Pollution by Sewage and Garbage

What do you think about when you hear the word Sewage?... Sewage is, first of all, a combination of drainage and wastewater from toilets, urinals and WC scuppers, but it also includes waste from medical premises (dispensary, sickbay, etc) via washbasin, washtubs and scuppers located on such premises. 

Drainages from spaces containing living animals are also included in sewage, but also other wastewaters when mixed with the wastes defined above. Therefore, sewage is a combination of different types of wastewater and could be dangerous if anyone would get exposed to untreated sewage. It is prohibited to discharge sewage into the water unless:

• The vessel is discharging comminuted and disinfected sewage using a system approved by the administration at a distance of more than 3 nautical miles from the nearest land.
• The vessel is discharging non-comminuted or disinfected sewage at a distance of more than 12 nautical miles from the nearest land.
• The vessel has in operation an approved sewage treatment plant that has been certified by the administration.

Sewage Treatment Plant

A plant treats sewage in different steps. The raw sewage is collected into a holding tank. The sewage then passes three separate chambers during the treatment and if the plant is type-approved, the residues after passing the plant can be pumped overboard. Sewage treatment plants continuously discharge their treated effluent so long as it is not within a Particular Sensitive Sea Area or a defined Special Area. If the sewage treatment plant does not have the test results stated in the ship’s International Sewage Pollution Prevention Certificate, the treated effluent must be temporarily stored in a storage tank.

Vessels utilising a comminuting system are prohibited from discharging treated sewage effluent within three nautical miles from land. Therefore this type of system must include a holding tank for the temporary storage of treated sewage. A sewage treatment plant that does not have the test results laid down in the ship’s International Sewage Pollution Prevention Certificate belongs to this type, as long as it is equipped with a satisfactorily sized storage tank.

A yacht that does not have any of the mentioned systems must have a holding tank of adequate size for the retention of all sewage. Considering the operation of the vessel, the number of persons onboard and other relevant factors. The construction of the holding tank is regulated and it shall have the means to indicate the amount of its content visually.

What Is Garbage?

Garbage means all kinds of victual, domestic and operational waste (excluding fresh fish and parts thereof). This garbage is generated during the regular operation of the yacht and is liable to be disposed of continuously or periodically.  Except for those substances which are defined or listed in other Annexes other than Annex V of the MARPOL convention.

In general, the discharge of all garbage into the sea is prohibited unless expressly provided for otherwise and then only when en route. Food waste, cargo residues and cleaning agents not harmful to the marine environment (carcasses of dead animals need special consideration), are the only types of garbage, that under certain circumstances and depending on location/distance from the shore may be discharged into the sea.

When the yacht is 3 miles from land or navigating within inland waterways, you cannot throw anything overboard, except for specific cleaning agents contained within wash water. At a distance of 3 nautical miles offshore, you can throw food waste comminuted or ground to less than 25 mm overboard. If the food waste is not comminuted, the distance to the nearest land must be at least 12 nautical miles. Any other form of garbage is forbidden from being thrown overboard. At a distance of 12 nautical miles or more offshore you can throw overboard:

• Food waste (not comminuted)
• Certain cargo residues that are contained in the wash water
• Carcasses of animals
• Any other form of garbage is forbidden from being thrown overboard.

On offshore platforms, more than 12 nautical miles from land and from all ships within 500 meters from them, you may be allowed to throw food waste comminuted or ground to less than 25 mm overboard. Any other form of garbage is forbidden to be thrown overboard. Local offshore regulations may apply, and that is why it’s essential to always check with the local administration before any discharge within the 500-meter zone.

What is A Special Area?

MARPOL defines certain sea areas as special areas which, for technical reasons relating to their oceanographical, ecological condition and sea traffic, the adoption of unique mandatory methods for the prevention of sea pollution is required. Under the convention, these special areas are provided with a higher level of protection than other areas. The following special areas have been created for MARPOL Annex V:

• The Mediterranean Sea area
• The Baltic Sea area
• The Black Sea area
• The Red Sea area
• The 'Gulfs' area
• The North Sea area
• The Antarctic area
• The Wider Caribbean area.

Disposal of Garbage Inside Special Areas

In special areas, food waste, if it has been comminuted or ground to less than 25mm, can be discharged. Specific restrictions apply in the Antarctic area. In certain circumstances and as long as not harmful to the environment, exceptions may also apply for cargo residues contained within wash water, cleaning agents and additives from the cargo hold together with deck wash water.

Control of Oil Discharge

Oil filtering equipment is a bilge separator and may include any combination of a separator, filter and coalesce. The standard installation on a vessel is an oily water separator as a single unit, designed to produce an effluent with oil content not exceeding 15 ppm(parts per million). The oily water separator (OWS) separates the oil from bilge water before the bilge water is discharged overboard. The maximum oil content in the bilge water discharged overboard is 15 ppm, according to MARPOL. The OWS is only to be used on order from the Chief Engineer and with permission from the Officer of the Watch on the bridge.

Contents of Oil Record Book

The Oil Record Book help the vessel's crew keep control of & record all oil or sludge transfers and discharges within the vessel. This is necessary for the authorities to be able to monitor if a yacht's crew has performed any illegal oil discharges at sea.

Requirements For the Discharge of Oil Outside Special Areas

Any discharge into the sea of oil or oily mixtures from vessels outside a special area shall be prohibited except when all of the following conditions are satisfied:

• The yacht is proceeding en route
• The oily mixture is processed through oil filtering equipment meeting the requirements of MARPOL
• The oil content of the effluent without dilution does not exceed 15 ppm
• The oily mixture does not originate from cargo pump room bilges on oil tankers
• The oily mixture, in the case of oil tankers, is not mixed with oil cargo residues.

Requirements for The Discharge of Oil Inside Special Areas

Any discharge into the sea of oil or oily mixtures from vessels inside a special area shall be prohibited except when all of the following conditions are satisfied:

• The vessel is proceeding en route
• The oily mixture is processed through oil filtering equipment meeting the requirements of MARPOL, which for this area includes an alarm when oil concentration exceeds 15 ppm and an automatic stopping device
• The oil content of the effluent without dilution does not exceed 15 ppm
• The oily mixture does not originate from cargo pump room bilges on oil tankers
• The oily mixture, in the case of oil tankers, is not mixed with oil cargo residues
• In respect to the Antarctic area, any discharge into the sea of oil or oily mixtures from any ship is prohibited.

Which are the Special Areas For Oil?

The following special areas have been created for the purpose of MARPOL Annex I (Oil):

• The Mediterranean Sea area
• The Baltic Sea area
• The Black Sea area
• The Red Sea area
• The 'Gulfs' area
• The Gulf of Aden
• The Antarctic area
• The North-West European waters
• The Oman area of the Arabian Sea
• The Southern South African waters.

Contents of Annex VI of MARPOL

Annex VI of MARPOL exists to prevent high levels of vapour emissions into the air. The problem with air pollution is that it is harder to detect than an oil spill since air pollution does not leave any visible mark. This invisibility is the reason why it is harder to get a grip on the negative environmental aspects of air pollution.

In MARPOL Annex VI, you can read more about the restrictions on air pollution and air emissions. MARPOL Annex VI sets limits on sulfur oxide (SOx) and nitrogen oxide (NOx) emissions from ships. The Annex VI regulations entered into force in May 2005 and are fully implemented in the year 2020, when the emission limits progressively have been reduced to 0.50% SOx and 0.10% NOx.