Autonomous remote gas sensor network platforms with applications in landfill, wastewater treatment and ambient air quality measurement

摘要

The composition of gas emissions from any natural or manmade process can reveal significant information about that process and can have a profound effect on the surrounding environment. Measuring gas emissions can expose previously unknown interactions between the process inputs as well as allowing the user to monitor the current state of the system. It is important to be aware of such emissions as carbon dioxide (CO2) is a greenhouse gas (GHG) and can asphyxiate if allowed accumulate in a low-lying area. Methane (CH4) is an even more potent GHG with a global warming potential 25 times greater than that of CO2 (IPCC, 2007), and poses a fire risk when existing in the highly flammable range of 5-15% v/v in air. In the context of wastewater treatment plants (WWTPs), measuring the CO2 and CH4 emissions from an anaerobic lagoon can be used to monitor gas concentrations which can enable the bio-digestion processes to be optimised, thus ensuring they remain within safe levels. For example, the gas emission levels can be reduced by modifying the chemistry of the process, or by water agitation. Eventually it could drive the decision to enclosure the pond and burn the biogas, an action that can lead to carbon credits. Similarly, with landfill GHG emissions, monitoring CO2 and CH4 is very important as they must remain below the threshold levels set by the Environmental Protection Agency (EPA), i.e., 1.5% and 1.0% respectively (EA, 2004). Such thresholds warn about leakages on the lining of sites where the biogas is captured for energy generation purposes.