Hana Škrobánková

Possibilities of municipal solid waste incinerator fly ash utilisation

Properties of the waste treatment residual fly ash generated from municipal solid waste incinerator fly ash were investigated in this study. Six different mortar blends with the addition of the municipal solid waste incinerator fly ash were evaluated. The Portland cement replacement levels of the municipal solid waste incinerator fly ash used were 25%, 30% and 50%. Both, raw and washed municipal solid waste incinerator fly ash samples were examined. According to the mineralogical composition measurements, a 22.6% increase in the pozzolanic/hydraulic properties was observed for the washed municipal solid waste incinerator fly ash sample. The maximum replacement level of 25% for the washed municipal solid waste incinerator fly ash in mortar blends was established in order to preserve the compressive strength properties. Moreover, the leaching characteristics of the crushed mortar blend was analysed in order to examine the immobilisation of its hazardous contents.

Conditions for energy generation as an alternative approach to compost utilization

Very strict limits constrain the current possibilities for compost utilization in agriculture and for land reclamation, thus creating a need for other compost utilization practices. A favourable alternative can be compost utilization as a renewable heat source – alternative fuel. The changes of the basic physical–chemical parameters during the composting process are evaluated. During the composting process, energy losses of 920 kJ/kg occur, caused by carbohydrate decomposition (loss of 12.64% TOC). The net calorific value for mature compost was 11.169 kJ/kg dry matter. The grain size of compost below 0.045 mm has the highest ash content. The energetic utilization of compost depended on moisture, which can be influenced by paper addition or by prolonging the time of maturation to six months.

Syngas Production from Pyrolysis of Nine Composts Obtained from Nonhybrid and Hybrid Perennial Grasses

A pyrolysis of compost for the production of syngas with an explicit H2/CO = 2 or H2/CO = 3 was investigated in this study. The composts were obtained from nonhybrid (perennial) grasses (NHG) and hybrid (perennial) grasses (HG). Discrepancies in H2 evolution profiles were found between NHG and HG composts. In addition, positive correlations for NHG composts were obtained between (i) H2 yield and lignin content, (ii) H2 yield and potassium content, and (iii) CO yield and cellulose content. All composts resulted in H2/CO = 2 and five of the nine composts resulted in H2/CO = 3. Exceptionally large higher heating values (HHVs) of pyrolysis gas, very close to HHVs of feedstock, were obtained for composts made from mountain brome (MB, 16.23 MJ/kg), hybrid Becva (FB, 16.45 MJ/kg), and tall fescue (TF, 17.43 MJ/kg). The MB and FB composts resulted in the highest syngas formation with H2/CO = 2, whereas TF compost resulted in the highest syngas formation with H2/CO = 3.

A survey of heavy metals in municipal wastewater in combined sewer systems during wet and dry weather periods

During wet weather, combined sewer system overflows affect the quality of water in watercourses. For planning overflows, the lowest possible load of priority substances according to Directive 2008/105/EC is crucial and the knowledge of variability in concentrations of elements in the sewer system is necessary. The behaviour of heavy metals in a sewer system was observed in the course of dry weather flow (DWF) and wet weather flow (WWF). We found, from the comparison of concentration medians for the WWF and DWF that during wet weather periods, an increase in the concentrations of As, Cr, Cd, Pb, Mn and Fe occurs in the sewer system and the effect of nonpoint sources manifests itself. Zn, Cu and Ni concentrations decreased during wet weather periods, and Hg concentrations did not significantly change. During the WWF period, a considerable nonhomogeneity of the sewage system was demonstrated.

Utilization of carbon produced by torrefaction of grass for energy purposes and related risks

Nine species of perennial grasses were studied as a possible raw material for energy production. Torrefaction at 200 degrees Celsius was used for production of biochar. Values of H/C ratio in individual species were determined in order to estimate the degree of thermal transformation. The attention was paid to the influence of inorganic components on the slagging and fouling. The water leaching was tested as a mean for decreasing the content of alkalies. Mineral phases present in biochar were determined by X-ray diffraction. The torrefaction process appears to be suitable for preparation of relatively high-quality fuel from grass. The content of risk alkalies can be minimized by water leaching.

Possibilities thermal utilization of solid char from pyrolysis of municipal solid waste

Requirements for quality of solid char from pyrolysis of municipal solid waste were studied from the point of view of possible utilization for combustion. Laboratory tests of pyrolysis were carried out with samples of municipal solid waste with various moisture. Mineral phases in solid char were determined by X-ray diffraction. Behavior of hazardous elements during pyrolysis was studied and possibility to control selected risk elements by technical means was proposed.

Ecotoxicity of Nanomaterials on the Basis of Clay Minerals

This article deals with the verification of ecotoxicity of nanomaterials on the basis of selected clay minerals (montmorillonite, kaolinite) and quartz as a reference substance. The ecotoxicity was determined by the inhibition of marine bacteria Vibrio fischeri, with relationship to the particle size and concentration of minerals in water leachate prepared according to Council Decision 2003/33/EC. Statistically significant dependence between inhibition of Vibrio fischeri and the concentration of minerals in water leachate was found for montmorillonite.

Possibilities of the utilization of char from the pyrolysis of tetrapak

Since the cellulose used in the production of tetrapak is of very high quality, the char generated during pyrolysis should be influenced mainly by the pyrolysis temperature. This article aims to determine the chemical composition of biochar prepared at the temperatures of 400, 500, 600 and 700 °C and its environmental properties determined by the presence of organic compounds with toxicity and relatively high mobility in the environment. The analytical pyrolysis of char was used to identify the following groups of organic compounds: alkanes, cycloalkanes, alkenes, cycloalkenes, alkynes, alkadiens, ethers, alcohols, nitrogen compounds, nitrils, ketones and aldehydes, compounds containing phenols, furans, benzofurans, PAHs (polycyclic aromatic hydrocarbons), carboxylic acids, compounds containing benzenes and markers indicative of the presence of synthetic polymers (polyethylene layers, a part of dyes, antioxidants, stabilizers), and fragments of cellulose. Concerning the use of char as a soil conditioner, its ecotoxicity was monitored (Folsomia candida) by monitoring its addition to the artificial soil (char addition: 0.5, 1, 2.5, 5, 10, 15, 20, 50 and 100%). The lowest reproduction inhibition of Folsomia candida is caused by biochar prepared at the temperature of 400 °C and 700 °C, but it is not suitable for the agricultural application, the concentration of PAHs is three times higher than the EBC limit. Low-density polyethylene which is present in the aseptic box in concentration of 6%, can degrade biochar so that it cannot be used as a soil amendment. The results of the char analyses show that the pyrolysis temperature is a decisive factor in the applicability of biochar.

The influence of pyrolysis temperature on the chemical composition and the energy properties of char from tetrapak

The chemical composition of char obtained from tetrapak cardboard was monitored in dependence on pyrolysis temperature ranging from 400 to 700 °C together with its influence on energy parameters (calorific value). The highest calorific value 27–28 MJ/kg was determined for char obtained at a temperature of 400 °C, which is caused by the highest content of hydrocarbons (alkanes and alkines) and the lowest content of undifferentiated organic matter. The highest homogeneity of chemical composition of char was found for the temperature of 600 °C.

Influence of Refused Glass on Thermal Properties of Municipal Waste

It is important to reduce the amount of municipal waste deposited in landfills, Czech Republic, therefore, puts more emphasis on the recovery of mixed municipal waste, which oblige and EU regulations. Production of solid alternative fuel that is suitable also due to less consumption of fossil fuels, is one of the uses of mixed municipal waste (Waste to Energy). A relatively high proportion of glass in mixed municipal waste is a major problem in the production of solid alternative fuel. The glass contained in the solid alternative fuel can be the cause of formation incrusts on heat transfer surfaces in combustion plants. For all examined types of glass, it was found that the melting temperature of the muffle furnace was 750 ° C. When using the method (ISO 540) for determining the temperature of softening , melting and flow showed no effect of the amount of glass in the ash, but the melting point was significantly higher (around 1,200 °C).