Renewable-powered modular EC for decentralized laundry wastewater treatment: energy scheduling and techno-economic evaluation

Electrocoagulation (EC) offers a compact and controllable option for decentralized laundry wastewater treatment, but its practical deployment is constrained by electricity cost, carbon intensity, and variable wastewater generation. This study develops a renewable-powered modular EC framework integrating photovoltaic generation, battery storage, grid backup, hydraulic equalization, and parallel EC modules through an energy-scheduling layer. A 1.0 m³ day −1 design case was evaluated under fixed-grid operation, renewable-scheduled operation, and low-renewable emergency operation. The scheduling strategy coordinated current density, active module number, flow allocation, battery state of charge, and effluent-quality constraints while preserving hydraulic retention time. Under renewable-scheduled operation, removal efficiencies reached 83.9% for COD, 92.8% for turbidity, 90.1% for TSS, 80.7% for MBAS, 86.9% for oil and grease, and 82.1% for phosphate. Compared with fixed-grid operation, renewable scheduling increased the renewable fraction to 76.4%, reduced grid import by 62.8%, decreased peak-hour grid use by 79.5%, and lowered greenhouse-gas intensity from 0.680 to 0.218 kg CO₂e m −3 . Unit OPEX decreased from 0.336 to 0.281 USD m −3 . The results demonstrate that modular EC can function as a dispatchable electrochemical treatment load for low-carbon decentralized wastewater management.