Global And Local Regulations For Scrubber Wash Water Discharge


On January 1, 2020, the International Maritime Organization (IMO) introduced measures to reduce sulphur oxide emissions from shipping. These regulations required vessels to either use fuel oil with lower sulphur content or to limit their air pollution by using exhaust gas cleaning systems known as “scrubbers.”

Compliance Methods and Environmental Impact

One common method for complying with these sulphur limit rules is the use of open-loop scrubbers. These systems filter harmful sulphur oxides from ships’ exhaust gases, releasing the sulphur into the water instead through “wash water.” However, while these systems remove pollutants from the air, they may introduce contaminants into the ocean. Studies suggest that open-loop scrubbers transfer pollution from the air to the sea.

Contamination Risks of Wash Water

Wash water from open-loop scrubber systems can be contaminated in several ways:

  • Increased Temperature: The temperature of the water may exceed 60°C.
  • Increased Acidity: The pH of the wash water may reach 6 or below.
  • Polycyclic Aromatic Hydrocarbons (PAHs): Byproducts of combustion processes involving petroleum products may be introduced to the water.
  • Increased Turbidity: The water may become cloudier due to suspended solids.

Global and Local Regulatory Framework

To manage these potential risks, global regulations on the monitoring, recording, and discharge quality of scrubber wash water are in place. These are primarily found in the IMO’s Resolution MEPC.340(77), known as the 2021 Guidelines for Exhaust Gas Cleaning Systems, and the MEPC’s 2022 Circular 899, which provides guidelines on risk assessments for scrubber discharge water.

Ship owners might assume that careful adherence to IMO rules ensures compliance. However, there are increasing instances of ship owners receiving significant fines from local authorities for not following local guidelines on scrubber usage. Local regulations can differ from IMO’s global standards in several ways:

  1. Express Approval: Some countries explicitly allow wash water discharge in their waters or ports. However, it is essential to consult local agents, as specific ports may have different rules.
    • Example: Brazil has stated no restrictions on scrubber water discharges, but the Ports of Parana have separate restrictions.
  2. Localized Bans on Discharge: Some jurisdictions prohibit the discharge of compliant wash water in certain areas, such as anchorages, ports, territorial seas, or Exclusive Economic Zones (EEZs).
    • Example: Argentina initially forbade wash water discharge within territorial waters, then extended this to the EEZ, and later considered suspending the regulations entirely.
  3. Notification Requirements: In some places, wash water discharge is allowed only if authorities are notified in advance and permission is obtained.
    • Example: Australia generally permits scrubber water discharge, subject to advance notification and permission from authorities. However, in certain ports like Sydney, permissions are always denied.
  4. Publicly Available Information: Some countries lack clear, publicly reported processes or procedures for wash water discharge.
    • Example: In the Caribbean, many countries, including Antigua and Barbuda, Aruba, Bahamas, Barbados, and others, do not have clear rules on scrubber discharge despite the region’s sensitive marine habitats and strict environmental standards.

Challenges for Ship Owners

The divergence in rules can make it challenging for ship owners to determine what actions are permissible and where, particularly for vessels engaged in tramp trade, as they may need to adjust procedures at each destination.

To assist members in navigating these complexities, Bimco offers a resource that maintains an up-to-date list of known regulations for scrubber wash water discharge in each country. Ship owners can also consult local agents and the Club’s local correspondents for advice if they are unsure of the regulations in a specific area or if they receive a related penalty from authorities.

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Source: The Shipowners’ Club