DEWATERING OPTIMIZATION AT THE PLUM ISLAND WATER RECLAMATION FACILITY USING AN INNOVATIVE TECHNOLOGY

Torque rheometers measure the viscosity-related torque caused by the resistance of a material to the applied shear and are commonly used in other fields for comparison of sample characteristics. One of the advantages of using torque rheometers is that they provide better reproducibility with conditioned sludges and they use large sample volumes enabling direct injection of polymers. This study presents torque rheology data to illustrate two different methods for polymer optimization. The methods can be used to optimize the polymer dose and mixing intensity, as well as to select the best performing product among a number of candidate polymers. The first method is used for unconditioned sludges, and utilizes the peaks observed after the polymer injection. The second method is used for conditioned sludges and utilizes the entire torque-time rheograms. Both methods were tested at the lab- and full-scale at the Plum Island Water Reclamation Facility (Charleston, SC). The methods were able to optimize the polymer dose and full-scale mixing, and reduce the polymer consumption by 50% at the treatment plant. This translates into major savings for the utility. The results of this study indicate that well-defined rheological properties of sludge provide a reliable tool for the optimization of conditioning and dewatering operations at wastewater treatment plants.