Effects of Cement Kiln Dust on pH and Phosphorus Concentrations in an Activated Sludge Wastewater Treatment System

Abstract

Abstract Cement kiln dust (CKD), the waste dust generated from a Portland cement kiln, was evaluated for its ability to increase the pH of acidic processed effluent in activated sludge wastewater treatment. Effluent samples were obtained from Corner Brook Pulp and Paper in Newfoundland, which currently uses NaOH as a pH buffer in its treatment system. Three separate effluent samples were tested. On average, 12.8 mL of a CKD neutralizing solution (0.4625 g CKD/L distilled water) raised the pH of 100 mL of effluent from pH 6.4—7.0 to pH 8.0. There was no significant problem with excess sedimentation at pH 8.0 and 9.0. However, there was a significant decrease in soluble reactive phosphorus (SRP-P) concentrations, probably through precipitation of calcium phosphate, resulting in a mean loss of 84.7 µg SRP-P per litre of CKD-treated effluent. The use of CKD as a neutralizing agent may be economically feasible, since the costs of adding increased phosphorus as nutrient were less than the costs associated with adding NaOH. Further experimentation needs to be done to determine the efficacy of CKD on a larger scale.