Experimental studies have been carried out to determine the sludge index of activated sludge used in the process of biological wastewater treatment on aerotanks at various doses of sludge. The possibility of changing the sedimentation properties of activated sludge when using its electrical treatment is analyzed. It is shown that the electrotreatment of returnable activated sludge together with aeration leads to a decrease in the value of the sludge index, as well as an improvement in the quality of the treated water after settling. pretreatment of activated sludge in an electrolyzer with aeration allows biological wastewater treatment in an aerotank with increased doses, as well as to increase the flocculating properties of sludge in relation to suspended solids.

Keywords: household waste water, biological treatment, activated sludge, aerotank, sedimentation, sludge index, electrical treatment, aeration

The parameters of the mixers widely used in the practice of water treatment are given. A fundamentally new design of the mixing unit is proposed, which provides a process of rapid and complete mixing of reagents in a thin layer of a rotating flow of a pre-created water-air mixture using the method of concentrated coagulation. At the same time dispersion of air bubbles is carried out. A detailed description of the design, operating principle and basic design parameters of the mixer used in the mixing unit.

Keywords: natural water, coagulant, mixer, concentrated coagulation, aeration, velocity gradient, rotational motion