Waste management on board a ship is technically a full-time job for the ship’s crew. The waste produced by some types of ships can amount to thousands of tons daily. This waste can be divided into operational-generated waste, such as oil waste, air pollution, cargo residue, etc., and human-generated waste, such as garbage and sewage. The sewage waste a ship produces depends on the number of crew members and the type of ship. A large cruise ship can produce about 170,000 gallons of sewage daily. On average, 0.01 to 0.06 m3 of sewage is produced per person in a day. Related Read: Ocean Pollution: 6 Things That Make It Worse Defining Sewage Waste The sewage waste produced on the ship can be divided into two categories: blackwater and greywater. Together, they are called wastewater. The black water comprises the following wastes produced on a ship: – Waste generated from drainage and in any other form from toilets and urinals – Waste generated from the drainage of a medical dispensary, sickbay, etc., via washbasins, washtubs and scuppers located in such premises – Drainage from the cargo hold of living animals or other wastewater when mixed with the drainages of such spaces The Grey Water produced on the Ship comprises of – Waste generated from the drainage of the dishwasher and washbasin in the galley – Waste generated from the drainage of cabin showers, bath and washbasin drains – Waste generated from the drainage of laundry – Wastewater from interior deck drains – Refrigerator and air conditioner condensate Untreated sewage contains a concentration of nitrates, phosphates, and organic matter. This will contaminate water bodies such as lakes, rivers, and the sea, as the bacteria in the untreated sewage are strong and can consume oxygen at a very high rate from the surroundings, making it difficult for the natural fauna of the aquatic environment to sustain. Related Read: Marine Pollution by Ships -Tips for Reducing & Recycling Waste at Sea Regulation For Sewage Waste – MARPOL ANNEX IV The sewage waste discharge from the ship is regulated under MARPOL Annex IV. The regulation states that: – Every ship of 400 GT and above, which is engaged in international voyages and carrying a minimum of 15 persons onboard, must be equipped with either a sewage holding tank of appropriate capacity or an approved sewage Treatment Plant (STP) or both – The sewage discharge from the ship is allowed if it has an approved sewage treatment plant, which can treat the raw sewage and discharge comminuted and disinfected sewage. With this arrangement, the discharge is allowed at a distance of more than 3 nautical miles from the nearest land when the ship is proceeding with a speed of 4 knots and above – Foreign going cargo ships may be allowed (depending upon the area they are plying) to discharge untreated sewage only at a distance greater than 12 nautical miles from the closest land only if the ship is proceeding with a speed of 4 knots and above – The ship has to maintain the rate of discharge of sewage from the ship as recommended by the administration – The rate of discharge from the ship is also limited to 1/200,000 (or one 200,000th part) of swept volume as follows: DRmax = 0.00926 V D B Where: DRmax is maximum permissible discharge rate (m3/h) V is ship’s average speed (knots) over the period D is Draft (m) B is Breadth (m) Special Areas The most recent amendment for MARPOL annexe IV was enforced in January 2013, wherein, the Baltic sea area has been adopte