School of Computing Engineering and Mathematics, Western Sydney University, Kingswood, NSW, 2747 Australia.
Chemosphere. 2018 Dec;212:744-754. doi: 10.1016/j.chemosphere.2018.07.160. Epub 2018 Aug 21.
Earlier, we reported on soluble microbial products-mediated chloramine decay in nitrifying waters. However, we neither separated the agent(s) nor identified the factors that enhanced the production of chloramine-decaying soluble microbial products (cSMPs). Experiments were conducted by feeding reactor sets (each consisting of five reactors connected in series) with treated water (3-8 mg-DOC.L) obtained from a water treatment plant. The reactors simulated various nitrifying conditions that are experienced in a chloraminated system. In unfiltered samples obtained from nitrified reactors, about 89-93% of the dosed chloramine decayed within 40 h. The cSMP-mediated decay accounted for 21-39% of all chloramine decay in the samples from 0 to 5 mg-C.L fed reactors and 15% in the samples from 7 to 8 mg-C.L fed reactors. Microbial processes (mediated by nitrifiers and/or heterotrophs) and biomass-associated microbial products (BMPs) in insoluble form accounted for 13-21% for the reactors fed with 0-5 mg-C.L and 34% for those fed with 7-8 mg-C.L. The cSMPs were separable with a 30 kDa cut-off membrane but not with 50 or 100 kDa membranes, i.e., they were above 30 kDa but below 50 kDa in size, and were confirmed to be a protein(s). The protein(s) accelerated chloramine decay by accelerating chloramine auto-decomposition and nitrite oxidation. As opposed to the traditional belief, unknown factors accounted for approximately 34-53% in commonly encountered re-chloraminated nitrifying waters (2-5 mg-DOC.L). Understanding the identity and role of these factors - such as cSMPs, BMPs, heterotrophs - will lead to a better control of chloramine.
早些时候，我们报道了可溶微生物产物介导的硝化水中氯胺衰减。然而，我们既没有分离出这种试剂，也没有确定增强产生氯胺降解的可溶微生物产物（cSMP）的因素。实验是通过用取自水处理厂的处理水（3-8mg-DOC.L）喂养反应器组（每个反应器组由五个串联连接的反应器组成）进行的。这些反应器模拟了氯胺系统中经历的各种硝化条件。在从硝化反应器中获得的未经过滤的样品中，大约 89-93%的投加氯胺在 40h 内降解。cSMP 介导的衰减占从 0 到 5mg-C.L 喂养的反应器的样品中所有氯胺衰减的 21-39%，在从 7 到 8mg-C.L 喂养的反应器的样品中占 15%。微生物过程（由硝化菌和/或异养菌介导）和不溶性生物量相关微生物产物（BMP）占 0-5mg-C.L 喂养的反应器的 13-21%，占 7-8mg-C.L 喂养的反应器的 34%。cSMP 可以用 30kDa 截止膜分离，但不能用 50 或 100kDa 膜分离，即它们的大小在 30kDa 以上但在 50kDa 以下，被确认为蛋白质（s）。这些蛋白质（s）通过加速氯胺自动分解和亚硝酸盐氧化来加速氯胺衰减。与传统观念相反，在常见的再氯胺化硝化水中（2-5mg-DOC.L），未知因素约占 34-53%。了解这些因素（如 cSMP、BMP、异养菌）的身份和作用将有助于更好地控制氯胺。
