This research was conducted to investigate the principal structural units from humic acids obtained from urban waste compost (AH-CRSU) and sewage sludge (AH-LETE) by pyrolysis - gas chromatography / mass spectrometry. The humic acids from sewage sludge presented most mono and diaryl esters with higher mass. The n-alcans in AH-LETE showed a shorter chain than AH-CRSU. Phthalate fragments were incorporated into the humic acid structures, probably due to an organic matter contamination by plastics. The aromatic compounds in the AH-LETE originated mainly from naphtalene derivatives and benzene derivatives with alquil chain substitutives higher than AH-CRSU. The nitrogenated compounds were essentially heteroaromatic and the oxigenated compounds were substituted furans originated from carbohydrate degradation. The oxiaromatic compounds were substituted phenols.
organic matter; humic substances; structural investigation