The residual waste has a high concentration of recoverable elements, which can be either recycled or recovered into energy in accordance with the waste hierarchy. One option is the implementation of mechanical biological treatment of waste, which has showed a steady progress in the recent two years in Hungary.
This paper analysis the relevant factors, which should be considered during the technology planning. The multi criteria analysis involves the economical environmental and external considerations into the technology assessment. Based on the results, the technology plan should be revised and adjusted.
For open channels significant pollution sources during the intensive precipitations are outflows from storm-water overflows on the sewer network. When combined with low discharges in rivers, the water released from overflows can cause high concentration of pollution in receiving open channels. In this paper, the results of computer modeling of the impact of storm-water overflows on the stream water quality in three municipalities in Czech Republic are shown. The local river networks are the main receivers in the cities where storm-water overflows are led in. The results serve as a base for the proposals on the measures, improvements and structural modifications.
Authors:Brigitta Török, Adél Len, and Zoltán Orbán
This paper presents a nonstandard experimental procedure for detection of the presence of salts in building materials. The proposed tests helped modeling the deterioration of specific historical building materials caused by salts. The specimens were subject to visual survey and scanning electron microscope analyses, after submerging them in salt solutions. The results showed the damage of brick, cement based mortar and lime based mortar, caused by various concentrations of sulphate and chloride solutions. By this method various types of salt crystals could be identified. In cement and lime based mortars larger extents of salt deposits were found. A relevant difference between the control samples and the salt treated samples was observed.
Authors:Endre Salamon, Zoltan Goda, and Tamás Berek
Unsuitable feed water quality causes fouling and serious decrease in membrane permeability during the operation of reverse osmosis filters, which leads to costly operation and low contaminant removal efficiency. The purpose of the experiment was to create a detailed, yet simple calculation scheme, suitable for higher education and everyday pilot experiments. The obtained formulas were calibrated against measured results, while investigating the fouling of the membranes at different iron concentrations. Pressure losses on a reverse osmosis equipment with a permeate capacity of 100 L/h were investigated for almost a year. Changes in permeability and cleaning methods were investigated with different feed water qualities.
The abandoned Smolnik mine is regarded as an environmental loading in the Central Europe region, where acid mine drainage (AMD) is generated and discharged from abandoned mine and contaminates the Smolnik creek catchments. The whole mine complex produces large amounts of AMD with the pH 3–4 that contain high metal concentrations, fluctuating depending on rainfall intensity.The main aim of this work is to compare and to interpret the method of adsorption for the heavy metals (Cu, Fe, Al, Mn and Zn) removal from AMD out-flowing from the shaft Pech of the deposit Smolnik (Slovak Republic).
Pollution of the natural environment by heavy metals is a universal problem because these metals are indestructible and most of them have toxic effects on living organisms, when permissible concentration levels are exceeded. The degree of contamination in the sediments of the Smolnik creek, for the metals Ca, Mg, Fe, Mn, Al, Cu, Zn, As, Cd and Pb, has been evaluated using Enrichment factor (EF), Pollution load index (PLI) and Geo-accumulation index (Igeo). The sediments have been found to be contaminated with Pb, Cu and As which has been attributed mainly acid mine drainage from abandoned shaft Pech (the mine Smolnik) since no major industrial establishments are present in the area.
Authors:Adriana Eštoková, Jozef Oravec, and Martina Kovalčíková
The paper presents the results of leachability testing of selected heavy metals from the concrete composites of various compositions in order to assess the degree of a contamination risk of the environment. Tested concrete samples contained various amounts of special ingredients based on the blast furnace slag (65%, 75%, 85% and 95% of Portland cement replacement). Leaching tests have been performed by using distilled water. The concentrations of chromium and barium ions in the leachates were measured after period of 30 and 240 days. Changes in pH and conductivity values in leachates have been also observed.
In the present study, fully developed laminar flow with forced convection heat transfer of Al2O3/water and TiO2/water nanofluids inside a vertical tube subjected by constant heat flux from the wall was numerically analyzed using Ansys Fluent release 17.2. In this work, the single-phase model was proposed to simulate the water and nanofluids heat transfer characteristics; spherical nanoparticles with a constant diameter equal to 30 nm are used. The study has been carried out on a Reynolds number with ranges (400-2000) and nanoparticles volume concentration up to 1.5%. the results show that the average Nusselt number for nanofluid is higher than that the base fluid (water) especially for TiO2/water nanofluid, the Nusselt number increased with increasing Reynolds number and volume concentration in all cases. The enhancement ratio for nanofluids compared to water at different volume friction was studied; the higher improvement is about 3.51% for TiO2/water nanofluid with 1.5% volume fraction. Moreover, a study for pressure drop along vertical tube was discussed.
This study describes the development and application of a mathematical model of the two-phase flow regime found in settling tanks. The phases present are water, the continuous medium, and solid, the dispersed phase. The performance of the model is assessed, applying it to two validation cases using solid suspensions as the working medium. These are; a settling tank measuring velocity and concentration. The calculations are presented for two different dispersed phase densities for the experimentally given density difference between the inlet and outlet. Computational Fluid Dynamics (CFD) simulations are employed to assess the effect of extended a baffle at the feed section of a full-scale sedimentation tank for the improvement of solids settling in potable water treatment in Slovakia. It is found that the baffle decreases the inlet re-circulation zone and enhances the settling of solids by directing them towards the bottom of the tank with high velocities. It is noteworthy that even small differences in the particle velocity can cause large changes in the percent of settled particles; in this work, the overall solids removal efficiency increased when using the baffle from 80% to 98% leading to a reduction of the effluent solids concentration of approximately 85%.
Heavy metals, including copper, are a serious environmental problem today. As an essential part of acid mine drainage they cause degradation of surface and subsurface water quality, including drinking water. Significant character of acid mine drainage is low value of pH, as a result of hydrogen cations releasing into aqueous environment during the process of pyrite oxidation and high concentration of heavy metals. Sorption techniques are widely used to remove heavy metal ions from large volumes of aqueous solutions. The fact of low pH must be taken in consideration because it has a relevant impact on the behavior of the sorbent during the sorption process.In order to study the optimal parameters of the sorption process of Cu(II) from acid mine drainage (pH=3–4), two sorbents under model conditions in solutions with pH of 4 were studied. For this purpose low cost natural sorbents turf brush PEATSORB and natural zeolite were selected. Different contact time and various initial concentrations of ions were tested as variables. The properties of the tested sorbents were compared from the point of view of their efficiency and sorption capacity. The impact of sorption on the pH change in solution was also studied.