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科技的高速发展在提高人类生活水平的同时对环境也会造成极大影响,近年来,国内外水体污染问题日益严峻[1-3]。2015年,中国废水排放总量为7.353×1010 t。其中,城镇生活污水排放量达到了5.352×1010 t[4]。城镇生活污水的处理问题备受关注,因此,AO、A2O、OAO、氧化沟等优良工艺应运而生[5-6]。
缺氧好氧工艺即AO工艺是我国目前广泛应用的一种生物脱氮工艺,由于其脱氮效果较好、原理简单被国内外学者和工程师持续研究和改进[7-9]。OAO工艺即是AO工艺的一种改良工艺,其在传统AO工艺的缺氧池前端增设一级曝气池,具有良好的废水处理效果[10-11]。
微生物是污水生物处理的核心部分,利用分子生物学技术对污水处理过程中活性污泥的微生物菌群进行动态跟踪和功能群种鉴定,有助于筛选并培养出利于污水处理的优势菌种,构建更加合理的活性污泥生态系统,提高污水处理效率[12]。MATSUDA等[13]对日本大阪8个城市污水厂的活性污泥微生物组成进行了分析,发现不同工艺在不同时期微生物群落差异很大。DING等[14]和YE等[15]分别应用AO工艺和A2O工艺处理混合废水和酱油废水,发现Proteobacteria是污水处理中的第一优势菌门。HAN等[16]、曾涛涛等[17]研究氧化沟工艺处理生活污水时发现,大部分细菌属于Proteobacteria和Bacteroidetes这2大门类,其优势菌属有Pseudomonas、Phycisphaera、Methylocystis等。但是,关于OAO工艺处理城镇生活污水过程中活性污泥的微生物特性,目前还少有研究。本研究拟采用16S rDNA高通量测序技术对OAO和AO工艺处理城镇生活污水过程中各反应池的活性污泥中的微生物进行测序分析,为OAO工艺处理城镇生活污水中优势菌种的筛选及培养提供参考。
OAO和AO工艺处理城镇生活污水的微生物群落特征分析
Analysis of microbial community characteristics of OAO and AO processes for domestic wastewater treatment
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摘要: 以模拟城镇生活污水为对象,采用AO和OAO 2种工艺进行处理,通过常规水质检测和高通量测序技术来分析和探究导致2种工艺运行效果不同的微生物层面原因。结果表明:OAO工艺对COD和NH3-N的平均去除率略高于AO工艺,但OAO工艺对TN和TP的去除效果较为显著,平均去除率分别比AO工艺高6.01%和3.44%;2种工艺的优势菌门均为Proteobacteria和Bacteroidetes,2种工艺的优势菌纲也均为β-Proteobacteria和γ-Proteobacteria;2种工艺间微生物群落差异性较大,OAO工艺的微生物种群丰度和多样性均大于AO工艺;AO工艺优势菌属为Pseudomonas、Thiothrix、Dechloromonas,OAO工艺为Thermomonas、Dechloromonas、Rhodobacter。此外,Nitrosomonas、Nitrospira作为亚硝化和硝化阶段的重要菌属在AO工艺好氧池的相对丰度为0.05%和0.02%,在OAO工艺中则显著提高,为0.47%和0.45%。其原因是OAO工艺的好氧池污泥BOD负荷较AO小,更适合硝化细菌生长。硝化细菌及其他功能菌在OAO工艺中的大量存在是OAO工艺的能够高效脱氮的主要原因。以上结果可为OAO工艺处理城镇生活污水中优势菌种的筛选及培养提供参考。Abstract: To reveal the reason for the different domestic wastewater treatment effects of OAO(oxic-anoxic-oxic) and AO(anoxic-oxic) process at the perspective of microorganism, the ordinary wastewater quality test and high-throughput sequencing technique were used to analyze the different bacterial community in the activated sludge. The results showed that the average removal rates of COD and NH3-N in OAO process were slightly higher than those in AO process, while TN and TP removal effect by OAO process were significant, and its average removal rates were 6.01% and 3.44% higher than in AO process, respectively. Proteobacteria and Bacteroidetes were the dominant phyla in the two processes, and β-Proteobacteria and γ-Proteobacteria were the dominant classes. A significant difference in the bacteria community occurred in these two systems, the abundance and diversity of species in OAO process were greater than AO process. Pseudomonas, Thiothrix, Dechloromonas were the dominant genus in AO process. Thermomonas, Dechloromonas, Rhodobacter were the dominant genus in OAO process. Nitrosomonas and Nitrospira, as important genus of nitrosation and nitrification stages, had a relative abundance of 0.05% and 0.02% in AO process and 0.47% and 0.45% in OAO process, respectively. The higher abundance of these two bacteria in OAO process might correspond to its lower BOD loading of the activated sludge, which was suitable for the growth of nitrifying bacteria. The high abundances of nitrifying bacteria and other functional bacteria in the OAO process ultimately resulted in high nitrogen removal efficiency. The above results can be used as the theoretical basis for the screening and culture of the dominant bacterial in domestic wastewater treatment using OAO process.
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表 1 2种工艺各反应器中微生物的Alpha多样性指数
Table 1. Alpha diversity index of microorganisms in each tank of the two processes
样本 Chao Ace Shannon Simpson 覆盖率/% AO.H 928.01 954.09 3.96 0.060 99.79 AO.Q 938.10 967.41 3.42 0.202 99.81 OAO.B 913.39 927.97 4.28 0.030 99.81 OAO.H 959.64 980.46 4.44 0.029 99.85 OAO.Q 943.01 980.01 4.37 0.034 99.82 表 2 Proteobacteria和Bacteroidetes中的各纲在各反应池中的分布
Table 2. Distribution of bacteria classes belonging to Proteobacteria and Bacteroidetes in each tank %
菌门 菌纲 AO.H AO.Q OAO.B OAO.H OAO.Q Proteobacteria α-Proteobacteria 3.75 3.04 6.52 7.16 5.24 β-Proteobacteria 22.30 14.14 26.98 19.24 24.67 δ-Proteobacteria 2.99 2.58 2.58 2.83 1.86 γ-Proteobacteria 46.22 50.51 19.28 27.45 25.48 Other 0.19 0.27 0.16 0.05 1.16 Bacteroidetes Sphingobacteria 2.95 4.29 6.65 13.36 11.02 Cytophagia 4.36 4.15 2.81 1.69 1.71 Flavobacteriia 1.74 1.18 4.85 3.13 1.10 Saprospirae 8.83 10.20 16.67 13.42 15.62 Other 0.53 0.54 0.20 0.33 0.64 表 3 功能菌在各反应池中的分布
Table 3. Distribution of functional bacteria in each tank
% 菌属 主要功能 AO.H AO.Q OAO.B OAO.H OAO.Q Dechloromonas 好氧反硝化、氨氧化 3.08 4.57 5.44 3.18 7.78 Flavobacterium 好氧反硝化 0.95 0.85 4.17 2.59 0.67 Hydrogenophaga 异养硝化-好氧反硝化 4.30 0.82 0.38 0.29 0.30 Pseudomonas 异养硝化-好氧反硝化 11.90 0.92 0.46 1.43 0.85 Rhodobacter 好氧反硝化 2.01 1.10 3.53 3.03 1.91 Thermomonas 自养反硝化 2.12 1.60 7.97 10.20 8.48 -
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