What happens to our household rubbish?

Above - Landfill, a common practice for rubbish management all over the world.

While landfill gas can seriously contribute to air pollution, it can be turned into a reliable and renewable fuel to benefit mankind. This gas is emitted from decomposing rubbish in a landfill site. A landfill is an area designated to receive solid wastes, such as municipal solid waste (household trash), construction debris, and sludges from sewage treatment and other processes.

As the world becomes increasingly sophisticated and technologically advanced, we are continually adding to our landfill sites and in America, it estimated that every person generates about 2 kilograms of waste per day, or almost 1 tonne per year. Australians are also some of the world’s highest producers of household waste. It is believed that every Australian household generates an average 15 tonnes of greenhouse gases per year through everyday activities such as transport, household energy use and household waste decaying in landfills.

These landfill sites contain anaerobic bacteria that thrive in this oxygen-free environment. The anaerobic bacteria work to decompose the landfill waste, which contains a significant amount of organic compounds. During this decomposition process, landfill gas is being produced.

Landfill gas consists of about 50 per cent methane (CH₄), a very potent greenhouse gas that is a key contributor to global climate change (and methane is more than 21 times stronger than carbon dioxide). However, methane is the primary component of natural gas, a valuable fossil fuel. About 80 per cent to 99 per cent of natural gas is made up of methane.

Landfill gas also consists of about 50 per cent carbon dioxide (CO₂), a much less potent greenhouse gas. There is also a small amount of non-methane organic compounds in landfill gas and they can contribute to the formation of smog. Some of these compounds pose health hazards due to their toxicity. The carbon dioxide is likely to leach out of the landfill because it is soluble in water. But methane is less soluble than water and it is lighter than air. Methane is likely to migrate out of the landfill into the atmosphere.

^ back to top ^