3.2.2 Industrial Waste Oil Segregation. If an aggressive program for
collecting and burning waste oil is established by an activity, publicizing
the results in dollar savings and energy conservation will help in
obtaining cooperation in segregation. Containers and collection at
necessary frequencies must be provided to lessen the workload of separate
handling. Once it becomes standard procedure in a shop to handle certain
wastes separately, the procedure will continue. Original containers may be
saved and reused for waste collection. Drums, with appropriate signs or
labels, may be placed in or near shops for disposal of "dirty" and "clean"
waste oil products. As with other types of recyclable products (such as
paper and metals) the difference in time, labor, and trouble required to
reclaim the item rather than throw it away is very small once it becomes
part of the routine.
3.3 CENTRALIZED STORAGE. Burnable waste oil should be centralized in
storage prior to delivery to the boiler plant or contractor-receiving
points. It is costly to have a waste oil buyer pick up small quantities at
many locations. Tank trucks or trailers may serve as mobile storage for
collecting and storing the waste oil between source and boiler plant.
Unless the waste oil is stringently treated prior to burning, or
unusually clean when collected, gravity separation will be required to
remove water and solids. Large quantities of "clean" waste oil (e.g.,
contaminated jet fuel declared unusable for aircraft) generated at one time
should be delivered directly to the boiler plant when possible to avoid
further degradation by mixing with other waste oils.
3.4 TREATMENT--WATER/SLUDGE REMOVAL. Waste oil may contain varied amounts
of water, sludge, and solids. Excessive water in oil may cause flame out;
sludge and solids may plug up the fuel system, cause excessive wear in
nozzle tip and pump components, etc. They must be removed from the waste
oil before it can be safely fired in a boiler. At present, an oil that
contains no free water* and that can pass through an 80-mesh screen filter
is considered reasonably adequate for boiler firing.
Water, sludge, and solids may appear in the waste oil either in a form
more or less separated from the bulk of the oil or suspended in it in
various emulsified states. In general, they may be removed simply by
gravity separation. By leaving the oil in a tank undisturbed for enough
time, they will eventually settle at the tank bottom and can be easily
removed. When sufficient time is not available, the gravity separation
process may be accelerated by heating the oil to some safe temperature
(e.g., with a steam coil heater to 150F), by using a centrifuge, or by
adding a commercial chemical demulsifying agent. If the waste oil appears
to be a stable emulsion (having poor demulsibility by the above methods),
mixing it with light fuels such as contaminated JP-5 or diesel will help
accelerate the demulsification before the gravitation separation process.
(The amount of light fuel to be used depends on the nature of the
emulsion. Adding one part of fuel in five parts of waste oil would be a
good starting point.)
*Refer to water visibly separated from the oil as distinguished from
water suspended in the oil in an emulsified state.