In-filter DAF in Australia: ''The Rous County Council application''

The raw water sources for potable water in Australia vary from turbid inland river abstractions to the soft, iron bearing reservoirs on the coast. Most sources have potential for algal blooms. Since 1980, various applications of the In-Filter DAF process to produce potable water from these sources have been very effective in Australia. In-Filter DAF is now widely accepted as a superior process for many applications. Pilot plant trials have proved the robust nature of the process when compared to sedimentation clarification or direct filtration. The reduced footprint of an In-Filter DAF water treatment plant offers substantial reductions in capital costs. The Rous County Council found that the high removal rates and resilience of the pilot plant were repeated in the operation of the full scale Nightcap Water Treatment Plant. To reduce operating costs, the filter medium for the facility was specified to allow direct filtration during those periods in which the raw water quality was good enough. However, the plant has not operated in the direct filtration mode as the DAF process has been very efficient and the small cost savings have not justified any compromise to the quality of the drinking water. From both a contractors perspective and a water authority operating a DAF plant, the process has proven to be robust, effective and therefor a low risk proposition. The real work in establishing good water treatment facilities lies in other areas such as coagulation, flocculation, control systems and controlling capital costs. However, the In-Filter DAF process provides an excellent basis for a modern water treatment plant.