Efficient and cost-effective treatment of oilfield produced water by integrating advanced oxidation processes and adsorption

Produced water represents the water produced as an inevitable byproduct during oil and gas extraction in oil fields. It is considered as the largest waste stream in oil and gas industry as extraction of 1 oil barrel yields approximately 3-9 barrels of produced water. Petroleum Development Oman (PDO) alone produces 1 million cubic metres of produced water every day. Produced water is a very complex mixture which is heavily contaminated with organic (hydrocarbons, oil and grease) and inorganic pollutants (toxic metals). Due to its huge amount, complex nature, and variety of pollutants in produced water, it is very challenging to develop a suitable treatment. Currently, most of the produced water is reinjected into deep aquifers using energy-intensive high-pressure pumps which is very costly and is against the environmental policies and vision. Capital expenditure on the management of produced water is expected to double in the next five years. PDO disposes 50% of its produced water in deep water wells but they are aiming to reduce it to 22% by 2025. It should be noted that water security has been recognized as a national priority in Oman Vision 2040 and Qatar Vision 2030. Considering the water shortage, produced water is considered as a potential valuable water source that could improve the long-term water security in both countries. It is, therefore, highly important to develop suitable strategies to treat produced water in an environment-friendly and cost-effective way. Here, we propose the use of an integrated treatment based on advanced oxidation processes (AOPs- to remove hydrocarbons and other organics) and adsorption (to remove toxic metals) to effectively treat the produced water in an environment-friendly and cost-effective way. We have demonstrated proof of concept to develop magnetic, reusable and highly efficient dual functional materials ( adsorbents/catalysts). In this proposal, role of magnetic materials would be firstly evaluated to catalyze the AOPs (H2O2 based) for an effective degradation of organics in produced water (simulated as well as real produced water). Once, organics are degraded, efficiency of these materials would be optimized as adsorbents to remove toxic metals from the produced water. Magnetic nature of these materials would allow their quick separation from the reaction medium from where metals can be recovered as a valuable resource. Reusability of these materials would also be tested in multiple treatment cycles. These materials, being reusable, would lead to an efficient and cost-effective treatment. Efficiency of this system would also be compared with ferrate(VI) that has recently emerged as an innovative oxidant for quick degradation of many organic pollutants but its efficiency has never been evaluated for produced water. After oxidizing the organics, ferrate(VI) itself gets oxidized into iron minerals which can serve as viable adsorbents. Therefore, use of ferrate(VI) can allow to couple both processes (AOPs and adsorption). To summarize, this project is intended to develop an integrated treatment by comparing two different systems: i) using magnetic, reusable and highly efficient materials to catalyze AOPs followed by their use as adsorbents, or ii) using ferrate(VI) firstly as an oxidant followed by the use of its oxidation products (iron minerals) as adsorbents. We are expecting to produce 05 high quality scientific publications and a potential patent (integrated treatment system as an environmental technology) through this proposal. In addition to technology development, this project would contribute to enhancing capacity of researchers of Sultan Qaboos University and Qatar University for environmental remediation and to strengthen academia/industry cooperative relationships. Such treatment strategies would facilitate the building of relationships between university researchers and industry partners; such relationships are important first steps in supporting potential marketplace applications of research. While opening avenues for future collaborative research, academic improvement, and technology transfer, the project should ultimately benefit residents of Oman and Qatar.