| Author | Pokhrel, Dinesh |
| Call Number | AIT Thesis no. EV-98-18 |
| Subject(s) | Methane
|
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of
Engineering, School of Environment, Resource and Development |
| Publisher | Asian Institute of Technology |
| Abstract | Laboratory scale experiments were conducted with soil column to study the methane
oxidizing capacity of methanotrophs. The study was confined to determine the oxidation
potential in two soil columns and batch experiments. Methane concentration was monitored at
headspace and oxidation capacity was calculated using mass balance. Methane oxidation
rates were determined after establishment of steady state condition. Effect of moisture content
and temperature was monitored and found to have significant effects on methane oxidation
potential. Low moisture content inhibited oxidation rate and oxidation rate was controlled by
temperature significantly. Experiment on column system produced an oxidation rate of 100 g
CH4 per m
2
per day. Increases in gas supply rate could not produce comparable increase in
oxidation rates although some increase in oxidation rate was observed. Significant oxidation
was noticed at a wide range of temperature although optimum was found to be between 30 to
37° C. Oxidation rate was slowed down at lower temperature more rapidly. Moisture content
between 14 - 20% was favorable for oxidation with oxidation rate dropped to almost zero at
moisture content below 5%. Higher moisture content (more than 18%) in column system
could not produce higher oxidation that could be due to low diffusion transport of gases.
Oxidation rate was found maximum at a depth 15 to 45 cm from top with depth profile of
both oxygen and methane overlapped at this depth. High temperature, although favorable for
oxidation, also caused decrease in moisture content of topsoil, reducing oxidation rates. Fresh
soil produced less oxidation than soil removed from column with high methane atmosphere
when incubated under favorable environmental condition of temperature and moisture
content. Maximum oxidation capacity of 276* 10-6 g CH4 per g soil per day (11.5* 10-6
g
CH4
/g soil.h) was observed with soil rich in methanotrophic bacteria. Soil likely to exposed to
elevated methane concentration like landfill cover soil could be designed and proper moisture
condition can be maintained considering the effect of temperature of the region in order to
reduce atmospheric methane concentration. Well-planned, constructed and managed landfill
cover soil can have mitigation effects on reducing methane emission from landfill and helps to
reduce potential of greenhouse effect. |
| Year | 1998 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Environmental Engineering (EV) |
| Chairperson(s) | Visvanathan, C.; |
| Examination Committee(s) | Wu, Jy S ;N. T. Kim Oanh; |
| Scholarship Donor(s) | World Health Organization ; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1998 |