In the 20th century, the industrial nations were devoted to satisfying our ever-growing consumer needs. To do so, they extracted and processed extensive natural resources. Today, we know that these resources are limited and that extractive and manufacturing activities are responsible for our major pollution problems: water pollution, global warming due to greenhouse gases, soil contamination and erosion, ecosystem degradation and loss of biodiversity. Part of the solution to these problems is sound residual materials management. Recovering useful materials and recycling them back into the production stream generally has the same effect as source reduction, namely, reducing the need for virgin materials along with pollution generated by their processing.
Putrescible materials are the main source of contamination in disposal sites. In landfills, their decomposition in the absence of oxygen produces malodorous, explosive gases that contribute to the greenhouse effect. The organic compounds released by the decomposition migrate with leachates and can contaminate surface and groundwaters, making them unfit for human consumption and even harmful to aquatic life.
Removing putrescible materials from the waste stream therefore reduces the pollutant load in disposal sites and can be a valuable source of compost, which helps improve soil quality while cutting back on the need for fertilizers and pesticides.
Minimizing the amount of waste entering landfills reduces the rate at which they are are filled, thereby extending their life span and restricting the need for replacement sites.
It was to meet these challenges that, in 1989, the QuÃÂÃÂ©bec government adopted an integrated solid waste management policy, which targeted a 50 percent reduction in the quantity of waste sent for disposal by the year 2000. In 1989, 5.7 million tonnes of residual materials, of the 7 million tonnes generated, went for disposal, leaving a recovered volume of just under 1.3 million tonnes. Ten years later,