Department of Civil and Environmental Engineering, Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution (Hong Kong Branch) and Water Technology Center, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.
School of Environmental Science & Engineering, Sun Yat-sen University, Guangzhou, China.
Water Res. 2020 May 1;174:115616. doi: 10.1016/j.watres.2020.115616. Epub 2020 Feb 12.
Emission of sulfide and methane from sewerage system has been a major concern for a long time. Sewers are now facing emerging challenges, such as receiving food waste (FW) to relieve the burdens on solid waste treatment. However, the knowledge of the direct impact of FW addition on sulfide and methane production in and emission from sewers is still lacking. In this study, two lab-scale sewer reactors, one without and one with FW addition, were continuously operated to investigate the production of sulfide and methane and microbial communities arising from FW discharge to freshwater sewerage system. The 190-day long-term monitoring and the batch tests on days 69 and 124 suggest that the FW addition has little impact on sulfide production possibly due to the limited sulfate concentration (40 mg S/L) but enhanced methane production by up to 60%. Moreover, cryosection-fluorescence in situ hybridization (FISH) revealed that the FW addition significantly stimulated the accumulation of methanogenic archaea (MA) in sewer biofilms and altered the spatial distributions of sulfate-reducing bacteria (SRB) and MA. Moreover, the relative abundance of MA in biofilms with FW addition was higher than that without FW addition, whereas the relative abundance of SRB was similar. Metabolic pathway analysis for sulfidogenesis and methanogenesis indicates that sufficient substrates derived from the FW addition were biodegraded during fermentation to produce acetate and hydrogen, and consequently facilitate methanogenesis. These findings shed light on the impacts of changes in wastewater compositions (e.g., FW addition) on sulfide and methane production in the freshwater sewerage system for improved policy-making on sewer management.
下水道系统中硫化物和甲烷的排放一直是一个长期存在的问题。下水道现在面临着新的挑战，例如接收食物垃圾（FW）以减轻固体废物处理的负担。然而，FW 加入对下水道中硫化物和甲烷产生和排放的直接影响的知识仍然缺乏。在这项研究中，连续运行了两个实验室规模的下水道反应器，一个没有 FW 加入，一个有 FW 加入，以研究 FW 排放到淡水下水道系统中对硫化物和甲烷产生以及微生物群落的影响。为期 190 天的长期监测和第 69 天和第 124 天的批量测试表明，FW 加入对硫化物的产生几乎没有影响，可能是由于硫酸盐浓度（40mgS/L）有限，但甲烷的产生增加了 60%。此外，冷冻切片-荧光原位杂交（FISH）显示，FW 加入显著刺激了下水道生物膜中产甲烷菌（MA）的积累，并改变了硫酸盐还原菌（SRB）和 MA 的空间分布。此外，FW 加入的生物膜中 MA 的相对丰度高于没有 FW 加入的生物膜，而 SRB 的相对丰度相似。硫化物生成和甲烷生成的代谢途径分析表明，FW 加入提供的足够底物在发酵过程中被生物降解，产生乙酸和氢气，从而促进了甲烷生成。这些发现揭示了废水成分变化（例如 FW 加入）对淡水下水道系统中硫化物和甲烷产生的影响，为下水道管理的政策制定提供了依据。
