Don Ray, superintendent of water treatment plants for the Village of Palm Springs, sampling settled MIEX resin. |
In Florida, the Village of Palm Springs, with a utility service area population of 43,000, has already addressed the issue and is in compliance with the Stage 2 rules. In fact, their water quality, which was once very poor, is now considered among the very best in America. They achieved all this four years ago by implementing what was then a first-of-its-kind technology in America. Their success has led the way for at least a dozen other municipalities to follow.
"Our finished water used to have high color. It contained a lot of organics and minerals, and we received complaints all the time," said Bill Davis, Public Service Director for the Village of Palm Springs. "About four years ago we installed the MIEX system as a DBP precursor removal water treatment process. The water that comes out of our plant now looks and tastes better than most bottled water."
Just how good is the water in the Village of Palm Springs? In 2009 it was selected as the best tasting drinking water in Florida and finished in the top five when compared to water from across the country at the American Water Works Association Annual Conference and Exposition (ACE 2009) in San Diego. The Village's water also was selected as the best tasting water in Florida by the Florida Rural Water Association. What's more, the TTHM and HAA5 levels are now each less than 20 micrograms per liter, well below the new Stage 2 DBPR standards for drinking water.
Treatment System
The turnabout in the Village's water quality came in 2005 when their MIEX (Magnetic Ion Exchange) system from Orica Watercare went on line. The technology is simple yet effective in removing the dissolved organic carbon (DOC) that is abundant in Florida's surface and groundwater supply. MIEX, which was developed by Australia-based Orica Watercare, was at the time a mostly unknown and unproven process in the U.S. As an unknown, many civil engineers and public works directors were reluctant to try it.
"I first heard about MIEX at the 2002 WEFTEC show in Chicago from John Mushinsky of Moss-Kelley, Inc., which is Orica Watercare's representative in Florida," said Doug Hammann, P.E., of Eckler Engineering. Hammann is the consultant to the Village of Palm Springs. "We did some bench scale tests and liked the results, so we arranged a pilot test on site. The pilot testing proved that the technology could meet the project design goals, so we felt confident going forward with the project."
Although the Village of Palm Springs' two treatment plants were well maintained and relatively modern, they were not designed to remove the amount of DOC present in South Florida's raw groundwater supply. Even after chlorination, the high DOC content resulted in ugly, bad-tasting water along with relatively high levels of TTHM and HAA5. With Stage 2 DBPR deadlines on the horizon, the Village faced the possibility of two extensive treatment facility upgrades in order to be in compliance.
"They didn't want to spend $20 to $30 million to upgrade their treatment facilities when their lime softening process worked just fine," Hammann said. "They just had a precursor issue; they needed to remove the precursor, the high levels of DOC in the water. The MIEX system could be installed at the head of the plant and accomplish that purpose. Everything downstream from that point would remain the same."
Removing DOC
The MIEX technology solves the disinfection byproduct problem by removing most of the DOC from the groundwater before it enters the existing treatment processes. Disinfection byproducts such as TTHM and HAA5 resulting from chlorination treatment are greatly reduced because there is far less DOC in the water to react with the chlorine.