Experiments with capillary fringes (CF) in quartz sand were conducted. The respiratory activity, cell growth or the biofilm formation by different soil bacteria in the CF were examined. Highest bacterial activity and cell adsorption on the sand particles were detected between the almost water saturated and unsaturated CF-region. Primarily in this transition zone the bacteria strongly influenced the vertical oxygen diffusion and reduced the hydraulic conductivity due to biological clogging.

Two fixed bed reactors for nitrification with either polyethylene/clay sinter lamellas (FBR A) or porous ceramic rings (FBR B) were continously run for treating synthetic saline wastewater. Seawater from Hafen Büsum was used as an inoculums. The performance of the system was evaluated under different operating conditions. A better overall nitrification without nitrite accumulation was observed in FBR B during continuous incubation. However, in term of ammonia (AOR) and nitrite oxidation rates (NOR) that were determined in batch incubations, FBR A revealed a higher AOR and NOR of 6 and 7 mg N L-1 h-1, compared to the AOR and NOR of 5 and 5.9 mg N L-1 h-1 in FBR B, respectively. For studies of the effect of fluctuating salinity on the nitrification, polyethylene/clay sinter lamellas or porous ceramic rings from FBR A and B, respectively, were used as a source of immobilized nitrifiers. Salt concentrations were decreased from 3.5% to 0.03% via 2, 1 and 0.5% and increased from 3.5% to 5, 7 and 9%. A similar result for AOR and NOR during batch incubation was obtained for both substrata in FBR A and FBR B. The salinity changes influenced more the nitrite oxidizing bacteria (NOB) than the ammonia oxidizing bacteria (AOB). Measurement of oxidation rates during changing conditions show that the NORs were always higher than the AORs in all reactors, especially in initial phase. However, NORs were more sensitive to the salinity fluctuation than AORs, especially at lower salinity. The AORs remained constant for 0.5-3.5% NaCl and dropped to 70% and 68.5% after the salt concentration was brought to 0.034 or 5%, respectively. The NORs decreased significantly to 62% and 87.5% of initial rates after the salt concentration was changed to 2 and 5%, respectively. Non-halotolerant nitrifiers reactors with fresh polyethylene/clay as supporting material were inoculated with water samples taken from a "Brackwasser"-location at the North Sea and were continuously run. The salt content in medium was 0% at the start and was then increased up to 10.5%. Increases of the salt concentration in a non-salt-adapted FBR suppressed more to NOR than AOR. When salinity was increased from 0.03% to 0.5, 1 and 2%, AORs remained constant. The AORs were approx. 90% of initial rates after the salt concentrations were increased stepwise to 3.5%, whereas the NORs decreased to 85, 52 and 36% of initial rate after salinity was increased to 1, 2 and 3.5%, respectively.

Die Dissemination von Antibiotika-Resistenzen gilt als eine der größten Bedrohungen der menschlichen Gesundheit des 21. Jahrhunderts. Über die Resistenzsituation in der aquatischen Umwelt ist derzeit noch wenig bekannt. Thema der vorliegenden Arbeit ist es, die Resistenzsituation in fäkal belasteten Oberflächengewässern zu erfassen und verschiedene Abwasserreinigungstechnologien bezüglich ihrer Eliminationsleistung von fakultativ pathogenen und Antibiotika-resistenten Keimen zu bewerten.

Propionic acid is an important intermediate produced during anaerobic degradation of biowaste and a precursor of a large amount of methane. Its accumulation during biomethanation is however a common problem resulting in stagnation phases in biogas production. During this study, the deeper insight into the process of propionic acid degradation was intended by using modern analytical chemistry, standard microbiological approach and molecular biology for describing and explaining the problem.