State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, PR China.
State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, PR China.
Water Res. 2019 Oct 15;163:114881. doi: 10.1016/j.watres.2019.114881. Epub 2019 Jul 17.
Alkaline (especially pH 10) anaerobic fermentation of waste activated sludge (WAS) has been reported to be an effective approach for hydrogen production through inhibiting the homoacetogenesis and methanogenesis. However, the potential effect of the widespread microplastics in sludge on the performance of hydrogen production has never been reported. To fill this knowledge gap, the dominant polyethylene terephthalate (PET) microplastics in WAS were selected as the model microplastics to evaluate their influences on hydrogen production during alkaline anaerobic fermentation of WAS as well as the key mechanisms involved. Experimental results demonstrated that hydrogen production from WAS decreased in the presence of PET microplastics (i.e., 10, 30 and 60 particles/g-TS) compared to the control, with the hydrogen yield at 60 particles/g-TS being only 70.7 ± 0.9% of the control. Although the hydrogen consumption (i.e., homoacetogenesis and methanogenesis) was restrained under alkaline (pH 10) condition, PET microplastics inhibited hydrolysis, acidogenesis and acetogenesis in alkaline WAS anaerobic fermentation, leading to the inhibitory effect on hydrogen production. This was further confirmed by the microbial analysis, which clearly showed PET microplastics caused the shift of the microbial community toward the direction against hydrolysis-acidification. Mechanism studies revealed that PET microplastics carried on their negative influence mainly through leaching the toxic di-n-butyl phthalate (DBP). The reactive oxygen species (ROS) and live/dead staining tests indicated that the increased ROS was induced by PET microplastics, causing more cells dead, which further resulted in the decreased production of hydrogen.
碱性（尤其是 pH 值为 10）厌氧发酵废活性污泥 (WAS) 已被报道通过抑制同型产乙酸作用和产甲烷作用是一种有效的产氢方法。然而，污泥中广泛存在的微塑料对产氢性能的潜在影响尚未有报道。为了填补这一知识空白，选择 WAS 中占主导地位的聚对苯二甲酸乙二醇酯 (PET) 微塑料作为模型微塑料，评估其在碱性厌氧发酵 WAS 过程中产氢过程中的影响以及涉及的关键机制。实验结果表明，与对照相比，在存在 PET 微塑料（即 10、30 和 60 个颗粒/g-TS）的情况下，WAS 中的产氢量减少，而 60 个颗粒/g-TS 的产氢量仅为对照的 70.7±0.9%。尽管在碱性（pH 10）条件下抑制了氢消耗（即同型产乙酸作用和产甲烷作用），但 PET 微塑料抑制了碱性 WAS 厌氧发酵中的水解、产酸和产乙酸作用，导致产氢受到抑制。这通过微生物分析进一步得到证实，该分析清楚地表明，PET 微塑料导致微生物群落向不利于水解酸化的方向转变。机理研究表明，PET 微塑料主要通过浸出有毒的邻苯二甲酸二丁酯 (DBP) 来发挥其负面影响。活性氧 (ROS) 和死活染色试验表明，PET 微塑料诱导 ROS 增加，导致更多细胞死亡，从而进一步导致产氢减少。
