New insights into membrane fouling in water and wastewater treatment by material properties characterisation
Gel layer formation on the membrane surface during filtration plays a significant role in membrane fouling that,in many instances,controls water production and energy consumption in the treatment of waters and wastewaters.In this presentation,a steady state approach to determining the matedal properties of fouling layers is described.The material properties,once determined,can be used to describe the filtration behavior over a range of conditions.In this paper,we describe the application of this approach to a gel-forming material.Alginate is selected as a model of the polysaccharides prevalent in wastewaters which,on membrane filtration,may form a gel on the membrane surface Which subsequently limits filtrate throughput.We show that over the range of the applied pressures of 11.7 kPa to 135 kPa,constant pressure ultraffltration of alginate follows the behavior of cake filtration.The material properties of the alginate are determined by the employment of the previously developed steady state filtration approach.The consolidation of the gel layer iS found to be controlled by the hydraulic flow resistance rather than the rearrangement of particles.Under these conditions,it is valid to apply the derived material properties for the quantification of both constant pressure and constant flux filtration.The gel layer formed from alginate is very compressible and shown to be far from uniform over its depth.Within the range of the applied pressures,the gel layer is very porous with a waater content of more thab 96％but very low permeability of less than 1×10-17m2.The material properties determined from flat sheet dead-end filtration studies can be used to describe the behaviour of fouling layers during submerged hollow fibre constant flux filtration.During hollow fiber membrane fdtration,the local flux iS neither uniform nor constant along the fiber length.Resulting in non-uniformity of the growth rate,the average porosity and the thickness of the gel layer.The non-uniformity is most apparent at the start of filtration and then gradually diminishes as the gel layer builds up with ongoing filtration.
T.David WAITE Xiao-mao WANG
School of Civil and Environmental Engineering,The University of New South Wales,Sydney,NSW 2032,Aust School of Civil and Environmental Engineering The University of New South Wales,Sydney,NSW 2032,Aust
国际会议
西安
英文
27
2008-05-15（万方平台首次上网日期，不代表论文的发表时间）