23. Organic waste may be disposed of by landfill or incineration. Both processes produce gases.
(a) The main gases produced from a typical landfill are shown in the table.
(i) Name the process that forms these gases in landfill.
(1)
ANSWER
Decomposition
(ii) State the main environmental problem caused by landfill gases, identifying the gas or gases responsible.
(2)
ANSWER
Global Warming due to methane and Carbon dioxide emission.
(iii) One tonne of landfill waste produces approximately 12.5dm3 of landfill gases per day.
Calculate the mass of carbon dioxide produced in a year by a typical landfill site which contains 90000 tonnes of waste.
Assume that the gas volume is measured at room temperature and pressure (r.t.p.). [Molar volume of gas at r.t.p. = 24.0dm3 mol−1]
(3)
ANSWER
1 tonne produces 12.5 dm3 gases per day, therefore,
(b) Suggest two advantages of incineration over landfill.
(2)
ANSWER
i. less land is needed
ii. Can be used to generate electricity
(c) Environmental groups prefer recycling to both landfill and incineration. Suggest one advantage of recycling.
(1)
ANSWER
Saves Energy / conserves resources.
