Unit-10--Filtration

Unit10FiltrationImportantWordsandExpressions•nonsettleable['setləbl]a.非沉降性的，不沉淀的•porousadj.多孔渗水的；能渗透的；有气孔的•impuritiesn.杂质（impureity的复数）•tertiarya.第三（位，级，纪）的•interstitiala.空[孔]隙的，缝隙间•voidsn.空洞，孔洞；空隙率，结点间（void的复数）；v.使无效；排泄，清空•turbulencen.骚乱，动荡；湍流；狂暴•agitationn.激动；搅动；煽动；烦乱•polymern.[化]聚合物•feasibilityn.可行性；可能性•porevi.细想；凝视；熟读；n.气孔；小孔；vt.使注视•penetrationn.渗透；突破；侵入；洞察力•viscosityn.粘性，粘度Text•Filtrationisusedtoseparatenonsettleablesolidsfromwaterandwastewaterbypassingitthroughaporousmedium.•Themostcommonsystemisfiltrationthroughalayeredbedofgranularmedia,usuallyacoarseanthracitecoalunderlainbyfinersand.•过滤是通过多孔介质用来从水和废水中分离非沉降性固体的。•最常见的系统是通过颗粒介质的分层床过滤，通常是位于精细砂子之下的粗糙的无烟煤。•Gravitygranular-mediafiltration•Gravityfiltrationthroughbedsofgranularmediaisthemostcommonmethodofremovingcolloidalimpuritiesinwaterprocessingandtertiarytreatmentofwastewater.[1]•Themechanismsinvolvedinremovingsuspendedsolidsinagranular-mediafilterarecomplex,consistingofinterception,straining,flocculation,andsedimentation.•Initially,surfacestrainingandinterstitialremovalresultinaccumulationofdepositsintheupperportionofthefiltermedia.•通过粒状滤料床的重力过滤方法，是水处理和废水的三级处理中去除胶体杂质最常见的方法。•涉及在粒状介质过滤除去悬浮固体的机制是复杂的，包括截取，伸展，絮凝和沉淀。•起初，表面应变和间质的去除导致沉积物在过滤介质的上部积累。•Becauseofthereductioninoreare,thevelocityofwaterthroughtheremainingvoidsincreases,shearingoffpiecesofcapturedflocandcarryingimpuritiesdeeperintothefilterbed.•Theeffectivezoneofremovalpassesdeeperanddeeperintothefilter.Turbulenceandresultingincreasedparticlecontactwithintheporespromotesflocculation,resultingintrappingofthelargerflocparticles.•Eventually,cleanbeddepthisnolongeravailableandbreakthroughoccurs,carryingsolidsoutintheunderflowandcausingterminationofthefilterrun.[2]•由于矿砂的减少，通过剩余空隙的水流速增加，进而剪断捕获的絮体片层，并且携带杂质进入更深的滤床。•去除的有效区越来越深进入到过滤器。湍流和由此导致颗粒与毛孔接触的增加，促进了絮凝，从而导致较大的絮凝物颗粒的捕集。•最终，清洁的滤层厚度不足，杂质发生穿透，底部出水携带固体颗粒，过滤周期结束。•Directfiltration•Theprocessofdirectfiltrationdoesnotincludesedimentationpriortofiltration.•Theimpuritiesremovedfromthewaterarecollectedandstoredinthefilter.•Althoughrapidmixingofchemicalsisnecessary,theflocculationstageiseithereliminatedorreducedtoamixingtimelessthan30min.•直接过滤•直接过滤的过程不包括过滤之前的沉降。•从水中去除的杂质被收集和储存在滤器中。•虽然化学品的快速混合是必要的，但是絮凝阶段被消除或被降低到一个少于30分钟的混合时间。•Contactflocculationofthechemicallycoagulatedparticlesinthewatertakesplacesinthegranularmedia.•Successfuladvancesindirectfiltrationareattributedtothedevelopmentofcoarse-to-finemultimediafilterswithgreatercapacityfor“in-depth”filtration,improvedbackwashingsystemsusingmechanicalorairagitationtoaidcleaningofthemedia,andtheavailabilityofbetterpolymercoagulants.•在水中化学凝结物的接触性絮凝发生在颗粒介质中。•直接过滤的成功进步（研究进展）归功于具有深层过滤的大容量的粗-细多介质的过滤器的改进，使用机械的或空气的搅动来辅助清洗介质的反洗系统的改善，以及更好的高分子混凝剂的可用性。•Surfacewaterswithlowturbidityandcoloraremostsuitableforprocessingbydirectfiltration.•Basedonexperiencescitedintheliterature,waterswithlessthan40unitsofcolor,turbidityconsistentlybelow5units,ironandmanganeseconcentrationsoflessthan0.3and0.05mg/L,respectively,andalgalcountsbelow2,000/mLcanbesuccessfullyprocessed.•Operationalproblemsindirectfiltrationareexpectedwhencolorexceeds40unitsorturbidityisgreaterthan15unitsonacontinuousbasis.•低色度和浊度的地表水是最适合直接过滤处理•基于文献中所引用的经验，色度小于40单位，浊度始终低于5个单位，铁和锰的浓度分别小于0.3和0.05毫克/升，以及藻类计数低于2000/mL的水可被成功地处理。•当色度超过40单位或者浊度大于15个单位时，在连续的基础上，直接过滤的操作问题可以被预测到。•Potentialproblemscanbealleviatedduringashortperiodoftimebyapplicationofadditionalpolymer.•Tertiaryfiltrationofwastewaterscontaining20-30mg/Lsuspendedsolidsfollowingbiologicaltreatmentcanbereducedtolessthan5mg/Lbydirectfiltration.[3]•Forinactivationofvirusesandahighdegreeofbacterialdisinfection,filtrationofchemicallyconditionedwastewaterprecedesdisinfectionbychlorine.•短时间内，通过应用添加的聚合物，潜在的问题可以得到缓解。•对浓度为20-30mg/L悬浮物的生化处理出水进行三级过滤处理，经过直接过滤后，悬浮物能减少至5mg/L。•对于病毒的灭活和细菌的高程度消毒，废水化学条件的过滤优于氯消毒。•Thefeasibilityoffiltrationwithoutpriorflocculationandsedimentationreliesonacomprehensivereviewofwaterqualitydata.•Theincidentofhighturbiditiescausedbyrunofffromstormsandbloomsofalgaemustbeevaluated.•Often,pilottestingisvaluableindeterminingefficiencyofdirectfiltrationcomparedtoconventionaltreatment,designoffiltermedia,andselectionofchemicalconditioning.•未经絮凝和沉淀的过滤可行性取决于水质数据的全面调查。•由于来自风暴的径流和藻类大量繁殖引起的高浊度事件必须进行评估。•通常，试验性的测试在确定与传统处理相比的直接过滤效率，过滤介质的设计，化学条件的选择上是有价值的。•FilterBackwashing•Duringtheservicecycleoffilteroperation,particulatematterremovedfromtheappliedwateraccumulatesonthesurfaceofthegrainsoffinemediaandintheporespacesbetweengrains.[4]•Withcontinuedoperationofafilter,thematerialsremovedfromthewaterandstoredwithinthebedreducetheporosityofthebed.•Thishastwoeffectsonfilteroperation:itincreasestheheadlossthroughthefilter,anditincreasestheshearingstressesontheaccumulatedfloc.•过滤器反洗•在滤池的工作周期内，被去除的进水中的悬浮物，聚集在细颗粒滤料的表面以及颗粒间的空隙中。•过滤器的连续工作，材料从水中被去除并存储过滤床中，由此降低了该床的孔隙率。•这对滤床运行（工作）有两个影响：它增加了通过过滤器的水头损失，并且增加了累积在絮凝物上的剪切应力。•Eventuallythetotalhydraulicheadlossmayapproachorequaltheheadnecessarytoprovidethedesiredflowratethroughthefilter,ortheremaybealeakageorbreakthroughofflocparticlesintothefiltereffluent.•Justbeforeeitheriftheseoutcomescanoccur,thefilt