Carbon footprint assessment for the waste management sector: A comparative analysis of China and Japan

Abstract

Waste management is becoming a crucial issue in modern society owing to rapid urbanization and the increasing generation of municipal solid waste (MSW). This paper evaluates the carbon footprint of the waste management sector to identify direct and indirect carbon emissions, waste recycling carbon emission using a hybrid life cycle assessment and input-output analysis. China and Japan was selected as case study areas to highlight the effects of different industries on waste management. The results show that the life cycle carbon footprints for waste treatment are 59.01 million tons in China and 7.01 million tons in Japan. The gap between these footprints is caused by the different waste management systems and treatment processes used in the two countries. For indirect carbon footprints, China’s material carbon footprint and depreciation carbon footprint are much higher than those of Japan, whereas the purchased electricity and heat carbon footprint in China is half that of Japan. China and Japan have similar direct energy consumption carbon footprints. However, CO₂ emissions from MSW treatment processes in China (46.46 million tons) is significantly higher than that in Japan (2.72 million tons). The corresponding effects of waste recycling on CO₂ emission reductions are considerable, up to 181.37 million tons for China and 96.76 million tons for Japan. Besides, measures were further proposed for optimizing waste management systems in the two countries. In addition, it is argued that the advanced experience that developed countries have in waste management issues can provide scientific support for waste treatment in developing countries such as China.

Keywords

waste management / waste recycling / carbon footprint / hybrid LCA

Introduction

To mitigate the harm resulted from climate change, it is crucial to control the increase in global temperatures to within at most 2°C, and preferably 1.5°C of pre-industrial levels [¹,²]. The Paris Agreement, aimed at achieving this goal, mandated a carbon cap of 450 parts per million (ppm) CO₂ equivalent (CO₂e) in the atmosphere. Under the intense pressure of demands to reduce greenhouse gas emissions and meet the carbon cap, it has become increasingly important to increase material recycling and improve the energy conversion rates. Better waste management could indirectly reduce carbon dioxide (CO₂) emissions by recovering materials and generating energy that would otherwise be produced using fossil fuels [³,⁴]. Moreover, rapid urbanization and continued economic grow in developing countries have led to a rapid increase in the amount of municipal solid waste (MSW) being generated. For these reasons, waste management has attracted increasing attention in recent years.

Several studies were conducted focusing on waste recycling [⁵,⁶], waste management system design [⁷–⁹], technology assessment [¹⁰,¹¹], and the potential for reduced CO₂ emissions in waste management [³,¹²]. For example, Zhuang et al. [¹³] evaluated the feasibility of a waste separation system that separated household waste into food waste, dry waste, and harmful waste. Cheng et al. [¹⁴] reported on a waste-to-energy incineration technology that co-fired MSW with coal. Wen et al. [¹⁵] compared the waste classification schemes of China, the European Union, Japan, and the United States. Most studies directly focused on the waste management sector, and only a few researchers identified indirect carbon emissions from upstream industries [¹⁶,¹⁷]. In addition, carbon emission reduction from waste recycling was rarely considered in the carbon footprint analysis of the waste management sector. Furthermore, to develop appropriate emission reduction policies, high-efficiency methods for handling MSW and the potential to reduce CO₂ emissions during waste treatment warrant further investigation.

The energy-saving and emission reduction experiences of developed countries are crucial for strengthening the financial and technological support for climate change mitigation in developing countries [¹⁸]. In practice, a study comparing developed and developing countries can highlight the impacts of various waste management systems and policies in different countries. Such studies have provided information useful for planning, changing, or implementing waste management systems in developing countries [¹⁹,²⁰].

Given these facts, a hybrid life cycle assessment (LCA) and input-output (IO) analysis were proposed in this paper to quantitatively analyze the carbon footprint of the waste management sector. Both direct CO₂ emissions from various waste treatment processes and indirect emissions from upstream activities, such as the use of energy or materials were evaluated. This approach also allowed further quantification of carbon emissions conservation from waste recycling. China generates the largest amount of waste in the world, and Japan’s experience in advanced waste management can introduce new knowledge of waste management to China. In this paper, the life cycle carbon footprint of the waste management sector was first addressed and policy suggestions were then proposed to improve waste management systems in Japan and facilitate the application of such improvements in China.

Methods and data sources

Case study

China and Japan were selected as the research areas because they are the largest developing and developed countries in Asia, respectively. In the 1960s, Japan experienced a rapid growth in MSW generation because of its economic development. This growth has presented Japan’s government with a series of challenges, such as landfill area shortages due to the nation’s limited territorial area and dioxin emissions from incinerators. After 30 years of development, the reduction, reuse, and recycle (3R) principle has been well implemented in Japan who has mature waste management legislation, waste recycling and collection systems, and advanced waste-to-energy technologies. Now Japan is experiencing aging populations in this century because of declining birth and mortality rates, and the MSW generation amount decreased year by year, from 49.75 million tons in 2005 to 41.70 million tons in 2015 (MOEJ).

With China’s exponential economic growth over the past few decades, the MSW output has increased from 148.57 million tons in 2005 to 191.42 million tons in 2015 [²³]. However, the MSW disposal ratio is far lower than the quantity delivered, meaning that huge amounts of MSW are still disposed in open dumps. MSW management has become a major concern in China and a significant issue for its government. The other developing country in Asian, such as Malaysia, shows the same upward trend of MSW generation, and the daily solid waste generated amount increased to 19100 t in 2005, 17000 t in 2007 and 21000 t in 2009, and is estimated increase to 31000 t/d by 2020 [²¹].

Hybrid LCA model

In this paper, a hybrid LCA is used because it allows a detailed analysis of direct, downstream, and upstream waste [²²]. Accordingly, three parts of the carbon footprint is considered: upstream carbon footprints, industrial process carbon footprints, and downstream carbon footprint, of which, the upstream and downstream carbon footprints are collectively known as indirect carbon emissions (Fig. 1). Upstream carbon emissions comprise the carbon footprints for electricity and heat consumption, materials, and depreciation. Direct carbon emissions include the carbon footprints for direct energy consumption and waste treatment processes. The downstream carbon footprint includes waste final disposal. The final product of the waste management sector is flow to landfill. Therefore, in this paper, the emission is treated from transportation process as downstream carbon footprint. Waste recycle carbon footprint includes carbon emission conservation from waste recycling. Calculation equations for each part are detailed in the following subsections.

Upstream carbon footprint: indirect carbon footprint

As introduced in the above, there are three parts in the upstream carbon footprint: upstream carbon footprints, industrial process carbon footprints, and the downstream carbon footprint. The indirect carbon footprint calculation methods are shown below. The parameters used in this section are taken from China Statistical Yearbook [²³] and Wang et al. [²⁴].

(1) The electricity and heat consumption carbon footprint coming from the electricity and heat consumption during the wasted treatment process is calculated using

(1){{\displaystyle C}}_{\mathrm{e},\mathrm{h}}={{\displaystyle M}}_{\mathrm{e},\mathrm{h}}\times {{\displaystyle f}}_{\mathrm{e},\mathrm{h}},

where {{\displaystyle C}}_{\mathrm{e},\mathrm{h}}is the carbon footprint of heat and electricity consumption by waste management sector (tCO₂e), M_{\mathrm{e},\mathrm{h}} is the electricity and heat consumption of the waste management sector (CNY or JPY), and f_{\mathrm{e},\mathrm{h}} is the emission factor of electricity and heat (tCO₂e/CNY or JPY).

(2) The material carbon footprint, which is the embodied carbon footprint in upstream products, is calculated using

(2){{\displaystyle C}}_{\mathrm{m}}={{\displaystyle \Sigma }}_i{{\displaystyle E}}_i\times {{\displaystyle V}}_{\mathrm{m}\mathrm{a}\mathrm{t},i},

where {{\displaystyle C}}_{\mathrm{m}} is the carbon footprint of upstream materials consumed by the waste management sector (tCO₂e), E_i is the embodied emission intensity of the industry (i) in which the material is used (tCO₂e/CNY or JPY), and {{\displaystyle V}}_{\mathrm{m}\mathrm{a}\mathrm{t},i} is the consumption of material i (CNY or JPY).

The embodied emission intensity of industry i is calculated using

(3)\mathit{E}=\mathit{D}{(\mathit{I}-\mathit{A})}^{-\mathrm{1}},

where D is the direct emission intensity of industry i (tCO₂e/CNY or JPY), row vector; I is the identity matrix; and A is the intermediate demand matrix.

(3) The depreciation carbon footprint is calculated in the same way as the material carbon footprint:

(4){{\displaystyle C}}_{\mathrm{d}\mathrm{e}\mathrm{p},i}=E\times {{\displaystyle N}}_{\mathrm{d}\mathrm{e}\mathrm{p}},

where {{\displaystyle C}}_{\mathrm{d}\mathrm{e}\mathrm{p},i} is the depreciation carbon footprint of industry i (tCO₂e), and {{\displaystyle N}}_{\mathrm{d}\mathrm{e}\mathrm{p}} is the depreciation value of industry i.

Industrial process carbon footprint

Industrial process carbon footprint includes the waste treatment process carbon footprint and energy consumption carbon footprint. The carbon footprint for the waste treatment process is calculated from the waste treatment amount and its corresponding carbon emission parameter by using

(5){{\displaystyle C}}_{\mathrm{p}}={{\displaystyle \Sigma }}_i^n{{\displaystyle W}}_i\times {{\displaystyle \gamma }}_i\hspace{0.17em}i=\mathrm{1},\mathrm{2},\mathrm{3},\mathrm{...},n,

where {{\displaystyle C}}_{\mathrm{p}}is the carbon footprint of different treatment processes (tCO₂e), {{\displaystyle W}}_iis the waste treatment capacity of each treatment method (t), and {{\displaystyle \gamma }}_iis the carbon footprint parameter of each treatment method (tCO₂e/t-waste).

The carbon footprint for energy consumption is the direct energy consumption of the waste management sector (for instance, the auxiliary fuel in the waste combustion process). It is calculated from different emission factors and consumption amounts of various types of fossil fuels introduced by the “2006 Intergovernmental Panel on Climate Change (IPCC) Guidelines for National Greenhouse Gas Inventories” by using

(6){{\displaystyle E}}_f={{\displaystyle \Sigma }}_{j=\mathrm{1}}^n{{\displaystyle M}}_j\times {{\displaystyle f}}_j{{\displaystyle \partial }}_k,i=\mathrm{1},\mathrm{2},\mathrm{3},\mathrm{...},n,

where E_f is the greenhouse gas (GHG) emissions from the fossil fuel consumption of the waste management sector (t), j is the different fossil fuel types, k is the different GHGs (CO₂, CH₄, and N₂O were considered in this study), {{\displaystyle M}}_jis the amount of fossil fuel j consumed, {{\displaystyle f}}_jis the emission factors of fossil fuel j (tGHG/t), and {{\displaystyle \partial }}_kis the global warming potential of different GHG emissions, of which the values of CO₂, CH₄, and NO_x are 1, 23, and 296, respectively.

Waste final disposal carbon footprint

The carbon footprint for waste final disposal is the direct energy consumption of the waste management sector. It is calculated as the emission from transportation process by using

(7){{\displaystyle C}}_{\mathrm{f}i}={{\displaystyle \Sigma }}_i^n{{\displaystyle W}}_{\mathrm{f}i}\times {{\displaystyle T}}_{\mathrm{f}i},i=\mathrm{1},\mathrm{2},\mathrm{3},\mathrm{...},n,

where C_fi is the carbon footprint from the waste final disposal process, W_fi is the waste final disposal amount, and T_fi is the emission factors of transportation process.

Waste recycling carbon footprint

Huge amounts of wastes or materials have been recycled in the waste management sector. The recycling waste could save a certain amount of corresponding new materials, thus decreasing the carbon emissions from the production process. The carbon footprint savings can be calculated by using

(8){{\displaystyle C}}_{\mathrm{c}\mathrm{y}\mathrm{c}}={{\displaystyle \Sigma }}_i^n{{\displaystyle Q}}_i\times ({{\displaystyle \epsilon }}_i-{{\displaystyle \gamma }}_i),i=\mathrm{1},\mathrm{2},\mathrm{3},\mathrm{...}n,

where {{\displaystyle C}}_{\mathrm{c}\mathrm{y}\mathrm{c}} is the carbon footprint of the industries corresponding to the recycled materials (tCO₂e), and {{\displaystyle \epsilon }}_i, is the carbon footprint parameter for the production process of each product, tCO₂e/t-waste.

Data sources

The fossil fuel consumption values for the waste management sector come from the energy balance table and the industrial terminal energy consumption table, which can be found in China Statistical Yearbook and the Ministry of Environment of Japan. The carbon emission factor of each fossil fuel is based on the value published in the IPCC 2006 guidelines [²⁵]. The carbon emission factor of electricity and heat is based on the emission factors of China’s regional electricity grid [²⁴]. The indirect carbon emission was calculated using the latest input-output tables for China (2012) and Japan (2011). The waste treatment amounts and corresponding CO₂ emission parameters come from previous studies [²⁶,²⁷]. The industries in the input-output tables were merged into 23 industries to reconcile China and Japan’s different classification criteria. Table 1 lists the details of these industries.

Results

MSW treatment in China and Japan

With China’s rapid urbanization, the amount of MSW generated increased from 148.57 million tons in 2003 to 170.80 million tons in 2012, the majority of which was treated in landfill sites. During this period, incineration became an increasingly popular treatment method, which decreased the landfill ratio from 85.5% to 61.55% and increased the proportion of MSW incinerated from 4.9% to 20.98%. In addition, the proportion of harmless treatment increased from 50.40% in 2003 to 84.80% in 2012.

In 2012, Japan generated 42.62 million tons of MSW, with 79.76% being treated in incinerators. During the same period, from 2003 to 2012, Japan’s recycling rate rose from 16.90% to 20.50%, and with an aging and shrinking population, per capita waste generation decreased from 1086 g/d to 922 g/d. Correspondingly, MSW decreased from 49.82 million tons in 2003 to 42.62 million tons in 2012. Hence, the final MSW disposal amount was reduced by 60% during this time.

Upstream carbon footprint

Material carbon footprint

China’s total material carbon footprint in 2012 was 9.69 million tons, much higher than that of Japan. Products in the chemical and metal smelting sectors contributed 20.29% and 25.76% to the carbon footprint of the waste management sector, respectively. An additional 13.08% and 10.66% came from the transportation and electrical, mechanical, and electronic communication sectors. In contrast, Japan’s material carbon footprint in 2011 was only 19.40 thousand tons, with transportation being the largest contributor at 32.91% of the carbon footprint. This was due to Japan’s door-to-door recycling system. The chemical sector was the second-largest contributor at 27.94% of the total amount (Fig. 2).

Waste paper, waste plastic, tire waste, and ferrous and nonferrous scrap metal are the main waste treatment process subjects in this paper. In the industrial sector, ferrous scrap from the metal smelting sector is the most recycled form of waste in China, contributing 2.450 million tons to the carbon footprint of the waste management sector in 2012 and accounting for 25.76% of the total material carbon footprint. An additional 2.69% of the material carbon footprint of the waste management sector came from waste plastic and tire waste in the nonmetal products sector, which contributed 260.9 thousand tons. Waste paper from the paper printing sector contributed 88.5 thousand tons to the carbon footprint, accounting for 0.91% of the total. In Japan, waste paper shared 1.65% of the total material carbon footprint, and the nonmetal products sector and metal smelting sector contributed only 0.27% and 0.01% to the material carbon footprint, respectively.

Carbon footprints of heat/electricity consumption and depreciation

In China, heat and electricity consumption contributed 1.55 million tons to the carbon footprint of the waste management sector, of which, 1.54 million tons came from electricity consumption, and only 6400 t came from heat consumption. Heat and electricity consumption is 44.8% higher in Japan than in China, at 2.93 million tons in 2011, of which, 2.23 million tons came from electricity consumption, with only 7800 t from heat consumption.

The carbon footprint of depreciation in China was 0.10 million tons in 2012, whereas it was only 8650 tons in Japan (Fig. 3).

Direct carbon footprint

Fossil fuel consumption carbon emissions

The direct carbon emissions of the waste management sector in China were 1.04 million tons. Coke is the most consumed energy source of the waste management sector, accounting for more than half of the total direct carbon emission. Other energy sources, such as raw coal, other washed coal, and diesel oil, also play roles in waste treatment. These fuels contributed 16.96%, 3.30%, and 10.71% to total direct carbon emissions, respectively. In Japan, fossil fuel consumption contributed 1.11 million tons to the total direct carbon emission, of which, 40.66% came from coke, and fuel oil contributed 54.03% to the fossil fuel consumption carbon footprint (Fig. 4).

Carbon footprint of waste treatment

Waste incineration, landfills, and fermentation are the main treatment methods considered in this paper, because they account for more than 98% of MSW treatment in China and Japan. In addition, energy recovery in the waste treatment process is considered. The carbon footprint of waste treatment in China and Japan are 46.46 and 2.71 million tons, respectively.

In China, 144.89 million tons of MSW were treated, generating a total carbon footprint of 49.17 million tons. Of this waste, 72.55% went to landfills, 24.74% was treated by incineration, and 2.71% was treated by fermentation. The corresponding carbon footprints for these methods are 3.52 million tons, 45.48 million tons, and 0.17million tons, respectively. In Japan, 42.62 million tons of MSW were generated, leading to a carbon footprint of 6.01 million tons for treatment processes. Of the MSW treated in Japan, 79.76% was combusted in incinerators, contributing 5.44 million tons to the total carbon footprint. Only 1.33% of MSW went to landfills, which produced a carbon footprint of 0.19 million tons. 8.92% of MSW was recycled, which produced a carbon footprint of 0.38 million tons (Table 2).

Energy recovery is conducted by electricity generation in incineration plants. The average waste power generation (WPG) efficiency in China and Japan are set as 17% [²⁸] and 12% [²⁹] respectively. The results showed that, the fossil fuel saving effect with WPG in China is 1.01 million tons equivalent coal (tce), and WPG will save up to 1.22 million tce in Japan. The carbon emission conservation of waste management sector from energy recovery in China and Japan are 2.71 and 3.29 million tons, respectively.

Carbon footprint of waste final disposal

In China, 3.58 million tons of MSW went to final disposal, while in Japan, 4.65 million tons of MSW went to final disposal. The carbon emission of waste final disposal in China and Japan are 0.17 and 0.22 million tons respectively.

Carbon footprint of waste recycling

Waste recycling has a great potential for reducing carbon emissions. Table 3 tabulates material recycling amounts in China and Japan. The total recycling amounts were 172.67 million tons in China and 80.64 million tons in Japan. Ferrous scrap was the most commonly recycled materials in Japan, totaling 44.00 million tons; in China, 44.20 million tons of iron and steel were recycled. Waste paper recycling was also considerable, with 17.03 million tons recycled in Japan and 44.72 million tons recycled in China. Wood and plastic recycling in China totaled 49.00 million tons and 24.88 million tons, respectively, and in Japan, only 6.92 million tons of wood and 7.44 million tons of plastic were recycled.

The corresponding effect of recycling on CO₂ emission reductions was also considerable, amounting to 181.37 million tons in China and 96.76 million tons in Japan (Fig. 5). Ferrous scrap recycling resulted in emission cuts of 96.80 million tons of CO₂ in China and 72.69 million tons in Japan. Because of the high CO₂ emission factor in the iron and steel sector, recycling has been the largest contributor to emission conservation. Plastic recycling in China saved 37.32 million tons of CO₂ emissions, whereas in Japan, it saved only 3.82 million tons. Recycling of nonferrous metals contributed 23.70 million tons to CO₂ emission conservation in China and 3.36 million tons in Japan. Paper recycling is another effective measure, bringing China an 18.11 million tons of CO₂ emission reduction and Japan a 16.19 million tons of CO₂ emission cut. The potential for further CO₂ emission reduction from waste recycling in China is much higher than that in Japan, because China’s current technology level results in more CO₂ emissions from the production processing.

Life cycle carbon footprint of the waste management sector

The life cycle carbon footprint of the waste management sector includes indirect carbon emissions, direct carbon emissions, and the downstream carbon footprint. The total life cycle carbon footprint in China was 59.01 million tons in 2012. In Japan, it was 7.01 million tons in 2011 (Fig. 6). The treatment process is the largest contributor to the life cycle carbon footprint in China, comprising 78.73% of the footprint. In Japan, the waste treatment process accounts for 38.80% of the life cycle footprint. Japan’s carbon footprint of heat/electricity consumption was the most considerable, accounting for 41.84% of the life cycle footprint, while in China, it only contributed 2.62% to the life cycle footprint. Material consumption of the waste management sector produced 16.42% of China’s total carbon footprint, while it only contributed 0.28% to Japan’s life cycle carbon footprint.

Discussion

The input-output analysis results showed that the waste management sector contributed 0.91% to China’s total CO₂ emissions in 2012 and 1.03% to Japan’s emissions in 2011. From the standpoint of direct carbon emissions, the reduction potential of the waste management sector is limited. However, the results show that the carbon emission reduction from waste recycling is enormous, which is much larger than the carbon emissions in the waste treatment process. This result indicates that, if further consider the carbon footprint of waste management sector from a life cycle perspective, it has contributed much more to the low carbon society development.

In terms of the quantity of waste produced, the carbon footprint of China’s waste management sector is about seven times larger than that of Japan. From a life cycle perspective, the upstream material consumption in China is much higher than that in Japan because of higher carbon emission intensity in various products produced by upstream sectors. For example, the carbon emission intensity in the paper printing sector was 7.58 × 10^-5 tCO₂e/USD in China in 2012 and only 2.80 × 10^-5 tCO₂e/USD in Japan in 2011. Similarly, the carbon emission intensity in the metal smelting sector was 0.79 × 10⁻³ tCO₂e/USD in China and 3.60 × 10⁻⁶ tCO₂e/USD in Japan (calculated in this paper). Complex waste sorting processes, such as magnetic separation, and the incineration process, led to higher electricity/heat consumptions in Japan.

Japan’s energy consumption footprint is 6.74% higher than China’s because landfills, which have a lower emission factor, are China’s most common waste treatment method, accounting for 72.55% of China’s total treated waste in 2012. In contrast, the MSW landfill treatment rate was only 1.33% in Japan in 2011. Advanced incineration techniques and a mature waste classification system in Japan have decreased the carbon emission factor for waste combustion to 16 tCO₂e/t-waste. In contrast, China’s carbon emission factor for incineration is as high as 126.9 tCO₂e/t-waste. Hence, the carbon footprint of incineration in Japan is much lower than that in China despite the fact that both nations handle a similar amount of waste [²⁶,²⁷]. Incinerators in Japan have integrated advanced technologies to decrease or neutralize harmful emissions, such as low air-ratio combustion and dioxin decomposition technologies. Moreover, Japan’s mature waste classification system has improved the calorific value of waste in Japan, which is 8800 kJ/kg (MOEJ), which, in turn, improves the combustion efficiency. However, the average calorific value of waste in China is only 4850 kJ/kg because of the country’s unsound garbage classification system [¹⁴]. For this reason, waste incineration in China consumes more fossil fuel during the combustion process, leading to more emissions.

A construction plan for a low-carbon society was launched in China in 2008. At present, 42 pilot cities have been announced by the National Development and Reform Commission. Advanced eco-town construction experiences in Japan have provided a strong precedent for China’s eco-city construction. For example, the Chinese city of Shenyang cooperated with the city of Kawasaki in Japan to build an environmentally friendly city. In 2009, Shenyang was honored as an ecological demonstration city by the United Nations Environment Program. Cooperation between China and Japan has also extended to industrial parks, which provides a platform for introducing Japan’s advanced energy conservation and environmental protection technologies to eco industrial parks in China.

Recovering energy from waste will contribute to energy savings and low-carbon development. China’s immense quantity of waste makes it necessary to recycle resources and possibly install incinerators with larger capacity and greater efficiency. However, several things should be noted. A scientific waste sorting and recycling system should be built to promote waste management in China, because this has proven to be effective for saving resources and reducing carbon emissions. Chung and Lo [³³] noted that national authorities’ lack of knowledge of treatment systems can affect waste treatment. Thus, laws and regulations should be further improved to regularize China’s waste management system. For example, enactment of the Law of the People’s Republic of China on the Promotion of Clean Production in 2002 laid the legal foundation for enhancing the implementation of 3 Ractivities by Chinese enterprises. However, specific regulations on waste recycling system construction have not been explicitly proposed. After waste source separation, further waste-to-energy processing would be more efficient.

To solve shortages in disposal capacity, encourage recycling, and promote source separation treatment, waste treatment systems in China need to be improved through a more integrated approach [³⁴]. On an industrial level, advanced waste treatment technologies should be applied to decrease CO₂ emissions from processes and improve energy recovery efficiency from waste. China is considering implementing extended producer responsibility for household electrical appliances, meaning that producers take responsibility for the recycling, reuse, and disposal of their products after use. In civil society, the active support and investment of real estate companies and community residential committees will affect household attitudes about waste separation [¹³,¹⁹]. Fortunately, China’s MSW treatment sector is growing rapidly, and the government will invest 192.4 billion CNY to promote MSW treatment and address corresponding problems during its 13th Five-Year Plan.

The Japanese government is vigorously promoting waste recycling and a sound material-cycle society. Aside from their waste recycling system, Japan will further promote the construction of reduce and reuse in the 3R principle through a series of regulations, such as a law covering the effective implementation of small appliance recycling and the Law for the Promotion of Effective Utilization of Resources. However, some areas still need improvement.

A comprehensive program of integrated low-carbon, natural symbiosis societies and a higher level of regional recycling should be further developed. MSW management policy should focus on incineration, since 82.6% of MSW in Japan is incinerated to produce electricity, while the average power generation efficiency is 12%, which leaves much room for improvement [²⁶]. Until 2014, Japan had 1162 incinerators; however, most are used in small-scale treatment, with 83.5% having capacities of less than 300 t/d and 34.3% of incinerators lacking any energy recovery facility (MOEJ). Centralized waste treatment and the phasing out of small and low-efficiency incinerators are options for improving treatment efficiency. On the other hand, combining a waste management system with industrial and heating systems would be another effective way of reducing emissions [³⁵].

Conclusions

Efficient waste management can play a significant role in reducing CO₂ emissions and conserving energy. Therefore, a hybrid LCA was conducted to estimate the carbon footprint of each production stage in the waste management sectors in China and Japan and provide policy suggestions for waste management in China. The research comparing China and Japan could demonstrate gaps in each process in these two countries and provide references for other Asian countries.

In this paper, four areas were considered: the upstream material consumption carbon footprint, the waste treatment process carbon footprint, the waste final disposal carbon footprint, and the waste recycle carbon footprint. The total carbon footprints of China and Japan are 59.01 million tons and 7.01 million tons, respectively. Waste treatment processes contribute 78.73% to China’s total carbon footprint, but only 38.81% to Japan’s total carbon footprint. Additionally, waste recycling has led to a 181.37-million-ton carbon footprint reduction in China and 96.76-million-ton carbon footprint reduction in Japan. This indicates that the waste management sector has contributed much more to the low carbon society development if further consider the carbon footprint from a life cycle perspective.

China’s high emission factor for incineration is the main reason for its high carbon footprint for waste treatment processes. To reduce this treatment carbon footprint, the waste sorting system is needed to separate wet kitchen waste and other matter unsuitable for incineration, thus improving the calorific value of combustible waste and improving waste recycling ratio. The ratio of landfill should be further decreased to promote recycling, reuse, and conversion of waste-to-energy. Based on Japan’s experience on waste management, a sound legislative framework would provide a fundamental guarantee that efficient waste management would be promoted.

Japan and China face different challenges and barriers to waste management. In Japan, major trends in waste management policy include the construction of reduction and reuse policies, building a low-carbon, natural symbiosis society, and achieving a higher level of regional recycling. Their shared goal is to realize a society that uses resources, including stock resources, efficiently and sustainably across the whole life cycle, by reducing natural resource consumption and promoting the use of recycled materials and renewable resources. In China, a waste sorting and recycling system should be built first before policy implementation and technological feasibility in different regions are considered. Key challenges for the future are efficiently linking waste management and resource management to realize integrated waste/resource management. This will require strengthening the cooperation of the relevant government sectors and promoting the participation of stakeholders.

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