Water Treatment for Small Public Supplies

The project successfully demonstrated the application of reverse osmosis and electrodialysis as methods for small New Mexico communities to upgrade current drinking water supplies to meet the National Drinking Water Act standards. Nine communities were visited. In each community the mobile demonstration unit was operated from 500 to 2000 hours using feed from the present drinking water supply. In all cases product water, as certified by the appropriate state agency (EID), met drinking water standards. Operating data has been reported. m is report presents engineering design data for the evaluation of electrodialysis, reverse osmosis and ion exchange unit operations for application in New Mexico’s drinking water systems. m e 9 communities are used as example cases.

In addition this project evaluated the potential for selectively removing ionized contaminants (cations) through precipitation as sulfides. Cadmium, mercury and zinc were examined. Experimental studies were conducted by developing a technique appropriate for a stopped-flow spectrophotometer. The initial data indicate that such a method would be appropriate under specialized conditions, e.g. the water has low TDS and high concentrations of only one or two of the cations. This experimental technique was also applied to study the removal of fluoride as calcium fluoride. To achieve reasonable precipitation rates and sedimentation rates a large excess of calcium must be used. Consideration of the effect of calcium on the drinking water quality would be required.

Project Number T-0009