Innovative reuse of drinking water sludge for the treatment of petroleum produced water to enhance oil recovery

Abstract

Using treated petroleum produced water (PPW) as injected water, for enhancing oil recovery, is important in petroleum industry. The process of water reuse is a cost-effective method. On the contrary, injection of inadequately treated water could induce scale formation. In the present study oil-free petroleum produced water (PPW) was treated to obtain water without scale tendency by using the water treatment sludge (WTS) produced from the Drinking Water Treatment Plants (DWTP). The WTS is usually accumulated in the DWTP as solid useless solid wastes. The characterization of the washed and dried WTS was investigated extensively by scanning electron microscope (SEM), Energy Dispersive X-Ray (EDAX), Dynamic light scattering (DLS), and Surface area analyzer. It was found that the average particle size of WTS is 47.34 nm. The main constituents of the WTS are MgO, Al2O3, SiO2, CaO, and Fe2O3. This WTS was reused for the treatment of oil-free PPW, where the chemical and physical characteristics of PPW before and after treatment were determined. The present study showed that the optimum WTS dose was 3 g/l at which the salinity, alkalinity, TDS, conductivity, hardness, cations and anions of the PPW were significantly decreased. The overall results revealed that by decreasing the cations and anions of PPW, the later has no any tendency to form scale. Therefore, the treated PPW could be used again to enhance oil recovery without any concern of scale formation, water-saving, as well as protecting the environment from the discharge of such polluted water.