A new approach using an open-source low cost system for monitoring and controlling biogas production from dairy wastewater

Abstract

Abstract Biogas plants can effectively treat various sources of organic wastes and recover energy from biomass. However, anaerobic digestion (AD) is highly sensitive to process disturbances, which can affect the biogas production efficiency. Online process monitoring/controlling can be used to ensure efficient and stable biogas production, but automated instruments are still associated with high costs. Therefore, this study developed a low-cost system, using the open-source platform Arduino and its components, to monitor/control some AD variables. To test the developed system (DS), some AD variables of the dairy wastewater inoculated with sewage sludge digestion was monitored/controlled in the liquid phase (pH, temperature) and in the gas phase (pressure, methane yield, biogas volume). The batch experiment was conducted in mesophilic conditions (38 °C), with an inoculum/substrate ratio of 1:2 for 21 days, and it was also evaluated in terms of volatile solids (VS) and chemical oxygen demand (COD) removal. The DS maintained the desired pH and temperature conditions and informed an average cumulative biogas and methane concentration of 675.2 mL and 51.46%, respectively. The VS and COD removal rate obtained after the digestion was 45.35% and 80.1%, respectively. At the end of AD, an ecotoxicity test using Lactuca sativa seeds was performed and high digestate concentrations exhibited toxicity. Finally, the apparatus construction was feasible for the proposed work, indicating its economic potential viability.