A review on the significance of Azolla for water and wastewater treatment

Abstract

Industrialization, urbanization, and population growth release many pollutants into water resources. Conventional mechanical wastewater treatment plants require a lot of electricity, are not sufficient to remove all pollutants, and generate a large amount of sludge. Therefore, it is crucial to develop economically accepted and environmentally friendly methods for wastewater treatment. The main advantages of bioremediation over conventional treatment methods include low cost, high effi-ciency, and minimizing the generation of chemical or biological sludge. Aquatic macrophytes can improve water quality by bioaccumulation/biosorption of toxic substances, excess nutrients and metals. Therefore, phytoremediation as a natural system presents itself as an environmentally friendly treatment technology for water remediation. This paper presents recent research on Azolla fern as a phytoremediation agent. Azolla can remove many pollutants from wastewater, including fluoride, ammonium, bisphenol A, dyes, chemical oxygen demand, nitrogen, phosphorus and toxic metals. Azolla is a floating water fern and its biomass produced during phytoremediation has various uses, such as animal feed, human food, production of hydrogen fuel, biogas production, med-icine, water treatment, and biological fertilizer in rice fields. Therefore, phytoremediation with Azolla is recommended as an advanced treatment after conventional wastewater treatment.