CE 527 Solid Waste Management – Fall 2003
Problem Set No. 2
Date due = Oct. 14
1. Solve Problem 8-12
2. Solve Problem 11-1 (b)
3. Solve Problem 11 –2
4. A landfill is being planed to occupy a rectangular space of 300 m x 450 m with an average
finished refuse depth of 20 m. It is estimated that the average deposition rate will be 120,000
metric tons/year and a density of 320 kg/m3 will be achieved throughout the site. Landfill gas
will be extracted from the landfill for energy recovery as a low-grade fuel. Gas will be
extracted through vertical extraction wells as soon as a cell is completed.
(i) Make a preliminary estimate of the amount of gas and energy that will be produced over
the life of the landfill. Provide yearly production values and cumulative values.
(ii) Estimate the number of extraction wells required
(See Example 11-2 and Example 11-8 to solve problem) and 1 ft3 CH4 (100%) = 1,000 BTU
Assume that the waste consists of 40 % rapidly decomposable waste and 60% slowly
decomposable waste. Composition of the two wastes is presented in the Table below.
Assume the yearly rate of decomposition for rapidly and slowly decomposable waste is based
on a triangular gas production model in which the peak rate of gas production occurs at the
end of the first year and the fifth year. Time periods for total decomposition of rapidly and
slowly decomposable waste are 5 and 15 years, respectively. Please state clearly any other
assumptions.
C
Rapidly decomposable
Slowly decomposable
43
50
H
O
N
(% by weight)
7
42
1
6
33
3
Ash
7
8