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G9 Procedure (BWMS Using Active Substances)

 The G9 Procedure is the IMO approval process for Ballast Water Management Systems (BWMS) that use Active Substances (chemicals).

It is issued under the
Ballast Water Management Convention by the International Maritime Organization.

Why G9 is Required?

If a BWMS uses chemicals like:

  • Chlorine (electrochlorination)

  • Ozone

  • Peracetic acid

  • Hydrogen peroxide

These substances may:

  • Harm marine environment

  • Produce toxic by-products

  • Affect crew safety

Therefore, special IMO approval is required.

G9 Approval – Step-by-Step Procedure

1️⃣ Submission by Manufacturer

  • Manufacturer submits:

    • Chemical composition details

    • Dosage rate

    • Toxicity data

    • Environmental impact study

    • By-product formation data

To a Flag Administration.

2️⃣ Review by GESAMP-BWWG

The data is reviewed by:

  • GESAMP-BWWG (IMO expert scientific group)

They assess:

  • Environmental risk

  • Human health risk

  • Persistence in marine environment

  • Bioaccumulation effects

3️⃣ Basic Approval (Stage 1)

Granted if:

  • No unacceptable environmental risk found.

👉 This allows further testing.

4️⃣ Land-Based & Shipboard Testing

  • System tested in:

    • Land-based facility

    • Onboard vessel

To verify:

  • Biological effectiveness

  • Compliance with D-2 standard

5️⃣ Final Approval (Stage 2)

Granted after:

  • Successful performance testing

  • Environmental safety confirmation

Then system can receive Type Approval Certificate.

Important Exam Difference

G8G9
For all BWMS                        Only for systems using chemicals
Performance testing                        Environmental safety evaluation
Biological complianceToxicity & by-product risk

(UV systems → G8 only)
(Electrochlorination → G8 + G9)

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