The government-accredited GA 2000 landfill gas analyzer was used to monitor the landfill gas (methane (CH4) and carbon dioxide (CO2)) generated from the subsurface of a landfill.
Methodology Eighteen gas sample probes were constructed and placed approximately 100 m apart on the boundaries of the landfill site. The monitoring of the gases was conducted over a period of two years, taking into consideration the different seasons of the year.
Results from the study show that as the LFG migrates toward the boundaries of the landfill in the subsurface, higher CO2 levels are recorded when compared to CH4. This could be a result of the oxidation process and some other factors present in the landfill. CH4 emissions ranged from 0.54 to 2.22% v/v in 2020. For the year 2021, the CH4 concentration ranged from 0.24% v/v to 2.33% v/v. In addition, the CO2 concentration for the year 2020 ranged from 4.66 to 6.37% v/v. In the year 2021, the CO2 concentration ranged from 3.5 to 6.56% v/v. Furthermore, higher gaseous concentrations were found in the surrounding active cells, where there is currently deposition of municipal solid waste (MSW). However, the monitoring probes situated in areas far away from the landfill recorded lower gaseous levels.
This study recommends that there should be continuous monitoring of the LFG emission from the Thohoyandou landfill due to the different results obtained over the temporal variation. Frequent monitoring will help prevent the potential risk of fire hazards and pollution in the future.