Discussion on development opportunities and countermeasures of building solid waste resource industry
Various provinces and cities have successively issued implementation plans for the construction of "waste-free cities" and started to focus on planning waste recycling industries, so as to achieve the goal of waste recycling utilization and promote the green development of cities. During the implementation period, there are also many obstacles, resulting in the slow layout and low recycling rate of construction waste treatment facilities in large and medium-sized cities, which is far from the level of waste recycling of more than 70% in developed countries such as Japan, Germany and the United States, and also restricts the enthusiasm of social capital to participate in urban public utilities investment. Based on the current situation of China's construction waste recycling industry, combined with the Work Plan for Building a Waste-free City in the Tenth Five-Year Plan period jointly issued by 18 departments including the Ministry of Ecology and Environment, this paper sorts out the industrial chain of China's construction waste recycling, analyzes the reasons and bottlenecks that restrict its development, so as to study and formulate relevant industry development plans and strategies for reference by relevant government departments, investment enterprises and contractors.
1. China's construction waste recycling industry background analysis and development status.
Construction waste is a general term for wastes generated in the process of new construction, alteration (expansion) construction, demolition of various buildings (structures), pipe networks, roads and bridges, and house decoration, mainly including engineering muck, waste mud, engineering garbage, demolition garbage and decoration garbage. According to the data released by China Huanlian, at present, China's construction waste accounts for more than 40% of the total urban waste, and the annual output of construction waste exceeds 3.0×109t, which is expected to reach 4.0×109t in 2025, as shown in Figure 1. However, at present, the recycling rate of construction waste in large and medium-sized cities does not exceed 10%, which is far from the recycling level of construction waste in developed countries such as Japan, Germany and the United States.
In order to improve the recycling level of urban waste in China and implement the development strategy of urban green and low-carbon cycle, the Ministry of Ecology and Environment, together with other ministries and commissions, formulated and issued the "Pilot Work Plan for the Construction of Waste-free City" in December 2018, putting forward the concept of "waste-free city" for the first time, which is a development concept based on green, openness, coordination, innovation and sharing, and an urban development model that continuously promotes the reduction of solid waste sources and resource utilization. After a successful pilot, 18 ministries and commissions jointly issued the Work Plan for Building a Waste-Free City during the Tenth Five-Year Plan period on December 15, 2021, which emphasized the need to reduce the source of urban construction waste, improve the utilization rate of resources, rationally arrange the facilities for the transfer, disposal and recycling of construction waste, and form a construction waste treatment system that matches the needs of urban development, which has formed policy support for the overall development of the construction waste recycling industry.
In order to implement this plan, various provinces and cities have issued specific implementation plans including the development plan of recycling construction waste. For example, Shenzhen requires that the recycling rate of construction waste will reach 35% in 2025, of which the recycling rate of house demolition waste will reach 95%; Shandong Province requires that the construction of "waste-free cities" should be started in 16 cities from 2022. During the "Tenth Five-Year Plan" period, the proportion of newly-started prefabricated buildings should reach 40%, and the proportion of green buildings in new civil buildings should reach 100%. The implementation of specific plans in these places has supported the improvement of the recycling level of construction waste and the consumption of recycled products.
However, comparing the current stage development goal of China's urban construction waste recycling industry with the existing level of construction waste recycling in developed countries, we can find that although China's construction waste recycling industry started earlier, its overall development is still a sunrise industry. The low level of recycling, the shortage of construction waste treatment facilities, the lack of technological innovation and market drive are the urgent problems to be solved in the development of construction waste recycling industry.
2. Present situation of pretreatment and resource utilization of engineering muck
Engineering muck refers to all kinds of buildings (structures), pipe networks, roads and bridges, etc., which are abandoned by excavation of earthwork in the construction process. At present, the treatment methods of engineering dregs in various places mainly follow the principle of on-site utilization, and are treated by means of balanced consumption of earthwork within the region, landfill of surplus soil outside the country and resource utilization. According to the soil type and material composition in the muck, the products of the muck resource utilization can include site cover or garden planting soil, subgrade soil and road inorganic binder; Machined sand; Recycled aggregate concrete and its components; Recycled aggregate mortar; Ceramsite and pottery sand; Sintered recycled bricks and blocks; Non-sintered recycled bricks, blocks, plates, etc.
Enterprises engaged in waste residue resource treatment in the southern coastal areas of China mostly adopt the recycling scheme of machine-made sand and foundation solidified soil, while in the northern areas, the main methods are crushing and screening, piling mountains and landscaping, landfill and digestion (such as Beijing-Tianjin-Hebei area). The project cases of firing ceramsite and making non-sintered bricks and light wall materials with waste residue are applied in some southern provinces of China (such as Jiangsu, Zhejiang, Anhui, Fujian, etc.). Generally speaking, the recycling level of engineering waste residue is low. Cases of waste residue resource utilization in Xiamen and Ningbo.
3. Present situation of pretreatment and resource utilization of waste mud
Waste mud refers to the waste and surplus mud produced by the construction of various buildings (structures), foundation pit retaining structures, slurry shield and pipe network excavation. At present, most of the waste mud is dehydrated and solidified on site, and the foundation backfill soil and green soil are produced on site, while the centralized treatment for deep processing and reuse is less, mainly because of the high water content of mud, high transportation cost and uneconomical centralized treatment. If it can be dehydrated and transported by the field centrifuge, the disposal cost of waste mud will be greatly reduced. The recycled products after the disposal of waste mud can be recycled aggregate, mortar and recycled brick, and can also be used as garden planting soil, subgrade water-stable material and base-level solidified soil after improvement, and can also be used for co-firing ceramsite with muck and other sludge. In China's coastal areas, due to the lack of soft soil foundation and clay resources, there are many recycling routes of waste mud used as subgrade soil backfill and brick making after solidification, but there are relatively few ceramsite firing.
4. Market capacity of construction waste pretreatment and recycling industry under the background of "waste-free city" construction and double carbon.
Since the Ministry of Ecology and Environment issued a document in 2019 to carry out the pilot project of "waste-free city" construction in the first batch of 16 cities and regions in China, in 2022, seven provinces and cities including Shandong, Hebei and Jiangsu released the implementation plan to promote the construction of "waste-free city" in the whole region. According to the goal of "Work Plan for Building a Waste-free City during the Tenth Five-Year Plan", it is estimated that by 2025, there will be about 100 cities at or above the prefecture level in China to build a waste-free city, and an assessment target of 30% has been set for the recycling rate of urban construction waste.
Based on this calculation, China's urban construction waste treatment market will release at least 6.0×108t of new production capacity, equivalent to about 1.2×108t of construction waste treatment per year. In addition, the plan also sets the proportion index of urban prefabricated building area to the newly started building area (generally not less than 40%). According to the calculation of the newly started building area in China in 2020, it is estimated that the newly added prefabricated building area will be about 3.0×109m2 every year during the Tenth Five-Year Plan period. If 20% of the floor insulation projects and 40% of the lightweight walls use construction waste resource products, It can consume about 8.0×108m3 of recycled building materials every year, which creates conditions for the construction waste pretreatment and recycling industry to further improve the industrial chain, release production capacity and sustainable development.
According to GB/T 51366-2019, the carbon emission of renewable building waste generated in the construction and demolition stages can be calculated as 50% of the carbon emission of its replaceable primary raw materials. However, in the process of actual urbanization, the purified carbon generated in the production of building materials such as cement, steel and glass and construction accounts for about 11% of the total carbon emission every year. Therefore, the implementation of the national "double carbon" target strategy will promote the green and low-carbon transformation of the construction and building materials industries, making them a new force for carbon reduction and carbon neutrality, thus providing a broader market space for the construction waste recycling industry.
5. New development opportunities
The construction of urban venous industrial park and eco-environmental protection demonstration zone advocated by the "Waste-free City" construction scheme provides the possibility for the coordinated disposal of construction waste and other urban and rural solid waste. By practicing the economic development concept of "building and sharing infrastructure" and "double circulation" of materials and energy, the construction waste resource project can be implemented, which can realize low-cost operation and high value-added products output.
For example, Shanghai Laogang Vein Industrial Park is the world's largest standardized multi-source solid waste comprehensive disposal base, which mainly deals with domestic waste, and it has the capacity of 1.0×106t/a demolition/decoration waste pretreatment and resource utilization, and has achieved good social and environmental benefits after its completion; Suzhou Everbright Environmental Protection Industrial Park is a modern environmental protection industrial park that centrally treats urban industrial and domestic garbage. It can cooperatively dispose of combustible materials of construction garbage, and use the slag generated by incineration to make recycled building materials. The steam generated can be used as the heat source of other projects in the park, thus realizing the comprehensive utilization of materials and energy to the maximum extent.
In southern China, a new technology for producing lightweight ceramsite by co-disposal of engineering dregs and sludge from water plants has been widely used, which will solve the treatment problems of sewage sludge and engineering dregs at the same time, and maximize the economic benefits of multi-source waste co-disposal. Successful cases such as the 5.0×105m3/a new ceramsite production line (engineering dregs/sludge as raw materials) put into operation by Anhui Changjiuqu Environmental Protection Technology Co., Ltd. in 2022, Jiangsu Ruixin Shiyue Environmental Protection New Materials Technology Co., Ltd. 6.0×105m3/a new ceramsite production line, etc., which combines traditional waste treatment with new building materials manufacturing, is a new way to develop the construction waste resource industry.
It can be predicted that with the implementation of the construction plan of "waste-free city" and the development of multi-source waste collaborative disposal technology, the circular economy model that realizes cross-regional and cross-industry development will replace the single eco-environmental project development model through the joint construction and sharing of infrastructure between venous industrial park and comprehensive environmental protection demonstration park, thus promoting a large number of construction waste resource projects to land in the park and contributing to the construction of "waste-free city".
6. New challenges
(1) The lack of innovation in technology, products and market of construction waste recycling industry restricts the vigorous development of construction waste recycling industry.
(2) The industrial policy of recycling construction waste is not perfect, and the supply chain has not been opened, which hinders the survival and large-scale development of enterprises.
(3) Lack of systematic research on the recycling industry of construction waste, as well as interdisciplinary and multi-professional technology integration and collaborative research, resulting in low recycling rate of construction waste, low added value of products and low industry prosperity.
7. Conclusion
Based on the analysis of the development status and opportunities of China's construction waste recycling industry, the development potential of construction waste recycling industry is huge under the background of "waste-free city" construction and "double carbon". It is necessary to further sort out and systematically study the industrial chain of construction waste recycling, build a systematic industrial platform for multi-source solid waste collaborative disposal and jointly build and share infrastructure, so as to achieve the systematic goal of industrial structure optimization, smooth whole chain and coordinated development.
Source：https://mp.weixin.qq.com/s/ZMVnW4-ZezGOCzIdlMy49g