Environmental Engineering Reference
In-Depth Information
500,000
450,000
400,000
350,000
300,000
250,000
200,000
Untreated
Osorb treated
150,000
100,000
50,000
0
4
6
8
10
12
14
16
18
20
Time (min)
FIGURE 7.10
(See color insert.)
Photographs and gas chromatograms of emulsiied bilge water simulant before and after
addition of 1.5% w/v
Osorb-EB sorbent media. Oil content is reduced to <5 ppm.
carbon decreased from 1164 to 207 ppm, indicating that the nonionic surfactant was retained
in the water although the oil was effectively stripped from the water. Currently, researchers
are developing a variation of swellable organosilica that also absorbs nonionic surfactants
and metal ions by altering the surface chemistry of the porous matrix. In addition, a 10 gpm
pilot-scale treatment system has been built that will be used to evaluate treatment of oil-water
systems. One of the key engineering steps has been accommodating the swelling.
7.4.3.3 Regeneration
Use of sorbent media on shipboard is limited by storage space of consumables and waste.
As a result, physical separators such as membranes and centrifuges are attractive in
limiting the physical footprint of bilge water treatment systems to make room for other
equipment and cargo. Sorbent media may only ind application if the materials can be
regenerated for continuous reuse. Speciically, the oil must be removed from the sorbent
in an eficient and autonomous manner. Currently, the only sorbent that has been demon-
strated to be regenerable is swellable organosilica.
62
It was determined that the swelling
is fully reversible if the absorbates are removed. The inert silica matrix allows for various
processes to be used. Solvent rinsing and thermal evaporation was reported in the lit-
erature. Steam rinsing and supercritical carbon dioxide regeneration also shows promise
in regenerating used swellable organosilica. Further research into sorbent technologies
should be paired with developing regeneration methods if such methods are to be applied
to bilge water treatment on ocean-going vessels.
7.5 Comparative Technology Status and Future of Bilge Water Management
There is very little scientiic research currently being done on the treatment of bilge
water despite the vast volumes that are discharged into the environment and the need
