Understanding The Impact Of Entrained Gas On Flow Measurement Accuracy In Wastewater Treatment

Wastewater treatment plants (WWTPs) need accurate flow measurements for everything from process control and chemical dosing to energy management and regulatory compliance. While most common meter technologies are precise enough under normal conditions, the presence of entrained gases can throw them off. Entrained gases can come in the form of visible air bubbles introduced through turbulence or pump cavitation, as well as dissolved gases that come out of solution due to pressure or temperature changes. Aeration tanks, transfer pipelines, and pump stations can all potentially entrain air into the liquid phase. As pressure and/or temperature fluctuate, dissolved gases can form, adding to the gas content within the flow stream. This gas can interfere with the measurement process of most metering technologies. Understanding how entrained gas can disrupt flow measurement ― and the technologies that can help overcome this challenge ― are key to ensuring reliable and efficient plant operation.