Method of sewage biological purification and an equipment for performing this method

A biological sewage purification system, for performing the steps of mechanically pretreating of the sewage including passing through a purification process of biological removal of pollution with activated sludge and under aerobic and/or anoxidic and/or anaerobic conditions;

• separating the mixture of purified water and activated sludge by sedimentation, such that the activated sludge is returned to the purification process and the purified water is pumped off at determined time intervals;
• and interrupting the separating step with intensive stirring, whereafter the separating step continues, the system comprising:
• a vessel, having an inlet zone and an activation space;
• a feeding tank having a bottom located inside the vessel;
• a basket in the inlet zone, for performing the mechanical pretreatment with a preconnected inlet of purified sewage, the basket including aerating elements;
• a feed roll connected by a feed adaptor to the activation space;
• and
• a recirculation sludge pump for pumping the activated sludge from the bottom of the feeding tank to the inlet zone adapted to remove the purified sludge;
• wherein the feeding tank (6) is connected, either directly or indirectly, to a source of intensive stirring (17), the feeding tank (6) is also connected to a pump (25) for lowering an operating level, the pump (25) having an outlet (26) in fluid communication with a withdrawal (16) of the feeding tank (6), and the feeding tank further includes a suction branch (20), arranged for sucking off floating impurities from the lowered operating level (24), connected to a suction pump (22) whose outlet is connected to above the level of the inlet zone (2).