Development of a Low-Flow Meter for Measuring Gas Production in Bioreactors

Accurate measurement of gas production from biological processes is important in many laboratory experiments. A gas flow rate measurement system, consisting of an embedded controller operating three gas meters, was developed to measure volumetric flows between 0 and 9 mL min-1 (1 atm, 273 K). The gas meter system builds on earlier pressure-based designs by adding a reference chamber to avoid errors associated with atmospheric pressure fluctuations. The controller has a keypad and LCD that guides users through operation, logs data, and can be connected to a computer for data retrieval using a custom graphical user interface. Each of the three gas meters was calibrated using a bubble meter as the standard. The error in gas flow rates measured by the calibrated gas meter is expected to be within 0.17 mL min-1 95% of the time. The gas metering system was used to measure biogas production from batch anaerobic reactors that were operated for biohydrogen production using non-fat milk as the substrate. The results show that the gas meter can be used to collect accurate and high-resolution gas flow data from laboratory bioreactors.