Household garbage
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Description
Household garbage is one of the most insidious pollutants that exists. If handled badly, it can cause vast pollution of air, water and soil. If handled well, it can be a valuable resource. Unfortunately, it is handled badly more often than it is handled well. Furthermore, the transport of garbage is often achieved over long distance, because many cities do not want it in their own backyard and prefer to pay large sums to send a poison gift anywhere else.
Detailed description
Composition
The composition of household garbage varies enormously. Ideally, it should consist of:
- a tightly packed polyethylene bag
- food refuse that cannot be composted
- soiled or impregnated paper unsuitable for recycling
- indeterminate plastics unsuitable for recycling
- used cleaning wipes
- ash
It should not contain any recyclable material:
- electrical and electronic waste (WEEE), including batteries
- empty food cans
- empty aluminium beverage cans
- empty aerosol cans
- empty bottles
- identifiable plastics
- paper or cardboard other than as indicated above.
In some countries, where kitchen sink disposal units are used, food refuse is sent into the sewage rather than composted or put into garbage. This is very negative for the environment because it can significantly increase the chemical oxygen demand of the sewage stream and release more methane. Such units are forbidden in many countries because of the risk of overloading sewage treatment plants. In addition, it wastes a valuable recyclable resource.
Landfill
If there is no alternative, it may be the worst solution. However, a modern, well-managed landfill, constructed according to the latest technologies would be better than a "fly dump". There can be several problems with landfills:
- they emit large quantities of greenhouse gases
- much garbage deposited in them may take hundreds of years or longer to decompose
- they become a breeding ground for vermin (rats)
- they may emit nauseabond odours
- they can use up vast areas of valuable land which may become unusable for very long periods
- they can pollute the soil below them
- they can pollute rain water infiltrating through them: this can enter surface water or ground water in turn, sometimes contaminating sources of drinking water.
All in all, if they can be avoided, they should be. If they cannot, they should be constructed according to modern standards and managed correctly.
According to a recent report on EuroNews TV (12 April 2008), Europe disposes of 300 million tonnes of household garbage each year, into landfills. This has not been substantiated, but figures for the UK [1] (23 million tonnes, population, 60.7 million), extrapolated to the population of Europe (730 million), would yield about 275 million tonnes. The article cites the area of UK's landfills at about 109 square miles (175 km²). Extrapolating this according to population would yield an area of 2100 km², 2¾ times the size of New York City or one-third as much again as London.
Transport
The transport of garbage to distant sites is common throughout the world. No one wants to live on top of a landfill. Yet the environmental and economic cost of doing this is sometimes astronomical. To illustrate this point, let us cite the case of Toronto in Ontario, Canada. This is a city of about 5 million inhabitants, including extraterritorial suburbs. Toronto shuttles about 75 trucks of garbage per day to the Carlton Farms Landfill, Wayne County, Michigan, USA, a distance of about 390 km in each direction. About 700,000 tonnes of garbage is landfilled there, each year, at a landfill cost to the taxpayers of $35 million, not counting the cost of the transport. [2] Counting the methane and carbon dioxide emitted by the landfill and the emissions from the trucks, this approaches an estimated added load of nearly 1 million tonnes of equivalent carbon dioxide into the atmosphere each year, with no added advantage. To be fair, Toronto has to stop this waste by 2010 and some nearer landfills are being opened. [3] This case is not unique. Some cities in Germany and Italy send garbage into Switzerland. We have recently seen that the City of Naples had to send garbage to the North of Italy and Sardinia.
Recycling garbage
By definition, garbage is a mixture of waste matters and is generally unpleasant to handle. Recycling, in the sense of sorting it and reusing each sort in the conventional use of the term, is simply not practical, nor economical. However, there is a practical and economically viable way and that is to convert it into energy, while ensuring that it is environmentally safe to do so. This is done in a few places in a number of countries, such as Japan, USA and Switzerland. Beijing plans to recycle part of its rubbish in the short term. [4] 10 kg of garbage houses as much energy as 2.5 kg of fuel oil and is continually and locally available. It reduces landfill volume by 90 per cent. As one example, Lausanne, Switzerland, a small city, has a state-of-the-art garbage recycling plant providing heat and electricity. [5][6]. With economy of scale, larger cities could be even more viable, as such plants can supply electricity to up to about 9 per cent of the catchment area consumption, lowering the need for fossil fuel combustion.
To take the case of Toronto, in the previous section, if the City Fathers there had had the same idea as their Lausannois counterparts, and recycled their garbage, the 700,000 tonnes sent to Michigan, would be energetically equivalent to over 200 million litres (nearly 1.5 million barrels) of fuel oil per year, equivalent to nearly two days' oil production of Qatar!
If we take the estimated 275 million tonnes/year of garbage for Europe (see above), this is equivalent in energy to over 2 years' oil production of Qatar!
An alternative method, with a somewhat lower energetic efficiency, is to gasify the garbage and to feed the gas into a conventional gas-fired generating plant. This has the advantage of being compatible with existing natural gas-fired equipment, lowering capital costs.
Food
A recent serious study [7] shows that an astounding quantity of perfectly edible food is wasted in the UK. "UK households waste 6.7 million tonnes of food every year, around one third of the 21.7 million tonnes we purchase. Most of this food waste is currently collected by local authorities (5.9 million tonnes or 88%). Some of this will be recycled but most is still going to landfill where it is liable to create methane, a powerful greenhouse gas. The remaining 800,000 tonnes is composted by people at home, fed to animals or tipped down the sink." This quantity amounts to over 100 kg per man, woman and child per year wasted. In the context of the above, if this quantity were recycled into energy, instead of being landfilled, it would mean that the UK could save having to import nearly 2 million tonnes of fossil fuel per year.
References
- ↑ UK, 'garbage can' of Europe [1]
- ↑ City of Toronto: Solid waste management [2]
- ↑ Michigan dumps Toronto garbage by 2010 [3]
- ↑ Beijing to turn garbage into power [4]
- ↑ Lausanne's garbage recycling [5]
- ↑ E&T, Vol 3, Issue 7, 26 Apr-9 May 2008, pp 22-25, "Not wasting waste", Institution of Engineering and Technology, London, UK
- ↑ The food we waste[[6]]
