Effect of Textile Wastewater Irrigation on Heavy Metals Accumulation in Post-harvest Soils

Abstract

Textile wastewater is used as an alternative irrigation source where freshwater is limited, but repeated application may alter soil heavy-metal status. This study evaluated heavy-metal accumulation in post-harvest soils under a vegetables-jute-T. Aman crop rotation at the Bangladesh Jute Research Institute, Central Station, Dhaka. Six treatments were evaluated: T1 control, T2                 sole RDF plus freshwater, and T3–T6 50% RDF combined with 25%, 50%, 75%, and 100% textile wastewater, respectively. Post-harvest soil samples were collected after each crop, digested using aqua regia and H₂O₂, and analysed for Zn, Cu, Ni, Fe, Cd, Cr, Pb, and Mn by flame atomic absorption spectrophotometry. Heavy-metal concentrations generally increased with increasing textile wastewater concentration, and the highest values were consistently observed in T6. Under T6, concentrations of Zn, Cu, Ni, Fe, Cd, Cr, Pb, and Mn were 30.31, 0.93, 24.74, 239.55, 0.255, 34.03, 33.79, and 2.80 ppm after jute cultivation and 38.20, 1.79, 36.22, 303.70, 0.345, 41.15, 40.22, and 6.00 ppm after red amaranth cultivation, respectively. The results indicate progressive accumulation of the measured metals across the studied crop sequence under 100% textile wastewater irrigation. Regular monitoring of wastewater quality and post-harvest soil metal concentrations is therefore warranted when textile wastewater is considered for irrigation.