The working area for outside maintenance
installations should be minimized to reduce the volume of
contaminated runoff requiring treatment. Using high-pressure
water and/or detergents to clean up the work area increases
emulsification and inhibits gravity oil/water separation and is
therefore not recommended.
Use of dry absorbents should be considered to
minimize the amount of oils reaching installation sewers. Dry
absorbents may be collected and disposed of with solid waste
materials. Evaluate the flash point of spent absorbent for
possible hazardous waste designation under RCRA guidelines.
Point source controls should be investigated to
eliminate or reduce the wastewater volume and contaminant
concentrations. For example, segregate used oils and solvents
for disposal or reuse rather than allowing them to enter the
wastewater stream. Implementing point source controls may be
more economical than providing a wastewater treatment system.
Also, consider point source control techniques, such as process
change or modification, material recovery, wastewater
segregation, and water reuse.
Making process changes may eliminate the perceived
need for an oil/water separator. Is the floor drain in the
maintenance bay necessary? The drain should be protected against
hazardous substance spills if there is a potential for spills in
that area. Can a dry process replace a wet process? This
approach would completely eliminate a wastewater stream. An
oil/water separator should not be installed to capture spills. A
holding tank can accomplish this.
The formation of oil emulsions should be minimized
and emulsions should be segregated for special treatment whenever
possible. Emulsions are usually complex, and bench scale or
pilot scale testing is generally necessary to determine an
effective method for emulsion breaking. For guidance in
emulsions treatment, refer to API Publication 421, Design and
Operation of Oil-Water Separators.
Current process operating practices should be
employed and if changes can be made to reduce waste materials or
use of excess water. In many cases, proper attention to control
of operations can greatly reduce the amount of soluble oil
avoiding spills, and discarding oil only when it is no longer
serviceable should be a part of any oil disposal program.