環(huán)境學(xué)院研究團(tuán)隊(duì)提出利用超聲波技術(shù)實(shí)現(xiàn)處理廢水脫氮過(guò)程控制的新方法
清華新聞網(wǎng)2月25日電 日前，清華大學(xué)環(huán)境學(xué)院博士后鄭敏、汪誠(chéng)文教授、劉艷臣副研究員和美國(guó)斯坦福大學(xué)高級(jí)研究員吳唯民等在國(guó)際環(huán)境科學(xué)與技術(shù)領(lǐng)域頂尖期刊《環(huán)境科學(xué)與技術(shù)》（Environmental Science and Technology）上發(fā)表了題為“Ultrasonic Treatment Enhanced Ammonia-oxidizing Bacterial (AOB) Activities for Nitritation Process”（超聲波處理增強(qiáng)亞硝化工藝中氨氧化細(xì)菌（AOB）活性）的研究論文，首次提出一種利用超聲波技術(shù)有效控制廢水處理微生物群落組成從而實(shí)現(xiàn)高效、節(jié)能的短程硝化脫氮的新方法。
人類(lèi)生活產(chǎn)生的污水含有大量的氮素污染物，排入水體可造成富營(yíng)養(yǎng)化，因此除氮是廢水處理過(guò)程中的重要環(huán)節(jié)。傳統(tǒng)的廢水生物脫氮是利用細(xì)菌先將水中的氨氮曝氣氧化為亞硝酸鹽，然后由另一類(lèi)細(xì)菌將亞硝酸鹽氧化為硝酸鹽（全程硝化過(guò)程），最后在無(wú)氧條件下利用有機(jī)物將硝酸鹽還原成氮?dú)忉尫诺酱髿猓ǚ聪趸^(guò)程）。1975年Voet等學(xué)者提出了一種短程硝化—反硝化的工藝，即將氨氮氧化為亞硝酸鹽（短程硝化），然后將亞硝酸鹽還原為氮?dú)�。該方法較傳統(tǒng)全程硝化脫氮方法可大大節(jié)省曝氣所耗的能耗、節(jié)省反硝化所需碳源、減少污泥產(chǎn)量，縮短反應(yīng)時(shí)間及減少相應(yīng)反應(yīng)器容積。近年來(lái)又開(kāi)發(fā)了將半量氨氮曝氣氧化為亞硝酸鹽，再與另外半量氨氮反應(yīng)生成氮?dú)獾膮捬醢毖趸に嚕蛇M(jìn)一步減少一半的曝氣能耗。以上兩種工藝，短程硝化是關(guān)鍵，但實(shí)施的難點(diǎn)是要控制廢水處理的細(xì)菌僅將氧化氨氮至亞硝酸鹽。迄今，國(guó)內(nèi)外研究者一直在致力于尋找操作簡(jiǎn)便、具有大規(guī)模應(yīng)用前景的短程硝化過(guò)程控制方法。
2011年，在環(huán)境學(xué)院攻讀博士學(xué)位的鄭敏在利用超聲波技術(shù)進(jìn)行污泥源頭減量化的試驗(yàn)研究中發(fā)現(xiàn)，利用適宜的超聲波條件處理活性污泥后的菌群可以在反應(yīng)器內(nèi)穩(wěn)定地積累亞硝酸鹽而使硝酸鹽生成量大幅減小。此后，在導(dǎo)師汪誠(chéng)文的指導(dǎo)下，鄭敏開(kāi)展了利用超聲波控制細(xì)菌種群結(jié)構(gòu)、獲取高效穩(wěn)定短程硝化的全面系統(tǒng)研究。本次發(fā)表的論文是其中的重要成果之一。該文章報(bào)道了研究組成功通過(guò)超聲波的條件優(yōu)化與控制，利用適當(dāng)?shù)某暡◤?qiáng)度刺激短程硝化必需的好氧氨氧化細(xì)菌（Ammonia-oxidizing Bacteria，AOB）生長(zhǎng)，同時(shí)抑制滅活產(chǎn)生硝酸鹽的亞硝酸鹽氧化細(xì)菌（Nitrite-oxidizing Bacteria，NOB），從而實(shí)現(xiàn)反應(yīng)器的持續(xù)運(yùn)行，并建立了評(píng)價(jià)超聲波對(duì)不同細(xì)菌作用的動(dòng)力學(xué)試驗(yàn)?zāi)Ｐ�。此研究首次全面系統(tǒng)地證實(shí)了在超聲波處理?xiàng)l件下，可以控制反應(yīng)器的細(xì)菌種群、富集馴化出含高豐度AOB無(wú)NOB的微生物達(dá)到高效的短程硝化。該方法將為開(kāi)發(fā)高效污水處理與污泥資源化組合新工藝提供一條全新思路。今后，研究人員將進(jìn)一步探明系統(tǒng)控制的微生物生理學(xué)和生態(tài)學(xué)機(jī)理和實(shí)現(xiàn)從小型試驗(yàn)到生產(chǎn)示范過(guò)渡。
鄭敏為論文第一作者，汪誠(chéng)文為通訊作者。合作者中吳唯民參與試驗(yàn)設(shè)計(jì)和指導(dǎo)研究工作，劉艷臣參與了試驗(yàn)設(shè)計(jì)和微生物學(xué)的分析工作。
論文鏈接：http://pubs.acs.org/doi/abs/10.1021/acs.est.5b04178
Ultrasonic Treatment Enhanced Ammonia-Oxidizing Bacterial (AOB) Activity for Nitritation Process
Min Zheng†, Yan-Chen Liu*†‡, Jia Xinϕ, Hao Zuo†, Cheng-Wen Wang*†, and Wei-Min Wu§
† School of Environment, Tsinghua University, Beijing 100084, China
‡ State Key Joint Laboratory of Environment Simulation and Pollution Control, Beijing 100084, China
ϕ College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
§ Department of Civil & Environmental Engineering, the William & Cloy Codiga Resource Recovery Research Center, Center for Sustainable Development & Global Competitiveness, Stanford University, Stanford, California 94305, United States
Environ. Sci. Technol., 2016, 50 (2), pp 864–871
DOI: 10.1021/acs.est.5b04178
Publication Date (Web): December 17, 2015
Copyright © 2015 American Chemical Society
*(Y.-C.L.) E-mail: liuyc@mail.tsinghua.edu.cn., *(C.-W.W.) Phone: +86 10 6277 1551; fax: +86 10 6278 8148; e-mail:wangcw@tsinghua.edu.cn
Abstract
Oxidation of ammonia to nitrite rather than nitrate is critical for nitritation process for wastewater treatment. We proposed a promising approach by using controlled ultrasonic treatment to enhance the activity of ammonia-oxidizing bacteria (AOB) and suppress that of nitrite-oxidizing bacteria (NOB). Batch activity assays indicated that when ultrasound was applied, AOB activity reached a peak level and then declined but NOB activity deteriorated continuously as the power intensity of ultrasound increased. Kinetic analysis of relative microbial activity versus ultrasonic energy density was performed to investigate the effect of operational factors (power, sludge concentration, and aeration) on AOB and NOB activities and the test parameters were selected for reactor tests. Laboratory sequential batch reactor (SBR) was further used to test the ultrasonic stimulus with 8 h per day operational cycle and synthetic waste urine as influent. With specific ultrasonic energy density of 0.09 kJ/mg VSS and continuously fed influent containing above 200 mg NH3–N/L, high AOB reproductive activity was achieved and nearly complete conversion of ammonia-N to nitrite was maintained. Microbial structure analysis confirmed that the treatment changed community of AOB, NOB, and heterotrophs. Known AOB Nitrosomonasgenus remained at similar level in the biomass while typical NOB Nitrospira genus disappeared in the SBR under ultrasonic treatment and after the treatment was off for 30 days.
