Features of wastewater composition at small-scale treatment facilities

Summary

The composition of wastewater at small-scale treatment facilities differs significantly from the composition of municipal wastewater both in terms of pollution concentrations and their proportions. Information is presented on the collection and analysis of data from long-term observations of the composition and temperature of wastewater from small settlements at 31 treatment facilities. It has been revealed that an increased concentration of nitrogen at medium concentrations of organic substances is typical for these facilities. Such a disproportion results in a shortage of substrate for biological treatment – denitrification; consequently, dosing an external source of organic matter is required. Wastewater supplied to the treatment facilities has a very low N–NH₄/N_total ratio, which indicates incomplete ammonification and the need to take into account total nitrogen during laboratory control. At some facilities, the temperature of incoming wastewater is below 10–12°C during most of the year, which significantly reduces the efficiency of biochemical treatment processes.

Key words

domestic wastewater , sewerage treatment facilities , temperature , wastewater composition , denitrifying potential