USE OF MAGNET TECHNOLOGY FOR PHOSPHATE ELIMINATION FROM MUNICIPAL SEWAGE

The present report describes the set-up and first operation results of a novel carousel magnetic separator. This carousel magnetic separator is suitable for continuous separation of magnetized particles from wa ter. Continuous operation is achieved by a segmented rotating separati on matrix. This matrix also allows the use of low-cost permanent magne ts, by means of which magnetic fields of up to 0.5 T can be generated without energy consumption. The suitability of a first prototype of th is carousel magnetic separator was tested for elimination of magnetite -containing iron phosphate and iron hydroxide flocs. These flocs resul t from conventional precipitation/ flocculation of municipal sewage wi th FeCl3 and the addition of magnetite particles generated by wet-chem ical processes. First results demonstrate that the carousel magnetic s eparator can reduce phosphate concentrations of up to 14 mg/L PO43--P in the inlet to below 14 mg/L PO43--P in the outlet at filtration rate s of about 40 m/h. Magnetite dosage in the range of 50 mg/L affects ph osphate precipitation positively via a slight reduction of the precipi tant volume. However, the total amount of chemicals required for phosp hate elimination is increased by the substances needed for magnetite p roduction. Therefore, a further reduction of magnetite dosage must be achieved.