Potentially Toxic Elements’ Contamination of Soils Affected by Mining Activities in the Portuguese Sector of the Iberian Pyrite Belt and Optional Remediation Actions: A Review

Both sectors of the Iberian Pyrite Belt, Portuguese and Spanish, have been exploited since ancient times, but more intensively during and after the second half of the 19th century. Large volumes of polymetallic sulfide ore were extracted in open pits or in underground works, processed without environmental concerns, and the generated waste rocks and tailings were simply deposited in the area. Many of these mining sites were abandoned for years under the action of erosive agents, leading to the spread of trace elements and the contamination of soils, waters and sediments. Some of these mine sites have been submitted to rehabilitation actions, mostly using constructive techniques to dig and contain the contaminated tailings and other waste materials, but the remaining soil still needs to be treated with the best available techniques to recover its ecosystem functions. Besides the degraded physical structure and poor nutritional status of these soils, they have common characteristics, as a consequence of the pyrite oxidation and acid drainage produced, such as a high concentration of trace elements and low pH, which must be considered in the remediation plans. This manuscript aims to review the results from studies which have already covered these topics in the Iberian Pyrite Belt, especially in its Portuguese sector, considering: (i) soils’ physicochemical characteristics; (ii) potentially toxic trace elements’ concentration; and (iii) sustainable remediation technologies to cope with this type of soil contamination. Phytostabilization, after the amelioration of the soil’s properties with organic and inorganic amendments, was investigated at the lab and field scale by several authors, and their results were also considered.

Mapping Bauxite Mining Residues Using Remote Sensing Techniques

Bauxite residuals from abandoned mining sites are both an environmental challenge and a possible source of secondary raw materials. Processing of multispectral and hyperspectral images with the best available techniques can help to produce multiscale spatial maps of elements inside and around the mining sites. The authors propose a procedure for mapping elements concentration using multiple data sets at different scales and resolutions. A comparison between multispectral Sentinel-2 images and hyperspectral PRISMA processing is performed over some case studies of bauxite residues in the Mediterranean area. Specifically, a case study from Italy is composed regarding artificial canyons created by past artisanal mining activities and by stockpiles of extracted bauxite. Hyperspectral punctual measurements (spectroradiometer surveys) were taken in various zones of the bauxite site, where infield topsoil samples were also taken for X-ray fluorescence chemical analysis. Final concentration maps were estimated by performing geostatistical techniques.

Modeling of Energy Consumption and Reduction of Pollutant Emissions in a Walking Beam Furnace Using the Expert Method—Case Study

This paper presents an algorithm for modeling electricity and natural gas consumption in a walking furnace with the use of artificial intelligence and simulation methods, depending on the length of the rolling campaign and the established rolling program. This algorithm is the basis for the development of a proposal for a set of minimum requirements characterizing the Best Available Techniques (BAT) for beam furnaces intended for hot rolling, taking into account the requirements set out in national regulations and the recommendations described in the BREF reference documents. This information should be taken into account when drawing up an application for an integrated permit, as well as when setting emission limit values. Based on the constructed algorithm, it was shown that depending on their type and technical specification, the analyzed projects will offer measurable economic benefits in the form of reducing the amount of energy consumed by 1,076,400 kWh during the implementation of 50 rolling campaigns to reduce gas by 14,625 GJ and environmental benefits in the form of reduction of pollutant emissions into the atmosphere 80–360 g/Mg. The constructed algorithm was validated in the Dosimis-3 program, based on a discrete event-driven simulation. Thanks to this representation of the model, its user can interactively participate in changes that take place in the model and thus evaluate its behavior. The model, verified in real conditions, can be the basic source of information for making effective operational technological decisions related to the preparation of production at the rolling mill as part of planning and long-term activities.

Reduction of Ammonia Emissions from Laying Hen Manure in a Closed Composting Process Using Gas-Permeable Membrane Technology

Nitrogen losses during composting processes lead to emissions problems and reduce the compost fertilizer value. Gas-permeable membranes (GPM) are a promising approach to address the challenge of reducing nitrogen losses in composting processes. This study investigated the applicability of two GPM membrane systems to recover N released during the closed composting process of laying hen manure. The ammonia (NH3) capture process was performed using two different systems over a period of 44 days: the first system (S1) consisted of 120 m of an expanded polytetrafluoroethylene (ePTFE) membrane installed inside a 3.7 m3 portable, closed aerobic composter with forced ventilation; the second system (S2) consisted of 474 m of an ePTFE membrane placed inside as an external module designed for NH3 capture, connected to a closed aerobic composter through a pipe. In both cases, a 1 N H2SO4 acidic NH3 capture solution was circulated inside the membranes at a flow rate of 2.1 L·h−1. The amount of total ammonia nitrogen (TAN) recovered was similar in the two systems (0.61 kg in S1 and 0.65 kg in S2) due to the chosen membrane surface areas, but the TAN recovery rate was six times higher in system S1 (6.9 g TAN·m−2·day−1) than in system S2 (1.9 g TAN·m−2·day−1) due to the presence of a higher NH3 concentration in the air in contact with the membrane. Given that the NH3 concentration in the atmosphere of the membrane compartment directly influences the NH3 capture, better performance of the GPM recovery system may be attained by installing it directly inside the closed aerobic composters. Regardless of the chosen configuration, this technology allows N recovery as a stable and concentrated 1.4% N ammonium salt solution, which can be used for fertigation. The presented GPM systems may be used in community composting systems with low volumes of waste to be treated or in livestock facilities that have implemented best available techniques such as solid–liquid separation or anaerobic digestion, provided that the use of GPM technology in combination with these techniques also contributes to odor mitigation and improves biogas yields.

Sustainable Energy Management Benchmark at Wastewater Treatment Plant

Urban wastewater effluents bring large amounts of nutrients, organic matter, and organic microcontaminants into freshwater ecosystems. Ensuring the quality of wastewater treatment (WWT) is one of the main challenges facing the management of wastewater treatment plants (WWTPs). However, achievement of high-quality standards leads towards significant energy consumption: usually the more intensive WWT process requires additional energies. Energy efficiency at WWTP is actual mainstream on the current sustainable development agenda. The WWTP processes and methods can be considered from the standpoint of material and energy flows according to circular economy paradigm, which offers great possibilities to reuse waste originating from WWT in order to receive renewable energy. The correlation between energy and quality issues to evaluate WWTP efficiency is of a great scientific and practical interest. The main goal of the paper is to check the dependency between these two main issues in WWTP management—WWT quality and energy efficiency—and to determine possible limits of such relation. The municipal sewerage system of Ekaterinburg, Russia was studied within this paper. The total length of centralized sewerage system in Ekaterinburg is over 1500 km of pipes within two main sewerage basins: northern and southern. The methodological framework for the current research consisted of three steps: (i) WWT quality evaluation, (ii) energy efficiency evaluation, and (iii) WWTP Quality/Energy (Q/E) efficiency dependency matrix. For the purpose of research, authors investigated the 2015–2018 period. The results showed that the outputs correlate with the technical conditions of WWTPs and the implementation of the best available techniques (BATs): most of the northern WWTP values are referred to the green zone (good rank), while the southern WWTP values are situated generally in the orange zone (unsatisfactory rank). The proposed methodological approach for Q/E dependency of WWT process creates a strong but simple tool for managers to evaluate the current success of the operation of WWTP and progress towards circular economy practices implementation.

Criterial approach to substantiation of the best available techniques for engineering protection against hazardous techno-natural processes

Прогнозирование мероприятий и строительства сооружений по инженерной защите от опасных процессов имеет целый ряд специфических особенностей, которые следует иметь в виду при разработке методологии обоснования наилучших доступных технологий. Математический аппарат, позволяющий обосновать выбор технологии инженерной защиты от опасных техноприродных процессов, которую можно отнести к наилучшим доступным технологиям, находится в стадии разработки. Представлен один из подходов, который позволяет на основе количественных оценок обосновывать выбор варианта инженерной защиты от опасных техноприродных процессов. За основу такого подхода принят экспертно-аналитический метод оценки риска от опасных природно-техногенных процессов, который в последние годы получил широкое развитие. Предложен математический аппарат, позволяющий обоснованно подходить к выбору наилучшей доступной технологии инженерной защиты от опасных техноприродных процессов с учетом возможностей собственника, его положения в текущей ситуации и перспектив развития. Prediction of measures and construction of facilities for engineering protection from hazardous processes has a number of specific features that should be borne in mind while developing a method for substantiating the best available techniques. The mathematical tools that provide for substantiating the choice of a technology for engineering protection from hazardous techno-natural processes, that can be assigned to the best available techniques, are under development. One of the approaches is presented that allows, on the basis of quantitative assessments, to substantiate the choice of an option of engineering protection against hazardous techno-natural processes. This approach is based on the expert-analytical method for assessing the risk from hazardous natural-technogenic processes that has been widely used in recent years. Mathematical tools have been proposed that provide for reasonably approaching the choice of the best available technique for engineering protection against hazardous techno-natural processes, taking into account the capabilities of the owner, his position in the current situation and development prospects.