Modeling Changes in the Composition of River Water with Discharged Wastewater: A Case Study in NW Russia

The technogenic impact of the development of the Lomonosov diamond deposit is associated with the discharge of quarry and drainage water into the river, which has a special conservation status. Earlier studies on the composition of bottom sediments showed that there are signs of increased accumulation of heavy metals and radionuclides at wastewater discharge sites. The purpose of this work was to predict changes in the composition of surface water and bottom sediment in the river during the further development of mining operations with brackish and salty water captured by drainage systems, the presence of which was established in the zone of their future influence. For this, a simulation of changes in the composition of the water in the river was carried out using the GEOCHEQ software package by minimizing the free energy of the system using a convex simplex algorithm. It was found that the maximum salinity of surface water can reach 1.51 g/L. In this case, the MPC of Cl−, Na+, SO42−, Mg2+, Sr, V, and U can be exceeded for fishery watercourses. The genetic basis of the accumulation of these components in solutions for mixing was considered. According to the calculations, when about 5000 m3/h of drainage water is discharge d into the river, the mass of precipitated chemical elements will be 56–191 t/h, including up to 2.1 t/h of iron; therefore, accumulation in the discharge zone must be controlled.

Hydrochemical peculiarities and groundwater quality assessment of the Birimian and Tarkwaian aquifer systems in Bosome Freho District and Bekwai Municipality of the Ashanti Region, Ghana

The Birimian and Tarkwaian aquifer systems are the main sources of water supply for the Bosome Freho District and Bekwai Municipality inhabitants in the Ashanti region of Ghana. A hydrogeochemical assessment was carried out to ascertain the natural baseline chemistry of the groundwaters and the factors influencing groundwater chemistry in these two areas. A multivariate statistical tool consisting of principal component analysis (PCA) and hierarchical cluster analysis (HCA) together with hydrochemical graphical plots was applied on 64 groundwater samples. The Q–mode HCA results were used to explain the changes in groundwater chemistry along the flow paths where three spatial groundwater zones and water types were delineated. The first type consists of Ca–Mg–HCO3 freshwater (recharge zone), which transitions into Ca–Na–HCO3 or Na–Ca–HCO3 mixed waters (intermediate zone) and finally evolves to the third type of Na–Ca–Mg–HCO3–Cl water (discharge zone). The study also reveals that the natural process influencing water chemistry is groundwater–rock interaction from carbonate and silicate weathering/dissolution, aided by carbonic acid from precipitation and releases concentration of Na+, Ca2+, Mg2+, and HCO3− into the groundwaters significantly. The chloro-alkaline indices also reveal cation exchange as the principal natural factor that controls groundwater chemistry in the area. Inverse geochemical modelling shows the dissolution of primary minerals such as dolomite, plagioclase, halite, gypsum, and precipitation of calcite and chlorite along the groundwater flow path. Anthropogenic activities have little influence on groundwater chemistry. The quality of groundwater in the Bosome Freho District and Bekwai Municipality is suitable for irrigational use and drinking water consumption. The results obtained so far will contribute to research paucity in the study area and serve as a guide for decision-makers for improved water resources management.

Investigation of the electrospark coating, alloying and strengthening technology

Introduction. The work objectives were the analysis and application of the technology of electrospark deposition of wear-resistant metal coatings on cutting tools or machine parts for their hardening or dimensional restoration.Materials and Methods. The technology, device and principle of operation of the modernized installation intended for electric spark application of wear-resistant metal coatings with composites T15K6, VK8 and VK6 are considered.Results. To determine the parameters of the upgraded electrospark alloying plant, experiments were carried out on hardening of polished samples made of steel 45 with hard alloy T15K6 with dimensions of 25×25×25 mm. As a result of using the experiment planning method, the possibility of selecting and adjusting the installation parameters was confirmed. The following parameters were selected for hardening samples made of steel 45 with hard alloy T15K6: current I = 1-2–A, voltage U = 40-75 V, capacitor bank capacity = 60–100 µF.Discussion and Conclusions. The use of carbon dioxide as a protective medium enables to increase the number of passes and, accordingly, the number of coating layers to twenty, to obtain a total thickness of up to 0.3 mm with a dense structure without oxides. Coatings of this thickness make it possible not only to strengthen, but also to restore the dimensions of worn machine parts. The parameters of the technological modes of electrospark alloying significantly affect the intensity of coating application and the quality of the resulting surface. A rise in the electrical parameters causes an increase in the intensity of each individual discharge and, within certain limits, contributes to an increase in the amount of the transferred coating material, as well as to deeper transformations of the coated surface in the discharge zone. Thus, an electrospark alloying plant equipped with monitoring and diagnostic tools, as well as with a protective gas supply system, can be used for hardening and restoring machine parts and cutting tools.

Research stand for microplasma surface treatment of materials at atmospheric pressure

A research stand for microplasma treatment of object surfaces with the ability to move the discharge zone along the object using a program-controlled linear stepper motor has been developed. The design of the stand allows the use of different types of plasma generation systems, as well as processing with feeding of various gases such as air, nitrogen, oxygen, etc. into the discharge zone. The research bench is equipped with measuring equipment for monitoring the electrical and physical characteristics of the discharge (digital oscilloscopes, optical emission spectrometer, air ion meter, etc.). A microhardness tester, goniometer, interference microscope, tribometer, tensile testing machine, etc. can be used to further evaluate the quality and characteristics of the treated surfaces. Examples of the electrical characteristics of discharge devices tested as part of the research stand, optical emission spectroscopy of plasma, and results of measurements of the contact angle of treated objects surfaces are given.

Transfer of "dark hydrogen" by atomic matter. Methods of diagnostics of "dark hydrogen"

This work experimentally shown that traces found on track detectors during the study of low-energy nuclear reactions are also formed in the course of many widely used technical processes (combustion of hydrocarbons, operation of internal combustion engines, physicochemical processes accompanying the process of charging smartphone batteries). This coincidence of the track pattern allows us to consider low-energy nuclear reactions as a significant environmental factor, and indicates the important role of “dark hydrogen” in nature. The paper shows the convective transfer of “dark hydrogen” from the discharge zone along the path of the air-water mixture. Using the theoretical model of “dark hydrogen”, fundamentally new, less laborious, in comparison with track, methods of its registration have been developed and described: 1) measurement of the charge of a copper box with its irradiation with “dark hydrogen”, 2) measurement of pressure in a closed volume when irradiated with “dark hydrogen”, 3) the use of a torsion balance with a nickel plate with magnets when irradiated with “dark hydrogen”.

МОДЕЛЮВАННЯ ПРОЦЕСУ ВЗАЄМОДІЇ ІМПУЛЬСНОГО СТРУМЕНЯ ІЗ ЗАГОТОВКОЮ ПРИ ЕЛЕКТРОГІДРАВЛІЧНОМУ НА-ВАНТАЖЕННІ

The eg-stamping of thin-leaf-sized parts has shown its technical and economic efficiency, including the ability to receive parts of ultrahon-thread accuracy. At the same time, the workpieces are loaded on the eg-presses of large intensive energy (up to 500 kJ), which have the possibility of space-time loading control. Such management is carried out using multi-terminated discharge blocks in which dozens of discharge cavities are combined into one. The controlled parameters can be the electrical parameters of tens of discharge circuits of the current pulse generator, the volume and step of the arrangement of the discharge cavities, their height to the workpiece, as well as the sequence of discharges in time (simultaneous or with a shift in the time of EG-discharges in adjacent discharge cavities). The choice of rational ranges of these parameters is impossible without numerical simulation of processes occurring in the discharge volume of the entire block.In the simulation, the processes of heat power is comprehensively considered with the EG-discharge, the formation and propagation of the vapor-gas bubble, which generates a flooded stream of liquid, and deforming the supple billet when exposed to such a jet.The results of numerical experiments in the LS-DYNA environment using the ALE method with the EG-discharge in a single bit (submersible) chamber, in two and three neighboring conditions with different variable conditions are set: the distance from the discharge zone to the workpiece (discharge distance) and the displacement of the time of two and three discharges in the adjacent discharges. As compared parameters were selected: movement of the billet and their speed, the distribution of deformations on the surface of the workpiece and the work of deformation. The adequacy of the model of the real process is shown. An energy-efficient energy-generating cell is proposed for generating EG-discharges from a multi-mounted pulse current generator.

Numerical Study and Theoretical Comparison of Outlet Hole Geometry for a Gravitational Vortex Turbine

The gravitational water vortex turbine is an alternative to renewable energies, it transforms the hydrokinetic energy of the rivers into electric energy and it does not require a reservoir. According to studies carried out, the hydraulic efficiency can increase or decrease according to the turbine geometrical configuration. This paper presents a numerical (CFD) and analytical comparison between conical and cylindrical designs for the outlet. The results show a higher performance for conical geometry than the cylindrical tank. The fluid behavior in CFD and analytical studies presents a tangential velocity increase near to air core and outlet hole (similar behavior). The maximum theoretical power generated was 167 W and 150 W for conical and cylindrical design respectively. The differences between geometries of the outlet holes using CFD and analytical models were 11 and 7%, respectively. However, the closest results to the CFD model had different values of 31 and 29% for conical and cylindrical design, respectively. The furthest result regarding the CFD study was 55%. The principal difference is due to tank geometry, the change in discharge zone, as well as the ratio of diameter tank and outlet hole can increase or decrease the tangential velocity and make a stronger and more stable vortex formation. The theoretical power generated is a good parameter to select the height to place the rotor.

Human Health Risk Assessment and Histopathological Alterations in Puntius sophore of Damsal Nala, Sukinda Chromite Valley, Odisha, India

The aim of the present study was to assess the concentration of potentially toxic metals (PTMs) like As, Cd, Cr, Cu, Fe and Pb in the Damsal Nala of Sukinda Chromite Valley, Jajpur of Odisha (India) and its subsequent histopathological lesions in the fish Puntius sophore. Energy Dispersive X-Ray Fluorescence (EDXRF) and Flame Atomic Absorption Spectroscopy (FAAS) methods were used to evaluate the concentrations of PTMs in the muscles of fish, Puntius sophore collected from different zones namely upstream discharge zone (UDZ) and upstream zone (UZ) of the Damsal Nala and control water bodies (CW). In the UDZ of Nala, the concentration of metals viz., Cd, Pb and Fe were 2 to 7 times, and Cr was 77 times higher than the maximum permissible limits recommended by WHO and FAO in the fish muscles. The values of Target Hazard Quotients (THQ) of all these 6 metals were <1 in CW and UZ, but in UDZ the THQ values of Cr and Fe were >1. Hazard Index (HI) for UDZ was 3.47, indicated the alarming concentration of metal which can pose serious risk to human health. Histopathological observations in liver and kidney of Puntius sophore collected from UDZ demonstrated the serious lesions, but mild damage in fish collected from UZ. These histological alterations and the health risk indices disclosed the effects of effluents of chromite mining and the impact on the ecological balance which may result into health hazards to the local human population who are maintaining their livelihood by consuming these fish as protein source.

The Role of HNO2 in the Generation of Plasma-Activated Water by Air Transient Spark Discharge

Transient spark (TS), a DC-driven self-pulsing discharge generating a highly reactive atmospheric pressure air plasma, was employed as a rich source of NOx. In dry air, TS generates high concentrations of NO and NO2, increasing approximately linearly with increasing input energy density (Ed), reaching 1200 and 180 ppm of NO and NO2, at Ed = 400 J/L, respectively. In humid air, the concentration of NO2 decreased down to 120 ppm in favor of HNO2 that reached approximately 100 ppm at Ed = 400 J/L. The advantage of TS is its capability of simultaneous generation of the plasma and the formation of microdroplets by the electrospray (ES) of water directly inside the discharge zone. The TS discharge can thus efficiently generate plasma-activated water (PAW) with high concentration of H2O2−(aq), NO2−(aq) and NO3−(aq), because water microdroplets significantly increase the plasma-liquid interaction interface. This enables a fast transfer of species such as NO, NO2, HNO2 from the gas into water. In this study, we compare TS with water ES in a one stage system and TS operated in dry or humid air followed by water ES in a two-stage system, and show that gaseous HNO2, rather than NO or NO2, plays a major role in the formation of NO2−(aq) in PAW that reached the concentration up to 2.7 mM.

Identification and Investigation of Subsidence Areas to Mitigate Karstic Risks in Urbanized Areas of Madrid, Spain: A Case Study

A multidisciplinary investigation was carried out in a karstic depression in a housing development under construction in Madrid to assess its stability. It was found that it is a small basin within a larger depression as a result of subsidence accumulated during the Quaternary. Subsidence has built up progressively in the Miocene clay cap and bedrock due to the underlying dissolution of gypsum rich intercalations. The preferential circulation of the dissolving subsurface flow is along a fault conditioned by subsidence, the formation of an elongated syncline along the fracture, and the alluvial basin. During the Pleistocene, a former lagoon zone was formed in this subsiding area; it was also a groundwater discharge zone. The decrease in recent times is very small and could be evaluated to be about 0.4 mm/year, and affects the alluvial zone and along the furrow of a fault zone, where the maximum average rate of subsidence would be 1.4 mm/year. This has led to the development of a relatively strong alluvium. It seems that under the alluvial deposits, a slow and diffuse dissolution is taking place of the shallower clayey gypsiferous levels, free of hypersoluble mineral species; this is somewhat more intense in the fault zone, which is more active hydrodynamically, where groundwater velocity is higher. Microgravimetry surveys indicate that only 5% of the area hidden under the alluvium shows anomalies, interpreted as residual soft clayey masses, or anomalous alluvial fillings of old dissolution voids. These pockets (“bolsones”), have dimensions of no more than 20 × 20 m and depths below 20 m. These measurements have been confirmed by boreholes and are the only points that would require special attention in the future construction of the urbanization. The urbanization work, in full development, is implementing solutions aimed at the stability of the road in the strips of alluvial studied.