100 gph Portable Unit for Surface Water RO Pretreatment
A 100 gph CMF potable unit has been built to facilitate product demonstration and pilot studies. The figure on the right shows the unit and its process diagram. The CMF concept originated from a filter designed by FSI for an Army field RO pretreatment application where the goal for the design was for it to be simple and robust. The core technology in the CMF is Dean Flow, which is generated when the processed flow passes through the curved flow path. By taking advantage of the high shear and rigorous mass-mixing characteristics of the flow, it creates a self-cleaning mechanism without any moving parts or additional mechanical components. The self-cleaning mechanism allows the CMF to survive for days (with the designed 100 gph output) treating highly challenged water (SDI = 6.7) without any chemical pretreatment. The typical SDI of the effluent is less than 2. In many cases, a conventional straight membrane filter (SMF) that has the same type of membrane and comparable surface area can survive only hours based on a side-by-side direct comparison test.
The unit contains four coils mounted under the cover of a 10-gallon tank with dimensions of 10” x 14.5” x 18” as shown in the picture. The overall membrane area of the coils is 48 ft2, which is about equivalent to a 4” x 40” membrane filter element. Considering the performance of the CMF can double the performance of the SMF for a typical long-term service, the system output can be equivalent to a conventional system that is composed of two 4” x 40” membrane filter cartridges. The stand-alone unit consists of a 5” x 20” prefilter housing (for a standard 2.5” x 20” cartridge filter), a feed pump, and the piping assembly that is conveniently arranged on the tank cover to interface with other components. All these components can be arranged in a compact structural frame with overall dimensions of 20” x 18” x 24”. The unit weighs only around 50 lbs making it highly portable and convenient to be handled by one person.