Section 17.2 Annex IV: Sewage Management

MARPOL Annex IV deals with the control of pollution of the sea by sewage from ships. Sewage, if discharged untreated, can pose a threat to marine ecosystems and human health due to pathogens and nutrient loading. All bulk carriers on international voyages are subject to these regulations.

Key Requirements and Aspects for Bulk Carriers:

1. Application:

Annex IV applies to ships of 400 gross tonnage and above, or which are certified to carry more than 15 persons. This effectively covers all internationally trading bulk carriers.

New ships (keel laid on or after 27 September 2003) must comply fully. Existing ships had phased compliance dates.

2. Options for Sewage Management: Ships can comply with Annex IV by one of the following methods:

Operating an approved Sewage Treatment Plant (STP):

The STP must be type-approved by the Administration according to IMO standards (e.g., MEPC.227(64) for newer plants).

The effluent from an operational STP must not produce visible floating solids nor cause discoloration of the surrounding water.

Specific effluent standards (e.g., for thermotolerant coliforms, Biochemical Oxygen Demand (BOD), Total Suspended Solids (TSS), and pH) must be met, particularly for plants installed after 1 January 2016, if discharging in areas where passenger ships operate or in Special Areas.

Using an approved Sewage Comminuting and Disinfecting System:

This system grinds solids and disinfects the sewage before discharge.

Discharge is permitted beyond 3 nautical miles from the nearest land.

The sewage must be comminuted and disinfected.

Retaining sewage in a Sewage Holding Tank:

The tank must have adequate capacity based on the ship’s complement and voyage duration.

Stored sewage can only be discharged when the ship is en route and proceeding at not less than 4 knots:

If comminuted and disinfected: beyond 3 nautical miles from the nearest land.

If not comminuted and disinfected: beyond 12 nautical miles from the nearest land.

Discharge must not be instantaneous but at a moderate rate.

3. Special Areas under Annex IV:

The Baltic Sea is a designated Special Area under Annex IV.

Stricter discharge requirements apply in Special Areas. For passenger ships (which doesn’t directly apply to bulk carriers but sets a precedent for stricter controls), and for other ships from a future date, the discharge of sewage is generally prohibited unless the ship has an operative STP meeting stringent effluent standards and there is no discoloration or floating solids.

Bulk carriers must be aware of any specific regional or national regulations that may be more stringent than MARPOL, especially within Special Areas or sensitive sea areas.

4. Standard Discharge Connection:

Ships must be fitted with a standard discharge connection to enable pipes from reception facilities to be connected for the discharge of sewage.

5. Surveys and Certification:

International Sewage Pollution Prevention (ISPP) Certificate: Ships to which Annex IV applies must be surveyed and issued with an ISPP Certificate. This certificate is subject to initial and renewal surveys.

The condition of the sewage system and any treatment plant must be maintained to ensure compliance.

6. Operational Considerations for Bulk Carriers:

Maintenance of STPs: If an STP is fitted, it requires regular maintenance as per the manufacturer’s instructions. This includes checking disinfectant levels, operational parameters, and periodic cleaning. Crew responsible must be adequately trained.

Holding Tank Management: If relying on holding tanks, careful planning is needed to ensure sufficient capacity for the intended voyage legs between discharge opportunities or access to reception facilities.

Record Keeping: While not explicitly mandated by Annex IV in the same way as the Oil Record Book or Garbage Record Book, it is good practice and often a company requirement to maintain records of sewage discharge operations (dates, times, positions, quantities, method used). This is especially important if operating an STP or discharging from a holding tank.

Availability of Port Reception Facilities: Masters should ascertain the availability of port reception facilities for sewage well in advance, particularly if the vessel will be in port for extended periods or if operating primarily on holding tanks.

Crew Awareness: All crew should be aware of the ship’s sewage management plan and the importance of not discharging sewage illegally.

Best Practices for Bulk Carriers:

Regular Inspection and Testing: Ensure the STP or comminuting/disinfecting system is regularly inspected, tested, and maintained in full working order.

Training: Provide thorough training to relevant crew members on the operation, maintenance, and troubleshooting of the sewage treatment system.

Clear Procedures: Have clear, ship-specific procedures for sewage management, including operations in different sea areas (outside 3 NM, outside 12 NM, Special Areas).

Minimize Water Usage: Encourage practices that minimize water usage in toilets and showers to reduce the load on the sewage system.

Avoid Prohibited Items: Ensure that no prohibited items (e.g., plastics, chemicals, galley waste) are discharged into the sewage system as this can damage the STP or cause pollution.

Compliance with MARPOL Annex IV is essential for protecting coastal water quality and public health. Proper management of sewage onboard bulk carriers demonstrates a commitment to environmental stewardship.