Treatment of complex compost leachate using a combined electrochemical and stripping process for safe surface water discharge

Leachate is one of the most challenging byproducts of the composting process, as it contains high levels of pollutants and exhibits a very low biodegradability. A new combined sequence of electrocoagulation (EC), electrooxidation (EO), and ammonia stripping (AS) was employed to treat this complex wastewater to a level suitable for discharge into surface waters in accordance with the environmental regulations of Quebec, Canada. Two anode materials, iron (Fe) and aluminum (Al), were evaluated in the EC process, achieving COD removals of 61.0% and 60.5%, respectively, after 60 min of operation at a current density of 20 mA/cm 2 . Optimization with response surface methodology indicated that the best EC performance was achieved with the Fe electrode at 15 mA/cm 2 and 45 min. In the subsequent EO step, treatment at 70 mA/cm 2 for 120 min reduced COD from an initial concentration of 517 mg/L to 9 mg/L, corresponding to a 95% removal. Finally, AS was applied to control ammonia levels, reducing the final effluent concentration to 6.39 mg/L, which complies with discharge regulations. Overall, this hybrid treatment sequence achieved 99% COD removal and 96% ammonia recovery as fertilizer, demonstrating the potential of this process as an effective treatment strategy for compost leachate management. • Optimization of electrocoagulation by RSM using CCD and factorial design. • Degrading refractory organic compounds by electrooxidation process. • Recovery of ammonia by stripping process. • Efficient removal of organic, inorganic, and nitrogen pollutants by EC/EO/AS. • Compliance of the integrated process with surface water discharge standards.