Joint Australian-German Project: Phosphorus removal and recovery from waste water by crystallisation Final report

The joint project dealt with the further development of 'crystallisation' with seed crystals for phosphorus removal. During the project especially experiments with the Australian fluidised bed technique were carried out which led to a hybrid process: the 'German' Calcite is used as a seeding material and the 'Australian' MgO as a reagent for pH-adjusting. Using this system favourable results were obtained for the Australian Ca-deficient water as well as for German domestic waste water in batch and long-term experiments. The use of dolomite instead of MgO was less effective, on the other hand. Further experiments regarding the influence of the Ca-content were carried out. It was shown that a remarkable improvement could be achieved also with addition of Ca"+"+-ions up to a concentration of 200 mg/L Ca. But, the Calcite process seems to have two advantages: less consumption of chemicals, i.e. cheaper running cost and no increase of the Cl"--concentration in the water, which is of course no question if the water is discharged into the ocean, the Calcite process is much easier to handle, because after putting the Calcite into the crystallisation unit it must not be replaced for at least one year. Additionally experiments applying ultrasonic for a further enhancement of the crystallisation method were carried out and yielded a considerable improvement of the phosphorus removal efficiency. (orig.)SIGLEAvailable from TIB Hannover: DtF QN1(71,18) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman