A simplified open flux chamber method for the measurement of greenhouse gas emissions from activated sludge reactors

Measuring greenhouse gas emissions from wastewater treatment plants is of utmost importance in the context of climate change. However, due to their variability and complexity, it is a particularly challenging task in aerated reactors. The current methods involve capturing gas emissions from the water surface, measuring gas flow rates, and determining the concentration of the emitted gas at that location. Our study proposes a new, more efficient method that eliminates the need for gas flow rate measurements and additional equipment. The proposed technique uses a gas analyzer and a specially designed floating chamber to measure the transient trend of gas concentration within the chamber from the moment it is deployed to when it reaches a new steady state. Our research shows that this method accurately determines methane and carbon dioxide emissions from aerated reactors and potentially other gases emitted in wastewater treatment plants. It is cost effective, versatile, and simplifies the measurement process. This method facilitates the assessment of greenhouse gas emissions in wastewater treatment plants. Our findings are backed by comprehensive testing in the aeration tanks of a full-scale activated sludge plant, across diverse conditions, including fine- and coarse-bubble aeration. HIGHLIGHTS A simple chamber method is proposed to measure gas emissions in aerated reactors.; The method is designed for surface gas flow rate and concentration determination.; It utilizes only a chamber and a gas analyzer for simplicity and cost savings.; Together, these features offer a simplified tool for characterizing large-scale reactors.; The method was successfully applied to a full-scale wastewater plant.;