Effect of selected metal ions on the photocatalytic degradation of bog lake water natural organic matter.

Herein we report the photocatalytic degradation of natural organic matter from a bog lake (Lake Hohloh, Black Forest, Germany) in the presence of 0, 5, and 10 μmol L(-1) of added Cu(2+), Mn(2+), Zn(2+) and Fe(3+). The reactions were followed by size exclusion chromatography with organic carbon detection (SEC-DOC) and by measurements of low molecular weight organic acids. Addition of Cu(2+) had the largest effect of all four studied metals, leading to a retardation in the molecular size changes in NOM: degradation of the larger molecular weight fraction was inhibited leading to reduced production of smaller molecular weight metabolites.

Nitrifying microorganisms in fixed-bed biofilm reactors fed with different nitrite and ammonia concentrations.

Nitrifying bacteria and archaea were fed in fixed-bed biofilm reactors with different nitrite and ammonia concentrations in synthetic and real wastewater. During high nitrite concentrations (rho(NO(2)(-))=5-10mg/L), an increase in the abundance of Nitrobacter species was detected with fluorescence in situ hybridization (FISH), while Nitrospira species disappeared to a large extent. During high ammonia concentrations (rho(NH(4)(+))=60-80 mg/L), a slight increase in ammonia-oxidizing bacteria was obtained, while the abundance of archaebacteria remained unchanged.

A standardized pre-treatment method of biofilm flocs for fluorescence microscopic characterization.

The availability of epifluorescence microscopy opens the door for the visualization of biofilm flocs via the fluorescence staining technique. However, one of the main problems in the application of the method is a missing standardized protocol for sample preparation. In this study, different pre-treatment methods for the simultaneous staining of different sludge flocs components e.