Jan Habart

Composition and parameters of household bio-waste in four seasons.

Bio-waste makes up almost half portion of municipal solid waste. The characterization of household bio-waste is important in determining the most appropriate treatment method. The differences in composition and parameters of bio-waste derived from urban settlement (U-bio-waste) and family houses (F-bio-waste) during the four climate seasons are described in this paper. Twelve components and 20 parameters for bio-waste were evaluated. The composition of U-bio-waste was almost steady over those seasons, unlike F-bio-waste. U-bio-waste was comprised mainly (58.2%) of fruit and vegetable debris. F-bio-waste was primarily made up of seasonal garden components. The amount of variation among seasons in both type of bio-waste increased in sequence: basic parameters<macro-elements<potentially toxic elements. Spearmans correlations among proportions of individual components and parameters of bio-waste were found out. Results of this research could be utilized to support another composition and parameters of bio-waste and be suitable for establishing bio-waste processing.

Changes in cadmium mobility during composting and after soil application.

The effect of twelve weeks of composting on the mobility and bioavailability of cadmium in six composts containing sewage sludge, wood chips and grass was studied, along with the cadmium immobilization capacity of compost. Two different soils were used and Cd accumulation measured in above-ground oat biomass (Avena sativa L.). Increasing pH appears to be an important cause of the observed decreases in available cadmium through the composting process. A pot experiment was performed with two different amounts of compost (9.6 and 28.8 g per kg of soil) added into Fluvisol with total Cd 0.255 mg kg(-1), and contaminated Cambisol with total Cd 6.16 mg kg(-1). Decrease of extractable Cd (0.01 mol l(-1) CaCl(2)) was found in both soils after compost application. The higher amount of compost immobilized an exchangeable portion of Cd (0.11 mol l(-1) CH(3)COOH extractable) in contaminated Cambisol unlike in light Fluvisol. The addition of a low amount of compost decreased the content of Cd in associated above-ground oat biomass grown in both soils, while a high amount of compost decreased the Cd content in oats only in the Cambisol.

Utilization of Permanent Grassland for Biogas Production

Permanent grasslands represent undoubtedly an inseparable part of landscape, which has historically both agriculture and environmental importance. Considering restricting agriculture-food-processing production, especially in Central and Eastern European countries, the main aim of European policy is to support mainly environmental function of permanent grasslands. To fulfil non-productive function of permanent grasslands, there is the base of their utilization and harvest of biomass. Therefore, agriculture is also focused on non-food processing production where the first place is taken by energy production.

The Role of Aeration Intensity, Temperature Regimes And Composting Mixture on Gaseous Emission During Composting

The aim of the work was to compare production of N2O during composting with different temperature regimes, different aeration intensity and different input mixture. Two different mixtures of organic material with three levels of aeration underwent the composting process in two temperature regimes. Mixture A contained woodchips, separated pig slurry, fresh grass and tree leaves. Mixture B contained woodchips, tree leaves, grass and urea to optimize C:N ratio. This experiment was carried out in specially designed 70 liter fermentors. Oxygen and nitrous oxide were monitored in the exhaust air as well as pH, NO3− and NH4+ and temperature of solid material. The mixture with urea additive showed high N2O production when kept under low temperature; when the same mixture was kept in higher temperature, production of NO2 was 3 fold lower. However, the mixture without urea addition kept in high temperature shows almost no N2O production. Production of N2O was highest when nitrates concentration increased. Production of N2O is perhaps a by-product of nitrification, but also other pathways may contribute.