Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are persistent organic contaminants of concern to human and environmental health. Several literature reviews and laboratory column experiments have been conducted to determine the transport parameters and to describe the fate of PFAS as they migrate in subsurface environments. However, there are very few case studies focusing on contaminated sites with high-resolution field data. Such studies are crucial for the validation of transport simulation models that have been developed from experimental studies, prior to their broader applications. The key purpose of this research was to evaluate lithological separations of PFAS fractions as they are transported in the vadose zone of a historically (1979) contaminated site where Aqueous Film Forming Foam (AFFF) formulations (3M Lightwater™ and Ansulite™) have been used for fire training exercises. Surface and subsurface soils, and groundwater samples were collected across the site and a total of 29 PFAS compounds were selected as target analytes. The results indicated a distinct profile of PFAS concentration with depth at most of the test bores, exhibiting separation of PFAS as transported in vadose zone soils. Perfluorooctanoic acid (PFOA), Perfluorooctane sulfonic acid (PFOS), and Perfluorohexane sulfonic acid (PFHxS) were the predominant compounds detected in the site samples and they have been found in near-surface soils (<3 m) with concentrations declining with depth. The concentration of the 6:2 fluorotelomer sulfonate showed little change with depth in most of the test bore wells. The percentage concentration of each compound relative to the sum of PFAS, and the ratio of PFHxS/PFOS with depth, suggested transformation processes. Despite the relatively high solubility of PFAS, and that the application of AFFF has been ceased for some years at the site, there were still significant concentrations of PFAS adsorbed to the vadose zone soils that acted as ongoing sources of contamination to groundwater.

The rapid increase in construction and demolition waste (C&DW) has emerged as a significant environmental challenge, particularly due to the hazardous substances embodied within the fine residues destined into landfills. The disposal of C&DW in landfills has been widely recognized as a source of leachate, containing toxic contaminants, which pose significant environmental risks. A controlled column leaching experiment was conducted using samples with varying proportions of C&DW, gypsum, and organic content to assess their impact on leachate chemistry. The results indicate that higher C&DW content leads to increased concentrations of heavy metals, such as Pb, Hg, As, Cr, Ni, Cu, Zn, and Co, as well as other metals like Al and Fe, with peak contamination occurring within the first 13–15 weeks. Gypsum presence exacerbates heavy metal solubility by reducing pH, increasing sulfate levels, and promoting metal-sulfate complex formation. Despite remaining within regulatory thresholds, the cumulative concentration of toxic metals over time highlights potential environmental risks, particularly in landfill settings. This study underscores the need for improved C&DW management practices, enhanced waste segregation, and sustainable alternatives to gypsum to mitigate long-term ecological impacts. These findings contribute to a deeper understanding of C&DW leachate dynamics and inform policy recommendations for sustainable waste management in the construction sector.

Purpose: The increasing African population and economic growth leading to urbanisation continues to increase the need to redevelop brownfields as a strategy of encouraging sustainable development of cities, in particular in Ethiopia. However, the adoption of brownfield redevelopment in Ethiopia is at initial stage. Thus, the purpose of this paper is to highlight the framework based on grey-incidence decision-making approach to manage brownfields in African countries by taking Ethiopia as case example. The grey-incidence decision-making model integrates multiple factors such as economic, social, environmental, technical and associated risks and provides an effective decision-making and management tool for environmental practitioners and government agencies. Design/methodology/approach: Questionnaires were used to collect data on terms and definitions of brownfield. The questions were prepared on the basis of currently used definitions developed by a number of developed countries. Moreover, this study utilises a grey-incidence decision-making approach to help in management and decision-making for the implementation of brownfield redevelopment projects (BRPs) in the remediated sites. Findings: Standard definition of brownfield and essential guidelines for brownfield redevelopment is proposed for Ethiopian context. The research findings were tested and verified using literature data and survey from major stakeholders. In addition, the grey-incidence decision-making approach is applied for the evaluation of BRPs in the remediated sites. A framework is proposed to control future brownfields for African countries by taking Ethiopia as a case example. Originality/value: This research stresses the significance of an urban structure to address sustainable development, and the need to consider redevelopment of brownfields and identify the potential for a specific government policy framework. This research provides the best opportunity for Ethiopia by devising an urban land policy and create a strategy to contribute social, economic, financial and environmental benefits. It also provides a foundation to solve environmental issues by involving all major stakeholders, including community citizens, environmentalists and government agencies, and it also serves as guidelines to transform brownfields into Greenfields; and finally, it contributes to achieve the 2030 UN global goals.