A Real-Time Gas Sensor Network with Adaptive Feedback Control for Automated Composting Management
Naser A.G. Nawi N.M. Zakaria M.R. Kassim M.S.M. Mutalovich A.A. Katibi K.K.
November 2025Multidisciplinary Digital Publishing Institute (MDPI)
Sustainability (Switzerland)
2025#17Issue 22
This study addressed the persistent limitation of discontinuous and labor-intensive compost monitoring procedures by developing and field-validating a low-cost sensor system for monitoring oxygen (O2), carbon dioxide (CO2), and methane (CH4) under tropical windrow conditions. In contrast to laboratory-restricted studies, this framework integrated rigorous calibration, multi-layer statistical validation, and process optimization into a unified, real-time adaptive design. Experimental validation was performed across three independent composting replicates to ensure reproducibility and account for environmental variability. Calibration using ISO-traceable gas standards generated linear correction models, confirming sensor accuracy within ±1.5% for O2, ±304 ppm for CO2, and ±1.3 ppm for CH4. Expanded uncertainties (U95) remained within acceptable limits for composting applications, reinforcing the precision and reproducibility of the calibration framework. Sensor reliability and agreement with reference instruments were statistically validated using analysis of variance (ANOVA), intraclass correlation coefficient (ICC), and Bland–Altman analysis. Validation against a reference multi-gas analyzer demonstrated laboratory-grade accuracy, with ICC values exceeding 0.97, ANOVA showing no significant phase-wise differences (p > 0.95), and Bland–Altman plots confirming near-zero bias and narrow agreement limits. Ecological interdependencies were also captured, with O2 strongly anticorrelated to CO2 (r = −0.967) and CH4 moderately correlated with pH (r = 0.756), consistent with microbial respiration and methanogenic activities. Nutrient analyses indicated compost maturity, marked by increases in nitrogen (+31.7%), phosphorus (+87.7%), and potassium (+92.3%). Regression analysis revealed that ambient temperature explained 25.8% of CO2 variability (slope = 520 ppm °C−1, p = 0.021), whereas O2 and CH4 remained unaffected. Overall, these findings validate the developed sensors as accurate and resilient tools, enabling real-time adaptive intervention, advancing sustainable waste valorization, and aligning with the United Nations Sustainable Development Goals (SDGs) 12 and 13.
composting , greenhouse gases , real-time monitoring , sensor validation , sustainable agriculture
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Department of Agricultural Machinery and Equipment, Faculty of Agriculture, Tikrit University, Tikrit, 34001, Iraq
Department of Biological & Agricultural Engineering, Faculty of Engineering, Universiti Putra Malaysia, Serdang, 43400, Malaysia
Institute of Plantation Studies, Universiti Putra Malaysia, Serdang, 43400, Malaysia
Department of Bioprocess Technology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang 43400, Malaysia
Research Laboratory Innovative Water Treatment Systems, M. Auezov South Kazakhstan University, Shymkent, 16000, Kazakhstan
Department of Food and Agricultural Engineering, Faculty of Engineering and Technology, Kwara State University, Ilorin, Malete, 23431, Nigeria
Department of Agricultural Machinery and Equipment
Department of Biological & Agricultural Engineering
Institute of Plantation Studies
Department of Bioprocess Technology
Research Laboratory Innovative Water Treatment Systems
Department of Food and Agricultural Engineering
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