Research progress in the effects of micro (nano) plastics on anaerobic digestion system

Abstract:

Anaerobic digestion (AD) of biomass waste combined with waste activated sludge (WAS),which is characterized by great stability,low energy consumption,and biogas production,can effectively reduce the volume and improve the dehydration of WAS and thus has been widely applied in methane production.However,the AD process is susceptible to external factors such as microplastics (MPs) or nanoplastics (NPs),which can lead to reduced efficiency or even collapse of AD.The AD system needs the interdependence and interaction of the microbial community to keep stable operation in a dynamic equilibrium state,in which phages play a key role.Phages can not only regulate the structure of the microbial community in the sludge and direct the energy flow but also attach to MPs and NPs with bacteria and archaea for transmission.Nevertheless,the effects of MPs and NPs on such a process were underestimated in previous studies.In this paper,we summarize the research progress in the effects of different types and sizes of MPs and NPs on AD systems,with focus on the ecological connections among microbial communities,especially bacteria,archaea,and phages,in anaerobic systems.Furthermore,we put forward novel viewpoints about the effects of MPs and NPs on microbial communities and make an outlook on the future research directions in this field.