Polyamide 6 microplastics facilitate methane production during anaerobic digestion of waste activated sludge
Polyamide 6 microplastics facilitate methane production during anaerobic digestion of waste activated sludge
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DOI：
10.1016/j.cej.2020.127251
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发表时间：
2021-01-15
影响因子：
15.1
通讯作者：
Zhou, Yaoyu
中科院分区：
文献类型：
--
作者：
Chen, Hongbo;Tang, Mengge;Zhou, Yaoyu
聚酰胺6（PA 6）作为一种典型的新兴微塑料污染物，在污水处理厂中经常出现，但其对废水活性污泥（WAS）厌氧消化过程的影响尚未完全了解。通过生化产甲烷测试和模型分析，确定了PA 6微塑料（5-50粒/g TS）在厌氧消化产甲烷过程中的关键作用，并通过监测代谢中间产物的转化、关键酶的活性以及渗滤液己内酰胺（CPL）的影响，探讨了其作用机制。与通常抑制厌氧消化的其他微塑料不同，由于CPL的作用，PA 6显著提高了甲烷产量。10颗粒PA 6/g TS的存在使甲烷产量提高了39.5%（从124 +/- 6升CH 4/kg VS提高到173 +/- 8升CH 4/kg VS）。基于模型的分析表明，PA 6促进甲烷生产潜力和挥发性固体破坏。PA 6对WAS的增溶和水解作用较小，而CPL的淋溶促进了WAS的酸化和产甲烷，这是PA 6提高WAS产甲烷量的主要原因。这些发现表明，PA 6对WAS厌氧消化的毒性低于其他微塑料，这促使人们了解微塑料在污水处理厂中的双重作用。
Polyamide 6 (PA6) as a typical emerging microplastic pollutant has frequently been featured in wastewater treatment plants (WWTPs), yet its associated impact on waste activated sludge (WAS) anaerobic digestion process have not been fully understood. This study identified the key role of PA6 microplastics (5-50 particles/g TS) in methane production during anaerobic digestion through biochemical methane production testing and model-based analysis, and explored the mechanism involved by monitoring the conversion of metabolic intermediates, the activity of key enzymes, and the effects of leachate caprolactam (CPL). Unlike other microplastics that normally inhibit anaerobic digestion, PA6 significantly enhanced methane production due to the effect of CPL. The presence of 10 particles PA6/g TS improved methane production by 39.5% (from 124 +/- 6 to 173 +/- 8 L CH4/kg VS). Model-based analysis showed that PA6 promoted methane production potential and volatile solids destruction. PA6 offered marginal effect on the solubilization and hydrolysis of WAS, the leaching of CPL improved acidification and methanogenesis due to the promotion of key enzyme activities, which is the main reason why PA6 increased methane production. These findings indicate that PA6 is less toxic to WAS anaerobic digestion than other microplastics, which prompts an understanding of the dual role of microplastics in WWTPs.