Submerged membranes concepts

Figure 10.3 Submerged membrane concepts (a) vertical HF, (b) horizontal HF, and (c) flat sheet.

According to CH2M HILL. SDC A awarded the contract to the company due to it s w ater tr eatment plant concept that uses a submerged-membrane treatment process, which produces high-quality water, is less expensive than conventional processes, and is more environmentally friendly. Tire membrane option allowed for a smaller ibotprint, less concrete, fewer chemicals to store, and fewer solids to dispose of than traditional treamient methods,... 

The concept of the helical membrane module has been tested in a submerged membrane filtration mode with bubbling used for the membrane fouling control. Liu et al. [30] showed that the helical membrane with a twisted angle of 180° could achieve a 1.46-1.69 flux enhancement, compared to the membrane modules with 0° twisted angle, in the filtration of 500 mg/L kaolin suspension under a constant TMP of 2.8 and 3.2 kPa. The particle image velocimetry (PIV) analysis [31] showed that the tortured membrane surface of the helical membrane could generate rotational flow near the membrane surface and increase the wall shear rate. 

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 pointed out by Cui et al. (2003) there arc two features of submerged membranes in a bubbling system that compheate the critical flux concept for such systems. These features relate to the spatial and temporal variation of filtration conditions, as indicated below. 

Submerged membranes have come from being a curiosity to a mainstream membrane technology in less than a decade. The concept continues to evolve and can be expected to have an increasing major role in the water industry. Potential developments could include ... 

Also, dialysis was reported to remove TMCs from reaction mixtures. No mechanical pressure is needed here, clearly facilitating the mechanical and safety requirements. The first proof of concept was given with Ru-BINAP confined in a PDMS- envelop simply submerged in the reactor. In a catalytic transfer hydrogenation, the PDMS-membrane retained the catalyst... 

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