Urbanization and the Geoenvironment - Sustainable Practices in Geoenvironmental Engineering - page 237

• novaEQUER : an LCA tool based on the description of a district/building, the
dynamic thermal simulations by Pleiades+COMFIE and the behavior of the
occupants
• LEGEP : a calculation tool for integrated design of sustainable buildings
7.4.1.3 Recycling
Recycling, reuse of wastes, and incineration reduce the volumes of waste entering land-
ills. It is clear that Canada, whose per capita waste generated is continually increasing
(from 510 kg per capita in 1980), must increase efforts through recycling and waste to
landill reduction. Countries such as Finland and Japan have initiated aggressive waste
management plans. Application of waste limits could be implemented as a “polluter-pays”
mechanism. Although recycling and reduction of the amount of wastes, and thus the
sources of contamination, has made inroads, particularly in advanced countries, a lot more
progress is required. Although dificult to achieve, 100% recycling should be the goal for
all materials including those for construction (asphalt, concrete, wood, etc.). Collection of
paper, plastics, glass, trees, and other materials for recycling can reduce energy, material
requirements, and landill spaces. Backyard composting can substantially reduce organic
waste transport, collection, processing, and disposal, while providing a fertilizer for home
gardens.
Sewage sludge or biosolids is produced by wastewater treatment plants. The amount
of sludge depends on the amount of water treated by the city, town, or municipality. The
sludge is typically treated to remove water, and stabilization is by thickening, digestion,
conditioning, dewatering, drying, and incineration. After drying/incineration, the sludge
can be reused as a powder for manufacturing bricks, or mixed with Portland cement and
stabilized ash. Land application for agricultural uses or for land reclamation is also pos-
sible. Pathogen and heavy metal concentrations must be removed to protect groundwater
quality and public safety.
Sewage sludge has been used as an amendment to urban and agricultural gardens for
organic carbon and nutrients. The sludges generally contain about 45% organic matter,
2.0% nitrogen, 0.3% phosphorus, and 0.2% potassium (Bridges, 1991). These sludges have
been known to contain up to 3000 ppm of zinc, 2000 ppm of chromium, 1400 ppm of
copper, 385 ppm of nickel, 240 ppm of lead, 60 ppm of cadmium, and 60 ppm of arsenic.
Repeated application of this sludge leads to an accumulation of heavy metals in the soil.
More recently, the metal content of biosolids was evaluated in Canada (Table 7.6). Although
the levels are lower, they still can be problematic for Cd, Co, Cu, and Se, which are higher
than Quebec regulations for fertilizer use.
Glass is dense and takes up signiicant landill space. Increasing recycle rates is required.
However, separation of colored glasses is dificult and they must not be contaminated with
other materials such as ceramics. Crushed glass can be processed to reach the characteris-
tics of gravel or sand. It can thus replace aggregate in backill, road construction and retain-
ing walls. The use of mixed glass as glassphalt is another possibility to replace aggregate
in asphalt. More engineering tests (compaction, durability, skid resistance) will need to be
performed on the properties of glassphalt and other materials. TCLP tests would need to
be undertaken to determine the leachability of heavy metals from the glass. Lead has been
shown to leach below the USEPA levels (CWC, 1998).
Plastics are used in many everyday items such as containers, packaging, and trays.
Polystyrene, polypropylene, and polyvinyl chloride (PVC) are some of the plastic materials.