Recycling Solid Wastes

There was a time when nothing of value was thrown away. It was re-used, repaired or traded. Unfortunately that changed and the mounds of useful material tossed into landfills grows.

Environmental engineers are involved with researching, planning and designing ways of reducing the amount of solid waste produced by industry and society and ways of increasing the amount that is reused.

Large amounts of waste materials from industry are used in the production of concrete. Fly ash and silica fume are combined with cement to make concrete. Fly ash is the waste material found in the smoke of coal-burning power plants. Silica fume is found in the fumes formed during the refining of silicon, which is used in the production of computer chips.

Fridges and freezers are decontaminated (the CFC refrigerants are removed and disposed of) and recycled for scrap metal. Other large appliances are also recycled for scrap.

Household metal dropped off for recycling at a landfill.

With efficient recycling and composting programs well over half of solid waste produced in a city can be diverted from landfill. Recycling helps reduce our consumption of natural resources like fossil fuels, trees and metals.

• Producing aluminum from scrap metal instead of bauxite cuts energy use and air pollution by 95%.
• Making paper from discards instead of cutting down more trees reduces energy consumption by 75% and requires less than half as much water.
• Household metal and automobiles are being used to make rebar for reinforced concrete construction.
• Newspapers and low-grade paper is being used to produce cellulose insulation.
• Cardboard and low-grade paper is being used to make tar paper and shingles.
• Asphalt from roadways is recycled and used instead of gravel on driveways
• Plastic is used to make carpets and clothing
• Old tires are used to make car parts and rubber sheeting

Around 90% of the material collected at Edmonton's Materials Recovery Facility is sold. Research is underway for potential uses for the remaining 10%.

Nova Scotia - Canadian Champion of Waste Reduction

They have banned tires, plastics, tin cans, paper, batteries, paint, antifreeze and compostable organic garbage from their landfills. Thereby not just encouraging but insisting on recycling. Halifax has a system where the garbage is dumped onto conveyer belts, the materials which can be recycled and any contaminants are removed either by machines or workers and the remaining material is composted and decomposed. Eventually the compost is sold to farmers, gardeners and industry.