Using the CPE Approach to Optimize Industrial Waste

Treatment Facilities

Ronald G. Schuyler and Michael Rothberg

Rothberg, Tamburini, and Winsor, Inc.

Denver, CO

And

Deb Skirvin, Steve Hamilton and Kelly Peters

Hercules Incorporated, Louisiana, MO

RTW

Coauthors

• Mike Rothberg, RTW

• Deb Skirvin, Hercules

• Steve Hamilton, Hercules

• Kelly Peters, Hercules

Comprehensive Performance Evaluation

• CPE - Evaluation Phase• Design, administration, operation, maintenance• Assess capability of major unit processes• Identify performance limiting factors

• CCP - Composite Correction Program phase• Systematic approach• Eliminate factors inhibiting performance

*

*Hegg, DeMers and Barber

CPE Process

• Originally designed for municipal facilities• Evaluation approach• Major unit process criteria • Administration, design, operation, maintenance factors

• Approach applied to industrial facilities• Revised loading criteria• Same biological, chemical and physical laws• Apply them to minimize poor performance

Procedure

• Become familiar with existing facility

• Define present plant loadings

• Define major unit process characteristics

• Define present operating conditions

• Suggest process control modifications

• Suggest simple process modifications

• Identify longer-term oriented modifications

Communications

• Operation/consultant staffs side-by-side• Lab• Control room• On/in the tanks

• 3-4 days• Listen to operating staff experience• Compare to accepted standards• Verify validity or suggest alternate finding

Missouri Chemical Works

Return Sludge

A Tank2.0 MG

Winter Heating

Summer Cooling

EQ Tank2.7 MG

Nitroform & Storm

Clarifiers

PolymerPE

Lake

Formaldehyde &Methanol Wastes

Stormwater

Effluent

EffluentRecycleDecant

Sludge Pond

WasteSludge

1996 Conditions

• Flow = 0.32 MGD• Influent

• BOD = 11,190 lb/day (about 4,193 mg/L)• COD = 23,915 lb/day (about 8,961 mg/L)

• Effluent• BOD = 77 lb/day (about 29 mg/L)• COD = 1,271 lb/day• TSS = 50 lb/day (about 19 mg/L)

1996 Process Data

• MLSS/MLVSS = 6,305/5,376 mg/L (85% vol)• RAS flow = 0.504 MGD, 160% of influent• WAS = 1,460 lb/day• MCRT = 73 days• F/M < 0.1 lb/lb• Polymer added = 283 lb/day (1995/96 Ave.)• Antifoam added = 54 gal/mo (1995-96 Ave.)

PE Lake

• Flow equalization

• Load equalization

• Toxic materials such as formaldehyde

• Slowly degradable formaldehyde derivatives

• Storm water

• Some volatilization of organics

EQ Basin

• Maintained at 10-10.5’ depth

• Load equalization

• About 7 days DT

• Received no return sludge

• Aerated to control odors

• 25% COD removal without biomass return

• No temperature control

Aeration Tank

• 20’ deep

• Parkson Biolac aeration chains

• 2.4 days detention time @ Q = 0.5 MGD and RSF = 0.5 MGD

• MLSS about 6,000 mg/L

• Maintain temperature about 95°F (35°C)

• Volumetric loading = 32-52 lb BOD/103 ft3

Secondary Clarifiers

• 2-45’ diameter, 12’ deep• 101 gal/ft2/day, 13.6 lb MLSS/ft2/day• Return ratio

• Average = 160%• Peak month = 312%

• Blanket thickness about 1-2 feet• Periodic “black” layer required high RSF• Polymer addition

• Average = 283 lb/day• Peak month = 620 lb/day

Process Modifications

• Convert EQ basin to aeration tank

• Reduce MLSS in both tanks to about 3,700 mg/L

• Reduce return rate to less than 100% of Q

• Take one secondary clarifier off line

• Reduce variability of organic loading

Convert EQ Basin to Aeration Tank

• Bring some return sludge to EQ• Low temperature = lower metabolism rate• Increase aeration to maintain DO about 2 mg/L• Aeration capacity??

• Could only use one 600 hp blower? Not enough!• Two blowers would “kick-out” both blowers• Calculations did not verify this• Started both < 70%• Plenty of air

• Reduced volumetric loading and F/M

Reduce MLSS

• Maintain about 3,750 mg/L

• Increase total biomass by 50%• Use EQ basin• Addresses organic/toxic/foaming shocks

• Reduce polymer dose

Reduce Return Sludge Flow Rate

• Reduced total flow to clarifiers

• Reduce polymer poundage at same dose

• Reduce solids load to clarifier

Remove One Secondary Clarifier

• Not required with lower solids loading• Not required with less total flow (Q + RSF)• Largest problem was with operations staff

• Always needed two clarifiers to settle sludge• Never operated with just one• Trial OK

+ Half-hour blanket readings+ Back to two clarifiers if blanket rises over a foot+ Raised 6” in first half-hour+ Back to 1-2 feet thickness within one hour

• Have not used two clarifiers together since then

Stabilization of Organic Loading

• Long-term

• Work with production staff • Reduce unusual discharges• Notify operations when problem occurs

• Environmental and Production groups are now a team!

Results

• Effluent quality improved• Organic loads stabilized• Secondary clarifier blankets maintained at

normal• Chemicals saved

• Polymer• Antifoam

• Significant monetary savings

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BOD Permit Limit

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Effluent Quality

Parameter Before After

BOD, mg/L 98 39

TSS, mg/L 168 56

Organic Load Stabilization

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Summary

• Initiated CPE• Made simple process changes• Reduced polymer use by average 66%• Eliminated use of antifoam• Reduced effluent BOD and TSS• Reduced influent organic load• Reduced costs significantly• Great communications and teamwork