Assessment of Biochar Corn (Zea mays) Cob and Coconut Guinit as Media for Treating Public Market Wastewater

Public market discharges often enter surface waters untreated, carrying extremely high organic loads and dissolved/suspended solids. Locally abundant agricultural residues, corncob and coconut guinit, offer a potentially low-cost filtration medium, yet remain understudied in market waste applications. This study evaluated a gravity-fed vertical filtration prototype using three corncob biochar masses (≈247, 389, 530 g; corresponding layer thicknesses ~5, 7.5, 10 cm) sandwiched between constant coconut guinit layers downstream of a pebble pre-filter. Raw public market wastewater from Isabela City, Basilan, was passed through each configuration. Effluents were analyzed for Biological Oxygen Demand (BOD), Total Dissolved Solids (TDS), turbidity, and color. The results were compared with the Philippine DENR DAO 2016-08 Class C effluent standards. Maximum mean reductions were 25.7% (to 2,760 mg/L) for BOD, 29.0% TDS (to 5,072 mg/L), 5.3% turbidity (to 60.1 NTU), and 16.0% color (to 17,707 CU). None met regulatory limits (BOD