EPA Review - Rochem PF Module

The PFM technology can utilize reverse osmosis (RO), ultrafiltration (UF), or microfiltration (MF) membrane ma- terials, depending on the application. The membranes are generally more permeable to water than to contami- nants or impurities. RO membranes are most commonly used with this technology. They can reject dissolved and suspended solids, dissolved salts and ions, and many low and most high molecular weight organic compounds (1). In RO, water in the feed is forced through a mem- brane by applied pressure which exceeds the osmotic pressure of the feed. This water, called permeate, has a lower concentration of contaminants. The impurities are selectively rejected by the membranes and are thus concentrated in the concentrate left behind. The percent- age of water that passes through the membranes is a function of operating pressure, membrane type, and con- centration and chemical characteristics of the contami- nants. The PFM technology utilized thin-film composite (TFC) RO membranes during the Demonstration at the Central Landfill.
The patented membrane module features larger feed flow channels and a higher feed flow velocity than con- ventional membrane separation systems. According to the technology developer, these characteristics allow the PFM greater tolerance for dissolved solids and turbidity, and a greater resistance to membrane fouling and scal- ing. Suspended particulates are readily flushed away from the membrane during operation. The high flow velocity, short feed water path across each membrane, and the circuitous flow path create turbulent mixing to reduce boundary layer effects and minimize membrane fouling and scaling. In addition, the developer claims that the design of the PFM allows easy cleaning and mainte- nance of the membranes—the open channels facilitate rinsing and cleansing of particulate matter, and mem- branes can be removed as needed from modules for replacement. (United States Environmental Protection Agency - EPA)