denitrification^ towers. This increase from well water to Biotower #2 effluent is9 statistically significant (o=0.05), increasing by 6-orders of9 magnitude.

• 2. Coliform bacteria were reduced on average by approximately 1 log9 in the roughing filter and by less than half a log in the slow sand• filter during June - August 1997. That is, a total of over one log9 removal was obtained in the two-step filtration system.

• 3. After pre-chlorination, removal of total coliform bacteria was stillw one log, but removal with the combination of pre-chlorination and9 slow sand filtration was another 1,5 logs, for a total of 2.5 logsg removal of total coliform bacteria in Sept. - Oct. 1997. Statistical

testing in a t~test indicated that total coliform in the effluent after• pre-chlorination were significantly fewer (a = 0.06).

•f 4. The effluent density of total coliform bacteria was much higher than^ expected compared with earlier pilot tests of the denitrification^ system. In those pilot tests, total coliform bacteria from the Biotower9 effluent were always on the order of 104 MPN/100 ml and from the• slow sand filter effluent, on the order of 103/100 ml (Cooket al.,f 1991). The most significant difference between the earlier pilot^ operation and the demonstration at Wiggins is the substitution of™ corn syrup for acetic acid. We suspected that the substrate9 comprised of sugars would support the growth of many non-9 denitrifying bacteria, including members of the coliform group. InA research recently completed at the University of Colorado, this

hypothesis has been verified. With use of acetate as the carbon9 substrate, the numbers of coliform bacteria are 2 - 3 logs lower than9 with MFCS. This will be treated in more detail in the discussionA section.

Aw 5. A presence/absence test for total coliform bacteria was performed• in the University of Colorado laboratories after chlorination with a^ dose of 4 mg/L C\ to the slow sand filter effluent. No coliform^ bacteria were detected even after seven days of incubation and

after chlorine residual had disappeared.

•• Heterotrophic Plate Count (HPC) Bacteria

• Five system profiles for HPC bacteria were made monthly between™ June and October 1997 using the R2A agar plate count method. There

63

was no significant reduction in HPC counts after pre-chlorination wasbegun, so data for all five sample profiles are shown in Figure 36 andare summarized in Table 23 as colony forming units (CFU)/100 ml.

1.00E+10

Figure 36. System bacteria profile based on average Heterotrophic PlateCount (HPC) results from five monthly samples, June through October 1997.Error bars are + one standard deviation.

Table 23. HPC system profile data for June through October 1997. Dataare means ± one standard deviation.

Well Water BiotowerEffluent

CPU

RoughingFilter Effluent7100 ml

Slow SandFilter Effluent

June-October

9.8 (±10.1)». H r\

6.6 (±7.7) 2.9 (±1.4)x10' x10'

1.7 (±2.7)x106

64

Key Points:

•A 1 . The data indicate, not surprisingly, that HPC values increase after« water passes through the biological denitrification towers. This™ increase of over three logs CFU/1 00 ml from the well water to9 Biotower #2 effluent is statistically significant (a=O.Q5).•£ 2. The data also indicates that HPC values decrease after the

roughing filter by approximately half a log CFU/1 00 ml, and^ decrease over one log through the slow sand filter. This pattern• was similar before and after pre-chlorination. Statistical analysis (T-f test) indicated that the difference in mean HPC values between• Biotower#2 effluent and roughing filter effluent were not significantly

different (a=0.05). However, statistical analysis did indicate that the9 mean HPC CFU/1 00 ml observed in the slow sand filter effluent9 was significantly lower than the mean HPC value in the roughing9 filter effluent (o=0.05).

£w 3. Average density of HPC (CFU/1 00 ml) in the slow sand filterw effluent was the similar to the average HPC values found during9 pilot testing of the denitrification process (Cook et al., 1991).f Possibly the similar results are explained by the fact that the HPC

density is proportional to the number of denitrifying bacteria in the^ system. If sufficient carbon substrate is provided, this number• should be dependent only on the nitrate consumed, which was thef same in the pilot tests as at the Wiggins plant. It is interesting that^ HPC density was not affected by the low dose of chlorine used in^ pre-chlorination.

9 4. As with coliform bacteria, the roughing filter plus slow sand filterA process sequence removed approximately 2.5 logs of HPC_ bacteria.

*

65

•

Chlorine Demand

One of the costs of the biological denitrification process is the addition ofdisinfectant-demanding compounds to the well water. Primarily these areparticulate and dissolved organic compounds (DOC), sulfides, organic nitrogen,and ammonia. The latter two can be minimized by optimal operation of thedenitrification process. Seven analyses for chlorine-demand comparing the wellwater at Wiggins with the denitrification system (slow sand filter) effluent weredone between July 9 and October 8, 1997. A 24-hour chlorine demand test wasused, which provides a very conservative estimate of chlorine demand since thecontact time in a distribution system is more typically on the order of severalhours. Even the chlorinated well water was found to exert a chlorine demandafter 24 hours. The results of the seven tests have been presented in tabularform to emphasize the variability of chlorine demand, particularly in thedenitrification system (slow sand filter effluent). Also, it was noticed that theremay have been a relation between system chlorine demand and the number ofdays since the Biotowers were air scoured. Chlorine demand data from theseven tests are given in Table 24 and average data over the period from July 9 toOctober 8, 1997 are compared in Table 25.

Table 24. 24-hour chlorine demand measurements from July 9 to October8, 1997. Except as noted, data are means ± one standard deviation.

Sample

Well WaterSystem EffluentWell WaterSystem EffluentWell WaterSystem EffluentWell WaterSystem EffluentWell WaterSystem EffluentWell WaterSystem EffluentWell WaterSystem Effluent

Sample date(Days sinceAir scour)

7/9(51)7/23(12)7/29(18)8/11(4)9/4(28)9/22

(18)10/8(7)

Dose range(mg/L CI2)0.9 - 3.50.9 - 3.50.9 - 4.70.9 - 4.70.8 • 3.80.8 - 3.81.9-9,21.9- 9.21.9- 9.11.9- 9.12.0 - 9.42.0- 9.41.7-15.21.7- 15.2

24-hourdemand

(mg/L CI2)1.6 ±0.531.73 ±0.671.6 + 0.53

n.a.10

3.732

0.47 ± 0.268.263

0.71+0.211.53 ±0.280.56 ± 0.25

>9.44

0.95 + 0.7411. 422

T sodium thiosulfate residual from influent quenched all samples2 only highest dose had chlorine residual (no s.d.)3 only two higher doses had chlorine residual (no s.d.)4 no chlorine residual in any dosed samples (no mean or s.d.)

66

* Table 25. Statistics for 24-hour chlorine demand tests over period July 9 to• October 8, 1997. Data are means ± one standard deviation.

A 24-hour Chlorine DemandStatistic Well Water* System Effluent

• Mean (mg/L CI2) 0.63 5.33

• Standard Deviation 0.5 4.35(mg/L CI2)

Number 7 5* chlorinated in Town water system pressurized equalization tank

Key Points:

1. Well water chlorine demand was similar for all 7 tests. Although thewater received a chlorine dose in the equalization tank, the 24-hour

W test indicated some long-term chlorine demand in the well water.£ Well water chlorine demand averaged 0.63 mg/L CI2 with aA standard deviation of 0.5 mg/L CI2-

•6 2. There were some problems associated with chlorine demand testsf for system effluent water. During Test #2, there was thiosulfateA residual in the effluent water, negating the results. During tests 3, 4,^ 5 and 6 residual was detected in only one or two of the dosed9 samples, reducing confidence in the results. No standard deviation£ values could be computed for the individual tests, makingA comparison with well water chlorine demand difficult.

^ 3. Average and standard deviation values computed from the• individual tests which had detectable residual for the system£ effluent in at least one sample dose, as well as for the well water^ samples, which had detectable chlorine residual in all doses for all^ tests. Analysis by a t-test showed that the 24-hour chlorine demand^ of the denitrification system effluent (5.33 + 4.35 mg/L) was9 significantly higher than the chlorinated well water (0.63 ± 0.5 mg/L)£ (a = 0.05), The variance of the system effluent mean value alsoA was significantly higher than that of the well water over the 5-monthA sampling period (a = 0.05).

• 4. Samples of the denitrification system effluent (slow sand filterf effluent) with the lowest 24-hour chlorine demand were those taken^ after the longest times had elapsed since air scouring of the

•• 67

Biotowers, at 28 and 51 days, with associated average 24-hourchlorine demand values of 1 .53 and 1 .73 mg/L Cla, respectively.These are both lower than the average 24-hour chlorine demand of5.33 mg/L Cl2. This observation is similar to findings from laboratoryexperiments at the University of Colorado in which chlorine demandalso decreased as time after air scour increased. Data from thatstudy revealed a maximum chlorine demand of 16.8 mg-Cl2/L threedays after air-scour to a minimum chlorine demand of 1 .6 mg-Cl2/Lthirty days after air-scour (Cook and Silverstein, 1 989).

Total Trihalomethane Formation Potential(TTHMFP)

9 Four independent monthly samples for total trihalomethane formationf potential (TTHMFP) were made on July 30, August 1 1 , September 4,

and September 22, 1997. Overall, the denitrification system had no™ effect either on any single species of TTHMFP compounds: chloroform• (CHCIg), dichlorobromoform (CHCI2Br), dibromochloroform (CHCIBr2),9 or bromoform (CHBr3) or on the total (TTHMFP). One TTHMFP test forA the system effluent (September 4, 1997) was not considered because• unusually high chlorine demand consumed chlorine before it could9 react in the TTHMFP test. Results are presented in Table 26 and9 Figure 37 below. The current maximum contaminant level (MCL) for£ TTHMFP in the Safe Drinking Water regulations which went into effect_ in 1998 is 80 jig/L; no individual species are regulated. Both the well™ water at Wiggins and the denitrification system effluent were below the• MCL

Table 26. Individual and total THMFP results of four monthly samples of wellwater and three of denitrification system effluent from July to October 1997.Summary data are means ± one standard deviation.

DateCHCI3(Ufl/L)

CHCl2Br(U9/L)

CHCIBr2

(US/L)CHBr3

(MS/UTTHMFP

(MS/L)

Well Water 21.7 ± 8.7 20.7 ± 5.4 23.1 ± 4.7 10.1 ± 4.7 75.6 ± 20.8

System 22.5 ± 9.9 17.9 ± 1.6 19.4 ± 2.2 8.7 ± 0.9 68.5 ± 8.4Effluent

68

e•••••••••

O)

•

C/3CD'o

CDQ.CO

XH

120

100 -

80 -

60 -

40 -

20 -

0

U Well Water

• Effluent

X?

Figure 37. System influent and effluent concentrations for individual THMspecies: chloroform (CHCIa), dichiorobromoform (CHCIzBr), dibromochloroform(CHClBr2) and bromoform (CHBr3) and for total THMFP (TTHMFP). Barsrepresent averages from four tests for well water and three tests for systemeffluent. Error bars are + one standard deviation.

Key Points:

Mean concentration values for each THM specie are similar forboth system influent and system effluent water. Statistical analysisusing a t-test indicated that there was no significant difference inTHM concentrations, for individual species or total, between wellwater and system effluent (a = 0.05).

The denitrification system had no significant effect on organicspecies that react with chlorine to form trihatomethane (THM)disinfection by-product compounds. This result was different fromresults during lab operation of the denitrification column, whichindicated a 40 - 50% reduction in THM precursor compounds (Cooket al., 1991). Other investigators also have found that biofilmrectors can remove from 20 to 40% of natural organic matter whichform disinfection by-products, through a combination of sorptionand biodegradation mechanisms. (Carlson and Silverstein, 1997).

69

Secondary Water Quality

Manganese

Almost from the beginning of the plant operation at Wiggins,accumulation of dark brown deposits on the aerobic roughing filter andon the surface of the slow sand filter bed were observed. The depositswere always associated with biofilm, either in the roughing filter reactorand effluent surge tank or the slow sand filter schmutzedecke. Thesedeposits were identified as manganese. In August 1996 water sampleswere analyzed for total manganese (Mn) concentration from the wellwater, after the equalization tank, the denitrified effluent from thebiotower and the slow sand filter effluent. The results of that singlesample support observations of manganese removal from water duringthe filtration process. Total manganese in the well water was 0.271mg/L; from the Biotower effluent, 0.30 mg/L and in the slow sand filtereffluent, 0.155 mg/L, suggesting that manganese was removed as thewater passed through the roughing filter and slow sand filter. This wasnot surprising. The roughing filter biofilm would be a good environmentfor manganese oxidation, as would the slow sand filter. Both werehighly aerobic and had low concentrations of degradable organicmatter, which would favor the growth of autotrophic manganese-oxidizing bacteria like Leptothrix sp. (Wheeler, 1998). Although nomonitoring of manganese in the well water was done after that singlesample in August 1996, on September 4, 1997 samples of biofilm fromthe roughing filter effluent surge tank and both halves of the slow sandfilter surface sand were collected and analyzed for manganesecontent. The results are shown in Table 27.

Table 27. Manganese content of biofilm and biofilm/sand solids in theroughing filter and slow sand filter, respectively.

Solid-phase Mn concentrationSample Source (mg-total Mn/kg-dry weight)

Roughing Filter Surge TankBiofilm 3,100

Slow Sand Filter Surface Sand(Compartment 1) 1,000

Slow Sand Filter Surface Sand(Compartment 2) 1,000

70

•

Key Points:

1. Manganese accumulated both in the roughing filter biofilm and slowsand filter sand/biofilm matrix at the surface of the sand beds. (Itwas also observed coating the roughing filter media and walls ofthe slow sand filter that were submerged during normal operation.)Accumulation in the roughing filter biosolids appeared to be greater.This is consistent with the role of manganese-oxidizing bacteria inremoval of reduced manganese (Mn2+) by sorption followed byoxidation and precipitation of MnO2 in the biofilm (Wheeler, 1998).

2. Clearly manganese is removed in the filtration step of thedenitrification process, since manganese precipitates accumulate atsolid surfaces, particularly where there is aerobic biofilm. However,since manganese was not monitored regularly, it is not possible tomake any quantitative conclusions about removal efficiency.

3. Presumably, dissolved iron would be removed as well by similarbiological and chemical mechanisms. At Wiggins, since the wellwater was chlorinated before being pumped into the denitrificationsystem, no soluble iron was detected at any point in the system.

Color and Odor

The use of the fermentable carbohydrate compounds in MFCS werecause for concern with respect to odor generation. Researchers havereported that a fermentation environment can result in production ofammonia as an end product in denitrification (Akunna, 1993). Therequirement for a higher carbon dose and C:N ratio for corn syrup thanfor the acetate used in earlier research raised concerns that a notinsignificant fraction of the HFCS might be the source of odoroussoluble fermentation products and even sulfides. Occasionally whenHFCS was dosed at high levels, weak sulfide and ammonia odorswere detected. On October 15, 1997, a sample of the slow sand filtereffluent was analyzed at a commercial laboratory for total odor number(TON) and color on the platinum-cobalt scale (Pt/Co). Color of thesystem effluent water was 5 Pt/Co and odor was quantified as 1 TON.

71

Air-Scour

Air scour for removal of excess biomass from the Biotowers wasproblematic throughout the Wiggins demonstration. Air scour isessential to maintain uniformly dispersed plug flow regime through theBiotowers and to insure that both nitrate and organic carbon aretransported efficiently to the biofilm denitrifying bacteria. In laboratoryand pilot research of the packed tower denitrification process, it wasfound that an air flow rate of 0.3 to 0.5 m3/min/m2 -Biotower cross-sectional area (1 - 1 .5 SCFM/ft2) was satisfactory to fluidize the slightlybuoyant Jaeger Tri-Packs packing media (S.G. = 0.96). There weretwo differences at the Wiggins plant. As was discussed in theIntroduction, a different media was used at Wiggins, and while thegeometric and material characteristics of the two media were verysimilar, the media in the Wiggins biotowers tended to interlock andresist fluidization. Second, we were unable to afford a compressor ofsufficient capacity to deliver the airflow used previously. In fact the airflow rate during scouring was less than 50% of the value used in earlyresearch. We mistakenly assumed that this would not be a significantproblem. However, as the results as discussed previously point out,there was increasing clogging and probably short-circuiting of flowthrough channels instead of into the biofilm. On the other hand, over-scouring of the denitrifying biomass also could cause problems. Wewere concerned that too much biomass might be lost possibly causinga long lag before resumption of complete denitrification. In order toinvestigate recovery of denitrification samples were collected everyhour after air scour from May to October 1 997. Denitrification in thefirst four to five hours immediately after air scour is compared withnitrate consumption before air scour in profiles of percent recovery ofdenitrification in Figure 38. Percent recovery was determined using thefollowing equation:

Percent Re cov ery = 1 00 (N0-NB S)

where: N0 = influent nitrate-nitrogen (mg-N/L); NAs = effluent nitrate-nitrogen at associated times after air-scour (mg-N/L); NBs = effluentnitrate-nitrogen on the last previous measurement before air-scour(mg-N/L). Other water quality effects of air scour were observed also,notably the Biotower effluent DOC and turbidity. Water quality data forthe five post-air scour monitoring are shown in Table 28. Turbidityprofiles during the first 240 to 360 minutes after air scour are shown inFigure 39.

72

coCD

O

"fa.Q

c.2"cdo

cCDU

CDCL

100

90 --

20 --

10- -

-•-Air-Scour #1

-*-Air-Scour #3

-*— Air-Scour #5

-Air-Scour #2

-Air-Scour #4

50 100 150 200 250

Time After Air-Scour

300 350 400

Figure 38. Percent recovery of pre-air scour denitrificationperformance during the six hours after air scour for five air scouroperations between May and the end of October 1997.

Table 28. Biotower denitrification recovery after air scour from May toOctober 1997. Recovery specified as achieving over 75% ofdenitrification measured just before air scour. Nitrate and DOC dataare means ± one standard deviation of hourly samples.

AirScourDate

5/19/97

7/11/97

8/7/97

9/4/97

10/1/97

EffluentNitrate

(mg-N/L)10.8±1.9

10.4 ±0.5

11.0 + 1.5

12.3 + 0.7

9.7 + 0.6

EffluentDOC

(mg/L)13.8 ±0.7

9.5 + 2.2

14.9 ±1.8

8.4 + 0.6

16.2 + 1.1

Days toRecovery

21

5

41

5

51

PercentRecovery

99%

92%

94%

85%

111%1Day of first regular sample after scour

73

5/19/97

7/11/97

8/7/97

9/4/97

10/1/96

0 100 200 300

Time after Air Scour (minutes)

400

Figure 39. Biotower effluent turbidity profiles during the first 240 to 360minutes after air scour from May to November 1997.

Key Points:

1. For all air-scour events except the first, similar nitrate removalrecoveries were observed. Average recovery for the four air-scourexperiments (July, August, September and October 1997) was 63.4% ± 10.0%. It was interesting that this level of recovery wasobserved as soon as the Biotower tank filled. There were nosignificant differences between effluent nitrate values from the timethat the Biotowers were refilled and data from four to six hourslater, as can be seen from the flat profiles in Figure 38.

2. When compared to results from the earlier pilot study at Brightonthat showed post-scour recoveries of 80% to 100%, the system atWiggins did not achieve the same performance. Possibly this is dueto the fact that air scouring was not very efficient at restoringuniform dispersed plug flow in the Biotowers.

74

3. With one exception (July 11) denitrification performance hadrecovered to over 90% of the denitrification measured just beforeair scour within 5 days. This is a conservative interpretation of thedata since for three of those four air scour events, regular datawere not collected before the recovery date. Resumption of fulldenitrification may actually have occurred sooner. In July, 85% ofprevious denitrification was achieved five days after air scour. Ittook 12 days to reach 99% of pre-scour performance.

4. MFCS consumption (measured as DOC) followed the denitrificationrecovery observations. There was proportionally less DOC removalduring recovery also.

5. As expected, effluent turbidity increased after air scour, butreduction in effluent turbidity to pre-scour levels was very rapid.Typically, the turbidity had reached a low level in less than twohours after air scour (Figure 39).

75

DISCUSSION

The results of the seven months operation of the drinking waterdenitrification system from April to November 1997 are discussed inthis section, in the context of the three objectives of the demonstrationin Wiggins, Colorado:

1. Investigate the effects of scaling up the biofilm denitrification andpolishing process based on laboratory and small-scale pilotresearch at the University of Colorado.

2. Comprehensive monitoring of physical, chemical and biologicalwater quality parameters to determine system performancereliability and anticipated effects on drinking water safety andaesthetic quality.

3. Investigation of the effects of process equipment and plantoperation on product water quality and system operability.

EFFECTS OF PROCESS SCALE-UP

Spatial scale concerns included reliability of parameters such asbiotower hydraulic loading rate, media surface loading rate, detentiontime and mass loading rate which had been associated withsatisfactory denitrification and filter polishing at the bench and smallpilot scale in predicting full-scale denitrification. Design and operationparameters at the Wiggins facility are compared with those for thesmall-scale pilot research reactors operated by the University ofColorado for the biotowers in Table 29 and filters in Table 30.

Key biotower column design and operations parameters which wereconsistent between the pilot plant and Wiggins demonstration were thehydraulic loading rate and empty bed contact time (EBCT), with valuesof approximately 3.5 m3/m2/d and 90 minutes, respectively. Columnpacking media characteristics also were similar, except for resistanceto fluidization, as was discussed earlier. Interestingly, the nitrate-nitrogen mass loading rates, normalized either for biotower volume ortotal media surface area, were 35 - 40% greater during the Wigginsdemonstration than at the Brighton pilot plant: 438 g-NO3-N/m /dcompared with 306 g-NO3-N/m3/d and 10.2 g-NO3-N/m2/d comparedwith 7.52 g-NO3-N/m2/d, respectively. Overall the performance of theWiggins demonstration was similar to that at Brighton, 8.4 versus 15.4mg/L NO3-N was destroyed, respectively, at similar hydraulic loadingrates and EBCT values. In both systems, the amount of denitrificationwas determined by the carbon addition rate, as intended. The

76

increased denitrification efficiency with respect to reactor volume andmedia surface area reflect the advantage of a larger-diameter biotowercolumn. In other words, for the same media height, more denitrificationis obtained in a larger-diameter column. This efficiency has benefits:specifically reducing the cost of pumping water through the up-flowcolumns. Since the biotowers operate in up-flow mode, distribution ofinfluent water in the biotower column has not been a problem.

Table 29. Comparison of process parameters characteristic of the biotowersduring the demonstration at Wiggins (1996-1997) and the earlier small-scale pilotbiotower operated in Brighton, Colorado (1989-1990).

Biotower System Characteristic*

Flow Rate RangeNominal Design Flow RateBiotower Height

Biotower DiameterBiotower System Empty Bed VolumeEmpty Bed Contact time (EBCT)Hydraulic Loading Rate RangeDesign Hydraulic Loading Rate (HLR)System Packed Media VolumeSystem Packed Media DepthPacking Media

Media Surface Area:Volume RatioMedia Void FractionMedia Specific GravityTotal Media Surface AreaNO3-N Mass Loading RateNO3-N Loading Rate/Total VolumeNO3-N Loading Rate/Media Surf. AreaMass Nitrate-Nitrogen VolumetricRemoval Rate (Based on BiotowerTotal Media Volume)

Brighton PilotPlant

0.5 - 4 Ipm1 Ipm5.2m

(single column)0.15m

0.094 md

94 minutes1.8-10m3/m2/hr

3.6 md/mz/hr0.085 m3

4.7mJaeger Tri-Packs™,

polypropylene,5-cm diam.,

spherical45 mz/ma

0.930.96

3.83 m2

28.8 g/d306 g/m3/d7.52 g/m2/d

0.142kg/m3/d

WigginsDemonstration

19-76 Ipm38 Ipm

5.4 m (two 2.7-mcolumns in series)

9.91 m3.2m3

84 min1.7-6.8m3/nrVhr

3.4 m'VnrVhr2.5m3

4.3mNor-Pac™,

polypropylene,3-cm diam.,cylindrical

43 m2/m3

0.950.96

lOT.Sm*1,094 g/d

438 g/m3/d10.2g/rrrVd

0.337 kg/m3/d

Characteristic values are for normal design operation, except where a range isgiven, indicating testing of the effect of varying that characteristic.

Denitrification kinetics were not investigated at the Wigginsdemonstration. The biotower system was sized using the half-order

77

kinetic model that had been verified during laboratory research at theUniversity of Colorado and pilot studies in Brighton, Colorado.

10.5 0.5 - k*(EBCT)

Where N = effluent NO3-N (mg/L), N0 = influent NO3-N (mg/L), EBCT =empty bed contact time (min), and k = the half-order constant, whichwas found to be between 0.03 and 0.05 (mg/L)°'5/min (Cook et al.,1989). A conservative value of k (0.03 (mg/L)a5/min) was used todesign the Wiggins biotower system. Even after clogging had occurred,shortening the EBCT by more than 50%, denitrification wassatisfactory, indicating that the half-order model produces reliablebiotower specifications.

Table 30. Comparison of process parameters characteristic of the roughing filterand slow sand filter during the demonstration at Wiggins (1996-1997) and theearlier small-scale pilot filters operated in Brighton, Colorado (1989-1990).

Filter Train Characteristic

Nominal Design Flow Rate

Brighton PilotPlant1 Ipm

WigginsDemonstration

38 IpmRoughing FilterHeightDiameterVolumePacking Media

Media Surface Area:Volume RatioMedia DepthMedia VolumeTotal Media Surface AreaHydraulic Loading RateDOC Loading Rate1

DOC Loading Rate/Media Volume1

DOC Loading Rate/Media Surf. Area1

1.2m0.15m0.1 8 md

Jaeger Tri-Packs,polypropylene,5-cm spherical

45 m2/m3

1.2m0.18mJ

8.1 m2

3.33 m3/m2/hr8.6 g-DOC/d

47.8 g-DOC/m3/d1.1 g-DOC/m2/d

2.1 m0.76m1.6m3

Nor-Pac,polypropylene,3-cm cylindrical

43 m2/m3

1.8 m1.4m3

60.2 m2

3.45 m3/m2/hr328 g-DOC/d

234 g-DOC/m3/d5.4 g-DOC/m2/d

Slow Sand FilterSurface AreaSand Bed DepthHydraulic Loading Rate

0.37 m2^1 m

0.003 m3/m2/min(0.08 gpm/ft2)

8.8m2

0.8 m0.004 m3/m2/min

(0.1 gpm/ft2)SanddioU = dio/d6o

0.85 mm1.53

1 mm1.47

1 Roughing filter DOC mass loading estimates based on average biotowereffluent DOC of 6 mg/L.

78

Performance of both filter polishing systems at the Brighton pilot plantand at the Wiggins demonstration were similar, as is noted in theResults section, when compared for removal of DOC, turbidity andbacteria. On a concentration basis, relatively more DOC was removedin the roughing filter at Brighton whereas at Wiggins, more DOC wasremoved in the slow sand filter, with the aggregate removal in the two-process sequence the same. As with the biotower denitrificationperformance, on a mass basis, normalized either for volumetric ormedia surface area loading, the larger-diameter roughing filter atWiggins has a higher DOC removal efficiency compared with theBrighton roughing filter. Scaled parameters for the roughing filter werehydraulic loading rate and the media surface area:volume ratio. Boththe sand characteristics and slow sand filter hydraulic loading rateswere consistent between Brighton and Wiggins. Effluent turbidity forboth systems was always less than 0.5 NTU; at Wiggins, the averageeffluent turbidity from April to November 1997 was 0.4 NTU.

Two things are apparent from the comparison of performance of thescaled-up process at the Wiggins demonstration with earlier pilot plantoperation. First, both the biological denitrification and filtrationprocesses will produce consistent denitrified drinking water over a fairlylarge range of mass loading rates for nitrate-nitrogen and DOC,provided hydraulic loading rates and detention times are maintained.Probably that is because the biofilm will grow, or decrease in massdepending on substrate and nitrate availability, and clogging andchannelization are prevented by sufficient air scouring.

DRINKING WATER QUALITY

The major effect of the denitrification and polishing processes on wellwater quality are reduction of nitrate and introduction of bacteria. Alsothe chlorine demand of the product water increased significantly overthat of the well water. Turbidity and organic carbon also increasedthrough the process, but both were well within drinking waterstandards. Table 31 has a summary comparison of the Town ofWiggins' well water quality and the slow sand filter effluent product(detailed results have been presented in the previous section).

79

Table 31. Comparison of quality of well water and denitrified and filtered productwater from the Wiggins demonstration, April to November 1997.

Constituent

NO3-N (mg/L)NO2-N (mg/L)DOC (mg/L)Dissolved Oxygen(mg/L)PHTurbidity (NTU)Chlorine Demand (mg/LCl)Total Coliform Bacteria1

(MPN/100ml)Total Coliform Bacteria2

(MPN/100ml)Fecal Coliform Bacteria(MPN/100 ml)Heterotrophic PlateCount(CFU/100ml)Total TrihaiomethaneFormation Potential(ua/L)Color (Pt/Co)Odor (TON)Manganese (mg/L)

Wiggins Well Water

19.6 + 2.4*BDL

2.3 ± 0.83.3 + 1.5

7.3 + 0.10.19 + 0.080.63 ±0.5

BDL

BDL

ND

9.8 (± 10,1) x103

75.6 + 20.8

——0.3

Denitrified and FilteredProduct Water

4.3 ±2.51.3 + 0.953

3.1 ±0.83.8 + 0.4

7.4 + 0.10.4 + 0.16

5.33 + 4.35

2.45(±1.7)x105

4.7 x104

ND

1.7(+2.7)x106

68.5 ± 8.4

51

0.16* after nitrate addition to well water1 before pre-chlorination2 after pre-chlorination of roughing filter effluent. Dose = 1.2 -1.4 mg/L Cl3 before final chlorination

As will be discussed below, we think that the high numbers of totalcoliform bacteria and chlorine demand are a result of the use of cornsyrup as the carbon source. In previous pilot research, effluent densityof total coliform bacteria was 1 to 2 log units less than at Wiggins.Recent research during 1998 and 1999 at the University of Coloradohas shown that significantly fewer coliform bacteria (2 to 3 log units)remain in the system if acetic acid (vinegar) is used as the carbonsource (Silverstein, 1998). After breakpoint chlorination, no totalcoliform bacteria were detected in the effluent. Overall, thedemonstration showed that with simple post-treatment: filtration anddisinfection, the product water quality was consistently high and wellwithin drinking water standards.

80

CARBON SUBSTRATE - MFCS vs. ACETIC ACID

Parameters for the design and operation of the biotower denitrificationsystem assume a sufficient supply of organic carbon substrate for thedenitrifying bacteria. Indeed, it was demonstrated during pilot operationthat denitrification performance is controlled by the supply of organiccarbon within a fairly large range of hydraulic and nitrate mass loadingrates (deMendonga et al., 1992). The most significant change betweenthe laboratory and pilot biotower studies and the Wigginsdemonstration was the substitution of high fructose corn syrup foracetic acid. Although satisfactory denitrification was achieved usingHFCS and corn syrup is significantly less expensive than food-gradeacetic acid, there were enough problems associated with use of HFCSto recommend return to acetic acid as a carbon source.

The most significant problem that we observed with use of HFCS isgrowth of excess non-denitrifying biomass. This had a number ofeffects. First a significant fraction of the non-denitrifying biomassappeared to be members of the total coliform group. As indicated inTable 32, total coliform bacteria counts were very high before pre-chlorination was begun, on the order of 105 MPN/100 ml even afterfiltration. Pre-chlorination reduced product water bacteria by one log,and no bacteria were found in breakpoint chlorinated water. However,the number of bacteria probably increased chlorine demand of thefiltered water. Recent research has verified that 2 to 3 logs fewer totalcoliform bacteria result when denitrifying cultures are fed acetic acid, anon-fermentable substrate (Silverstein, 1998). In addition, researchershave suggested that ammonia may be generated as a fraction of thedenitrification end product, instead of N2 gas, if the denitrifier growthenvironment allows fermentation (Akunna et al., 1993; Tiedje, 1988).The second problem was biotower clogging, evidenced by reduction ofthe fill time (actual residence time) of both biotowers from 34 to 13minutes. Excess biomass growth and clogging is consistent with thehigh numbers of non-denitrifying coliform bacteria observed. Recentresearch as shown that observed yield for denitrifying cultures is morethan two times higher when HFCS is used, compared with acetic acid.Interestingly, the volumetric denitrification rate for both the acetic acid-and HFCS-fed cultures was the same, in spite of the much higherbiomass solids in the HFCS culture. Thus the specific denitrificationrate for the acetic acid was three times higher than for the HFCSdenitrification (Grounds, 1999). Other fermentation products,particularly alcohols and carboxylic acids can be formed when afermentable substrate is present in an anoxic environment. Grounds(1999) observed acetate formation in lab denitrifying reactors receivingHFCS. If fermentation products were generated at Wiggins, a fraction

81

of these might leave the biotowers and sustain excess growth on theroughing filter. This may explain the excess biomass and cloggingwhich occurred in this pre-filter reactor. Finally, because MFCS can beso easily used by a diverse group of bacteria, it may be much moredifficult to control denitrification by availability of the carbon source.Figure 40 shows an attempt to correlate denitrification (nitratedestroyed) and MFCS (DOC) consumed using the data from theWiggins demonstration. One would expect proportionality, if otherconditions in the biotower were in excess for denitrification. Linearproportionality between acetic acid consumed and nitrate destroyedwas reported by Cook et al. (1990) with the slope of the line being thenecessary carbon; nitrogen ratio, C:N = 1.5:1. However, the Wigginsresults showed no correlation between DOC used and nitratedestroyed, over a fairly large range of C:N -1.5:1 to 3.5:1. Whether thelack of association between carbon dosed and denitrification may bedue to clogging-caused transport problems or use of MFCS by non-denitrifying bacteria is not as important than the fact that control ofdenitrification by carbon dose rate appears to be unreliable with MFCS.

0 ^0o DUD6) 40 -I

E 3CH

| 20

§ 10

I 003o o

Regression line:DOCr2 = 0.02DOC = 22.6 + 0.3017NO3-N

5 10 15 20

Nitrate destroyed (mg-NO3-N/L)

25

Figure 40. Relation between DOC and nitrate consumption during theWiggins demonstration between April and November 1997.

82

One difficulty with any conclusions about lack of a strong correlationbetween DOC consumed and nitrate destruction is that DOC is asurrogate measurement for MFCS. While it is probably a reliableindicator of influent DOC, soluble effluent organic carbon may alsoinclude fermentation products and soluble microbial products sloughedfrom the biofilm. Also, there are no data for very low influent DOCvalues that would have produced a more apparent slope and anintercept closer to zero in the regression line in Figure 40.

Another group of problems associated with MFCS at Wiggins was thedifficulty of storage and pumping. An important rationale for the switchfrom acetic acid to corn syrup was the difficulty of storing the highlycorrosive glacial acetic acid, as well as the wear on pumps and piping.However, MFCS is a very viscous fluid that tends to crystallize if notheated and mixed continuously. HFCS even crystallized in thediaphragm pump used for carbon addition, necessitating purchase of amore expensive and harder to maintain water-jacketed carbon dosingpump. The problems with on-site storage and pumping of acetic acidare more simply solved by substitution of weaker food-grade vinegaras the acetic acid source. Vinegar is widely available and can beobtained in high enough strength (10 - 30%) to allow for keepingsufficient carbon substrate on hand for weeks and even months. Also,vinegar will not freeze at cool room temperatures (15 °C) as glacialacetic acid will.

DISSOLVED OXYGEN

Anoxic conditions are necessary for denitrification. Denitrifying bacteriaare facultative organisms. In the presence of oxygen, denitrifyingbacteria will use the more energetically favorable oxygen electronacceptor rather than nitrate. However, in the relatively thick biofilm inthe bioreactor, a large fraction of the biomass can remain under anoxicconditions in spite of the presence of dissolved oxygen in the bulkwater. Cook et al. (1991) reported that dissolved oxygen entereddenitrifying biotowers at the Brighton pilot project at concentrationsranging from 2 to 6 mg/L. Additional carbon substrate was added toallow bacterial uptake of the dissolved oxygen at the head end of thebiotower. Similarly we found that dissolved oxygen in the influent watervaried widely at Wiggins, averaging over 3 mg/L. This did not inhibitdenitrification. The fact that the denitrified water had on average 0.6mg/L DO is evidence that the oxygen was consumed during passageof the water through the denitrifying biotower. What is more importantis that the denitrification performance was stable in spite of significantfluctuations of dissolved oxygen. Figure 41 shows paired influent DOand nitrate-nitrogen destruction along with the linear regression line for

83

these variables. There is a slight trend for decreasing denitrificationwith higher DO, but this is not significant, with r2 = 0.028. Figure 42 hastime profiles showing the variation of influent DO and denitrificationbetween May and November 1997, and there are no apparentassociations of peaks and valleys which would support a direct relationbetween influent DO and denitrification.

CO

o

CD

P1 10 -\0

CDQCD

5 -

~ 0

0 2 4 6

Influent Dissolved Oxygen (mg/L)

8

Figure 41. Effect of influent dissolved oxygen on biotower denitrificationfrom May through October 1997. Line is linear regression estimate: NO3-Ndestroyed = 15.8 - 0.337*DO, r2 = 0,028.

It should be noted that excess MFCS was added to account for oxygenrespiration, using a C:O2 ratio of 1:1. However, the additional DOCdose was based on the average DO concentration. No attempt wasmade to track fluctuations, which as can be seen from Figure 42, wereboth large and frequent. The ability of the Biotower denitrificationprocess to function consistently well in spite of changing influent DOlevels bodes very well for application of the system in rural areas usingwells with pressurized storage tanks resulting in highly variabledissolved oxygen concentrations.

84

25

O 20-Q

CD

~OCD

O

"55CD

O

15 -

10-

5 -

0

Influent DONO3-N consumed

30-Apr 19-Jun 8-Aug 27-Sep 16-Nov

Figure 42. Time plot of influent dissolved oxygen and denitrification(nitrate destroyed) from May to November 1997.

EQUIPMENT MODIFICATIONS

As a result of the Wiggins demonstration, two equipment/materialmodifications are suggested to improve the operability of drinkingwater denitrification systems.

Air scour is a critical operation for maintaining stable denitrification inthe biotower(s). One of the most significant problems at the Wigginsplant was severely retarded flow through the biotowers, a's indicated bydramatic reduction in fill time (retention time). Several factorscontributed to this. Probably the choice of HFCS as a substrateincreased the biomass growth. Also the compressor was not largeenough to provide the air flow rate necessary for fluidization of thebiotower packing media. These problems were exacerbated by themedia, which was observed to interlock, resisting fluidization.Accordingly, we recommend that ease of fluidization be anothercriterion for media selection (along with buoyancy, void fraction andspecific surface area). Particularly, spherical media seems to fluidizemuch more readily than the barbed cylindrical media. We have shownthat cylindrical media particles also can be fluidized readily, if theparticle edges are smooth (Silverstein, 1998).

85

Although no problems with roughing filter clogging were reported inearlier pilot operation of the denitrification-filtration sequence, biomassgrowth in the roughing filter at the Wiggins demonstration eventuallybecame so significant that the influent ponded and overflowed thereactor, necessitating manual cleaning on three occasions. Withrelatively few modifications, the roughing filter reactor can be equippedfor air scouring in the same way as the denitrifying biotowers. Becauseof the reduced carbon loading, this would be a far less frequentoperation than air scour of the biotowers, but it would eliminate verytime-consuming maintenance procedures like unpacking andrepacking the roughing filter over the life of the process.

OPERABILITY

Probably the most important reason for building the denitrificationsystem demonstration at the Town of Wiggins, Colorado was toinvestigate performance of the scaled up system under rural operatingconditions. Water quality effects had been studied previously at theBrighton pilot plant operation. Scale-up effects were not expected to besignificant, and they were not during normal operation. However, thedenitrification system used at Wiggins was sized to approximate full-scale application in a rural community under rural operating conditions.

The demonstration plant operated unattended most of the time. Oncestable operation at 38 Ipm had been achieved by April 1997, one staffresearcher from the University of Colorado was at the site three daysper week to collect data, making measurements and doing routinemaintenance. Keep in mind that in full-scale utility facilities, systemmonitoring would be far less intense than at the demonstration.Regular equipment failures were associated with power outages, andelectrical equipment was simple enough to restart as soon as powerreturned. The slow sand filter reservoir and equalization tank after theroughing filter had emergency overflow pipes to prevent flooding.Spilling from the roughing filter surge tank never occurred. Twice theslow sand filter reached maximum head loss between visits. After that,scraping was initiated after the reservoir had reached less thanmaximum depth. The roughing filter did flood once due to severeclogging. Modification of equipment to allow regular air scour ofaccumulated biomass will prevent that situation in future applications.

PROCESS CONTOL

There are two sources of influent variations that might impactdenitrification performance. The first is flow variation. The influent flowrate can be controlled to prevent short-term variation. However, water

86

consumption patterns vary seasonally and variation of performance ofthe denitrification system with different hydraulic loading rates is animportant concern. The denitrification biotower pilot study at Brightonshowed that the hydraulic loading to the biotower could be varied by asmuch as a factor of four while maintaining process performance,provided large changes in influent flow were accompanied byadjustment in the carbon dosing rate. Also, the biofilm neededapproximately two weeks to grow sufficiently to completely denitrify theincreased flow (deMendonca et al., 1992). At Wiggins, flow varied from19 to 76 Ipm, and satisfactory denitrification was achieved at all thoseflow rates, although only comprehensive monitoring data werecollected only for the 38-lpm influent flow rate.

The second variable is influent nitrate concentration. Early experimentswith the denitrification biotower process at the University of Coloradoshowed that the biofilm was not able to increase denitrification rate torespond to a rapid doubling of influent nitrate concentration within 24hours, even when the carbon dose had been increasedproportionately. However, at Wiggins, the influent nitrate concentrationwas increased from the normal well water concentration of 7 mg/LNO3-N to 20 mg/L NO3-N and complete denitrification was obtainedwithin one month. Also, ground water nitrate levels would not beexpected to fluctuate by a factor of two, even allowing for seasonalvariation. At Wiggins, the average nitrate level in the well water was6.8 mg/L NO3-N over the duration of one year's operation, with arelatively low standard deviation, 1.5 mg/L NO3-N, Figure 43 showsthe variation of effluent nitrate with influent nitrate at Wiggins from Mayto November 1997. The regression line equation predicts that effluentnitrate will rise as a function of increasing influent nitrate concentration,but the r2 value is low, 0.078, indicating a very weak trend. The spreadin the data points also suggest that denitrification is not stronglyaffected by fluctuations in influent between 15 and 25 mg/L NO3-N.

87

14.0

O

CD-»— iCO

cCD_^

u]

10.0-

8.0 -

6.0-

4.0 -

2.0 -

0.0

0.0 5.0 10.0 15.0 20.0 25,0 30.0

Influent Nitrate (mg/L NO3-N)

Figure 43. Relation between influent and effluent nitrate concentrationsbetween April and November 1997. Linear regression:effluent NO3-N = 0.32*(influent NO3-N) - 1,18, r^ 0.072.

88

CONCLUSIONS

1. Results of the demonstration of the drinking water denitrificationsystem in Wiggins, Colorado support the conclusion that ground watercan be treated effectively by the packed biotower denitrification andfilter polishing process sequence developed at the University ofColorado. Nitrate removal calculated from over 60 independent regularsamples collected from May to November 1997 was 15.4 ± 2.5 mg/LNO3-N with an influent of 19.6 + 2.4 mg/L NO3-N. Process design andoperation parameters specified in earlier laboratory and pilot-scaleresearch associated with complete denitrification have been verified.

2. As anticipated, the most deleterious effect on system water quality wasthe introduction of turbidity and bacteria. However, these are effectivelyremoved from the product water by filtration and disinfection, twoprocesses that are easily implemented in rural communities using slowsand filtration and chlorine addition.

3. Use of corn syrup (MFCS) as the carbon source caused a number ofsignificant problems, including excess biomass growth, associatedclogging of the biotower and roughing filter, higher concentration oftotal coliform bacteria in the denitrified product and increased chlorinedemand. Subsequent controlled research at the University of Coloradohas shown that use of acetic acid (vinegar) as a carbon substrate willsubstantially alleviate these problems.

4. The extended operation of the denitrification system in a rural venuewas very successful. During the seven months of standard operation at38 Ipm, only one person visited the sight three days per week, primarilyfor sample collection and monitoring. There was not a single incidentthat required shut down of the entire system. Individual processeswere by-passed for minutes during air scour up to hours for slow sandfilter scraping, cleaning the roughing filter media, or one-timereplacement of the carbon dosing pump.

89

REFERENCES

Akunna, J.C, C. Bizeau and R. Moietta (1993) "Nitrate and Nitrite Reductionswith Anaerobic Sludge using Various Carbon Sources: Glucose, Glycerol, AceticAcid, Lactic Acid and MethanoL" Wat Res., 27(8):1303-1312.

APHA, AWWA, WEF (1992) Standard Methods for the Examination of Water andWastewater, 18th Edition. APHA, Washington, DC.

Carlson, G. and J. Silverstein (1997) "Effect of Ozonation on Sorption of NaturalOrganic Matter by Biofilm." Wat Res., 31(10):2467-2478.

Cook, N.E., Jr., J. Silverstein, B. Veydovec, M.M deMendonca and R. Sydney(1991) "Field Demonstration of Biological Denitrification of PollutedGroundwater." Completion Report No. 162, Colorado Water Resources ResearchInstitute, Fort Collins, CO.

Cook, N.E., Jr., J. Silverstein, W. Hogrewe and K. Hammad (1990)"Denitrification of Potable Water in a Packed Tower Biofilm." Proc. ASCEEESpecialty Conf., Washington, DC, 175-183.

deMendonca, M.M., J. Silverstein and N.E. Cook, Jr. (1992) "Short and Long-Term Responses to Changes in Hydraulic Loading in a Fixed DenitrifyingBiofilm." Wat Sci. Tech. 26(3-4):535-544.

Grounds, J. (1999) "Enrichment of Biomass to Minimize Excess Growth andPathogens in a Drinking Water Denitrification Process." MS Thesis, CivilEngineering, Univ. Colorado, Boulder.

Hogrewe, W. (1990) "Biofilm Denitrification of Drinking Water: Kinetics, OxygenInhibition, and Biomass Removal." Ph.D. Dissertation, Civil Engineering, Univ.Colorado, Boulder.

Silverstein, J. (1997) "Demonstration of Biological Denitrification of DrinkingWater for Rural Communities." Vol I. EPRI Report WO-2662-84, Electric PowerResearch Institute, Palo Alto, CA.

Silverstein, J. (1997) "Biological Denitrification of Drinking Water." US Patent No.5,681,471. US Patent Office, Washington, DC.

Silverstein, J. and G. Mann (1998) "Development of Safe and Rapid BiofilmInoculation Protocol to Enhance Commercialization of Biological Processes forDrinking Water Treatment." Report for ETAP 98.3.6, Colo. Adv. Materials Inst.,Golden, CO.

90

Tiedje, J.M. (1988) "Ecology of denitrification and dissimilatory nitrate reductionto ammonium." in Biology of Anaerobic Microorganisms, e. Alexander B.Zehnder, Wiley, New York.

Wheeler, E.R. (1998) "Factors that Effect Nitrification and Manganese Removalin Nitrifying Trickling Filters." MS Thesis, Civil Engineering, Univ. Colorado,Boulder.

*

ft

•§

•

*

§

iii

§§

ft 91

ft

COST AND ENERGY USE EVALUATION

SCOPE AND APPROACH

System cost is often the most important criterion used by utilities inselecting a drinking water treatment system, and choosing a nitrateremoval process is no exception, especially for small ruralcommunities. The demonstration of the novel drinking waterdenitrification system at Wiggins was designed to match many of theoperational and size constraints of a rural utility. However there wereseveral critical differences between the demonstration and aproduction water treatment plant that make it difficult to extrapolatecosts from the pilot operation in Wiggins. In the following section, threemethods have been used to estimate costs of the Biotowerdenitrification system so that comparisons can be made with other thetechnologies available for nitrate removal of drinking water in a ruralcommunity. The first was to separate the costs at Wiggins that wereassociated with drinking water treatment from the total costs of theproject which included very significant research and monitoring.Second was to survey drinking water utilities in the United Statesoperating or anticipating building a water treatment plant for nitrateremoval. Third was to review published drinking water nitrate removalcost comparisons. The last was made possible by the study preparedby Blais et al., students at California State Polytechnic University,Pomona, under the direction of Professor Julie Wei, for the Main SanGabriel Basin Watermaster, Director, Richard Sase (1997).

WIGGINS DENITRIFICATION DEMONSTRATION COSTS

As a benchmark, we tried to estimate the cost of the denitrified andfiltered water produced over one year of the demonstration (November1996 - November 1997). Approximately $240,000 was spent on thedemonstration project in total. Of that, $145,000 was paid for thedemonstration facility, distributed as: $50,000 for the processequipment, $80,000 for site preparation and construction of thebuilding, and $15,000 for engineering fees. If the present worth of thefacility is discounted assuming a subsidized interest rate of 4% and a20-year life for the physical plant, the present worth annual cost isapproximately $11,000 per year. Of the remaining $95,000, the cost ofthe extensive monitoring (much more than a rural utility would carryout) and addition of nitrate and sodium thiosulfate chemicals (whichwould not be costs for an actual water treatment plant) accounted forapproximately $82,000, including the research assistants' time spentsampling and doing lab analyses. Travel between Wiggins and Boulderaccounted for another $6,000. Thus an estimate of $7,000 can bemade for carbon addition, electricity costs, personnel and other

92

operations and maintenance during the year from November 1996 toNovember 1997.

Another approach to estimating "real" costs associated with watertreatment at the demonstration is to sum actual expenditures duringthe year that can be directly linked to the denitrification watertreatment. The two largest operations expenses were electricity andcarbon substrate (MFCS) addition. The electric utility bills for thedemonstration plant that averaged $250/month, for a total of $3,000 forthe year. Using an average C:N ratio of 2:1, average nitrate removal of15 mg/L NO3-N, and average flow rate of 38 Ipm, the average MFCSutilization was approximately 2,000 kg for the year. At $0.50/kg, thetotal cost for MFCS is estimated at $1,000. Thus, the cost of the twomajor operations and maintenance items, carbon (MFCS) addition andelectricity, totaled approximately $4,000. That leaves approximately$3,000 for another major expense, paying an operator. Based on thedemonstration experience, regular operation of the plant would requirea maximum of 4 hours per week. Assuming that an operator would bepaid $15/hr (approximately the salary paid to the post-doctoralresearch associate who was in charge of the field operation), then thecost of personnel for the year would be approximately $3,000. Addedto the cost of chemicals and electricity, that also yields an estimate foroperations and maintenance of $7,000 for the year.

At an average flow rate of 38 Ipm (10 gpm), approximately 20,000 m3

(5 million gallons) of water was treated in one year. Using thedemonstration costs, the capital cost of the treated demonstrationwater was approximately $0.55/m3 ($2.10/1,000 gallons) and theoperations and maintenance costs were approximately $0.35/m3

($1.30/1,000 gallons). Using the utility bills for the demonstration, theunit cost for electricity alone can be estimated at $0.15/m3 ($0.56/1,000gallons). This was due to the high cost of the relatively inefficientheater in the un-insulated building, both of which reflect the uniqueconstraints of the tight budget for the demonstration.

Great caution should be used in applying these estimates to predictingthe cost of a denitrification system for a rural utility. Capital costs canvary greatly. For example, many water systems already have buildingsthat can house the components of the denitrification system.Construction costs also are not easily transferable to different regionsof the country. The demonstration plant had a very small capacity, 55m3/day (14,400 gallons/day). Probably there would be significanteconomies of scale for much of the process equipment, piping andcontrol system that was installed at the Wiggins demonstration facilityfor a larger plant. Finally, various revolving loan funds and grants canreduce the capital costs of a water treatment system to a public utility,

93

especially in rural areas. Likewise, the operations and maintenancecosts for the demonstration probably contain items that would not berelevant to a regular drinking water utility. For example, a significantfraction of the electricity was used to pump water from the equalizationtank to the demonstration plant. In regular operation, a single wellpump could be used, greatly reducing the cost. Another factor is theamount of nitrate that must be destroyed. Lower influent nitrateconcentration would mean less carbon substrate addition andconsequently lower operation costs.

WATER UTILITY COMPARISON

We wanted to compare the costs of biological denitrification of drinkingwater with the two processes which have been recommended in thepast for nitrate removal from drinking water: reverse osmosis (RO) andion exchange (IX) (USEPA, 1983). The best way to do this seemed tobe getting estimates of costs from operating utilities carrying out nitrateremoval from drinking water. Process equipment vendors couldprovide equipment cost estimates, and even could predict costs forchemical addition sometimes, but could not reliably detail operationsand maintenance costs of a nitrate removal process in a small watertreatment facility. This information was received either directly fromwater plant operators or from the engineer who designed the plant.There also were feasibility studies available that compared differentnitrate removal technologies.

By collecting this budget data from as many utilities as possible,graphs were made to investigate general trends. One trend ofparticular interest was that of economy of scale, which necessitatedthe retrieval of data from utilities of different size for each technology.Other trends included capital vs. operation and maintenance costs,factors that affect overall investment and annual budget. Finally,summary tables were prepared to address the many factors thatinfluence system cost.

UTILITIES SURVEYED

Ten utilities that either had operating nitrate removal treatment facilitiesor had done a recent detailed feasibility study anticipating building aprocess soon were queried in Summer 1998. The utilities, plantcapacity and nitrate removal process used are given in Table 32.

Because every facility was unique, designed in order to meet waterquality and capacity at different conditions and constructed at differenttimes, it was necessary to combine the information in a uniformmanner for comparison purposes. To simplify the situation, cost data

94

were requested in a survey form to get information in the followingcategories:

1. Facility Capital Costs, total $/system

2. Operation and maintenance costs (O&M), $/10QO gallons ofwater produced

3. Electricity costs, either as $/1000 gallons or percent of O&Mcosts

Table 32. Nitrate Removal Facilities in Utilities Surveyed.

Utility

City of McFarland, California.Contact: Kelly UlrichTown of Adrian, Minnesota.

City of Des Moines, Iowa.Contact: Gary BenjaminSan Gabriel Basin, California

Town of Seymour, Texas**Contact: Ken MartinTown of Lucas, Kansas**Contact: Chris CoxCity of Brighton, Colorado.Contact: Rodney EvansCity of Tustin, California.Contact: Arturo ValenzuelaTown of Coyle, Oklahoma.Contact: Gary CarlsonTown of Crayton, Nebraska.Contact: Bradley Simons

PlantCapacity

m3/d(MGD)3,785(D

1,635(0.432)37,850

(10)16,278(4.3)3,217(0.85)572

(0.151)11,355

(3)1,893(0.5)300

^0.079)No reply

Process

IX

IX

IX

IX

IX, RO

IX, RO

RO

RO

BioDen*

No reply

commercial name for Biotower denitrification and filtration process* data from feasibility study

Operation and maintenance costs were specified as those whichconstituted any expenses that occurred after plant start-up. Forreverse osmosis, these costs include membrane replacement (15% ofthe membranes were assumed to be replaced every year), pre-filtering,

95

chemical addition, concentrate disposal, water monitoring systems,operator salary, and electricity. Ion exchange O&M costs consist ofsalt costs, brine disposal, brine regeneration, operator salary, andelectricity. Biological denitrification O&M costs consist of food gradecarbon source (vinegar, MFCS) costs, operator salary, and electricity.Capital costs represent the required investment before the first year ofoperation, consisting mainly of facility design and construction costsand equipment costs. These initial costs were then annualized overthe lifetime of the system, which was assumed to be ten years, usingan 8% discount (interest) factor. This factor probably is higher than theactual cost of money for small public utilities, but has been used by theUSEPA in comparing treatment processes. Both annualized capitalcosts and O & M costs were combined and normalized by the waterproduced to give $/m3 ($/1,000 gallons) estimates for comparison.

The estimation procedure averages regional difference and does notaccount for advances in technologies made since the plants were builtwhich may either increase or lower costs. It should be noted thatsystem costs considered are for treatment system costs only. Thesecosts do not include some factors that contribute to the total water costcharged to consumers such as distribution systems, property values,well maintenance and drilling, storage tanks, and blending facilities.

UTILITY COST SURVEY RESULTS

Of the 10 utilities surveyed, nine responded. Two, the cities of Lucas,Kansas and Seymour, Texas, had done feasibility studies for theirwater utilities and had site-specific cost estimates for both RO and IXfacilities. The only biological denitrification process currently underconsideration by a utility (Coyle, Oklahoma) for drinking watertreatment in the US is the BioDen process which is the commercialversion of the Biotower denitrification process demonstrated atWiggins, Colorado. The survey cost data for six IX facilities, four ROfacilities and one biological denitrification facility are in the Appendix.Table 33 is a summary comparison of cost data for IX, RO and BIO(BioDen) plants.

From the survey data, ion exchange has the lowest unit cost, onaverage, $1.03 per 1,000 gallons ($0.27/m3). Reverse osmosisappeared to be the most costly process, with an average total unit costof $2.01/1,000 gallons ($0.53/m3). The BioDen biological denitrificationprocess bid for the Town of Coyle, Oklahoma is estimated to cost$1.06/1,000 gallons ($0.28/m3), which is significantly less than the costof RO and equivalent to the cost of IX. For both the IX and ROprocesses, annualized capital and O & M costs are relatively equal.

96

For the BioDen process, the capital cost is almost two-thirds of thetotal costs, reflecting the high construction cost of the slow sand filter.

Table 33. Summary statistics for cost data from utility survey, includingcapital, O & M, and total unit costs. Data are averages + one standarddeviation and number of utilities for each process.

Process (n)

IX (6)

RO(4)

BIO(1)

Capital$/m3

($71,000 gal)$0.13+0.08

($0.50 ± 0.32)

$0.29 ± 0.08($1.09 + 0.31)

$0.17($0.64)

O&M$/m3

($/1 ,000 gal)$0.12 + 0.11

($0.44 ± 0.40)

$0.24 + 0.07($0.92 + 0.27)

$0.11($0.42)

Total$/m3

($/1,OOOgal)$0.27 + 0.13

($1.03 + 0.50)

$0.53 + 0.06($2.01 +0.23)

$0.28($1.06)

The survey data provided an opportunity to investigate economy ofscale for both the RO and IX processes. An economy-of-scale analysisfor IX and RO is presented in Figures 44 and 45, respectively.

0.70

0.60 -

^ 0.50 -

r o-4o HCO

O 0.30 -4-1

!§ 0.20 -

0.10 -

0.00

0 10,000 20,000 30,000 40,000

IX Plant Capacity (m3/d)

Figure 44. Effect of plant capacity on cost of ion exchange processes.Line is regression: unit cost ($) = 0.32-4.93e-6*IX plant capacity (m3/d),r2 = 0.296.

97

tooO

"c

u./u

0.60 -

0.50 -

0.40 -

0,30 -

0.20 -

0.10 -n nn

*

0 3,000 6,000 9,000 12,000

RO Plant Capacity (m /d)

Figure 45. Effect of plant capacity on cost of reverse osmosisprocesses. Line is regression: unit cost ($) = 0.50+7.42e-7*RO plantcapacity (m3/d), r2 = 0.359.

Interestingly, while there did seem to be a trend that as IX plantcapacity increased, unit water production costs decreased, althoughthe regression constant for the linear fit was not high, r2 = 0.296.However, there appears to be no economy of scale for reverseosmosis, as can be seen from the flat regression line in Figure 45. Infact, there was only one large capacity RO plant, in Brighton, Colorado,which had the highest unit costs of the four plants, $2.27/1,000 gallons($0.60/m3).

It was beyond the scope of the survey to obtain data such which mightbe very important in deciding what nitrate removal process to use.Factors such as operability, water quality factors, demand variation,land requirements, and process waste by-product disposal couldimpose constraints on process selection which could easily overridepure cost considerations.

PUBLISHED COST ESTIMATES

A student research group at the California State Polytechnic Universityin Pomona, California produced a feasibility study for the San GabrielBasin Watermaster in 1997 (Blais et al., 1997). Six nitrate removal

98

ftftftftftftftft

alternatives were compared: ion exchange, reverse osmosis, biologicalfluidized-bed reactor, in-situ bio-denitrification, the BioDen process,and autotrophic denitrification using sulfur. Cost estimates were madeusing a combination of equipment vendor and utility. Because thisreport focused a treatment system to be designed for one 800 GPM(3,028 Ipm) well in the San Gabriel Basin area, the alternative costcomparison eliminates variations from water quality and regional costfactors. The cost estimates for RO, IX and BioDen are cited below inTable 34.

Table 34. Cost estimates for IX, RO, and BioDen for treatment of nitrates inwater from an 800 GPM (3,028 Ipm) well in the San Gabriel Basin. (Blais eta!., 1997)

Process

IX

RO

BioDen

Capital$/m3

($71,000 gal)$0.07

($0.28)

$0,15($0.55)

$0.10($0.38)

O&M$/m3

($71,000 gal)$0.07

($0.28)

$0.18($0.67)

$0.04($0.16)

Electricity$/m3

($71,000 gal)$0.003($0.01)

$0.05($0.20)

$0.003($0.01)

Total$/m3

($71 ,000 gal)$0.15

($0.56)

$0.32($1.22)

$0.14($0.54)

ift»ift

The cost trends in the San Gabriel Basin study are similar to thosefrom the survey except that the total cost estimate for the IX andBioDen processes are almost identical, $0.56/1,000 gallons ($0.15/m3)and $0.54/1,000 gallons ($0.14/m3), respectively. Both are less thanhalf the cost of RO which was estimated to be $1.22/1,000 gallons($0.32/m3). As in the survey results, the capital cost of the BioDenprocess is more than twice the O & M cost, because of the high cost ofsiting and constructing the slow sand filter. Electric power consumptioncosts follow the total cost trend, considering that the cost ofpressurizing water for the RO process is expected to be high. Theestimated power cost for RO accounts for 30% of the anticipated O &M costs, whereas for IX and BioDen, electric power costs are 4% and7%, respectively.

99

COST ANALYSIS REFERENCES

Benjamin, Gary, "Nitrate Removal for Des Moines, Iowa".

Blais, C., K. Burl, A. Nazaroff, P. Tonthat, V. Truong, and J. Yu (1997)Nitrate Removal Study Main San Gabriel Basin. California StatePolytechnic Univ. and Main San Gabriel Basin Watermaster, Azusa, CA.

Carlson, G. (1998) BioDen system cost estimates. InformalCommunication.

Environment, Transport, and Planning, "DENITROCAT report ECO1".

Guter, Gerald A., (1985) "Studies on Nitrate Removal from ContaminatedWater Supplies: Design and Initial Performance of a 1 MGD NitrateRemoval Plant", Water Research Engineering Research Laboratory,Cincinnati, Ohio.

Kartinen, Ernest O., "Selection of a Nitrate Removal Process for the City ofSeymour, Texas".

Office of Water Research and Technology (1979) "Reverse Osmosis",Water Research Capsule Report, U.S. Government Printing Office,Washington DC.

Silverstein, JoAnn (1997) "Demonstration of Biological Denitrification ofDrinking Water for Rural Communities", Vol 1, Report to EPRI, Universityof Colorado, Boulder.

USEPA (1983) Nitrate Removal for Small Public Water Systems. EPA570/9-83-009, Office of Drinking Water, Washington, DC.

100

COMMERCIALIZATION

The University of Colorado received a US Patent for the Biotowerdenitrification and biological roughing filter processes in 1997 (USPatent #5,681,471, October 27, 1997). The technology has beenlicensed exclusively by Nitrate Removal Technologies, LLC, (NRT)located in Golden, Colorado. NRT has begun marketing the biologicaldenitrification process under the name, BioDen. The first drinking watertreatment facility using the BioDen process was constructed in theTown of Coyle, Oklahoma during 1998. The Coyle plant has a capacityof 55 GPM (208 Ipm), and serves a rural population of approximately350 people. The plant started to produce drinking water for thecommunity in October 1998.

The demonstration of biological denitrification of drinking water atWiggins, Colorado has been critical for commercialization. The processis performing well in Coyle, incorporating many of the operation andequipment modifications suggested as a result of the Wigginsdemonstration project. Food-grade vinegar is used for the carbonsource instead of HFCS. The vinegar has been easily obtained from acommercial supplier to food processing operations, and severalmonths supply can be stored in a 4,000-liter tank at the plant.Spherical media have been substituted for the interlocking media usedat Wiggins. The roughing filter has been modified to allow air scouringof that media as well as the media in the Biotower. The air compressorhas been sized to deliver sufficient airflow to fluidize media in both theBiotower and roughing filter. The Coyle plant superintendent/operatoris also the Town Police Chief, verification that this process is operablewithin the labor constraints of a rural community.

101

ACKNOWLEDGEMENTS

We were fortunate to have the support of many individuals andinstitutions throughout this demonstration. Two of the principal projectsponsors, the Electric Power Research Institute, through itsCommunity Environmental Center (EPRI/CEC), and the National RuralElectric Cooperative Association (NRECA) were the first groups tocommit financial resources for the demonstration. Beyond fundingsupport, their enthusiasm was a critical validation of the concept of ademonstration to promote the application of a novel drinking watertreatment technology for rural communities. In addition, involvement ofgroups representing electric utilities set an important precedent forfuture links between energy and water infrastructure development inrural communities. We especially thank Mr. Tom Yeager, Chair ofEPRl/CEC's Small Community Systems group and also Chair of theProject Advisory Committee for the demonstration. Mr. Yeagerprovided both engineering and management insights and wasunflagging in his optimism, even through the most difficult early days ofthe demonstration. We appreciate the contributions of Mr. John Neal,retired Director of Energy Research for the National Rural ElectricCooperative Association. Mr. Neal was especially helpful in makingsure the demonstration project results would support eventualcommercialization of the denitrification process. Two representatives oflocal utilities: Mr. Vernon Tryon of the Morgan County Rural ElectricAssociation and Mr. Warren White of the Tri-State Generating andTransmission Association, helped us to understand the concerns ofrural electric power suppliers in developing infrastructure (includingwater treatment facilities) in rural areas.

The purpose of the denitrification process demonstration was tooperate the process at significant scale in a rural community. As thehost to the demonstration facility, the Town of Wiggins provided criticalsupport for the project in several ways. We are particularly grateful forthe contributions of Mr. John Holdren, the Town Manager, who was avery effective liaison between the demonstration project and the Townthroughout the demonstration. First, the community generously allowedus to construct the facility adjacent to their drinking water well pumphouse, including bringing in power lines. When we encounteredproblems such as how to use the product water for ground waterrecharge and meet water rights concerns, Mr. Holdren found solutions,The Town provided financial support. Also Wiggins sponsored theproject through the Colorado State Department of Local Affairs(DOLA), enabling us to obtain financial support from DOLA. Finally, Mr.Holdren gave us the benefit of his insights as the manager of the waterutility for the Town of Wiggins. Mr. Kent Gumina, the Northeast

102

Regional Director of DOLA, was instrumental in helping us obtainfunding through DOLA and also was a liaison between people from theUniversity of Colorado, the Town of Wiggins and the State of Colorado.

The Colorado State Department of Public Health and Environment(CDPHE) helped us to address one of the key objectives of thedemonstration: implementing monitoring and data collection whichwould be important for regulatory oversight of the drinking waterdenitrification process in any future applications. Staff from theCDPHE's Drinking Water Division, Mr. Jerry Biberstine, Mr. Greg Akinsand Mr. Glen Bodnar have reviewed and commented on ourmonitoring plans both in meetings and in writing, and visited thedemonstration in Wiggins for on-site advice.

In addition to the support from EPRI/CEC, NRECA, the Town ofWiggins and the State of Colorado, the National Water ResearchInstitute became the fourth critical project sponsor, really enabling thedemonstration to get off the ground. In addition to a grant, the NWRIthrough its Director, Dr. Ron Linsky, and members of its ResearchAdvisory Board, Dr. Roy Spalding, Dr. Anita Highsmith and Dr. HermanBouwer, contributed important technical expertise to thedemonstration, especially through the difficult start-up phase.

Technology transfer of the research-based denitrification process toapplication in a drinking water treatment plant has always been thegoal of the engineers at the University of Colorado who developed thebiotower system, and that was the thrust of the demonstration. Theinvolvement of Nitrate Removal Technologies (NRT) was essential tointegrate technology transfer directly into the demonstration. NRT wasa key supporter of the demonstration before anyone had committedmoney. Both the President and Vice President of NRT, Mr. Greg Mannand Mr. John Copeland, stayed with us through all the ups-and-downsof the project, including the three years it took to get all the necessaryfunding in place. NRT fabricated the process equipment that was usedin the Wiggins demonstration, and NRT provided the critical supportthat allowed the extensive monitoring and data collection during thelast seven months of the demonstration. But most important, theirvision that the drinking water denitrification process was bothcommercializable and marketable gave the project a challenging andinspiring end-point.

The demonstration project was carried out by people from theUniversity of Colorado. Dr. Gary Carlson, a post-doctoral researchassociate, was the on-site project manager. (He also did all theoperation, sample collection, instrumental and data analyses for theyear of operation between October 1996 and November 1997.) More

103

than a manager and diligent worker, Dr. Carlson always seemed tohave the critical insight necessary to solve the myriad problems thatcame up throughout the demonstration. Many of his observations areincorporated in the Discussion section, eventually becoming importantsuggestions for design and operation modifications. In addition, Mr.Dan Thompson, Mr. Jude Grounds and Mr. Juan Paez worked on thedemonstration project during the conceptualization of the monitoringprogram and plant start-up. Ms. Alison Keith supervised the utility costsurvey, developing hard-to-get sources of cost information, maintainingcontacts with utilities and organizing and interpreting data from utilityresponses.

Prominent in the references cited in this report is the name, Dr. NevisE. Cook, Jr. He was instrumental in the development of the biotowerdenitrification process at the University of Colorado. Dr. Cook co-supervised laboratory and pilot plant operation of the denitrification andpolishing reactors when he was on the staff at the University ofColorado. During that time he made numerous creative contributions tothe design of the denitrification process equipment. Now a facultymember at the Colorado School of Mines, Dr. Cook continued toprovide invaluable technical advice throughout the demonstration.Students who were involved in the early research at the University ofColorado, including laboratory and small-scale pilot plant operationwere: Dr. William Hogrewe, Dr. Marcia deMendonca, Mr. BillVeydovec, Dr. Joy Barrett, Mr. Roger Sydney, and Mr. KhalidHammad.

104

Left:

bui

ldin

g h

ousi

ng d

rinki

ng w

ater

wel

l pu

mps

in T

own

of W

iggi

ns,

CO

. R

ight

: fo

unda

tion

for

deni

trifi

catio

n de

mon

stra

tion

faci

lity.

Con

stru

ctio

n be

gan

in M

arch

199

6.

John Holdren, Town Manager of Wiggins, Colorado.

Tow

n of

Wig

gins

wat

er s

uppl

y bu

ildin

g. R

ear

cent

er:

sout

h w

ell

pum

p. L

eft:

stai

nles

s st

eel p

ress

ure

equa

lizat

ion

and

chlo

rine

cont

act

tank

. In

fluen

t to

deni

trific

atio

n de

mon

stra

tion

was

take

n fr

om s

mal

t bl

uepi

pe e

xten

ding

from

und

erne

ath

equa

lizat

ion

tank

at f

ar le

ft.

Rig

ht:

com

plet

ed b

uild

ing

hous

ing

den

itrifi

catio

n de

mon

stra

tion

proc

esse

s ad

jace

nt t

o T

own

of W

iggi

ns'

drin

king

wat

er w

ell p

ump

hous

e on

left.

Den

itrifi

catio

n de

mon

stra

tion

proc

ess

equi

pmen

t. N

ear

right

: G

ary

Car

lson

sam

ples

lead

den

itrify

ing

biot

ower

.Fa

r rig

ht: c

orn

syru

p pu

mp

and

roug

hing

filt

er.

Left:

JoA

nn S

ilver

stei

n at

lab

benc

h by

slo

w s

and

filte

r bo

x.

JoAnn Silverstein (center) and Gary Carlson (on ladder) sample thedenitrification biotower reactors (center and right tanks). Roughing filtertank is on the left.

Den

itrifi

catio

n bi

otow

er c

olum

n pa

ckin

g m

edia

(N

orP

ac) c

oate

d w

ith b

iofil

m a

fter

mon

ths

of o

pera

tion

with

reg

ular

air

scou

ring.

Corn syrup addition from 55-gatlon drum in foreground using pistonpump on table. Control panels, denitrifying biotowers and roughingfilter in background.

JoA

nn S

ilver

stei

n in

spec

ts s

low

san

d fil

ter ju

st a

fter

scra

ping

. B

row

n st

aini

ng o

n fil

ter

box

wal

ls is

from

man

gane

se d

epos

ition

.

Dan

Tho

mps

on,

CD

gra

duat

e s

tude

nt r

esea

rch

ass

ista

nt,

anal

yzes

bio

tow

er w

ater

sam

ple.

Jude Grounds, CU student researcher, assists with demonstrationplant start-up.

Firs

t co

mm

erci

al d

rinki

ng w

ater

den

itrifi

catio

n pl

ant

usin

g pr

oces

s de

mon

stra

ted

at W

iggi

ns (

Bio

Den

pro

cess

),de

sign

ed a

nd b

uilt

by N

itrat

e R

emov

al T

echn

olgi

es (

NR

T)

in C

oyle

, OK

. P

roce

ss c

apac

ity is

114

lite

rs p

er m

inut

e(3

0 gp

m).

Bio

tow

er a

nd r

ough

ing

filte

r ar

e in

side

bric

k bu

ildin

g w

ith s

low

san

d fil

ter

box

at th

e rig

ht.

Left:

Gre

g M

ann,

Pre

side

nt o

f NR

T.

Coyle, OK denitrification plant process equipment. Left: compressor for airscouring operations. Center: control panel. Right: roughing filter tank.

Denitrifying biotower at Coyle, OK drinking water treatment plant. Dimensionsare 6 m height, 1.2 m diameter. Design capacity is 114 liters per minute (30gpm).

APPENDIX A: WATER QUALITY DATA

No

vem

ber

'96 N

itra

te D

ata

Dat

eB

ioT

ower

#1

Bio

Tow

er #

2 R

ough

ing F

ilter

S

low

San

d F

ilter

S

low

San

d F

ilter

Raw

R

aw +

MFC

S

Effl

uent

E

fflue

nt

Effl

uent

In

fluen

t E

fflue

nt

11/1

3

11/1

5

11/1

8

11/1

9

11/2

0

11/2

1

11/2

2

11/2

5

11/2

6

8.0 6.2

5.9

6.2

5.9

5.9 6.1

6.0

5.9

6.0 5.9

4.4

4.6

6.1

5.7

5.9

5.6

2.4 1.9

1.9

1.6

3.2

2,8

1.6

3.2 1.8

0.9

0.4

0.2 0.3 1.2

1.1

0.2

1.2 0.3

0.2

0.4 0.1

0.2 1.3

1.1

0.3

1.3

0.4

0.9

0.4

0.2

0.6

0.9

0.9

0.7

0.7

0.7

0.7

0.8

0.7 1.2

0.6

AP

PE

ND

IX P

AG

E A

-2

De

ce

mb

er

'96 N

itra

te D

ata

Dat

eB

ioT

ow

er #

1 B

ioT

ow

er #

2 R

ou

gh

ing

Filt

er

Slo

w S

and

Filt

er

Slo

w S

and

Fi

lter

Raw

R

aw +

HFC

S

Eff

luen

t E

fflu

ent

Eff

luen

t In

flu

ent

Eff

luen

t

12/4

12/5

12/9

12/1

1

12/1

2

12/1

5

12/1

6

12/1

8

12/1

9

12/2

3

12/2

7

12/3

0

6.3

6.7

6.7

6.4

6.5

6.0

13.7

6.5

6.4

7.5

8.6

6.1

5.8

7.2

6.0

5.7

13.5

6.7

7.0

6.0

6.3

10.1

6.2

5.9

2.4

2.1

2.4

3.0 3.6

10.6

3.6

18.6

4.4

5.0

4.3

3.4

0.8

0.5

1.1

1.2

1.1

2.5

3.6

2.8 3.1

2.0

3.1

2.1

1.0

1.8

1.0 0.9

1.3

3.5

3.2

1.7

4.1

2.9

3.0

2.2

4.1

2.3

0.7

2.9

2.1

AP

PE

ND

IX P

AG

E A

-3

Jan

uary

'9

7 N

itra

te D

ata

Dat

eB

ioT

ow

er #

1 B

ioT

ow

er #

2 R

ou

gh

ing

Filt

er

Slo

w S

and

Filt

er

Slo

w S

and

F

ilter

Raw

R

aw +

MFC

S

Eff

luen

t E

fflu

ent

Eff

luen

t In

flu

ent

Eff

luen

t

1/2

1/3

1/7

1/8

1/9

1/13

1/16

1/19

1/20

1/22

1/23

1/28

1/29

1/31

5.7

5.7

5.5

5.8

5.7

5.6

6.9

9.7

7.7

6.3

7.3

7.5

5.9

7.2

5.8

5.6

5.6

5.8

5.8

6.1

7.3

7.6

8.5

31.7

21.9

18.1

16.4

24.6

3.5

3.7

3.8

3.8

3.2

3.6

4.6 5.1

5.4

18.6

18.2

16.0

15.6

16.6

2.2

2.3

2.7

3.0

2.0

2.1

3.6

5.4

3.3

13.6

16.4

17.0

15.7

14.4

2.2

2.3

2.7

2.9

1.9

2.0

3.5 6.1

3.7

27.3

17.0

14.8

14.4

22.0

1.7

1.4

1.5

1.1

0.2

0.2

AP

PE

ND

IX P

AG

E A

-4

••••••••••••••••••••••••••••••••••••••••0

*0

4

Dat

e

Feb

ruary

'97 N

itra

te D

ata

Bio

To

wer

#1

Bio

To

wer

#2

Ro

ug

hin

g F

ilter

S

low

San

d F

ilter

S

low

San

d

Filt

erR

aw

Raw

+ M

FCS

E

fflu

ent

Eff

luen

t E

fflu

ent

Infl

uen

t E

fflu

ent

2/3

2/6

2/7

2/10

2/11

2/16

2/17

2/18

2/19

2/24

2/27

7.4

8.4

7.2

6.6

5.2

9.7

8.1

5.8

4.2

6.5

5.6

32.8

22.5

26.0

14.2

21.7

31.4

18.0

16.4

25.6

13.6

14.6

16.6

16.8

11.3

12.3

9.3

17.4

12.0

9.9

16.6

6.1

10.5

12.1

17.4

150.

2

7.5

7.6

14.4

9.3

8.0

8.6

9.8

8.2

11.6

14.2

9.4

7.8

7.3

14.1

7.7

10.0

8.6

7.3

9.0

AP

PE

ND

IX P

AG

E A

-5

Ma

rch

'9

7 N

itra

te D

ata

Dat

eB

ioT

ow

er #

1 B

ioT

ow

er #

2 R

ough

ing

Filt

er

Slo

w S

and

Filte

r S

low

San

d Fi

lter

Raw

R

aw +

HFC

S

Eff

luen

t E

fflu

ent

Eff

luen

t In

fluen

t E

fflu

ent

3/4

3/6

3/10

3/11

3/17

3/19

3/21

3/24

3/25

3/28

3/31

6.0

5.6

6.1

5.7

5.0

7.9

6.9

6.0

5.8

5.0

4.6

15.6

14.7

12.8

13.9

19.2

23.9

20.5

19.2

18.8

18.2

17.9

13.2

12.2

10.0

10.7

17.8

16.5

14.3

12.9

13.0

11.4

9.3

11.3

9.6

6.6

8.2

14.7

11.6

6.6

3.2

3.4

7.8

4.1

11.4

8.5

6.8

8.5

14.6

9.8

7.6

2.6

3.3

8.2

4.2

AP

PE

ND

IX P

AG

E A

-6

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ril

'97

Nit

rate

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Dat

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ing

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and

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S

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luen

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luen

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4/2

4/4

4/7

4/9

4/12

4/15

4/16

4/17

4/21

4/22

4/23

4/25

4/28

4/29

4/30

4.5

5.0

5.4

5.5

6.9

5.4

5.2

8.7

7.6

6.7 10

.3

6.6

6.0

5.8

5.9

19.1

16.9

19.0

17.7

29.4

18.8

17.7

20.1

21.4

21.4

18.4

23.8

17.0

16.4

16.0

14.2

4.3

3.2

3.8

3.7

10.1

7.7 7.0

6.5 11.2

5.3

4.4 6.1

2.9

4.1

11.3

0.5

0.5

0.6

2.0

4.7

2.6

5.3

2.7

4.3

1.9

2.4

4.6

0.9

1.1

11.6

0.6

0.8

0.5

1.3

3.1

1.7

3.2 6.5

4.3

21.9

1.6

1.1

0.7

2.2

0.8

1.2

0.7

1.3

AP

PE

ND

IX P

AG

E A

-7

Ma

y '

97 N

itra

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Dat

eB

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ent

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luen

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5/1

5/2

5/5

5/6

5/7

5/12

5/14

5/16

5/19

5/21

5/23

5/28

5/30

5.5

7.2

5.7

7.9

6.1

6.6

12.6

6.1

6.7

7.4

9.0

5.7

6.9

18.0

17.5

16.0

18.3

17.2

16.1

18.3

15.3

19.4

20.2

19.1

19.2

3.4

4.8

7.9

6.2

10.9

1.4

1.9

2.8

3.2

9.3

13.2

4.6

4.0

0.7

1.4

6.8

4.1

9.6

2.7

0.6

0.8

0.8

5.0

8.8

1.3

5.3

0.7

0.9

1.9

5.1

11.7

1.2

0.7

0.7

0.5

9.5

4.4

6.5

1.2

0.9

1.0

0.8

4.8

10.6

1.1

0.8

AP

PE

ND

IX P

AG

E A

-8

Ju

ne '

97

Nit

rate

D

ata

Bio

To

wer

#1

Bio

To

wer

#2

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ug

hin

g F

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low

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d F

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S

low

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d

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R

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Eff

luen

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Eff

luen

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flu

ent

Eff

luen

t

6/2

6/4

6/6

6/9

6/11

6/13

6/18

6/20

6/25

6/26

6/29

6.3

5.9

5.4

5.3

5.6

5.5

5.7

5.6

6.2

10.1

5.5

18.5

18.1

18.0

17.9

18.7

18.3

16.7

16.4

18.1

24.8

17.8

6.8

6.1

6.4

4.2

5.6

5.6

7.2

8.5

9.0

5.0

5.5

1.5

1.5

2.8

0.4

1.3

1.1

2.7

5.7

9.0

2.2

2.2

1.4

1.5

4.5

0.7

1.0

3.8

2.0

6.3

7.3

2.9

5.9

0.5

1.4

1.2

1.5

1.6

0.5

1.0

5.6

9.3

3.1

2.5

AP

PE

ND

IX P

AG

E A

-9

••••••••*•••••••••••••••••••••••••••••••••*<

Ju

ly '

97 N

itra

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Dat

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Filt

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E

fflu

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Eff

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luen

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7/9

7/10

7/11

7/14

7/15

7/16

7/18

7/21

7/23

7/25

7/29

7/30

7/31

5.7

6.2

7.4

6.1

7.0

7.0

6.9

7.6

6.4

6.7

6.9

6.9

6.5

26.8

21.2

20.4

20.6

10.0

20.5

21.2

20.6

18.7

21.7

20.8

19.1

18.4

7.1

7.2

7.2

14.1

11.0

9.2

14.1

10.7

9.8

12.0

12.9

11.8

12.5

3.5

3.4

4.0

12.0

8.3

5.7

13.1

7.0

2.5

3.2

5.6

3.8

4.0

3.1

3.3

3.9

13.0

9.3

7.1

12.2

5.9

3.8

5.3

4.3

4.0

3.7

4.7

3.6

5.7

14.6

14.0

9.8

12.9

4.5

2.6

3.8

4.4

3.1

AP

PE

ND

IX P

AG

E A

-10

Au

gu

st

'97 N

itra

te D

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Dat

eB

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2 R

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gh

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and

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E

fflu

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8/4

8/7 8/11

8/13

8/14

8/15

8/18

8/20

8/22

8/27

8/29

6.6

7.3 7.4

7.5 6.8

6.4

6.8

7.0

6.7

7.2 14

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23.0

22.3

23.6

19.6

19.7

20.2

20.9

19.3

21.0

21.2

20.9

12.7

12.2

14.8

13.7

13.3

13.3

13.7

14.2

13.0

13.6

13.1

2.0 6.8

7.2 6.0

5.9

4.8

6.0

5.2 6.7

5.1

5.7

1.6

7.7 6.6

3.8

2.8

6.9

3.8

8.2

2.4

2.5

1.6

3.6 2.7

3.9

4.4 2.5

4.5 2.8

6.4

7.9

AP

PE

ND

IX P

AG

E A

-11

!••••••••••«•

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Sep

tem

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Dat

eB

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fflu

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Eff

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ent

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9/3

9/4

9/5

9/8

9/10

9/15

9/16

9/17

9/18

9/22

9/24

9/26

9/29

10.0

6.4

7.7

6.4

5.6

6.8

6.5

6.5

6.5

6.1

6.0

6.7

6.0

23.5

19.2

20.9

20.0

18.6

20.5

19.0

19.4

19.0

21.0

16.3

19.1

18.4

14.7

10.3

13.9

14.9

13.9

14.9

13.2

13.7

13.1

13.4

9.9

12.4

11.6

9.3

6.0

10.9

11.7

7.4

6.5

6.2

6.7

5.9

5.8

5.5

4.7

3.5

8.4

6.0

10.6

8.5

6.7

6.5

5.6

5.9

4.5

4.1

4.0

2.7

3.1

8.0

6.5

12.4

9.8

7.6

6.7

6.1

5.8

4.9

3.4

4.2

2.5

2.4

AP

PE

ND

IX P

AG

E A

-12

Oc

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'97 N

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Dat

eB

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luen

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10/1

10/6

10/8

10/1

0

10/1

5

10/1

7

10/2

2

10/3

0

6.9

6.8

6.7

6.2

7.2

8.4

6.1

7.8

18.4

20.6

19.9

21.0

23.2

24.3

21.9

23.0

12.0

10.9

14.4

7.0

17.0

17.5

17.4

15.8

4.6

5.3

6.7

7.2

9.6

10.1

8.8

9.8

2.8

6.7

7.3

5.4

6.7

9.3

3.5

9.9

2.5

7.3

5.6

6.0

0.9

5.6

10.5

AP

PE

ND

IX P

AG

E A

-13

••••••••••••••••••••••••••••••••••••••••••I

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'97

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Dat

a

Dat

e R

aw

Raw

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FCS

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Effl

uent

Influ

ent

Effl

uent

5/14

5/16

5/19

5/21

5/23

5/28

5/30

0.0

0.0 0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

2.05

3.62

4.20

2.94

1.23

4.20

3.10

0.71

1.55

3.80

4.84

0.81

3.80

1.73

0.69

1.58

3.77

4.71

1.77

3.63

1.71

0.72

1.43

3.69

4.13

2.22

3.63

1.23

AP

PE

ND

IX P

AG

E A

-14

*••

June

997

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ta

Dat

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2

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g F

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S

low

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d F

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S

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aw

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FC

S

Eff

luen

t E

fflu

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t In

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t E

fflu

ent

6/2

6/4

6/6

6/9

6/11

6/13

6/18

6/20

6/25

6/26

6/29

0,0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

1.74

1.18

0.73

0.23

0.74

0.24

0.10

1.11

2.39

1.51

0.46

1.53

0.96

0.56

0.08

0.92

0.11

0.13

2.20

2.79

1.05

0.42

1.48

0.93

0.59

0.13

1..08

0.31

0.25

2.36

3.11

1.25

1.03

1.00

0.61

0.73

0.0

1.31

0.55

0.55

3.03

3.86

1.32

1.16

AP

PE

ND

IX P

AG

E A

-15

Ju

ly '

97 N

itri

te D

ata

Dat

eB

ioT

ow

er #

1 B

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er #

2 R

ou

gh

ing

Filt

er

Slo

w S

and

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and

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R

aw +

MFC

S

Eff

luen

t E

fflu

ent

Eff

luen

t In

flu

ent

Eff

luen

t

7/9

7/10

7/11

7/14

7/15

7/16

7/18

7/21

7/23

7/25

7/29

7/30

7/31

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

2.10

1.21

2.17

2.39

3.16

2.48

2.44

1.26

1.47

1.69

0.88

0.64

0.50

1.69

0.51

2.13

3.66

4.31

3.94

3.13

4.26

5.25

6.28

1.45

1.07

0.83

1.47

0.39

2.15

3.88

4.02

3.17

2.81

3.74

4.82

6.41

1.57

1.14

0.96

0.46

0.05

0.86

3.77

2.43

1.22

1.59

2.51

5.05

1.54

0.76

0.96

AP

PE

ND

IX P

AG

E A

-16

Au

gu

st

'97 N

itri

te D

ata

Dat

eB

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#1

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er #

2 R

ough

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Filt

er

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w S

and

Filte

r S

low

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R

aw +

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S E

fflue

nt

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E

fflue

nt

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ent

Effl

uent

8/4

8/7

8/11

8/13

8/14

8/15

8/18

8/20

8/22

8/27

8/29

0.0

0.0 0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0 0.0

0.0

0.0 0.0

0.0

0.0

0.0

0.96

0.82

0.72

0.68

0.64

0.65

1.04 1.35

1.41

1.37

1.30

1.73

1.19

1.31

1.58

1.53

1.64

1.82

1.65

1.79

1.88

1.52

1.27

0.95

1.75

1.43

1.22

1.69

1.91

2.37

2.42

2.10

0.94

0.95

1.43

1.12

1.11

1.34

1.05

1.23

1.47

1.49

AP

PE

ND

IX P

AG

E A

-17

*•••••••••••••••••

Se

pte

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'97 N

itri

te D

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Dat

eB

ioT

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1 B

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Filt

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and

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S

Eff

luen

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Eff

luen

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Eff

luen

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9/3

9/4

9/5

9/8

9/10

9/15

9/16

9/17

9/18

9/22

9/24

9/26

9/29

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.43

0.18

0.51

0.31

0.40

0.74

0.52

0.58

0.50

0.43

0.26

0.43

0.45

0.16

0.20

0.79

0.94

0.84

1.00

0.78

0.92

0.72

0.60

0.62

0.70

0.67

0.38

0.23

0.95

1.06

1.00

1.04

0.41

0.95

0.76

0.96

0.95

1.33

0.73

0.00

0.00

0.09

0.26

0.30

0.89

0.86

1.01

1.00

1.02

0.83

0.98

0.49

AP

PE

ND

IX P

AG

E A

-18

••••••••••••••I

Oc

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Dat

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Filt

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and

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S

Eff

luen

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luen

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10/1

10/6

10/8

10/1

0

10/1

5

10/1

7

10/2

2

10/3

0

0.0

0.0

0.0 0.0

0.0

0.0

0.0

0.0

0.0

0,0

0.0 0.0

0.0

0.0

0.0

0.0

0.45

0.56

0.47

5.26

0.59

0.85

0.33

0.92

0.59

0.62

0.73

0.95

1.62

1.66

1.38

0.69

1.10

0.73

1.15

1.14

1.77

2.12

1.80

0.44

0.78

0.94

0.56

0.71

0.24

0.54

AP

PE

ND

IX P

AG

E A

-19

No

ve

mb

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t E

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11/1

11/3

11/4

11/5

11/6

11/8

11/1

1

11/1

3

11/1

5

11/1

8

11/1

9

11/2

0

11/2

1

11/2

2

11/2

5

11/2

6

11/2

7

0.5 1.0

0.7 1.1

1.3

1.0

1.3

0.9 1.2

0.7

0.8 1.1

1.0

1.0

0.7

0.8

2.0

24.0

16.8

16.1

12.0

12.6

11.9

12.1

10.3

11.1

11.9

12.6

13.5

11.7

11.9

12.2

12.9

14.3

12.6

8.7 11

.0

8.7

8.4

5.4

5.2

6.9 6.6

7.1

7.8

6.9 6.7

7.5

6.6 11

.2

8.4

9.8 6.1

8.8

5.0

6.6

4.0 3.8

5.1 5.0

4.8

4.8

5.6

4.9

7.0

5.0 12

.7

6.5

8.4

4.7

7.3

4.4

4.1 4.2

5.6 5.6

4.6 4.5

4.7

4.9

6.0

4.5

5.4

6.4

AP

PE

ND

IX P

AG

E A

-20

Decem

ber

'96

DO

C D

ata

Dat

e R

aw

Raw

+ M

FCS

Bio

Tow

er #

1E

fflue

ntB

ioTo

wer

#2

Effl

uent

Rou

ghin

g F

ilter

S

low

San

d F

ilter

S

low

San

d F

ilter

Effl

uent

In

fluen

t E

fflue

nt

12/4

12/5

12/9

12/1

1

12/1

2

12/1

6

12/1

8

12/1

9

12/2

3

12/2

7

12/3

0

0.9

0.9

0.9

0.5 2.0 1.6

0.7

1.1

1.1

1.5

0.7

2.2

8.4

5.8

2.6

7.7

14.6

6.8

14.1

9.7

17.7

19.4

2.4 11

.5

7.1 8.6 11.1

4.3

8.9 20.4

18.1

22.4

32.2

2.6

2.1

4.4

3.7 3.1

5.3

4.8 17.6

4.0 29.0

20.0

1.7

2.6

2.6

2.1

2.6

2.9

3.8

3.7 14.0

9.2 36.8

AP

PE

ND

IX P

AG

E A

-21

Ja

nu

ary

'97 D

OC

Da

ta Bio

To

wer

4D

ate

Raw

R

aw +

MFC

S

Eff

luen

tB

ioT

ow

er #

2 R

ou

gh

ing

Filt

er

Slo

w S

and

Filt

er

Slo

w S

and

Filt

erE

fflu

ent

Eff

luen

t In

flu

ent

Eff

luen

t

1/2

1/3

1/7

1/8

1/9

1/13

1/16

1/19

1/20

1/22

1/23

1/28

1/29

1/31

0.7

1.1

0.9

0.7

0.7

0.8

0.8

1.0

1.0

1.9

1.9

2.8

2.1

16.3

19.9

22.4

17.7

20.8

25.7

24.6

34.6

36.8

76.6

69.7

65.8

54.0

42.7

12.0

18.4

19.7

16.2

16.1

23.0

23.0

28.1

29.8

66.9

61.2

59.3

46.4

42.1

19.2

13.3

16.4

7.2

22.2

20.7

20.3

24.6

25.8

62.3

62.1

53.7

46.7

38.0

14.2

5.15

10.3

14.4

20.4

21.6

20.8

24.7

25.8

62.6

56.1

50.1

48.8

36.1

AP

PE

ND

IX P

AG

E A

-22

Feb

ruary

'97

DO

C D

ata

Dat

eB

ioT

ow

er #

1R

aw

Raw

+ H

FCS

E

fflu

ent

Bio

Tow

er #

2E

fflu

ent

Ro

ug

hin

g F

ilter

S

low

San

d F

ilter

S

low

San

d F

ilter

Eff

luen

t In

flu

ent

Eff

luen

t

2/3

2/6

2/7

2/10

2/11

2/16

2/17

2/18

2/19

2/24

2/27

2/28

1.7

2.1

2.8

2.8

1.5

2.1

1.7

1.6

2.6

1.4

1.8

1.5

29.5

59.5

66.8

61.0

54.7

5.0

34.9

43.7

44.8

27.2

61.7

54,4

21.1

50.4

53.0

47.2

42.3

4.1

27.7

16.4

39.8

28.3

50.3

42.8

17.4

57.3

48.7

41.8

40.7

3.5

29.6

19.9

34.9

26.2

43.0

34.0

13.8

45.7

45.1

47.3

1.8

24.4

31.1

28.1

18.4

27.4

34.0

AP

PE

ND

IX P

AG

E A

-23

Marc

h '

97

DO

C D

ata

Bio

To

wer

#1

Bio

To

wer

#2

Ro

ug

hin

g F

ilter

S

low

San

d F

ilter

S

low

San

d F

ilter

Dat

e R

aw

Raw

+ M

FCS

E

fflu

ent

Eff

luen

t E

fflu

ent

Infl

uen

t E

fflu

ent

3/4

3/10

3/11

3/17

3/19

3/21

3/24

3/25

3/28

3/31

2.0

2.0

2.4

2.1

2.6

2.4

2.9

2.2

2.2

2.0

39.3

45.4

64.3

71.9

82.8

51.1

51.9

55.5

9.3

77.5

24.3

34.7

46.0

70.7

76.4

45.5

36.7

41.5

8.2

59.2

26.1

33.0

37.2

54.5

79.9

37.5

21.8

26.9

7.1

13.6

26.0

30.7

36.7

51.9

71.6

29.9

19.3

17.9

7.3

14.9

AP

PE

ND

IX P

AG

E A

-24

Ap

ril

'97

DO

C D

ata

Dat

e R

aw

Raw

+ H

FC

SB

ioT

ower

#1

Effl

uent

Bio

Tow

er #

2E

fflue

ntR

ough

ing

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r S

low

San

d F

ilter

S

low

San

d Fi

lter

Effl

uent

In

fluen

t E

fflue

nt

4/2

4/4

4/7

4/9

4/12

4/15

4/16

4/17

4/21

4/22

4/23

4/25

4/28

4/29

4/30

2.8

2.8

2.8

3.8

3.1

1.8

2.2

2.3 1.9

2.2

2.8

2.9

2.0 1.8

2.0

4.8 9.3

95.4

84.2

42.9

45.5

52.5

49.9

40.9

33.5

36.2

35.0

39.5

51.9

53.9

, , —

• •

5.2 25.7

48.4

51.7

12.9

24.6

28.6

24.8

14.1

14.2

12.4

10.7

12.3

18.4

16.1

5.8

6.7

19.7

25.0

41.0

15.8

14.6

15.8

15.1

9.6

9.8

8.3 6.7

5.6

12.8

10.3

17.6

19.2

33.4

14.0

13.3

15.7

12.5

8.4

6.8 15.2

8.6

4.8 11

.5

8.6

9.7

6.5

3.1

2.9

AP

PE

ND

IX

PA

GE

A-2

5

Ma

y '

97

DO

C D

ata

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e R

aw

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FCS

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Eff

luen

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g F

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low

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d F

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S

low

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d F

ilter

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luen

t In

flu

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Eff

luen

t

5/1

5/2

5/14

5/16

5/19

5/21

5/28

5/30

2.5

2.7

2.4

3.6

3.7

2.8

2.4

2.7

51.2

18.5

30.8

43.2

36.8

30.8

35.5

40.9

16.6

5.5

10.9

12.5

13.8

17.6

15.4

16.3

11.1

3.0

8.7

4.3

4.6

7.3

5.1

7.5

3.6

7.0

7.6

5.3

4.2

4.7

6.5

3.5

8.0

4.0

8.0

4.1

3.5

4.2

3.3

7.9

3.3

4.7

2.9

3.0

AP

PE

ND

IX P

AG

E A

-26

Ju

ne '

97

DO

C D

ata

Dat

e R

aw

Raw

+ H

FC

SB

ioT

ow

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6/4

6/9

6/11

6/18

6/20

6/25

6/26

6/27

6/29

2.9

2.0

1.8

2.1

2.5

1.5

3.5

3.1

2.6

36.8

28.2

27.5

42.4

28.1

30.1

30.6

36.6

29.1

16.6

5.7

6.9

14.3

13.6

12.8

12.8

12.6

11.1

5.8

5.6

3.8

5.2

5.0

9.8

3.7

4.4

3.8

4.6

4.6

3.8

4.4

6.1

6.0

4.3

4.2

4.2

4.3

3.8

4.1

4.2

3.7

2.9

3.7

3.6

3.6

3.1

3.2

2.8

3.0

5.4

3.0

3.5

3.2

3.4

••••••••••••••••I

Ro

ug

hin

g f

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r S

low

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d F

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S

low

San

d F

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Eff

luen

i In

flu

ent

Eff

luen

t

AP

PE

ND

IX P

AG

E A

-27

Ju

ly '

97

DO

C D

ata

Bio

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er *

Dat

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aw

Raw

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fflu

ent

Bio

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wer

#2

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ug

hin

g Fi

lter

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and

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low

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d Fi

lter

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luen

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fflu

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Infl

uent

E

fflu

ent

7/9

7/10

7/11

7/14

7/15

7/16

7/21

7/23

7/25

7/29

7/30

7/31

1.9

1.6

1.9

2.5

2.4

2.3

2.4

3.0

3.0

3.1

2.3

2.2

32.9

31.8

16.4

14.7

18.0

23.0

32.2

27.4

25.4

35.0

33.7

35.5

11.1

11.0

6.8

5.1

7.9

8.3

16.8

15.6

17.0

19.8

20.1

21.5

2.9

2.1

2.9

2.9

4.0

4.9

5.4

5.7

5.9

9.5

8.5

11.1

2.6

1.9

2.4

5.3

3.3

4.0

4.0

5.6

5.7

7.4

7.0

8.3

2.2

2.0

2.5

5.3

2.8

3.4

3.4

3.5

6.1

9.9

6.1

2.1

1.6

2.6

5.3

2.8

2.2

3.2

3.2

4.0

4.0

3.7

AP

PE

ND

IX P

AG

E A

-28

Au

gu

st 9

97 D

OC

Data

••••I

Dat

e R

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tB

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ow

er #

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S

low

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d F

ilter

S

low

San

d F

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Eff

luen

t E

fflu

ent

Eff

luen

t

8/4

8/7

8/11

8/13

8/14

8/15

8/20

8/22

8/27

8/29

2.7

2.5

3.5

1.7

2.0

3.5

1.5

1.4

4.1

1.2

32.7

29.3

30.2

31.9

31.3

33.6

29.8

30.0

33.9

34.6

19.6

18.8

19.9

19.2

20.5

20.0

19.1

18.1

20.6

25.2

5.7

5.5

9.6

7.5

8.9

7.5

6.3

6.7

7.2

6.6

6.1

4.1

5.7

5.3

6.2

6.0

4.1

7.9

6.8

3.9

5.1

3.9

5.7

5.7

5.8

4.2

3.4

3.9

3.3

4.3

3.1

3.6

3.5

2.5

2.2

2.2

AP

PE

ND

IX P

AG

E A

-29

•••••••••••••••••••ft*

Se

pte

mb

er

'97 D

OC

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ta

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aw

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and

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luen

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9/4 9/5

9/8

9/10

9/15

9/16

9/17

9/18

9/22

9/24

9/26

9/29

3.1 3.7 1-7

1.7

1.7

1.9

1.6

1.5

1.2

1.7

1.5

1.6

31.9

31.0

34.9

35.2

33.8

35.4

34.4

35.5

37.8

32.6

32.4

41.4

16.9

20.6

22.0

21.2

21.2

22.0

20.9

21.1

20.8

20.6

20.8

27.4

4.4 11

.0

9.7 8.4

6.6 6.8

7.3

6.7

9.4

7.4

6.8

10.7

4.3 6.6 12.7

4.6

6.1 5.8

5.0

4.3

4.1

4.7

5.0

7.1

4.1 6.6

5.3 4.3

4.7

4.7

4.7

4.9 4.6

4.3 4.8

5.8

2.4 3.3

2.7

2.3

3.1

2.9

2.7

2.8 2.6

2.2

2.5

4.4

APPENDIX PAGE A-30

•••••*••••••••**•••••••*•*•••••

Oc

tob

er

'97

DO

C D

ata

Dat

e R

aw

Raw

+ M

FCS

Bio

To

wer

#1

Eff

luen

tB

ioT

ow

er #

2E

fflu

ent

Ro

ug

hin

g F

ilter

S

low

San

d F

ilter

S

low

San

d F

ilter

Eff

luen

t In

flu

ent

Eff

luen

t

10/1

10/6

10/8

10/1

5

10/1

7

10/2

2

10/3

0

1.4

1.1

1.2

1.4

2.1

2.2

2.1

35.2

37.9

41.3

39.0

31.3

40.4

39.0

24,3

18.1

26.0

25.9

24.2

31.6

29.6

10.4

16.5

11.9

13.4

10.5

15.8

12.7

4.0

3.7

5.1

9.4

7.5

6.5

7.1

6.5

4.9

6.2

10.4

9.0

12.7

5.9

2.2

1.7

2.2

2.9

3.2

3.5

3.2

AP

PE

ND

IX P

AG

E A

-31

•••»••••••••••••••<

No

ve

mb

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11/1

11/3

11/4

11/5

11/6

11/8

11/1

1

11/1

3

11/1

5

11/1

8

11/1

9

11/2

0

11/2

1

11/2

2

11/2

5

11/2

6

11/2

7

5.2

5.3

4.6

2.8

2.6

5.7

5.0

1.9

3.6

3.7

1.7

5.4

5.2

1.9

7.6

2.3

4.7

6,0

5.8

4.7

2.8

2.3

5.9

5.1

1.9

3.6

3.7

1.7

5.5

5.6

1.8

8.0

2.2

4.7

1.0

1.2

0.6

0.4

0.5

0.7

0.7

0.5

0.6

0.6

0.5

1.1

0.9

0.5

1.6

0.5

0.7

0.4

0.3

0.5

0.3

0.4

0.4

0.5

0.5

0.4

0.4

0,4

0.5

0.4

0.4

0.7

0.4

0.5

8.6

8.3

8.6

8.1

8.5

8.7

8.9

8.8

8.6

8.4

8.4

8.6

8.7

8.6

8.8

8.7

8.6

8.6

8.2

8.6

8.0

8.4

8.8

9.0

9.0

8.8

8.4

8.6

8.6

3.9

4.6

5.8

5.4

5.1

5.2

5.1

4.7

4.4

4.5

4.5

4.6

4.3

4.3 4.2

AP

PE

ND

IX P

AG

E A

-32

Decem

ber

'96

Dis

so

lved

Oxyg

en

Da

ta

Dat

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12/4

12/5

12/9

12/1

1

12/1

2

12/1

6

12/1

8

12/1

9

12/2

3

12/2

7

12/3

0

4.3

2.3

2.6

5.2

2.5

1.8

2.3

4.2

4.9

3.9

2.0

4.4

2.0

2.3

5.0

2.2

1.8

2.2

4.1

5.0

3.0

1.8

• —

_1.

0

0.5

0.4

0.6

0.6

0.4

0.6

1.2

1.7

1.0

0.5

.

•0.

8

0.6

0.5

0.8

0.7

0.6

0.5

0.9

0.9

0.7

0.7

8.4

8.4

8.4

8.4

8.4

8.3

8.5

8.5

8.4

8.3

8.4

r '

8.3

8.4

.

• —3.

6

3.3

4.5

4.5

i

AP

PE

ND

IX P

AG

E A

-33

Jan

uary

'9

7 D

isso

lved

Oxyg

en

Data

Dat

eB

ioTo

wer

#1

Bio

Tow

er #

2 R

ough

ing

Filt

er

Slo

w S

and

Filt

er

Slo

w S

and

Fi

lter

Raw

R

aw +

MFC

S

Eff

luen

t E

fflu

ent

Eff

luen

t In

flu

ent

Eff

luen

t

1/2

1/3

1/7

1/8

1/9

1/13

1/16

1/19

1/20

1/22

1/23

1/28

1/29

1/31

2.3

3.9

4.9

6.0

2.0

2.8

5.0

5.3

3.9 5.5

6.0 3.9

6.0

5.7

2.3

3.8

4.8

6.0

1.8

2.8

3.7

5.3

3.8

5.5

6.1

3.9

6.0

5.7

0.7 0.9

1.6

2.1 0.5

0.7 0.1

2.1

1.3

2.1

2.3

2.2

3.7

2.3

0.7

0.8

0.1

1.1

0.6

0.7 0.4 1.1

0.8 1.2

1.4

1.6

2.9 1.5

8.4

8.2

8.3

8.5

8.4

8.4

8.4

8.4

8.5 8.4

8.4

8.5

8.5

8.3

4.4 4.2

4.1

3.7 3.7

3.5 3.4

AP

PE

ND

IX P

AG

E A

-34

Feb

ruary

'9

7 D

isso

lved

Oxyg

en

Da

ta

Dat

eB

ioTo

wer

#1

Bio

To

wer

#2

Rou

ghin

g F

ilter

S

low

San

d F

ilter

S

low

San

d

Filte

rR

aw

Raw

+ M

FCS

E

fflu

ent

Eff

luen

t E

fflu

ent

Influ

ent

Eff

luen

t

2/3

2/6

2/7 2/10

2/11

2/16

2/17

2/18

2/19

2/24

2/27

2/28

2.4

4.3 2.1

2.5 4.6

2.0

2.0 1.8

3.7

2.3

3.6

4.7

2.0

4.2

2.0

2.4 4.6

1.8

1.8

1.6

3.6

1.9

3.7

4.1

0.6

0.8

0.6

0.6 1.5

0.6

0.5

0.5 1.0

0.6 1.5

1.9

0.6

0.7

0.6

0.6 1.0

0.6

0.4

0.4

0.5

0.4 1.2

1.2

8.4

8.4

8.4

8.4 8.4

8.5

8.4

8.5 8.6

8.6

8.3

8.3

AP

PE

ND

IX P

AG

E A

-35

Marc

h *

97 D

isso

lved

Ox

yg

en

Da

ta

Dat

eB

ioT

ow

er #

1 B

ioT

ow

er #

2 R

ough

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Filt

er

Slo

w S

and

Filt

er

Slo

w S

and

Fi

lter

Raw

R

aw +

MFC

S

Eff

luen

t E

fflu

ent

Eff

luen

t In

flu

ent

Eff

luen

t

3/4

3/6

3/7

3/10

3/11

3/17

3/19

3/21

3/24

3/25

3/28

3/31

4.3

3.3

4,2

2.3

2.5

2.8

2.3

2.0

2.2

2.2

2.2

2.1

4.5

3.1

4.2

2.1

2.0

2.4

2.1

1.7

1.7

1.7

1.9

1.8

2.6

1.5

2.0

0.8

0.7

1.5

1.0

0.7

0.5

0.7

0.6

0.4

1.4

0.9

1.1

0.5

0.4

1.1

0.4

0.3

0.3

0.3

0.4

0.3

8.5

8.3

8.4

8.3

8.3

8.2

7.8

7.8

7.2

7.6

7.8

7.8

AP

PE

ND

IX

PA

GE

A-3

6

Ap

ril

'97

Dis

so

lve

d O

xy

ge

n D

ata

Dat

eB

ioT

ow

er#

1 B

ioT

ow

er #

2 R

ou

gh

ing

Filt

er

Slo

w S

and

Filt

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Slo

w S

and

F

ilter

Raw

R

aw +

MFC

S

Eff

luen

t E

fflu

ent

Eff

luen

t In

flu

ent

Eff

luen

t

4/2

4/4

4/7

4/9

4/12

4/15

4/16

4/17

4/21

4/22

4/23

4/25

4/28

4/29

4/30

2.2

2.0

1.8

5.1

1.8

1.8

1.8

4.9

0.5

0.4

0.3

0.5

0.4

0.3

0.2

0.4

8.1

7.9

8.1

7.8

NO

DA

TA

AP

PE

ND

IX P

AG

E A

-37

•••••••••••••••••••••••••••••••••••••••••••I

May '

97

Dis

solv

ed O

xyg

en D

ata

Dat

eB

ioT

ow

er#1

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ioT

ow

er #

2 R

ou

gh

ing

Filt

er

Slo

w S

and

Filt

er

Slo

w S

and

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erR

aw

Raw

+ H

FCS

E

fflu

ent

Eff

luen

t E

fflu

ent

Infl

uen

t E

fflu

ent

5/1

5/2

5/5

5/6

5/7

5/14

5/16

5/19

5/21

5/23

5/27

5/28

5/30

2.3

2.3

1.8

1.8

3.4

4.0

4.9

5.1

2.1

2.0

1.5

1.7

3.1

3.7

5.0

5.1

0.5

0.6

0.5

0.5

0.4

0.2

0.3

0.4

NO

DA

TA

0.5

0.6

0.5

0.3

0.4

0.4

0.5

0.5

6.9

6.9

7.6

8.6

8.6

8.1

8.2

7.8

7.1

7.1

7.6

8.3

8.8

7.4

7.5

6.8

3.7

3.7

4.2

4.3

4.5

3.8

3.9

3.7

AP

PE

ND

IX P

AG

E A

-38

June

'9

7 D

iss

olv

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ta (

mg

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Dat

eB

ioT

ow

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and

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and

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R

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S

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luen

t E

fflu

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Eff

luen

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flu

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Eff

luen

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6/2

6/4

6/6

6/9

6/11

6/13

6/18

6/20

6/25

6/26

6/27

6/29

2.0

1.9

4.1

4.3

4.9

4.8

4.1

2.1

5.1

1.9

4.1

1.7

1.8

1.7

4.0

4.2

4.9

4,7

4,1

1.9

5.1

1.6

3.9

1.5

0.4

0.4

0.4

0.4

0.4

0.5

0.6

0.4

0.4

0.4

0.4

0.4

0.5

0.5

0.5

0.6

0.5

0.6

0.6

0.7

0.7

0.6

0.6

0.6

7.8

7.9

8.0

7.3

7.5

7,5

7.1

7,4

7.6

7.7

7.8

7.3

6.8

6.9

7.6

6.5

7.5

7.5

7.2

7.4

7.7

7.8

7.8

7.4

3.6

3.6

3.9

3.8

3.9

3.8

3.4

3.5

4.0

4.0

4.3

3.7

AP

PE

ND

IX P

AG

E A

-39

Ju

ly '

97

Dis

so

lve

d O

xy

ge

n D

ata

Dat

eB

ioT

ow

er #

1 B

ioT

ow

er #

2 R

ou

gh

ing

Filt

er

Slo

w S

and

Filt

er

Slo

w S

and

Filt

erR

aw

Raw

+ H

FC

S

Eff

luen

t E

fflu

ent

Eff

luen

t In

flu

ent

Eff

luen

t

7/9

7/10

7/11

7/14

7/15

7/16

7/18

7/21

7/23

7/25

7/29

7/30

7/31

2.9

3.0

1.9

2.2

2.2

1.9

1.9

4.0

3.1

2.1

4.3

3.5

4.3

2.8

2.7

1.7

2.0

1.8

1.5

1.5

3.9

3.1

1.9

4.2

2.9

4.2

0.5

0.5

0.4

0.7

0.7

0.6

0.6

0.9

0.9

0.7

1.1

1.1

1.5

0.7

0.7

0.7

0.7

0.7

0.8

0.6

0.7

0.7

0.6

0.8

0.8

0.8

8.4

8.4

8.3

9.8

9.6

9.2

8.2

8.0

7.8

7.9

7.9

7.4

7.3

8.2

8.2

8.3

9.4

9.5

9.3

8.0

7.3

6.8

8.0

7.7

7.4

3.6

3.9

3.7

4.1

4.3

4,2

3.8

3.6

3.4

3.7

3.7

3.6

AP

PE

ND

IX P

AG

E A

-40

Au

gu

st '

97 D

isso

lved

Oxy

gen

Dat

a

Dat

eB

ioT

ow

er #

1 B

ioT

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er #

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er

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and

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and

F

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Raw

R

aw +

MFC

S

Eff

luen

t E

fflu

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Eff

luen

t In

flu

ent

Eff

luen

t

8/4

8/7

8/11

8/13

8/14

8/15

8/18

8/20

8/22

8/27

8/29

3.6

5.0

2.7

1.8

3.6

5.1

2.6

1.7

2.5

4.8

2.1

1.4

1.4

1.8

5.8

1.1

1.9

1.1

0.6

0.9

1.8

0.7

0.5

0.7

0.6

2.2

0.5

0.7

0.6

0.6

0.6

0.7

0.5

0.6

0.7

0.7

0.8

6.4

6.2

6.1

5.5

6.0

5.8

5.8

5.9

5.1

3.1

2.7

6.6

7.5

5.2

5.3

6.2

5.9

6.7

6.2

5.4

4.6

3.7

3.0

3.9

3.2

3.7

3.5

3.7

3.7

3.7

3.6

AP

PE

ND

IX P

AG

E A

-41

Se

pte

mb

er

'97

Dis

so

lved

Ox

yg

en

Da

ta

Dat

eB

ioT

ow

er #

1 B

ioT

ow

er #

2 R

ou

gh

ing

Filt

er

Slo

w S

and

Filt

er

Slo

w S

and

F

ilter

Raw

R

aw +

MFC

S

Eff

luen

t E

fflu

ent

Eff

luen

t In

fluen

t E

fflu

ent

9/2

9/3

9/4

9/5

9/8

9/10

9/15

9/16

9/18

9/22

9/24

9/26

9/29

3.6

4.9

4.5

3.6

6.1

5.9

1.7

3.5

3.4

4.2

3.9

3.6

5.7

1.7

1.7

1.7

1.8

3.1

3.0

0.7

1.7

1.6

2.1

1.8

1.8

3.0

0.7

0.6

0.8

1.0

0.9

1.1

0.5

0.7

0.6

0.6

0.6

0.6

0.7

8.0

8.0

8.0

7.9

7.6

7.2

6.6

6.1

5.7

3.9

3.4

3.7

8.2

8.1

8.1

8.4

8.3

8.1

7.8

6.9

7.2

6.3

6.2

6.2

7.7

4.6

4.8

4.1

3.9

3.8

4.2

4.3

3.9

3.3

3.8

3.7

3.5

AP

PE

ND

IX P

AG

E A

-42

••••••••*••••••••••••••••

Oc

tob

er

'97

Dis

solv

ed O

xyg

en D

ata

Dat

eB

ioT

ow

er#1

B

ioT

ow

er#

2 R

ou

gh

ing

Filt

er

Slo

w S

and

Filt

er

Slo

w S

and

Fi

lter

Raw

R

aw +

MFC

S

Eff

luen

t E

fflu

ent

Eff

luen

t In

flu

ent

Eff

luen

t

10/1

10/6

10/8

10/1

0

10/1

4

10/1

7

10/2

2

10/2

8

10/3

0

10/3

1

4.6

5.6

5,8

4.5

5.5

1.7

4.8

2.0

1.5

1.7

2.4

3.1

3.2

2.5

2.7

1.2

3.1

1.2

0.9

1.0

0.6

0.9

0.8

0.5

0.6

0.4

0.7

0.3

0.3

0.3

8.0

7.8

7.8

7.0

6.9

6.4

4.2

2.6

8.4

8.2

8.1

8.2

8.0

7.2

6.7

7.0

5.5

3.6

8.4

8.4

3.8

3.8

3.8

3.8

3.3

2.7

2.5

3.1

3.6

3.6

AP

PE

ND

IX P

AG

E A

-43

No

vem

ber

'96 p

H D

ata

Dat

eB

ioT

ow

er #

1 B

ioT

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er #

2 R

ou

gh

ing

Filt

er

Slo

w S

and

Filt

er

Slo

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and

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+ M

FCS

E

fflu

ent

Eff

luen

t E

fflu

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Eff

luen

t

11/1

11/8

11/1

1

11/1

3

11/1

5

11/1

9

11/2

1

11/2

2

11/2

5

11/2

6

11/2

7

7.21

7.19

7.36

7.28

7.22

7.24

7.28

7.20

7.27

7.22

7.21

7.23

7.21

7.36

7.30

7.28

7.20

7.28

7.20

7.26

7.20

7.19

7.09

7.19

7.15

7.15

7.13

7.08

7.09

7.10

7.03

7.09

7.07

7.05

7.04

7.19

7.12

7.11

7.06

7.06

7.10

7.00

7.08

7.03

7.84

7.89

7.97

7.86

7.83

7.85

7.86

7.77

7.80

7.79

7.70

7.88

7.89

7.97

7.87

7.86

7.81

7.46

7.47

7.43

7.40

7.38

7.58

7.62

7.53

7.49

7.42

AP

PE

ND

IX P

AG

E A

-44

Decem

ber

'96 p

H D

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Dat

eB

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#1

B

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ing

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er

Slo

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and

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and

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FCS

E

fflu

en

t E

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nt

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uent

In

fluent

Effl

uent

12/4

12/5

12/9

12/1

1

12/1

2

12/1

6

12/1

8

12/1

9

12/2

3

12/2

7

12/3

0

7.28

7.08

7.22

7.26 7.22

7.23

-7.2

3

7.29

7,33

7,27

7.24

7.30

7.06

7.21

7.24

7.20

7.20

7.20

7.29

7.32

7.27

7.25

7.16

6,99

7.10

7.06

7.12

7.11

7.13

7.16

7.19

7.17

7.17

7.16

6.97

7.1o

7.05

7.09

7.13

7.09

7.13

7.17

7.14

7.16

7.89

7.68

7.87

7.77

7.84

7.95

7.78

7.82

7.88

7.86

7.79

7.87

7.84

7.52

7.33

7.55

7.54

AP

PE

ND

IX P

AG

E A

-45

Jan

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'9

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Dat

eB

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g F

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S

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Eff

luen

t E

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Eff

luen

t In

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Eff

luen

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1/2

1/3

1/7

1/8

1/9

1/13

1/16

1/19

1/20

1/22

1/23

1/28

1/29

1/31

7.31

7.23

7.25

7.21

7.24

7.21

7.25

7.28

7.27

7.30

7.27

7.27

7.29

7.26

7.26

7.22

7.27

7.21

7.23

7.22

7.25

7.26

7.27

7.31

7.30

7.29

7.29

7.28

7.18

7.13

7.15

7.11

7.15

7.12

7.14

7.12

7.17

7.15

7.13

7.20

7.19

7.15

7.16

7.10

7.08

7.09

7.14

7.11

7.13

7.08

7.15

7.13

7.10

7.17

7.15

7.11

7.81

7.80

7.84

7.76

7.78

7.84

7.82

7.82

7.75

7.78

7.76

7.86

7.78

7.74

7.46

7.45

7.46

7.39

7.37

7.32

7.35

AP

PE

ND

IX P

AG

E A

-46

Fe

bru

ary

'97

pH

Da

ta

Dat

eB

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wer

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low

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low

San

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R

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S

Eff

luen

t E

fflu

ent

Eff

luen

t In

flu

ent

Eff

luen

t

2/3

2/6

2/7 2/10

2/11

2/16

2/17

2/18

2/19

2/24

2/27

2/28

7.26

7.30

7.27

7.26

7.30

7.26

7.25

7.27

7.28

7.38

7.24

7.28

7.25

7.31

7.26

7.27

7.32

7.26

7.25

7.29

7.30

7.38

7.27

7.28

7.13

7.11

7.12

7.13

7.15

7.22

7.13

7.15

7.15

7.27

7.15

7.16

7.11

7.07

7.08

7.12

7.12

7.21

7.10

7.11

7.09

7.23

7.11

7.12

7.74

7.81

7.77

7.80

7.78

7.82

7.76

7.83

7.79

7.90

7.70

7.72

AP

PE

ND

IX P

AG

E A

-47

Marc

h'9

7 p

H D

ata

•••••»

••••••*•••••<

Bio

To

wer

#1

Bio

To

we

r#2

Ro

ug

hin

g F

ilter

S

low

San

d F

ilter

S

low

San

d

Filt

erD

ate

Raw

R

aw +

MFC

S

Eff

luen

t E

fflu

ent

Eff

luen

t In

flu

ent

Eff

luen

t

3/4

3/6

3/7

3/10

3/11

3/17

3/19

3/21

3/24

3/25

3/28

3/31

7.28

7.26

7.30

7.27

7.31

7.28

7.18

7.20

7.23

7.24

7.20

7.33

7.30

7.28

7.32

7.27

7.31 7.27

7.18

7.19

7.23

7.23

7.20

7.33

7.21

7.2

7.2

7.18

7.21

7.2

7.14

7.03

7.03

7.03

7.08

7.16

7.18

7.15

7.15

7.13

7.17

7.26

7.05

6.96

6.95

6.95

7.10

7.14

7.74

7.73

7.65

7.67

7.71

7.71

7.99

7.90

7.83

7.80

7.87

7.96

AP

PE

ND

IX P

AG

E A

-48

Ap

ril

'97 p

H D

ata

Dat

eB

ioTo

wer

#1

Bio

Tow

er #

2 R

ough

ing

Filte

r S

low

San

d Fi

lter

Slo

w S

and

Filte

rR

aw

Raw

+ H

FCS

E

fflu

ent

Eff

luen

t E

fflu

ent

Influ

ent

Eff

luen

t

4/2

4/4

4/7

4/9

4/12

4/15

4/16

4/17

4/21

4/22

4/23

4/25

4/28

4/29

4/30

7.34

7.30

7.28

7.27

7.26

7.28

7.27

7.32

7.28

7.34

7.33

7.30

7.28

7.27

7.31

7.32

7.28

7.30

7.34

7.28

7.32

7.28

7.32

7.29

7.34

7.34

7.28

7.30

7.26

7.31

7.25

7.02

7.05

6.85

6.97

7.12

7.08

7.10

7.09

7.12

7.11

7.11

7.10

7.01

7.06

7.23

6.94

7.10

6.74

6.93

7.09

7.06

7.06

7.06

7.10

7.07

7.10

7.08

6.97

7.01

7.94

7.86

7.95

7.78

7.80

7.66

7.66

7.66

7.66

7.56

7.59

7.52

7.47

7.26

7.40

7.44

7.44

7.42

7.42

AP

PE

ND

IX P

AG

E A

-49

Ma

y '

97

pH

Data

Dat

eB

ioT

ow

er #

1 B

ioT

ow

er #

2 R

ou

gh

ing

Filt

er

Slo

w S

and

Filt

er

Slo

w S

and

F

ilter

Raw

R

aw +

HF

CS

E

fflu

ent

Eff

luen

t E

fflu

ent

Infl

uen

t E

fflu

ent

5/1

5/2

5/5

5/6

5/7

5/12

5/14

5/16

5/19

5/21

5/23

5/27

5/28

5/30

7.29

7.28

7.26

7.27

7.33

7.30

7.25

7.28

7.25

7.29

7.25

7.26

7.30

7.32

7.27

7.34

7.25

7.25

7.32

7.29

7.27

7.27

7.25

7.29

7.26

7.29

7.33

7.33

7.06

7.15

7.07

7.08

7.27

7.05

7.08

7.08

7.07

7.12

7.16

7.03

7.08

7.03

7.05

7.13

7.06

7.08

7.28

7.07

7.08

7.08

7.07

7.09

7.17

7.03

7.14

7.05

7.40

7.44

7.46

7.42

7.53

7.41

7.47

7.51

7.60

7.64

7.71

7.57

7.56

7.50

7.41

7.53

7.54

7.50

7.61

7.50

7.52

7.53

7.56

7.54

7.64

7.42

7.61

7.48

7.46

7.46

7.48

7.46

7.54

7.44

7.44

7.44

7.45

7.41

7.46

7.34

7.53

7.40

AP

PE

ND

IX P

AG

E A

-50

June '97

pH

Da

ta

Bio

To

wer

#1

Bio

To

wer

#2

Ro

ug

hin

g F

ilter

Dat

e R

aw

Raw

+ M

FCS

E

fflu

ent

Eff

luen

t E

fflu

ent

Slo

w S

and

Filte

rIn

flu

ent

Slo

w S

and

Filt

erE

fflu

ent

6/2 6/4

6/6

6/9

6/11

6/13

6/18

6/20

6/25

6/26

6/27

6/29

7.27

7.27

7.34

7.36

7.30

7.31

7.33

7.29

7.27

7.28

7.22

7.25

7.26

7.24

7.33

7.34

7.29

7.29

7.33

7.27

7.31

7.30

7.27

7.22

7.06

7.10

7.11

7.06

7.07

7.04

7.12

7.19

7.09

7.11

7.02

7.03

7.05

7.10

7.10

7.05

7.01

7,03

7.10

7.16

7.05

7.10

7.00

7.02

7.59

7.63

7.57

7.54

7.49

7.58

7.52

7.57

7.51

7.69

7.61

7.58

7.50

7.46

7.52

7.47

7.49

7.35

7.53

7.60

7.55

7.70

7.58

7.61

7.44

7.41

7.43

7.40

7.39

7.40

7.43

7.40

7.39

7.52

7.45

7.42

AP

PE

ND

IX P

AG

E A

-51

Ju

ly'9

7 p

H D

ata

•••••••*••«

••••«

<

Dat

eB

ioT

ow

er #

1 B

ioT

ow

er #

2 R

ou

gh

ing

Filt

er

Slo

w S

and

Filt

er

Slo

w S

and

Fi

lter

Raw

R

aw +

MFC

S

Eff

luen

t E

fflu

ent

Eff

luen

t In

flu

ent

Eff

luen

t

7/9

7/10

7/11

7/14

7/15

7/16

7/18

7/21

7/23

7/25

7/29

7/30

7/31

7.22

7.26

7.22

7.23

7.25

7.24

7.23

7.23

7.20

7.21

7.22

7.19

7.24

7.24

7.23

7.20

7.20

7.22

7.21

7.26

7.27

7.20

7.23

7.25

7.18

7.25

7.05

7.03

7.02

7.09

7.06

7.03

7.12

7.05

7.04

7.11

7.05

7.05

7.10

7.03

7 7

.61

7.01

7.04

7.03

7.00

7.11

6.98

6.97

7.04

6.98

6.97

6.99

7.68

7.60

7.63

7.62

7.61

7.58

7.64

7.55

7.53

7.56

7.42

7.30

7.28

7.62

7.45

7.64

7.56

7.60

7.58

7.63

7.46

7.52

7.56

7.43

7.35

7.48

7.44

7.33

7.41

7.44

7.45

7.40

7.45

7.35

7.24

7.24

AP

PE

ND

IX P

AG

E A

-52

Au

gu

st 9

97 p

H D

ata

Dat

eB

ioT

ow

er#1

B

ioT

ow

er #

2 R

ou

gh

ing

Filt

er

Slo

w S

and

Filt

er

Slo

w S

and

Filte

rR

aw

Raw

+ M

FCS

E

fflu

ent

Eff

luen

t E

fflu

ent

Infl

uen

t E

fflu

ent

8/4

8/7

8/11

8/13

8/14

8/15

8/18

8/20

8/22

8/27

8/29

7.22

7.24

7.28

7.24

7.26

7.22

7.28

7.26

7.27

7.34

7.32

7.27

7.26

7.27

7.32

7.09

7.06

7.17

7.16

7.17

7.2

7.23

7.18

7.15

7.21

7.22

7.00

6.93

7.10

7.09

7.10

7.11

7.16

7.11

7.10

7.12

7.14

7.42

7.10

7.25

7.31

7.29

7.29

7.38

7.31

7.27

7.21

7.47

7.33

7.31

7.39

7.35

7.29

7.39

7.37

7.31

7.29

7.32

7.22

7.25

7.33

7.31

7.36

7.35

7.32

7.30

7.30

AP

PE

ND

IX P

AG

E A

-53

Se

pte

mb

er

'97 p

H D

ata

Dat

eB

ioTo

wer

#1

Bio

To

wer

#2

Ro

ug

hin

g F

ilter

S

low

San

d F

ilter

S

low

San

d

Filt

erR

aw

Raw

+ H

FCS

E

fflu

ent

Eff

luen

t E

fflu

ent

Infl

uen

t E

fflu

ent

9/2

9/3

9/4

9/5

9/8

9/10

9/15

9/16

9/18

9/22

9/24

9/26

9/29

7.24

7.31

7.26

7.2

7.27

7.19

7.2

7.22

7.21

7.24

7.25

7.18

7.26

7.22

7.23

7.16

7.11

7.21

7.12

7.01

7.16

7.16

7.11

7.14

7.07

7.09

7.22

7.20

7.14

7.04

7.10

7.01

7.00

7.07

7.10

7.03

7.06

6.98

6.99

7.62

7.69

7.53

7.37

7.32

7.15

7.21

7.25

7.40

7.15

7.17

7.12

7.70

7.71

7.75

7.64

7.47

7.53

7.36

7.40

7.44

7.61

7.35

7.38

7.31

7.63

7.50

7.66

7.53

7.37

7.45

7.30

7.29

7.36

7.57

7.24

7.32

7.25

7.44

AP

PE

ND

IX P

AG

E A

-54

Octo

ber

'97 p

H D

ata

Dat

eB

ioTo

wer

#1

Bio

To

wer

#2

Ro

ug

hin

g F

ilter

S

low

San

d F

ilter

S

low

San

d

Filte

rR

aw

Raw

+ H

FCS

E

fflu

ent

Eff

luen

t E

fflu

ent

Infl

uen

t E

fflu

ent

10/1

10/6

10/8

10/1

0

10/1

4

10/1

7

10/2

2

10/2

8

10/3

0

10/3

1

7.24

7.25

7.30

7.14

7.22

7.20

7.19

7.18

7.21

7.19

7.12

7.10

7.19

7.03

7.07

7.14

7.08

7.07

7.14

7.10

6.99

6.98

7.06

6.93

6.99

7.06

6.97

6.99

7.07

7.02

7.69

7.56

7.63

7.36

7.28

7.26

7.17

7.05

7.81

7.79

7.66

7.55

7.57

7.42

7.36

7.39

7.21

7.14

7.93

7.91

7.47

7.38

7.41

7.28

7.31

7.32

7.27

7.39

7.54

7.54

AP

PE

ND

IX P

AG

E A

-55

Ma

rch

'97

Tu

rbid

ity D

ata

Bio

To

wer

#1

Bio

To

wer

#2

Ro

ug

hin

g F

ilter

S

low

San

d F

ilter

S

low

San

d

Filt

erD

ate

Raw

E

fflu

ent

Eff

luen

t E

fflu

ent

Infl

uen

t E

fflu

ent

3/10

3/11

3/17

3/19

3/21

3/24

3/25

3/28

3/31

0.05

0.04

0.09

0.14

0.04

0.06

0.12

0.09

0.10

1 "

~"

0.22

0.22

0.13

0.21

0.29

2.00

2.00

1.20

0.76

• —

—0.

24

0.22

0.18

0.32

0.47

4.3

4.45

1.2

0.96

. -1r

. "

0.24

0.25

0.21

0.55

0.62

4.50

0.20

0.80

0.85

I "

'

I

I "

AP

PE

ND

IX P

AG

E A

-56

Ap

ril

'97

Tu

rbid

ity

Da

ta

Dat

eB

ioT

ow

er #

1 B

ioT

ow

er #

2 R

ou

gh

ing

Filt

er

Slo

w S

and

Filt

erR

aw

Eff

luen

t E

fflu

ent

Eff

luen

t In

flu

ent

Slo

w S

and

Filt

erE

fflu

ent

4/2

4/4

4/7

4/9

4/12

4/15

4/17

4/21

4/22

4/23

4/25

4/28

4/29

4/30

0.12

0.08

0.05

0.36

0.10

0.11

0.18

0.14

0.07

0.18

0.09

0.12

0.10

0.14

0.52

1.45

0.89

2.35

6.30

1.50

2.70

1.10

2.40

2.20

1.80

2.15

1.85

2.00

0.89

1.85

1.20

5.50

6.65

3.30

4.05

1.50

3.00

2.40

2.25

2.05

2.10

3.60

1.50

1.50

2.90

5.90

3.45

3.50

1.00

1.60

1.40

1.45

1.55

1.90

1.70

1.90

1.80

0.85

0.62 A

PP

EN

DIX

PA

GE

A-5

7

Ma

y '

97

Tu

rbid

ity D

ata

Dat

eB

ioTo

wer

#1

Bio

To

wer

#2

Ro

ug

hin

g F

ilter

S

low

San

d F

ilter

Raw

E

fflu

ent

Eff

luen

t E

fflu

ent

Infl

uen

tS

low

San

d

Filt

erE

fflu

ent

5/1

5/2

5/5

5/6

5/7

5/12

5/14

5/16

5/19

5/21

5/23

5/28

5/30

0.14

0.16

0.10

0.08

0.13

0.10

0.10

0.08

0.10

0.08

0.20

0.12

0.24

2.50

2.80

0.79

1.40

1.25

1.60

1.50

1.45

1.20

1.10

0.88

1.45

2.20

2.90

3.50

0.96

1.45

1.55

1.50

1.50

1.30

1.10

1.60

1.10

1.50

1.80

2.30

2.40

0.66

0.92

1.20

1.10

1.10

1.00

0.90

1.25

1.20

1.20

1.45

2.20

2.00

0.77

0.77

1.20

0.90

1.10

0.95

0.83

1.30

1.10

1.05

1.05

0.80

0.46

0.31

0.24

0.35

0.17

0.18

0.28

0.24

0.20

0.21

0.19

0.19 A

PP

EN

DIX

PA

GE

A-5

8

Ju

ne

'9

7 T

urb

idit

y D

ata

Bio

Tow

er #

1 B

ioT

ow

er #

2 R

ough

ing

Filt

er

Slo

w S

and

Filt

erD

ate

Raw

E

fflu

ent

Eff

luen

t E

fflu

ent

Infl

uen

tS

low

San

d

Filte

rE

fflu

ent

6/2

6/4

6/6

6/9

6/11

6/13

6/18

6/20

6/25

6/26

6/29

0.16

0.12

0.17

0.12

0.20

0.24

0.23

0.12

0.20

0.12

0.25

1.80

1.80

1.95

1.80

2.90

5.40

3.50

4.00

1.70

3.10

5.30

2.10

1.60

1.50

2.60

3.45

5.60

5.30

5.20

1.40

3.00

3.45

1.75

1.20

1.20

2.20

2.05

2.10

2.30

1.70

0.80

1.00

1.65

1.60

1.10

1.05

1.90

1.60

2.30

1.80

1.10

0.50

0.85

1.35

0.37

0.31

0.40

0.67

0.44

0.44

0.48

0.42

0.38

0.45

0.35 A

PP

EN

DIX

PA

GE

A-5

9

Ju

ly '

97

Tu

rbid

ity

Da

ta

Dat

eB

ioT

ow

er #

1 B

ioT

ow

er #

2 R

ou

gh

ing

Filt

er

Slo

w S

and

Filt

erR

aw

Eff

luen

t E

fflu

ent

Eff

luen

t In

flu

ent

Slo

w S

and

F

ilter

Eff

luen

t

7/9

7/10

7/11

7/14

7/15

7/16

7/18

7/21

7/23

7/25

7/29

7/30

7/31

0.20

0.18

0.13

0.15

0.15

0.16

0.15

0.26

0.29

0.16

0.30

0.17

0.27

3.60

2.20

2.20

1.80

1.45

1.80

1.45

2.80

4.00

2.50

4.20

2.00

2.60

2,35

2.60

1.95

2.65

1.90

2.45

1.80

3.35

3.05

2.00

3.50

2.25

3.05

0.95

0.90

0.67

1.00

1.20

1.05

1.05

1.50

1.80

0.93

2.30

1.55

2.10

1.10

0.97

0.75

1.00

0.95

1.05

0.92

1.80

1.70

2.05

1.50

2.05

0.25

0.20

0.25

0.32

0.31

0.31

0.23

0.25

0.25

0.40

0.36

0.42

AP

PE

ND

IX P

AG

E A

-60

•«•••*••••••••••••••••••

Au

gu

st

'97

Tu

rbid

ity D

ata

Bio

To

wer

#1

Bio

To

wer

#2

Rou

ghin

g Fi

lter

Slo

w S

and

Filt

erD

ate

Raw

E

fflu

ent

Eff

luen

t E

fflu

ent

Influ

ent

Slo

w S

and

Filte

rE

fflu

ent

8/4

8/7

8/11

8/13

8/14

8/15

8/18

8/20

8/22

8/27

8/29

0.25

0.23

0.4

0.16

0.2

0.2

0,17

0.16

0,14

0.15

0.24

2.55

3.60

2.90

1.55

2.80

2.10

2.50

1.60

2.45

1.80

3.45

3.50

4.70

4.20

3.20

3.40

3.45

3.45

3.00

3.55

4.45

5.05

2.45

2.05

2.75

3.45

2.90

2.45

2.55

2.40

2.50

3.80

2.55

2.00

2.40

3.25

2.05

3.30

2.65

2.40

2.50

3.45

0.46

0.36

0.54

0.56

0.54

0.45

0.75

0.46

0.52

0.47 A

PP

EN

DIX

PA

GE

A-6

1

••••••f

Se

pte

mb

er

'97

Tu

rbid

ity

Da

ta

Bio

To

wer

#1

Bio

To

wer

#2

Ro

ug

hin

g F

ilter

S

low

San

d F

ilter

S

low

San

d

Filt

erD

ate

Raw

E

fflu

ent

Eff

luen

t E

fflu

ent

Influ

ent

Eff

luen

t

9/3

9/4

9/5

9/8

9/10

9/15

9/16

9/18

9/22

9/24

9/26

9/29

0.31

0.34

0.19

0.30

0.32

0.10

0.14

0.18

0.22

0.25

0.22

0.25

0.95

1.60

1.30

0.75

0.70

0.58

0.65

0.86

0.81

0.92

1,05

1,10

1.50

1.20

1.80

1.40

1.25

0.98

1.15

1.50

1.70

1.80

2.15

2.80

1.30

1.45

1.05

0.85

0.66

0.70

0.82

0.91

1.10

1.60

1.65

2.80

1.20

0.80

1.00

0.75

0.65

0.73

0.79

0.09

1.00

1.30

1.30

2.60

0.31

0.27

0.35

0.38

0.36

0.31

0.28

0.28

0.38

0.39

0.44

0.70 A

PP

EN

DIX

PA

GE

A-6

2

Oc

tob

er

'97

Tu

rbid

ity D

ata

Bio

To

wer

#1

Bio

To

wer

#2

Ro

ug

hin

g F

ilter

S

low

San

d F

ilter

S

low

San

d

Filt

erD

ate

Raw

E

fflu

ent

Eff

luen

t E

fflu

ent

Infl

uen

t E

fflu

ent

10/1

10/6

10/8

10/1

4

10/1

7

10/2

2

0.35

0.36

0.34

0.34

0.17

0.23

1.80

1.50

1.20

1.20

0.50

0.68

3.05

1.70

2.20

3.50

1.80

1.80

2.05

1.10

1.10

2.50

1.30

1.90

1.50

1.10

1.05

2.00

1.50

1.30

0.63

0.35

0.28

0.52

0.44

0.82 A

PP

EN

DIX

PA

GE

A-6

3

•«•«

••«

To

tal

Co

lifo

rm M

PN

Da

ta

Sam

ple

Dat

e(#

co

un

ts/1

00 m

l)W

ell W

ater

B

ioT

ow

er #

2 E

fflu

ent

Ro

ug

hin

g F

ilter

Eff

luen

tS

low

san

d F

ilter

Eff

luen

t

6/4 6/25

7/23

7/31

8/14

9/16

10/1

5

7.0

x1

01

<2

.0x1

0°

7.0

x1

01

<2

.0x1

0°

<2

.0x

10°

<2

,0x

10°

<2,0

x 1

0°

>1

.6x1

07

17

x1

06

1.6

x1

07

1.1

x1

06

1.6

x1

06

3.0

x1

07

1.1

x1

07

>1

.6x

10

7

8.0

x1

03

5.0

x1

05

1.6

x1

06

5.0

X1

05

1.6

x1

06

1.6

x1

06

>1

.6x

10

7

1.4

X1

05

5.0

x1

05

1,6

x1

05

1.6

x1

05

3.0

x1

03

9.0

x1

04

Sam

ple

Ave

rag

e V

alu

es (

#/10

0 m

l)

Sta

nd

ard

Dev

iati

on

Wel

l Wat

er

Bio

Tow

er #

2 E

fflue

nt

Rou

ghin

g F

ilter

Effl

uent

Slo

w s

and

Filt

er E

fflue

nt

2.0

x1

01

1.0

x1

07

9.7

x1

05

1.8

x1

05

3.4

x1

01

1.1

5x1

07

7.2

x1

0s

1.7

X1

05

Fec

al c

olif

orm

bac

teri

a w

ere

nev

er d

etec

ted

in

an

y sa

mp

le!

AP

PE

ND

IX P

AG

E A

-64

He

tero

tro

ph

ic P

late

Co

un

t (H

PC

) D

ata (#

cou

nts

/100

ml)

Sam

ple

Dat

e W

ell W

ater

B

ioT

ow

er #

2 E

fflu

ent

Rou

ghin

g Fi

lter

Eff

luen

tS

low

san

d Fi

lter

Eff

luen

t

6/4 7/23

8/14

9/16

10/1

5

1.9

x1

04

1.0

X1

03

1 .2

X 1

03

1.8

x 10

4

<1

.0x1

0°

>8

.0x

104

1.8

x1

08

2.5

x1

07

2.2

x1

07

3.5

x1

07

>8

.0x

104

3.8

x10

7

2.2

x1

07

1.4

x1

07

4.3

x1

07

1.3

x1

05

1.2

X1

06

3.0

x1

03

6.6

X1

05

6.4

x1

06

Sam

ple

Ave

rage V

alu

es

(#/1

00 m

l)

Sta

ndard

Devi

atio

n

Wel

l Wat

er

Bio

Tow

er #

2 E

fflue

nt

Rou

ghin

g F

ilter

Effl

uent

Slo

w s

and F

ilter

Effl

uent

7.5

x10

3

4.6

x10

7

2.9

x10

7

1.7

x1

06

9,8

x10

3

3.7

x10

7

1.4

x10

7

2.7

x1

06

AP

PE

ND

IX P

AG

E A

-65

Ch

lori

ne D

em

an

d #

1

(7-9

-97

)

Tar

get

Do

se

Mea

sure

d D

ose

@

24

HO

UR

S C

hlo

rin

e R

esid

ual

at

Giv

en D

ose

(m

g-C

I2/L

)(m

g-C

I2/L

) (m

g-C

I2/L

) (m

g-C

I2/L

) 1

23

4

Sys

tem

Infl

uen

t (m

g-C

I2/L

)

1 2 3 4

1.1

1.8

2.6

3.6

0.9 1.9

2.6

3.5

0.0

0.0

0.1

0.3

0.3

0.6

0.7

1.6

1.4

^^^^^^^^^^

0.05

(±

0.0

14

)

0.30

(±

0.0

14

)

0.65

(±

0.0

57

)

1.50

(±

0.1

70)

12

34

S

yste

m E

fflu

ent

(mg-C

I2/L

)

0,1 0.1

0.15

0.7

1.1

1.1

^^^^^^^^^^

0.08

(±

0.05

7

0.15

0.67

1.07

(±

0.02

8

AP

PE

ND

IX P

AG

E A

-66

•••«

•••«

•*•*•••••••••••••••••••••••••••••*«

<

Ch

lori

ne

De

ma

nd

#2 (7

-23

-97

)

Targ

et D

ose

Mea

sure

d D

ose

(mg-

CI2

/L)

(mg-

CI2

/L)

24 H

OU

RS

C

hlor

ine

Res

idua

l at

Giv

en D

ose

(mg

-CI2

/L)

(mg

-CI2

/L)

12

3

45

S

yste

m I

nf.

{mg-

CI2

/L)

1 2 3 4 5

1.0

1.6

2.7

3.6

4.4

0.9 1.8

2.6 3.7

4.7

0.5

3

0.6

6

0.79

1.51

1.80

1.84

2.34

2.32

2.38

3.30

3.12

4.25

4.1

^^^^^^^^^^^^^^

/'^

^^^^^^^^^^m

^^M

0.66

(±

0.26

)

1.72

(±

0.3

6)

2.35

(±

0.0

6)

3.21

(±

0.25

)

4.18

(±

0.21

)

12

3

4

5

Sys

tem

Eff.

(m

g-C

I2/L

)

0 0 0

0 0 0

0 0 0

0 0 0

0 0 0

^^^^^^^^^^^

Thi

osul

fate

Res

idua

l in

SS

FE

fflue

nt

AP

PE

ND

IX P

AG

E A

-67

••«

*•••••••••••••••••*••••••••••«

•••••

Ch

lori

ne D

em

an

d #

3 (

7-2

9-9

7)

Tar

get

Dos

e M

easu

red

Do

se

@ 2

4 H

OU

RS

C

hlo

rin

e R

esid

ual

at

Giv

en D

ose

(mg

-CI2

/L)

(mg

-CI2

/L)

(mg

-CI2

/L)

(mg

-CI2

/L)

12

3

45

S

yste

m In

f. (

mg

-CI2

/L)

1 2 3 4 5

1.2

1.9

2.8

3.3

4.2

0.8 1.6

2.4

3.0

3.8

1.15

1.22

1.12

1.30

2.15

1.91

1.90

1.96

2.70

2.82

2.76

2.68

3.4 3.52

3.6

3.4

4.36

4.16

4.38

3.78

^^^^^^^^^

1.12

(±

0.1

6)

2.00

(±

0.23

)

2.75

(±

0.13

)

3.50

(±

0.2

0)

4.20

(±

0.5

6)

Sys

tem

Eff

. (m

g-C

l2/L

)

0.01

0.03

0.03

0.01

0.06

0.08

0.08

0.07

0 0 0

0.02

(±

0.0

2)

0.07

(±

0.0

2)

AP

PE

ND

IX P

AG

E A

-68

Ch

lori

ne D

em

an

d #

4

(8-1

1-9

7)

Tar

get

Do

se

Mea

sure

d D

ose

(mg-

Cla

/L)

(mg

-CI2

/L)

24 H

OU

RS

C

hlo

rin

e R

esid

ual

at

Giv

en D

ose

(m

g-C

I2/L

)(m

g-C

I2/L

) 2

46

8

10

Sys

tem

In

f. (m

g-C

I2/L

)

2 4 6 8 10

2.0

3.0

4.8

7.0

9.3

1.9

3.7

6.1

7.9

9.2

1.44

1.38

1.65

1.47

3.54

3.36

3.36

3.22

5.50

5,40

5.50

5.35

7.25 6.80

7.65

6.65

9.05

9.15

8.75

9.25

mm

mm

mm

m.

1.49

(±

0.23

)

3.37

(±

0.26

)

5.44

(±

0.15

)

7.09

(±

0.91

)

9.05

(±

0.43

)

810

S

yste

m E

ff.

(mg

-CI2

/L)

0.24

0.30

0.22

0.26

0.40

0.27

0.33

0.29

0 0 0

0.26

(±

0.07

)

0.32

(±

0.12

)

AP

PE

ND

IX P

AG

E A

-69

Ch

lori

ne D

em

an

d #

5 (

9-4

-97

)

Tar

get

Do

se

Mea

sure

d D

ose

(mg

-CI2

/L)

(mg

-Cb

/L)

24 H

OU

RS

C

hlo

rin

e R

esid

ual

at

Giv

en D

ose

(m

g-C

I2/L

)(m

g-C

I2/L

) 2

4 6

81

0

Sys

tem

In

f. (m

g-C

I2/L

)

2 4 6 8 10

1.90

3.80

5.80

7.56

9.10

1.15

0.92

1.02

3.04

2.62

3.50

5.15

5.05

4.75

7.30

7.20

7.15

8.45

8.30

8.25

WM

^MM

^MM

$>

1.03

(±

0.23

)

3.05

(±

0.88

)

4.98

(±

0.42

)

.21

(±0.

15)

8.33

(±

0.21

)

24

6

8 1

0 S

yste

m E

ff.

(mg-

CI2

/L)

0.78

0.32

0.79

2.15

2.40

2.62

4.35

4.05

3.85

6.20

4.50

6.20

7.90

8.05

7.35

Wii

M^M

MM

K.

0.63

(±

0.57

)

2.39

(±

0.47

)

4.08

(±

0.50

)

5.63

(±

1.9

6)

7.77

(±

0.74

)

AP

PE

ND

IX P

AG

E A

-70

**«

Ch

lori

ne D

em

an

d #

6

(9-2

2-9

7)

Tar

get

Do

se

Mea

sure

d D

ose

(mg

-CI2

/L)

(mg

-CI2

/L)

24 H

OU

RS

C

hlo

rin

e R

esid

ual

at

Giv

en D

ose

(m

g-C

I2/L

)(m

g-C

I2/L

) 2

4 6

8 10

S

yste

m In

f. (

mg

-CI2

/L)

2 4 6 8 10

2.0

3.8

5.9

7.5

9.4

1.49

1.49

1.78

3.42

3.28

3.52

5.50

5.50

5.25

6.8

7.15

7.00

8.40

8.30

8.55

1.58

(±

0.43

)

3.41

(±

0.24

)

5.42

(±

0.28

)

6.98

(±

0.35

)

8.41

(±

0.25

)

810

S

yste

m E

ff.

(mg

-CI2

/L)

0 0 0

0 0 0

0

Add

ition

al 1

.4 m

g-C

I2/L

add

ed a

t su

rge

tank

.

AP

PE

ND

IX P

AG

E A

-71

••••••••*•••••

Ch

lori

ne D

em

an

d #

7 (

10-8

-97)

Tar

get

Dos

e M

easu

red

Dos

e @

24

HO

UR

S C

hlor

ine

Res

idua

l at

Giv

en D

ose

(mg-

CI2

/L)

(mg-

CI2/L

) (m

g-C

I2/L

) (m

g-C

I2/L

) 2

4

6

8

16

Sys

tem

Inf.

(mg-

CI2

/L)

2 4 6 8 16

1.7

3.9

5.6

7.4

15.2

1.58

1.16

2.88

3.14

4.95

4.70

6.50

6.75

13.8

14.7

1.37

(±

0.30

)

3.01

(±

0.30

)

4.83

(±

0.30

)

6.63

(±

0.30

)

14.2

5 (+

0.30

)

816

S

yste

m E

ff.

(mg-

CI2

/L)

3,90

3.50

3.95

AP

PE

ND

IX P

AG

E A

-72

Air

-Sco

ur

#1 (5

-19-9

7)

Tim

e A

fter

Sam

ple

Air

-Sco

ur(

min

.) N

itra

te (

mg

-N/L

) N

itri

te (

mg

-N/L

) D

OC

(mg

/L)

Tu

rbid

ity

(NTU

)pH

D

.O.

(mg

-Oz/

L)

Bio

Tow

er

Effl

uent

Slo

w S

and

Filt

erE

fflue

nt

0 60 120

180

24

0300

360

0 60 120

180

240

300

360

9.3

10.3

11.4

11.4

11.7

1.1

3.5

8.0

9.4

9.8 12.1

0.5 1.2

1.4

2.2 1.9

4,0

2.2 1.8

1.5

1.6

1.9

12.7

13.6

13.4

14.3

14.5

14.0

4.0 3.6

4.0 3.5

3.4

4.0

2.7 1.6

1.3

1.0

0.9

0.9

0.2 0.7

0.5

0.4

0.3

0.3

7.2

7.2

7.2 7.2

7.2

7.2

7.4 7.5

7.5 7.5

7.4

7.5

1.45

1.55

1.15

1.05

1.10

0.95

4.10

3.55

3.60

3.55

3.60

3.55

Bio

Tow

er i

nflu

ent b

efor

e ai

r-sc

our:

Nitr

ate =

15.

3 m

g-N

/LD

OC -

36.

8 m

g-C

/LT

urbi

dity

= 0

.10

NT

UpH

=7.2

5=

1.5

0m

g-O

2/L

Bio

Tow

er e

fflue

nt b

efor

e ai

r-sc

our:

Nitr

ate =

0.8

mg-

N/L

DO

C =

4.6

mg-

C/L

Tur

bidi

ty=

1.

10 N

TU

DO

= 0

.50

mg-

O2/

LN

itrite

= 3

.8 m

g-N

/L

Slo

w s

and

filte

r ef

fluen

t bef

ore

air

-sco

ur:

Nitr

ate =

0.8

mg-

N/L

DO

C =

4. 7

mg-

C/L

Turb

idity

- 0.

2 N

TU

= 4

.15

mg

-O2/L

Nitr

ite =

3.7

mg-

N/L

Air

-sco

ured

bot

h to

wer

s fo

r 10

min

utes

at 2

0 ps

ig.

Air

was

lef

t on

for

1 m

inut

e af

ter

drai

ning

beg

an.

Bio

mas

s fr

om t

ow

er #

1co

nsis

ted

of b

lack

bio

mas

s an

d cr

eam

col

ored

bio

mas

s. H

owev

er,

tow

er #

2 co

ntai

ned

only

cre

am c

olor

ed b

iom

ass.

Pre

ssur

eaf

ter

air-

scou

r at

a fl

ow r

ate

of 1

0 gp

m w

as 1

0,0

psig

.

AP

PE

ND

IX P

AG

E A

-73

Air

-Sc

ou

r #2

(7-1

1-9

7)

Tim

e A

fter

Sam

ple

A

ir-S

cou

r(m

in.)

Nit

rate

(m

g-N

/L)

Nit

rite

(m

g-N

/L)

DO

C (

mg

/L)

Tu

rbid

ity

(NT

U)

pH

D.O

. (m

g-Q

z/L)

Bio

Tow

erE

fflue

nt

Slo

w S

and

Filt

erE

fflue

nt

0 42 84 126

168

210

0 42 84 12

616

8210

9.5 10.9

10.5

10.6

10.4

4.6

4.1

4.7 6.9

3.6

3.5

4.8

5.1 5.0

4.3

4.7

5.3

4.8

13.4

8.3

8.2

8.8

9.0

2.3

2.4

2.4

2.3

8.3

4.3

3.6

3.5

2.8

0.2

0.5 0.4

0.4

7.3

7.2

7.2

7.2 7.1

7.5

7.7

7.5

7.5

1.00

0.70

0.65

0.60

0.55

3.45

3.35

3.45

3.50

Bio

Tow

er I

nflu

ent

befo

re a

ir-sc

our:

Nitr

ate

= 2

0.4

mg-

N/L

DO

C =

16.

4 m

g-C

/LT

urbi

dity

= 0

,15

NT

UP

H-7

.20

DO

= 1

.65

mg-

O2/

L

Bio

Tow

er e

fflue

nt b

efor

e ai

r-sc

our:

Nitr

ate

= 4

.0 m

g-N

/LD

OC

= 2

.9 m

g-C

/LT

urbi

dity

= 2

.0 N

TU

pH =

7.0

0D

O =

0.6

5 m

g-O

2/L

Nitr

ite =

2.1

mg-

N/L

Slo

w s

and

filte

r ef

fluen

t be

fore

air-

scou

r:N

itrat

e =

5.7

mg-

N/L

DO

C =

2.6

mg-

C/L

Tur

bidi

ty =

0.3

0 N

TU

pH =

7.4

0D

O =

3.7

0 m

g-O

2/L

Nitr

ite =

0.9

mg-

N/L

Air-

scou

red

tow

ers

for

5 m

inut

es a

t 20

psig

(3

scfm

) an

d fo

r 1

min

ute

afte

r dra

inin

g be

gan.

Rin

sed

tank

s w

ith 2

0 ga

llons

of w

ater

.B

iom

ass

rem

oved

fro

m B

ioT

ower

#1

was

bla

ck/c

ream

col

ored

and

sm

elle

d o

f sul

fides

. B

iom

ass

rem

oved

fro

m B

ioTo

wer

#2

was

crea

m c

olor

ed w

ith w

hite

fle

cks

and

did

not

smel

l of s

ulfid

es. P

ress

ure

afte

r ai

r-sc

our

at 1

0 gp

m w

as 8

.10

psi

g.

At

a flo

w r

ate

of 1

0 gp

m,B

ioT

ower

#1

requ

ired

12

min

utes

to

fill!

Thi

s w

as m

uch

low

er t

han

the

empt

y be

d de

tent

ion

tim

e of

42

min

utes

. B

ioT

ower

#2

requ

ired

30 m

inut

es t

o fil

l. T

here

fore

, the

tot

al d

eten

tion

time

of b

oth

tow

ers

was

42

min

utes

, ha

lf th

eem

pty

bed

dete

ntio

n tim

e of

84

min

utes

!

AP

PE

ND

IX P

AG

E A

-74

••»»•«•••••••••••»•••••••••••*•••••»••»••

Air

-Sco

ur

#3

(8

-7-9

7)

Tim

e A

fter

Sam

ple

A

ir-S

cou

r(m

in.)

Nit

rate

(m

g-N

/L)

Nit

rite

(m

g-N

/L)

DO

C (

mg

/L)

Tu

rbid

ity

(NT

U)

pH

D

.O.

(mg

-O2/

L)

Bio

Tow

erE

fflue

nt

Slo

w S

and

Filte

rE

fflue

nt

0 60 12

018

0240

30

0360

0 60 120

180

240

300

360

9.2 12.1

11.7

12.3

9.6

2.9 3.7

9.1

8.0

7.9

0.4

0.8 1,0

1.2

1.3

1.2

1.0

0.3

0.5

0.7 0.8 1.1

11.0

15.3

15.7

15.2

15.9

15.3

16.0

2.6

3.3

3.5 3.4

3.4

3.5

3.7

13.0

10.0

8.0

6.5

4.6

4.2

3.6 0.4

0.5 0.5

0.4

0.5

0.5

7.1 7.1 7.1

7.1 7.1

7.1

7.0

7.4

7.4

7.3

7.3

7.3

7.3

1.05

1.00

0.75

0.40

0.45

0.40

0.55

4.05

4.20

3.65

3.25

3.25

3.25

Bio

Tow

er i

nflu

ent

befo

re

air-

scou

r:N

itrat

e =

22.

3 m

g-N

/LD

OC

= 2

9.3

mg-

C/L

Tur

bidi

ty =

0.2

NT

UpH

= 7

.20

DO

= 5

.05

mg-

O2/

L

Bio

Tow

er e

fflue

nt b

efor

e ai

r-sc

our:

Nitr

ate

= 6

.8 m

g-N

/LD

OC

= 5

.5 m

g-C

/LT

urbi

dity

= 4

.7 N

TU

pH

= 7

.10

DO

= 0

.70

mg

-O2/L

Nitr

ite =

1.2

mg-

N/L

Slo

w s

and

filte

r ef

fluen

t be

fore

air-

scou

r:N

itrat

e =

3.6

mg-

N/L

DO

C =

3.1

mg-

C/L

Tur

bidi

ty =

0.4

NT

UpH

= 7

.20

DO

= 3

.00

mg

-O2/L

Nitr

ite =

1.0

mg-

N/L

Dra

ined

50

gallo

ns fr

om e

ach

reac

tor.

Air

-sco

ure

d to

we

rs fo

r 4

min

utes

at

20 p

sig

(3 s

cfm

) an

d fo

r 1

min

ute

durin

gdr

aini

ng. W

ashe

d bo

th to

wer

s w

ith 5

0 g

allo

ns o

f w

ater

. P

ress

ure

at 1

0 gp

m w

as 6

.90

psig

.A

t a

flow

rat

e of

10

gpm

, B

ioT

ower

#1

requ

ired

12 m

inut

es t

o fil

l. T

his

was

muc

h lo

wer

tha

n th

e em

pty

bed

dete

ntio

n tim

eof

42

min

utes

. Bio

Tow

er #

2 re

quire

d 22

min

utes

to

fill.

Tot

al d

eten

tion

time

for

both

to

we

rs w

as 3

4 m

inut

es,

less

than

hal

fof

the

em

pty

bed

dete

ntio

n tim

e of

84

min

utes

.

AP

PE

ND

IX P

AG

E A

-75

•«

••••••••••••••••••••••••••••••••*•••*«

«<

Air

-Sco

ur #

4 (9

-4-9

7)

Tim

e A

fter

Sam

ple

Air

-Sco

ur(

min

.) N

itra

te (

mg

-N/L

) N

itrite

(m

g-N

/L)

DO

C (m

g/L

) T

urb

idit

y (

NTU

)p

H

D.O

. (m

g-O

2/L

)

Bio

To

we

rE

fflu

en

t0 60 12

018

02

40

300

11.3

11.8

12.2

12.5

12.6

13.2

0.3

0.3 0.5

0.5 0.5

0.5

8.1

8.9 9.2

8.0

7,9

8.0

5.0

2.1 1.5

1.2

1.1

1.1

7.2

7.2 7.1

7.1 7.1

7.0

3.30

1.10

0.70

0.55

0.60

0.65

Bio

Tow

er i

nflu

ent

befo

re a

ir-s

cour

:N

itrat

e =

19.

2 m

g-N

/LD

OC

= 3

1.9

mg

-C/L

Tur

bidi

ty =

0.3

5 N

TU

pH =

7,3

0=

4.5

0m

g-O

2/L

Bio

Tow

er e

fflu

en

t be

fore

air

-sco

ur:

Nitr

ate

= 6

.0 m

g-N

/LD

OC

= 4

.4m

g-C

/LT

urbi

dity

=1

.2 N

TU

pH =

7.1

0D

O =

0.8

0 m

g-O

2/L

Nitr

ite =

0.2

0 m

g-N

/L

Dra

ined

30 g

allo

ns fr

om e

ach

rea

ctor

. A

ir-sc

oure

d to

wer

s fo

r 4 m

inut

es a

t 20 p

sig

(3

scf

m)

and fo

r 1 m

inut

e d

urin

gdr

aini

ng.

Was

hed

both

tow

ers

with

50

gallo

ns o

f wat

er.

Pre

ssur

e at

10

gpm

was

8.7

5 ps

ig.

At

10 g

pm,

Bio

Tow

er #

1 re

quire

d 13

min

utes

to

fill.

Thi

s is

muc

h lo

wer

than

the

em

pty

bed

dete

ntio

n tim

e of

42

min

utes

.B

ioT

ower

#2

requ

ired

20 m

inut

es t

o fil

l. T

otal

det

entio

n tim

e fo

r bo

th t

ow

ers

was

33

min

utes

, al

mos

t 1/

3 of

the

empt

y be

dde

tent

ion

time

of 8

4 m

inut

es.

AP

PE

ND

IX P

AG

E A

-76

Air

-Sco

ur

#5

(10-

1-97

)

Tim

e A

fter

Sam

ple

Air-

Sco

ur(

min

.) N

itrat

e (

mg-

N/L

) N

itrite

(m

g-N

/L)

DO

C (m

g/L)

T

urb

idity

(N

TU)

pH

D.O

. (m

g-O

2/L)

Bio

Tow

erE

fflue

nt

Bio

Tow

erIn

fluent

0 60 120

180

240

0 60 120

180

240

10.1

9.1

9.1 10.4

9.9 19.2

21.6

20.0

20.3

19.6

0.4

0.5

0.5

0.4 0.5

14.8

15.6

16.0

17.2

17.5

38.0

38.8

39.6

39.0

39.0

7.6 3.6

3.2

3.1 3.4

7.0 7.0

7.0

7.0

7.1

7.3

7.3

7.2

7.3 7.2

1.65

0.95

0.45

0.45

0.40

5.75

5.30

1.45

1.30

1.25

Bio

Tow

er i

nflu

ent b

efor

e ai

r-sc

our:

Nitr

ate

= 1

8.4

mg-

N/L

DO

C =

35.

2 m

g-C

/LTu

rbid

ity =

0.3

5 N

TU

pH =

7.2

5D

O =

4.6

0 m

g-O

2/L

Bio

Tow

er e

fflue

nt b

efor

e ai

r-sc

our:

Nitr

ate

= 4

.6 m

g-N

/LD

OC

= 1

0.4

mg-

C/L

Tur

bidi

ty =

3.0

5 N

TU

pH =

7.0

0D

O =

0.5

0 m

g-O

2/L

Nitr

ite =

0.5

5 m

g-N

/L

Dra

ined

35

gallo

ns fr

om e

ach

reac

tor.

Air

-sco

ured

tow

ers

for

1.5

min

utes

at 2

0 ps

ig (

3 sc

fm)

and

for

30 s

econ

ds d

urin

gdr

aini

ng.

Was

hed

both

tow

ers

with

30

gallo

ns o

f wat

er.

Pre

ssur

e at

10

gpm

was

7.0

0 ps

ig.

At

10 g

pm,

Bio

Tow

er #1

req

uire

d 13

min

utes

to f

ill.

Bio

Tow

er #

2 re

quire

d 18

min

utes

to

tow

ers

was

31

min

utes

, al

mos

t 1/

3 th

e em

pty

bed

dete

ntio

n tim

e of

84

min

utes

!T

otal

det

entio

n tim

e fo

r bot

h

AP

PE

ND

IX P

AG

E A

-77

Sam

ple

THM

FP #

1 (7

-30-

97)

Chl

orof

orm

(ug

/L)

Dic

hlor

obro

mof

orm

(u

g/L)

C

hlor

odib

rom

ofor

m (

ug/L

) B

rom

ofor

m (

ug/L

)

Sys

tem

Inf

luen

t #1 #2 #3

Ave

rage

->

Sys

tem

Effl

uent

#1 #2 #3

Ave

rage

->

19.5

13.8

22.4

18.6

(±

4.3)

17.9

16.4

16.1

16.8

(±1

.0)

18.7

19.5

23.6

20.6

(±2.

6)

25.7

22.3

22.5

23.3

(±

1.9)

19.2

26.4

25.0

23.5

(±

3.9

)

32.5

25.0

24.9

27.4

(±4.

4)

9.3 15

.6

12.8

12. 6

(±3.

1)

13.4

8.7

9.1

10.4

(±

2.6)

TTH

MFP

Raw

75

.21

(±13

.94)

TTH

MFP

SS

FE

77.9

3 (±

9.87

)

AP

PE

ND

IX P

AG

E A

-78

Sam

ple

THM

FP #

2 (8

-11-

97)

Chl

orof

orm

(ug

/L)

Dic

hlor

obro

mof

orm

(ug

/L)

Chl

orod

ibro

mof

orm

(ug

/L)

Bro

mof

orm

(u

g/L)

Sys

tem

Inf

luen

t #1 #2

#3

Ave

rage

->

Sys

tem

Effl

uent

#1 #

2

#3

Ave

rage

->

13.4

15.1

19.5

16.0

(13.

2)

0 1.8

0.2

0.7

(±1.

0)

13.5

15.5

19.1

16.0

(±2

.8)

0 1.58 0

0.5

(±0.

9)

13.6

15.5

19.2

16.1

(±2

.9)

0 5.49

2.51

2.7

(±2.

8)

2.5

2.9

4.5

3. 3

(±1

.1)

4.25 0 1.56

1.9

(±2.

10)

TT

HM

FP

Raw

51

.4 (

±10.

0)

TT

HM

FP

SS

FE

5.

8 (±

6.8)

Pos

sibl

e ch

lorin

atio

n pr

oble

m.

Chl

orin

ede

man

d w

as p

roba

bly

very

hig

h, r

esul

ting

in v

ery

little

chl

orin

e re

sidu

al to

rea

ct w

ithD

OC

and

fro

m T

HM

s.

AP

PE

ND

IX P

AG

E A

-79

•

Sam

ple

THM

FP #

3 (9

-4-9

7)

Chl

orof

orm

(ug

/L)

Dic

hlor

obro

mof

orm

(ug

/L)

Chl

orod

ibro

mof

orm

(ug

/L)

Bro

mof

orm

(ug

/L)

Sys

tem

Inf

luen

t #1 #2

#3

Ave

rage

->

Sys

tem

Effl

uent

#1 #2 #

3

Ave

rage

->

30.2

33.0

33.4

32.2

(±3.

4)

28.9

30.6

33.1

30.8

(±4.

2)

24.1

28.1

27.8

26.7

(±4.

4)

23.3

26.2

27.3

25.6

(±4.

0)

21.4

27.3

25.9

24.9

(±

6.1)

22.8

25.0

25.0

24.3

(±1.

5)

7.7

9.6

9.6

9.0 (

±1.2

)

8.4 9.7

9.1

9.1

(±1.

3)

TH

MF

P R

aw92

.7 (

±15.

2)

TH

MF

P S

SF

E89

.8 (

±11

.0)

AP

PE

ND

IX P

AG

E A

-80

Sam

ple

THM

FP #

4 (9

-22-

97)

Chl

orof

orm

(ug

/L)

Dic

hlor

obro

mof

orm

(ug

/L)

Chl

orod

ibro

mof

orm

(ug

/L)

Bro

mof

orm

(ug

/L)

Sys

tem

Inf

luen

t #1 #2 #3

Ave

rage

->

Sys

tem

Effl

uent

#1 #

2

#3

Ave

rage

->

25.5

16.9

17.8

20.1

(±4.

7)

18.7

22.9

17.6

19. 8

(±2

.8)

24.4

15.6

19.0

19.6

(±4

.4)

4.9

4.8 4.6"

4.8

(±0.

2)

31.5

21.0

30.5

27.7

(±5

.8)

6.6 6.5

6.5

6.55

(±

0.05

)

16.5

12.7

17.7

15.6

(±2

.6)

6.6

6.6 6.7

6.60

(±

0.05

)

THM

FP R

aw83

.0 (

±17.

6)

THM

FP S

SF

E37

.7 (

±3.

0)

AP

PE

ND

IX P

AG

EA

-81

BIOTOWER PRESSURE DATA- RUN #1

*DateDavs Since Air-Scour

*

ftftftftftftftftftftftftftftftft»ftftftftftftftift

5/195/215/235/275/285/306/26/46/66/96/116/136/166/186/206/256/266/276/297/77/97/107/11

02489111416182123252830323738394149515253

7.07.38.07.88.28.58.29.08.48.89.09.18.88.89.79.810.310.611.311.911.9512.1

APPENDIX PAGE A-82

BIOTOWER PRESSURE DATA- RUN #2

Date Dai7/11

7/14

7/15

7/16

7/18

7/21

7/23

7/25

7/29

7/30

7/31

8/4

8/7

/s Since Air-Scour Pressure (psig)0

3

4

5

7

10

12

14

18

19

20

24

27

8.1

8.5

8.4

8.2

8.4

9.1

9.6

9.9

8.1

8.3

8.4

9.0

9.4

*

i

ftft

APPENDIX PAGE A-83

BIOTOWER PRESSURE DATA- RUN #3

8/7

8/11

8/13

8/14

8/15

8/18

8/20

8/22

8/25

8/27

8/29

9/2

9/3

9/4

0

4

6

7

8

11

13

15

18

20

22

26

27

28

6.9

8.3

9.35

9.4

9.8

10.1

10.2

10.4

11.3

11.45

11.6

11.75

12.15

12.4

APPENDIX PAGE A-84

BIOTOWER PRESSURE DATA- RUN #4

DateDavs Since Air-Scour Pressure (psig)9/4

9/5

9/8

9/10

9/15

9/16

9/18

9/22

9/24

9/26

9/29

10/1

0

1

4

6

11

12

14

18

20

22

25

27

8.75

8.8

8.3

8.8

10.3

10.0

10.6

10.3

10.6

11.6

11.95

12.1

APPENDIX PAGE A-85

BIOTOWER PRESSURE DATA- RUN #5

DateDavs Since Air-Scour Pressure (psig)10/1

10/3

10/6

10/8

10/10

0

2

5

7

9

7.0

8.0

10.0

10.8

11.2

BIOTOWER PRESSURE DATA- RUN #6

Date Days Since Air-Scour Pressure (psig)10/10

10/14

10/15

10/17

10/21

10/22

10/23

10/28

10/30

10/31

0

4

5

7

11

12

13

18

20

21

6.8

7.0

7.3

7.6

8.5

9.4

9.6

10.6

10.8

10.95

APPENDIX PAGE A-86

APPENDIX B: COST AND ENERGY USE SURVEY

•Survey Results: Ion ExchangePlants

UtilitySan Gs&r rel 0 1

€ACapiai

Annuaized Caj iaJ'UnitCa ial

1M0&&3' Unit Total

Unit ElectricityMcFarland, CA

CapitalAnnualized Capital

Unit CapitalUnit O&MUnit Total

Unit ElectricityDes Moines, IA

CapfiAfwtualkecl Capital

Unit C&piialUnftOfcWUnit Total

: Unit StectrtefySeymour, TX

CapitalAnnualized Capital

Unit CapitalUnit O&MUnit Total

Unit ElectricityLucas, KS

CapilalArtm&Szed Capital

IMftCapiaiUnllO&yUnit Total

Unit ElectricityAdrian, MN

CapitalAnnualized Capital

Unit CapitalUnit O&MUnit Total

Unit Electricity

Capacity (MOD)4+30

;

- :

1.00

10,00

;

' %

,'

0.85

0,151--

;

-

0.432

Cost

1,73 900259?245

0.17113t36o>ao

957,652142,690

0.390.350.740.02

3,661,000: 645,489

0,160>250,40

&0Q68

1,300,000193,700

0.620.240.87

na

360,000$3,640

0,97&$21,82O.Q3

724,000107,876

0.680.080.99

0.0021

Units

total $$/year$/1000gai$/10GOg$l$/iooo$9i$/1000gal

total $$/year$/1 000 gal$71000 gal$71 000 gal$71 000 gal

$ total$/year$/1000gatS/1000g^^/lOOO QsiW000gal

$ total$/year$71 000 gal$71 000 gal$71 000 gal

$ totalS/y0arW1000 gal$/1000gai$/1DOD^ai$/1000gal

$ total$7year$71 000 gal$71 000 gal$71 000 gal$71 000 gal

APPENDIX PAGE B-1

•

ftftftft

Survey Results: Reverse OsmosisPlants

i

UtilitySeymour, TX

CspialAnnustoed Capital

4JnJi Capiaiif rsi 0»:W»M Total

Uratil c ldtyLucas, KS

CapitalAnnualized Capital

Unit CapitalUnit O&MUnit Total

Unit Electricity8r Jgfto\O *

CapitalArtnyaizBci Capital; Unit Capi&l: Or ii O&M

UnltToisiINt itoMolty

Tustin, CA (2)Capital

Annualized CapitalUnit Capital

Unit O&MUnit Total

Unit Electricity

Capacity (MGD)&S&

;

0.151

$

0.5

Year

19S4 :

1994 :1994

study

19S4199?

190?1037

19871987

1987

Cost

<$ -arsrvrjfv^

342,7001JO0.64

; 1,74na

465,00069,285

1.260.842.100.25

fi$^,S661T47 fO^

1,35as?2,27W**H'T>*

800,000119,200

0.651.281.93

na

Units

total $ ;

SflOOOgaf$/tcoo $/1000§ai \l i

total $$/year$/1000gal$71000 gal$/1000gal$/1000gal

total $ :$/year :

i/tooo^j$/1000@a] iS/1000^1 1$/10Q0gai :

$ total$/1000gal

$/1000ga!

APPENDIX PAGE B-2

*BBBiIBBBBBBBBBBBftftftftftftftftftftftftft

Survey Results: Biological Processes

Annuitized

Utility7 OK

ToiaUral Efedridty

Capacity (MOD)0.043

Year1S98

Cost

130,000 total17,471

&.06

Units

APPENDIX PAGE B-3

Su

mm

ary

of

surv

ey c

osts

, in

clu

din

g sy

stem

siz

e ef

fect

on

cost

s

IXC

apita

l O

&M

T

otal

($/1

000

($/1

000

($71

000

gat) 1.

36 0.4

0.74

0.87

1.82

0.99

1.03

0.50

aver

age

std

ev

IX (

Eng

lish)

size

, IX

(MG

D)

0.15

10.

432

0.85

14.

3 10

gai) 0.

170.

390.

150.

620.

970.

680.

500.

32

tota

l un

itco

st($

7100

0ga

i) 1.82

0.99

0.87

0.74

1.36 0.

4

gai) 1.

190.

350.

250.

240.

520.

080.

440.

40

IX (

SI)

size

, IX

(m3/d

)

572

1635

3217

3785

1627

637

850

surv

ey

regr

essi

on

tota

l uni

t to

tal u

nit

cost

($/m

3)co

st($

/m3)

0.48

0.26

0.23

0.20

0.36

0.11

0.32

0.31

0.30

0.30

0.24

0.13

RO Cap

ital

($71

000

gal) 1.

101,

261.

350,

65

O&

M($

7100

0ga

i) 0.64

0.84

0.92

1.28

Tot

al

Ele

ctric

ityT

Tot

al($

71 0

00 g

al)

1.74

2,10

2.27

1.93

1.09

0,31

0.92

0.27

2.01

0.23

RO

(E

nglis

h)

size

, R

O

tota

l uni

t co

st

(MG

D)

($71

000

gai)

0.15

1 2.

100.

5 1.

930.

85

1.74

3 2.

27

RO

(SI)

size

,R

O

572

1893

3217

1135

5

surv

ey

regr

essi

on

tota

l un

it to

tal

unit

cost

co

st($

7m3)

($

7m3)

0.55

0.51

0.46

0.60

0.50

0.50

0.50

0.51

AP

PE

ND

IX P

AG

E B

-4