Possibilities of Management of Fly Ash from Municipal Solid Waste Incineration Plant in Building Industry in the Circular Economy

To improve the condition of the environment and prevent its degradation, global trends have moved from linear to the circular economy. Closing the loop is to protect natural resources, minimize waste, emissions, and pollution. The circular economy assumptions are based mainly on the 3-R: Reduce (minimum use of raw materials); Reuse (maximum reuse of products and components); Recycle (high-quality reuse of raw materials). In the waste management hierarchy, the last place in the circular economy is energy recovery. In the process of incinerating municipal waste, secondary waste is generated. Some of them, like fly ash, are hazardous waste. It includes, among others heavy metals, chlorine, sulphur, and other pollutions, hence it is currently not used as a raw material. The management of fly ash from municipal solid waste incineration plant in the construction industry is a part of sustainable development and the circular economy. Fly ash is a hazardous and heterogeneous waste, therefore it is important to know its physicochemical and construction properties, which are presented in the article. Fly ash has pozzolanic properties, therefore it can be a good binding and building material. For fly ash to be a component of the construction mixture, it is necessary to immobilize pollutants, heavy metals, and some elements so that they do not leach into the environment. For this purpose, the concrete structure and the C-S-H matrix should be compacted. Currently, fly ash is stabilized and stored in underground landfills. They are storage in closed salt, manganese, and potassium mines. However, the volume of post-mining voids is limited, and storage is not part of the circular economy. In addition, some countries do not have their fly ash storage facilities and it has to be exported across borders. This increases the carbon footprint and shortens the product life cycle.