Membrane bioreactor aeration

Tacke, D, Pinnekamp, J, Prieske, H and Kraume, M (2008), Membrane bioreactor aeration investigation of the velocity flow pattern . Water Science and Technology, 57(4) 559-565. 

Du C, Wu Z, Xiao E et al (2008) Bacterial diversity in activated sludge from a consecutively aerated submerged membrane bioreactor treating domestic waste water. J Environ Sci (China) 20(10) 1210-1217... 

Industrial hazardous wastewater can be treated aerobically in suspended biomass stirred-tank bioreactors, plug-flow bioreactors, rotating-disc contactors, packed-bed fixed-biofilm reactors (or biofilters), fluidized bed reactors, diffused aeration tanks, airlift bioreactors, jet bioreactors, membrane bioreactors, and upflow bed reactors [28,30]. 

Holakoo L., G. Nakhla, E.K. Yanful and A.S. Bassi (2005). Simultaneous nitrogen and phosphoms removal in a continuously fed and aerated membrane bioreactor. Journal of Environmental Engineering 131 1469-1472. 

Ivanovic, I. and Leiknes, T. Impact of aeration rates on particle colloidal fraction in the biofilm membrane bioreactor (BF-MBR). Proceedings, IWA 4th International Membrane Technologies Conference, 15-17 May 2007, Harrogate, UK. 

Ji, L. and Zhou, J. (2006) Influence of aeration on microbial polymers and membrane fouling in submerged membrane bioreactors. Journal of Membrane Science, 276, 168-177. 

Le-Clech, P., Jefferson, B. and Judd, S.J. (2003) Impact of aeration, solids concentration and membrane characteristics on the hydraulic performance of a membrane bioreactor. Journal of Membrane Science, 218,117—129. Le-Clech, P., Jefferson, B. and Judd, S.J. (2005) Comparison of submerged and side-stream tubular membrane bioreactor configurations. Desalination, 173, 113-122. 

Ueda, T., Hata, K., Kikuoka, Y. and Seino, O. (1997) Effects of aeration on suction pressure in a submerged membrane bioreactor. Water Research, 31 (3), 489-494. 

Oxygen transfer is an important issue in the operation of a hollow-fiber bioreactor. In these bioreactors, a membrane-based aeration system is usually included in the intracapillary recirculation loop to enrich the recirculating culture medium with oxygen. However, due to the low solubility of oxygen in aqueous solutions, the recirculation speed through the fibers must be very high. 

The chapter focuses on membrane bioreactors where a UF or MF membrane is employed for biomass retention and filtration. However, membrane bioreactors where the membrane provides a support for biofilms are an alternative form of membrane bioreactor for wastewater treatment application. Two processes, in particular, the membrane-aerated biofilm reactor (MABR) and the extractive membrane bioreactor (EMB), have seen significant interest in recent years. Figure 36.4 shows these two technologies schematically. The application of biofilms reactors for wastewater treatment systems is advantageous in view of... 

Germain E, Stephenson T, and Pearce P. Biomass characteristics and membrane aeration Toward a better understanding of membrane fouhng in submerged membrane bioreactors (MBRs). Biotechnol Bioeng. 2(X)5 90 316-322. 

Pellegrin, M.L., Tazi-Pain, A., Buisson, H., Wisniewski, C., Grasmick, A., Sequenced aeration in a membrane bioreactor Specific nitrogen removal rates. The Canadian Journal of Chemical Engineering 2002, 80(3), 386-392. 

Fan, F. S., Zhou, H. D. (2007). Interrelated effects of aeration and mixed liquor fractions on membrane fouling for submerged membrane bioreactor processes in wastewater treatment. Environmental Science Technology, 41(7), 2523-2528. 

MBR (1) [Membrane BioReactor] A system that combines a suspended growth bioreactor with a membrane filtration device. Most systems involve aeration in which the bubbles minimize fouling of the membrane anaerobic systems are used in special situations. Widely used in water and wastewater treatment since the 1980s. In 2012, it was offered by 13 companies. 

Membrane bioreactors combine the activated sludge process for wastewater treatment with biomass separation from the mixed liquor by ultra- or microfiltration membranes. Advantages are the superior effluent quality characterized by complete solids removal and disinfection, the small footprint of the plant resulting from more compact aeration tanks, the absence of a secondary sedimentation tank, and the modular construction. 

The early references to submerged membranes came from Japan. Ohkubo et al. (1988) obtained a patent describing hollow fibers in a vertical bundle in a vessel with air scour to vibrate the fibers to remove the cake. The first reported use of submerged hollow fibers in a wastewater membrane bioreactor (MBR) was by Yamamoto et al. (1989), who used fibers in a bundle and air bubbles for aeration, mixing, and induced liquid flow. Permeate was removed by suction. At that time the concept was more of a curiosity, but within a decade the submerged membrane has become the dominant approach for low-pressure membrane processing in the water and wastewater industry. 

As is the case with pure bubble columns and gas-operated loop reactors, most bioreactors in technical use are aerated with oxygen or air. Reactors with pure surface aeration, such as roller bottles, shake flasks and small stirred reactors or special reactors with membrane aeration, are exceptions. The latter are used for the cultivation of cells and organisms which are particularly sensitive to shearing (see e. g. [28 - 29]). The influence of gas bubbles in increasing stress has been described in many publications (see e.g. [4, 27, 29, 30]). In principle it can be caused by the following processes ... 

The core of double membrane stirrer perfusion bioreactors is a stirrer on which two microporous hollow fiber membranes are mounted, one of them being hydrophobic and used for bubble-free aeration, the second of them being hydrophilic and used for cell-free medium exchange [15]. This system has been reported to provide viable cell densities of 20 million cells per miUiliter for more than two months [106]. Although Lehmann et al. [15] have described the scale-up of this system to the 20-L and 150-L scale, it has been most commonly employed at the bench-scale. 

In the submerged MBR the driving force is achieved by pressurizing the bioreactor or creating negative pressure on the permeate side. A diffuser is usually placed directly beneath the membrane module to facilitate scouring on the filtration surface. Aeration and mixing are also achieved by the same unit. 

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