Membrane Bioreactor (mbr) as an Advanced Wastewater Treatment Technology
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Introduction Membrane bioreactor (MBR) technology, which combines biological-activated sludge process and membrane filtration has became more popular, abundant, and accepted in recent years for the treatment of many types of wastewa- ters, whereas the conventional activated sludge (CAS) process cannot cope with either composition of wastewater or fluctuations of wastewater flow rate. MBR technology is also used in cases where demand on the quality of effluent exceeds the capability of CAS. Although MBR capital and operational costs exceed the costs of conventional process, it seems that the upgrade of conven- tional process occurs even in cases when conventional treatment works well. It can be related with increase of water price and need for water reuse as well as with more stringent regulations on the effluent quality. Along with better understanding of emerging contaminants in wastewater, their biodegradabil- ity, and with their inclusion in new regulations, MBR may become a necessary upgrade of existing technology in order to fulfill the legal requirements in wastewater treatment plants (WWTPs). The idea for coupling the activated sludge process and membrane separa- tion was firstly reported by research conducted at Rensselaer Polytechnic In- stitute, Troy, New York, and Dorr-Oliver, Inc. Milford, Connecticut, US [1, 2]. The first MBR installation (Membrane Sewage System-MST) was made by Dorr-Oliver, Inc., with flat sheet ultrafiltration plate and frame membrane. It did not gain much interest in North America but it had considerable success in Japan in the 1970s and 1980s. Before the 1990s, most of the installed MBRs were used for industrial water treatment. With the development of submerged membranes, firstly introduced by Yamamoto et al. [3], the number of MBRs treating municipal wastewater increased while the MBR market is currently experiencing accelerated growth. The global MBR market doubled over the last 5-year period and in 2005 it has reached a market value of $217 million in 2005 with a projection for the year 2010 of $360 million [4]. The MBR process can be configured in many different ways depending on project-specific nutrient removal objectives. Anoxic zones before or after the aerobic treatment may be used for denitrification, depending on the efflu- ent nitrate and total nitrogen requirements. Anaerobic zones may be used to achieve enhanced biological phosphorus removal in any of its possible config- urations. tải về 0.95 Mb. Chia sẻ với bạn bè của bạn:
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