郝曉地:污水處理行業實現碳中和的路徑及其適用條件對比分析
【谷騰環保網訊】節(jie)能(neng)(neng)(neng)降耗(hao)、污(wu)(wu)泥厭氧消(xiao)化(hua)(hua)(hua)產甲(jia)烷、與(yu)工藝(yi)相關(guan)的(de)能(neng)(neng)(neng)源利用(yong)等策(ce)略可(ke)有(you)(you)助(zhu)于(yu)碳(tan)(tan)減排(pai),但這(zhe)些常規方(fang)法潛力(li)距(ju)碳(tan)(tan)中(zhong)(zhong)和目(mu)標仍(reng)有(you)(you)相當距(ju)離。國(guo)外諸多案(an)例表(biao)明(ming),污(wu)(wu)水(shui)(shui)(shui)(shui)余(yu)溫熱能(neng)(neng)(neng)利用(yong)技術是污(wu)(wu)水(shui)(shui)(shui)(shui)處(chu)理領(ling)域實現碳(tan)(tan)中(zhong)(zhong)和運行的(de)可(ke)行方(fang)案(an)。在總(zong)結污(wu)(wu)水(shui)(shui)(shui)(shui)處(chu)理領(ling)域碳(tan)(tan)減排(pai)策(ce)略的(de)基礎上(shang),評(ping)價(jia)分析(xi)其對碳(tan)(tan)中(zhong)(zhong)和的(de)貢(gong)獻。通過對國(guo)內案(an)例計算分析(xi)余(yu)溫熱能(neng)(neng)(neng)潛力(li)并與(yu)有(you)(you)機(ji)(COD)能(neng)(neng)(neng)轉化(hua)(hua)(hua)率(lv)進行比(bi)較發現,污(wu)(wu)水(shui)(shui)(shui)(shui)中(zhong)(zhong)蘊含的(de)余(yu)溫熱能(neng)(neng)(neng)潛力(li)為有(you)(you)機(ji)化(hua)(hua)(hua)學能(neng)(neng)(neng)的(de)9倍。余(yu)溫熱能(neng)(neng)(neng)利用(yong)可(ke)使污(wu)(wu)水(shui)(shui)(shui)(shui)處(chu)理廠達到(dao)碳(tan)(tan)中(zhong)(zhong)和目(mu)標,還可(ke)將剩余(yu)熱能(neng)(neng)(neng)(約75%~85%)以(yi)供熱/制冷形式(shi)向外輸(shu)出(chu),或用(yong)于(yu)原位(wei)低溫污(wu)(wu)泥干化(hua)(hua)(hua),實現污(wu)(wu)水(shui)(shui)(shui)(shui)處(chu)理廠向“能(neng)(neng)(neng)源工廠”轉型。
在污(wu)(wu)水(shui)(shui)(shui)處理(li)過(guo)(guo)程(cheng)中(zhong),由于(yu)大量藥劑,以及曝氣(qi)、污(wu)(wu)泥脫水(shui)(shui)(shui)設備、水(shui)(shui)(shui)泵(beng)等(deng)的電耗非常大,因此,污(wu)(wu)水(shui)(shui)(shui)處理(li)行業(ye)在保護水(shui)(shui)(shui)環境的同時(shi),也是高耗能產業(ye)。同時(shi),一些污(wu)(wu)水(shui)(shui)(shui)處理(li)過(guo)(guo)程(cheng)還伴有CH4、N2O等(deng)直(zhi)接溫室氣(qi)體(ti)排放,污(wu)(wu)水(shui)(shui)(shui)處理(li)過(guo)(guo)程(cheng)的、中(zhong)碳排放問題不可小覷。
以(yi)(yi)實現(xian)碳中(zhong)和(Carbon neutrality)或能量自(zi)給(gei)(gei)自(zi)足(zu)(zu)(zu)(Energy self-sufficiency)為(wei)目標,多個國家對(dui)污(wu)(wu)水(shui)處(chu)理碳中(zhong)和運(yun)行制定(ding)了相關政策。荷(he)蘭提(ti)出(chu)NEWs概念(nian),將未(wei)來污(wu)(wu)水(shui)處(chu)理廠描述為(wei)“營養物(wu)(Nutrient)”、“能源(yuan)(Energy)”、“再(zai)生(sheng)水(shui)(Water)”三廠(Factories)合一的(de)(de)運(yun)行模式;新加坡國家水(shui)務局推行“NEWater”計(ji)劃,并制定(ding)水(shui)行業能源(yuan)自(zi)給(gei)(gei)自(zi)足(zu)(zu)(zu)的(de)(de)三階段目標,其遠期目標為(wei)完全(quan)(quan)實現(xian)能源(yuan)自(zi)給(gei)(gei)自(zi)足(zu)(zu)(zu),甚至向外提(ti)供能量;美國以(yi)(yi)“Carbon-free Water”為(wei)目標,期望實現(xian)對(dui)水(shui)的(de)(de)取用、分配、處(chu)理、排放全(quan)(quan)過程以(yi)(yi)實現(xian)碳中(zhong)和;日本(ben)發(fa)布“Sewerage Vision 2100”,宣布本(ben)世紀末將完全(quan)(quan)實現(xian)污(wu)(wu)水(shui)處(chu)理過程中(zhong)能源(yuan)自(zi)給(gei)(gei)自(zi)足(zu)(zu)(zu)。
已有存在一些通過(guo)不同(tong)手(shou)段(duan)實(shi)現(xian)(xian)(xian)污(wu)(wu)水(shui)處理(li)(li)廠(chang)“能(neng)量(liang)中和(he)(he)”或“碳(tan)(tan)中和(he)(he)”的(de)國(guo)外(wai)案例。奧地利(li)(li)Strass污(wu)(wu)水(shui)處理(li)(li)廠(chang)利(li)(li)用初(chu)沉池可截(jie)留進水(shui)懸(xuan)浮(fu)物(SS)中近(jin)60%的(de)COD,并以A/B工藝最大化(hua)富積剩余(yu)污(wu)(wu)泥(ni)(ni),將初(chu)沉與(yu)(yu)(yu)(yu)剩余(yu)污(wu)(wu)泥(ni)(ni)共厭(yan)氧消(xiao)(xiao)化(hua)并熱電(dian)(dian)(dian)聯(lian)(lian)產(CHP)后可實(shi)現(xian)(xian)(xian)108%能(neng)源(yuan)自給(gei)率(lv)。美國(guo)Sheboygan污(wu)(wu)水(shui)處理(li)(li)廠(chang)利(li)(li)用廠(chang)外(wai)高濃度食品(pin)廢(fei)棄物與(yu)(yu)(yu)(yu)剩余(yu)污(wu)(wu)泥(ni)(ni)厭(yan)氧共消(xiao)(xiao)化(hua)并熱電(dian)(dian)(dian)聯(lian)(lian)產實(shi)現(xian)(xian)(xian)產電(dian)(dian)(dian)量(liang)與(yu)(yu)(yu)(yu)耗(hao)電(dian)(dian)(dian)量(liang)比(bi)值(zhi)達(da)(da)90%~115%、產熱量(liang)與(yu)(yu)(yu)(yu)耗(hao)熱量(liang)比(bi)值(zhi)達(da)(da)85%~90%。德(de)(de)國(guo)Bochum-Ölbachtal污(wu)(wu)水(shui)處理(li)(li)廠(chang)通過(guo)節(jie)能(neng)降耗(hao)與(yu)(yu)(yu)(yu)熱電(dian)(dian)(dian)聯(lian)(lian)產實(shi)現(xian)(xian)(xian)能(neng)源(yuan)中和(he)(he)率(lv)96.9%、碳(tan)(tan)中和(he)(he)率(lv)63.2%。德(de)(de)國(guo)Köhlbrandhöft/Dradenau污(wu)(wu)水(shui)處理(li)(li)廠(chang)通過(guo)厭(yan)氧消(xiao)(xiao)化(hua)與(yu)(yu)(yu)(yu)污(wu)(wu)泥(ni)(ni)干化(hua)焚(fen)燒實(shi)現(xian)(xian)(xian)能(neng)源(yuan)中和(he)(he)率(lv)>100%,并實(shi)現(xian)(xian)(xian)42.3%的(de)碳(tan)(tan)中和(he)(he)率(lv)。希臘Chania污(wu)(wu)水(shui)處理(li)(li)廠(chang)通過(guo)厭(yan)氧消(xiao)(xiao)化(hua)實(shi)現(xian)(xian)(xian)70%的(de)能(neng)源(yuan)中和(he)(he)率(lv),碳(tan)(tan)中和(he)(he)率(lv)達(da)(da)到(dao)58.5%。德(de)(de)國(guo)布(bu)倫瑞(rui)克市Steinhof污(wu)(wu)水(shui)處理(li)(li)廠(chang)通過(guo)剩余(yu)污(wu)(wu)泥(ni)(ni)單獨厭(yan)氧消(xiao)(xiao)化(hua)并熱電(dian)(dian)(dian)聯(lian)(lian)產獲得79%的(de)能(neng)源(yuan)中和(he)(he)率(lv),再通過(guo)補充出(chu)水(shui)農灌(guan)、污(wu)(wu)泥(ni)(ni)回(hui)田等手(shou)段(duan)額外(wai)實(shi)現(xian)(xian)(xian)了35%的(de)碳(tan)(tan)減排量(liang),使(shi)碳(tan)(tan)中和(he)(he)率(lv)高達(da)(da)114%。芬蘭Kakolanmäki污(wu)(wu)水(shui)處理(li)(li)廠(chang)通過(guo)熱電(dian)(dian)(dian)聯(lian)(lian)產與(yu)(yu)(yu)(yu)余(yu)溫熱能(neng)回(hui)收最終實(shi)現(xian)(xian)(xian)高達(da)(da)640%能(neng)源(yuan)中和(he)(he)率(lv)與(yu)(yu)(yu)(yu)332.7%碳(tan)(tan)中和(he)(he)率(lv)。
以上案例表明,為(wei)(wei)實現碳(tan)(tan)中(zhong)(zhong)和(he)目標,國(guo)外污(wu)水(shui)(shui)處(chu)理(li)(li)廠(chang)大都采取超量(liang)有機物(wu)厭氧消(xiao)化并(bing)熱電聯產(chan)的(de)方案。然而,我(wo)國(guo)市政(zheng)污(wu)水(shui)(shui)處(chu)理(li)(li)廠(chang)普遍存在碳(tan)(tan)源低下的(de)情況,該路徑(jing)可(ke)能無(wu)法(fa)實現我(wo)國(guo)污(wu)水(shui)(shui)處(chu)理(li)(li)廠(chang)碳(tan)(tan)中(zhong)(zhong)和(he)。這(zhe)就需(xu)要全方位分析污(wu)水(shui)(shui)自身潛能及利用方式(shi)來制(zhi)定適宜于我(wo)國(guo)污(wu)水(shui)(shui)處(chu)理(li)(li)領域的(de)碳(tan)(tan)中(zhong)(zhong)和(he)途徑(jing)。在國(guo)內,基于碳(tan)(tan)中(zhong)(zhong)和(he)的(de)污(wu)水(shui)(shui)處(chu)理(li)(li)運行機制(zhi)研究(jiu)才(cai)剛起步。在技(ji)術(shu)(shu)層(ceng)面(mian),各種(zhong)節能降(jiang)耗(hao)、能量(liang)回(hui)收(shou)方式(shi)直(zhi)接(jie)或間接(jie)補償污(wu)水(shui)(shui)處(chu)理(li)(li)碳(tan)(tan)排放量(liang)似(si)乎是實現污(wu)水(shui)(shui)處(chu)理(li)(li)碳(tan)(tan)中(zhong)(zhong)和(he)的(de)重要手段(duan)。基于此,本文從(cong)能量(liang)中(zhong)(zhong)和(he)與碳(tan)(tan)中(zhong)(zhong)和(he)基本概念入手,梳理(li)(li)污(wu)水(shui)(shui)處(chu)理(li)(li)行業碳(tan)(tan)減排策略(lve),同時探討其能量(liang)潛力、技(ji)術(shu)(shu)路徑(jing)及可(ke)操作性(xing)等,以期為(wei)(wei)我(wo)國(guo)污(wu)水(shui)(shui)處(chu)理(li)(li)領域選擇適宜的(de)碳(tan)(tan)中(zhong)(zhong)和(he)路徑(jing)提供參考。
1 污水處理碳減排途徑及案例分析
1)技術升級實現節能減排
污(wu)(wu)水(shui)處(chu)理(li)(li)(li)過程(cheng)碳(tan)(tan)排(pai)(pai)(pai)放(fang)(fang)(fang)分(fen)直(zhi)接(jie)碳(tan)(tan)排(pai)(pai)(pai)放(fang)(fang)(fang)與(yu)間接(jie)碳(tan)(tan)排(pai)(pai)(pai)放(fang)(fang)(fang)。其中(zhong),按IPCC規定由污(wu)(wu)水(shui)中(zhong)生(sheng)源性COD產生(sheng)的CO2(直(zhi)接(jie)排(pai)(pai)(pai)放(fang)(fang)(fang))不應納(na)入(ru)污(wu)(wu)水(shui)處(chu)理(li)(li)(li)碳(tan)(tan)排(pai)(pai)(pai)放(fang)(fang)(fang)清(qing)單,而CH4、N2O及污(wu)(wu)水(shui)COD中(zhong)化石(shi)(shi)成(cheng)分(fen)產生(sheng)的CO2則應納(na)入(ru)污(wu)(wu)水(shui)處(chu)理(li)(li)(li)直(zhi)接(jie)碳(tan)(tan)排(pai)(pai)(pai)放(fang)(fang)(fang)清(qing)單。因此(ci),間接(jie)碳(tan)(tan)排(pai)(pai)(pai)放(fang)(fang)(fang)包括:電耗(化石(shi)(shi)燃料)碳(tan)(tan)排(pai)(pai)(pai)放(fang)(fang)(fang),即,污(wu)(wu)水(shui)、污(wu)(wu)泥(ni)處(chu)理(li)(li)(li)全過程(cheng)涉及能耗,以及藥耗碳(tan)(tan)排(pai)(pai)(pai)放(fang)(fang)(fang)(指污(wu)(wu)水(shui)處(chu)理(li)(li)(li)所用碳(tan)(tan)源、除磷藥劑等在(zai)生(sheng)產與(yu)運輸(shu)過程(cheng)中(zhong)形(xing)成(cheng)的碳(tan)(tan)排(pai)(pai)(pai)放(fang)(fang)(fang))。
在污水(shui)(shui)、污泥處(chu)理(li)過(guo)(guo)(guo)程(cheng)(cheng)中(zhong),直接(jie)產(chan)生(sheng)(sheng)的(de)CH4、N2O是節能減排中(zhong)應重點關注(zhu)的(de)溫室氣體(ti)。控制污水(shui)(shui)處(chu)理(li)過(guo)(guo)(guo)程(cheng)(cheng)中(zhong)產(chan)生(sheng)(sheng)的(de)CH4有兩種方(fang)式:一(yi)是嚴防其(qi)從污泥厭(yan)氧消化(hua)(hua)(hua)池中(zhong)逃逸,二是在污水(shui)(shui)處(chu)理(li)其(qi)它(ta)單元(yuan)(特別是污泥脫(tuo)水(shui)(shui)和(he)(he)儲泥單元(yuan))及管道中(zhong)避免沉(chen)積物聚積的(de)死角(jiao),也要(yao)注(zhu)意沉(chen)砂(sha)池(需(xu)選用曝氣沉(chen)砂(sha)池或旋流沉(chen)砂(sha)池)有效(xiao)去(qu)除砂(sha)粒(li)表面有機物。對(dui)(dui)N2O控制則比CH4顯(xian)得(de)難度要(yao)大,N2O主(zhu)要(yao)產(chan)生(sheng)(sheng)于硝化(hua)(hua)(hua)和(he)(he)反硝化(hua)(hua)(hua)過(guo)(guo)(guo)程(cheng)(cheng)。目(mu)前,有關N2O形(xing)成(cheng)的(de)機理(li)研究已漸清晰,硝化(hua)(hua)(hua)過(guo)(guo)(guo)程(cheng)(cheng)是N2O形(xing)成(cheng)的(de)主(zhu)因(yin),反硝化(hua)(hua)(hua)過(guo)(guo)(guo)程(cheng)(cheng)對(dui)(dui)N2O形(xing)成(cheng)的(de)作用為次因(yin)。根據N2O產(chan)生(sheng)(sheng)機理(li),提(ti)高硝化(hua)(hua)(hua)過(guo)(guo)(guo)程(cheng)(cheng)DO濃度,增(zeng)加(jia)反硝化(hua)(hua)(hua)過(guo)(guo)(guo)程(cheng)(cheng)有效(xiao)碳源量有助于抑(yi)制N2O形(xing)成(cheng),然而,這(zhe)勢(shi)必會增(zeng)加(jia)CO2排放量。
間接排放(fang)(fang)主要是能(neng)耗(hao)(hao)(hao)(hao)和藥(yao)耗(hao)(hao)(hao)(hao)。由于在污(wu)(wu)水(shui)處(chu)(chu)理廠(chang)運行(xing)中(zhong)最(zui)直(zhi)接反映的(de)(de)(de)是能(neng)耗(hao)(hao)(hao)(hao),而藥(yao)耗(hao)(hao)(hao)(hao)形成(cheng)的(de)(de)(de)碳(tan)(tan)排放(fang)(fang)一般在污(wu)(wu)水(shui)處(chu)(chu)理以外的(de)(de)(de)行(xing)業(ye)(化工(gong)、運輸等)產生(但應計入(ru)污(wu)(wu)水(shui)處(chu)(chu)理碳(tan)(tan)排放(fang)(fang)清單(dan)),故污(wu)(wu)水(shui)處(chu)(chu)理廠(chang)并不關心。圖(tu)1為不同國(guo)家污(wu)(wu)水(shui)處(chu)(chu)理能(neng)耗(hao)(hao)(hao)(hao)以及所對應的(de)(de)(de)碳(tan)(tan)排放(fang)(fang)量(liang)(liang)。不同地區能(neng)耗(hao)(hao)(hao)(hao)差(cha)異較為明顯(xian)(xian),但大(da)(da)數國(guo)家的(de)(de)(de)處(chu)(chu)理能(neng)耗(hao)(hao)(hao)(hao)為0.5~0.6 kW·h·m-3;我國(guo)平(ping)(ping)均處(chu)(chu)理能(neng)耗(hao)(hao)(hao)(hao)0.31 kW·h·m-3(居中(zhong)),巴西(xi)(xi)(xi)和印度處(chu)(chu)理能(neng)耗(hao)(hao)(hao)(hao)僅(jin)為0.22 kW·h·m-3,而丹麥、比利時、薩摩亞(ya)(1.4 kW·h·m-3)等國(guo)家污(wu)(wu)水(shui)處(chu)(chu)理平(ping)(ping)均能(neng)耗(hao)(hao)(hao)(hao)超過1.0 kW·h·m-3。然而,碳(tan)(tan)排放(fang)(fang)量(liang)(liang)結果顯(xian)(xian)示,瑞士、巴西(xi)(xi)(xi)單(dan)位水(shui)處(chu)(chu)理碳(tan)(tan)排量(liang)(liang)最(zui)低,僅(jin)為0.05 kg CO2-eq·m-3,墨西(xi)(xi)(xi)哥(ge)最(zui)高,達0.76 kg CO2-eq·m-3,我國(guo)則(ze)處(chu)(chu)于中(zhong)等水(shui)平(ping)(ping)(平(ping)(ping)均值約0.28 kg CO2-eq·m-3)。高能(neng)耗(hao)(hao)(hao)(hao)一般伴隨著嚴(yan)格的(de)(de)(de)出水(shui)排放(fang)(fang)標(biao)準(zhun)。圖(tu)1表明,上述高能(neng)耗(hao)(hao)(hao)(hao)國(guo)家碳(tan)(tan)排放(fang)(fang)量(liang)(liang)水(shui)平(ping)(ping)卻處(chu)(chu)于與我國(guo)一樣的(de)(de)(de)中(zhong)等水(shui)平(ping)(ping)(≤0.4 kg CO2-eq·m-3)。調研顯(xian)(xian)示,以上國(guo)家的(de)(de)(de)污(wu)(wu)水(shui)處(chu)(chu)理大(da)(da)都利用了(le)污(wu)(wu)泥(ni)厭(yan)氧消化與熱電聯產、甚至余溫熱能(neng)等清潔(jie)能(neng)源(yuan)利用方(fang)式,從而抵消了(le)一部分碳(tan)(tan)排放(fang)(fang)量(liang)(liang)。
藥(yao)(yao)耗碳(tan)排(pai)放(fang)因工藝(yi)本身使用的(de)藥(yao)(yao)劑(ji)所產生(sheng),因此(ci)(ci),應(ying)考慮減少碳(tan)源(yuan)與化學除磷藥(yao)(yao)劑(ji)投加量,以減少此(ci)(ci)類(lei)間(jian)接碳(tan)排(pai)放(fang)。因此(ci)(ci),以減少對碳(tan)源(yuan)和(he)藥(yao)(yao)劑(ji)的(de)依賴(lai)的(de)強化生(sheng)物脫氮(dan)除磷技術將是今(jin)后污(wu)水(shui)處理的(de)主流(liu)。例如(ru),德國(guo)Bochum-Ölbachtal污(wu)水(shui)處理廠(chang)通過對原(yuan)(yuan)有(you)前置反硝化工藝(yi)進行改造,不僅出水(shui)可滿足(zu)嚴格排(pai)放(fang)標準,而(er)且能耗也從原(yuan)(yuan)來的(de)0.47 kW·h·m-3降至0.33 kW·h·m-3。
另外,通(tong)過(guo)模(mo)型軟件對工(gong)藝流程進行優化(hua)(hua),或基于(yu)在線(xian)(xian)數(shu)據實(shi)(shi)(shi)現實(shi)(shi)(shi)時參數(shu)調整也(ye)可(ke)(ke)實(shi)(shi)(shi)現污(wu)水(shui)處理(li)(li)(li)工(gong)藝節(jie)能(neng)降耗(hao)。歐(ou)盟開(kai)發了(le)“ENEWATER”項目(mu),用于(yu)污(wu)水(shui)處理(li)(li)(li)廠(chang)能(neng)量在線(xian)(xian)平衡(heng)分配。該(gai)項目(mu)可(ke)(ke)采用模(mo)糊(hu)邏輯、人工(gong)神(shen)經網絡及(ji)隨機森林等(deng)機器(qi)學習技術,對實(shi)(shi)(shi)際污(wu)水(shui)處理(li)(li)(li)廠(chang)水(shui)泵(beng)、鼓風機等(deng)設備進行優化(hua)(hua),可(ke)(ke)不同程度(du)降低污(wu)水(shui)處理(li)(li)(li)廠(chang)運行能(neng)耗(hao),最高(gao)節(jie)能(neng)可(ke)(ke)達(da)80%。然(ran)而,“零能(neng)耗(hao)”的污(wu)水(shui)處理(li)(li)(li)工(gong)藝是(shi)很難實(shi)(shi)(shi)現的,除非(fei)采用基于(yu)自然(ran)的處理(li)(li)(li)系(xi)統(nature-based solutions,NBS)。因此,僅(jin)僅(jin)靠(kao)節(jie)能(neng)降耗(hao)這種間(jian)接碳減排方式(shi),尚不能(neng)完全實(shi)(shi)(shi)現碳中和(he)運行的目(mu)標。
2)污泥厭氧消化產CH4以實現能源轉化
在我國碳中(zhong)(zhong)和目標(biao)(biao)提出后,剩余污(wu)泥厭氧消(xiao)化重獲關注(zhu)。上述從污(wu)水中(zhong)(zhong)獲取(qu)有(you)(you)機(ji)(COD)能(neng)(neng)源(yuan)來(lai)彌補污(wu)水處理中(zhong)(zhong)能(neng)(neng)耗案例(li)似乎成(cheng)為實現碳中(zhong)(zhong)和目標(biao)(biao)的(de)有(you)(you)效途徑(jing)。然而,污(wu)泥厭氧消(xiao)化所能(neng)(neng)回收的(de)有(you)(you)機(ji)能(neng)(neng)量取(qu)決于進水中(zhong)(zhong)有(you)(you)機(ji)物(wu)濃度(BOD/COD)的(de)多寡(gua)以及厭氧消(xiao)化有(you)(you)機(ji)物(wu)能(neng)(neng)源(yuan)轉化效率,尚不能(neng)(neng)完(wan)全(quan)照搬。
因生活水(shui)平、食物(wu)結構(gou)、無(wu)化(hua)糞池(chi)設置等(deng)原因,歐美等(deng)國家地區(qu)污(wu)水(shui)處(chu)理廠進水(shui)COD普遍(bian)高于(yu)我(wo)國,COD大(da)于(yu)600 mg·L-1的情況非常(chang)普遍(bian)。因此,通過(guo)(guo)初沉(chen)池(chi)以懸浮固體(ti)(suspended solid,SS)形式截留大(da)部分COD,以及剩(sheng)(sheng)余(yu)污(wu)泥(ni)厭(yan)氧(yang)(yang)(yang)共消(xiao)(xiao)化(hua)并(bing)熱(re)電(dian)聯(lian)產(chan)可獲得(de)較高的有機能源(yuan)轉化(hua)率。另外,以上通過(guo)(guo)污(wu)泥(ni)厭(yan)氧(yang)(yang)(yang)消(xiao)(xiao)化(hua)并(bing)熱(re)電(dian)聯(lian)產(chan)實(shi)(shi)現(xian)(xian)(xian)碳(tan)(tan)中(zhong)(zhong)和案(an)例大(da)多還通過(guo)(guo)外源(yuan)有機物(wu)添加(廚余(yu)垃圾或食品廢(fei)物(wu))來增加進水(shui)有機物(wu)的濃度,從而(er)保(bao)證其(qi)實(shi)(shi)現(xian)(xian)(xian)碳(tan)(tan)中(zhong)(zhong)和運行(xing)目標。然而(er),我(wo)國市政污(wu)水(shui)的進水(shui)COD普遍(bian)偏低,COD一般為(wei)100~300 mg·L-1,甚(shen)至(zhi)難(nan)(nan)以滿足基(ji)本脫氮除磷對碳(tan)(tan)源(yuan)的需求,以至(zhi)于(yu)為(wei)保(bao)留碳(tan)(tan)源(yuan)而(er)不(bu)設初沉(chen)池(chi)已成為(wei)主流工藝(yi)設計思路。這(zhe)也使得(de)僅依(yi)靠剩(sheng)(sheng)余(yu)污(wu)泥(ni)厭(yan)氧(yang)(yang)(yang)消(xiao)(xiao)化(hua)轉化(hua)有機能源(yuan)無(wu)法實(shi)(shi)現(xian)(xian)(xian)碳(tan)(tan)中(zhong)(zhong)和運行(xing)目標,即使存(cun)在熱(re)水(shui)解等(deng)手(shou)段(duan)強化(hua)污(wu)泥(ni)厭(yan)氧(yang)(yang)(yang)消(xiao)(xiao)化(hua),在最佳運行(xing)狀(zhuang)況下也難(nan)(nan)突破(po)50%CH4的增產(chan)量(liang)。
表1為幾個污(wu)水處(chu)理廠(chang)污(wu)泥(ni)(ni)有(you)(you)(you)機能源(yuan)回收過程(cheng)中COD平衡數據(ju),展示了污(wu)泥(ni)(ni)厭(yan)氧消化(hua)有(you)(you)(you)機能源(yuan)轉(zhuan)率。數據(ju)表明(ming),進水COD中有(you)(you)(you)機能最終(zhong)只有(you)(you)(you)不到(dao)15%可通過厭(yan)氧消化(hua)與熱電聯產轉(zhuan)化(hua)為電或熱。例(li)如(ru),進水COD為400 mg·L-1(理論(lun)電當(dang)量1.54kW·h·m-3)的(de)市(shi)政(zheng)污(wu)水在完成(cheng)脫氮除磷目(mu)的(de)后所(suo)產生的(de)剩(sheng)余污(wu)泥(ni)(ni)經中溫厭(yan)氧消化(hua)產CH4并熱電聯產,轉(zhuan)化(hua)率僅13%,即實際轉(zhuan)化(hua)電當(dang)量僅為0.20 kW·h·m-3。
3)與污水處理相關的清潔能源工藝
既然(ran)(ran)僅(jin)靠節能(neng)(neng)(neng)降耗和(he)(he)污(wu)泥厭(yan)氧消化(hua)并(bing)熱電(dian)(dian)聯產很難實(shi)現碳(tan)中(zhong)和(he)(he)目(mu)標,那(nei)可(ke)考慮通過吸(xi)收(shou)/捕捉CO2(如,植樹造林)或在污(wu)水(shui)(shui)處(chu)(chu)理(li)(li)工藝或廠(chang)(chang)區使用(yong)(yong)(yong)清潔能(neng)(neng)(neng)源(yuan)(yuan)來達到碳(tan)減(jian)排目(mu)的(de)。因此,傳統意義上(shang)的(de)可(ke)再生能(neng)(neng)(neng)源(yuan)(yuan)成為首要選擇。近年來,微型(xing)(xing)發電(dian)(dian)機、光伏(fu)(fu)能(neng)(neng)(neng)、風能(neng)(neng)(neng)等(deng)新(xin)型(xing)(xing)能(neng)(neng)(neng)源(yuan)(yuan)用(yong)(yong)(yong)于(yu)(yu)英國、土耳其和(he)(he)澳(ao)大利(li)亞等(deng)國的(de)污(wu)水(shui)(shui)處(chu)(chu)理(li)(li)廠(chang)(chang),產生的(de)新(xin)能(neng)(neng)(neng)源(yuan)(yuan)大約可(ke)彌(mi)補(bu)7%~60%的(de)污(wu)水(shui)(shui)處(chu)(chu)理(li)(li)廠(chang)(chang)能(neng)(neng)(neng)耗。POWER等(deng)[30]將微型(xing)(xing)發電(dian)(dian)機技術成功用(yong)(yong)(yong)于(yu)(yu)英國和(he)(he)愛爾蘭等(deng)國的(de)污(wu)水(shui)(shui)處(chu)(chu)理(li)(li)廠(chang)(chang),產生約50%的(de)電(dian)(dian)能(neng)(neng)(neng),用(yong)(yong)(yong)于(yu)(yu)彌(mi)補(bu)廠(chang)(chang)區能(neng)(neng)(neng)耗。澳(ao)大利(li)亞的(de)污(wu)水(shui)(shui)處(chu)(chu)理(li)(li)廠(chang)(chang)充分利(li)用(yong)(yong)(yong)太陽能(neng)(neng)(neng)、風能(neng)(neng)(neng)和(he)(he)污(wu)水(shui)(shui)水(shui)(shui)力(li)發電(dian)(dian)技術,最終產生能(neng)(neng)(neng)源(yuan)(yuan)可(ke)滿足該水(shui)(shui)廠(chang)(chang)69%的(de)運行(xing)能(neng)(neng)(neng)耗。希臘克(ke)里特島某污(wu)水(shui)(shui)處(chu)(chu)理(li)(li)廠(chang)(chang)利(li)用(yong)(yong)(yong)光伏(fu)(fu)發電(dian)(dian)項目(mu)減(jian)排25%、風力(li)發電(dian)(dian)環節減(jian)排25%、人工種植林固(gu)碳(tan)減(jian)排至少(shao)30%,并(bing)輔(fu)以污(wu)泥厭(yan)氧消化(hua)能(neng)(neng)(neng)源(yuan)(yuan)回(hui)收(shou)方(fang)來實(shi)現碳(tan)中(zhong)和(he)(he)目(mu)標。具有(you)可(ke)行(xing)性清潔能(neng)(neng)(neng)源(yuan)(yuan)還有(you)太陽能(neng)(neng)(neng)。然(ran)(ran)而,受(shou)限(xian)于(yu)(yu)污(wu)水(shui)(shui)處(chu)(chu)理(li)(li)廠(chang)(chang)的(de)地理(li)(li)位置、自(zi)然(ran)(ran)環境(光照、風速(su))等(deng)條件,經詳細測算,即使將太陽能(neng)(neng)(neng)光伏(fu)(fu)發電(dian)(dian)板(ban)鋪滿整個污(wu)水(shui)(shui)處(chu)(chu)理(li)(li)廠(chang)(chang)最多(duo)也(ye)只(zhi)能(neng)(neng)(neng)彌(mi)補(bu)約10%~15%的(de)污(wu)水(shui)(shui)處(chu)(chu)理(li)(li)能(neng)(neng)(neng)耗,距(ju)離碳(tan)中(zhong)和(he)(he)目(mu)標仍有(you)差距(ju)。
4)通過余溫熱能利用回收能源的相關技術
污(wu)(wu)水(shui)(shui)(shui)(shui)中(zhong)被(bei)忽視的(de)(de)(de)(de)另外一種潛能(neng)(neng)(neng)(neng)(neng)(neng)——水(shui)(shui)(shui)(shui)熱(re)(re)(re)(余溫(wen)熱(re)(re)(re)能(neng)(neng)(neng)(neng)(neng)(neng))實(shi)際上潛力(li)巨大,可通(tong)過(guo)熱(re)(re)(re)交換(水(shui)(shui)(shui)(shui)源熱(re)(re)(re)泵)方式回(hui)收(shou)(shou)并加(jia)以(yi)利用。污(wu)(wu)水(shui)(shui)(shui)(shui)余熱(re)(re)(re)(<30 ℃)排放(fang)約(yue)占城市總廢熱(re)(re)(re)排放(fang)量(liang)(liang)的(de)(de)(de)(de)40%,且(qie)其(qi)流量(liang)(liang)穩定,具(ju)有(you)冬暖夏涼的(de)(de)(de)(de)特點。熱(re)(re)(re)能(neng)(neng)(neng)(neng)(neng)(neng)衡算表明(ming)(ming),若提取處(chu)(chu)理(li)后(hou)出水(shui)(shui)(shui)(shui)4 ℃溫(wen)差(cha),實(shi)際可產(chan)生(sheng)1.77 kW·h·m-3電當量(liang)(liang)(熱(re)(re)(re))和(he)1.18 kW·h·m-3電當量(liang)(liang)(冷)。這是上述實(shi)際可轉化有(you)機能(neng)(neng)(neng)(neng)(neng)(neng)(0.20kW·h·m-3)的(de)(de)(de)(de)9倍(bei),亦表明(ming)(ming)有(you)機能(neng)(neng)(neng)(neng)(neng)(neng)與熱(re)(re)(re)能(neng)(neng)(neng)(neng)(neng)(neng)分(fen)別為(wei)污(wu)(wu)水(shui)(shui)(shui)(shui)總潛能(neng)(neng)(neng)(neng)(neng)(neng)的(de)(de)(de)(de)10%和(he)90%。因此,污(wu)(wu)水(shui)(shui)(shui)(shui)余溫(wen)熱(re)(re)(re)能(neng)(neng)(neng)(neng)(neng)(neng)蘊含量(liang)(liang)巨大,不(bu)僅能(neng)(neng)(neng)(neng)(neng)(neng)完全(quan)滿(man)足(zu)污(wu)(wu)水(shui)(shui)(shui)(shui)處(chu)(chu)理(li)自(zi)身碳中(zhong)和(he)運行(xing)(案(an)例(li)污(wu)(wu)水(shui)(shui)(shui)(shui)處(chu)(chu)理(li)平均(jun)能(neng)(neng)(neng)(neng)(neng)(neng)耗約(yue)0.37 kW·h·m-3)需(xu)要,而(er)且(qie)還有(you)更多余熱(re)(re)(re)(約(yue)85%)可外輸供熱(re)(re)(re)或自(zi)身使(shi)用(如,用以(yi)進行(xing)污(wu)(wu)泥(ni)低(di)溫(wen)干化),能(neng)(neng)(neng)(neng)(neng)(neng)形(xing)成(cheng)大量(liang)(liang)可進行(xing)碳交易的(de)(de)(de)(de)負碳。污(wu)(wu)水(shui)(shui)(shui)(shui)熱(re)(re)(re)能(neng)(neng)(neng)(neng)(neng)(neng)有(you)效利用可使(shi)污(wu)(wu)水(shui)(shui)(shui)(shui)處(chu)(chu)理(li)廠(chang)(chang)轉變成(cheng)“能(neng)(neng)(neng)(neng)(neng)(neng)源工廠(chang)(chang)”。芬(fen)蘭Kakolanmäki污(wu)(wu)水(shui)(shui)(shui)(shui)處(chu)(chu)理(li)廠(chang)(chang)的(de)(de)(de)(de)案(an)例(li)表明(ming)(ming),該廠(chang)(chang)2020年的(de)(de)(de)(de)總耗能(neng)(neng)(neng)(neng)(neng)(neng)為(wei)21.0 GWh·a-1,通(tong)過(guo)熱(re)(re)(re)能(neng)(neng)(neng)(neng)(neng)(neng)回(hui)收(shou)(shou)等(deng)主要手段(duan)使(shi)能(neng)(neng)(neng)(neng)(neng)(neng)源回(hui)收(shou)(shou)總量(liang)(liang)高(gao)達(da)211.4 GWh·a-1,產(chan)能(neng)(neng)(neng)(neng)(neng)(neng)幾乎為(wei)運行(xing)能(neng)(neng)(neng)(neng)(neng)(neng)耗的(de)(de)(de)(de)10倍(bei)。其(qi)污(wu)(wu)泥(ni)厭氧消(xiao)化產(chan)能(neng)(neng)(neng)(neng)(neng)(neng)僅占3.7%,只能(neng)(neng)(neng)(neng)(neng)(neng)滿(man)足(zu)36.8%的(de)(de)(de)(de)運行(xing)能(neng)(neng)(neng)(neng)(neng)(neng)耗(0.31kW·h·m-3),而(er)余溫(wen)熱(re)(re)(re)能(neng)(neng)(neng)(neng)(neng)(neng)回(hui)收(shou)(shou)占比達(da)95%。
2 各種碳減排策略適用條件對比
現有研(yan)究表(biao)明,污(wu)泥(ni)厭(yan)(yan)(yan)氧(yang)消(xiao)化(hua)有機(ji)能(neng)(neng)(neng)(neng)源(yuan)轉(zhuan)化(hua)率(lv)普(pu)(pu)遍不(bu)高(gao),僅靠(kao)此(ci)路徑很難實(shi)(shi)現碳中和(he)(he)目標(biao),且厭(yan)(yan)(yan)氧(yang)消(xiao)化(hua)至(zhi)少還有50%有機(ji)質需進(jin)行進(jin)一步穩定(ding)處(chu)(chu)(chu)理(li)(li),因(yin)此(ci),在(zai)污(wu)泥(ni)處(chu)(chu)(chu)理(li)(li)中躍過厭(yan)(yan)(yan)氧(yang)消(xiao)化(hua),而直接干化(hua)、焚燒(shao)(shao)(shao)污(wu)泥(ni)應該(gai)是污(wu)泥(ni)處(chu)(chu)(chu)置與(yu)能(neng)(neng)(neng)(neng)源(yuan)回(hui)收(shou)(shou)的上(shang)策(ce),也成為國(guo)內(nei)外普(pu)(pu)遍采(cai)用的方法。前文(wen)提(ti)及的進(jin)水(shui)COD為400 mg·L-1的案例,若采(cai)用直接干化(hua)焚燒(shao)(shao)(shao)工藝來處(chu)(chu)(chu)理(li)(li)污(wu)泥(ni),其有機(ji)能(neng)(neng)(neng)(neng)轉(zhuan)化(hua)率(lv)可(ke)(ke)升(sheng)至(zhi)0.50 kW·h·m-3(電當(dang)(dang)量(liang)),遠遠高(gao)于厭(yan)(yan)(yan)氧(yang)消(xiao)化(hua)的0.20 kW·h·m-3,扣除(chu)(chu)污(wu)水(shui)處(chu)(chu)(chu)理(li)(li)廠(chang)運(yun)(yun)行能(neng)(neng)(neng)(neng)耗(hao)(0.37 kW·h·m-3)后,可(ke)(ke)盈(ying)余電當(dang)(dang)量(liang)0.12 kW·h·m-3。若再(zai)進(jin)一步考慮出(chu)水(shui)熱(re)(re)(re)能(neng)(neng)(neng)(neng)利用,按上(shang)述熱(re)(re)(re)能(neng)(neng)(neng)(neng)實(shi)(shi)際轉(zhuan)化(hua)計(ji)算,水(shui)源(yuan)熱(re)(re)(re)泵提(ti)取4 ℃溫差后,可(ke)(ke)獲(huo)得熱(re)(re)(re)能(neng)(neng)(neng)(neng)1.77 kW·h·m-3(電當(dang)(dang)量(liang)),再(zai)扣除(chu)(chu)污(wu)泥(ni)干化(hua)能(neng)(neng)(neng)(neng)耗(hao)0.61 kW·h·m-3,可(ke)(ke)盈(ying)余熱(re)(re)(re)能(neng)(neng)(neng)(neng)1.16 kW·h·m-3(電當(dang)(dang)量(liang))(見圖2)。因(yin)此(ci),污(wu)泥(ni)焚燒(shao)(shao)(shao)熱(re)(re)(re)能(neng)(neng)(neng)(neng)與(yu)余溫熱(re)(re)(re)能(neng)(neng)(neng)(neng)回(hui)收(shou)(shou)可(ke)(ke)實(shi)(shi)現污(wu)水(shui)處(chu)(chu)(chu)理(li)(li)自(zi)身(shen)能(neng)(neng)(neng)(neng)源(yuan)中和(he)(he)、甚(shen)至(zhi)碳中和(he)(he)運(yun)(yun)行,還可(ke)(ke)使(shi)其變成能(neng)(neng)(neng)(neng)源(yuan)工廠(chang),向(xiang)社會輸(shu)電、供熱(re)(re)(re)。
以上案例表明,污水(shui)(shui)處理(li)僅靠(kao)節(jie)能(neng)(neng)(neng)降耗難(nan)以實(shi)(shi)現碳(tan)中(zhong)和(he),還應通(tong)過開源(yuan)來達到目標。利(li)(li)用(yong)光伏發電(dian)、剩余(yu)污泥化(hua)(hua)學(xue)能(neng)(neng)(neng)厭氧(yang)消化(hua)(hua)回(hui)收(shou)與水(shui)(shui)源(yuan)熱泵余(yu)溫(wen)熱能(neng)(neng)(neng)回(hui)收(shou)方(fang)式(shi),分(fen)別核算3種能(neng)(neng)(neng)量回(hui)收(shou)方(fang)式(shi)對運行(xing)(xing)能(neng)(neng)(neng)耗的(de)(de)貢獻率。結果表明,若進水(shui)(shui)COD為400 mg·L-1,污水(shui)(shui)化(hua)(hua)學(xue)能(neng)(neng)(neng)通(tong)過厭氧(yang)消化(hua)(hua)產CH4并熱電(dian)聯產(CHP)最多僅可(ke)彌(mi)補約(yue)一半的(de)(de)污水(shui)(shui)處理(li)運行(xing)(xing)能(neng)(neng)(neng)耗,剩余(yu)一半能(neng)(neng)(neng)量赤字(zi)仍(reng)需靠(kao)其它途徑來補充。若利(li)(li)用(yong)出水(shui)(shui)余(yu)溫(wen)熱能(neng)(neng)(neng),僅需要<10%熱能(neng)(neng)(neng)或<15%冷能(neng)(neng)(neng)交(jiao)換(通(tong)過碳(tan)交(jiao)易)便可(ke)彌(mi)補能(neng)(neng)(neng)量赤字(zi),間接實(shi)(shi)現碳(tan)中(zhong)和(he)目標。剩余(yu)約(yue)90%熱能(neng)(neng)(neng)或85%冷能(neng)(neng)(neng)則可(ke)用(yong)于(yu)周邊建(jian)筑物空(kong)調(diao)、溫(wen)室(shi)供(gong)暖等,以減少外部的(de)(de)化(hua)(hua)石(shi)能(neng)(neng)(neng)源(yuan)(煤電(dian)、油電(dian))消耗。相比之下,光伏發電(dian)可(ke)獲得(de)(de)的(de)(de)能(neng)(neng)(neng)量則顯(xian)得(de)(de)有些(xie)“微不足道”,最多也就(jiu)能(neng)(neng)(neng)提供(gong)10%~15%的(de)(de)運行(xing)(xing)能(neng)(neng)(neng)耗。因此,污水(shui)(shui)處理(li)廠若考慮余(yu)溫(wen)熱能(neng)(neng)(neng)回(hui)收(shou)不僅可(ke)實(shi)(shi)現碳(tan)中(zhong)和(he)運行(xing)(xing)目標,亦可(ke)向廠外供(gong)熱/冷,從而實(shi)(shi)現向能(neng)(neng)(neng)源(yuan)工廠的(de)(de)轉變(bian)。這(zhe)種認知在(zai)顛覆傳統能(neng)(neng)(neng)量利(li)(li)用(yong)觀念的(de)(de)同時,也揭示了污水(shui)(shui)化(hua)(hua)學(xue)能(neng)(neng)(neng)的(de)(de)利(li)(li)用(yong)局限(xian),表明可(ke)將COD的(de)(de)利(li)(li)用(yong)向高附加值產品(如,藻酸鹽、PHA等)資(zi)源(yuan)化(hua)(hua)方(fang)向轉變(bian),而無需再去刻意強調(diao)污泥厭氧(yang)消化(hua)(hua)產CH4。
余溫(wen)熱(re)(re)(re)(re)能回收(shou)與(yu)應用(yong)并(bing)無技(ji)術障礙,唯一(yi)的(de)(de)利(li)用(yong)設備——水(shui)(shui)源(yuan)熱(re)(re)(re)(re)泵已(yi)較為(wei)成熟。熱(re)(re)(re)(re)能利(li)用(yong)的(de)(de)最大問題是(shi)余溫(wen)熱(re)(re)(re)(re)能乃一(yi)種低品位能源(yuan)(60~80 ℃),只(zhi)適合熱(re)(re)(re)(re)量直接利(li)用(yong),并(bing)不(bu)能用(yong)來發電。當作(zuo)為(wei)熱(re)(re)(re)(re)源(yuan)外輸(shu)冬(dong)季供暖時,較低的(de)(de)水(shui)(shui)溫(wen)又決定了其熱(re)(re)(re)(re)量有效(xiao)輸(shu)送半徑不(bu)能太大,僅適用(yong)于3~5 km的(de)(de)輸(shu)送半徑。而且(qie)在(zai)余溫(wen)熱(re)(re)(re)(re)能實際利(li)用(yong)中,政府部門(men)決策與(yu)規劃最為(wei)重要。個別北(bei)歐(ou)國(guo)家的(de)(de)作(zuo)法值得借鑒,其熱(re)(re)(re)(re)能利(li)用(yong)已(yi)涵(han)蓋建筑(zhu)供暖、溫(wen)室加溫(wen)、人工養魚等多個方面(mian)。例如,瑞典首都斯(si)德哥爾摩建筑(zhu)物(wu)中有40%采用(yong)水(shui)(shui)源(yuan)熱(re)(re)(re)(re)泵技(ji)術供熱(re)(re)(re)(re),其中,10%熱(re)(re)(re)(re)源(yuan)來自污(wu)水(shui)(shui)處(chu)理廠(chang)(chang)出(chu)水(shui)(shui);芬(fen)蘭(lan)(lan)Kakolanmäki污(wu)水(shui)(shui)處(chu)理廠(chang)(chang)對(dui)出(chu)水(shui)(shui)余溫(wen)熱(re)(re)(re)(re)能予以(yi)回收(shou)利(li)用(yong),并(bing)向圖(tu)爾庫市(shi)居(ju)民供熱(re)(re)(re)(re)、制冷,形成了大量負碳(tan);荷蘭(lan)(lan)于2021年在(zai)烏特勒支De Stichtse Rijnlanden污(wu)水(shui)(shui)處(chu)理廠(chang)(chang)建成25 MW水(shui)(shui)源(yuan)熱(re)(re)(re)(re)泵系統,為(wei)周邊(bian)10 000戶(hu)家庭(ting)提供供熱(re)(re)(re)(re)服務。奧地利(li)學者通過全生命周期影響(xiang)評價(life cycle impact assessment, LCIA)方法得出(chu),該國(guo)總共(gong)173個污(wu)水(shui)(shui)處(chu)理廠(chang)(chang)中約(yue)3/4的(de)(de)出(chu)水(shui)(shui)潛熱(re)(re)(re)(re)可被利(li)用(yong),并(bing)在(zai)廠(chang)(chang)區周圍有穩定的(de)(de)熱(re)(re)(re)(re)源(yuan)用(yong)戶(hu)。
盡管對污水(shui)(shui)處(chu)(chu)理(li)(li)廠(chang)(chang)余(yu)(yu)溫(wen)(wen)熱(re)(re)能近距離外(wai)輸利(li)用(yong)(yong)可(ke)大大中和工藝本身能耗,但當(dang)余(yu)(yu)熱(re)(re)難以外(wai)輸時,只能在(zai)污水(shui)(shui)處(chu)(chu)理(li)(li)廠(chang)(chang)內部就地(di)消納,可(ke)考慮將(jiang)余(yu)(yu)溫(wen)(wen)熱(re)(re)能原位用(yong)(yong)于低溫(wen)(wen)干化污泥,然后將(jiang)污泥集中運送至(zhi)具有鄰(lin)避效應的(de)焚燒(shao)廠(chang)(chang)集中焚燒(shao)利(li)用(yong)(yong)。這樣(yang)便可(ke)將(jiang)不能發(fa)電的(de)低品位熱(re)(re)能間接轉化為可(ke)以高(gao)溫(wen)(wen)發(fa)電的(de)高(gao)品位熱(re)(re)能。另外(wai),在(zai)冬季寒冷的(de)北方城市,還可(ke)考慮用(yong)(yong)出水(shui)(shui)余(yu)(yu)溫(wen)(wen)熱(re)(re)能加熱(re)(re)前(qian)端進水(shui)(shui),以確保在(zai)冬季維(wei)持生物處(chu)(chu)理(li)(li)效率。
3 結語
“碳中和”已成為(wei)(wei)熱(re)(re)詞。污(wu)(wu)(wu)水(shui)(shui)(shui)(shui)處(chu)(chu)理(li)(li)廠(chang)(chang)固(gu)然可以(yi)通過節能降(jiang)(jiang)耗、污(wu)(wu)(wu)泥厭氧(yang)消化(hua)、太陽能等方式很大(da)程(cheng)度上(shang)減少碳排放量。但(dan)是,由(you)于(yu)我國(guo)污(wu)(wu)(wu)水(shui)(shui)(shui)(shui)存在(zai)有機質(zhi)含量低的(de)特點,要(yao)通過這(zhe)些常規手段實現碳中和目標(biao)差距(ju)較大(da)。盡(jin)管污(wu)(wu)(wu)水(shui)(shui)(shui)(shui)余溫(wen)熱(re)(re)能的(de)利(li)(li)(li)用是使污(wu)(wu)(wu)水(shui)(shui)(shui)(shui)處(chu)(chu)理(li)(li)廠(chang)(chang)轉型為(wei)(wei)“能源工廠(chang)(chang)”的(de)有效(xiao)手段,但(dan)在(zai)我國(guo)污(wu)(wu)(wu)水(shui)(shui)(shui)(shui)余溫(wen)熱(re)(re)能尚未被(bei)(bei)視為(wei)(wei)清潔能源,更(geng)未被(bei)(bei)列入(ru)(ru)碳交易清單(dan)。因(yin)此,除了在(zai)常規“降(jiang)(jiang)碳”技術上(shang)下功(gong)夫,還應在(zai)管理(li)(li)層面(mian),從(cong)整(zheng)個污(wu)(wu)(wu)水(shui)(shui)(shui)(shui)處(chu)(chu)理(li)(li)領域的(de)整(zheng)體規劃、污(wu)(wu)(wu)水(shui)(shui)(shui)(shui)處(chu)(chu)理(li)(li)廠(chang)(chang)的(de)設(she)計(ji)布局,以(yi)及碳匯政(zheng)策(ce)等多方面(mian)著(zhu)手,來選(xuan)擇適(shi)合我國(guo)國(guo)情的(de)污(wu)(wu)(wu)水(shui)(shui)(shui)(shui)處(chu)(chu)理(li)(li)廠(chang)(chang)碳中和路徑(jing)。慶(qing)幸的(de)是,北京已將污(wu)(wu)(wu)水(shui)(shui)(shui)(shui)余溫(wen)熱(re)(re)能利(li)(li)(li)用列入(ru)(ru)議事日(ri)程(cheng),但(dan)希望余溫(wen)熱(re)(re)能利(li)(li)(li)用能統一規劃而不(bu)是各(ge)自為(wei)(wei)政(zheng),應該(gai)集中于(yu)污(wu)(wu)(wu)水(shui)(shui)(shui)(shui)處(chu)(chu)理(li)(li)廠(chang)(chang)出水(shui)(shui)(shui)(shui),而不(bu)是單(dan)獨(du)樓宇(yu)的(de)原污(wu)(wu)(wu)水(shui)(shui)(shui)(shui)原位利(li)(li)(li)用,因(yin)為(wei)(wei)樓宇(yu)原位利(li)(li)(li)用會降(jiang)(jiang)低流入(ru)(ru)污(wu)(wu)(wu)水(shui)(shui)(shui)(shui)處(chu)(chu)理(li)(li)廠(chang)(chang)污(wu)(wu)(wu)水(shui)(shui)(shui)(shui)溫(wen)度,對北方冬(dong)季污(wu)(wu)(wu)水(shui)(shui)(shui)(shui)處(chu)(chu)理(li)(li)運行極為(wei)(wei)不(bu)利(li)(li)(li)。

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