Options for increased low-risk recycling of building products
Materials containing chemical substances with hazardous properties may, under certain conditions generate undesirable emissions of such chemicals during the use phase, as well as during recycling and other types of waste treatment. Since recycling of materials is a key element in the movement towards a circular economy it is crucial that the recycling is conducted in way that minimizes the risk associated with exposure to hazardous chemicals. Construction and demolition waste is a category of products where large volumes of waste are managed. In addition, new construction is very resource- and energy-intensive, which is why increased recycling is desirable from a waste, energy and resource perspective. Meanwhile many of the older building products which are now appearing as waste due to demolition and re-construction, contain potentially harmful substances such as various plasticizers, flame retardants, anti-corrosion and waterproofing additives, etc. Chemicals which have been phased-out from new materials may thus remain in the technosphere due to recycling of older materials. The EU target for recycling of construction and demolition waste is set to 70 percent by the year 2020 and development of reliable procedures for waste management, recycling and risk assessment for this product group are desirable.
Based on current knowledge on recycling methods for construction goods and chemical contents we have specifically studied four building product categories: PVC floor, plaster waste, flat glass and EPS boards which were selected based on a set of selected criteria. Opportunities and obstacles for increased recycling were highlighted for each product category. Specific attention was also given to the demolition process, as it precedes recycling and reuse of any type of construction material. The following aspects were studied: recyclability with current methods, pre-treatment requirements to guarantee safe materials, the possibility to carry out risk assessments with regard to hazardous substances and use area as well as recyclability for other purposes than the products’ original function. The study was mainly carried out through literature studies and interviews/visits with relevant actors.
Out of the four product categories the largest potential for climate savings was estimated to arise from increased recycling of EPS, a material group with low content of hazardous chemicals (in Sweden and depending on the production year). Although the environmental burdens for the other product groups are lower in comparison to that of EPS, increasing recycling for these products would still carry with it significant climate savings. For product groups where recycling techniques and infrastructure are already in place i.e. for plaster and glass, increasing recycling rates could be achieved with relatively little effort. Increased selective demolition and on-site sorting of construction and demolition waste is of great importance to enable an increase of the recycling of building products, and also to better control the occurrence and flow of chemicals throughout the product lifetime and through waste and recycling stages. This is especially true for building products that already have a functioning recycling process with no significant problems regarding hazardous substances e.g. plaster boards and flat glass. Through selective demolition, it is possible to increase recycling rates in a relatively short time. However, even though selective demolition is often a requirement from ordering clients in demolition purchasing involving actors within the public sector, follow-ups are rare and most likely selective demolition does not occur to sufficient extent. The main obstacle to increased selective demolition is the lack of incentive due to the high cost compared to incineration of mixed fractions since the value of the sorted material is not sufficient to compete with conventional treatment. Much larger volumes of waste are needed for the value to be sufficient in relation to transportation costs (true for e.g. plastic). Lack of spacefor containers is also an obstacle. Therefore selective demolition is more common on larger demolition sites. Economic instruments need to be implemented to increase the application of selective demolition.
The results from the project showed that hazardous chemicals are not the main obstacle to increased recycling of building products, rather it has to do with costs and access to recycling facilities. Thus economic instruments and improved logistics and infrastructure may promote increased recycling.