Fermentation is a biologically active process that metabolizes organic products in a controlled environment. Industrial fermentation typically takes place in a sealed bioreactor comprising multiple components, including air and reagent gas inlets, a mechanical agitation system, and diagnostic inlets for process monitoring and control. Fermenters are continuously monitored to acquire information on parameters such as sample gas uptake, off-gas concentrations and dissolved species, providing the detailed information required for calculating the process respiratory coefficients – oxygen uptake and carbon dioxide production rates.
Gas analyzers are used to determine this information, providing insight into process yield, agitation efficiency, aeration, and the bioreactor’s feed distribution.
This article will explore the use of gas analyzers for fermentation monitoring in more detail:
Off-Gas Analysis in Bioreactor Monitoring
Gas analyzers for fermentation monitoring provide real-time analysis of sample off-gases for species that are critical to a fermenter’s product yield, in particular oxygen (O2) and carbon dioxide (CO2) for aerobic processes, and hydrogen (H2) and methane (CH4) in anaerobic processes – all critical in the determination of the fermentation respiratory coefficient. Multiple reactor studies, using just a single gas analyzer requires integration of the analyzer with a multi-stream valve to quantitatively assess the gas production and uptake rates for multiple gas and vapor species in real-time.
The QIC BioStream gas analyzer is a multi-stream fermentation off-gas analysis system providing for real time, sub-ppm gas concentration analyses. Sample inlets for the QIC BioStream can accommodate gas flows of up to 10 L/min, with low flow options available down to 4 ml/min. Data (both raw and derived values – RQ, OUR, CER for example), is output to OPC tags. The OPC data output uses the standard NI shared variable engine.
Complementing the off-gas data, details regarding the bioreactor’s agitation efficiency and feed distribution is obtained using a dissolved species probe.
For dissolved species analysis, special probes that sample through submerged permeable membranes are employed and supplied as part of a dedicated dissolved species gas analyzer, (our HPR-40 DSA) or as inlet attachments for the QIC BioStream system.
These gas analyzers are also routinely used to monitor fermentation product yields for ethanols, lactic acid, hydrogen gas, and more.
Gas Analyzers from Hiden Analytical
Hiden Analytical is a leading manufacturer of precision mass spectrometers for a range of research applications and industrial processes. We provide gas analyzers for both off-gas and dissolved species monitoring in fermentation processes.