Optimization of Turbidity and Organic Matter Removal from Palm Oil Mill Effluent by Batch Adsorption Using Gasification-Derived Pinus patula Biochar

Abstract

In the palm oil agroindustry, large volumes of POME (palm oil mill effluent) are generated during the oil extraction process, representing a significant source of water pollution by organic matter (OM) and turbidity. In this work, gasification-derived biochar from Pinus patula wood pellets was evaluated as an adsorbing material for POME treatment. For this purpose, a face-centred central composite design of experiments was used, and biochar dose and the pH of the solution were optimized through a second-order regression model. POME samples were taken from an agro-industrial company located in Colombia. The study identified a dose of biochar of 6 g/L and a pH of 6, as optimal operating conditions, achieving turbidity and OM in terms of chemical oxygen demand (COD) removal values of 58.27% and >50% at a treatment time of 30 min, respectively. The high specific surface area (367.33 m2/g) and pore volume (0.20 cm3/g) of the Pinus patula biochar used favoured turbidity and OM elimination mainly by physical mechanisms, such as pore filling and intraparticle diffusion, since the biochar surface remained near neutral at the optimal pH value found, minimizing electrostatic interactions. These results suggest that Pinus patula biochar has the potential to be used as an alternative technique to eliminate turbidity and decrease COD in POME. Additionally, it contributes to circular bioeconomy approaches through the valorisation of forestry solid waste in biochar production.