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Prevention of odour emergence in sewage networks.

Through increasing central development and through the decrease of specific wastewater production, wastewater systems are more and more prone to odour and corrosion problems. Hydrogen sulphide is produced, particularly in anaerobic flow stretches, which will then escape at turbulent places because of change in the flow direction and create odour harassment. Of particular importance in this respect are the transferring shafts after rising mains. The empirical approaches used for the estimation of the assumed sulphide concentrations yield considerable differences in the calculation and must therefore be used with care. This report presents a methodology for the co-ordination of odour- and corrosion-reducing measures which also includes the area of complaint management. It is crucially important to fine-tune the necessary measures (for instance the application of operational or chemical/biological methods) to the specific frame conditions. The practical comparison of the additional dosage of external water, iron and nitrate served to test the efficiency of these methods. The dosage of iron and nitrate led to considerable reductions in H2S content at the transferring shaft. The online measurement of the spectral adsorption coefficient (SAC) could become one control parameter for saving chemicals. It should be pointed out that it is necessary to consider the relevant measures and effects of odour and corrosion production during the planning stage--from the creation of the development plan of cities and communities. Through the selection of the wastewater disposal method to the planning of details. Moreover, the relevant financial means for these measures must be included in the economic plan.