JultikaUniversity of Oulu repository

Phosphorus is a vital element in human’s lifecycle. It is required for humans and for other organisms to live. Life activities of some of these organisms cause big problems for humans. Eutrophication process is caused by excessive income of phosphorus and nitrogen to natural water resources. The main aim of this project was to test flotation unit together with coagulants and flocculants for removing of phosphorus from wastewater in a water basin of water reservoir Švihov. Research consisted of laboratory analyzes with subsequent verification of the results in the field. Coagulants and flocculants were tested, using conventional jar tests. For these tests were used wastewater from target wastewater treatment plant with artificial addition of phosphate in the form of KH2PO4. It was done for better visibility of the coagulation results. Flotation experiments were done on a pilot scale flotation unit, provided by the KUNST company, on wastewater treatment plant of the Pacov city. Using jar tests the best available combination of coagulant and flocculant was found (FeCl3 and 827 BS with dosage of 1.25 mg/l for both of them). Different dosages of coagulants and flocculants were assessed, basing on subsequent analyses. Was measured pH value, as it is critical value for the environment and it cannot be less than 6. Also assessment was based on residual phosphates concentration, traces of aluminum and iron from coagulants and COD value. During subsequent flotation tests was found that at certain ratio of Fe/P, there is additional consumption of coagulant in the sampling water. We supposed, that it happened because of breakthrough point for inorganic phosphorus, which is situated between Fe/P ratios of 2.6 and 4.6. It is important to conduct additional experiments on less equipped treatment plants in the area, where effectiveness of application of flotation unit, together with chemicals can be determined better for these territories and conditions. Together with additional studies informative conclusions could be done.