Experimental study on accumulation of heavy metals in vegetables irrigated with treated wastewater

Abstract

Treated sewage and industrial effluents are used for irrigation of crops in developing countries which may contain heavy metals in high concentration. It can contaminate soil and accumulate in vegetables. In the present study, the vegetables were irrigated with treated wastewater brought from a nearby full-scale sewage treatment plant. The concentration levels of the Cd, Co, Cu, Mn and Zn in the leaves were found below toxic limits as prescribed in the literature. Daily intake metals values suggest that the consumption of plants grown in treated wastewater and tap water is nearly free of risks, as the dietary daily intake limits of Cu, Fe, Zn, and Mn in adults can range from 1.2 to 3 mg, 10 to 50 mg, 5 to 22 mg and 2 to 20 mg, respectively. The enrichment factor for the treated wastewater irrigated soil was found to decrease in order of Zn > Ni > Pb > Cr > Cu > Co > Mn > Cd.