Safer Food Production With Reclaimed Wastewater: Linking Biological Treatment, Microbial Quality, and Heavy-Metal...

Agricultural wastewater reclamation can reduce freshwater demand, but crop productivity must be balanced against contaminant transfer. We evaluated UASB-aerobic effluent produced at a 6-h UASB hydraulic retention time in a factorial greenhouse experiment with squash, six irrigation-water treatments, and three field capacity levels (100%, 80%, and 60%; N = 54). Water source × field capacity interactions were significant for all 12 agronomic outcomes (p < 0.001). At 80% field capacity, untreated wastewater (UTW) produced the highest shoot fresh biomass (80.30 g plant^-1), whereas treated wastewater (TW) maintained 85.3% of this maximum (68.53 g plant^-1) and did not differ significantly from freshwater (Tukey-adjusted p = 0.484). TW fruit had lower measured Cu, Mn, and Zn concentrations than UTW, while Cr, Ni, Co, and Pb were below instrumental detection limits. Descriptive pooled-soil analyses showed lower electrical conductivity and total and fecal coliform counts under TW than UTW. Fruit-metal and soil assessments were restricted to FW, TW, and UTW at 80% field capacity. Under the tested conditions, TW maintained substantial squash biomass while reducing measured fruit-metal exposure relative to UTW.