朱 淼,袁林江,牛澤棟,周旭紅,賀向峰,鐘冰冰

升流式污泥床對(duì)無機(jī)廢水中氮硫轉(zhuǎn)化及相互影響

朱 淼,袁林江*,牛澤棟,周旭紅,賀向峰,鐘冰冰

(西安建筑科技大學(xué)環(huán)境與市政工程學(xué)院,陜西省環(huán)境工程重點(diǎn)實(shí)驗(yàn)室,西北水資源與環(huán)境生態(tài)教育部重點(diǎn)實(shí)驗(yàn)室,陜西 西安 710055)

采用無機(jī)含氨和硫酸鹽(SO42-)廢水作為升流式污泥床(USB)反應(yīng)器進(jìn)水,研究了其對(duì)銨(NH4+)和SO42-的去除以及不同高度污泥層含氮、硫元素的轉(zhuǎn)化途徑.結(jié)果表明在反應(yīng)器進(jìn)水口處由于進(jìn)水自含氧(外源性氧)和兼性厭氧菌受到氧化應(yīng)激產(chǎn)生過氧化氫(內(nèi)源性氧),兩種“氧”共同存在下,反應(yīng)器內(nèi)生物脫氨量(以氮計(jì))最高達(dá)40mg/L左右,且在USB反應(yīng)器不同高度污泥層含氮化合物和含硫化合物的轉(zhuǎn)化途徑不同.在反應(yīng)器底部污泥層,顆粒污泥表面氨氧化菌利用O2將氨(NH4+)氧化成亞硝酸鹽(NO2-),在顆粒污泥內(nèi)部厭氧氨氧化菌利用 NH4+和NO2-生成氮?dú)?N2)和硝酸鹽(NO3-);同時(shí),O2的存在使得反應(yīng)器底部污泥層部分厭氧顆粒污泥裂解,產(chǎn)生少量有機(jī)物,在顆粒污泥內(nèi)部硫酸鹽還原菌利用有機(jī)物將SO42-還原生成硫離子(S2-);硫自養(yǎng)反硝化菌利用NO2-/ NO3-將S2-重新氧化為SO42-.在反應(yīng)器上部污泥層,由于只有少量內(nèi)源性氧的存在,硫自養(yǎng)反硝化菌只能利用少量NO2-/ NO3-將S2-氧化為硫單質(zhì)(S0);在USB反應(yīng)器底部污泥層實(shí)現(xiàn)NH4+的去除和SO42-的循環(huán),在上部污泥層實(shí)現(xiàn)了SO42-的去除.

升流式污泥床；厭氧氨氧化；硫自養(yǎng)反硝化；脫氮除硫

污水中含氮化合物主要以還原態(tài)氮即有機(jī)氮化合物和NH4+-N的形態(tài)存在[1].在厭氧條件下,有機(jī)氮化合物會(huì)發(fā)生氨化作用轉(zhuǎn)變成NH4+-N[2].因此,如何廉價(jià)高效地去除NH4+-N是污水處理領(lǐng)域研究的熱點(diǎn).近年來,研究者發(fā)現(xiàn)通過構(gòu)造一些特殊環(huán)境或富集一些特殊的細(xì)菌,NH4+-N可以直接在厭氧條件下得以去除,如(亞硝酸鹽型)厭氧氨氧化(ANAMMOX)工藝[3].在工藝中,NH4+-N的去除往往高于理論值[4-5],現(xiàn)有的研究結(jié)果不能完全解釋這一現(xiàn)象.并且含硫化合物通常伴隨著含氮化合物的轉(zhuǎn)化而轉(zhuǎn)化[6-7].與此同時(shí),硫酸鹽型厭氧氨氧化(SRAO)[8-9]和硫自養(yǎng)反硝化[10]等過程的發(fā)現(xiàn)證實(shí)了含硫化合物和含氮化合物的轉(zhuǎn)化過程可能存在一定程度上的耦合[11].目前眾多研究者[12-14]為了減少厭氧氨氧化過程中NO3-的產(chǎn)生,采用向厭氧氨氧化反應(yīng)器中投加S0或S2-的方式,促使反應(yīng)器內(nèi)發(fā)生厭氧氨氧化耦合硫自養(yǎng)反硝化的反應(yīng)達(dá)到降低出水NO3-的目的.此外,袁林杰等[15]和Sabumon[16]分別在無機(jī)條件和有機(jī)條件研究生物脫氮過程時(shí)均檢測到有過氧化氫(H2O2)的產(chǎn)生,細(xì)菌通過產(chǎn)生過氧化氫酶來保護(hù)自己免受H2O2的攻擊,過氧化氫酶能分解H2O2產(chǎn)生O2,產(chǎn)生的O2可用于硝化反應(yīng)[17].有研究者發(fā)現(xiàn)NH4+-N“超量”去除現(xiàn)象發(fā)生在USB反應(yīng)器中[15,18-19].但在USB反應(yīng)器兼性厭氧菌受到氧化應(yīng)激產(chǎn)生H2O2過程是短暫且有限的,為何反應(yīng)器內(nèi)會(huì)出現(xiàn)NH4+-N持續(xù)去除且去除量逐漸增加的現(xiàn)象.不存在供氧條件的USB特殊的運(yùn)行狀態(tài)和模式是否是NH4+-N去除的原因尚不清晰.同時(shí)袁林杰等[15]在USB反應(yīng)器內(nèi)觀察到污泥分層現(xiàn)象,反應(yīng)器底部污泥層處于微氧環(huán)境,反應(yīng)器上部污泥層處于厭氧環(huán)境.USB反應(yīng)器內(nèi)不同高度污泥層O2含量的不同是否會(huì)引起反應(yīng)器內(nèi)菌群結(jié)構(gòu)不同,導(dǎo)致反應(yīng)器內(nèi)氮硫存在多種復(fù)雜生物轉(zhuǎn)化,并未進(jìn)行研究.

因此,本研究采用對(duì)無機(jī)條件下進(jìn)水只投加NH4+-N和SO42-的USB反應(yīng)器, 通過批式實(shí)驗(yàn)考察反應(yīng)器內(nèi)NH4+-N的去除機(jī)制,并通過解析不同高度污泥層的微生物群落、微生物活性以及不同高度污泥層含氮和含硫元素的變化,揭示反應(yīng)器內(nèi)SO42-的循環(huán)和代謝以及SO42-轉(zhuǎn)化與NH4+-N去除過程的耦合.

1 材料與方法

1.1 實(shí)驗(yàn)裝置

采用由有機(jī)玻璃制成的USB反應(yīng)器(圖1),反應(yīng)器內(nèi)徑100mm,高600mm,有效容積4.71L,外側(cè)水浴保溫層厚度20mm,利用加熱水槽和溫控裝置保持溫度為(32±2)℃.在保溫層外包裹鋁箔紙進(jìn)行隔光.反應(yīng)器出水及三相分離器排氣口均進(jìn)行水封處理,減少空氣中溶解氧對(duì)反應(yīng)器運(yùn)行的影響.

1.2 接種污泥

接種污泥為西安市雪花啤酒廠內(nèi)循環(huán)厭氧(IC)反應(yīng)器內(nèi)厭氧顆粒污泥與西安市江村溝垃圾滲濾液處理廠反硝化污泥的混合污泥,接種污泥量分別為3和1.5L,MLSS(懸浮物)為88.25g/L,MLVSS(可揮發(fā)性懸浮物)為47.32g/L,MLVSS/MLSS=0.54.

圖1 實(shí)驗(yàn)裝置示意

1-進(jìn)水桶;2-蠕動(dòng)泵;3-保溫層;4-三相分離器;5-出水;6-液封;a-取樣口1(進(jìn)水口);b-取樣口2;c-取樣口3;d-取樣口4;e-取樣口5;f-取樣口;6(出水口);S-上部污泥層;D-底部污泥層

1.3 實(shí)驗(yàn)用水

采用人工模擬廢水,主要以NH4Cl、Na2SO4按需配制,具體見表1,其他成分含量:NaHCO3800mg/L, KH2PO427mg/L,CaCl2·2H2O 200mg/L,MgCl2·6H2O 250mg/L.在反應(yīng)器運(yùn)行期間保持進(jìn)水pH值為8.0±0.3.

表1 反應(yīng)器內(nèi)進(jìn)水各組分濃度

1.3.1 指標(biāo)測定 NH4+-N、NO2--N、NO3--N、SO42-、S2-等常規(guī)項(xiàng)目的測定參照《水和廢水監(jiān)測分析方法》第四版中的方法[20];pH值采用PHS-3EpH計(jì)測定; DO采用HQ40d型溶氧儀測定;ORP采用ORP儀測定;污泥粒徑采用激光粒度分布儀(LS230/ SVM);H2O2采用鈦-硫酸鈦法[21];污泥的微觀結(jié)構(gòu)采用場發(fā)射掃描電子顯微鏡(Fe-SEM)觀察[22];微生物測序分析由上海生工生物工程公司測序.

1.3.2 活性測定 氨氧化細(xì)菌(AOB)、硝化細(xì)菌(NOB)[23]活性測定:從反應(yīng)器不同污泥層取泥水混合物,用PBS溶液(PBS:0.14g/L KH2PO4和0.75g/L Na2HPO4)清洗3次.稱取3g濕污泥置于150mL的錐形瓶內(nèi),加入含NH4+-N 50mg/L、NO2--N 50mg/L的基質(zhì)至150mL,在34℃水浴中充分曝入空氣(控制錐形瓶內(nèi)DO (7±0.5)mg/L),每間隔2h取樣經(jīng)0.22μm的濾頭過濾后分別測量NH4+-N和NO2--N濃度.由基質(zhì)降解曲線計(jì)算AOB、NOB活性.

厭氧氨氧化(AnAOB)[24]、硫酸鹽還原(SRB)[25]、硫酸鹽型厭氧氨氧化(SRAO)[11]、硫自養(yǎng)反硝化(SADN)菌活性測定[26]:稱取3g濕污泥置于130mL的血清瓶,加入基質(zhì)至130mL.(AnAOB活性測定主要基質(zhì)為NH4+-N 50mg/L、NO2--N 66mg/L,取樣間隔為12h;SRB活性測定主要基質(zhì)為COD 200mg/L、SO42-170mg/L,取樣間隔為6h;SRAO活性測定主要基質(zhì)為NH4+-N 50mg/L、SO42-170mg/L,取樣間隔為12h;硫自養(yǎng)反硝化活性測定主要基質(zhì)為硫磺粉 32mg/L、NO3--N 14mg/L,取樣間隔為6h).以高純氬氣曝氣10min后置于恒溫水浴搖床(34℃、160r/min),取樣經(jīng)0.22 μm的濾頭過濾后測量基質(zhì)的濃度,由基質(zhì)降解曲線計(jì)算活性.

上述活性實(shí)驗(yàn)均設(shè)定3組平行試驗(yàn)同時(shí)進(jìn)行空白試驗(yàn)(瓶內(nèi)不加污泥,只加基質(zhì)).

1.3.3 批次實(shí)驗(yàn) 從反應(yīng)器(第335d)底部取泥水混合物,用PBS洗滌3次.加入適量污泥和反應(yīng)液(主要基質(zhì)為NH4+-N 50mg/L)至130mL血清瓶,以高純氬氣曝氣10min后置于恒溫水浴搖床(34℃、160r/ min),方案見表2.

表2 批次實(shí)驗(yàn)方案

1.3.4 過氧化氫酶活性測定 取反應(yīng)器內(nèi)不同污泥層泥水混合液于離心管,在4000r/min離心5min,倒掉上清液,將離心后的濕污泥稱取2g置于100mL三角瓶中,加入40mL超純水,再加5mL 0.3%的H2O2溶液,隨后在25℃、150r/min的恒溫?fù)u床中振蕩20min,然后將其取出加入1mL飽和鋁鉀礬,立即過濾于盛有5mL 1.5mol/L硫酸的三角瓶中,過濾后的污泥樣品放入烘箱(105℃,2h)烘干,稱重(記為),取25mL濾液,用0.002mol/L高錳酸鉀溶液滴定至紫色,同時(shí)做無土空白實(shí)驗(yàn),設(shè)置3組平行實(shí)驗(yàn)[27].過氧化氫酶活性按下式計(jì)算:

=(-V)×51/0×17/(1)

式中:為過氧化氫酶活性,mg H2O2/(g·min);是0體積空白溶液所消耗的高錳酸鉀體積, mL;是0體積樣品溶液所消耗的高錳酸鉀體積, mL;是高錳酸鉀的濃度, mg/L;是污泥的干重, g.

2 結(jié)果與討論

2.1 反應(yīng)器對(duì)氮硫的脫除

由圖2可知,在USB反應(yīng)器運(yùn)行過程中,NH4+-N有明顯的去除,而SO42-幾乎沒有去除,出水無NO2--N和NO3--N的生成.階段Ⅰ(1～76d)由于在反應(yīng)器剛啟動(dòng)時(shí)接種的厭氧顆粒污泥和反硝化污泥中的異氧微生物及部分無法獲取營養(yǎng)物質(zhì)的微生物不適合現(xiàn)有的生存條件,出現(xiàn)污泥死亡現(xiàn)象,釋放大量的NH4+和有機(jī)物.導(dǎo)致在反應(yīng)器運(yùn)行前12d,出水NH4+-N濃度一直高于進(jìn)水;同時(shí)硫酸鹽還原菌利用污泥死亡釋放的有機(jī)物將SO42-還原,出水SO42-濃度低于進(jìn)水濃度,將反應(yīng)器產(chǎn)氣進(jìn)行氣相色譜分析后發(fā)現(xiàn)含有少量硫化氫(H2S).12d后,階段ⅠNH4+-N的平均去除量在10mg/L左右;隨后進(jìn)出水SO42-濃度變化不大.階段 II (77～106d)NH4+-N的平均去除量仍在10mg/L左右.階段III(107～156d)和階段IV(157～196d),NH4+-N的平均去除量在20mg/L左右.階段V(197～262d),NH4+-N的平均去除量在30mg/L左右;階段VI (263～338d),NH4+-N的平均去除量在40mg/L左右.結(jié)合表1和圖2可知,NH4+-N去除量似乎與NH4+-N進(jìn)水負(fù)荷的變化無關(guān),與進(jìn)水SO42-的濃度也無關(guān).這種NH4+-N獨(dú)立轉(zhuǎn)化現(xiàn)象在很多文獻(xiàn)中也都報(bào)道過[6,15,28-29].

由圖3可知,DO濃度從0.1mg/L提高到0.49mg/ L,ORP從-380mV提高到-166.9mV,NH4+-N的去除量從10mg/L提高到40mg/L.這表明反應(yīng)器不同階段NH4+-N的去除量與DO和ORP有很明顯的聯(lián)系,即DO和ORP的值越高,反應(yīng)器內(nèi)NH4+-N的去除量越高.有文獻(xiàn)報(bào)道[7]厭氧程度越高(ORP和DO越低)氨轉(zhuǎn)化速率越慢,微氧條件下氨轉(zhuǎn)化速率明顯高于缺氧條件下,而厭氧條件下氨無法被轉(zhuǎn)化.由于在反應(yīng)器進(jìn)水未添加亞硝酸鹽、硝酸鹽等氧化態(tài)化合物,故氨氧化的電子受體為O2,USB反應(yīng)器內(nèi)發(fā)生了氨氧化反應(yīng)去除NH4+-N.

圖2 USB對(duì)NH4+-N與SO42-的去除情況

圖3 取樣口2處不同階段ORP、DO與NH4+-N去除量

由圖4可知,pH值的變化主要發(fā)生在取樣口1到取樣口2之間.取樣口1(進(jìn)水口處)pH值為(8.12±0.09),取樣口2處pH值為(7.57±0.059),pH值有明顯的下降,說明在此處發(fā)生了消耗堿度的生化反應(yīng).進(jìn)水NH4+-N濃度為(203.30±5.50)mg/L,經(jīng)過底部污泥層后在取樣口2處測得NH4+-N濃度為(161.05±2.42) mg/L,NH4+- N的平均去除量在42.25mg/L左右,同時(shí)在取樣口2處檢測到(0.69±0.18) mg/L左右NO2--N的生成和(1.46±0.22) mg/L左右NO3--N的生成,NO2--N的存在說明發(fā)生了亞硝化反應(yīng),NO3--N的來源還有待進(jìn)一步證實(shí).取樣口3、4處NH4+-N濃度較取樣口2處變化不大,這主要是因?yàn)榈撞窟M(jìn)水處的DO會(huì)被底部污泥層(ORP= -166.9mV、DO=0.49mg/L)中的AOB菌消耗殆盡,從而為上部污泥層(ORP= -310.8mV、DO=0.14mg/ L)創(chuàng)造一個(gè)厭氧環(huán)境.

如圖5所示,在A0、A1、A2檢測到的AOB菌屬主要是,其相對(duì)豐度分別為0.95%、0.31%、0.15%,它是目前亞硝酸菌中代謝途徑最豐富的菌種,DO 濃度較低時(shí)該菌可能起著厭氧條件下氧化氨的功能[30].如圖6所示,A1、A2中AOB活性分別為 59.98和34.38mg NH4+-N/(gVSS·d).反應(yīng)器底部AOB菌的豐度及活性均高于反應(yīng)器上部,這說明反應(yīng)器內(nèi)氨氧化過程主要發(fā)生在反應(yīng)器的底部.在A0、A1、A2處均未檢測到NOB菌屬,A1、A2處NOB菌的活性極其微弱.這說明反應(yīng)器內(nèi)NO3--N (取樣口2處)并非來自NOB的NO2--N氧化過程.在A0、A1、A2處均檢測到AnAOB菌屬.在反應(yīng)器運(yùn)行穩(wěn)定后,AnAOB菌屬(unclassified)從0.01%增加到了7.70%(底部污泥)和0.38%(上部污泥).說明(取樣口2處)產(chǎn)生的NO3--N來自于厭氧氨氧化過程.

反應(yīng)器內(nèi)底部和上部污泥的粒徑測定結(jié)果表明,底部污泥中粒徑>200μm的占比為51.67%,上部污泥中粒徑>200μm的占比為27.73%.粒徑小于200μm被視為絮狀污泥,粒徑大于200μm 被視為顆粒污泥[31].說明反應(yīng)器底部污泥顆?；潭让黠@.顆粒污泥具有大量的生物群體,對(duì)復(fù)雜的環(huán)境條件具有更強(qiáng)的適應(yīng)性[32-33].

圖4 反應(yīng)器不同高度NH4+-N、NO2--N、NO3--N濃度和pH值

圖5 屬水平物種相對(duì)豐度

圖6 反應(yīng)器不同污泥層污泥活性

本實(shí)驗(yàn)的反應(yīng)器進(jìn)水采用未經(jīng)消氧的自來水配制模擬廢水,在反應(yīng)器底部污泥層低DO環(huán)境中,AOB菌分布于顆粒污泥表面利用O2將NH4+-N氧化為NO2--N,緩解O2對(duì)AnAOB菌的抑制[34]; AnAOB菌存在于顆粒污泥內(nèi)部利用亞硝化生成的NO2--N進(jìn)一步消耗NH4+-N.在AOB菌和AnAOB菌的共同作用下,反應(yīng)器內(nèi)的NH4+-N得到不斷去除.

2.2 反應(yīng)器內(nèi)NH4+-N“超量”去除機(jī)理解析

由圖7可知,第Ⅵ階段過氧化氫酶活性均高于第Ⅴ階段,反應(yīng)器底部污泥過氧化氫酶活性高于上部污泥.與此對(duì)應(yīng),在第Ⅵ階段反應(yīng)器底部(取樣口2)檢測到H2O2濃度最高[(1.58±0.018)mg/L],且第Ⅵ階段H2O2濃度均高于第Ⅴ階段,在反應(yīng)器內(nèi)有污泥存在的區(qū)域都檢測到H2O2的存在.這說明反應(yīng)器NH4+-N去除量增加與反應(yīng)器內(nèi)H2O2的濃度有關(guān).

批次實(shí)驗(yàn)結(jié)果圖8所示,初始每個(gè)血清瓶中NH4+-N濃度均為50mg/L左右,前24h NH4+-N濃度基本都沒有變化,說明在絕對(duì)厭氧只含NH4+-N的體系內(nèi),NH4+-N不會(huì)發(fā)生轉(zhuǎn)化.24h后向血清瓶2中注入O2和血清瓶3中注入H2O2后發(fā)現(xiàn)NH4+-N濃度都有所降低,說明NH4+-N的去除與系統(tǒng)內(nèi)存在的O2和過氧化氫酶分解H2O2產(chǎn)生O2有關(guān).當(dāng)O2或H2O2添加后,血清瓶2中NH4+-N濃度減少了11.45mg/L,血清瓶3中NH4+-N濃度減少了7.49mg/ L,血清瓶4中NH4+-N濃度減少了24.42mg/L.血清瓶4中NH4+-N的減少量多于血清瓶2和血清瓶3中NH4+-N減少量之和.這說明H2O2的出現(xiàn)不僅會(huì)產(chǎn)生一定的O2,在內(nèi)源性和外源性的O2共同存在的條件下會(huì)促進(jìn)系統(tǒng)內(nèi)產(chǎn)生更多的O2,反應(yīng)器內(nèi)NH4+-N的去除量也不斷增加.

圖8 添加O2和H2O2對(duì)NH4+的去除

2.3 反應(yīng)器內(nèi)SO42-代謝機(jī)理

由圖9可知,進(jìn)水SO42-濃度為(677.40± 11.11)mg/L,經(jīng)過底部污泥層后在取樣口2處測得SO42-濃度為(701.53±14.43) mg/L,這可能與反應(yīng)器進(jìn)水桶未進(jìn)行除氧,進(jìn)水中攜帶少量的溶解氧(進(jìn)水DO約8mg/L)導(dǎo)致不斷有DO進(jìn)入和產(chǎn)生導(dǎo)致底部厭氧微生物死亡釋放有機(jī)碳(TOC)和SO42-有關(guān).經(jīng)過上部污泥層,取樣口4處SO42-的濃度為(681.03± 16.55) mg/L,SO42-的平均去除量約20.50mg/L,然而反應(yīng)器進(jìn)出水SO42-濃度變化不大.由圖5可知在A1、A2中檢測到的SRB菌屬unclassifiedunclassified、可以利用有機(jī)物將SO42-還原為S2-.在無機(jī)條件運(yùn)行的反應(yīng)器中檢測到SRB菌,這可能是因?yàn)榉磻?yīng)器底部厭氧微生物受DO影響,不斷衰亡釋放有機(jī)物.同時(shí)受水力沖擊影響,污泥上浮裂解釋放有機(jī)物,導(dǎo)致反應(yīng)器上部也存在少量的SRB菌.在反應(yīng)器運(yùn)行的300～330d,反應(yīng)器內(nèi)TOC濃度在3mg/L左右.圖10b表明,污泥發(fā)生了細(xì)胞自溶現(xiàn)象[35].同時(shí)在A1、A2中檢測到大量的菌屬,種泥A0中菌屬的豐度為0.01%,A1中的豐度為17.06%,A2中的豐度為 13.27%.菌屬是最為廣泛報(bào)道的SADN菌屬,它具有將脫氮與硫化合物氧化耦合的能力,可利用還原態(tài)硫素與NO3--N、NO2--N反應(yīng)生成N2[36].由圖6可知A1中SRB菌活性為5.6mg SO42-/ (gVSS·d),SADN菌活性為9.16mg NO3--N/(gVSS·d); A2中SRB菌活性為6.6mg SO42-/(gVSS·d), SADN菌活性為6.33m mg NO3--N/(gVSS·d).在反應(yīng)器內(nèi)取樣口3處檢測到S2-的生成,但在出水處未檢測到S2-.說明在反應(yīng)器內(nèi)發(fā)生了硫酸鹽還原和硫自養(yǎng)反硝化反應(yīng).

圖9 反應(yīng)器不同取樣口SO42-、S2-濃度變化

a、b:第 Ⅵ 階段反應(yīng)器上部、底部污泥SEM圖;c:污泥硫元素含量

由圖10a、c可知, 在反應(yīng)器上部污泥中發(fā)現(xiàn)了S0的產(chǎn)生,S元素所占質(zhì)量百分比從1.11%增加到2.22%.而反應(yīng)器底部污泥中S元素所占質(zhì)量百分比基本沒有出現(xiàn)變化.有文獻(xiàn)報(bào)道硫化物的氧化通常分為兩個(gè)步驟進(jìn)行[37]:首先,硫化物被氧化成中間產(chǎn)物S0;在NO3--N足夠的情況下,S0會(huì)進(jìn)一步被氧化成SO42-.研究證明,S0被氧化成SO42-的速度要比硫化物被氧化成S0的速度慢很多,利用S0的反硝化速率比利用硫化物時(shí)要低一個(gè)數(shù)量級(jí)[38].這說明了在反應(yīng)器底部出現(xiàn)了SO42-“循環(huán)過程”,在反應(yīng)器上部出現(xiàn)了SO42-的去除.

2.4 反應(yīng)器內(nèi)N、S代謝的耦合作用

由圖5和圖6可知未檢測到SRAO菌屬及其活性,說明反應(yīng)器內(nèi)沒有發(fā)生SRAO反應(yīng).

如圖11所示,反應(yīng)器底部由于進(jìn)水自含外源性O(shè)2和兼性厭氧菌受到氧化應(yīng)激產(chǎn)生H2O2而生成的內(nèi)源性O(shè)2,兩者共同存在的條件下會(huì)產(chǎn)生更多的O2,導(dǎo)致反應(yīng)器內(nèi)NH4+的去除量不斷增加.同時(shí)O2在反應(yīng)器底部污泥層被AOB菌消耗,從而為上部污泥層創(chuàng)造一個(gè)厭氧環(huán)境(ORP= -310.8mV、DO=0.14mg/ L),USB反應(yīng)器不同高度污泥層中由于O2含量不同,導(dǎo)致在污泥床不同高度含氮化合物和含硫化合物的轉(zhuǎn)化途徑不同.在反應(yīng)器底部污泥層,由于有內(nèi)源性O(shè)2和外源性O(shè)2的存在,在顆粒污泥表面氨氧化菌利用O2將NH4+氧化成NO2-,在顆粒污泥內(nèi)部厭氧氨氧化菌利用NH4+和NO2-生成N2和NO3-;同時(shí),O2的存在使得反應(yīng)器底部污泥層部分厭氧顆粒污泥裂解,產(chǎn)生少量SO42-和有機(jī)物,在顆粒污泥內(nèi)部硫酸鹽還原菌利用有機(jī)物將SO42-還原生成S2-;硫自養(yǎng)反硝化菌利用NO2-/NO3-將S2-重新氧化為SO42-.在反應(yīng)器上部污泥層,由于只有少量H2O2產(chǎn)生的內(nèi)源性O(shè)2的存在,少量NH4+被氧化為NO2-,AnAOB菌生成少量NO3-,SRB菌利用細(xì)胞死亡釋放的有機(jī)物將SO42-還原為S2-,硫自養(yǎng)反硝化菌只能利用生成的少量NO2-/NO3-將S2-氧化為S0.并用Fe-SEM觀察到S0的生成,反應(yīng)器運(yùn)行的第255～335d上部污泥中硫元素的含量從1.11%增加到2.22%.在USB反應(yīng)器底部污泥層實(shí)現(xiàn)NH4+的去除和SO42-的循環(huán),在上部污泥層實(shí)現(xiàn)SO42-的去除.

圖11 反應(yīng)器內(nèi)NH4+去除途徑及SO42-變化

3 結(jié)論

3.1 隨著運(yùn)行時(shí)間延長,USB反應(yīng)器對(duì)無機(jī)廢水中NH4+-N的去除量不斷增加,而對(duì)SO42-的去除量卻不變化.

3.2 反應(yīng)器內(nèi)NH4+-N的去除與反應(yīng)器內(nèi)隨進(jìn)水帶入的微量氧及微生物代謝過程中H2O2的產(chǎn)生有關(guān),DO濃度在反應(yīng)器進(jìn)水口處不斷升高,NH4+-N的去除量逐漸增加,最高可達(dá)到40mg/L左右.

3.3 USB反應(yīng)器內(nèi)不同高度污泥層O2含量的不同導(dǎo)致不同高度污泥層的微生物菌群以及活性不同,反應(yīng)器內(nèi)N、S代謝是分層進(jìn)行.TN的去除主要發(fā)生在反應(yīng)器底部污泥層通過氨氧化、厭氧氨氧化、硫自養(yǎng)反硝化途徑.SO42-的去除主要發(fā)生在反應(yīng)器上部污泥層,硫酸鹽還原菌以有機(jī)物為電子供體將SO42-還原為S2-,然后硫自養(yǎng)反硝化菌利用少量NO2--N/NO3--N將S2-氧化為S0,實(shí)現(xiàn)S0的積累和SO42-的去除.

[1] Vlaeminck S E, Terada A, Smets B F, et al. Nitrogen removal from digested black water by one-stage partial nitritation and anammox [J]. Environmental Science & Technology, 2009,43(13):5035-5041.

[2] Zehr J P, Ward B B. Nitrogen cycling in the ocean: New perspectives on processes and paradigms [J]. Applied and Environmental Microbiology, 2002,68(3):1015-1024.

[3] Van der Star W R L, Abma W R, Blommers D, et al. Startup of reactors for anoxic ammonium oxidation: experiences from the first full scale anammox reactor in Rotterdam [J]. Water Research, 2007, 41(18):4149-4163.

[4] Udert K M, Kind E, Teunissen M, et al. Effect of heterotrophic growth on nitritation/anammox in a single sequencing batch reactor [J]. Water Science and Technology, 2008,58(2):277-284.

[5] Yu J J, Jin R C. The ANAMMOX reactor under transient-state conditions: process stability with fluctuations of the nitrogen concentration, inflow rate, pH and sodium chloride addition [J]. Bioresource Technology, 2012,119:166-173.

[6] Liu S, Yang F, Zheng G, et al. Application of anaerobic ammonium- oxidizing consortium to achieve completely autotrophic ammonium and sulfate removal [J]. Bioresource Technology, 2008,99(15):6817-6825.

[7] 畢 貞,董石語,黃 勇.ANAMMOX培養(yǎng)物中硫酸鹽型氨氧化生物轉(zhuǎn)化機(jī)制[J]. 環(huán)境科學(xué), 2021,42(3):1477-1487.

Bi Z, Dong S Y, Huang Y. Biological Conversion Mechanism of Sulfate Reduction Ammonium Oxidation in ANAMMOX Consortia [J]. Environmental Science, 2021,42(3):1477-1487.

[8] Fdz-Polanco F, Fdz-Polanco M, Fernandez N, et al. New process for simultaneous removal of nitrogen and sulphur under anaerobic conditions [J]. Water Research, 2001,35(4):1111-1114.

[9] Fdz-Polanco F, Fdz-Polanco M, Fernandez N, et al. Simultaneous organic nitrogen and sulfate removal in an anaerobic GAC fluidised bed reactor [J]. Water Science and Technology, 2001,44(4):15-22.

[10] 于振國.自養(yǎng)脫硫反硝化反應(yīng)器微生物群落動(dòng)態(tài)及功能菌群分析[D]. 哈爾濱:哈爾濱工業(yè)大學(xué), 2007.

Yu Z G. The analysises of microbial community dynamics and functional groups in autotrophic denitrifying sulfide removal reactor [D]. Harbin: Harbin Institution of Technology, 2007.

[11] 王 洋.厭氧氨氧化污泥EPS功能解析及對(duì)氮,硫的耦合轉(zhuǎn)化研究[D]. 西安:西安建筑科技大學(xué), 2019.

Wang Y. Study on the oxidation of ammonium coupling with sulfur transformation and the function of EPS of anammox sludge [D]. Xi'an: Xi'an University of Architecture and Technology, 2019.

[12] Chen F, Li X, Yuan Y, et al. An efficient way to enhance the total nitrogen removal efficiency of the Anammox process by S0-based short-cut autotrophic denitrification [J]. Journal of Environmental Sciences, 2019,81:214-224.

[13] 周 健,黃 勇,劉 忻,等.硫自養(yǎng)反硝化耦合厭氧氨氧化脫氮條件控制研究[J]. 環(huán)境科學(xué), 2016,37(3):1061-1069.

Zhou J, Huang Y, Liu X, et al. Element Sulfur Autotrophic Denitrification Combined Anaerobic Ammonia Oxidation [J]. Environmental Science, 2016,37(3):1061-1069.

[14] Fajardo C, Mosquera-Corral A, Campos J L, et al. Autotrophic denitrification with sulphide in a sequencing batch reactor [J]. Journal of Environmental Management, 2012,113:552-556.

[15] 袁林杰,袁林江,陳 希,等.厭氧氨氧化UASB系統(tǒng)對(duì)氨氮的超量去除機(jī)制研究[J]. 中國環(huán)境科學(xué), 2021,41(10):4686-4694.

Yuan L J, Yuan L J, Chen X, et al. Mechanism of excessive removal of ammonia nitrogen by anammox UASB system [J]. China Environmental Science, 2021,41(10):4686-4694.

[16] Sabumon P C. Anaerobic ammonia removal in presence of organic matter: a novel route [J]. Journal of Hazardous Materials, 2007,149(1):49-59.

[17] Fu H, Yuan J, Gao H. Microbial oxidative stress response: novel insights from environmental facultative anaerobic bacteria [J]. Archives of Biochemistry and Biophysics, 2015,584:28-35.

[18] 于麗萍,王 茹,袁林江,等.Anammox的硫酸鹽利用特性及脫氮性能[J]. 中國給水排水, 2021,37(15):1-7.

Yu L P, Wang R, Yuan L J, et al. Sulfate Utilization Characteristics and Denitrification Performance of Anammox Process [J]. China Water and Wastewater, 2021,37(15):1-7.

[19] 牛晚霞,袁林江,有小龍,等.進(jìn)水亞硝氮限制下Anammox去除氨氮研究[J]. 中國環(huán)境科學(xué), 2021,41(7):3212-3220.

Niu W X, Yuan L J, You X L, et al. Study on removal of ammonia nitrogen by Anammox with or free of nitrite nitrogen [J]. China Environmental Science, 2021,41(7):3212-3220.

[20] 國家環(huán)境保護(hù)總局.水和廢水監(jiān)測分析方法 [M]. 北京:中國環(huán)境科學(xué)出版社, 2004.

State Environmental Protection Administration. Water and wastewater monitoring and analysis methods [M]. Beijing: China Environmental Science Press, 2004.

[21] Knowles R K H R . Production of nitrous oxide by Nitrosomonas europaea: Effects of acetylene, pH, and oxygen [J]. Canadian Journal of Microbiology, 1984,30(11):1397-1404.

[22] 王彬斌.顆粒態(tài)有機(jī)物及胞外聚合物對(duì)活性污泥結(jié)構(gòu)和特性影響研究 [D]. 西安:西安建筑科技大學(xué), 2014.

Wang B B. Effects of particulate organic matter and extracellular polymeric substances (EPS) on the structure and characteristics of activated sludge [D]. Xi'an: Xi'an University of Architecture and Technology, 2014.

[23] 趙良杰,彭黨聰,呂 愷,等.一段式部分亞硝化-厭氧氨氧化工藝處理中低濃度模擬氨氮廢水[J]. 環(huán)境工程學(xué)報(bào), 2021,15(1):143-151.

Zhao L J, Peng D C, Lv K, et al. Treatment of simulated medium and low-strength ammonia wastewater by single-stage partial nitritation- anammox process [J]. Chinese Journal of Environmental Engineering, 2021,15(1):143-151.

[24] 鄭照明,楊函青,馬 靜,等.SNAD反應(yīng)器中顆粒污泥和絮體污泥脫氮特性[J]. 中國環(huán)境科學(xué), 2015,35(10):2996-3002.

Zheng Z M, Yang H Q, Ma J, et al. The nitrogen removal performance of granules and flocs in SNAD reactor [J]. China Environmental Science, 2015,35(10):2996-3002.

[25] 王 輝,戴友芝,劉 川,等.混合硫酸鹽還原菌代謝過程的影響因素[J]. 環(huán)境工程學(xué)報(bào), 2012,6(6):1795-1800.

Wang H, Dai Y Z, Liu C, et al. Influencing factors on metabolism process of mixed sulfate-reducing bacteria [J]. Chinese Journal of Environmental Engineering, 2012,6(6):1795-1800.

[26] 馬瀟然,鄭照明,卞 偉,等.硫自養(yǎng)反硝化系統(tǒng)運(yùn)行效能和微生物群落結(jié)構(gòu)研究[J]. 中國環(huán)境科學(xué), 2020,40(10):4335-4341.

Ma X R, Zheng Z M, Bian W, et al. Study on operation efficiency and microbial community structure of sulfur-based autotrophic denitrification system [J]. China Environmental Science, 2020,40(10): 4335-4341.

[27] 楊蘭芳,曾 巧,李海波,等.紫外分光光度法測定土壤過氧化氫酶活性[J]. 土壤通報(bào), 2011,42(1):207-210.

Yang L F, Zeng Q, Li H B, et al. Measurement of catalase activity in soil by ultraviolet spectrophotometry [J]. Chinese Journal of Soil Science, 2011,42(1):207-210.

[28] 賴楊嵐,周少奇.硫酸鹽型厭氧氨氧化反應(yīng)器的啟動(dòng)特征分析[J]. 中國給水排水, 2010,26(15):41-44.

Lai Y L, Zhou S Q. Start-up characteristics of sulfate-dependent anaerobic ammonium oxidation reactor [J]. China Water and Wastewater, 2010,26(15):41-44.

[29] Prachakittikul P, Wantawin C, Noophan P, et al. ANAMMOX-like performances for nitrogen removal from ammonium-sulfate-rich wastewater in an anaerobic sequencing batch reactor [J]. Journal of Environmental Science and Health, Part A, 2016,51(3):220-228.

[30] Koops H P, Stehr G. Classification of eight new species of ammonia-oxidizing bacteria: Nitrosomonas communis sp. nov., Nitrosomonas ureae sp. nov., Nitrosomonas aestuarii sp. nov., Nitrosomonas marina sp. nov., Nitrosomonas nitrosa sp. nov., Nitrosomonas eutropha sp. nov., Nitrosomonas oligotropha sp. nov. and Nitrosomonas halophila sp. nov [J]. Microbiology, 1991,137(7): 1689-1699.

[31] Miao Y , Peng Y , Liang Z , et al. Partial nitrification-anammox (PNA) treating sewage with intermittent aeration mode: Effect of influent C/N ratios [J]. Chemical Engineering Journal, 2018,334:664-672.

[32] Lu H, Zheng P, Ji Q, et al. The structure, density and settlability of anammox granular sludge in high-rate reactors [J]. Bioresource Technology, 2012,123:312-317.

[33] 許冬冬,康 達(dá),郭磊艷,等.厭氧氨氧化顆粒污泥研究進(jìn)展[J]. 微生物學(xué)通報(bào), 2019,46(8):1653-1665.

Xu D D, Kang D, Guo L Y, et al. Research progress on Anammox granular sludge [J]. Microbiology China, 2019,46(8):1653-1665.

[34] Cho S, Fujii N, Lee T, et al. Development of a simultaneous partial nitrification and anaerobic ammonia oxidation process in a single reactor [J]. Bioresource Technology, 2011,102(2):652-659.

[35] Cao S, Du R, Li B, et al. High-throughput profiling of microbial community structures in an ANAMMOX-UASB reactor treating high-strength wastewater [J]. Applied Microbiology and Biotechnology, 2016,100(14):6457-6467.

[36] Kelly D P, Wood A P. Confirmation of Thiobacillus denitrificans as a species of the genus Thiobacillus, in the beta-subclass of the Proteobacteria, with strain NCIMB 9548as the type strain [J]. International Journal of Systematic and Evolutionary Microbiology, 2000,50(2):547-550.

[37] Xu G, Yin F, Chen S, et al. Mathematical modeling of autotrophic denitrification (AD) process with sulphide as electron donor [J]. Water Research, 2016,91:225-234.

[38] Liu Y , Lai P , Ngo H H , et al. Evaluation of nitrous oxide emission from sulfide and sulfur-based autotrophic denitrification processes. [J]. Environmental Science & Technology, 2016,50(17):9407.

Mechanisms of biological conversion and removal of nitrogen and sulfur from the inorganic influent in Upflow Sludge Bed Reactor.

ZHU Miao, YUAN Lin-jiang*, NIU Ze-dong, ZHOU Xu-hong, HE Xiang-feng, ZHONG Bing-bing

(Key Laboratory of Environmental Engineering of Shaanxi Province, Key Laboratory of Northwest Water Resources and Environmental Ecology, Ministry of Education, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China)., 2022,42(9)：4174～4182

The inorganic wastewater containing ammonium and sulfate was used as influent of upflow sludge bed (USB) reactor, and the removal of ammonium and sulfate and the transformation of nitrogen and sulfur elements in the sludge layers with different heights were studied. The results show that at the inlet of the reactor, the influent water contained dissolved oxygen (exogenous oxygen) and facultative anaerobes subjected to oxidative stress to produce hydrogen peroxide (endogenous oxygen). In the coexistence of two kinds of "oxygen", the biological deamination amount (calculated as nitrogen) in the reactor was up to about 40mg/L, and the conversion pathways of nitrogen-containing compounds and sulfur-containing compounds in the sludge layer varied with the position (height) of the USB reactor. In the sludge layer at the bottom of the reactor, ammonia oxidizing bacteria on the surface of granular sludge used molecule oxygen to oxidize ammonium to nitrite, and anaerobic ammonia oxidizing bacteria inside the granular sludge used ammonium and nitrite to generate nitrogen gas and nitrate; at the same time, the presence of oxygen made the anaerobic granular sludge in the sludge layer at the bottom of the reactor be cracked and produced a small amount of organic matter; the sulfate-reducing bacteria in the granular sludge use organic matter to reduce sulfateto form sulfide ion; and sulfur autotrophic denitrifying bacteria utilize nitrite/nitrate to re-oxidize sulfide to sulfate. In the upper sludge layer of the reactor, due to the existence of only a small amount of endogenous oxygen, the sulfur autotrophic denitrifying bacteria could only use a small amount of nitrite/nitrateto oxidize sulfide to sulfur element. The removal of ammonium and the circulation of sulfatewere realized in the sludge layer at the bottom of the USB reactor, and the removal of sulfatewas achieved in the upper sludge layer.

upflow sludge bed；anammox；sulfur autotrophic denitrification；nitrogen and sulfur removal

X703

A

1000-6923(2022)09-4174-09

2022-02-09

國家自然科學(xué)基金資助項(xiàng)目(51878538)

*責(zé)任作者, 教授, yuanlinjiang@xauat.edu.cn

朱 淼(1997-),女,陜西西安人,西安建筑科技大學(xué)碩士研究生,主要從事城市污水處理理論與技術(shù).