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.

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.

Behavior of metals in a combined wastewater collection system in Ostrava, Czech Republic.

In combined wastewater collection systems, the concentrations of metals and the form of metal occurrence (dissolved form and bonding of metals to total suspended solids) influence the efficiency of capturing metals into sludge in wastewater treatment plants. The variability of metal concentrations was determined for 12 sampling sites during dry weather periods (DWP) and wet weather periods (WWP). Wastewater during DWP contain in dissolved form 77% of cadmium, 75% of nickel, 66% of arsenic, 57% of manganese and 50% of zinc and copper. Other metals are preferably bound to suspended particulates: 65% of chromium, iron, vanadium, mercury and 91% of lead. Comparison of metal concentrations in wastewater during DWP and WWP can be used to determine non-point source contributions. During WWP, metal concentrations increase by 24 to 25% for cadmium and zinc, 22% for nickel and 18% for copper. Urine and feces are responsible for a very small portion (<15%) of the total content of metals. Households are the main source of cadmium and copper (64% of total concentrations of these metals in wastewater).

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.