MBBR处理某水厂微污染水硝化性能研究
韩文杰,刘凯,杨晓美,刘宜龙,苏丹丹,吴迪
（青岛思普润水处理股份有限公司，山东 青岛 266510）
摘要：对移动床生物膜反应器(MBBR)工艺应用于河道微污染水进行了研究，生化段采用“6段式MBBR生物氧化池”的处理工艺。结果表明，氨氮、COD去除率分别达到57.43%、20.27%，出水水质稳定达到GB3838-2002地表III类标准，且同步硝化反硝化(SND)脱氮占比7.97%。 对悬浮载体进行高氨氮含量（质量浓度7 mg·L-1）水质硝化试验，最大氨氮容积负荷65 g/(m3·d)。MBBR 悬浮载体生物膜硝化优势菌门为Proteobacteria，相对丰度平均为 55.40%，反硝化细菌相对丰度平均为13.36%，为系统SND现象提供微观证明，系统中存在较高丰度可降解难降解有机物的菌属，为微污染水出水COD稳定达标提供了保障。MBBR工艺占地小，可筛选和专性富集微生物，适用于处理微污染水体。
关键字：预处理；MBBR；低氨氮微污染水；硝化；悬浮载体；菌群富集；
Study on nitrification performance of MBBR Process in treatment of micro polluted water
HAN Wenjie, LIU Kai, YANG Xiaomei, LIU Yilong, SU Dandan, WU Di
(Qingdao Spring Water Treatment Co., Ltd, Qingdao 266510, China)
Abstract: The effect of the moving bed biofilm reactor (MBBR) process to the micro-polluted water in the river was studied, and the biological tankadopted the treatment process of 'six-stage MBBR biological oxidation'. The results showed that, the NH4+-N and COD removal rates reached 57.43%and 20.27% respectively, the effluent quality reached the surface water class III standard of GB 38382002, and the simultaneous nitrification anddenitrification (SND) ratio was 7.97%. Nitrification test of high NH4+-N content (mass concentration was 7 mg/L) for suspended carrier was carried out,and the maximum NH4+-N volume load was 65 g/(m3·d). Proteobacteria was the dominant phylum in the biofilm of the suspended carrier, with an average relative abundance of 55.40%, the average relative abundance of denitrifying bacteria was 13.36%, which provided a microscopic guarantee for the occurrence of the SND. The system had a high abundance of bacteria that could degrade the refractory organic matter, which provided a guarantee for the stable COD of micro polluted water to reach the standard. MBBR process occupies less space, it can be screened and specialized for enrichment of microorganisms, and is suitable for treating micro-polluted water. Nitrification test of high matrix (NH4+-N 7 mg·L-1) for suspended carrier was carried out, and the maximum volume load is 0.065 kgNH4+-N(m3·d)-1. The results of microbial assay showed that Proteobacteria is the dominant phylum in the biofilm of the suspended carrier, with an abundance of 55.40% on the suspended carrier, the proportion of denitrifying bacteria on the suspended carrier is 13.36%, which provides a microscopic guarantee for the occurrence of the simultaneous nitrification and denitrification (SND). The system has a high abundance of bacteria that can degrade the refractory organic matter, which provides a guarantee for the stable COD concentration of micro polluted water to reach the standard. MBBR process occupies less space, it can be screened and specialized for enrichment of microorganisms, and is suitable for treating micro-polluted water.
Keywords: Pretreatment; MBBR; micro-polluted water with low ammonia nitrogen; nitrification; suspension carrier; bacterial enrichment
引言
河道水源污染问题成为近期全民关注的焦点。水利部 2003 年在全国开展了水资源质量评价，结果表明 38.2%水体已丧失使用价值[1]。生物净化利用了微生物自身代谢消耗功能，凭借其能耗低、投资省、处理效果明显的优点，在国内外得到了广泛的应用[2]。日本广岛通过向排水渠中布设细绳状生物悬浮载体进行微污染水处理项目，COD、SS的去除率分别达到 2%～32%和 16%～53%[1]。国内徐斌等为考察移动床生物膜反应器（MBBR）对黄浦江微污染水的预处理效果而进行了中试，结果显示，悬浮载体最大硝化容积负荷达 72 g/(m3·d)[3]。李璐等利用生物接触氧化工艺及分段进水生物接触氧化工艺对河道微污染水进行了处理，COD 去除率在 50%左右[4-5]。以 MBBR 为代表的生物接触氧化技术应用于微污染河水净化受到了越来越多的关注[6]。
江苏某自来水厂，设计取水量 300×103 m3/d，沿线农业面源、城镇化、工业化发展使得水源地水质污染严重，污染物负荷超出其环境承载能力，原水呈现有机物污染特征，主要表现在COD 和NH4+-N 的质量浓度等污染指标季节性分别高达9 mg/L和1.8 mg/L，无法达到自来水厂规定的进水标准。2015年，该市提出利用现有弃土区和农田建设饮用水安全工程，新建原水预处理厂以改善原水水质，使原水COD、NH4+-N 指标达到GB 3838－2002的地表水III类标准，以满足自来水厂的进水水质要求[7]。
本研究针对江苏某原水预处理项目，考察了MBBR 工艺应用于河道微污染水的处理效果，以期为众多微污染水处理项目在工艺选择及运行指导上提供参考。
1 工艺流程选择
本项目的重点在于保证COD及NH4+-N含量的达标，工艺选择极为重要。针对COD的去除，传统的给水处理工艺（混凝、沉淀和过滤）在保证饮用水水质方面起到了重要作用，主要是去除相对分子质量大于10×106以上的有机物，对低分子量有机物去除率较低，特别是对于相对分子质量小于0.5×106的有机物，几乎没有去除能力。生物氧化法借助微生物群体的新陈代谢活动，可去除传统处理工艺不能有效去除的低分子量有机物污染物，对提高整个给水处理工艺对有机物的去除效果有着重要意义，成为传统饮用水处理方法的重要补充。
针对NH4+-N的去除工艺主要有4种：氨吹脱、折点加氯、选择性离子交换、生物硝化和反硝化。目前多采用生物硝化法，涉及工艺主要有传统活性污泥法和生物接触氧化，MBBR工艺兼具2种工艺的优点而成为一种新型、高效的复合工艺，因而在微污染水的处理上极具潜力，且生物脱氮成本较低，是饮用水水处理过程中去除NH4+-N的主要手段。利用MBBR 纯膜工艺处理河道中微量NH4+-N，可保障出水稳定达标。
