張洛紅,李芮瑩,曹 敏,成晶晶,王勛濤,翟迎博,熊 鑫

印染廢水活性污泥代謝狀態(tài)光偏轉(zhuǎn)快速檢測(cè)法

張洛紅*,李芮瑩,曹 敏,成晶晶,王勛濤,翟迎博,熊 鑫

(西安工程大學(xué)環(huán)境科學(xué)與工程系,陜西 西安 710600)

針對(duì)現(xiàn)有活性污泥檢測(cè)方法過(guò)程繁瑣、耗時(shí)長(zhǎng)、檢測(cè)結(jié)果滯后的局限,提出了光偏轉(zhuǎn)快速檢測(cè)法.在污泥負(fù)荷為0.33KgCOD/(kg MLSS×d)、水力停留時(shí)間為15h的印染廢水完全混合式活性污泥系統(tǒng)中,投放粒徑4mm、具有20μm微孔結(jié)構(gòu)的聚乙烯醇(PVA)凝膠小球以負(fù)載微生物,并在小球達(dá)到穩(wěn)定狀態(tài)后,對(duì)其表面處因外界溶液與微生物代謝產(chǎn)物交換產(chǎn)生的濃度梯度變化,借助光斑分析儀進(jìn)行光偏轉(zhuǎn)檢測(cè),同時(shí)測(cè)定與光偏轉(zhuǎn)檢測(cè)結(jié)果相對(duì)應(yīng)的15h后的出水COD及COD去除率.連續(xù)10個(gè)月的檢測(cè)發(fā)現(xiàn),小球中富集的主要為細(xì)菌,當(dāng)進(jìn)水COD由91.95mg/L增至519.4mg/L時(shí),小球的光偏轉(zhuǎn)值從229.51μm增加至299.97μm,COD去除率從16.03%提高至66.99%;當(dāng)DO濃度為1.5mg/L～5mg/L時(shí),小球光偏轉(zhuǎn)值在DO=4mg/L時(shí)增至最大為309.3mg/L,對(duì)應(yīng)狀態(tài)下COD去除率增至最大為61.18%;在pH值為6～9時(shí),小球光偏轉(zhuǎn)值在pH=7時(shí)增至最大為293.96μm,對(duì)應(yīng)狀態(tài)下COD去除率也達(dá)到最大值為64.83%;當(dāng)重金屬Cr3+濃度增至50mg/L時(shí),微生物活性逐漸受到抑制,小球光偏轉(zhuǎn)值在Cr3+濃度為20mg/L時(shí)降至269.7μm,隨后隨著Cr3+濃度的增加,微生物細(xì)胞受損,胞內(nèi)物質(zhì)溶出,小球光偏轉(zhuǎn)值有所增大,對(duì)應(yīng)狀態(tài)下COD去除率從52.5%持續(xù)降低至25.73%.結(jié)果表明:該方法可快速獲得活性污泥代謝狀態(tài)變化信息,且依據(jù)特定條件下小球光偏轉(zhuǎn)值變化能夠預(yù)測(cè)隨后印染廢水COD的去除效果.利用三維熒光光譜初步探究了微生物代謝引發(fā)光偏轉(zhuǎn)的機(jī)理,發(fā)現(xiàn)參與微生物代謝的主要有機(jī)物為酪氨酸、芳香類蛋白及色氨酸.

光偏轉(zhuǎn)快速檢測(cè)法；活性污泥法；微生物代謝狀態(tài)；聚乙烯醇(PVA)凝膠小球；COD去除率

印染廢水屬難處理的工業(yè)廢水之一,其有效處理是行業(yè)可持續(xù)健康發(fā)展的關(guān)鍵[1].活性污泥法對(duì)印染廢水中的有機(jī)物及顯色基團(tuán)有較好的處理效果[2-3],但該方法處理印染廢水所需周期較長(zhǎng),且印染廢水水質(zhì)水量、溫度、有毒有害物質(zhì)等變化較大,會(huì)影響活性污泥代謝活性[4-6],因而需要對(duì)活性污泥中微生物的生長(zhǎng)代謝狀態(tài)進(jìn)行快速檢測(cè),以保證印染廢水活性污泥處理系統(tǒng)的出水水質(zhì).

現(xiàn)有傳統(tǒng)的活性污泥檢測(cè)方法如30min污泥沉降比(SV30)法、混合液揮發(fā)性懸浮物濃度(MLVSS)法、污泥容積指數(shù)(SVI)法等,可隨時(shí)觀察活性污泥的絮凝、沉降性能[7],且可與污泥負(fù)荷、溶解氧(DO)濃度及活性污泥中總絮凝體體積引起的氧轉(zhuǎn)移消耗獲得很好的相關(guān)性,常用以判斷并指導(dǎo)污水處理系統(tǒng)的運(yùn)行[8-9];隨后引進(jìn)的微生物檢測(cè)方法如三磷酸腺苷(ATP)法、脫氫酶活性(DHA)法、比耗氧速率(SOUR)法等,可有效反映微生物的活性狀態(tài),與溶解氧濃度、氧化還原電位(OPR)及pH有較好的相關(guān)性[10-11];顯微鏡技術(shù)在細(xì)菌生物的檢測(cè)中具有操作簡(jiǎn)便、分辨率高等諸多優(yōu)點(diǎn)[12];近些年來(lái),采用其他檢測(cè)方法及模型模擬來(lái)反映污泥性質(zhì),為污水處理工藝運(yùn)行提供數(shù)據(jù)依據(jù)的研究也很活躍[13-16].

當(dāng)印染廢水活性污泥處理系統(tǒng)運(yùn)行異常甚至崩潰時(shí),則需要較長(zhǎng)時(shí)間恢復(fù),而目前采用的方法雖然有諸多優(yōu)點(diǎn),但普遍存在檢測(cè)過(guò)程繁瑣、耗時(shí)長(zhǎng)、檢測(cè)結(jié)果滯后等局限,從而導(dǎo)致污泥性質(zhì)檢測(cè)數(shù)據(jù)不能快速反映出污泥代謝狀態(tài).因此探究一種快速檢測(cè)活性污泥性質(zhì)的方法顯得尤為重要[17].

本研究向?qū)嶒?yàn)室印染廢水活性污泥完全混合式曝氣池中投放聚乙烯醇(PVA)凝膠小球,用來(lái)負(fù)載活性污泥微生物,采用光偏轉(zhuǎn)快速檢測(cè)法對(duì)PVA凝膠小球中微生物代謝狀態(tài)進(jìn)行快速檢測(cè),探究進(jìn)水化學(xué)需氧量(COD)、pH值、DO濃度、重金屬Cr3+濃度對(duì)PVA小球光偏轉(zhuǎn)檢測(cè)結(jié)果的影響,并分析COD去除率與PVA凝膠小球光偏轉(zhuǎn)檢測(cè)結(jié)果的相關(guān)關(guān)系,以探究光偏轉(zhuǎn)快速檢測(cè)法的可行性.同時(shí)通過(guò)三維熒光光譜,探究活性污泥體系中參與微生物代謝及引發(fā)光偏轉(zhuǎn)的主要有機(jī)物.

1 材料與方法

1.1 實(shí)驗(yàn)用水、接種污泥與PVA凝膠小球

1.1.1 實(shí)驗(yàn)用水 印染廢水采集于陜西省咸陽(yáng)際華新三零印染有限公司污水處理廠,廢水初始COD為1300mg/L,按實(shí)驗(yàn)需要,將其稀釋后泵入印染廢水活性污泥完全混合式曝氣池.

1.1.2 接種污泥 實(shí)驗(yàn)污泥取自上述污水處理廠回流污泥,接種到實(shí)驗(yàn)室印染廢水活性污泥處理系統(tǒng)內(nèi),MLSS約為2165.4mg/L,SV30約為33%.經(jīng)實(shí)驗(yàn)室處理裝置馴化15d,系統(tǒng)達(dá)到穩(wěn)定狀態(tài).

1.1.3 PVA凝膠小球 研究中的PVA凝膠小球(日本Kuraray公司)為新型微生物固定化載體,其直徑為4mm,密度為1.025g/cm3,內(nèi)部及表面均具有20μm的多孔微結(jié)構(gòu).

1.2 實(shí)驗(yàn)內(nèi)容

1.2.1 活性污泥處理系統(tǒng) 采用活性污泥完全混合式曝氣池探究進(jìn)水COD、pH值、DO濃度、重金屬Cr3+濃度對(duì)小球光偏轉(zhuǎn)檢測(cè)結(jié)果及印染廢水COD去除率的影響,實(shí)驗(yàn)從春季持續(xù)到秋季共10個(gè)月.

圖1 污水處理示意

1.印染廢水;2.曝氣池;3.曝氣;4.PVA凝膠小球容器;5.沉淀池;6.出水;7.污泥回流;8.剩余污泥

如圖1所示,將PVA凝膠小球置于容器壁光滑且多孔(孔隙直徑為3mm)的圓柱體容器中,PVA凝膠小球投加量與盛放其的容器體積比為1:10,并將PVA凝膠小球容器放置在印染廢水活性污泥完全混合式曝氣池內(nèi)部以負(fù)載微生物,用空氣壓縮機(jī)(廣東日生集團(tuán)有限公司)進(jìn)行曝氣,處理后的印染廢水經(jīng)過(guò)沉淀池靜置沉淀后出水.具體運(yùn)行參數(shù)為:處理印染廢水水量為31.97L/d、污泥負(fù)荷為0.33KgCOD/ (kg MLSS?d)、水力停留時(shí)間為15h、回流比為100%.

1.2.2 光偏轉(zhuǎn)檢測(cè)裝置 光偏轉(zhuǎn)檢測(cè)裝置由三維精密位儀光學(xué)平臺(tái)(WNOIHB型,中國(guó)孚光精儀有限公司)、穩(wěn)頻He-Ne激光器(美國(guó)Melles Griot公司)、衰減片(透過(guò)率分別為50%和10%,北京卓立漢光儀器有限公司)及光斑分析儀(包括SPOU20CCD相機(jī);Beam Gage軟件,美國(guó)Ophir-Spiricon公司)組成.

1.2.3 PVA凝膠小球的光偏轉(zhuǎn)檢測(cè)及系統(tǒng)出水COD測(cè)定 取曝氣池的污泥混合液在4000r/min下離心30s,離心后所得上清液轉(zhuǎn)移至平底玻璃容器中,并取出1個(gè)在完全混合式曝氣池內(nèi)富集了微生物并達(dá)到穩(wěn)定狀態(tài)的PVA凝膠小球,將其放入存有上清液的平底玻璃容器中(上清液剛好完全淹沒(méi)小球),隨后借助光偏轉(zhuǎn)檢測(cè)裝置對(duì)小球進(jìn)行光偏轉(zhuǎn)檢測(cè).待檢測(cè)完第1個(gè)小球,重新取離心后所得的上清液,在相同的操作步驟下檢測(cè)第2個(gè)小球,每次檢測(cè)小球個(gè)數(shù)36,計(jì)算其光偏轉(zhuǎn)值平均值及標(biāo)準(zhǔn)偏差(SD).從開(kāi)始離心至所有小球光偏轉(zhuǎn)檢測(cè)結(jié)束,每次檢測(cè)時(shí)間在3min之內(nèi).

同時(shí)在檢測(cè)PVA小球光偏轉(zhuǎn)值15h后,檢測(cè)印染廢水活性污泥處理系統(tǒng)出水COD,并計(jì)算COD去除率.

1.3 檢測(cè)方法

1.3.1 基本檢測(cè)指標(biāo)

表1 基本指標(biāo)測(cè)定方法

1.3.2 光偏轉(zhuǎn)檢測(cè)方法 如圖2所示,激光器發(fā)出的激光先經(jīng)過(guò)擴(kuò)束器以擴(kuò)展激光束直徑并減小激光束發(fā)散角,再通過(guò)光學(xué)衰減片后經(jīng)45°反射鏡進(jìn)行垂直反射,最后通過(guò)顯微鏡鏡頭進(jìn)行聚焦,在實(shí)際檢測(cè)中,光學(xué)設(shè)備一次性調(diào)試好后不再移動(dòng),只需旋轉(zhuǎn)微型位儀臺(tái)X-Y軸,使聚焦后的激光接近PVA凝膠小球邊緣并逐漸與之相切,形成的光斑圖像經(jīng)SPOU20CCD相機(jī)采集后轉(zhuǎn)換為模擬信號(hào)傳送給計(jì)算機(jī)Spiricon Beam Gage操作軟件.

1.3.3 掃描電子顯微鏡(SEM) 采用SEM掃描PVA凝膠小球的內(nèi)部及表面,觀察空白PVA凝膠小球表面、內(nèi)部結(jié)構(gòu)以及富集微生物后的PVA凝膠小球表面、內(nèi)部微生物生長(zhǎng)繁殖狀態(tài).小球預(yù)處理方法為:將空白及富集了微生物的PVA凝膠小球經(jīng)冷凍干燥機(jī)干燥24h,定型且去除水分后進(jìn)行噴金.

圖2 光偏轉(zhuǎn)距離測(cè)量示意

1.計(jì)算機(jī)Beam Gage操作軟件;2.CCD相機(jī);3.X;Y載物臺(tái),PVA凝膠小球;4.目鏡;5.物鏡;6反射鏡;7.衰減片;8.固定架;9.激光擴(kuò)束器;10.激光器電源;11.光學(xué)平臺(tái)

1.3.4 三維熒光光譜法 采用三維熒光光譜對(duì)印染廢水中有機(jī)物組份及經(jīng)活性污泥法處理后的印染廢水中有機(jī)物組份進(jìn)行對(duì)比分析.三維熒光光譜的測(cè)定采用日本日立公司生產(chǎn)的三維熒光光譜儀,型號(hào)為F-4500型,參數(shù)設(shè)置為:激發(fā)波長(zhǎng)ex:250～ 550nm,發(fā)射波長(zhǎng)em:200～400nm,激發(fā)掃描步長(zhǎng): 5nm,掃描速度:12000nm/min,測(cè)定結(jié)果以熒光強(qiáng)度及三維熒光光譜圖來(lái)表示.

2 結(jié)果與討論

2.1 PVA凝膠小球外觀變化與微生物富集情況

2.1.1 PVA凝膠小球外觀變化 如圖3所示,未富集微生物的空白PVA凝膠小球顏色為白色;而在印染廢水活性污泥完全混合式曝氣池中,經(jīng)過(guò)1個(gè)月的運(yùn)行,PVA凝膠小球狀態(tài)達(dá)到穩(wěn)定,外觀顏色加深,說(shuō)明小球中富集了一定量的微生物[18-19].

圖3 PVA凝膠小球外觀形貌

2.1.2 PVA凝膠小球微生物富集情況 為進(jìn)一步分析PVA凝膠小球表面和內(nèi)部微生物的生長(zhǎng)繁殖狀態(tài),采用SEM對(duì)PVA凝膠小球進(jìn)行觀察,結(jié)果如圖4所示.

圖4 PVA凝膠小球微生物富集SEM圖

如圖4(a)所示,PVA凝膠小球內(nèi)部及表面均具有20μm的多孔微結(jié)構(gòu).

如圖4(b)所示,PVA凝膠小球表面富集了大量細(xì)菌.實(shí)驗(yàn)中,將PVA凝膠小球容器固定在曝氣頭上部,使得容器內(nèi)密度為1.025g/cm3的小球在氣體與水流的作用下處于持續(xù)流動(dòng)狀態(tài),且小球投加量為容器體積的10%,合適的體積比及較好的懸浮狀態(tài),使得小球彼此之間相互摩擦,從而避免多余污泥絮體及原生動(dòng)物、后生動(dòng)物的附著,以減少對(duì)光偏轉(zhuǎn)檢測(cè)結(jié)果的影響.

如圖4(c)所示,PVA凝膠小球內(nèi)部也富集了大量細(xì)菌.這表明小球中細(xì)菌富集量高,各種細(xì)菌從PVA凝膠小球表面逐漸富集到內(nèi)部[20-21].而在活性污泥生物處理過(guò)程中,對(duì)活性污泥微生物的檢測(cè)很大程度體現(xiàn)在對(duì)細(xì)菌的檢測(cè)上[22-24],而PVA凝膠小球?qū)?xì)菌的有效富集,有利于光偏轉(zhuǎn)檢測(cè)法對(duì)活性污泥代謝狀態(tài)的快速檢測(cè),更有利于提高光偏轉(zhuǎn)檢測(cè)法對(duì)于活性污泥代謝狀態(tài)檢測(cè)結(jié)果的有效性.

2.2 光偏轉(zhuǎn)檢測(cè)可行性研究

理論上認(rèn)為,PVA凝膠小球作為一個(gè)相對(duì)獨(dú)立的整體,其中富集的細(xì)菌群體在代謝過(guò)程中,產(chǎn)生的代謝產(chǎn)物會(huì)與外界溶液之間相互交換,從而在小球邊緣產(chǎn)生一定的濃度梯度變化,當(dāng)激光經(jīng)過(guò)這一濃度梯度時(shí),會(huì)發(fā)生偏折,而當(dāng)激光無(wú)限接近小球表面時(shí),因?yàn)樾∏虮砻娴臐舛忍荻茸兓畲?此時(shí)引起的光斑偏移程度也最大[25].

本研究選擇型號(hào)為Melles Griot 05-STP910- 230的穩(wěn)頻氦氖激光器,其光束直徑為0.48mm,波長(zhǎng)為632.8nm,輸出功率為0.6～1.4mW,發(fā)散角為1.7mrad,屬低能量級(jí)激光,經(jīng)過(guò)衰減片后能量進(jìn)一步減弱,對(duì)生物無(wú)危害,且光斑大小合適,可用于光偏轉(zhuǎn)快速檢測(cè)[17].

實(shí)際檢測(cè)發(fā)現(xiàn),激光在遠(yuǎn)離小球時(shí),由SPOU20CCD相機(jī)采集并傳送給計(jì)算機(jī)的光束信號(hào),在Spiricon Beam Gage操作軟件中經(jīng)預(yù)處理后,呈現(xiàn)出與入射的激光光束截面大小和形狀完全相同的光斑圖像,如圖5(a)所示,此時(shí)光偏轉(zhuǎn)距離為零;旋轉(zhuǎn)微型位儀臺(tái)X-Y軸,因PVA凝膠小球邊緣存在的濃度梯度變化,入射激光在Beam Gage操作軟件呈現(xiàn)的光斑圖像會(huì)發(fā)生偏折,如圖5(b)所示,此時(shí)產(chǎn)生一定的偏轉(zhuǎn)距離;繼續(xù)旋轉(zhuǎn)微型位儀臺(tái)X-Y軸,直至Beam Gage操作軟件上光斑圖像消失,如圖5(c)所示,此時(shí)入射激光的偏轉(zhuǎn)距離為231.6μm(2.316e+02μm,光束輪廓X界面高斯擬合峰值的變化距離,此值是DO濃度為1.5mg/L時(shí)小球的光偏轉(zhuǎn)值),即為被測(cè)PVA凝膠小球的光偏轉(zhuǎn)值.

圖5 PVA凝膠小球光偏轉(zhuǎn)距離測(cè)量示意

由檢測(cè)結(jié)果,富集在小球內(nèi)的細(xì)菌,在不同的生長(zhǎng)代謝狀態(tài)下,代謝產(chǎn)物與外界溶液形成的濃度梯度是不同的,光偏轉(zhuǎn)快速檢測(cè)法檢測(cè)所得的光偏轉(zhuǎn)值也是不同的.且每次檢測(cè)時(shí)間均在3min之內(nèi),可以克服以往活性污泥檢測(cè)方法耗時(shí)長(zhǎng)、檢測(cè)結(jié)果滯后的局限性,有效提高了活性污泥代謝狀態(tài)的檢測(cè)效率及數(shù)據(jù)的可靠性,故光偏轉(zhuǎn)檢測(cè)法用于快速檢測(cè)微生物代謝狀態(tài)變化是可行的.

2.3 進(jìn)水COD對(duì)PVA凝膠小球光偏轉(zhuǎn)值的影響

如圖6(a)所示,印染廢水COD去除率與PVA凝膠小球光偏轉(zhuǎn)值變化趨勢(shì)均先快速增加后趨于平緩.當(dāng)進(jìn)水COD為91.95mg/L時(shí),PVA凝膠小球的光偏轉(zhuǎn)值為229.51μm,印染廢水COD去除率僅為16.03%,此時(shí)完全混合式曝氣池內(nèi)有機(jī)負(fù)荷較低,富集在PVA凝膠小球中的細(xì)菌處于營(yíng)養(yǎng)不足的狀態(tài),其代謝活力較弱,對(duì)印染廢水中有機(jī)物的氧化分解不徹底,代謝產(chǎn)物與外界溶液進(jìn)行不間斷的物質(zhì)交換時(shí)產(chǎn)生的濃度梯度變化較小;在進(jìn)水COD增至179.3mg/L的過(guò)程中,PVA凝膠小球的光偏轉(zhuǎn)值逐漸增至272.65μm,印染廢水COD去除率也增至40.73%,此時(shí)由于曝氣池內(nèi)隨進(jìn)水COD濃度的增加,可供小球中細(xì)菌代謝繁殖利用的營(yíng)養(yǎng)底物增多,從而使得細(xì)菌代謝逐漸旺盛,羅茜等[26]的研究表明外加碳源會(huì)改變?cè)嘉勰嘀械奈镔|(zhì)供應(yīng)水平,從而刺激脫氫酶的合成,這與本實(shí)驗(yàn)進(jìn)水COD濃度增加,會(huì)引起細(xì)菌活性的提高,進(jìn)而使得光偏轉(zhuǎn)值增高的結(jié)論一致;當(dāng)進(jìn)水COD進(jìn)一步增至519.4mg/L時(shí), PVA凝膠小球光偏轉(zhuǎn)值從272.65μm增至299.97μm,印染廢水COD去除率從40.73%增至66.99%,此時(shí)曝氣池內(nèi)有機(jī)負(fù)荷進(jìn)一步升高,但細(xì)菌的水解酶酶促反應(yīng)速率有限[27],小球中細(xì)菌的代謝狀態(tài)逐漸趨于穩(wěn)定,與印染廢水COD去除率增速減緩保持一致.

圖6 各因素對(duì)PVA凝膠小球光偏轉(zhuǎn)值及COD去除率的影響

2.4 pH值對(duì)PVA凝膠小球光偏轉(zhuǎn)值的影響

為探究pH值對(duì)PVA凝膠小球內(nèi)富集細(xì)菌的影響,調(diào)節(jié)初始pH=6,后逐漸增大曝氣池內(nèi)pH值,隨后反復(fù)調(diào)節(jié)曝氣池內(nèi)pH=6～9.

如圖6(b)所示,在前15d的檢測(cè)研究中,當(dāng)pH=6時(shí),對(duì)應(yīng)狀態(tài)下PVA凝膠小球光偏轉(zhuǎn)值為270.52μm,印染廢水COD去除率為54.18%,此時(shí)曝氣池內(nèi)處于異常運(yùn)行狀態(tài),偏酸性的條件使得PVA凝膠小球中富集的細(xì)菌表面特性被改變,影響了細(xì)菌自身對(duì)營(yíng)養(yǎng)物質(zhì)的攝取及有效分解,且低pH值可能直接影響細(xì)菌的活性,從而導(dǎo)致細(xì)菌自身代謝活性較弱[28];當(dāng)pH值升至7的過(guò)程中,PVA凝膠小球光偏轉(zhuǎn)值增至293.96μm,印染廢水COD去除率增至64.83%,此時(shí)由于曝氣池內(nèi)從偏酸性變?yōu)橹行?有利于細(xì)菌活性的恢復(fù)及代謝繁殖,對(duì)有機(jī)污染物的降解效率也逐漸增大;當(dāng)pH值升至8.5時(shí),PVA凝膠小球光偏轉(zhuǎn)值降低至266.26μm,印染廢水COD去除率降低至55.2%,此時(shí)在偏堿性條件下,曝氣池內(nèi)PVA凝膠小球中富集的細(xì)菌代謝活性再次受到抑制;但這與其他研究得出的pH=7.5～8.5時(shí),活性污泥微生物仍能保持較好活性[29]的結(jié)論不符.當(dāng)pH值升至9時(shí),PVA凝膠小球的光偏轉(zhuǎn)值增大至293.94μm,但光偏轉(zhuǎn)值波動(dòng)較大(SD>5),且對(duì)應(yīng)狀態(tài)下印染廢水COD去除率進(jìn)一步降低至47.1%,此時(shí)完全混合式曝氣池系統(tǒng)受到危害,再次處于異常運(yùn)行狀態(tài),曝氣池內(nèi)PVA凝膠小球中富集的細(xì)菌代謝活性進(jìn)一步減弱,印染廢水COD去除率也隨之降低.Wang等[30]的FTIR研究結(jié)果表明,在較高的pH值下,羧基、酰胺基團(tuán)被破壞并出現(xiàn)無(wú)序的盤旋結(jié)果.故在較高的pH值下,部分細(xì)菌可能出現(xiàn)細(xì)胞受損的情況,導(dǎo)致細(xì)胞內(nèi)物質(zhì)大量釋放溶解,使得小球光偏轉(zhuǎn)值異常增大.

朱哲等[31]研究表明在酸性條件下,污泥絮體的平均粒徑增大,結(jié)構(gòu)松散,在中性條件下,絮體平均粒徑減小,分形維數(shù)較高,結(jié)構(gòu)致密,偏堿性條件下,絮體平均粒徑較中性條件略有增大,分形維數(shù)相應(yīng)減小.這表明,在酸性條件及堿性條件下,污泥中微生物狀態(tài)較差,從而導(dǎo)致污泥絮體結(jié)構(gòu)產(chǎn)生不好的變化,進(jìn)一步影響微生物代謝活性及對(duì)污染物的分解,而這與本研究PVA凝膠小球中細(xì)菌的代謝狀態(tài)引起的光偏轉(zhuǎn)值及印染廢水COD去除率變化結(jié)論一致.

隨后檢測(cè)研究中,重復(fù)調(diào)節(jié)系統(tǒng)pH=6～9,發(fā)現(xiàn)PVA凝膠小球的光偏轉(zhuǎn)值與印染廢水COD去除率和前15d檢測(cè)結(jié)果存在相似的變化關(guān)系.

2.5 DO濃度對(duì)PVA凝膠小球光偏轉(zhuǎn)值的影響

為探究DO濃度對(duì)PVA凝膠小球內(nèi)富集細(xì)菌的影響,開(kāi)始調(diào)節(jié)DO=1.5mg/L,而后逐漸增大曝氣池內(nèi)DO值,隨后反復(fù)調(diào)節(jié)曝氣池內(nèi)DO=1.5～5mg/L.

如圖6(c)所示,在前15d的檢測(cè)研究中,當(dāng)DO= 1.5mg/L時(shí),PVA凝膠小球光偏轉(zhuǎn)值為231.6μm,印染廢水COD去除率為52.23%,此時(shí)印染廢水活性污泥完全混合式曝氣池內(nèi)含氧量較少,PVA凝膠小球中富集的細(xì)菌新陳代謝活性不足,對(duì)有機(jī)物底物不能進(jìn)行充分的傳質(zhì)與反應(yīng),代謝產(chǎn)物與外界溶液間產(chǎn)生的濃度梯度變化也較小;當(dāng)DO濃度從1.5mg/L增至3.5mg/L,PVA凝膠小球的光偏轉(zhuǎn)值快速增長(zhǎng),從231.6μm增至288.1μm,印染廢水COD去除率從52.23%增至58.46%,此時(shí)曝氣池內(nèi)PVA凝膠小球中富集的細(xì)菌代謝活性逐漸增強(qiáng),對(duì)營(yíng)養(yǎng)物質(zhì)的吸附與攝取速度加快,對(duì)有機(jī)物的氧化分解效率也不斷提高;隨著DO濃度增至4mg/L,PVA凝膠小球的光偏轉(zhuǎn)值從288.1μm增至309.3μm,印染廢水COD去除率從58.46%增至61.18%,此時(shí)隨著曝氣池內(nèi)含氧量的進(jìn)一步升高,PVA凝膠小球中富集的細(xì)菌與有機(jī)物底物得以充分接觸,對(duì)有機(jī)物底物的代謝能力也進(jìn)一步提高.李興[29]研究結(jié)果表明當(dāng)DO濃度值在2.0～4.5mg/L時(shí)脫氫酶活性法可以有效反映活性污泥的實(shí)際代謝狀態(tài),且隨著DO濃度的增加,活性污泥脫氫酶活性逐漸增強(qiáng),這與本研究小球光偏轉(zhuǎn)值檢測(cè)結(jié)果表明的活性污泥代謝狀態(tài)結(jié)論一致.

隨后調(diào)節(jié)完全混合式曝氣池內(nèi)DO濃度,使得DO=3mg/L,對(duì)應(yīng)狀態(tài)下PVA凝膠小球光偏轉(zhuǎn)值為286.45μm,印染廢水COD去除率為56.42%,此時(shí)完全混合式曝氣池從異常運(yùn)行條件調(diào)整至正常運(yùn)行條件,PVA凝膠小球中細(xì)菌的代謝活性逐漸恢復(fù);當(dāng)DO濃度增至4mg/L時(shí),PVA凝膠小球光偏轉(zhuǎn)值為303.47μm,印染廢水COD去除率為56.05%,此時(shí)PVA凝膠小球中細(xì)菌的代謝活性進(jìn)一步增強(qiáng),PVA凝膠小球光偏轉(zhuǎn)值增大,印染廢水COD去除率也隨之增大;當(dāng)DO濃度增至4.5mg/L時(shí),PVA凝膠小球中細(xì)菌的代謝活性減弱,PVA凝膠小球光偏轉(zhuǎn)值減小,但印染廢水COD去除率卻稍許增加.

在隨后檢測(cè)中,重復(fù)調(diào)節(jié)曝氣池DO=1～5mg/L,結(jié)果發(fā)現(xiàn)PVA凝膠小球的光偏轉(zhuǎn)值變化與印染廢水COD去除率變化和之前的研究存在相似的變化關(guān)系.

2.6 重金屬濃度對(duì)PVA凝膠小球光偏轉(zhuǎn)值的影響

金屬鉻化合物被廣泛應(yīng)用于印染領(lǐng)域染色工藝中,如媒染劑重鉻酸鉀(K2Cr2O7)就常用于羊毛染色[32-33].為探究重金屬對(duì)PVA凝膠小球內(nèi)細(xì)菌代謝狀態(tài)的影響,向印染廢水活性污泥完全混合式曝氣池內(nèi)投加CrCl3.

如圖6(d)所示,印染廢水COD去除率持續(xù)降低,PVA凝膠小球的光偏轉(zhuǎn)值先快速降低后增加,然后再次降低.隨著Cr3+濃度從0mg/L增至20mg/L, PVA凝膠小球的光偏轉(zhuǎn)值從289.2μm減小到269.7μm,印染廢水COD去除率從52.5%降至47.5%,重金屬會(huì)使酶活性受到抑制[34-35],此時(shí)曝氣池內(nèi)小球中細(xì)菌的代謝活性在Cr3+作用下減弱;當(dāng)Cr3+濃度從20mg/L增至40mg/L時(shí),PVA凝膠小球的光偏轉(zhuǎn)值從269.7μm增大到304.3μm,印染廢水COD去除率從47.5%降至30.7%,此時(shí)曝氣池內(nèi)PVA凝膠小球中細(xì)菌的代謝活性進(jìn)一步減弱,但部分對(duì)Cr3+耐受性較差的細(xì)菌出現(xiàn)細(xì)胞膜受損甚至死亡,導(dǎo)致細(xì)胞內(nèi)物質(zhì)大量釋放[36],從而使PVA凝膠小球中富集的細(xì)菌與外界溶液物質(zhì)交換時(shí)產(chǎn)生的濃度梯度變化增大,導(dǎo)致PVA凝膠小球光偏轉(zhuǎn)值增加,對(duì)應(yīng)狀態(tài)下印染廢水COD去除率的下降速度加快.Plaper等[37]研究表明Cr3+可能引起DNA損傷并抑制拓?fù)洚悩?gòu)酶DNA活性,且Cr3+還會(huì)降低細(xì)胞的活力或增殖速率,這與本研究PVA凝膠小球光偏轉(zhuǎn)值增加結(jié)論一致;當(dāng)Cr3+濃度升至50mg/L時(shí),污泥出現(xiàn)解體上浮現(xiàn)象,曝氣池內(nèi)PVA凝膠小球中富集的尚有活性的細(xì)菌代謝狀態(tài)持續(xù)減弱,PVA凝膠小球光偏轉(zhuǎn)值降低至281.4μm,印染廢水COD去除率降低至25.73%.

3 活性污泥中微生物代謝引發(fā)光偏轉(zhuǎn)的機(jī)理分析

3.1 三維熒光光譜檢測(cè)

圖7 活性污泥降解印染廢水前后有機(jī)物三維熒光光譜圖

a:降解前;b:降解后

如圖8所示,通過(guò)三維熒光光譜[38-39]檢測(cè)發(fā)現(xiàn),印染廢水三維熒光峰分別為A酪氨(ex/em= 210.0nm/320.0nm)、B芳香類蛋白(ex/em= 230.0nm/335.0nm)、C色氨酸(ex/em=280.0nm/ 320.0nm),這3種有機(jī)物的熒光強(qiáng)度分別為2210、8663、8138.說(shuō)明印染廢水中主要的有機(jī)物為酪氨酸、芳香類蛋白、色氨酸.

對(duì)比經(jīng)印染廢水活性污泥完全混合式曝氣池處理后的出水,發(fā)現(xiàn)酪氨酸、芳香類蛋白、色氨酸的熒光強(qiáng)度分別降為270.7、1032、1138.下降率分別為87.77%、88.08%、86.02%(表2),說(shuō)明這3類有機(jī)物是活性污泥中參與微生物(主要為細(xì)菌)代謝的主要有機(jī)物.

表2 各有機(jī)組分熒光強(qiáng)度

3.2 展望

在活性污泥中,有活性的微生物(Ma)、微生物自身氧化殘留物(Me)、吸附在活性污泥上沒(méi)有被微生物所降解的有機(jī)物(Mi)、無(wú)機(jī)懸浮固體(Mii)甚至是菌膠團(tuán)中的胞外聚合物(EPS)在不同運(yùn)行條件下都會(huì)對(duì)活性污泥本身的性質(zhì)產(chǎn)生重要影響[40-41],在不同條件下產(chǎn)生何種微生物代謝產(chǎn)物及哪種物質(zhì)對(duì)于光偏轉(zhuǎn)值影響較大還未展開(kāi)具體探究,后續(xù)實(shí)驗(yàn)以期深入探究光偏轉(zhuǎn)快速檢測(cè)法檢測(cè)活性污泥代謝狀態(tài)的影響因素及機(jī)理,進(jìn)一步縮短檢測(cè)時(shí)間,并提升檢測(cè)方法的精度和靈敏度,為日后光偏轉(zhuǎn)快速檢測(cè)法應(yīng)用于活性污泥代謝狀態(tài)的檢測(cè)、活性污泥處理系統(tǒng)的運(yùn)行調(diào)節(jié)及保護(hù)、出水水質(zhì)在線預(yù)警提供有效的依據(jù).

4 結(jié)論

4.1 研究表明,在印染廢水活性污泥完全混合式曝氣池中,采用光偏轉(zhuǎn)快速檢測(cè)法,檢測(cè)PVA凝膠小球中細(xì)菌的代謝狀態(tài)及依據(jù)PVA凝膠小球光偏轉(zhuǎn)值變化,預(yù)測(cè)系統(tǒng)隨后15h的出水水質(zhì)是可行的;

4.2 曝氣池運(yùn)行條件改變且狀態(tài)正常時(shí),細(xì)菌代謝狀態(tài)良好,對(duì)應(yīng)狀態(tài)下PVA凝膠小球光偏轉(zhuǎn)值快速增大并穩(wěn)定在較高值,且SD<5;曝氣池運(yùn)行條件改變但狀態(tài)異常時(shí),細(xì)菌代謝狀態(tài)受到抑制或細(xì)胞受到損傷,此時(shí)PVA凝膠小球光偏轉(zhuǎn)值快速減小或異常增大,且SD>5;

4.3 PVA凝膠小球光偏轉(zhuǎn)值增大并穩(wěn)定在較高值,且SD<5時(shí),對(duì)應(yīng)狀態(tài)下印染廢水COD去除率隨之增大,出水水質(zhì)穩(wěn)定;當(dāng)PVA凝膠小球光偏轉(zhuǎn)值減小或異常增大,且SD>5時(shí),對(duì)應(yīng)狀態(tài)下印染廢水COD去除率隨之降低,出水水質(zhì)不穩(wěn)定;

4.4 三維熒光光譜表明在印染廢水處理中參與微生物(主要為細(xì)菌)代謝的主要有機(jī)物為酪氨酸、芳香類蛋白、色氨酸.

[1] Carmen S D R, Luis M M, Rui A R B. Decontamination of an industrial cotton dyeing wastewater by chemical and biological processes [J]. Industrial & Engineering Chemistry Research, 2014, 53(6):2412-2421.

[2] 端正花,潘留明,陳曉歐,等.低溫下活性污泥膨脹的微生物群落結(jié)構(gòu)研究 [J]. 環(huán)境科學(xué), 2016,37(3):1070-1074.

Duan Z H, Pan L M, Chen X O, et al. Changes of microbial community structure in activated sludge bulking at low temperature [J]. Environmental Science, 2016,37(3):1070-1074.

[3] 周 律,彭 標(biāo).微量元素對(duì)工業(yè)廢水好氧生物處理的促進(jìn) [J]. 清華大學(xué)學(xué)報(bào)(自然科學(xué)版), 2015,55(6):653-659.

Zhou L, Pen B. Effect of trace elements for improving the aerobic biological treatment of industrial wastewater [J]. Journal of Tsinghua University (Science and Technology), 2015,55(6):653-659.

[4] 郝思宇,張 艾,劉亞男.臭氧與過(guò)氧化鈣協(xié)同降解甲基紅廢水 [J]. 中國(guó)環(huán)境科學(xué), 2019,39(2):591-597.

Hao S Y, Zhang A, Liu Y N. Removal of methyl red in aqueous by O3/CaO2treatment: influencing factors and synergetic effects [J]. China Environmental Science, 2019,39(2):591-597.

[5] 唐嘉麗,岳 秀,吉世明,等.好氧生化法處理印染廢水原水的工藝優(yōu)化研究 [J]. 環(huán)境工程, 2016,34(S1):123-125,158.

Tang J L, Yue X, Ji S M, et al. Optimizatio research on process of aerobic biological treatment for raw dyeing wastewater [J]. Environmental Engineering, 2016,34(S1):123-125,158.

[6] El Gohary F, Tawfik A. Decolorization and COD reduction of disperse and reactive dyes wastewater using chemical-coagulation followed by sequential batch reactor (SBR) process [J]. Desalination, 2009,249(3): 1159-1164.

[7] 章志元,張 莉,劉 新,等.活性污泥培養(yǎng)初期溶解氧(DO)的控制 [J]. 環(huán)境工程, 2008,26(S1):163-164.

Zhang Z Y, Zhang L, Liu X, et al. Dissolved oxygen (DO) controlling in initial period of raising activated sludge [J]. Environmental Engineering, 2008,26(S1):163-164.

[8] Jochen H, Barbara S, Martin W. Floc volume effects in suspensions and its relevance for wastewater engineering [J]. Environmental Science & Technology, 2011,45(20):8788-8793.

[9] 張日霞,王社平,謝純德,等.SVI在Orbal氧化溝運(yùn)行管理中的指導(dǎo)作用 [J]. 中國(guó)給水排水, 2010,26(6):52-54.

Zhang R X, Wang S P, Xie C D, et al. Guiding role of SVI in actual operation and management of Orbal oxidation ditch process [J]. China Water & Wastewater, 2010,26(6):52-54.

[10] 張洛紅,李冰清,李 興.ATP法和TTC法表征印染污泥性質(zhì)的適用性 [J]. 西安工程大學(xué)學(xué)報(bào), 2013,27(6):764-767.

Zhang L H, Li B Q, Li X. The applicability for describing the printing and dyeing sludge properties with ATP and TTC [J]. Journal of Xi'an Polytechnic University, 2013,27(6):764-767.

[11] Wang X F, Jia Y G, Li D. The relationship between SOUR and some pocess parameters in activated sludge system [J]. Advanced Materials Research, 2012,462:169-172.

[12] 劉寶寶,汪 洋,易 立,等.細(xì)菌生物被膜檢測(cè)與分析方法 [J]. 微生物學(xué)通報(bào), 2018,45(10):2263-2270.

Liu B B, Wang Y, Yi L, et al. Detection and analysis methods of bacterial biofilm [J]. Microbiology China, 2018,45(10):2263-2270.

[13] Szilvia T S, József O, Magdolna M, et al. Comparison of different granular solids as biofilm carriers [J]. Microchemical Journal, 2013, 107:101-107.

[14] Zheng Y K, Hu Z B, Tu X J, et al. In-situ determination of the observed yield coefficient of aerobic activated sludge by headspace gas chromatography [J]. Journal of Chromatography A, 2020,1610.

[15] Jiang X T, Ye L, Ju F, et al. Toward an intensive longitudinal understanding of activated sludge bacterial assembly and dynamics [J]. Environmental Science & Technology, 2018,52(15):8224-8232.

[16] Ni B J, Fang F, Xie W M, et al. Formation of distinct soluble microbial products by activated sludge: Kinetic analysis and quantitative determination [J]. Environmental Science & Technology, 2012,46(3): 1667-1674.

[17] 李冰清.光偏轉(zhuǎn)檢測(cè)活性污泥生長(zhǎng)狀態(tài)新方法研究 [D]. 西安:西安工程大學(xué), 2014.

Li B Q. The study of new method for detecting the activated sludge metabolic state by light deflection [J]. China: Xi'an Polytechnic University, 2014.

[18] 王利娜,劉永紅,閆愛(ài)軍,等.生活污水PVA生物處理工藝 [J]. 環(huán)境工程學(xué)報(bào), 2016,10(4):1688-1692.

Wang L N, Liu Y H, Yan A J, et al. Treatment of domestic sewage by PVA biological process [J]. Chinese Journal of Environmental Engineering, 2016,10(4):1688-1692.

[19] 曹 敏,張洛紅,成晶晶,等.聚乙烯醇載體在序批式高校生活污水處理中的應(yīng)用 [J]. 西安工程大學(xué)學(xué)報(bào), 2018,32(3):285-290.

Cao M, Zhang L H, Cheng J J, et al. Application of PVA carrier in SBR treatment of domestic sewage at university campus [J]. Journal of Xi'an Polytechnic University, 2018,32(3):285-290.

[20] Khanh D P. Studies on COD removal using poly (vinyl alcohol)-gel beads as biomass carrier in UASB reactor [D]. Japan: Kumamoto University, 2012.

[21] Bai X, Ye Z F, Li Y F, et al. Preparation ofcrosslinked macroporous PVA foam carrier for immobiliza-tion of microorganisms [J]. Process Biochemistry, 2010,45(1):60-66.

[22] 康小虎,冷 艷,曾小英,等.污水處理活性污泥微生物群落研究進(jìn)展 [J]. 環(huán)境科學(xué)與技術(shù), 2020,43(5):49-54.

Kang X H, Len Y, Zeng X Y, et al. Review on activated sludge microbial community in sewage treatment [J]. Environmental Science & Technology, 2020,43(5):49-54.

[23] 鞠 峰,張 彤.活性污泥微生物群落宏組學(xué)研究進(jìn)展 [J]. 微生物學(xué)通報(bào), 2019,46(8):2038-2052.

Ju F, Zhang T. Advances in metaomics research on activated sludge microbial community [J]. Microbiology China, 2019,46(8):2038- 2052.

[24] Chao Y, Wei Z, Liu R H, et al. Phylogenetic diversity and metabolic potential of activated sludge microbial communities in full-scale wastewater treatment plants [J]. Environmental Science & Technology, 2011,45(17):7408-7415.

[25] Nie L J, Kuboda M, Inoue T, et al. Effect of acid solutions on plants studied by the optical beam deflection method [J]. Journal of Environmental Sciences, 2013,25(1):93-96.

[26] 羅 茜,馬宏瑞,朱 超,等.外源和內(nèi)源呼吸模式下好氧活性污泥的微生物群落演替及生物活性特征[J]. 生態(tài)環(huán)境學(xué)報(bào), 2013,22(12): 1887-1892.

Luo Q, Ma H R, Zhu C, et al. Bacterial community and metabolic characteristics during endogenous and exogenous periods in activated sludge [J]. Ecology and Environmental Sciences, 2013,22(12):1887- 1892.

[27] 金寶丹,王淑瑩,邢立群,等.基質(zhì)投加方式對(duì)污泥堿性發(fā)酵性能的影響 [J]. 中國(guó)環(huán)境科學(xué), 2015,35(10):3010-3017.

Jin B D, Wang S Y, Xing L Q, et al. The effect of substrate adding method on performance of sludge alkaline fermentation [J]. China Environmental Science, 2015,35(10):3010-3017.

[28] Gulde R, Helbling D E, Scheidegger A, et al. pH-dependent biotransformation of ionizable organic micro-pollutants in activated sludge [J]. Environmental Science & Technology, 2014,48(23):13760- 8.

[29] 李 興.印染廢水生物處理系統(tǒng)活性污泥性質(zhì)的檢測(cè)方法比較研究[D]. 西安:西安工程大學(xué), 2011.

Li X. Comparative study on detection methods of activated sludge on printing dyeing wastewater biological treatment system [J]. Xi￠an: Xi'an Polytechnic University, 2011.

[30] Wang L L, Wang L F, Ren X M, et al. pH dependence of structure and surface properties of microbial EPS [J]. Environmental science & technology, 2012,46(2):737-44.

[31] 朱 哲,李 濤,王東升,等.pH對(duì)活性污泥表面特性和形態(tài)結(jié)構(gòu)的影響 [J]. 環(huán)境工程學(xué)報(bào), 2008,(12):1599-1604.

Zhu Z, Li T, Wang D S, et al. Effect of pH on surface properties and Physical structure of activated sludge flocs [J]. Chinese Journal of Environmental Engineering, 2008,(12):1599-1604.

[32] 管斌斌,李 慶,陳靈輝,等.基于鋯-有機(jī)骨架的印染廢水中Cr(Ⅵ)的熒光檢測(cè) [J]. 紡織學(xué)報(bào), 2021,42(2):122-128.

Guan B B, Li Q, Chen L H, et al. Fluorescence detection of Cr(VI) from printing and dyeing wastewater by zirconium-organic framework [J]. Journal of Textile Research, 2021,42(2):122-128.

[33] He T, Zhang Y Z, Kong X J, et al. Zr(IV)-based metal organic framework with T-shaped ligand: unique structure, high stability, selective detection, and rapid adsorption of Cr2O72－in water [J]. ACS Applied Materials & Interfaces, 2018,10(19):16650-16659.

[34] 趙長(zhǎng)坤,于娜玲,馬丙瑞,等.二價(jià)鈷離子對(duì)序批式反應(yīng)器性能;微生物活性及其微生物群落的影響 [J]. 中國(guó)海洋大學(xué)學(xué)報(bào)(自然科學(xué)版), 2020,50(6):101-108.

Zhao C K, Yu N L, Ma B R, et al. Effects of divalent cobalt (co(Ⅱ)) on the performance microbial activity and microbial community of sequencing batch reactor [J]. Periodical of Ocean University of China, 2020,50(6):101-108.

[35] Jaiswal D, Pandey J. Impact of heavy metal on activity of some microbial enzymes in the riverbed sediments: Ecotoxicological implications in the ganga river(India) [J]. Ecotoxicology and Environmental Safety, 2018,46(3):104-115.

[36] Zeeshan M, Murugadas A, Ghaskadbi S, et al. Ecotoxicological assessment of cobalt using Hydra model: ROS, oxidative stress, DNA damage, cell cycle arrest, and apoptosis as mechanisms of toxicity [J]. Environmental pollution, 2017,224:54-69.

[37] Plaper A, Jenko-Brinovec S, Premzl A, et al. Genotoxicity of trivalent chromium in bacterial cells. Possible effects on DNA topology [J]. Chemical Research in Toxicology, 2002,15(7):943-9.

[38] 楊金強(qiáng),趙南京,殷高方,等.城市生活污水處理過(guò)程三維熒光光譜在線監(jiān)測(cè)分析方法 [J]. 光譜學(xué)與光譜分析, 2020,40(7):1993-1997.

Yang J Q, Zhao N J, Yin G F, et al. On-line monitoring and analysis method of three-dimensional fluorescence spectrum in urban domestic sewage treatment process [J]. Spectroscopy and Spectral Analysis, 2020,40(7):1993-1997.

[39] 王士峰,吳 靜,程 澄,等.某印染廢水的水質(zhì)指紋特征 [J]. 光譜學(xué)與光譜分析, 2015,35(12):3440-3443.

Wang S F, Wu J, Cheng C, et al. Aqueous fingerprint of printing and dyeing wastewater [J]. Spectroscopy and Spectral Analysis, 2015,35 (12):3440-3443.

[40] Li W W, Zhang H L, Sheng G P, et al. Roles of extracellular polymeric substances in enhanced biological phosphorus removal process [J]. Water Research, 2015,86:85-95.

[41] Wei L L, An X Y, Wang S, et al. Effect of hydraulic retention time on deterioration/restarting of sludge anaerobic digestion: Extracellular polymeric substances and microbial response [J]. Bioresource Technology, 2017,244:261-269.

Study on rapid detection of beam deflection method for detecting metabolic status of activated sludge from printing and dyeing wastewater.

ZHANG Luo-hong*, LI Rui-ying, CAO Min, CHENG Jing-jing, WANG Xun-tao, ZHAI Ying-bo, XIONG Xin

(Xi'an polytechnic University, Department of Environmental Science and Engineering, Xi'an 710600, China)., 2021,41(9)：4157～4166

Considering that limitation that cumbersome process, time-consuming and lagging detection of current activated sludge testing process, a rapid detection of beam deflection method were provided in this study. The polyvinyl alcohol gel beads with a particle size of 4mm and microporous structure of 20μm were put in the printing and dyeing wastewater complete mixed activated sludge treatment system with a sludge load of 0.33KgCOD/(kg MLSS×d) and a hydraulic retention time of 15h. The light spot analyzer was used to detecte light deflection which reflect the surface concentration gradient changes due to the exchange of external solutions and microbial metabolites after the beads reached a stable state. The corresponding COD of effluent after 15h were also measured, meanwhile the COD removal rate were calculated. After ten consecutive months of testing, it was found that the predominant microorganism is bacteria in the PVA-gel beads. The light deflection value of the beads increased from 229.51μm to 299.97μm when the influent COD increased from 91.95mg/L to 519.4mg/L, and The COD removal rate also increased from 16.03% to 66.99%. The light deflection of the beads increased with dissolved oxygen concentration and reached to the higest value 309.3μm at DO=4mg/L, meanwhile, the corresponding COD removal rate reached to the maximum which is 61.18%, when the dissolved oxygen concentration range from 1.5mg/L to 5mg/L. The light deflection of the beads increased with dissolved oxygen concentration and reached to the higest value 293.96μm at pH=7, meanwhile, the corresponding COD removal rate reached to the maximum which is 64.83%, when the pH range from 6to 9. The light deflection value of the beads decreased with the concentration of Cr3+and reached to 269.7μm when the Cr3+concentration at 20mg/L. The light deflection value increased with Cr3+concentration continiued increased to 50mg/L, but the corresponding COD removal rate decreased form 52.5% to 25.73%, for the reason that the microbial cells are damaged and the intracellular substances are dissolved. The results show that the changes information of metabolic state in activated sludge can be quickly obtained by this method. And the changes of light deflection value of beads can be used to predict the subsequent COD concentration removal effect of printing and dyeing wastewater under specific conditions. Three-dimensional fluorescence spectroscopy were also used to explore the mechanism of microbial metabolism triggering light deflection. And the results showed that the main organic substances involved in microbial metabolism are tyrosine, aromatic proteins and tryptophan.

rapid detection of beam deflection method；activated sludge method；microbial metabolism status；polyvinyl alcohol (PVA) -gel beads；COD removal rate

X703.1

A

1000-6923(2021)09-4157-10

張洛紅(1969-),男,陜西西安人,教授,博士,主要研究方向?yàn)榄h(huán)境監(jiān)測(cè)與污染控制.發(fā)表論文80余篇.

2021-02-01

陜西省重點(diǎn)研發(fā)計(jì)劃項(xiàng)目(2018KW-036);西安市科技計(jì)劃項(xiàng)目(2019217114GXRC007CG008-GXYD7.10)

* 責(zé)任作者, 教授, 1710501539@qq.com