人工濕地在城市水污染治理中的應用
摘要:人(ren)工濕地(di)(di)污水(shui)處理是由相互關(guan)聯的(de)基質、植物(wu)和(he)微生物(wu)通過物(wu)理、化(hua)學、生物(wu)過程的(de)協同(tong)作(zuo)用完成(cheng)的(de)，它只(zhi)需要投(tou)入極少的(de)人(ren)力和(he)能(neng)(neng)源，就(jiu)可以去除(chu)有(you)(you)機(ji)污染(ran)(ran)物(wu)、營養物(wu)質、固(gu)體懸浮物(wu)、重(zhong)金屬(shu)物(wu)質，實現對生活污水(shui)、面源污染(ran)(ran)徑(jing)流、農(nong)田(tian)廢水(shui)、二級污水(shui)處理廠出水(shui)、河(he)道末(mo)端水(shui)進行長期穩定的(de)凈化(hua)處理。目前，該工藝在鄭(zheng)州和(he)成(cheng)都得到(dao)了(le)應用，均取得了(le)很(hen)好的(de)效(xiao)果，然(ran)而人(ren)工濕地(di)(di)在城市水(shui)污染(ran)(ran)治理中還(huan)存(cun)在有(you)(you)機(ji)質積(ji)累、占(zhan)地(di)(di)面積(ji)大、受季節影(ying)響(xiang)等問題。人(ren)工濕地(di)(di)是耐用而高效(xiao)的(de)系統(tong)，不斷完善人(ren)工濕地(di)(di)的(de)設(she)計、性(xing)能(neng)(neng)、操作(zuo)及(ji)維護，將能(neng)(neng)夠更(geng)有(you)(you)效(xiao)地(di)(di)改善水(shui)質。
關(guan)鍵(jian)詞: 污水處理; 人工濕地; 生(sheng)物凈化; 城市環(huan)境水利(li)
相(xiang)比工(gong)(gong)(gong)(gong)(gong)(gong)業(ye)污(wu)(wu)水(shui)(shui)(shui)，城市水(shui)(shui)(shui)污(wu)(wu)染一般(ban)污(wu)(wu)染物(wu)(wu)(wu)濃度低(di)、水(shui)(shui)(shui)量大，不宜采用(yong)常規的(de)污(wu)(wu)水(shui)(shui)(shui)二級處理(li)方(fang)(fang)法，而適于采用(yong)人(ren)(ren)(ren)工(gong)(gong)(gong)(gong)(gong)(gong)濕(shi)(shi)(shi)(shi)(shi)(shi)(shi)地(di)(di)(di)等生態凈化處理(li)方(fang)(fang)法。人(ren)(ren)(ren)工(gong)(gong)(gong)(gong)(gong)(gong)濕(shi)(shi)(shi)(shi)(shi)(shi)(shi)地(di)(di)(di)是20 世紀70 年代發展起來的(de)一種新興污(wu)(wu)水(shui)(shui)(shui)處理(li)技術，它將污(wu)(wu)水(shui)(shui)(shui)、污(wu)(wu)泥有控(kong)制地(di)(di)(di)投(tou)配到人(ren)(ren)(ren)工(gong)(gong)(gong)(gong)(gong)(gong)建(jian)造的(de)濕(shi)(shi)(shi)(shi)(shi)(shi)(shi)地(di)(di)(di)上，在土壤(rang)、人(ren)(ren)(ren)工(gong)(gong)(gong)(gong)(gong)(gong)介質、植物(wu)(wu)(wu)、微生物(wu)(wu)(wu)的(de)物(wu)(wu)(wu)理(li)、化學、生物(wu)(wu)(wu)三(san)重協同作用(yong)下，對(dui)污(wu)(wu)水(shui)(shui)(shui)、污(wu)(wu)泥進行處理(li)［1］。目(mu)前(qian)，一般(ban)所指的(de)人(ren)(ren)(ren)工(gong)(gong)(gong)(gong)(gong)(gong)濕(shi)(shi)(shi)(shi)(shi)(shi)(shi)地(di)(di)(di)都(dou)是挺(ting)水(shui)(shui)(shui)植物(wu)(wu)(wu)系統，根據(ju)污(wu)(wu)水(shui)(shui)(shui)在濕(shi)(shi)(shi)(shi)(shi)(shi)(shi)地(di)(di)(di)中流(liu)動的(de)方(fang)(fang)式可分(fen)為(wei)(wei)表(biao)面流(liu)人(ren)(ren)(ren)工(gong)(gong)(gong)(gong)(gong)(gong)濕(shi)(shi)(shi)(shi)(shi)(shi)(shi)地(di)(di)(di)、潛流(liu)人(ren)(ren)(ren)工(gong)(gong)(gong)(gong)(gong)(gong)濕(shi)(shi)(shi)(shi)(shi)(shi)(shi)地(di)(di)(di)、垂(chui)直流(liu)人(ren)(ren)(ren)工(gong)(gong)(gong)(gong)(gong)(gong)濕(shi)(shi)(shi)(shi)(shi)(shi)(shi)地(di)(di)(di)，其中:表(biao)面流(liu)人(ren)(ren)(ren)工(gong)(gong)(gong)(gong)(gong)(gong)濕(shi)(shi)(shi)(shi)(shi)(shi)(shi)地(di)(di)(di)與自然濕(shi)(shi)(shi)(shi)(shi)(shi)(shi)地(di)(di)(di)最為(wei)(wei)接近，投(tou)資較(jiao)低(di)，但占地(di)(di)(di)面積大、處理(li)能力低(di)，一般(ban)情況下難(nan)以被采用(yong); 潛流(liu)人(ren)(ren)(ren)工(gong)(gong)(gong)(gong)(gong)(gong)濕(shi)(shi)(shi)(shi)(shi)(shi)(shi)地(di)(di)(di)占地(di)(di)(di)面積約(yue)為(wei)(wei)表(biao)面流(liu)人(ren)(ren)(ren)工(gong)(gong)(gong)(gong)(gong)(gong)濕(shi)(shi)(shi)(shi)(shi)(shi)(shi)地(di)(di)(di)的(de)15%，且(qie)保溫性(xing)能好、處理(li)效果(guo)受(shou)氣候影響(xiang)小，是目(mu)前(qian)研(yan)究(jiu)和(he)應(ying)(ying)用(yong)較(jiao)多(duo)(duo)的(de)一種人(ren)(ren)(ren)工(gong)(gong)(gong)(gong)(gong)(gong)濕(shi)(shi)(shi)(shi)(shi)(shi)(shi)地(di)(di)(di)處理(li)系統;垂(chui)直流(liu)人(ren)(ren)(ren)工(gong)(gong)(gong)(gong)(gong)(gong)濕(shi)(shi)(shi)(shi)(shi)(shi)(shi)地(di)(di)(di)對(dui)基建(jian)要求較(jiao)高，衛生條件(jian)差，目(mu)前(qian)研(yan)究(jiu)和(he)應(ying)(ying)用(yong)成果(guo)還(huan)不多(duo)(duo)。筆者(zhe)基于表(biao)面流(liu)人(ren)(ren)(ren)工(gong)(gong)(gong)(gong)(gong)(gong)濕(shi)(shi)(shi)(shi)(shi)(shi)(shi)地(di)(di)(di)和(he)潛流(liu)人(ren)(ren)(ren)工(gong)(gong)(gong)(gong)(gong)(gong)濕(shi)(shi)(shi)(shi)(shi)(shi)(shi)地(di)(di)(di)的(de)凈化機理(li)，分(fen)析了人(ren)(ren)(ren)工(gong)(gong)(gong)(gong)(gong)(gong)濕(shi)(shi)(shi)(shi)(shi)(shi)(shi)地(di)(di)(di)在城市水(shui)(shui)(shui)污(wu)(wu)染治理(li)中的(de)應(ying)(ying)用(yong)案例、存在問題和(he)發展前(qian)景(jing)。
1 人工濕地的凈化機理
人工(gong)濕地只需要投(tou)入極少的(de)(de)(de)人力和(he)能源(yuan)，就可以去除有(you)機(ji)污染(ran)物(wu)、營養物(wu)質、固體懸浮物(wu)、重(zhong)金屬物(wu)質，實現對生(sheng)活污水、面源(yuan)污染(ran)徑流、農(nong)田廢水、二級污水處理(li)廠出水、河道末端水進行長期穩定的(de)(de)(de)凈化(hua)處理(li)。人工(gong)濕地污水處理(li)是(shi)由(you)相互關聯的(de)(de)(de)基質、植物(wu)和(he)微生(sheng)物(wu)通過(guo)物(wu)理(li)、化(hua)學、生(sheng)物(wu)過(guo)程的(de)(de)(de)協同作用(yong)(yong)完成的(de)(de)(de)，其效(xiao)果受到上述因素及其相互作用(yong)(yong)的(de)(de)(de)直(zhi)接或間接影響。
1．1 去除有機污染物
人工濕地對(dui)有機(ji)污染(ran)物具有較強(qiang)的(de)去(qu)除能力，不(bu)溶性有機(ji)物通(tong)過(guo)(guo)在濕地基質中的(de)沉積(ji)等(deng)可以很快(kuai)被(bei)截留，進而(er)被(bei)微(wei)生(sheng)(sheng)物分解(jie)(jie)、利用，可溶性有機(ji)物則通(tong)過(guo)(guo)植物根(gen)系生(sheng)(sheng)物膜的(de)吸(xi)附、吸(xi)收及(ji)厭氧(yang)、好氧(yang)生(sheng)(sheng)物代謝降(jiang)解(jie)(jie)被(bei)分解(jie)(jie)和(he)去(qu)除［2 － 3］。植物根(gen)系對(dui)氧(yang)的(de)傳(chuan)遞釋放，不(bu)僅可使(shi)污染(ran)物被(bei)植物、微(wei)生(sheng)(sheng)物吸(xi)附，還可以通(tong)過(guo)(guo)硝化(hua)、反硝化(hua)和(he)累積(ji)、降(jiang)解(jie)(jie)、結(jie)合、吸(xi)附等(deng)作(zuo)用顯著提高污染(ran)物的(de)去(qu)除率。
(1) 表(biao)面(mian)人工流(liu)濕(shi)(shi)(shi)地的(de)BOD5 去(qu)除(chu)機(ji)理。在(zai)表(biao)面(mian)流(liu)濕(shi)(shi)(shi)地系(xi)統(tong)中，BOD5 的(de)去(qu)除(chu)主要是由吸附在(zai)植物根、莖以及落入(ru)水中的(de)葉子上(shang)的(de)微(wei)生物完成(cheng)的(de)。對(dui)于(yu)低中度有機(ji)污染負荷，表(biao)面(mian)流(liu)人工濕(shi)(shi)(shi)地系(xi)統(tong)設(she)計(ji)水深應小于(yu)600 mm，以確保(bao)有足夠的(de)氧氣分布。表(biao)面(mian)流(liu)濕(shi)(shi)(shi)地系(xi)統(tong)去(qu)除(chu)BOD5 的(de)一階模型為(wei)
Ce /Co = Aexp(-0．7KtAv1．75 LWdn /Q)
式中: Ce 為(wei)(wei)(wei)濕地(di)出水(shui)(shui)BOD5 質量(liang)濃度(du)，mg /L; Co 為(wei)(wei)(wei)進入濕地(di)污水(shui)(shui)BOD5 質量(liang)濃度(du)，mg /L; A 為(wei)(wei)(wei)濕地(di)系統中距離入口處較近(jin)的(de)(de)未被除(chu)去的(de)(de)BOD5 的(de)(de)百分比; Kt 為(wei)(wei)(wei)一級(ji)反(fan)應的(de)(de)溫度(du)，℃; Av 為(wei)(wei)(wei)單位體(ti)積(ji)微生物活動的(de)(de)表面積(ji)，m2 /m3 ; L 為(wei)(wei)(wei)濕地(di)長(chang)度(du)，m; W 為(wei)(wei)(wei)濕地(di)寬度(du)，m; d 為(wei)(wei)(wei)濕地(di)深(shen)度(du)，m; n 為(wei)(wei)(wei)濕地(di)孔隙度(du)，%; Q 為(wei)(wei)(wei)平(ping)均(jun)水(shui)(shui)力負荷，m/d。
(2) 潛(qian)流(liu)(liu)人(ren)工濕(shi)地(di)的BOD5 去除機理。在(zai)大多情況(kuang)下(xia)，潛(qian)流(liu)(liu)濕(shi)地(di)系(xi)統很少有(you)直接的大氣復(fu)氧，為了(le)保持流(liu)(liu)動床表(biao)面以下(xia)的氧氣含量(liang)，需(xu)要對植物進行選擇。潛(qian)流(liu)(liu)濕(shi)地(di)系(xi)統去除BOD5可采用一(yi)階推流(liu)(liu)反應動力(li)學方程來估計所(suo)需(xu)的表(biao)面積，計算公(gong)式為
Ce /Co = exp(-Ktt)
As = Q(ln Co-ln Ce ) / (Ktdn)
式中: t 為水力停(ting)留時間，d; As 為濕地(di)的表面(mian)積，m2。
1．2 脫氮作用
在(zai)人工濕地中(zhong)，氮(dan)主(zhu)要(yao)是通(tong)過微生(sheng)(sheng)物(wu)的(de)(de)硝化(hua)(hua)和(he)反硝化(hua)(hua)作(zuo)用(yong)(yong)、植物(wu)的(de)(de)脫氮(dan)作(zuo)用(yong)(yong)、氨氮(dan)的(de)(de)揮發(fa)(fa)、基(ji)質的(de)(de)吸(xi)(xi)附和(he)過濾(lv)等(deng)過程被(bei)去除(chu)的(de)(de)［4］。基(ji)質對氮(dan)的(de)(de)去除(chu)不具有持續性，其僅(jin)為微生(sheng)(sheng)物(wu)同(tong)化(hua)(hua)、降(jiang)解和(he)植物(wu)吸(xi)(xi)收(shou)提供(gong)中(zhong)介，氨氮(dan)的(de)(de)揮發(fa)(fa)即使在(zai)夏季也相當微弱，因此濕地植物(wu)和(he)微生(sheng)(sheng)物(wu)作(zuo)用(yong)(yong)是脫氮(dan)的(de)(de)主(zhu)要(yao)機(ji)(ji)(ji)理。污水中(zhong)的(de)(de)氮(dan)包(bao)括無機(ji)(ji)(ji)氮(dan)和(he)有機(ji)(ji)(ji)氮(dan)，其中(zhong): 無機(ji)(ji)(ji)氮(dan)占總氮(dan)的(de)(de)8% ～ 16%，可以(yi)被(bei)人工濕地中(zhong)的(de)(de)植物(wu)吸(xi)(xi)收(shou)，合成植物(wu)蛋(dan)白質，隨著植物(wu)的(de)(de)收(shou)割從(cong)濕地系統中(zhong)去除(chu); 有機(ji)(ji)(ji)氮(dan)則主(zhu)要(yao)依靠微生(sheng)(sheng)物(wu)的(de)(de)硝化(hua)(hua)和(he)反硝化(hua)(hua)作(zuo)用(yong)(yong)去除(chu)。
1．3 除磷作用
人工濕(shi)(shi)地(di)的(de)(de)(de)除(chu)磷(lin)(lin)(lin)(lin)機(ji)理主要包(bao)括基(ji)質(zhi)對磷(lin)(lin)(lin)(lin)的(de)(de)(de)吸(xi)附和(he)沉(chen)淀(dian)、植(zhi)物(wu)(wu)對磷(lin)(lin)(lin)(lin)的(de)(de)(de)吸(xi)收、微(wei)生物(wu)(wu)對磷(lin)(lin)(lin)(lin)的(de)(de)(de)同化吸(xi)收、無脊椎動物(wu)(wu)分泌物(wu)(wu)的(de)(de)(de)除(chu)磷(lin)(lin)(lin)(lin)作(zuo)用。除(chu)磷(lin)(lin)(lin)(lin)效(xiao)果以(yi)基(ji)質(zhi)吸(xi)附、植(zhi)物(wu)(wu)吸(xi)收和(he)微(wei)生物(wu)(wu)去除(chu)為佳(jia)，而磷(lin)(lin)(lin)(lin)最終(zhong)從系(xi)統中去除(chu)，則依(yi)賴于濕(shi)(shi)地(di)植(zhi)物(wu)(wu)的(de)(de)(de)收割和(he)飽和(he)基(ji)質(zhi)的(de)(de)(de)更(geng)換［4］。由于流量(liang)大，污水和(he)土(tu)壤的(de)(de)(de)接觸機(ji)會很有(you)限，因(yin)此許多人工濕(shi)(shi)地(di)系(xi)統的(de)(de)(de)除(chu)磷(lin)(lin)(lin)(lin)效(xiao)率(lv)不高(gao)。有(you)學者提(ti)出(chu)選(xuan)擇適當的(de)(de)(de)土(tu)壤，通過提(ti)高(gao)黏土(tu)、鐵(tie)、鋁含量(liang)來增強(qiang)除(chu)磷(lin)(lin)(lin)(lin)效(xiao)果，然而黏土(tu)會影響排水能力，因(yin)而需要更(geng)大的(de)(de)(de)處(chu)理面積。
1．4 去除懸(xuan)浮物
表面流人(ren)工濕(shi)(shi)地(di)和潛流人(ren)工濕(shi)(shi)地(di)對懸(xuan)浮(fu)物(wu)都有(you)非常好的(de)處(chu)理效果(guo)。受到基質(zhi)層填料、植(zhi)物(wu)根(gen)系和莖(jing)、腐(fu)殖(zhi)層的(de)過(guo)(guo)濾和截留，大部分(fen)固(gu)體懸(xuan)浮(fu)物(wu)的(de)去除過(guo)(guo)程(cheng)發生(sheng)在距離(li)濕(shi)(shi)地(di)進(jin)口5 ～10 m處(chu)，去除率的(de)高低取決于(yu)污水與(yu)植(zhi)物(wu)及填料的(de)接(jie)觸程(cheng)度。在污水管道設計時應適當控制分(fen)散進(jin)水流量(liang)，以防(fang)止濕(shi)(shi)地(di)渠道上游固(gu)體懸(xuan)浮(fu)物(wu)去除效率過(guo)(guo)低，發生(sheng)厭(yan)氧反應。如果(guo)濕(shi)(shi)地(di)中的(de)水體沒有(you)植(zhi)物(wu)對太(tai)陽光(guang)的(de)遮蔽，藻(zao)類的(de)生(sheng)長可(ke)能會(hui)造成出水口附近水體懸(xuan)浮(fu)物(wu)增加(jia)，影響凈化效果(guo)。
1．5 去除重金屬(shu)
受污水與植(zhi)物、填(tian)料接觸程度的(de)影響，表面流人工濕地(di)(di)對(dui)重金(jin)屬的(de)去(qu)(qu)(qu)除(chu)(chu)能力有限，而(er)潛流人工濕地(di)(di)的(de)重金(jin)屬去(qu)(qu)(qu)除(chu)(chu)效果(guo)則相對(dui)較好。人工濕地(di)(di)的(de)重金(jin)屬去(qu)(qu)(qu)除(chu)(chu)機理主要包括土壤的(de)固定、去(qu)(qu)(qu)除(chu)(chu)作(zuo)用，微生物的(de)吸收、轉化作(zuo)用，植(zhi)物的(de)存儲、揮發(fa)和根系的(de)固定作(zuo)用。美國加州桑迪(di)的(de)人工濕地(di)(di)的(de)水力停留時(shi)間為5．5 d時(shi)，對(dui)重金(jin)屬污染物的(de)去(qu)(qu)(qu)除(chu)(chu)效果(guo)較好，其中銅、鋅、鎘的(de)去(qu)(qu)(qu)除(chu)(chu)率分(fen)別達99%、97%、99%。
2 人工濕地在城市水污染治理中的應用案例
2．1 鄭(zheng)州市CBD 中心湖水凈化處理人(ren)工濕地
鄭東(dong)新(xin)區CBD 中心湖(hu)水(shui)(shui)凈(jing)化處理人工濕地(di)位于鄭東(dong)新(xin)區CBD 東(dong)西運河和南北運河交(jiao)匯處，是龍(long)湖(hu)水(shui)(shui)系的(de)重要組成部分(fen)，占地(di)面積約為4 萬(wan)m2，日處理水(shui)(shui)量約為1．0 萬(wan)m3，處理后中心湖(hu)水(shui)(shui)質可達Ⅲ類標(biao)準。
該人(ren)工(gong)(gong)濕(shi)(shi)(shi)(shi)地(di)系(xi)統(tong)(tong)主要(yao)由(you)中(zhong)(zhong)央控(kong)制系(xi)統(tong)(tong)、給(gei)(gei)排(pai)水(shui)(shui)(shui)(shui)(shui)(shui)管線(xian)和(he)(he)配電系(xi)統(tong)(tong)、溫(wen)室(shi)、人(ren)工(gong)(gong)濕(shi)(shi)(shi)(shi)地(di)四(si)大部分組成。作(zuo)為發揮(hui)水(shui)(shui)(shui)(shui)(shui)(shui)質凈化作(zuo)用的(de)主體，人(ren)工(gong)(gong)濕(shi)(shi)(shi)(shi)地(di)是由(you)4 個(ge)跌(die)(die)水(shui)(shui)(shui)(shui)(shui)(shui)曝(pu)氣池(chi)(chi)(chi)、8 塊(kuai)(kuai)濕(shi)(shi)(shi)(shi)地(di)及(ji)連(lian)通(tong)管線(xian)組成的(de)，其中(zhong)(zhong)每個(ge)跌(die)(die)水(shui)(shui)(shui)(shui)(shui)(shui)曝(pu)氣池(chi)(chi)(chi)供兩(liang)塊(kuai)(kuai)濕(shi)(shi)(shi)(shi)地(di)用水(shui)(shui)(shui)(shui)(shui)(shui)。跌(die)(die)水(shui)(shui)(shui)(shui)(shui)(shui)曝(pu)氣池(chi)(chi)(chi)為漿(jiang)砌(qi)卵石(shi)結構，分為一(yi)級(ji)跌(die)(die)水(shui)(shui)(shui)(shui)(shui)(shui)池(chi)(chi)(chi)、二(er)(er)級(ji)跌(die)(die)水(shui)(shui)(shui)(shui)(shui)(shui)池(chi)(chi)(chi)、三級(ji)跌(die)(die)水(shui)(shui)(shui)(shui)(shui)(shui)池(chi)(chi)(chi)，通(tong)過(guo)瀑布式流(liu)水(shui)(shui)(shui)(shui)(shui)(shui)的(de)方式為濕(shi)(shi)(shi)(shi)地(di)水(shui)(shui)(shui)(shui)(shui)(shui)體進行充氧。每塊(kuai)(kuai)濕(shi)(shi)(shi)(shi)地(di)由(you)一(yi)級(ji)生(sheng)物(wu)池(chi)(chi)(chi)、一(yi)級(ji)碎(sui)石(shi)床(chuang)、二(er)(er)級(ji)生(sheng)物(wu)池(chi)(chi)(chi)和(he)(he)二(er)(er)級(ji)碎(sui)石(shi)床(chuang)組成，碎(sui)石(shi)床(chuang)內(nei)和(he)(he)生(sheng)物(wu)池(chi)(chi)(chi)內(nei)栽種的(de)水(shui)(shui)(shui)(shui)(shui)(shui)生(sheng)植(zhi)物(wu)包(bao)括香(xiang)蒲(pu)、蒼蒲(pu)、蘆(lu)葦、水(shui)(shui)(shui)(shui)(shui)(shui)竹、水(shui)(shui)(shui)(shui)(shui)(shui)蔥等(deng)，這些水(shui)(shui)(shui)(shui)(shui)(shui)生(sheng)植(zhi)物(wu)能(neng)夠吸附(fu)水(shui)(shui)(shui)(shui)(shui)(shui)體中(zhong)(zhong)的(de)氮、磷元素，既凈化水(shui)(shui)(shui)(shui)(shui)(shui)體又美化環(huan)境。中(zhong)(zhong)央控(kong)制系(xi)統(tong)(tong)是整個(ge)濕(shi)(shi)(shi)(shi)地(di)系(xi)統(tong)(tong)的(de)控(kong)制監測(ce)中(zhong)(zhong)心，設(she)有水(shui)(shui)(shui)(shui)(shui)(shui)質分析實驗設(she)備、配電控(kong)制系(xi)統(tong)(tong)、濕(shi)(shi)(shi)(shi)地(di)監視(shi)系(xi)統(tong)(tong)和(he)(he)管理人(ren)員(yuan)辦公設(she)施等(deng)。溫(wen)室(shi)主要(yao)用于水(shui)(shui)(shui)(shui)(shui)(shui)生(sheng)植(zhi)物(wu)過(guo)冬和(he)(he)種苗培育。給(gei)(gei)排(pai)水(shui)(shui)(shui)(shui)(shui)(shui)管線(xian)和(he)(he)配電系(xi)統(tong)(tong)是濕(shi)(shi)(shi)(shi)地(di)與中(zhong)(zhong)心湖之間以(yi)及(ji)濕(shi)(shi)(shi)(shi)地(di)各池(chi)(chi)(chi)之間給(gei)(gei)水(shui)(shui)(shui)(shui)(shui)(shui)連(lian)接、水(shui)(shui)(shui)(shui)(shui)(shui)體循環(huan)等(deng)服務(wu)配套設(she)施。
2．2 成(cheng)都鳳凰二(er)溝水處(chu)理人工(gong)濕地
成(cheng)(cheng)都(dou)鳳凰二溝水(shui)處(chu)理(li)人工濕地位于成(cheng)(cheng)都(dou)三(san)環(huan)(huan)路(lu)外側、寶成(cheng)(cheng)鐵(tie)路(lu)以(yi)東、鐵(tie)路(lu)西(xi)環(huan)(huan)線以(yi)南，是(shi)成(cheng)(cheng)都(dou)最大(da)的(de)(de)人工治污(wu)濕地，也(ye)是(shi)成(cheng)(cheng)都(dou)規劃(hua)(hua)的(de)(de)一座污(wu)水(shui)處(chu)理(li)廠(chang)，周邊正(zheng)計劃(hua)(hua)配置游(you)樂設施，目的(de)(de)是(shi)建成(cheng)(cheng)一個集休閑、旅游(you)、環(huan)(huan)保、教育多功(gong)能(neng)于一體(ti)的(de)(de)生態樂園(yuan)。根據《成(cheng)(cheng)都(dou)市(shi)市(shi)域排水(shui)工程體(ti)系規劃(hua)(hua)》，該(gai)人工濕地日處(chu)理(li)污(wu)水(shui)能(neng)力為2．4 萬(wan)m3，將在(zai)成(cheng)(cheng)都(dou)市(shi)的(de)(de)排水(shui)規劃(hua)(hua)中被推(tui)廣使用。
集中到鳳(feng)凰二溝污(wu)(wu)(wu)水(shui)(shui)(shui)處(chu)理(li)人(ren)工(gong)(gong)濕地(di)的污(wu)(wu)(wu)水(shui)(shui)(shui)包括(kuo)生活污(wu)(wu)(wu)水(shui)(shui)(shui)、工(gong)(gong)業(ye)污(wu)(wu)(wu)水(shui)(shui)(shui)、畜(chu)禽養殖(zhi)污(wu)(wu)(wu)水(shui)(shui)(shui)。污(wu)(wu)(wu)水(shui)(shui)(shui)經過前(qian)處(chu)理(li)系(xi)(xi)(xi)統，通過沉淀、曝氣、快(kuai)速滲濾等(deng)方式進行處(chu)理(li)后，流入污(wu)(wu)(wu)水(shui)(shui)(shui)處(chu)理(li)的核(he)心區(qu)域——人(ren)工(gong)(gong)濕地(di)。該人(ren)工(gong)(gong)濕地(di)共8 個處(chu)理(li)系(xi)(xi)(xi)統，種植的植物(wu)包括(kuo)蘆葦、傘草、水(shui)(shui)(shui)葫(hu)蘆、水(shui)(shui)(shui)芹(qin)、香蒲、再力花、美(mei)人(ren)蕉等(deng)，每個系(xi)(xi)(xi)統有(you)4 ～ 5 個獨立(li)的種植有(you)不同植物(wu)的格子(zi)，污(wu)(wu)(wu)水(shui)(shui)(shui)在(zai)里面停(ting)留(liu)一(yi)段時間，再由(you)人(ren)工(gong)(gong)控(kong)制(zhi)流入下一(yi)個格子(zi)，可以根(gen)據植物(wu)特性完(wan)成不同的除(chu)污(wu)(wu)(wu)任務。
3 人工濕地應用存在的問題和發展前景
3．1 存在(zai)的問題
(1) 城(cheng)(cheng)市(shi)(shi)(shi)水(shui)(shui)(shui)污(wu)染(ran)(ran)加(jia)劇(ju)。我國城(cheng)(cheng)市(shi)(shi)(shi)水(shui)(shui)(shui)污(wu)染(ran)(ran)狀況總體(ti)呈(cheng)現出以下(xia)幾個特征(zheng): ①污(wu)染(ran)(ran)范圍大，城(cheng)(cheng)市(shi)(shi)(shi)周(zhou)邊的(de)主(zhu)要河流(liu)和(he)水(shui)(shui)(shui)域都受到了(le)不同(tong)程度(du)的(de)污(wu)染(ran)(ran)，尤其以納污(wu)溝渠污(wu)染(ran)(ran)最為嚴重(zhong); ②多(duo)數水(shui)(shui)(shui)體(ti)呈(cheng)有機污(wu)染(ran)(ran)特征(zheng)，主(zhu)要污(wu)染(ran)(ran)指標有COD、BOD5 和(he)氨氮;③近年來(lai)，城(cheng)(cheng)市(shi)(shi)(shi)工業點(dian)源污(wu)染(ran)(ran)治理(li)(li)取得了(le)顯(xian)著(zhu)成效，但城(cheng)(cheng)市(shi)(shi)(shi)面(mian)源污(wu)染(ran)(ran)問題逐漸凸(tu)顯(xian)，治理(li)(li)難度(du)很大; ④工業用水(shui)(shui)(shui)和(he)生活(huo)用水(shui)(shui)(shui)急劇(ju)增加(jia)，導(dao)致城(cheng)(cheng)市(shi)(shi)(shi)排污(wu)量顯(xian)著(zhu)增加(jia)，與之配(pei)套的(de)節(jie)水(shui)(shui)(shui)和(he)污(wu)水(shui)(shui)(shui)處理(li)(li)設施(shi)建(jian)設明顯(xian)滯后。總體(ti)來(lai)說(shuo)，我國城(cheng)(cheng)市(shi)(shi)(shi)水(shui)(shui)(shui)污(wu)染(ran)(ran)治理(li)(li)面(mian)臨(lin)著(zhu)水(shui)(shui)(shui)循環系統脆弱、水(shui)(shui)(shui)環境質(zhi)量下(xia)降(jiang)、水(shui)(shui)(shui)功能退(tui)化、污(wu)水(shui)(shui)(shui)處理(li)(li)設施(shi)不足(zu)等問題。
(2) 人(ren)(ren)工(gong)濕(shi)(shi)地(di)(di)自身存在(zai)的問(wen)題。雖然人(ren)(ren)工(gong)濕(shi)(shi)地(di)(di)處理(li)工(gong)藝的出水水質能(neng)夠滿足城市中水回用(yong)的要求(qiu)，但仍然存在(zai)一(yi)些問(wen)題: 有(you)些濕(shi)(shi)地(di)(di)在(zai)運行過(guo)程(cheng)中有(you)機質積(ji)累引起填料空隙堵(du)塞，導(dao)致處理(li)能(neng)力下降(jiang); 人(ren)(ren)工(gong)濕(shi)(shi)地(di)(di)占地(di)(di)面(mian)積(ji)大(da)，在(zai)寸土寸金的城市其發展受到限制; 植(zhi)物和(he)有(you)機物吸(xi)收、降(jiang)解(jie)作用(yong)呈現一(yi)定的季節變化規(gui)律，冬(dong)季污(wu)染(ran)物的去除(chu)效果(guo)較差; 人(ren)(ren)工(gong)濕(shi)(shi)地(di)(di)對細菌和(he)病(bing)原體的去除(chu)效率有(you)待提高。
3．2 應用前景
針對上述問題(ti)，可(ke)對人工濕(shi)地(di)進行(xing)改進。
(1) 有機(ji)質積(ji)累。出(chu)現這種情況的(de)根本(ben)原因是有機(ji)質負(fu)荷(he)過(guo)高，需要(yao)采取(qu)措施(shi)控制人工(gong)濕(shi)地負(fu)荷(he)。可(ke)以在(zai)一(yi)定(ding)范圍內將人工(gong)濕(shi)地分(fen)為兩級(ji)(ji): 一(yi)級(ji)(ji)濕(shi)地作(zuo)為宅前(qian)濕(shi)地，處理(li)(li)污染(ran)程度(du)較(jiao)輕、COD 負(fu)荷(he)較(jiao)低的(de)景觀用水等，兼做休閑公園; 二級(ji)(ji)濕(shi)地作(zuo)為公共濕(shi)地，距建筑(zhu)物較(jiao)遠，可(ke)用于處理(li)(li)廚房、廁所排出(chu)的(de)生(sheng)活污水，此類污水的(de)污染(ran)負(fu)荷(he)較(jiao)高，需采用化(hua)糞池或沼氣(qi)池進行預處理(li)(li)，以避(bi)免有機(ji)物積(ji)累。
(2) 占(zhan)地(di)(di)面(mian)積大。通過潛流式(shi)人(ren)工濕(shi)地(di)(di)、垂直流人(ren)工濕(shi)地(di)(di)、人(ren)工濕(shi)地(di)(di)景觀化(hua)等方式(shi)，可有效緩(huan)解人(ren)工濕(shi)地(di)(di)占(zhan)地(di)(di)面(mian)積大與城市發展之間的矛(mao)盾。
(3) 季(ji)節影響(xiang)。有(you)關研(yan)究(jiu)表明，在氣候寒(han)冷的(de)(de)挪威(wei)，有(you)厭氧池進行預處(chu)理(li)的(de)(de)人(ren)工濕地(di)系統，冬季(ji)運行效(xiao)果與其他季(ji)節沒(mei)有(you)明顯不(bu)同; 瑞士利用垂直－水平流濕地(di)組合系統處(chu)理(li)住(zhu)宅區(qu)污水，冬季(ji)的(de)(de)去(qu)除性能也較理(li)想［5］。通過技術(shu)手段可以克服低溫對人(ren)工濕地(di)處(chu)理(li)效(xiao)果的(de)(de)影響(xiang)，如在一級(ji)濕地(di)上建造溫室等。
人(ren)工(gong)濕(shi)地的(de)一個(ge)常見應用(yong)是處理初(chu)次或(huo)二次生活(huo)污水。模仿(fang)自然濕(shi)地處理生活(huo)污水的(de)人(ren)工(gong)濕(shi)地，也可被應用(yong)于處理農(nong)業高負荷有(you)機物(wu)。許多(duo)濕(shi)地已經建成并用(yong)于處理礦井排水，僅在阿帕拉(la)契就有(you)超過500 個(ge)這樣的(de)濕(shi)地系(xi)統。利用(yong)人(ren)工(gong)濕(shi)地處理雨水是這種工(gong)藝近年來新的(de)應用(yong)，人(ren)工(gong)濕(shi)地的(de)數量(liang)也在快速增多(duo)。
人(ren)(ren)工(gong)濕地(di)是耐用而(er)高效的系統。人(ren)(ren)工(gong)濕地(di)處理污水(shui)或(huo)雨水(shui)是一種低成本、低能耗、低人(ren)(ren)工(gong)干預的過程。經(jing)過廣泛研究(jiu)和實際應用，有識(shi)之士正在不斷完善(shan)人(ren)(ren)工(gong)濕地(di)的設計、性能、操(cao)作(zuo)及維護，使其能夠更有效地(di)改善(shan)水(shui)質。
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作(zuo)者簡介:秦明(1964-) ，男，上海人，高(gao)級工(gong)程師(shi)，主要從事水(shui)利工(gong)程建(jian)設管理工(gong)作(zuo)。
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