A review on phenolic wastewater remediation using homogeneous and heterogeneous enzymatic processes: Current status and potential challenges

Water pollution is one of the serious environmental problems threatening the sustainable development of human civilization. Many phenolic compounds are hazardous, toxic, endocrine disrupting, mutagenic, teratogenic, and/or carcinogenic. They also cause severe damages to marine ecosystem. Accordingly, their removal from polluted wastewaters prior to its discharge to the environment is a mandatory task. Several processes have been proposed for treating phenol-contaminated waters. Among the proposed treatment processes is the enzymatic method. Thus, the key objective of this review article is to present the recent progress in utilizing peroxidases and laccases for the remediation of phenolic wastewaters. Both homogenous and heterogeneous enzymatic processes to remove different phenolic pollutants from wastewaters will be reviewed. Recent studies on the effects of the key operational factors (i.e., temperature and pH) will also be presented. Additionally, emerging trends in enzymatic wastewater treatment will be addressed. The obstacles and challenges facing the large scale applications of enzymatic remediation of phenolic wastewaters will be highlighted. More importantly, several ideas for addressing the limitations of the process and improving its efficiency and viability will be provided. These ideas might form the basis for future studies on developing a more effective enzymatic process for treating wastewaters contaminated with phenolic pollutants, which is a growing environmental problem worldwide.