24
1 Wastes Generation, Characterization, Management Strategies …
The chemical compositions of landfill leachates from Taiwan, Hong Kong,
Kuwait, Saudi Arabia, USA, and Germany are compared in the Table. Clearly, the
leachates compositions vary significantly between regions and likely the ages of the
landfill sites. The leachate (Riyadh landfill) generated from Saudi Arabia contains
the highest concentrations of (Na 2408–4622 mgL
−1 , K 4136–7770 mgL
−1 , Ca
5300–8600 mgL
−1 and Mg 693–2612 mgL
−1 ) compared with the other landfills,
as well as the highest electric conductivity (EC 4.25–6.32 dS m
−1 ) and chemical
oxygen demand (COD 13,900–22,350 mgL
−1 ) values. It is interesting to note that
the heavy metals V (0.024–0.152 mgL
−1 ), As (1.09–1.682 mgL
−1 ) and Co (0.064–
0.094 mgL
−1 ) were detected only in the Saudi Arabia leachates, and the concentrations of Cr (0.21–0.336 mgL
−1 ) and Mn (9.25–13.16 mgL
−1 ) were higher at the
Saudi Arabia leachates than those of other landfill leachates. The relatively higher
contents of COD, heavy metals of Cr, Ni, Cu, As, Mn, Co, V and Fe in the Saudi
Arabia landfill leachates should be monitored closely to prevent contamination of
surrounding soil and surface/groundwater.
Another source of contamination from landfills is landfill gas which is formed
as the organic materials decompose in landfills. Landfill gas is primarily composed
of methane and carbon dioxide followed by small amounts of nitrogen, sulfur and
oxygen and trace amounts of a wide range of other organic compounds. Landfill
gas concerns include the potential for fires and explosions, vegetation damage and
unpleasant odors. Methane is a potential GHG and can contribute to air quality
impacts and global warming. In 2009, the emissions from landfills in Canada
accounted for 22% of the total methane emissions and 3% of the total GHG emissions. Migration of landfill gas into the soil surrounding the site can also create
environmental and health concerns [2, 46].
Residents living in the vicinity of a landfill are exposed to pollutants through
inhalation, contact with water or polluted soil, or consumption of products or contaminated water. There is also a risk of respiratory disease, cancer and birth outcomes.
Other health and environmental impacts of landfills include public acceptance to
place a local landfill site, siting challenges such as surrounding land uses, odor emissions from the landfill site, traffic impacts as a result of vehicles delivering waste to
the facility and local impacts such as dust, noise, vermin and litter [46].
Thermal treatment has the advantage of the reduction of the volume/amount of
waste for disposal. However, it creates gaseous wastes and ash that contribute to
negative health and environmental impacts. According to the Statistics Canada data
for 2009, 677 tonnes of PM, 350 tonnes of sulfur dioxides, 1364 tonnes of nitrogen
oxides, 602 tonnes of VOC, 1330 tonnes of carbon monoxide and 19 tonnes of
ammonia were released into the atmosphere from municipal incineration which was
corresponding to 0.004, 0.02, 0.06, 0.002, 0.01 and 0.004% of the total emissions of
PM, sulfur dioxides, nitrogen oxides, VOC, carbon monoxide and ammonia, respectively [2]. Dioxins and furans are bioaccumulative chemicals and considered as other
potential contaminants and that result from incomplete combustion. When the waste
containing mercury is thermally treated, mercury emission can also be another air
pollution problem [2]. Exposure to the emissions from the incinerator is associated
1 Wastes Generation, Characterization, Management Strategies …
The chemical compositions of landfill leachates from Taiwan, Hong Kong,
Kuwait, Saudi Arabia, USA, and Germany are compared in the Table. Clearly, the
leachates compositions vary significantly between regions and likely the ages of the
landfill sites. The leachate (Riyadh landfill) generated from Saudi Arabia contains
the highest concentrations of (Na 2408–4622 mgL
−1 , K 4136–7770 mgL
−1 , Ca
5300–8600 mgL
−1 and Mg 693–2612 mgL
−1 ) compared with the other landfills,
as well as the highest electric conductivity (EC 4.25–6.32 dS m
−1 ) and chemical
oxygen demand (COD 13,900–22,350 mgL
−1 ) values. It is interesting to note that
the heavy metals V (0.024–0.152 mgL
−1 ), As (1.09–1.682 mgL
−1 ) and Co (0.064–
0.094 mgL
−1 ) were detected only in the Saudi Arabia leachates, and the concentrations of Cr (0.21–0.336 mgL
−1 ) and Mn (9.25–13.16 mgL
−1 ) were higher at the
Saudi Arabia leachates than those of other landfill leachates. The relatively higher
contents of COD, heavy metals of Cr, Ni, Cu, As, Mn, Co, V and Fe in the Saudi
Arabia landfill leachates should be monitored closely to prevent contamination of
surrounding soil and surface/groundwater.
Another source of contamination from landfills is landfill gas which is formed
as the organic materials decompose in landfills. Landfill gas is primarily composed
of methane and carbon dioxide followed by small amounts of nitrogen, sulfur and
oxygen and trace amounts of a wide range of other organic compounds. Landfill
gas concerns include the potential for fires and explosions, vegetation damage and
unpleasant odors. Methane is a potential GHG and can contribute to air quality
impacts and global warming. In 2009, the emissions from landfills in Canada
accounted for 22% of the total methane emissions and 3% of the total GHG emissions. Migration of landfill gas into the soil surrounding the site can also create
environmental and health concerns [2, 46].
Residents living in the vicinity of a landfill are exposed to pollutants through
inhalation, contact with water or polluted soil, or consumption of products or contaminated water. There is also a risk of respiratory disease, cancer and birth outcomes.
Other health and environmental impacts of landfills include public acceptance to
place a local landfill site, siting challenges such as surrounding land uses, odor emissions from the landfill site, traffic impacts as a result of vehicles delivering waste to
the facility and local impacts such as dust, noise, vermin and litter [46].
Thermal treatment has the advantage of the reduction of the volume/amount of
waste for disposal. However, it creates gaseous wastes and ash that contribute to
negative health and environmental impacts. According to the Statistics Canada data
for 2009, 677 tonnes of PM, 350 tonnes of sulfur dioxides, 1364 tonnes of nitrogen
oxides, 602 tonnes of VOC, 1330 tonnes of carbon monoxide and 19 tonnes of
ammonia were released into the atmosphere from municipal incineration which was
corresponding to 0.004, 0.02, 0.06, 0.002, 0.01 and 0.004% of the total emissions of
PM, sulfur dioxides, nitrogen oxides, VOC, carbon monoxide and ammonia, respectively [2]. Dioxins and furans are bioaccumulative chemicals and considered as other
potential contaminants and that result from incomplete combustion. When the waste
containing mercury is thermally treated, mercury emission can also be another air
pollution problem [2]. Exposure to the emissions from the incinerator is associated