Safer Food Production With Reclaimed Wastewater: Linking Biological Treatment, Microbial Quality, and Heavy‐Metal Risk
M. A. El‐Shawadfy, Ahmed Abukhadrah, Adel M. A. Elhdad, Shin‐ichi Morita, Emad M. Hafez, Mohamed M. Abdel‐Galeil, Zhicheng Luo, Samir I. GadowABSTRACT
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.