Study On Characteristics Of Generation And Management Of Demolition Wastes During Urban Renewal

With the continuous and steady progress of urbanization in China,many cities face increasingly serious problems of resources and environment.Among them,the problem of demolition waste caused by the large-scale urban renewal and transformation activities is particularly prominent.At present,this kind of demolition waste is mainly simple landfilled with low resource utilization and large safety and environmental risks.In order to optimize the environmental management of demolition waste and improve its resource utilization efficiency,and promote sustainable urban construction and development,this study will estimate and forecast the amount of waste removal under the background of urban renewal and transformation,and focus on the systematic analysis of waste removal from the perspective of urban village reconstruction.The characteristics and management characteristics of abandoned objects.Firstly,three large and medium-sized cities(Shenzhen,Nanchang and Zhengzhou)with different levels of economic development and regional characteristics were selected as the research objects.Based on objective conditions,reasonable selection and follow-up investigation were carried out on some urban village reconstruction projects.Through field sampling and data analysis,list of data of waste removal was formed..The results show that there are significant differences in the unit production and waste rate,material composition and so on.Among them,Shenzhen City Village demolition waste unit production rate is the highest,an average of 1,450 kg/m2;Zhengzhou City slightly lower,an average of 1,150 kg/m2;and Nanchang City demolition waste production rate is relatively low,but also reached about 970 kg/m2.It is mainly due to the differences in the types of urban village buildings,such as Shenzhen and Zhengzhou urban village buildings are mainly brickconcrete structure,while Nanchang is mainly brick-wood structure.Secondly,based on the production and waste rate data and combined with the three urban renewal planning data,this paper constructs the urban scale urban renewal project waste generation measurement model and estimates and analyzes.The results show that in recent years,the amount of demolition waste produced by the three selected urban villages is obviously different because of the different speed of renovation,but all of them keep a rapid growth.Among them,Shenzhen is very short of land resources and the old reform projects planned in recent years are more centralized and the growth rate is the fastest.The amount of waste removal in urban villages has increased from 7.44 million tons in 2013 to 12.3 million tons in 2016.The urban renewal in Zhengzhou is actually more active,and the amount of waste removal in urban villages has reached the highest level in 2014.(1.62 million tons),but in the past two years due to the scale of the transformation reduced and the rate of slowing down,the number of urban villages in 2016 only 510,000 tons of waste removal;Nanchang,due to the large-scale shantytown transformation began in 2013,in recent years the growth rate is faster,the amount of waste removal in 2016 reached 4.33 million tons.In addition,through the follow-up investigation and analysis of the flow direction management of the demolition waste,the results show that the recovery rates of metal materials in the demolition waste of the three urban villages are relatively high(nearly 100%),followed by timber and plastic building materials(about 30% on average);the recovery rates of masonry concrete and other low,Shenzhen and Zhengzhou.About 5% of the city;Nanchang is still using artificial brick recovery in the demolition stage of the village in the city,so the recovery rate of green and red bricks is relatively high,with an average recovery rate of about 40%.Finally,based on the input-output data of the recycling and disposal stages of the dismantled wastes,the potential environmental benefits of promoting the recycling and utilization of the dismantled wastes were preliminarily evaluated.The carbon emissions were taken as the evaluation index,and the results showed that the efficiency of the dismantled wastes recycling and water utilization were improved.It can produce significant environmental benefits.The first-hand data obtained in this paper and the established measurement methods can provide a basis for the systematic management and further research of waste removal,and provide a reference for different cities to formulate different policies for waste removal management.