环境工程专业英语 unit 14

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1、3BiologicalWastewaterTreatmentApplicationofmicrobialdegradationandremovalofundesirableconstituentsinindustrialandmunicipalwastesisnotanewconcept.Itiscommonlyusedprocessforgeneralwastewatertreatmentactivitiesandhasbeenformanyyears.Astheawarenessofchemicalcontaminationoftheenvironment,muchresear

2、chonbiologicaldegradationoftoxicchemicalshasoccurred.Amongtherangeoftreatmenttechnologies,biologicaldegradationranksamongthemosteffective.Itsmanagementandapplicationisenhancedbythepotentialtoapplybiologicaltreatmentinsequencewithotherchemicalandthermalprocesses.ActivatedsludgeTheactivatedsludg

3、eprocessisstypicaltypeofsuspendedgrowthbiologicaltreatmentsystemandprobablythemostwidelyusedbiologicalprocessforthetreatmentoforganicandindustrialwastewaters.However,itcanonlytreataqueousorganicwastestreamshavinglessthan1%suspendedsolidcontent,andcannottolerateshockloadingofconcentratedorganic

4、s.Therefore,thewastestreamenteringthisprocesswillusuallyhavepassedthroughapretreatmentprocesswhichincludesaclarifier(primaryclarifier)andanequalizationbasin.Theprimaryclarifierisusedforremovalofgrit,oilyandfattymaterialandgrosssolidmaterial,whiletheequalizationbasinisusedtodampenwastewaterflow

5、variationsandtoprovidemoreuniformorganicloadingtotheactivatedsludgesystem.Activatedsludgeprocessareusedtotreatmunicipalandindustrialwastessincetheyareversatile,flexible,andcanbeusedtoproduceaneffluentofdesiredqualitybyvaryingprocessparameters.Theprocesswasso-namedbecauseitproducesanactivemasso

6、fmicroorganismscapableofaerobicallystabilizingawaste.Manyversionsofthebasicprocessexistbutallarefundamentallysimilar.9Thetermactivatedsludgeisappliedtoboththeprocessandtothebiologicalsolidsinthetreatmentunit.Themixedliquorsuspendedsolidsoractivatedsludgecontainsavarietyofheterotrophicmicroorga

7、nismssuchasbacteria,protozoa,fungi,andlargermicroorganisms.Thepredominanceofaparticularmicrobialspeciesdependsuponthewastethatistreatedandthewayinwhichtheprocessisoperated.Theactivatedsludgeprocessiscurrentlythemostwidelyusedbiologicalt