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Gewählte Master / Diploma Thesis:

Robert Ernst Lauschmann (2012): Vorgeschaltete Phosphorfällung bei Pflanzenkläranlagen.
Master / Diploma Thesis - Institut für Siedlungswasserbau, Industriewasserwirtschaft und Gewässerschutz (SIG), BOKU-Universität für Bodenkultur, pp 124. UB BOKU obvsg FullText

Data Source: ZID Abstracts
Abstract:
Constructed wetlands (CWs) with vertical flow systems offer satisfying purification results for organic matter and nitrogen removal. Only the removal mechanism for phosphorus is limited and decreases with time. The object of this research was to determine the applicability of conventional physicochemical phosphorus removal due to precipitation with sodium aluminate at a constructed wetland. The experiment was carried out at a full-scale CW in Oberwindhag in Lower Austria, a two-stage vertical flow CW with intermittent loading with a size of 60 person equivalent. It was attempted to reach the required effluent concentration of 1.6 mg/l PO4-P with pre-precipitation. The sedimentation of the flocs should take place in the chambers of the primary treatment. The plant was already in operation for 3 years without measures for phosphorus removal. The results showed no significant changes of the phosphate concentrations in the primary treatment. The first bed (240 m²) had an abatement rate of almost 36 %, whereas the second bed (60 m²) did hardly remove any phosphorus. Then the pre-precipitation with sodium aluminate was activated and 3 different dosages were investigated. Satisfying results in the preliminary treatment chambers were not obtained until a high dosage of ß = 3,5 was applied. In addition the concentration at the outflow of the reed beds was sometimes higher than at the inflow. Then it was attempted to optimize the conditions of the injection of the precipitation agent into the wastewater stream by building in a siphon like structure into the pipe. The measurements showed a slight improvement but it is assumed that the variability of the phosphorus concentration at the inflow and competing reactions of dissolved substances with the coagulant inhibit better results. Nevertheless it was possible to demonstrate the possibility to maintain a low outflow concentration of 1.6 mg/l PO4-P at a CW with chemical pre-precipitation.

Beurteilende(r): Ertl Thomas
1.Mitwirkender: Langergraber Günter

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