Photocatalytic and biological technologies for elimination of microplastics in water: Current status

Water pollution by microplastics (MPs) has emerged as a significant environmental and public health concern. Several conventional technologies in drinking water and wastewater treatment facilities are capable of capturing a substantial portion of microplastics from surface water; however, only limited methods are available for actual destruction of microplastics. Rate of success is highly variable, and actual mechanisms which result in MP destruction are only partly known. Photocatalysis and microbial degradation technologies show promise at laboratory scale for the transformation of microplastics to water-soluble hydrocarbons, carbon dioxide and, in limited cases, useful fuels. Both photocatalytic and microbial technologies offer the potential for long-term water security and ecological stability and deserve further attention by scientists. Additional research is necessary, however, in identifying more effective semiconductors for photocatalysis, and optimal effective microbial consortia and environmental conditions to optimize microplastic biodegradation. Many more polymer types beyond polyethylene must be studied for degradation, and laboratory-scale research must be expanded to field-scale. This paper provides a comprehensive overview of processes and mechanisms for removing MPs by photocatalysis and microbial technologies. It provides useful data for research dedicated to improved removal of MPs from surface waters.