Implementation of the technologic solutions focused on the prevention of water body eutrophication (best practices of SUE «Vodokanal of St. Petersburg»)

Summary

SUE «Vodokanal of St. Petersburg» has been the biggest water user in the Baltic Sea coastal zone; therefore the enterprise is obliged to meet the regulations of effluent discharge into the water bodies. The qualitative composition of the discharged effluents is regulated not only by the Russian standards but also by the international recommendations including the Helsinki Convention on the Protection of the Marine Environment of the Baltic Sea. Russia endorsed the Convention in 1998. Since that moment Saint-Petersburg and Vodokanal have been aiming at reducing raw wastewater discharges into the Baltic Sea and meeting the regulations of the effluent quality. The best practices of SUE «Vodokanal of St. Petersburg» implementing the technology of nutrients removal with the purpose of preventing water body eutrophication are presented. The international experience was studied; the laboratory and full-scale tests of different technologies of enhanced phosphorus and nitrogen removal were conducted. Kreal technology and its limitations revealed in the process of operation are described alongside with the process schemes designed by the University of Cape Town (UCT-Process) and Johannesburg University (JHB-Process) and implemented with the purpose of improving the efficiency of wastewater treatment. In order to provide for the stable phosphorus concentration in the effluent according to the regulations chemical removal of phosphorus was introduced. Starting from 2011 Saint-Petersburg has been fully meeting the HELCOM recommendations.

Key words

treatment facilities , wastewater , aluminium sulphate , total phosphorus , total nitrogen , eutrophication , ferrous sulphate

Specific characteristics of phosphorus removal in biological wastewater treatment

Summary

It is shown that in using chemicals for deep phosphorus removal in biological wastewater treatment or effluent polishing one must take into account the effect of added metal ions on biological treatment process. A technique is suggested for estimating chemical consumption depending on the selected flow scheme of biological and chemical treatment; adjusting factors with account of this effect are given.

Key words

wastewater , biological treatment , aluminium salts , chemical treatment , biogene substances , phosphates , total phosphorus , chemicals , ferrum salts

Phosphorus compounds in municipal wastewater

Summary

The analysis of the results of determining phosphorus compounds in wastewater at the treatment facilities is presented. In order to remove phosphorus compounds different methods of municipal wastewater treatment are used. The efficiency of eliminating some or other phosphorus forms depends on the technology used. The ratio of separate phosphorus forms in raw sewage differ much from effluent; therefore their impact on the water body also differs even if the discharged effluent quality is meeting the maximum permissible concentration of phosphates. Addition of chemical into wastewater provides for the fast and reliable removal of phosphates. The efficient reduction of total phosphorus and phosphates occurs only under the combination of biological and chemical wastewater treatment, or under the use of the modified biological treatment with alternating aerobic and anaerobic conditions of activated sludge retention.

Key words

wastewater , biological treatment , chemical treatment , phosphates , total phosphorus , biological and chemical treatment