Application of phosphate water and slime in agriculture: investigation of the mobility of the pollutants using hydrologic modeling

The use of phosphate slime or phosphate water in a Mediterranean region (Gafsa, Tunisia) was
investigated through hydrologic modeling. The simulations were made using the Hydrus 1D
software package for a typical soil in the area of Gafsa (Tunisia). Two main applications were
examined: mixing the surface soil with the phosphate slime and irrigating with polluted (phosphate)
water or irrigating only with phosphate water. The elements under study were Cd, Cr, Ni, and Sr.
The results show that there is no significant risk of groundwater pollution with these elements if the
phosphate slime or the phosphate water is used for agricultural purposes. The addition of slime in
the upper soil layer retards the mobility of the pollutants. The results also show that the mobility of
these elements is highly dependent on the applied irrigation dose. These pollutants need high
amounts of water in order to reach great depths. This research was carried out in the framework of
the EU project “Integrated water management of Mediterranean phosphate mining and local
agricultural systems” (ELMAA).