Wang Baixiang, Hu Heping, Huang Shaobin, Yuan Haiguang, Wang Yanling, Zhao Tianyu, Gong Zerui, Xu Xinyue
South China University of Technology China
China Water Resources Pearl River Planning Surveying & Designing Co. Ltd China.
RSC Adv. 2023 Jun 26;13(28):19265-19275. doi: 10.1039/d3ra02749j. eCollection 2023 Jun 22.
Nitrate (NO) and sulfate (SO) often coexist in organic wastewater. The effects of different substrates on NO and SO biotransformation pathways at various C/N ratios were investigated in this study. This study used an activated sludge process for simultaneous desulfurization and denitrification in an integrated sequencing batch bioreactor. The results revealed that the most complete removals of NO and SO were achieved at a C/N ratio of 5 in integrated simultaneous desulfurization and denitrification (ISDD). Reactor Rb (sodium succinate) displayed a higher SO removal efficiency (93.79%) with lower chemical oxygen demand (COD) consumption (85.72%) than reactor Ra (sodium acetate) on account of almost 100% removal of NO in both Ra and Rb. Ra produced more S (5.96 mg L) and HS (25 mg L) than Rb, which regulated the biotransformation of NO from denitrification to dissimilatory nitrate reduction to ammonium (DNRA), whereas almost no HS accumulated in Rb which can avoid secondary pollution. Sodium acetate-supported systems were found to favor the growth of DNRA bacteria (); although denitrifying bacteria (DNB) and sulfate-reducing bacteria (SRB) were found to co-exist in both systems, Rb has a greater keystone taxa diversity. Furthermore, the potential carbon metabolic pathways of the two carbon sources have been predicted. Both succinate and acetate could be generated in reactor Rb through the citrate cycle and the acetyl-CoA pathway. The high prevalence of four-carbon metabolism in Ra suggests that the carbon metabolism of sodium acetate is significantly improved at a C/N ratio of 5. This study has clarified the biotransformation mechanisms of NO and SO in the presence of different substrates and the potential carbon metabolism pathway, which is expected to provide new ideas for the simultaneous removal of NO and SO from different media.
硝酸盐（NO）和硫酸盐（SO）经常共存于有机废水中。本研究考察了不同底物在不同碳氮比下对NO和SO生物转化途径的影响。本研究采用活性污泥法，在一体化序批式生物反应器中同时进行脱硫和反硝化。结果表明，在一体化同步脱硫反硝化（ISDD）中，碳氮比为5时，NO和SO的去除最为彻底。由于Ra和Rb中NO的去除率几乎都达到了100%，反应器Rb（丁二酸钠）的SO去除效率更高（93.79%），化学需氧量（COD）消耗量更低（85.72%）。Ra比Rb产生更多的S（5.96 mg/L）和HS（25 mg/L），这将NO的生物转化从反硝化调节为异化硝酸盐还原为铵（DNRA），而Rb中几乎没有HS积累，可避免二次污染。发现以乙酸钠为支撑的系统有利于DNRA细菌的生长（）；尽管在两个系统中都发现反硝化细菌（DNB）和硫酸盐还原细菌（SRB）共存，但Rb具有更大的关键分类群多样性。此外，还预测了两种碳源的潜在碳代谢途径。丁二酸和乙酸都可以通过柠檬酸循环和乙酰辅酶A途径在反应器Rb中生成。Ra中四碳代谢的高发生率表明，在碳氮比为5时，乙酸钠的碳代谢显著改善。本研究阐明了不同底物存在下NO和SO的生物转化机制以及潜在的碳代谢途径，有望为从不同介质中同时去除NO和SO提供新思路。
