AWWA MTC61123

Submerged systems are increasingly being used in water and wastewater treatment applications because of the relatively low operating costs associated with submerged membrane systems compared to their external counterparts. However, the operating costs associated with submerged membrane systems are still relatively high when compared to that associated with conventional treatment technologies such as sand filtration. The magnitude of the permeate flux that can be maintained is the most significant factor affecting the capital and operating costs associated with submerged membrane systems. The current bench-scale approach used to assess the performance of submerged membrane systems does not provide the information that is necessary to design full-scale systems. As a result, the design of full-scale systems is based on a time and capital extensive trial and error approach using relatively large pilot-scale systems. The objective of this study was to develop a method for generating the data necessary for full-scale designs based on bench scale testing. This approach is based on a better understanding of the mechanisms behind the mass transfer at the membrane surface. The primary factor that causes the increase in the trans-membrane pressure during the operation of the membrane is the occurrence of reversible and irreversible fouling on the membrane surface. The determination of the reversible and the irreversible fouling coefficients were conducted through bench scale experiments for a chosen source water, membrane configuration and hydrodynamic condition. (The approach described herein can be used to determine the fouling coefficients for different source water, membrane configuration and hydrodynamic conditions.) The extent of irreversible fouling was found to be a function of the inverse of the permeate flux through the membrane. For the raw water used, the irreversible fouling coefficient at different permeate fluxes (Jv) can be estimated from the slope of the regression line. Includes 3 references, figures.