AWWA WQTC64188

Meeting water supply needs in the Western U.S. means that many communities are exploring opportunities to make use of all available water supplies. In many regions, "first-use" water supplies are no longer available, or their development represents unacceptable environmental impacts. Water utilities are faced with the challenge of improving the reliability of their water supply, while protecting public health, and meeting their commitments to their customers for high-quality water. Natural purification strategies are an excellent means of meeting these commitments, and are cost-effective and environmentally sustainable. This paper focuses on the capabilities of these natural systems to remove nitrate and organic carbon. In this study, riverbank filtration (RBF) and aquifer recharge and recovery (ARR) are utilized to pre-purify the source water, prior to advanced water treatment in a physical/chemical water treatment plant. In this project, the two systems are operated in series; RBF followed by ARR. This research focused on the treatment strategy of employing these two technologies in series for removing nitrate from source water. To accomplish this, both laboratory-scale column studies were conducted and a field-scale RBF site was monitored for denitrification. Results showed that RBF treatment effectively removed nitrate year-around, averaging greater than 70% nitrate removal. Column studies suggested that denitrification will continue during ARR treatment, although a longer treatment interval was required. This result was attributed to the depletion of the primary electron donor, assimilable organic carbon. Includes 16 references, table, figures.