Pollutant Gas Distribution and Environmental Factors in a Wet Waste Treatment Plant Based on Multi-Parameter UAV Monitoring

Emissions of atmospheric pollutants such as methane (CH₄), hydrogen sulfide (H₂S), ammonia (NH₃), and volatile organic compounds (VOCs) from wet waste treatment plants pose serious environmental and health risks. Conventional monitoring methods, which rely on fixed stations or manual sampling, often face challenges such as limited spatial coverage, delayed data collection, and operational safety hazards. To address these limitations, this study developed a gas monitoring system utilizing a multi-parameter sensor integrated with an unmanned aerial vehicle (UAV). Field monitoring was conducted at a wet waste treatment plant in Shanghai to assess pollutant distribution, vertical concentration gradients, and correlations with environmental factors across different functional areas. The results revealed that CH₄ concentrations were significantly higher than those of other gases, reaching up to 1860 μg/m³ throughout the plant, making CH₄ the primary contributor to the total emission load. In contrast, H₂S and NH₃ exhibited distinct point-source characteristics, with high concentrations closely associated with specific processing stages, including the kitchen waste workshop, the catering waste workshop, the drying workshop, and the unloading hall. Although VOC concentrations were relatively low, their complex composition presented potential environmental risks. Vertical profile monitoring showed that CH₄ maintained high concentrations at all heights (1800–1900 μg/m³); NH₃ tended to accumulate in the upper sections of the facility, while H₂S concentrations gradually increased with height. Conversely, VOCs exhibited a relatively homogeneous vertical distribution across the plant. These diffusion trends suggest that NH₃ could intensify odor pollution, while VOCs may enhance ozone formation and the generation of secondary organic aerosols. Correlation analysis indicated that humidity and air pressure were key environmental factors influencing the release and dispersion of these gases. Among these factors, humidity demonstrated the most significant influence on NH₃ and VOC levels, suggesting its critical role in determining their atmospheric residence time and transport behavior. This study demonstrates the effectiveness of UAV-based sensing for detecting pollutant gases in complex industrial settings. By enabling precise monitoring and real-time data acquisition, this approach improves environmental risk assessment and supports the creation of targeted pollution control strategies for wet waste treatment plants. Our findings confirm that UAV-mounted systems provide significant advantages over conventional methods, specifically in terms of expanded spatial coverage and enhanced operational safety. Overall, this study highlights the transformative potential of UAV technology in environmental monitoring, offering critical insights for air quality management and evidence-based policymaking in waste treatment sectors.