污泥厌氧消化中典型纳米颗粒对微生物活性与EPS去除的影响机制

Worldwide application of nanotechnology lead to an increasingly release of nanoparticles in wastewater, which potentially impairs the operation the anaerobic digestion of sewage sludge. Thus, research of the inhibition of nanoparticles on the biomass in sludge digestion is therefore of great significance. To clarify the inhibition mechanisms of typical nanoparticles (CuO, ZnO, AgNO3) on the sludge digestion, batch adsorption tests and multiple fluorescence labeling/confocal laser scanning microscope (CLSM) were applied to study the attachment characteristics of nanoparticles on the sludge extracellular polymeric substances (EPS) firstly, and to analyze the correlation between the attachment methods and its corresponding negative effect on the chemical structure of biomass. Secondly, high-throughput sequencing was used to clarify the changes of the microbial groups and biomass activities in the digestion system, to reveal the negative effects of nanoparticles on the metabolic pathways of the sludge organics. Moreover, by using the XAD fractionation technology, an three-dimensional structure-activity relationship among the EPS fractions reduction, the biomass activity and the characteristics of nanoparticles in the anaerobic digestion system was constructed. Finally, the index for poor operation of digestion system was also built under the condition of nanoparticels additive. The investigation will provide theoretical basis as well as technical support for the steady-state operation of digestion, which could deal with the negative effect of typical nanoparticles.

由于随排水系统进入污水处理厂污泥的纳米颗粒会显著抑制微生物活性、进而制约污泥厌氧消化系统的高效运行，因此开展纳米颗粒对厌氧消化效能抑制机制的研究十分必要。本项目以不同粒径的纳米CuO、ZnO、AgNO3为研究对象，拟采用静态吸附实验、荧光标记-激光共聚焦显微等测试手段，深入分析不同粒径纳米颗粒在污泥胞外聚合物(EPS)上的附着行为、形态特征及析出规律，阐明该过程与污泥微生物絮体细胞结构破坏的相关性；借助于DNA高通量测序技术，揭示典型纳米颗粒对厌氧消化系统微生物活性抑制和微生物群落结构影响的作用机制，进而解析污泥有机物可能的代谢途径；结合XAD树脂分级技术，构建消化系统中纳米颗粒特性、污泥EPS组分去除特征、微生物活性间的三维构效关系，获取纳米颗粒存在时污泥厌氧消化系统稳定运行的评判指标。该研究成果可为典型纳米颗粒存在条件下污泥厌氧消化系统的高效运行提供理论依据和技术支撑。

本项目以不同粒径的纳米CuO、ZnO为研究对象，拟采用静态吸附实验、荧光标记-激光共聚焦显微等测试手段，深入分析不同粒径纳米颗粒在污泥胞外聚合物(EPS)上的附着行为、形态特征及析出规律，阐明该过程与污泥微生物絮体细胞结构破坏的相关性；借助于DNA高通量测序技术，揭示典型纳米颗粒对厌氧消化系统微生物活性抑制和微生物群落结构影响的作用机制，进而解析污泥有机物可能的代谢途径；结合XAD树脂分级技术，构建消化系统中纳米颗粒特性、污泥EPS组分去除特征、微生物活性间的三维构效关系。项目首先揭示了重金属离子/纳米颗粒在污泥上作用的机制及机理，得出了Cu2+较Zn2+在活性污泥、厌氧颗粒污泥和厌氧絮体污泥EPS上的吸附效能明显较高，并且厌氧颗粒污泥对Zn2+和Cu2+离子的吸附能力明显高于活性污泥和厌氧絮体污泥。活性污泥和厌氧絮体污泥中疏水性的组分对Zn2+和Cu2+离子的吸附能力明显高于其对应的亲水性组分，但是厌氧颗粒污泥中的亲水性组分对金属离子的吸附能力要高于疏水性组分。活性污泥EPS和厌氧颗粒污泥EPS对纳米CuO的吸附能力明显高于纳米ZnO(1.31 g/g VS vs 0.53 g/g VS)，纳米颗粒物粒径越小，污泥EPS对其的吸附能力更高。在10 d的HRT条件下，EPS中HPO-A组分的水解为厌氧消化过程中有机物降解的主要限速步骤，而在20 d的HRT条件下，消化上清液中HPI组分的生物降解速度，特别是与蛋白质类相关的HPI的生物降解过程成为厌氧消化过程中有机物降解的最主要限制性因子。Cu2+对厌氧消化的效能抑制较强，相对应的纳米CuO对厌氧消化的效能也较强。上述金属离子及纳米颗粒对厌氧消化的抑制主要与对系统中产甲烷菌的活性抑制有关。纳米颗粒的加入，将抑制甲烷八叠球菌属(Methanosaeta)和Archaea产甲烷菌属的活性。