Environmental Bio-innovations Group, School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, N1-01a-29, Singapore 639798, Singapore; Advanced Environmental Biotechnology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, Clean Tech One, #06-08, Singapore 637141, Singapore.
Environmental Bio-innovations Group, School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, N1-01a-29, Singapore 639798, Singapore.
Sci Total Environ. 2019 Apr 10;660:11-17. doi: 10.1016/j.scitotenv.2019.01.024. Epub 2019 Jan 4.
This study investigated the initiation and maintenance of nitritation in a membrane bioreactor (MBR) with long solids retention time (SRT) of 43.8 days. Nitritation was initiated within 65 days in the MBR via dissolved oxygen (DO) limitation (<0.5 mg/L). However, nitrite oxidizing bacteria (NOB) (Nitrospira and Nitrobacter) acclimated to the low DO environment and proliferated from day 81, leading to nitrate accumulation. Thereafter, the combined strategy of DO limitation and in-situ generated free nitrous acid (FNA) shock successfully restored and maintained stable nitritation for >70 days. Quantitative polymerase chain reaction (qPCR) results showed that cell abundances of Nitrospira and Nitrobacter decreased by between 50.0 to 68.9% and 60.6 to 96.4%, respectively following the FNA shocks. The maximum ammonium loading rate achieved was 1.81 kg N/(m day) with ammonium removal ratio and nitrite accumulation ratio of over 0.97 and 0.96, respectively. Average emission rate of NO from the MBR was 2.1 ± 0.72% of ammonium removed. FNA shock on day 195 reduced the NO emission by 13.6%. The strategy developed in this study verified that spiked FNA shock together with DO limitation can be used for maintaining nitritation in MBRs with long SRTs. This method can potentially allow for maintaining nitritation at relatively low capital and operating expenditure when treating high concentration ammonium wastewater.
本研究考察了长固体停留时间（SRT）为 43.8 天的膜生物反应器（MBR）中硝化作用的启动和维持。通过溶解氧（DO）限制（<0.5 mg/L），在 MBR 中经过 65 天实现了硝化作用的启动。然而，亚硝酸盐氧化菌（NOB）（Nitrospira 和 Nitrobacter）适应了低 DO 环境，并从第 81 天开始繁殖，导致硝酸盐积累。此后，通过 DO 限制和原位生成的游离亚硝酸（FNA）冲击相结合的策略，成功地恢复并维持了超过 70 天的稳定硝化作用。定量聚合酶链反应（qPCR）结果表明，在 FNA 冲击后，Nitrospira 和 Nitrobacter 的细胞丰度分别降低了 50.0%至 68.9%和 60.6%至 96.4%。最大氨负荷率达到 1.81 kg N/（m·天），氨去除率和亚硝酸盐积累率分别超过 0.97 和 0.96。MBR 中从氨去除的平均 NO 排放率为 2.1±0.72%。第 195 天的 FNA 冲击使 NO 排放减少了 13.6%。本研究中开发的策略验证了，在长 SRT 的 MBR 中，添加 FNA 冲击与 DO 限制相结合可用于维持硝化作用。当处理高浓度氨废水时，这种方法可以在相对较低的资本和运营支出下，潜在地维持硝化作用。
