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Introduction. When sewage is transported along sewer pipes, sewer gases are actively formed and released. Special attention (in terms of desorption capacity) should be paid to surge chambers characterized by changes in the flow and flow arrival conditions, as well as by drop flow. The release of sewage gases has an adverse effect on sanitary and environmental safety. Therefore, it is required to control sewage gases’ release and assess the condition of the ambient air and the air in the surge chamber space. Methods. We selected a surge chamber in Cherepovets for monitoring. The experiment included: 1) measurements of sewer gases’ concentrations in the surge chamber and in the ambient air near the hatch; 2) analysis of dissolved hydrogen sulfide concentration in sewage; 3) recording of climate characteristics. Results. Based on the monitoring results, we determined the concentrations of sewer gases in the surge chamber. It has been found that gases leave the chamber in portions, which is due to aerodynamic processes and airing owing to incomplete air tightness. The relationship between the gas concentrations recorded at the same time in the surge chamber and the ambient air is reversed. The analysis of wastewater samples showed that most part of hydrogen sulfide leaves the water medium before wastewater enters the air space of the surge chamber. This is due to the absence of overpressure in the last headrace section. Besides, the maximum allowable concentrations were exceeded manifold both in the chamber and in the ambient air near it. Conclusion. The monitoring results confirm that it is required to develop: methods for assessing the environmental impact of surge chambers; methods for predicting total and one-time maximum emissions in the facilities; recommendations for setting the boundaries of sanitary protection zones around such facilities.

Introduction. Separation chambers are designed and built for separate and partially separate sewerage systems. Their main function is to separate the flow of relatively clean water during heavy rain. This allows the discharge of such water without treatment into water bodies or storage tanks. The approach reduces the load of wastewater treatment plants. To design separation chambers, we need to understand how their design features affect the process of flow separation. It is possible to study the hydraulic characteristics of separation chambers of any design with the help of computer simulation. Two designs of separation chambers were investigated: a circular spillway with a full-scale prototype and a spiral spillway proposed by the authors. Methods. The research was based on simulation in the ANSYS CFX finite element analysis software. For each design, a series of five experiments with different incoming flow rates was performed. Results. Models of two types of separation chambers were developed and qualitatively evaluated. The hydraulic characteristics were established and quantified: the uniformity of the flow discharged for treatment and the spillway discharge coefficient. Conclusion. As a result, a principled approach was formed and tested. Using this approach, it is possible to study the hydraulic characteristics of separation chambers of various designs for their further use in the sewerage system.

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Wastewater transport in sewer networks contributes to the formation and emission of fetid and toxic sewage gases into the environment, one of which is hydrogen sulfide. The emission of gases can have a significant impact on the environment and health of maintenance workers and city residents. The object of the research is the study of the process of hydrogen sulfide emission in the energy dissipation chamber (EDC). The method of two-stage mathematical modeling in the program of finite element analysis ANSYS CFX is applied for the research. Two models have been created, the first one simulates the internal space of the EDC structure itself, and the second one simulates the EDC manhole and the volume of the surrounding air next to it. Mathematical dependences of hydrogen sulfide concentration change at three sections inside the structure are obtained for incoming wastewater flow velocities V = 1 m/s, 1.5 m/s and 2 m/s. The critical flow velocities at which the maximum single threshold limit value will exceed 1 m/s and the threshold limit value of the working area will exceed 1.52 m/s are determined. The methodology for solving the problem of assessing the impact of the EDC object on the environment is formed. The results of the study can be applied in the design of structures for a preliminary assessment and prediction of the impact of a wastewater facility, as well as the selection of the most favorable hydraulic regime.