Zheng Fang, Xu Shaoyi, Chai Wenbo, Liu Dezhao, Lu Huijie
Key Laboratory of Environment Remediation and Ecological Health, Ministry of Education, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China.
Key Laboratory of Equipment and Informatization in Environment Controlled Agriculture, Ministry of Agriculture and Rural Affairs, College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China.
Sci Total Environ. 2022 Aug 1;832:155115. doi: 10.1016/j.scitotenv.2022.155115. Epub 2022 Apr 7.
Sludge alkaline fermentation liquid (SAFL) is an alternative to sodium acetate (NaAc) in enhancing wastewater nitrogen removal. Upon SAFL addition, dissolved organic nitrogen (DON) can be externally introduced or biologically synthesized during nitrogen removal, which is an important precursor to toxic nitrogenous disinfection by-products (N-DBPs). This study aims to evaluate the effects of different carbon source addition on effluent DON concentration, composition, and N-DBP formation potentials. A lab-scale AO system treating real municipal wastewater was operated with NaAc or SAFL as external carbon sources. DON molecules and potential N-DBP precursors were identified by Orbitrap mass spectrometry. Subsequently, major microorganisms contributing to DON biosynthesis were suggested based on metagenomics. It was found that effluent DON was higher with SAFL as the carbon source than NaAc (1.51 ± 0.24 v.s. 0.56 ± 0.08 mg N/L, p < 0.05). Nevertheless, dichloroacetonitrile and nitrosamine formation potentials (7.14 ± 1.02 and 1.57 ± 0.07 μg/mg DON-N, respectively) of the effluent with SAFL addition were 42.79 ± 2.42% and 54.89 ± 1.70% lower than those of NaAc. Protein- and lignin-like compounds were the most abundant DON molecules in the effluent, where alanine, glycine and tyrosine were important precursors to N-DBPs. Azonexus and Flavobacterium spp. were positively correlated with these precursors, and possessed key genes involved in precursor synthesis. SAFL is a promising carbon source, not only for achieving efficient inorganic nitrogen and DON removals, but also for reducing N-DBP formation potentials of chlorinated effluent.
污泥碱性发酵液（SAFL）是一种在强化废水脱氮方面可替代乙酸钠（NaAc）的物质。添加SAFL后，溶解性有机氮（DON）可在脱氮过程中从外部引入或生物合成，而DON是有毒含氮消毒副产物（N-DBPs）的重要前体物质。本研究旨在评估不同碳源添加对出水DON浓度、组成及N-DBP生成潜力的影响。采用以NaAc或SAFL作为外部碳源的实验室规模AO系统处理实际城市污水。通过轨道阱质谱法鉴定DON分子和潜在的N-DBP前体物质。随后，基于宏基因组学推测出对DON生物合成起主要作用的微生物。结果发现，以SAFL作为碳源时的出水DON含量高于以NaAc作为碳源时的含量（分别为1.51±0.24与0.56±0.08 mg N/L，p<0.05）。然而，添加SAFL的出水二氯乙腈和亚硝胺生成潜力（分别为7.14±1.02和1.57±0.07 μg/mg DON-N）比添加NaAc的出水分别低42.79±2.42%和54.89±1.70%。蛋白质类和类木质素化合物是出水中最丰富的DON分子，其中丙氨酸、甘氨酸和酪氨酸是N-DBPs的重要前体物质。固氮弧菌属和黄杆菌属与这些前体物质呈正相关，且拥有参与前体合成的关键基因。SAFL是一种有前景的碳源，不仅可实现高效去除无机氮和DON, 还能降低氯化出水中N-DBP的生成潜力。
