Acid mine drainage (AMD) are a worldwide problem leading to ecological destruction in river basins and the contamination of water sources. AMD are characterized by low pH and high content of heavy metals and sulphates. In order to minimize negative impacts of AMD appropriate treatment techniques has to be chosen. Treatment processes are focused on neutralizing, stabilizing and removing pollutants. From this reason efficient and environmental friendly methods are needed to be developed in order to reduce heavy metals as well as sulphates. Various methods are used for remediation of acid mine drainage, but any of them have been applied under commercial-scale conditions. Their application depends on geochemical, technical, natural, financial, and other factors. The aim of the present work was to interpret the study of biological methods for sulphates removal from AMD out-flowing from the shaft Pech of the deposit Smolmk in Slovak Republic. In the experimental works AMD were used after removal of heavy metals by precipitation and sorption using the synthetic sorbent Slovakite. The base of the studied method for the sulphates elimination was the anaerobic bacterial sulphate reduction using sulphate-reducing bacteria (SRB) genera Desulfovibrio. SRB represent a group of bacteria that uses sulphates as a terminal electron acceptor for their metabolism. These bacteria realize the conversion of sulphate to hydrogen sulphide under anaerobic conditions. For the purposes of experiments a few variants of the selective medium DSM-63 culture media were used in term of the sulphates and sodium lactate contents in the selective medium as well as sulphates in the studied AMD.

The submitted paper deals with the study of combination of chemical and biological-chemical methods for the heavy metals elimination from the acid mine drainage. The experiments were carried out at the laboratory scale using a synthetic solution with similar properties to the real sample of acid mine drainage, originating from the zinc mine located in Tùnel Kingsmill outflow of the Rio Yaulì (district of Yauli - Perù). The successive repetition of the metal precipitations as hydroxides (chemical method) and sulphides (biological-chemical method) at the various acid mine drainage pH was the basis of the examined processes. For the hydrogen sulphide production the sulphate-reducing bacteria of genus Desulfovibrio were used. Results confirmed the precipitation of Fe, As, Al and Mn in the hydroxide form; Cu and Zn in the form of sulphides. For the selective removal of Cu, Zn, Al and Mn the excellent results were received. Selective precipitation of Fe and As was not so successful since the co-precipitation of Fe and As was later determined as a main mechanism of the precipitate forming.

In Slovakia, there are a number of contaminated sites that have occurred due to intensive mining, mineral processing, metallurgical activities, chemical industry, fossil fuel combustion, and industrial agriculture in the past. This paper summarizes the occurrence, chemistry, toxicity, and mineralogy of arsenic species related to soil and water contamination in Slovakia. Four main localities with arsenic exposure were identified. Additionally, magnetically modified carbon biochar (MWchar-Mag) was tested for arsenic removal from a model solution alongside real mine water discharged from the abandoned Hauser adit. For the model aqueous solution, the maximum adsorption capacity was established at 6.2 mg of As per g of MWchar-Mag at natural pH. In the case of mine water with a concentration of arsenic at around 0.2 mg/L, adsorbent dosage, pH influence experiments, and kinetic tests were realized. The results confirmed 100% arsenic removal efficiency at pH~3–7 and extremely fast kinetics.

This paper analyses Saharan dust (SD) from settled precipitation from the episode of its record occurrence in eastern Slovakia at the end of March and early April 2024.The aim is to assess the impact of SD on atmospheric deposition (AD) and particulate matter immissions in the Košice area with the metallurgical industry present. The particles' size and distribution, chemical, and phase composition were analyzed. The methods of laser granulometry, electron microscopy (SEM and EDX), ICP MS, CHNS, and X - ray powder diffraction analysis were used. Saharan dust is polydisperse, with a mean geometric grain diameter of 15.1 μm; the proportion of particles with sizes below 10 and 2.5 μm is 37 and 10.9 %, respectively. The proportion of particles larger than 20 μm is 45 %. The SD sample is polymineralic, with quartz as the dominant component, accompanied by calcite and dolomite to a lesser extent. Additionally, feldspars, micas, kaolinite, and other common phyllosilicates and rock - forming minerals were confirmed. The main components of the analyzed EDX spectra, apart from oxygen and silicon, also included elements such as Al, Ca, K, Fe, Mg, and Na. The SD sample contained a relatively high carbon content (9.6%). Based on their occurrence in the spectra, the elements were present in the following order: O, Si, Al, Fe, Ca, Mg, K, C, Ti, Na, Cu, P, Mn, Nb, Ba, Br, Cr, and Pt. The chemical composition of SD is very similar to the average composition of the Earth's crust. Compared to the concentrations of the monitored elements in AD, the SD sample exhibited higher levels of aluminum and, to some extent, calcium and magnesium. In the case of other elements, their concentrations in AD from an area in the metallurgical industry were significantly higher than in Saharan dust. The estimated contribution of Saharan dust to the atmospheric deposition of the solid fraction in the study area ranges from 4.6% to 22%, depending on the emission loading rate.

In this work a comparative study of manganese removal from pre-treated acid mine drainage is described. Manganese removal by three ways was realized. At the first method sodium hydroxide was added to raise pH of processed AMD to the 9.5 to promote the abiotic oxidation of soluble divalent species to insoluble form of manganese. Potassium permanganate was used at pH near neutrality for elimination of manganese from AMD by oxidative precipitation in the second process. A third method, as electrowinning, was applied, finalized to the anodic Mn recovery under MnO 2 form. The results showed that the three methods are effective and manganese were removed from acid mine drainage for values that comply with environmental requirements. However, when sodium hydroxide was used as reagent, coprecipitation of manganese and magne - sium present in AMD was observed. In the second experiment enhanced selectivity of the process and purity of obtained precipitates were achieved. In the process of electrowinning – over 95% of Mn removal under MnO 2 form, with a high degree of purity (about 99%) was attained.

Acid Mine Drainage (AMD) is one of the significant environmental and financial liabilities of the mining industry. Currently active mines, as well as mines that have been out of production for years, produce acidic waters with high concentration of sulphates and heavy metals. Treatment methods used to mitigate impact of AMD on the environment are focused on neutralizing, stabilizing and removing pollutants through various physical, chemical and biological processes. This paper reports the results of anorganic pollutants removal from AMD using sulphate reducing bacteria (SRB). Hydrogen sulphide produced by SRB for recovery of Cu and Zn has been used in the course of selective sequential precipitation process (SSP). In the next stage sulphates were removed from AMD by the biological anaerobic reduction. Thus, by this method removing of metals and sulphates has been achieved in successive discrete steps. The experiments were performed at laboratory condition using water collected from the site of the AMD outflow at the shaft Pech from the enclosed and flooded Smolnik sulphidic deposit (Slovakia).