Polychlorierte Dibenzo-p-dioxine und Dibenzofurane (PCDD/F)

Distillation residues of dry cleaning machines contain small quantities of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F), independent of the type of solvent employed. PCDD/F were not only detectable in distillation residues using perchloroethylene as dry cleaning solvent, but also similar quantities and congeneric patterns of PCDD/F were found in residues from machines operated with stoddart solvent or CFC 113. Current results suggest that PCDD/F occurrence is linked to the dirt adhering to the textiles. Dirty textiles were a prerequisite for finding PCDD/F in the distillation residues. The congeneric patterns of the identified PCDD/F in the distillation residues were found to be similar as those from household dust, sewage sludge, as well as those from soil, sediments, and street dust. The investigations clearly show that perchloroethylene is not linked to PCDD/F formation. The freshly produced, commercial perchloroethylene as well as laboratory-distilled perchloroethylene did not contain any detectable quantities of PCDD/F. Also, the possibility of PCDD/F formation through decomposition reactions of the solvents during the dry cleaning process can be excluded on the basis of existing data.     

Investigation of pathogenic Escherichia coli and microbial pathogens in pulp and paper mill biosolids.

Biosolids produced from pulp and paper mill wastewater treatment have excellent properties as soil conditioners, but often contain high levels of Escherichia coli. E. coli are commonly used as indicators of fecal contamination and health hazard; therefore, their presence in biosolids causes concern and has lead to restrictions in land-spreading. The objectives of this study were to determine the following: (1) if E. coli from the biosolids of a wastewater-free pulp and paper mill were enteric pathogens, and (2) if other waterborne microbial pathogens were present. E. coli were screened for heat-labile and heat-stable enterotoxin and verocytotoxin virulence genes using a polymerase chain reaction. Ten isolates were also screened for invasion-associated locus and invasion plasmid antigen H genes. None of the 120 isolates carried these genes. Tests for seven other microbial pathogens were negative. Effluents and biosolids from this mill do not contain common microbial pathogens and are unlikely to pose a health hazard.