摘要:
A multi-layer filter, wherein a filter medium inside a rotatable or swingable horizontal drum (3) is formed in a multi-layer shape with a single or a combined grading, specific gravity, and characteristic of filter medium desirably according to the purpose of treatment and washed with raw water while rubbing the filter medium by rorating or swinging the drum (3) so that contaminent can be removed to surely recover the filter medium at each layer, a raw water inflow tube (5) and a filtered water outflow tube (7) are formed in a shape of double-pipe, a sandproof means and a filter medium agitating means are installed on both or either of the tubes, and a cleaning means and an adhesion prevention means for preventing seaweed from adhering to the inside wall of the drum (3) are installed between a filter net (15) and the inside wall of the drum (3), whereby a structure can be simplified, controllability and maintainability can be facilitated, production cost and maintenance cost can be reduced, and durability and filtering efficiency can be increased.