Microbial Processes in the Rhizosphere of Constructed Wetlands

Ecological Water Treatment Technologies (EWaTT)

Cross section of a wetland Bacteria in the environment are constantly exposed to oxygen variations and gradients as they occur in planted systems. In planted systems, the plants provide the area around their roots, the rhizosphere with root exudates such as sugars, alcohols, organic acids, and amino acids that stimulate growth of the microbial communities responsible for the biodegradation of organic pollutants. In addition, the plants transport oxygen to the roots stimulating aerobic processes. We hypothesize that pharmaceutical micropollutants can be efficiently removed by constructed wetlands from the municipal wastewater stream. For this reason, several planted systems running in our department such as planted fixed bed reactors (PFR), small scale horizontal-flow constructed wetlands (CW, 1 m length) as well as four pilot-scale horizontal-flow constructed wetlands (6 m length) will be running with different pharmaceutical compounds as sole external C-source. Bacteria capable to degrade these compounds will be isolated, identified and physiologically characterised. In addition, catabolic pathways present in the isolate will be identified. Using real time PCR-based molecular biology will the allow monitoring the activity of these catabolic genes in the planted systems running under certain process conditions.

Adaptive mechanisms of microorganisms such as membrane phospholipid fatty acid (PLFA), the release of membrane vesicle (MV), changes in the cell surface hydrophobicities and biofilm formation will be analyzed and used as biomarkers for the characterization of microbial communities in bacterial pure cultures as well as in environmental samples with special emphasis to soils contaminated with organic hydrocarbons.