WATER PURIFICATION BY PASSING IMPURE WATER INTO VESSEL AT LOW VELOCITY, THROUGH LAYER OF RISING GAS BUBBLES AND THEN DOWN THROUGH FILTER BED

摘要

The invention relates to a liquid treatment method and apparatus for removing impurities from a liquid stream, comprising forming a zone of micro gas bubbles from a source (3) across substantially the whole surface area of a treatment vessel (12) which is situated above a filter bed (13), passing liquid to be treated into the vessel (12) above the inlet (3) for the air whereby the liquid passes in countercurrent mode through the air bubbles.