FIELD: biological purification of sewage. SUBSTANCE: plant has aeration reservoir for receiving and aeration of sewage water and sediments, and device for generating air bubbles to provide sewage water delivered for purification with air and/or oxygen in form of air bubbles. Plant has oxygen-free and anaerobic reservoir installed at outer side of aeration reservoir for removal of nitrogen and extraction of phosphorous from liquid with sediment in suspension, and settler installed from outer side of oxygen-free and anaerobic reservoir for settling sediment suspended in liquid. According to invention, each stage of purification, namely, oxidation of organic substances, removal of nitrogen and phosphorus under oxygen free and anaerobic conditions and settling of microorganism are carried out in one multiple-tube reactor. EFFECT: reduced overall dimensions of construction, provision of optimum conditions for effective removal of organic substances, nitrogen and phosphorus at minimum distance of running of sewage water. 23 cl, 4 tbl, 1 dwg, 2 ex
