Saturday, September 14, 2013

An Idiot's Guide to MARPOL ANNEX IV (revised)

International Regulation for the prevention of pollution by Sewage from Ships
Regulations: 11
Enforcement: 27 Sep 2003
Revised on : 1 Aug 2005

Regulation 1: Definitions
  • Sewage: For the purpose of this Annex, Sewage means the following,
  1. Drainage and other waste from any form of toilets, urinals and WC scuppers.
  2. Drainage from medical premises (dispensary, sick bay etc) via wash tubs and scuppers located in such premises.
  3. Drainage from spaces living animals (as on cattle carrier vessel)
  4. Other waste waters when mixed with the drainage and storage of sewage.
  • Sewage Treatment Plant( STP): A plant to disinfect the above said sewage. This plant to be type approved under MEPC.2(VI).
[The factors mentioned in blue are responsible for the count of sewage treatment and discharge]
  • BOD (Biochemical Oxygen Demand): It is amount of dissolved oxygen needed by aerobic bacteria to break down organic material in a waste water (such as STP).The value of BOD can be determined in milligrams of oxygen consumed by taking one litre of sample at 20 deg C in water kept in dark for 5 days.The difference in dissolved oxygen between the initial measurement and the fifth day measurement represents the biochemical oxygen demand. Also, it is not solely responsible for the waste water strenth. Other industrial methods are employed for that matter.
  • e-Coli Count: It is rod shaped bacteria which can easily develop colonies and multiply them under suitable conditions.Responsible for forming the 'good bacteria' which forms the backbone of STP.
  • Suspended Solids(SS): It is the amount of solid particles still present in the effluent. The total amount of SS indicate the insoluble content of the sewage.
  • Aerobic Bacteria: Such bacteria needs continuous supply of oxygen from air and nutrient in form of solids (which it breaks down).They produce CO2 as remains.
  • Anaerobic Bacteria: It can decompose the sludge and suspended solids without the presence of oxygen but they produce harmful gases such as CO,H2S and CH4.
  • Holding Tank: Means a tank used for collection and storage of sewage.
  • Nearest Land: Base line of land from which the sea starts.
Regulation 2: Application

This annex shall apply to,

Ammendments: Those ships that are built on or after 27 Sep 2003 are considered as new ships for the purpose of this annex and they need to carry ISPP Certificate since 1 Aug 2005.
Existing Ships are those whose keel laid on or after 2 Oct 1983 or building contract signed before 27 Sep 2003.They need to carry ISPP since 27 Sep 2008.
  • New ship of 400 GT and above (formerly 200 GT)
  • New ship < 400 GT but certified to carry more than 15 persons (formerly 10 persons)
  • New ships with unspecified GT but certified to carry > 15 persons.
  • Existing ships >= 400 GT ( formerly 200 GT) since 5 years (formerly 10 years) of date of entry into force of this Annex.
  • Existing ships < 400 GT, certified to carry > 15 persons, since 5 years (formerly 10 years) of date of entry into force of this Annex.
  • Existing ships with unspecified GT, certified to carry > 15 persons, since 5 years (formerly 10 years) of date of entry into force of this Annex.
Regulation 3: Surveys
  •  Initial Survey before ship put to service or when certificate for this annex is issued for first time.
  • Periodic Survey <= 5 years to ensure equipment, fittings etc in order as per Admin.
  • Survey done by competent officers of Admin and post survey no major changes in equipment advised.
Regulation 4: Issue of Certificate

  • "International Sewage Pollution Prevention Certificate" shall be issued.
  • Issued by Admin or an Organization authorised by Admin.
Regulation 5: Issue of Cert by Other Govt
  • Provision shall be made to issue a certificate by foreign government upon successful survey upon request by the Admin.
Regulation 6: Form Of Certificate
  • It should be drawn up in an official language of issuing country.
  • If language is other than English/French, then a translation of home language in above stated lanugages must be present.
Regulation 7: Duration of Certificate
  • International Sewage Pollution Prevention Certificate is issued for <= 5 years from the date of issue.
  • Grace period of 1 month is given from the date of expiry if not extended.
  • Cert shall be revoked if severe alteration is found to be done on the equipment without approval of Admin.
  • If ship is transferred from one flag state to another then this cert cease to be valid and a new cert shall be issued by the new Govt.
Regulation 8: Discharge of Sewage
  • Discharge of Disinfected Sewage @ 4nm away from nearst land
  • Discharge of Untreated Sewage @ 12nm from nearest land
  • Ship must be Enroute @ >= 4 knots
  • Provided that sewage has been stored in Sewage holding tank
  • Approved treatment plant must be installed onboard ship and,
  1. The operational results of this plant must be laid down in ISPP Cert.
  2. Additionally, the effluent shall not produce visible floating solids in, nor cause discoloration of surrounding water or when sewage is mixed with waste/waste water having different discharge requirements, then the more stringent requirements shall apply.
Regulation 9: Exceptions
  • Regulation 8 of this Annex shall not apply to,
  1. Discharge of sewage from a ship necessary for the purpose of securing the safety of ship and those onboard or saving life at sea.
  2. Discharge sewage resulting from damage to ship or its equipment and all reasonable precautions have been taken before the occourance of this damage.
Regulation 10: Reception Facilities
  • The govt of each party to this convention undertakes to ensure the provision of facilities at ports and terminals for the reception of sewage, without causing undue delay to ships, adequate enough to meet the requirements of the ships using them.
Regulation 11: Standard Discharge Connection

To enable standardizatin for the purpose of regulation 10, ship's discharge pipe line needs to be fitted with standard discharge connection whose dimentions are as follows,

Description                                Dimention
Outside Diameter                      210 mm
Inner Diameter                          Acc. to pipe OD
Bolt Circle Dia.                           170 mm
Slots in Flanges                          4 holes (18 mm in dia).Slot width 18 mm
Flange Thickness                        16 mm
Bolts & Nuts                                4, each 16 mm in dia @ suitable lenth

This flange is designed to accept pipes of upto 100 mm ID and they are made of steel or other equivalent material. Its fitted with a gasket of oil proof material, suitable for pressure of 6 kg/cm2.

Thats All Folks :)


  1. Could you please mention the BOD and e coli Limits for approved STP effluents? Also are the above values ever measured on board if so How?

    1. BOD measurement permits an estimate of the waste strength in terms of the amount of dissolved oxygen required to break down the wastewater.
      As per the test described in reg 1, the difference in dissolved oxygen between the initial measurement and the fifth day measurement represents the biochemical oxygen demand.
      While BOD describes the biological oxidation capacity of a wastewater, it is not a measure of the total potential oxidation of the organic compounds present in the wastewater.
      Thus there isn't a documented specified value for the said parameter. Its just an estimate of efficiency.

      For further reading, suggest you to refer to this link:


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