Advanced electrochemical membrane technologies for near-complete resource recovery and zero-discharge of urine: Performance optimization and evaluation

• Published in: Water research (Oxford) 2024-10, Vol.263, p.122175, Article 122175
• Main Authors: Yang, Hao-Ran, Liu, Yuan, Hu, Shu-Jie, Zhang, Meng-Yue, Wu, Di, Zheng, Lei, Zhong, Lin-Jiang, Wang, Chuan, Liu, Hong
• Format: Article
• Language: English
• Subjects: Bipolar membrane electrodialysis; Electrochemical Techniques - methods; Fertilizers; Hollow fiber membrane; Membranes, Artificial; Near-complete resource recovery; Nitrogen; Phosphorus; Potassium - urine; Selective separation; Urine - chemistry; Waste Disposal, Fluid - methods; Wastewater - chemistry; Water Purification - methods; Zero urine discharge
• ISSN: 0043-1354; 1879-2448; 1879-2448
• DOI: 10.1016/j.watres.2024.122175

•Bipolar membrane electrodialysis and hollow fiber membrane composed the system.•Voltage of BMED and flow rate of solution showed key impacts on system performance.•The system recovered 89% N, 96% P, and 95% K from fresh urine.•The system converted urine into acids, bases, and fertilizers with zero discharge.•A net profit was achieved by the system from urine recovery at lab and pilot scales. The depletion of nutrient sources in fertilizers demands a paradigm shift in the treatment of nutrient-rich wastewater, such as urine, to enable efficient resource recovery and high-value conversion. This study presented an integrated bipolar membrane electrodialysis (BMED) and hollow fiber membrane (HFM) system for near-complete resource recovery and zero-discharge from urine treatment. Computational simulations and experimental validations demonstrated that a higher voltage (20 V) significantly enhanced energy utilization, while an optimal flow rate of 0.4 L/min effectively mitigated the negative effects of concentration polarization and electro-osmosis on system performance. Within 40 min, the process separated 90.13% of the salts in urine, with an energy consumption of only 8.45 kWh/kgbase. Utilizing a multi-chamber structure for selective separation, the system achieved recovery efficiencies of 89% for nitrogen, 96% for phosphorus, and 95% for potassium from fresh urine, converting them into high-value products such as 85 mM acid, 69.5 mM base, and liquid fertilizer. According to techno-economic analysis, the cost of treating urine using this system at the lab-scale was $6.29/kg of products (including acid, base, and (NH4)2SO4), which was significantly lower than the $20.44/kg cost for the precipitation method to produce struvite. Excluding fixed costs, a net profit of $18.24/m3 was achieved through the recovery of valuable products from urine using this system. The pilot-scale assessment showed that the net benefit amounts to $19.90/m3 of urine, demonstrating significant economic feasibility. This study presents an effective approach for the near-complete resource recovery and zero-discharge treatment of urine, offering a practical solution for sustainable nutrient recycling and wastewater management. [Display omitted]