Waste activated sludge (WAS) contains high concentrations of microplastics (MPs), which could serve as vectors of various organic pollutants and heavy metals, causing synergistic transportation and pollution. The application of combined hydrothermal pretreatment (HTP) and anaerobic digestion (AD) has raised growing concerns since the low-temperature hydrothermal treatment could enhance the biogas production of WAS. However, the changes in physicochemical properties, adsorption performances, and effects on AD of MPs by HTP have not been studied. The study used three typical MPs in WAS, and it was found that the HTP (170°C & 30min) increased MPs’ specific surface area and carbonyl index (CI) while decreasing the relative crystallinity. The adsorption capacity to Cd increased through the carbonylation for polyethylene microplastic (PE-MP) and polystyrene microplastic (PS-MP) while decreasing by the dechlorination for polyvinyl chloride microplastic (PVC-MP). Meanwhile, increased hydrophilicity reduced the adsorption capacities of all three typical MPs for ofloxacin. The above results indicated that the HTP could be worth blocking the adsorption of polar MPs for polar pollutants. For the pristine MPs, only PVC-MP at the highest concentration (0.5 g kg⁻¹ VS) significantly (p < 0.05) reduced methane production by 16.2 ± 3.3% of WAS without the HTP. However, the HTP resulted in significant (p < 0.05) inhibition of methane production of WAS at high concentrations of PE-MP and PVC-MP (e.g., 0.1 and 0.5 g kg⁻¹ VS), which was due to the acceleration of the released toxic plastic additives (dibutyl phthalate, dimethyl phthalate, and bisphenol-A). Microbial analysis showed the abundances of vital anaerobes, such as acid-producing bacteria (Acetoanerrobium and Mesotoga), proteolytic bacteria (Proteiniborus), and methanogens (Methanosaeta) clearly decreased with the PE-MP and PVC-MP after the HTP, which might result in the decreased methane production. The study provided deep-insight of MPs’ behaviors during the combined HTP-AD process.

废活性污泥（WAS）含有高浓度的微塑料（MPs），可作为各种有机污染物和重金属的载体，造成协同运输和污染。联合水热预处理 (HTP) 和厌氧消化 (AD) 的应用引起了越来越多的关注，因为低温水热处理可以提高 WAS 的沼气产量。然而，尚未研究 HTP 对 MPs 的物理化学性质、吸附性能和对 AD 的影响的变化。该研究在WAS中使用了三种典型的MP，发现HTP（170°C和30min）增加了MP的比表面积和羰基指数（CI），同时降低了相对结晶度。聚乙烯微塑料（PE-MP）和聚苯乙烯微塑料（PS-MP）的羰基化作用增加了对镉的吸附能力，而聚氯乙烯微塑料（PVC-MP）的脱氯降低了对镉的吸附能力。同时，增加的亲水性降低了所有三种典型 MP 对氧氟沙星的吸附能力。上述结果表明，HTP 可以阻止极性 MPs 对极性污染物的吸附。对于原始 MP，只有最高浓度的 PVC-MP（0.5 g kg 上述结果表明，HTP 可以阻止极性 MPs 对极性污染物的吸附。对于原始 MP，只有最高浓度的 PVC-MP（0.5 g kg 上述结果表明，HTP 可以阻止极性 MPs 对极性污染物的吸附。对于原始 MP，只有最高浓度的 PVC-MP（0.5 g kg^-1 VS) 显着 ( p  < 0.05) 将甲烷产量减少了 16.2 ± 3.3% 的 WAS，没有 HTP。然而， 在高浓度 PE-MP 和 PVC-MP（例如，0.1 和 0.5 g kg ^{-1 VS）下，HTP 对 WAS 的甲烷产生有显着的抑制作用（} p < 0.05） ，这是由于释放有毒塑料添加剂（邻苯二甲酸二丁酯、邻苯二甲酸二甲酯和双酚-A）。微生物分析显示重要厌氧菌的丰度，例如产酸细菌（Acetoanerrabium和Mesotoga）、蛋白水解细菌（Proteiniborus）和产甲烷菌（Methanosaeta) 在 HTP 之后随着 PE-MP 和 PVC-MP 的增加而明显减少，这可能导致甲烷产量减少。该研究深入了解了国会议员在 HTP-AD 联合过程中的行为。