Abstract Summary
As global food production dominates freshwater consumption and nutrient discharge regulations tighten, there is a need to investigate novel circular water solutions at applied scale. In the Netherlands, the greenhouse horticulture sector is required to achieve (nearly) zero liquid discharge by 2027. This challenge calls for new technologies to produce and reuse irrigation water that meets strict quality standards while reducing environmental impact. We evaluated production of irrigation water and nutrient recovery from greenhouse wastewater using a one-pass capacitive electrodialysis (CED) system at a pilot scale (19.32 m2 membrane area, 1-4 m3/day capacity), employing carbon-based electrodes. Using CED, we produced reclaimed water that meets the target for irrigation water quality (Na+< 0.1 mmol/L). Furthermore, we were able to concentrate nutrients by 42-85% making it possible to reduce emissions while also reducing the need for virgin materials as fertilizer. It was observed that the specific energy consumption (SEC) of CED was 4-fold lower than for reverse osmosis (RO) and conventional electrodialysis (ED) studies, making CED an promising alternative to established water treatment solutions. Operating costs were predominantly driven by energy consumption which accounted for over 80% of total expenses, while ion-exchange membranes contribute approximately 10%, representing potential bottlenecks relative to alternative technologies. Further full-scale demonstrations in collaboration with industry stakeholders are necessary to confirm long-term operational and economic feasibility. Moreover, ongoing research is being done to developing Na⁺/K⁺ selective membrane solutions, optimizing costs, and managing concentrate streams. By addressing both technical challenges and socioeconomic barriers, this work provides critical insights that can guide the scale-up of CED and support policy decisions and for sustainable water management in high-demand agricultural sectors.
