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The MBR Book: Principles and Applications of Membrane

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4.1 Introduction<br />

Available <strong>and</strong> developing commercial membrane bioreactor (<strong>MBR</strong>) technologies<br />

employed for wastewater treatment can be classified according to membrane configuration:<br />

flat sheet (FS), hollow fibre (HF) <strong>and</strong> multitube (MT) (Section 2.1.3). Many<br />

such products exist <strong>and</strong> many more are being developed, <strong>and</strong> a comprehensive<br />

description <strong>of</strong> all technologies available globally is not possible. In the sections that<br />

follow, the leading technologies are described. Other technologies <strong>of</strong> interest are also<br />

outlined, for which most have reference sites (Chapter 5).<br />

4.2 Immersed FS technologies<br />

4.2.1 Kubota<br />

Commercial technologies 165<br />

<strong>The</strong> Kubota membrane module was developed in the late 1980s by the Kubota<br />

Corporation, a diversified Japanese engineering company originally best known for<br />

agricultural machinery. <strong>The</strong> development was in response to a Japanese Government<br />

initiative to encourage a new generation <strong>of</strong> a compact wastewater treatment process<br />

producing high-quality treated water. <strong>The</strong> first pilot plant demonstration <strong>of</strong> the<br />

Kubota membranes was conducted in 1990, prior to the first commercial installation<br />

soon after. <strong>The</strong>re are now over 2200 Kubota <strong>MBR</strong>s worldwide, with about 10% <strong>of</strong><br />

these installed in Europe.<br />

<strong>The</strong> original FS micr<strong>of</strong>iltration (MF) membrane, the type 510 which is still widely<br />

used, comprises a 0.5 m � 1 m flat panel, 6 mm thick, providing an effective<br />

membrane area <strong>of</strong> 0.8 m 2 . <strong>The</strong> membrane itself is a hydrophilicised, chlorinated<br />

polyethylene (PE) membrane, supported by a very robust non-woven substrate (Fig.<br />

4.1), which is ultrasonically welded on each side to an acrylonitrile butadiene<br />

styrene (ABS) resin plate with a felt spacer material between the membrane <strong>and</strong><br />

plate. <strong>The</strong> plate contains a number <strong>of</strong> narrow channels for collecting the permeate.<br />

<strong>The</strong> nominal pore size is 0.4 �m, but, due to the formation <strong>of</strong> the dynamic layer on<br />

�50 �10 000<br />

Magnification<br />

Figure 4.1 Kubota membrane showing substrate <strong>and</strong> membrane surface

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