I Avfallsgruppen Forsok rned biologisk nedbrytning av oljehaltigt ...

Oily wastes are a big part of hazardous wastes produced. This report describes
experiments to treat oily wastes through composting.
Large scale composting of oily sludge with bark and horse manure is a good method to
reduce the con tens of total hydrocarbons in the material. The main mechanism of total
hydrocarbon reduction seems to be biological transformation, althoug part of the
hydrocarbons volatilize and leak out with rain water. In 250 days a 60-80% reduction
was measured.
Effective mixing of the oily material into the substrate and turning the compost are
critical steps eg, to break clumps of material. The selection of mixing equipment must
be done very carefully. The composting temperature must reach at least 10-l5°C for a
resonable reduction of hydrocarbons to occur. This is not possible during winter time
out door composting. Other experiments, where eg forced ventilation was used, seems
to indicate that the same percental reduction of hydrocarbons could be reached in
shorter time.
It ought to be possible to use the metod with sucess for stabilizing and reducing of the
environmental hazards of oily wastes befor deposing. Composting may be an altemativ
to long transports of wastes away from smal citys, eg for treating of contamineated soil.
Further studies should include: mass balance studies to quantifie volitalization and leachate,
identification of compounds not degraded, and methods to degrade the residue.
Summary sid ii