Submerged membranes features

Submerged (or immersed) membranes are now commonplace in advanced water and wastewater applications. However, this is a relatively recent development for example, the subject does not rate a mention in Membrane Handbook (Ho and Sirkar, 1992) and only has the briefest mention in Water Treatment Membrane Processes (Mallevialle et al., 1996). This chapter provides an overview of submerged membranes, from basic features to practical aspects and applications. We wiU start with the background to this development. 

Figure 10.1 Schematic showing common features of submerged membrane system.

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. 

In summary, the spatial and temporal features of submerged membranes in bubbly flow complicate the definition of critical flux in these systems. However, in practice it is found that sustainable flux can be achieved and that it is improved by bubbling. 

Submerged membranes are now an established feature in the water industry for water treatment, water process pretreatment, and wastewater treatment. The following sections provide brief comments on these applications. 

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