Question

1. A municipal solid waste to be combusted has the following composition:

Component	Fraction by Weight
Food	45
Paper	30
Textiles	10
Wood	15

1. Assuming the weights are on a dry basis, estimate the heat value of the waste.
2. Assuming the weights are on a wet basis, estimate the heat value of the waste.

Answer 1

Ans) Given,

a) Using Khan's formula ,heat value of waste (MJ/kg) can be given by,

E = 0.051(F + 3.6 CP) + 0.352 (PLR)

where, F = fraction of food waste

CP = fraction of cardboard, wood and paper

PLR = fraction of plastic and rubber

E = 0.051(45 + 3.6(30+15) ) + 0.352(0)

E = 10.55 MJ/kg

b) To determine heat value on wet basis assume moisture content in each waste as:

Waste	Fraction by weight	Moisture content (%)	Dry weight
Food	45	70	13.5
Paper	30	6	28.2
Textile	10	10	9
Wood	15	20	12

Now using, Khan formula,

E = 0.051(13.5 + 3.6(28.2+12) ) + 0.352(0)

E = 8.07 MJ/kg