Organic Matter Removal of Biogas-Digested Pig Wastewater Using an Upflow Anaerobic Biochar-Based Filter Column

This study evaluates the performance of an upflow anaerobic biochar-based filter column for treating pig farm wastewater, addressing the limited application of biochar in this context. Biochar derived from Mimosa pigra, an invasive plant species, was utilized to explore its potential as a sustainable, cost-effective treatment medium. Two systems with varying hydraulic loading rates (HLR) and organic loading rates (OLR) were evaluated. Both systems achieved high chemical oxygen demand (COD) removal efficiency, ranging from 84.90% to 85.62% within the first 12 days. The system operating under higher OLR and HLR exhibited slightly better COD removal efficiency (78.22 ± 5.05%) compared with the lower-rate system (77.93 ± 5.44%). The results suggest that increased OLR generally enhances COD removal, while higher HLR may reduce efficiency by decreasing biofilter contact time. Despite elevated HLRs, effluent COD remained within discharge limits, indicating the potential to optimize HLR and OLR for improved performance and cost-efficiency. This study provides new insights into the application of invasive plant-derived biochar in pig farm wastewater treatment, contributing to more sustainable waste management practices.