Membrane treatment relies upon the use of porous materials to retain pollutants from the bulk water. Effective membrane filtration utilizes a pressure differential to force the water through pores to achieve target flow rates. The “tighter” the pores, the higher the required pressure to produce adequate volumes of filtered water.
Membranes are classified according to the relative amount of pressure needed to drive the separation of pollutants from water. The type of contaminants removed also depends on the specific membrane employed. “Loose” membranes require nominal pressures to achieve pollutant separations and include microfiltration (MF) and ultrafiltration (UF). Low pressure membranes are useful for the removal of bacteria, parasitic protozoa and larger particles. “Tight” systems require elevated pressures and include nanofiltration (NF) and reverse osmosis (RO) processes. High pressure membranes can be used to remove dissolved contaminants as well as particles and are increasingly common in water reuse applications where potable or near-potable standards apply.
Membrane use for production of portable water has increased due to improvements in membrane technology, reductions in the cost per gallon of finished water produced, and the requirements of the DBP/Microbial regulatory cluster. Additionally, membrane use is increasing in the wastewater market. Membranes are being used as a means of treating wastewater prior to aquifer recharge or other water reuse applications.
SMI scientists are experienced in bench-scale and pilot-scale validation of membrane treatment applications. We have completed pilot-scale studies along the North Atlantic seaboard in support of water reuse studies to determine alternate uses of secondary effluent. If you are considering an expansion of an existing system or are designing a new system, we can support you with microbial challenge experimentation to determine the actual microbial removals that can be expected with your water.