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J Hazard Mater

Title:		Long-term operation of submerged membrane bioreactor (MBR) for the treatment of synthetic wastewater containing styrene as volatile organic compound (VOC): Effect of hydraulic retention time (HRT)
Author(s):		Fallah N; Bonakdarpour B; Nasernejad B; Alavi Moghadam MR;
Address:		"Department of Chemical Engineering, Amirkabir University of Technology, P.O. Box 15875-4413, Tehran, Iran. nfallah2001@aut.ac.ir"
Journal Title:		J Hazard Mater
Year:		2010
Volume:		20100206
Issue:		1-Mar
Page Number:		718 - 724
DOI:		10.1016/j.jhazmat.2010.02.001
ISSN/ISBN:		1873-3336 (Electronic) 0304-3894 (Linking)
Abstract:		"In this study, the membrane bioreactor (MBR) was utilized to remove styrene from a synthetic wastewater having a chemical oxygen demand (COD) and styrene concentration of 1500 mg/L and 50 mg/L, respectively. At two hydraulic retention times (HRTs) of 24 h and 18 h, the MBR was operated for a period in excess of 100 days. The HRT effects were studied and it was found out that the removal efficiency of COD and styrene for both HRTs was consistently higher than 99%. Unlike conventional activated sludge processes (CASPs), no styrene was detected in the exhaust air, which meant that biodegradation was the major styrene removal mechanism at both HRTs. The transmembrane pressure (TMP) profile during the operation of the MBR showed a fairly low and constant TMP up to day 70, after which, the TMP showed a dramatic rise, as a result of the occurrence of severe membrane fouling. It was thought that an increase in styrene loading rate, when HRT was reduced to 18 h, resulted in the release of extracellular polymeric substance (EPS) from the bacterial cells, which in turn was responsible for the rise in soluble microbial product (SMP) and sludge deflocculation. The severe fouling observed during operation of MBR at HRT of 18 h was attributed to the rise in SMP concentrations and decrease in mean floc size and increase in the proportion of small particles in the activated sludge"
Keywords:		"*Bioreactors Chromatography, Gas Membranes, Artificial Models, Statistical Organic Chemicals/*chemistry Oxygen/chemistry Particle Size Styrene/*chemistry Volatilization Waste Disposal, Fluid/*methods Water Microbiology;"
Notes:		"MedlineFallah, N Bonakdarpour, B Nasernejad, B Alavi Moghadam, M R eng Research Support, Non-U.S. Gov't Netherlands 2010/03/09 J Hazard Mater. 2010 Jun 15; 178(1-3):718-24. doi: 10.1016/j.jhazmat.2010.02.001. Epub 2010 Feb 6"