Improvements in effluent treatment technologies in Common Effluent Treatment Plants (CETPs): Review and recent advances

Common Effluent Treatment Plants (CETP) are intended for effective treatment of effluent discharged from industrial clusters aiming to support the small/medium scale industries that are deprived of enough resources and technological ability to treat their effluent individually. The present review discusses various processing steps in a typical CETP and their design considerations. The various drawbacks of existing CETPs have been discussed with the need for requirement of novel treatment techniques for their reformation. The different novel approaches discussed include improved coagulation-flocculation, advanced oxidation processes like electrochemical oxidation, cavitation, Fenton, ozonation and photocatalysis. Additionally, possible improvements in the biological treatment methods have also been discussed. Possible applications of bioremediation methods like phytoremediation, constructed wetlands, microbial fuel cells, use of fungi and algae have been highlighted. Membrane technologies and physicochemical treatments coupling with biological oxidation have also been described. For each method, mechanism involved, recent advances and possible recommendations for operating conditions have been provided. The economic aspects of the effluent treatment have also been discussed to aid the transformation of existing CETPs. Overall, the review clearly brings out the important novel techniques having potential to be applied in the existing CETPs and modifications in the existing approaches for their performance enhancement.