School of Civil Engineering, Hefei University of Technology, Hefei 230009, China; School of Resources and Environmental Engineering, Hefei University of Technology, Hefei 230009, China.
Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China.
Water Res. 2021 Oct 1;204:117599. doi: 10.1016/j.watres.2021.117599. Epub 2021 Aug 27.
Extensive use of organoarsenic feed additives such as roxarsone has caused organoarsenicals to occur in livestock wastewater and further within anaerobic wastewater treatment systems. Currently, information on the long-term impacts of roxarsone on anaerobic granular sludge (AGS) activity and the underlying mechanisms is very limited. In this study, the response of AGS to long-term loading of roxarsone was investigated using a laboratory up-flow anaerobic sludge blanket reactor spiked with 5.0 mg L of roxarsone. Under the effect of roxarsone, methane production decreased by ∼40% due to the complete inhibition on acetoclastic methanogenic activity on day 260, before being restored eventually. Over 30% of the influent arsenic was accumulated in the AGS and the capability of AGS to prevent intracellular As(III) accumulation increased with time. The AGS size was reduced by ∼30% to 1.20‒1.26 mm. Based on morphology and confocal laser scanning microscopy analysis, roxarsone exposure stimulated the excretion of extracellular polymeric substances and the surface spalling of AGS. High-throughput sequencing analysis further indicated roxarsone initially altered the acidogenic pathway and severely inhibited the acetoclastic methanogen Methanothrix. Acetogenic bacteria and Methanothrix were finally enriched and became the main contributor for a full restoration of the initial methane production. These findings provide a deeper understanding on the effect of organoarsenicals on AGS, which is highly beneficial for the effective anaerobic treatment of organoarsenic-bearing wastewater.
罗硝唑等有机胂饲料添加剂的大量使用，导致其在养殖废水中出现，并进一步在厌氧废水处理系统中出现。目前，关于罗硝唑对厌氧颗粒污泥（AGS）活性的长期影响及其潜在机制的信息非常有限。在这项研究中，使用实验室上流式厌氧污泥床反应器，在其中添加 5.0mg/L 的罗硝唑，研究了 AGS 对罗硝唑长期负荷的反应。在罗硝唑的作用下，由于对第 260 天的乙酸型产甲烷活性的完全抑制，甲烷生成量减少了约 40%，然后最终得到恢复。超过 30%的进水砷被AGS 积累，AGS 防止细胞内 As(III)积累的能力随着时间的推移而增加。AGS 的大小减少了约 30%，至 1.20-1.26mm。基于形态学和共聚焦激光扫描显微镜分析，罗硝唑暴露刺激了胞外聚合物的分泌和 AGS 的表面剥落。高通量测序分析进一步表明，罗硝唑最初改变了产酸途径，并严重抑制了乙酸型产甲烷菌 Methanothrix。随后，产乙酸细菌和 Methanothrix 得到了富集，并成为初始甲烷产量完全恢复的主要贡献者。这些发现提供了对有机胂对 AGS 影响的更深入理解，这对含有机胂废水的有效厌氧处理非常有益。
