Apparatus for mechanical purification of waste water

Apparatus for mechanical purification of waste water, particularly of water which has undergone a biological purification, comprising a vessel for a supply of waste water;

• a hollow support;
• at least one hollow drum-shaped frame rotatably mounted on and surrounding said support, said frame having at least one opening at least a portion of which is immersed into waste water in said vessel during each revolution of said frame about said support;
• filter means including a foraminous filter mounted in said frame and having an inner side overlying said opening and an outer side which intercepts impurities contained in waste water entering said frame by way of said filter and said opening;
• means for withdrawing the thus purified water from the interior of said frame;
• a source of clean water;
• a feeding device operable to supply clean water from said source into the interior of said frame and having a stationary portion arranged to direct clean water against successive portions of the inner side of said filter as the filter rotates with said frame around said support;
• and suction generating means including a portion adjacent to the outer side of said filter opposite said portion of said feeding device and actuatable to collect impurities which are expelled from the filter by clean water in response to operation of said feeding device, said portion of said feeding device cooperating with said portion of said suction generating means to maintain the permeability of said filter above a preselected minimum acceptable value for extended intervals of time.