Engineered technologies for the separation and degradation of microplastics in water: A review

Abstract In recent years, the presence of the group of contaminants, termed as microplastics (MPs) has been recognized as significant water pollutants with considerable potential for exerting adverse impacts on human health and wildlife. Natural attenuation has practically no effect while conventional treatment processes are not capable of entirely removing MPs which are reported to accumulate in the environment, in organisms in the aquatic food web and, potentially reaching humans. This in-depth review critically evaluates the state-of-the-art engineered technologies suitable for the separation and degradation of microplastics in water with potential for real-scale application. The outcomes of the review confirmed that very limited number of studies are reported in this field, the majority from recent years and have focused on using phase-changing processes, including coagulation-flocculation, flotation, and membrane processes. A few other studies have reported the use of chemical or biological digestion, and even fewer, engineered removal using biodegradation, wet oxidation, and advanced oxidation processes. This paper focuses on the type of MPs being removed, the process conditions and the outcomes reported in research literature. The emerging trends in the field are also highlighted as well as the identification of current knowledge gaps and future research directions along with perceptive comments and recommendations related to the application of available technologies for water treatment.