CHANGES IN CONCENTRATIONS AND LOADS OF TOTAL PHOSPHORUS IN DOMESTIC AND TREATED WASTEWATER OVER A 15-YEAR OBSERVATION PERIOD IN TERMS OF LIMITING NEGATIVE ANTHROPOPRESSURE ON THE QUALITY OF SURFACE WATER – CASE STUDY

30-059 Krakow ABSTRACT Aim of the study The main aim of the research was to verify the thesis that formal and legal restrictions on the use of phosphorus compounds, particularly polyphosphates, in detergents extensively introduced in recent years reduced the concentration and load of this nutrient in raw sewage inflowing to the selected treatment plant. Additionally, it was tested whether the phosphorus decreasing in raw sewage reduced the concentrations and loads of total phosphorus in treated sewage, and thus reduced negative sewage anthropopressure of the water body. Material and methods This paper presents observations accumulated during the 15-years study (2003–2015), the concentrations and loads of total phosphorus in domestic sewage flowing into the selected treatment plant, as well as in treated sewage discharged into the receiving water body. A total of 148 samples of raw sewage and 114 samples of treated sewage were collected over the research period. The concentration of the total phosphorus in wastewater was determined by spectrometry with ammonium molybdate. The research results were analysed with the aid of advanced statistical analysis using, among others Mann-Kendall test, Kolmogorov Smirnov test, elements of descriptive statistics, as well as regression analysis with selected that only for one analysed sewage treatment plant, the annual phosphorus content in the wastewater would reduce the trophic mass growth by nearly 33 tons, in comparison to the period when no restrictions were applied to the content of polyphosphate in detergents.