Competition between a bacteriocinogenic and a non-bacteriocinogenic Lactococcus lactis strain, respectively, and a Listeria monocytogenes strain was studied in two semi-synthetic liquid media at various temperatures. The media used for the study were ST I and modified ST I broth (ST I broth + 1 g l-1 Tween 80). In both media, at 30 °C, a significant cell count reduction (5 log) of L. monocytogenes occurred only when the cell concentration of the bacteriocinogenic competitor reached the level of at least 107 CFU ml-1 required for the production of sufficient concentration of nisin-like bacteriocin. The same phenomenon was also observed when the initial level of the lactic acid bacteria (LAB) was one log higher or lower than that of the Listeria, however, the reduction of Listeria cell count occurred earlier with the higher initial concentration of the LAB. Incubation of the mixed cultures at 20 °C gave similar results but the bacteriocinogenic activity resulted in only a three log decline of the cell count of L. monocytogenes. At 10 °C Lactococcus lactis produced much less bacteriocin than at 30 °C, therefore, a drastic decrease of the Listeria cell count was not observed. Suppression of the Listeria growth was expressed in its decreased maximum population level (i.e. in an earlier appearance of the stationary phase). When the non-bacteriocinogenic Lac. lactis and Listeria were present at the same initial level (approx. 105 CFU ml-1), the Lactococcus did not affect the growth of L. monocytogenes at 30 °C in modified ST I broth.
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).
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.
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.
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 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.
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.
Even if plants can contain high levels of nitrate and nitrite, milk and dairy products are not described as sources of these anions. The purpose of this paper was to measure the concentrations of nitrate and nitrite in forage, cow blood, and milk.The results show that the nitrate ratio of milk to plasma is very low, suggesting that milk contamination with nitrate is unlikely to occur. This finding also proves the lack of an active transport mechanism to transfer nitrate from blood to milk. The nitrite anion almost disappears from milk through an enzymatic conversion; usually levels of μg l−1 were measured.
Applying several hydrocolloids in ascending concentrations (0.1, 0.5 and 1% w/w flour basis) to bread making procedure was considered. Effect of hydrocolloids [guar, xanthan gum, carboxylmethylcellulose (CMC), and hydroxypropylmethylcellulose (HPMC)] as bread improver on Barbari (Iranian bread) was analysed in terms of microstructure. Image analysis parameters, hardness, and microstructure of fresh bread were analysed. The results confirmed the ability of hydrocolloids for improving fresh bread quality. Among all used hydrocolloids, HPMC and CMC produced the softest texture, smoothest and continuous structure, and improved overall the bread quality.