Zhao Weixin, Hu Tianyi, Ma Hao, He Shufei, Zhao Qingliang, Jiang Junqiu, Wei Liangliang
State Key Laboratory of Urban Water Resources and Environment (SKLUWRE), School of Environment, Harbin Institute of Technology, Harbin 150090, China.
State Key Laboratory of Urban Water Resources and Environment (SKLUWRE), School of Environment, Harbin Institute of Technology, Harbin 150090, China.
Sci Total Environ. 2023 Nov 25;901:166551. doi: 10.1016/j.scitotenv.2023.166551. Epub 2023 Aug 24.
Microplastics are ubiquitous in the natural environment, which inevitably affect the relevant biochemical process. Nevertheless, the knowledge about the impacts of microplastics on organics transformation and corresponding microbial metabolism response in anaerobic environment is limited. Here, polystyrene (PS) microplastics were selected as model microplastics to explore their potential impacts on organics transformation, microbial community and metabolic pathway during sludge anaerobic digestion system operation. The results indicated that the PS microplastics exhibited the dose-dependent effects on methane production, i.e., the additive of 20-40 particles/g TS of PS microplastics improved the maximum methane yield by 3.38 %-8.22 %, whereas 80-160 particles/g TS additive led to a 4.78 %-11.04 % declining. Overall, PS microplastics facilitated the solubilization and hydrolysis of sludge, but inhibited the acidogenesis process. Key functional enzyme activities were stimulated under low PS microplastics exposure, whereas were almost severely inhibited due to the increased oxidative stress induced from excess PS microplastics. Microbial community and further metabolic analysis indicated that low PS microplastics improved the acetotrophic and hydrogenotrophic methanogenesis, while a high level of PS microplastics shifted methanogenesis from acetotrophic to hydrogenotrophic pathway. Further analysis showed that the reacted PS microplastics exhibited greater toxicity and ecological than the raw PS microplastics due to that they are more likely to adsorb contaminants. These findings revealed the dosage-dependent relationships between microplastics and organics transformation process in anaerobic environments, providing new insights for assessing the impact of PS microplastics on sludge anaerobic digestion.
微塑料在自然环境中无处不在，不可避免地会影响相关的生化过程。然而，关于微塑料在厌氧环境中对有机物转化及相应微生物代谢响应影响的认识有限。在此，选择聚苯乙烯（PS）微塑料作为模型微塑料，以探讨其在污泥厌氧消化系统运行过程中对有机物转化、微生物群落和代谢途径的潜在影响。结果表明，PS微塑料对甲烷产生呈现剂量依赖性效应，即每克总固体（TS）添加20 - 40个PS微塑料颗粒可使最大甲烷产量提高3.38% - 8.22%，而每克TS添加80 - 160个颗粒则导致产量下降4.78% - 11.04%。总体而言，PS微塑料促进了污泥的溶解和水解，但抑制了产酸过程。在低PS微塑料暴露条件下，关键功能酶活性受到刺激，而由于过量PS微塑料诱导的氧化应激增加，酶活性几乎受到严重抑制。微生物群落及进一步的代谢分析表明，低浓度PS微塑料促进了乙酸营养型和氢营养型甲烷生成，而高浓度PS微塑料使甲烷生成途径从乙酸营养型转变为氢营养型。进一步分析表明，反应后的PS微塑料比原始PS微塑料表现出更大的毒性和生态影响，因为它们更易吸附污染物。这些发现揭示了厌氧环境中微塑料与有机物转化过程之间的剂量依赖关系，为评估PS微塑料对污泥厌氧消化的影响提供了新的见解。
