For reasons of economy, this document is printed in a limited number. Delegates are 

kindly asked to bring their copies to meetings and not to request additional copies.

I:\MEPC\58\2-1.doc 

INTERNATIONAL MARITIME ORGANIZATION

IMO 

E

MARINE ENVIRONMENT PROTECTION 

COMMITTEE 

58th session 

Agenda item 2 

MEPC 58/2/1

 19 March 2008

 Original: ENGLISH

HARMFUL AQUATIC ORGANISMS IN BALLAST WATER 

Application for Final Approval of the OceanSaverÆ Ballast Water Management System 

(OS BWMS) 

Submitted by Norway 

SUMMARY

Executive summary: This document contains non-confidential information related to the 

application for Final Approval of the OceanSaverÆ Ballast Water 

Management System in accordance with the Procedure for approval 

of ballast water management systems that make use of Active 

Substances (G9) adopted by resolution MEPC.126(53) 

Strategic direction: 7.1 

High-level action: 7.1.2 

Planned output: 7.1.2.4 

Action to be taken: Paragraph 6 

Related document: BWM/CONF/36, MEPC 53/24/Add.1, MEPC 57/2/6, MEPC 57/2/10 

and BWM.2/Circ.12 

Introduction

1 Regulation D-3.2 of the International Convention for the Control and Management of 

Shipsí Ballast Water and Sediments stipulates that ballast water management systems that make 

use of Active Substances to comply with the Convention shall be approved by the Organization. 

2 The Procedure for approval of ballast water management systems that make use of Active 

Substances (G9) identifies the information that should be included into a proposal for approval 

(MEPC 53/24/Add.1, annex 4, paragraph 4.2.1) and provisions for risk characterization and 

analysis (MEPC 53/24/Add.1, annex 4, paragraph 5.3). According to section 6 of 

Procedure (G9), the Organization should evaluate the information provided in the application. 
MEPC 58/2/1 - 2 - 

I:\MEPC\58\2-1.doc 

3 According to BWM.2/Circ.12, a document on the proposal for approval containing all the 

non-confidential data related to the respective ballast water management systems that make use 

of Active Substances needs to be submitted to MEPC 58. 

4 The competent authority in Norway has verified the application dossier and believes that 

it satisfies the data requirements of Procedure (G9). 

5 Norway therefore submits the non-confidential part of the manufacturerís application 

dossier, as set out at the annex to this document, to the Organization for evaluation according to 

Procedure (G9). The complete dossier will be made available to the experts of the 

GESAMP-BWWG with the understanding of confidential treatment. 

Action requested of the Committee 

6 The Committee is invited to consider the proposal for approval and decide as appropriate. 

*** 
MEPC 58/2/1 

I:\MEPC\58\2-1.doc 

ANNEX 

NON-CONFIDENTIAL INFORMATION ON THE OCEANSAVERÆ BALLAST WATER 

MANAGEMENT SYSTEM (NORWAY) 

Contents

1 INTRODUCTION 

2 OVERVIEW OF THE OCEANSAVERÆ BWMS 

2.1 OceanSaverÆ Ballast Water Management System ñ treat sequence 

2.2 Ship system interface implications 

2.2.1 Operational implications 

3 OVERVIEW OF THE INFORMATION BASIS FOR THE APPLICATION

3.1 Land-based tests for approval of the BWMS (G8) 

4 ACTIVE SUBSTANCES 

4.1 Identification of Active Substances 

4.2 Active Substance decay 

5 RELEVANT CHEMICALS 

6 DATA-SET FOR ACTIVE SUBSTANCES AND RELEVANT CHEMICALS 

7 ECOTOXICOLOGICAL RESPONSES OF TREATED BALLAST WATER

7.1 Introduction 

7.2 Growth inhibition of the marine algae Skeletonema Costatum 

7.3 Invertebrate toxicity testing 

7.4 Fish toxicity testing 

7.5 Summary and conclusion with regard to ecotoxicity 

8 ENVIRONMENTAL RISK ASSESSMENT ñ BALLAST WATER DISCHARGE 

8.1 PNEC evaluation based on toxicity testing of treated ballast water 

8.2 Environmental risk assessment applying the MAMPEC Model 

8.3 SINTEF - environmental risk assessment in two harbours 

8.4 Risk assessment - discharge of hypoxic ballast water 

8.5 Conclusion - environmental risk assessment 
MEPC 58/2/1 

ANNEX 

Page 2 

I:\MEPC\58\2-1.doc 

9 HUMAN EXPOSURE ASSESSMENT 

9.1 Introduction 

9.2 Risk characterization during normal operation 

9.2.1 Risk characterization for the operator during ballasting 

9.2.2 Risk characterization for the crew and general public during ballasting 

9.2.3 Risk characterization for the operator and crew during discharge of ballast water 

9.2.4 Risk characterization for the general public during discharge of ballast water 

9.3 Risk characterization during maintenance 

9.3.1 Maintenance of the C2E unit 

9.3.2 Maintenance of the ballast water tanks 

9.4 Risk characterization in accident situations 

10 CORROSION 

10.1 Introduction 

10.2 Testing 

10.3 Results 

10.4 The addition of the C2E disinfectants 

1 INTRODUCTION 

This report contains the non-confidential information concerning the OceanSaverÆ Ballast Water 

Management System (OS BWMS) and is structured in accordance with the Procedure for 

approval of ballast water management systems that make use of Active Substances (G9). 

The application for Final Approval submitted to IMO consists of two parts: 

ñ a summary document containing non-confidential information submitted by the 

Member to MEPC (this document); and 

ñ a full and comprehensive application dossier submitted to the IMO secretariat 

accompanied by a complete set of annexes containing reports, assessments and 

confidential information about the OceanSaverÆ BWMS. 

Besides covering the requirements of Procedure (G9) and the GESAMP-BWWG Methodology, 

the application also includes information meeting the recommendations and requests provided by 

the GESAMP-BWWG in the report of its fifth meeting (MEPC 57/2/10), recommending that 

Basic Approval to be granted the OS BWMS. The GESAMP BWWG comments are listed below 

with a reference to the section in this document containing information relevant to the 

comments: 

1 ìThe application indicates that the sequence of the different treatment elements 

may be varied. In any application for Final Approval, the Group would require a 

definite configuration to be submitted for evaluation.î (section 2); 

2 ìWhere the use of Nitrogen is concerned, the Group considers that high nitrogen 

levels and consequent oxygen depletion in the headspace of ballast tanks could 

form a hazard to human health and that deoxygenated ballast water could form a 

hazard to the environment unless adequately oxygenated prior to discharge of 

ballast water.î (sections 8 and 9);
MEPC 58/2/1 

ANNEX 

Page 3 

I:\MEPC\58\2-1.doc 

3 ìThe applicant claims that TRO had disappeared in less than 24 h. However, it 

requires explanation why the ecotoxicity tests carried out all showed ecotoxicity 

even 5 days after treatment.î (sections 4 and 7);

4 ìThe Group expects that the applicant will provide a complete environmental risk 

assessment as part of an application for Final Approval.î (section 8);

5 ìThe Group considered that the mitigation steps included in the application i.e. 

re-aeration prior to discharge would be an important factor, in reducing the 

discharge concentrations of a variety of Active Substances and by-products.î

(section 8);

6 ìTaking the above into consideration, the Group recommends that for Final 

Approval, the Applicant should submit the BWTS HES, namely to address 

nitrogen exposure as here is an identified risk in several areas adjacent to a 

nitrogen-filled space.î (section 9); 

7 ìThe Group recommends that for Final Approval description of the operation 

units where human exposure can take place should be submitted according to 

HES (MEPC 56/2/2, annex 9). The Group recommended that for Final Approval, 

the Applicant should submit a BWTS HES, where unit operations for the nitrogen 

system and electrochemical system are described in terms of where, when and 

how human exposure can take place (please see HES, MEPC 56/2/2, annex 9).î

(section 9); and 

8 ìThe Group noted that no corrosion tests were carried out with the complete 

OceanSaverÆ treated ballast water, which would include electrochemical 

activation and cavitation.î (section 10).

2 OVERVIEW OF THE OceanSaverÆ BWMS 

The OceanSaverÆ Ballast Water Management System (OS BWMS) applies cavitation, nitrogen 

supersaturation and disinfection as main working principles following a pre-filtration step. 

The OS BWMS consists of several components which may be categorized as both ancillary 

components and as OceanSaverÆ components. The ancillary components are industrial type 

equipment developed for the maritime industry, and are applied on board ships for various 

purposes worldwide. For these components the OS BWMS is not committed to use a singular 

manufacturer or a specific component, but rather it is more pertinent to specify equipment 

performance characteristics and deliverables. The OceanSaverÆ components on the other hand 

are specifically developed and designed for the OS BWMS and thus require a more in-depth 

specification. 
MEPC 58/2/1 

ANNEX 

Page 4 

I:\MEPC\58\2-1.doc 

The OS BWMS treatment sequence is fixed and illustrated in Figure 1 below and further 

elaborated upon in the following text. 

Figure 1: The OSBWMS: Main Components 

2.1 OceanSaverÆ Ballast Water Management System ñ treatment sequence 

On ballast uptake, following the ballast water pump, the water enters a mechanical filtration unit 

to remove particles and organisms. The filter includes automatic back flushing, which removes 

the larger trapped particles and organisms and thus contributes in protecting the remaining 

treatment components and at the same time contributes to the reduction of accumulated 

sediments in the ballast water tanks. 

Following filtration, the ballast water is subjected to controlled intense pressure pulses arising 

from hydrodynamic cavitation. In the OS BWMS, the cavitation is generated in a specially 

developed circumferential cavitation chamber (the C3T unit), which operates over a flow rate and 

differential pressure range with the aid of either active or passive back pressure controls 

(depending on the overall configuration of the specific ballast water system including the ballast 

water tanks). Harnessed in this way, these pressure pulses are intense enough to rupture cell 

membranes and destroy particles and organisms by forcing them to rupture, collapse or collide 

with one another. In order to achieve desired flow rate capacities, the C3T unit is stacked with 

identical C3T sub-units, duplicated and arranged along a circumference and integrated in the 

actual ballast water pipe in a manner providing identical flow conditions and thus identical 

efficacy for each individual sub-unit. 
MEPC 58/2/1 

ANNEX 

Page 5 

I:\MEPC\58\2-1.doc 

Following exposure to cavitation, the ballast water is then supersaturated by the injection of 

nitrogen before it enters the vesselís ballast water tanks. Nitrogen supersaturation causes oxygen 

naturally dissolved in the water to be released, leaving the water in the tanks deficient in oxygen 

(in a hypoxic condition) and thus, severely affecting residual organisms that are dependent on 

oxygen for their survival. The released oxygen and surplus nitrogen is evacuated by the use of 

conventional tank ventilation arrangements. In order to avoid further natural release of the 

nitrogen over time and to prevent potential contamination by outside air entering the ventilation 

system a pressure-vacuum device is incorporated into the ventilation system of the ballast water 

tanks (the vent-head) to maintain and allow control of optimum saturation levels during a 

voyage. 

Additionally, in order to ensure compliant efficacy as a function of varying ballast water 

properties, the system also incorporates an isolated electrodialytic process based on the principles 

of an electrochemical activation technology, the C2E process. The C2E unit applies the principle 

of electrochemical activation to a small portion of the flow, producing a disinfectant which is 

returned to the main flow following cavitation (C3T) exposure in conjunction with 

supersaturation in order to enhance the overall biological efficacy. The C2E unit does this by 

generating controlled amounts and variations of Active Substances in situ without adding any 

Preparations to the water. A feature of the process is that these activated substances naturally 

degrade over a relative short period of time. Further, the efficacy of the disinfectant is enhanced 

by cavitation since the cavitation causes fragmentation and separation of bacterial colonies etc., 

which expose organisms previously protected by the surrounding colony to the disinfectant, 

thereby, creating a significant increase in biological efficacy at modest dosage and concentration 

levels. To meet necessary range of flow rates, the C2E unit is modularly composed and consists 

of a number of identical cells powered by a number of identical rectifiers. 

During ballast water discharge, the ballast water pump pumps the ballast water from the 

respective ballast water tanks. In this mode, the water is exposed to cavitation (C3T) only. 

2.2 Ship system interface implications 

The introduction of ballast water treatment, regardless of measure or measures applied, is most 

likely to have impacts that may introduce requirements to other on board ship systems. Analysis 

of the OS BWMS has identified such implications: 

ñ existing or conventional approaches to supply system (pump, piping and 

distribution); 

ñ automation, control and monitoring; and 

ñ corrosion and potential coating degradation. 

The generation of hydrodynamic cavitation introduces additional pressure losses to the overall 

ballast water system when compared to conventional non-treatment ballast water systems. This is 

taken into account by including the pressure losses generated in total by the system including 

the C3T unit when specifying the ballast water pump requirements. For some vessels this 

requirement may introduce an additional boosting pump instead of an upgrade of the actual 

ballast water pump specification. Note that an increased system pressure may impact piping 

arrangements as this may be specified to a diverging design pressure specification. This is an 

issue arising when considering the installation of the OS BWMS on board an existing vessel. 

For new vessels, this issue will have been addressed in the system requirement specification. 
MEPC 58/2/1 

ANNEX 

Page 6 

I:\MEPC\58\2-1.doc 

The extent of on-board automation may vary considerably from one vessel to another and 

consequently representing a considerable challenge in relation to interface flexibility. The 

OS BWMS has an internal automation, calibration and data monitoring, storage and reporting 

system. This administrates and controls overall performance between all components/processes 

within the system and records all measured data. This allows the OS BWMS to operate with 

simplified interfaces limited to the vessels ballast water pump and distribution. The system 

includes recording and storage of data in accordance with the requirements as specified in the 

Guidelines for approval of ballast water management systems (G8). 

Comprehensive corrosion and coating impact studies including literature assessments, 

small-scale and laboratory studies as well as full-scale studies have been conducted. The main 

objectives of these studies have been to verify that the OS BWMS does not accelerate corrosion 

nor the ageing of corrosion protection systems (coatings) and also that the system is compliant 

with the intentions of Performance standard for protective coatings for dedicated seawater ballast 

tanks in all types of ships and double-side skin spaces of bulk carriers adopted by 

resolution MSC.215(82). It may be noted that the full-scale studies included all treatment stages 

with the exception of the addition of the disinfectants produced by the C2E unit 

(filtration, cavitation and supersaturation). An additional study has since been undertaken 

including this treatment stage. Results from these studies are further discussed in section 10. 

2.2.1 Operational implications 

The performance of the C2E component in the OS BWMS depends upon the use of saline 

seawater or alternatively a brine solution. The electrochemical activation process will operate 

satisfactorily with a level of seawater salinity of 0.7% and above. In cases where the ballast water 

taken on board has a level of salinity below this point, measures are installed to ensure that the 

saline level in the feed water to the unit remains within satisfactory levels. 

The electrochemical activation technology applied within the C2E unit will generate a limited 

quantity of hydrogen (H2). Since hydrogen is a flammable gas which may also be explosive 

under certain conditions, this naturally raises various concerns. These concerns have been 

comprehensively addressed in a separate study including theoretical considerations verified by 

field test programs. The study has addressed potential accumulation of hydrogen at dangerous 

levels in spaces as applicable (C2E location, engine room, ballast water pipe line, ballast water 

tanks, etc.). Based on this study, a safe gas evacuation system has been specified and developed. 

The system rests upon the principles of collection at source, dilution by air to safe concentration 

levels and evacuation to open air. 

Hydrogen is flammable at concentrations of 4% and explosive at levels above 18%. The safe gas 

evacuation system includes continuous dilution to less than 1%. Safety features are employed to 

ensure reliable collection at source, continuous dilution and evacuation. The approach on safe gas 

evacuation as identified for the OS BWMS has been benchmarked with approaches implemented 

for other systems on board ships producing H2 (e.g. electrochemical bio-fouling units for cooling 

systems, battery charge stations, etc.). 
MEPC 58/2/1 

ANNEX 

Page 7 

I:\MEPC\58\2-1.doc 

3 OVERVIEW OF THE INFORMATION BASIS FOR THE APPLICATION 

The system has been the subject of continuous performance assessments and development for a 

duration accumulating to more than 5 years. This has incorporated: 

ñ initial small-scale laboratory studies (flow rates flow < 5 m3

/h) at the DNV 

laboratories (2003 ñ 2004); 

ñ small- and medium-scale (flow rates < 40 m3/h) land-based tests at the 

MetaFil laboratory at Fagerstrand from May 2005 to March 2008; 

ñ the OS BWMS test unit of 200 m3/hr capacity (operational range: 190ñ250 m3/hrs). 

This was commissioned in June 2007. Compliant land-based testing in accordance 

with the IMO Guidelines (G8)/Procedure (G9) started in August 2007 at NIVAís 

facility at Solbergstrand, Norway. The compliance tests in Guidelines (G8 )were 

successfully finished in November 2007; 

ñ endurance tests (OS BWMS 200 m3

/ hrs test unit) test unit (January 2008 and 

ongoing); 

ñ the development process has incorporated two prototype ship installations which are 

used actively as research platforms. A full installation of the OS BWMS is now on 

board the MV Hˆegh Trooper. A total of two full-scale corrosion studies 

(DNV/ Safinah Ltd.) and 18 on-board biological efficacy studies have been carried 

out (University of Bergen (UNIFOB)/GoConsult) including two approval tests 

(shipboard testing) under Guidelines (G8); 

ñ parallel laboratory assessments of corrosion control and coating impact studies in 

compliance with DNVís respective standards (DNV/ Safinah Ltd.). 

ñ consequential analysis addressing the potential impacts of the inclusion of the C2E 

treatment step to the overall coating/corrosion achievements by the remaining 

treatment stages (nitrogen supersaturation and consequential oxygen reduction. 

(Safinah Ltd.); 

ñ environmental Risk Assessment (in accordance with Guidelines (G8)/Procedure (G9) 

(DNV/ NIVA/ Sintef); 

ñ installation studies including vibration analysis (StoGda sp.zo.o Ship Design and 

Engineering (Poland)); 

ñ testing of a data recording and monitoring system for functionality control of the 

treatment system under the EU CRAFT Programme (OceanSaver Ballast Water 

treatment) (Pole Star Ltd./Houm as/MAS as/Technological Institute of Norway (TI); 

ñ the development of a singular platform for system automation, calibration and data 

recording, processing and storage (Batronic AS); 

ñ safety assessment associated with gas production by electrolysis; production, 

separation dilution and removal (IGAGIC (UK)/ GexCon as); 
MEPC 58/2/1 

ANNEX 

Page 8 

I:\MEPC\58\2-1.doc 

ñ a study of the efficacy of filtration under dirty load situations. The initial filtration test 

was undertaken in 2005 at the research facility of NIOZ, the Netherlands 

(DNV/NIOZ); 

ñ industrialization ñ feasibility assessments looking at improvements with focus on 

sampling, system interactions including shipboard automation, installation and 

maintenance issues etc. For this, the vesselís crew has been engaged in order to attain 

experience feedback to be used in the process of industrialization; 

ñ conceptual feasibility studies regarding OS BWMS onboard; chemical carriers 

(including product carriers/LNG carriers/crude oil carriers/bulk carriers (larger class). 

These studies were undertaken by DNV; and 

ñ human exposure assessment. 

3.1 Land-based tests for approval of the BWMS (G8) 

The tests were conducted at NIVAís test site located at Solbergstrand, 20 km south of Oslo. 

Seawater is supplied from various depths down to 60 m in the Oslofjord, while fresh water is 

supplied from ground water bore holes or from a local creek. 

The test facility includes 4 glass-fibre reinforced polyester tanks, supplied with inlet and outlet 

arrangements and equipment for proper cleaning. The three tanks for storage are covered to 

mimic real conventional ballast tank conditions, e.g. preventing light introduction and limiting air 

exchange. The surfaces of the test tanks (TT1 and TT2) and the control tank (CT1) are coated 

with coatings widely applied for ships ballast tanks (Balloxy HB light, Jotun, Norway). 

Figure 2: Transfer of test water during one test cycle with the OS BWMS including a test line 

(blue) and a control line (red). Sampling numbers are indicated by S1-S5. Note that nitrogen 

supersaturation is not included in the illustration for purposes of clarity. 

The different water transfers between tanks via the OS BWMS during a test cycle including the 

control, is shown in Figure 2. One test cycle (blue lines) includes the consecutive treatment 

of >200 m3

 test water by the OS BWMS (including filter, C3T cavitation, C2E disinfectants as 

WST 

516 m3

 S2

TT1 

231 m3 

S5

C3T

TT2 

205 m3

CT2 

205 m3

S1 

 S3

S4 

filter 

Pump 

C3T cavitation unit 

C2E electrodialytic unit

C2E
MEPC 58/2/1 

ANNEX 

Page 9 

I:\MEPC\58\2-1.doc 

well as nitrogen injection for supersaturation), transferring the test water from tank with prepared 

test water (WST) to a ballast water tank (TT1). The treated water is stored in TT1 for a minimum 

of 5 days. After 5 days, the water is transferred by the feed pump, ballast pump and the booster 

pump, by-passing the filter and the C2E unit, but treated in the C3T unit, to TT2 for sampling 

before discharge. Note that discharge does not involve the use of C2E nor nitrogen 

supersaturation. Tank ventilation management by means of pressure/vacuum valve control is 

fitted on the tank (TT1) simulating the vessels ballast tank ventilation arrangement as specified in 

the OS BWMS. 

A control cycle (red lines) is run by transferring >200 m3 of the same type of prepared test water 

from WST to a ballast tank (CT2) for at least 5 days storage using the pump of the OS BWMS, 

but in by-pass of the treatment units. After storage the control water is pumped to TT1 for 

sampling before discharge. 

An overview of the relevant analysis of disinfection by-products (DBP) and ecotoxicity tests 

done with water treated in the land-based tests under Guidelines (G8) is presented in Table 3-1. 

Note that in addition, results from similar analysis (DBP and ecotoxicity tests) from a pre-test 

with medium salinity carried out in June 2007 were presented in the application for Basic 

Approval. 
MEPC 58/2/1 

ANNEX 

Page 10 

I:\MEPC\58\2-1.doc 

Table 3-1 Overview of ecotoxicity tests and disinfection by-product analysis carried out in 

the land-based tests in accordance with Guidelines (G8) 

Test 

cycle Date Salinity PSU 

TSS, 

mg/L 

DOC, 

mg/L 

POC, 

mg/L Samples/Analysis 

1 8-13th 

Aug 07 > 32 15.7 2.2 3.3 

2 15-20th 

Aug 07 > 32 15.3 2.2 3.0 

Ecotoxicity-Skel (Day 5) 

Ecotoxicity- Acute Turbot (day 5) 

Ecotoxicity ñ Chronic turbot ñ 1 (day 5) 

3 22-27th 

Aug 07 > 32 13.0 2.8 2.6 

Ecotoxicity-Skel (Day 0, 5) 

Ecotoxicity-Nitocera (day 5) 

Ecotoxicity ñ Chronic turbot ñ 1 (day 5) 

4 

29th 

Aug3th Sep 

07 

> 32 10.8 3.0 3.1 

Ecotoxicity-Skel (Day 0, 5) 

Ecotoxicity-Nitocera (day 5) 

Ecotoxicity ñ Chronic turbot ñ 1 (day 5) 

5 5-10th

Sept 07 > 32 76.2 2.6 2.9 

By-products (day 0, 5) 

Ecotoxicity-Skel (Day 0, 2, 5) 

Ecotoxicity-Acartia (day 5) 

Ecotoxicity ñ Chronic turbot ñ 1 (day 5) 

6 12-17th

Sept 07 < 22 69.5 8.9 11.6 Ecotoxicity-Skel (Day 0, 5) 

7 19-24th

Sept 07 < 22 67.6 8.3 11.2 

By-products (day 0, 5) 

Ecotoxicity-Skel (Day 0, 5) 

Ecotoxicity-Acartia (day 5) 

Ecotoxicity-Nitocera (day 5) 

Ecotoxicity- Acute Turbot (day 5) 

Ecotoxicity ñ Chronic turbot ñ 2 (day 5) 

8 3-8th

Oct 07 < 22 68.5 9.9 9.9 Ecotoxicity-Skel (Day 0, 5) 

Ecotoxicity ñ Chronic turbot ñ 2 (day 5) 

9 10-15th

Oct 07 < 22 64.5 8.6 11.5 Ecotoxicity-Skel (Day 0) 

Ecotoxicity ñ Chronic turbot ñ 2 (day 5) 

10 17-22th

Oct 07 < 22 66.9 7.8 11.0 Ecotoxicity-Skel (Day 0, 5) 

Ecotoxicity ñ Chronic turbot ñ 2 (day 5) 

11 24-29th

Oct 07 < 22 67.9 7.6 11.0 

By-products (day 0, 5) 

Ecotoxicity-Skel (Day 0, 2, 5) 

Ecotoxicity ñ Chronic turbot ñ 2 (day 5) 

12 

31th 

Oct5th Nov 

07 

< 22 81.6 9.0 12.7 

By-products (day 0, 5) 

Ecotoxicity-Skel (Day 0) 

Ecotoxicity ñ Chronic turbot ñ 2 (day 5) 

13 7-12th

Nov 07 > 32 14.4 2.2 2.7 By-products (day 0, 5) 

Ecotoxicity-Skel (Day 0, 5) 

14 14-19th

Nov 07 < 22 76.4 8.5 10.2 By-products (day 0, 5) 

Ecotoxicity-Skel (Day 0, 5) 

Results from these tests are presented in the following sections. 
MEPC 58/2/1 

ANNEX 

Page 11 

I:\MEPC\58\2-1.doc 

4 ACTIVE SUBSTANCES 

4.1 Identification of Active Substances

The component of the OS BWMS deemed relevant for Active Substance approval is the C2E 

unit (MEPC 57/2/6). Active Substances are produced in the anode chamber 

(anolyte, commercial reference: AWAC) and to some extent in the cathode chamber (catholyte, 

commercial reference: AWAL) of the C2E unit. The Active Substances formed in the C2E unit 

are primarily hypochlorous acid (HClO) with concentrations of chlorine gas (Cl2), ozone (O3), 

hydrogen peroxide (H2O2), chlorine dioxide (ClO2) and hypochlorite (ClO-). In seawater these 

oxidants react with bromide (Br-) and generate hypobromous acid and hypobromite ion. 

The resulting mixture of oxidants (mainly hypochlorous acid, hypochlorite ions, hypobromous 

acid and hypobromite ion) are named Free Residual Oxidant (FRO) in the literature while 

Total Residual Oxidant (TRO) also includes the halogenamines and other less effective oxidants 

with N-C link. The maximum dosage of TRO in the OS BWMS measured in the ballast water 

line is 2.5 mg Cl/L. 

More detailed information about the Active Substance and properties of the individual oxidants 

was submitted in the application for Basic Approval (MEPC 57/2/6) and will not be repeated in 

this document. In the following text the Active Substance will be referred to either as 

Free Residual Oxidant (FRO) or Total Residual Oxidant (TRO). 

4.2 Active Substance decay 

The decay of free and total residual oxidant levels has been investigated in relevant natural sea 

water environment after OS BWMS treatment under simulated ballast water treatment conditions 

in the Oslofjord, Norway. Remaining concentrations of oxidants in the treated ballast water were 

measured with standard colorimetric methods (HACH-Lange: DPD method; SM 4500-Cl G, 

USEPA 330.5). Results from samples taken during the full scale land-based tests are presented in 

the following figures (Figures 3 to 7). 

The results show that the decay rates are very high in the first 30 minutes after injection of the 

disinfectants arriving from the C2E unit. It takes approximately one hour to treat the full volume 

(>200 m3

) of test tank TT1. During this period it was not possible to take samples from TT1. 

Highest oxidant concentration measured in samples taken from TT1 between 1 and 2 hours after 

filling started was around 1 mg Cl/L (low salinity Tests 10 and 11, and all high salinity tests). 

A 50 L sample was therefore taken from the ballast pipe for the purpose of monitoring the 

oxidant decay before samples could be taken from test tank TT1. All results in the following 

figures from before 2 hours are from these samples. 

The maximum allowable concentration of the Active Substances (Procedure (G9), 

paragraph 7.1.1) measured in the ballast tank after filling of treated water is estimated to 

be 2 mg Cl/L taking into account that the sea water taken up by a ship may be less polluted with 

organic matter than used in the land-based tests. 
MEPC 58/2/1 

ANNEX 

Page 12 

I:\MEPC\58\2-1.doc 

Medium salinity - high organic concentration

0,00

0,25

0,50

0,75

1,00

1,25

1,50

1,75

2,00

2,25

2,50

0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320

Time (min)

Free residual oxidant (mg Cl/L)

Test 6 Test 7 Test 8 Test 9 Test 10 Test 11 Test 12

Figure 3: Decay of Free Residual Oxidant in treated water from land-based approval tests with 

the OS BWMS measured by the DPD method. Measurements were done in a sample (50 L) taken 

out immediately after treatment. Test numbers refer to Table 3-1. 

Medium salinity - high organic concentration

0,00

0,25

0,50

0,75

1,00

1,25

1,50

1,75

2,00

2,25

2,50

0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320

Time (min)

Total residual oxidant (mg Cl/L)

Test 6 Test 7 Test 8 Test 9 Test 10 Test 11 Test 12

Figure 4: Decay of Total Residual Oxidant in treated water from land-based approval tests with 

the OceanSaver BWMS measured by the DPD method. Measurements were done in a sample 

(50 L) taken out immediately after treatment. Test numbers refer to Table 3-1. 
MEPC 58/2/1 

ANNEX 

Page 13 

I:\MEPC\58\2-1.doc 

Medium salinity water - high organic concentration

0,00

0,25

0,50

0,75

1,00

1,25

1,50

1,75

0

250

500

750

1000

12501500

1750

2000

22502500

2750

3000

32503500

3750

4000

425045004750

5000

52505500

5750

6000

6250

6500

6750

7000

7250

7500

Time (min)

Free residual oxidant (mg Cl/L)

Test 6 Test 7 Test 9 Test 10 Test 11 Test 12

1 day 2 days 3 days 4 days 5 days

Figure 5: Decay of Free Residual Oxidant in treated water with medium salinity 

(around 22 PSU) from land-based approval tests with the OceanSaver BWMS measured by the 

DPD method. Measurements from 0 to 2 hours are done in a sample (50 L) taken out 

immediately after treatment. Other measurements are from test tank TT1. Test numbers refer to 

Table 3-1. 

Medium salinity water - high organic concentration

0,00

0,25

0,50

0,75

1,00

1,25

1,50

1,75

2,00

0

250

500

750

1000

1250

1500

1750

2000

2250

2500

2750

3000

3250

3500

3750

4000

4250

4500

4750

5000

5250

5500

5750

6000

6250

6500

6750

7000

7250

7500

Time (min)

Total residual oxidant (mg Cl/L)

Test 6 Test 7 Test 9 Test 10 Test 11 Test 12

1 day 2 days 3 days 4 days 5 days

Figure 6: Decay of Total Residual Oxidant in treated water with medium salinity 

(around 22 PSU) from land-based approval tests with the OceanSaver BWMS measured by the 

DPD method. Measurements from 0 to 2 hours are done in a sample (50 L) taken out 

immediately after treatment. Other measurements are from test tank TT1. Test numbers refer to 

Table 3-1. 
MEPC 58/2/1 

ANNEX 

Page 14 

I:\MEPC\58\2-1.doc 

High salinity water - low organic concentration

0,00

0,25

0,50

0,75

1,00

1,25

1,50

1,75

2,00

2,25

0

250

500

750

1000

1250

1500

1750

2000

2250

2500

2750

3000

3250

3500

3750

4000

4250

4500

4750

5000

5250

5500

5750

6000

6250

6500

6750

7000

7250

7500

Time (min)

Free residual oxidant (mg Cl/L)

Test 1 Test 2 Test 3 Test 4 Test 5 Test 13 Test 14

1 day 2 days 3 days 4 days 5 days

Figure 7: Decay of Free Residual Oxidant in treated water with high salinity (around 33 PSU) 

from land-based approval tests with the OceanSaver BWMS measured by the DPD method. 

Measurements from 0 to 2 hours are done in a sample (50 L) taken out immediately after 

treatment. Other measurements are from test tank TT1. Test numbers refer to Table 3-1. 

Oemcke & van Leuwen (1998) states that the decay of residual oxidant (y) can be modeled by an 

exponential equation:

y = ce-kt

where k is the decay constant for the residual with denomination hr-1. Higher values imply faster 

decay of TRO. The decay constant for tests with the OS BWMS is approximately 0.014 hrs-1, 

which corresponds to TRO concentration of more than 0.1 mg/L for a maximum 10 days 

depending on water quality. This corresponds to decay constants found in DNV (2000) and in 

experimental work and literature cited in Oemcke & van Leuwen (1998). 

The free and total residual oxidant was monitored from treatment (simulating ballasting) (day 0) 

to discharge of ballast water after 5 days. Highest oxidant concentration measured after 5 days 

was 0.2 mg Cl/L. In a normal situation on board ships it may be assumed that the shortest 

voyages where treatment of the ballast water is required will be 24 hours. Based on the 

information above the maximum allowable discharge concentration (Procedure (G9), 

paragraph 7.1.1) is 0.5 mg Cl/L. 

5 RELEVANT CHEMICALS 

The TRO formed in chlorinated seawater are more persistent than their parent compounds. 

However, the TRO will gradually degrade in redox-reactions with inorganic and organic matter, 

with the liberation of Br-

-ions and formation of halogenated organic by-products in low 

concentrations (Relevant Chemicals). 

These Relevant Chemicals are so-called Disinfection By-Products (DBPs) that are both organic 

and inorganic substances formed when TRO react with naturally occurring compounds in the 

water. DBPs are normally formed in reactions where organic chemicals play a major part. They 
MEPC 58/2/1 

ANNEX 

Page 15 

I:\MEPC\58\2-1.doc 

are called organohalogens and are further divided into volatile organohalogens (POX) and 

adsorbable organohalogens (AOX). Figure 8 (from Taylor, 2006) summarizes the current 

understanding of halogene chemistry associated with use of oxidants in seawater systems. 

Figure 8: An outline of chemical reactions upon electrochlorination treatment of natural 

seawater (figure from Taylor 2006). 

Based on literature review and preliminary analyses of ballast water treated with OS BWMS, the 

main relevant chemicals were identified in the application for Basic Approval (MEPC 57/2/6). 

In the present study, treated water in several test cycles were sampled and analysed for AOX, 

EOX, bromate, trihalomethanes (THMs) and other halogenated organic compounds. These 

compounds were analysed to clarify if the residual oxidants produced react with organic 

substances to form potentially harmful organic compounds, and in what concentrations. Results 

are given in Table 5-1 from one of the two different laboratories used for the analysis. 

As expected, the dominating halogenated organic compound, and THM, was bromoform. 

Bromoform was detected in concentrations up to 294 μg/l. In general, halogenated organic 

compounds are not acute toxic to aquatic animals in the concentration range detected. Even the 

most toxic by-product, which is bromoform, has to be present in the mg-range to exhibit an 

acute toxic effect. Bromoform has an NOEC (No Observed Effect Concentration) for algae 

(the most sensitive trophic group) of ≥2 mg/l (Erickson and Hawkins, 1980). 

Another compound of concern is Bromate, which was not found in any of the samples 

(Table 5-1). It was expected that some bromate would be formed in the process. One should be 

aware of the analytical challenges the laboratories are faced with when processing seawater 

samples. High salinity content may interfere with some of the analytical procedures used. 
MEPC 58/2/1 

ANNEX 

Page 16 

I:\MEPC\58\2-1.doc 

Table 5-1 Concentration of AOX, EOX and oxidation by-products in control and treated 

water (day 0 and day 5) from Tests 5 and 7 (Analysis by Eurofins laboratory) 

 

Test 5, 

day 0, 

Treated 

Test 5, 

day 0, 

Control 

Test 5, 

day 5, 

Treated 

Test 5, 

day 5, 

Control 

Test 7, 

day 0, 

Treated 

Test 7, 

day 0, 

Control 

Test 7, 

day 5, 

Treated 

Test 7, 

day 5, 

Control 

AOX mg/l 2.9 1.63 0.84 3.74 0.64 3.48 5.04 0.75 

Bromate μg/l < 0.003 < 0.003 < 0.003 < 0.003 < 0.003 < 0.003 < 0.003 < 0.003 

EOX μg/l < 0.01 < 0.01 0.07 < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 

Trichlormethane μg/l < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 

Dibromchlormethane μg/l 4.6 < 0.5 5.5 < 0.5 17 < 0.5 15 < 0.5 

Tribrommethane 

(Bromoform) μg/l 110 < 1 120 < 1 200 < 1 230 2.5 

Dibromethane μg/l < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 

Dichlorbrommethane μg/l 0.51 < 0.5 < 0.5 < 0.5 0.93 < 0.5 1 2.6 

1,2,3-Trichlorpropane μg/l 2.5 2.1 2.3 4.1 2.2 2.6 1.5 1.5 

1,2-Dibrom-3-

Chlorpropane μg/l < 1 < 1 < 1 < 1 < 1 < 1 < 1 < 1 

Phenol 

2-Chlorphenol μg/l < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 

3-Chlorphenol μg/l < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 

4-Chlorphenol μg/l < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 

2,3-Dichlorphenol μg/l < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 

2,4-Dichlorphenol μg/l < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 

2,5-Dichlorphenol μg/l < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 

2,6-Dichlorphenol μg/l < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 

3,4-Dichlorphenol μg/l < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 

3,5-Dichlorphenol μg/l < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 

2,3,4-Trichlorphenol μg/l < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 

2,3,5-Trichlorphenol μg/l < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 

2,3,6-Trichlorphenol μg/l < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 

2,4,5-Trichlorphenol μg/l < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 

2,4,6-Trichlorphenol μg/l < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 

3,4,5-Trichlorphenol μg/l < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 

2,3,4,5-

Tetrachlorphenol μg/l < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 

2,3,4,6-

Tetrachlorphenol μg/l < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 

2,3,5,6-

Tetrachlorphenol μg/l < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 

PCP μg/l < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 

2-Chlortoluol μg/l < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 

4-Chlortoluol μg/l < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 

1,2,4-Tribrombenzol μg/l < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 

1,3,5-Tribrombenzol μg/l < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 
MEPC 58/2/1 

ANNEX 

Page 17 

I:\MEPC\58\2-1.doc 

6 DATA-SET FOR ACTIVE SUBSTANCES AND RELEVANT CHEMICALS 

This information was submitted in the application for Basic Approval (MEPC 57/2/6) and will 

not be repeated here. 

7 ECOTOXICOLOGICAL RESPONSES OF TREATED BALLAST WATER 

7.1 Introduction 

The IMO regulations require that treated ballast water as a minimum be toxicity tested both 

acutely and chronically at three trophic levels. Although not required in Procedure (G9), a full 

test program with acute and chronic ecotoxicity at all three trophic levels has been performed for 

both water qualities tested and in nearly all land-based tests carried out as part of approval 

procedure under Guidelines (G8). As control, non-treated ballast water has been used to ensure 

that only the effect of the treatment system is assessed. The tests and test results are summarized 

below. 

 

7.2 Growth inhibition of the marine algae Skeletonema costatum 

Pre-tests showed that the toxicity tests with S. costatum were the most sensitive endpoint. It was 

therefore decided that this test should be performed both at 0 day and at 5 day treated water. 

As both absolute amount of anolyte (AWAC) and amount of organic matter varied somewhat in 

each test, it was of interest to have a measure of variability in toxicity. Using the results of the 

algal inhibition test results, it was possible to monitor the variability in biological active levels of 

anolyte and degradation products with toxic potential. 

The algae growth inhibition tests were carried out in a concentration series of 0-100% of the 

treated ballast water diluted in untreated ballast water from the same batch. To all samples, an 

inorganic nutrient solution was added to allow unrestricted, exponential growth of the added test 

algae for three days. The results of the tests are reported as graphics showing the progress of 

growth in the cultures at various concentrations of the treated ballast water and 

concentration/response plots with a response curve fitted to the observations and indications of 

the effect concentrations EC10 and EC50 which are derived from the response curve. The EC10

and EC50 are the concentrations (expressed as % treated ballast water) that cause 10% and 50% 

reduction of the growth rate of the algae, respectively. This implies that a low EC50 indicates a 

high toxicity. For those tests that the growth inhibition was too low to derive EC10 and EC50 by 

curve fitting, the NOEC was reported as the lowest test concentration causing a statistically 

significant reduction of the algal growth after 72 hours. An example of the results is shown in 

Figures 9 and 10 below (Test 8, day 0). 
MEPC 58/2/1 

ANNEX 

Page 18 

I:\MEPC\58\2-1.doc 

1

10

100

1000

0 20 40 60 80

Hours

106 cells/l

10

18

32

56

100

Control

Concentration 

(%)

Figure 9: Growth curves of S. costatum at various concentrations of treated ballast water 

0

20

40

60

80

100

120

1 10 100 1000

Concentration (%)

Growth rate (% of control)

Figure 10: Concentration/response plot showing the effect of treated ballast water on the growth 

rate (0-72h) of S. costatum

The growth curves (Figure 9) show that the growth in the control (untreated ballast water) and at 

low concentrations of the treated ballast water (10% and 18%) was exponential throughout the 

three day incubation period as indicated by the straight curves when cell density is plotted against 

a logarithmic y-axis. At 32% concentration, the growth was slightly reduced initially, but during 

the last two days the growth rate was as high as or even slightly higher than in the control as 

indicated by the slope of the growth curve. At 56% concentration, the growth was completely 

inhibited during the first day, but after that the algae seemed to recover and the growth rate was 

almost as high as in the control in the undiluted treated ballast water. The growth inhibition was 

complete throughout the exposure period and no recovery was observed. This growth pattern 

which was seen in most of the tests, indicates a gradual decrease of the toxic effect during the 

three-day test at intermediate concentrations of the treated ballast water. The final effect 

concentrations were calculated for the average growth rate during the entire exposure period 

(0-72 hours). In this case the EC50 was 57% and the EC10 was 39% (Figure 10). Because of the 

apparent recovery of the algae during the exposure, calculation of the EC-values during the initial 

phase of the test (0-24 or 0-48 hours) would yield lower EC-values. 
MEPC 58/2/1 

ANNEX 

Page 19 

I:\MEPC\58\2-1.doc 

With respect to 0 day samples the EC50 estimates vary in the range of 16% to >100% with a 

mean of 47%. Test water with 32 PSU had a mean EC50 of 27%, while 22 PSU water had a mean 

of 68%. This difference probably reflects the influence of greater amount of organic matter in 

the 22 PSU test water, giving a more rapid degradation of the active C2E disinfectants in the low 

salinity water. It should be noted that the water samples were stored at 4-6 °C overnight before 

the toxicity tests were started. 

In most of the test runs, the EC-values were higher at 5 days after treatment than at day zero, and 

on several occasions EC50 could not be derived. Therefore, the EC10 or NOECs should be used 

for comparison. The EC10/NOEC values vary in the range of 26% to 100%, with a mean 

of 68.4% for all tests of day 5 samples. For 32 PSU, water the mean was 68.8% while it 

was 68.0% for 22 PSU water. The difference in observed effect level found for 0 day samples is 

no longer there for the 5 day samples. There were some instances were the residual toxicity 

for 5-day samples were at a level that allowed estimation of an EC50 value. The 5-day test sample 

for test Nos. 8, 10, 11 and 13 had EC50 of 66%, 53%, 93% and 39%, respectively. These values 

indicate that sometimes there are small residual amounts of biological active compounds in the 

treated water even after 5 days. 

The dose response curve is often quite steep as indicated by a low EC50/EC10 ratio. This is 

indicative of presence of powerful biological reactive compounds. In the most extreme case, the 

ratio is only 1.13 as on day 0 in test 13. The most extreme the other way is 2.7 on 2.day, test 5. 

The steep response curves can be related to the growth response pattern that was observed and 

exemplified by the growth curves in Figure 9 above. The apparent recovery of the algae at 

intermediate concentrations results in small reduction of the average (0-72 hours) growth rate as 

compared to the control cultures even if a substantial initial growth inhibition is observed. Above 

a critical concentration, however, the growth inhibition is complete and no recovery occurs. This 

response pattern may be caused by a partial destruction of the algal cells caused by the initial 

concentration of oxidants. When the concentration of oxidants is high enough to destroy all the 

cells, no recovery is observed. When only a fraction of the cells are destroyed, the remaining 

cells are able to grow at a normal rate once the concentration of oxidants has decayed below a 

critical level. The decay of the oxidant concentration is linked to the destruction of the algal cells. 

The response of algal growth inhibition tests of organic substances with a non-polar narcotic 

mode of action is usually characterized by a more constant growth reduction (less recovery) and 

lower slopes of the concentration/response curves. This may indicate that the observed effects of 

the treated ballast water are mainly due to oxidants and not by-products like halogenated 

organics. Even the most toxic halogenated organic by-product like bromoform has an NOEC for 

algae (the most sensitive trophic group) of ≥2 mg/l (Erickson and Hawkins 1980). For 

bromoform, the lowest EC50 found for algae (Skeletonema costatum) is 12.3 mg/l with respect to 

photosynthesis (Aquire, US EPA database). With an initial oxidant level of even 3 ppm, it is not 

expected that bromoform levels would reach such toxic levels. 

Bromoform has been measured in 6 of the tests (see some of the results in Table 5-1) with a 

maximum concentration in treated water after 5 days of 0.29 mg/l, and an average concentration 

of 0.185 mg/l. This value includes both measurements for test 5. As the bromoform NOEC is ≥2 

mg/l and bromoform is the most toxic halogenated organic by-product expected to occur, it is 

unlikely that any of the observed effects seen in the algal tests are caused by by-products. 
MEPC 58/2/1 

ANNEX 

Page 20 

I:\MEPC\58\2-1.doc 

Bromoform is a volatile compound; therefore, bromoform released to seawater will eventually 

end up in the atmosphere where it has a decay 1⁄2 time of 80 h (Barnes et al., 1981). It has been 

estimated that about 70% of the global bromoform production is produced by marine algae 

(Manley and Barbero, 2001). 

7.3 Invertebrate toxicity testing 

Acute toxicity testing with Acartia tonsa with 5 day treated water did not give significant 

mortality. However, the chronic reproduction test with Nitocra spinipes showed a 

significant 20% reduction in fecundity in both test water qualities. Again, indicating that there are 

small amounts of remaining biological active components in the treated water after 5 days. 

7.4 Fish toxicity testing 

Both acute and chronic testing was performed with turbot (Scopthalmus maximus) with both 

water qualities (Table 3-1). There was no mortality due to test compound in any of the tests and 

no significant reduction in growth rate observed in the chronic tests. 

7.5 Summary and conclusion with regard to ecotoxicity 

Although a general rapid reduction in toxicity was observed in the samples from day 5 compared 

to day 0 samples, several day 5 samples show a small remaining toxicity that is evident in the 

chronic toxicity studies with S. costatum and N. spinipes. This makes it necessary to perform an 

environmental risk assessment taking into consideration the observed effects in these tests. 

8 ENVIRONMENTAL RISK ASSESSMENT ñ BALLAST WATER DISCHARGE 

8.1 PNEC (Predicted No Effect Concentration) evaluation based on toxicity testing of 

treated ballast water

Treated ballast water has, after a 5- day holding period, been tested in acute and chronic tests 

with species from three trophic levels. From these tests, it is clear that algae are the most 

sensitive group. According to TGD (EU, 2003) an Assessment Factor (AF) of 100 is then 

applicable for assessment of PNECseawater. Given that there are several (11) tests available for 5 day 

holding period, the average EC10 of 62.2% is used as basis. With an AF =100 this gives a PNEC 

of 0.62 of treated ballast water. There is no significant difference between the results from high 

salinity tests, equal to 62.6% and brackish water tests, equal to 61.2%. A common average is 

therefore applicable and the common PNECseawater becomes: 

PNECseawater= Average EC10=62.2% /100=0.62% 

There is a need to redefine the units at this stage, in order to perform risk characterization. As 

evident from the toxicity testing (presented in detail in the Confidential Dossier), high EC10 

values are related to low toxicity of test water. In order to assess the PEC/PNEC ratio the 

following calculation needs to be performed. PEC=Inverse EC10 value of test water =100/EC10. 

The PNEC needs to be multiplied with 100 in order to have same unit. 

PEC/PNEC=100/EC10/PNEC*100 (1) 

Table 8-1 presents the dilution factor of ballast water necessary in order to reduce the risk below 

the threshold of PEC/PNEC=1 assuming no oxidant decay. 
MEPC 58/2/1 

ANNEX 

Page 21 

I:\MEPC\58\2-1.doc 

Table 8-1. Predicted necessary dilution factor after variable days of holding time to bring 

PEC/PNEC ratio below the risk threshold of PEC/PNEC=1. The calculation is based on the EC10

values for treated ballast water using the slopevalues calculated based on ecotoxicity results. 

The estimated PEC/PNEC ratio is calculated according to equation (1).

Holding time of treated ballast 

water in tank 

(Days) 

PEC/PNEC = 

Dilution factor 

0 346 

1 325 

2 306 

3 289 

4 274 

5 261 

6 248 

7 237 

The remaining toxicity of the treated ballast water found in the ecotoxicity tests is caused by the 

low concentrations (<0.5 mg Cl/L (0.5 ñ 0.05 mg Cl/L)) of residual oxidants after one day 

holding time. Bromoform is the most toxic disinfection by-product expected to occur in the 

treated ballast water and has been measured with a maximum concentration in treated water 

after 5 days of 0.29 mg/l, and an average concentration of 0.185 mg/l. As the bromoform NOEC 

is ≥2 mg/l, it is unlikely that any of the observed effects seen in the algal tests are caused by 

by-products. 

The above calculations assume no decay of the residual oxidants, which is a very conservative 

assumption. When the treated ballast water is discharged into coastal and harbour waters, the 

residual oxidants will be exposed to organic molecules and particles which are easily oxidized. 

A decay rate similar to the rates observed in the ballast tanks can be expected. The half-life of 

TRO just after injection of C2E disinfectants into the ballast line is less than 30 minutes. 

This slows down to approximately one day mainly due to degradation of the organic matter in the 

treated water. 

The calculated dilution factors for treated ballast water after one holding day in ballast tanks are 

used in the following risk assessments (sections 8.2 and 8.3). This dilution factor includes an 

assessment factor of 100 in accordance with the EU TGD. 

Two risk models have been applied with different traffic scenarios. The MAMPEC model 

(section 8.2) has been used in several earlier applications. In addition, the applicant has used the 

DREAM model (section 8.3) with more detailed hydrodynamic calculations where the worst case 

scenario found during a whole year modeling (February 14th) has been used as basis for the risk 

assessment. 

8.2 Environmental risk assessment applying the MAMPEC model

A simplified risk assessment of the remaining ecotoxicity was performed using the 

MAMPEC model for a worst case commercial harbour scenario. MAMPEC includes a 

commercial harbour scenario (Rotterdam case study) with specifics as shown in Table 8-2. The 

flush rate indicates fraction of water exchanged each day. 
MEPC 58/2/1 

ANNEX 

Page 22 

I:\MEPC\58\2-1.doc 

Table 8-2 The MAMPEC commercial harbour scenario 

Harbour Length 

(m) 

Width 

(m) 

Depth 

(m) 

Volume 

(m3

) Flush rate 

Commercial 

estuarine 

habour 

10000 2000 20 400x106

 0.65 

MAMPEC informs that Rotterdam in 1996 had 25,078 port arrivals with an average tonnage 

of 15,000 dwt. This indicates an average number of port calls of 68 ships per day. Table 4.23 in 

the emission scenario document for anti-fouling products (EU, 2004), tabulates size and number 

of ships at port for 1 day. This gives a total release of ballast water of 92,100 m3/day. This is 

believed to be a conservative estimate as number of ships used is much higher than average and 

not all the ships will discharge ballast water. Rather the opposite is the case as ships unloading 

cargo will take on ballast water to compensate for the cargo taken on board. 

Table 8-3: Based on the number of ships and categories given in Table 4.23 of the emission 

scenario document (EU, 2004) for a port like Rotterdam, the following ballast water volume 

released per day can be estimated. 

No. of 

ships 

Ship size 

(m) 

Dwt Ballast 

(m3

) 

Sum ballast 

(m3) 

57.0 100.0 6615 1600 91,200 

25.0 150.0 14,215 6000 150,000 

24.5 200.0 30,547 12,000 294,000 

5.5 250.0 65,646 20,000 110,000 

7.5 300.0 141,074 28,000 210,000 

1.5 350.0 303,166 44,000 66,000 

Sum 111,600 921,200 

Applying the total release of ballast water from Table 8-3, equal to 921,200 m3

/day give a build 

up of ballast water as shown in Table 8-4. It is assumed that ballast water is evenly distributed 

throughout the harbour. The dilution converges at a value of 280. This value may be compared to 

the required dilution of 261 found for 5-day old water in Table 8-1. As the dilution in the harbour 

is greater than required to meet the PNEC, the PEC/PNEC in this instance is less than 1. Using 

shorter holding times for ballast water gives a higher need of dilution and therefore an estimated 

PEC/PNEC that may be grater than 1. A worst case example using the 2-day dilution value from 

Table 8-4 gives a PEC/PNEC of 1.88. In both calculations, the TRO is assumed to be persistent 

with no decay as discussed in section 8.1. 

Several studies related to the decay of TRO have been documented that this follows an 

exponential equation with less than 30 minutes half-life of TRO immediately after discharge. 

Table 8-4 Estimated dilution of ballast water 

 Dilution 

Released ballast 

(m3

) 1 day 2 day 3 days 4 days 

921,200 434 322 295 287 
MEPC 58/2/1 

ANNEX 

Page 23 

I:\MEPC\58\2-1.doc 

Using a realistic worst case scenario from MAMPEC and estimated dilution requirements to reach 

PNEC from the land-based tests, it is found that estimated PEC/PNEC may vary between 1.88 

and 0.9 using holding times of 2-5 days based on the traffic scenario as described above. One should 

have in mind that these estimates are very conservative as they assume no oxidant decay, that all 

ships arriving at the port release ballast water (probably less than 50% do so), and the number of 

ships is 80% higher than the average number for Rotterdam. Lastly, it is unlikely that all ships 

will have ballast water that is treated with the OS BWMS technology. It is therefore highly 

unlikely that PEC/PNEC>1 will occur. 

8.3 SINTEF- environmental risk assessment in two harbours

The DREAM model tool has also been utilized to calculate the potential environmental impact 

caused by discharge of ballast water treated with OS BWMS at two different locations on the 

Norwegian coast (Mongstad and Fredrikstad). 

The model was chosen because it gives detailed hydrodynamic results where worst case 

situations may be chosen from a modeled full year discharge scenario. 

The two locations are selected due to variations in currents and hydrography. For the Mongstad 

case, the winter month of February is simulated (weak currents and stratification). For the 

Fredrikstad case, the month of May is simulated (strong river flow and also strong stratification 

due to the presence of the river water masses). 

Figure 11: Location of the two sites considered in the present report, Mongstad and the Glomma 

archipelago (Fredrikstad).
MEPC 58/2/1 

ANNEX 

Page 24 

I:\MEPC\58\2-1.doc 

The traffic used for the Mongstad port is the real traffic of crude and product tankers at this oil 

terminal as given by the operator StatoilHydro. With respect to ballast water discharge, 

Mongstad is one of the largest recipients in Europe. 

Table 8-5: The ship categories and corresponding discharges for the Mongstad case (oil terminal 

and refinery). Discharges are given as an average for one year. BW (tons) is the total amount of 

ballast water discharged over a whole year. 

Mongstad Size categories (dwt) 

Size (dwt) 12 000 50 000 100 000 150 000 250 000 350 000 SUM 

No. tankers 600 200 80 70 40 10 1000 

BW (tons) 2 880 000 4 000 000 3 200 000 4 200 000 4 000 000 1 400 000 19 680 000 

Discharge 

rate (ton/h) 600 1800 3500 5000 5500 8000 

Discharge 

depth 5 6 7 8 10 10 

The traffic in the Fredrikstad port is low and the location was chosen mainly due to the limited 

port area (water volume) and strong stratification of the water column due to large fresh water 

effluent from the river Glomma. To increase traffic and thereby ballast water discharges, the ship 

traffic from the LPG terminal KÂrst ̄ was assumed located at Fredrikstad. 

Table 8-6: The ship categories and corresponding discharges for the Fredrikstad case 

(traffic from the LPG terminal at KÂrst ̄). Discharges are given as an average for one year. 

BW (tons) is the total amount of ballast water discharged over one year. 

Fredrikstad Size categories (dwt) 

Size (dwt) 4 000 15 000 30 000 50 000 70 000 110 000 SUM 

No. vessels 180 120 120 90 80 10 600 

BW (tons) 288 000 720 000 1 440 000 1 800 000 2 240 000 440 000 6 928 000 

Discharge rate 

(ton/h) 200 750 1500 2000 2500 4000 

Discharge depth 3 5 5 6 6 7 

This study was aimed at considering environmental risk when treated ballast water is discharged 

to the sea. Based on the evaluation in section 8.1 three cases have been considered: 

- Base case: PNEC at dilution 400. No oxidant decay included 

- Case 2: PNEC at dilution 400. Oxidant decay included 

- Case 3: PNEC at dilution 260. Oxidant decay included 

Discharges from 6 different ship/tanker categories are programmed with discharges with regular 

time intervals for the various ship/tanker categories through one month for each of the locations 

selected. The DREAM model has calculated the dilution of the various discharges and thus 

determined the volumes of water impacted (at any time through the month simulated) with water 

masses diluted with a factor less than 400 or 260 (that is, PEC/PNEC > 1 for the ballast water 

when the dilution is less than 400 and 260, respectively). Two of the cases also include some 

oxidant decay (a conservative 6 hrs half-time as to the 30 min half-time experienced the 

comprehensive assessments undertaken by NIVA). 
MEPC 58/2/1 

ANNEX 

Page 25 

I:\MEPC\58\2-1.doc 

The locations considered have yearly discharge rates that are somewhat different. Total discharge 

through one year is slightly below 20 mill. tons/year for the Mongstad case, and slightly 

below 7 mill. tons/year for the Fredrikstad case. Therefore, impacted volumes of recipient water 

are expected to be larger for the Mongstad case than for the Fredrikstad case. 

Time plots are presented for calculated volumes of water impacted with dilutions less than 

required (including effects from oxidant decay) for the three cases considered (for both Mongstad 

and Fredrikstad) at any time through the simulation period. The results are presented in Table 8-7 

below. 

Table 8-7: Summary of results from DREAM simulations of volumes of water impacted with 

PEC/PNEC > 1. 

Location Case Dilution 

requirement 

Oxidant 

decay 

Maximum volume of water 

x 105 m3 (PEC/PNEC>1) 

Base case 400 No 370 

Mongstad Case 2 400 Yes 70 

Case 3 260 Yes 38 

Base case 400 No 35 

Fredrikstad Case 2 400 Yes 20 

Case 3 260 Yes 13 

As expected, impacted volumes of water are largest for the Mongstad case, without oxidant 

decay. Impacted volumes of water are smallest for the Fredrikstad case, with oxidant decay 

included. 

Details from the calculations of Case 3, PNEC at dilution 260, with decay is presented in more 

detail in the following figures. Figure 12 shows the concentration field downstream caused by the 

discharge from the various sources with the maximum volume of water impacted with a dilution 

of 260 of the ballast water (PNEC is at the concentration level of 3.846 ppm, 1000 ppm in the 

ballast water before discharge). 
MEPC 58/2/1 

ANNEX 

Page 26 

I:\MEPC\58\2-1.doc 

Figure 12, Case 3, Mongstad. Concentration field generated from discharge of ballast water for 

the case with a PNEC level of 260 dilution of the ballast water. With decay. Concentration level 

of 3.846 ppm for the tracer shown corresponds to the PNEC level of the treated ballast water 

(concentration in the discharge is assumed to be 1000 ppm of the tracer). Discharge during the 

month of February. Aerial view is shown to the left, vertical cross section is shown to the right. 

The cross section selected is shown with an arrow on the figure to the left. 
MEPC 58/2/1 

ANNEX 

Page 27 

I:\MEPC\58\2-1.doc 

Figure 13 shows the similar risk field for the concentration field shown in Figure 12. 

Figure 13, Case 3, Mongstad. Maximum risk field found in the simulations. Risks are 

encountered when the ratio PEC/PNEC > 1. Aerial view is shown to the left, vertical cross 

section is shown to the right. The cross section selected is shown with an arrow on the figure to 

the left. 

Figure 14 shows the time development of the water volume impacted by ballast water diluted less 

than 260, including effects from the decay. For such a case, the ratio PEC/PNEC > 1 and thus has 

a potential risk for damage on the biota in the recipient. Due to the decay of the toxic compounds 

in the ballast water, the water volume of the impacted water is significantly reduced, compared to 

the Base case with no TRO decay. 
MEPC 58/2/1 

ANNEX 

Page 28 

I:\MEPC\58\2-1.doc 

Time development chart

0

5

10

15

20

25

30

35

40

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27

Time (days)

g Figure 14, Case 3, Mongstad. Time development of the water volume impacted by a dilution that 

is less than 260 of the ballast water. Decay included. Calculation for the month of February. 

Units on the vertical scale is 105

 m3 of sea water. 

Case 3 represents a conservative approach since no ecotoxicity was found after a dilution of 1:2 

or more in the ecotoxicity tests. When diluting the treated ballast water in the ecotoxicity tests, 

seawater with low content of organic matter was used. If normal harbour water or coastal water 

had been used, even lower dilution than 1:2 would have given no remaining ecotoxicity as result. 

In addition, the assessment factor 100 was used as recommended by the EU TGD (2003). 

The maximum allowable discharge concentration of TRO in ballast water treated with OS BWMS 

is 0.5 mg Cl/L (ranging from 0.5 ñ 0.05 mg/Cl/L). Due to the assessment factor, this TRO has to be 

diluted with a factor 1:400 down to a concentration far below any detectable level indicating that 

there are remaining ecotoxicity at concentration down to approximately 0.001 mg Cl/L. This 

concentration is below expected concentrations of naturally occurring TRO in surface water 

exposed to sunlight. 

Different oxidant treatment systems are used to prevent bio-fouling in coastal power stations. 

Chlorination using hypochlorite or electrolysis of seawater are standard technologies for such 

treatment. According to Taylor (2006), 50 ñ 85 m3

/h of chlorinated cooling water effluent is 

discharged to the recipient coastal waters from these power stations. A 60 m3

/h discharge 

accumulate to nearly 2000 mill. m3 yearly discharge of oxidant treated cooling water. 

In comparison, the oil terminal Mongstad represents one of Europeís largest ballast water 

discharge localities with a total discharge of ballast water of 20 mill. m3

. 

Taylorís paper reviews the current understanding of the degree of impact involved of these 

discharges. The paper describes a recent collaborative programme of work on chlorination 

by products within the wider context of a number of allied studies on power station cooling water 
MEPC 58/2/1 

ANNEX 

Page 29 

I:\MEPC\58\2-1.doc 

entrainment and discharge effects. The results suggest a very limited impact of oxidant use and 

the associated chlorination by-products on receiving waters both in terms of plume toxicity or 

any more widespread ecotoxicological influence. Instead, it is the combination of applied 

temperature, pressure and the other stressors involved in entrainment within the power station 

cooling water circuits themselves that cause a marked impact in the recipient. 

8.4 Risk assessment ñ discharge of hypoxic ballast water

A study carried out by DNV (DNV, 2007) investigated the dilution of six typical scenarios of 

ballast water discharge in a harbour recipient. A total ballast water volume of 50,000 m3 is 

assumed discharged at a rate of 6,000 m3/h. A typical harbour depth of 20 m is assumed. 

The discharge velocity is assumed to be just less than 4 m/s. A discharge pipe diameter of 750 

gives a velocity of 3.77 m/s. The discharge of water is assumed to occur at 8 m depth. This may 

be assumed to be a ìworst case scenarioî compared to a surface discharge, in that a surface 

discharge may experience more turbulent mixing. 

The initial mixing of the discharge in the recipient is modelled using Visual Plumes. This is an 

industry-standard tool provided by the US EPA (see www.epa.gov/ceampubl/swater/vplume/). 

A range of 6 scenarios are defined, combining 2 cases of longshore currents with 3 cases of 

density difference between discharge and recipient, thereby investigating the effect of density 

and currents on the extent of the plume: 

.1 no density difference, no current; 

.2 no density difference, transverse current; 

.3 brackish recipient, no current; 

.4 brackish recipient, transverse current; 

.5 brackish ballast, no current; and 

.6 brackish ballast, transverse current. 

A near-zone of 300 m along the quay and 200 m from the ship side is defined. The total volume 

of this zone is 1,200,000 m3

. Therefore, excluding the effect of initial momentum and longshore 

currents, the discharge will be diluted >20 times within this zone. 

The boundary defining the near-zone has a flux area of 14,000 m2. The flux of discharged ballast 

water through this boundary, again excluding the effect of initial momentum and longshore 

currents, is 0.42 m/h. Therefore, excluding the effect of initial momentum and longshore 

currents, it can be said that the discharge will be diluted >20 times within the 300 x 200 m 

near-zone to the discharge point, and that the flux of ballast water out of this zone is low. 

The initial mixing of ballast water gives a dilution of more than 20 x within 50 m of discharge. 

This is supported by general considerations of volumes and discharge rates, which find that 

excluding the mixing effects of the initial momentum, and any longshore currents, a 20 x dilution 

is achieved in a 300 x 200 m near zone. The harbour current pattern will affect the influence zone 

to a great extent. Tidal currents and river flows can in many cases be expected to stretch the 

influence zone downstream and upstream. 
MEPC 58/2/1 

ANNEX 

Page 30 

I:\MEPC\58\2-1.doc 

Oxygen levels in coastal surface water varies normally between 6 and 14 mg O2/l depending on 

organic load and algae blooms. Degradation of organic matter will consume oxygen causing 

lower levels and the photosyntesis of algae cause higher oxygen levels. 

Ballast water treated with the OS BWMS is supersaturated with nitrogen and the oxygen level is 

between 2 and 3 mg O2/L. When ballast water low in oxygen is discharged to the sea, the oxygen 

level in the plume spreading from the point of discharge will increase due to mixing with 

oxygen-rich (6 and 14 mg O2/L) seawater. Using the dilution factor of 1:20 within 50 m of 

discharge, found in the calculations above, the oxygen level in the plume will reach the same 

level as seawater at this distance from the discharge point. Hence, discharge of ballast water will 

have a local effect on seawater quality in terms of oxygen, limited to a 50 metres distance from 

the ship. With ballast water containing 2 mg O2/l, the oxygen content in the plume 50 m away 

from the discharge is calculated to 5.8 mg O2/L. 

It may be noted that conventional (untreated) ballast water discharged from ships following some 

time of storage is characterized by typically having a reduced level of oxygen naturally 

consumed by organisms present in the water. The oxygen levels in ballast tanks after treatment 

with the OS BWMS is held constant around 2-3 mg O2/L while the oxygen levels in conventional 

ballast tanks slowly decrease and reach approximately the same level in the lower section of the 

tank after some days or weeks depending on the water quality. 

8.5 Conclusion ñ environmental risk assessment 

Two different models have been applied to assess cases in three different ports. The scenarios 

have applied a conservative approach with regards to decay as well as to discharge volumes. 

Based on the available ecotoxicity data an environmental risk assessment has been performed 

applying different models; MAMPEC and DREAM. 

The MAMPEC model is a simple box-model calculating concentrations in Rotterdam harbour 

with a worst case emission scenario assuming that all ships entering the port, discharge all ballast 

water on board. It is found that estimated PEC/PNEC may vary between 1.88 and 0.9 using 

holding times of 2-5 days. These estimates are conservative as they assume no oxidant decay. 

By including a decay rate following a exponential function as found in several earlier studies as 

well as in this study, the PEC/PNEC level is below 1 for all holding times of ballast water. 

The DREAM model includes more detailed hydrodynamic calculations, which make it possible 

to find a worst case discharge scenario for a whole year. For the Mongstad oil terminal, this was 

found to be February 14 with low stratification of the water column and weak currents leading to 

a low dilution of the discharges. With an assessment factor 100 and assuming linear decay of the 

remaining TRO, the PEC/PNEC was found to be slightly above 1 in a volume of 4 mill. m3

. 

Due to the assessment factor, the TRO has to be diluted with a factor 1:400 down to a 

concentration far below any detectable level indicating that there are remaining ecotoxicity at 

concentrations down to approximately 0.001 mg Cl/L. 

An assessment of the implications of discharging ballast water low in oxygen has also been 

undertaken. It may be noted that also untreated ballast water from ships will have a reduced level 

of dissolved oxygen dependent upon storage time and organic content. 
MEPC 58/2/1 

ANNEX 

Page 31 

I:\MEPC\58\2-1.doc 

Using the dilution factor of 1:20 within 50 m of discharge, found in the calculations in 

chapter 8.4, the oxygen level in the plume will reach the same level as seawater at this distance 

from the discharge point. Hence, discharge of ballast water will have a local effect on seawater 

quality in terms of oxygen, limited to a 50 metres distance from the ship. With ballast water 

containing 2 mg O2/l, the oxygen content in the plume 50 m away from the discharge is 

calculated to 5.8 mg O2/L. 

9 HUMAN EXPOSURE ASSESSMENT 

9.1 Introduction

The human health risk assessment of the OceanSaverÆ Ballast Water Management System 

covers risks to human health due to potential exposure to chemicals during normal operation, 

accident situations, as well as incidents following equipment maintenance as well as 

malfunctioning and failure. 

The assessment focuses on two groups: the crew on board the ship, and the general public 

(users of coastal areas, beach coastlines and offshore installations and harbours 

(GESAMP-BWWG 3/9). 

The assessment is based on the work processes/unit operations involved with the OS BWMS in 

which exposure to humans occur. A unit operation is a basic step in the process encompassing 

individual system components that are likely to lead to human exposure to Active Substances, 

Relevant Substances and by-products (GESAMP-BWWG 4/9). 

In this risk assessment, the applicant addresses nitrogen exposure, exposure to chemicals and 

substances used in the treatment process, and exposure to the halogenated by-products in treated 

ballast water, generated by the electrochemical process (C2E). The applicant assesses the 

intensity and duration of exposure to halogenated by-products, followed by a characterization of 

the risk for human health applying WHO guideline values for drinking water quality 

(WHO, 2003). The WHO guidelines are founded on comprehensive studies of risks for human 

health when exposed to disinfectant by-products. 

9.2 Risk characterization during normal operation 

9.2.1 Risk characterization for the operator during ballasting

There are two possible scenarios for operation of the OceanSaverÆ Ballast Water Management 

System as follows: 

ñ the system is operated by deck officers. The system will in this case be remotely 

controlled, preferably from a deck office. The possibility of exposure to harmful 

substances to the person in question is equal to zero; and 

ñ the system is operated by the engineers. The system is controlled from the engine 

control room (ECR). As long as the engineer is located in these premises, there is 

no exposure. 

Common for both scenarios is that engine room personnel will be performing daily routines in 

the area where the system is located. Under normal operation, the BWT system is to be 

considered as a closed circuit. There is no exposure to anolyte (AWAC), catholyte (AWAL) or 

N2 during normal operation (exposure to these substances can only occur as a result of breakage 

in the piping). 
MEPC 58/2/1 

ANNEX 

Page 32 

I:\MEPC\58\2-1.doc 

Due to possible leakage of N2, sensors detecting O2 levels are installed in all rooms affected by 

piping connecting the N2 generator to the ballast water pipeline as well as in the area where the 

N2 generator is located. There is also an internal O2 sensor inside the N2 generator for internal gas 

leakage. If the sensors detect a leakage of N2, the system automation will record an alarm and the 

system will enter shutdown mode. 

Any individual O2 sensors will activate system shutdown should the O2 level fall below 19%. It 

may be noted that the extent of this safeguard exceeds that of the requirements of class for such 

systems. 

There is no health risk for the operator during normal operation.

9.2 Risk characterization for the crew and general public during ballasting 

During ballasting, the air in the empty ballast tanks will gradually be vented out of the tanks as 

the air is replaced by the rising water and residual N2. The air can contain halogenated 

compounds found in the ballast water that could imply a health risk if inhaled. The tank air is 

released through vent-heads usually located on the deck edge, along the deck hatch frame or less 

commonly, on the side of the ship (for instance on car ships and RO/RO ships). 

Crew on deck can be exposed to the vented tank air. The intensity and duration of exposure 

depends on various factors, for instance, type of ship. On LNG-tankers, no-one is allowed on 

deck during ballasting, resulting in no exposure. On other ships, there could be crew working on 

deck while ballasting is on-going. The maximum duration of the exposure equals the duration of 

the ballasting. Duration of ballasting is maximum 10-12 hours for large ships with big ballast 

tanks (ìworst case scenarioî). 

The intensity of exposure varies with, for instance, wind conditions and how close a person is to 

the vent-head. It is not likely that anyone will be located right next to the vent-head and inhale 

the released air directly for the duration of the ballasting. More likely, persons on deck will 

inhale air from the vent-head that is mixed and diluted with ambient air, reducing the exposure to 

any halogenated by-products. The worst-case weather condition is considered to be no wind, 

reducing the effects of mixing and, hence, dilution. In a best-case scenario, wind directs the 

discharge from the vent-heads away from the ship, resulting in minimal exposure for persons on 

deck. 

The compounds detected in treated ballast water are equal to the compounds formed as 

by-products during chlorination of drinking water. WHO guidelines for drinking water1

 

(WHO, 2003) include risk assessments of inhalation of these compounds. For this reason, 

WHO Guidelines have been applied to assess the health risks for crew inhaling tank air released 

during ballasting. The assessment is done by comparing the guidelines with measured 

concentrations in treated ballast water. The compounds in question are bromodichloromethane, 

bromoform, chlorodibromomethane, dichloromethane and vinyl chloride. Table 9-1 gives 

WHO Guidelines and concentrations in treated ballast water (maximum and mean 

concentrations) for each of the compounds in question. 

 

1

 WHO has developed a comprehensive background documentation about the chemical hazards in 

drinking water for the ìWHO Guidelines on Drinking-water qualityî. The documentation can be found 

at: www.who.int/water_sanitation_health/dwq/chemicals/en. 
MEPC 58/2/1 

ANNEX 

Page 33 

I:\MEPC\58\2-1.doc 

Table 9-1: WHO guideline values for drinking-water quality and the concentrations in the 

treated ballast water 

BromodichloroMethane Bromoform Chlorodibromomethane Methylene 

bromide 

Dibromomethane 

Dichloromethane Vinyl 

Chloride 

CAS NR 75-27-4 75-25-2 124-48-1 74-95-3 75-09-2 75-01-4 

WHO Guideline 

Value (mg/L) 

0.06 0.1 0.1 0.02 0.0003 

Highest measured 

concentration in 

Ballast water 

(mg/L)* 

0.0009 0.3 0.02 0.0004 0.9 0.0003 

Mean value of 

measured 

concentration in 

ballast water 

(mg/L) 

0.00004 0.2 0.01 0.0002 0.1 0.0002 

* data from NIVA-report found in full application 

Three compounds in ballast water are found in concentrations lower than the WHO guideline; 

bromodichloromethane, chlorodibromomethane, and vinyl chloride. 

Two compounds are found in concentrations higher than the WHO guideline value for drinking 

water quality; bromoform and dichloromethane. The implications of this is investigated further 

by calculating the concentration of bromoform and dichloromethane in the air just above the 

water surface using Henrys law, and comparing these calculated values with the Norwegian 

administrative norm2

 for 8 hours work. The concentration of bromoform in the air was calculated 

to 0.004 mg/m3 and the administrative norm is 5 mg/m3. The concentration of dichloromethane 

was calculated to 0.056 mg/m3 and the administrative norm is 50 mg/m3

. Thus, the calculated 

concentration values in the vented air for these two compounds are much lower than the 

Norwegian administrative norms. 

The compound dibromomethane identified in the ballast water is not mentioned in the WHO 

guideline. The measured concentration in the ballast water was low with a maximum 

concentration of 0.0004 mg/L (Table 9-1). The concentrations of dibromomethane are on the 

same level as the concentrations of vinyl chloride, and it is not more toxic (EPA, 2008 ). On this 

basis, dibromomethane in treated ballast water is considered to imply the same health risk as 

vinyl chloride. 

The low concentrations of compounds in ballast water compared to WHO guidelines for drinking 

water and Norwegian administrative norms indicate that the health risk related to inhalation of 

tank air for persons on deck is very low. It is worth noting that exposure to tank air is less 

frequent and of lower intensity than exposure to drinking water vapours, which should imply that 

the risk characterization is conservative. There is no need for risk mitigation measures. 

If the wind directs the released tank air to the nearby port/coast, third party in the port/coast can 

be exposed to the tank air. The health risks involved for third party is equally very low.

Release of N2 through the vent heads is of no health risk to persons on deck, as N2, being lighter 

than air, will rise up vertically in the open rapidly, and disappear. 

 

2 The Norwegian administrative norm is based on EEA- requirements.
MEPC 58/2/1 

ANNEX 

Page 34 

I:\MEPC\58\2-1.doc 

9.2.3 Risk characterization for the operator and crew during discharge of ballast water 

There is no exposure to the operator or crew during discharge of ballast water as the ballast water 

is discharged under sea level. 

9.2.4 Risk characterization for the general public during discharge of ballast water 

Seafood such as shellfish and fish can be harvested from areas where treated ballast water is 

discharged. The halogenated compounds found in treated ballast water are found to be not 

bio-accumulating (MEPC 57/2/6). Hence, these compounds will not be found in seafood. As a 

result, there is no health risk connected to consumption of seafood taken from areas where ballast 

water is discharged. 

People can be swimming in ports or nearby beaches while ships are discharging treated ballast 

water, possibly getting exposed to treated ballast water via skin contact, inhalation (of vapours) 

and swallowing of (small amounts of) seawater. WHO guidelines for drinking water quality are 

used to assess the health risks in connection with swimming. The guidelines cover risk 

assessments of halogenated compounds for all three exposure paths. Two compounds in treated 

ballast water have been found in concentrations higher than the WHO guideline; bromoform and 

dichloromethane, the latter found in the highest concentration compared to the guideline value. 

The mean concentration of dichloromethane is 5 x guideline value, and the maximum 

concentration is 45 x the guideline value. When discharged to sea, the plume of ballast water will 

be diluted in seawater, reducing the concentrations of dichloromethane in the plume. The dilution 

is previously modelled to 1:20 within 50 metres from the discharge (section 8.4). For anyone 

swimming in the sea at a distance of 50 m from the discharge point, the water will be of WHO 

drinking water standard in terms of dichloromethane. Concentrations of the other halogenated 

compounds will be much lower than the guideline value. Only if a person gets very close to the 

discharge (a few metres away) is there a risk of exposure to concentrations above WHO 

guidelines for drinking water. Hence, the health risk in connection with swimming in the vicinity 

of ships discharging ballast water is assessed as very low. 

9.3 Risk characterization during maintenance 

9.3.1 Maintenance of the C2E unit

As part of maintaining the cells in the C2E unit, the cells are to be flushed with AWACLEAN, 

a 7% solution of vinegar. Flushing takes place after ballasting or after approximately 10-12 hours 

of use. The C2E flushing system is a relatively simple device. The system consists of a 100-litre 

tank in addition to valves and a small pump. The flushing system is integrated in the OS BWMS 

and controlled by the OS automation with its own start/stop sequences. 

Filling up the storage tank for the vinegar is manual labour. The operator can inhale fumes from 

the vinegar during filling, and possibly spill vinegar on hands and clothes. The intensity of the 

exposure is considered low and the duration is short, as the filling procedure is completed within 

minutes. Emptying the tank is a closed circuit process. It consists of opening a valve under the 

tank and draining it to the bilge, hence, there is no exposure to vinegar that is emptied from the 

tank. 
MEPC 58/2/1 

ANNEX 

Page 35 

I:\MEPC\58\2-1.doc 

Vinegar is a dilute solution of acidic acid. Dilutions with an acidic acid concentration below 10% 

are not classified as a hazardous chemical according to European Inventory of existing 

Commercial Chemical Substances (EINECS). A 7% solution of vinegar is considered as a food 

article and there is no health risk in connection with neither normal handling nor spillage. 

9.3.2 Maintenance of the ballast water tanks 

Before entering a ballast tank, the tank must be free of both hydrocarbon and inert gasses to 

secure a safe working environment. This involves blowing fresh air into the tank to force 

accumulated gasses out. There are strict requirements and thus routines associated with securing 

safe breathable atmospheres before personnel are allowed to enter any tanks on board ships. This 

is according to class regulation. Specially trained personnel shall monitor the tankís atmosphere 

during the process, often using hand-held gas indicators which measure the percentage of 

hydrocarbons present as well as e.g. oxygen. There can be N2 in the tank resulting from the 

ballast water treatment. However, existing procedures for work in a tank means that any N2 in the 

tank due to ballast water treatment will not pose any additional health risk to personnel entering 

the tank. Hence, there is no need for additional risk mitigation measures. 

When a ballast water tank is full and N2 is accumulated in the headspace, oxygen levels will be 

low. There will be no human exposure to the gases in the headspace of the ballast tanks, as 

opening and inspection of the tank is strictly prohibited when the vessel is operating in this mode. 

This is also according to class regulation. Note also that the OS BWMS employs active tank 

ventilation management as conventional vent-heads are replaced by pressure/vacuum vent-heads. 

Thus, under normal operations, there will be no releases from the vent-heads except during 

ballasting. 

9.4 Risk characterization in accident situations 

There is no exposure to the C2E disinfectants (anolyte (AWAC), catholyte (AWAL)) or to N2

during normal operation. Exposure to these substances may occur only in the case of breakage in 

the piping. This type of fault will quickly be detected by the automation system as it includes 

internal leakage detection (inside the C2E cabinet) and pressure loss monitoring (piping) that 

monitors the process. In the case of detected leakage, alarms are recorded and an immediate 

shutdown procedure of the C2E is activated. 

If the breakage is located outside the C2E cabinet, the amount of AWAC and AWAL fluid 

spilled is limited to the amount within the pipes, from the point of leakage to the cabinet and 

confined to a few litres. Personnel can remove the liquid by conventional means, using water 

and/ or an absorbent. The person will be exposed to whatever volume that is spilled. The C2E 

solutions are classified as non-dangerous (88/279/EWG) but may cause irritation to the eyes, 

sensitive skin and throat. Conventional personal protective equipment (PPE) is considered 

adequate in order to protect against accidental exposure (i.e. gloves, and goggles). In case of 

ventilation breakdown or leakage, there is a risk of vapour or fumes to be released. These fumes 

may cause dizziness and nausea and inhalation should be avoided. Respiratory protection should 

be available. Note that ventilation performance is actively monitored. Any failure will institute an 

alarm and consequently the system shutdown. The risk to human health is considered to be low. 
MEPC 58/2/1 

ANNEX 

Page 36 

I:\MEPC\58\2-1.doc 

The C2E solution does not react with other materials and is stable and may be stored in sealed 

plastic containers. 

If the breakage is inside the C2E cabinet, this is a sealed compartment with a built-in detection 

system and the risk of exposure is considerably limited. 

There are strict safety procedures in place to minimize the health risk for crew and other persons 

on the ship in connection with N2 leakage from the N2 generator or piping. N2 is a non-toxic but 

asphyxiating gas. Due to possible leakage, sensors detecting O2 levels are installed in all rooms 

affected by piping connecting the N2 generator to the ballast water pipeline as well as in the area 

where the N2 generator is located. If the sensors detect a leakage of N2, the system will enter the 

shutdown mode. An alarm will be activated if the oxygen level is reduced to 19%, and access to 

the rooms will be denied. No-one will be able to enter the rooms until they are thoroughly 

ventilated and controlled, as the rooms will be closed, secured and have warning signs posted 

until they are safe to enter. 

N2 can migrate from the source to adjacent spaces. The safety procedures will ensure that also 

adjacent spaces and areas under potential nitrogen migration are closed, secured and warning 

signs posted. Each of the adjacent spaces will be ventilated to secure that any N2 that has 

migrated from the leakage point is vented out. When the safety procedures are followed, the 

health risks related to leakage of N2 from the N2 generator or piping is assessed as low. 

10 CORROSION 

10.1 Introduction

To complement the development work of the OS BWMS in compliance with the intentions of the 

IMO Ballast Water Management Convention and the recommendations and guidance provided in 

the accompanying Guidelines (G8) and Procedure (G9), a corrosion and coating impact test 

programme has been devised by DNV, Safinah Ltd. in cooperation with OceanSaver/ Metafil. 

This program has been carried out in order to consider any effects on ballast tank coatings and 

further to evaluate the hypotheses that OS BWMS treatment would fulfil the criteria of not being 

detrimental to ballast tank coatings and also that the hypoxic or oxygen deficient seawater would 

be beneficial in reducing the rates of corrosion. The test program has included desk-top/ literature 

assessments as well as laboratory-based and ship-based assessments. 

A total of 12 ballast tank coatings representing conventional products, present standard coatings 

as well as state of the art coatings have been included. All tests are undertaken by independent 

third parties in compliance with recognized test methods. Test reports have previously been 

submitted as enclosures to the Basic Approval. Two additional reports are included in the 

Confidential Dossier (Summary results of testing Seawater Ballast Tank Coatings under 

ìOceanSaverî Conditions (Safinah Ltd.) and Effect of Electrochemical Activation by the 

C2E component in the OS BWMS to cause Corrosion/Coating impacts in Ballast Tanks 

(Safinah Ltd.). 
MEPC 58/2/1 

ANNEX 

Page 37 

I:\MEPC\58\2-1.doc 

10.2 Testing 

The test program has included laboratory-based testing at the DNV Corrosion Laboratory in 

Bergen, Norway. Two ballast water tank simulators were applied with an unmodified tank 

acting as control with ìstandard 2 conditionsî. Two simulated test programmes were 

carried out: (1) coating study; and (2) corrosion study. 

In addition and in parallel, two shipboard test programmes have been performed focussing on 

corrosion and coating impacts, respectively. These programmes were undertaken over a period of 

more than 15 months on board the vessels; MV Hˆegh Trooper/MV Federal Welland. 

All testing has been undertaken applying filtration, cavitation (C3T) and nitrogen supersaturation 

only. The disincentive component of the OS BWMS (C2E) was excluded from testing. 

The effects of electrochemical activation represented by the C2E component in the OS BWMS to 

cause corrosion/coating impacts has been addressed in the separate study as enclosed. 

10.3 Results 

The tests confirm that a decrease of oxygen content in water and in the humid atmosphere in the 

tanks causes a decrease of the general corrosion rate of steel. A similar conclusion is drawn with 

regards to impacts on coated surfaces as references are drawn to: (1) the formation of rust; 

(2) blistering; and (3) adhesion. In the tests report, none observed rusting, none blistering and 

adhesion strength similar to unexposed laboratory retained reference control panels. 

Following an in-depth analysis of the results from tests undertaken, it is concluded that the 

OS BWMS as tested has no recognizable detrimental effect upon the coatings or upon their 

corrosion protection properties. Further, it is reported that; ì...the results show a higher anode 

consumption and current demand for the bottom panel in the untreated seawater compared to the 

nitrogen treated seawater, i.e. corrosion is suppressed under OceanSaver treatment conditions.î 

10.4 The addition of the C2E disinfectant 

Potential effect of electrochemical activation by the C2E treatment component in the OS BWMS 

to cause corrosion/coating impacts in ballast tanks when integrated with the remaining treatment 

stages has been studied. The work concludes that free residual oxidant level in the treated 

seawater is present over a period of time approximated to 24 hrs. Initial values lies in the range 

of 2 ppm. Following resting in tanks, these residual oxidants are consumed rapidly as illustrated 

in Figures 3 to 5. After 5 hours, the free residual oxidant level (FRO) is typically 

below 0.25 ppm. After a 24-hour period, levels are typically between 0.05 and 0.25 ppm. 

Based on the identified rapid consume of the free residual oxidants and the initial low starting 

level and on general available literature and experience, it is concluded that it is unlikely that the 

introduction of the C2E component will have any effect on the coatings applied for corrosive 

protection of ballast water tanks. Similarly, it is unlikely that the additional treatment component 

will affect corrosion of steel. 

It is further concluded that the overall positive effects of reduced corrosion is likely to be 

maintained with such low levels of active oxygen species present over the short timeline. 
MEPC 58/2/1 

ANNEX 

Page 38 

I:\MEPC\58\2-1.doc 

REFERENCES 

Allonier A.-S., Khalanski M., Camel V. and Bermond A. 1999. Characterization of chlorination 

by-products in cooling effluents of coastal nuclear power stations. Marine Pollution 

Bulletin 38(12): 1232-1241. 

Cherney D., Duirk S. E., Tarr J. C. and Collette T. W. 2006. Monitoring the speciation of 

aqueous free chlorine from pH 1-12 with Raman spectroscopy to determine the identity of the 

potent low-pH oxidant. Appl. Spectroscopy. Society for Applied Spectroscopy, 60(7): 764-772. 

DNV, 2000. Ballast water treatment by ozonation. DNV Report no. 2000-3229. 

EPA, 2008. Region 6 Human Health Medium- Specific Screening Levels 2008 

http://www.epa.gov/earth1r6/6pd/rcra_c/pd-n/screenvalues.pdf. 

Erickson,S.J. and C.E.Hawkins, 1980. Effects of Halogenated Organic Compounds on 

Photosynthesis in Estuarine PhytoplanktonBull. Environ. Contam. Toxicol. 24(6):910-915). 

EU, 2004. Harmonization of environmental emission scenarios: An emission scenario document 

for anti-fouling products in the OECD countries. European Commission, Directorate-General 

Environment 23 September 2004. Final report 9m2891.01. 

Fabbricino M. and Korshin G.V, 2005. Formation of disinfection by-products and applicability of 

differential absorbance spectroscopy to monitor halogenation in chlorinated coastal and deep 

ocean seawater. Desalination 176: 57-69. 

Manley, S.L. and Barbero P.E, 2001. Physiological Constraints on Bromoform (CHBr3) 

Production by Ulva lactuca (Chlorophyta) Limnology and Oceanography, Vol. 46, 

pp. 1392-1399. 

Oemcke, DJ & van Leeuwen, H, 1998. Potential of ozone for ballast water treatment. CRC Reef 

Research Centre and the Ports Corporation of Queensland, 40 pp. 

Sugam R. and Helz G.R, 1981. Chlorine speciation in seawater; a metastabile equilibrium model 

for ClI

 and BrI species. Chemosphere 10: 41-57. 

Taylor C.J.L, 2006. The effects of biological fouling control at coastal and estuarine power 

stations. Review. Mar. Poll. Bull. 53: 30-48. 

Vogelsang C, 2007. Active compounds produced by the C2E unit. Technical NIVA Report to 

OceanSaverÆ by Egil Dragsund dated July 7 2007. 

Wang, T.X., M.D. Kelley, J.N. Cooper, R.C. Beckwith and D.W. Margerum;? Equilibrium, 

kinetic, and UV-spectral characteristics of aqueous bromine chloride, bromine, and chlorine 

WHO, 2003. ìGuidelines for drinking water qualityî, 3rd edition. 

___________