Electrodialysis treatment of rhamnolipids hydrolysate and its waste water for use as water-soluble fertilizer

Rhamnolipids can serve as a precursor for rhamnose production, but using ion exchange resin in purifying rhamnolipids hydrolysate results in excessive high-salinity wastewater, making the process environmentally and economically unfeasible. This study introduced electrodialysis technology as an alternative for purifying rhamnolipids hydrolysate, significantly reducing wastewater to less than 5 % compared to the resin method. To achieve zero wastewater discharge, the electrodialysis-treated wastewater was repurposed into a water-soluble fertilizer containing 7.1 g/L of rhamnolipids, 11.4 g/L of fatty acid, 2.4 g/L of amino acid, and 8.2 g/L of po-tassium. Unlike traditional fertilizers, the nutritional components with rhamnolipids showed remarkable po-tential in enhancing tomato plant growth, flowering, and fruit quality. Taken together, the electrodialysis treatment of rhamnolipids hydrolysate largely reduced the water volume, the economic cost, and took a full use of the final wastewater as efficient water-soluble fertilizers, making it applicable for large-scale rhamnose production.