Compounds contributing to odors from pulp and paper mill biosolids - Anaerobic biological activity a contributing cause

Compounds contributing to the manure-type odors associated with biosolids p rocessing and dewatering in pulp and paper mills were identified as several volatile fatty acids (propanoic, isobutyric, butyric, isovaleric and valer ic), a phenol (p-cresol), indole, 3-methyl indolc (skatole) and the four re duced sulphur gases: hydrogen sulphide, methyl mercaptan, dimethylsulphide and dimethyldisulphide. A Preliminary study of the concentrations of these odor-causing components at three mills indicates that they appear to be pre sent at relatively low concentrations in the ambient air of the biosolids p rocessing areas, well below literature threshold limit values (TLV). Nevert heless, the odors can be a nuisance and options need to be evaluated for th eir potential control.