AWWA WQTC58828

As the elevation of Lake Mead decreases due to drought, the Southern Nevada Water Authority (SNWA) has been challenged with addressing new water quality issues. The SNWA can produce 750-MGD between two direct filtration water treatment plants. The intake structures for these plants have recently become more influenced by surface water than in past years resulting in more particles, inorganic contaminants, organic matter, and higher temperatures. Dissolved air flotation (DAF) was determined to be a possible solution to resolve some of these issues. DAF could be retrofitted into the existing hydraulic grade line of the plant while minimizing the required footprint. A two-month pilot study showed DAF coupled with enhanced coagulation could provide adequate total organic carbon and arsenic removal. Another pilot plant study showed that adequate algae removal could be achieved in order to extend filter run times during high production periods. Overall, the SNWA has been pleased with the results of these studies and has initiated a conceptual level study to further investigate the feasibility of a DAF retrofit. Includes reference, tables, figures.