SPECIATION OF PHOSPHORUS IN WASTEWATER SEDIMENTS FROM SELECTED WASTEWATER TREATMENT PLANT

The aim of this work was to characterize wastewater sediments of various types of wastewater treatment plants in terms of the occurrence of forms of phosphorus speciation. The preliminary analysis of speciation using sequential extraction by Golterman was made. It consists in using chelating reagents (Ca-EDTA and Na-EDTA) as well as NaOH and H2SO4 solutions. The quantitative measurement of phosphorus was carried out using spectrophotometric method according to binding rules. The number of individual fractions of phosphorus in wastewater sediments and the concentration of total phosphorus in treated and raw wastewater were examined. According to Golterman the phosphorus absorbed on the surface of sludge particles, so called mobile phosphorus, is a speciation form that is the most easily accessible for organisms. Preliminary results show that the significant participation of mobile phosphorus in wastewater sediments appeared in these wastewater treatment plants, where integrated methods of the wastewater treatment were applied (wastewater treatment plants mechanical-biological- chemical). The results obtained allow to conclude that, depending on the physico-chemical conditions in the various types of wastewater treatment plants, excess sludge shares have different forms of mobile phosphorus speciation, which may affect the recovery of this element from wastewater sediments.