污泥蚯蚓堆肥中纳米CuO毒性削减机理及生物相的应激响应机制研究

Due to extensive applications of metal oxide nanoparticles (NPs), their discharge in wastewater has increased in recent years. This has also resulted in their enrichment in sludge due to adsorption, flocculation, and sedimentation processes. Their accumulation in the sludge adversely affects the conventional sludge treatment processes. Due to the bacteriostatic effect of Cu2+, CuO NPs have severe impact on the anaerobic digestion of wastewater sludge. This has hindered the normal operation of the anaerobic digestion process, and therefore, exploration of methods to treat the excess sludge polluted by CuO NPs has become an urgent problem to deal with. The current research project intends to utilize the vermicomposting method to treat excess sludge polluted by CuO NPs and to investigate the effects of CuO NPs on factors which control the stabilization and reclamation of vermicomposting process. The study is intended to be conducted with the purpose of treatment and sustainable utilization of excess sludge polluted by CuO NPs, with the condition that the final content of heavy metal Cu will meet the adopted standards for landuse applications. The study aims to analyze the stress response mechanism of earthworms and microorganisms to the CuO NPs toxicity during composting by employing methods, such as metabonomics and metaproteomics. The work aims to reveal the reduction mechanism for the CuO NPs toxicity during vermicomposting by utilizing the excitation emission matrix fluorescence combined with the parallel factor analysis (EEM-PARAFAC) method. With the intended study, we expect to provide a feasible and effective treatment method for the disposal and sustainable utilization of excess sludge polluted by CuO NPs.

纳米金属氧化物的广泛应用导致其在污水中大量排放，并最终富集于剩余污泥中，影响污泥常规处理工艺。由于Cu2+本身的抑菌效应，使得纳米CuO（CuO NPs）对污泥的常规处理工艺的危害性更为严重，因此CuO NPs污染的污泥处理与处置成为亟待解决的难题。本项目从实现CuO NPs污染的污泥的资源化利用与污泥中CuO NPs的毒性削减两个方面着手，利用蚯蚓堆肥处理CuO NPs污染的污泥，在保证重金属Cu含量满足土地利用安全性的前提下，考察CuO NPs对污泥蚯蚓堆肥的关键指标所产生的影响，论证CuO NPs污染的污泥蚯蚓堆肥资源化利用的可行性；借助代谢组学与宏蛋白质组学研究手段，解析堆肥中蚯蚓与微生物对CuO NPs毒性的应激响应机制；采用三维荧光光谱结合平行因子分析方法，揭示蚯蚓堆肥对CuO NPs毒性的削减作用机理，为CuO NPs污染的剩余污泥的处理与资源化利用提供行之有效的处理方法。

纳米氧化铜（CuO NPs）由于其磁性、热阻、抗菌性以及光催化等方面的特性，已经广泛应用各个领域，然而其在生产、运输、使用以及报废过程中不可避免的排放到环境当中，造成危害。作为污水向环境水体排放的最后一道屏障，污水厂成为水体中的纳米金属氧化物的最终去向，并通过吸附、凝聚以及沉淀作用富集在剩余污泥当中，从而对剩余污泥的处理与处置产生危害。. 本项目利用蚯蚓堆肥处理CuO NPs污染的剩余污泥，考察了CuO NPs浓度与污泥蚯蚓堆肥关键因素之间的相互关系，明确了CuO NPs浓度对污泥蚯蚓堆肥效果的影响；解析了堆肥过程中CuO NPs浓度对微生物群落结构的影响及蚯蚓对CuO NPs毒性的应激响应机制；采用BCR连续提取法及三维荧光光谱结合平行因子分析技术，研究了CuO NPs在蚯蚓堆肥过程中的动态演变规律及Cu2+与有机物的结合特性，从而阐明了蚯蚓堆肥对CuO NPs的毒性削减作用机理。堆肥结束后基质中CuO NPs中不稳定形态的Cu所占的比例显著降低，腐殖化程度提高、速效氮、速效磷等营养元素大幅增加，即蚯蚓堆肥能够降低受CuO NPs的生态毒性并实现受污染污泥的减量化与资源化。. 基于上述工作，本研究发表学术论文3篇，申请国家发明专利2项，为受CuO NPs及其他纳米金属氧化物污染的剩余污泥提供了理论研究基础与行之有效的处理方法，为解决剩余污泥的二次污染与削减纳米金属氧化物的生态毒性提供了新的思路，具有一定的实际意义与应用前景。