Oil refinery wastewater treatment using coupled electrocoagulation and fixed film biological processes |
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| Institution: | 1. Department of Civil Engineering, National Institute of Technology, Tiruchirappalli, Tamil Nadu, India;2. Department of Civil Engineering, National Institute of Technology, Calicut, Kerala, India;3. Department of Civil Engineering, Vimal Jyothi Engineering College, Chemperi, Kannur, Kerala, India;1. CIEPQPF – Centro de Investigação em Engenharia dos Processos Químicos e Produtos da Floresta, GERST – Group on Environment, Reaction, Separation and Thermodynamics, Department of Chemical Engineering, Faculty of Sciences and Technology, University of Coimbra, Pólo II, Rua Sílvio Lima, 3030-790 Coimbra, Portugal;2. Polytechnic Institute of Coimbra, Department of Chemical and Biological Engineering, Rua Pedro Nunes, Quinta da Nora, 3030-199 Coimbra, Portugal;1. Civil and Environmental Engineering Department, Amirkabir University of Technology (AUT), Hafez Ave., Tehran, 15875-4413, Iran;2. Social Determinant of Health Research Center, Qazvin University of Medical Sciences, Qazvin, Iran;1. Center for Infrastructure Research, Civil and Environmental Engineering, University of Louisville, Louisville, KY, USA;2. Civil and Environmental Engineering, K.N. Toosi University of Technology, Tehran, Iran;1. State Key Laboratory of Heavy Oil Processing, Beijing Key Laboratory of Oil & Gas Pollution Control, China University of Petroleum, 18 Fuxue Road, Changping District, Beijing 102249, PR China;2. Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan |
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| Abstract: | Oil refinery wastewater was treated using a coupled treatment process including electrocoagulation (EC) and a fixed film aerobic bioreactor. Different variables were tested to identify the best conditions using this procedure. After EC, the effluent was treated in an aerobic biofilter. EC was capable to remove over 88% of the overall chemical oxygen demand (COD) in the wastewater under the best working conditions (6.5 V, 0.1 M NaCl, 4 electrodes without initial pH adjustment) with total petroleum hydrocarbon (TPH) removal slightly higher than 80%. Aluminum release from the electrodes to the wastewater was found an important factor for the EC efficiency and closely related with several operational factors. Application of EC allowed to increase the biodegradability of the sample from 0.015, rated as non-biodegradable, up to 0.5 widely considered as biodegradable. The effluent was further treated using an aerobic biofilter inoculated with a bacterial consortium including gram positive and gram negative strains and tested for COD and TPH removal from the EC treated effluent during 30 days. Cell count showed the typical bacteria growth starting at day three and increasing up to a maximum after eight days. After day eight, cell growth showed a plateau which agreed with the highest decrease on contaminant concentration. Final TPHs concentration was found about 600 mgL?1 after 30 days whereas COD concentration after biological treatment was as low as 933 mgL?1. The coupled EC-aerobic biofilter was capable to remove up to 98% of the total TPH amount and over 95% of the COD load in the oil refinery wastewater. |
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| Keywords: | Electrocoagulation Oil refinery wastewater Aerobic biofilter Sequential water treatment Biodegradability enhancement |
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