WATER TECHNOLOGIES FOR RURAL TEXAS OFFICE OF RURAL COMMUNITY AFFAIRS Cryptosporidium: Technologies for Disinfection, Particulate Removal & By-Product Management.

WATER TECHNOLOGIES FOR RURAL TEXASOFFICE OF RURAL COMMUNITY AFFAIRS

Cryptosporidium: Cryptosporidium: Technologies for Disinfection, Technologies for Disinfection,

Particulate Removal & Particulate Removal & By-Product ManagementBy-Product Management

Presented byPresented by

Roger K. Noack, P.E.Roger K. Noack, P.E.


Outline of PresentationOutline of Presentation

• History/BackgroundHistory/Background

• RegulationsRegulations

• Treatment Technologies AvailableTreatment Technologies Available

• Treatment Technologies LimitationsTreatment Technologies Limitations


HistoryHistory

• 1945 – Texas requires disinfection1945 – Texas requires disinfection

• 1974 – SDWA promulgated1974 – SDWA promulgated

• 1979 – THM Rule1979 – THM Rule

• 1986 – SDWA Amendments1986 – SDWA Amendments

• 1993 – Milwaukee 1993 – Milwaukee CryptosporidiosisCryptosporidiosis outbreakoutbreak

• 1996 – SDWA Amendments1996 – SDWA Amendments


BackgroundBackground

• Multiple Barrier ApproachMultiple Barrier Approach– Source WaterSource Water– TreatmentTreatment

• RemovalRemoval• DisinfectionDisinfection

– DistributionDistribution


RegulationsRegulations

• Microbiological ContaminationMicrobiological Contamination– Giardia – 3-log removal/inactivationGiardia – 3-log removal/inactivation– Viruses – 4-log removal/inactivationViruses – 4-log removal/inactivation– Cryptosporidium – 2-log removalCryptosporidium – 2-log removal– Turbidity – 0.3 NTU in 95% of samplesTurbidity – 0.3 NTU in 95% of samples


RegulationsRegulations

• Disinfection and Disinfection By-ProductsDisinfection and Disinfection By-Products– CT (disinfectant Concentration x contact Time )CT (disinfectant Concentration x contact Time )– Maximum Disinfectant Residual LevelMaximum Disinfectant Residual Level– Total TrihalomethanesTotal Trihalomethanes– Haloacetic AcidsHaloacetic Acids– ChloriteChlorite– BromateBromate– Total Organic CarbonTotal Organic Carbon


Simultaneous ComplianceSimultaneous Compliance

• Producing drinking water that meets all Producing drinking water that meets all regulatory requirementsregulatory requirements

• ALL RULES ARE EQUALALL RULES ARE EQUAL

• One rule cannot be undermined in favor One rule cannot be undermined in favor of anotherof another

• Simultaneous compliance will be Simultaneous compliance will be challengechallenge


DisinfectionDisinfection

• ChlorineChlorine– LiquidLiquid– TabletTablet– GasGas– On-site generationOn-site generation

• Chloramine (chlorine + ammonia)Chloramine (chlorine + ammonia)– LiquidLiquid– GasGas


DisinfectionDisinfection

• Ozone Ozone

• Chlorine dioxideChlorine dioxide

• Ultraviolet lightUltraviolet light


Limitations of DisinfectantsLimitations of Disinfectants

• ChlorineChlorine– Contact timeContact time– DBPsDBPs– Demand versus residualDemand versus residual– SafetySafety

• ChloraminesChloramines– Weak disinfectantWeak disinfectant– Potential regrowthPotential regrowth



• OzoneOzone– Strong disinfectantStrong disinfectant– DBPsDBPs– No residualNo residual– SafetySafety– Biodegradable organics affects water Biodegradable organics affects water

qualityquality



• Chlorine DioxideChlorine Dioxide– Strong disinfectantStrong disinfectant– DBPsDBPs– No residualNo residual– SafetySafety



• Ultraviolet lightUltraviolet light– Not a disinfectantNot a disinfectant– No residualNo residual– Special instrumentationSpecial instrumentation– Special maintenanceSpecial maintenance


Removal TechnologiesRemoval Technologies

• Conventional treatment Conventional treatment – FlocculationFlocculation– SedimentationSedimentation– FiltrationFiltration

• MonomediaMonomedia• Dual mediaDual media• Mixed mediaMixed media



• Direct filtration Direct filtration

• Slow sand filtrationSlow sand filtration

• Diatomaceous earth filtrationDiatomaceous earth filtration

• Cartridge/Bag/Backwashable filtersCartridge/Bag/Backwashable filters



• MicrofiltrationMicrofiltration

• UltrafiltrationUltrafiltration

• Nanofiltration Nanofiltration

• Reverse osmosis Reverse osmosis



Removal Tech. LimitationsRemoval Tech. Limitations

• Conventional treatment Conventional treatment – Handle wide range of water qualityHandle wide range of water quality– ExpensiveExpensive

• Direct filtration Direct filtration – Low turbidityLow turbidity– Algae may be a problemAlgae may be a problem



• Slow sand Slow sand – Low turbidityLow turbidity– Algae may be a problemAlgae may be a problem

• Direct filtration Direct filtration – Low turbidityLow turbidity– Low removal credits for Giardia/virusesLow removal credits for Giardia/viruses– Algae may be a problemAlgae may be a problem– Not allowed in Texas on surface water Not allowed in Texas on surface water



• Diatomaceous earth filtrationDiatomaceous earth filtration– Good water quality requiredGood water quality required– Low bacteria and viruses removalLow bacteria and viruses removal

• Cartridge/Bag/Backwashable Cartridge/Bag/Backwashable – Exceptional water quality requiredExceptional water quality required– Pretreatment requiredPretreatment required– Variable particulate removal Variable particulate removal



• MembranesMembranes– High pressure requires exceptional water High pressure requires exceptional water

qualityquality– Stabilization of permeate requiredStabilization of permeate required– Low pressure replaces conventional Low pressure replaces conventional

treatmenttreatment– Cost is decreasing as usage increasesCost is decreasing as usage increases


DBP ControlDBP Control

• Move the point of disinfectant Move the point of disinfectant applicationapplication

• Increase DBP precursor removalIncrease DBP precursor removal

• Change the disinfectant usedChange the disinfectant used– PrimaryPrimary– SecondarySecondary


DBP ControlDBP Control

• TemperatureTemperature

• pH pH

• Aggressive flushing programAggressive flushing program

• Corrosion leads to elevated disinfectant Corrosion leads to elevated disinfectant residualsresiduals

• Supplemental (boost) disinfectant Supplemental (boost) disinfectant addition in the distribution systemaddition in the distribution system


Questions & AnswersQuestions & Answers

WATER TECHNOLOGIES FOR RURAL TEXAS OFFICE OF RURAL COMMUNITY AFFAIRS Cryptosporidium: Technologies for Disinfection, Particulate Removal & By-Product Management.

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