Optimization of Compressible Medium Filter for Secondary Effluent Filtration

Several innovative filtration technologies have been developed in the last two decades to decrease the backwash requirements, to increase the water production efficiency, and to improve the operational and design conditions. The Compressible Medium Filter (CMF) also known as the “Fuzzy Filter” involves the use of a synthetic compressible fiber (polyvaniladene) porous material as the filtering medium instead of conventional granular material. The optimization of the CMF operation is discussed in this paper. Both the CMF removal performance and backwash water ratio (BWR) increase significantly as the medium compression ratio (MCR) is increased. The optimum MCR (for turbidity removal purposes) is the minimum MCR that results in the required degree of turbidity removal to prevent excessive BWR. The optimum MCR for the filtration of conventional activated sludge secondary effluent (for wastewater reuse application) increases from approximately five percent to 25 percent as the average influent turbidity increases from 4 NTU to 7 NTU. The filtration model developed for CMF application can be used to predict the optimum MCR curves for different and more complex filtration conditions. Chemical requirements are also eliminated or minimized with the CMF technology by increasing the MCR when the influent conditions get worse.