<p>The present study is aimed to enhance electrocoagulation (EC) remediation of tannery wastewater with a EC unit having rotating fins anodes and ring cathodes for the effective removal of chemical oxygen demand (COD) and chromium, Cr(VI), despite high concentrations (COD: 6000 mg L^− 1, Cr(VI): 40 ppm). The operational EC parameters (pH: 2–10, electrolysis time: 5–25&#xa0;min, applied current: 0.4–1.2&#xa0;A, and rotational speed: 50–250&#xa0;rpm) are optimized using Response Surface Methodology (RSM) and central composite design (CCD) to maximize the COD and Cr(VI) removal percentage. The maximum percentage removal of COD and Cr(VI) is obtained as 92.28% and 97.92% at the optimized process parameters i.e., 6 pH, 18&#xa0;min electrolysis time, 1&#xa0;A current (current density = 2.65&#xa0;mA cm^− 2) and 170&#xa0;rpm rotating speed. Kinetics studies for both the COD and Cr(VI) removal are also performed to analyse the impact of retention time and design the best fit kinetic model. Kinetic study reveals that both the COD and Cr(VI) removal follow second order kinetics with R² values of 0.98 and kinetic constants, <i>k</i>_{Cr (VI)} = 0.0292&#xa0;min^− 1 and <i>k</i>_COD = 7.0 × 10^− 5&#xa0;min^− 1. Lastly, the total electrical energy consumption (EEC) and total operating cost (OC) including labour and maintenance are calculated to be 1.67 kWh m^− 3 and 0.384 US$ m^− 3, respectively under optimal conditions. The results suggest a promising method for COD and Cr(VI) removal, offering a combination of high efficiency, cost-effectiveness, and environmental sustainability. This novel design EC reactor shortens treatment time and reduces energy with intensified mass transfer and suppress passivation.</p> Graphical abstract <p></p>