Here is an interesting feature from the Toronto Star – landfill mining is alive & well (and living in Tennessee)
About 20 miles south of Nashville, Tenn. amid the rolling hills and pastures of Williamson County, you´ll find a large rectangular mound resembling a truncated pyramid. The mound measures about 3 hectares acres wide and 10 metres tall. Its sides are grassy and blend with the scenery. On top is a large clay cover, out of which metal pipes, connected to various pumps and machines, stand straight as soldiers. What´s inside the mound is about to be mined, but it´s not precious metals, it´s garbage. This mound is a landfill site-the final resting place of much of what we throw away. A mucky, moist assortment of used Q-Tips, chairs, carpets, car engines, washing machines, typewriters, eggshells and fruit peelings – you name it.
But the messy mélange of detritus hidden underneath the grassy blanket is going to be turned into new and sellable products: compost, metals for cars and trucks, ferry bumpers, marine docks and seawalls. In effect, the landfill will be recycled. An outrageous idea to most people, but not to John Baxter of London, Ont. Baxter is president of Environmental Plastic Solutions Inc., a Canadian company that holds the patents to a technology that can reduce, reuse and recycle up to 85 per cent of the material in the municipal solid waste site.
The technology has been used, mostly on a pilot basis in Canada, The United States, Europe and Japan, as well as in a recent full-scale commercial operation in South Carolina. “It´s not a panacea,” he says, “but it is the most economically and socially cost effective way to get more out of a traditional landfill that what´s presently being used.”
Dumping and dumps, as we now know them, are costly and controversial. Each day, 185 truckloads of garbage, mostly from Toronto, travel down our provincial highways to a Michigan dump because our own sites are jam-packed. Apart from congesting the highways, burning fuel and costing municipal taxpayers millions of dollars, our dumping on Michigan has many Michiganites trashing Toronto.
With landfill recycling, the same dumpsite can be used four or five times, meaning, “you don´t have to keep finding new places to store the trash,” says Baxter. Not that he advocates this as a replacement to traditional recycling; instead, it´s a means to transform the plentiful landfills already in existence from environmental and social liabilities into sustainable community assets.
Baxter´s landfill recycling technology works in three phases. First he installs an aerobic bioreactor, somewhat akin to a giant composter. The bioreactor consists of a series of vertical wells drilled into the top of the landfill´s six-foot clay cover in a grid-like formation, connected to one another and to a series of tanks. The tanks contain bacterial elements collected from the landfill´s own leachate (liquid seeping from garbage), as well as oxygen and water which, when injected into the landfill at a gradually increasing temperature to about 55 degrees Celsius, fully decompose the organic matter within 18 to 24 months.
In conventional, anaerobic landfills, where oxygen and moisture are absent, organic matter can take up to 100 years to decompose. Here´s where you may find fruit and vegetable remains flawlessly preserved, long after the people who consumed them have died, notes Baxter, recalling a site he studied in Atlanta. “After 60 years, the bananas were still yellow and the lettuce was still green.”
Anaerobic landfills have been the norm for decades. “The understanding was if we kept the stuff dry, we could treat the landfill like a big storage facility,” explains John Jackson, coordinator of the Citizens´ Network on Waste Management, who also teaches waste management at Trent University.
|Ano da Publicação:||2003|
|Fonte:||Toronto Star Journal|
|Email do Autor:||email@example.com|