Environmental impacts of the utilisation of challenging plastic-containing waste
Khan, Md.Musharof Hussain (2022-12-01)
Väitöskirja
Khan, Md.Musharof Hussain
01.12.2022
Lappeenranta-Lahti University of Technology LUT
Acta Universitatis Lappeenrantaensis
School of Energy Systems
School of Energy Systems, Ympäristötekniikka
Kaikki oikeudet pidätetään.
Julkaisun pysyvä osoite on
https://urn.fi/URN:ISBN:978-952-335-897-3
https://urn.fi/URN:ISBN:978-952-335-897-3
Tiivistelmä
The current economy is primarily based on the concept of a linear economy, which results in negative impacts on the environment, human health, and over-dependency on resources. Shifting towards a circular economy could alleviate the up-growing pressure on the environment, economy, and society and provide benefits to these sectors. Challenging plastic-containing waste is one of the prime examples of the result of the linear economy that has not been adequately addressed due to its heterogeneous and complex nature and improper management.
The primary aim of the dissertation is to analyse and compare the environmental impacts of several types of materials and energy recovery options for challenging plasticcontaining waste and to discover the best possible environmentally friendlier options by using the life cycle assessment (LCA) method. Three objectives were formulated to address this primary aim: (1) to analyse the influence of the material substitution rate on the environmental impacts of the recovery options for challenging plastic-containing waste; (2) to quantify the impact of the energy source on the environmental impacts of the recovery options for challenging plastic-containing waste; and (3) to analyse the environmental impacts of the recovery of challenging plastic-containing waste that can no longer be recycled by mechanical and chemical recycling processes.
Four LCA studies were conducted to investigate the environmental impacts of recovering materials and energy from different treatment processes for challenging plasticcontaining waste. The results obtained from Publications I and II showed that the environmental impacts of the recovery options for challenging plastic-containing waste significantly changed due to the virgin plastic substitution rate. In Publication I, mechanical recycling had higher environmental impacts than chemical recycling because it was assumed that recycled plastic from the mechanical recycling process did not substitute for virgin plastic. However, the sensitivity analysis of Publication I showed that mechanical recycling could have a better environmental impact compared to the chemical recycling process when mechanically recycled plastic substituted 80% or more virgin plastic. The result of Publication I was further supported by Publication II, which showed that mechanical recycling had better environmental impacts than chemical recycling when recycled materials substituted for 100% virgin plastic. In addition to the virgin plastic substitution rate, Publications I, II, and III revealed that the selection of energy sources has a significant impact on the environmental impacts of the recovery options for challenging plastic-containing waste. When thermal and electrical energy was consumed and substituted from an average production mix, the environmental impacts of the recovery options were higher than when the energy was based on renewable sources. Publication IV showed that when the challenging plastic-containing waste has a higher impurity level, and it is no longer possible to recycle, it can be used for recovering energy in cement production, and it could be a better option over energy recovery in waste incineration. However, this process has a higher environmental impact than mechanical and chemical recycling processes.
The recovery of materials and the relevant environmental impacts from mechanical and chemical recycling processes depend primarily on considerations of the virgin plastic substitution rate, separation techniques, and energy consumption from different sources. The studies in this dissertation demonstrate that a single recycling process cannot solve the uprising waste management issues of challenging plastic-containing waste; instead, the solution requires a synchronised utilisation of various recycling processes. This study enables a better understanding of the development of different recovery options for challenging plastic-containing waste and assists in decision making in this area.
The primary aim of the dissertation is to analyse and compare the environmental impacts of several types of materials and energy recovery options for challenging plasticcontaining waste and to discover the best possible environmentally friendlier options by using the life cycle assessment (LCA) method. Three objectives were formulated to address this primary aim: (1) to analyse the influence of the material substitution rate on the environmental impacts of the recovery options for challenging plastic-containing waste; (2) to quantify the impact of the energy source on the environmental impacts of the recovery options for challenging plastic-containing waste; and (3) to analyse the environmental impacts of the recovery of challenging plastic-containing waste that can no longer be recycled by mechanical and chemical recycling processes.
Four LCA studies were conducted to investigate the environmental impacts of recovering materials and energy from different treatment processes for challenging plasticcontaining waste. The results obtained from Publications I and II showed that the environmental impacts of the recovery options for challenging plastic-containing waste significantly changed due to the virgin plastic substitution rate. In Publication I, mechanical recycling had higher environmental impacts than chemical recycling because it was assumed that recycled plastic from the mechanical recycling process did not substitute for virgin plastic. However, the sensitivity analysis of Publication I showed that mechanical recycling could have a better environmental impact compared to the chemical recycling process when mechanically recycled plastic substituted 80% or more virgin plastic. The result of Publication I was further supported by Publication II, which showed that mechanical recycling had better environmental impacts than chemical recycling when recycled materials substituted for 100% virgin plastic. In addition to the virgin plastic substitution rate, Publications I, II, and III revealed that the selection of energy sources has a significant impact on the environmental impacts of the recovery options for challenging plastic-containing waste. When thermal and electrical energy was consumed and substituted from an average production mix, the environmental impacts of the recovery options were higher than when the energy was based on renewable sources. Publication IV showed that when the challenging plastic-containing waste has a higher impurity level, and it is no longer possible to recycle, it can be used for recovering energy in cement production, and it could be a better option over energy recovery in waste incineration. However, this process has a higher environmental impact than mechanical and chemical recycling processes.
The recovery of materials and the relevant environmental impacts from mechanical and chemical recycling processes depend primarily on considerations of the virgin plastic substitution rate, separation techniques, and energy consumption from different sources. The studies in this dissertation demonstrate that a single recycling process cannot solve the uprising waste management issues of challenging plastic-containing waste; instead, the solution requires a synchronised utilisation of various recycling processes. This study enables a better understanding of the development of different recovery options for challenging plastic-containing waste and assists in decision making in this area.
Kokoelmat
- Väitöskirjat [1036]