First tests of using an electronic nose to control biogas plant efficiency

The demand for online monitoring and control of biogas process is increasing, since better monitoring and control system can improve process plants stability and economy. A number of parameters,such as gas production, pH, alkalinity, Volatile Fatty Acids (VFA) and H2, in both the liquid and the gas phase have been suggested as process indicators. For different reasons these indicators do not offer enough information to build a consistent feedback control able to promptly forecast and solve plants working problems. The study proposes the use of unconventional complex sensors as a possible solution to engineer a reliable control system. Tests to analyze the biogas coming from a plant were performed using an electronic nose (Airsense PEN 2, AIRSENSE Analytics GmbH). In particular, a 108 olfactometric fingerprinting reference database obtained by different combination of VFA (acetic, propionic e butyric acids, pure or in solution with water) was initially determined. As a second step, the e-nose was tested to verify a potential difference in the analysis of gases emitted by digested manure. Statistic multivariate analysis confirm that the e-nose can distinguish the manure and digester mixed liquor aromatic emission proving the possibility of using this technology as possible base for a biogas control system.