Converting Sioux City WWTP to Modified Ludzak-Ettinger (MLE)

Converting Sioux City WWTP toModified Ludzak-Ettinger (MLE)MPUA/MWEA Specialty ConferenceAugust 10, 2011

Existing Wastewater Treatment Facility• Population ~80,000• 320 Miles of Sewers• 12 WW Pump Stations• Primary Treatment 1961• Headworks & DigesterImprovements 2006-8• Secondaries added 1978• (4) 4-pass Step FeedAeration Basins• (4) Final Clarifiers

Recent Facility Planning History• Current NPDES Permit (issued Oct. 2006)– Seasonal Ammonia-based effluent limits– Monthly Average 26 to 92 mg/L– Daily Maximum 53 to 97 mg/L– Compliance schedule thru August 2011• Facility Plan completed in 2008 (Veenstra& Kimm, Inc.)• CDM completed design and constructionpermitting process for recommendedtreatment improvements

Facility Plan Approach to NitrogenConventional Activated Sludge(nitrification)vs.Modified Ludzack-Ettinger (MLE)(nitrification/de-nitrification)• Current Industrial loading vs.reduced loading• Wet weather treatment alternatives• More stringent ammonia limits• IDNR Design Criteria

Facility Plan Approach to Nitrogen• MLE Process Selected:– No reduction in industrial loads– Secondary treatment of peak flow• (2) Add’l AerationBasins – (6) total• (1) Add’l FinalClarifier – (5) total• Benefits/Advantages:– Reduced power, alkalinity cost– Comparable capital cost– Reserve capacity via criteriaupdate*– Expansion to total nitrogen/BNR– No de-nitrification in FinalClarifiers.

Biological Nitrification Basics• TKN NO 3-(Nitrate)• O 2 demand 4.5 mg O 2 /mgAmmonia• Alkalinity demand 7.1 mg CaCO3/mg AmmoniaO 2O 2OrganicNitrogenAnaerobic orAerobicBacteriaAmmoniaNitrogenNitrosomonosBacteriaNitriteNitrobacterBacteriaNitrateAlkalinityAlkalinity

De-Nitrification Basics•-Nitrate NO 3 Nitrogen Gas• Occurs in the absence of molecular oxygen• NO 3 used instead of O 2 as an electron acceptor• Anoxic contact time (2 to 4 hours) w/ Mixing• Carbon source is required for denitrification• O 2 recovery 2.8 mg O 2 /mg NO - 3 reduced•-Alkalinity recovery 3.0 mg CaCO 3 /mg NO 3

Modified Ludzack-Ettinger (1973)MLEInternal RecycleNitrate Rich MLSS

Influent Loading CriteriaDesign Year2021ParameterFlowMGDBODLbs/day(mg/L)TSSLbs/day(mg/L)NH3Lbs/day(mg/L)TKNLbs/day(mg/L)Average DailyFlow(ADF)15.9873,242(550)53,267(400)7,324(55.0)9,721(73.0)Avg. WetWeather (AWW)17.687,208(595)69,676(475)8,540(58.2)12,338(84.1)Max. WetWeather (MWW)28.7390,208(376)74,700(312)8,540(35.7)12,338(51.5)Peak Hour(PHWW)56.54 - - - -*Current Permit Loadings: Ref’nce 2008 Facility Plan by Veenstra & KimmTerminology: AWW = Max Month; MWW = Max Day, PHWW =Peak Hour

BioWin Process Flow ChartPlant InfluentPCsSelector 1Selector 2 Selector 3 AnoxicEffluentFCsPass 4Pass 3Pass 2GBT'sIndustrial InfluentBFP'sAnaerobic DigestersCakeMLE Secondarytreatment process

BioWin Simulation ResultsFlow(SRT)BODmg/LTSSmg/LNH3mg/LTKNmg/LTotal-Nmg/L16.0 MGD(7.8 days)17.6 MGD(6.8 days)28.73 MGD(6.8 days)Influent 550 400 55 73 73Effluent 2.5 5.0 0.05 2.7 11Influent 595 475 58.2 84.1 84.1Effluent 3.0 5.0 0.05 2.9 13.5Influent 376 312 35.7 51.5 51.5Effluent 4.5 10 0.05 2.2 11.3

Secondary Treatment ImprovementsModifications toExisting 4 AerationBasinsBlower, Pumps,and PipingUpgradesLimeSystem(Alkalinity)1 2 345Two NewMLEAerationBasins656New FinalClarifierFuture FinalClarifier

MLE ProcessAeration BasinsEffluentPass 4InternalRecyclePass 3Pass 2InfluentRASMixersPass 1Anoxic

Aeration Basin ConversionModifications toExisting 4 AerationBasins1 2 345656Grit Removal

Aeration Basin ConversionModifications toExisting 4 AerationBasins1 2 345656Air pipe demo, modifications

Aeration Basin ConversionModifications toExisting 4 AerationBasins1 2 345656Fine bubble diffusers,Internal Recycle pump

Aeration Basin ConversionModifications toExisting 4 AerationBasins1 2 345656Anoxic Selector Zones, mixers

New Aeration BasinsConstruct AerationBasins 5 and 61 2 345656

Process Air ImprovementsBlower buildingImprovements1 2 345656(4) New Multi-stage, 1000 HP ea.;(3) Re-built Multi-stage, 400 HP ea.

New Final Clarifier1 2 3412563 456Splitter StructuresWeir brushesConstruct New FinalClarifier #5

Lime Silo1 2 3412563 4Slurry Feed, 1600 CF storageEst. < 30 days/year usage56

Effluent: pHmonitoring in effluentfor local manual orauto lime feed controlDOProcess ControlAeration Basin:Internal Blower Staging Recycle: based onVFD Dissolved w/ Local Oxygen and (DO) atRemote end of Passes Auto Control, 2 and 4 andPass Blower 1 DO control 0.3 package mg/lPass 4DODOInternal Recycle:VFD w/ Local andRemote Auto Control,Pass 1 DO 0.3 mg/lInfluent: Flow meterw/ Local and Remotemanual valve controlRAS Feed: Flow meter w/Local Manual and Remotemanual and auto valve controlPass 3Pass 2Pass 1Anoxic

Multi-Blower SequencingBlower Control ViaMaster DissolvedOxygen ControlSystem (MDOCS)

Construction Results• $27 million construction cost•

Recent PerformanceFlow(SRT)BODmg/LTSSmg/LNH3mg/LTKNmg/LTotal-Nmg/L16.0 MGD(7.8 days)17.6 MGD(6.8 days)28.73 MGD(6.8 days)June 201131.0 MGDInfluent 550 400 55 73 73Effluent 2.5 5.0 0.05 2.7 11Influent 595 475 58.2 84.1 84.1Effluent 3.0 5.0 0.05 2.9 13.5Influent 376 312 35.7 51.5 51.5Effluent 4.5 10 0.05 2.2 11.3Influent 178 247 - 23.4 23.4Effluent 6.1 12.7

Next StepsFACILITY PLANNING• Quantify Actual WWTP Capacity– Re-calibrate modeling with actual operational data– Participate in IDNR Criteria revision• Nutrient Removal??– Evaluate improvement alternatives forvarious “Tiers”• Capital Improvement Plan– Asset Renewal– Expansion/Re-rating

Engineering Consulting ServicesThe City of Sioux City, IowaQUESTIONSAugust 2, 2011