Towards cleaner production in palm oil industry: Advanced treatment of biologically-treated POME using palm kernel shell-based adsorbent

Abstract

Palm oil processing generates enormous amount of wastewater, the palm oil mill effluent (POME), containing various recalcitrant pollutants. The biological processes commonly employed to treat POME often fail to achieve treatment levels required for safe disposal or recycling of the effluent, prompting the need to develop polishing technologies. In this work, we investigated the possibility of polishing biologically-treated POME using palm kernel shell activated carbon (PKSAC) derived from a solid waste generated during palm oil processing. The rationale is to provide impetus towards adopting cleaner production in the palm oil industry through recycling both wastewater and solid wastes generated from palm oil processing. The PKSAC was impregnated with iron oxide to produce a magnetic adsorbent that could be easily separated after the treatment. The adsorbent was characterized using BET, SEM/EDX, FTIR and VSM analyses. The adsorbent exhibited high specific surface area (611.85 ​m 2 /g), excellent magnetic property (15.16 emu/g) and various surface functional groups. Batch adsorption experiments were conducted to investigate the suitability of the adsorbent to polish biologically-treated POME. To investigate the effect of operational parameters (initial pH, adsorbent dosage and contact time) on the adsorption, response surface methodology using Box-Behnken Design was employed. Under the optimum condition (initial pH ​= ​3.5, adsorbent dosage ​= ​9.9 ​g/L and contact time ​= ​3.4 ​h), 99.7% of the initial color and 85.0% of the initial COD were removed. The initial pH and adsorbent dosage are the most significant parameters affecting the adsorption. The adsorbent maintained excellent adsorption performance over 4 cycles, with the removal efficiency reducing by less than 2% after the 4th cycle. This study has shown that palm kernel shell can be used as an effective adsorbent for POME polishing, indicating a potential for wastes recycling within the palm oil industry. The use of palm kernel shell to treat POME, which could be subsequently recycled, represents a significant step towards enhancing the sustainability of palm oil industry.