Controlled landfill offers a possible alternative for the disposal of oily wastes, and research has been carried out to assess the impact of these practices using laboratory simulations and a site study.
These studies showed that oil emulsions (cutting oil and mousse) were rapidly broken down to free oil and an associated aqueous phase in the landfill. The oil was readily sorbed by domestic waste solids, whereas the aqueous phase was flushed out with leachate. Concentrations of oil in leachate were, in most cases, similar to those found in leachate from domestic wastes only (within the range of 5 to 10 mg/L). It was probable that under anaerobic conditions in the fill, oil was not significantly degraded by microorganisms, small losses of oil being mainly due to leaching.
It is concluded that water pollution (surface or groundwater) from the disposal of small volumes of oily wastes with domestic wastes will not be significantly greater than pollution by leachates from domestic wastes only. It is possible that, at small landfills, disposal of excessive quantities of aqueous oil emulsion wastes could exceed the sorptive capacity of the domestic wastes and give rise to leaching of oil.
The persistence of oil in a landfill for long periods of time is an additional problem, which has consequences for the long-term development of land “reclaimed” with wastes containing oils.