Advancing wastewater treatment with Azolla filiculoides waste: a comprehensive review of adsorption applications

Abstract

ABSTRACT Rapid urbanisation and industrialisation have led to severe environmental pollution from the accumulation of wastewater and poorly treated or untreated industrial wastes. Traditional waste treatment methods are often expensive and ineffective in fully removing contaminants. As a result, there is a growing interest in exploring natural and cost-effective treatment systems. One such potential solution is the use of the aquatic fern, Azolla filiculoides Lam which has shown promise as a readily available, free-floating biomass that can effectively adsorb and remove metal ions and other pollutants from water. This review paper delves into the untapped potential of A. filiculoides bio-adsorbent, as a highly effective and eco-friendly solution for removing organic and inorganic pollutants from wastewater. The review also identified future research opportunities and recognised existing limitations in our understanding of A. filiculoides for wastewater treatment. Various aspects of its efficiency, including equilibrium isotherm, kinetics, thermodynamics, desorption, and adsorbent reclamation, have been studied. The research highlights A. filiculoides’s impressive maximum specific surface area of 484 m²/g, enabling it to adsorb a wide range of contaminants effectively. Among the studied adsorption models, Langmuir and pseudo-second-order models best described the adsorption phenomena on this bio-adsorbent. Thermodynamic evaluations further confirm that its waste can be utilised to construct feasible and spontaneous adsorption systems for efficient pollutant removal. It shows great promise as a bio-adsorbent to mitigate the adverse environmental impacts of wastewater pollution promoting sustainable water management practices. Further research and application of A. filiculoides in wastewater treatment could lead to substantial environmental benefits.