Agriculture is the mainstay of the Indian economy. The agro-based industries produce high volumes of highstrength wastewaters that need to be treated and reused to prevent environmental pollution and water wastage. This study evaluated the performances of a sequential biological-electrochemical process for treating an anaerobically digested effluent of a Marigold flower processing agro-industry. The uniqueness of this wastewater possess a major challenge to its treatment since not many studies have been conducted on this wastewater. The biological treatment was carried out in a Sequential Batch Reactor (SBR). The treated water was further polished in a Continuous Bipolar-mode Electrochemical Reactor (ECR) to remove the residual organics. The anaerobically digested effluent Chemical Oxygen Demand (COD), Dissolved Organic Carbon (DOC), Total Nitrogen (TN), Total Phosphorus (TP) and Total Suspended Solids (TSS) were 5750 ± 991 mg/L, 980 ± 120 mg/L, 692 ± 60 mg/L, 9.7 ± 1.1 mg/L, and 1144 ± 166 mg/L, respectively. A significant level of treatment was achieved in the SBR. The combined system was able to remove 79% of COD, 85% of DOC, 53% of TN, and almost 100% of TP, TSS, and Volatile Suspended Solids (VSS). Several organic compounds belonging to the category of natural plants compound, pesticide, fungicide, etc. were detected in the raw wastewater. Most of the compounds were almost completely removed by the treatment system. The final effluent was almost colorless and free from suspended solids. However, for reuse, the water needs to be further treated in an advanced oxidation process.

The effectiveness of a sequenced biological–physicochemical reactor system for treating sewage was studied. The biological degradation was conducted in a Sequential Batch Reactor, which had innovative features for simplifying the operation and maintenance of the reactor. The reactor was operated at 4, 6, 8, and 12 hr cycle. Up to 82% removal of Chemical Oxygen Demand (COD), 50% removal of Dissolved Organic Carbon (DOC), 45% removal of Total Nitrogen (TN), and 45% removal of Total Phosphorus (TP) were achieved. The treated effluent was further polished in a continuous‐flow bipolar‐mode electrochemical reactor to remove additional recalcitrant organic matter from the wastewater. The process parameters were optimized using Response Surface Methodology. At the optimum condition (pH = 8.7; Current = 1.0; reaction time = 9.0), up to 90% removal of COD, 67% removal of DOC, 61% removal of TN, and 99.9% removal of TP were achieved in the coupled system. Micropollutants belonging to Pharmaceutically Active Compounds, pesticides, etc., were significantly removed. The coupled system completely removed Salmonella, Pseudomonas, and Staphylococcus. However, coliforms were detected at the outlet samples. A UV or ozone disinfection treatment is recommended for the safe reuse of the treated water for nonpotable purposes. Practioner points Sequential sequential batch reactor‐electrochemical reactor process (SBR‐ECR) technology is effective for micropollutant removal from sewage. The coupled SBR‐ECR system requires less footprint compared to conventional biological systems for wastewater treatment. Carbon material balance study revealed that more than 60% of carbon escapes from wastewater in the form of CO2