Granular Indigenous Microalgal–Bacterial Consortium (G-IMBC) Technology for Sustainable Palm Oil Mill Effluent Bioremediation and High-Value Biomass Generation

The increasing production of crude palm oil (CPO) also raises the volume of palm oil mill effluent (POME), where one ton of CPO generates around 2.5 tons of POME. Conventional treatment using open pond systems releases greenhouse gases, but POME contains nutrients that can be utilized for developing Granular Indigenous Microalgal-Bacterial Consortium (G- IMBC) as an alternative treatment. This study investigates the formation of G-IMBC and its performance in pollutant removal, focusing on chemical oxygen demand (COD), total nitrogen, and total phosphate reduction, as well as its nutrient content for sustainable applications. G-IMBC was cultivated from microalgae and bacteria isolated from POME ponds over 22 days at 620 mgCOD/L with 100 mg/L Ca²⁺ addition. The granules formed had an average size of 2.71 mm, SVI₅ of 28.02 mL/g, density of 3.33 g/mL, and chlorophyll-a concentration of 2.23 mg/L. Performance tests showed significantly higher pollutant removal compared to POME-activated sludge (P < 0.05), with COD, nitrogen, and phosphate removal efficiencies of 82.25 ± 9.61%, 72.70 ± 14.09%, and 71.68 ± 21.20%, respectively. Nutrient recovery was also higher (88.63%) than activated sludge (77.73%), attributed to microalgal photosynthesis and the dense granule structure. These results highlight G-IMBC as a promising eco-friendly technology with potential applications in fertilizer, bioenergy, and animal feed production.