Bilge systems
The bilge water occurs: due to leaks through leaks behind the onboard and
fresh water, fuel and oil systems, removal of water from fuel settling and
sludge collection tanks, or collection of water and waste after various
cleaning and washing procedures. This water can mix with various contaminants
flowing through the various production facilities.
Until 50 years ago, the waters of the bilge consisted mainly of water and
diesel. They are now capable of detecting: heavy fuel oil, lubricants and their
additives, detergents and other chemicals, catalyst particles, soot and other
solid particles (sludge).
Therefore, all vessels must be equipped with a drainage system and bilge
water treatment equipment. This equipment must be tested and certified in
accordance with MERC.107 (49) to ensure its operability.
Static and dynamic treatment technologies are used for the treatment of
sewage.
Static treatment technologies use the following methods: chemical
treatment, absorption filtration, membrane filtration, traditional coagulation.
Dynamic bilge water treatment systems use a centrifugal separation method
implemented with high-speed disc separators (the principle of operation is
similar to that of fuel and oil separators described in fuel and oil systems,
so we will not discuss this bilge water treatment method in detail).
In accordance with the requirements of the International Convention for
the Prevention of Pollution from Ships (MARPOL) in international waters, the
discharge of purified bilge water with an oil concentration not exceeding 15 ppm
is permitted overboard (although some governments or local authorities may
impose more stringent requirements). In the future, further tightening of
legislation and reduction of the permissible concentration of oil products in
water, as well as a total ban on discharges into vital water bodies are
envisaged.
The control methods used by government agencies and other authorized
bodies are becoming more effective and today include not only airborne but also
space-based measures to detect the release of hydrocarbons in the oceans.
Drainage systems used on ships are divided into: