Nutrient Recovery from Food-Industry Wastewater Using Zeolite and Its Application as a Fertilizer for Crops in Bikaner

The increasing generation of nutrient-rich wastewater from the food processing industry poses serious environmental challenges, particularly in terms of eutrophication and water quality deterioration. At the same time, the depletion of natural phosphorus reserves and the rising demand for sustainable fertilizers highlight the need for resource recovery approaches. This study investigates the potential of zeolite synthesized from industrial sludge for nutrient recovery from food industrial wastewater and its subsequent reuse in agriculture. Wastewater samples collected from five food industries exhibited high variability in physicochemical characteristics, with Industry 5 showing significantly elevated levels of chemical oxygen demand (2860 mg/L), biochemical oxygen demand (681 mg/L), ammonia (340 mg/L), and phosphate (5.10 mg/L). Zeolite was synthesized using hydrothermal treatment and characterized by X-ray diffraction, confirming the formation of crystalline zeolite phases with an average crystallite size of 38–45 nm.Batch adsorption experiments were conducted to optimize parameters affecting nutrient recovery, including pH, agitation speed, and contact time. Maximum recovery efficiencies of 91.1% for ammonium and 82.1% for phosphate were achieved at pH 7, 150 rpm, and 120 minutes. These results are comparable or superior to previously reported studies, indicating high adsorption efficiency of synthesized zeolite. Furthermore, nutrient-loaded zeolite was applied in pot experiments using Aloe vera, Cyamopsis tetragonoloba, and Spinacia oleracea, resulting in significant improvements in plant height and biomass. Spinach exhibited the highest biomass increase (~66%), demonstrating effective nutrient utilization.The study confirms that zeolite-based nutrient recovery is a viable and sustainable approach for wastewater management and agricultural reuse. The integration of waste valorization, nutrient recovery, and crop productivity enhancement supports the implementation of circular economy principles in environmental management.