Heart of the Valley Sewerage District in Kaukauna, Wisconsin required high-purity water to test plant effluent for biochemical oxygen demand (BOD) and other contaminants. Testing is required to ensure that the effluent meets state and federal guidelines before discharge into the Fox River.
Laboratory manager Chad Giackino tests the facility's effluent daily, using a pure water sample as a benchmark. He used a still to make the pure water; however, it proved unreliable. Many different impurities would often remain in the water that came out of the still, such as organics, inorganics, biological products and microorganisms. Besides yielding unreliable results, the still increased testing time because the tests often had to be repeated.
Giackino switched to a PURELAB Option-R point-of-use laboratory system. This system produces water that is higher in quality (between 10 and 15 megohm-cm) than double-distilled water (typically 1.0 megohm-cm). It includes pretreatment, RO and ion exchange technologies to purify the water. A prefilter removes chlorine and particulates, the high-flux RO membrane results in high flow rates and maximizes efficiency, and the purification cartridge pack removes organic and inorganic impurities. An ultraviolet lamp keeps bacteria counts low, as does the 0.2-micron point-of-use filter. Water inside the system is recirculated to maintain quality.
Since switching from the still to the point-of-use system, Giackino has found that the quality of water in his benchmark samples has been much higher and much more predictable. "I rarely see any depletion in my benchmark samples," Giackino says, "and on the odd occasion that I do, it's minimal. I often used to see significant depletion with water from the still. Sometimes it would be clear and sometimes it would fail. The point-of-use water system gives much more reliable results, and I have to repeat far fewer tests."
SOURCE: Evoqua Water Technologies