I:\MEPC\55\2.doc 

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.

INTERNATIONAL MARITIME ORGANIZATION

IMO 

E

MARINE ENVIRONMENT PROTECTION 

COMMITTEE 

55th session 

Agenda item 2 

MEPC 55/2

 12 April 2006

 Original: ENGLISH

HARMFUL AQUATIC ORGANISMS IN BALLAST WATER 

Basic Approval of Active Substances used by Special Pipe Ballast Water Management 

System (combined with Ozone treatment) 

Submitted by Japan 

SUMMARY

Executive summary: This document contains non-confidential information for Basic 

Approval of Active Substances used by Special Pipe Ballast Water 

Management System (combined with Ozone treatment) in accordance 

with the Procedure for approval of Ballast Water Management 

Systems that make use of Active Substance (G9) adopted by 

resolution MEPC.126(53). The relevant documents and an 

application dossier will be provided to the Marine Environment 

Division of the Organization for review by the GESAMP – Ballast 

Water Working Group. 

Action to be taken: Paragraph 6 

Related documents: BWM/CONF/36, BWM.2/Circ.2, MEPC 54/2/9, MEPC 54/2/12, 

MEPC 54/21 

Introduction 

1 The Ballast Water Management Convention (BWM Convention), in its regulation D-3, 

provides that Ballast Water Management systems, which make use of Active Substances to 

comply with the Convention, shall be approved by IMO based on a procedure developed by the 

Organization. 

2 MEPC 53 adopted, by resolution MEPC.126(53), the “Procedure for approval of Ballast 

Water Management Systems that make use of Active Substances (G9)”. Section 8 of the 

Procedure sets out the methodology to be followed for the approval of Active Substances and 

requests IMO to establish a Technical Group (the GESAMP – Ballast Water Working Group) to 

review the proposals submitted by Administrations and report to the Organization on its findings. 
MEPC 55/2 - 2 - 

I:\MEPC\55\2.doc 

3 MEPC 54 agreed to invite Members to submit their proposals for approval (application 

dossiers) and the non-confidential description of the systems for MEPC 55, by Friday, 

21 April 2006 (MEPC 54/21, paragraph 2.24). 

4 This document contains non-confidential information regarding Special Pipe Ballast 

Water Management System (combined with Ozone treatment) developed by the Japan 

Association of Marine Safety (JAMS). This system holds excellence in treatment capability, is 

safe not only to ships and crew but also to the environment and uses Ozone generated on board 

the ships as an Active Substance. A brief introduction of this system has been provided in 

annex 2 of document MEPC 54/2/9. 

5 The application dossier together with relevant documents indicated in the circular 

regarding the second meeting of the GESAMP-BWWG (BWM.2/Circ.4) will be submitted to 

Marine Environment Division of the Organization to be reviewed by the Group in accordance 

with the provisions of resolution MEPC.126(53). 

Action requested of the Committee 

6 The Committee is invited to consider the proposal for approval of the Active Substances 

used by Special Pipe Ballast Water Management System (combined with Ozone treatment) for 

ballast water management. 

***
MEPC 55/2 

I:\MEPC\55\2.doc 

ANNEX

 

INFORMATION FOR BASIC APPROVAL OF ACTIVE SUBSTANCES USED BY 

SPECIAL PIPE BALLAST WATER MANAGEMENT SYSTEM (COMBINED WITH 

OZONE TREATMENT) 

1 INTRODUCTION 

This system employs a disinfection method which falls under the category of the in-line type to 

be installed in the initial ballast line for taking the ballast water. A complex of mechanical 

treatment1 by means of slit plates called “special pipe” and a chemical treatment by Active 

Substance, Ozone, heightens the disinfection effect for organisms. 

The maximum Ozone feeding ratio to the ballast water of this system is 4 mg/L. Also this 

system is designed to store the treated water in the ballast tank at least 48 hours. Ozone is 

produced by converting a part of oxygen, as raw material, by the silent electric discharge. Since 

Ozone is not commercially prepared using additives, storing it on board is not required. It can be 

produced at any time when required in certain quantity by using of a generator provided on 

board. Therefore, the system can be handled on board very easily. The generator installed on 

board can quickly respond to any unforeseen inboard accidents and is assured to be safe. 

1.1 System configuration 

Configuration of the system is shown in Figure 1. Its main treatment process employs a 

disinfecting compound unit of mechanical treatment by means of slit plates and chemical 

treatment using Ozone. A pre-treatment unit, gas/liquid separation unit and discharge unit are 

also integrated with the main unit for the improved treatment performance, safety inboard, and 

environmental precaution against discharge. That is, the system is composed of four treatment 

processes, each of them is described below. 

1.1.1 Pre-treatment unit 

Pre-treatment is required for preventing blockage of the disinfecting unit. 

1.1.2 Disinfecting unit 

Disinfecting unit is composed of mechanical treatment and chemical treatment with the 

generated Ozone. 

1.1.3 Gas/liquid separation unit 

De-aeration is a gas-liquid separation process to prevent Ozone without reaction from flowing 

into the ballast tank. An Ozone discharging unit to handle the de-aerated Ozone in the gaseous 

phase is also required.

1.1.4 Discharge treatment unit 

The system is designed to decompose oxidant remaining in the ballast water at the time of 

discharge. Active carbon, etc., act to decompose the residual oxidant to 1/10. 
MEPC 55/2 

ANNEX 

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Figure 1. System Configuration 

1.2 Conception on onboard installation 

This system can be installed by using the existing ballast line. In order to avoid human errors by 

operators, the equipment is integrated within the ballast remote control console in view of 

importance to operability. 

This system plans to be installed on an existing container ship of 60,000-ton class in 

August 2006. Figure 2 outlines a piping system diagram. 

 

Figure 2. Piping System Diagram

S.C.

O.B.

(1)プレ処理部 (2)殺滅処理部 (3)脱気処理部

(4)排出処理部 バラストタンク

S.C.

O.B.

(1)プレ処理部 (2)殺滅処理部 (3)脱気処理部

(4)排出処理部 バラストタンク

(1) Preparatory 

treatment 

unit (2) Disinfection unit (3) Gas/Liquid 

separation unit 

(4) Discharge 

Treatment Unit Ballast tank 

P

P Ballast

Tank

(Fore)

S.C

S.C

Pre-filter

Ozone Injector

O.B

FIRE MAIN

Ballast Tank (Aft)

FIRE & G.S. PUMP

200/300m3/h*0.83/0.25Mpa

FIRE,BILGE & BALLAST PUMP

200/600m3/h*0.83/0.25Mpa

Drain line

Ozone

HEELING PUMP & SYSTEM

Remote control valve

Manual valve 121 097

135

136

138

137

139

Φ8m m strainer

Additional Ballast pump

300m3/h*135m

185kw(300KVA)

Rinse pump for Pre-filter

100m3/h*20m

P

Slit 

Nozzle

P

Sampling

Gas device

Separation 

tank

Charcoal

Tank

Circulation Line

waste ozone

destruction unit 

Note) The red color indicates extend part for 

the system.

P

P Ballast

Tank

(Fore)

S.C

S.C

Pre-filter

Ozone Injector

O.B

FIRE MAIN

Ballast Tank (Aft)

FIRE & G.S. PUMP

200/300m3/h*0.83/0.25Mpa

FIRE,BILGE & BALLAST PUMP

200/600m3/h*0.83/0.25Mpa

Drain line

Ozone

HEELING PUMP & SYSTEM

Remote control valve

Manual valve 121 097

135

136

138

137

139

Φ8m m strainer

Additional Ballast pump

300m3/h*135m

185kw(300KVA)

Rinse pump for Pre-filter

100m3/h*20m

P

Slit 

Nozzle

P

Sampling

Gas device

Separation 

tank

Charcoal

Tank

Circulation Line

waste ozone

destruction unit 

Note) The red color indicates extend part for 

the system.
MEPC 55/2 

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1.3 Ozone generator 

1.3.1 Components of Ozone generator 

The Ozone generator is composed of Ozone generating unit, Ozone control panel and other 

components. Functions of each unit composing the Ozone generator are shown in Table 1. 

Table 1. Components of Ozone Generator 

Component Function 

Ozone generation 

process 

Composed of the Ozone generator to generate Ozone and the power supply unit (PSU) to 

supply electric energy to the Ozone generator. Multiple electrodes are contained in the Ozone 

generator to convert a part of oxygen in the gas to Ozone. The power supply unit (PSU) 

converts the power type from commercial frequency and low voltage to medium frequency 

and high voltage most suitable to Ozone generation. 

Ozone control 

panel (Power 

Instrumentation 

panel) 

Adjust the power output of PSU and quantity of Ozone to be generated, monitors the status of 

gas and cooling water around the Ozone generator, interlock the system to control the system 

or protect the equipment and for safety, and transfer signals to and from the central console. 

Receives all the power required for PSU and instruments and supplies the power to each 

equipment and instrument. 

Instrument Includes the emergent shut-off valve, safety valve, Ozone monitor, Ozone leakage monitor, 

dew point meter, Ozone flow meter, temperature indicator, pressure indicator, etc. Located 

online or around the Ozone generator. 

1.3.2 Peripheral units of Ozone generator 

To ensure normal operation of the Ozone generator, air as raw materials, cooling water and other 

utilities should be properly supplied. Peripheral units required for the supply of utilities are 

shown in Table 2. 

Table 2. Functions of Peripheral Units of Ozone Generator 

 Ozone Utility Function of Ozone Utility 

Air compressor Pressurizes and compresses the air to generate oxygen efficiently. When used for generating 

Ozone, an oil-free air compressor should be used. 

Filter Used to remove dust from dry oxygen supplied to the Ozone generator. 

Oxygen 

Generator (PSA) 

Unit 

Concentrates the compressed air supplied from the compressed air by pressure swing (PSA; 

Pressure Swing Adsorption) to obtain oxygen. Removes moisture at the same time to supply 

dry oxygen more than 90% to the Ozone generator. 

Cooling water 

supply unit 

(Chiller Unit) 

Used to remove heat generated in the Ozone generator. Cooling water supply unit for this 

system is an air-cooled chiller unit, etc. using coolant. Cooling water is ion exchange water 

cooled by being circulated in a closed loop. To release the pressure in the cooling water line, 

a head tank may be installed in the cooling water line. 

1.4 Safety measures for Ozone generator 

To completely eliminate the Ozone leakage, which is harmful to human health, the following 

measures are taken for the safety of the Ozone generator:

1.4.1 Provision of leaking Ozone densitometer 

Ozone leakage from the Ozone generator and Ozone piping line is harmful to human body 

(crew). Leaking Ozone densitometers are provided around the Ozone generator, ballast tank air 

vents, and other places to monitor Ozone leakage constantly. The system is designed (controlled) 
MEPC 55/2 

ANNEX 

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to raise the alarm if Ozone leakage is detected, and Ozone generation discontinues and supply of 

the Ozone gas shuts off depending on the situation

1.4.2 Emergency stop 

In the event that the Ozone generation should be put in emergency stop while the ballast water is 

treated by Ozone on board, it is designed to stop the Ozone generation immediately from the 

remote ballast control console or others. 

1.4.3 Fail-safe system 

If a power trouble or failure arises in the equipments, the fail-safe system is activated. 

2 PREPARATION, ACTIVE SUBSTANCE AND RELEVANT CHEMICAL 

Ozone used for this system as an Active Substance has strong oxidizing property and is effective 

for disinfecting aquatic organisms. Its half-life period in the water (seawater, for instance) is as 

short as 5.8 seconds and Ozone remains there for a very short term. Therefore, no Ozone 

remains in the ballast water when discharged. In the seawater, by the reaction of Ozone and 

bromide ion, bromate is generated. Bromate ion also has a strong oxidizing property and 

contributes to disinfecting. The half-life period of bromate ion is on an average 12 hours which 

is longer than that of Ozone and impact on the environment by discharged ballast is a matter of 

concern. 

Active Substance and relevant chemical used in this application is as shown in Table 3. 

Table 3. Definition of Active Substance and Relevant chemical 

 Seawater Fresh water 

Active Substance Ozone Ozone 

Relevant chemical Bromate ion - 

2.1 Preparation 

Ozone as an Active Substance is produced by a generator provided on board. Since this process 

is not a commercial preparation using additives, etc., it is not described in this application form. 

2.2 Active Substance 

In this application form, Ozone is defined as an Active Substance. Ozone exists in oxygen (raw 

material) at a ratio of 6 to 12%. Therefore, when it is used for treating the ballast water, it is in a 

state of Ozone gas. Components of Ozone gas are shown in Table 4.
MEPC 55/2 

ANNEX 

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Table 4. Components of Ozone Gas 

Name of substance CAS number Ratio 

Ozone 10028-15-6 6~12v/v%

Oxygen 7782-44-7 80~88v/v%

Nitrogen 7727-37-9 2~3v/v%

Argon 7440-37-1 4~5v/v%

2.3 Relevant chemical 

In this application form, bromate ion generated during treatment of the ballast water of the 

seawater is defined as a relevant chemical. 

Products generated by the reaction between Ozone and bromate ion in the seawater are 

hypobromous acid ion, hypobromous acid and bromate ion. Ratio of their existence varies under 

the influence of pH. Among these products, only the bromate ion is generated in the presumable 

pH range of 5 to 8 in the ballast water. Generally bromide ion accounts for 60 mg/L in the 

seawater but 0.1 mg/L or below in the fresh water of rivers, etc. Therefore, the volume of 

bromate ion generated when Ozone of 4 mg/L (the maximum feeding ratio in this system) is 

added, makes a substantial difference between the seawater and fresh water. The volume of 

bromate ion (measured as value of oxidant) when Ozone of 4 mg/L is added into the seawater is 

about 1.6 mg/L in 2 days (see section 8, Toxicity testing of the treated ballast water). In a short 

navigation, however, this concentration of the ballast water discharged may be potentially higher 

under the influence of the water quality or water temperature. For this reason, bromate ion was 

defined as a relevant chemical in the seawater. In the fresh water, on the other hand, the volume 

generated is on the level of ppb and the influence on the environment may be actually ignored 

and bromate ion is not defined as a relevant chemical. 

2.4 Physical and chemical properties of Active Substance and relevant chemical 

Physical and chemical properties of Ozone and bromate ion and ballast water after being treated 

with this system are shown in Table 5. 
MEPC 55/2 

ANNEX 

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Table 5. Physical and Chemical Properties of Ozone, Bromate ion and Ballast Water 

Physical property Ozone Bromate ion 

(Potassium bromate)

Ballast water 

CAS number 10028-15-6 7789-38-0 ―

Molecule weight 48.0 2) 167.0 ―

Liquid concentration 1358g/L

(at -112°C)3)

― ―

Evaporation heat 15.2kJ/moL 3) ― ―

Melting point -193°C 2) ― ―

Boiling point -112°C 2) ― ―

Flammability Non-combustible but promotes burning 

of other substances. No inflammability 

to liquid2). 

― ―

Density (20°C) 2.144g/L(N.T.P)

(at 0°C, 101kPa) 3) ― ―

Vapour pressure 

(20°C; Pa) 

>1 atm4) ― ―

Vapour density 

(air=1) 

1.6 2)

(air=1) 

― ―

Water solubility 0.1g/100mL 

(at 0°C)2)

7.5g/100ml (25°C) ―

pH in solution ― ― Approx. 5~8 

Dissociation 

constant(pKa) 

Definition for liquid; no relation with 

gas. 

8.62 ―

Oxidation reduction 

potential 

2.07V 3、5) ― ―

Corrosivity to 

Material 

Yes Yes No 

Reactivity to 

container material 

Yes ― ―

Auto ignition 

temperature (°C) 

Noncombustible but promotes burning 

of other substances. Various reactions 

may cause a fire or explosion.2)

― ―

Explosive Properties May cause a fire or explosion when 

heated or coming in contact with a 

combustible material (alkene, ether)2)

― ―

Oxidizing properties Yes ― ―

Surface tension 3.84×10-2N/mm 

(at -183°C)3)

― ―

Viscosity 1.57×10-3Pa.s 

(at -183°C)3)

66.6~67.6※ 0.01Pa.s

Thermal stability and 

breakdown product 

Oxygen ― ―

Other physical and 

Chemical property 

Nothing of noteworthy Oxidizing property Nothing of 

noteworthy 

※Value assuming the water coefficient of viscosity at 0°C to be 100 (density, 14.02~34.64wt%)

―:data not required 
MEPC 55/2 

ANNEX 

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2.5 Laws and regulations for Active Substance and relevant chemical 

2.5.1 Laws and regulations for Ozone 

2.5.1.1 Regulations for Ozone concentration dissolved in water 

There exist regulations on Ozone concentration for the water of the swimming pools in Germany, 

the European Union, Italy, etc. In the case of Germany, DIN Specification regulates the residual 

Ozone concentration as lower than 0.5mg/L and also the corresponding residual chlorine 

concentration as a different value. 

2.5.1.2 Standard environmental concentration 

In Japan, Ozone is regulated as a constituent of oxidant or photochemical oxidant. Standard 

value (value permitted in an hour) under the Basic Environment Law and the Air Pollution 

Control Act is 0.06ppm and 0.12ppm respectively. United States environmental standards are 

shown in Table 66), 7), 8).

Table 6. United States Environmental Standards 

State Classification Standard Value 

State of New York Area of small classification 

unit, I, II 

Area of small classification 

unit, III, IV 

0.05ppm/24hr (average) 

0.1ppm/24hr (average) 

State of California Highest harmful 

concentration 

0.15ppm/1hr 

City of Los Angeles First warning 0.5ppm or higher 

2.5.2 Laws and regulations for bromate ion 

WHO determined the recommended value on bromate ion in the Drinking-water Quality 

Guidelines in 1993. The tentative value of the Guidelines was 25 μg/l.10), 11)

In the 1998 revision of the universal drinking water standard in the European Union, the standard 

bromic acid values were determined to be 25 μg/l by 2003 and 10 μg/l by 2008.

2.6 Information on application 

Ozone is used as a disinfector for the city water, hygiene materials, breaching agent of 

agricultural chemicals at the stage of manufacture, compound intermediate of chemical 

compound raw materials, etc.

3 REACTION OF OZONE AND BROMATE ION IN WATER 

Ozone is finally decomposed to oxygen and water by self-decomposition in water. Its half-life 

period in the seawater, for instance, is 5.8 seconds. Organics, inorganics, and other substances 

are contained in the water and Ozone reacts to them. Decomposition of Ozone is mainly caused 

by its reaction to such substances contained in nature. Other decomposition factors include 

temperature and pH. 
MEPC 55/2 

ANNEX 

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Ozone decomposition rate increases in accordance with the increase of temperature and pH. In 

the acidity range, however, the increase of decomposition rate is not high. The rate increases fast 

in the neutral to alkaline range at any temperature. This tendency accelerates with the increase of 

temperature. The pH value of ballast water is generally 5 to 8, in which range the 

self-decomposition of Ozone progresses fast. Therefore, it is hard to consider that the Ozone 

remains and gives any influence on the ecosystem where the ballast water is discharged.12

Ozone is injected to the ballast water to maintain 4mg/L at the maximum in this system. Ozone 

self-decomposition is composed of two categories, which are firstly self-decomposition as 

described above and secondly reaction with organic and inorganic substances. 

In the seawater the latter reaction specifically occurs. This is because bromate ion (BrO3

-

) is 

generated by reacting with bromide ion which contains 60mg/L in the seawater. 3.3mg/L of 

bromate ion is generated when Ozone with 4mg/L at the maximum is injected to the ballast 

water. Half-life of bromate ion is about 12 hours. Discharge ballast water may cause a concern 

to the environment, depending on storage time in the tank after Ozone treatment. 

The materials generated by reacting with organic matters where low level of organic 

concentration in COD such as 0.5-2.0mg/L, average concentration in the normal seawater is very 

low compared with the quantity produced by reacting with bromate ion described above. This is 

the negligible amount. 

Ozone shows in the fresh water a behaviour different from one in the seawater. Since there exists 

little bromite ion in the fresh water, bromate ion is not produced by reacting with Ozone. 

Furthermore, since the ratio of Ozone to be consumed by reacting with organic and inorganic 

matters is low, majority of Ozone decomposed in the fresh water will be consumed by 

self-decomposition. As half-life period of Ozone is 30 minutes in the fresh water, it is considered 

that it does not remain at time of ballast water discharge. 

4 ANALYTICAL METHOD OF ACTIVE SUBSTANCES AND RELEVANT CHEMICAL 

4.1 Analysis of Ozone 

Ozone concentration is measured as a gas or dissolved Ozone. Two analytical methods are used. 

The ultraviolet rays absorption method makes use of the fact that the Ozone has the absorption 

layer in the ultraviolet region. Another method is the iodine titration method. Actual analytical 

methods are referred in “IOA Standard Committee, Brussels, 1987”. No method has been 

specified about the analysis of Ozone in the seawater. This is because about 60 mg/L of bromide 

ion (Br 7 –), contained in the seawater and Ozone supplied into the seawater react fast to each 

other to generate bromate ion (BrO3 –), etc., and analysis of Ozone dissolved in the seawater is 

very difficult. Generally, dissolved Ozone in the seawater is measured as oxidant by the iodine 

titration method. Ozone concentration referred to in this application form was obtained by the 

iodine titration method. Analysis accuracy of this method is 0.1 mg/L. This accuracy is the most 

suitable for the practical use and provides a sufficient level from the viewpoint of the Ozone 

toxicity level. 

4.2 Analysis of bromate ion 

Any specific method has not been established for the analysis of bromate ion concentration in the 

seawater. Usually, it is measured by the ion chromatogram or by the iodine titration method as 

oxidant. Values of bromate ion concentration in this application form were obtained by the 
MEPC 55/2 

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iodine titration method. Measurement accuracy of iodine titration method is 0.15mg/L similar to 

Ozone. 

Analytical methods for Active Substance and relevant chemical are listed in Table 7. 

Table 7. Analytical method for Ozone and Bromate ion 

Substance Analytical Method Analytical 

accuracy 

Reference/Comment 

Ozone (gas) and 

dissolved Ozone 

Ultraviolet rays absorption method 

Iodine titration method (as oxidant) 

few ppm 

±few%FS 

0.01 mg/l 

±1%FS 

IOA Standardization 

Committee, 12)

Bromate ion Ion chromatogram 

Iodine titration method (as oxidant) 

2μg/l 

0.01 mg/l 

±1%FS 

AWWA13) 

IOA Standardization 

Committee, 12)

Ballast Water 

(seawater) 

Ion chromatogram 

Iodine titration method (as oxidant) 

2μg/l 

0.15mg/l 

±1%FS 

AWWA13) 

I 

5 EXPOSURE SCENARIO 

5.1 Exposure scenario to aquatic organisms 

As for the exposure to aquatic organisms, only exposure to bromate ion contained in the ballast 

water discharged after the treatment of seawater takes place. 

5.2 Exposure scenario to human beings 

Ozone and bromate ion may be taken by men through aquatic organisms. 

5.3 Exposure scenario to crew 

Exposure of Ozone to crew may take place by leaking from the Ozone generator, piping, etc. 

5.4 Scenario of influence on hull 

Corrosion of the hull may take place due to the Ozone gas, dissolved Ozone, and bromate ion. 
MEPC 55/2 

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6 INFORMATION RELATED WITH TOXICITY EVALUATION 

6.1 Toxicity to aquatic organisms 

6.1.1 Acute toxicity 

We researched the United States EPA database (ECOTOX) to obtain data on the acute toxicity to 

aquatic organisms. 

Table 8 shows the acute toxicity of the Ozone used as an Active Substance for this system and 

bromate ion, a relevant chemical for the treatment of seawater. Data in Table 8 is extracted from 

ECOTOX, which shows the end points clearly and the lowest values, that stands for strong 

toxicity. These data is based on analysis of oxidant concentration in the water (refer to 

“section 4. Analysis Method for Active Substances and Relevant chemical” for the analysis 

method). 

Acute toxicity of Ozone (LC50) is 8.1μg/L in the fresh water and 50μg/L in the seawater. 

Acute toxicity of bromate ion is 32,000μg/L, which is required by NOEC (as sodium bromate 

ion) against Crassostrea gigas. 

As described above, acute toxicity of Ozone is very strong both in fresh water and seawater. On 

the other hand, the acute toxicity of bromate ion in this system about which influence at the time 

of discharge of ballast water is apprehended, is relatively weak, about 1/1000 of that of Ozone. 

Table 8. Acute aquatic toxicity 

Test water 

Substance 

Organisms Scientific name 

Common name 

Stage n Endpoint Effect Effect 

Measurem

ent 

Trend Duration 

Exp. 

Type 

Conc. as 

Ozone 

(ug/L) 

95%confid

ence Limit 

Database Reference 

Fresh 

water 

Ozone 

Fish Oncorhynchus 

Mykiss 

Rainbow trout 

Donaldson 

trout 

 LC50 Mortality Mortality 96 h 

flowthrough 

9.3 

8.1-10.6 

See 

Refere

nce 

14 

See 

Reference 

17 

Salt water 

Ozone 

Fish Morone 

Saxatili 

Striped bass 

larvae 40 LC50 Mortality Mortality 96 h 

flowthrough 

80 

50-110 

See 

Refere

nce 

14 

See 

Reference 

18 

Salt 

Water 

Sodium 

bromate 

Bivalvia Crassostrea 

Gigas 

Pacific oyster 

 NOEC Developmental Abnormal increase 24 h 

static 

32000 See 

Refere

nce 

15 

See 

Reference 

19 

Salt 

Water 

bromate 

Bivalvia Crassostrea 

Gigas 

Pacific oyster 

 EC50 Developmental Abnormal 24 h 

static 

30000 See 

Refere

nce 

16 

See 

Reference 

20 

6.1.2 Chronic toxicity 

There exists no data on the chronic toxicity of Ozone and bromate ion but both possess acute 

toxicity. 

Ozone has a half-life period of 5.8 seconds in the seawater and is supposed to be depredated 

in 30 minutes in the same way in the fresh water also. Ozone feeding concentration for treating 
MEPC 55/2 

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the ballast water of this system (at the full ballast water capacity) is designed to be 4 mg/L or 

below. Based on the decomposition speed as described above, when the ballast water is 

discharged, the Ozone is believed to decompose to the concentration level of 0.14μg/L (refer to 

paragraph 6.3.7) which may exist in the environmental water. Thus, it is supposed that the 

Ozone has no chronic toxicity. 

Half-life period of bromate ion in the seawater is about 12 hours relatively longer than Ozone. 

Though the acute toxicity is relatively weak, about 1/1000 of that of Ozone, chronic toxicity of 

ballast water discharged is apprehended. Therefore, a chronic toxicity test of the bromate ion 

was conducted on the seawater organisms. Method and results of this test are described in 

“section 8. Toxicity testing of the treated Ballast Water”. 

6.1.3 Endocrine disruptive properties 

No instance has been reported on the endocrine disruptive properties for both Ozone and bromate 

ion (as a result of research in the ECOTOX database). Because of the dissolution speed, it is 

considered that there is no internal disturbance. 

6.1.4 Toxicity of sediment 

Soil absorption factor of bromate ion is estimated as follows from the relation with the 

octanol/water partition coefficient, Pow: 

Koc=0.41×log Pow(-7.18)8)= 2.7×10-8L/kg 

This estimate of Koc: 2.7×10-8L/kg is far below the value of anticipated toxicity to benthic 

organisms and, therefore, there is no anxiety for the toxicity to benthic organisms. 

Decomposition speed of Ozone is higher than that of bromate ion and its absorption into the soil 

is not anticipated and there is no fear of toxicity to benthic organisms.

6.1.5 Biomagnification/bioaccumulation 

Octanol/water partition coefficient log value of bromate ion, logPow, is -7.18 and is estimated to 

be free from fear of concentration to organisms. 

Ozone decomposition speed is far higher than that of bromate ion and the Ozone is promptly 

decomposed to oxygen and water in the water. Therefore, there is no fear that the Ozone may be 

concentrated in organisms. 

6.2 Mammalian toxicity 

6.2.1 Mechanism of toxicity to mammal 

Toxicity of Ozone and bromate ion to mammal is based on its strong oxidizing property. 

Ozone exerts various influences on the mammal such as irritation to eyes, or to pharynx →

trachea →bronchus →bronchiole →cells caused by inhalation. 

Bromate ion also has various effects on the skin and eyes by exposure, and cough, pharynx pain, 

nausea, vomiting, abdominal pain, diarrhoea, or central nervous system caused by taking orally.
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6.2.2 Effects on skin and eyes 

Ozone gives no effects to the skin but causes irritation to eyes when exposed to the Ozone of 

2ppm or more for several minutes22. Bromate ion exerts effects on both the skin and eyes so that 

the skin flares and eyes flare and pain23. 

6.2.3 Acute toxicity 

Acute toxicity of Ozone (4 hours, LD50) to the mouse is 5.9~6.8ppm22). 

Acute toxicity of bromate ion to hamsters is reported to be 280~495mg/kg of LD50 when taken 

orally25.

6.2.4 Chromic toxicity 

When Ozone is sucked for a long time, it gives effects on the lungs of human and mammal even 

if the concentration is extremely low22. 

In tests of bromate ion for rats for 15 weeks, NOAEL:30mg/kg/day is required25.

6.2.5 Carcinogenicity 

No information has not been acknowledged on the carcinogenicity of Ozone25. 

As for the bromate ion, there has been an example of a test of oral dose to mice and rats for 

100 weeks and carcinogenicity to the kidney, etc., have been recognized24.

6.2.6 Mutagenicity 

Most of research reports have denied the mutagenicity of Ozone24. 

Tests have been conducted on salmonella or colon bacillus of bromate ion and shown negative 

results24.

6.2.7 Secondary toxicity and toxicity of secondary chemicals 

As described in section 3, secondary chemicals other than the bromate ion can be actually 

ignored. Therefore, it is considered that toxicity of secondary products other than bromate ion 

may be ignored. 

6.3 Environmental fate and effect under aerobic and anaerobic conditions 

6.3.1 Decomposition process 

Ozone has high self-decomposition. The Ozone molecule itself is basically an unstable substance 

and its decomposition is prompted promoted under high temperature and high pH in the water. It 

is finally decomposed to oxygen and water in the water. When there are organisms, Ozone reacts 

to them to oxidize. By the decomposition reaction of organisms, Ozone is decomposed and 

consumed (see section 3 for details). 
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Bromate ion is decomposed by the action of anaerobic bacteria such as methanogen in anaerobic 

situation.

6.3.4 Potential effects on wildlife and benthic habitats 

As the half-life period of gaseous phase Ozone is as long as several to several tens of hours, its 

effects on organisms exposed to it is apprehended. The half-life period of Ozone is 5.8 seconds 

in the seawater and the Ozone is decomposed in about 30 minutes in the fresh water. Therefore, 

it is considered that the Ozone has no potential effects in the water. 

Effects of bromate ion, a relevant chemical produced in the seawater, is also apprehended. 

However, since its half-life period in the seawater of bromate ion is fairly short as about 12 hours 

and the estimated absorption coefficient is as very low as 2.7×10-8L/kg, there is no potential of 

effects on benthic organisms. It is considered that there is no such effects either as bromate ion 

may be accumulated in high-order organisms through a food chain. 

6.3.5 Potential residues in seafood 

Both the Ozone and bromate ion are not accumulated, it is judged that there will be no potential 

residues in seafood.

6.3.6 Any known interactive effects 

Ozone produces oxygen when decomposed in the water. As a result, it increases the 

concentration of oxygen dissolved in the water and helps to form the environment suitable for the 

aquatic organisms to inhabit. In the closed seawater for aquaculture, Ozone has effect to remove 

ammonia nitrogen discharged from the fish. 

Bromate ion is hard to be reduced in the water under the normal environmental condition but can 

be reduced to bromide ion where ferrous ion27, activated carbon or other carbonaceous 

substances exist28.

6.3.7 Distribution of Ozone in environment components (atmosphere, water, soil, 

sediment, suspended solid or organisms) 

Since the Ozone decomposes quickly, it does not exist in the water or soil. It is produced by 

photochemical reaction, however, and there is extremely small amount of Ozone as a background 

value in the atmosphere. The background value in the atmosphere is about 200ppb at the 

maximum. 

Ozone dissolves in the water basically according to Henry’s law. On the hypothesis that the 

quantity of Ozone gas is 100%, possible dissolved concentration calculated based on Henry’s law 

is 0.14×10-6 (g/L) as dissolved Ozone in the case of fresh water and as BrO3 in the case of 

seawater. That is, the concentration level in the environmental water is under the ppb order far 

below the analysis accuracy of the analysis method. 
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7 EVALUATION BASED ON PBT CRITERIA 

Both the Ozone (Active Substance) and bromate ion (relevant chemical) have naturally acute 

toxicity. The half-life period of Ozone in the water is 5.8 seconds in the seawater and 

about 30 minutes in the fresh water, while that of bromate ion is about 12 hours apparently 

shorter than 60 days. The absorption coefficient, Koc, is as low as 2.7×10-8L/kg and cannot be 

categorized as the persistent. Bioaccumulation for bromate ion with comparatively low 

decomposition rate is as low as –7.18 in logPow. Therefore, both the Ozone and bromic acid do 

not fall under the category of PBT substances. 

Table 9. Risk characterization 

Substance Persistent(y/n) Bioaccumulative 

(y/n) 

Toxic(y/n) Reference/comments 

Ozone no No Yes See Sections 3 and 6. 

Bromate ion no No Yes See Sections 3 and 6. 

8 TOXICITY TESTING OF THE TREATED BALLAST WATER 

As described in “paragraph 6.1.2, Chronic toxicity”, there is no data on the chronic toxicity of 

Ozone and bromate ion. This ballast water treatment system dissolves the Ozone gas with the 

special structure of the disinfection unit and disinfect the aquatic organisms by the acute toxicity 

of Ozone and bromate ion (a relevant chemical) (see section1, Introduction). It is considered that 

there is no potential of chronic toxicity of discharged ballast water since the Ozone is 

decomposed in an extremely short time to the level of 0.14μg/L which is the concentration of 

Ozone where it may exist in the environmental water. It is also considered that bromate ion 

which is a relevant chemical generated by the reaction of Ozone with the seawater has little 

impact because its acute toxicity is even under 0.16 mg/L, 1/200 of NOEC in addition to 

compliance with NOEC:32 mg/L due to the tank holding time and the functions of the discharge 

treatment unit at the time of discharge. However, since there is no data on the chronic toxicity of 

bromate ion, it was determined as a prudent policy to prepare a sample of the discharged ballast 

water in accordance with the actual ballast water treatment and carry out a chronic toxicity test of 

the discharged water for evaluation. 

This system can be enhanced to be installed on board if the flow rate at the slip plates of the 

sterilizing treatment unit as well as the Ozone gas feeding concentration are kept constant and its 

scale can be further upgraded to comply with the land testing requirements provided in the 

Guidelines (G8) by increasing the diameter of the passage of the special pipe and the volume of 

Ozone gas to be supplied. From the result of toxicity in the test described below, toxicity in the 

operation on an actual ship and for the final approval in accordance with the Procedure (G9) will 

be able to be predicted in advance. 

8.1 Test method 

The test method is described in details in the unofficial report. The test was carried out by a 

method that allowed to evaluate the chronic toxicity of 3 organisms as follows: 

 1 Growth prevention test on algae (Skeletonema costatum) by ozone-treated 

seawater; 
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.2 Chronic toxicity test of Ozone-treated seawater with crustacean (Hyale 

barbicorins); and 

.3 Ozone-treated seawater toxicity test at initial stage of biology of fish 

(Oryzias javanicus) .

To secure the reproducibility of test results and reliability of test reports, each step of test 

operations and the final report were based on the OECD GLP standard, “OECD Principles of 

Good Laboratory Practice” (1997, ENV/MC/CHEM(98)17)29. 

8.2 Test result 

The original test water was treated at the Ozone concentration of 4mg/L and stored at a dark 

place at about 4°C and 25°C each for 24 hours. Aquatic organism was exposed to the test water 

diluted to more than 1/10 of the original test water. The estimated bromate ion concentration (as 

the oxidant concentration) in the sample water is 0.16 mg/L or less. 

In the experiments, obvious chronic toxicity was not observed in the 3 types of aquatic organisms 

in the bromate ion concentration under 0.16 mg/L. Therefore, the chronic toxicity NOEC of 

bromate ion generated by this system is estimated to be more than 0.16 mg/L. This value is a 

result with test water of TOC about 1.1 mg/L. This TOC concentration values are low in the 

normal fresh water and sea water. It implies, therefore, that these results were obtained in such 

an environment where the bromate ion is hard to be consumed or decomposed by organic 

substances, that is, an environment where strong toxicity is easily represented. 

9 RISK ASSESSMENT REGARDING ENVIRONMENT 

It is evaluated that there is no risk of Ozone as an Active Substance related with the environment 

both in the fresh water and seawater since Ozone is decomposed in an extremely short time and 

not discharged outside the ship. Therefore, the risk evaluation to the environment hereinafter is 

focused on bromate ion which is a relevant chemical generated when the seawater is treated. 

9.1 Short-term aquatic toxicity 

Acute toxicity of bromate ion in the seawater was the NOEC: 32 mg/L (oxidant analysis value as 

sodium bromate) to Crassostrea gigas in the existing data (see paragraph 6.1, Acute toxicity). 

On the other hand, the bromate ion concentration (as oxidant concentration) at the time of 

discharge from the special type hybrid system is less than 0.16 mg/L in many cases (tank holding 

time = more than 48 navigation hours). 

Therefore, it is considered that the short-term toxicity of ballast water discharged after being 

treated in this system is basically insignificant. Even when the tank holding time, in case 

navigation time is less than 48 hours, it can be evaluated to be safe enough due to the 

concentration lower than the acute toxicity NOEC and the effect of dilution with the surrounding 

sea water. 
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9.2 Long-term aquatic toxicity 

Since concentration of bromate ion (oxidant concentration) at time of discharge is lower than 

0.16mg/L, there exists little anxiety of long term effects. 

However, a prediction computation by using model of MAM-PEC Version 1.630 was performed 

to ensure the above. Rotterdam Port in the Netherlands was hypothetically selected. 

Calculated concentration of bromate ion contains the following 4 cases: (1) 0.16mg/L 

concentration designed for this system at time of ballast water discharge, (2) 1.6 mg/L without 

decomposition treatment at the discharge treatment unit, (3) 3.44mg/L, average concentration by 

production after Ozone injection (prior to storage in the ballast water tank) and (4) 4.56mg/L, the 

maximum concentration after Ozone injection (prior to storage in the ballast water tank). 

This prediction computation showed that average concentration covering the whole part area 

would be 0.000722mg/L, compounded with the effect of dilution, if 0.16mg/L designed 

concentration of discharged bromate ion for Special Pipe hybrid system is applied. This 

predicted concentration is equivalent to 1/575 of 0.16mg/L concentration where no chronic 

toxicity arises. Average concentration for 1.6mg/L without decomposition treatment at the 

discharge treatment unit is predicted as 1/57 of 0.16mg/L 10 years later. Safety related to long 

term effect will be sufficiently secured without decomposition treatment at the discharge 

treatment unit. 

Therefore, bromate ion to be discharged from this system will not cases any effects on aquatic 

organisms from stand point of long term and short term view. 

10 EFFECTS ON HUMAN HEALTH 

A scenario of influence on men (excluding the crew) through the marine organisms (ecosystem) 

is potentially considered. However, since there is no effect on the environment, concentration in 

marine organisms will not be caused. Thus, there is no risk of effects. 

11 EFFECTS ON SAFETY OF LABOUR (CREW) 

For this system, leaking Ozone densitometers are provided around the Ozone generator and close 

to the transfer route to monitor the leaking Ozone continuously. If leaking Ozone is detected, 

visible and audible alarms are raised at the bridge and the location of the system to stop operation 

of the generator and urge the crew to evacuate. Therefore, there is no possibility of exposure to 

the crew in the normal operation of the Ozone, an Active Substance of this system. 

Possibilities of exposure to the crew due to discharge of Ozone gas caused by casualties, should 

be examined in advance. Generally assumed casualties onboard are confined to fire and 

flooding. If a fire breaks out in the engine room, this system in the engine room can be stopped 

emergently from the outside of the engine room like the fuel pump and can stop the generation of 

Ozone which may grow the fire. If the engine room is flooded and this system is soaked in water 

during operation, there is no possibility of secondary accidents. Only electrical parts are 

short-circuited and stop. Details are described in the unofficial version. 
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12 EFFECTS ON HULL 

When this system is installed on board a ship, effects of Ozone causing corrosion should be first 

considered among effects on the hull. As Ozone has strong oxidizing property, materials should 

be selected taking consideration to the corrosion resistance. 

In accordance with the result of electrochemical analysis and corrosion tests by using the 

designed Ozone concentration of this system, the area required for selection of the materials were 

identified. 

If the Ozone concentration (oxidant concentration) in the seawater is 0.3 mg/L, which is a value 

immediately after the designed treatment (immediately after Ozone is supplied to the disinfection 

treatment unit), corrosive influence on bare steel plates or galvanized steel plates is not so 

different from that in the seawater containing no Ozone and the corrosive influence of Ozone can 

be ignored. 

Since the Ozone dissolution speed is high, the concentration decreases to under 0.3 mg/L within 

the piping to the deaerating tank. Therefore, no corrosion measures are required in the piping 

after the deaerating tank and in the ballast tank. However, the piping from the Ozone inlet to the 

pump and the deaerating tank is continuously exposed to Ozone. Therefore these parts should be 

made of Ozone resistant materials such as stainless steel for the safety. 

Corrosion-proofing effect can be maintained with epoxy coating for several hours but this effect 

decreases rapidly when exposed longer continuously. Therefore, use of epoxy coating should be 

avoided in piping exposed to Ozone continuously for a long time. 

As described above, in a ship where this system is installed, materials of equipment or piping are 

selected considering the corrosive influence of Ozone and therefore the hull is not subjected to 

such influence of Ozone. In this context, oxidizing property of bromate ion is weak and can be 

avoided by the measures against the corrosive effects of Ozone. 

The range in this system requiring the corrosion measures of Ozone is only the area provided 

additionally for installing this system. It was found out that the piping after the deaerating tank 

and the ballast tank can be handled in the same manner as with the traditional seawater ballast. 
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Reference 

1 Hiroharu KATO, Fifth International Symposium on Cavitation (cav2003), Osaka, Japan, 

November 1-4, 2003. 

2 ISCS#/0068 (ILO : International Labour Organization, etc.). 

3 Ozone Ullmann’s Encyclopaedia of Industrial Chemistry, Six Edition, Section 2, Physical 

Properties P.39-P.40, June-2001. 

4 ISCS#/0068 (NIOH : National Institute for Occupational Safety and Health). 

5 Atlas Of Electrochemical Equilibria, Chapter IV, Section 1.1, P.99, James A. Franklin, 

1966. 

6 Recommendation of Occupational Exposure Limits (2004-2005), The Japan Society for 

 Occupational Health, April 13, 2004, Journal of Occupational Health, 2004. 

7 ACGH TLV 1993-1994. 

8 Safety Data Sheet, issue 8b, April 2004. 

9 Guidelines for Safe Recreational-water Environments Vol.2: Swimming Pools, Spas and 

Similar Recreational-water Environments Final Draft for Consultation, August 2004, 

Chapter 4, Chemical Hazards Ch.4-1 (Deutshe Norm: Aufbereitung und Desinfektion von 

Schwimm-und Badebeckenwasser, DIN19643 (April 1984)). 

10 WHO Guidelines for Drinking-water Quality, 2nd edition, Vol.2: Health Criteria and 

Other Supporting Information, Geneva, Switzerland, 1996. 

11 WHO Guidelines for Drinking-water Quality, 2nd edition, Vol.1: Recommendations, 

Geneva, Switzerland, 1996. 

12 IOA Standardisation Committee, 004/87(F), 005/89(F), 006/89(F), 007/89(F), 008/89(F). 

13 AWWA DBPs/Alternative Disinfectants, Bromate Ion. 

14 EPA「ECOTOX」Database, Ozone, CAS No. 10028-15-6. 

15 EPA「ECOTOX」Database, Sodium bromate, CAS No. 7789-38-0. 

16 EPA「ECOTOX」Database, Sodium bromate, CAS No. 7789-38-0. 

17 Wedemeyer, G.A., N.C. Nelson, and W.T. Yasutake. 1979. Physiological and 

Biochemical Aspects of Ozone Toxicity to Rainbow Trout (Salmo gairdneri). 

J.Fish.Res.Board Can. 36(6):605-614. 

18 Hall, L.W.Jr., D.T. Burton, and L.B. Richardson. 1981. Comparison of Ozone and 

Chlorine Toxicity to the Developmental Stages of Striped Bass, Morone saxatilis. 

Can.J.Fish.Aquat.Sci. 38(7):752-757. 
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19 Brixham Environmental Laboratory. 1995. Bromate: Acute Toxicity to the 

Embryo-Larval Stages of the Pacific Oyster, Crassostrea gigas. Study No.AB724/B, 

Brixham Environmental Laboratory, Devon, London: 3 p. 

20 Crecelius, E.A. 1979. Analysis of Oxidants in Ozonized Seawater and Some Biological 

Reactions. J.Fish.Res.Board Can. 36(8):1006-1008. 

21 AQUIRE Data Base by EPA. 

22 Chemical Properties Created by CCOHS (Canadian Center for Occupied Health and 

Safety). 

23 NIOSH: National Institute Occupational Safety and Health, RTECS. 

24 WHO, International Programme on Chemical Safety: Environmental Health Criteria 216 

Disinfectants and Disinfectant By-products. 

25 WHO Guidelines for Drinking-water Quality, 2nd edition, Vol.2: Health Criteria and 

other Supporting Information, Geneva, Switzerland, 1996. 

26 International Chemical Safety Cards (WHO/IPCS/ILO). 

27 Siddiqui M.S., Amy G.L., Rice R.G., J.Am. Water Works Assoc., 87, 58-70 (1995). 

28 Siddiqui M.S., Zhai W., Amy G., Mysore C., Water Res., 30 1651-1660(1996). 

29 OECD Principles of Good Laboratory Practice (1997, ENV/MC/CHEM(98)17). 

30 A.Baat, J Boon, B. van Hattum, Delft/Amdterdam, 2002, IVM Report nr. E-02/03 Delft 

Hydroulics Z 3117. 

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