Evaluating the flow rate and composition of wastewater in St. Petersburg

Summary

The wastewater disposal system of St. Petersburg and its suburbs is specified by receiving and handling large amounts of surface run-off (both stormwater and melted snow) as well as infiltration flows that result from the high ground water level. Regulating the incoming surface run-off is very expensive, whereas investments into the wastewater treatment technologies are used more efficiently. Monitoring the quality of effluent discharged into the surface water bodies is carried out in compliance with the recommendations of Helsinki Commission on Baltic Marine Environment Protection. Basing on the results of three years operating St. Petersburg advanced wastewater treatment plants graph (probability density of the measured parameter values) of the flow rate and composition of the incoming wastewater and treated effluents were developed. Separate assessment of the measurement results in dry and rainy weather was suggested. The necessity of limiting the capacity of the treatment facilities and setting the maximum permissible inflow at the wastewater treatment plants is shown; the excess flow shall be bypassed and treated according to the emergency flood protection plans.

Key words

cleansing , water disposal , wastewater flow rate , wastewater composition , pollution index

Deterioration of sewage tunnels and in-line structures as a result of microbiologic corrosion

Summary

The process of microbiology corrosion of sewers and structures was considered; corrosion protection is a most expensive issue in operating wastewater facilities. General cost of rehabilitating corroded structures amounts to billions euro annually. The present-day concept of a complicated microbiologic corrosion process affected by a great number of different factors such as higher turbulence, and as a result high degree of wastewater flow degassing, is presented. The main indicator of the problem, i. e. concentration of hydrogen sulfide in the ambient air of the structure, is determined. The results of sewer wells inspection in St. Petersburg and their analysis are presented. The high rate of corrosion and extreme operating conditions of No. 10 sewer well are recorded.

Key words

wastewater , sewer , microbiologic corrosion , reinforced concrete