Following the international trends great numbers of biogas plants were opened during the last few years in Hungary. However this issue presents a number of new questions, including the subsequent use of anaerobic fermentation residues. This endproduct can be applied as fertilizer. Chemical properties of digestate are correspond to the Hungaroan... Regulations. Digestate contains high amount of nitrogen which is present mainly ammonium form and this form can cause root depression and lower germination rates. High ammonium and mineral salt content of digestate increased the water soluble salt content of soil. The added amount of NH4-N transformed to NO3-N while disengage hidrogen ions from the bond. This process caused the decreasing pH. Humus content determination did not show changes. Long term experiments are needed to recognise detail effects.
The proper management of communal sewage sludge is a priority aim in today’s environmental protection. Among the possible technologies one environmentally sustainable sludge treatment technology can be the vermicomposting of communal sewage sludge. Before the successful operational level vermicomposting is absolutely necessary to investigate...the process of vermicomposting in laboratory controlled conditions. In our studies vermicomposting of communal sewage sludge was carried out by comparing two earthworm populations in laboratory. During 6-week experimental period the temperature (with soil thermometer) and the redox potential (with ORP portable device) were measured every other day. The weekly, measured, basis parameters were the compost visual appearance, color and smell, pH (H2O), dry matter content, organic matter content, EC (conductivity), from which the total salt content can be calculated, total nitrogen content, phosphorus content (P2O5), potassium content (K2O), calcium and magnesium content, humus content (H%), determining the humus quality according to Hargitai’s method and dehydrogenase enzyme activity. It can be concluded from the results that the vermicomposting of studied communal sewage sludge has started and keeps going. The basic physical and chemical parameters (e.g. temperature, humus quality and quantity) support the changes. The results of humus quality and quantity which are priority variables of agriculture use show average increasing despite the initial recession. The changes of the important chemical parameters (nitrogen, phosphorus, potassium) in nutrient management were developed favorably. In our presentation the previous laboratory results are described.