Monitoring of Ambient Air and Air Inside a Surge Chamber

Abstract

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.