NOVELTY - Devices used in the urban aeration plants for complete biochemical oxidation of the domestic sewage and industrial waste waters with similar compositions, are new.    USE - Sewage purification; installations for biochemical purification of the sewage.    ADVANTAGE - The device ensures reduction of the installation overall dimensions, the ease of operation of the aeration system, the stable and of the high quality purification of the water, the averaging of the waste waters consumption and concentrations of the polluting impurities, the stable indexes at the outlet of the installation by the residual value of the biochemical oxygen demand.    DETAILED DESCRIPTION - Devices used in the urban aeration plants for complete biochemical oxidation of the domestic sewage and industrial waste waters with similar compositions.    he unitized modular installation for biochemical purification of the sewage contains:    (a) the rectangular shape body made in the form of the tank, which includes the built-in unit of the mechanical purification;    (b) the sectional aerotank with the carriers of the adherent microflora made in the form of the removable cassettes with consolidated barbed polymeric components and the aeration system fixed on them;    (c) the echo depth-sounder;    (d) the after purification bioreactor;    (e) blocks of dephosphorization and disinfection of the sewage; and    (f) the systems of aeration and recycling of the active sludge.    The aerotank is coupled with the secondary settling tank, which has a layer of suspended sediment, fulfills the functions of the neutralizer and has the submerged spillway.    In the aerotank, which functions as the aerotank-displacer, the hydraulic mode is maintained ensuring the multiple passage of the subjected to purification water through the removable cassettes.    The technical result of the invention is reduction of the installation overall dimensions, provision of the ease of operation of the aeration system, provision of the stable and the high quality purification of the water, the cost averaging of the consumptions of the waste waters and the concentrations of the polluting impurities, provision of stable indexes at the outlet of the installation by the residual value of the biochemical oxygen demand (BODcomplete) at the level of 3-5 mg O2/l, for the suspended substances - up to 3-5 mg/l and for the nitrogen group: ammonium nitrogen - up to 4.4 mg/l, nitrates nitrogen - up to 9.1 mg/l, nitrites nitrogen - up to 0.08 mg/l.