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Case Study

UV Disinfection Interference From Industry

MWEA Industrial Pretreatment Seminar

October 24, 2007

Jack D. Fraser City of Big Rapids

Jerald O. Thaler, P.E.Fishbeck, Thompson, Carr & Huber, Inc.

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AGENDA

• The UV Interference Mystery

• Transmittance Local Limit Development

• Summary

• Questions

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The UV Interference Mystery

• In 2002, Nestle Waters North America opened a major pumping and bottling facility in Stanwood, Michigan.

• Facility has 145 employees, 80% live within 30 miles.

• Produces Ice Mountain® bottled water and Pure Life ® (“Splash”) fruit-flavored water.

• Wastes originally trucked to Grand Rapids area.

Background

• WWTP operational problems with aging UV disinfection system.

– Periodic fecal coliform violations.

– Preliminary engineering began for a new system.

• City received inquiries about accepting “clean” process wastes from Stanwood facility.

– Previous policy - not to accept hauled waste.

– Expected monthly revenue to City - up to $25,000.

2003 - 2004

• City performed characterization of process wastes from Stanwood facility.

• In June, City granted approval and trucking of wastes to WWTP began.

• Construction of replacement UV system started in July.

2005

• Periodic fecal coliform violationscontinued.

• Fecal coliform violations continued, even after start-up of new UV system.

• MDEQ initiated formal enforcement action.

• Aggressive investigations into cause:

– Transmittance testing of effluent and each truckload.

– Operators noted color/odor changes in trucked waste and at WWTP headworks.

– Evaluation of Stanwood facility raw materials by Mr. Michael Goergen of Merit Laboratories, Inc.

2006

• Investigations indicated cause of interference was potassium sorbate:

– Natural preservative, commonly used in foods.

– Additive in Splash fruit-flavored water product.

– Absorbs UV at approximately same wavelength as is optimum for microorganism deactivation.

• Question - How to control…

Mystery Solved

H3C H

C = C H

H C = C

H COO– K+

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Development of Local Limitfor Transmittance

• Option 1 – Chemical-Specific Local Limit

– Not directly correlated to observed interference.

– Testing issues

• Turnaround time

• Cost

Control Mechanism forPotassium Sorbate

Control Mechanism forPotassium Sorbate (cont’d)

• Option 2 – Transmittance Local Limit

– Direct correlation to observed interference.

– Straightforward testing.

– But…

No experience or EPA/MDEQ guidance on developing transmittance local limit.

General Methodologyfor Local Limit Development

1. Calculate maximum allowable headworks loading (MAHL):– Pass-through– Sludge Quality– Inhibition

2. Calculate domestic/background loading (LBKGD).

3. Calculate maximum allowable industrial loading (MAIL):

MAIL = MAHL*(1-SF) - LBKGD

4. Allocate MAIL among significant industrial users (SIUs).

Transmittance

• Definition of transmittance (T):

where: I = intensity of UV light leaving sample

Io = intensity of UV light entering sample

• Not concentration-proportional; not additive.• Not adaptable to mathematical manipulation.

100I

IT

o

Absorbance

• Related parameter, absorbance (A), is related to T by Beer’s Law:

or

• Both concentration-proportional and additive• Adaptable to mathematical manipulation

A10100T

log(T/100)A

Proposed Calculation Procedure

1. Assume effluent absorbance (AEFF) is additive from:

– Residual effluent total suspended solids (TSS):

– Pass-through of background sources:

– Pass-through of trucked waste source:

)100BKGD

R(1

BKGDA

)100SIU

R(1

SIUA

EFFTSS

TSSΔA

Proposed Calculation Procedure

2. Assume AEFF maintained at or below maximum value (AMAXEFF) less safety factor (XSF):

3. Calibrate parameters using site-specific data, then solve above equations for ASIU.

4. Transpose ASIU to TSIU:

)100

X(1AMAXA SF

EFFEFF

SIUSIU

A10100T

Site–Specific Calibration• ΔTSS

0.0

0.1

0.2

0.3

0.4

0.5

0 10 20 30 40 50 60

TSS, mg/L

Abs

orb

an

ce

ΔATSS = 0.00701

Site–Specific Calibration (cont’d)

• ABKGD*(1-RBKGD/100)

Effluent Transmittance

%

Effluent TSS mg/L

Effluent Absorbance

TSS Correction

Corrected Effluent

Absorbance

Corrected Effluent

Transmittance %

a.m. 61 17 0.215 0.119 0.096 80

p.m. 55 18 0.260 0.126 0.133 74

April 7, 2004 a.m. 54 24 0.268 0.168 0.099 80

April 8, 2004 a.m. 58 23 0.237 0.161 0.075 84

a.m. 54 33 0.268 0.231 0.036 92

p.m. 56 20 0.252 0.14 0.112 77

a.m. 57 19 0.244 0.133 0.111 77

p.m. 61 14 0.215 0.098 0.117 76

April 11, 2004 p.m. 62 17 0.208 0.119 0.088 82

57 0.240 0.096 80

ABKGD*(1-RBKGD/100)

Measured Calculated

April 6, 2004

April 9, 2004

April 10, 2004

Average

Sampling Event (without SIU discharge)

Site–Specific Calibration (cont’d)• AMAXEFF

Design Basis

NPDES Limit

Pass-through

0

200

400

600

800

0.000 0.100 0.200 0.300 0.400 0.500 0.600

Effluent Absorbance

Eff

luen

t F

ecal

Col

iform

, co

unts

/100

mL

Design Basis Pass-through

NPDES Limit

(AMAXEFF)

Site-Specific Parameters

• RSIU

Data showed lower A at higher trucked waste volume, but effluent remained relatively constant.

0.0

1.0

2.0

3.0

4.0

5.0

0 25,000 50,000 75,000 100,000 125,000

Trucked Waste Volume, gal/day

Tru

cked

Was

te A

bsor

banc

e

ASIU = 2.32 – 1.58x10-5*QSIU

0.0

0.1

0.2

0.3

0.4

0.5

0 25,000 50,000 75,000 100,000 125,000

Trucked Waste Volume, gal/day

Eff

luen

t A

bso

rban

ce

(B

ack

gro

und-

and T

SS

-corr

ect

ed)

0.0

0.1

0.2

0.3

0.4

0.5

0 1 1 2

SIU Flow, gal/day

Eff

lue

nt

Ab

sorb

an

ce (

TS

S-c

on

tro

lled

)

0.0

0.1

0.2

0.3

0.4

0.5

0.0 0.5 1.0 1.5

Discharge Absorbance

Eff

lue

nt

Ab

sorb

an

ce (

TS

S-C

otr

rect

ed

)

50%

60%

70%

80%

90%

100%

0 25,000 50,000 75,000 100,000 125,000

Trucked Waste Volume, gal/day

Rem

oval

of

Tru

cked

Was

te A

bsor

banc

e

ASIU = 2.32 – 1.58x10-5*QSIU

AEFF’ = 0.065 + 2.30x10-8*QSIU

Site-Specific Parameters (cont’d)

RSIU decreased at higher trucked waste volume:

60%

70%

80%

90%

100%

0 25,000 50,000 75,000 100,000 125,000

Trucked Waste Volume, gal/day

RS

IU

Results• Solving for ASIU and transposing to TSIU produced

family of curves for local limit:

0

20

40

60

80

100

0 25,000 50,000 75,000 100,000 125,000

Trucked Waste Volume, kgal/day

Min

imu

m T

ran

smitt

an

ce,

Da

ily A

vera

ge

%

Effluent TSS

10 mg/L

5 mg/L

15 mg/L

17.5 mg/L

>18.5 mg/L

Results (cont’d)• Permit negotiations between City and Nestle

Waters led to following permit conditions:– No acceptance if TSSEFF exceeds 15 mg/L.

– Maximum QSIU of 120,000 gal/day.

– Minimum transmittance of 70%.

0

20

40

60

80

100

0 25,000 50,000 75,000 100,000 125,000

Trucked Waste Volume, kgal/day

Min

imu

m T

ran

smitt

an

ce,

Da

ily A

vera

ge

%

Effluent TSS

10 mg/L

5 mg/L

15 mg/L

17.5 mg/L

>18.5 mg/L

Summary

• “Clean” waste caused interference in this case.

• For T limit, use general methodology based on A.

• Must specify both TSSEFF and QSIU to set limit.

• Lessons learned:

– You never know what you will get with trucked waste.

– Use all your resources to maximize knowledge.

– Get it in writing before it happens.

– Permit the discharger, not the transporter.

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Questions