2.4 Waste Diversion
49
After composting the end-product will be prepared for the market through postprocessing processes such as drying, removal of recyclables, screening, blending and
bagging [19].
Composting technologies can be classified into non-reactor and reactor (in-vessel)
methods. In non-reactor technologies, the composting process takes place in an
open area or outdoors (a slow but the most common process used for centralized
composting, producing a fully degraded compost product in 3–18 months). Unlike
the non-reactor technologies, the reactor (in-vessel) methods take place indoors in
fully sealed vessels. The residence time of the organic waste reduces to between 3
and 28 days and air is forced through the composting waste for aeration and removing
off-gasses from the process. The off-gases are treated in a biofilter or scrubber [19].
2.4.2.1 Health and Environmental Impacts of Composting Systems
The potential environmental hazard of the composting systems is odor and leachate
generation. As previously described, some technologies are equipped with odors
management. Leachate can be collected and recycled to the process to increase
the moisture content or sent to a wastewater treatment plant. Generally, leachate
generation is higher in outdoor non-reactor systems compared to the reactor systems.
2.5 Conventional Approaches for Wastewater Management
Canada is blessed with an immense supply of renewable freshwater (an average of
3472 km
3 per year) [4], while it also generates a great amount of wastewater as a
result of domestic, industrial, commercial or agricultural activities that are discharged
into the drains and sewers or discharged directly to the environment. According to
Statistic Canada, wastewater discharges contribute to the greatest emission of waste
by weight into the environment. Municipal wastewater and industrial wastewater
may contain many pollutants such as debris, disease-causing pathogens, decaying
organic wastes, nutrients and hundreds of chemicals, so treatment before releasing
the wastewater into the environment is essential.
2.5.1 Treatment of Municipal Wastewater
Municipal wastewater includes sanitary sewage from homes, businesses, institutions
and industries, as well as the stormwater from rain or melting snow that drains off
rooftops, lawns, parking lots, roads and other urban surfaces. Municipal wastewater is collected with two types of wastewater collection system: a combined sewer
and a separate sewer system. Combined sewers collect both sanitary sewage and
49
After composting the end-product will be prepared for the market through postprocessing processes such as drying, removal of recyclables, screening, blending and
bagging [19].
Composting technologies can be classified into non-reactor and reactor (in-vessel)
methods. In non-reactor technologies, the composting process takes place in an
open area or outdoors (a slow but the most common process used for centralized
composting, producing a fully degraded compost product in 3–18 months). Unlike
the non-reactor technologies, the reactor (in-vessel) methods take place indoors in
fully sealed vessels. The residence time of the organic waste reduces to between 3
and 28 days and air is forced through the composting waste for aeration and removing
off-gasses from the process. The off-gases are treated in a biofilter or scrubber [19].
2.4.2.1 Health and Environmental Impacts of Composting Systems
The potential environmental hazard of the composting systems is odor and leachate
generation. As previously described, some technologies are equipped with odors
management. Leachate can be collected and recycled to the process to increase
the moisture content or sent to a wastewater treatment plant. Generally, leachate
generation is higher in outdoor non-reactor systems compared to the reactor systems.
2.5 Conventional Approaches for Wastewater Management
Canada is blessed with an immense supply of renewable freshwater (an average of
3472 km
3 per year) [4], while it also generates a great amount of wastewater as a
result of domestic, industrial, commercial or agricultural activities that are discharged
into the drains and sewers or discharged directly to the environment. According to
Statistic Canada, wastewater discharges contribute to the greatest emission of waste
by weight into the environment. Municipal wastewater and industrial wastewater
may contain many pollutants such as debris, disease-causing pathogens, decaying
organic wastes, nutrients and hundreds of chemicals, so treatment before releasing
the wastewater into the environment is essential.
2.5.1 Treatment of Municipal Wastewater
Municipal wastewater includes sanitary sewage from homes, businesses, institutions
and industries, as well as the stormwater from rain or melting snow that drains off
rooftops, lawns, parking lots, roads and other urban surfaces. Municipal wastewater is collected with two types of wastewater collection system: a combined sewer
and a separate sewer system. Combined sewers collect both sanitary sewage and