UASB reactors are widely employed in wastewater treatment due to their operational simplicity and the potential for energy recovery from biogas, although continuous, low-cost monitoring of CH4 and flow rate remains challenging. This work presents the development and validation of an IoT system for remote, real-time monitoring, integrating NDIR sensors for CH4/CO2, a temperature sensor, a pressure sensor, a thermal mass flow meter, and an ESP32 platform with web/mobile interfaces. Deployment was carried out in a bench-scale UASB reactor treating an industrial slaughterhouse effluent. Over 30 days of continuous operation, stable data transmission was recorded with an average latency of ∼1.77 s; measurements covered 42.84–76.16 NL·d–1 (flow) and 53.31–88.0% (CH4), with temperature within a narrow mesophilic range (22.25–27.80 °C) and near-zero sensor drift. Estimates based on removed chemical oxygen demand (COD), normalized to STP, yielded 45.18–74.72 NL·d–1 (flow). Temporal agreement with the measured series was observed (MAE = 6.58 NL·d–1 and 4.69 percentage points; MAPE = 9.88% and 6.69% for flow and composition, respectively). This modular, fault-tolerant architecture demonstrates feasibility for supporting operational control and assessing the methane energy potential in decentralized applications.
Nunes et al. (2026) studied this question.