Evaluating an e-nose ability to detect biogas plant efficiency: a case study

Abstract

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 in both the liquid and the gas phase have been suggested as process indicators (pH, alkalinity, VFA and H 2, redox potential, biogas production rate, biogas composition, FOS/TAC ratio, COD and/or VS reduction). The present study proposes the use of complex sensors as a possible solution to engineer a consistent control system. Tests were performed to analyze the biogas coming from a biogas plant in which conditions of pre-overloading and overloading were artificially inducted. The different inducted functioning conditions were recognised using a FOS/TAC tester, or the ratio volatile organic acids/alkaline buffer capacity. The FOS/TAC ratio has long been recognized extending as far as the imminent inversion of the digester biology to be detected at an early stage. Data coming from the e-nose were sorted and classified according to FOS/TAC ratio as a reference method. Not all the sensors of the e-nose were reactive to manure digestates, but four of them, sensitive to aromatic compounds, ammonia alkanes and methane, resulted crucial in the samples identification. Results confirmed that the e-nose can discriminate different digestion conditions, demonstrating the possibility to reduce the number of sensors in this innovative tool for biogas control systems. However, this instrument cannot be considered a complete alternative to traditional analysis systems, as, for example, the FOS/TAC titration, but a supporting tool for a quick analysis of the system. ARTICLE HISTORY

Electronic Noses and Their Applications for Sensory and Analytical Measurements in the Waste Management Plants—A Review

“…This work showed that gas phase relation with anaerobic process should be deeper investigated, as an EN could indicate the reactor state, focusing on the gas phase. Similar conclusions can be drown from Costa et al [183] Orzi et al [184] investigate the correlation between microbial activity (i.e., biological stability measured by aerobic OD 20 test and ABP anaerobic tests) and odor emissions from municipal solid waste during anaerobic digestion in a full-scale treatment plant considering the three stages of the process (input, digested and post-digested waste). Authors used complementary approaches for the measurement of odor impact (olfactometry) and characterization of the different groups of VOCs responsible for that odor (GC-MS and PEN2 e-nose from Airsense).…”

Plant Pest Detection Using an Artificial Nose System: A Review

“…MOS sensors are some of the most commonly used gas sensors for constructing sensor arrays due to their cost-effectiveness, reliability, and availability. They have been widely applied in agriculture and forestry industries for diagnosis of plant infection caused by fungus, bacteria, and viruses; insect damage; or mechanical damage [ 42 , 43 , 44 , 45 , 46 , 47 ]. The main advantages of MOS sensors are the fast response and recovery times, which mainly depend on the temperatures and the level of interaction between the sensors and gases [ 48 ].…”

Fuzzy Logic System for Intermixed Biogas and Photovoltaics Measurement and Control

“…Our design uses cheaper hardware and simple fuzzy logic algorithms compared to the complex pattern recognition (requiring training) algorithms. However, our method lacks the fine tuning achieved by other researchers [45].…”

“…Figure 18 shows actual display readings for the photovoltaics system. [45] is based on the e-nose. The e-nose whose design is premised on the biological method is capable of sensing a large number of gases through pattern recognition and is able to evaluate the stability of the digester [45].…”