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附錄
An Analytical Study on the Resource Recycling Potentials of
Urban and Rural Domestic Waste in China
Abstract
The total wet-basis weight of urban and rural domestic waste in China is about 500,000,000 tons every year, 60% of which comes from dry-basis waste (about 300,000,000 tons). Single-composition, clean waste that is separated on a dry basis, especially the low-value components such as food waste and plastics, has huge resource recycling potentials. The potential added values from resource recycling of the 500,000,000 tons of urban and rural domestic waste would be around RMB 926.17 billion, RMB 1,065.98 billion and RMB 1,205.81 billion upon three prices of granulated organic-inorganic compound fertilizers. A potential value of RMB 1,065.98 billion, for instance, would be 2.26% of China’s 2011 GDP (RMB 47.1564 trillion), which may make resource recycling of domestic waste one of the large industries. Resource recycling of domestic waste is a major energy-saving and environment-friendly strategic emerging industry in China, and a prioritized management strategy for resource recycling of domestic waste should be established for the maximum resource recycling.
Keywords: Domestic waste; Resource recycling; Potential analysis
1. Issues
The evaluation on resource recycling potentials of urban and rural domestic waste in China is an important basis for a well-drawn technology roadmap of domestic waste and workable management policies. According to the dry-basis separation test for urban residential waste, domestic waste includes high-value marketable waste and low-value unmarketable waste, in which paper, bulky furniture and others in the first category may be collected and sold via various channels, whereas those in the second category go to landfills or are burned because of their “uselessness”.
According to the World Bank, there will be a vast market for secondhand materials in China, and by 2030, urban waste in China – paper and metals in particular – will be one of the biggest commodity sources in the world. Domestic studies show that China produces 400,000,000 tons of domestic waste each year, indicating it is time to use waste as a strategic resource. According to the academic community, waste should be known as the one and only growing resource, and the waste industry should be planned as one of the key industries.
According to relevant statistics, “renewable resources” that are discarded in Chinese cities every year are valued at RMB 25 billion, and the yearly value of discarded domestic waste “resources” approximates at RMB 125 billion. In China, every year there is a huge amount of domestic waste buried or burned before separation, and its resource recycling potentials need to be further studied. In this paper, the resource recycling potentials of value-added processing and production of dry-basis raw materials from urban and rural domestic waste in China are estimated and analyzed on the basis of the dry-basis separation test and relevant domestic studies.
2. Total Weight and Total Dry-basis Weight of Urban and Rural Domestic Waste in China
Accurate basic data of the total wet-basis weight and the total dry-basis weight is a necessity for the resource recycling potential analysis of domestic waste. However, all we know about urban domestic waste at present is how much it has been collected and transported instead of being produced, and for rural domestic waste, we lack both. Therefore, we have to estimate the production from the weight of collected and transported waste, and calculate the production of rural domestic waste according to relevant data.
2.1 Annual production of urban domestic waste
According to the Ministry of Construction, urban domestic waste that was collected and transported in 654 cities of China amounted to 157,000,000 tons in 2010. The production is supposed to be 25% higher, or, according to Zhang Li Jing’s conservative estimate, 30% higher. So the actual production of urban domestic waste in the 654 cities may be estimated between 196,250,000 tons and 204,100,000 tons – 200,000,000 tons for convenience.
2.2. Annual production of rural domestic waste
According to a nationwide survey on drinking water and environmental health in rural areas that was jointly organized by the National Patriotic Health Campaign Committee and the Ministry of Health from August 2006 to November 2007, domestic waste was a major part of farmer household waste, the daily production of rural domestic waste was 0.86kg per person, and every year there was nearly 300,000,000 tons of domestic waste produced in China’s rural areas, of which 1/3 (about 100,000,000 tons) was randomly dumped and seriously polluted the environment.
2.3. Total dry-basis weight of urban and rural domestic waste
The average water content of urban residential waste in Beijing is 50.19%. Estimated from a water content of 50%, the 200,000,000 tons of urban domestic waste produced in China includes about 100,000,000 tons of water, which means the total dry-basis weight is 100,000,000 tons. Calculated from a water content of 35.79% of rural domestic waste in Beijing, the 300,000,000 tons of rural domestic waste in China is the sum of 107,370,000 tons of water and about 200,000,000 tons of dry-basis waste. In such a case, the annual amount of urban and rural domestic waste in China is about 500,000,000 tons, including more than 200,000,000 tons of water and about 300,000,000 tons of dry-basis waste.
2.4. Reference physical components for evaluation on resource recycling potentials of urban and rural domestic waste
The evaluation on the resource recycling potentials of urban domestic waste is based on reference components in Table 1and Table 2, and that of rural domestic waste is based on the findings of Xie Dongming.
Table 1. Physical components of domestic waste in the eight urban districts of Beijing, 2007 (wet basis, %)
Table 2. Physical components of low-value urban residential waste
Table 3. Physical components of rural domestic waste in China (wet basis, %)
3. Estimates on Resource Recycling Potentials of Urban and Rural Domestic Waste
Based on the reference components in Tables 1-3, the resource recycling potentials of major domestic waste are estimated as follows.
3.1. Food waste
Urban food waste. Urban household food waste are a quite large part of domestic waste (as shown in Table 1, food waste accounted for 66.22% of the domestic waste in the eight urban districts of Beijing in 2007). For convenience, we assume 60% of urban domestic waste is food waste in average, so there would be 120,000,000 tons of food waste in the 200,000,000 tons of urban domestic waste. According to Li Zhenshan et al., the dry weight of food waste is 20-25%, so the annual total dry-basis weight of urban food waste in China would be 27,600,000 tons upon a mean dry weight of 23%. The most appropriate water content for composting is 50-60%, and the produced organic fertilizers weigh 50% lighter than the total, so the potential amount of organic fertilizers from urban domestic waste in China would be 21,390,000 tons in case of a water content of 55% (27,600,000 x 1.55 = 42,780,000/2).
According to Table 3, food waste accounts for 24.54% of the total rural domestic waste in China. Based on a rounded percentage of 25%, the total amount of rural food waste in China would be 75,000,000 tons, including 17,500,000 tons of dry-basis waste (dry-basis content: 23%) which could produce 13,562,500 tons of organic fertilizers (17,500,000 x 1.55 = 27,515,000/2).
According to the above analysis and estimates, the theoretic potential amount of organic fertilizers from food waste in the annually 500,000,000 tons of urban and rural domestic waste in China would be 34,952,500 tons (21,390,000 + 13,562,500). In case of the most appropriate ratio of organic and inorganic nutrients for organic-inorganic compound fertilizers (1:1), the potential amount of organic-inorganic compound fertilizers from food waste in China approximates at 69,905,000 tons.
Granulated organic-inorganic compound fertilizers are efficient, high-quality slow-release fertilizers. Slow/controlled release fertilizers usually cost 3-9 times more than ordinary fertilizers outside China, and 2-8 times more than ordinary chemical fertilizers, known as “unaffordable fertilizers”. By June 2012, the price of urea in the domestic market has been stabilized at around RMB 2,300/t. Given the price of urea is RMB 2,000/t, then the potential value of the 69,905,000 tons of granulated organic-inorganic compound fertilizers would be RMB 139.81 billion, RMB 279.62 billion and RMB 419.43 billion at different price ratios of slow/controlled release fertilizers and ordinary fertilizers (1:1, 2:1 and 3:1).
3.2. Waste plastics
Low-value waste plastics are usually sent to landfills or burned rather than being recycled, leading to serious environmental pollution and resource waste. According to Table 1, waste plastics accounted for 13.11% of domestic waste in the eight urban districts of Beijing, so the total amount of plastics in urban domestic waste in China would be 20,000,000 tons (the percentage is assumed at 10% for convenience).According to Table 3, 6.02% of rural domestic waste is plastics, so the total amount would be 18,060,000 tons. As a result, the annual production of urban and rural waste plastics would be about 38,060,000 tons.
Wood-plastic composites are new reversible and recyclable multipurpose materials which are mainly made of wood fibers and plastics (plastic resin: 30-75%; wood fibers: 25-70%). Wood-plastic building templates made of waste plastics (30%) and wood chips (70%) have already been developed in China, which means 126,870,000 tons of wood-plastic boards can be produced from the 38,060,000 tons of waste plastics. Assuming wood-plastic templates cost RMB 5,760/t [20], the potential value would be RMB 741.1 billion.
The application of wood-plastic composites is an important national policy of China concerning renewable resources. In 2010, the National Development and Reform Commission, the Ministry of Science and Technology, the Ministry of Industry and Information Technology, the Ministry of Land and Resources, the Ministry of Housing and Urban-Rural Development and the Ministry of Commerce jointly issued the Outline of Technical Policies for Comprehensive Use of Resources in China, clearly putting forward the decision to “promote the technologies that utilize waste plastics and wood materials for the production of wood-plastic composites and products.” A two-step development strategy for the wood-plastic composite industry has also been unveiled:
Step 1 (2011-2015): 5,000,000 tons (basic objective); 8,000,000 tons (development objective);
Step 2 (2016-2020): 15,000,000-20,000,000 tons (development objective) [21]; an industrial system with an annual output of RMB 300 billion.
Table 4: Annual outputs, objectives and potentials of wood-plastic composites in China
Source: Outline of the Development Plan for China’s Wood-Plastic Composite Industry in the 12th
Five-year Plan Period
3.3. Toilet paper
Waste toilet paper is not listed in Table 1 and Table 3 as a physical component of domestic waste. Despite serious pollution, the separate collection and disposal of such waste are seldom mentioned in domestic research documents. As far as resource recycling is concerned, it is a rich cellulosic resource with stable sources. It is practical to produce fuel ethanol from separately-collected waste toilet paper through centralized disposal.
In industrially developed countries, there are 170 tons of cellulosic materials in every 250 tons of urban waste, which can produce about 36.5 tons of ethanol – 14.6 tons of ethanol out of 100 tons of cellulosic waste. The dry-basis separation test shows that 166.29kg of low-value unmarketable waste includes 8.75kg of toilet paper (5.26%). Without public data, we assume waste toilet paper averagely accounts for 3% of urban and rural domestic waste, so there would be 15,000,000 tons of waste toilet paper in the yearly 500,000,000 tons of domestic waste in China, which could produce 2,190,000 tons of ethanol worth of RMB 13.14 billion (at the minimum price of RMB 6,000/t).
US technologies such as Nitick and Penn-GE (complex hydrolysis and fermentation) which is jointly developed by the University of Pennsylvania and General Electric work on urban cellulosic waste to transform all the organisms into liquid fuels and other valuable products, making new breakthroughs in the energy-oriented use of urban cellulosic waste and suggesting biological disposal solutions for urban and rural cellulosic waste (other than burying or burning it).
3.4. Waste glass
According to Tables 1-2, glass accounts for 0.95% of urban domestic waste in China (200,000,000 tons x 0.95% = 1,900,000 tons). In rural domestic waste there is 4,530,000 tons of glass (300,000,000 x 1.51%). Therefore, there is totally 6,430,000 tons of glass in urban and rural domestic waste. Each ton of waste glass can produce 20,000 wine bottles. Conservatively, each bottle costs RMB 0.1, so the market potential of waste glass is RMB 2,000 per ton, that is, RMB 12.86 billion in total.
In fact, waste glass may have higher economic value after resource recycling. Concrete with 35% of glass aggregates from the US has proved qualified for the design requirements in its compression strength, shrinkage and water absorbability. Waste glass can also be made into glass-ceramic artificial marble slabs, building tiles, glass mosaics, heat-insulating and soundproof materials, etc. The potential value of the 6,430,000 tons of waste glass may be higher in case of a larger value-added production.
3.5. Used clothes
So far used clothes are seldom recycled as resources but directly buried or burned in most cases. Based on relevant data in Tables 1-3, the total amount of used clothes in urban and rural domestic waste in China is 8,110,000 tons, including 3,280,000 tons in urban domestic waste and 4,830,000 tons in rural domestic waste. The prices of used clothes offered on www.zz91.com from May 17 to June 17, 2012 ranged from RMB 700/t to RMB 8,800/t. The 8,110,000 tons of used clothes would cost RMB 8.11 billion at a price of RMB 1,000/t.
The industrialization of technologies for comprehensive use of used clothing fibers has been included into the Outline of Technical Policies for Comprehensive Use of Resources in China, and national policies have made it clear to industrialize the recycling of used textiles. By turning such domestic waste as glass, textiles, paper and tiles into reinforcing fillers for wood-plastic composites, Ma Jianli et al. have found that short textile fibers have the best mechanical properties for reinforcing, which creates a new way for the recycling of used clothes in domestic waste.
3.6. Waste electronics, paper and metals
Waste electronics are not listed in Table 1 and Table 3 as physical components of domestic waste. According to Table 2, the percentage of waste electronics in low-value non-marketable waste is 1.24%, so we estimate there are about 6,200,000 tons of waste electronics in the 500,000,000 tons of domestic waste in China. The estimates of the Ministry of Science and Technology show that by 2010, there were 3,000,000 tons of waste electronics in China, and the figure will climb to 5,000,000 tons by 2015. According to relevant estimates of Tianjin Recycling Research Institute of China, the potential price of waste electronics per ton is above RMB 1,000, so the potential value of the 3,000,000 tons of waste electronics in 2010 would at least exceed RMB 3 billion.
According to Table 1 and Table 3, paper accounts for 10.68% of urban domestic waste (about 21,360,000 tons) and 2.88% of rural domestic waste (about 8,640,000 tons) in China, so the total weight would be 30,000,000 tons. The potential value would be around RMB 30 billion if the paper costs RMB 1,000/t (a modest price of waste paper in the Pricelist of Renewable Resources in Some Cities and Provinces of China, June 12, 2012.
According to Table 1 and Table 3, metals account for 0.68% of urban domestic waste (about 1,340,000 tons) and 0.64% of rural domestic waste (about 1,920,000 tons) in China, so the total weight would be 3,260,000 tons. The potential value would be at least RMB 8.15 billion at a price of RMB 2,500/t for general waste steel according to the Pricelist of Renewable Resources in Some Cities and Provinces of China, June 12, 2012.
The recycling potentials of tiles, mucks, bamboo and other components as well as the 200,000,000 tons of water are not estimated in this paper.
4. Conclusions
(1) Recycling of urban and rural domestic waste would create potential values of RMB 926.17 billion, RMB 1,065.98 billion and RMB 1,205.81 billion upon three prices of granulated organic-inorganic compound fertilizers. 69,905,000 tons of granulated organic-inorganic compound fertilizers would be produced from food waste, so the potential values from resource recycling would be RMB 139.81 billion, RMB 279.62 billion and RMB 419.43 billion upon the three prices. 126,870,000 tons of wood-plastic slabs would be produced from 38,060,000 tons of waste plastics, so the potential value from resource recycling would be RMB 741.1 billion. 2,190,000 tons of ethanol would be produced from waste toilet paper, so the potential value from resource recycling would be RMB 13.14 billion. The potential values from resource recycling of waste glass (6,430,000 tons), used clothes (8,110,000 tons), waste electronics (3,000,000 tons) and waste metals (3,260,000 tons) would be RMB 12.86 billion, RMB 8.11 billion, more than RMB 3 billion and more than RMB 8.15 billion respectively.
Fig.1. Resource recycling potentials of different components of low-value domestic waste (unit: RMB 100 million)
(2) Dry-basis separation from the source is the basis for the industrialization of domestic waste resources. Effective source separation is the only way to separate renewable resources in domestic waste into single-component, clean raw materials for pre-homogenization, so as to realize resource recycling, truly eliminate environmental pollution and resource waste caused by mixed burying or burning, and help tackle the crises of resource shortage and the encirclement of domestic waste.
(3) Resource recovery of domestic waste is a major strategic emerging industry in China. The waste recovery output in China exceeded RMB 1 trillion in 2010, and is expected to hit RMB 2 trillion by 2015. Resource recycling of domestic waste, with a potential value of about RMB 1 trillion, is an even more crucial energy-saving and environment-friendly strategic emerging industry which will continue to grow in the future.
(4) How to break the bottleneck of separation technologies is the key to recovery of domestic waste. The long-existing absence of breakthroughs in separation of domestic waste is one of the reasons for the increasingly serious crisis of domestic waste in China. It is necessary to build a smoothly-connected, comprehensive dry-basis separation technology system for separate collection, transportation and disposal, give priority to the development of key technologies, and continue to develop, test and improve dry-basis low-frequency direct transport technologies.
資源回收潛力分析研究——基于中國城市和農(nóng)村生活垃圾的研究
摘要
中國城市和農(nóng)村生活垃圾總濕基重量大約是每年5億噸，其中60％來自干基廢物（約300,000,000噸）。單組合物，清潔廢物分離以干基計(jì)算，特別是低價(jià)值的食品廢物和塑料組件，具有巨大的資源回收再利用的潛力。500,000,000噸的城鄉(xiāng)生活廢物的資源化利用的潛在附加價(jià)值將約為人民幣926.17億元，人民幣1,065.98億元及人民幣1,205.81億元，在三個(gè)價(jià)格顆粒狀的有機(jī) - 無機(jī)復(fù)合肥料。一個(gè)潛在的價(jià)值為人民幣1,065.98億元，舉例來說，將是中國2011年GDP的2.26％（471564億人民幣），這可能使國內(nèi)廢棄物資源循環(huán)利用成為大產(chǎn)業(yè)之一。家居廢物資源回收是一個(gè)主要的能源節(jié)約型和環(huán)境友好的戰(zhàn)略性新興產(chǎn)業(yè)，在中國應(yīng)優(yōu)先建立最大的資源回收和資源回收家居廢物管理策略。
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