Experimental study of the permeability of clays from the potential sites for acid effluent storage

Abstract

The protection of the underground water layer in storage of industrial waste (acid effluent) is accomplished using clays that are essential for reducing the hydraulic conductivity of natural clay liners in landfill sites. This work describes the experimental study of permeability and the characterisation of clays of the three following sites in Tunisia: Sebkhat El Malah-El Mkhacherma, Jebel Haidoudi and Zemlet El Beidha. In the laboratory, we first studied the permeability of the three clays with fresh water and with acid lixiviate (pH between 2 and 3) containing wastes. We concluded that the first site had the lowest permeability of 6.25 10 −11 m/s and a neutral pH for the recovered solution, due to the existence of carbonate in the clay. We already know that a high percentage of carbonate makes the plate alkaline; favouring all fixation modes. In a second step, mineralogical DRX study of clay of the same site (Sebkhat El Malah-El Mkhacherma) reveals significant amounts of palygorskite and the kaolinite which are strongly resistant to acid attack. Moreover, based on results of the other techniques of characterisation such as the infrared spectroscopy and the specific measurement of surface BET, we confirm that the (Sebkhat El Malah-El Mkhacherma) site is the most suitable for the storage of these acid effluent wastes.