Feasible Use of Electrical Conductivity for Optimizing Polymer Dosage and Mixing Time Requirement in Sludge Conditioning

Abstract

The feasible use of electrical conductivity was evaluated in this study for optimizing polymer dosage and mixing time required in the municipal biological wastewater treatment plant sludge conditioning process. The electrical conductivity could be adopted as a key indicator because it is a low cost device with acceptable accuracy and is available in any laboratory. The cationic polymer concentrations of 0, 2, 4, 6, 8, and 10 kg polymer/ton of dry sludge were applied on the 1% solids at different mixing time of 60 minutes. The centrate viscosity was used to determine the optimal dosage of polymer for the sake of comparison to the results obtained from the electrical conductivity. It was found that the electrical conductivity exhibited a similar trend to the kinematic viscosity and provided the same optimal polymer dosage of 4 kg polymer/ton of dry solids. The mixing time requirement for conditioning sludge with polymer monitored by the electrical conductivity at a 5 minute- interval was longer than 55 minutes at the mixing intensity of 120 rpm. The electrical conductivity profiles suggest that sufficient mixing time resulting in the homogenous mixture be provided, so that the optimal polymer dosage could be clearly identified.