Georgios Gaidajis

This study presents the geotechnical evaluation of phosphogypsum, a byproduct of phosphate fertilizer production. The objective is to assess the suitability of phosphogypsum or its mixtures with natural materials as a technically viable and environmentally responsible backfill material for the restoration of closed and abandoned quarries. This study adds to the scarce existing literature on the use of phosphogypsum for quarry reclamation and further investigates the behavior of phosphogypsum mixtures incorporating clay and marble dust. A comprehensive experimental program was conducted to evaluate typical geotechnical properties, i.e., grain size distribution, Atterberg limits, compaction characteristics, permeability, compressibility, and shear strength. The results indicate that phosphogypsum is fine grained, low in plasticity, and exhibits relatively high permeability and compressibility, which limits its application as a deep fill material. The addition of clay increased the liquid and plastic limits but had a limited positive effect on strength and compressibility. In contrast, mixtures with marble dust improved particle gradation, reduced permeability, and enhanced compaction behavior without significantly increasing plasticity or settlements. Notably, the most promising mixture of phosphogypsum with a modest proportion of marble dust demonstrates improved shear strength and reduced hydraulic conductivity, making it suitable for use in the upper layers of quarry fills.

Phoshpogypsum (PG) is an environmentally hazardous industrial by-product of the fertilizer industry with an annual production of 300 Mt, with a utilization rate of only 15%. In this work, we propose a novel use-case for PG. The latter is combined with a commercial-grade paraffin to fabricate composite phase change materials (CPCMs), for thermal energy storage applications. CPCMs are fabricated following a comminution and sintering process. The fabricated materials exhibit a stable latent heat (75 J/g) after 96 cycles (25 to 100 °C), with a maximum average specific heat capacity of 1.54 J/gK at 60% paraffin content. The thermal conductivity is found to be 75% higher than pure paraffin, while the energy storage density is only 14% lower.

The production and utilization of fertilizers are processes with known and noteworthy environmental impacts. Direct greenhouse gas (GHG) emissions and a high contribution to water eutrophication due to the nitrogen (N) and phosphorus (P) derivatives are some of the most crucial impacts derived from the overall life cycle of fertilizer use. The life cycle assessment (LCA) has been reliable and analytical tool for the identification, quantification, and evaluation of potential environmental impacts of fertilizers related to the products, production processes, or activities throughout their lifecycle. In this paper, a gate-to-gate LCA approach was applied in order to identify and evaluate the impacts derived from the production processes of nitrate and compound fertilizers the production industry in Northeastern Greece. The results from this study prove that compound fertilizers have a greater impact compared with nitrate fertilizers, contributing up to 70% of the total production impacts. Furthermore, climate change, freshwater eutrophication, and fossil fuel depletion were identified as the most crucial impact categories. Finally, a comparison with relevant LCA studies was conducted, in order to identify the possibility of a consistency pattern of the fertilizer production impacts in general.

The current paper presents a methodological framework that is able to evaluate the carrying capacity of protected areas where various human activities, apart from recreation and tourism, take place. The proposed framework converts the energy and product consumption into land required to satisfy those needs (Ecological Footprint) and compares them with the current land uses and available land (Biocapacity), in order to calculate carrying capacity. To facilitate the evaluation, an algorithm that calculates the Ecological Footprint, the Biocapacity, and the Carrying Capacity of the protected area under study by introducing 48 inputs was developed. The inputs were related to the evaluation of individual indicators assessing energy and product consumption of human activities such as households, tertiary sector, municipal buildings, public lighting, private and public transportation, and tourism. A new unit is introduced, the “equivalent person,” since the anthropogenic activities within the boundaries of the protected area contribute in a dissimilar way to the total land requirements. The framework is applied, as case study, in the National Park of Eastern Macedonia and Thrace (NPEMT), Greece, with a view to validate and improve its applicability. Within the NPEMT, habitats of significant biodiversity and ecological value are in coexistence with extensive human activities (urban, rural, tourist, light industrial). The study area covers up to approximately 73,000 ha and its population is estimated at about 29,000 people. The Carrying Capacity of the NPEMT according to the current consumption patterns was estimated at 39,193 equivalent residents, which was higher than the current equivalent residents (36,960), indicating a potential for tourism development at the NPEMT. The Ecological Footprint of the NPEMT was estimated at 181,324 Gha or 4.9 Gha/pers_eq, slightly higher than the European mean (4.69 Gha/pers_eq). Among activities, households and private transportation (with approximately 79% and 10%, respectively), among land use, agriculture, livestock, and CO₂ emissions (with approximately 36%, 30%, and 30%, respectively), and among products, beef, fruits/vegetables, and beverages (with approximately 22%, 15%, and 14%, respectively) were the main contributors of the total Ecological Footprint of the NPEMT. The area of the NPEMT is able to meet the needs of its population provided that the consumption patterns will be stable. The results encourage the expansion of tourism development, as the tourism activity within the NPEMT is limited compared to other adjacent domestic destinations.

The aim of this study is to evaluate the existing available methods that can potentially be applied to anthropogenic spatial entities to access their environmental sustainability. The paper offers an overview of existing sustainability assessment methods, discusses their adequacy, and evaluates their efficiency to assess the environmental sustainability of anthropogenic spatial entities. From a list of sixty-one (61) sustainability assessment methods for spatial entities with anthropogenic activities that had been identified and examined, thirteen (13) methods were selected to be assessed based on specific exclusion criteria set. The thirteen methods were further classified into four categories, namely, (1) Indicators/Indices, (2) Resource Availability Assessment, (3) Material and Energy Flow Analysis, and (4) Life-Cycle Assessment, and then these methods were evaluated using specific evaluation criteria. The “Resource Availability Assessment” category, and particularly the “Ecological Footprint” method, was indicated as the most appropriate method to assess the environmental sustainability of anthropogenic spatial entities.

The aim of this study is to strengthen the capacity of mining industries to assess and improve their environmental sustainability performance through the introduction of a relevant framework. Specific assessment categories and respective indicators were selected according to predefined steps. Sustainability threshold values were identified for each indicator to enable the comparison of the facility’s performance with a sustainability reference value. The application of the framework results in the extraction of an Environmental Sustainability Assessment of Mining Industries Index (I_ESAMI). The framework was applied to evaluate a mining facility in Greece, with a view to improve its applicability in parallel. The final score of environmental sustainability for the examined facility was 3.0 points (I_ESAMI = 3.0 points), indicating significant room for improvement where the company should aim to further enhance its sustainability performance.

In the specific study, four flat roof thermal systems namely: the gravel ballasted roof, the green roof, the ventilated roof and the insulated false ceiling, were analysed with the application of the life cycle assessment method (LCA). The analysis of the systems was based on literature references, theoretical calculations and extensive simulation scenarios. Various parameters were evaluated such as cost and time of application, structural loads, maintenance needs and energy efficiency. The study focused on the comparative environmental evaluation of the systems. Results indicated that the ballasted roof exhibited the best environmental performance. Extruded polystyrene and steel parts were the key parameters affecting the environmental performance of the systems. Significant results are also provided regarding the energy reimbursement and technical characteristics. The conclusions of the specific study support the need to identify alternative materials and processes for the formation of the thermal roof system layers and the integration of separation processes and partial recycling in construction activities.

Life-cycle thinking significantly affects the assessment of the environmental performance of a system. In this study, the life-cycle assessment of a multi-Si photovoltaic (PV) module was conducted in order to examine the environmental burden throughout its life cycle and benchmark it with the environmental burden of the identical conventional energy produced with the energy mix of Greece and supplied by the national energy network grid. The results indicated that aluminium, solar glass and the energy consumed during PV assembly significantly affected the environmental performance of the PV module. Non-renewable energy utilisation, global warming and respiratory inorganic emissions were the major impact categories affected by the life cycle of the module examined. Significant questions were raised regarding the distance of the PV installation site from manufacturers and maintenance personnel. Still, the utilisation of the system examined was more efficient than the application of conventional energy sources in terms of environmental performance.

To assess ambient air quality at the wider area of a mining-industrial facility in Chalkidiki, Greece, the particulate matter with an aerodynamic diameter of 10 μm (PM₁₀) and its content in characteristic elements, i.e., As, Cd, Cu, Fe, Mn, Pb, Zn were monitored for a period of three years (2008–2010). Gravimetric air samplers were employed for the particulate matter sampling at three sampling stations located in the immediate vicinity of the industrial facility and at a neighbouring residential site. Monitoring data indicated that the 3-year median PM₁₀ concentrations were 23.3 μg/m³ at the residential site close to the facility and 28.7 μg/m³ at the site within the facility indicating a minimal influence from the industrial activities to the air quality of the neighbouring residential area. Both annual average and median PM₁₀ concentration levels were below the indicative European standards, whereas similar spatial and temporal variation was observed for the PM₁₀ constituents. The average Pb concentrations measured for the three sampling sites were 0.2, 0.146 and 0.174 μg/m³ respectively, well below the indicative limit of 0.5 μg/m³. The quantitative and qualitative comparison of PM₁₀ concentrations and its elemental constituent for the three sampling stations did not indicate any direct influence of the mining-industrial activities to the air quality of the Stratoni residential area.