To verify the effect of added starch on flowability and pelletization of spruce sawdust, were prepared mixtures with addition of 0, 5, 10, 15 and 20 % (w/w) starch. The measured basic mechanical-physical properties of the individual mixtures have shown that starch improves flowability of the mixture (growing value of the ffc parameter), reduces impact of friction forces on the contact stainless material (reduced wall friction), thus reducing energy demands of the process as regards flow of the mixture through the hopper of a pellet press. High-speed camera simulations, which evaluate the immediate speed of particles during discharge of the hopper, have proved that addition of a material with different distribution of size and shape of the particles (starch) has a favourable effect on the overall flowability of the mixture. When pelletizing a mixture with starch, which has a lower angle of internal friction, the pelletizing pressure in the die is slightly lower and the resulting pellets have a slightly lower density. This feature is compensated by prevailing positive effects of the added starch on the pelletization, where the resulting pellets have higher durability, higher hardness and moisture resistance.

The investigation of the effect of moisture on the release and enrichment of heavy metals during pyrolysis of municipal solid waste is essential. This is important owing to: (i) the increasing amount of metals in the solid product of pyrolysis beyond the normalised level; (ii) the effect of moisture on the overall cost of pyrolysis process; and (iii) the utilisation of pyrolysis products. Seven metals were selected for evaluation: arsenic, cadmium, chromium, mercury, nickel, lead, and vanadium. Pyrolysis experiments were conducted in a steel retort at 650 °C. The municipal solid waste samples with moisture contents of 0, 30, and 65 wt% were investigated. The relative enrichment index and release of heavy metals were evaluated individually for liquid and solid fractions. A consistent trend was observed for the majority of metals investigated. Reductions of relative enrichment index and release, i.e. an increase of volatility, were observed for arsenic, chromium, cadmium, nickel, and vanadium, with an increase of municipal solid waste moisture. Whereas divergent results were obtained for lead and mercury. The effect of moisture on the relative enrichment index and release was greater at 65 wt% moisture than at 30 wt% for lead, and more remarkable at 30 wt% than at 65 wt% for mercury.

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Ten composts produced by composting plants in the Moravosilesian Region (the Czech Republic) were studied from the point of view of their possible utilization for energy production. The parameters relevant for this possible application of low-quality composts were determined: elemental composition (C,H,O,N,S), volatile combustibles, fixed carbon, ash, gross calorific value, moisture, water leachable potassium and chlorine, alkali index, C/N.