AWWA ACE59825

This paper describes the results of a pilot-scale Actiflo® waste treatment investigation conducted at the City of Calgary's Glenmore Water Treatment Plant (WTP) from April to June 2003. In addition to Actiflo pilot testing, a pilot-scale clarifier-thickener was used to evaluate sludge thickening. The clarifier-thickener consisted of a flocculation tank followed by an integrated tube settler unit located above a gravity sludge thickener. Performance of the clarifier-thickener was excellent. At a surface loading rate of 5.6 m/h, solids content in the thickened sludge ranged from 1% with no polymer addition to 9% with the addition of 0.5 mg/L of anionic polymer. Thickener supernatant ranged from 1-4 NTU, depending on polymer dose. The dewaterability of the thickened sludge was also examined as part of this study. Sludge from the clarifier-thickener was sent offsite for bench-scale centrifuge and plate filter press tests. Dewatered cake solids ranged from 20-40% from the centrifuge tests, using an anionic polymer with the centrifuge. It was found that the ease of dewatering was affected by the polymer dose added in the thickener-clarifier. In some instances, excessive polymer doses in the thickener-clarifier resulted in poor sludge dewaterability, and low final solids content. Bench-scale plate filter press tests resulted in dewatered cake solids in the range of 20-40%. Best results with the filter press were seen with the addition of lime and polymer to the thickened sludge. Includes tables, figures.