含氮有机物在污水处理过程中的生物转化机制与模型研究进展

随着市政污水处理厂的提标改造,出水总氮浓度逐渐降低,但溶解性有机氮(Dissolved Organic Nitrogen,DON)在总氮中的占比却越来越高,对含氮消毒副产物的生成和受纳水体富营养化的潜在贡献不可忽视。正因如此,近年来有关污水处理系统中DON的研究不断增加。本文重点综述了污水处理厂DON特征、生成转化规律及其生态影响。目前通过混凝沉淀、消毒等物理化学工艺的联合最高可去除70%左右的进水DON,但生物处理单元的微生物代谢活动会生成新的DON,主要包括氨基酸、聚胺等,其藻类生物可利用性较高。在已有DON模型基础上,本文提出了更加完善的ASM3-DON模型,纳入了包括内源呼吸、细胞生长、微生物产物再利用在内的6个过程,可用于对DON生成转化进行更加精确的模拟。未来围绕污水处理过程的DON研究应重点关注DON的快速精确定量分析、生成转化规律探究以及高效去除方法开发。

Biotransformation and modeling of nitrogeneous organic matter in wastewater treatment processes

In many countries around the world, it is necessary to upgrade municipal wastewater treatment plants (WWTPs) to meet the more stringent discharge limits of nutrients. However, with the decreased total dissolved nitrogen (TDN) in the effluent, the proportion of dissolved organic nitrogen (DON) in TDN is increasing, which potentially contributes to the synthesis of more nitrogenous disinfection byproducts (N-DBP) and the eutrophication of receiving water bodies. As a result, studies on WWTP DON have been increasing in recent years, and this article systematically reviews its characteristics, transformation and ecological consequences. At present, up to 70% of the influent DON can be removed by coagulation, precipitation, disinfection and other combined physical and chemical processes. However, metabolic activities in the biological treatment units generate new DON, including small molecular amino acids and polyamines, which have a relatively high algal bioavailability. We propose a more comprehensive ASM3-DON model, involving six major processes associated with DON biotransformation, including endogenous respiration, cell growth, and reuse of soluble microbial products. The model can be used to predict wastewater effluent DON concentration with increased accuracy. Future research on wastewater DON should focus on developing more rapid and accurate quantification methods, unraveling its formation and transformation mechanisms, as well as developing more efficient removal techniques to reduce effluent DON.