Comparison of some spectroscopic and physico-chemical properties of humic acids extracted from sewage sludge and bottom sediments

Comparison of the physico-chemical properties was carried out for humic acids extracted from sewage sludge and bottom sediments.The isolated humic acids were investigated by means of EPR, IR, UV/vis spectroscopic methods and elementary analysis AE.On the basis of earlier studies it was stated that humic acids extracted from sewage sludge can be divided into humic acids extracted from raw sewage sludge and from sewage sludge after the digestion process. The digestion process was found to have the most significant effect on the physico-chemical properties of humic acids extracted from sludge during sewage treatment.Humic acids extracted from sewage sludge had higher free radical concentration than humic acid extracted from bottom sediments. Values of the g-factor were similar for all studied samples. However, it is noteworthy that g-factor values for humic acid extracted from raw sewage sludge and from bottom sediments were lower in comparison to the humic acid extracted from sewage sludge after the fermentation processes.The IR spectra of all studied humic acids confirmed the presence of functional groups characteristic for humic substances.It was also observed that humic acids extracted from bottom sediments had a more aromatic character and contained less carbon, nitrogen and hydrogen than those extracted from the sewage sludge.