Development and environmental performance of a pilot-scale membrane capacitive deionization system for wastewater reclamation: Long-term operation and life cycle analysis.

Wastewater reclamation is regarded as a primary solution for efficient water resource management because of its environmental friendliness and energy efficiency. Membrane capacitive deionization (MCDI) has shown great promise as a practical technology for wastewater reclamation, but challenges remain for the large-scale deployment of this technology due to gaps in understanding its technical and environmental performance. This study presents a pilot-scale MCDI-based wastewater treatment and reclamation system that includes sand filtration (SF), ultrafiltration (UF), MCDI, and ultraviolet (UV) units. Additionally, this research aims to investigate the overall environmental impacts and trade-offs of the system through a life cycle assessment (LCA) approach to identify impact hotspots with the potential for system improvement. Over long-term operation, the water quality characteristics showed significant improvements in conductivity, ammonia-N content, and total hardness, satisfactorily meeting the standards for wastewater reclamation. Results from the impact assessment revealed that the production of 1 m³ of desalinated water for reclamation in the MCDI-based system generates a global warming potential of approximately 2.77 kg CO₂ eq, primarily due to electricity consumption and the use of high-impact chemicals. Electricity and chemical consumption contribute nearly 81 % and 15 %, respectively, to the overall impacts. These inputs also have remarkable impacts on marine aquatic ecotoxicity, human toxicity and abiotic depletion. The impacts from material and chemical usage are average out during the scaling-up process due to the increase in water productivity. As demonstrated, the integration of emerging water treatment technologies with high energy efficiency could significantly improve the environmental performance of the system. The results from the present study can offer valuable insights for advancing future wastewater reclamation systems aimed at improving environmental outcomes.