On-line measurement of gas production rates

Gas evolution rates represent an important variable to track in biological and certain electrochemical processes. Accurate gas flow rate sensors exist for gas streams possessing a pressure head, such as when pressurized air or oxygen is delivered to a fermentation process. However, these devices impose pressure heads that can inhibit gas production and, therefore, yield false measurements. Examples of effected processes would include electrochemical production of a gas at the electrode (e.g., electrolysis) or anaerobic fermentation (e.g., anaerobic production of methane). In this work, we present an on-line gas measurement technique that measures on-line gas production from an anaerobic microbial process that is continuously fed simulated food waste over a 6-month period. Commentary is given on the sensor's accuracy and ease of use within the context of long-term operation, ability to measure both low and high gas production rates, as well as its potential for process control and system-health monitoring.