Sustainable nutrient water recovery by a hybrid electrodialysis (ED) - forward osmosis (FO) process for agricultural application

With increasing water shortages, irrigation with reclaimed water is necessary to secure agricultural production in many regions. This study investigated the feasibility of a novel hybrid electrodialysis-forward osmosis (ED-FO) process designed to recover nutrients and clean water from anaerobic digester effluent to produce food crops safely. The final product water from the process was tested and evaluated for hydroponic production of lettuce and kale. The ED treatment demonstrated an impressive nutrient recovery rate: 84% for ammonium, 86% for potassium, 98% for ortho-phosphate, and 97% for nitrate from the anaerobic effluent. The nutrient-rich concentrate from the ED process reclaimed up to 74% of clean water from the ion-stripped diluate through the FO process. The hybrid ED-FO process also retained 62-98% of heavy metals and 83% of total organic carbon (TOC) in the residual waste stream, consistent with non-target analysis. Both ED and FO demonstrated lowfouling potential. According to our economic analysis, the hybrid ED-FO process is promising for scalable implementation, making the process highly attractive in terms of resource recovery, waste footprint reduction, and water quality enhancement.