单级和多级A/O工艺中氮的去除效果及N_2O的产生特性
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摘要
利用SBR反应器模拟单级和多级A/O工艺,在进水水质、水力停留时间(HRT)、泥龄(SRT)、温度、缺氧好氧时间比(A/O比)均相同的条件下,考察了两种脱氮系统中氮的去除效果及N_2O的释放情况.结果表明,对于与城市污水水质相当的进水水质,单级A/O工艺和多级A/O工艺对COD、氨氮的去除率均在95%以上,二者无明显区别,但是前者对TN的去除效率高于后者,二者的总氮去除率分别为72.1%和52.2%.在氮素的转化过程中,典型周期内(3 h)单级A/O工艺和多级A/O工艺中N_2O的产生量分别为16.95 mg和3.59 mg,其转化率(即N_2O的产量与TN的去除量之比)分别为11.47%和4.11%,且N_2O的产生和释放主要发生在好氧段(硝化阶段),缺氧段(反硝化阶段)基本无N_2O释放.单级A/O工艺比多级A/O工艺更有利于硝化细菌(AOB、NOB)的生长,在相同的运行条件下,两工艺中AOB的优势菌种皆为Nitrosomonas,但前者的相对丰度高于后者;单级A/O工艺中NOB的种类和相对丰度也明显多于多级A/O工艺.在实际运行中采用合适的A/O分区或供氧方式既可以较好地去除污水中氮素污染,又可以减少N_2O的释放对大气造成二次污染.
The single-stage A / O and multi-stage A / O processes were simulated by sequencing batch reactors( SBRs) with alternate stirring and aeration. The removal efficiency of nitrogen and the release mechanism of N_2O were studied under the identical conditions of influent quality,hydraulic retention time( HRT),sludge retention time( SRT),temperature and anoxic / oxic( A / O) retention time ratio. Experimental results showed that COD or ammonia-nitrogen removal had no significant difference between the single-stage and the multi-stage A / O processes for the influent quality equivalent to municipal wastewater. However,TN removal efficiency of the former was better than the later with 72. 1% and 52. 2%,respectively. In the conversion of total nitrogen,during the typical cycle in the single-stage A / O and multi-stage A / O processes,the yields of N_2O were 16. 95 mg and 3. 95 mg,respectively. The conversion rate,which is the ratio of N_2O yield and TN removal,was respectively 11. 47% and 4. 11%. N_2O production and emission occurred mainly in aerobic( nitrification) phase while there was little N_2O emission in anoxic( denitrification) phase. Although the dominant species of AOB was both Nitrosomonas in the single-stage A / O and the multi-stage A / O processes under the same operating conditions,it was more conducive to the growth of nitrifying bacteria( AOB,NOB) in the single-stage A / O process with the greater abundance of Nitrosomonas. Meanwhile,the type and abundance of NOB in the single-stage A / O process were significantly more than in the multistage A / O process too. Therefore,it is more competitive to deal with the high-strengthening ammonia-nitrogen wastewater in the singlestage A / O process. In the actual operation of wastewater treatment,using appropriate partitions of A / O or oxygen-supplying modes can not only result in better nitrogen removal but also decrease the secondary pollution caused by N_2O to the atmosphere.
The single-stage A / O and multi-stage A / O processes were simulated by sequencing batch reactors( SBRs) with alternate stirring and aeration. The removal efficiency of nitrogen and the release mechanism of N_2O were studied under the identical conditions of influent quality,hydraulic retention time( HRT),sludge retention time( SRT),temperature and anoxic / oxic( A / O) retention time ratio. Experimental results showed that COD or ammonia-nitrogen removal had no significant difference between the single-stage and the multi-stage A / O processes for the influent quality equivalent to municipal wastewater. However,TN removal efficiency of the former was better than the later with 72. 1% and 52. 2%,respectively. In the conversion of total nitrogen,during the typical cycle in the single-stage A / O and multi-stage A / O processes,the yields of N_2O were 16. 95 mg and 3. 95 mg,respectively. The conversion rate,which is the ratio of N_2O yield and TN removal,was respectively 11. 47% and 4. 11%. N_2O production and emission occurred mainly in aerobic( nitrification) phase while there was little N_2O emission in anoxic( denitrification) phase. Although the dominant species of AOB was both Nitrosomonas in the single-stage A / O and the multi-stage A / O processes under the same operating conditions,it was more conducive to the growth of nitrifying bacteria( AOB,NOB) in the single-stage A / O process with the greater abundance of Nitrosomonas. Meanwhile,the type and abundance of NOB in the single-stage A / O process were significantly more than in the multistage A / O process too. Therefore,it is more competitive to deal with the high-strengthening ammonia-nitrogen wastewater in the singlestage A / O process. In the actual operation of wastewater treatment,using appropriate partitions of A / O or oxygen-supplying modes can not only result in better nitrogen removal but also decrease the secondary pollution caused by N_2O to the atmosphere.
引文
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[20]Aslan S,Miller L,Dahab M.Ammonium oxidation via nitrite accumulation under limited oxygen concentration in sequencing batch reactors[J].Bioresource Technology,2009,100(2):659-664.
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[27]Terada A,Sugawara S,Yamamoto T,et al.Physiological characteristics of predominant ammonia-oxidizing bacteria enriched from bioreactors with different influent supply regimes[J].Biochemical Engineering Journal,2013,79:153-161.
[28]Wunderlin P,Mohn J,Joss A,et al.Mechanisms of N2O production in biological wastewater treatment under nitrifying and denitrifying conditions[J].Water Research,2012,46(4):1027-1037.
[29]Shrestha N K,Hadano S,Kamachi T,et al.Dinitrogen production from ammonia by Nitrosomonas europaea[J].Applied Catalysis A:General,2002,237(1-2):33-39.
[2]张静蓉,王淑莹,尚会来,等.污水短程硝化反硝化和同步硝化反硝化生物脱氮中N2O释放量及控制策略[J].环境科学,2009,30(12):3624-2629.Zhang J R,Wang S Y,Shang H L,et al.N2O emission and control in shortcut nitrification and denitrification and simultaneous nitrification and denitrification biological nitrogen removal systems[J].Environmental Science,2009,30(12):3624-2629.
[3]Khalil M A K,Rasmussen R A,Shearer M J.Atmospheric nitrous oxide:patterns of global change during recent decades and centuries[J].Chemosphere,2002,47(8):807-821.
[4]IPCC.Climate change 2007:the physical science basis.Contribution of working group I to the fourth assessment report of the intergovernmental panel on climate change[M].Cambridge:Cambridge University Press,2007.
[5]闫旭,李琦路,韩云平,等.p H对污水好氧处理过程N2O产生的影响[J].环境工程学报,2015,9(7):3240-3246.Yan X,Li Q L,Han Y P,et al.Effect of p H value on N2O production in aerobic wastewater treatment process[J].Chinese Journal of Environmental Engineering,2015,9(7):3240-3246.
[6]刘秀红,彭轶,马涛,等.DO浓度对生活污水硝化过程中N2O产生量的影响[J].环境科学,2008,29(3):660-664.Liu X H,Peng Y,Ma T,et al.Effects of DO concentration on N2O production during nitrification for treating domestic wastewater[J].Environmental Science,2008,29(3):660-664.
[7]Hu Z,Zhang J,Li S P,et al.Effect of aeration rate on the emission of N2O in anoxic-aerobic sequencing batch reactors(A/O SBRs)[J].Journal of Bioscience and Bioengineering,2010,109(5):487-491.
[8]张婷婷,张建,杨芳,等.温度对污水脱氮系统污染物去除效果及氧化亚氮释放的影响[J].环境科学,2012,33(4):1283-1287.Zhang T T,Zhang J,Yang F,et al.Effect of temperature on pollutant removal and nitrous oxide emission of wastewater nitrogen removal system[J].Environmental Science,2012,33(4):1283-1287.
[9]叶建锋.废水生物脱氮处理新技术[M].北京:化学工业出版社,2006.Ye J F.New technologies of biological nitrogen removal in wastewater[M].Beijing:Chemical Industry Press,2006.
[10]王晓慧.城市污水处理厂中氨氧化菌及细菌群落结构与功能研究[D].北京:清华大学,2010.Wang X H.The community structures and functions of ammonia oxidizing bacteria and bacteria in wastewater treatment plant[D].Beijing:Tsinghua University,2010.
[11]侯金良,康勇.城市污水生物脱氮除磷技术的研究进展[J].化工进展,2007,26(3):366-370.Hou J L,Kang Y.Research progress of biological removal of nitrogen and phosphorus in municipal sewage[J].Chemical Industry and Engineering Progress,2007,26(3):366-370.
[12]刘艳臣.Carrousel氧化沟单沟脱氮优化条件及其控制策略研究[D].北京:清华大学,2008.Liu Y C.Study on the optimum operational condition and control strategy of the removal of nitrogen in the carrousel oxidation ditch[D].Beijing:Tsinghua University,2008.
[13]郭昌梓,陈雪梅.一种氧化沟工艺的模拟方法[P].中国专利:CN102815790B,2013-09-11.Guo C Z,Chen X M.Simulation device and method for oxidation ditch technique[P].China Patent:CN102815790B,2013-09-11.
[14]郭昌梓,彭党聪,陈雪梅,等.氧化沟不同曝气模式对氮磷去除性能的优化与比较[J].环境科学,2012,33(3):910-915.Guo C Z,Peng D C,Chen X M,et al.Optimization and comparison of nitrogen and phosphorus removal by different aeration modes in oxidation ditch[J].Environmental Science,2012,33(3):910-915.
[15]国家环境保护总局.水和废水监测分析方法[M].(第四版).北京:中国环境科学出版社,2002.243-284,368-370.State Environmental Protection Administration.Determination methods for examination of water and wastewater(4th ed.)[M].Beijing:China Environmental Science Press,2002.243-284,368-370.
[16]Hu Z,Zhang J,Xie H J,et al.Effect of anoxic-aerobic phase fraction on N2O emission in a sequencing batch reactor under low temperature[J].Bioresource Technology,2011,102(9):5486-5491.
[17]Blcakwood C B,Marsh T,Kim S H,et al.Terminal restriction fragment length polymorphism data analysis for quantitative comparison of microbial communities[J].Applied and Environmental Microbiology,2003,69(2):926-932.
[18]Binladen J,Gilbert M T P,Bollback J P,et al.The use of coded PCR primers enables high-throughput sequencing of multiple homolog amplification products by 454 parallel sequencing[J].PLo S One,2007,2(2):e197.
[19]Guo C Z,Fu W,Chen X M,et al.Nitrogen-removal performance and community structure of nitrifying bacteria under different aeration modes in an oxidation ditch[J].Water Research,2013,47(11):3845-3853.
[20]Aslan S,Miller L,Dahab M.Ammonium oxidation via nitrite accumulation under limited oxygen concentration in sequencing batch reactors[J].Bioresource Technology,2009,100(2):659-664.
[21]Wang Y Y,Lin X M,Zhou D,et al.Nitric oxide and nitrous oxide emissions from a full-scale activated sludge anaerobic/anoxic/oxic process[J].Chemical Engineering Journal,2016,289:330-340.
[22]Hu Z,Zhang J,Xie H J,et al.Minimization of nitrous oxide emission from anoxic-oxic biological nitrogen removal process:effect of influent COD/NH+4ratio and feeding strategy[J].Journal of Bioscience and Bioengineering,2013,115(3):272-278.
[23]Peng L,Li Y W,Ni B J.Nitrous oxide production in completely autotrophic nitrogen removal biofilm process:a simulation study[J].Chemical Engineering Journal,2016,287:217-224.
[24]Kim D J,Kim S H.Effect of nitrite concentration on the distribution and competition of nitrite-oxidizing bacteria in nitratation reactor systems and their kinetic characteristics[J].Water Research,2006,40(5):887-894.
[25]Coskuner G,Curtis T P.In situ characterization of nitrifiers in an activated sludge plant:detection of Nitrobacter spp.[J].Journal of Applied Microbiology,2002,93(3):431-437.
[26]Hu Z,Zhang J,Xie H J,et al.Identifying sources of nitrous oxide emission in anoxic/aerobic sequencing batch reactors(A/O SBRs)acclimated in different aeration rates[J].Enzyme and Microbial Technology,2011,49(2):237-245.
[27]Terada A,Sugawara S,Yamamoto T,et al.Physiological characteristics of predominant ammonia-oxidizing bacteria enriched from bioreactors with different influent supply regimes[J].Biochemical Engineering Journal,2013,79:153-161.
[28]Wunderlin P,Mohn J,Joss A,et al.Mechanisms of N2O production in biological wastewater treatment under nitrifying and denitrifying conditions[J].Water Research,2012,46(4):1027-1037.
[29]Shrestha N K,Hadano S,Kamachi T,et al.Dinitrogen production from ammonia by Nitrosomonas europaea[J].Applied Catalysis A:General,2002,237(1-2):33-39.