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Z. Liang et al.
were identified. This helps to understand and compare the environmental impacts of
different treatment processes and provides suggestions for the sustainable development of wastewater treatment processes. (3) The GHG emission characteristics of
nine scenarios of different sewage-sludge treatment processes were analyzed, and
the environmental impacts caused by energy consumption and chemicals consumption were studied. Consequently, the sewage-sludge treatment process under low
carbonization and low environment impact were proposed.
Keywords Greenhouse gas (GHG) emission · Mass balance · Sewage-sludge
treatment system
18.1 Introduction
Climate change has become one of the most serious challenges of the twenty-first
century. Until the end of 2010, the “Greenhouse Gas Bulletin” published by the World
Meteorological Organization (WMO) indicated that the concentration of several
major GHGs, such as methane (CH 4 ), nitrous oxide (N 2 O), and carbon dioxide (CO 2 )
in the global atmosphere reached their highest level, increasing by 38%, 158%, and
19%, respectively, compared with the concentrations during pre-industrial revolution (1750 years ago) (Liu 2010). With an increase in GHG emissions, the global
average temperature is predicted to increase by 5 °C in the next 100 years (World
Bank, 2010). It is estimated that because of China’s economic development, the
atmospheric CO 2 concentration will continue to increase, leading to an increase in
the average surface temperature of China by 2.2–4.2 °C in 2100 (Chen 2009). Due
to rising global temperatures, governments have begun to take measures to reduce
GHG emissions to meet climate change targets. In the past 100 years, the Municipal
Wastewater Treatment Plants (WWTPs) have developed rapidly in order to solve
environmental and health problems due to urban sewage. The traditional sewage
treatment process consumes a lot of energy and medicines as well as produces GHG
emissions, including CH 4 , N 2 O, and CO 2 . In developed countries, energy consumptions, CO 2 emissions, N 2 O emissions, and CH 4 emissions from WWTPs account for
3% (Mo and Zhang 2012), 4% (Martin et al. 2008), 3% (Kampschreur et al. 2009),
and 5% (El Fadel et al. 2001) of total consumptions/emissions, respectively.
Meanwhile, the evaluation method of urban sewage treatment process is primarily
based on technical and economic analysis to ensure the output quality of WWTPs.
This evaluation method is mainly aimed at achieving water quality standards,
considering the cost and benefit of different sewage treatment processes from an
economic perspective, and analyzing the economic rationality of the treatment
process. However, in the face of development challenges of pollutant reduction,
energy conservation, and emission reduction, this emphasis on the evaluation of
processing technology performance will highlight its shortcomings; thus, a systematic environmental impact analysis should be established. With the development of
urbanization in China, energy consumption and GHG emissions of sewage-sludge
Z. Liang et al.
were identified. This helps to understand and compare the environmental impacts of
different treatment processes and provides suggestions for the sustainable development of wastewater treatment processes. (3) The GHG emission characteristics of
nine scenarios of different sewage-sludge treatment processes were analyzed, and
the environmental impacts caused by energy consumption and chemicals consumption were studied. Consequently, the sewage-sludge treatment process under low
carbonization and low environment impact were proposed.
Keywords Greenhouse gas (GHG) emission · Mass balance · Sewage-sludge
treatment system
18.1 Introduction
Climate change has become one of the most serious challenges of the twenty-first
century. Until the end of 2010, the “Greenhouse Gas Bulletin” published by the World
Meteorological Organization (WMO) indicated that the concentration of several
major GHGs, such as methane (CH 4 ), nitrous oxide (N 2 O), and carbon dioxide (CO 2 )
in the global atmosphere reached their highest level, increasing by 38%, 158%, and
19%, respectively, compared with the concentrations during pre-industrial revolution (1750 years ago) (Liu 2010). With an increase in GHG emissions, the global
average temperature is predicted to increase by 5 °C in the next 100 years (World
Bank, 2010). It is estimated that because of China’s economic development, the
atmospheric CO 2 concentration will continue to increase, leading to an increase in
the average surface temperature of China by 2.2–4.2 °C in 2100 (Chen 2009). Due
to rising global temperatures, governments have begun to take measures to reduce
GHG emissions to meet climate change targets. In the past 100 years, the Municipal
Wastewater Treatment Plants (WWTPs) have developed rapidly in order to solve
environmental and health problems due to urban sewage. The traditional sewage
treatment process consumes a lot of energy and medicines as well as produces GHG
emissions, including CH 4 , N 2 O, and CO 2 . In developed countries, energy consumptions, CO 2 emissions, N 2 O emissions, and CH 4 emissions from WWTPs account for
3% (Mo and Zhang 2012), 4% (Martin et al. 2008), 3% (Kampschreur et al. 2009),
and 5% (El Fadel et al. 2001) of total consumptions/emissions, respectively.
Meanwhile, the evaluation method of urban sewage treatment process is primarily
based on technical and economic analysis to ensure the output quality of WWTPs.
This evaluation method is mainly aimed at achieving water quality standards,
considering the cost and benefit of different sewage treatment processes from an
economic perspective, and analyzing the economic rationality of the treatment
process. However, in the face of development challenges of pollutant reduction,
energy conservation, and emission reduction, this emphasis on the evaluation of
processing technology performance will highlight its shortcomings; thus, a systematic environmental impact analysis should be established. With the development of
urbanization in China, energy consumption and GHG emissions of sewage-sludge