Data‐Driven Optimization of Agricultural Waste Adsorbents: Statistical Insights on Wastewater Treatment Efficiency

Water pollution poses a significant global challenge, threatening human health, ecosystems, and environmental sustainability. Conventional wastewater treatment methods often fall short in addressing emerging contaminants, necessitating innovative and cost‐effective alternatives. This study evaluates the potential of agricultural by‐products, rice husks and coffee husks, converted into activated carbon (AC) through carbonization (300°C and 400°C, respectively), and followed by physical and ZnCl 2 ‐assisted chemical activation, as sustainable adsorbents for wastewater treatment. Raw wastewater samples were collected from the Kigongi Sewage Treatment Plant in Kabale, Uganda, and analyzed for turbidity, pH, Escherichia coli , total suspended solids (TSS), biochemical oxygen demand (BOD), and chemical oxygen demand (COD). Jar tests established optimal dosages of 70 mg/L for rice husk–activated carbon (RHAC) and 80 mg/L for coffee husk–activated carbon (CHAC) supported by regression modeling. Under these conditions, RHAC achieved 64.3% turbidity and 84.4% TSS removal, while CHAC removed 60.7% turbidity and 72.9% TSS. In terms of microbial contamination, RHAC and CHAC achieved 59.18% and 34.69% removal of Escherichia coli , respectively, indicating meaningful antimicrobial activity in real sewage wastewater. Analysis of variance (ANOVA) results confirmed the statistical significance of RHAC’s superior performance in reducing BOD and COD, and regression analysis demonstrated strong correlations between adsorbent dosage and pollutant removal efficiencies. These findings illustrate the viability of agricultural‐waste‐derived ACs as low‐cost and sustainable polishing agents for wastewater treatment. Beyond addressing immediate pollutant loads, their deployment advances circular economy goals and environmental conservation by transforming biomass residues into value‐added materials. Future research should examine regeneration capacity and performance against emerging contaminants to further validate their scalability under real‐world conditions.