李 冬,曹思雨,王 琪,張 杰,2

低表觀氣速間歇曝氣AGS-SBR系統(tǒng)處理實(shí)際生活污水

李 冬1*,曹思雨1,王 琪1,張 杰1,2

(1.北京工業(yè)大學(xué)城市建設(shè)學(xué)部,水質(zhì)科學(xué)與水環(huán)境恢復(fù)工程北京市重點(diǎn)實(shí)驗(yàn)室,北京 100124；2.哈爾濱工業(yè)大學(xué)環(huán)境學(xué)院,城市水資源與水環(huán)境國(guó)家重點(diǎn)實(shí)驗(yàn)室,黑龍江 哈爾濱 150001)

實(shí)驗(yàn)選用3個(gè)SBR反應(yīng)器接種污水廠活性污泥,R1采用高表觀氣速(SGV)連續(xù)曝氣,R2采用低SGV連續(xù)曝氣,R3采用低SGV間歇曝氣,在低碳氮比的實(shí)際生活污水中培養(yǎng)好氧顆粒污泥,探究不同SGV曝氣條件對(duì)好氧顆粒污泥的形成及系統(tǒng)處理效果的影響.經(jīng)過(guò)120d的培養(yǎng),R1?R2和R3中顆粒粒徑分別為(754±78),(812±86),(1183±93)μm,R3的脫氮除磷效果優(yōu)于R1和R2.結(jié)果表明,應(yīng)用低SGV間歇曝氣策略在低碳氮比實(shí)際生活污水中培養(yǎng)的好氧顆粒污泥脫氮除磷性能良好,且系統(tǒng)中反硝化聚磷菌(DPAO)占聚磷菌(PAO)比例為24.75%.

好氧顆粒污泥(AGS)；表觀氣速(SGV)；間歇曝氣；反硝化除磷菌(DPAO)；生活污水；脫氮除磷

好氧顆粒污泥(AGS)因其沉降性能好、生物保留量高及基建占地面積小等優(yōu)點(diǎn),有著廣泛的應(yīng)用前景[1].AGS通常具有直徑大于0.2mm的顆粒結(jié)構(gòu),可以在一個(gè)顆粒內(nèi)保持好氧、缺氧和厭氧的環(huán)境,有利于富集不同種類的功能菌,實(shí)現(xiàn)多種污染物的同步去除[2-3].

我國(guó)城市生活污水COD濃度較低,培養(yǎng)出的好氧顆粒污泥往往結(jié)構(gòu)松散,易發(fā)生崩解[4-7].研究表明[8],在低COD進(jìn)水條件下,選擇性富集聚糖菌(GAO)和聚磷菌(PAO)等功能菌更有助于形成結(jié)構(gòu)光滑?致密和穩(wěn)定的顆粒污泥.反硝化聚磷菌(DPAO)是一種特殊的PAO,能夠在缺氧條件下以NO--N為電子受體,同時(shí)進(jìn)行反硝化和吸磷,實(shí)現(xiàn)“一碳兩用”,為處理低碳氮比生活污水提供了新思路[9].有研究表明,厭氧/缺氧或厭氧/缺氧/好氧交替的環(huán)境有利于DPAO的生長(zhǎng)[10-11].此外,硝酸鹽氮的積累會(huì)對(duì)PAO的吸磷作用產(chǎn)生抑制,影響系統(tǒng)的除磷效率[12-14],而間歇曝氣能夠提供交替好氧/缺氧環(huán)境,可以減少硝酸鹽氮的積累,有利于PAO和DPAO的富集.

同時(shí)在好氧顆粒污泥的培養(yǎng)過(guò)程中,表觀氣速(SGV)通常是一個(gè)比較重要的曝氣參數(shù).以往的研究認(rèn)為,高SGV是培養(yǎng)好氧顆粒污泥的必要因素[15-17],然而,這些研究均使用COD濃度較高的人工配水進(jìn)行實(shí)驗(yàn),但由于我國(guó)城市生活污水具有COD濃度較低的特點(diǎn)[4],并不能完全借鑒以往實(shí)驗(yàn)的經(jīng)驗(yàn). Devlin等[18]在反應(yīng)器SGV為0.41cm/s的條件下,探究不同COD濃度培養(yǎng)好氧顆粒污泥.發(fā)現(xiàn)進(jìn)水COD濃度為340mg/L時(shí)生成了穩(wěn)定密實(shí)的顆粒,而進(jìn)水COD濃度為1300mg/L時(shí)形成的顆粒結(jié)構(gòu)松散,邊緣模糊.

雖然該實(shí)驗(yàn)并未對(duì)所培養(yǎng)好氧顆粒污泥的脫氮除磷效果進(jìn)行詳細(xì)討論,但是能夠說(shuō)明在低COD條件下,高SGV并不是顆粒形成的必要條件.而低SGV的條件可能更適合在低COD進(jìn)水下培養(yǎng)好氧顆粒污泥,并且結(jié)合好氧顆粒污泥的結(jié)構(gòu)特點(diǎn),在單個(gè)顆粒中提供好氧/缺氧/厭氧區(qū)[30],選擇性強(qiáng)化系統(tǒng)對(duì)PAO和DPAO的富集,使培養(yǎng)出的好氧顆粒污泥更適合應(yīng)用于我國(guó)的低碳氮比生活污水,并降低系統(tǒng)能耗.以往研究中[19],培養(yǎng)結(jié)構(gòu)強(qiáng)度高的好氧顆粒污泥大多需要投加金屬離子,若能通過(guò)運(yùn)行方式對(duì)好氧顆粒污泥進(jìn)行強(qiáng)化,也能提升好氧顆粒污泥系統(tǒng)的經(jīng)濟(jì)效益.

基于此,本研究使用3組序批式反應(yīng)器(SBR)進(jìn)行實(shí)驗(yàn),分別應(yīng)用高SGV連續(xù)曝氣?低SGV連續(xù)曝氣和低SGV間歇曝氣這3種曝氣方式,在低碳氮比實(shí)際生活污水中培養(yǎng)好氧顆粒污泥,以此探究不同曝氣策略對(duì)好氧顆粒污泥特性?功能菌富集和污染物去除效率等方面的影響,以期為好氧顆粒污泥工藝處理實(shí)際生活污水提供理論指導(dǎo).

1 材料與方法

1.1 實(shí)驗(yàn)裝置與運(yùn)行方式

使用3組序批式反應(yīng)器R1、R2和R3,反應(yīng)器有效容積6L,換水比為75%.反應(yīng)器采用底部進(jìn)水,通過(guò)PLC(Programmable Logic Controller)控制進(jìn)水?攪拌?曝氣和出水.系統(tǒng)顆?；瓿珊?通過(guò)反應(yīng)器底部排水口手動(dòng)控制排泥,使3個(gè)反應(yīng)器的SRT均為30d.使用鼓風(fēng)機(jī)進(jìn)行底部曝氣,通過(guò)轉(zhuǎn)子流量計(jì)控制曝氣流量.實(shí)驗(yàn)裝置圖如圖1所示.

R1、R2和R3分別應(yīng)用SGV速(1.0cm/s)連續(xù)曝氣、低SGV(0.4cm/s)連續(xù)曝氣和低SGV (0.4cm/s)間歇曝氣進(jìn)行好氧顆粒污泥的培養(yǎng),其中間歇曝氣設(shè)置為每曝氣60min,停曝30min.SGV通過(guò)調(diào)整曝氣強(qiáng)度進(jìn)行調(diào)控,計(jì)算見(jiàn)式(1).

式中:表示SGV,cm/s;表示單位時(shí)間內(nèi)曝氣量, cm3/s;表示反應(yīng)器橫截面面積, cm2.

圖1 反應(yīng)器裝置示意

(1)進(jìn)水箱;(2)蠕動(dòng)泵;(3)出水;(4)氣體流量計(jì);(5)鼓風(fēng)機(jī);(6)進(jìn)水?出水?攪拌?曝氣時(shí)序控制器;(7)攪拌機(jī)

反應(yīng)在室溫條件下進(jìn)行,運(yùn)行過(guò)程中不對(duì)pH值進(jìn)行控制.每周期運(yùn)行時(shí)間為6h.厭氧段前先進(jìn)行5min進(jìn)水,進(jìn)水結(jié)束后進(jìn)入?yún)捬鯏嚢桦A段.初始污泥沉降時(shí)間設(shè)置為30min,之后每4d將沉降時(shí)間減少2min,最終將沉降時(shí)間設(shè)置為4min.3個(gè)反應(yīng)器的具體運(yùn)行參數(shù)如表1所示.

表1 反應(yīng)器運(yùn)行參數(shù)

1.2 接種污泥與實(shí)驗(yàn)用水

反應(yīng)器的接種污泥使用北京市某污水處理廠的二沉池回流污泥,R1?R2和R3的初始MLSS分別為4179,4296,4144mg/L,初始VSS/SS分別為0.63、0.62和0.63.實(shí)驗(yàn)用水為某小區(qū)化糞池的實(shí)際生活污水,污水水質(zhì)如表2所示.

表2 生活污水水質(zhì)(mg/L)

1.3 分析項(xiàng)目及方法

本實(shí)驗(yàn)的NH4+-N、NO2--N、NO3--N、MLSS和SVI等指標(biāo)均采用國(guó)家規(guī)定的標(biāo)準(zhǔn)方法進(jìn)行測(cè)定[20],胞外聚合物(EPS)中的蛋白質(zhì)(PN)采用Lowry法進(jìn)行測(cè)定,多糖(PS)采用蒽酮硫酸法進(jìn)行測(cè)定.使用WTW多參數(shù)測(cè)定儀對(duì)pH值和溶解氧(DO)進(jìn)行測(cè)定.使用Mastersize 2000型激光粒度儀測(cè)定顆粒粒徑,通過(guò)OLYMPUS體式顯微鏡觀察顆粒形態(tài).

其中,EPS的提取步驟如下:

(1)在反應(yīng)器內(nèi)均勻攪拌條件下,由反應(yīng)器側(cè)面取樣口取30mL污泥混合液,在常溫條件下4000倍重力加速度離心15min,之后去除上清液;

(2)使用緩沖液(組成成分:2mmol/L Na3PO4, 4mmol/L; NaH2PO4,9mmol/L; NaCl,1mmol/L KCl)將剩余樣品體積恢復(fù)至30mL,震蕩1min使樣品與緩沖液混合均勻,60℃條件下水浴加熱30min;

(3)樣品冷卻至室溫后,在4℃條件下20000倍重力加速度離心20min,上清液經(jīng)0.22μm濾膜過(guò)濾后得到待測(cè)EPS樣品.

1.4 批次實(shí)驗(yàn)

在實(shí)驗(yàn)運(yùn)行過(guò)程中通過(guò)批次實(shí)驗(yàn)對(duì)系統(tǒng)中DPAO的富集情況進(jìn)行考察.實(shí)驗(yàn)方法如下:從反應(yīng)器中取出2L的泥水混合液,使用自來(lái)水?dāng)嚢枨逑床⑷コ锨逡?重復(fù)3次,之后定容至2L.加入丙酮酸,控制COD濃度為300mg/L,在室溫下厭氧攪拌120min.再次清洗污泥并定容至2L,將污泥平均分為兩份,加入磷酸二氫鉀控制TP濃度為6mg/L,其中一份通過(guò)曝氣進(jìn)行好氧吸磷實(shí)驗(yàn),另一份加入硝酸鉀控制初始硝氮濃度為20mg/L進(jìn)行缺氧吸磷實(shí)驗(yàn).定時(shí)取樣測(cè)定好氧和缺氧實(shí)驗(yàn)的TP濃度.計(jì)算公式如下:

式中:ONn表示能利用O2、NO3-和NO2-作為電子受體去除的磷;ON表示能利用O2和NO3-(不能利用NO2-)作為電子受體去除的磷;O表示只能利用O2作為電子受體去除的磷;O表示利用O2為電子受體在好氧段的吸磷量;ON表示利用NO3-為電子受體在缺氧段的吸磷量;ONn表示利用NO2-為電子受體的吸磷量.

2 結(jié)果與討論

2.1 不同運(yùn)行條件下污泥理化性質(zhì)變化

R1?R2和R3在運(yùn)行過(guò)程中顆粒平均粒徑變化如圖2所示.可以看出在整個(gè)實(shí)驗(yàn)過(guò)程中,3個(gè)反應(yīng)器的平均粒徑均呈現(xiàn)上升趨勢(shì).最終R3中生成的顆粒平均粒徑最大,為(1183±93)μm,R1和R2中顆粒的平均粒徑分別為(754±78)μm和(812±86)μm.

圖2 運(yùn)行期間3個(gè)反應(yīng)器中顆粒平均粒徑的變化

有研究認(rèn)為[21],較高的SGV提供的水力剪切力有利于微生物分泌EPS,從而促進(jìn)顆粒的形成.但是由于本實(shí)驗(yàn)所用進(jìn)水的COD濃度較低,雖然R1采取了較高的SGV進(jìn)行曝氣,但在進(jìn)入好氧段時(shí),由于絲狀細(xì)菌比非絲狀細(xì)菌具有高的比表面積,故能夠更快地從進(jìn)水當(dāng)中吸收營(yíng)養(yǎng)物質(zhì)[22],因此R1中生成的顆粒污泥主要由絲狀菌構(gòu)成,結(jié)構(gòu)較為松散,有研究表明[23],高SGV條件可能導(dǎo)致顆粒磨損性增加,最終導(dǎo)致反應(yīng)器內(nèi)生成的好氧顆粒污泥機(jī)械強(qiáng)度較低,在高SGV條件下粒徑較小.另有研究表明[24],在SGV相同的條件下,不同曝氣裝置產(chǎn)生的氣泡大小不同,也會(huì)對(duì)好氧顆粒污泥的形成產(chǎn)生不同的影響.王陸璽等[25]的研究也表明,曝氣氣泡的分布方式也會(huì)影響好氧顆粒污泥的形成,因此這部分影響因素還有待進(jìn)一步實(shí)驗(yàn)考證.

R3由于采用間歇曝氣的方式運(yùn)行,反應(yīng)器中形成顆粒的粒徑較R1和R2的更大,有研究表明[26],間歇曝氣提供的飽食/饑餓交替的條件有利于促進(jìn)細(xì)胞分泌EPS,進(jìn)而促進(jìn)顆粒的形成.黃健盛等[27]在對(duì)比連續(xù)曝氣與間歇曝氣條件下培養(yǎng)好氧顆粒污泥的實(shí)驗(yàn)中也有相似結(jié)論,在間歇曝氣條件下,顆粒污泥粒徑的增長(zhǎng)速度更快.而R2相較于R3缺少刺激微生物分泌EPS的選擇壓條件,因而在顆粒污泥培養(yǎng)過(guò)程中粒徑增長(zhǎng)較R3更低,且穩(wěn)定運(yùn)行后反應(yīng)器內(nèi)顆粒污泥平均粒徑更小.可見(jiàn)在低C/N生活污水條件下,SGV不再是影響顆粒形成的主要因素,可以通過(guò)其他運(yùn)行參數(shù)促進(jìn)顆粒的培養(yǎng).

由圖3可見(jiàn),實(shí)驗(yàn)初期由于通過(guò)逐步縮短沉降時(shí)間篩選沉降性能好的污泥,3個(gè)反應(yīng)器的MLSS均出現(xiàn)一定程度的下降,隨后呈上升趨勢(shì).當(dāng)系統(tǒng)的SV30/SV5大于0.9時(shí),即可認(rèn)為反應(yīng)器造粒完成[27].因此R1、R2、R3分別在第56,40,36d完成顆粒污泥的培養(yǎng).

圖4 污泥顯微鏡照片

圖4(a)為接種絮狀物泥的顯微鏡照片,圖4(b)～ (d)分別為R1?R2和R3這3個(gè)反應(yīng)器在第100d的顆粒污泥顯微鏡照片.可以看到3個(gè)反應(yīng)器中生成的顆粒污泥均呈現(xiàn)較為不規(guī)則的邊緣,這是由于實(shí)際生活污水中有機(jī)物較為復(fù)雜,降解步驟較多,因而在實(shí)際生活污水中培養(yǎng)的好氧顆粒污泥邊緣較為不規(guī)則,多具有復(fù)雜的微觀結(jié)構(gòu)[29].其中R1中生成的顆粒邊緣絲狀結(jié)構(gòu)較多,且有較多呈不規(guī)則破碎狀的顆粒,R2中生成的顆粒粒徑偏小,R3中生成的顆粒邊緣更加光滑,結(jié)構(gòu)更密實(shí).說(shuō)明在低C/N實(shí)際生活污水條件下,應(yīng)用低SGV間歇曝氣有助于培養(yǎng)結(jié)構(gòu)穩(wěn)定的顆粒污泥.

2.2 不同運(yùn)行條件下系統(tǒng)污染物去除效率變化

由圖5(a)可以看出,剛接種活性污泥的運(yùn)行初期,3個(gè)反應(yīng)器的COD處理效果均不夠理想,之后隨著沉降時(shí)間的縮短,沉降性能較差的污泥隨出水被排出,反應(yīng)器的COD去除效率略有波動(dòng).在隨后的實(shí)驗(yàn)過(guò)程中,3個(gè)反應(yīng)器的COD去除效果均表現(xiàn)良好,出水COD濃度在50mg/L以下,符合《城鎮(zhèn)污水處理廠污染物排放標(biāo)準(zhǔn)》(GB 18918-2002)一級(jí)A的標(biāo)準(zhǔn)[41],最終R1、R2和R3的COD去除率為94.75%、95.69%和97.25%.

圖5(b)為實(shí)驗(yàn)過(guò)程中3個(gè)反應(yīng)器的TN去除效果變化,可以看出R1和R2的TN去除率較R3更低.有研究表明,氧氣在好氧顆粒污泥中的傳質(zhì)深度為150～300μm[30],故當(dāng)顆粒污泥的粒徑小于300μm時(shí),顆粒內(nèi)主要為好氧區(qū).當(dāng)顆粒粒徑繼續(xù)上升時(shí),才能夠提供缺氧區(qū)甚至厭氧區(qū),進(jìn)而通過(guò)反硝化作用獲得較好的脫氮效率.R1由于反應(yīng)器內(nèi)生成顆粒結(jié)構(gòu)疏松,粒徑偏小,且反應(yīng)器曝氣強(qiáng)度較高,導(dǎo)致運(yùn)行過(guò)程中缺乏缺氧條件,不利于系統(tǒng)反硝化,出水中硝態(tài)氮濃度較高.R2由于所用曝氣強(qiáng)度較低,隨著反應(yīng)器內(nèi)顆粒污泥的出現(xiàn),能夠在反應(yīng)器內(nèi)形成一定的缺氧區(qū),故出水TN濃度低于R1.但是由于連續(xù)曝氣,運(yùn)行周期末系統(tǒng)內(nèi)DO濃度升高,對(duì)反硝化菌?DPAO的活性有一定的影響,TN去除率仍低于R3.

圖5(c)為實(shí)驗(yàn)過(guò)程中3個(gè)反應(yīng)器的TP去除效果的變化情況,與TN去除效率的變化情況相似,R1和R2的TP去除率低于R3.由于硝態(tài)氮的積累會(huì)對(duì)PAO吸磷產(chǎn)生影響[12-14],故R1和R2的除磷效果較差可能是由于連續(xù)曝氣條件下,生成的硝態(tài)氮不能及時(shí)去除,對(duì)PAO的除磷效果產(chǎn)生影響.R2較R1所用的SGV更低,系統(tǒng)中包含更多的缺氧區(qū),有利于同步硝化反硝化作用消耗硝態(tài)氮,故與R1相比,R2的脫氮除磷效果更好.

2.3 不同運(yùn)行條件下AGS胞外聚合物含量變化

EPS被認(rèn)為是維持好氧顆粒污泥結(jié)構(gòu)的重要組成部分[31],PN和PS的含量及PN/PS值的變化也可以從一定程度上反映顆粒形成的情況.圖6所示為R1?R2和R3反應(yīng)器在實(shí)驗(yàn)進(jìn)行過(guò)程中EPS含量的變化.可以看出,在顆?；^(guò)程中,3個(gè)反應(yīng)器的EPS含量均較接種時(shí)有所上升.

實(shí)驗(yàn)初期R1的PS含量增長(zhǎng)較快,可能是由于高SGV有利于刺激細(xì)胞分泌EPS[20],但是R1中生成的顆粒結(jié)構(gòu)較為松散,絲狀結(jié)構(gòu)較多,在高SGV條件下并不能保持很好的穩(wěn)定性,顆粒粒徑增長(zhǎng)緩慢,實(shí)驗(yàn)后期EPS總量較R2和R3的更低.研究表明,PS能夠起到粘結(jié)細(xì)胞的作用,進(jìn)而促進(jìn)顆?；?但是過(guò)量的PS也會(huì)使形成的顆粒結(jié)構(gòu)松散,最終因?yàn)槲⑸锏倪^(guò)快生長(zhǎng)導(dǎo)致顆粒破碎[32].He等[33]的研究也發(fā)現(xiàn),系統(tǒng)中PS含量的增加與顆粒的絲狀菌膨脹有關(guān).故雖然高SGV有助于刺激細(xì)胞分泌EPS,但更多的是PS含量的增長(zhǎng),生成的顆粒污泥絲狀菌較多,不利于生成結(jié)構(gòu)密實(shí)的顆粒.R2中的EPS含量在初期呈上升趨勢(shì),但之后略有下降,并在一定范圍內(nèi)波動(dòng),不再上升.R2采用連續(xù)曝氣,導(dǎo)致好氧段饑餓期較長(zhǎng),而饑餓環(huán)境下,EPS可以作為微生物的臨時(shí)碳源被消耗[34],這可能是R2中EPS含量較低的原因.

在實(shí)驗(yàn)過(guò)程中R3的EPS含量較R1和R2的更高,且EPS中PN的增長(zhǎng)更為顯著.Zhang等[35]的研究表明,在污泥顆?；倪^(guò)程中,隨著PN含量的增加,細(xì)胞表面的疏水性也隨之增加,同時(shí)電負(fù)性減小,而這有利于細(xì)胞之間的聚集.McSwain等[36]通過(guò)激光共聚焦技術(shù)(CLSM)對(duì)好氧顆粒內(nèi)部進(jìn)行染色觀察的結(jié)果也表明,PN是顆粒核心的主要構(gòu)成成分,而PS主要聚集在顆粒外層,說(shuō)明了PN在促進(jìn)顆粒污泥穩(wěn)定方面的作用.R3所用的間歇曝氣提供了交替的好氧/缺氧條件,有利于刺激EPS特別是PN的分泌,同時(shí)也有利于富集DPAO等細(xì)菌,使生成的顆粒結(jié)構(gòu)更加密實(shí)穩(wěn)定.因R3的PN增長(zhǎng)較PS更快,故在實(shí)驗(yàn)過(guò)程中系統(tǒng)的PN/PS呈上升趨勢(shì).有研究表明[37],較高的PN/PS值有利于污泥的絮凝,說(shuō)明R3所應(yīng)用的低SGV間歇曝氣策略促進(jìn)了顆粒的形成.

2.4 不同運(yùn)行條件下系統(tǒng)中DPAO比例

實(shí)驗(yàn)通過(guò)批次實(shí)驗(yàn)來(lái)測(cè)定運(yùn)行期間3個(gè)反應(yīng)器內(nèi)DPAO占PAO的比例變化.運(yùn)行期間,R1?R2和R3中DPAO占PAO比例變化情況如圖7所示.由于厭氧/缺氧或厭氧/缺氧/好氧交替的環(huán)境有利于DPAO的生長(zhǎng)[10-11],可以看出,實(shí)驗(yàn)運(yùn)行期間,R3中DPAO占PAO的比例上升最快,最終達(dá)到24.75%.R1和R2由于采用連續(xù)曝氣的運(yùn)行方式,好氧段硝態(tài)氮的積累抑制DPAO的活性,不利于DPAO的富集,最終R1和R2系統(tǒng)中DPAO僅占PAO的11.75%和14.32%.說(shuō)明通過(guò)應(yīng)用低SGV間歇曝氣,可以在低C/N比生活污水中加強(qiáng)對(duì)DPAO的富集,實(shí)現(xiàn)“一碳兩用”,提高系統(tǒng)的脫氮除磷效率.

圖7 運(yùn)行期間DPAO占PAO比例的變化

2.5 不同運(yùn)行條件下典型周期實(shí)驗(yàn)

圖8所示為第110d時(shí)R1、R2和R3一個(gè)周期內(nèi)COD、TP、NH4+-N、NO2--N和NO3--N濃度的變化情況.由于進(jìn)水COD濃度不高,R1、R2和R3中的大部分COD在厭氧段就已被去除,部分難降解COD在好氧段初期被異養(yǎng)菌消耗,最終3個(gè)反應(yīng)器出水COD濃度均小于50mg/L,符合《城鎮(zhèn)污水處理廠污染物排放標(biāo)準(zhǔn)》(GB 18918-2002)一級(jí)A的標(biāo)準(zhǔn)[41].

R1和R2在連續(xù)曝氣條件下,系統(tǒng)提供的DO雖然有利于硝化作用去除NH4+-N,但由于顆粒粒徑較小,在連續(xù)曝氣條件下不能為反硝化作用提供足夠的缺氧?厭氧環(huán)境,可以看到,在運(yùn)行周期中,硝態(tài)氮濃度隨著持續(xù)的曝氣不斷增加,出水中硝態(tài)氮濃度較高,且多為NO3--N,TN去除率較R3更差.又因?yàn)橄鯌B(tài)氮的積累會(huì)對(duì)PAO的吸磷作用產(chǎn)生抑制影響除磷效率[12-14],R1和R2的除磷效果也不夠理想.

R3由于采用低SGV間歇曝氣,運(yùn)行過(guò)程中硝態(tài)氮的積累量并不高,多為NO2--N積累.當(dāng)環(huán)境由缺氧向好氧過(guò)度時(shí),AOB具有能夠快速?gòu)娜毖躔囸I環(huán)境中恢復(fù)的生理特性[38-40],故R3中間歇曝氣帶來(lái)的好氧/缺氧交替使得R3中更多地富集了AOB.且能夠在好氧段后的缺氧段觀察到TP與硝態(tài)氮濃度的同步下降,說(shuō)明有反硝化吸磷現(xiàn)象發(fā)生,使R3能夠獲得較好的脫氮除磷效率.

3 結(jié)論

3.1 低SGV間歇曝氣條件下,以實(shí)際生活污水為進(jìn)水的R3能夠培養(yǎng)出結(jié)構(gòu)密實(shí)的好氧顆粒污泥,且造粒成功后出水能夠滿足《城鎮(zhèn)污水處理廠污染物排放標(biāo)準(zhǔn)》(GB 18918-2002)一級(jí)A的標(biāo)準(zhǔn)[41].

3.2 第120d時(shí)R1?R2和R3的平均粒徑分別為(754±78),(812±86),(1183±93)μm,R3中在低SGV間歇曝氣條件下生成的顆粒表面更光滑?結(jié)構(gòu)更密實(shí).

3.3 低SGV間歇曝氣的運(yùn)行方式有利于選擇性富集DPAO,最終R1、R2和R3中DPAO占PAO的比例分別為11.75%、14.32%和24.75%.

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Low superficial gas velocity intermittent aeration AGS (aerobic granular sludge) SBR system oftreating domestic wastewater.

LI Dong1*, CAO Si-yu1, WANG Qi1, ZHANG Jie1,2

(1.Key Laboratory of Beijing Water Quality Science and Water Environment Recovery Engineering, Faculty of Architecture, Civil and Transportation Engineering, Beijing University of Technology, Beijing 100124, China；2.State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150001, China)., 2021,41(10)：4588～4596

Three SBR reactors were used to inoculate activated sludge from sewage treatment plants in this experiment. R1was used high SGV continuous aeration, R2 was used low SGV continuous aeration, and R3 was used low SGV intermittent aeration to cultivate aerobic granular sludge in actual domestic sewage, and explore the effect of different SGV aeration conditions on the formation of aerobic granular sludge and the effect of system processing. After 120 days of incubation, the particle sizes of R1, R2 and R3 were (754±78)μm, (812±86)μm and (1183±93)μm, respectively. The denitrification and phosphorus removal effect of R3 was better than that of R1 and R2. The results show that the application of low SGV intermittent aeration strategy can realize the cultivation of aerobic granular sludge in actual domestic sewage, and the system had good denitrification and phosphorus removal performance. The proportion of denitrifying phosphorus-removing organisms (DPAO) to phosphorous accumulating organisms (PAO) was 24.75%.

aerobic granular sludge(AGS)；superficial gas velocity (SGV)；intermittent aeration；denitrifying phosphorus-removing organism (DPAO)；domestic；nitrogen and phosphorus removal

X703.1

A

1000-6923(2021)10-4588-09

李 冬(1976-),女,遼寧丹東人,教授,博士,主要研究方向?yàn)樗|(zhì)科學(xué)與水環(huán)境恢復(fù)技術(shù).發(fā)表論文160余篇.

2021-02-23

北京高校卓越青年科學(xué)家計(jì)劃項(xiàng)目(BJJWZYJH0120191 0005019);國(guó)家水體污染控制與治理科技重大專項(xiàng)(2018ZX07601-001)

* 責(zé)任作者, 教授, lidong2006@bjut.edu.cn