Produced water secondary treatment using waste casting sand adsorbent

Abstract

Petroleum crude is a significant fuel source and raw material for many industries. The major industrial endeavour in the world depends on crude oil. It is extracted from the reservoir by drilling and pumping. During oil recovery operations, a considerable amount of wastewater is obtained, called produced water (PW). The PW contains oil, suspended particles, dissolved salts and various chemicals in soluble and insoluble forms. Therefore PW should be adequately treated before reusing and disposing of. Even though different advanced technologies are available for treating PW, still it is not easy to remove the traces of organic compounds (residual crude oil) present in it is not easy. Removing the residual oil from the primary-treated PW is time-consuming and costly. Among the different oil residue removal processes, adsorption plays a significant role in having easy and lower operation costs. The present study used the adsorption technique to remove the residual oil from the primary-treated PW. The adsorbent waste casting sand (WCS) used in this work was obtained as waste material from foundry industries. Initially, the adsorbent was characterized by using different analytical techniques like Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-ray diffraction analysis (XRD), Brunauer-Emmett-Teller (BET) and size analysis. Different parameters that affect the adsorption process were studied and identified that oil uptake capacity increase with the increase in contact time and adsorbate concentration. In contrast, it decreases with an increase in adsorbent dosage. Langmuir isotherm model fits well, indicating monolayer adsorption. On the other hand, the kinetic data confirms that the adsorption follows a pseudo-second-order mechanism. Overall, the viability of using WCS as an adsorbent for removing traces of residual oil for secondary PW treatment was studied.