When A Seafarer’s ‘Business’ Becomes The Ocean’s Business

  In the early 1980’s, if a seafarer wanted to do his big business in the toilet, he would have to examine the ships sewage outlet to ensure the pipe
23 Aug 2017 11:00
When A Seafarer’s ‘Business’ Becomes The Ocean’s Business
Discharge of Sewage.


In the early 1980’s, if a seafarer wanted to do his big business in the toilet, he would have to examine the ships sewage outlet to ensure the pipe to ensure no nasty surprise awaited them. If they didn’t have a good look, creepy crawlies shimmying up pipe might just take a bite in the bum.

Whether you were in a port or at sea, the blue waters of the ocean were clearly visible through the hole that went straight through the hull.

It was also not unusual to erect a box on the poop deck of a fishing vessel. The make shift wooden structure hanging out serves as a squatting toilet depositing directly into the ocean.

That means your big business was now the ocean’s business.

Marine Sewage plant image from Marine Insight.

Marine Sewage plant image from Marine Insight.

In the last few articles, I was referring to Marine Industries deadly sins. Here is another.

What is Sewage?

Sewage is the drainage and other wastes from any form of a toilet, urinal or any other waste water when mixed with such drainages.

Incorporated within this description is the term “sewage.” Sewage includes human faecal wastes.  Sewage does not include grey-water (waste water from showers and sinks) unless it is mixed with any of the above.

Sewage Categories

Any sewage discharged from a vessel will be either one of the following two categories:

  • treated sewage,
  • untreated sewage


Treated sewage

Treated sewage is sewage that has passed through an onboard sewage treatment system and has three distinct grades; that is Grade A, Grade B, and Grade C treated sewage.

Grade C is the lowest level of treatment; Grade B is a higher level of treatment and Grade A is the highest level of treatment. Macerated sewage is not treated sewage.


Untreated sewage

Untreated sewage (or raw sewage) is all sewage that has not passed through a treatment system. It includes sewage that is discharged directly from a toilet into a waterway (in areas where discharge is permitted) or contained in an onboard holding tank.

Any untreated sewage that is discharged, in areas where the discharge of untreated sewage is permitted, must first pass through a macerator. Macerated sewage is untreated sewage.


How does raw sewage affect the ocean?

The top three


  1. Oxygen depletion: When sewage decomposes it uses up oxygen from the surrounding water, and if the discharged concentration is too great, the amount of oxygen available for fish and other aquatic animals and plants will be insufficient, and they may die.
  2. Disease: Sewage can contain disease causing bacteria and viruses which pose a risk to public health for swimmers and those eating contaminated shellfish.
  3. Nutrient enrichment: Sewage discharges also contain nutrients which, when elevated slightly, may increase algal and plant growth under certain background conditions.

However, when present in high concentrations, nutrients can be responsible for the formation of algal blooms which reduce light penetration through the water column, may produce toxins and can cause oxygen depletion when decomposition takes place.


Treatment system

A treatment system is a system for treating sewage, and it can reduce the levels of sewage quality characteristics below the levels outlined in the legislation for the relevant grade of treatment for that particular system (that is Grade A, B or C treated sewage).

It also conforms to the standards for a treatment system as outlined in the legislation.

A sewage plant on a commercial cargo vessel is not that complicated.

Working on the principle of decomposition of raw sewage, by a continuous aerating process, it is possible to treat the sewage and discharge to the sea as required by regulations.

A typical sewage treatment plant will consist an aeration tank, settling tank and chlorination and collection tank with a blower provided a controls stream of fresh air.

Some vessels and small leisure craft use chemicals to treat sewage which is accepted as long as the chemicals are of approved type.


Regulation and Control

Although it is not within the scope of this article to describe the regulations, it is possible to summarize for the readers how sewage should be treated.

Currently, regulations administrated through ship design and inspections control how sewage is discharged into the ocean.

One of the International Maritime Organization (IMO) instruments, is the International Convention for Preventing Marine Pollution from Ships (MARPOL)

MARPOL 73/78 is the International Convention for the Prevention of Pollution from Ships, 1973 as modified by the Protocol of 1978. (“MARPOL” is short for marine pollution and 73/78 short for the years 1973 and 1978.)  In Annex IV, “Regulation of prevention sewage from ships” distances for discharging sewage is specified as 3 and 12 nautical from ashore. The discharge depends on the treatment of the sewage on board.

IMO also has certain stipulated special areas that along with sewage many other discharges are strictly prohibited.

In Fiji, there is the regulation that covers the release of sewage. It’s the Maritime Transport Decree 2013 (DECREE NO. 20 OF2013)

“Decree” has now been changed to “Act”.

Marine (Pollution Prevention and Management) PART 1—PRELIMINARY Division VI—Discharge Of Sewage in Fiji Waters Regulations 2014.

If in the past ignorance and negligence has prevailed in the maritime industry in regards to pollution, actions have been taken to identify the causes and rectify them through regulations and awareness.

The curriculum in the Fiji Maritime Academy Covers MAPOL regulations in the Maritime Law Unit at all levels of study. It is no longer possible to please ignorance to the law as everyone contributes to preventing pollution of our pristine oceans.

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