The aim of the presented research was to analyse the pollution of the Kozłowa Góra Dam Reservoir

with PCBs (28, 52, 101, 118, 138, 153, 180) and heavy metals (Zn, Cu, Ni, Cd, Pb, Cr). The investigated water

and bottom sediments were sampled from two sampling points in November, 2009. The sampling points were

located in the southern part of the Kozłowa Góra Dam Reservoir. The samples of bottom sediments were taken

from the surface layer of 5 cm thickness. The extraction of PCBs from the bottom sediments was performed

according to the EPA 3550B standard. For the sequential extraction analysis of metals from the sampled bottom

sediments, the method suggested by Tessier was applied. Based on the obtained results the water and bottom

sediments from the Kozłowa Góra Dam Reservoir were polluted with polychlorinated biphenyls. The highest

concentration of the investigated PCB congeners in bottom sediments was determined in the sampling point

No. 1 (2.78 µg/kg d.m.), whereas in the sampling point No. 2 this level was over 20-fold lower which might

result from the inflow of these compounds with the waters of the Brynica river. In both sampling points the investigated bottom sediments were predominated by higher chlorinated PCBs with comparable contents of 86%

and 85%, respectively. The level of pollution in the investigated bottom sediments (calculated per dry matter)

with polychlorinated biphenyls did not exceed the level of TEL (< 0.02 mg/kg). The PEL value (3.5 mg/kg) was

exceeded in the case of cadmium in the bottom sediment from the sampling point No. 2 and also lead (91 mg/kg)

from both sampling points. The first two fractions with the mobile forms of metals are the most sensitive fractions to any changes of the environmental conditions in the benthic zone. In those fractions significant contents

of lead, cadmium, nickel and zinc were observed.

The investigations were carried out in order to assess the effect of thermophilic fermentation on

changes in concentration of seven congeners with codes: 28, 52, 101, 118, 138, 153 and 180 in sewage sludge.

The total concentration of PCBs was the highest before the process of thermophilic fermentation. On the tenth

day of the process of fermentation it was found that the total concentration of LCB doubled the previous level,

whereas in higher chlorinated PCBs this value decreased twice. After the process of thermophilic digestion,

all the determined congeners of PCBs were still present. However, their total concentration was reduced by

84% on the fourteenth day of the process. Low concentration of heavy metal ions in the liquid phase of sewage

sludge was observed. The metal ions precipitated and remained bound throughout the stabilization process.

Metal speciation analysis was performed, and revealed some changes in the chemical forms of the metals during the stabilization process of sludge. The highest increase of zinc, copper, nickel, cadmium, and chromium

concentration was observed in the organic-sulfide fraction, whereas the highest increase of lead was found in

the residual fraction. Thermophilic methane fermentation did not cause the accumulation of heavy metals in the

mobile fractions of sludge.