Coconut shell biochar as a sustainable approach for nutrient removal from agricultural wastewater

Coconut shell residues are abundant in tropical countries and have the potential to be further processed into biochar. Due to its specific characteristics, biochar has the potential to remove contaminants from wastewater. The intensification of agriculture in these tropical countries produces large volumes of wastewater that require nutrient removal before being discharged into water bodies. Accumulated nutrient in bodies of water can lead to eutrophication. This study investigates the capacity of coconut shell biochar in removing phosphate, ammonium, and nitrate from agricultural wastewater using both batch adsorption and fixed-bed column methods. The nutrient sorption capacity of biochar produced at different pyrolysis temperatures (300°C, 450°C, and 600°C) was evaluated and compared with locally produced biochar from Padang City. Findings indicated that the nutrient adsorption efficiency of coconut shell biochar is influenced by pyrolysis temperature and is comparable to that of local biochar. The sorption capacity of ammonium, nitrate, and phosphate using local biochar were 10.12, 7.51, and 10.79 mg∙g−1. A continuous sorption study using a fixed-bed column reactor confirmed the ability of local coconut shell biochar in removing nutrients from real agricultural wastewater. This study highlights the potential of utilising coconut shell waste as a sustainable material for nutrient removal from wastewater, thereby helping to prevent nutrient pollution in water bodies.