MIL-HDBK-1138
wastewater to design flow rates will improve the efficiency of
the separator.
Design Capacity. An oil/water separator has a
5.3.2
finite capacity for storing oils and sludges accumulated during
its operation. Quite often the oil/water separator holding
compartments can become saturated or full of oils and sludges,
allowing contamination to flow freely into the wastewater
effluent exiting the separator system. Ensuring that the
separator capacity meets the needs of the process will aid
separation efficiency.
Emulsifying Agents. Detergents and soaps designed to
5.3.3
remove oily grime from dirty weapon systems, vehicles, or other
components can adversely affect oil/water separator operation.
These agents are designed to increase solvency of oily grime in
water. Hence, the oil droplets take longer to separate from
water, reducing separation efficiency. Overzealous use of
detergents can degrade efficiency by completely emulsifying oil
in the wastewater stream, thus allowing the oil to pass through
an oil/water separator unaffected.
Periodic Maintenance Practices. Sludges and oils that
5.3.4
are not periodically pumped from separator holding tanks can
render the separator inoperative. Additionally, leaks from
oil/water separators can result in environmental pollution that
could require investigative studies and extensive cleanup.
Regular equipment inspections and a preventive maintenance plan
can prevent contaminated discharges from the oil/water separator
system. Depending on the wastewater characteristics(e.g., low
pH), what material the separator is made of, and the age of the
facility, visual equipment inspections should be performed from
once per week to once per month. More rigorous inspections should
be conducted two to four times per year. Inspections should focus
on areas below the water line; equipment construction joints;
piping connections and interfaces; and other areas prone to wear,
spills, or leaks. See par. 5.5 for more detail.
Type of Oil/Water Separator System. An oil/water
5.3.5
separator designed and installed to a past mission requirement
may not be suitable for current maintenance operations. For
example, a wash rack with an oil/water separator designed to
capture contaminants from a small fighter aircraft will not
handle larger wastewater volumes from a larger aircraft.
Additionally, changes in mission can affect the effluent
characteristics of the wastewater being discharged to an
oil/water separator (i.e., wastewater with solvents or emulsions
versus free floating oil). Thus, as installation missions
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