Abstract:

Anaerobic/anoxic/oxic (AAO)-biological aerated filter (BAF) is a two-sludge system with different SRT, which can remove nitrogen and phosphorus simultaneously in the low C/N condition. The startup of a pilot-scaled AAO-BAF system with capacity of 40—100 m³·d^-1 used for treating real domestic sewage was studied in this experiment. The AAO and BAF run independently in order to cultivate and acclimate the phosphorus accumulating organisms (PAOs) and nitrifying bacterial biofilms, respectively. When the TP concentration of AAO effluent and concentration of BAF effluent were found keeping stable, the two parts were combined. With this operation strategy, the effluent concentration of COD,, TN, TP, NTU and SS was lower than 50 mg·L^-1, 5 mg·L^-1, 15 mg·L^-1, 0.5 mg·L^-1, 5 NTU and 10 mg·L^-1 in the 58th day, respectively, indicating the successful setup of the pilot-scaled process. Comparing with the lab-scale study, the separate running had more advantage in cultivating PAOs. The formation of natural biofilm in BAF was more convenient than the method of inoculated sludge, but needed longer time. According to the analysis of microbial community diversity, the abundance of nitrobacteria was less than 3% in the AAO system, however, it was higher than 12% on the biofilm in BAF. This experiment can provide a reference for practical engineering application of the process.

Key words: two-sludge system, biofilm, denitrifying phosphorus removal, low C/N ratio, waste water, degradation

摘要：

AAO-曝气生物滤池(BAF)是污泥龄差距较大的双污泥系统,可在低C/N条件下实现氮、磷的同步去除。本试验以低碳氮比的城市污水为处理对象,研究了处理量为40~100 m³·d^-1的大型中试级别的AAO-BAF脱氮除磷工艺的启动运行。通过先使AAO和BAF独立运行以分别培养驯化聚磷菌活性污泥和硝化细菌生物膜,待分别观察到AAO出水TP及BAF 出水NH₄⁺-N浓度稳定后,再将两部分连通运行的策略,使得在第58天时系统出水COD、 、TN、TP、浊度、SS分别小于50 mg·L^-1、5 mg·L^-1、15 mg·L^-1、0.5 mg·L^-1、5NTU、10 mg·L^-1,表明该中试系统已成功启动。与小试研究比较发现,分开运行更有利于聚磷菌的培养驯化;BAF中采用自然挂膜法较接种污泥法更方便,但增加了填料挂膜的时间。根据微生物群落多样性分析,发现AAO中的硝化细菌丰度少于3%,而BAF生物膜上的硝化细菌的丰度占到12%以上。本试验可为该工艺的实际工程应用提供一定参考。

关键词: 双污泥系统, 生物膜, 反硝化除磷, 低C/N, 污水, 降解