Emília Hroncová

Ecotoxicity of Concretes with Granulated Slag from Gray Iron Pilot Production as Filler

This paper focuses on research concerning the ecotoxicological properties of granulated slag from the pilot production of gray iron with red mud addition and concrete composites with the application of this slag. Red mud is a hazardous waste generated in the production of aluminium oxide. Negative ecotoxicological tests are, therefore, one of the basic prerequisites for the ability to use granulated slag from gray iron pilot production. Granulated slag and concrete composite samples with various ratios of granulated slag have been subject to ecotoxicity tests: determining root growth inhibition in the highly-cultivated plant Sinapis alba, and determining acute toxicity in Daphnia magna. The results of ecotoxicological testing of granulated slag from gray iron standard production and gray iron pilot production with the additive were, according to the standard (STN 83 8303), negative. Additionally, the results of ecotoxicological tests of concrete composites were negative, with the exception of a 50% substitution of fine aggregate with slag from gray iron pilot production.

Problematic issues of air protection during thermal processes related to the energetic uses of sewage sludge and other waste. Case study: Co-combustion in peaking power plant

Currently, it is necessary to deal with issues related to the emissions as there is a constantly increasing interest in combusting sludge from sewage treatment plants in the boilers for wood. An analysis of the energetic importance of the combustion of sewage sludge has already been carried out, but the effects of various treatments of the sludge are not always clear, e.g. composting and subsequent combustion to the air pollution. Investments in other thermal processes of energetic utilisation of sewage sludge and organic waste are not always successfully implemented. The objective of this paper is to point out some problematic cases for acceptance of thermal processes related to energetic use of waste in terms of the air protection. The other aim is to mention the experience with solutions of such issues in Slovakia. There are mentioned first results of the operational validation experiments during the energy generation in circulating fluidized bed boiler in peaking power plant (Power 110MW) with the addition of the so-called alternative fuel based on wood and sewage sludge to the main fuel - black coal (anthracite). And there has already been achieved the highest share of 12.4%w. (dry matter) of sewage sludge in form of compost in blend with black coal, which is technologically viable. Moreover analyzed the problems of the authorization and operation of the co-combustion of sewage sludge and of combustion of products of various kinds of pyrolysis waste - pyrolysis gas and pyrolysis oil are analyzed.

A Comparison of the Behaviour of Spruce Wood and Polyolefins during the Test on the Cone Calorimeter

This article deals with comparison of the behaviour of spruce wood and polyolefins (polyethylene PE and polypropylene PP) during the test on the cone calorimeter. Samples were tested on the cone calorimeter at heat flux of 20 and 40 kW/m2. An evaluation of the behaviour of examined materials was based on the determination of the maximum and the average heat release rate, yield of carbon monoxide (CO), and relative comparison of tendency to fire propagation in a flashover phase. The tendency of materials to fire propagation in the flashover phase was evaluated based on the Pearson ́s correlation, the Spearman ́s correlation and the Kendall ́s correlation coefficient of HRR-CO and CO2-CO. Spruce wood showed better properties in comparison with PE and PP in all evaluated parameters (the maximum and the average heat release rate, the yield of CO, and also the resistance to fire propagation in the flashover phase. Additionally, spruce wood showed significantly lower sensitivity of dependence of the maximum and also the average heat release rate on external heat flux.

Combustion of Biomass Fuel and Residues: Emissions Production Perspective

This article provides possibilities for minimising the emissions from eight types of biomass combustion boilers given by virtue of continuous emission measurement. The measure‐ ments were carried out on various types of one‐ or two‐stage combustion devices. In all investigated modes of combustor operation, the concentration of nitrogen oxides in the whole cycle of fuel combustion was without marked deviations and far lower than the emission limit of 650 mg/mn3. Concentrations of carbon monoxide (CO) and total organic carbon (TOC) are extremely variable at some operating schedules of combustion boilers. The variability of these concentrations indicates that there are unstable aerodynamic conditions in the combustion device. The causes of this aerodynamic instability have been studied. The mode with stable aerodynamic conditions, for which emission concentra‐ tions of CO and TOC are relatively stable, has been determined.

Thermal Treatment of Wood for Mitigating of Climate Change

Among individual techniques of wood treatment, there are highly significant differences in the greenhouse gas balance. Greenhouse gases have, according to the currently adopted global convention, a major impact on global warming and climate change. Nevertheless, there are also sceptical opinions on the scientific basis of such concept. As well as the natural processes of tree growth and the end of their life cycle, the wood processing technologies also affect the balance of greenhouse gases on Earth. The current natural forest without human intervention does not have to reduce greenhouse gas emissions definitely, but can also be the source of their emissions. Also, technological, particularly thermal, processes have different contribution to the production of greenhouse gases. The submitted paper presents the context of warming and cooling of the Earth during its development with a concentration of carbon dioxide in the atmosphere. Further, the indicative greenhouse gas balance, respectively, CO2 generated at thermal wood processing processes, are analysed.