Controlling Chemical Dosing Into Sewers for Odour and Corrosion Abatement

Sewers conveying domestic or even industrial wastewater are subject to release of odours and other compounds from the liquid into the gaseous phase. This can cause odour nuisance and also massive damage to the sewer network itself due to corrosion of concrete and metal. In order to prevent the formation of the responsible substances, mainly sulphide, chemicals, mostly oxygen carriers, can be dosed into the sewer network. If odorants or sulphide are present in discharges or have been formed in the sewer already, especially with pressure mains, chemicals that oxidise odorants and chemicals that precipitate sulphide can be dosed in order to mitigate or suppress the negative effects. Large communities like the Paris area spend up to 7 million per year just for the chemicals that are dosed into the sewer system for these purposes. Proper dosing of chemicals that always is in line with the actual demand is not realized today. There are several reasons for this that will be highlighted, and it will be explained how a proper solution looks like. First results from an ongoing research project at a large German city will be shown, where the new improved strategy & methodology is adopted.