一、生物活性炭的定義與特性
生物活性炭(簡稱(cheng)BAC)是指在活(huo)性炭(tan)的孔內使微生物繁殖,使這些微生物產生活(huo)性的水(shui)質凈化法(生物活(huo)性炭(tan)法)中所用的炭(tan)材(cai)料,是一種新型(xing)的水(shui)凈化用炭(tan)材(cai)料。
活(huo)(huo)性(xing)炭(tan)(tan)(tan)(tan)是一(yi)種多(duo)孔性(xing)物(wu)(wu)質,其中(zhong)由微(wei)(wei)孔(孔徑小(xiao)于2mm)構成的(de)(de)(de)內表面積約占總面積的(de)(de)(de)95%以上(shang),過度(du)孔和大(da)孔僅5%左右。根據活(huo)(huo)性(xing)炭(tan)(tan)(tan)(tan)的(de)(de)(de)形狀和制作方法不同(tong),可以對(dui)(dui)活(huo)(huo)性(xing)炭(tan)(tan)(tan)(tan)進(jin)行分類(lei),一(yi)般包括粉末(mo)活(huo)(huo)性(xing)炭(tan)(tan)(tan)(tan)、顆粒活(huo)(huo)性(xing)炭(tan)(tan)(tan)(tan)、破碎狀活(huo)(huo)性(xing)炭(tan)(tan)(tan)(tan)等類(lei)別。活(huo)(huo)性(xing)炭(tan)(tan)(tan)(tan)的(de)(de)(de)化學性(xing)質穩定,能耐酸、堿(jian),耐高(gao)溫高(gao)壓,因(yin)此適應性(xing)很廣。活(huo)(huo)性(xing)炭(tan)(tan)(tan)(tan)吸(xi)附(fu)技術是飲用水(shui)深(shen)度(du)處理中(zhong)成熟有效(xiao)的(de)(de)(de)技術之一(yi),它(ta)對(dui)(dui)水(shui)中(zhong)多(duo)種污(wu)(wu)染(ran)物(wu)(wu)有很好(hao)的(de)(de)(de)去除(chu)(chu)效(xiao)果(guo)。活(huo)(huo)性(xing)炭(tan)(tan)(tan)(tan)吸(xi)附(fu)是完善常規(gui)處理工藝(yi)以去除(chu)(chu)水(shui)中(zhong)有機污(wu)(wu)染(ran)物(wu)(wu)成熟有效(xiao)的(de)(de)(de)方法之一(yi),可以除(chu)(chu)去水(shui)中(zhong)的(de)(de)(de)臭味、色度(du)、微(wei)(wei)量有機污(wu)(wu)染(ran)物(wu)(wu)(如烷(wan)烴類(lei)、多(duo)環芳烴類(lei)等)、重金屬、合成洗滌劑、放射性(xing)物(wu)(wu)質等多(duo)種污(wu)(wu)染(ran)物(wu)(wu),并對(dui)(dui)水(shui)中(zhong)COD、TOC和Ames致突變性(xing)都有不同(tong)程度(du)的(de)(de)(de)降低。在20世紀六(liu)十年代末(mo)至七十年代末(mo),發達開(kai)展了利用活(huo)(huo)性(xing)炭(tan)(tan)(tan)(tan)吸(xi)附(fu)去除(chu)(chu)水(shui)中(zhong)微(wei)(wei)量有機物(wu)(wu)的(de)(de)(de)研究工作,對(dui)(dui)飲用水(shui)進(jin)行了深(shen)度(du)處理。
隨著生(sheng)物(wu)(wu)(wu)活性(xing)炭應用狀況的(de)不(bu)同,微生(sheng)物(wu)(wu)(wu)的(de)種類(lei)、濃度(du)(du)(du)及個數,活性(xing)炭的(de)種類(lei)、形狀以及裝置的(de)形狀等也不(bu)一(yi)樣。在(zai)高度(du)(du)(du)凈水處理的(de)場合,一(yi)方面(mian),由(you)于要(yao)處理的(de)物(wu)(wu)(wu)質在(zai)水中的(de)濃度(du)(du)(du)非常(chang)低,而(er)且,微生(sheng)物(wu)(wu)(wu)還往往難以分(fen)解(jie)這些物(wu)(wu)(wu)質,因此,除(chu)去這樣的(de)物(wu)(wu)(wu)質就需要(yao)活性(xing)炭的(de)吸附作(zuo)用,而(er)微生(sheng)物(wu)(wu)(wu)具有讓活性(xing)炭的(de)處理效果持續(xu)進(jin)行下去的(de)機能。另一(yi)方面(mian),在(zai)處理有機物(wu)(wu)(wu)濃度(du)(du)(du)高的(de)廢水的(de)場合,結果就變成主(zhu)要(yao)依靠微生(sheng)物(wu)(wu)(wu)分(fen)解(jie)除(chu)去,而(er)活性(xing)炭吸附僅僅起到輔(fu)助作(zuo)用。
生物(wu)活性炭(tan)的(de)(de)(de)機能就是隨著其應(ying)用(yong)場合(he)的(de)(de)(de)不同(tong)而(er)有相當(dang)大(da)的(de)(de)(de)差(cha)異,但共同(tong)點在于在利(li)用(yong)活性炭(tan)吸附的(de)(de)(de)同(tong)時,還積(ji)極地利(li)用(yong)微(wei)生物(wu)的(de)(de)(de)分解機能,可以(yi)認為這就是生物(wu)活性炭(tan)的(de)(de)(de)特征。
目前對(dui)生(sheng)(sheng)(sheng)物(wu)(wu)(wu)活(huo)性(xing)(xing)炭(tan)(tan)的(de)(de)(de)(de)(de)去除(chu)機理(li)沒有(you)統一(yi)公認的(de)(de)(de)(de)(de)解釋,國內外學者有(you)兩種(zhong)機理(li)來解釋BAC的(de)(de)(de)(de)(de)生(sheng)(sheng)(sheng)物(wu)(wu)(wu)降解。其中之一(yi)是(shi):由(you)于(yu)(yu)活(huo)性(xing)(xing)炭(tan)(tan)和(he)水(shui)中的(de)(de)(de)(de)(de)有(you)機物(wu)(wu)(wu)濃度(du)梯度(du),生(sheng)(sheng)(sheng)物(wu)(wu)(wu)活(huo)性(xing)(xing)炭(tan)(tan)的(de)(de)(de)(de)(de)生(sheng)(sheng)(sheng)物(wu)(wu)(wu)降解作用使得活(huo)性(xing)(xing)炭(tan)(tan)再生(sheng)(sheng)(sheng)。該理(li)論(lun)認為由(you)活(huo)性(xing)(xing)炭(tan)(tan)釋放到水(shui)中的(de)(de)(de)(de)(de)有(you)機物(wu)(wu)(wu)由(you)于(yu)(yu)生(sheng)(sheng)(sheng)物(wu)(wu)(wu)降解作用是(shi)逐級減少的(de)(de)(de)(de)(de),使得水(shui)中有(you)機物(wu)(wu)(wu)的(de)(de)(de)(de)(de)濃度(du)較低(di)。因此,吸(xi)附(fu)的(de)(de)(de)(de)(de)有(you)機物(wu)(wu)(wu)由(you)于(yu)(yu)濃度(du)梯度(du)而得以再生(sheng)(sheng)(sheng)。與以往有(you)關協同作用解釋觀點不同的(de)(de)(de)(de)(de)是(shi),他們任務影響生(sheng)(sheng)(sheng)物(wu)(wu)(wu)吸(xi)附(fu)的(de)(de)(de)(de)(de)因素是(shi)活(huo)性(xing)(xing)炭(tan)(tan)生(sheng)(sheng)(sheng)物(wu)(wu)(wu)再生(sheng)(sheng)(sheng)的(de)(de)(de)(de)(de)強(qiang)度(du),并且在整個生(sheng)(sheng)(sheng)物(wu)(wu)(wu)吸(xi)附(fu)過程中微孔(kong)一(yi)直被吸(xi)附(fu)基質所占用,沒有(you)發生(sheng)(sheng)(sheng)生(sheng)(sheng)(sheng)物(wu)(wu)(wu)再生(sheng)(sheng)(sheng),只有(you)過度(du)孔(kong)能夠通過微生(sheng)(sheng)(sheng)物(wu)(wu)(wu)再生(sheng)(sheng)(sheng)。
生(sheng)物(wu)活性炭作(zuo)為(wei)深度處(chu)理(li)工藝的一種有(you)(you)效形式對去除水(shui)中天然有(you)(you)機物(wu)有(you)(you)著重(zhong)要的作(zuo)用。生(sheng)物(wu)活性炭的形成(cheng),活性炭上微生(sheng)物(wu)能夠生(sheng)長繁(fan)殖(zhi),其重(zhong)要原(yuan)因有(you)(you)以(yi)下幾(ji)點:
1、飲用水中(zhong)的(de)微(wei)生物屬于貧營養微(wei)生物,對水中(zhong)的(de)微(wei)量有機污(wu)染物在生存環境上能(neng)夠適應;
2、活性炭(tan)作為微(wei)生(sheng)(sheng)物的載(zai)體(ti),能夠(gou)吸附富集有機物,為微(wei)生(sheng)(sheng)物的生(sheng)(sheng)長儲存(cun)了營(ying)養,并且活性炭(tan)能夠(gou)防止有毒、有害物質(zhi)對(dui)微(wei)生(sheng)(sheng)物的沖擊,防止水流變化的沖擊;
3、臭氧(yang)化將難(nan)降解(jie)有機(ji)物氧(yang)化分解(jie)為(wei)(wei)易降解(jie)有機(ji)物,有利(li)于微生(sheng)物利(li)用,而且對水(shui)體富(fu)氧(yang),使水(shui)體為(wei)(wei)好氧(yang)環境
這幾種作用是微生物在活(huo)性炭表(biao)面生長繁殖,進而形成(cheng)生物活(huo)性炭。
活(huo)(huo)性(xing)(xing)(xing)炭(tan)(tan)吸(xi)附(fu)技術在(zai)實(shi)際應用(yong)(yong)中(zhong),依靠吸(xi)附(fu)法去除有(you)(you)機(ji)物(wu)(wu)的(de)(de)使用(yong)(yong)壽命只有(you)(you)3-6個月,并(bing)且再生(sheng)困(kun)難,生(sheng)物(wu)(wu)活(huo)(huo)性(xing)(xing)(xing)炭(tan)(tan)是(shi)以(yi)活(huo)(huo)性(xing)(xing)(xing)炭(tan)(tan)為載體(ti),用(yong)(yong)生(sheng)長在(zai)炭(tan)(tan)表面的(de)(de)微(wei)(wei)(wei)生(sheng)物(wu)(wu),在(zai)水處理中(zhong)同時(shi)發(fa)揮活(huo)(huo)性(xing)(xing)(xing)炭(tan)(tan)的(de)(de)物(wu)(wu)理吸(xi)附(fu)和微(wei)(wei)(wei)生(sheng)物(wu)(wu)的(de)(de)生(sheng)物(wu)(wu)降(jiang)(jiang)解作用(yong)(yong),因(yin)此既能有(you)(you)效去除水中(zhong)微(wei)(wei)(wei)量(liang)有(you)(you)機(ji)污染物(wu)(wu),又能延長活(huo)(huo)性(xing)(xing)(xing)炭(tan)(tan)的(de)(de)使用(yong)(yong)壽命。依靠活(huo)(huo)性(xing)(xing)(xing)炭(tan)(tan)自然形(xing)成(cheng)的(de)(de)生(sheng)物(wu)(wu)活(huo)(huo)性(xing)(xing)(xing)炭(tan)(tan),其生(sheng)物(wu)(wu)較為復(fu)雜,生(sheng)物(wu)(wu)降(jiang)(jiang)解的(de)(de)速率不高(gao),通過人(ren)(ren)工(gong)(gong)強化(hua)(hua)技術如投加高(gao)活(huo)(huo)性(xing)(xing)(xing)微(wei)(wei)(wei)生(sheng)物(wu)(wu),采用(yong)(yong)人(ren)(ren)工(gong)(gong)固(gu)定化(hua)(hua)技術形(xing)成(cheng)的(de)(de)生(sheng)物(wu)(wu)活(huo)(huo)性(xing)(xing)(xing)炭(tan)(tan),則具有(you)(you)高(gao)效、長效、運行穩定和出水無(wu)病原微(wei)(wei)(wei)生(sheng)物(wu)(wu)等優點,因(yin)此以(yi)人(ren)(ren)工(gong)(gong)固(gu)定化(hua)(hua)技術為代表的(de)(de)活(huo)(huo)性(xing)(xing)(xing)炭(tan)(tan)生(sheng)物(wu)(wu)強化(hua)(hua)工(gong)(gong)藝也越來越收到人(ren)(ren)們的(de)(de)重視。
二、生物活性炭的制備
人工形(xing)成的(de)生物(wu)(wu)(wu)(wu)活(huo)(huo)性(xing)(xing)炭(tan)的(de)微(wei)生物(wu)(wu)(wu)(wu),是采(cai)用新(xin)型(xing)生物(wu)(wu)(wu)(wu)菌(jun)種(zhong)(zhong)篩選和馴(xun)化(hua)(hua)技術,使(shi)得(de)(de)生物(wu)(wu)(wu)(wu)菌(jun)種(zhong)(zhong)針對水(shui)(shui)中微(wei)量有(you)機(ji)物(wu)(wu)(wu)(wu)具有(you)高(gao)(gao)效降解性(xing)(xing),同(tong)時也(ye)保(bao)證(zheng)了生物(wu)(wu)(wu)(wu)菌(jun)種(zhong)(zhong)的(de)生物(wu)(wu)(wu)(wu)安全性(xing)(xing);對生物(wu)(wu)(wu)(wu)菌(jun)種(zhong)(zhong)采(cai)用人工固(gu)定(ding)化(hua)(hua)方(fang)法,限度地(di)提高(gao)(gao)了活(huo)(huo)性(xing)(xing)炭(tan)上固(gu)定(ding)生物(wu)(wu)(wu)(wu)菌(jun)種(zhong)(zhong)的(de)數量,增加了生物(wu)(wu)(wu)(wu)菌(jun)種(zhong)(zhong)與活(huo)(huo)性(xing)(xing)炭(tan)結合的(de)緊密程度,保(bao)證(zheng)微(wei)生物(wu)(wu)(wu)(wu)菌(jun)種(zhong)(zhong)的(de)高(gao)(gao)活(huo)(huo)性(xing)(xing),使(shi)得(de)(de)生物(wu)(wu)(wu)(wu)活(huo)(huo)性(xing)(xing)炭(tan)能夠快速有(you)效地(di)降解水(shui)(shui)中微(wei)量的(de)水(shui)(shui)中有(you)機(ji)污(wu)染物(wu)(wu)(wu)(wu)。
固(gu)定化(hua)生(sheng)物活性(xing)炭(tan)(tan)是以活性(xing)炭(tan)(tan)為(wei)(wei)載(zai)(zai)體(ti),人為(wei)(wei)采用吸附(fu)載(zai)(zai)體(ti)法將(jiang)工程菌吸附(fu)在活性(xing)炭(tan)(tan)表面形成生(sheng)物膜,通(tong)過(guo)工程菌的生(sheng)物降解作用和活性(xing)炭(tan)(tan)纖維(wei)的物理吸附(fu)作用對污染物進行去除,而工程菌是經過(guo)針(zhen)對性(xing)篩選(xuan)、馴化(hua)得到(dao)的活性(xing)極高(gao)的微生(sheng)物。
三、生物活性炭的應用
從生物活性炭技術發(fa)現至今(jin),BAC已(yi)在許(xu)多成功地應用(yong)于污(wu)染水(shui)源凈化、工(gong)業廢水(shui)處理和污(wu)水(shui)的深度凈化等。生物活性炭技術的應用(yong)研究(jiu)有以下(xia)幾個方面。
1、飲用水處理
生(sheng)物(wu)(wu)(wu)(wu)(wu)活(huo)(huo)性(xing)炭目前在日本(ben)、西歐(ou)等(deng)的水(shui)廠(chang)有著較為廣泛(fan)的應用,其(qi)中有代表性(xing)的應用實例有:法國魯昂市夏佩爾水(shui)廠(chang),該(gai)水(shui)廠(chang)是世界上運行久的生(sheng)物(wu)(wu)(wu)(wu)(wu)活(huo)(huo)性(xing)炭處理(li)(li)廠(chang),是BAC工(gong)藝有代表性(xing)的生(sheng)產應用,其(qi)處理(li)(li)流(liu)程為:源水(shui)→預臭氧(yang)化→砂濾→粒狀生(sheng)物(wu)(wu)(wu)(wu)(wu)炭濾池→二次臭氧(yang)化→后氯化出水(shui)。該(gai)廠(chang)處理(li)(li)量為5萬立方(fang)米/天,采(cai)用生(sheng)物(wu)(wu)(wu)(wu)(wu)活(huo)(huo)性(xing)炭主(zhu)要是去(qu)除氨及合成有機物(wu)(wu)(wu)(wu)(wu)。進水(shui)COD為0.15mg/L,去(qu)除率為20%左(zuo)右。運轉到26個(ge)月時出水(shui)水(shui)質仍然很(hen)好,活(huo)(huo)性(xing)炭不(bu)必再生(sheng)。
2、污水處理
生(sheng)物(wu)(wu)(wu)活(huo)性(xing)(xing)(xing)炭對水中(zhong)有機(ji)物(wu)(wu)(wu)有較好(hao)的(de)(de)吸附(fu)性(xing)(xing)(xing)能,可(ke)(ke)以促進有機(ji)物(wu)(wu)(wu)在炭表面集中(zhong),減緩高沖(chong)擊負荷的(de)(de)壓力(li),提(ti)高微(wei)生(sheng)物(wu)(wu)(wu)的(de)(de)降解速率(lv),有效地去除有機(ji)污染物(wu)(wu)(wu)。活(huo)性(xing)(xing)(xing)炭對溶解氧的(de)(de)吸附(fu),可(ke)(ke)保持微(wei)生(sheng)物(wu)(wu)(wu)的(de)(de)活(huo)性(xing)(xing)(xing),促進微(wei)生(sheng)物(wu)(wu)(wu)對有機(ji)物(wu)(wu)(wu)的(de)(de)降解,提(ti)高活(huo)性(xing)(xing)(xing)炭的(de)(de)吸附(fu)容(rong)量(liang),大大延長活(huo)性(xing)(xing)(xing)炭的(de)(de)使用周期,起到活(huo)性(xing)(xing)(xing)炭的(de)(de)生(sheng)物(wu)(wu)(wu)再(zai)生(sheng)作用。
生(sheng)(sheng)物活(huo)性(xing)炭(tan)法處理有機廢水時,不(bu)僅運(yun)行(xing)穩定、除去(qu)率高,同(tong)時可去(qu)除活(huo)性(xing)炭(tan)和微(wei)生(sheng)(sheng)物單獨(du)作用時不(bu)能去(qu)除的(de)(de)污染物。目前,生(sheng)(sheng)物活(huo)性(xing)炭(tan)技術已經在飲用水、工業燃料廢水、生(sheng)(sheng)活(huo)污水的(de)(de)處理中得到了廣泛的(de)(de)應用研究。
生(sheng)(sheng)(sheng)(sheng)物活(huo)性炭處(chu)理(li)苯(ben)酚廢(fei)水時,可借助于(yu)活(huo)性炭的(de)吸(xi)附和(he)微(wei)生(sheng)(sheng)(sheng)(sheng)物的(de)降(jiang)解(jie)作用。研究表明,活(huo)性炭吸(xi)附與生(sheng)(sheng)(sheng)(sheng)物相(xiang)結合能有效(xiao)地(di)去除廢(fei)水中的(de)苯(ben)酚,利(li)用微(wei)生(sheng)(sheng)(sheng)(sheng)物的(de)生(sheng)(sheng)(sheng)(sheng)物降(jiang)解(jie)可以(yi)很好(hao)地(di)解(jie)決活(huo)性炭的(de)再生(sheng)(sheng)(sheng)(sheng)問題。
3、臭氧-生物活性炭工藝
目前(qian),臭氧(yang)(yang)(yang)(yang)(yang)-生(sheng)(sheng)(sheng)物(wu)(wu)活(huo)性(xing)炭(tan)工(gong)藝在(zai)水(shui)的(de)深度處理上應用(yong)較為廣泛,國內(nei)外對(dui)(dui)03-BAC技術也(ye)開展了(le)大(da)量的(de)研(yan)究(jiu)工(gong)作。在(zai)微(wei)污染源水(shui)處理中,生(sheng)(sheng)(sheng)物(wu)(wu)活(huo)性(xing)炭(tan)對(dui)(dui)去除原水(shui)中有機(ji)物(wu)(wu)和部(bu)分消(xiao)毒副產(chan)物(wu)(wu)。給(gei)水(shui)處理中常(chang)采(cai)用(yong)臭氧(yang)(yang)(yang)(yang)(yang)預氧(yang)(yang)(yang)(yang)(yang)化(hua),發揮(hui)臭氧(yang)(yang)(yang)(yang)(yang)的(de)強氧(yang)(yang)(yang)(yang)(yang)化(hua)能力,提(ti)高有機(ji)物(wu)(wu)的(de)可(ke)生(sheng)(sheng)(sheng)化(hua)性(xing)。臭氧(yang)(yang)(yang)(yang)(yang)分解(jie)后產(chan)生(sheng)(sheng)(sheng)的(de)氧(yang)(yang)(yang)(yang)(yang)保持濾柱(zhu)內(nei)有好的(de)好氧(yang)(yang)(yang)(yang)(yang)條件(jian),好氧(yang)(yang)(yang)(yang)(yang)微(wei)生(sheng)(sheng)(sheng)物(wu)(wu)在(zai)活(huo)性(xing)炭(tan)表面(mian)繁殖生(sheng)(sheng)(sheng)長,對(dui)(dui)吸附的(de)有機(ji)物(wu)(wu)生(sheng)(sheng)(sheng)物(wu)(wu)降解(jie),于萬波等(deng)人采(cai)用(yong)人工(gong)配水(shui)方(fang)式(shi),通過中試研(yan)究(jiu)03-BAC工(gong)藝對(dui)(dui)有機(ji)微(wei)污染原水(shui)深度凈化(hua)處理的(de)效果(guo),結果(guo)表面(mian),選擇適(shi)應投加臭氧(yang)(yang)(yang)(yang)(yang)環境的(de)優勢菌種,人工(gong)固(gu)定(ding)化(hua)形成(cheng)生(sheng)(sheng)(sheng)物(wu)(wu)活(huo)性(xing)炭(tan),可(ke)以在(zai)水(shui)溫較低時(shi),較短(duan)時(shi)間內(nei)達(da)到生(sheng)(sheng)(sheng)物(wu)(wu)活(huo)性(xing)炭(tan)的(de)穩定(ding)性(xing)期