A highly efficient membrane / biological process, IMAS (Integrated Membrane Activated Sludge), has been developed to dramatically lower the membrane fouling rate without additional energy input or an increase in the amount of membrane area. In fact, both energy usage and membrane area are significantly reduced compared to a conventional MBR. A demonstration project was in operation at the Eastern Municipal Water District’s Perris, CA facility from June to December 2006. The low fouling nature of IMAS generated suspended particles allows the transmembrane pressure drop to remain consistently low, even when challenged with high peak flow periods and varying influent turbidities. Although the membrane influent turbidity can vary significantly, the membrane permeate turbidity consistently remains less than 0.1 NTU.
A high efficiency combined biological & membrane process for wastewater reuse
The current trend in combined biological / membrane processes is to challenge the membrane with a high fouling environment, resulting in very costly operating procedures which are required to limit the membrane fouling rates. The MBR requires high membrane area, high energy consumption, excessive pre-screening and large equalization basins. Increasing economic, environmental and political concerns will not sustain the continued high costs and excessive associated CO2 emissions of this process trend. To date, a membrane / biological process approach which has fundamental dual goals of minimizing both membrane area and energy consumption has not only presumably contained mutually exclusive goals, it has in large part been unexplored as an option.