Ultra filtration (UF) is membrane separation process, similar to Reverse Osmosis (RO) process. The difference is that, with the UF, suspended solids are retained but some dissolved solids are allowed to pass through the membrane. So the (UF) process is not able to remove dissolved solids from the water, where the (RO) can. The (UF) is an inexpensive alternative to the (RO), but not as efficient.
