Biotic and Abiotic Decomposition of Indeno-Pyrene and Benzo(GHI)Perylene in Sewage Sludge Under Various Light Conditions

Abstract

The aim of the studies was to determine the changes in the concentration of PAHs in sewage sludge stored under various light conditions. The sewage sludge samples were stored under aerobic conditions. Sewage sludge samples were deposed in darkness, in laboratory conditions and exposed to UV rays. The changes in the concentration of PAHs were analyzed in fourth series: in sludge samples taken from treatment plant (biotic samples), in sludge with the addition of a standard PAH mixture (biotic samples+PAHs), in sewage sludge with addition sodium azide (abiotic samples) and both a standard mixture and with added sodium azide (abiotic samples+PAHs). Changes in 6-ring of PAHs concentration in sewage sludge samples were studied at seven day intervals for 4 weeks. The concentration of PAHs was determination using gas chromatograph-mass spectrometry GC-MS. The losses of hydrocarbons after 4 weeks of research were in the range of 60 to 97%. It depends of kind of samples. In sewage sludge with standard mixture the effectiveness of PAHs decomposition were in the range of 60 to75%. In sewage sludge with standard mixture of PAHs the losses of hydrocarbons were the highest and reached 97%. The final concentration of PAHs in biotic samples was lower (2-13%) than the concentration of analysed compounds in abiotic samples.