Kinetics of autothermal thermophilic aerobic digestion - application and extension of Activated Sludge Model No 1 at thermophilic temperatures.

The application of an ASM1-based mathematical model for the modeling of autothermal thermophilic aerobic digestion is demonstrated. Based on former experimental results the original ASM1 was extended by the activation of facultative thermophiles from the feed sludge and a new component, the thermophilic biomass was introduced. The resulting model was calibrated in the temperature range of 20-60 degrees C.

Application of activated sludge model no. 3 for the modeling of organic matter biodegradation at thermophilic temperatures.

The primary aim of our research was to investigate the applicability of activated sludge models (ASM) for aerobic thermophilic processes, especially autothermal thermophilic aerobic digestion (ATAD). The ASM3 model (Gujer et al., 1999) theoretically seems to be the most suitable, because storage plays an important role in a batch-feed cycle system like ATAD.

Nitrification of high-strength ammonium wastewater by a fluidized-bed reactor.

A laboratory-scale fluidized-bed reactor with an external aeration loop was used for nitrification of high-strength ammonium wastewater (up to 500 mg NH4-N/L). The results demonstrated that the system is capable of handling ammonium removal rates of up to 2.5 kg NH4-N/m3 x d, while removal efficiencies were as high as 98% and independent of the applied ammonium loading rates.

Identification of factors contributing to degradation in autothermal thermophilic sludge digestion.

A laboratory scale ATAD reactor (6 days SRT, 24 h feed cycle) was operated at quasi steady-state conditions with real waste activated sludge feed. Hydrolysis tests of waste activated sludge demonstrated that 10% of feed suspended matter is hydrolysed practically instantaneously and 20-30% of all fed suspended matter is dissolved after 60 minutes in tap water and in cell free reactor liqueur equally. Respirometric, VSS and COD concentration data served as basis for calibration of a simple VSS based kinetic model.

The evaluation of dioxin emissions from pilot scale incineration of organochlorine compounds.

Formation of the dioxins was investigated in case of two fuel types (kerosene-dichlorobenzene and kerosene-dichloroethane) on a pilot scale liquid waste incinerator. It was determined the effect of the molecule structure (aromatic, aliphatic) and Cl content (1, 3 and 6%) of the liquids and the combustion parameters (O2 content, residence time and temperature). In some experiments particulate matters (fly ash and soot) were injected.