Chen Song, Zhang Qing-Pei, Zhang Jin-Song, An Na, Yu Hai-Yang, Fu Xiang, Li Zhi-Hua
Key Laboratory of Northwest Water Resource, Environment, and Ecology, MOE, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China.
Xi'an Key Laboratory of Intelligent Equipment Technology for Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China.
Water Res X. 2024 Sep 1;25:100253. doi: 10.1016/j.wroa.2024.100253. eCollection 2024 Dec 1.
Efficient carbon use is crucial for biological nitrogen removal. Traditional aerobic processes can waste carbon sources, exacerbating carbon deficiency. This study explores an anaerobic/oxic/anoxic system with sludge double recirculation to improve nitrogen removal in low C/N wastewater. This system integrated aerobic nitrification after the carbon intracellular storage, separating carbon and nitrogen by denitrifying glycogen-accumulating organisms (DGAOs) with endogenous partial denitrification and Anammox within the anoxic units. A significant efficiency of 91.02±7.01% chemical oxygen demand (COD) was converted into intracellular carbon in anaerobic units, significantly reducing carbon futile oxidation in the aerobic units by effectively separating COD from ammonia. Intracellular storage of carbon sources and microbial adaptation to carbon scarcity prevent futile oxidation of COD in the aerobic units even with short-term high dissolved oxygen (DO), thereby enhancing nitrogen removal under anoxic conditions with sufficient intracellular carbon source. The microbial analysis identified as the dominant anammox bacteria, in combination with the activity of DGAOs and other related microbial communities, accounting for 37.0% of the TN removal. Consequently, the system demonstrated remarkable nitrogen removal efficiencies, achieving 81.3±3.3% for total nitrogen (TN) and 98.5±0.9% for ammonia nitrogen while maintaining an effluent COD concentration of 17.2±9.1 mg/L, treating the low C/N of 4.18 in the influent wastewater. The findings in this study provide a sustainable and energy-saving technique for conventional WWTPs to meet strict discharge standards by avoiding futile oxidation of COD and encouraging anammox contributions.
高效的碳利用对于生物脱氮至关重要。传统的好氧工艺会浪费碳源，加剧碳源不足。本研究探索了一种具有污泥双循环的厌氧/好氧/缺氧系统，以提高低C/N废水中的氮去除率。该系统在碳源细胞内储存后进行好氧硝化，通过缺氧单元内的反硝化聚磷菌（DGAOs）进行内源性部分反硝化和厌氧氨氧化来分离碳和氮。在厌氧单元中，91.02±7.01%的化学需氧量（COD）被高效转化为细胞内碳，通过有效分离COD和氨显著减少了好氧单元中碳的无效氧化。碳源的细胞内储存以及微生物对碳缺乏的适应，即使在短期高溶解氧（DO）条件下也能防止好氧单元中COD的无效氧化，从而在细胞内碳源充足的缺氧条件下提高氮去除率。微生物分析确定 为主要的厌氧氨氧化细菌，结合DGAOs和其他相关微生物群落的活性，占总氮去除量的37.0%。因此，该系统展现出显著的氮去除效率，总氮（TN）去除率达到81.3±3.3%，氨氮去除率达到98.5±0.9%，同时出水COD浓度维持在17.2±9.1 mg/L，处理进水低C/N为4.18的废水。本研究的结果为传统污水处理厂提供了一种可持续且节能的技术，通过避免COD的无效氧化和促进厌氧氨氧化的作用来满足严格的排放标准。
