Membrane Bioreactor (mbr) as an Advanced Wastewater Treatment Technology
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Membrane Classification The membrane process is a very important separation process in water and wastewater technology, which becomes increasingly competitive and is supe- Membrane Bioreactor (MBR) as an Advanced Wastewater Treatment Technology 41 rior to the traditional water technology with proven performance and process economics. The most widely applied membrane separation processes are mi- crofiltration (MF), ultrafiltration (UF), nanofiltration (NF), reverse osmosis (RO), electrodialysis (ED) and electro deionization (EDI), whereas the first four processes produce permeate and concentrate. The separation ranges are as fol- lows: 100 to 1000 nm for MF, 5 to 100 nm for UF, 1 to 5 nm for NF, and 0.1 to 1 nm for RO. Firstly, application of membrane-based technologies in wastew- ater treatment was focused on tertiary treatment of secondary effluent, so as to obtain a high-quality final effluent that can be reused for different purposes. However, over the past 10 years, MBRs have emerged as an effective secondary treatment technology, whereas membranes applied are usually in the range of those of MF and UF. Membranes are usually made from different plastic and ceramic materials, but metallic membranes also exist. The most widely used materials are cellu- loses, polyamides, polysulphone, charged polysulphone and other polymeric materials such as polyacrylonitrile (PAN), polyvinylidene difluoride (PVDF), polyethylsulphone (PES), polyethylene (PE), and polypropylene (PP). All of these polymeric materials have a desirable chemical and physical resistance. They are also hydrophobic, and it is known that hydrophobic membranes are more prone to fouling than hydrophilic ones due to the fact that most interactions between the membrane and the foulants are of hydrophobic na- ture [5, 6]. All commercially available membranes are therefore modified by chemical oxidation, organic chemical reaction, plasma treatment, or by graft- ing to achieve more hydrophilic surface. This modification process usually differs one membrane from another together with the method of fabrication of the membrane module. tải về 0.95 Mb. Chia sẻ với bạn bè của bạn:
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