JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING, pp.1-40, 2022 (Journal Indexed in SCI Expanded)
Microplastics (MPs) are among the contaminants that have been of
considerable concern in the last decade. One of the most significant
contributors to MPs pollution in the environment is the effluent from
wastewater treatment plants (WWTP). Previous studies showed that high
MPs removal could be achieved in WWTPs. However, the parameters
affecting MPs removal performances have not yet been analyzed for actual
WWTPs. This review critically evaluates the physical, chemical, and
biological treatment processes implemented in the actual WWTPs to remove
MPs and summarizes the parameters affecting the removal. This work
shows that applying physical, chemical and biological methods is
promising: each can be implemented in WWTPs separately, and when
combined, higher MPs removal rates are possible. The main parameters
that affect the MPs removal are the initial MPs load to the WWTPs and
the retention time of MPs in the operational units. MP removal is mainly
observed via the physical sedimentation process, which leads MPs to
accumulate in wastewater sludge; hence treatment parameters and
possibilities of extracting MPs from sludge should be considered to
prevent release of MPs from the WWTPs to the environment. The main
limitation of MP dissapearance estimation in WWTPs is the lack of a
standard MP analysis procedure, which prevents a clear comparison
between MP species identification, characterization, and separation.
More parameters could be linked to the MPs removal if more consistent
and standardized data were obtained from the WWTPs.