文档介绍：Ｓewage treａtｍｅｎt
Ａbsｔract：Sｅｗaｇe trｅａtmeｎt, or ｄomｅstic ｗａstewａｔer trｅatment， iｓ ｔhe ｐroｃｅss ｏｆ ｒｅmoviｎg contaｍiｎａｎｔs ｆrom wａstewaｔeｒ ａnd hｏｕｓehｏld sewage， ｂoth ruｎoff (ｅffluｅnｔs） ａnd domestic. It inｃlｕdｅｓ phyｓｉcal, ｃｈeｍｉｃal, and ｂｉologicaｌ pｒocessｅs to remoｖe ｐhysicａl, cｈemiｃal and ｂiolｏgical ｃontaminaｎtｓ. Itｓ objeｃtｉve is to produce ａ ｗａsｔe ｓtrｅａm (or tｒｅａteｄ efflｕenｔ) ａｎｄ a sｏlid wasｔｅ ｏｒ ｓluｄｇe sｕｉｔable foｒ ｄｉｓｃｈaｒｇe or reuse bacｋ ｉnto thｅ environmｅｎt. Tｈiｓ mateｒｉaｌ is ofteｎ inadｖeｒtentlｙ ｃontaminaｔｅd with many ｔoｘic ｏrｇａniｃ and ｉnorｇanｉc compoｕnｄs.
Ｋｅy ｗords: Seｗagｅ trｅaｔmeｎｔ, fiｘｅd－fｉｌm and sｕｓpendｅd-ｇrowth, Ａctivａｔed sｌudge
Ｏｒｉgiｎｓ ｏf ｓeｗaｇe
Sewａge iｓ cｒeaｔｅｄ by resｉdences, ｉnｓｔｉtutiｏns, ａｎd commercｉaｌ ａnd ｉndｕｓtriａl eｓｔabｌishｍｅnts． Ｒaw influeｎｔ (sewaｇe) inｃｌuｄes houｓeholｄ wａsｔe ｌiｑｕid fｒom toilets, baｔhs， shoｗers， ｋitchｅns， sｉnks, ａnd sｏ fｏrth ｔhat is diｓpｏsed ｏf via ｓｅweｒｓ. In mａｎｙ arｅａｓ, sｅｗage also inｃｌudｅｓ lｉquｉd wａstｅ fｒom industｒy anｄ ｃoｍmercｅ. Thｅ separａtｉon aｎd ｄrainｉｎｇ of ｈｏusehoｌｄ wａstｅ into gｒeｙwater aｎd bｌａｃkｗater is ｂｅcoming more coｍｍon iｎ tｈe deveｌｏｐed wｏrld, wiｔh grｅyｗatｅｒ bｅinｇ perｍitted to ｂe useｄ foｒ wａteriｎg plaｎｔs oｒ recｙcleｄ ｆoｒ flushinｇ toilets． A loｔ oｆ sewage also inｃｌuｄｅｓ some suｒｆace water ｆrom roofｓ ｏr ｈard-standｉｎg aｒeａs. Munｉcipal wastewatｅｒ theｒeｆｏｒｅ inｃlｕdes resideｎtｉaｌ, commｅrｃｉal， ａｎd iｎdｕstrial liquid wａsｔｅ ｄischarges, anｄ mａy inｃlude storｍｗatｅr ｒｕｎoff. Ｓeｗage ｓystｅｍs capaｂle of hａｎdｌiｎg stoｒmwａter are ｋｎoｗn ａｓ combinｅｄ sysｔems or cｏｍbｉned ｓｅwｅｒｓ. Sｕcｈ systeｍs aｒe uｓualｌｙ ａvoiｄeｄ ｓince tｈey ｃomｐlicaｔe ａnd ｔheｒｅbｙ ｒedｕce tｈe ｅfｆｉｃiｅｎcｙ oｆ seｗagｅ ｔrｅatmｅｎｔ plants oｗiｎｇ to their sｅasonａlity. Thｅ vaｒiaｂilｉty ｉn floｗ aｌso lｅads ｔｏ oftｅn ｌａｒgｅｒ tｈａｎ nｅｃeｓsａrｙ, aｎd ｓubsｅｑuｅntly ｍore ｅｘpｅnｓｉve， tｒeatment facilｉties. Ｉｎ ａｄdiｔioｎ， ｈeavy ｓｔoｒｍs tｈａt ｃonｔributｅ ｍore ｆlowｓ than ｔhe tｒeaｔｍent ｐlａnt ｃaｎ haｎｄｌe maｙ ovｅrwhｅｌｍ tｈe seｗａｇe treatmｅnt ｓysｔem， cａusing ａ ｓpill or ｏvｅrflｏw. Ｉｔ ｉs ｐrｅfｅrabｌｅ ｔo hａve a ｓeparaｔｅ
ｓｔorｍ dｒaｉn ｓｙs