李欣忱,何澤源,吉芳英,丁世林,毛圓翔,方德新,曾琰婷

剩余污泥微波-淘洗及零價(jià)鐵強(qiáng)化發(fā)酵性能

李欣忱,何澤源,吉芳英*,丁世林,毛圓翔,方德新,曾琰婷

(重慶大學(xué)三峽庫(kù)區(qū)生態(tài)環(huán)境教育部重點(diǎn)實(shí)驗(yàn)室,重慶 400045)

為解決微波預(yù)處理高含固率污泥存在碳源溶出率低和釋放的碳源有效性低的問(wèn)題,本文選用淘洗的方法,同時(shí)將零價(jià)鐵(ZVI)添加到淘洗污泥的混合液和上清液中進(jìn)行厭氧發(fā)酵以強(qiáng)化碳源的有效性.結(jié)果表明,淘洗顯著提升了微波預(yù)處理高含固率(TS=11%~17%)污泥的碳溶出率,水淘和堿淘較未淘洗時(shí)碳源溶出率分別提高了13%~68%、146%~308%.ZVI的加入不僅顯著提高了揮發(fā)性脂肪酸(VFAs)溶出率,還能將大分子碳源定向轉(zhuǎn)化為乙酸、丙酸等低分子碳源.混合液+ZVI、上清液+ZVI發(fā)酵的VFAs溶出量分別為317和354mg/g VSS,超過(guò)微波污泥VFAs溶出量的30倍.添加ZVI發(fā)酵后,丙酸、乙酸、丁酸等小分子碳源的比例有所上升,混合液中的占比分別為34%、26%、18%,上清液中的占比分別為39%、27%、20%,提升了污泥碳源的利用價(jià)值.研究表明,微波-淘洗預(yù)處理聯(lián)合ZVI發(fā)酵技術(shù)能夠有效提高剩余污泥中高效碳源的溶出率,這為剩余污泥的碳源化提供了一條新思路.

微波預(yù)處理；淘洗；高含固率；污泥；零價(jià)鐵；碳源

目前,國(guó)內(nèi)城鎮(zhèn)污水處理廠進(jìn)水碳源普遍不足,為滿足日益嚴(yán)格的出水標(biāo)準(zhǔn),污水廠大多投加外碳源,導(dǎo)致運(yùn)行成本增大、污泥產(chǎn)量增加.剩余污泥本身含有豐富的“碳源”,污泥中碳源的回收利用可以降低污水處理成本.厭氧發(fā)酵是實(shí)現(xiàn)污泥資源化的常用手段之一[1-2].然而,剩余污泥由于有機(jī)物束縛于胞外聚合物以及微生物細(xì)胞中,在其厭氧發(fā)酵初期不易被微生物利用[3-4].因此,通過(guò)預(yù)處理的手段使剩余污泥中有機(jī)物溶解釋放,多年來(lái)一直是該領(lǐng)域的重要研究?jī)?nèi)容.微波具有處理時(shí)間短、升溫快、加熱均勻、節(jié)能高效等特點(diǎn),在污泥預(yù)處理中被廣泛采用[5-7].但現(xiàn)有研究發(fā)現(xiàn),利用熱水解、堿、超聲等污泥破解技術(shù)處理高含固率污泥(TS>7%),隨著污泥固體濃度升高,COD溶解率出現(xiàn)了不同程度的下降,且含固率越高的污泥其粒徑分布曲線中的第二峰越明顯,表明高含固率污泥顆粒在破解過(guò)程中發(fā)生了再凝聚,有機(jī)物包裹或吸附現(xiàn)象嚴(yán)重使得有機(jī)物溶出率降低[8-10].淘洗能將污泥中的固體或固液混合物與液體完全混合,使污泥中的有機(jī)物以及部分有機(jī)顆粒轉(zhuǎn)移到液相中.李秀芳[11]采用機(jī)械攪拌淘洗,實(shí)現(xiàn)了初沉污泥顆粒態(tài)碳源向溶解態(tài)轉(zhuǎn)化,達(dá)到強(qiáng)化污泥碳源釋放的效果.故本文擬采用淘洗的方法促進(jìn)微波預(yù)處理高含固率污泥中的有機(jī)物由固相轉(zhuǎn)移至液相中,以提高污泥中有機(jī)物的有效溶出率.然而,盡管污泥經(jīng)微波-淘洗預(yù)處理后釋放了大量的有機(jī)物,但其中也包含了一些大分子、難降解有機(jī)物,需要進(jìn)一步水解酸化將其轉(zhuǎn)化為易生物降解的小分子有機(jī)物——VFAs. ZVI由于其還原性能有助于為專性厭氧菌創(chuàng)造一個(gè)強(qiáng)化的厭氧環(huán)境,同時(shí),鐵作為微生物代謝中的電子供體,在酸化過(guò)程中能提高一些重要酶的活性[12].近年來(lái),大量研究[13-16]表明ZVI加入污泥厭氧發(fā)酵系統(tǒng)中能顯著提高COD的轉(zhuǎn)化率和甲烷產(chǎn)量,但鮮有以提高碳資源有效性為目的的研究.

本文創(chuàng)新性地將淘洗引入污泥預(yù)處理技術(shù),解決微波預(yù)處理高含固率污泥過(guò)程中所釋放有機(jī)物的再絮凝問(wèn)題,提高碳源溶出率.再結(jié)合污泥厭氧發(fā)酵技術(shù),添加ZVI強(qiáng)化污泥水解酸化,將大分子碳源定向轉(zhuǎn)化為乙酸、丙酸等小分子碳源,增強(qiáng)碳資源有效性.同時(shí),通過(guò)研究ZVI對(duì)污泥厭氧發(fā)酵的影響,及其污泥發(fā)酵液中溶解性COD(SCOD)的變化和VFAs組成特征,為后續(xù)剩余污泥中碳資源的高效利用提供數(shù)據(jù)支持.

1 材料與方法

1.1 污泥的來(lái)源與性質(zhì)

試驗(yàn)所用的剩余活性污泥(WAS)來(lái)自重慶市某污水處理廠,該污水廠污水來(lái)源主要為生活污水,采用奧貝爾氧化溝處理工藝,污泥在使用前于4℃下保存,其性質(zhì)如表1所示.

表1 剩余活性污泥的初始特性

試驗(yàn)所用的厭氧發(fā)酵接種污泥取自重慶某市政污水廠的水解酸化池,該廠為了提高進(jìn)水水質(zhì)的可生化性,在前端設(shè)置了水解酸化池,其主要理化性質(zhì)如表2所示.

表2 厭氧發(fā)酵污泥的理化性質(zhì)

1.2 含固率對(duì)微波預(yù)處理污泥碳溶出效率影響試驗(yàn)

取含水率約為80%的剩余污泥,調(diào)配為污泥含固率為2%~17%的10個(gè)樣品.每一個(gè)濃度分別取3組200g污泥樣品于500mL的燒杯中,在400W的微波功率下加熱5min,溫度達(dá)到100℃,攪拌冷卻至室溫,取微波破解液于50mL離心管中以4500r/min離心5min,測(cè)定上清液的體積和COD濃度.

1.3 淘洗對(duì)微波預(yù)處理高含固率污泥碳溶出效率的影響試驗(yàn)

由1.2的結(jié)果可知,當(dāng)TS>6%時(shí),微波預(yù)處理污泥的碳溶出率急劇下降.為比較淘洗方法對(duì)微波預(yù)處理高含固率污泥(TS=6%~17%)碳溶出性能的影響,分別對(duì)微波預(yù)處理污泥進(jìn)行直接分離(MW)、水淘分離(MW-W)、堿淘分離(MW-A)處理,收集上清液并測(cè)定體積和COD濃度.具體操作方法:

直接分離(MW):取適量微波預(yù)處理污泥于50mL離心管中,以4500r/min離心5min,收集上清液;

水淘分離(MW-W):加入400mL純水于微波預(yù)處理污泥中,200r/min攪拌淘洗30min,離心分離(同上);然后再加入200mL純水于離心沉渣淘洗30min,離心分離(同上),合并2次淘洗上清液;

堿淘分離(MW-A):用0.10mol/L NaOH溶液替換MW-W 中400mL純水作為淘洗液,其余操作過(guò)程同水淘分離.

1.4 ZVI輔助微波-淘洗污泥水解酸化試驗(yàn)

取100g的剩余污泥(TS=13%)經(jīng)過(guò)MW-A預(yù)處理后,得到污泥混合液,離心后得到上清液.分別將污泥混合液和上清液裝入?yún)捬醢l(fā)酵反應(yīng)器中(1L抽濾瓶),接種35%的水解酸化菌,用Na2CO3調(diào)節(jié)堿度,再用HCl調(diào)節(jié)pH值為5.0,設(shè)置2組對(duì)比試驗(yàn),一組添加3g/L的ZVI,一組不添加,將反應(yīng)器放入水浴恒溫振蕩器中,維持恒溫(30±1)℃.每24h取樣,測(cè)定系統(tǒng)中SCOD、VFAs的濃度變化.

1.5 分析方法

按照標(biāo)準(zhǔn)方法測(cè)定TS、VS、NH4+-N、TN、PO43--P和TP[17].TCOD、SCOD采用快速消解分光光度法[18],通過(guò)COD測(cè)定儀(DR1010, HACH, USA)測(cè)定.經(jīng)0.45 μm濾膜過(guò)濾后,采用Dubois法測(cè)定可溶性碳水化合物[19],Lowry- folin法測(cè)定可溶性蛋白[20].VFAs通過(guò)氣相色譜儀(GC9720,浙江富力分析儀器有限公司,中國(guó))和TCD檢測(cè)器(Agilent Technologies 6890N)進(jìn)行組分分析.污泥樣品經(jīng)化學(xué)固定、乙醇脫水、臨界點(diǎn)CO2干燥、鍍金后,使用掃描電鏡(SEM)觀察污泥的微觀結(jié)構(gòu)(JSM-7800F, JEOL, Japan).

1.6 特征參數(shù)

污泥碳溶出率DD(%)的計(jì)算方法如下:

式中:表示上清液COD濃度, mg/L;表示收集到的上清液體積, mL;COD微波污泥表示用于微波熱處理污泥的COD,單位為mg,由表1推導(dǎo)出其值等于微波污泥質(zhì)量×TS(%)×0.885×1000.

1.7 數(shù)據(jù)處理與表達(dá)

試驗(yàn)數(shù)據(jù)處理與分析采用Microsoft Excel 2010進(jìn)行,結(jié)果以平均值和標(biāo)準(zhǔn)差表示,圖形繪制采用OriginPro 2020完成.

2 結(jié)果與討論

2.1 含固率對(duì)微波預(yù)處理剩余污泥碳溶出性能的影響

對(duì)含固率為2%~17%的污泥進(jìn)行微波預(yù)處理,污泥碳溶出率(DD)情況如圖1所示.隨著污泥含固率的增加,污泥碳溶出率先升高后大幅下降,污泥濃度顯著影響污泥的碳溶出率.TS=6%時(shí),碳溶出率最大,為23.5%,相當(dāng)于1g VSS固體污泥碳源能產(chǎn)生365mg液體碳源,在一定范圍內(nèi)隨著TS增大,溶液中污泥含量增加,即污泥溶液中有機(jī)物增多,所能釋放出的有機(jī)物也相應(yīng)增多;但是當(dāng)污泥濃度進(jìn)一步增大時(shí),由于污泥吸附包裹有機(jī)物,導(dǎo)致碳溶出率急劇下降,TS=17%時(shí),碳溶出率只有9%,僅為TS=6%樣品的1/2.污泥含固率過(guò)高時(shí),微波預(yù)處理后產(chǎn)生大量的污泥碎屑,污泥間粘連嚴(yán)重(圖3(b)),導(dǎo)致有機(jī)物難以從固相轉(zhuǎn)移至液相中.

圖1 含固率對(duì)微波預(yù)處理污泥碳溶出率的影響

2.2 淘洗對(duì)微波預(yù)處理高含固率污泥碳溶出性能的影響

針對(duì)高含固率污泥(TS=6%~17%)在微波處理后碳溶出率下降的問(wèn)題,采用淘洗的方式將被包裹吸附的有機(jī)物再次釋放到液相中.將微波預(yù)處理后的污泥(MW)直接離心,與經(jīng)過(guò)水淘洗(MW-W)或堿淘洗(MW-A)后離心進(jìn)行對(duì)比,污泥濃度對(duì)污泥碳溶出效率的影響見(jiàn)圖2.

圖2 淘洗對(duì)微波預(yù)處理高含固率污泥碳溶出率的影響

從圖中可以看出,MW-W的碳溶出率范圍為15%~23.7%,仍在污泥濃度TS=6%時(shí)達(dá)到最大值, DD在高含固率(TS=11%~17%)污泥中較MW有明顯提高,增幅為13%~68%,TS=17%時(shí)DD增幅最大. MW-A的碳溶出率范圍為34.5%~39.2%,較MW、MW-W分別提高了47%~308%和46%~142%,此時(shí)污泥濃度對(duì)污泥碳溶出率的影響不顯著;當(dāng)TS= 13%時(shí),DD達(dá)到最大值(39.2%),相當(dāng)于1g VSS固體污泥碳源能產(chǎn)生609mg液體碳源,較MW、MW-W的最大值提高了65%以上.由試驗(yàn)結(jié)果可知堿液較純水能更進(jìn)一步地促進(jìn)污泥中有機(jī)物大量溶出,這是由于堿性條件能分離EPS中的酸性基團(tuán)(圖3(c)),導(dǎo)致帶負(fù)電的EPS彼此排斥[21-22],增加EPS溶解性.通過(guò)上述分析,本研究認(rèn)為MW-A處理TS=13%的污泥實(shí)現(xiàn)了在此微波條件(400W, 5min)下的碳資源最大化,碳溶出率由未經(jīng)淘洗時(shí)的13.8%提升至39.2%.

圖3 污泥處理前后的表面細(xì)胞結(jié)構(gòu)特征

2.3 ZVI對(duì)剩余污泥厭氧發(fā)酵過(guò)程中SCOD的影響

采用MW-A預(yù)處理后的污泥混合液、上清液進(jìn)行厭氧發(fā)酵,分別與添加ZVI發(fā)酵進(jìn)行對(duì)比.如圖4所示,上清液發(fā)酵過(guò)程中SCOD濃度由3878mg/L持續(xù)下降至2043mg/L,而混合液發(fā)酵SCOD濃度由3890mg/L逐漸升高至4980mg/L后基本保持穩(wěn)定.產(chǎn)生這種差異的原因是由于上清液中缺乏固體碳源溶出的補(bǔ)充,在微生物自身代謝生長(zhǎng)作用下, SCOD不斷被消耗而使?jié)舛认陆?而混合液中含有污泥固體,在水解酸化的作用下,固體有機(jī)物不斷水解為溶解態(tài)有機(jī)物,當(dāng)SCOD的產(chǎn)生速率大于消耗速率時(shí),SCOD濃度持續(xù)升高.添加ZVI后,上清液發(fā)酵中SCOD被消耗的平均速率為126mg/d,混合液發(fā)酵中SCOD的平均增長(zhǎng)速率為303mg/d,均較未添加ZVI時(shí)分別提高了6.4%和49%,這是因?yàn)閆VI的加入對(duì)水解酸化過(guò)程中電子傳遞效率的促進(jìn)作用[23-24].在其他研究中也發(fā)現(xiàn)了類似的效果,Zhen等[25]發(fā)現(xiàn),污泥發(fā)酵12d(20℃),SCOD濃度隨著零價(jià)廢鐵(ZVSI)劑量的增加呈上升趨勢(shì),投加量為0~1g/ g VSS時(shí),SCOD濃度由178mg/g VSS增加到199mg/g VSS;Wu等[26]發(fā)現(xiàn),當(dāng)ZVI應(yīng)用于養(yǎng)殖廢水發(fā)酵系統(tǒng)時(shí),COD濃度較未添加ZVI時(shí)有所下降,ZVI投加量為25mg/L時(shí),COD濃度降低至621mg/ L,COD去除率提高到89.2%,優(yōu)于對(duì)照試驗(yàn)(75.1%和1419mg/L).

由圖4中混合液和混合液+ZVI的曲線可知,厭氧發(fā)酵使微波預(yù)處理污泥中有機(jī)物明顯地溶解釋放,而ZVI投加具有進(jìn)一步促進(jìn)該過(guò)程的作用.在厭氧發(fā)酵初期(第1d),混合液發(fā)酵的污泥碳資源溶出量為521mg SCOD/g VSS,添加ZVI發(fā)酵后提升至533mg SCOD/g VSS;在7d時(shí),混合液發(fā)酵的污泥碳資源溶出量最大,為635mg SCOD/g VSS,較發(fā)酵之初提高了28%,而混合液+ZVI發(fā)酵在6d時(shí)碳資源溶出量就達(dá)到了最大值,為658mg SCOD/g VSS,較發(fā)酵之初提高了33%.這說(shuō)明添加ZVI不僅能提高污泥碳資源溶出量,還能縮短發(fā)酵時(shí)間.Yang等[27]的研究同樣發(fā)現(xiàn),納米零價(jià)鐵(NZVI)投加量為1.68g/L時(shí),僅經(jīng)過(guò)2d發(fā)酵,SCOD濃度由對(duì)照組的645mg/L顯著提升至2125mg/L.

圖4 微波-堿淘洗污泥厭氧發(fā)酵過(guò)程中SCOD變化

2.4 ZVI對(duì)剩余污泥厭氧發(fā)酵過(guò)程中VFAs及其組分的影響

從圖5可知,在9d的反應(yīng)時(shí)間內(nèi),各處理的VFAs濃度都是先增大后減小,上清液發(fā)酵在第3d達(dá)到最大值(2679mg/L),上清液+ZVI發(fā)酵在第2d達(dá)到最大值(2986mg/L),提高了11%;之后VFAs的濃度急速下降,主要是因?yàn)镾COD酸化產(chǎn)生的VFAs在厭氧環(huán)境中被產(chǎn)乙酸菌進(jìn)一步分解為CH4、CO2等[28-29],而上清液中SCOD含量有限,使得溶液中VFAs有減無(wú)增.混合液發(fā)酵在第8d時(shí)VFAs濃度達(dá)到最大值(1860mg/L),混合液+ZVI發(fā)酵在第6d達(dá)到最大值(2643mg/L),提高了42%,有研究表明投加ZVI能顯著提高產(chǎn)酸酶的活性[30],這是ZVI促進(jìn)VFAs產(chǎn)生的原因.在VFAs濃度最大時(shí),混合液+ZVI和上清液+ZVI發(fā)酵的VFAs/SCOD較未添加ZVI時(shí)分別由38%和75%提升至51%和83%,說(shuō)明ZVI能促進(jìn)污泥厭氧發(fā)酵過(guò)程中SCOD向VFAs轉(zhuǎn)化[31],有效提高了污泥碳源的可利用性.邢立群等[32]研究剩余污泥堿性發(fā)酵時(shí),最優(yōu)條件下VFAs/SCOD低于60%; Ahn等[33]采用新型發(fā)酵工藝強(qiáng)化污泥水解酸化,VFAs/SCOD約為62%,均低于本研究中的上清液發(fā)酵.

圖5 微波-堿淘洗污泥厭氧發(fā)酵過(guò)程中VFAs變化

從圖6(a)可知,初始污泥的VFAs溶出量?jī)H為7mg/g VSS,經(jīng)過(guò)微波熱處理后,VFAs溶出量升高至10mg/g VSS,污泥混合液、上清液厭氧發(fā)酵過(guò)程中最大VFAs溶出量為237和337mg/g VSS,添加ZVI發(fā)酵時(shí)最大VFAs溶出量分別提升為317和354mg/g VSS,可見(jiàn)微波預(yù)處理污泥經(jīng)厭氧發(fā)酵后VFAs溶出量有了極顯著的提高,約為發(fā)酵前的24~35倍.

(b)、(c)圖例一致

同種類的VFAs對(duì)生物脫氮除磷效率會(huì)有不同的影響,如果將污泥的水解酸化產(chǎn)物用于外加碳源,那么每種VFAs組分的比例和含量就變得十分重要[34].如圖6(b)、(c)所示,初始污泥中VFAs主要組分的含量比例排序?yàn)?乙酸>戊酸>丙酸,經(jīng)微波熱處理后,VFAs主要組分含量比例排序改變?yōu)?丙酸>戊酸>乙酸,這與牛雨彤等[35]的研究結(jié)果一致,但VFAs 3種主要組分的排序稍有差異.厭氧發(fā)酵后各組試驗(yàn)的VFAs組分比例大小排序均如下:丙酸>乙酸>丁酸>異丁酸>戊酸>異戊酸,其中,丙酸所占比例為32%~39%,乙酸所占比例為25%~27%,丁酸所占比例為17%~20%,三者之和占VFAs的73%~86%.值得注意的是,初始污泥以乙酸主導(dǎo),經(jīng)過(guò)微波熱處理、厭氧發(fā)酵后,以丙酸主導(dǎo),這是因?yàn)樵诒緟捬醢l(fā)酵過(guò)程中, pH值控制在5.0,較低的pH值會(huì)減少甲烷的生成和氫消耗,并進(jìn)一步引起酸化階段產(chǎn)物組成的改變[36],一些產(chǎn)物例如丙酸會(huì)大量生成,而產(chǎn)甲烷菌活性的下降又會(huì)進(jìn)一步加劇有機(jī)酸的累積,且丙酸在熱力學(xué)上不利于轉(zhuǎn)化為乙酸(?0=76.1kJ/mol)[30].同時(shí),Van Den Berg等[37]的研究發(fā)現(xiàn),鐵可提高嗜乙酸產(chǎn)甲烷菌的相對(duì)豐度,從而加快乙酸的消耗,使其比例下降.Chen等[38]的研究指出,乙酸和丙酸更適合作為生物強(qiáng)化除磷的外碳源,以短期除磷效果而言乙酸作碳源效果較好,而從長(zhǎng)期看丙酸效果更優(yōu).牛雨彤等[35]進(jìn)行了ZVI和微波預(yù)處理組合強(qiáng)化污泥厭氧發(fā)酵的試驗(yàn),得到丙酸、乙酸的濃度均低于200mg/L;賈瑞來(lái)等[34]經(jīng)過(guò)微波-H2O2-堿預(yù)處理后進(jìn)行污泥水解,得到的最大乙酸濃度低于200mg/L、最大丙酸濃度低于100mg/L.而本研究中丙酸濃度可達(dá)1165mg/L、乙酸濃度可達(dá)806mg/L,說(shuō)明污泥碳源的利用價(jià)值較高,利于污泥碳源的回用.

3 結(jié)論

3.1 淘洗顯著提高了微波預(yù)處理高含固率污泥的碳溶出率,MW-A處理TS=13%的污泥實(shí)現(xiàn)了在此微波條件(400W, 5min)下的碳資源最大化,DD達(dá)到最大值,為39.2%,較MW、MW-W提高了65%以上.

3.2 零價(jià)鐵不僅提高了污泥混合液發(fā)酵的碳資源溶出量,還縮短了發(fā)酵時(shí)間.SCOD濃度達(dá)到最大值的時(shí)間縮短1d,混合液發(fā)酵中最大碳資源溶出量為658mg SCOD/g VSS,較發(fā)酵之初提高了33%.由于缺乏固體碳源溶出的補(bǔ)充,上清液發(fā)酵的SCOD濃度持續(xù)下降.

3.3 零價(jià)鐵能促進(jìn)污泥厭氧發(fā)酵過(guò)程中SCOD向VFAs轉(zhuǎn)化,有利于提高微波污泥碳源的可利用性.與未添加零價(jià)鐵相比,上清液+ZVI發(fā)酵VFAs濃度為2986mg/L,提高了11%,混合液+ZVI發(fā)酵VFAs濃度為2643mg/L,提高了42%;VFAs/SCOD分別由38%和75%提升至51%和83%.

3.4 在碳源組成方面,零價(jià)鐵發(fā)酵能將液體碳源定向轉(zhuǎn)化為丙酸、乙酸、丁酸這些小分子碳源,其在混合液中的占比分別為34%、26%、18%,離心液中的占比分別為39%、27%、20%,污泥碳源的利用價(jià)值進(jìn)一步被提高.

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Microwave-elutriation pretreatment and zero valent iron enhanced fermentation performance of waste activated sludge.

LI Xin-chen, HE Ze-yuan, JI Fang-ying*, DING Shi-lin, MAO Yuan-xiang, FANG De-xin, ZENG Yan-ting

(Key Laboratory of Three Gorges Reservoir Region’s Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China)., 2021,41(4)：1608~1614

In order to solve the problems of low dissolution rate of carbon source and low availability of released carbon source of waste activated sludge (WAS) with high solid content in microwave pretreatment, the method of elutriation was adopted, and zero valent iron (ZVI) was added to the mixture and supernatant of elutriated sludge for anaerobic fermentation to enhance the availability of carbon source. The results showed that elutriation significantly improved the carbon dissolution rate of microwave-pretreated WAS with high solid content (TS=11%~17%). Compared with non-elutriaton, the dissolution rate of carbon source of elutriating with water and alkali increased by 13%~68% and 146%~308% respectively. The addition of ZVI not only significantly improved the dissolution rate of volatile fatty acids (VFAs), but also transformed macromolecular carbon sources into low molecular carbon sources such as acetic acid and propionic acid.In the mixture, supernatant and ZVI fermentation, the dissolving-out amount of VFAs was 317and 354mg/g VSS respectively, which were 30 times higher thanthat in the microwave-pretreated WAS. After adding ZVI, the proportion of propionic acid, acetic acid and butyric acid respectively increased to 34%, 26% and 18% in the mixture, and 39%, 27% and 20% in the supernatant, which enhanced the utilization value of carbon source in WAS. The research showed that microwave-elutriation pretreatment combined with ZVI anaerobic fermentation technology could effectively improve the dissolution rate of efficient carbon source in WAS, which provided a new idea for the transformation of carbon source in WAS.

microwave pretreatment；elutriation；sludge；high solid content；zero valent iron；carbon source

X703

A

1000-6923(2021)04-1608-07

李欣忱(1996-),女,四川成都人,重慶大學(xué)碩士研究生,主要從事水污染控制研究.發(fā)表論文2篇.

2020-08-12

國(guó)家重點(diǎn)研發(fā)資助項(xiàng)目(2018YFD1100501)

* 責(zé)任作者, 教授, jfy@cqu.edu.cn