Optimisation of Wastewater Treatment Plant Based on Polymer and Electricity Consumption − a Case Study of Finland

Wastewater treatment plants are crucial for water management, enabling water reuse, recycling, and regulating pollutant levels. Their operation varies based on factors such as season, wastewater type, and treatment volume, impacting electricity and material consumption. Despite their longstanding use, chemical agents are often applied at constant ratios, resulting in excessive use and environmental impact. A model was employed to analyse plant operation, focusing on optimising polymer concentration and electricity demand. Polymer reduction was monitored through sedimentation kinetics at different concentrations, incorporating zeta potential measurement and particle size distribution. Sedimentation data were interpreted using a TurbiScan Lab®, examining the effect of sample collection and analysis time on sedimentation kinetics. The optimal cationic polyacrylamide concentration for treating wastewater with approximately 5 mg/L suspended particles and 5.525 mg/mL phosphorus ranged from 0.1 mg/mL to 1.3 mg/mL. In-line sensing of suspended particles can optimise polymer use. Additionally, a novel electricity operation mode was tested in a Finnish plant, presenting a model that can be extrapolated to enhance global wastewater treatment operations.