Global exponential increase in levels of Photovoltaic (PV) module waste is an increasing concern. The purpose of this study is to investigate if there is energy value in the polymers contained within first-generation crystalline silicon (c-Si) PV modules to help contribute positively to recycling rates and the circular economy. One such thermochemical conversion method that appeals to this application is pyrolysis. As c-Si PV modules are made up of glass, metal, semiconductor and polymer layers; pyrolysis has potential not to promote chemical oxidation of any of these layers to help aid delamination and subsequently, recovery. Herein, we analysed both used polymers taken from a deconstructed used PV module and virgin-grade polymers prior to manufacture to determine if any properties or thermal behaviours had changed. The calorific values of the used and virgin-grade Ethylene vinyl acetate (EVA) encapsulant were found to be high, unchanged and comparable to that of biodiesel at 39.51 and 39.87 MJ.Kg⁻¹, respectively. This result signifies that there is energy value within used modules. As such, this study has assessed the pyrolysis behaviour of PV cells and has indicated the energy recovery potential within the used polymers found in c-Si PV modules.

Poor storage of industrial wastes has been a cause of land contamination issues. These wastes or by-products have the potential to be used as secondary raw materials in construction, promoting the concept of a circular economy that will avoid land contamination. Here we evaluate radiological environmental impacts when wastes that contain elevated levels of naturally occurring radionuclides (NORs) such as red mud, fly ash and ground granulated blast furnace slag are made into 'green cements' such as geopolymers or alkali-activated materials (AAMs). During the study, three AAM concrete and mortar series with various mixing ratios were prepared and investigated. The NOR content, I-Index, radon emanation and exhalation of the precursor waste materials and their cement products were measured and calculated and the strength of the cement products was compared. The emanation and the exhalation properties were calculated for the final products, weighing the data of the components as a function of their mixing ratio. The I-index alone suggested that the AAMs would be suitable products. AAMs containing ground granulated blast furnace slag exhibited the lowest radon exhalation and higher compressive strength, while the fly ash and red mud AAMs had increased final radon exhalation. In the case of fly ash, alkaline activation of fly ash dramatically increased the radon exhalation; the highest measured fly ash exhalation was 1.49 times of the theoretically calculated exhalation value. This highlights the increased risk of using fly ash as a component in AAMs and the need to carry out testing on the final products as well as individual secondary raw materials.

Increasing urbanisation has a direct impact on soil quality, resulting in elevated concentrations of potentially toxic elements (PTEs) in soils. This research aims to assess if soil PTE concentrations can be used as an 'urbanisation tracer' by investigating geogenic and anthropogenic source contributions and controls, and considering PTE enrichment across historical urban development zones. The UK cities of Belfast and Sheffield are chosen as study areas, where available shallow and deep concentrations of PTEs in soil are compared to identify geogenic and anthropogenic contributions to PTEs. Cluster analysis and principal component analysis are used to elucidate the main controls over PTE concentrations. Pollution indices indicate that different periods of historical development are linked to enrichment of different PTEs. Urban subdomains are identified and background values calculated using various methodologies and compared to generic site assessment criteria. Exceedances for a number of the PTEs considered suggest a potential human health risk could be posed across subdomains of both Belfast and Sheffield. This research suggests that airborne diffuse contamination from often historical sources such as traffic, domestic combustion and industrial processes contribute greatly to soil contamination within urban environments. The relationship between historical development and differing PTEs is a novel finding, suggesting that PTEs have the potential for use as 'urbanisation tracers'. The investigative methodology employed has potential applications for decision makers, urban planners, regulators and developers of urban areas.

As the global cumulative installation of solar photovoltaic (PV) devices grows every year, a proportionate number of waste PV modules arises because of their limited lifespan. It is estimated that by 2050, there will be approximately 60–78 million tonnes of PV waste (Farrell, C.; Osman, A. I.; Zhang, X. et al. Sci Rep.2019, 9, 5267). These modules are bound in a strong encapsulated laminate that is prone to imminent degradation. Subsequently, a form of treatment is required to remove a problematic polymeric material such as the encapsulant poly(ethylene-co-vinyl acetate) (EVA) in order to recycle. Pyrolysis is an ideal option that facilitates clean delamination by removing the polymer fraction, and it does not promote chemical oxidation to any of the constituents left behind after pyrolysis. To date, there are limited studies on the pyrolysis of EVA found in PV modules, resulting in significant gaps in the knowledge of pyrolysis kinetic parameters. This work aims to investigate the pyrolysis reaction kinetics concerning the EVA encapsulant found in end-of-life (EoL) crystalline silicon (c-Si) PV modules. The thermoanalytical technique employed was thermogravimetric analysis, which was carried out at 0.5, 1, 2, 4, and 5 °C min^–1 to ensure accuracy and high resolution while analyzing the kinetics. The kinetic triplet was determined and reported for the first time using the Advanced Kinetics and Technology Solutions (AKTS) Thermokinetics software. The main kinetic modeling method employed was the Friedman differential isoconversional method. Other conventional kinetic modeling approaches were also used, such as the integral (Ozawa) and ASTM-E698 methods for comparison of apparent activation energy. It was observed that the activation energy values for each method were 167.66–260.00, 259.70, and 167.00–252.65 kJ mol^–1 for EVA pyrolysis. Additionally, isothermal, nonisothermal, and step-based predictions were reported for the first time using the thermokinetics package. Furthermore, pyrolysis of EVA can have a triple role in the successful delamination of PV modules, recovery of additional constituents, and aiding of waste management of this problematic polymer.

The simulation-optimisation models of groundwater and contaminant transport can be a powerful tool in the management of groundwater resources and remediation design. In this study, using Multiquadratic Radial Basis Function (MRBF) a coupled groundwater flow and reactive transport of contaminant and oxidant was developed in the framework of the Meshfree method. The parameter analysis has determined the optimum shape parameter (0.97), and the results of the model were compared with a physical sandbox model which were in good agreement. The genetic algorithm approach was used to find the optimum design of the remediation using permanganate as an oxidant. To find the optimum design we considered two objectives and two constraints. The results revealed that the breakthrough of contaminant to the downstream area of interest and the concentration of the contaminant in this area is reduced significantly with optimisation.