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 Tank 2.0 MG Winter Heating Summer Cooling EQ Tank 2.7 MG Nitroform & Storm Clarifiers Polymer PE Lake Formaldehyde & Methanol Wastes Stormwater Effluent Recycle Decant Sludge Pond Waste Sludge

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 = 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 ( 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 ’ 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 Q = 0.5 MGD and RSF = 0.5 MGD MLSS about 6,000 mg/L Maintain temperature about 95°F (35°C) Volumetric loading = lb BOD/10 3 ft 3

Secondary Clarifiers 2-45’ diameter, 12’ deep 101 gal/ft 2 /day, 13.6 lb MLSS/ft 2 /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

Effluent Quality ParameterBeforeAfter BOD, mg/L9839 TSS, mg/L16856

Organic Load Stabilization

Polymer and Antifoam Use

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