一般污泥和含油污泥的处理方法外文翻译

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1、ThewaysofregularsludgeandoilysludgetreatingGenerallyspeaking，thereisaprocedurefortreatingsludgeaftersecondarytreatmentofwastewaterifwewanttopreventourlivingenvironmentfromsecondpolluting.Wastewatertreatmentobjectivesareaccomplishedbyconcentratingimpuritiesintosolidformandth

2、enseparatingthesesolidsfromthebulkliquid.Thisconcentrationofsolids，referredtoassludge，containsmanyobjectionablematerialsandmustbedisposedofproperly.Sludgedisposalfacilitiesusuallyrepresent40to60percentofdisposedoftheconstructioncostwastewater-treatmentplants，accountforasmuc

3、has50percentoftheoperatingcost，andarethecauseofadisproportionateshareofoperatingdifficulties.Firstofall，theinitialsludgeisseparatedfromthecleanwaterlyinguponitinthesecondaryclarifierbypumpingittoatank.Becausetheinitialsludgehaveahighwatercontentthatusuallycanupto99.5percent

4、involume，sludgethickeningisanecessaryprocedure，andthereareseveraltechniquesareavailablefoevolumereduction.Mechanicalmethodssuchasvacuumfiltrationandcentrifugationmaybeusedwherethesludgeissubsequentlytobehandledinasemisolidstate.Theremethodsarecommonlyusedprecedingsludgeinci

5、neration.Wherefurtherbiologicaltreatmentisintend，volumereductionbygravitythickeningorflotationiscommonpractice.Inbothcases，thesludgeremainsinaliquidstate.Gravitythickenersareverysimilarindesignandoperationtothesecondaryclarifiersusedinwastewatertreatingsystems.Thethickening

6、functionisthemajordesignparameter，andtanksaregenerallydeeperthansecondaryclarifierstoprovidegreaterthickeningcapacity.Awell-designed，well-operatedgravitythickenershouldbeableto，atleastdoublethesolidscontentofthesludge.Inanotherword，thewatercontentratioofsludgecanbereducedfr

7、om99.5percentinvolumeto98percentorevermuchmorereduction.Itshouldbenotedthatthedesignofgravitythickenersshouldbebasedontheresultsofpilotplantanalysiswhereverpossible，sincesuccessfulloadingratesarehighlydependentonthenatureofthesludge.Indissolvedairflotation，asmallquantityofw

8、ater，usuallysecondaryeffluentissubjectedtoaerationunderapressureofabout400kPa.This