控制氧化沟工艺中的污泥沉降外文翻译三

本科生毕业设计本科生毕业设计外文文献翻译外文文献翻译ControllingsludgesettleabilityintheoxidationditchprocessK.J.HartleyABSTRACTThispaperdescribesaninvestigationaimedatdevelopinganoperatingtechniqueforcontrollingsludgesettleabilityintheoxidationditchformofthenitrificationdenitrificationactivatedsludgeprocess.Itwashypothesizedthatspecificsludgevolumeindex(SSVI)islowestatanoptimumprocessanoxicfractionandincreasesathigherandlowerfractions.Usingeffluentammonia:nitrateratioasasurrogateforanoxicfraction,itwasfoundthatasimpleempiricalmodelbasedonathreesolidsretentiontimemovingaveragenitrogenratiowasabletoreplicatethelong-termSSVIvariationsintwoindependentoxidationditchesatafull-scaleplant.Operatingdatafromasecondoxidationditchplantduringperiodswhenaprefermenterwason-oroff-lineshowedthatSSVIalsovarieswithRBCOD,greaterRBCODgivinglowerSSVI.Itwasconcludedthatbestsettleabilityoccursataboutthesameanoxicfractionaslowesteffluenttotalnitrogenconcentration,withanammonia:nitrateratioofabout1.Anoperatingruleofthumbistousedissolvedoxygencontroltomaintaineffluentammoniaandnitratenitrogenconcentrationsaboutequal.Athirdoxidationditchplantdeliberatelyoperatedinthismannerachieved15-monthmedianoperatingvaluesforSSVIof60mL/gandforeffluentammonia,nitrateandtotalN,respectively,of0.2,0.3and2.0mgN/L.KeywordsSettleability；Sludgevolumeindex；SVI；Control；Nitrogen；Oxidationditch1IntroductionTheoxidationditchprocesshasthecapabilitytoreliablymeetlowtotalnitrogenstandardsbecauseofitsspecialoperatingcharacteristics.Nitrogenremovalcanbecontinuouslyoptimizedinoperationbyvaryingtheanoxicandaerobicmassfractionstomeetshort-andlong-termchangesinwastewatercharacteristics(Hartley,1997;MinesandWoods,1994).Ithasalsobeenobservedthatsludgesettleabilityinoxidationditchesvarieswiththeoperatingmassfractions(VivianandHartley,1989).Sludgesettleabilityisoneofthemostimportantdesignandoperatingcharacteristicsoftheactivatedsludgeprocess.Itaffectsboththesizingoftankageandtheprocesscapacityactuallyachieved.Yet,nearly100yearsaftertheactivatedsludgeprocess