Abstract:The previously received results of individual processes of hydrodynamic and alkaline disintegration were decisive significant for the conducted research task. The combination of hydrodynamic cavitation (30 minutes duration of the process) and alkaline (pH ≈ 9) to the destruction of activated sludge caused a significant release of organic matter about 1383 mg/dm 3 in comparing to individual processes. Such increase in the SCOD value resulted in a significant growth the efficiency of biogas yield in a two-stage mesophilic-thermophilic processes. The increase in yield was from 26 to 38% depending on the volume of disintegrated sludge. The effect of the two-stage fermentation resulted activated sludge hygienisation. The microbiological analysis of the influence of the fermentation with the different volume of hybrid disintegrated sludge was based on microbiological indicators: Salmonella spp. and coliphages. The obtained results prove the effectiveness of the two-stage digestion process compared to single mesophilic fermentation which not always completely eliminates the above indicators.
The paper presents a new method of estimation of the effect of a river on the ground waters of the adjacent area, different than the one used so far and based on the application of geostatistical methods and the fractal theories. An analysis was performed of a 14-year series of daily observations of ordinates of water level in the river Oder and ordinates of ground water levels in five piezometers situated at various distances from the riverbed, within the range from 120 to 1000 m. The first stage of the analysis was devoted to evaluation of the applicability of classical statistical measures. It was found that only selected ones display a relation with the distance. Those included maximum value, ranges, coefficients of variation, and variances. The remaining ones proved to be non-applicable. The next stage was the analysis of correlations between the parameters of semivariograms of ground water levels in the piezometers and the parameters of semivariograms of water levels in river Oder. It was demonstrated that the values of each parameter were related with the distance of a given piezometer from the riverbed. This means that they are useful for the estimation of the effect of the river Oder on the adjacent areas, as are the fractal dimensions.
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