Detecting the places of corrosive gas emissions from sewers to the surface and conditions of their formation

Summary

Corrosive gas emissions from sewers to the surface happen because of the excess pressure increase in the underroof and shaft space of the sewer. The causes of the pressure increase in the shaft space are considered. The gas amount changing during entering the shaft and removed from it depends on the wastewater flow rate, sewer filling (the height of the gas flow), hydraulic gradient of the sewer, formation of stagnation zones (sludge sedimentation), and temperature. Variation of these parameters and thus the location of corrosive gas emissions to the surface depend on a number of factors that can be divided into several groups: construction, hydraulic, geodesic, operation, random, climatic. Reducing the gas emissions from sewers is possible by: introduction of construction solutions for gaseous medium redistribution; elimination of air blocks, installation of purification filters; avoiding deviations from the design solutions arising during the construction of deep sewers; proper management of wastewater flow at elevation differences; improvement of the sewer operation rules, severization of the requirements to the operating personnel qualification.

Key words

collector , sewerage network , joint movement of liquid and gas , gas emission , excess pressure , ventilation