Single-Stage Aluminum Electrocoagulation for Treating Real Wastewater From Rural Cassava Starch Mills

This study assessed the performance of monopolar electrocoagulation (EC) using aluminum electrodes to treat real wastewater generated from cassava starch extraction, a stream characterized by high organic loads, elevated suspended solids, and complex organic matter that can challenge conventional biological treatments. The research was conducted at pilot scale at the La Victoria facility in Sucre, Colombia, between June 2024 and March 2025. A multifactorial experimental design comprising 18 trials was applied, with electric potential (0, 12, 15, and 18 V) and interelectrode distance (2 and 3 cm) as independent variables. The primary response variable was chemical oxygen demand (COD), complemented by biochemical oxygen demand (BOD₅), total suspended solids (TSS), turbidity, total phosphorus (TP), and total nitrogen (TN). Among the discrete conditions evaluated, EC3-15 (3 cm, 15 V) provided the most favorable overall performance, achieving removals of 75.8% for COD, 76.0% for BOD₅, 57.4% for TSS, approximately 92.0% for turbidity, 72.8% for TP, and 62.7% for TN. EC3-15 was therefore identified as the best-performing condition within the experimental domain rather than as a mathematically optimized condition. At 15 V, the estimated specific energy consumption was 9.6 kWh/m³, substantially lower than the 17.5 kWh/m³ estimated at 18 V. Unlike studies relying on synthetic wastewater or high-energy, multistage reactors, this study shows that a single-stage EC process operated under moderate electrical conditions can provide an effective decentralized treatment option for highly concentrated agroindustrial effluents. Future work should address sludge valorization and integrate this EC unit as a primary treatment stage before biological polishing.