The Effect of Short-Term Irrigation of TWW on the State of Soils, Groundwater and Vegetation in the Cebala Borj-Touil Area (Tunisia)

Treated wastewater (TWW) has been used for the irrigation of a plot located in the periphery of Cebala—Borj Touil (Tunisia), the largest area irrigated with TWW since 1989. Samples from wastewater, groundwater, soils and corn crops ( Zea Mays ) have been taken. Physicochemical parameters and heavy metals were analyzed. The results of the experiment showed a distinct decrease in soil pH and increase of salinity accompanied by an increase of Na + and Cl – concentrations. Irrigation increased the heavy metals especially in the top layer from 0–30 cm. The most abundant heavy metals were Cd and Cr. The groundwater quality meets the Tunisian standard. Results for corn showed that irrigation with treated wastewater increased potassium content in the stems and seeds and sodium content in the stems and roots. The heavy metals Cd, Fe, Pb and Cr increased: Cr, Fe and Zn in roots and Cr, Mn and Zn in seeds. Absorption factor values were, in order, Fe > Ni > Zn > Mn > Cu > Co > Pb > Cr > Cd, whereas, translocation factor values were, in order, Cu > Zn > Co > Mn > Cd > Cr > Fe > Pb > Ni.