City of Griffin, GA – Still Branch WTP Conversion to DAF

Raw water for the 8-MGD Still Branch Water Treatment Plant comes from a pumped storage reservoir that has a very small drainage basin. This combination results in raw water with a very low turbidity of less than 1 NTU, which makes conventional treatment challenging due to the difficulty of making a settleable floc that also provides for long filter runs. The floc that is formed in flocculation and sedimentation tends to shear easily and results in short filter runs of the downstream multi-media filters.
ESI worked with the City of Griffin to evaluate the plant in preparation for an expansion needed to meet future demands. The recommendation that resulted from the evaluation was to convert the sedimentation step prior to filtration to Dissolved Air Flotation (DAF). The DAF process requires the formation of only a small pin floc that will float instead of the denser floc required in sedimentation. The conversion to DAF designed by ESI will result in significant savings to the City of Griffin immediately after construction is completed in 2014 and in all future expansions to the facility, which was designed originally to be expanded from the initial capacity of 8 MGD to an ultimate capacity of 48 MGD.