Study of the dynamics of surface runoff composition of the urban lands

Summary

The qualitative composition of surface runoff of urban lands is affected by significant fluctuations. Studying its dynamics, determining possible regularities and causes of these fluctuations can be conveniently carried out with the use of the mathematical apparatus of the time series analysis. The procedure of seasonal decomposition was applied to the time series of monthly dynamics with the annual periodicity of seasonal fluctuations with the help of the multiplicative model. The results of the quantitative chemical analysis of surface runoff at the «XXII Party Congress» outfall of the Samara municipality for 2004–2016 were used as benchmark data. As a result of the performed analysis the occurrence of the seasonal regularities of the surface runoff composition changes was determined. The seasonal indices of 15 effluent quality parameters were determined: BOD_full, suspended solids, mineralization, chlorides, sulfates, ammonium ion, nitrite ion, nitrate anion, phosphates (as phosphorus), total iron, copper, zinc, aluminium, oil products, and detergents (anionic). Based on the given seasonal decomposition of the time series the qualitative assessment of the effect of the trend, seasonal and random components on the unsteadiness of the surface runoff quality parameters was performed.

Key words

surface runoff , wastewater composition , outfall to the water body , multiplicative model , time series , seasonal decomposition , seasonal index

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