Domestic wastewater supplementation enhances biomass, nutrient uptake, and water use efficiency of tomato in non-circulating hydroponic systems

Within a circular nutrient economy framework, supplementing wastewater with commercial hydroponic fertilizer mix has been proposed to reduce nutrient variability, enhance phytoremediation, and support nutrient recovery for crop production. However, the resource-use (wastewater and nutrient) efficiency of such practice in non-circulating hydroponic systems compared to conventional freshwater and fertilizer use remains unclear. This study evaluated the effect of anaerobic filter effluent (AF), AF supplemented with 50% (CHFM50) commercial hydroponic fertilizer mix (CHFM), and CHFM with tap water (CHFMT) on biomass production, nutrient uptake, and water-use efficiency of tomato (Solanum lycopersicum cv. Star 9001) under glasshouse conditions. Significant treatment effects (p < 0.05) were observed for yield, biomass, agronomic (AWUE) and instantaneous (WUEins) water use efficiency. CHFMT produced the highest yield (3,107 g/plant) and AWUE (77.7 g/L), which were not significantly different from CHFM50 (2,975 g/plant; 74.4 g/L). In contrast, AF resulted in lower yield (1,500 g/plant) and AWUE (37.5 g/L). WUEins and shoot nutrient concentrations (N, K, Ca, Zn, Fe) were significantly higher in CHFM50 and CHFMT than in AF. Overall, CHFM50 maintained comparable performance to CHFMT despite 50% reduction in CHFM. This demonstrates potential to reduce fertilizer dependency, eliminate freshwater use, and promote wastewater phytoremediation in non-circulating hydroponic systems.