| With the economical development and the improvement of our life level in China, the demands of protecting the living-environment and ecological environment is increasing day by day. At the same time, the sources and amount of municipal solid waste (MSW) production are all raised by the influence of diversification of consumption patterns and improvement of comsumption level, which continuously threatens the environmental quality and public health. Since the environmental carrying capacity owned by the rural areas has not caught up the intensity of environmental pollution, it’s urgent to process MSW by a scientific way. In recent years, in the condition of less land resource and strict requirement of environmental conservation, the area sharing of public infrastructure and the effective scale operation has represented a general trend. The urban-rural integration of MSW treatment should be greatly pushed. As the key link of it, the option of waste transfer mode and the construction of transfer system is a thesis task with theoretic research value and practical content.In the study, multiple methods, such as field survey, questionnaire, web search and expertise consultation, were used to collect current situation data of MSW treatment in many provinces, cities, towns and villages. After gathering these data of 106 towns and villages, some rational indexes were selected to establish a fuzzy comprehensive evoluation model, which was used to evoluation the existing situation of MSW treatment in rural areas of our country. The result of evoluation indicated that the situation of MSW treatment in rural area was generally serious. The level of MSW treatment was related closely with the level of urban and rural integration. By analyzing the urban and rural systems and the situation of MSW treatment, three types of urban-rural integration for MSW treatment were proposed. They were close connection type, relative close type and relative dispersive type. It can be seen from the structure chart of the urban-rural integration of MSW treatment summarized from those types that, with whatever any integration type, MSW transfer system was the basic and crucial point to achieve integration.Then, according to the theory of integer-linear program in operations research and the minimum cost of transportation, adopting the notions of equivalent cost and total cost, a node optimization model of waste transfer system, that is, a mixed integer-linear planning model, was established. Moreover, the computing formula of threshold distance was obtained by the simplification and integration of this model based on the practical situation in China, which can distinguish the primary transfer system and secondary transfer system. When the amount of MSW production were 150t/d,450t/d, and 1000t/d, the corresponding threshold distances were separately 34km,28km and 24km. If the transfer distance exceeds the threshold distance, the secondary transfer station is needed. The result can provide decision-making basis for the optimization of waste transfer pattern in different urban-rural systems.Furthermore, a case of Kunshan in Jiangsu province was studied for empirical research. The urban-rural integration type of Kunshan belonged to the close connection type, so it could adopt the MSW managing method of "village collection, town transfer and city disposal". Based on the threshold distances calculated above, the transfer pattern of "combination of two points and three zones" was put forward to transfer all MSW to the final disposal site. At last, the site selection schemes of secondary transfer station in each MSW transfer zone were compared by using the node optimization model. The ranges for locating the secondary transfer stations were decided respectively. It made the construction of MSW transfer system flexible and feasible to detail the implement program of the urban-rural integration mode of MSW treatment in Kunshan. |
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