Electrochemical Pathways to Circular Livestock Wastewater Management: Boron-Doped Diamond Anodes for Detoxification and Nutrient Recycling

Abstract Livestock wastewater poses a major environmental challenge due to its high organic load, ammonium content, and the presence of persistent pollutants that resist conventional biological treatment. This study aims to develop and optimize an electrochemical oxidation process using boron-doped diamond anodes as a process-intensified technology for the simultaneous detoxification and nutrient recovery from livestock wastewater. The influence of applied current intensity and electrode surface area on treatment efficiency, energy demand, and toxicological outcomes was investigated. Experiments using 10 and 20 cm 2 electrodes at applied current intensities from 0.1 to 1.0 A revealed a size-dependent behaviour. While the smaller electrodes benefited from higher current density, the larger electrodes achieved superior overall performance, with up to 96% chemical oxygen demand removal, faster degradation of refractory compounds (benzene, indole, phthalates), and lower specific energy consumption due to reduced ohmic losses and a more uniform current and oxidant distribution. Toxicological modelling using USEtox ® demonstrated that electrode area influences the removal of hazardous metals. The 20 cm 2 electrodes reduced human toxicity potential by 97% and ecotoxicological impact by 84%, surpassing the smaller configuration. Both configurations produced effluents with concentrations indicative of potential agricultural reuse, while the larger electrodes provided more stable and energy-efficient operation. Furthermore, treated effluents enabled recovery of up to 97% of the residual ammonium remaining after EO as crystalline struvite, contributing to circular resource use. The results support the integration of advanced electrochemical oxidation with nutrient recovery as a promising compact, multifunctional, low-footprint treatment strategy. This integrated approach aligns with the principles of process intensification, offering enhanced degradation kinetics, minimized environmental impact, and resource circularity within agroindustrial systems. The findings contribute to the development of scalable, energy-efficient wastewater treatment solutions that simultaneously address pollution control and sustainable resource management, advancing the transition toward cleaner and more circular agricultural production. Graphical Abstract This study investigates an advanced electrochemical oxidation process using boron-doped diamond (BDD) anodes for the treatment and valorization of livestock wastewater. The research integrates pollutant degradation and nutrient recovery within a single intensified system, addressing the pressing challenge of managing high-strength agroindustrial effluents. The image visually summarizes the sequential stages of the research, from the collection of livestock effluents rich in organic matter and ammonium to their electrochemical degradation and resource recovery. The electrochemical oxidation process was optimized by varying electrode surface area and current intensity, demonstrating that larger electrodes enhance mass transfer and reduce ohmic resistance, resulting in higher removal efficiencies and lower specific energy demand. Under optimal conditions, the treatment achieved up to 96% chemical oxygen demand (COD) removal and a 97% reduction in overall toxicity potential. The process also enabled the recovery of nitrogen through struvite precipitation, achieving 97% ammonium recovery and promoting circular resource utilization. Toxicological modeling using USEtox ® confirmed the mitigation of potential human and ecotoxicological risks. Overall, the study highlights electrochemical oxidation with BDD anodes as a compact, energy-efficient, and environmentally promising technology that embodies the principles of process intensification, providing a sustainable pathway for wastewater detoxification and nutrient recycling within circular agricultural systems.