The project of wastewater treatment facilities for Molodezhnoe Settlement of the Kurort District of Saint-Petersburg

Summary

The project of the wastewater treatment facilities for Molodezhnoe Settlement of the Kurort District of Saint-Petersburg is presented. The wastewater treatment facilities include: the main pumping station, a combined mechanical wastewater treatment unit, an equalizing tank, a bioreactor (aeration tank operating the technology of nitri-denitrification) for enhanced nitrogen removal, a membrane bioreactor, an effluent UV-disinfection plant, a screw press for excess activated sludge dewatering. Separation of activated sludge and effluent is provided by three blocks each containing 8 membrane filtration modules each with a capacity of 104 m³/day. In the given project the membrane bioreactor acts as a secondary settling tank and tertiary treatment facilities. To provide for enhanced phosphorus removal aluminium sulphate is dosed at the biological treatment stage. Disinfected effluent is discharged through the outfall into the Gulf of Finland. Dewatered excess activated sludge is transported by trucks to the sludge incineration plant of the Northern Wastewater Treatment Plant. Gas emissions generated in the process of wastewater treatment are cleaned in a sorption-plasmacatalytic unit and a biofilter. The technology designed in the project provides for enhanced treatment of wastewater and gas emissions resulting in the significant improvement of the environment in the Kurort District of Saint-Petersburg.

Key words

wastewater , membrane bioreactor , comminuting screens , combined mechanical treatment facilities , biological treatment plant , enhanced wastewater treatment , gas cleaning unit

Advanced solutions for the reconstruction of small-scale wastewater treatment facilities: design and calculation

Summary

The advanced solutions proposed for the reconstruction of small wastewater treatment facilities that contain biofilters are considered. The peakpoint of designing and constructing biofilters occurred in the 1960–1970s. At present biological filters are often used for wastewater treatment. It is proposed to use them again as the basic treatment facilities. These structures, as a rule, are structurally reinforced concrete tanks; so it is advisable to develop new process flow schemes taking into account the use of existing structures. Three process flow schemes with different combinations of nitrification and denitrification zones are considered. Graphic results of sanitary and technical analyses of a number of indicators are presented on the basis of which sufficient purification efficiency is shown that allows discharging effluents into fishery water bodies. A method for calculating biofilters for specific media materials is proposed. It is concluded that the height of the structure depends not only on the required level of purification, the parameters of the incoming water but also on the type and size of the media material. The proposed process flow schemes will provide for the wider use of biofilters both in the reconstruction of existing and in the design of new treatment facilities.

Key words

reconstruction , wastewater , nitrification , biofilter , ammonia nitrogen , denitrification , biofilm , enhanced wastewater treatment , small-scale wastewater treatment facilities