19 BOONE PICKENS SCHOOL OF GEOLOGY Graduate Student Research Spotlight Valentine Ezennubia, Javier Vilcáez. Removal of oil hydrocarbons from petroleum produced water by indigenous oil degrading microbial communities. Journal of Water Process Engineering, Vol 51, 2023, Article 103400. doi.org/10.1016/j. jwpe.2022.103400 Summary of research: Petroleum-produced water (PW) is one of the most significant waste streams in the oil and gas industry and it is characterized by high concentrations of dissolved salts and oil hydrocarbons. Plugging membrane filters with oil hydrocarbons (mostly n-alkanes) constitutes one of the main barriers to treating PW for its integration into industrial and agricultural uses. Based on previous research conducted at the Geofluids and Hydrogeology Lab showing that the injection of CO2 and PW supplied with protein-rich matter could be used to recover oil from depleted oil reservoirs as methane gas, this research’s hypothesis was that stimulating the activity of methanogenic oil degrading microbial communities by combining the supply of CO¬2 as sodium bicarbonate and protein-rich matter as soy protein in anaerobic environments can result in the complete removal of oil hydrocarbons from PW. This hypothesis was tested using PW collected from oil wells in Oklahoma. Experiments aimed to determine the kinetics and degree of oil hydrocarbon degradation, assess the effect of pH and oxidation reduction potential (ORP), and elucidate the mechanism of oil degradation by the proposed stimulation method. The novelty of the proposed PW treatment method is on the synergetic effect of combining the supply of CO2 and protein-rich matter to stimulate indigenous methanogenic oil degrading microbial communities that are adapted to high salinity conditions. The potentiality of the proposed method lays on its practicality and low cost. PW storage tanks can be operated as anaerobic enclosed reactors, without additional investment, soy protein constitutes the cheapest type of protein-rich matter in the world, and the produced methane could be recovered from the anaerobic enclosed tanks for subsequent purification and commercialization. Moreover, the proposed stimulation method could be used to remediate anaerobic aquifers contaminated with oil hydrocarbons sourced from abandoned and natural leaks.
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