Reuse of treated swine wastewater in a hydroponic forage production system

The objective of this study was to evaluate the agronomic and nutritional responses of hydroponic green forage (HGF) produced using treated swine wastewater (T-SWW) processed by immediate one-step lime precipitation (IOSLP) followed by natural carbonation. Five forage crops – oat, ryegrass, barley, durum wheat, and triticale – were assessed using a 3 × 5 factorial experimental design, comparing three irrigation treatments: groundwater (control), a 1:1 mixture of groundwater and T-SWW, and 100% T-SWW. Although T-SWW exceeded regulatory thresholds for some conventional physicochemical parameters (e.g. BOD₅ and total nitrogen), no adverse effects on biomass production or water-use efficiency were observed under the experimental conditions. Barley showed the highest water use efficiency (0.95 ± 0.03), while durum wheat achieved the highest dry biomass yield (4.7 ± 0.1 kg/m²). Significant differences among species were observed in agronomic performance, nutritional composition, and mineral content, with irrigation treatments influencing crude protein, ash, and selected mineral contents (Na, K, Ca, Mn). Overall, the results indicate that T-SWW treated by IOSLP‑carbonation may be agronomically feasible as a partial substitute for freshwater in HGF production under controlled conditions. Further research is required to evaluate long-term performance, microbial aspects, and environmental and economic sustainability prior to large-scale implementation.