Sludge Watch ==> How PCBs are concentrated in sewage sludges

[Maureen Reilly]

Sludgewatch Admin:

This study shows how sewage that has mean PCB content of only 27 parts per 
billion can create sewage sludge with high PCB levels.

Add to that the regular (and irregular) cleaning of the sewers...which 
mobilizes PCBs (and likely chunks of mercury from dental offices that is 
resting in the bottom of the pipe...into the sewage stream and thence into 
the sludge.

And from there onto the lands where we grow your food.

..............................................

Polychlorinated Biphenyl Concentration in Sewage and Sludges of Some Waste 
Treatment Plants in Southern Ontario

Lawrence, J; Tosine, HM
Bulletin of Environmental Contamination and Toxicology Vol 17, No 1, p 
49-56, January, 1977. 3 tab, 13 ref.

Polychlorinated biphenyl (PCB) levels were monitored in raw sewage at six 
waste treatment plants and in sludge samples from four major urban areas in 
Ontario, Canada. PCB levels from grab samples were analyzed by gas 
chromatography and identified with chromatographs of standard Arochlors. One 
of the treatment plants surveyed received a large proportion of industrial 
wastes , while the other five treated only domestic wastes. Primary and 
activated sludge treatment were used by all facilities.

Concentrations for the 36 samples collected at the six plants ranged from 
1.5 ppb to 27.3 ppb with a mean of 27.3 ppb. Projections based on an annual 
plant loading at a daily flow of 236 million liters/day yielded an average 
value of 310 kg PCB/yr.

Total PCB and contributions by individual Arochlors are listed in tabular 
form. Sludge digestion was observed to concentrate PCB with values reported 
as high as 2,085 ppb. Differences in contributions by individual Arochlors 
between the treatment plants examined were observed. Investigations on PCB 
levels in corn and grass grown on sludge-treated land indicated that 
although concentrations of PCB in leaves were comparable with concentrations 
in the applied sludge, uptake of PCB was not biologically accelerated by 
plants as has been observed for animals.

Analyses of sludge samples from urban areas revealed PCB concentrations of 
100 to 200 ppb. More stringent controls on the disposal of sludge containing 
PCB, particularly on land application, is suggested. (Schulz-FIRL)

Descriptors: Polychlorinated biphenyls; Arochlors; Industrial wastes; Sewage 
treatment; Sludge disposal; Waste water treatment; Organic compounds; Sludge 
digestion; Gas chromatography; Chemical wastes; Chemical analysis; Water 
pollution sources; Absorption; Municipal wastes