Preparing for a New Water Treatment Technology in Kentucky: Low PressureReverse Osmosis for the Treatment of Groundwater

摘要

The City of Hardinsburg, Kentucky (City) currently owns and operates a 1.6 million gallon perrnday (MGD) surface water treatment plant located on Rough River Reservoir in the extremernsouthern portion of Breckinridge County, Kentucky. The current water treatment plant (WTP)rnobtains its water from a tributary to the main stem of the reservoir. For several years, the Cityrnhas been battling with siltation problems with the raw water intake structure and the formation ofrndisinfection/disinfectant by-products (D/DBP) due to the high organic content of the reservoir’srnwater.rnSince 1999, the City has been looking for and evaluating new and reliable raw water sources forrntheir customers. In 2001, the City made the decision to relocate the WTP to the alluvium fieldsrnalong the Ohio River in the northeast part of the county (approximately 20 miles from thernexisting WTP.) In July 2001, it was determined that an abundant source of water was availablernfor a new plant to serve the City, now and for many years into the future. However, initial waterrnquality test results, indicated high hardness (> 300 mg/l CaCO3) and high nitrate levels (8 mg/lrn±) in the groundwater source. The City was determined that the local groundwater was the bestrnavailable raw water source to use for the new WTP, as they did not want to continue facingrnproblems associated with surface water treatment of the reservoir water that they currentlyrnexperience. Based on the proposed groundwater source, the City began evaluating state-of-the-artrntreatment technologies to meet the current drinking water quality regulations as well as beingrnprepared for future regulations.rnThe treatment technology chosen was low-pressure reverse osmosis (LPRO) to remove thernhigh hardness and high levels of nitrates with one treatment process. This treatment technologyrnis the first of its kind in the State of Kentucky for the treatment of groundwater for a potablerndrinking water system. The drinking water treatment program will include an on-site membranernpilot test for the treatment of this groundwater source. This paper will discuss the proceduresrnand protocol developed for conducting the 90-day pilot study demonstrating hardness andrnnitrate removal utilizing LPRO. This paper will also discuss how the pilot study assisted in thernevaluation and development of design criteria including operating conditions, and raw waterrnblending percentages in the order to meet the water quality goals established by the City for thernfinal product.