附录
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
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