Department of Applied Physics and Chemical Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-Cho, Koganei, Tokyo 184-8588, Japan.
Global Innovation Research Institute, Tokyo University of Agriculture and Technology, 3-8-1 Harumi-Cho, Fuchu, Tokyo 185-8538, Japan.
Environ Sci Technol. 2023 Sep 19;57(37):13874-13886. doi: 10.1021/acs.est.3c03002. Epub 2023 Sep 7.
A transition to ammonia recovery from wastewater has started; however, a technology for sustainable nitrogen retention in the form of ammonia and organic carbon removal is still in development. This study validated a microaerophilic activated sludge (MAS) system to efficiently retain ammonia from high-strength nitrogenous wastewater. The MAS is based on conventional activated sludge (CAS) with aerobic and settling compartments. Low dissolved oxygen (DO) concentrations (<0.2 mg/L) and short solids retention times (SRTs) (<5 days) eliminated nitrifying bacteria. The two parallel MASs were successfully operated for 300 days and had ammonia retention of 101.7 ± 24.9% and organic carbon removal of 85.5 ± 8.9%. The MASs mitigated NO emissions with an emission factor of <0.23%, much lower than the default value of CAS (1.6%). A short-term step-change test demonstrated that NO indicated the initiation of nitrification and the completion of denitrification in the MAS. The parallel MASs had comparable microbial diversity, promoting organic carbon oxidation while inhibiting ammonia-oxidizing microorganisms (AOMs), as revealed by 16S rRNA gene amplicon sequencing, the quantitative polymerase chain reaction of functional genes, and fluorescence in situ hybridization of β-proteobacteria AOB. The microbial analyses also uncovered that filamentous bacteria were positively correlated with effluent turbidity. Together, controlling DO and SRT achieved organic carbon removal and successful ammonia retention, mainly by suppressing AOM activity. This process represents a new nitrogen management paradigm.
从废水中回收氨的转变已经开始；然而，一种以氨和有机碳去除形式实现可持续氮保留的技术仍在开发中。本研究验证了一种微需氧活性污泥（MAS）系统，可从高强度含氮废水中有效地回收氨。MAS 基于具有好氧和沉淀隔室的传统活性污泥（CAS）。低溶解氧（DO）浓度（<0.2 mg/L）和短固体停留时间（SRT）（<5 天）消除了硝化细菌。两个平行的 MAS 成功运行了 300 天，氨保留率为 101.7 ± 24.9%，有机碳去除率为 85.5 ± 8.9%。MAS 减少了 NO 排放，排放系数<0.23%，远低于 CAS（1.6%）的默认值。短期阶跃试验表明，NO 表明 MAS 中硝化作用的开始和反硝化作用的完成。平行 MAS 具有相似的微生物多样性，通过 16S rRNA 基因扩增子测序、功能基因的定量聚合酶链反应和β-变形菌 AOB 的荧光原位杂交揭示，促进了有机碳氧化，同时抑制了氨氧化微生物（AOM）。微生物分析还表明，丝状菌与出水浊度呈正相关。总之，通过控制 DO 和 SRT 实现了有机碳去除和成功的氨保留，主要是通过抑制 AOM 活性。这个过程代表了一种新的氮管理范式。
