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Sourcewater coag/settling filtration storage elevated tank consumer Optimizing the chemistry in a water treatment plant

Sourcewater coag/sett ing filtration storage elevated tank consumer SourcewaterTemperature 32 85oFpH 6.5 to 8.5Alkalinity 60-200TOC (chlorine demand and DBP formation) 1.5 to 5 mg/lbacteria

Sourcewater coag/settling filtration storage elevated tank consumer Pre-oxidationChlorine, chlorine dioxide, potassium permanganatepH likely is decreased

Sourcewater coag/settling filtration storage elevated tank consumer Coagulation/flocculation/sedimentationAddition of alum (wants pH low) or ferric coagulant, polymers, pH decreasesAlkalinity decreasesLime addition may be necessary

Sourcewater coag/settling filtration storage elevated tank consumer DisinfectionAddition of chlorine (low pH favored for HOCl formation) pH decreasesAlkalinity decreases (slightly)DBP reaction startsReaction time with microorganisms is critically importantIN SUNLIGHT, UV REACTS WITH FREE CHLORINE

Sourcewater coag/settling filtration storage elevated tank consumer DisinfectionAddition of chlorine (low pH favored)pH decreasesAlkalinity decreases (slightly)DBP reaction startsReaction time with microorganisms is critically importantLime addition may be necessaryIF DONE IN SUNLIGHT, UV REACTS WITH FREE CHLORINEDBP ControlReduce pH for slower reaction Reaction time is critical Chlorine feed in plantFlushing in DSTemperature is critical Reaction can be modified by changing reactants (chloramine)

Sourcewater coag/setting filtration storage elevated tank consumer Corrosion ControlIncrease pH (pH 8.5 typical) with lime or causticUse corrosion inhibitors (pH 7.5 typical)

Sourcewater coag/settling filtration storage elevated tank consumer Optimized ProcessPre-oxidant that doesnt form DBPs Coagulant at lower pH Chlorine at low pHlime to raise pH and ammonia to change DBP reaction Chlorine trim dose for monochloraminesFlushing to minimize water age