Exploring the potential of single-batch and multi-batch electrodialysis treatment of domestic wastewater for resource recovery

The growing global population has intensified pressure on water and fertilizer resources, necessitating their sustainable recovery. This study investigates electrodialysis (ED) for nutrient recovery and hydrogen generation from domestic wastewater using single-batch (SB) and multi-batch (MB) modes. Synthetic domestic wastewater was treated in both ED modes to assess ion separation efficiency, electrochemical performance, and economic feasibility. The results demonstrated that MB-ED exhibited higher nutrient recovery, reaching 90 % for nitrate and potassium. The energy and exergy efficiencies were also higher for MB-ED (83.2 % and 81.7 %, respectively). Nevertheless, the hydrogen generation rate was greater in SB-ED at 629.4 mg/h.m³ in comparison to 540.7 mg/h.m³ for MB-ED. However, MB-ED proved more cost-effective, with a lower levelized cost of nutrients (0.42 USD/kg) and higher net present value. When treating pre-treated real domestic wastewater, electrodialysis initiated with multi-batch mode faced operational challenges, notably membrane fouling by organic matter, increasing system resistance from 180.40 Ω in the first batch to 447.71 Ω in the second batch, and energy consumption rising from 1.40 kWh/m³ to 1.49 kWh/m³. Despite this, the electrodialysis process maintained effective ion recovery performance, with recovery rates up to 85.1 % for potassium ions and moderate recoveries between 64.5 % and 73.0 % for calcium, magnesium, aluminium, and sulfate ions. The findings highlight the potential of electrodialysis, particularly in multi-batch mode, as an efficient and economical approach for resource recovery in sustainable wastewater treatment.