Microscopic evaluation of the manholes in selected sewerage pressure system

The aim of the research was to determine changes in the elemental composition of concrete under the influence of exposure to hydrogen sulphide in the existing sewage system. The system operator pointed to significant problems with odours in this system. The research included a fragment of the pressure sewage system. The concentration of gases: hydrogen sulphide, ammonia and methane was measured in selected wells. High concentrations of hydrogen sulphide (over 200 ppm) were recorded in the studies. Concrete samples were taken from the internal walls of the well for testing. The samples were used for a microscopic analysis of their composition, using an electron microscope with an EDS attachment. Also, concrete samples from a new sewage well were tested to compare their elemental composition. Gas measurements confirmed the problem of odors, while the analysis of the elemental composition showed a significant proportion of sulphur(from 7.53% to 42.9%) on the surface of the well compared to the reference sample (0%).