- Oils, greases, and grit which collect on an aircraft during
flight are removed on the U. S. Air Force washracks using an
alkaline, water-base cleaner. Waste-flows from these washracks
may include in addition to free oils, emulsified oils, and alkaline,
water-base cleaners several other constituents such as acid skin
brightners, paint stripping solvents, paint scrapings, and volatile
A study of aircraft washrack waste characteristics and treatment
methods is presented in this thesis. The first section is a
review of available literature including past experimental analysis.
A survey of current washrack installations and treatment facilities at
65 Air Force bases in the United States forms the second section.
The final section of this thesis contains an experimental analysis of the washrack wastes and the treatment facility at Portland AFB,
Oil concentration, five-day BOD., suspended solids, total
solids, and effluent over-flow are used to measure the waste
characteristics and flow and to determine the efficiency of a gravity
oil separator at the Portland base. A testing procedure for
determining oil concentrations is developed.
Tests of the inflow and outflow of the gravity oil separator
showed the following ranges.
Waste Characteristics: 5-day BOD. (mg/1), Oil Content (mg/1), Suspended Solids (mg/1), Total Solids (mg/1) Influent: 530 - 3,300, 1,450 - 6,400, 34 - 270, 690 - 2,400 Effluent: 350 - 1,250, 240 - 1,130, 28 - 80, 500 - 2,070 The conclusions drawn from the test results are as follows:
1. An acclimated seed was required for the five-day BOD.
test of aircraft washrack wastes.
2. For oil concentrations in washrack wastes, the testing
procedure presented in this thesis measured oil concentrations
with an error of less than four percent.
3. The gravity oil separator at the Portland AFB provided
an average BOD. reduction of 37 percent and an oil removal of 70 percent.
4. The effluent from the gravity oil separator contained
only emulsified oils.
5. The average oil content of the treated effluent was 589
ppm. This value greatly exceeded the general limit of
30 ppm, established by states which had oil concentration
6. An average of 410 gallons of water was required to wash
a C-119 aircraft at Portland AFB.