Characterization and efficiency of chitosan zinc-oxide nano-adsorbent coated sand filter bed for milk processing industry wastewater treatment

Abstract

Abstract Sustainable wastewater management in an industry is required to avoid widespread water scarcity problems. In this study, chitosan zinc oxide nano-adsorbent was synthesised and obtained a particle size of 88.35 ± 2.89 d. nm. Superadsorbent was developed by coating Chitosan-zinc oxide nanoadsorbent (CZnO) with sand, and characterised by considering its adsorption properties as well as its surface morphology, crystallinity, and functional groups. Batch adsorption experiments were conducted to optimise the process parameters such as CZnO coating dosage, contact time, pH, and initial concentration of biological oxygen demand (BOD) and chemical oxygen demand (COD). Adsorbent efficiency was studied in treating simulated and real milk processing industry wastewater. The percent reduction efficiency of organic pollutants was found to increase with the increase in contact time and coating dosage of CZnO. Adsorption was rapid and occurred within 140 min with different coating dosages. The percent reduction of BOD and COD increased with an increase in pH. The optimum solution pH for adsorption of both the pollutants from synthetic solution was 6.0. The equilibrium concentration of synthetic solution reached 200 mg/L and 250 mg/L for both pollutants. Four regeneration cycles were applied without compromising the adsorption efficiency of the superadsorbent. The performance of the superadsorbent was compared with previous studies, and it was found to have excellent adsorption efficiency. Hence, chitosan zinc-oxide nano-adsorbent coated sand could be used as a promising superadsorbent for the removal of organic load from milk processing industry wastewater.