Coagulation removal and photocatalytic degradation of microplastics in urban waters

Abstract

• The coagulation removal and photocatalytic degradation of MPs in urban water are reviewed. • The mechanisms of coagulation and photocatalysis removal are summarized. • The conditions and characteristics of MPs can significantly affect coagulation removal. • The knowledge gaps and prospect of coagulation and photocatalytic removal are given. The global concerns to the environmental pollution and health risks by microplastics (MPs) urgently require action to develop effective and sustainable processes to deal with this problem. Coagulation removal and photocatalytic degradation, considered as cost- and energy-effective techniques, have attracted growing attention to remove MPs from urban waters. However, its removal behavior and degradation mechanism have not been systematically summarized. Therefore, the recent progress on coagulation and photocatalysis for MPs removal was comprehensively reviewed in this study. Particularly, the effects of parameters (e.g., type and dosage of coagulant, environmental conditions, characteristics of MPs and catalyst type, etc) and removal mechanisms were commendably discussed. Moreover, the challenges of current techniques application process and the potential coping strategies were also put forward. This review will not only help to deeply understand the detailed processes and mechanisms for removing MPs by coagulation and photocatalysis but also provide constructive information and useful data for future researches relevant to the enhanced removal of MPs from urban waters.