1. Bilge Water Treatment Unit – For the
purposes of this document a bilge water treatment unit is defined
as, but not limited to, an oily water separator augmented with filters
and a polishing or secondary treatment capability (if fitted) along
with a metering device operating in unison to prevent discharge of
effluent exceeding 15 ppm of oil. This unit could also use a biotreatment
process.
2. Bilge Water – For the purposes of this
document bilge water is taken to be water with a complex cocktail
of soluble and insoluble organic and inorganic materials with a primary
component being oil or oily hydrocarbons.
3. Biological Contamination – In the case
of bilge water the most prevalent biological contamination is sulphate-reducing
bacteria. The presence of these bacteria results in high amounts of
suspended particulate matter composed primarily of colloidal iron
and other iron compounds. Biological contamination is most often caused
by exposure of the bilge to material in the sludge tanks. Nutrient
rich environments (chronically dirty bilge water) will also enhance
the occurrence of biological contamination.
4. Cloudy Water – Water which is not totally
transparent to the naked eye due to the presence of suspended materials.
5. Clear Water – Water which is totally
transparent upon inspection with naked eye. Note: Water can possess
a colour and can still be clear. Clean water is taken to be clear
and colourless.
6. Detergent – Any liquid or solid cleaner
which when added to water has the ability to emulsify oil.
7. Emulsion – The stable suspension of droplets
in one immiscible liquid by another. The formation of emulsions is
enhanced by the presence of detergents and solvents, by the presence
of finely suspended particulate matter or by mechanical action such
as shearing action of pumps. Emulsions are destabilized by heating,
acidification or chemical action.
8. OCM – Oil Content Meter. This is a somewhat
generic term for a meter capable of detecting the presence of hydrocarbons
in water. The most common types are based on light dispersion. Ultra-violet
(UV) based fluorescence meters are also able to detect the presence
of carbon-hydrogen bonds.
9. OWS – Oily Water Separator. This is also
a somewhat generic term for mechanical devices, many of which exploit
gravity or density differences between two immiscible liquids in order
to achieve separation into two distinct phases. This type of equipments
includes centrifuges, parallel and inclined plate separators and a
variety of other configurations. The coalescing oily water separator
is self-contained in a tank shell and includes an improved oil coalescing
medium for separating oil out of wastewater and a series of baffles
and weirs to direct flow, skim the separated oil and control the liquid
level in the separator. This unit could also use a bio-treatment process.
10. Oil – A liquid that is a water insoluble
animal or mineral based hydrocarbon (for the purposes of this document
we will consider a material a liquid if it has a freezing point above
32°F).
11. Oily bilge water – Water which may be
contaminated by oil. Any liquid entering the bilge system including
bilge wells, bilge piping, tank top or bilge holding tanks is considered
oily bilge water.
12. Particulate Material – Aerosolized solid
matter which when captured with a filter has no less than 50% non-volatile
residue.
13. Polishing – Secondary (post-OWS) treatment
of bilge water. This category can include flocculation, surface modified
filtration, biological digestion, membrane filtration, distillation
and other techniques.
14. PPM – one ppm is one ten thousandth
of a per cent. One milligram per litre of water is equal to 1 ppm.
15. Soot – Carbon based particulate matter
resulting from the incomplete combustion of hydrocarbons.
16. Sheen – Diffraction colours visible
to the naked eye when a thin layer of oil is floating on water. Rainbow
sheen is the most familiar. A rainbow sheen is produced over one square
nautical mile by the addition of 40 gallons of oil.
17. Sulphuric Acid – A highly corrosive
mineral acid. H2SO4 utilized to lower the pH
of a sample. Sulphuric acid is used to split droplets of suspended
hydrocarbons from water. Cloudiness resulting from hydrocarbons will
be eliminated in the presence of sulphuric acid. This is not the case
with other categories of opacity causing agents.
18. Visible Oil – Oil which is clearly visible
as sheen or distinct layer floating on the collected sample.
19. Retrofit – the modification of equipment
already installed.
20. Upgrade – renewal or replacement of
equipment with a newer or more appropriate (e.g., powerful) model.