Influence of Polymer Selection on Nutrient Phase Separation for Waste Activated Sludge Thickening at Bench Scale

The use of polymers to condition waste activated sludge prior to thickening is a common practice at domestic wastewater treatment plants. In this study, the performance of various commercially available granular polymers was observed. Thickening by gravity belt thickener was simulated at the bench scale, and the thickened sludge and fi ltrate produced were examined. Laboratory analysis was used to determine the differences in nutrient chemical concentration in the thickened solids and fi ltrate produced by different polymers. By examining the content of nutrient chemicals such as total Kjeldahl nitrogen (TKN), ammonia nitrogen, and total phosphorous, this research showed that polymer choice could affect the chemical composition of thickened sludge and fi ltrate with respect to nutrients. Results showed that the total phosphorous and TKN concentrations in the thickened sludge and fi ltrate were affected by polymer selection, which suggested that the chemical loading on the plant due to fi ltrate recycle, and the nutrient content of thickened sludge delivered to the digester are affected by polymer choice. Polymer optimization studies that examine nutrient properties of fi ltrate and thickened sludge beyond the basic total suspended solids analysis may be advantageous to minimize recycling of these compounds into the fi ltrate phase.