Stormwater Pond Sediment De-watering by Anionic PAM at Low Temperature

Abstract

Storm water ponds have been widely constructed over the past four decades as part of municipal storm water drainage systems. These ponds are designed to collect neighborhood storm water run-off to reduce flooding, but can also improve the quality of water discharged to surface water bodies by allowing sediments to drop out of the water column. This sediment gradually accumulates at the bottom of the storm water pond, necessitating occasional dredging. Polyacrylamides (PAM) offer an option to decrease the water content, and therefore weight and volume, of this pond sediment before dredging. This study aimed to improve understanding of the performance of PAM-based sediment dewatering in different conditions, with a focus on the low northern temperatures of Canada. First, the characteristics of storm water pond sediments were reported. Then, dose and temperature effects of PAM were tested. The results indicated that the best dose of PAM (Clearflow Enviro Systems Inc. Soil Lynx 398) to be applied was 0.3g/L when treating pond sediment. The water content of sediment cake increased with increasing PAM concentration when PAM concentration was at 0.3-5 g/L. Meanwhile, in terms of temperature effects for a range of 4-30°C, the water content did not show any significant change (p > 0.05). Other parameters such as turbidity, initial settling rate, sediment volume were also measured in this study. The potential mechanisms involved were discussed as well.