State of the art and sustainability of natural coagulants in water and wastewater treatment

Natural coagulants have shown its coagulation efficiency as reported in a substantial number of research articles. However, the acceptance and widespread application of natural coagulants in water industry is still low. It is necessary to conduct a review to boost the potential of using natural coagulants by highlighting the current development and the efforts for improving the capability of natural coagulants, including showing the compatibility of natural coagulants with other treatment technologies in integrated/hybrid treatment process; the modification of natural coagulants for marked improvement in coagulation performance efficiency; the possibility of hybridizing natural coagulants with other types of coagulants; the improvement of extraction and purification approaches for high purity of natural coagulants; and the synthesis of multifunctional natural coagulants. Though the current progress of natural coagulants is quite encouraging, perspectives from sustainability assessment showed that the acceptance and commercialization of natural coagulants are hindered by two main challenges: practicality and feasibility of real field application and sustainability of using natural coagulants overlooking technical, environmental, economic, and social aspects. Future research focusing on these issues may help to clarify the uncertainties shrouded on natural coagulants and at the same time shifting the water industry to be more sustainable.