Membrane fouling simulator

A membrane fouling simulator (MFS) provides a similar visualization method to DOTM and DVO. This technique features microscopic visualization of the surface of a spiral wound membrane and a crossflow membrane module constructed from stainless steel plate. TMP during filtration is also measured, while fouling deposition of biomass on spacer is visualized simultaneously. MFS is easy to handle, simple, robust and small, with a flow capacity of 15-25 Lh [70, 71]. 

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As discussed, NF process simulation offers some possible process optimization by predicting the membrane-fouling mechanisms and sources of performance deterioration. However, membrane modification and fabrication stiU ranains as one of the most attractive research strategies, offering a complete solution to the drawbacks associated with NF membrane applications. Development of new manbrane materials with special features such as antifouling, biocompatibility, and functionality has become the current trend in NF research. 

FIGURE 3.4 Biofouling reduces the exchange kinetics of PRCs (deuterated acenaphthene and fluorene) between the nonpolar Chemcatcher sampler (fitted with either fouled or unfouled LDPE membranes) and water. The experiment was performed in a laboratory flow-through calibration system at a water temperature of 11°C with simulated water turbulence of 40 rpm. MD(t)/MD(0) is the fraction of the PRC remaining in the sampler during exposure. 

Void [52] developed a variety of ballistic deposition models to simulate sedimentation processes. Void used ballistic models to determine deposition densities for spherical particles which traveled via vertical paths and were deposited on horizontal surfaces. Recently, Schmitz et al. [53] used a ballistic aggregation model to describe particle aggregation at the surface of a crossflow microfiltration membrane. Schmitz and co-workers were able to account for interfacial forces empirically, and demonstrated the influence of physical and chemical variables on the resulting morphology of the fouling deposits (such as aggregate density variation with depth, and influence of shear flow and re-entrainment properties on fouling deposit density and porosity). 

In addition to the Navier-Stokes equations, the convective diffusion or mass balance equations need to be considered. Filtration is included in the simulation by preventing convection or diffusion of the retained species. The porosity of the membrane is assumed to decrease exponentially with time as a result of fouling. Wai and Fumeaux [1990] modeled the filtration of a 0.2 pm membrane with a central transverse filtrate outlet across the membrane support. They performed transient calculations to predict the flux reduction as a function of time due to fouling. Different membrane or membrane reactor designs can be evaluated by CFD with an ever decreasing amount of computational time. 

Gufllen-Burrieza, E., R. Thomas, B. Mansoor, D. Johnson, N. Hilal, and ArafaL H. 2013. Effect of Dry-Out on the Fouling of PVDF and PTFE Membranes Under Conditions Simulating Intermittent Seawater Membrane Distillation (SWMD). Journal of Membrane Science 43% 126-139. doi 10.1016/j.memsci.2013.03.014. 

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