模拟光伏曝气硝化SBR自动控制策略及其AOB群落结构

采用模拟光伏曝气硝化SBR(序批式反应器)去除污水中的NH₄+-N,探究适用于反应器硝化过程的自动控制策略,并采用PCR(聚合酶链式反应)和TA克隆考察反应器内AOB(氨氧化细菌)群落结构. 结果表明,反应器可在15 d内成功启动,NH₄+-N平均去除率达97.8%,出水ρ(NH₄+-N)平均值为0.67 mg/L. ρ(DO)和pH变化曲线上均存在指示氨氧化终点的特征点——氨谷和DO肘,可通过d pH/d t(pH导数)准确判断氨氧化终点,而d ρ(DO)/d t〔ρ(DO)导数〕信号波动较大. Nitrosomonas为反应器内绝对优势AOB,但AOB的群落结构并不稳定,只有2个OTU(分类操作单元)在7个克隆文库(d15、d30、d45、d60、d75、d90和d105)中均有分布,AOB群落结构的平均变化率(Δ₁₅ d)为22.1%±16.5%,20%的AOB累积相对丰度随时间变化范围为40.0%~60.7%,表明维持硝化SBR稳定运行的关键是AOB的多样性及群落结构的动态变化,而不是某些特定的AOB种. 

Real-Time Control and Ammonia Oxidizing Bacterial Community Dynamic in a Simulated PV Aeration SBR for Nitrification

A simulated PV aeration system without batteries was proposed for ammonium elimination. The correspondence of pH and dissolved oxygen (DO) with the nitrification process was identified for real-time control purposes. Moreover, the ammonia oxidizing bacterial (AOB) community structure was evaluated based on PCR and TA cloning. The results showed that the novel reactor was started up successfully in 15 days. Subsequently, the mean ammonium removal rate achieved was 97.8%, and the mean ammonium concentration in the effluent was 0.67 mg/L, indicating that the system was functionally stable. Significant feature points associated with the completion of NH₄+-N oxidation were detected in pH and DO profiles (i.e., “ammonia valley” and “DO elbow”). The “ammonia valley” could be readily detected by the first derivative of pH, however, the “DO elbow” could hardly be detected in the original signals of derivative of DO, since the signals were interfered with by a substantial amount of high-frequency noise. Phylogenetic analysis indicated that Nitrosomonas was the dominant AOB; however, the AOB community structure was unstable. There were only two OTUs shared by the seven clone libraries. Cluster analysis demonstrated that very distinct bacterial communities occurred in the SBR during the operational period. Moving window analysis showed that the average change rate of AOB community (every 15 days) was 22.1%±16.5%. Based on the Pareto-Lorenz curves, only a small group of AOB species played a numerically dominant role in the ammonium oxidation of the reactor. The remaining less dominant species were speculated to constitute a reserve of AOB, which could proliferate to replace the dominant species. In conclusion, the reactor with functional stability did not correlate with stable AOB communities, and AOB diversity and community dynamic rather than the presence of a specific AOB species ensured nitrification functionality.