CHARACTERIZATION OF SULFUR IN FULVIC-ACIDS EXTRACTED FROM ANAEROBICALLY DIGESTED SEWAGE-SLUDGE

A variety of analytical methods were employed to characterize 80 to 90% of the sulfur (S) in two representative fulvic acids extracted from anaerobically digested sewage sludge. As in fulvic acids extracted from soils and peats, the majority of the sulfur (69%) was present as organic ester sulfate, with smaller contributions from LAS-type detergents, amino acids, and inorganic sulfates. Of the ester sulfate, between 20 and 30% was identified as sulfate esters of fatty alcohols, presumably of detergent origin, and about 5% was accounted for by sulfated acidic polysaccharides. It was concluded that, because of the ubiquitous distribution of sulfate esters, the disposal of anaerobically digested sewage sludge should not alter drastically the character of sulfur in natural soil and water systems. Perhaps of greater concern would be the contribution of carbon-bonded sulfur from LAS-type detergents, which have no common natural analogs. © 1982 Soil Science Society of America.