Desenvolvimento e avaliação preliminar de um protótipo e-Nose aplicado ao monitoramento de biogás gerado da digestão anaeróbia da vinhaça

Abstract

Monitoring the biogas produced in anaerobic reactors is important to monitor the stability of the process and support the energy use of organic waste, such as sugarcane vinasse. Currently, methods such as gas chromatography are used to evaluate the composition of biogas, but its application is punctual, depends on laboratory infrastructure and does not allow continuous monitoring in real time. In this context, electronic noses appear as a promising alternative for the qualitative monitoring of gas mixtures, as they use the joint behavior of sensors with partially selective responses. Still, there is a gap related to the use of these systems in real biogas, especially in conditions subject to humidity, operational variations, and the influence of sensor exposure history. In view of this, this work developed and evaluated, on a preliminary basis, an e-Nose prototype for qualitative monitoring of biogas produced in anaerobic reactors fed with vinasse. The system was composed of metal oxide semiconductor sensors from the MQ line, BME280 and ENS160+AHT21 sensors, multiplexer, analog-to-digital converter, valves, mini air pump, touch interface, SD card storage and data sending to the cloud. The experiments were carried out with biogas from anaerobic reactors in single-phase and two-phase configurations, with qualitative comparison in relation to gas chromatography data. The results showed that the prototype was able to operate on real biogas, perform automatic collection cycles, and record variations in sensor responses after injecting the biogas mixture with ambient air. The readings indicated noticeable changes between the preheating and analysis steps, although limitations related to cleaning between cycles, humidity, pressure stability, physical prototype adjustments, and sensor integrity over time were also observed. It is concluded that the developed e-Nose has potential as a complementary tool for the qualitative monitoring of biogas, contributing to the advancement of embedded systems applied to the monitoring of anaerobic processes.