Oľga Šestinová, Jozef Hančuľák and Tomislav Špaldon
This study was conducted to investigate heavy metals bioaccumulation in industrialized soils in surrounding of Košice city (Slovakia), using earthworms. In the present research, we used ecotoxicity tests with Dendrobaena veneta (7 and 28-day bioassays) to infer about potential toxic risks to the agricultural (A) and permanent grass vegetation (PGV) of soils around the plant U. S. Steel Košice. The total Fe, Cu, Zn, Pb, Cd, Cr and As contents and eco-toxicological tests of industrialized soils from the Košice area were performed for 12 sampling sites in years 2016 – 2017. An influence of the sampling sites distance from the largest steel producer plant on the total concentrations of heavy metals was determined for Fe, Cd, Cr and As. It was found that earthworms (Dendrobaena veneta) in some cases caused a decrease of metals concentration in contaminated soils, the largest metal concentration differences were recorded in the samples PGV (4) U. S. Steel-plant-main gate. The results of the bioaccumulation factors of heavy metals in D. veneta (BAFs/7-28 d) are < 1 for the studied metals order in the sequence: Cr < Fe < Pb < Cu < As and > 1 for Zn > Cd.
Ewa Możdżer, Krystyna Cybulska, Teresa Krzyśko-Łupicka and Edward Meller
Therefore the carried out study aimed at determination of the effect of high-calcium brown coal ash and compost being produced from municipal sewage sludge on the content and bioaccumulation of heavy metals in potato tubers, wheat grains and rapeseeds during a three-year period. Rapeseeds contained most Cd whereas wheat rains less. Potato tubers, wheat grains and rapeseeds contained more Mn, Ni and Zn in the fertilization objects with municipal sewage sludge with or without coal ash and compared to those where calcium carbonate or coal ash had been introduced into the soil at a dose corresponding to 1.5 Mg CaO · ha–1 at the beginning of this study. Differences in the Mn, Ni and Zn contents in test plants between the fertilization objects with sewage sludge of with and without addition of ash were not significant.
Sinoyolo Nondlazi, Nosiphiwe Ngqwala, Bongumusa M. Zuma, Paul K. Mensah and Roman Tandlich
Acute toxicity of raw and treated greywater towards Daphnia magna was assessed in this study. Treatment was performed with exposure of greywater to the fly-lime mixture After 48 h of exposure, 100 % mortality of D. magna was recorded when testing the following volumetric fractions of the raw greywater streams in the tested liquid medium (%; v/v): 10 % for kitchen greywater, 5 – 10 % for bathroom greywater and 1.25 – 10 % for laundry greywater. After greywater treatment with the fly-ash-lime mixture with pH adjustment to 7.0, 80 % of neonates of D. magna survived after exposure to treated laundry greywater in all dilutions at 48 h. At the same time, 100 % of neonates survived exposure to treated bathroom and kitchen greywater at all volumetric fractions. Therefore greywater had acute toxicity to D. magna, i.e. greywater treatment was required before its discharge or reuse. Values of the Pearson’s correlation coefficient between the chemical components of the raw greywater and treated greywater and the survival of D. magna indicated a lack of statistically significant correlation at 5 % level of significance (p-value > 0.05 in all cases), i.e. the survival of D. magna was independent of the concentration of chemical constituents in greywater samples tested. Further studies will have to be conducted on the chronic toxicity of the greywater effluent after treatment with the fly-lime mixture. Experiments from this study will have to be re-run for the fully scaled-up version of the fly-lime mixture-based greywater treatment systems.
Jiří Horák, Lenka Kuboňová, Milan Dej, Vendula Laciok, Šárka Tomšejová, František Hopan, Kamil Krpec and Jan Koloničný
Ashes were prepared by annealing selected types of solid fuels (biomass: corn cobs, sunflower husks, olive pomace, hay pellets and rice husks; coal: lignite and bituminous; and alternative fuel: paper sludge) at different temperatures (550°C, 815°C and 975°C). Based on X-ray fluorescence spectra, the slagging/fouling indexes were used to study the effects of the type of ash and the ashing temperature on the ash fouling and slagging properties. Slagging indexes were compared with the ash fusion temperatures. Ash fusion temperatures were measured by a LECO AF-700. The lowest deformation temperature (below 1000°C) was seen for the ashes prepared from hay pellets and corn cobs. On the other hand, the deformation temperature exceeded 1500°C for ashes prepared from paper sludge, sunflower husks and rice husks. By calculating the different slagging/fouling indexes, all the ashes exhibited slagging/fouling problems of varying degrees.
Jana Sedláková-Kaduková, Jana Kisková, Lenka Maliničová, Ivana Timková, Stanislav Jeleň and Peter Pristaš
Sulphur-oxidising autotrophic bacterial communities in deep biosphere from weathered ore samples from active gold mine Hodruša-Hámre, Slovakia were analysed using cultivation approach followed by DNA extraction, PCR amplification and 16S rRNA gene analyses. Indirect measurement of pH changes in cultivation media evidenced the presence of acidophilic bacteria with active production of acids. The decrease of pH was observed at the beginning of isolation and later pH in range of 1.5 – 2 was maintained in both, sulphuric acid and thiosulphate, media. The presence of homogenous population of gram-negative rods was proved by Gram staining. Molecular analyses have revealed that the population of sulphur-oxidising bacteria in gold mine is dominated by a single species of Aciditiobacillus genus, identified as A. albertensis, suggesting the low level of autotrophic bacteria diversity in deep deposits. For the first time this species was isolated from weathered rocks of a gold mine subsurface environment.
The hydrophilic films based on starch and carboxymethyl starch (CMS) were obtained using cast method. The effect of CMS content on the physicochemical properties of prepared films were evaluated. With increasing content of starch derivative the moisture absorption, solubility in water as well as swelling ratio increased. The highest values of mechanical parameters (tensile strength and Young’s modulus) were determined for the starch/CMS film containing the lowest CMS amount, i.e. 10 wt.% (1.1 MPa, 15 MPa, respectively). For the same system the lowest moisture absorption, solubility in water as well as swelling ratio were reported. Thus, it could be concluded that for this system the highest crosslinking density has been achieved, what was confirmed by DMTA results. Such a film could potentially find application in food or agricultural industry.
Permeabilization is one of the effective tools, used to increase the accessibility of intracellular enzymes. Immobilization is one of the best approaches to reuse the enzyme. Present investigation use both techniques to obtain a biocatalyst with high catalase activity. At the beginning the isopropyl alcohol was used to permeabilize cells of baker’s yeast in order to maximize the catalase activity within the treated cells. Afterwards the permeabilized cells were immobilized in calcium alginate beads and this biocatalyst was used for the degradation of hydrogen peroxide to oxygen and water. The optimal sodium alginate concentration and cell mass concentration for immobilization process were determined. The temperature and pH for maximum decomposition of hydrogen peroxide were assigned and are 20°C and 7 respectively. Prepared biocatalyst allowed 3.35-times faster decomposition as compared to alginate beads with non permeabilized cells. The immobilized biocatalyst lost ca. 30% activity after ten cycles of repeated use in batch operations. Each cycles duration was 10 minutes. Permeabilization and subsequent immobilization of the yeast cells allowed them to be transformed into biocatalysts with an enhanced catalase activity, which can be successfully used to decompose hydrogen peroxide.
Ľubor Dlháň, Roman Krylov, Martin Kopáni and Roman Boča
Bovine spleen has been used as a sample for deep magnetochemical investigation. Temperature dependence of the magnetic susceptibility and field dependence of the magnetization reveal a paramagnetic behaviour that violates the Curie law. The zero-field cooled magnetization and field cooled magnetization experiments show the bifurcation point at ca TC = 20 K and the blocking temperature TB = 10 K confirming a dominating portion of ferritin along with the organic tissue. There is a remnant magnetization at temperature below 20 K and the search for the magnetic hysteresis was positive.
The paper presents analysis of stress distribution in the friction node of knee joint endoprosthesis where sleds are made of various titanium alloys and CoCrMo cooperate with spherical polyethylene inserts. Currently used titanium alloys consists of Nb, Ta, Zr or Mo and with lesser value of Young’s modulus than Ti6Al4V alloy, or steel CoCrMo, which significantly varies from other metal materials. The obtained results make it possible to indicate the “weak points” of the accepted solution, and thus counteract the subsequent effects resulting from premature wear of endoprosthesis elements. The analysis was conducted with numerical method of ADINA System 8.6. The Finite Elements Method allowed to compute and present stress distribution quickly in all elements of the model.
Advances in nanotechnology in various fields of human activity contribute to increase of their production, improved properties and wider implementation of nanomaterials. However, increasing use may enhance their release into the environment and can lead to affecting human health. The toxicity of colloidal solutions of metal nanoparticles (Cu, Mn) and their oxides, obtained in the absence and presence of a stabilizer, was examined and compared with the use of the standard test system of Allium cepa L.. The phytotoxicity of the experimental solutions was evaluated according to the growth response of the onion roots; the cyto- and genotoxicity were estimated due to the proliferative activity of the root meristem cells. It was established that solutions of stabilized metal nanoparticles were at given concentration toxic to Allium cepa L. according to the integral index of roots growth, however, were not cytotoxic. Difference in the phytotoxicity of stabilized and non-stabilized metal nanoparticles and their oxides depended on their phase composition and affected root growth.