Comparative analysis of sewage sludge from two sewage treatment plants: in Mrozy and Siedlce (Mazowieckie Province) / Porównawcza analiza osadów ściekowych z dwóch oczyszczalni ścieków w Mrozach i Siedlcach (województwo mazowieckie)

Selected parameters of sewage sludge from two different sewage treatment plants: a rural one (in Mrozy) and a municipal one (in Siedlce) were compared. Samples from a mechanical-biological sewage treatment plant (Mrozy) showed a higher content of nitrogen and lower content of phosphorus, potassium and magnesium than the samples from the sewage treatment plant with the tertiary enhanced nutrient removal (Siedlce). The C/N ratio was 7.5 and 11.7, respectively. No differences were noted in the content of zinc in analysed samples. From among analysed metals (Cu, Zn, Fe and Mg), magnesium occurred in the greatest amounts in easily available form. The presence of ¹³⁷Cs was found in sewage sludge from both treatment plants.