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The global energy demand is growing substantially. Clean and secure energy supply is a must for our civilization's sustainable development. Solar and wind energy is growing fast and can contribute significantly to meet the goals set by many countries to reduce greenhouse gas emissions. A deep and wide investigation of the environmental impact of solar and wind energy is important before any solar or wind plants' construction is made. In this study, the literature is reviewed to summarize the environmental impact of solar and wind energy systems in terms of the following factors; land use, water consumption, impact on biodiversity, visual and noise effects, health issues, and impact on micro climate. Although the benefits of solar and wind energy are obvious and great, negative perception of these technologies can inhibit their wide penetration in some regions. This review paper includes a critical and an inclusive analysis of solar and wind energy’s environmental impact and may serve as an important tool to conduct a proper environmental impact assessment. This critical analysis may serve also as a tool for developers, policy, and decision-when planning future solar and wind farms.

The European Union is currently in the process of transformation toward a circular economy model in which different areas of activity should be integrated for more efficient management of raw materials and waste. The wastewater sector has a great potential in this regard and therefore is an important element of the transformation process to the circular economy model. The targets of the circular economy policy framework such as resource recovery are tightly connected with the wastewater treatment processes and sewage sludge management. With this in view, the present study aims to review existing indicators on resource recovery that can enable efficient monitoring of the sustainable and circular solutions implemented in the wastewater sector. Within the reviewed indicators, most of them were focused on technological aspects of resource recovery processes such as nutrient removal efficiency, sewage sludge processing methods and environmental aspects as the pollutant share in the sewage sludge or its ashes. Moreover, other wide-scope indicators such as the wastewater service coverage or the production of bio-based fertilizers and hydrochar within the wastewater sector were analyzed. The results were used for the development of recommendations for improving the resources recovery monitoring framework in the wastewater sector and a proposal of a circularity indicator for a wastewater treatment plant highlighting new challenges for further researches and wastewater professionals.

The inhibition of undesirable nitrite oxidizing bacteria (NOB) and desirable ammonium oxidizing bacteria (AOB) by free ammonia (FA) and free nitrous acid (FNA) in partial nitritation (PN) is crucially affected by the biomass growth mode (suspended sludge, biofilm, encapsulation). But, the limitations of these modes towards less concentrated reject waters (≤600 mg-N L-1) are unclear. Therefore, this work compares the start-up and stability of three PN sequencing batch reactors (SBRs) with biomass grown in one of the three modes: suspended sludge, biofilm and biomass encapsulated in polyvinyl alcohol (PVA) pellets. The SBRs were operated at 15°C with influent total ammonium nitrogen (TAN) concentrations of 75-600 mg-TAN L-1. PN start-up was twice as fast in the biofilm and encapsulated biomass SBRs than in the suspended sludge SBR. After start-up, PN in the biofilm and suspended sludge SBRs was stable at 150-600 mg-TAN L-1. But, at 75 mg-TAN L-1, full nitrification gradually developed. In the encapsulated biomass SBR, full nitrification occurred even at 600 mg-TAN L-1, showing that NOB in this set-up can adapt even to 4.3 mg-FA L-1 and 0.27 mg-FNA L-1. Thus, PN in the biofilm was best for the treatment of an influent containing 150-600 mg-TAN L-1.

The paper presents the comparative analysis of the amount of waste generated in Ukraine and European countries (except for radioactive waste) based on the official EU and Ukrainian statistical data. The data on waste generation are compiled according to the following classification: by economic activity and household, waste category, grades of hazard, and regions. In Ukraine, 352.3 million tons of waste was generated in 2018. By 2018, almost 13 billion tons of waste had been accumulated at the managed dumpsites, including about 12 million tons of hazardous and over 200 million tons of household waste. In the European Union, 2.6 billion tons of waste was generated in 2018. Over 70% of it was generated by 10 countries: Germany, France, England, Poland, Romania, Italy, Sweden, the Netherlands, Spain and Finland. By economic activity, the largest amounts of waste in Ukraine are generated by the mineral extraction and processing industry, the smallest – from water treatment and construction. In the EU countries, these values are somewhat different. For example, in Germany and France, the largest amounts of waste are generated from construction and manufacturing, the smallest – from agriculture, forestry and fishery. By waste category, the waste generated both in the EU countries and in Ukraine is mineral and solid waste. In Ukraine, the largest amounts of waste are produced and accumulated in the Dnipropetrovsk, Donetsk and Zaporizhzhia regions which accommodate large enterprises for extraction and mineral processing of iron and manganese ores, titanium-zirconium placers, coal, dolomite, and metallurgical limestone, as well as metallurgical and ferroalloy plants.

The steel industry is the largest consumer of energy in the world among industrial sectors. It is generally acknowledged that energy and environment are intimately related. Steel production is an energy intensive process that has a significant environmental impact. This paper reviews the progress made on energy consumption, carbon dioxide emissions and water consumption in the steel industry worldwide. The reduction in the availability of fresh water resources combined with the effects of global warming and climate change have increased pressure on industries, especially steel, to reduce its overall pollution, and specifically its water and carbon footprint. The implications of these effects on the value chain is discussed in this review. The contribution of new emerging technologies of iron and steelmaking is also reviewed. Finally, the important issues that contribute to define a sustainable industrial activity such as the recycling of steel and of by-products of steel production are studied. The history of steel industry is full of lessons, one of which is the need to keep the dreams alive. There are indeed expectations to solve problems created by technical progress.

Abstract In addition to CO2 released by the combustion of fossil fuel and leading to climate change, large steelworks emit pollutants that have other environmental impacts. ArcelorMittal Gent, an integrated steelwork producing ca. 5 × 106 tons of steel per year, not only decreased its specific energy consumption and CO2-emissions, but also reduced the environmental impact of its other emissions. This is illustrated by means of the evolution of 6 partial eco-efficiency indicators for the impact categories acidification, photo-oxidant formation, human toxicity, freshwater aquatic ecotoxicity, eutrophication and water use. The partial eco-efficiency indicators are eco-intensities, defined as the environmental impact in the respective impact category, divided by the amount of liquid steel produced. In the period 1995 – 2005 these indicators decreased by 45, 4, 52, 9, 11 and 33% respectively, whereas the steel production increased by 17%. The net impact of discharges of wastewater is negligible for human toxicity and is negative (concentrations lower than in the canal water used) for freshwater aquatic toxicity and eutrophication. For acidification, human toxicity (only emissions to air) and water use, the decoupling between environmental impact and production was absolute; for photo-oxidant formation, freshwater aquatic ecotoxicity (only emissions to air) and eutrophication, it was relative.

Power plant or cement kiln co-incineration are important disposal routes for the large amounts of waste activated sludge (WAS) which are generated annually. The presence of significant amounts of heavy metals in the sludge however poses serious problems since they are partly emitted with the flue gases (and collected in the flue gas dedusting) and partly incorporated in the ashes of the incinerator: in both cases, the disposal or reuse of the fly ash and bottom ashes can be jeopardized since subsequent leaching in landfill disposal can occur, or their "pozzolanic" incorporation in cement cannot be applied. The present paper studies some physicochemical methods for reducing the heavy metal content of WAS. The used techniques include acid and alkaline thermal hydrolysis and Fenton's peroxidation. By degrading the extracellular polymeric substances, binding sites for a large amount of heavy metals, the latter are released into the sludge water. The behaviour of several heavy metals (Cd, Cr, Cu, Hg, Pb, Ni, Zn) was assessed in laboratory tests. Results of these show a significant reduction of most heavy metals.

In DRC, hospital waste correspond to a mixture of the waste similar to household waste (DAOM) and waste of Infectious clinical activities (HCW). As part related to hospital hygiene, our study focuses on the impact of clinical waste in the workplace and the environment.For the workstation, on 20 selected people, more than 70% suffered from chest tightness, organic dust syndrome, dryness of the throat and nose, fungi and actinomycetes. About 40% have suffered from gastrointestinal disorders in the handling of hospital waste (from collection to treatment / disposal).From an environmental perspective, the physicochemical characterization of the outgoing storm water litter deposits from four selected hospitals (CUK, HGRK, HGRN, and HGK) show high levels for most of the parameters studied. For the first campaign carried out in 2006, the ratio of BOD5 / COD is 0.08 leachate. Based on available data, the pollution load is composed of chloride (5529 mg / l), COD (890 mg / l) and Cd (20 1 g / l). The electrical conductivity is 25,80 µS cm-1, the pH is basic (9 07) and the average is T ° (27 03° C). For the 2011 campaign, the ratio of BOD5/ COD has a higher value of 0.46; the chloride concentration was 177.17 mg / l and the MEST reach the value of 231.40 mg / l. The value of AOX concentration is 0.89 mg / l.These results indicate the existence of toxic substances in the leachate that may impact on the environment. This finding is reinforced by the analyzes in the river waters that receive leachate. En RDC, les déchets hospitaliers correspondent à un mélange des déchets assimilés aux ordures ménagères (DAOM) et des déchets d’activités de soins à risques infectieux(DASRI). Dans le cadre lié à l’hygiène hospitalière, notre étude s’intéresse à l’impact de ces déchets hospitaliers sur le poste de travail et l’environnement.Pour le poste de travail, sur 20 personnes choisies, plus de 70 % ont souffert de la sensation d’oppression thoracique, du syndrome de poussières organiques, de la sécheresse de la gorge et du nez, des moisissures et des actinomycètes. Environ 40 % ont souffert d’affections gastro-intestinales lors de la manipulation des déchets hospitaliers (de la collecte au traitement/élimination).Du point de vue environnemental, la caractérisation physico-chimique des eaux de ruissellement sortant des dépôts de déchets sauvages des quatre hôpitaux choisis (CUK, HGRK, HGRN, HGK)1 montrent des concentrations élevées pour la plupart des paramètres étudiés. Pour la première campagne réalisée réalisé en 2006, le rapport DBO5/DCO est de 0,08 pour les lixiviats. Sur la base des données disponibles, la charge polluante est composée des chlorures (5529 mg/l), de la DCO (890 mg/l) et du Cd (20,1 µg/l). La conductivité électrique est de 25,80 µS/cm-1, le pH est basique (9,07) et la T° est moyenne (27,03 °C). Pour la campagne de 2010, le rapport DBO5/DCO a une valeur plus élevée de 0,46 ; la concentration en chlorures est de 177,17 mg/l et les MEST atteignent la valeur de 231,40 mg/l. La valeur de la concentration en AOX est de 0,89 mg/l. Ces résultats indiquent l’existence de substances toxiques dans ces lixiviats qui peuvent avoir un impact sur l’environnement. Cette constatation est consolidée par les analyses effectuées dans les eaux de rivière qui réceptionnent les lixiviats.

Five different pre-treatments were investigated to enhance the solubilisation and anaerobic biodegradability of kitchen waste (KW) in thermophilic batch and continuous tests. In the batch solubilisation tests, the highest and the lowest solubilisation efficiency were achieved with the thermo-acid and the pressure-depressure pre-treatments, respectively. However, in the batch biodegradability tests, the highest cumulative biogas production was obtained with the pressure-depressure method. In the continuous tests, the best performance in terms of an acceptable biogas production efficiency of 60% and stable in-reactor CODs and VFA concentrations corresponded to the pressure-depressure reactor, followed by freeze-thaw, acid, thermo-acid, thermo and control. The maximum OLR (5 g COD L(-1) d(-1)) applied in the pressure-depressure and freeze-thaw reactors almost doubled the control reactor. From the overall analysis, the freeze-thaw pre-treatment was the most profitable process with a net potential profit of around 11.5 € ton(-1) KW.

Few studies focus on the co-valorization of river dredging sediments (DS) and residual waste glass (RWG) in alkali-activated binders. This study investigates the use of DS as an aluminosilicate source by substituting a natural resource (metakaolin (MK)), while using RWG as an activator (sodium silicate source). Suitable treatments are selected to increase the potential reactivity of each residue. The DS is thermally treated at 750 °C to promote limestone and aluminosilicate clays’ activation. The RWG (amorphous, rich in silicon, and containing sodium) is used as an alkaline activator after treatment in 10 M NaOH. Structural monitoring using nuclear magnetic resonance (29NMR and 27NMR), X-ray diffraction, and leaching is conducted to achieve processing optimization. In the second stage, mortars were prepared and characterized by determining compressive strength, water absorption, mercury porosimetry and Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS). Results obtained show the great advantage of combining RWG and DS in an alkali-activation binder. The treated RWG offers advantages when used as sodium silicate activating solution, while the substitution of MK by calcined sediments (DS-750 °C) at 10%, 20%, and 30% leads to improvements in the properties of the matrix such as an increase in compressive strength and a refinement and reduction of the pore size within the matrix.