White Paper: RO Pretreatment

By Marcus N. Allhands, PhD, PE Vice President of Business Development, Orival Inc.

The RO process has recently become very efficient and economically feasible for many industrial, commercial, municipal and even residential customers. Because of the infinitesimally small entities dealt with in this technology, blinding of the membrane surface becomes a chronic problem.

To maintain the efficiency of this technology, pre-treatment must remove the greater bulk of the suspended solids to allow the membranes to efficiently remove selected dissolved solids (mostly salts) and microscopic pathogens. Bag and cartridge pre-filters with filtration degrees of 1-5 microns have traditionally been used to treat the influent to RO systems. The inherent nature of the elements in these pre-filters has restricted them to one-time use. Then they must be discarded and replaced by new elements. Under many conditions these pre-filter elements may be useful only for a few hours before replacement. This replacement activity can be very labor-intensive and quite expensive.