Key Engineering Materials Vol. 838

Abstract: People spend most of their time in various indoor spaces and their health is exposed to different kinds of air pollutants. Volatile organic compounds (VOCs) belong to a group of chemical substances polluting the indoor environment. They come into the interior of buildings mainly from internal sources in the form of building materials, flooring, composite wood products, adhesives and other consumer products. Their presence in indoor air is monitored, due to their carcinogenic and mutagenic effects on human health. Many studies of indoor environment contaminated by VOC have been published during the last years. The present study provides general overview of the occurrence and emission sources of VOCs in the indoor environment of different types of buildings. The most frequently monitored indoor organic pollutants in terms of their occurrence and health risk are BTEX (benzene, toluene, ethylbenzene and xylenes), terpenes (α-pinene and d-limonene) and aldehydes (formaldehyde, acetaldehyde and benzaldehyde). Their concentrations in different indoor environments are variable and depend on factors such as emission characteristics of sources, microclimatic and ventilation conditions. Formaldehyde and toluene levels increased significantly with increasing room temperature. Benzene enters the indoor environment of buildings from external sources, especially from traffic or industrial areas. Formaldehyde, α-pinene and d-limonene originate from indoor sources as a part of building materials, furniture and household products.

Abstract: In the framework of this study, compressed earth blocks (CEB) were produced using waste materials and various parameters. Material parameters included waste soil, recycled concrete, fly ash, cement, admixtures and water contents. Manufacturing parameters were vibration during manufacturing, confinement pressure, curing environment and curing time. Specimens used in this study were cubes and compressive strength testing was used to evaluate different mixtures and manufacturing methods. In terms of compressive strength, compressed earth blocks made of these materials could be used for manufacturing bricks and other structural elements.

Abstract: Green concrete is defined as a concrete which uses waste material as at least one of its components, or its production process does not lead to environmental destruction, or it has high performance and life cycle sustainability. Currently, cement and concrete production is at all-time high resulting in significant carbon dioxide emissions. Eight percent of the world's total CO₂ emissions come from manufacturing cement. Nanomaterial concrete is new generation concrete formed of materials of the grain size of nanoscale. In the construction industry, nanomaterials has potentials, especially the functional characteristics such as increased tensile strength. The paper shows the dose dependence carbon nanotubes for the physico-mechanical properties of cement mixes.

Abstract: The paper deals with investigation of changes in selected properties of concretes which have been exposed to acid rain. The experiments took place in laboratory under model solution representing acid rain (40 % HNO₃, 60% H₂SO₄) over a period of 7 weeks. The concrete samples investigated were concretes with ordinary Portland cement only as well as concretes of high-portion-mineral-addition-cements as well. Disruptions, cracking and samples' falling apart at the end after 7-week exposure to acid rain were observed by evaluation of visual changes. Based on the determination of the other parameters the results are not so uniform that is why the clear statement of more suitable concrete resistant to acid rain is not given. The assumption that a high-mineral concrete mix would be more suitable for environments exposed to acidic rain was not confirmed in this experiment.

Abstract: Pyrogenic carbonaceous materials produced by pyrolysis process of various waste feedstocks are increasingly used in non-soil applications such as water purification tools. Pyrogenic carbonaceous materials thermochemically converted from wood chips, corn cobs, garden green waste, cherry pits, walnut shells, pine cones and municipal sewage sludge in slow pyrolysis under N₂ atmosphere, were characterized by total C analysis, specific surface area, volumes of micro- and mesopores and tested in batch experiments as potential radiocesium sorption materials. Cesium adsorption-desorption experiments were conducted using the ¹³⁷Cs radioisotope. Although tested materials significantly differ in Cs removal, Cs⁺ ions uptake could be attributed to the mechanisms of Freundlich surface adsorption. The highest maximum sorption capacities were reached for pine cones, wood chips and garden waste pyrogenic materials and reached 95.9 to 126 μmol g^-1. These results demonstrate suitability of selected Pyrogenic carbonaceous materials as Cs adsorbents potentially useable as reactive barriers for ¹³⁷Cs contaminated effluents.

Abstract: The research is primarily focused on the determination of humidity on radon volume activity in different soil gas permeabilities in a given land. The research also included the detrermination of the radon index in the given land. The mean concentrations of radon in soil gas during the drought ranged from 15.9 - 24.1 kBq/m³ and in the precipitation period 16.3 - 26.7 kBq/m³. The first area was characterized by low gas permeability of soils, where a low radon index was determined during the dry season and a medium radon index was determined in the precipitation period. The second area, the medium gas permeability of the soils was determined from the analysis of the collected soil samples. The values of the third quartile in both cases measurements of radon volume activity in soil gas fall into the middle class of radon index. The third location would be determined by high gas permeability of soils. The radon index of the given land during the drought was determined as the medium, as in the case of measurement of radon volume activity in soil gas in the period with added moisture in the soil profile. The analysis confirmed the effect of moisture on the volume activity of radon.

Abstract: The paper is focused on the research of pollutants in dredged material and water in the watershed of the Sigord reservoir (Eastern Slovakia), which is influenced by anthropogenic activity. The monitored area extends to the cadastral area of ​​Zlatá Baňa, which has been used for a long time and intensively for mining of gold, antimony and mercury. After the end of mining activities (at the beginning of the 20th century) the territory remained devastated by numerous remains of mining activities and no attention has been paid to this area in terms of scientific research. Therefore, the monitoring of dredged sediment and water quality has been carried out. The results show that the limit values ​​of selected heavy metals (such as Sb, As, Hg, Pb, Cu, Zn, Ni, Fe and Al) are exceeded in both sediments and water in the reservoir watershed, as a result of the former mining activities around Sigord.

Abstract: This work studied the potentials of indigenous Micrococcus sp., Bacillus sp., Pseudomonas sp., and Escherichia coli (E. coli) for bioremediation of lead contaminated soils collected from Amita forest in Ebonyi State of Nigeria.The organisms isolated from the soils were conditioned with the predetermined optimum factors in inoculated soil samples. The samples were tested for residual lead concentration at times 8, 16, 24, 32, 40, 48, and 56 days with Atomic Absorption Spectrophotometer.The performances of the organisms were in the decreasing order of Micrococcus sp., Bacillus sp., Pseudomonas sp., and E. coli. Micrococcus sp. and Bacillus sp. performed earlier at time 16 days as against Pseudomonas sp., and E. coli at 24 days. The maximum efficiencies were discovered at time 56 days as 76.68%, 72.24%, 70.11% and 55.47% for Micrococcus sp., Bacillus sp., Pseudomonas sp., and E. coli respectively with respective residual concentrations of 31.55 mg/kg, 37.55 mg/kg, 40.44 mg/kg and 60.24 mg/kg at the respective efficiencies.The rates of removals were in the decreasing order of -0.0524d^-1 for Pseudomonas sp., -0.0714 d^-1 for Bacillus sp., -0.0743d^-1 Micrococcus sp., and 0.113 d^-1 E. coli. The fitted models showed diffusion as the rate-limiting step for removals by Pseudomonas sp., Bacillus sp., and Micrococcus sp.; while chemisorption was the rate-limiting step for removal by E. coli. This information will be helpful to researchers and decision makers for the remediation of lead contaminated soils.

Abstract: Degradation of arable land can rightly be considered as one of the most serious environmental problems; therefore, detailed research is needed to examine the practical possibilities for improving soil properties. The application of compost and vermicompost substrates seems to be a very advantageous way of improving the quality of soil, which may also result in an increase in the yield of cultivated plants. At the same time, the use of compost, a product of completely natural decomposition of biowaste, as a suitable organic fertilizer for arable land, is a very desirable contribution to the principles of the circulatory and recycling society.

Abstract: This study aims to carry out an experimental investigation of particulate matter (PM) concentrations, temperature, humidity and air velocity. Košice - Krásna is located in the south-eastern part of the city of Kosice on both sides of the river Hornád. Locality Na Hore II is a residential area that was under construction during the monitoring period. This study also investigates the relationship between various fractions of particulate matter (PM_0.5, PM₁, PM_2.5, PM₅ and PM₁₀) in outdoor and indoor environment. Indoor mean concentration of PM_2.5 was 3.92 μg/m³ and outdoor mean concentration of PM_2.5 was 15.41 μg/m³. An indoor mean concentration of PM₁₀ was 13.77 μg/m³ and outdoor mean concentration of PM₁₀ was 38.34 μg/m³. Permissible value for indoor PM₁₀ (50 μg/m³) was exceeded. I/O ratio were <1 for all fractions of particulate matters.