Treatment performance of advanced onsite wastewater

treatment systems in the Otsego Lake w

SUNY Oneonta Biological Field Station

1 Funding provided by NYSDEC grant #49298.

Treatment performance of advanced onsite wastewater

treatment systems in the Otsego Lake watershed

2008-20111

Submitted by:

Holly Waterfield

SUNY Oneonta Biological Field Station

5838 State Highway 80

Cooperstown, NY

13326

Funding provided by NYSDEC grant #49298.

Treatment performance of advanced onsite wastewater

atershed

EXECUTIVE SUMMARY

This report documents the treatment performance of four advanced onsite wastewater

treatment systems based on monitoring during the summers of 2008 through 2011. All four

systems are installed in the Otsego Lake watershed; three were installed as part of a NYS DEC

grant to demonstrate the use of advanced onsite wastewater treatment systems. Three systems

have been monitored since 2008 (Waterfield and Kessler 2009, Waterfield 2010, Waterfield

2011); OWTS 1 and OWTS 2, funded by the grant, and the UIC system (serving BFS Upland

Interpretive Center). Another system, also funded by the grant, was installed in the spring of

2009 at the BFS Thayer Farm; this system serves three buildings; the Hop House, Boat House,

and a rented residence. Many of these enhanced treatment technologies are new the region, and

thus are unfamiliar to industry professionals, regulators, and residents. For this reason, a DEC

grant was sought and obtained to fund a demonstration project to install and monitor the

treatment performance of six shared advanced treatment systems. The scope of the grant has

since been amended, changing the total number of treatment systems to four, with the last

installed in early 2011 to serve SUNY Oneonta’s newly renovated Cooperstown Campus, which

houses the Biological Field Station and the Cooperstown Graduate Program. The grant did not

fund the installation of the system, though the treatment technologies used were chosen by the

demonstration project’s coordinators.

Treatment performance was assessed based on the following analyses: biochemical

oxygen demand (BOD or CBOD), total suspended solids (TSS), nitrate (NO3), ammonium

(NH3), and total phosphorus (TP). Systems were sampled a total of about 31 occasions, though

all four systems weren’t necessarily sampled on each collection date. Detailed analysis of each

system’s performance is provided in the System Performance, Operation, and Maintenance

section of the 2008-2011 report. Overall, treatment systems performed well, but mainly because

they were actively managed and serviced by qualified professionals. The systems incorporating

textile filters received the most consistent use with the incoming effluent being of typical

household strength (higher than the other systems monitored). Outgoing effluent from these units

was of the highest quality, achieved the best nitrogen transformation rates, and was the least

variable of the systems monitored. The aerobic treatment unit (ATU) serving the UIC produced

effluent of consistent quality, though the system saw very low use compared to its designed

capacity. It handled typical UIC functions and events (field trips, workshops, etc.) and long

periods of low use very well without compromising effluent quality. The foam filter’s treatment

was most variable of the four systems and produced effluent of lower quality than the other units.

The configuration and dosing regime of this system may play a role in the variability observed

throughout this monitoring program.

In the end, most treatment performance issues were improved by communicating with the

trained service provider contracted for each system. As the manufacturer’s recommend, regular

maintenance is needed in order for these systems to operate as they are intended and produce

high quality effluent. Homeowners should be encouraged (and potentially regulated) to prioritize

such maintenance as they would for other major investments (heating systems, vehicles, etc.).

Treatment performance of advanced onsite wastewater treatment systems

in the Otsego Lake watershed, 2008-20112

Holly Waterfield3

INTRODUCTION

This report serves to document the treatment performance of four advanced onsite

wastewater treatment systems monitored during the summers of 2008 through 2011. All four

systems are installed in the Otsego Lake watershed; three were installed as part of a NYS DEC

grant to demonstrate the use of advanced onsite wastewater treatment systems. Three systems

have been monitored since 2008 (Waterfield and Kessler 2009, Waterfield 2010, Waterfield

2011); OWTS 1 and OWTS 2, funded by the grant, and the UIC system (serving BFS Upland

Interpretive Center). Another system, also funded by the grant, was installed in the spring of

2009 at the BFS Thayer Farm. This system serves three buildings; the Hop House, Boat House,

and a rented residence. Due to operation and maintenance issues, OWTS 2 was not monitored in

2010 or 2011. Treatment performance was assessed based on the following analyses:

biochemical oxygen demand (BOD or CBOD), total suspended solids (TSS), nitrate (NO3),

ammonium (NH4), and total phosphorus (TP).

Otsego Lake is located in northern Otsego County, New York. According to the

historical overview by Harman, et al. (1997), the monitoring of Otsego Lake’s water quality

dates back to a 1935 NYS Department of Environmental Conservation (DEC) study. Routine

water quality monitoring efforts began subsequent to the establishment of the Biological Field

Station (BFS) in 1968 (Harman, et al. 1997). Comparisons to these and other historical datasets

had shown overall decreasing water quality conditions, noting in particular increased

phosphorous concentrations likely tied to loading from watershed activities (agriculture, road

maintenance, onsite wastewater treatment, etc.). Onsite wastewater treatment (septic) systems

are estimated to contribute only 7% of the total phosphorus load (Albright 1996), though the

combination of the bio-available form and time of greatest loading at the height of the growing

season is likely to lead to stimulation of algal production (Harman, et al. 1997). The cascading

effects of such nutrient loading on the lake’s ecosystem are far-reaching, and began to concern

lake users and the Village of Cooperstown, which uses Otsego Lake as its source of drinking

water. In 1985, the Village implemented public Health Law 1100 in order to give them legal

grounds to protect the lake as their source of drinking water (Harman, et al. 1997). Additional

actions to curb further water quality degradation in the lake culminated in the formation of a

watershed management plan in 1998, which identified nutrient loading as the greatest threat to

the health of Otsego Lake. Wastewater treatment via onsite treatment systems were listed

second on a prioritized list of action areas (Anonymous 1998), and efforts to manage the

effectiveness of these treatment systems began with a 2004 inventory of all systems in the

established Lake Shore Protection District followed by the inception of the inspection program in

2005 (Anonymous 2007). Under the program, any system found to be in failing condition is to

be replaced within one calendar year. Such replacement systems generally make use of

advanced or enhanced treatment technologies due to conditions that constrain the use of

2 Funding provided by NYSDEC grant #49298.

3 Research Support Specialist, SUNY Oneonta Biological Field Station.

- 1 -

conventional designs, such as setback to the lake or a tributary, soil depth to bedrock or

groundwater, percolation rate, etc. Many of these enhanced treatment technologies are new the

region, and thus are unfamiliar to industry professionals, regulators, and residents. For this

reason, a DEC grant was sought and obtained to fund a demonstration project to install and

monitor the treatment performance of six shared advanced treatment systems. The scope of the

grant has since been amended, changing the total number of treatment systems to three, with the

last installed in December of 2008.

Biochemical oxygen demand (BOD or CBOD) and total suspended solids (TSS) are

typical metrics used to characterize the strength of residential wastewater (Crites and

Tchobanoglous 1998). BOD is an analysis used to determine the relative oxygen requirements

of wastewater, effluents, and polluted waters, by measuring the oxygen utilized during a given

incubation period (APHA 1992). It is expected that organic material is broken down as

wastewater progresses through a treatment system, thus decreasing the oxygen requirements of

highly-treated wastewater and in turn resulting in lower BOD concentrations over the course of

the treatment system (APHA 1992). TSS analysis measures the total amount of suspended or

dissolved solids in wastewater. Solids may negatively affect water quality for drinking or bathing

and potentially clog a drain field. As with BOD, the amount of solids in treated effluent should

be lower than that of raw wastewater (APHA 1992).

Nitrate and ammonia concentrations will provide insight into the physio-chemical

conditions along the treatment train, as the transformations between various nitrogen forms are

dependent on oxygen availability, alkalinity, temperature, and the presence of specific bacterial

populations. Nitrogen is a dynamic component of wastewater treatment systems, which are often

designed to facilitate specific transformations of nitrogen species. Advanced treatment systems

most often incorporate a secondary treatment step that involves aerating the wastewater in order

to create favorable conditions for the bacterial transformation of ammonia to nitrate, called

nitrification. Nitrogen can be completely removed from the waste stream through the process of

denitrification, during which nitrate is converted to nitrogen gas (N2), which is released to the

atmosphere. Nitrification is generally considered the most limiting step of this overall nitrogen

removal process, as it supplies the nitrate that is converted to N2 gas.

Phosphorus, as previously mentioned, is the nutrient of greatest concern with regards to

vulnerable freshwater bodies. The removal of phosphorus from the waste stream prior to

subsurface disposal will be of great benefit to lake management efforts should the technologies

installed prove to be successful. The nutrient removal units installed in all four systems are of the

same, or very similar design, sourced from a single manufacturer. Phosphorus removal occurs

via adsorption of P onto active sites of an iron-oxide based reactive media; this design results in

the gradual reduction in performance as active adsorption sites on the media surface become

occupied. Eventually the adsorption capacity of the media is exhausted and the media must be

replaced in order to restore the treatment unit’s ability to effectively reduce the phosphorus

concentration leaving the treatment system.

- 2 -

METHODS AND MATERIALS

Four onsite wastewater treatment systems (OWTS) were monitored in this study and are

illustrated and described in Figure 1; these include the systems serving the SUNY Oneonta BFS

Thayer Farm Upland Interpretive Center (UIC) and Hop House (HH) and two shared homeowner

systems, OWTS 1 and 2. The UIC system has relatively high treatment capacity, as the UIC was

built to accommodate large groups for field trips and meetings. However, typical water usage is

relatively low due to the short duration of most events (<4 hours); actual flow has not been

measured. The system was installed and use commenced in fall of 2005. The system has been in

continuous operation, though initially the main tank was not sealed adequately and as a result

proper function did not begin until fall of 2007. Use of this facility increased during the summers

of 2009 and 2010, when typical BFS operations were moved temporarily to the Thayer Farm. A

period of intensive use occurred in 2011 and is reflected in the performance results. OWTS1 and

OWTS2 are located within 100 feet of the western shore of Otsego Lake off of State Highway

80, and are used mainly on weekends during the summer. Each system is shared by two adjacent

residences and they are designed to receive daily flows of 440 gallons and 550 gallons

respectively. Actual flow for OWTS1 was not measured. Flow through OWTS2 was measured

by the service provider. OWTS1 has been in use since 1 June 2006. OWTS2 has been in use

since 1 June 2007; this system was not monitored in 2010 or 2011 due to operational issues,

which have since been resolved. The HH system was installed at the BFS Thayer Farm to serve

the Hop House (BFS temporary main offices and labs), the Thayer Boat House, and the Thayer

Farm House (a residential rental) and operation began in April 2009 with waste from the Hop

House and Farm House. Flow from the Boat House began in August 2009. The system receives

consistent domestic flow from the Farm House, which is anticipated to be beneficial to the

treatment system especially during the winter months, which is a low-occupancy period at the

BFS.

Preliminary sampling efforts were conducted during the summer of 2007 in order to

assess the concentrations of various chemical and nutrient parameters. Regular grab samples

were collected between May and August 2008, and June through September 2009. Weekly

samples were collected between 9 June and 13 August 2010 and 6 June and 3 August 2011.

During each sampling event, approximately 600 mL of wastewater were collected following

each treatment component of all systems. Each sample site is shown in Figure 1 as “S#”.

Samples were tested for BOD5 using methods summarized by Green (2004). This method

involves determining initial dissolved oxygen (DO) concentration of the sample and nutrient

buffer followed by incubation at 20°C for five days and determination of the final DO

concentration. Samples were diluted to obtain target DO values such that the 5-day DO

concentration would be lower than the initial by at least 2 mg/L but with a final concentration

greater than 1 mg/L. These conditions were not always achieved, thus valid BOD values were

not obtained for every sample collected. Because a nitrification inhibitor is used during

incubation, results are presented as values of CBOD, and are associated with the carbonaceous

oxygen demand rather than the total oxygen demand (APHA 1992). Overall CBOD reduction

rates for each secondary treatment unit (OWTS 1, 2 and HH filters, UIC 1-3) were calculated

based on the average CBOD concentrations observed over the monitoring period, presented in

Table 6.

- 3 -

Figure 1. Onsite wastewater treatment system configurations. “S#” indicates a sampling point.

A) The UIC system is comprised of a 2-compartment tank, a phosphorus removal unit, a pump tank, and gravel bed drainfield.

Wastewater is circulated and aerated in the first chamber (UIC1 and 2), and settles in the clarification chamber for final solids

settling (UIC3). It then flows through the phosphorus removal unit, on to a pump chamber (UIC4), from which it is pumped in to

the drain field.

B) OWTS1 provides primary treatment in a septic tank and processing tank (PTE) which flow into an equalization tank, then to a

pump tank where the wastewater is pumped and sprayed over an open-cell foam media filter (BFE). In this case the foam media

filter aerates the wastewater and provides surface area for beneficial bacteria, increasing organic digestion. 25% of flow is

returned to the headworks of the processing tank to facilitate the removal of nitrogen from the waste stream, and 50% flows to

the P removal unit (PRE) and on to the drainfield via gravity.

C) OWTS2 provides primary treatment in 2 septic tanks which flow to a two-compartment processing tank. Effluent flows from

the processing tank to a pump tank which periodically doses a textile media filter. Filter-effluent (AXE) is split between the

processing tank (PTE) and the P removal unit (PRE). A portion of effluent from the textile media filter is returned to the

processing tank to facilitate the removal of nitrogen from the waste stream.

D) HH provides primary treatment in 2 septic tanks (STE) which flow to a two-compartment processing tank (PTE). Effluent is

pumped from the processing tank to a textile media filter. Filter-effluent (AXE) is split between the processing tank (PTE) and

the P removal unit (PRE). A portion of effluent from the textile media filter is returned to the processing tank to facilitate the

removal of nitrogen from the waste stream.

- 4 -

Total suspended solids (TSS) concentration was determined according to the standard

method (APHA 1992). A recorded volume of wastewater was filtered through a rinsed, dried,

pre-weighed glass fiber filter. Filters were dried for a minimum of 24 hours at 105°C in a

gravimetric oven and then removed to a desiccator to cool before being weighed. The

concentration of solids in each sample was calculated from the weight of the filtered solids and

the volume of sample filtered; concentrations are reported in mg solids/L. Overall TSS reduction

rates for each secondary treatment unit (OWTS 1, 2 and HH filters, UIC 1-3) were calculated

based on the average TSS concentrations observed over the monitoring period, presented in

Table 6.

Total phosphorus concentrations were determined using the ascorbic acid following

persulfate digestion method run on a Lachat QuikChem FIA+ Water Analyzer (Laio and Marten

2001). Nitrate and ammonia concentrations were also determined for most samples, using

Lachat-approved methods (Pritzlaff 2003, Liao 2001). All reduction and transformation rate

estimates are calculated based on average concentrations observed over the duration of the

monitoring period (Table 6). Total nitrogen concentrations were not determined and are not

presented here due to incomplete oxidation of ammonia to nitrate during the digestion process,

which results in underestimation of TN concentration.

SYSTEM PERFORMANCE, OPERATION, AND MAINTENTANCE

Monitoring results for each sampling location in all treatment systems are presented in

tabular and graphical form for all parameters monitored (Tables 1-6, Figures 2-5). The tables

summarize the testing results for each year (2008-2011) and over the entire monitoring period,

including calculated standard error and the sample size. Figures for CBOD, TSS, TP and

NO3/NH4 include standard error bars. The overall performance of the systems can be assessed by

comparing the first stage of treatment with the last. Typical CBOD concentrations associated

with raw wastewater vary greatly (100 – 600 mg/L) depending on per capita water usage and

inputs of solids to the system (i.e. garbage grinder waste) (Crites and Tchobanoglous 1998). The

industry standard for BOD5 and TSS in effluent from secondary treatment units is 30 mg/L (NSF

2007).

Each system will be discussed individually in the following sections; the treatment

performance of each is assessed in addition to a description of operation and maintenance issues

encountered over the course of the monitoring period. At the time of installation and design,

phosphorus removal units were available from single manufacturer, and so the same treatment

unit is used in all four systems; the results obtained for each treatment system expose the same

performance and maintenance issues for this specific treatment unit, which are addressed in the

last section, Phosphorus Removal Components.

- 5 -

average +\- SE n average +\- SE n average +\- SE n average +\- SE n average +\- SE n

UIC1 12 1.62 10 22 7.45 6 15 2.03 9 66 38.05 5 24 6.45 31

UIC2 10 1.06 11 8 2.82 5 12 1.37 9 54 29.07 6 19 5.86 31

UIC3 8 0.93 10 9 2.57 4 11 0.97 9 54 28.11 6 19 6.06 29

UIC4 12 1.54 9 28 - - 1 - - - - - - - - - - 14 2.10 10

OWTS1 PTE 93 16.47 11 110 21.75 5 92 12.94 9 43 8.78 5 86 8.44 30

OWTS1 BFE 62 14.64 8 45 9.53 6 26 2.76 9 37 7.45 5 43 5.31 28

OWTS1 PRE 28 3.53 7 25 10.41 3 - - - - - - - - - - 27 3.65 10

OWTS2 PTE 255 64.90 6 238 19.25 5 - - - - - - - - - - 247 34.98 11

OWTS2 AXE 16 3.99 4 57 20.96 6 - - - - - - - - - - 41 13.91 10

OWTS2 PRE 12 1.78 5 7 5.67 2 - - - - - - - - - - 11 2.02 7

HH STE - - - - - 186 22.55 5 229 12.64 9 126 25.15 7 178 13.84 21

HH PTE - - - - - 22 6.14 5 23 2.58 9 6 1.10 3 18 2.68 17

HH AXE - - - - - 6 2.69 6 2 0.47 8 1 0.00 7 3 0.85 21

HH PRE - - - - - 3 1.85 2 - - - - - - 1 0.00 2 2 0.93 4

Table 1. Average carbonaceous biochemical oxygen demand (CBOD)in mg/L determined for onsite

wastewater treatment systems between 2008 and 2011, with calculated standard error (SE), sample size (n) for

2008 through 2011 and over the entire monitoring period.

Carbonaceous Biochemical Oxygen Demand

Site2008 2009 2010 2011 overall

Figure 2. Average 2008-2011 carbonaceous biochemical oxygen demand (CBOD) in mg/L determined for

onsite wastewater treatments systems. Bars indicate standard error.

0

50

100

150

200

250

300

UIC OWTS1 OWTS2 HH

CB

OD

(m

g/L

)

Site

Carbonaceous Biochemical Oxygen Demand

- 6 -

average +\- SE n average +\- SE n average +\- SE n average +\- SE n average +\- SE n

UIC1 18.7 3.35 4 - - - - - 21.4 4.59 8 28.2 10.15 6 22.8 3.60 18

UIC2 58.3 42.82 4 - - - - - 12.8 2.14 8 33.0 12.15 6 31.1 10.38 18

UIC3 39.2 29.28 4 - - - - - 11.2 1.67 8 21.8 4.57 6 21.9 6.67 18

UIC4 5.3 2.15 4 - - - - - - - - - - - - - - - - - - - -

OWTS1 PTE 116.4 73.00 4 - - - - - 82.9 11.45 8 42.1 15.88 5 77.6 17.86 17

OWTS1 BFE 46.3 11.35 4 - - - - - 32.1 1.89 8 23.6 3.10 5 33.7 4.09 17

OWTS1 PRE 13.1 5.89 4 - - - - - - - - - - - - - - - - - - - -

OWTS2 PTE 75.1 23.21 4 - - - - - - - - - - - - - - - 67.9 8.93 17

OWTS2 AXE 5.1 1.96 4 - - - - - - - - - - - - - - - 24.0 3.88 17

OWTS2 PRE 7.1 2.06 4 - - - - - - - - - - - - - - - - - - - -

HH STE - - - - - - - - - - 57.1 4.97 8 34.6 3.74 7 46.6 3.98 15

HH PTE - - - - - - - - - - 18.5 2.30 8 5.8 1.12 7 11.5 1.99 15

HH AXE - - - - - - - - - - 2.7 0.72 8 1.8 0.36 7 2.6 0.54 15

HH PRE - - - - - - - - - - - - - - - - - - - - - - - - -

Table 2. Average total suspended solids (TSS)in mg/L determined for onsite wastewater treatment systems

between 2008 and 2011, with calculated standard error (SE), sample size (n) for 2008 through 2011 and over

the entire monitoring period.

Total Suspended Solids

Site2008 2009 2010 2011 overall

Figure 3. Average 2008-2011 total suspended solids (TSS) in mg/L determined for onsite wastewater

treatments systems. Bars indicate standard error.

0

20

40

60

80

100

UIC OWTS1 OWTS2 HH

To

tal

Susp

end

ed S

oli

ds

(mg/L

)

Site

Total Suspended Solids

- 7 -

average +\- SE n average +\- SE n average +\- SE n average +\- SE n average +\- SE n

UIC1 57.82 2.48 13 43.81 6.30 6 61.73 1.90 5 36.03 10.24 6 51.31 3.07 30

UIC2 59.29 2.33 13 38.81 6.86 6 62.06 1.97 5 31.74 9.49 6 50.14 3.33 30

UIC3 60.51 4.04 13 38.44 6.61 6 61.04 1.74 5 36.00 8.25 6 51.28 3.38 30

UIC4 25.54 0.95 13 35.13 5.50 6 30.20 - - 1 24.11 7.21 5 27.74 2.06 25

OWTS1 PTE 2.39 1.53 7 22.46 1.14 4 37.92 11.76 5 42.50 10.74 5 20.34 5.51 21

OWTS1 BFE 31.95 3.95 15 54.28 10.37 6 80.30 7.37 5 59.40 2.76 5 48.50 4.34 31

OWTS1 PRE 32.19 5.45 13 32.31 4.71 6 40.60 - - 1 19.90 16.55 3 30.99 3.74 23

OWTS2 PTE 0.05 0.01 6 0.46 0.16 6 - - - - - - - - - - - - 11.33 5.35 17

OWTS2 AXE 29.54 6.38 6 24.63 8.83 5 - - - - - - - - - - - - 43.87 7.52 16

OWTS2 PRE 22.78 4.88 7 7.52 1.35 6 - - - - - - - - - - - - 17.51 3.62 14

HH STE - - - - - - 0.15 0.04 5 - - - - - - - - - - - - 0.15 0.04 5

HH PTE - - - - - - 32.82 5.36 6 42.00 4.21 5 45.83 4.17 7 40.43 2.86 18

HH AXE - - - - - - 39.17 3.51 6 50.25 1.58 5 44.81 3.49 7 44.44 2.04 18

HH PRE - - - - - - 39.97 3.61 5 55.00 - - 1 46.08 3.19 6 44.28 2.45 12

Table 4. Average ammonium (NH4)in mg/L determined for onsite wastewater treatment systems between 2008

and 2011, with calculated standard error (SE), sample size (n) for 2008 through 2011 and over the entire

monitoring period.

Table 3. Average nitrate concentration in mg/L determined for onsite wastewater treatment systems between

2008 and 2011, with calculated standard error (SE), sample size (n) for 2008 through 2011 and over the entire

monitoring period.

2009 2010 2011 overallSample

2008

Nitrate

Sample 2008 2009 2010 2011 overall

average +\- SE n average +\- SE n average +\- SE n average +\- SE n average +\- SE n

UIC1 1.70 0.75 7 1.05 0.44 5 0.71 0.33 5 45.31 18.14 5 11.24 5.53 22

UIC2 1.59 0.71 6 0.97 0.49 5 0.77 0.38 5 52.31 16.21 6 15.10 6.47 22

UIC3 1.36 0.74 7 1.02 0.55 5 0.64 0.35 5 49.68 15.38 6 13.73 5.90 23

UIC4 3.02 0.78 10 8.53 4.14 4 0.09 0.04 4 44.85 17.27 5 12.56 5.08 23

OWTS1 PTE 87.71 5.79 15 73.47 6.10 6 88.90 2.51 5 62.10 4.42 5 81.02 3.56 31

OWTS1 BFE 46.34 3.91 15 46.16 4.40 6 39.74 2.61 5 44.20 4.85 5 44.90 2.22 31

OWTS1 PRE 42.44 2.89 13 26.87 7.00 6 20.20 3.18 4 51.13 4.10 4 36.97 2.93 27

OWTS2 PTE 85.43 2.60 9 63.27 7.03 6 - - - - - - - - - - - - 76.48 3.44 23

OWTS2 AXE 23.35 8.66 7 50.44 9.74 6 - - - - - - - - - - - - 37.15 4.56 21

OWTS2 PRE 26.93 7.95 7 24.53 4.20 6 - - - - - - - - - - - - 26.80 3.58 19

HH STE - - - - - - 63.99 9.96 5 78.20 2.47 5 63.56 10.49 7 67.99 5.24 17

HH PTE - - - - - - 16.12 2.08 6 18.30 4.30 5 10.09 2.86 7 14.38 1.87 18

HH AXE - - - - - - 3.00 1.79 3 0.87 0.38 4 0.04 0.02 7 0.91 0.46 14

HH PRE - - - - - - 0.24 0.06 2 1.68 0.30 4 0.04 0.02 7 0.58 0.23 13

monitoring period.

Ammonium

- 8 -

Figure 4. Average 2008-2011 nitrate and ammonium concentrations in mg/L determined for onsite

wastewater treatments systems. Bars indicate standard error.

0

20

40

60

80

100

120

UIC OWTS1 OWTS2 HH

Co

nce

ntr

atio

n m

g N

/L

Site

Ammonia (mg/L)

Nitrate (mg/L)

- 9 -

average +\- SE n average +\- SE n average +\- SE n average +\- SE n average +\- SE n

UIC1 7.03 0.66 12 10.18 1.49 6 9.1875 1.14 8 11.4183 0.855 6 8.98475 0.558 32

UIC2 6.60 0.37 12 9.98 1.57 6 9.08625 1 8 11.6283 0.881 6 8.79827 0.537 32

UIC3 6.34 0.32 12 10.64 1.91 6 9.4525 1.03 8 11.2417 0.846 6 8.84218 0.582 32

UIC4 0.66 0.09 12 5.25 1.37 6 3.555 1.08 8 5.062 0.915 5 3.00343 0.527 31

OWTS1 PTE 11.70 0.69 13 15.96 1.99 6 14.3457 1.37 7 11.56 0.621 5 13.1008 0.637 31

OWTS1 BFE 12.57 0.85 13 18.80 1.69 6 17.6014 2.09 7 15.96 2.089 5 15.4614 0.854 31

OWTS1 PRE 9.77 0.60 11 0.89 0.14 6 2.91125 1.18 6 2.36 0.44 3 5.2837 0.859 26

OWTS2 PTE 9.55 0.22 8 11.64 1.96 6 - - - - - - - - - - 11.7445 0.821 21

OWTS2 AXE 9.07 0.44 5 12.73 1.81 6 - - - - - - - - - - 13.6071 1.285 18

OWTS2 PRE 6.71 0.90 6 0.61 0.23 6 - - - - - - - - - - 3.4106 0.77 18

HH STE - - - - - 9.42 1.53 4 11.17 1.09 8 10.14 0.62 7 10.42 0.59 19

HH PTE - - - - - 8.95 1.80 5 10.25 1.40 8 8.33 0.35 7 9.25 0.71 20

HH AXE - - - - - 11.51 2.06 5 10.99 1.47 8 7.45 0.45 7 9.88 0.86 20

HH PRE - - - - - 7.86 1.79 5 11.74 1.34 8 7.51 0.48 6 9.38 0.85 19

Table 5. Average total phosphorus concenration (TP)in mg/L determined for onsite wastewater treatment

systems between 2008 and 2011, with calculated standard error (SE), sample size (n) for 2008 through

2011 and over the entire monitoring period.

Total Phosphorus

Site2008 2009 2010 2011 overall

Figure 5. Average 2008-2011 total phosphorus (TP) in mg/L determined for onsite wastewater treatments

systems. Bars indicate standard error.

0

2

4

6

8

10

12

14

16

18

UIC OWTS1 OWTS2 HH

To

tal

Pho

spho

rus

(mg/L

)

Site

Total Phosphorus

- 10 -

N Removal

% n % n % n % n %

UIC 22 31/29 4 18 66 32/31 -0.6 22/25 37

2008 40 10/9 91 4 90 12 0.5 7 52

2009 57 6/5 - - - - 51 6 80 5/4 2

2010 27 10 48 8 62 8 1 5/4 51

2011 19 5/6 23 6 55 6/5 1 5/4 15

OWTS 1 50 30/28 57 17 66 31/26 54 31 33

2008 34 11/8 60 4 22 13/11 47 15 13

2009 59 5/6 - - - - 95 6 63 6 36

2010 72 10 61 8 83 7 77 5 52

2011 14 5 44 5 85 5/3 18 6 32

OWTS 2 84 11/10 65 17 75 18 65 23/21 50

2008 94 6/4 93 4 26 5/6 74 9/7 42

2009 76 5/6 - - - - 95 6 61 6 50

2010 - - - - - - - - - - - - - - - - - -

2011 - - - - - - - - - - - - - - - - - -

HH 99 21 94 15 5 20/19 99 17/14 34

2008 - - - - - - - - - - - - - - - - - -

2009 97 5/6 - - - - 32 5 99 5/3 37

2010 99 9 95 8 -7 8 98 5/3 35

Table 6. Average rates of removal or reduction for CBOD, TSS, TP, NH4, and Nitrogen calculated for each

onsite wastewater treatment system overall and for each year 2008 through 2011, with sample size (n).

TP NH4 DecreaseSystem

CBOD TSS

2010 99 9 95 8 -7 8 98 5/3 35

2011 99 7 95 7 -1 7/6 99 5/3 29

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Upland Interpretive Center (UIC) Typical flow through the system was greatly below the design flow capacity for the

majority of the monitoring period; throughout the monitoring period the system produced high

quality effluent, meeting the NSF Standard 40 for Class 1 ATUs (30mg/L CBOD and TSS). In

2010 the system saw more consistent usage and monitoring results indicate enhanced reduction

of CBOD and TSS, with high quality effluent produced (final CBOD < 11 mg/L, TSS = 11

mg/L). In 2011, the system experienced a period of intense use, which may have been beyond

the treatment capacity of the system. Though this period was relatively short in comparison to

the monitoring period (10 days of use by 19 individuals), average 2011 effluent CBOD and TSS

concentrations increased substantially, to 54 mg/L and 22 mg/L, respectively (Tables 1 and 2).

Over the 4-year monitoring period, the system proved to handle long periods of low usage well.

The size of the system is able to accommodate sporadic short-duration heavy-use events without

noticeable influence on the quality of final effluent.

Though nitrogen reduction is not a priority of treatment in the Otsego Lake watershed’s

wastewater management program, the nitrogen transformations that take place in advanced

treatment systems are notable and give insight into the conditions within the treatment system.

The final effluent from the UIC system contains relatively high nitrate to ammonium ratio,

indicating that the aeration provided in the unit is sufficient for nitrification to take place.

System-wide over the 4-year period, nitrogen was reduced by 37%; better removal rates occurred

during years where use of the system was higher (without exceeding the design-capacity) (Table

6).

Operational Notes

The only major issue encountered with the UIC system was related to its installation.

The mid-seam of the 3-compartment tank was not properly sealed at the time of installation. For

the first season of its use, the full operating level was never attained (i.e. the tank remained

approximately half-full). The problem was not immediately diagnosed because of the low use of

the system during non-summer months. Following repair the system has maintained an

appropriate operating level.

The blower/aerator by design runs full-time (24/7) and has had no mechanical problems

to date. The microbiological inoculant must be replaced on occasion; this doesn’t seem to be

critical in the overall functionality of the system. As with all four monitored systems, the

nutrient removal unit’s reactive media must be replaced regularly to maintain high phosphorus

removal rates and sufficiently low final P concentrations. This is likely more important for units

serving systems in close proximity to P-limited water bodies.

Onsite Wastewater Treatment System 1 (OWTS 1)

The configuration of this system seems to be less robust than others for seasonal-use

situations, due in large part to the above-ground installation of the media filter combined with

summer-only use and the long start-up time for the microbiological community that lives in and

on the foam media. The foam media comprising the filter in this system is susceptible to settling

over time, especially during periods of freeze and thaw. This particular system is installed above

ground, and therefore is subjected more extreme temperature variation than its below-ground

counterparts. Extreme temperature fluctuations and long period of dormancy (without nutrient,

carbon, and water supply) also influence the microbial community, contributing to the long

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period of time required for treatment performance to reach a consistent level following dormant

periods. Treatment performance of this particular installation did not meet the manufacturer’s

expectation (Jowett 2010) nor was it consistent with the results of other field testing studies

(ETV 2003, MASSTC 2004). This discrepancy is likely due to the difference in both

configuration and actual use of the system.

Treatment of BOD and TSS improved steadily over the duration of the monitoring

program and treatment proved to be enhanced by spring maintenance to combat settling of the

foam media that may have occurred during the winter. BOD and TSS concentrations averaged

43 and 33 mg/L, respectively, following treatment in the foam filter. This does not meet the

industry standard of 30 mg/L for each parameter (for secondary treatment performance as Class

1 Aerobic Treatment Unit, media filter, etc), though the system was likely still in the “start-up”

phase for the majority of the monitoring period each summer. Monitoring protocols used in this

study are also different than those used by the National Sanitation Foundation when testing

advanced treatment systems again performance criteria (NSF 2007).

Nitrogen concentrations were in line with the other systems monitored, though the

incoming ammonium concentration was generally greater than the other systems. This is likely

due to the fact that the system was being used on a regular basis and with water conservation in

mind, producing a more concentrated waste. Over the entire monitoring period, nitrogen

removal averaged about 33%. The reduction of ammonium concentration before and after

treatment by the foam filter unit (54%) was less than that achieved by the other systems; this

indicates a less effective conversion of ammonium to nitrate within the foam filter itself.

Following a service visit in early 2010, the ammonium reduction rate increased (to 77%),

indicating that the environment within the filter was better suited to facilitate the nitrification

process.

Operational Notes

Operation and maintenance issues were related to settling of the foam media over time.

Spring maintenance was effective at restoring the treatment performance for all parameters. This

servicing involved redistribution of the foam to restore the original packing density and eliminate

any preferential flow paths that had allowed wastewater to short-circuit the media. Ideally,

wastewater should trickle in a thin film through and around the foam cubes.

Odor coming from this system was also a major issue for the property owners, though it

was a design flaw that did not directly impact the treatment performance and was independent of

the manufacturers of the treatment components. Three sources of odor were identified; one was

the system’s vent stack, another was the lid of the equalization tank, which receives processing

tank effluent (mix of septic tank of effluent and foam filter effluent), and the third was the

electrical conduit connecting the pump vault to the control panel. All three sources were

remedied, though these should be considered by the design engineer prior to installation. The

vent stack was extended above the roof-line in order to physically move it away from the patio

and deck areas of the two camps served by the system. This pipe was also capped with a carbon-

filter assembly to reduce the final odor. The equalization tank’s cover is of poor design and does

not provide an air-tight or water-tight seal at the surface. The odor was greatly reduced by

weighting the lid down; ideally, this lid should be replaced with a model that will provide a more

secure seal. The conduit from the pump vault to the control panel was left unsealed by the

installer, and so proved to be the preferential flow path for gas exchange. This conduit was

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sealed with a caulking agent, eliminating the odor problem. All-in-all, while the odor problem

did not directly affect treatment performance, public perception and acceptance of advanced

treatment systems can be negatively impacted by such oversights.

Onsite Wastewater Treatment System 2 (OWTS 2)

Overall treatment performance met expectations in 2008 and most of the 2009 monitoring

period compared to the performance of other systems of this type. Prior to the operational

problems that began in 2009, OWTS 2 produced high quality effluent containing less than 15

mg/L BOD and TSS on average (Tables 1 and 2) with nitrogen removal between 42 and 50%

(Table 6). As a result of the operational issues and subsequent maintenance that was required

this system was not monitored in 2010 or 2011.

Operational Notes

This system experienced periods of poor treatment unrelated to the design or the

treatment processes employed in the system. One of the camps served by the system underwent

major renovations, during which time electrical power to the system was inadvertently shut off;

this system does not operate by gravity-flow, and so relies on timers, switches, and pumps for

proper cycling of wastewater between the treatment components. Although no one was living in

the renovated camp, the other camp served by the system was still occupied and sending

wastewater to the system. Wastewater was not treated properly and resulted in fouling of the

nutrient removal device. The problem persisted though 2011 due to lack of communication

between the main service provider to the system and the homeowner, as well as between the

main service provider and the manufacturer/service provider for the nutrient removal unit.

This issue highlights a number of areas where more work is needed to ensure that

advanced treatment systems are operating properly and to the best of their ability; (1) the need

for effective communication between involved parties (regulators, homeowners, and service

providers) to ensure that maintenance contracts are in place and carried out according to the

manufacturer’s guideline (2) the challenges associated with effectively operating a shared system

and (3) the need for homeowners to be aware of the system’s function and operation. All users

of the structure must be aware of “good practices” for disposal of wastes in the system – this

includes tenants, contractors, guests, etc. These systems are highly engineered and treatment

often relies on the presence of beneficial microbial communities. Disposal of chemicals, paints,

disinfectants, etc. can reduce or eliminate the populations of such microbes and may also cause

fouling of or reduced longevity of other physical and mechanical components of the system (e.g.

textile fabrics, coarse filters, pumps, etc.).

Hop House (HH) Treatment performance has consistently been at a high level and no major maintenance

issues have occurred to date aside from the high media replacement rate for the nutrient removal

unit. Incoming waste was of typical strength (100-600 mg/L) for American households. CBOD

and TSS concentrations averaged 3 mg/L following treatment in the textile filter (Tables 1 and

2); this is an exceptional level of treatment and standard error indicates a low degree of

variability with respect to fluctuations in the concentration of these two parameters. Ammonium

concentration was reduced to less than 1 mg/L on average (Table 4), a 99% reduction from the

septic tank effluent to textile filter effluent. Nitrogen removal averaged around 34%, which is

- 14 -

lower than seen in OWTS 2, and may be enhanced by altering the system dosing cycles based on

the actual flow received; this is discussed further in the Operational Notes.

Operational Notes

No major treatment or mechanical issues were encountered during the monitoring period;

all pumps and controls are functioning properly. This particular system has a larger design

capacity than a typical residential situation (the Hop House and Boat House are served in

addition to a residence); however, the actual flow through the system has generally been less

than anticipated. Actual flow through the system can be calculated, but to date this information

has not been used to adjust the rate at which wastewater is cycled from the processing tank to the

textile filter. As a result, the textile filter is dosed more often than is necessary to adequately

treat the waste and therefore the processing tank does not consistently maintain an anaerobic

environment to facilitate denitrification (final step of nitrogen removal) of effluent coming in

from the textile filter. Treatment would be enhanced by increased oversight of the system by the

service provider.

Phosphorus Removal Components

The nutrient removal devices are designed to remove phosphorus from the wastewater via

chemical adsorption of phosphorus onto the surface of a reactive porous media. Over time the

active sites are occupied by adsorbed phosphorus and the efficiency declines until no active sites

remain. These work well but require frequent replacement in order to maintain high degree of

phosphorus removal, as a result of the relatively small volume of reactive media in each unit.

Larger media canisters would reduce the frequency of media replacements. The size of each unit

was not scaled to correspond to the designed treatment capacity of the system with which it was

installed. In the case of the Hop House system, following replacement of the reactive media,

acceptable treatment was documented for less than 3 months before the adsorptive capacity of

the media was reached. Frequent sampling and analysis for total phosphorus concentration is the

only way to determine the efficacy of each unit; it is unlikely that such sampling would be done

more than once per year in a typical residential situation.

CONCLUSIONS

Treatment Technologies

Media Filters (Textile, Foam, Dosing Regime)

Textile filters provided the most consistent and effective treatment of the three types

installed in the demonstration systems. CBOD and TSS were consistently below 15 mg/L and

showed little variation over the sampling period under normal operating conditions. The filter

media are arranged in hanging sheets, and so are not subject to settling or compaction over time;

it seems that this arrangement, combined with an insulated cover and below-ground installation,

result in a short start-up period at the beginning of the occupancy season.

The foam filter’s performance was variable and frequently fluctuated above the industry

standard for this class of system. When installed for seasonal use, spring maintenance is needed

to ensure that the media is properly distributed in the baskets, as settling may have occurred due

- 15 -

to freeze and thaw during the winter. A long period of time (upwards of 8 weeks in some cases)

was required at the start of each summer occupancy season for the establishment of a sufficient

microbial community such that consistent and acceptable treatment was documented. Microbial

populations are greatly reduced during periods without flow (i.e. winter) and are likely further

reduced during periods of extreme cold. This should be considered in the design process if this

technology is to be used at other seasonal installations; installing the media filter underground

may provide enough thermal buffering to reduce the temperature fluctuation and in so doing,

reduce the settling and start-up period.

Differences observed in the treatment performance of the foam and textile filters may be

related more to the dosing regimens rather than the ability of either media to provide a favorable

treatment environment. Dosing regimes are typically based on either time or demand (flow).

• A Timed Cycle: A predetermined volume is dosed at a regular time interval. Both

systems incorporating textile filters (OWTS 2 and HH) were time-dosed (a

requirement of the manufacturer).

o Storage capacity is built-in to allow for holding of wastewater for later

processing based on default schedule

o Flow is distributed over a 24-hour period

� Eliminates potential inundation of treatment components and the

drainfield;

• Holds water during high-use periods (shower-time, laundry,

etc.)

• Cycles wastewater throughout the day and night, providing

consistent flows to the treatment technologies and the

drainfield during lower-use periods

� Allows for alternation between unsaturated and saturated flow, and

thus, aerobic and anaerobic conditions

• Facilitates gas exchange

• Facilitates activity of both aerobic and anaerobic microbial

populations – together yield more effective and complete

breakdown of wastewater constituents

o Floats detect high-flow conditions and can trigger the over-ride of default

timing cycle to more quickly process wastewater, accommodating extreme

events without compromising the integrity of system components.

o In seasonal-use or weekend-use situations, cycling of wastewater between

a processing tank and the filter continues even during periods where no

new water enters the system, maintaining nutrient and water supply to the

microbial populations.

• Demand (flow through the system): A predetermined volume is transferred every

time that specific volume accumulates in a dosing chamber. The foam filter

(OWTS 1) operated on demand-dosing.

o During high flow periods, wastewater may be dosed without a time delay

in order to keep up with incoming flow. This may result in the inundation

of subsequent treatment components (such as a nutrient removal device)

that have a limited volume capacity and require a longer period of time for

wastewater to pass through.

- 16 -

o During periods with little or no use, no water is dosed to the filter unit,

potentially resulting in a reduction in the microbial population.

.

Aerobic Treatment Unit

The aerobic treatment unit (ATU) serving the UIC produced effluent of consistent

quality, though the system saw very low use compared to its designed capacity. CBOD and TSS

were generally below 15 mg/L and nitrogen was removed at moderate rates. It handled typical

UIC functions and events (field trips, workshops, etc.) and long periods of low use very well

without compromising effluent quality.

Phosphorus Removal Devices

The effective life-span of the reactive media within the phosphorus removal devices was

disappointing, especially given the cost of the units and fees associated with media replacement.

These units work well but require frequent replacement in order to maintain high degree of

phosphorus removal as a result of the relatively small volume of reactive media in each unit.

Larger media canisters would reduce the frequency of media replacements. In order to

adequately address the need for phosphorus removal in certain locales, a more affordable,

longer-lasting design is essential.

Monitoring Procedures

Sampling protocols can influence the observed treatment performance and varies with the

type and configuration of each system. Comparisons between monitoring and assessment efforts

should acknowledge such details.

• Grab samples are likely to be more variable and have a higher associated

standard error if the quality of effluent is variable over the course of a day.

• Composite samples capture the range of conditions encountered throughout the

day, providing flow-weighted results of effluent quality produced by the system.

• The potential for sampling protocol to influence results will vary with the

configuration of the system.

o Some systems continuously mix wastewater and yield more consistent

results over the course of a 24-hour period, whereas a system with discrete

treatment components will experience variation over the course of a day,

depending on use of the system, in which case a grab sample may yield

non-representative results if such factors are not considered.

• Sufficient sample size should allow for a range of conditions to be encountered,

providing an average that is representative of the effluent quality that typically

leaves the system, though this cannot be guaranteed.

Lessons Learned

Oversight of Operation & Maintenance

Communications with service providers and manufacturers resulted in remedied issues

and increased treatment performance. Vigilance in the maintenance of advanced treatment

systems is of the utmost importance if these systems are to be relied upon to reduce human

- 17 -

impacts to sensitive environments, especially considering that the vast majority of systems are

not monitored once they are installed, as they were with this project.

Property Owner Awareness & Proper Use Homeowners, as the primary users of such systems, are the key to ensuring proper use

and maintenance. Steps should be taken to stress the importance of their participation as a means

of protecting their investment in addition to protecting public health and their surrounding

environment. In a few instances, as outlined in the system performance section of this report,

operational issues occurred due to a lack of communication between the property owners of

shared systems, or between the property owners and others that were renting or working on the

property. Owners failed to recognize the importance of informing the other users as to the

requirements of the system (i.e. electrical power) and best practices for disposal of materials to

the system.

REFERENCES

Albright, M.F. and H.A. Waterfield. 2010. Evaluation of phosphorus removal media for use in

onsite wastewater treatment. In: 42nd

Ann. Rept. (2009). SUNY Oneonta Bio. Fld. Sta.

Cooperstown, NY.

Albright, M.F., L.P. Sohaki, and W.N. Harman. 1996. Hydrological and nutrient budgets for

Otsego Lake, N.Y. and relationships between land form/use and export rates of its sub-

basins. Occ. Paper #29, SUNY Oneonta Bio. Fld. Sta., SUNY Oneonta.

Anonymous. 1998. A plan for the management of the Otsego Lake watershed. Prepared by:

Otsego Lake Watershed Council.

Anonymous. 2007. A plan for the management of the Otsego Lake watershed. Prepared by:

Otsego Lake Watershed Council (1998). Updated by the Otsego County Water Quality

Coordinating Committee.

APHA, AWWA, WPCF. 1992. Standard methods for the examination of water and wastewater,

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Crites, R. and G. Tchobanoglous. 1998. Small and Decentralized Wastewater Management

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Model 4-Bedroom. National Sanitation Foundation and

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Green, L. 2004. Standard Operating Procedure 011: Biochemical Oxygen Demand (BOD)

Procedure. University of Rhode Island Watershed Watch.

Harman, W.N. 1997. The state of Otsego Lake 1936-1996. Occ. Paper #30, SUNY Oneonta Bio.

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Jowett, C. 2010. Personal Communication. February 2010.

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