AWWA ACE61766

The City of Winnipeg completed an intensive Phase 2 pilot water treatment program in 1997. The Phase 2 program tested the most suitable treatment processes for Winnipeg's water quality on an annual cycle and resulted in a recommendation for a baseline water treatment process, which included conventional dissolved air flotation (DAF). In November 2002, the use of high-rate DAF was identified as a potential cost savings alternative for consideration by the City. In 2003, the City contracted a consultant team from Earth Tech and CH2M HILL to determine the suitability and limits of the high-rate DAF process through pilot testing. The high-rate DAF pilot tests were completed in December 2003 and the suitability of high-rate DAF was determined by comparing the process performance with data from the Phase 2 testing. Based on the success of the high-rate DAF pilot trials, it was recommended that high-rate DAF be considered as a viable alternative to conventional DAF for the City's full scale Water Treatment Plant. In August 2004, the City contracted the consultant team to design the full scale water treatment plant. The new treatment plant will use a multiple barrier approach that will further protect the public from waterborne diseases, improve the aesthetic quality of the water and help it comply with current and anticipated Canadian Drinking Water Quality Guidelines and Provincial standards and regulations. High-rate DAF is a relatively new technology and there is currently only one manufacturer with significant full scale North American experience (Infilco-Degremont's AquaDAF™ system). Only four full scale AquaDAF™ systems existed worldwide at the time of the pilot testing. The AquaDAF™ design is patented, and thus the full scale equipment procurement method represents a key component of the full scale design. A competitive tendering process between conventional and high-rate DAF incorporating detailed facility life cycle costing, as well as non-economic evaluation criteria, was selected. Full scale DAF design optimization includes the flocculation time and mixing energies, flocculation aid chemical requirements, DAF design loading rate, mechanical float removal, DAF saturator design, recycle requirements, and the number and size of DAF basins. The design plant flow is 400 ML/day, which will represent the largest DAF system in North America. If high-rate DAF is selected, the high-rate DAF design will represent the highest DAF loading rate (36 m/hr in warm water conditions) among existing full scale installations. The City of Winnipeg Water Treatment Plant is scheduled to be constructed and in operation by the end of 2007. Includes 2 references, tables, figures.