硝化、反硝化系統詳解
本文(wen)對硝化、反硝化系統進行詳解:
由于環境污(wu)染(ran)的(de)(de)(de)(de)(de)(de)(de)(de)不(bu)斷加(jia)重,國家從加(jia)強環保的(de)(de)(de)(de)(de)(de)(de)(de)角度出(chu)發,出(chu)水(shui)(shui)(shui)總(zong)(zong)氮(dan)(dan)(dan)(dan)(dan)(dan)(dan)成為(wei)(wei)一(yi)個重要(yao)(yao)(yao)的(de)(de)(de)(de)(de)(de)(de)(de)指標(biao):非敏感地區40mg/L,敏感地區20mg/L;另外《城市污(wu)水(shui)(shui)(shui)再生(sheng)利(li)用(yong)工業用(yong)水(shui)(shui)(shui)水(shui)(shui)(shui)質(zhi)》標(biao)準(zhun)(GB/T 19923-2005)中的(de)(de)(de)(de)(de)(de)(de)(de)循環冷卻水(shui)(shui)(shui)水(shui)(shui)(shui)質(zhi)標(biao)準(zhun)對(dui)(dui)氨(an)(an)氮(dan)(dan)(dan)(dan)(dan)(dan)(dan)提(ti)出(chu)了更高(gao)(gao)的(de)(de)(de)(de)(de)(de)(de)(de)排放要(yao)(yao)(yao)求。可(ke)是(shi)到(dao)(dao)目(mu)前(qian)為(wei)(wei)止應用(yong)的(de)(de)(de)(de)(de)(de)(de)(de)許(xu)多脫(tuo)氮(dan)(dan)(dan)(dan)(dan)(dan)(dan)工藝(yi)一(yi)方(fang)面從降(jiang)低運行成本出(chu)發,另一(yi)方(fang)面也是(shi)因(yin)為(wei)(wei)技術原因(yin),只(zhi)考慮了氨(an)(an)氮(dan)(dan)(dan)(dan)(dan)(dan)(dan)的(de)(de)(de)(de)(de)(de)(de)(de)去除,而忽略了總(zong)(zong)氮(dan)(dan)(dan)(dan)(dan)(dan)(dan)的(de)(de)(de)(de)(de)(de)(de)(de)去除,有時出(chu)水(shui)(shui)(shui)氨(an)(an)氮(dan)(dan)(dan)(dan)(dan)(dan)(dan)雖然(ran)達(da)到(dao)(dao)標(biao)準(zhun)≤15mg/L,但是(shi)總(zong)(zong)氮(dan)(dan)(dan)(dan)(dan)(dan)(dan)卻達(da)到(dao)(dao)200mg/L。在(zai)新標(biao)準(zhun)提(ti)出(chu)前(qian),報道的(de)(de)(de)(de)(de)(de)(de)(de)一(yi)些數據普遍反映總(zong)(zong)氮(dan)(dan)(dan)(dan)(dan)(dan)(dan)去除率在(zai)70%左右,因(yin)此(ci)對(dui)(dui)于這種高(gao)(gao)總(zong)(zong)氮(dan)(dan)(dan)(dan)(dan)(dan)(dan)的(de)(de)(de)(de)(de)(de)(de)(de)污(wu)水(shui)(shui)(shui)要(yao)(yao)(yao)達(da)到(dao)(dao)排放要(yao)(yao)(yao)求,需(xu)要(yao)(yao)(yao)采(cai)取不(bu)同的(de)(de)(de)(de)(de)(de)(de)(de)措(cuo)(cuo)施(shi)來解決(jue)。最經(jing)濟實用(yong)的(de)(de)(de)(de)(de)(de)(de)(de)方(fang)法是(shi)改善和(he)優化目(mu)前(qian)的(de)(de)(de)(de)(de)(de)(de)(de)生(sheng)化脫(tuo)氮(dan)(dan)(dan)(dan)(dan)(dan)(dan)工藝(yi),從設(she)計(ji)一(yi)開始就(jiu)以脫(tuo)總(zong)(zong)氮(dan)(dan)(dan)(dan)(dan)(dan)(dan)為(wei)(wei)目(mu)的(de)(de)(de)(de)(de)(de)(de)(de),而不(bu)是(shi)以降(jiang)低氨(an)(an)氮(dan)(dan)(dan)(dan)(dan)(dan)(dan)為(wei)(wei)目(mu)的(de)(de)(de)(de)(de)(de)(de)(de)來設(she)計(ji)。由于生(sheng)化過程(cheng)(cheng)的(de)(de)(de)(de)(de)(de)(de)(de)本身的(de)(de)(de)(de)(de)(de)(de)(de)局限性,生(sheng)化過程(cheng)(cheng)也不(bu)能(neng)完全保證總(zong)(zong)氮(dan)(dan)(dan)(dan)(dan)(dan)(dan)的(de)(de)(de)(de)(de)(de)(de)(de)排放,有必要(yao)(yao)(yao)結合其它一(yi)些處理(li)措(cuo)(cuo)施(shi),例如化學沉淀,吸附,膜過濾技術等。所(suo)以在(zai)本方(fang)案(an)中采(cai)用(yong)了優化的(de)(de)(de)(de)(de)(de)(de)(de)脫(tuo)氮(dan)(dan)(dan)(dan)(dan)(dan)(dan)工藝(yi):污(wu)泥法工藝(yi)和(he)膜結合的(de)(de)(de)(de)(de)(de)(de)(de)聯合脫(tuo)氮(dan)(dan)(dan)(dan)(dan)(dan)(dan)工藝(yi)。
在好氧(yang)過程中(zhong),有機(ji)物的(de)轉化途徑為:
進(jin)行上述過(guo)程(碳氧(yang)化)的微生物(wu)以異(yi)氧(yang)型(xing)兼氧(yang)細(xi)菌(jun)(jun)占主體。其特點是:以有(you)機物(wu)為食,通過(guo)對有(you)機物(wu)的分(fen)解(jie)提(ti)供新陳(chen)代謝所(suo)需的碳源(yuan)和能源(yuan);既可進(jin)行有(you)氧(yang)呼吸,又可進(jin)行無氧(yang)呼吸(發酵);以菌(jun)(jun)膠團細(xi)菌(jun)(jun)為主,也有(you)一些絲(si)狀菌(jun)(jun)。
氨(an)氮的轉化途(tu)徑為(wei):
進行(xing)硝化作用(yong)的微(wei)生物以自養型好氧菌為(wei)主體,其特點:
以無(wu)機碳作為細(xi)胞生長的(de)碳源(yuan),一(yi)般(ban)為專性(xing)好氧菌(jun)(jun),在缺氧時受到抑(yi)制;棲居在活性(xing)污泥菌(jun)(jun)膠團表(biao)面(mian),以桿菌(jun)(jun)、球(qiu)菌(jun)(jun)為主。
硝(xiao)化段的混(hun)合液回流至A段,在A段發(fa)生反硝(xiao)化作用,反應過程為:
經過(guo)(guo)硝化-反硝化過(guo)(guo)程,沼液中(zhong)(zhong)的有機物和(he)氨氮大部(bu)(bu)分被轉(zhuan)(zhuan)化為無機物(CO2、H2O、N2)從水中(zhong)(zhong)去除,一小部(bu)(bu)分則轉(zhuan)(zhuan)化為細胞物質(zhi),通過(guo)(guo)定期排(pai)泥(ni)被排(pai)出系統。
生(sheng)(sheng)(sheng)(sheng)化(hua)系(xi)(xi)(xi)統(tong)(tong)(tong)主要(yao)由(you)反(fan)硝(xiao)化(hua)池(chi)/硝(xiao)化(hua)池(chi)、消泡系(xi)(xi)(xi)統(tong)(tong)(tong)和冷卻系(xi)(xi)(xi)統(tong)(tong)(tong)組(zu)成,其(qi)它系(xi)(xi)(xi)統(tong)(tong)(tong)的(de)輔助設備也列入生(sheng)(sheng)(sheng)(sheng)化(hua)系(xi)(xi)(xi)統(tong)(tong)(tong)。其(qi)中反(fan)硝(xiao)化(hua)池(chi)一(yi)(yi)組(zu),硝(xiao)化(hua)池(chi)一(yi)(yi)組(zu),厭氧反(fan)應器出(chu)(chu)水(shui)進入生(sheng)(sheng)(sheng)(sheng)化(hua)系(xi)(xi)(xi)統(tong)(tong)(tong)生(sheng)(sheng)(sheng)(sheng)產線,生(sheng)(sheng)(sheng)(sheng)化(hua)系(xi)(xi)(xi)統(tong)(tong)(tong)為AO型生(sheng)(sheng)(sheng)(sheng)化(hua)反(fan)應器,反(fan)應器內的(de)好(hao)氧微生(sheng)(sheng)(sheng)(sheng)物(wu)對水(shui)中的(de)有機物(wu)進行(xing)分(fen)解利用(yong),合(he)成細(xi)胞(bao)(bao)組(zu)織,放出(chu)(chu)水(shui)和二氧化(hua)碳。水(shui)中的(de)氨氮(dan)一(yi)(yi)部(bu)(bu)分(fen)用(yong)于(yu)除碳反(fan)應中細(xi)胞(bao)(bao)合(he)成,一(yi)(yi)部(bu)(bu)分(fen)被硝(xiao)化(hua)細(xi)菌(jun)利用(yong),生(sheng)(sheng)(sheng)(sheng)成硝(xiao)酸(suan)鹽、亞硝(xiao)酸(suan)鹽。硝(xiao)酸(suan)鹽、亞硝(xiao)酸(suan)鹽隨硝(xiao)化(hua)液(ye)回流至反(fan)硝(xiao)化(hua)池(chi),在(zai)缺氧環境下(xia)發生(sheng)(sheng)(sheng)(sheng)反(fan)硝(xiao)化(hua),硝(xiao)酸(suan)鹽和亞硝(xiao)酸(suan)鹽被還(huan)原,生(sheng)(sheng)(sheng)(sheng)成氮(dan)氣逸出(chu)(chu),實(shi)現脫氮(dan)。
MBR系統由硝(xiao)化池(chi)取水進行泥(ni)水分離,濃縮后的泥(ni)水混合液作為內(nei)回流回反硝(xiao)化段(duan)。
生化生化系統每日(ri)排出污(wu)(wu)泥(ni),含水(shui)率為98.0-99.0%,由于污(wu)(wu)泥(ni)濃度(du)較低,本系統設(she)置了污(wu)(wu)泥(ni)存儲(chu)池,然(ran)后通(tong)過污(wu)(wu)泥(ni)泵(beng)送至板(ban)框壓濾機,使得(de)最終泥(ni)餅(bing)含水(shui)率低于80%。

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