Effect of Water Treatment on the Chemical Composition of Drinking Water: A Case of Lovozero, Murmansk Region, Russia

The surface waters in Russia’s Murmansk Region used for public water supply are exposed to the negative impact of dust particles carried from the storage facilities for mining waste. For example, lanthanides and other rare metals enter the surface waters in Lovozero District from the tailings storage facilities (TSFs) of the Lovozero Concentrator, which requires thorough water treatment of drinking water. Using the monitoring data of the natural water of the Virma River and of the tap water in the residential community of Lovozero, Murmansk Region, and with the help of physical and chemical modeling (in the software suite Selector), we examined the effect of reagents used in water treatment on water chemistry. It was shown that the use of aluminum polyoxydichloride coagulant can lead to an increase in the concentration of aluminum and chlorine in water, a change in pH and Eh values. The use of liquid chlorine leads to a decrease in pH values and a change in the concentration of HCO3−, which entails a change in the forms of migration of calcium and lanthanides in solution. The composition of the precipitated phases changed, which indicates a change in the water chemistry, demonstrating that the applied water treatment technology adopted in Lovozero fails to improve water quality. It was shown that replacing liquid chlorine (a hazardous reagent) with NaOCl optimized the water treatment process, eliminating the need to stabilize the pH by adding sodium. Physical and chemical modeling was found to be useful for studying and optimizing water treatment processes

The speciation of chemical elements in water and their possible impact on human health

The speciation of chemical elements in groundwaters of Apatity Kirovsky district may affect their bioavailability and toxicity. A complete hydrochemical analysis showed measurable concentrations of uranium, molybdenum, silver, barium, nickel, vanadium, aluminum, and lead, which contributed to a growing database of the chemical compositions of groundwater. Physical and chemical models showed that the vital elements calcium, sodium, potassium, magnesium and sulfate ion are in chemical forms that are favorable for human health (Ca2+, Na+, K+, Mg2+, SO42-). Forms of migration of carcinogenic or toxic elements (nickel, barium, vanadium, strontium, aluminum, lead) are among the most toxic (Ni2+, Ba2+, Sr2+) and remain so at the temperatures studied +3, +25, +37°C. One of the most insidious effects of inorganic compounds of lead, barium and strontium is the ability to replace calcium in bones isomorphically, nickel in the form of free ions (Ni2+) is 2 times more toxic than its complex compounds with inorganic and organic ligands. The results of this research can be useful in the fields of geochemistry, hydrology, ecology and medicine

Sequential Extraction of Potentially Toxic Metals: Alteration of Method for Cu-Ni Polluted Peat Soil of Industrial Barren

An evaluation of fraction composition and transformation of metal compounds emitted by metal ore processing enterprises and accumulated in soils is crucial for assessing the environmental risks of pollution and ecosystem benefit of remediation. The aim of this study was to develop a suitable sequential fractional procedure for metal pollutants for the peat soils matrix in the impact zone of a Cu-Ni smelter. Three experiment series were performed: (a) the study of the effect of ammonium acetate buffer pH in the range of 3.7–7.8 on the soil metal extraction; (b) the study of the effect of additional volume and frequency of soil treatment with solutions on the content of water-soluble, ammonium acetate extractable, and 0.1 N HNO3 extractable fractions; and, (c) the determination of the metal fraction composition in the modified technique. Soil treatment with ammonium acetate buffer with a pH range of 4.5–5.5 was the most appropriate for the determination of mobile compounds of Cu and other metals in highly polluted peat soil. Triple soil treatment with water and ammonium acetate is necessary for the complete extraction of the water-soluble and exchangeable fractions, respectively. Additionally, we propose a procedure of full extraction of the exchangeable metal fraction from peat soils while using single treatment with 0.1 N HNO3. This scheme allows evaluating geochemical mobility of metals and current environmental harm of polluted soils with a high content of organic matter

COBALT SALTS PRODUCTION BY USING SOLVENT EXTRACTION

The paper deals with the extracting cobalt salts by using mixtures on the basis of tertiary amine from multicomponent solutions from the process of hydrochloride leaching of cobalt concentrate. The optimal composition for the extraction mixture, the relationship between the cobalt distribution coefficients and modifier’s nature and concentration, and the saltingout agent type have been determined. A hydrochloride extraction technology of cobalt concentrate yielding a purified concentrated cobalt solution for the production of pure cobalt salts has been developed and introduced at Severonikel combine

Magnesium Silicate Binding Materials Formed from Heat-Treated Serpentine-Group Minerals and Aqueous Solutions: Structural Features, Acid-Neutralizing Capacity, and Strength Properties

The influence of structural features of three serpentine-group minerals (antigorite, chrysotile, and lizardite) on the hydration of heat-treated materials and the formation of magnesium silicate binder has been studied. Initial serpentine samples have been fired in the interval 550–800 °C with a step of 50 °C; acid neutralization capacity (ANC) values have been determined for all samples. Antigorite samples (SAP) have exhibited a maximum reactivity at a temperature of 700 °C (ANC 7.7 meq/g). We have established that the acid-neutralizing capacity of chrysotile and lizardite samples in the temperature range of 650–700 °C differ slightly; the capacity varied in the interval of 19.6–19.7 meq/g and 19.6–19.7 meq/g, respectively. The samples obtained at optimal temperatures (antigorite—700 °C, lizardite, and chrysotile—650 °C) have been studied. Heat-treated serpentines have interacted with water vapor for a year; serpentine hydration has been investigated. The strength characteristics of the resulting binder agents were studied after 7, 28, 180, and 360 days. Upon hardening within 7 days, the strengths of the SAP and SCH samples have been almost the same (2.2 MPa), whereas this indicator for the SLH and SLK samples has been significantly lower (0.5 MPa). After hardening for over a year, the chrysotile sample SCH had the highest strength (about 8 MPa), whereas the strength of antigorite SAP was 3 MPa. The samples of initial, heat-treated, and hydrated heat-treated serpentines have been studied using XRD, differential scanning calorimetry, and surface texture analysis. The serpentine structure is crucial in destroying the mineral crystal lattice during heat treatment. In contrast to heat-treated chrysotile and lizardite, antigorite did not adsorb water. Structural features of chrysotile provided the highest compressive strength of the binding agent compared with antigorite and lizardite. The acid-neutralizing ability of lizardite was noticeably higher than antigorite, whereas its compressive strength was lower due to the layered mineral structure and impurities. We have established that the minerals’ structural features are crucial for the hydration of heat-treated serpentines; the structure determines material utilization in various environmental technologies

Technosols on mining wastes in the subarctic: Efficiency of remediation under Cu-Ni atmospheric pollution

The copper-nickel factory's emissions in the Murmansk region, Russia, led to the degradation of plant cover and topsoil with the subsequent formation of industrial barrens. In this study, the industrial barrens were remediated by means of Technosol engineering, when grasses were sown on the two different types of mining wastes (carbonatite and serpentinite-magnesite) covered by hydroponic vermiculite. The serpentinite-magnesite waste was significantly different from the carbonatite waste in the content of silicon (Si) and manganese (Mn), pH, and texture. Both wastes had an alkaline pH level and high content of calcium (Ca) and magnesium (Mg). The vegetation and Technosol properties at the remediated sites were analyzed in 2017 and compared to the initial state (2010 year) to assess the efficiency of the long-term remediation. The quality and sustainability of Technosols based on the serpentinite-magnesite wastes were substantially higher compared to the carbonatite-based Technosol. Biomass and a projective cover of the grass community depended on Si content in the original mining waste and were found to be higher in the serpentinite-magnesite Technosol. The content of organic carbon and its fractions, microbial biomass and basal respiration after seven years of Technosol evolution was comparable to natural values. These parameters were directly related to plant cover state and were inversely proportional to copper (Cu) content in Technosol. The Technosol development led to the reduction of nickel (Ni) and Cu migration in soil-plant ecosystems due to neutralization and adsorption properties of mining wastes and phytostabilization by underground parts of grass communities. The Technosol development in its early stage of pedogenesis indicates the efficiency of applied remediation technology to the degraded acidic soil under the conditions of industrial atmospheric pollution