The biological treatment of high salinity synthetic oilfield produced water in a submerged membrane bioreactor using a halophilic bacterial consortium

Abstract

Background Produced water (PW) is the most important wastewater of the oil industry and if disposed of without adequate treatment can cause serious environmental pollution. Biological treatment is one option explored in recent years for treatment of PW but traditional biological processes potentially fail when the salinity level of the PW is high. In the present study, a halophilic bacterial consortium was employed for treatment of high salinity synthetic PW in a membrane bioreactor (MBR). Results During the 112 days operation of the MBR at hydraulic retention time (HRT) and sludge retention time (SRT) of 48 h and 80 days respectively, there was a consistently low turbidity in the MBR effluent. Oil and grease (O&G) content of the effluent was also consistently below international limits for discharge to the sea or re‐injection to oil wells. With increase in organic loading rate from 0.3 to 0.9 kg COD m−3 d−1, O&G removal efficiency increased from 89.2% to 95.5% whereas chemical oxygen demand (COD) removal efficiency (c. 83%) did not change. Also, the transmembrane pressure during operation of the MBR remained in the range 1–2 kPa. Conclusion The results of the present study indicate the very good potential of the MBR, both in terms of removal performance and membrane fouling, for treatment of high salinity PW. © 2013 Society of Chemical Industry

Biological Treatment of Synthetic Oilfield-Produced Water in Activated Sludge Using a Consortium of Endogenous Bacteria Isolated from A Tropical Area

“…In the other hand, the synthetic oilfield-produced water was used throughout our study to determine the capability of strains of bacteria to degrade organic compounds. The synthetic oilfield-produced water was prepared by mixing crude oil (1.5 mL L -1 ) and salt water (real sea water and tap water) in a container, as described in the literature [12,16]. The C/N/P ratio of the medium was adjusted to approximately 100/5/1 by adding appropriate concentrations of (NH 4 ) 2 SO 4 and KH 2 PO 4 to the synthetic oilfieldproduced water.…”

“…This suggested that the oilfieldproduced water had a lack of nutrients (nitrogen and phosphate). It has been reported that an appropriate composition of nutrients is an important factor in the degradation of organic compounds, especially for hydrocarbon degradation [12,13]. A sufficient amount of nutrients in the wastewater can stimulate the bacteria activity, leading to high removal of the targeted contaminants.…”

“…However, with respect to time, the microorganisms recovered and adapted to the changed loading conditions and eventually reached steady-state biodegradation [33]. Under steady-state conditions, the concentrations of the COD effluent for each HRT (20,12,8 ) were slightly decreased as the HRT and initial COD concentration decreased. However, the concentrations of the COD effluent increased as the SRT decreased.…”

“…However, since oilfield-produced water contains toxic substances that can inhibit bacterial activity, the application of appropriate bacteria is important. Several strains of bacteria, including Pseudomonas, Marinobacter, Halomonas, Aeromonas, Bacillus, Ochrobactrum, Achromobacter, and Rhodococcus, have shown good performance in the removal of organic compounds in oil-contaminated wastewater [9][10][11][12]. It has been reported that the performances of these bacteria depend on the concentration of petroleum hydrocarbon [2], the salinity/total dissolved solid (TDS) concentration [9], the nutrient composition [13], and other environmental conditions.…”

Challenges and Opportunities in Produced Water and Drilling Waste Treatment Techniques to Mitigate the Adverse Environmental Impacts

“…The high level of salinity in PW limits conventional bioremediation process and its application in agriculture and power plants for its nature of corrosion. A recent study by Sharghi et al [13] designed a membrane bioreactor to biodegrade high salinity synthetic oilfield produced, which achieves 89.2% and 95.5% oil and gas removal efficiency, respectively. The effluent of the membrane bioreactor is consistently below international standards for disposal to sea or reinjection to oil wells.…”