Life Cycle Assessment of Municipal Solid
Waste Management in Chinese urban areas: case study inChongqing City
1

Wenyu Huang1,*, Helmut Yabar1, Takeshi Mizunoya1，Yoshiro Higano1
University of Tsukuba, Graduate School of Life and Environmental Sciences, Japan; 1-1-1 Tennodai, Tsukuba, Ibaraki,
Japan 305-8572*
hwy_4@hotmail.com

Abstract
Chongqing city, a major city in Southwest China, has experienced a rapid increase in municipal waste generation.
Currently only 38.3% of the waste is treated through incineration and bio-treatment and from the remainder 54.7% is directlysent to the landfill site and 7% is sent to open dumping. Since the landfill site, located near the ChangJiang River, is reachingits full capacity it is urgent to introduce alternative waste management options to minimize the amount of final disposal waste.
In order to address this problem, this paper proposes different viable alternative options based on the integrated waste
management approach and evaluates their environmental and economic performance by means of Life cycle assessment(LCA). The scenarios include different collection options, pre-treatment and treatment technologies that focus on material
recycling, organic and energy recovery as well as final disposal. The Life Cycle Inventory analysis was carried out with theaid of IWM-2 Model. Based on these analysis results, a sustainable waste management strategy that has environmental,
economic and social advantage is proposed and recommended.
Keywords: Municipal Solid Waste Management, Life Cycle Assessment, Life Cycle Cost, Integrated Approach, Recycling

1. Introduction
Chongqing is located near the ChangJiang River inSouthwest of China. The main urban areas of Chongqing
city, with a population of approximately 7 million in 2001,
generate 1.08kg/capita/day waste [1]. Landfills are the main
method of disposal in Chongqing, but pollution caused bysimple landfills and lack of backup municipal solid waste(MSW) disposal capacity are becoming major problems in
the urban areas of Chongqing. This paper discusses thecurrent MSW system and treatment options in Chongqing
city, and suggests integrated and environmental friendly
solutions, through different viable alternative options
generated by life cycle assessment (LCA).
2. Current treatment processes in Chongqing
2.1 Generation
The amount of MSW generated in the main districts ofChongqing has increased sharply with the growth of theeconomy and urban population (Fig.1). In 2011,
approximately 2.75 million tons waste was generated. [2and 3]
Waste generation （million tos）

Fig.2: Urban solid waste composition in Chongqing
2.2 Collection& Separation
2.2.1 Waste Collection
In Chongqing，waste is collected in curbside way.
Residents send their mixed household waste to thecollection site without separation. Most of the waste will becollected and transported to the transfer station by the
Chongqing Municipal Administration Commission [5].
Commercial waste will be directly sent to the transfer
station.

3
2.5
2
1.5
1
0.5

2011

2010

2009

2008

2007

2006

2005

2004

2003

0

Fig.1: Waste generation of Chongqing urban areas
As shown in Fig. 2, in 2011 waste was classified as
59.2% organic, 10.10% paper, 15.7% plastics, 3.40% glass,
1.10% metal, 4.20% garden wastes, 6.1% textiles and 0.2%
others [4].

2.2.2 Waste Separation
After that, waste is moved to a transfer point for pretreatment and brief separation, and then delivered totreatment facilities. Until 2010, Chongqing has only one
secondary transfer station with a capacity of 1300t/day. [6]Other than that, residents may sold recyclable materials(include plastics, paper and metal)to some privatecompanies for money.

2.3 Treatment Facilities
At present, there are several treatment options in theworld, including incineration, composting, gasification,
recycling, pyrolysis, combined pyrolysis-gasification,
anaerobic digestion and landfill.[7]2.3.1 Incineration & Composting & Landfill
By 2011, there were five large treatment centers,
including two landfill centers with an annual treatment
capacity of 2500 tons a year, two incineration centers withan annual treatment capacity of 1500 tons a year, and one
Bio-treatment center with an annual treatment capacity of
500 tons a year (Table 1). [8]Table 1 Waste treatment facilities Chongqing
year
Capacity(t) location
Tongxing
Incineration
Fengsheng
Incineration
Heishizi kitchen
waste Treatment
Heishizi Landfill
Changshengqiao
Landfill

2005

1200

Bei'bei2012

2400(300)

Ba'nan

2010

500

Yubei

2006
2003

1000
1500

Jiang'bei
Nan'an2.3.2 Recycling
Recyclable materials include many kinds of glass,paper, metal, plastic, and textiles. As the special collection
system—curbside without sorting—in China, Waste always
recycled by the private company. Residents usually sellpaper, plastic, metal, and cans. The recycle rate is very low
in Chongqing.
2.4 Final disposal
Currently, 2759400 tons of waste is generated, Of this,27.96% (771615 tons) unfortunately goes straight tounsanitary landfills; the rest is transported to transfer
stations for pre-treatment and brief separation. Next,
231000 tons of waste (8.37%) are moved to a food waste
facility for composting, and 18480 tons of residue are taken
to landfill sites after treatment. Only 68985 tons (2.5%) of
recyclable waste are recycled by social communities, ofwhich 20695 tons residues are moved to landfill.
Combustible waste of 561500 tons (20.35%) is delivered to
an incineration facility, of which 101070 tons (18%) bottom
ash will go to landfill.
3. Modeling by LCA
3.1 LCALife Cycle Assessment (LCA) is an environmental
management tool increasingly used to understand andcompare how a product or service is provided ‘fromcradle to grave. The emissions from the system studied areclassified and characterized using methodology from LCA
into the following environmental impact categories: Global
warming potential (GWP), Acidification potential (AP),
Eutrophication potential (EP), Formation of photochemical
oxidants (excluding NOx), NOx-emissions, Heavy metals(input/output analysis). [9]The environmental results are also aggregated using
monetary weightings for emissions. The aim ofstandardization is to eliminate the difference between thedimension and the series, but not to affect the nature of theoriginal results [10]. The monetary weightings are based on
willingness-to-pay estimates. [11]3.2 Goal & Scope

The goal of LCA is to compare the full range ofenvironmental effects assignable to products and services inorder to improve processes, support policy, and provide asound basis for informed decisions. [12] In this paper weassumed that the MSW generated, and all stages throughout
waste collection, transfer, treatment, and final disposal in
Chongqing in 2011 as the LCA scope . The goal of the
LCA study is to analyze and compare the environmental
impact of every scenario.
3.3 Scenarios
This chapter describes results and analysis from
Integrated Waste Management (IWM-II), including waste
flow, final disposal amount, gas emission, human toxicity,
and waste emission [13]. Due to the current situation (2011as current situation in this research), we assumed thatgovernment plan as Scenario I. Based upon this, four
separate scenarios, including the current situation focus on
sorting, incineration, Bio-treatment, and recycling, were
proposed. I also assumed that if with sorting, the dumping
will be zero.
3.3.1 Scenario I
The Five Action Plan for Environmental Protection
covers all environmental fields. Currently, the Eleven Five
Action Plan was carried out for the next (2010–2015) . The
Government wants to construct another incineration plantand Bio-treatment plant to reduce the landfill amount. [14]The boundary of waste treatment flow is showed in Fig.3.

Fig.3: Boundary of waste treatment flow
3.3.2 Scenario II
In Scenario II (Fig. 4), I assumed no unsanitary landfill,
so all the waste generated will be moved to a transfer
station. the amount of waste for Bio-treatment andrecycling is assumed to be the same as Scenario I. As the
proportion of plastic (15.6%) and paper (10.10%), 551880
tons RDF (20%) are assumed. In this scenario, the amountof waste moved directly to landfill is obviously smaller thanin Scenario I .
3.3.3 Scenario III
Scenario III (Fig. 5) focuses on Bi0bio-treatment.
Because the food waste now collected in the urban areas is
about 26.5% of the total waste.. so I assumed all of theorganic waste will go to Bio-treatment with the technology
of gasification.

CO2 to the atmosphere. MSW contains approximately thesame mass fraction of carbon as CO2 itself, so incinerationof 1 ton of MSW produces approximately 1 ton of CO2[16]. So，CO2 is the main factor of global warming inthese Scenarios. However, Scenario I has high level of
unsanitary landfill, its CO2 landfill emission are the highest.
As Scenarios II focusing on RDF burning, it discharged alarge amount of CO2 (Fig.7). landfill contributes most to
the GWP of the studied scenarios. Recycling of materials
and nutrients shows slightly lower impact than incineration.
Fig. 4: Boundary of waste treatment flow

Fig. 7:

Fig. 5: Boundary of waste treatment flow
3.3.4 Scenario IV
Scenario IV (Fig. 6) focuses on recycling and tries tomaintain the others proportions as in Scenario I. Paper,
plastic, glass, metal, and textiles are assumed to be recycled.
551880 tons of recyclable wastes are moved to recycling
facilities.

CO2 emission

Fig. 8: CO emission

Fig. 9: CH4 emission
4.3.2 Eutrophication
Acidification potentials are mainly affected by SOx
and NOx emissions (Figs. 10 and 11) [17]. Althoughemissions of other gases，such as HCL, HF,H2S, and NH3
will also cause acid rain also, the amounts are very small.
The
proportionsofequivalent
factorsare
1:0.7:0.88:0.6:1.88:1.88, respectiv separately.
The acidification potential in this research does notvary greatly between each scenario, but Scenario II does
not score well at acidification impact.

Fig. 6: Boundary of waste treatment flow
4. Results & Analysis
4.2 Amount & Final Disposal
This Paper describes results and analysis from IWM-II
including waste flow, final disposal amount, gas emission,
human toxicity, and waster emission. The Waste flow ofeach scenario formed the basic data for analysis; theresearch parameters of every scenario could be carried out
in this part, based on the waste flow.

4.3 Gas Emission
4.3.1 Global Warming Potential
In the thermal ,Scenarios I, III, and IV, CO2 emissions
are nearly the same. The long-term effect on climate of
reducing methane emissions is relatively small [15] and theconcentration of the CO and CH4 is very low. Neverthelessnearly all of the carbon content in the waste is emitted as

Fig 10: NOX emission

Fig. 11: SOX emission

Fig. 12: BOD emission
4.3.3 Human toxicity
For metals, flows of lead, cadmium, mercury, copper,
chrome, nickel and zinc were nearly the same. There are no
big differences between the scenarios. The big sink formetals is in recycled materials (mostly metal containers) orin landfill after the surveyable time period. In all scenarios,
almost the same amount of metals end up in the landfill, butemissions in Scenario IV were higher. Because recycling
phase we should use some chemical ways to recycle

materials, compared to other scenarios, Scenario IV
produce more toxicity.
4.4 Integrated EvaluateThis research discusses the final results ofenvironmental impact including GWP, acidification
potential, eutrophication for every scenario proposed in thisresearch. From these analysis we can immediately see that
Scenario III was the best performer. Because of its GWP,
Scenario IV was in second place, just behind Scenario III.
Scenario II, which focuses on thermal treatment, accounts
for 3. And Scenario I, the current situation, had the highest
environmental impact because of unsanitary landfill.
5. Conclusion
The overall conclusion from the study is for the popurse of avoiding the large amount of the landfill, several
waste treatments are possible and have less adverse
environmental impact, using of energy resources andeconomy. A combination of anaerobic digestion, materials
recycling and incineration would probably be the bestsolution to avoid landfilling as much as possible. if
considering of the costs and environmental impact, theintegrated waste management will be a wise choice.
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