Agro-industrial wastewaters are generated in large volumes with high organic content. It is very difficult to eliminate the recalcitrant organic compounds present in the wastewater after the biological treatment. Monopolar-mode electrocoagulation systems are extensively studied in the literature as polishing treatment systems after the biological treatment. However, studies on bipolar-mode electrocoagulation systems are limited. This study compares the performance of a Continuous Bipolar-Mode Electrocoagulation (CBME) unit developed at a laboratory scale with that of a field-scale CBME system used for the removal of recalcitrant organic carbon and phosphorus from marigold wastewater. The design parameters required for a CBME system were extracted. The higher Surface area to Volume (S/V) ratio of 76.5 m-1, used in this study achieves higher treatment efficiency at lower energy consumption and lesser retention time, which saves energy and space when applied in field scale. The optimization study was carried out at both lab-scale and field-scale for the removal of Total Organic Carbon (TOC) and Total Phosphorus (TP) using Response Surface Methodology (RSM). The S/V ratio was kept constant, for both the CBME systems. The potential design parameters and the performance of the CBME reactors were compared. The optimum values obtained for operating variables were found to be, pH at 6.5, retention time of 6.8 min and current at 2.9 A for lab-scale system and the optimum values obtained for field-scale system were found to be, the retention time of 6.5 min and current at 51.3 A. The organic compounds were identified in the wastewater samples at the optimum points. Retention time, S/V ratio, and energy consumption were found to be potential design parameters for a CBME system. © 2019 Elsevier Ltd