The effect of organic loading rate on the performance of membrane bioreactor used for the treatment of hypersaline real produced water
Paper ID : 1269-MST2015-FULL
Mehrzad Pakzadeh1, Babak Bonakdarpour2, Narges Fallah2, Elham Abdollahzadeh Sharghi *3
1Department of Chemical Engineering, Amirkabir University of Technolog
2Department of Chemical Engineering, Amirkabir University of Technology
3Department of Energy, Materials and Energy Research Center, Karaj, Iran
Produced water (PW) represents a significant waste stream of the oil and gas industry. It is a complex mixture of dissolved and particulate organic and inorganic chemicals in water that ranges from essentially fresh water to concentrated saline brine and if disposed of without suitable treatment can cause severe environmental pollution. Biological treatment is one alternative explored in recent years for treatment of PW but traditional biological processes do not have this capability when the salinity level of the PW is high. In this study, a halophilic bacterial consortium was employed for biological treatment of high salinity real PW obtained from Cheshme-Khosh oilfield in western Iran in a submerged membrane bioreactor (sMBR). During the 93 days of MBR operation at hydraulic retention time (HRT) and sludge retention time (SRT) of 96 h and 115 days, respectively, there was a consistently low turbidity in the MBR effluent (lower that 1.5 NTU). During the operation of the MBR, oil and grease (O&G) content in the effluent was also consistently below international limits for discharge to the sea or reinjection to oil wells. With increase in organic loading rate (OLR) from 0.09 to 0.3 kg COD m−3 d−1, O&G and COD removal efficiency increased from 61.5±2.8% and 49.2±1.8% to 88.7±3.7% and 77.9±1.4%, respectively. The result of GC/MS analysis confirmed the presence of hardly-biodegradable compounds in the influent. Since the most of the total petroleum hydrocarbon (TPH) compounds (97%) have been removed, the residual COD in the MBR effluent related to soluble microbial products (SMP) and hardly-biodegradable compounds other than O&G. Also, there was no pronounced membrane fouling at any time of MBR operation. 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 real PW.
Keyword: hypersaline real produced water (PW); membrane bioreactor (MBR); halophilic bacterial consortium; organic loading rate (OLR); membrane fouling
Status : Paper Accepted (Oral Presentation)