Evaluation of Ballast Water Treatment Technology 

for Control of Nonindigenous Aquatic Organisms 

DECEMBER 2002 

STATE WATER RESOURCES CONTROL BOARD 

CALIFORNIA ENVIRONMENTAL PROTECTION AGENCY 

In consultation with 

The California State Lands Commission 

and 

The California Department of Fish and Game 
i 

Preface 

This report has been prepared in compliance with section 71210 of the 

California Public Resources Code, in consultation with the Department of 

Fish and Game, the State Lands Commission, the United States Coast 

Guard, the regulated industry, and other stakeholders. The report presents 

treatment alternatives currently available, under development, or 

potentially available in the future for managing ballast waters for the 

purpose of eliminating the discharge of nonindigenous species into waters 

of the state. 
ii 

Table of Contents 

PREFACE .....................................................................................................................................................................i 

TABLE OF CONTENTS ........................................................................................................................................... ii 

LIST OF TABLES........................................................................................................................................................iv 

ABBREVIATIONS ........................................................................................................................................................v 

EXECUTIVE SUMMARY .........................................................................................................................................1 

BALLAST WATER UPTAKE/RELEASE PRACTICES.......................................................................................................2 

BALLAST WATER EXCHANGE....................................................................................................................................2 

ONSHORE TREATMENT ..............................................................................................................................................2 

FILTRATION/SEPARATION SYSTEMS ..........................................................................................................................2 

BIOCIDES ...................................................................................................................................................................2 

HEAT TREATMENT.....................................................................................................................................................3 

ULTRAVIOLET RADIATION.........................................................................................................................................3 

ULTRASOUND ............................................................................................................................................................3 

MAGNETIC TREATMENT ............................................................................................................................................3 

OZONE.......................................................................................................................................................................3 

PULSE PLASMA..........................................................................................................................................................4 

DEOXYGENATION ......................................................................................................................................................4 

BALLAST TANK COATING..........................................................................................................................................4 

BWE EFFECTIVENESS EQUIVALENCY .......................................................................................................................4 

RECOMMENDATION ...................................................................................................................................................4 

INTRODUCTION .......................................................................................................................................................6 

BACKGROUND..........................................................................................................................................................7 

THE PROBLEM ...........................................................................................................................................................7 

THE ROOT OF THE PROBLEM......................................................................................................................................9 

REGULATORY ACTIVITIES ................................................................................................................................11 

TREATMENT EVALUATION CONSIDERATIONS ..........................................................................................13

TREATMENT ALTERNATIVES ...........................................................................................................................15 

PRACTICES AND PROCEDURES .................................................................................................................................15 

Ballast Water Uptake/Release Practices............................................................................................................15 

Description...................................................................................................................................................................... 15 

Safety .............................................................................................................................................................................. 16 

Biological Effectiveness ................................................................................................................................................. 17 

Environmental Acceptability .......................................................................................................................................... 17 

Status of Technology ...................................................................................................................................................... 17 

Cost................................................................................................................................................................................. 17 

Ballast Water Exchange (BWE) .........................................................................................................................17 

Description...................................................................................................................................................................... 17 

Safety .............................................................................................................................................................................. 19 

Biological Effectiveness ................................................................................................................................................. 20 

Environmental Acceptability .......................................................................................................................................... 23 

Status of Technology ...................................................................................................................................................... 23 

Cost................................................................................................................................................................................. 23 

ONSHORE TREATMENT ALTERNATIVES ...................................................................................................................23 

Onshore Ballast Water Treatment, Treatment Ship, or Mobile Transport Facility ...........................................23 

Description...................................................................................................................................................................... 23 

Safety .............................................................................................................................................................................. 24 
iii 

Biological Effectiveness ................................................................................................................................................. 24 

Environmental Acceptability .......................................................................................................................................... 25 

Status of Technology ...................................................................................................................................................... 25 

Cost................................................................................................................................................................................. 25 

ON BOARD TREATMENT TECHNOLOGIES.................................................................................................................29 

Filtration and Hydrocyclonic Separation Systems.............................................................................................29 

Description...................................................................................................................................................................... 29 

Safety .............................................................................................................................................................................. 30 

Biological Effectiveness ................................................................................................................................................. 30 

Environmental Acceptability .......................................................................................................................................... 30 

Status of Technology ...................................................................................................................................................... 30 

Cost................................................................................................................................................................................. 31 

Biocides..............................................................................................................................................................32 

Description...................................................................................................................................................................... 32 

Safety .............................................................................................................................................................................. 32 

Biological Effectiveness ................................................................................................................................................. 33 

Environmental Acceptability .......................................................................................................................................... 33 

Status of Technology ...................................................................................................................................................... 34 

Cost................................................................................................................................................................................. 34 

Heat Treatment ..................................................................................................................................................34 

Description...................................................................................................................................................................... 34 

Safety .............................................................................................................................................................................. 35 

Biological Effectiveness ................................................................................................................................................. 35 

Status of Technology ...................................................................................................................................................... 36 

Environmental Acceptability .......................................................................................................................................... 36 

Cost................................................................................................................................................................................. 37 

Ultraviolet Light.................................................................................................................................................37 

Description...................................................................................................................................................................... 37 

Safety .............................................................................................................................................................................. 38 

Biological Effectiveness ................................................................................................................................................. 38 

Environmental Acceptability .......................................................................................................................................... 40 

Status of Technology ...................................................................................................................................................... 40 

Cost................................................................................................................................................................................. 41 

Ultrasound .........................................................................................................................................................41 

Description...................................................................................................................................................................... 41 

Safety .............................................................................................................................................................................. 42 

Biological Effectiveness ................................................................................................................................................. 42 

Environmental Acceptability .......................................................................................................................................... 42 

Status of Technology ...................................................................................................................................................... 42 

Cost................................................................................................................................................................................. 44 

Magnetic Treatment ...........................................................................................................................................44 

Description...................................................................................................................................................................... 44 

Safety .............................................................................................................................................................................. 44 

Biological Effectiveness ................................................................................................................................................. 45 

Environmental Acceptability .......................................................................................................................................... 45 

Status of Technology ...................................................................................................................................................... 45 

Cost................................................................................................................................................................................. 45 

Ozone .................................................................................................................................................................46 

Description...................................................................................................................................................................... 46 

Safety .............................................................................................................................................................................. 46 

Biological Effectiveness ................................................................................................................................................. 47 

Environmental Acceptability .......................................................................................................................................... 47 

Status of Technology ...................................................................................................................................................... 47 

Cost................................................................................................................................................................................. 48 

Pulse Plasma......................................................................................................................................................48 

Description...................................................................................................................................................................... 48 

Safety .............................................................................................................................................................................. 49 

Biological Effectiveness ................................................................................................................................................. 49 

Environmental Acceptability .......................................................................................................................................... 49 

Status of Technology ...................................................................................................................................................... 49 

Cost................................................................................................................................................................................. 49 
iv 

OTHER TREATMENT OPTIONS..................................................................................................................................50 

Deoxygenation ...................................................................................................................................................50 

Description...................................................................................................................................................................... 50 

Ballast Tank Coating .........................................................................................................................................50 

Description...................................................................................................................................................................... 50 

FINDINGS AND EVALUATION OF BALLAST WATER TREATMENT ALTERNATIVES .......................52 

SAFETY....................................................................................................................................................................55 

BIOLOGICAL EFFECTIVENESS ..................................................................................................................................55 

ENVIRONMENTAL ACCEPTABILITY..........................................................................................................................57 

COST........................................................................................................................................................................58 

CONCLUSIONS........................................................................................................................................................60 

RECOMMENDATION.............................................................................................................................................63 

REFERENCES ..........................................................................................................................................................66 

List of Tables 

TABLE 1: REPORTED ESTIMATES OF BALLAST WATER EXCHANGE EFFECTIVENESS ..................... 22 

TABLE 2: PORT SPECIFICATIONS AND ESTIMATED COSTS TO INSTALL SHORE-BASED 

TREATMENT FACILITIES IN CALIFORNIA ........................................................................ 27 

TABLE 3: TRANSFER COST TO TREAT BALLAST WATER IN SHORE-BASED OR MOBILE 

SYSTEMS FACILITIES...................................................................................................... 28 

TABLE 4: PERCENT REDUCTION OF DIFFERENT BACTERIA AND VIRUSES IRRADIATED 

WITH 20-MW/CM2

/SEC DOSE ......................................................................................... 39 

TABLE 5: BIOLOGICAL EFFECTIVENESS ON VARIOUS ORGANISMS USING A 100 GPM 

ULTRASOUND UNIT FOR PROCESSING UNFILTERED WATER ............................................ 43 

TABLE 6: PRELIMINARY BALLAST WATER TREATMENT TECHNOLOGY 

EVALUATION................................................................................................................. 54 

TABLE 7: CAPITAL AND TREATMENT COST ESTIMATES TO TREAT BALLAST WATER.................... 59 

TABLE 8: INITIAL ASSESSMENT OF THE STATUS OF THE TREATMENT OPTIONS............................... 61 
v 

Abbreviations 

SWRCB State Water Resources Control Board 

IMO International Maritime Organization 

O&M Operating and Maintenance 

BWE Ballast Water Exchange 

ERE Empty and Refill Exchange 

FTE Flow Through Exchange 

UV Ultravoilet 

BWT Ballast Water Treatment 

U.S. United States 

DFG California Department of Fish And Game 

SLC California State Lands Commission 

USCG U.S. Coast Guard 

NRC National Research Council 

ESTUARY San Francisco Bay Estuary 

NOBOB No Ballast On Board 

NISA National Invasive Species Act 

DWT Dead Weight Tonnage 

MGD Million Gallons Per Day 

PPM Parts Per Million 

NM Nanometers 

LP Low Pressure 

MP Medium Pressure 

GPM Gallons Per Minute 

HPUP High Power Ultrasonic Process 

OSHA Occupational Safety and Health Administration 

MT Metric Ton 
1 

Executive Summary 

California Public Resources Code section 71210 requires that the State 

Water Resources Control Board (SWRCB) evaluate ballast water 

treatment alternatives for the purpose of eliminating the discharge of 

nonindigenous species into the waters of the state. The law also requires 

that SWRCB submit to the Legislature, on or before December 31, 2002, a 

report that includes (1) a recommendation of the best available and 

economically feasible technologies that reflect the greatest degree of 

reduction in the release of nonindigenous aquatic species, (2) the 

effectiveness of these technologies, and (3) the costs of implementing 

them. 

This report evaluates thirteen possible alternative options for treatment of 

ballast water, including two established practices that are presently 

recommended under the International Maritime Organization (IMO) 

guidelines and are mandated under California Public Resources Code 

section 71204. The evaluation focused principally on five considerations: 

safety, biological effectiveness, environmental acceptability, status of 

technology, and cost. 

There are a number of treatment technologies that have been identified as 

possible solutions to address the ballast water discharge problem. At 

present, there is not enough conclusive information to recommend a single 

treatment option or a combination of treatment options for certification in 

California. The initial assessment of the status of the various treatment 

options using the information collected indicates that most of the 

technologies are in either developing or conceptual stage. Many of the 

treatment technologies discussed in this report may be available in the 

future. At present, some have been tested under laboratory conditions and 

only a few have undergone full scale testing aboard ship. There are many 

fundamental scientific, engineering, and operational questions that need to 

be answered for each of the proposed onboard treatment systems before 

certification for use in California is possible. 
2 

Ballast Water Uptake/Release Practices 

California Public Resources Code section 71204(b) also requires the 

vessels to take a series of actions to minimize the uptake and release of 

nonindigenous species. For example, vessels must avoid discharge or 

uptake of ballast water in areas within marine sanctuaries, minimize or 

avoid uptake of ballast water in areas known to have infestations or 

populations of harmful organisms and pathogens, and discharge only the 

minimal amount of ballast water essential for vessel operations while in 

the waters of the state. These requirements are established practices that 

are recommended by IMO. They are considered readily available as long 

as ship safety is not compromised. However, the procedures should only 

serve as primary avoidance strategies and should be used in combination 

with other treatment methods or technologies. 

Ballast Water Exchange 

Ballast Water Exchange (BWE) is one of the ballast water management 

practices required under California Public Resources Code 

section 71204(a). Empty and Refill Exchange (ERE) and Flow Through 

Exchange (FTE) procedures are considered established BWE practices and 

are recommended under IMO guidelines. However, there are many 

uncertainties associated with BWE procedures regarding safety, biological 

effectiveness, and locations where exchange might be carried out. 

Onshore Treatment 

Despite concerns regarding the cost of establishing and operating onshore 

treatment facilities, this alternative remains an attractive option. At this 

point, onshore treatment may be an option for ports that have a limited 

number of dedicated ship visits, or for older vessels that discharge smaller 

volumes of ballast water or vessels that are unable to retrofit because they 

are either nearing the end of their service life or it would be too costly to 

retrofit. The viability of this alternative should increase as future 

generations of ships and port systems develop. 

Filtration/Separation Systems 

Filtration and cyclonic separation systems are considered safe. Both 

systems have been and continue to be tested under different scenarios. 

The consensus is that either system must be combined with a secondary 

technology to appropriately control or eliminate nonindigenous species 

from ballast water. 

Biocides 

Investigation of the use of biocides on board ship for the treatment of 

ballast water is just beginning. Preliminary observations seem to indicate 

a high level of biological effectiveness. However, questions regarding the 
3 

discharge of residual chemical compounds have not been adequately 

addressed thus far. 

Heat Treatment 

Much of the technology necessary to implement heat treatment is currently 

available. Concerns regarding thermal and air pollution can be avoided 

through engineering modifications and design. Cost will vary based on 

the retrofitting, ship type, and amount of ballast water to be treated. 

Preliminary studies have been carried out on its effectiveness, yet further 

evaluation is needed. 

Ultraviolet Radiation 

The effectiveness of ultraviolet (UV) radiation is influenced by the amount 

of suspended organic and inorganic particles in the water to be treated. 

The system should be coupled with some type of filtration so that larger 

organisms and particles are removed before the UV treatment is 

administered. The system is currently under evaluation to better define the 

exposure time and intensity of UV application to achieve adequate 

inactivation or elimination of ballast water entrained organisms, as well as 

to address engineering questions regarding the installation and operation 

on board different types of ships. Studies also suggest that re-growth 

occurs after retention in the ballast system. 

Ultrasound 

Ultrasound achieves a high level of biological effectiveness on Zebra 

mussel veliger, nematodes, bacteria, and viruses, but the technology has 

not been tested on a large flow system capable of treating large volumes of 

ballast water on board ship. 

Magnetic Treatment 

Magnetic treatment effects will vary according to type and size of the 

organisms. Studies with fuel cleaning systems have indicated that high 

levels of biological effectiveness have been achieved against microbial 

organisms and fungi. It is feasible to design and manufacture a magnetic 

system, but such treatment systems have not yet been developed or tested 

for ballast water treatment. 

Ozone 

Ozone treatment is another type of oxidizing biocide capable of causing 

direct oxidation and destruction of the cell walls of organisms. 

Preliminary studies indicate that the treatment is highly effective, but 

further investigation is needed. 
4 

Pulse Plasma 

Pulse Plasma studies indicate that the treatment is effective against the 

Zebra mussel, algae, and bacterial growth. It is presently being further 

tested with Zebra mussels for land-based applications. No system has 

been developed for shipboard testing. 

Deoxygenation 

Deoxygenation treatment could be effective at killing larval, juvenile, and 

adult oxygen-consuming organisms but may be less effective on taxa 

adapted to low oxygen environments or with resistant stages such as cysts. 

Ballast Tank Coating 

Anti-fouling coat application inside ballast tanks would probably prevent 

benthic organisms from attaching to the tank’s surfaces but would not 

affect organisms within the water column. 

BWE Effectiveness Equivalency 

California Public Resources Code section 71204(a)(3) requires that any 

alternative method of ballast water management be at least as effective as 

BWE in removing or killing nonindigenous organisms. BWE should not 

be used to determine the biological effectiveness of ballast water treatment 

(BWT) technologies because the effectiveness of BWE has not been 

established and varies widely. In addition, while all of the proposed 

treatment technologies are designed to kill or remove organisms, BWE 

methods result in an unpredictable combination of killing, removing, and 

adding organisms. The effectiveness of BWE is dependent upon the 

volume of ballast water exchanged and the likelihood that the organisms 

that have been exchanged and then discharged will not be able to tolerate 

coastal, estuarine and freshwater environments. It is therefore difficult to 

meaningfully compare BWE organism replacement results with BWT 

killing results. 

Recommendation 

There is not enough conclusive information at this time to recommend a 

single treatment option or a combination of treatment options for 

certification in California. Most of the treatment technologies discussed in 

this report are under development or potentially available in the future. 

Some have been tested under laboratory conditions and only a few have 

undergone full-scale testing aboard ship. There are many fundamental 

scientific and engineering questions that need to be answered. Further 

research and onboard testing are necessary. 

Problems caused by ship ballasting are an international issue and should 

be addressed by appropriate federal agencies in coordination with the state 
5 

and the shipping industry. The State Lands Commission (SLC), which 

regulates shipping operations in state’s waters, is currently the lead state 

agency working with the U.S. Coast Guard (USCG) on ballast water 

management issues. USCG and SLC are implementing a joint detailed 

procedure to evaluate experimental or prototype ballast water treatment 

systems with demonstrated potential for effective destruction of 

nonindigenous aquatic organisms. Additional efforts that could be 

included in this joint program are the following: 

• Focused research and engineering studies that would guide the 

development of promising treatment alternatives towards a working 

prototype. The research and development would incorporate the 

specific constraints and requirements of defined classes of vessels. 

This should include land-based testing, where the technologies are 

evaluated in an environmentally safe location, that would facilitate 

objective testing using scientifically designed protocols for 

standardized land-based tests under highly controlled conditions. 

• Shipboard installation and testing that would guide the research and 

development of a prototype system toward application on board ship. 

This should include fitting and refining prototypes through shipboard 

trials over extended periods and under a broad range of operating 

conditions and biological testing to evaluate the effectiveness of the 

system. 

• Tested technologies that are proven effective should subsequently be 

certified as suitable for use and implemented throughout the maritime 

industry. 
6 

Introduction 

Ships arriving at California ports discharge approximately four million 

metric tons (MT) of ballast water annually, releasing thousands of 

nonindigenous aquatic organisms into the state’s marine and estuarine 

ecosystems. This type of discharge is one of the primary mechanisms for 

transporting nonindigenous aquatic organisms to California waters. The 

organisms inadvertently discharged with ballast water can potentially 

become established causing substantial environmental and economic 

impacts. The problem has become more acute as international commerce 

increases and ships and port systems become larger. 

In recognition of this threat, the Legislature in 1999 added Division 36 

(section 71200 et seq.) to the California Public Resources Code for 

controlling the introduction of nonindigenous organisms to waters of the 

state. Under this new law, all foreign and domestic vessels carrying 

ballast water into waters of the state after operating outside the 

United States (U.S.) Exclusive Economic Zone are prohibited from 

discharging ballast water unless the operator has carried out ballast water 

exchange (BWE) procedures or any alternative ballast water treatment 

technology that is as good or better than BWE. 

In addition to making ballast water management practices mandatory in 

California, the law also established a coordinated interagency effort, 

requiring an inventory of the locations and geographical range of resident 

nonindigenous species populations, and an evaluation of alternative 

methods for the control of the discharge of nonindigenous aquatic 

organisms. The State Water Resources Control Board (SWRCB) is 

responsible for the evaluation of treatment alternatives, in consultation 

with the California Department of Fish and Game (DFG), the State Lands 

Commission (SLC), the U.S. Coast Guard (USCG), the regulated industry, 

and other stakeholders. The evaluation must be completed and reported to 

the Legislature by December 31, 2002. 
7 

Background 

The Problem 

Over 80 percent of the world’s commodities are moved through maritime 

shipping operations. In this process, ships transfer millions of tons of 

ballast water from one place to another worldwide, inadvertently 

transferring and discharging nonindigenous aquatic organisms into 

receiving waters (Carlton and Geller, 1993; National Research Council 

[NRC], 1996). The introduction of nonindigenous aquatic organisms in 

this manner has created substantial environmental and economic impact 

on ports, estuaries, and other water resources of the state as well as on 

other parts of the world. 

Depending on where ships take on ballast water, virtually all organisms in 

the water column, either swimming or stirred up from bottom sediments, 

can be taken into ships’ ballast tanks. These organisms include 

holoplakton (free-floating), meroplakton (larval stages of bottom dwelling 

organisms), upper water column nekton (active swimming), and demersal 

(near bottom dwelling nekton) organisms. These include a wide variety of 

animals and plants such as mollusks, shrimp, crab, fish larvae, seaweed 

and sea grasses, phytoplankton, zooplankton (including larvae of bottomdwelling organisms), viruses, bacteria, fungi, molds, protozoans, many 

types of parasites, pathogenic organisms, egg, cysts, and larvae of various 

species. The problem is compounded by the fact that many marine 

benthic organisms are also taken into the ballast tanks during the early life 

stages, which are spent suspended in the water column. These organisms 

may include benthic invertebrates such as sea anemones, corals, hydroids, 

oysters, clams, barnacles, sea stars, sea cucumbers, and tunicates. 

At present, there is no way to determine when and/or whether an 

introduced species will survive to become established. Fortunately, most 

organisms discharged in ballast water do not survive to establish viable 

populations (Cohen and Carlton, 1995). However, the few that survive 

can become established, disrupting the natural ecological balance of the 
8 

receiving ecosystem by outcompeting native species for resources and 

upsetting predator-prey relationships. Nowhere is this more evident than 

in the San Francisco Bay Estuary (Estuary) where more than 

230 nonindigenous species have become established. These organisms 

have become dominant within specific communities, often accounting for 

up to 99 percent of biomass in the Estuary (Cohen and Carlton, 1998). 

The overall rate of invasion, based on an invasion record spanning 

145 years, indicates that roughly half of all invasions recorded have 

occurred in the last 40 years. Recent studies indicate that the rate of 

invasion is increasing exponentially with more invasions being reported 

along the Pacific coast than along the Atlantic or Gulf coasts (Ruiz et al., 

2000). The rate of new introductions will probably continue to increase as 

ships and port systems become larger in response to growing global 

commerce and as more investigators find newly introduced organisms. 

For example, in the Estuary, the Asian Clam (Potamocorbula amurensis) 

became established and, within a year, became the most abundant clam in 

the northern part of the Estuary. These organisms are capable of filtering 

the entire water column as much as twice a day, significantly disrupting 

the phytoplankton and native zooplankton food web in the Estuary 

(Cohen, 1998). The Chinese mitten crab (Eriocheir sinensis), a native to 

coastal rivers and estuaries of Korea and China, was introduced to the 

Estuary in the late 1980s or early 1990s. The most likely mode of 

introduction to the Estuary is believed to have occurred through the 

accidental release of ballast water and the deliberate release for the 

purpose of establishing a fishery (Cohen and Carlton, 1997). Commercial 

shrimp trawlers in South San Francisco Bay first collected the organism in 

1992 and in San Pablo Bay in 1994. By 1996, it had spread throughout 

the lower tributaries of South San Francisco Bay, San Pablo Bay, 

Suisun Bay, the Suisun Marsh, and the Sacramento-San Joaquin Delta. 

Documented impacts as a result of the population explosion of these 

nonindigenous species include disruption of commercial and recreational 

fisheries and disruption of fish salvage operations at the federal and state 

pumping plants located in the south delta. 

Since the late 1980s, the European Zebra mussel has caused extensive 

economical and ecological problems in the Great Lakes. Damage has 

been caused by blockage of water intake pipes in power plants as well as 

intake and delivery pipes used in municipal and industrial systems. They 

have also caused navigational hazards by attaching in large numbers to 

ship and boat hulls, marine structures, and navigational buoys. The 

population explosion has disrupted the food web and threatened the 

biodiversity of the Great Lakes. The average cost of damage over ten 

years has been estimated in the billions of dollars. The problem has now 

spread to other parts of North America and Canada. 
9 

Concentrations of bacteria, virus-like particles, and the bacteria Vibrio 

cholera which causes human epidemic cholera, have been identified in the 

ballast water of vessels arriving from foreign ports into Chesapeake Bay 

(Ruiz et al., 2000). In 1991, fish and oysters in Mobile Bay, Alabama, 

were found contaminated with the epidemic strain of cholera that was 

discharged with ballast water. The U.S. Food and Drug Administration 

discovered that five out of 19 ships arriving from South America were 

carrying the epidemic strain (Federal Register, 1998). 

Other ports such as Prince William Sound in Alaska, Puget Sound in 

Washington, Coos Bay in Oregon, Chesapeake Bay, the Hudson River 

Basin, Long Island Sound, the Florida Everglades, near-coastal portions of 

the Gulf of Mexico, Elkhorn Slough National Estuary Research Reserve, 

and the harbors of Los Angeles and San Diego have had significant 

invasions of nonindigenous organisms. In other parts of the world (from 

Australia and New Zealand to the Persian Gulf) there has been 

documentation of increased levels of aquatic invasions in coastal and 

estuarine waters. The Atlantic comb jelly introduced into the Black and 

Azov seas in the early 1980s consumed much of the seas’ crustacean 

zooplankton, contributing to the decline of the fishery industry of six 

nations (Cohen, 1996). 

Sediment accumulated in ballast tanks when discharged (usually a mix of 

harbor, port, or estuarine mud and small debris from other destinations) is 

also an important mode by which nonindigenous organisms are introduced 

(Cawthron Report No. 417, 1997). Introductions of toxic dinoflagellates 

from the discharge of sediments in Australia, New Zealand, and Japan 

have produced red tides killing fish and invertebrates. Some have 

produced human neurotoxins that accumulate in mussels and clams, 

causing toxic effects in humans who consume these organisms. 

Although the introductions of many of these aquatic organisms can be 

attributed to ship hulls, anchors, and other vessel surfaces, the discharge of 

ballast water and sediment is currently considered the most important 

vectors of nonindigenous organisms around the world. 

The Root of the Problem 

Broadly defined, ballast is any solid or liquid placed in a ship to increase 

the depth of submergence of the vessel in the water to change the trim, to 

regulate stability, or to maintain stress loads within acceptable limits 

(NRC, 1996). Proper ballasting reduces stresses on the hull, provides 

stability, aids propulsion and maneuverability, and compensates for weight 

lost from loading and unloading cargo and from fuel and water 

consumption. The use of ballast water varies among vessel types, the type 

of trade, different ports, and sea conditions. Ships carrying little or no 

cargo tend to ride high in the water. This makes them vulnerable to being 
10 

knocked about by heavy weather conditions, increasing the potential for 

slamming the bow or stern over high waves or raising the propeller out of 

the water. To remedy this, ballast water is taken on in order to lower the 

ship to a more safe and efficient position in the water. A ship partially 

loaded with cargo will carry some ballast water (“with ballast”), and a 

fully loaded ship will report carrying no ballast (“NOBOB” or no ballast 

on board). NOBOB vessels raise a special concern because, while 

reporting no ballast on board, such ships still retain residual volumes of 

unpumpable water and sediment in the ballast tanks containing a wide 

assortment of aquatic organisms. The organisms in the residual volume of 

ballast water are re-suspended when new ballast water is taken in and 

subsequently discharged when the vessel takes on new cargo 

(Doblin et al., 2001). The end result of these ship-safety procedures is that 

a vessel accumulates organisms from multiple ballasting at several sites. 

Therefore, under all conditions, ballast water containing potentially 

harmful invasive aquatic organisms will be discharged into ports receiving 

waters and surrounding coastal regions. 

The accumulated organisms are not strictly estuarine, coastal, or 

mid-oceanic in origin, or strictly represent organisms from the last port of 

call. The ballast water may be many hours or months old and may contain 

living organisms for an extended period of time. In addition, the sediment 

accumulated in the ballast tanks may also reflect an even longer history of 

ballasting and may include accumulation of life forms from many ports 

around the world. In these cases, a highly diverse permanently 

submerged, multi-origin assemblages of benthic organisms may become 

established in the sediment layers of ballast tanks. These benthic 

organisms may release planktonic larvae into the overlying ballast water, 

and resistant stages of cysts and spores become re-suspended or induced to 

excyst or hatch and subsequently become discharged into receiving 

waters. 

It has been generally assumed that only major ports are at risk from 

introduction of organisms. However, the movement and discharge 

patterns of ballast water are such that no coastal site, whether it receives 

direct shipping or not, is immune to ballast introduced organisms. 
11 

Regulatory Activities 

Many governments, international maritime environmental entities, and 

public health organizations have recognized the environmental, economic, 

and health threat caused by the translocation and release of ballast water. 

This has prompted the adoption of laws throughout the world requiring 

vessel operators to manage their ballast water in ways that will prevent the 

transfer of nonindigenous species through this media. Most national and 

regional regulations have been modeled after the guidelines established by 

International Maritime Organization (IMO) [1997-resolution A.868 (20), 

Guidelines from the Control and Management of Ships’ Ballast Water to 

Minimize the Transfer of Harmful Aquatic Organisms and Pathogens]. 

These guidelines are not binding unless specific nations adopt them for 

their own use. Presently, IMO guidelines remain largely voluntary. The 

guidelines include several operational procedures related to loading and 

discharging ballast water and sediment and recommend that ships carry 

out BWE of coastal ballast water in deep ocean water (at least 200 nautical 

miles from shore). The intent of this procedure is that any water of coastal 

origin (fresh, estuarine, or coastal marine) is exchanged with mid-ocean 

water during the ship’s voyage to the port of destination. At arrival, midocean water is subsequently discharged into receiving waters. The 

assumption is that mid-ocean organisms will not survive when discharged 

into near coastal or fresh water. 

The discharge of ballast water and the uncertainties associated with the 

biological efficacy of treatment options presently available to the shipping 

industry have caused regulatory jurisdictions to consider regulatory 

actions. This regulatory response has resulted in an increase of unilateral 
12 

national and regional actions to control the spread of nonindigenous 

aquatic organisms into local waters. At present, there are 14 countries 

with regulations in place including Australia, Argentina, Brazil, Canada, 

Chile, Ecuador, Israel, United States (U.S.), New Zealand, and some 

European Union countries. Several states in the U.S. have developed their 

own regulation, including California, the Great Lakes states, Oregon, and 

Washington. In addition, there are several ports around the world that 

have established ballast water management laws within their jurisdictions, 

including Buenos Aires in Argentina, Scapa Flow in Scotland, and 

Vancouver in Canada (GloBallast, 2001). Many of these regulatory 

responses have remained consistent with the current IMO guidelines, 

while others have imposed new and different requirements. Such 

developments have caused major concerns to the shipping industry which 

must operate across many of these jurisdictions and are severely affected 

when rules change from port to port. 

The problem caused by the discharge of ballast water worldwide, the 

regulatory response, and the lack of effective treatment alternatives to 

address the problem have created a heightened demand for more effective, 

practical, flexible, and cost effective ballast water treatment (BWT) 

alternatives over the use of BWE methodologies. BWT would offer a 

number of advantages to ship owners, including the flexibility to readily 

visit ports that have adopted ballast water management laws, and the 

resale enhancement of ships that already have BWT installed (Royal 

Haskonin Global Market Analysis Report, 2001). At present, no BWT 

technologies are available for application. Most technologies are just 

emerging or presently under development or testing. 

No single BWT technology currently being developed or tested can meet 

all the needs of the shipping industry. A range of certified technologies is 

needed so that one or a combination of them could be used to manage 

ballast water effectively, comply with all regulatory requirements, and be 

compatible with different ship designs and types of voyages.
13 

Treatment Evaluation Considerations 

This evaluation focuses on the following considerations: safety, biological 

effectiveness, environmental acceptability, status of technology, and cost. 

These considerations address the mandates of the existing law and the 

factors that could potentially affect the quality of the state’s waters. 

The actual implementation of any ballast water treatment technology will 

be limited by feasibility of application, retrofitting potential, compatibility 

with vessels of different size, and types, and the loading and discharge 

capacities of ballast pumping and piping systems. These design and 

engineering issues should be addressed as part of a state certification and 

verification program that would subject candidate treatment options 

through a rigorous scientific and engineering evaluation process. 

All the technologies and practices discussed in this report are assessed 

from different perspectives based on available information gathered for 

each treatment alternative. For some treatment options, there is not 

enough information to form an opinion. The five evaluation 

considerations addressed are defined as follows: 

1. Safety — Safety considerations of ship and crew while implementing 

any ballast water treatment controls. 

2. Biological effectiveness — The capacity of a treatment option to 

adequately reduce or eradicate the number of viable organisms in 

ballast water. 

3. Environmental acceptability — The capability of dealing with 

ballast residues of organisms or the production of chemical treatment 

residues in an environmentally safe manner. 
14 

4. Status of Technology - The current development status of a specific 

treatment technology, performance test results, and its practical current 

and future application potential. 

5. Cost – Capital and operating cost considerations. 
15 

Treatment Alternatives 

The treatment options described and discussed in this section are classified 

into three different categories as follows: 

• Established management practices and procedures that do not require 

special equipment or the design and installation of unique systems to 

accomplish treatment. 

• Onshore treatment systems that would be designed to accomplish 

treatment either on land or on some type of mobile system. 

• On board treatment alternatives including those options requiring 

installation of some type of system to either control the intake of 

aquatic organisms or eliminate organisms in the ballast tanks. 

Practices and Procedures 

Ballast Water Uptake/Release Practices 

Description

Ballast water uptake/release practices are strategies aimed at reducing the 

number of organisms taken on during ballasting operations or avoiding the 

discharge of ballast water in sensitive coastal areas. These strategies 

include avoiding ballasting in waters that are likely to contain unwanted 

organisms, in areas of sewage discharge, at ports with high sediment 
16 

loads, in certain areas at certain times of the year, or at night when 

planktonic organisms migrate upward in the water column. 

These procedures are currently recommended by IMO and are included in 

the guidelines issued by USCG pursuant to the National Invasive Species 

Act (NISA). They are also required under section 71204 of the California 

Public Resources Code. The management procedures are:

1. Avoid the discharge or uptake of ballast water in areas within or that 

may directly affect marine sanctuaries, marine preserves, marine 

parks, or coral reefs. 

2. Minimize or avoid uptake of ballast water in all of the following areas 

and circumstances: 

• Areas known to have infestations or populations of harmful 

organisms and pathogens 

• Areas near sewage outfalls 

• Areas near dredging operations 

• Areas where tidal flushing is known to be poor or times when a 

tidal stream is known to be more turbid 

• At night when bottom dwelling organisms may rise up in the water 

column 

• Where propellers may stir up the sediment 

Safety

The need for ballast to ensure ship safety during cargo loading and 

unloading imposes practical restrictions on this control option. Ballasting 

operations may need to be carried out in port to maintain ship transverse 

stability, and to maintain both the clearances under cargo loading or cargo 

discharge facilities and under-keel clearance so the vessel remains safely 

afloat. This prevents hull bending and keeps shear forces within safe 

limits to avoid damage that can result from incorrect loading. It also helps 

maintain the ship upright by trimming or heeling the ship and helps 

establish efficient ballast conditions for the voyage ahead. 

Implementation of the uptake/release procedures must take into account 

the ballast requirements for safe ship operations, the locations, the times of 

ballasting, as well as the practical limitations of treating ballast water as it 

is loaded. Despite such concerns, these procedures are considered safe 
17 

when a ballast water management plan is developed in conjunction with 

the ship cargo plan to ensure that both ballast loading and discharge needs 

and the constraints on ballasting in certain locations are met. 

Biological Effectiveness

These practices can only serve as the first line of defense, and it is 

recommended that they be used in combination with other treatment 

methods or technologies. Careful control of where, when, or how 

ballasting is done could be very helpful in reducing the intake of 

organisms. However, these practices may not always be possible since 

ballasting is highly dependent on operational needs. 

Environmental Acceptability

This option is environmentally acceptable since these control practices 

simply reduce the number of organisms picked up or discharged by 

ballasting operations on or before departure. 

Status of Technology

No additional or special equipment is needed to implement these 

management practices. 

Cost 

Ships arriving into California waters are required to maintain records of 

ballast water operations. Examination of ships’ logs and records 

containing mandatory information for monitoring purposes would not 

impose any additional economic burden on the shipping industry. There 

would be no other additional costs to carry out ballasting avoidance 

procedures except perhaps in the cases were additional monitoring would 

be necessary. This assumes that the vessels already use ballast water 

management procedures. However, additional costs could be incurred if a 

vessel moves offshore in an attempt to minimize uptake of organisms. 

Ballast Water Exchange (BWE) 

Description

The concept behind BWE is that freshwater, estuarine or near shore 

coastal organisms taken during ballasting operations at a port of origin are 

replaced with deep mid-oceanic organisms during the voyage. Upon 

arrival at a port of destination, mid-oceanic organisms are discharged into 

a near shore coastal, estuarine, or freshwater environment. An important 

underlying assumption of BWE is that mid-ocean organisms cannot 

survive in coastal and freshwater habitat. This assumption is strongest 

when ships carry out BWE while traveling between freshwater ports of 
18 

call. The assumption is weakest when mid-ocean organisms are 

discharged in coastal and estuarine environments where environmental 

conditions may not be different significantly enough to provide an 

inhospitable environment to the incoming organisms. 

The amount of ballast water carried by ships depends on the type of ship, 

cargo load, weather, and the depths at different ports. Some ships may 

carry as much as 36 percent of the ship’s dead weight tonnage (dwt) in 

ballast water (Cohen, 1996). During ballasting and de-ballasting 

operations, a ship will flood or empty its tanks by gravity or by using high 

volume pumps. Most ships’ ballast tanks are interconnected with pipes 

leading to a common water intake. The intakes are located in the ship’s 

side, covered by a metal grating to exclude large objects and larger aquatic 

organisms. Behind the grating is the sea chest that functions as a reservoir 

to the ballast water delivery pipe system, which finally enters the ballast 

tanks. In most ballast tanks, the end of this ballast pipe system is typically 

located at several inches above the bottom of the tank, invariably 

contributing to the accumulation of water and sediments in the ballast 

tanks. 

BWE operations are currently accomplished by two methods: 

• Empty-refill exchange (ERE) – This method requires a ballast tank to 

be pumped empty and then refilled during a voyage. The emptying 

and refilling procedure is commonly accomplished using the existing 

water intake/suction piping system and the ballasting pumps, which 

are also used to empty and refill the tanks. IMO guidelines 

recommend that ballast water be discharged until suction in the ballast 

tanks is lost. It has been suggested that during full tank ballasting 

procedures, large changes in loading conditions could affect stability, 

strength, draft, and trim of the ship. However, newer and larger 

vessels have been reported to conduct ERE without harmful 

consequences to the ship. 

ERE was originally reported to accomplish over 90 percent ballast 

water exchange efficiency. However, various studies have indicated 

that such efficiency is rarely achieved. Lower efficiency can result 

from a number of factors, including ballast tank size and design, 

pumping system, volume of unpumpable ballast water and sediment 

residual at the bottom of the tanks, and sea conditions during ballasting 

operations. Studies referenced by Dames and Moore (1999) have 

reported that exchange efficiencies ranging from 70 to 90 percent are 

more realistic. Furthermore, Hay and Tenis (1998) concluded that, in 

terms of the efficiency of eliminating nonindigenous organisms, ERE 

would not be as efficient because much of the sediment and organisms 

at the bottom of tanks would not be removed during ballasting 
19 

operations. Emptying and refilling tanks would probably result in resuspending sediments and organisms that are not discharged. 

• Flow Through Exchange (FTE) – In this method, ballast tanks are 

flushed out by pumping mid-ocean water into the ballast tanks during 

voyage allowing port water to overflow out. This method requires a 

separate uptake and outflow system. Water is delivered to the tanks 

from the common water intakes originating from the sea chest. Water 

out flow is subsequently accomplished via ventilators and manholes on 

the ships’ weather deck. IMO recommends that, at a minimum, the 

volume of the tank should be pumped out three times. This 

recommendation was based in part on theoretical dynamics of dilution 

calculations and on some field trials (Rigby and Hallegraeff, 1995; 

Parsons, 1998). In theory, 95 percent of the original ballast tank water 

should be replaced if volumes equivalent to three times the tank 

volume are pumped through the tank. 

The Petrobras Company, a Brazilian oil company, developed a 

variation of FTE by reversing the process (IMO, 1998). In this 

system, water is taken in through the sea chest as usual and pumped up 

to a ballasting pipeline on the weather deck. The deck-ballasting 

pipeline then distributes water to each tank from above. A separate set 

of ballast pumps located at the bottom of the tanks is then used to 

discharge ballast water overboard. This system has all the advantages 

of the FTE system plus the additional benefits of being able to remove 

accumulated sediment along with water because ballast water 

discharge occurs from the bottom of the ballast tanks. 

Safety 

It has been reported that ERE is unsafe for ships over 40,000 dwt because 

the procedure requires ballast tanks to be completely emptied before the 

tank can be refilled. During the empty and refill process, the ship’s 

stability and maneuverability may be compromised due to the temporary 

lack of water in ballast tanks that maintain safe operation at sea. 

However, ships larger than 130,000 dwt entering New Zealand (Hay and 

Tenis, 1998) have reported carrying out ERE without any problems. 

Modeling studies have further demonstrated that ships of up to 

188,000 dwt have no stability or shear force problems if ERE is carried 

out in the correct exchange sequence. The hydrostatic analysis of data 

from a dry bulk carrier, a tanker, and a container ship showed that hull 

bending and stability did not exceed allowable still water values while 

ballasting and deballasting operations were carried out. In addition, 

strength calculations made for significant wave height of 20 feet indicated 

that bending moments and shears resulting from wave action were below 

American Bureau of Shipping design values. The study concluded that 

ERE could be carried out at sea safely as long as wave height is lower than 

10 and 20 feet (Woodward et al., 1994). 
20 

The FTE method is generally considered safer, but, in order to achieve the 

effectiveness of ERE in exchanging ballast water, it is recommended that 

the volume of the tanks be pumped out at least three times. Beyond 

having a ship’s crew on deck opening or checking vents in preparation for 

the FTE procedure, this method is not considered to compromise a ship’s 

stability as has been claimed for the ERE procedure (Hay and Tenis, 

1998). The FTE procedures are also safer than ERE when carried out 

during heavy weather conditions. Other safety considerations associated 

with FTE operations are that large volumes of water are overflowed 

through the ship’s air ventilators pouring over the weather deck. These air 

ventilators are not designed for constant water flow. While large volumes 

of water pouring over the weather deck may not be a problem on flushed 

decked bulk carriers, having water erupting from numerous air vents on 

container ships may not be desirable. Conversely, the Dilution Method 

system developed by the Brazilian company mentioned above is a closed 

process. Ship vents or manholes do not have to be used to discharge 

water, and the crew does not have to be on the weather deck during heavy 

weather conditions or exposed to waters that may contain pathogens. In 

addition, stability issues may not be as much a problem since in the 

Brazilian system ballast water is replaced and emptied simultaneously. 

Biological Effectiveness

The effectiveness of BWE procedures for treating ballast water is not well 

known. Some studies have been conducted on a broad range of ballast 

water systems configurations involving ships of different ages. These 

studies used salinity dilution and dye tracers to quantify the percent of 

water exchanged, or measured a variety of organisms to determine the 

biological effectiveness of BWE. Preliminary results from salinity and 

dye tracer on the bulk carrier, Iron Whyalla, have indicated that roughly 

95 percent of original water in ballast tanks is replaced after three tank 

exchanges in a FTE system (Rigby and Hallegraeff, 1995). However, 

exchanging 95 percent of ballast water may not mean that 95 percent of 

the organisms in the tank have been replaced or eliminated. Results of 

other studies, where the effectiveness has been measured using the 

abundance of biota, vary widely in the calculated percent reduction of 

organisms as a result of exchange procedures. Table 1 presents some 

published BWE effectiveness data. These data are from studies using 

different methods of calculation, different study designs, a variety of 

different ship types, and different taxonomic groups to evaluate the 

exchange of organisms. 

The effectiveness of BWE methods may be further compromised by the 

length of voyage since the time needed to carry out effective ballast 

exchange operations may be longer than the actual duration of the specific 

voyage. In addition, coastal routes occurring less than 200 miles from the 

coast in waters shallower than 2000 meters may affect the biological 
21 

effectiveness of exchange procedures since the main objective of carrying 

out BWE is to accomplish the replacement of coastal, estuarine, or fresh 

water organisms with deep oceanic organisms. Only in this way can BWE 

procedures potentially achieve the most effective control of the 

introduction of nonindigenous species. 
22 

TABLE 1: REPORTED ESTIMATES OF BALLAST WATER EXCHANGE EFFECTIVENESS 

Reference Effectiveness Type of BWE Taxa Type of Ships Number of Ships Methods and App

Locke et al., 1993 

67% reduction in organisms 

Unknown Zooplankton 

and rotifers 

Various 24 Calculation based on living zooplankton 

ballast tanks from 24 ships originating fports. Eight ships were found to contain freshwater tolerant that could survive dienvironment. 

Locke et al., 1993 

86% reduction in organisms 

Unknown Zooplankton 

and rotifers 

Various 14 Calculation based on same data as abov

14 were found to have completed BWE ≥ 30%. Two of the 14 ships contained lorganisms. 

Zhang and Dickman, 1999 

87% reduction in organisms 

ERE Diatoms and 

dinoflagellates 

Container 34 Calculation based on the percentage red

dinoflagellates. Mid-ocean exchange deabundance of harmful organisms on avecells 1-1. 

Zhang and Dickman, 1999 

83% reduction in organisms 

ERE Diatoms and 

dinoflagellates 

Container 34 Calculation based on the percentage red

of diatoms and dinoflagellates. Mid-octhe total abundance of diatoms and dinofrom 6600 to 1100 cells 1-1. 

Dickman and Zhang, 1999 

48% reduction in organisms 

ERE Diatoms and 

dinoflagellates 

Container 3 Calculation based on the percentage red

of diatoms and dinoflagellates. Mid-octhe total abundance of diatoms and dinofrom 838 to 436 cells 1-1. 

Rigby and Hallegraeff, 1995 

95% water replaced 

FTE Phytoplankton Bulk carrier 1 Calculation based on measurements of r

blue dye and the dilution of stained phycomplete mixed flow model, original wreplaced if three tank volumes are allowwas assumed that the rate of water replareduction in organisms. 
23 

Environmental Acceptability

Acknowledging the uncertainty of BWE effectiveness, IMO specifically 

recommends that exchange be carried out in deep ocean water at least 

200 nautical miles offshore. NISA guidelines also require BWE be carried 

out by ships entering the Great Lakes and the upper Hudson River, and 

suggests voluntary implementation of BWE in the rest of the country. 

California law requires the implementation of the same practices included 

in NISA guidelines unless an alternative technology can be employed that 

is as effective as BWE in treating ballast water. This requirement also 

extends to ships traversing coastal water unless an alternative exchange 

zone has been identified and approved. It is generally acknowledged that 

even under ideal conditions the method will be less than 95percent 

effective. 

Status of Technology

BWE is currently the most widely used method worldwide, despite the 

reported 70 to 95 percent effectiveness in water replacement and 48 to 

99.9 percent in aquatic organisms reduction. 

Cost 

The cost of conducting exchange procedures depends on the type of 

exchange being carried out, the age of the vessel, pump size, and the 

percentage of ballast water being exchanged. Full ballast tank ERE 

including initial new piping, pumps, maintenance, labor costs, and the 

development of a ballast water management plan has been estimated to 

cost approximately $0.02 per MT. FTE has been estimated to range 

between $ 0.06 and $0.08 per MT (Rigby, 1994; Rigby and Hallaegraff, 

1995). Furthermore, very large crude carriers (250,000 to 500,000 dwt) 

have been estimated to carry out ERE at a cost of approximately $0.12 to 

$0.35 per MT, based on 10 trips/year and 45 percent of the vessel’s dwt in 

ballast water (Dames and Moore, 1999). 

Onshore Treatment Alternatives 

Onshore Ballast Water Treatment, Treatment Ship, or Mobile 

Transport Facility 

Description

These treatment alternatives require that ballast water be transferred to an 

onshore treatment facility for treatment. In some ports, there may be 

enough space to establish a large-scale, shore-based facility to treat ballast 

water. The size of the treatment facility would depend on the number, 

timing, and type of ships entering the port system. It is conceivable that 

treatment could be done in treatment facilities specifically designed and 
24 

dedicated to treat ballast water, or perhaps in already existing facilities 

designed to treat wastewater. 

Alternatively, ballast water could be collected directly from a docked ship 

by barge or pipeline and transported to a centralized onshore facility. In 

these cases pipelines would be needed between the treatment facilities and 

all berths of a port system. Ships would also need to have their ballast 

water pumping system or other piping systems, such as the fire 

extinguishing water pipeline, modified to be able to connect to the berth 

piping system. In addition to shore-based facilities, a port authority would 

need to establish a mobile system for deballasting operations to lessen the 

ship draft before crossing shallow bars or entering a shallow port. This 

would be an additional cost to the ports. Depending on the amount of 

water needed for ballasting operations, land-based treatment facilities 

could also store treated water for use as ballast to allow a visiting ship to 

exchange untreated ballast water for treated ballast water. 

Safety

The safety considerations associated with land-based treatment facilities 

are the safety concerns over actual construction of land-based facilities, 

the vessel and port retrofitting operations, and ship and crew safety during 

pumping operations while docked. 

Biological Effectiveness

Onshore treatment, in principle, could have several advantages over 

onboard treatment options since there are already established effective and 

cost-effective methods for treating large quantities of wastewater. A landbased treatment facility operated by professional wastewater treatment 

specialists would allow a better control of the treatment processes. In 

theory, the port authority would be responsible for the operation and 

maintenance of the facilities and would be able to constantly monitor to 

determine extent of effectiveness of treatment. In addition, deposited or 

suspended sediments and organic materials could be effectively treated 

through the use of settling ponds or filtration. In a similar manner, cysts 

and spores, which are the forms most resistant to treatment, could also be 

removed. Vessels using the onshore treatment system might need to pay a 

per MT charge to have ballast water treated and disposed of in an 

environmentally acceptable manner in compliance with existing discharge 

regulations. Since ships often need to deballast in near coastal areas prior 

to entry into port, a deballasting mobile system must be in place to 

transport untreated ballast water to the onshore treatment facility. Without 

a mobile transport or mobile treatment system onshore treatment would 

otherwise be inherently ineffective. 
25 

Environmental Acceptability

Waste from a treatment process would be disposed of in an 

environmentally acceptable manner in compliance with appropriate state 

and federal laws and regulations. 

Status of Technology

One example of an onshore facility that treats ballast water in the U.S. is 

located at the Valdez Marine Terminal in Alaska. The facility is not 

designed to prevent the introduction of nonindigenous species but rather to 

treat non-segregated oily ballast water from oil tankers. The ballast water 

onboard oil tanker is typically carried in cargo holds where oil is also 

stored. The facility treats the oily ballast water by extracting the residual 

oil from the water. The segregated water is then treated to remove 

aromatic hydrocarbons and control pH levels and is later returned to 

receiving waters. The oil recovered from the treatment process is then 

returned to the oil tankers (Greenman et al., 1997). 

Ballast water treatment on land could be very effective in eliminating 

introduced species. Such a treatment facility could be designed in a 

similar fashion as the Alaska facility but with the specific objective to treat 

ballast water to prevent the introduction of nonindigenous organisms. It 

would be technically feasible to retrofit vessels and berths, build onshore 

storage tanks and treatment facilities, and dispose of treated water in an 

environmentally safe manner. However, without some form of 

transportation system to collect ballast water discharged outside of ports, it 

would not be operationally possible to treat all ballast water discharged 

into receiving waters for the purpose of reducing hull draft to pass over 

shallow port areas. A barge transfer system could help in this respect by 

providing the ability to collect ballast water while the ship is either at 

anchor, moored at the port terminal, or while navigating within port 

waters. Onshore treatment facilities could certainly be considered for 

terminals that handle smaller volumes of ballast water and have 

predetermined regular vessel calls (e.g., passenger vessels). 

Cost

The cost of onshore or mobile treatment options varies depending on the 

location of the facility and the amount of ballast water that would be 

treated. Capital cost of a port-based facility located either on land or on a 

mobile barge system ranges from $9 million to $19 million. Operating 

costs would range from $90 to $414 per MT of ballast water treated 

(Greenman et al., 1997). In a feasibility study recently conducted by 

Dames & Moore (2000) for the California Association of Port Authorities, 

four conceptual onshore ballast water treatment facilities with four 

different treatment capacities were designed. The ballast water treatment 

capacities considered in the study were: 1.0 million gallons per day (mgd) 
26 

(3,785 MTs/day) to account for the demands of the Ports of Los Angeles 

and Long Beach, 0.2 mgd (757 MTs/day) for the Ports of Humboldt Bay, 

Oakland, and San Francisco, 0.1 mgd (379 MTs/day) for the Ports of 

Redwood City, Richmond, Sacramento, San Diego, and Stockton, and 

0.001 mgd (4 MTs/day) for Port Hueneme. 

The main purpose of the Dames & Moore study was to assess at a 

conceptual level the technical and operational feasibility of onshore ballast 

water treatment at public port facilities. The cost calculations were based 

on a set of narrow assumptions and may not be representative. They only 

serve to give a general idea of how much it would cost to build and 

operate onshore ballast water treatment facilities of different capacities. 

Estimated capital costs for onshore treatment facilities (excluding costs for 

port piping and storage tanks) at specific California ports would range 

from approximately $1.6 million for the 0.1 mgd facilities for the Ports of 

Redwood City, Richmond, Sacramento, San Diego, and Stockton to over 

$2.2 million for the 1.0 mgd facilities at the Ports of Los Angeles and 

Long Beach. A treatment facility was not designed for Port Hueneme due 

to the very small volumes of ballast water involved. Total capital cost 

including all onshore treatment components needed to treat ballast water 

was estimated to range between $8 million and $50 million. 

The annual operating and maintenance (O&M) costs, including chemicals, 

electricity, labor (facility operators), laboratory costs, and landfill disposal 

costs were calculated for each port and would range from $142,000 to 

$223,000. Table 2 summarizes port specifications and estimated costs for 

land-based ballast water treatment facilities. 
27 

TABLE 2: PORT SPECIFICATIONS AND ESTIMATED COSTS TO INSTALL SHORE-BASED TREATMENT FACILITIES IN CALIF

Specifications Capital Costs 

Port Piping 

Length 

(km) 

2-Day 

Storage 

Tank 

(million gallons) 

Treat. 

System 

Capacity 

(mgd) 

Piping Cost Storage 

Tank Costs 

Treatment 

System 

Capital 

Costs 

Outfall 

Cost 

Total Annual 

O&M 

Costs

Hueneme 1.6 0.1 0.001 $ 1,056,000 $ 55,000 NA $100,000 NA NA Humboldt 19.3 .9 0.2 $12,672,000 $ 4,000,000 $1,781,000 $100,000 $18,553,000 $149,800 Long Beach 43.6 10.2 1.0 $28,617,600 $ 5,100,000 $2,220,400 $100,000 $36,038,000 $223,454 Los Angeles 41.2 40.6 1.0 $27,033,600 $20,400,000 $2,220,400 $100,000 $49,754,000 $223,454 Oakland 24.1 7.3 0.2 $15,840,000 $ 3,800,000 $1,781,000 $100,000 $21,521,000 $149,800 Redwood City 2.4 8.4 0.1 $ 1,584,000 $ 4,300,000 $1,631,500 $100,000 $ 7,615,500 $142,400 Richmond 8.9 6.6 0.1 $ 5,808,000 $ 3,400,000 $1,631,500 $100,000 $10,939,500 $142,400 Sacramento 2.1 9.4 0.1 $ 1,372,800 $ 4,800,000 $1,631,500 $100,000 $ 7,904,300 $142,400 San Diego 14.2 6.0 0.1 $ 9,292,800 $ 3,100,000 $1,631,500 $100,000 $14,124,300 $142,400 San Francisco 12.9 12.4 0.2 $ 8,448,000 $ 6,300,000 $1,781,000 $100,000 $16,629,000 $149,800 Stockton 8.2 10.9 0.1 $ 5,385,600 $ 5,500,000 $1,631,500 $100,000 $12,617,100 $142,400 
28 

Depending on the port configuration and ballast water discharge volume, 

the report estimated that the cost of treatment on land-based facilities 

would range between $1.40 and $8.30 per MT. 

A recent study prepared for the Port of Seattle by Glosten (2002) 

examined ballast water transfer to shore-based facilities and/or mobile 

systems as a way to manage ballast water in Puget Sound. The study 

included a survey of five different types of ships to identify the extent and 

capital costs of modification required to accomplish ballast water 

transfers. The modification costs calculated for each type of ship is shown 

in Table 3. The calculations assumed (1) the different types of ships are 

retrofitted with a universal deck connector to transfer the ballast water, 

and (2) the ship ballast system has been modified to minimize schedule 

delays imposed by ballast water transfer operations. 

TABLE 3: TRANSFER COST TO TREAT BALLAST WATER IN SHORE-BASED OR MOBILE 

SYSTEMS FACILITIES

Transfer Modification 

Type Capital Costs Ballast Capacity 

MTs 

(Approximate Gallons) 

Tanker $ 1,892,100 75,850 (20,160,000) 

Grain Ship $ 106,700 35,000 (9,018,190) 

Break-bulk $ 303,400 26,850 (6,922,740) 

Container $ 438,400 19,670 (5,069,120) 

Car Carrier $ 160,700 6,600 (1,701,180) 
29 

On Board Treatment Technologies 

Filtration and Hydrocyclonic Separation Systems 

Description

These technologies have been considered a viable option for preventing or 

minimizing the intake of unwanted organisms into ballast tanks. The 

systems can be simple or complex requiring different levels of detailed 

engineering to achieve the filtration needed to provide the appropriate 

level of protection. A simple filtration system can be comprised of the 

installation of various types of screens, strainers or membranes designed 

to physically remove organisms above a specific size from ballast water 

during ballasting operations. 

Strainers are simple mesh layers that can clog when the effective opening 

of the screens is reduced. In water treatment processes where filtration is 

used, large areas of filtering screens are required to maintain working flow 

of water for any period of time. Generally, backup systems are included 

so that continual flow stream can be achieved despite rapid rates of 

plugging. Self-cleaning strainers have been developed with automatic 

control systems incorporating cleaning cycles that can be activated by 

differential pressure or on a time cycle. Some research on the 

effectiveness of screen filters with filtration in the range of 20 to 

100 microns has been completed. These screen filters appear to be most 

suitable for onboard ballast water treatment, but the filter system must 

include the automatic back-flush capability to meet the requirement of 

unattended automatic operation. 

On the opposite end of the spectrum is a continuous flow centrifuge 

capable of separating solids and large organisms from water at extremely 

high flow rates (cyclonic separation systems). This flow-through 

centrifugation system accomplishes the separation of solids and organisms 

through the creation of a strong vortex in the flow as water flows through 

the machine. As ballast is pumped onboard, water enters the separator 

producing a cyclonic flow inside the machine. The centrifugal force 

concentrates solid particles and large organisms against the outer wall, 

allowing water to move through the center of the separator. An advantage 

of this system is that there are no movable parts, no filter elements or 

screens to clean. Consequently, no back washing operation is needed. 

The system is reported to require little or no maintenance and, if properly 

designed, could be operated through simple controls. However, 

preliminary results from field trials onboard ship carried out in California 

(2002) indicate that the system does not perform as claimed. 

The biggest drawback of filters and cyclonic separator systems is that it 

can not be applied as a single system treatment option. These systems can 
30 

be used as a primary system to separate the larger particles from ballast 

water as it is taken onboard. Smaller materials such as sediments, 

microplankton, bacteria, and viruses will not be separated from the water 

using this approach. 

Safety

Both technologies are considered safe since both are installed after the 

ballast pumps and do not affect normal ballasting operations. 

Biological Effectiveness

The Great Lakes Ballast Technology Demonstration Project investigated 

the effectiveness of an automatic backwash screen filtration system. 

Testing was carried out aboard the dry bulk carrier, the M/V Algonorth, 

and later onboard a stationary barge (Parsons et al., 1999). The shipboard 

system consisted of two filter units (a 250-micron pre-filter unit and a 25-

micron, 50-micron, 100-micron, or 150-micron filter unit) connected in 

series. The barge tests were conducted at two different locations within 

Lake Superior. The barge-based tests not only evaluated a similar 

filtration system evaluated on the M/V Algonorth but also tested cyclonic 

separation and an ultraviolet radiation system as well. Biological 

effectiveness was measured by comparing zooplankton, phytoplankton 

and microbial concentration with and without filtration treatment. Results 

showed that the two smallest filters achieved 95-99 percent effectiveness 

at removal of macrozooplankton, and 70-80 percent removal of 

microzooplankton and phytoplankton. While bacteria that attach to 

organisms and other material were reduced significantly, total bacteria 

counts were unaffected by filtration. The study concluded that filtration 

with automatic back-flush screen filters was feasible with existing 

technology down to approximately 50 microns (Cangelosi et al., 1999). 

Environmental Acceptability

Both treatment technologies are presently considered attractive options to 

prevent or minimize the intake of unwanted organisms in ballast water. 

Further studies are being conducted to determine operational capabilities 

and biological effectiveness. In the final portion of the cyclonic separation 

system process, filtered organisms could be disposed of simultaneously as 

ballasting operations are underway. Preliminary studies suggest that such 

systems could help reduce the risk of introduction of harmful organisms 

by ships. However, it is likely that there would be a need for a secondary 

treatment system to achieve a more effective control of organisms 

introduced into ballast water. 

Status of Technology

The Singapore Environmental Technology Institute, in collaboration with 

the Maritime and Port Authority of Singapore and the National University 
31 

of Singapore, has been testing various ballast water treatments including 

screen filtration (Matheikal et al., 2001). It is believed that this type of 

filtering system has the potential to be the most effective treatment 

technology for ballast water management if designed in the appropriate 

size with automatic self-cleaning to handle large volumes of ballast water 

without clogging. This is due to advances in manufacturing technology 

that enable filters to remove particles down to the 10 micron range and the 

engineering designs that allow filtration systems to be very small, less 

complex, and simple to operate. 

As mentioned previously, filtration and cyclonic separation systems have 

been and are currently being tested as part of the Great Lakes Ballast 

Technology Demonstration Project. Early experimental work by the 

Northeast-Midwest Institute has led to important improvements in the 

combined two stage Cyclonic/Ultraviolet treatment system developed by 

Hyde Marine, Inc. Most recently, the Stolt-Nielson Transportation Group 

has agreed to install the Cyclonic/Ultraviolet system on the chemical 

tanker M/T Aspiration in order to provide further information on the 

operational and biological effectiveness of the treatment system. 

In California, as part of the West Coast Demonstration Project, the 

R.J. Pfeiffer of Matson Navigation and the Sea Princess of Princess 

Cruises have also installed the Hyde Marine, Inc. Optimar Ballast System. 

The first stage of this two-staged treatment system includes an in-line 

cyclonic separator designed to remove material heavier than sea water. 

This stage is used during ballasting operations where separated particles 

can be discharged back into the source waters. The second stage treatment 

uses ultraviolet irradiation (discussed later) to kill or deactivate biological 

organisms, including bacteria and viruses. Preliminary results from at-sea 

evaluations on the Sea Princess are inconclusive, but further evaluations 

are planned. 

A consensus emerging from these tests and tests that are currently being 

conducted on other technologies is that the effectiveness of other 

treatments is enhanced when a primary filtration stage is installed to 

remove larger particles in ballast water. 

Cost 

Estimated costs for a hydrocyclone/ultraviolet combination system is 

approximately $120,000 (Hyde Marine Inc., 2001) to $140,000 

(Cangelosi, 2001). Capital costs for installing a filtration system is 

approximately $40,000, although this cost can vary depending on ship 

type and extent of retrofitting necessary. Installation of the Optimar 

Ballast System on the R.J. Pfeiffer of Matson Navigation was estimated to 

cost $380,000, but the actual cost was closer to $500,000. Larger vessels 
32 

may require several systems to properly manage large volumes of ballast 

water, and, as a result, the cost would be several times higher. 

Biocides 

Description

This type of treatment consists of using either oxidizing or non-oxidizing 

biocide chemicals to treat ballast water. Oxidizing biocides include, but 

are not limited to, such chemicals as chlorine, chlorine dioxide (Simpson, 

2001), ozone, bromine, hydrogen peroxide, and Paraclean® peroxy acetic 

acid (Fuchs et al., 2001). Many of these chemicals have been widely used 

in wastewater treatment facilities for years. Organic structures, such as 

cell membranes, are destroyed with the use of some of these chemicals. 

Non-oxidizing biocides include a large number of compounds generally 

used in industry for killing and preventing the growth of organisms in 

cooling water towers, intake pipes, and other industrial system process 

areas where large amounts of biological growth or sediment accumulation 

occur. Non-oxidizing biocides work like pesticides; they interfer with the 

physiological and metabolic processes of organisms. Non-oxidizing 

biocides include, but are not limited to, such compounds as Acrolein® 

(Baker Petrolite, 2001), Seakleen® (Wright, 2002), tributlytin, dissolved 

copper, dissolved silver, glutaraldehyde, and organic acids. 

Biocides can be added to ballast water by metering concentrated solutions 

through chemical injection pumps that feed directly to the main ballast 

pumps during ballasting operation. Biocides such as chlorine, copper, and 

silver can also be generated electrolytically from sea water but the 

electrolytic generation system requires significant amounts of electricity. 

Biocides such as Acrolein® are injected into the ballast tank by allowing 

increased nitrogen pressure to displace the biocide from the container into 

the treatment ballast tank (Baker Petrolite, 2001). Other application 

methods consist of diluting appropriate amounts of soluble biocide 

compound into a 55-gallon drum and then pumping the biocide into the 

influent ballast water stream. 

Safety

Although many hazardous industrial compounds are routinely carried on 

ships, there are some safety issues associated with handling and storage of 

biocides on ship. Residual amounts of some chemicals left on the ship or 

in ballast tanks after treatment may cause corrosion of piping, pumps, and 

other structural components of the ship. There are also some concerns 

about the addition of powerful oxidative biocides such as chlorine to 

ballast water since chlorine could react with sea water and produce toxic 

byproducts. 
33 

Biological Effectiveness

Although biocides have been widely used in wastewater treatment 

processes, testing onboard ship to treat ballast water is just beginning. 

Laboratory tests of exposure of target organisms to a variety of biocides 

have had varying levels of biological effectiveness. For instance, in 

laboratory tests, 24-hour exposure to copper sulfate, an algicide, at 

concentrations of 200 parts per million (ppm) up to 10,000 ppm at varying 

levels of pH and salinity was found to be ineffective in killing 

dinoflagellate cysts. Other biocides such as chlorine tested at 10 to 

2000 ppm, and hydrogen peroxide tested at 100 to 60,000 ppm were found 

to be effective only at high concentrations (Cohen, 1996). However, 

laboratory tests conducted with Acrolein® detected no viable motile 

dinoflagellates in any Acrolein® treated samples and a significant 

reduction of test bacteria samples with the lowest concentration of 

Acrolein® used (Baker Petrolite, 2001). In laboratory tests exposing the 

biocide Seakleen® to a wide variety of marine and freshwater aquatic 

organisms representing major taxonomic groups indicated that a high 

degree of toxicity was achieved with the administration of low 

concentration of the biocide (1 ppm). An effective treatment dose is 

estimated at approximately 1-2 gallons per MT of ballast water. 

Seakleen® is reported to be an organic oxidant that contains no corrosive 

properties that could affect the structural elements of a ship (Wright et al., 

2002). 

Environmental Acceptability 

Biocide treatment equipment could be relatively simple and requires little 

maintenance. Nevertheless, the application of chemicals to kill aquatic 

organisms in ballast water has generated the following concerns: 

1. Residual chemical compounds discharged to receiving waters after 

treatment occurs. 

2. Uncertainties regarding the biological effectiveness of biocide and the 

relative concentrations of chemicals needed to achieve satisfactory 

level of organism inactivation. This would need to be tested under 

full-scale conditions. 

3. Compliance with discharge regulations not only in U.S. waters but 

internationally. 

These concerns need to be addressed through adequately designed field 

tests and through appropriate legal, economic, and political analyses. 
34 

Status of Technology

At present, few biocides have been tested under laboratory conditions. 

Some are being tested on ship, but most biocides proposed for use in 

treating ballast water have not been field-tested. 

Cost

The cost for dosing equipment to apply Seakleen® is estimated to be at 

approximately $1600. The biocide would retail at less than $.20 per MT 

of ballast water (Wright et al., 2002). Acrolein® application is estimated 

to cost between $.16 to $.19 per MT. Other than necessary minor ship 

modifications, capital cost could be negligible for the ship owner because 

little or no new equipment would be needed. That is, biocides could be 

applied by a service company in port. The service company would be 

responsible for its own application equipment. (Bonnivier, personal 

communication, 2002). 

Heat Treatment 

Description

In this process, heat would be used to elevate the temperature of ballast 

water to the level necessary to kill all aquatic organisms. The methods 

used to accomplish this would vary from ship to ship. The exhaust gases 

from operation of diesel engines and the use of engine cooling water 

during a voyage have been proposed as possible sources of heat. 

Regardless of heat source, water to be disinfected is drawn into a heat 

exchanger circuit where it is heated to the temperature needed to disinfect 

the water. 

A heat exchanger is a device that transfers heat from a higher temperature 

fluid or gas to a cooler fluid via a conducting surface. There are two basic 

kinds of heat exchangers: shell and tube, and plate type. In a shell and 

tube heat exchanger, a bundle of tubes is placed within a cylindrical shell. 

On a plate type heat exchanger, a number of pressed plates are surrounded 

by seals and held together by a frame (Taylor, 1990). 

In the exhaust gas system, exhaust from an engine is used to heat the 

ballast water to the required temperature by transferring waste heat to a 

heat exchanger. The extra exhaust heat is then discharged through the 

stack. The ballast water is either routed directly through the heat 

exchanger and then back to the ballast tanks or from the ballast tank to the 

heat exchanger and then to the ballast tanks. Alternatively, the ballast 

water can also be routed to a holding tank in order to increase the amount 

of time required to do proper treatment at the prescribed temperature. 

(Hi Tech Marine, 2001). 
35 

A system using exhaust gases as a heating medium would require 

additional piping in order to move the exhaust gases, and/or heated 

cooling water from the engines to the heat exchanger. Additional piping 

would also be needed to connect the ballast water system to the heat 

exchanger. Units using a boiler to raise the temperature of ballast water 

are similar. This system must also include a fuel source for the boiler and 

the removal of exhaust gases. 

Safety

The use of heat to treat ballast water could create minor hot water hazards, 

but fortunately many of these hazards can be removed or ameliorated 

during the design and installation phase of the system. Steps are normally 

taken aboard ship to prevent injury from hot surfaces, as it is a common 

hazard on ships. Pipes conducting heated fluid are typically insulated to 

prevent loss of energy and to protect crew members. Whenever possible 

such a system, especially the heat generating exchangers or boilers, should 

be installed away from potential contacts with crew and other industrial 

machinery. 

Some concerns have been raised regarding the effects of higher 

temperature on ballast tank corrosion, but studies have indicated that this 

effect is not major (Rigby et al., 1999). There is also a potential risk that 

filling empty ballast tanks with hot water could result in expansion and 

contraction of steel structures. This could compromise the structural 

integrity of the ship. Further analysis is necessary to determine if a risk is 

present (Buchholz, 1998). 

Not accounting for the installation of heat exchangers to strip and recycle 

heat from treated water, there are concerns about the discharge of hot 

water overboard. The heated water that is discharged overboard could 

represent a thermal threat to nearby marine life. 

Biological Effectiveness

The effectiveness of a heat treatment system depends on the ability of the 

equipment to raise the temperature of the ballast water to the thermalthreshold of the target organisms. Thermal threshold is the point at which 

an organism is killed due to either denaturing of cellular proteins or 

increasing the organism metabolism beyond sustainable levels. Thermal 

threshold varies among different species, so does the species’ ability to 

endure periods of high temperatures that are below their thermal 

thresholds. In general, temperatures close to an organism’s thermal 

threshold can be tolerated for short periods of time with little 

nonreversible damage. In temperatures cooler than the thermal threshold 

organisms can survive for longer periods. The ballast water should be 

heated to 110-150°F in order to kill a wide variety of organisms. The 
36 

exact temperature and length of exposure will vary according to system 

capabilities and the target organism (Buchholz, 1998). 

The most effective technique of heat treatment lies in continuous rather 

than batch treatment. In initial laboratory tests, Bolch and Hallegraeff 

(1993) showed that heating to temperatures of 40°C (104°F) to 45° C 

(113°F) for 30 to 90 seconds would result in 100 percent mortality for

Gymnodinium catenatum cysts (red-tide dinoflagellate). Sea trials carried 

out by Rigby et al. (1999) on the Bulk Carrier Iron Whyalla indicated that 

heat treatment of ballast water to temperatures of 38°C (100.4°F) for 

several days was sufficient to destroy all zooplankton and a major portion 

of the phytoplankton in the test ballast tank. There have been concerns 

that this temperature is not sufficient to kill pathogenic bacteria such as 

Vibrio cholera. However, some onboard heating systems are reported to 

be capable of attaining temperatures of 65°C (149°F), which would be 

adequate to kill the cholera bacterium (Hi-Tech Marine, 2001). Further 

onboard heating treatment trials on the Australian Bulk Carrier 

Sandra Marie reported to achieve 80 to 90 percent effectiveness despite 

the fact that it was sailing in heavy seas and gale force winds and only 

80 percent of the ballast water was treated. Of course, longer exposure 

times would be needed to achieve the same results at lower temperatures. 

Status of Technology

The components of heat treatment technology are commonly available. 

Boiler parts and units and heat exchangers are available from a large 

number of vendors around the world. Much of the technology is already 

developed and very reliable. The actual layout of a heat treatment system 

will vary widely and will depend on the size of the power generator and 

the physical layout of the ballast tanks. 

A major disadvantage of this type of system is associated with ship 

retrofitting. Retrofitting could require extensive piping modifications 

because water would need to be redirected from the ballast system to the 

heating medium. The main advantage, however, is that all the components 

needed to carry out a retrofitting project are also readily available. In 

addition, the crew would only need minimal training to operate the 

equipment since it is comprised of components that are commonly used on 

ships. 

Environmental Acceptability

The only two environmental concerns associated with heat treatment 

systems are potential thermal pollution and air quality problems. Thermal 

pollution may occur if large volumes of heated water are discharged into 

receiving waters, causing localized thermal effects on the immediate 

aquatic environment. However, heated water in the ballast tanks tends to 

dissipate gradually from the ship during voyage, reducing the potential of 
37 

a thermal impact on receiving aquatic environment. Also, using recovery 

heaters, which would remove much of the residual heat from treated water 

before it is discharged, could control any excess heat. 

Air pollution problems may occur if heat-generating equipment needs to 

be operated during extended periods of time in order to heat ballast water 

to required temperature. This problem can be avoided through the use of 

heat already generated by the main boiler system and engine cooling 

jackets. 

Cost

The cost of this system varies due to many factors. The most important 

factors are the amount and type of piping that must be installed to 

interface with the ballast water system, and the type and size of the heat 

exchangers or boiler. All of this would be determined by the amount of 

ballast water to be treated. Rough cost estimates are $28,000-$45,000 for 

a heat exchanger, and $60,000 to $600,000 for a boiler system (Buchholz, 

1998). Rigby et al. (1999) estimated that it would cost approximately 

$.03 per MT to treat ballast water not including installation costs for 

additional piping or equipment. 

Ultraviolet Light 

Description

Ultraviolet treatment works to achieve sterilization by exposing target 

organisms to Ultraviolet light (UV) energy waves. 

These systems are usually constructed with stainless steel to help prevent 

corrosion, and the lamps are enclosed in protective quartz sleeves. In a 

disinfecting system, UV lamps are submerged in an open channel of 

water, or installed within pipe systems so the water flows past the UV 

lamps exposing the organisms to the required lethal dose of radiation. 

Lamps are generally used in a linear configuration, but they can also be 

twisted into loops or in a spiral configuration to increase the intensity 

along a linear axis. The exposure time and the intensity of the UV light 

application would determine the effectiveness of a lethal dose. In 

addition, the system performances would not only be affected by the dose 

and flow rate but also by the water quality of the water being treated. 

Ultraviolet absorbing constituents in water, such as organics, turbidity, and 

color, can influence the effectiveness of the system. As UV transmission 

decreases, additional UV energy would be required to maintain peak 

effectiveness. 

UV waves can be emitted in two ways: continuous-wave and pulsed-wave 

delivery. The continuous-wave delivery provides a constant flow of low 
38 

level UV waves and is segregated into low and high intensity treatments. 

The pulsed-wave UV delivery system provides radiation doses through a 

flashing of the source lamp. This pulsing technique provides short bursts 

of higher energy into the system. High intensity UV waves, whether 

pulsed or continuous, will increase the range of transmittance and allow 

for more effective treatment of higher turbidity water or larger volumes of 

low turbidity water (Buchholz et al., 1998). The disadvantage of high 

intensity treatment is proportionately higher energy demands. 

Typical maintenance procedures to maintain peak effectiveness in these 

systems include cleaning the quartz sleeves, replacing lamps, and 

checking proper function of the power module, inspecting the overall 

structural integrity of the system which includes a pretreatment unit. 

Training required for these procedures would be minimal. 

Safety

As proven technology, UV systems are currently used for multiple 

purposes in primarily fresh water systems. Existing land-based 

applications are reported to need minimum maintenance and monitoring 

while in operation. Although the technology has existed for some time, it 

has just recently been tested for shipboard operation (Cangelosi, 2002). 

Some of the concerns raised with regard to UV systems are: 

• The use of mercury-containing lamps to generate UV radiation could 

be of concern onboard a ship where there is a high potential for 

physical damage during storage and installation. 

• Exposure of plastic piping to UV radiation for prolonged periods could 

cause degradation and eventual failure of such systems. 

• Although other treatment systems may also induce mutagenic effects, 

organisms that survive the UV treatment process could be genetically 

altered from the damage caused by UV photons. These genetically 

altered organisms could have a better survival potential when 

discharged into receiving waters environment. It is expected that most 

or all of the surviving organisms with damaged genetic material would 

fail to reproduce (Buchholz et al., 1998). 

Biological Effectiveness

Ultraviolet radiation is electromagnetic energy within the range of 

4-400 nanometers (nm) wavelength. This range of wavelengths is further 

subdivided into three levels, UV-A (315-400 nm), UV-B (280-315 nm), 

and UV-C (15-280 nm). The shorter wavelengths (< 280 nm) are 

generally considered to be the most effective against bacteria and viruses. 

Damage occurs through photodegradation, resulting in cell wall 
39 

destruction and alteration of cell genetic material and thereby prevent 

successful reproduction. 

There are several variations of two different types of lamps commercially 

available today. These are the conventional low-pressure (LP) mercury 

arc lamp that emits monochromatic UV light at a wavelength of 253.7 nm 

in the UV-C germicidal range, and the higher intensity medium pressure 

(MP) mercury arc lamp that emits a UV polychromatic light at all 

wavelength (UV-A, B, and C) but concentrated at selected peaks within 

the germicidal wavelength region (Cairns, 2001). UV irradiation from 

efficient LP mercury lamps or from less efficient but more intense MP 

mercury lamps brings about photochemical transformations in the nucleic 

acids of the target microbes. The amount of damage caused by the UV 

radiation (the effectiveness of treatment) is related to the intensity of UV 

light (germicidal effective range) and the exposure time target organisms 

are exposed at the germicidal effective range. The UV dose can therefore 

be expressed as units of intensity of UV light in milliwatts per square 

centimeter and exposure time in seconds. Typical UV doses for drinking 

water range between 16 and 40 milliwatts per squared centimeter per 

second (mW/cm2/sec). Table 4 shows the percent reduction of different 

bacteria and viruses when irradiated with a dose of 20 mW/cm2/sec 

(Cairns, 2001). 

TABLE 4: PERCENT REDUCTION OF DIFFERENT BACTERIA AND VIRUSES IRRADIATED WITH 

20-MW/CM2/SEC DOSE 

Organisms Percent Inactivation Organisms Percent Inactivation 

Bacillus anthracis 99.9964 Shigella dysenteriae 99.9999 

Clostridium tetani 97.8456 Streptococcus faecalis 99.9972 

Corynebacterium 

diphthera 

99.9999 Vibrio cholera 99.9162 

Escherichia coli 99.9999 Influenza virus 99.9997 

Legionela pneumophila 99.9999 Poliovirus 99.7846 

Mycobacterium 

tuberculosis 

99.9536 Rotovirus 98.3014 

Pseudomonas aeruginosa 99.9769 Saccharomyces cerevisiae 99.8179 

Salmonella paratyphi 99.9999 
40 

The ability of UV to treat unfiltered water is dependent on water clarity 

and turbidity. Since most coastal waters contain large amounts of 

inorganic and organic particles, which will decrease the effectiveness of 

UV treatment, it is recommended that some type of filtration in addition to 

UV treatment be used to remove larger organisms and solid matter from 

the flowing water. To achieve the kill rate of a combined filtered/UV unit, 

an unfiltered/UV unit must expend more energy to be as effective. It has 

been recommended that a filter between 25-50μ is ideal for removing 

sediment, and organisms larger than bacteria, and viruses (Cangelosi et al., 

1999). Length of exposure time at prescribed dose also helps determine 

effectiveness of the kill rate. Also, the UV wavelength delivered 

determines both effectiveness of kill and the energy required for operation. 

Studies of low and medium treatment on Zebra mussels indicate that 

medium pressure systems yield nearly 100 percent inhibition of mussel 

settlement (Lewis et al., 1996). Other studies have been conducted using 

xenon arc lamps (500 watts) that are capable of delivering higher levels of 

UV radiation over a greater portion of the UV spectrum. Results of these 

studies have indicated that veliger (free swimming mussel larvae) and 

post-veliger larvae were extremely sensitive to short exposures to a wide 

UV range, ceasing all swimming or crawling motions after exposure 

(Chalker-Scott et al., 1994). 

The Great Lakes Demonstration Project’s studies indicated that UV 

radiation alone is effective at reducing zooplankton, phytoplankton and 

bacteria growth, but physical and chemical conditions influence the UV 

performance. Further studies have suggested that re-growth occurs after 

retention in the ballast system and recommended that UV treatment be 

conducted on both intake and discharge (Cangelosi et al., 1999; Cangelosi, 

2001). Recent studies (work in progress) being carried out by scientists 

from the San Jose State University Foundation and the San Francisco State 

University suggest similar results. 

Environmental Acceptability

There are concerns with UV treatment and the accidental release of low 

level mercury if mercury-containing lamps are broken or improperly 

disposed. In most UV disinfection applications, the short wave portion or 

UV-C (200-280 nm) is used for the most effective treatment. Exposure to 

this UV range interrupts normal DNA replication and the organisms are 

either killed or inactivated. Although the risk that mutated organisms 

survive to invade a new environment is considered low (Buchholz et al, 

1998), the treatment has the potential of causing genetic mutations in 

microorganisms that survive treatment process. 

Status of Technology

The UV system process has been in common use for some time in 

hospitals, laboratories, and associated industries as well as in food 
41 

processing, potable water sterilization, aquaculture, municipal and 

industrial wastewater treatment, and other operations requiring the 

elimination of microbial contamination. Recently, systems have been 

designed for use onboard ship. The Great Lakes Demonstration Project 

reported that such systems, when coupled with some type of filtration, 

could be effective in controlling the introduction of nonindigenous aquatic 

species in ballast water. However, there are still outstanding engineering 

questions that need to be answered regarding the installation and operation 

onboard different types of ships. In addition, the exposure time and 

intensity of UV application to achieve adequate inactivation or elimination 

of ballast water entrained organisms have not been well defined. 

Cost

Ultraviolet treatment systems are a readily available technology. These 

systems are already commonly used onboard for treatment of sewage. 

They are reported to be simple to operate and maintain, and ship crews 

only need minimal training to operate the system. The cost of this 

technology depends on the amount of water to be treated, the pumping and 

pre-filtering costs, and the UV dosage to be administered. Cost estimates 

based on a 1200 to 8000 gallons per minute (gpm) treatment system range 

from $10,200-$542,000 (Buchholz, 1998). Operating costs for a 1200 

gpm system range between $2,200 to $4,000 per year assuming 10 percent 

duty cycle, one set of backup lamps, and normal maintenance procedures 

(Buchholz et al., 1998).

Ultrasound 

Description

Ultrasound (sonic spectrum ranging from 20 kHz and 10 MHz) can be 

used to generate high frequency energy that cause liquids to vibrate 

producing physical and chemical effects in the treated liquid. A high 

voltage current actuates an ultrasonic transducer, which in turn generates 

vibration in a liquid. The generated waves tend to travel perpendicular to 

the resonated surface. When liquids are exposed to these high frequency 

vibrations, the physical and chemical changes result in cavitation. 

Cavitation can be defined as the rapid formation and collapse of 

microscopic gas bubbles in liquid as the molecules in the liquid absorb 

ultrasonic energy. Sound waves of different density and intensity rapidly 

move through the liquid media. Waves of sufficient intensity will break 

the attractive forces in the existing molecules and create gas bubbles. As 

additional ultrasound energy enters the liquid, the gas bubbles grow until 

they reach a critical size. Upon reaching the critical size, the gas bubbles 

implode or collapse. The cavitation effects kill the organisms within the 

liquid medium. The implosion of microscopic gas bubbles of the liquid 

ruptures the cell membranes, and collisions with other organisms and 
42 

particulate matter can also cause further mortality within the target area 

(Buchholz et al., 1998). 

Ultrasound transducers are usually constructed of steel, titanium, 

aluminum, ceramic material, or in combinations such as aluminum stacked 

with ceramic discs. In cases where space is at a premium, transducers can 

be submerged into the ballast tanks. 

Safety

The most prominent concerns with the use of ultrasound systems is that 

the transducer can generate high temperatures while in operation, which 

would necessitate the use of cooling water to avoid overheating. 

Biological Effectiveness

In an ultrasound unit, small organisms and the cell walls of larger 

organisms are ruptured by the frequency of the ultrasonic energy, causing 

death to the target organisms. This technology has been researched for 

shipboard applications other than ballast water treatment. The ultrasound 

equipment has been developed for small-scale flow [< 100 gpm] 

degreasing and cleaning purposes. An appropriately designed ultrasound 

system could achieve a high level of biological effectiveness on bacteria 

and viruses. 

Some manufacturers have developed systems that could be effective in 

treating ballast water and the water flow associated with large volumes of 

water. However, these systems have not been tested on ships. 

Nevertheless, laboratory tests have shown good results. Table 5 shows the 

biological effectiveness on various organisms using a 100-gpm ultrasound 

unit for processing unfiltered water (Buchholz et al., 1998). 

Filtration also has a mixed effect on the effectiveness of an ultrasound 

system. Although filtering out larger particles will increase the 

effectiveness by removing organisms that have higher resistance to the 

energy waves, removal of particulate matter that might kill small 

organisms through collision may reduce the overall effectiveness. 

Environmental Acceptability

There are no known or anticipated environmental concerns associated with 

this technology. 

Status of Technology

Ultrasound technology is relatively new and has only been applied within 

the past few years in the wastewater treatment field and industrial cleaning 

applications. Ultrasound units already in existence are typically smaller 

scale units that can handle loads of 60-100 gpm. This flow rate is too low 
43 

for maritime application, which usually requires around 1200-gpm flow 

for ballast operations. 

TABLE 5: BIOLOGICAL EFFECTIVENESS ON VARIOUS ORGANISMS USING A 100 GPM ULTRASOUND 

UNIT FOR PROCESSING UNFILTERED WATER

Organism Type Size Performance 

Zebra 

Mussel 

Veligers 

Mollusk 70 microns 100% mortality1

Polio Virus Virus <5 microns 7 log10 reduction 

Heliminth 

ova, Ascaris

Nematode 8-10 microns 100% 

inactivation 

Cryptospori

dium 

parvum 

Bacteria ~5 microns 6-7 log10

reduction 

Data source: Innovatech Environmental Solutions Inc., Advance, NC 

1

100% mortality of zebra mussel veligers has also been demonstrated in 600 gpmflow systems 

One system, the High Power Ultrasonic Process (HPUP), reportedly 

shows promise. This system delivers energy vibrations into the liquid at a 

much greater intensity than other conventional systems. The HPUP 

produces more intense cavitation, thereby requiring less exposure time for 

mortality to occur and allowing high flow rates of the treated liquid 

(Buchholz, 1998). 

Another way to increase the capacity of the ultrasound treatment is to 

locate the unit in the ballast tanks. This would require a costly retrofit 

and, therefore, would probably only be economically feasible for new ship 

construction. Another problem with placing the unit in the ballast tank is 

maintenance, because access would be difficult. Grouping a number of 

smaller ultrasound units together could also solve flow rate problems. 

These ideas seem plausible but research and field trials still need to be 

completed. 
44 

Cost

The cost of an ultrasound unit is high – approximately $250,000 for a 

600 gpm unit. Cleaning and maintenance costs are considered minimal 

since it is estimated that only two hours would be needed to carry out 

these tasks approximately every 12,000 hours. The energy usage could 

range approximately from 28 kW for a 1,000 gpm unit to 206 kW for a 

7350 gpm unit and 840 kW for a 30,000 gpm unit. The cost for power 

generation would depend on the cost of fuel, but it is estimated at 

approximately $.03 per kWh. Based on this rate, estimated monthly 

energy usage cost would range from $605 for a 1,000 gpm unit to $18,144 

for a 30,000 gpm unit (Buchholz et al., 1998). 

Installation of an ultrasound unit might require major modification of 

ballast water system piping. Electrical power and controls would need to 

be wired into the unit and, due to the large amount of power required for 

operation, an extra generator might need to be installed. In some cases, 

non-essential equipment might need to be taken off-line when the 

ultrasound unit is being used. 

Magnetic Treatment 

Description

This treatment involves the application of a strong magnetic field to pipes 

systems. The technology has been primarily used for treatment of scale 

and minerals within a piping system or for the treatment of boiler feed 

water. The magnetic field created by the system polarizes hard water 

particles (Calcium Carbonate), making them less prone to settle or attach 

themselves to piping surfaces. The technology has also been applied for 

the elimination of microbes that are found within fuel oils and more 

recently to purify water. A typical magnetic system consists of a magnet 

or electromagnet attached to the piping system. These units can be 

compact and would require little or no energy to operate. Preliminary 

results from industrial and commercial research suggest that a magnetic 

field can also be used to control such aquatic organisms as Zebra mussels 

by causing tissue degeneration associated with the gill and other structures 

specialized for gas exchange and feeding (Barnes et al., 1998). 

Safety

One safety concern associated with electromagnetic treatment systems is 

the application of electric power to operate the system. Different 

manufacturers use different voltage, ranging from 120 volts for a small 

system to 230 volts or more. Typically, marine electrical systems are 

insulated and grounded, and considered safe, which would prevent the 

threat of fire in an enclosed space that might have flammable gases. 
45 

Biological Effectiveness

The effect of magnetic treatment on organisms would vary with the size 

and type of organism. When exposed to single cell bacteria it is very 

effective. Studies from a magnetic fuel cleaning system indicate near 

100 percent destruction of microbial organisms and 97 percent kill of 

fungi. Strong magnetic forces interfere with organism pH levels, which in 

turn supports the cell’s organelles and proteins. Magnetic forces also 

interfere with the flow of ions in the cell membrane, resulting in death. 

Yeast and fungi are affected in a similar manner (De-Bug Limited, 2001). 

Although larger organisms are more resistant to this treatment, damage 

can be caused to the tips of exposed surface areas such as fins and gills 

and reproduction. Zebra mussels subjected to magnetic treatment over the 

course of 78 days displayed aberrations in gill tissue suggesting the 

mussels are affected when exposed to magnetically treated water (Barnes 

et al., 1998). 

Environmental Acceptability

The effects of magnetic treatment are few, if any. There is a concern 

though that magnetic treatment reduces oxygen saturation levels in treated 

water (Florestano et al., 1996). This reduces corrosion in pipes but could 

pose a potential hazard to marine life in the immediate area where the 

treated water is discharged. 

Status of Technology 

The installation of a magnetic water treatment system on board a vessel 

may be feasible since there are magnetic treatment units currently in use to 

treat marine fuel oil systems. It is possible that, in time, manufacturers 

will offer treatment systems for ballast water. 

The units are typically constructed of stainless steel in order to resist 

corrosion. The units themselves are robust enough for marine operation 

and can be designed to fit within confined ships’ engine spaces. 

The maintenance for these systems is minimal. The units do require 

periodic monitoring to ensure proper operation. Crew training would be 

required because maintenance is necessary after prolonged use. However, 

the application of this technology has not been fully evaluated. The 

preliminary results on the effects of this treatment are by no means clear 

or conclusive. More time is needed to properly test and apply this 

technique to ballast water operations (Federal Technology Alerts, 2001). 

Cost 

Capital and operating costs vary widely, depending on the size of the 

equipment. Installation for a large magnetic unit designed to connect with 

12-inch to 18-inch pipes using flange type fittings could require 
46 

approximately one to four person-days and less than $1,000 in additional 

materials. A non-electric magnetic industrial water softening system has 

been estimated to cost approximately $10,000 to treat 1000 gpm, or 

$10 per gpm. An electromagnetic system would be more expensive. 

Depending on the size, a 1000 gpm treatment unit could cost as much as 

$1,000 per gpm. (Federal Technology Alerts, 2001). This does not take 

into account the special installation and retrofit that would be required on 

a ship’s ballast water system. 

Ozone 

Description

This is another type of oxidizing biocide treatment technology used to 

treat potable and a variety of industrial process water. Ozone (O3 ) is a 

naturally occurring form of activated oxygen produced during lightning 

storm discharges and is continuously occurring in the stratosphere by 

ultraviolet action. Ozone can also be artificially produced by the action of 

high voltage discharge in the presence of air or pure oxygen (O2). Due to 

the fact that the gas breaks down rapidly, users must generate the gas on 

site. The high oxidation potential of ozone increases its reactivity with 

other elements and compounds and achieves high kill rates of fungus, 

bacteria, and viruses. 

An ozone generator requires several different components to operate, 

including a clean oxygen supply and a source of high voltage, typically 

6 to 20 kilovolts of alternating current. Generators have two 

concentrically placed electrodes through which high voltage flows. The 

electrodes are separated by a dielectric discharge gap that contains the 

discharge chamber through which oxygen flows. The incoming oxygen 

molecules are broken down in the electric field, subsequently attaching to 

other free oxygen molecules forming ozone. After generation, the ozone 

is fed into a down-flow contact chamber containing the water to be 

disinfected (U.S. EPA, 1999). 

Safety

Ozone is very reactive and corrosive and requires corrosion resistant 

materials when used. In low concentrations (0.05 ppm) it imparts a sweet 

odor. However, prolonged exposure to high levels (> 100 ppm) can 

produces headaches and nausea. The off gases from the contact chamber 

in an ozonation system must be treated to destroy any remaining ozone 

before release into the atmosphere. In addition, the gas reacts violently 

when combined with ultraviolet waves creating reactive hydroxyl ion 

(U.S. EPA, 1999). 
47 

Biological Effectiveness

Ozone is a very strong oxidant-causing direct oxidation and destruction of 

the cell walls of organisms. The rupture of the cell walls exposes the 

organism to the external environment and cause immediate death to the 

cell (OzonePure, 2001). This is in contrast to chlorine, which kills 

organisms by diffusing into the cell protoplasm, inactivating cell enzymes. 

Ozone levels of 0.4 ppm have been reported to control most vertebrate 

species, unicellular, and some benthic organisms. Control of more 

resistant cysts can be achieved at 10 ppm (Laughton et al., 2001). 

Preliminary results of a recent study of an ozone system installed on the 

Tosina, a 869 foot double-hull American-flag oil tanker, indicate that the 

treatment killed more than 99.9 percent of the bacteria after five hours of 

ozonation and over 90 percent of the zooplankton after ten hours (Cooper, 

2002). 

Environmental Acceptability

Ozone treatment is reported to have no harmful residuals that would need 

to be removed after treatment. In addition, the ozonation process tends to 

elevate the dissolved oxygen concentration of the effluent, eliminating the 

need to re-aerate treated water before it is discharged into receiving 

waters. Due to its oxidative power, ozone can also decompose organic 

and inorganic pollutants in treated water that can easily be separated by 

filtration before discharged. The biggest health concern associated with 

ozone is the possible exposure at high concentration (>100 ppm) in 

enclosed spaces. Natural ozone background concentrations is 

approximately 0.03 ppm (Hughes, 2001). The federal Occupational Safety 

and Health Administration (OSHA) has set ozone exposure limit 

guidelines for industry and recommends short-term exposure limit at no 

more than 0.3 ppm, 0.1 ppm for an 8 hour exposure, and 0.05 ppm for 

24 hours of exposure. 

Status of Technology

There are currently a number of companies manufacturing ozonation 

systems for various wastewater and industrial applications. Only recently 

has this type of system been applied to the treatment of ballast water 

(Cooper, 2002). Ozone generators used in industry are usually very large 

and complicated systems that require a significant cooling water system 

for the generator and an air compressor for the oxygen separator. New 

units are becoming smaller as the technology improves. Some smaller 

ozone generators use air rather than liquid as a cooling medium. One of 

the major engineering problems is to manufacture a system that is small 

enough to fit in confined ship space but still has the capacity to handle the 

large volume of water used in a ballast system. 
48 

Space considerations are very important when a system is to be installed 

on ship. Retrofitting older ships with this type of system could prove 

costly due to the space available for installation and piping 

reconfiguration. 

Cost 

In the past, ozone generators have been very expensive in both capital and 

operation costs. The cost of such units has begun to decrease with the 

advent of new materials, power supplies, high frequency generators, and 

new types of cooling systems. The cost of an ozonation system will 

depend on the manufacturer, the size of the unit, the water treatment 

capacity, and the characteristics of the wastewater being treated. Cost 

estimates for an ozone disinfection system used to disinfect 1 mgd based 

on the wastewater passing through a primary and secondary treatment 

process are $245,000 for an oxygen feed gas and compressor and $800 to 

$1,200 for the destruct unit. 

There are other costs associated with the installation and operation of the 

system. Annual operations and maintenance costs were estimated at 

$12,000 for labor, 90 kW for power and approximately $6,500 for filter 

replacements, compressor oil, and spare parts (U.S. EPA, 1999). 

Pulse Plasma 

Description

Pulse Plasma can be loosely defined as an electrically conducting gas. At 

normal temperatures and pressures gases are not very good conductors 

because the electrons contained within gas atoms can not move in 

response to externally applied magnetic fields. However, through 

ionization some or all the electrons can be removed from their parent 

atom. The gas then becomes a mixture of negative charged electrons and 

positive charged ions and unionized charged particles. Under this 

condition, the electrons and ions are free to move under the action of an 

applied electromagnetic field, and the gas can then conduct electricity. 

Pulse plasma treatment is a relatively new technology, and its application 

to ballast water is untested. The system works on the same principle as a 

spark plug where a voltage of 5000 volts at 25,000 amps is applied 

between two electrodes for approximately 400 microseconds, creating an 

ionization field producing a high-energy plasma arc. 

This high-energy plasma arc produces a pressure shock wave. The shock 

wave kills the target organisms by causing physical damage to the cellular 

matrix either by the sudden recoil of cell tissue or by micro-eddies created 

on the internal cell structure (OCETA, 2001). Currently, the technology is 

undergoing tests for its effectiveness against Zebra mussel colonies in 
49 

intake pipes for onshore industrial facilities. In this application, the pulse 

is directed into a water intake pipe and the pressure wave is contained 

traveling down inside the pipe. 

Safety

The shock wave produced by this technology is powerful and over time 

could lead to materials failure or enhanced corrosion, resulting in damage 

to the piping in a ballast water system. Further studies are needed to fully 

evaluate the effects on a ship’s piping. 

Biological Effectiveness

Pulse plasma is reported to be able to remove aquatic fouling organisms 

such as Zebra mussels, alga colonies, and bacterial growth. At present, 

only one pulse power plasma spark system has been developed for fullscale operation. The system is designed to treat relatively high flows of 

water. This prototype system was tested (Smythe et al., 1999) and was 

reported to have induced Zebra mussel mortality. However, it is not 

known if it will be effective against hardy organisms such as cysts or 

larger aquatic organisms or whether it can be operational onboard ship. 

Environmental Acceptability

Pulse Plasma treatment technology for water treatment application is at an 

experimental stage. Environmental acceptability at this point is unknown 

although it would be expected that treated ballast water could be 

discharged into receiving waters safely. 

Status of Technology

This technology has been well developed on a theoretical and research 

basis. Its reliability and practicality for ship-based use is yet to be proven. 

The shock wave produced is very effective but application aspects aboard 

ship will require further research. The equipment has not been proven in a 

marine environment that is subject to physical stresses such as extreme 

heat, corrosion, lateral, and transverse movement. Land-based systems are 

not subject to such stresses. 

This technology would require training to operate and maintain. 

Equipment malfunctions might be beyond a crew’s ability to repair while 

at sea, which could lead to not having the treatment equipment available 

for extended periods of time. 

Cost 

Estimated costs range between $100,000 to $200,000 not including 

installation. Operation and maintenance are estimated to be approximately 

$150 per hour excluding electric power requirements. Electrode 
50 

replacement after 10,000 hours of operation would cost approximately 

$5,000 (NRC, 1996). 

Other Treatment Options 

The following treatment options have been presented as other possible 

alternatives to treat ballast water. They are described here in a general 

manner based on limited information available. 

Deoxygenation 

Description

This treatment accomplishes the removal of ballast water organisms by 

extracting the dissolved oxygen from ballast water. This can be 

accomplished by either purging the oxygen from the ballast tanks with 

nitrogen through the use of chemical additives or by use of a vacuum 

chamber over time. Nitrogen treatment is reported to be safe with the 

proper equipment and training. The treatment would be partially effective, 

causing substantial mortality of ballast tank organisms that are not adapted 

to low oxygen environments. It may be cost effective because it could 

decrease the rate of corrosion in ballast tanks. Preliminary laboratory 

results showed substantial reduction in the survival rated of polycheate 

worms, green crabs, and the Zebra mussel (Tamburri et al., 2001). 

Preliminary results from a prototype study involving a 72-ton per hour 

high speed ballast water treatment system fitted with a vacuum chamber 

showed an immediate kill of live zooplankton ranging from 50 to 

75 percent and nearly complete reduction within two days of treatment 

(Browning et al., 2001). 

Ballast Tank Coating 

Description

Anti-fouling paints have been commonly used on the bottom of ship hulls 

to prevent marine organisms from attaching. Ballast tank anti-fouling 

coating could be applied to ships during the building stages and reapplied 

while at dry dock for maintenance operations throughout the life of the 

ship. Basically, two types of anti-fouling paints could be used: (1) a nonstick type, silicon-based paint that would prevent organisms from 

attaching to the surface of the tank, and (2) a biocidal anti-fouling paint 

that would release small amounts of biocide at the coating surface to kill 

attaching organisms. Unfortunately, paint coatings could only act on 

benthic organisms, leaving species in water columns unharmed. There are 

also questions regarding the durability of the coatings and how frequently 

reapplication would be needed to maintain an effective level of protection. 

In addition, biocidal coatings would ultimately release residual biocide 
51 

into receiving waters. The NRC (1996) did not consider this type of 

treatment to be suitable because the organisms that would be effectively 

controlled by this treatment method only represent a small portion of the 

total problem. 
52 

Findings and Evaluation of Ballast Water Treatment Alternatives 

This report presents 13 different treatment technologies and procedures in 

five different evaluation considerations. The list of treatment technologies 

and procedures are by no means exhaustive. There are a number of other 

treatment options or different versions of some of the treatment options 

presented here that have not been discussed in this report. The evaluation 

and resulting findings are preliminary in nature because much of the 

information needed to complete a more conclusive assessment of the 

technologies is still being developed and not currently available. 

Nevertheless the information gathered so far may be sufficient to provide 

an idea regarding the status of development and application of the 

treatment options presented. 

Table 6 presents a qualitative summary evaluation of the treatment 

technologies. First and foremost, it is important that in considering 

specific treatment options for application each treatment alternative be 

considered safe, biologically effective, and environmentally acceptable. 

As mentioned previously, the evaluation is based on information gathered 

for each treatment alternative. The different treatment options are rated 

according to the following classifications: 

• Acceptable – Considered to be safe, effective, environmentally 

acceptable or will be safe, effective and environmentally acceptable 

with minor technological modifications and refinements. 

• Partially acceptable – Considered to be partially safe, effective 

or environmentally acceptable. 

• Unacceptable - This rating does not mean that the treatment 

option should not be considered further. It simply means that the 
53 

technology may be considered too costly, or there are uncertainties 

regarding its safety, effectiveness, or environmental acceptability. It 

may also mean that the technology needs more design work, 

development, refinement, and research. 

• Unknown - Treatment technology is currently at the conceptual 

stage. Not enough information is available or gathered at the time this 

report was prepared to make a judgement regarding the specific 

evaluation consideration. 
54 

TABLE 6: PRELIMINARY BALLAST WATER TREATMENT TECHNOLOGY EVALUATION

Treatment Technology Safety Biological 

Effectiveness 

Environmental 

Acceptability 

Uptake/Release Practices 

Onshore Treatment 

Empty and refill exchange (ERE) 

 Flow through exchange (FTE) 

Filtration 

Oxidizing Biocides 

Heat Treatment 

Ultraviolet 

Ultrasound 

Magnetic Fields 

Ozonation 

Pulse Plasma 

Deoxygenation 

Anti-fouling coatings 

 Acceptable Partially acceptable Unacceptable Unknown
55 

Safety 

• Ballast water uptake/release practices are moderately safe because they 

are subject to safety conditions during cargo loading and unloading. 

Ballasting operations may need to be carried out in port to maintain 

ship transverse stability, and to maintain both the clearances under 

cargo loading or cargo discharge facilities and under-keel clearance so 

the vessel remains safely afloat. 

• Both BWE procedures are considered safe, although there appears to 

be still unresolved uncertainties with regard to ERE. ERE procedure 

has been reported to be potentially unsafe because it requires that 

ballast tanks be emptied before they are filled again. This procedure 

has been reported to compromise the stability and maneuverability of 

ships. It has been reported that this is most pronounced in ships larger 

than 40,000 dwt. Ships larger than 40,000 dwt have reported to have 

carried ERE without any perceivable deleterious effects. Hydrostatic 

analyses confirm this observation as long as ERE is not carried out 

during extremely high sea conditions. FTE is considered safe or safer 

because in this method ballast tanks are flushed out and filled in 

simultaneously during the voyage, and consequently the stability of the 

ship is not likely to be compromised. 

• There are specific, unresolved concerns associated with biocide 

treatment. These concerns include handling and storing hazardous 

chemicals onboard as well as residual chemicals left onboard or in the 

ballast tanks after treatment causing corrosion problems. Further tests 

are necessary to evaluate the practicality of application for onboard 

treatment. 

• Safety of heat, ultraviolet, ultrasound, magnetic field, pulse plasma, 

and deoxygenation treatments is unknown because some have not been 

shipboard tested, and there is not enough conclusive information 

available. 

Biological Effectiveness 

• Ballast water uptake/release practices can only be used as an initial 

avoidance strategy to control the uptake and discharge of aquatic 

organisms in specific areas under specific conditions. 

• All BWE procedures were rated unacceptable because, although the 

operation is currently the most accepted practice in use today, it is 

widely recognized to be limited with regard to its effectiveness in 

reducing the discharge of non-indigenous organisms into receiving 

waters. The concept behind exchange procedures is that during a 

voyage nonindigenous organisms are replaced with mid-ocean 

organisms, which are then discharged at the port of destination. Mid-
56 

ocean organisms are assumed to be killed upon being discharged to the 

new environment due to different environmental conditions of the 

receiving waters. At this point there are many uncertainties about the 

effectiveness of the operation. Biological effectiveness has been 

reported to range between 39 and 99 percent. There are currently 

ongoing studies intended to better determine the effectiveness of this 

procedure. In the mean time these practices should only be considered 

as an interim measure until more effective management alternatives 

are developed. 

• Filtration and cyclonic separation was rated moderately acceptable. 

Studies have suggested that these systems could help reduce the intake 

of aquatic organisms into ballast tanks. However, it would be best to 

couple this treatment with a secondary system to ensure that more 

complete extraction of aquatic organisms is accomplished. 

• Some biocides have demonstrated high level of effectiveness under 

laboratory conditions. Preliminary onboard studies have been 

conducted, but there is not enough conclusive information to perform 

an evaluation at this time. 

• Much of the technology necessary to implement heat treatment is 

currently available. Preliminary studies have been carried out on its 

effectiveness, but further evaluation is needed. 

• The effectiveness of UV was rated unknown because there are 

unresolved engineering and design questions associated with the 

installation and operation of the system. In addition, the exposure time 

and intensity of UV application to achieve adequate organism 

inactivation or elimination have not been well defined. The system is 

currently under further evaluation. Ultrasound has shown to achieve a 

high level of biological effectiveness on Zebra mussel veliger, 

nematodes, bacteria, and viruses, but the technology has not been 

tested on a large flow system capable of treating large volumes of 

ballast water onboard ship. 

• Magnetic treatment effects would vary with the type and size of the 

organisms. Studies of fuel cleaning systems have indicated that high 

levels of biological effectiveness have been achieved against microbial 

organisms and fungi. At this time, no magnetic system has been 

developed for treating ballast water. Further tests aboard ship are 

necessary once the system is developed. 

• Ozone treatment is another type of oxidizing biocide capable of 

causing direct oxidation and destruction of the cell walls of organisms. 

Preliminary studies indicate that the treatment is highly effective, but 

further investigation is needed. 
57 

• Studies on pulse plasma technology have indicated that the treatment 

is effective against the Zebra mussel, algae, and bacterial growth. It is 

presently being further tested with Zebra mussels for land-based 

applications. No system has been developed for shipboard testing. 

• Deoxygenation treatment could be effective in killing larval, juvenile 

and adult oxygen consuming organisms but may be less effective on 

taxa adapted to low oxygen environments or with resistant stages such 

as cysts. 

• Anti-fouling coat application inside ballast tanks would probably 

prevent benthic organisms from attaching to the tank’s surfaces but 

would not affect organisms within the water column. 

Environmental Acceptability 

• Both ERE and FTE operations were rated as unacceptable because 

exchange operations result in an unpredictable combination of killing, 

removing, and adding organisms to a receiving aquatic environment. 

During exchange operations, some organisms in the original ballast 

water would be removed from the tanks as the water is replaced, but 

others could remain passively in the ballast tanks because of 

incomplete exchange process. When a ship arrives to the port of 

destination, the mix of mid-ocean as well as original estuarine 

organisms from the port of origin could be discharged during 

deballasting operations. The organisms that are discharged with 

ballast water are assumed killed by a change in salinity or other 

environmental factors. This assumption may not be valid because 

ballast tanks contain a wide range of organisms with a wide range of 

environmental tolerances. Consequently, the likelihood of any midocean organism being able to tolerate coastal, estuarine, and 

freshwater environments when discharged with ballast water is not 

known. 

• Biocide application to inactivate aquatic organisms in ballast water 

must be researched very carefully not only to determine effectiveness 

but to ensure that residual chemicals after treatment is neutralized or 

degraded into harmless byproducts before treated ballast water is 

discharged into receiving waters. Preliminary studies with specific 

biocides are promising. Any program designed to include application 

of any biocide should include a residual breakdown study phase to 

ensure active chemical ingredients are broken down into harmless 

compounds before being discharged into the environment. 

• Ultraviolet, ultrasound, magnetic field, ozonation, and pulse plasma 

treatment technology are experimental, and their environmental 

acceptability is unknown. 
58 

• Deoxygenation technology can be accomplished through various 

ways; one of which binds available oxygen through the use of 

chemical additives. This procedure is also subject to the same 

constraints as biocides because the treatment could produce hydrogen 

sulfide when a significant amount of organic matter is present. This 

could create problems onboard ship as well as when treated ballast 

water is discharged into receiving water. Another concern would be 

the possible danger to native estuarine organisms when ballast water 

containing low oxygen is discharged to receiving water. 

• Anti-fouling coatings, as with biocides, could ultimately release 

residual biocide into receiving waters. 

Cost 

Capital cost estimates for each treatment technology vary widely 

according to ship types and extent of modifications needed to install a 

specific system. Some estimates are conceptual, based on projected study 

costs. There are a number of cost estimates in the literature, but many are 

several years old and do not reflect current cost. Capital cost estimates for 

a shore-based treatment facility are substantially higher when compared 

with other types of treatment systems. Operation and maintenance cost 

also varies substantially, depending on power requirements or other 

peripheral equipment needed to operate the system. 

Table 7 presents a rough estimate of capital costs and the costs to treat 

ballast water using the different options. Whenever possible, all values 

have been transformed into one general unit of measure in an effort to 

present all costs in a uniform manner. Capital costs are based on 

equipment cost estimates. Whenever available, treatment cost per MT of 

ballast water is also presented. 
59 

TABLE 7: CAPITAL AND TREATMENT COST ESTIMATES TO TREAT BALLAST WATER

Treatment Technology Capital Cost Treatment Cost 

Ballast Water Uptake/Release 

Practices 

No capital cost. No Operating and Maintenance cost. 

 

Onshore Treatment $8 million – $50 million depending on 

the port. Further site specific work is 

needed. 

Annual O&M $150,000 – $223,000/ year 

$1.50 to $8.29 /MT. 

ERE Depends on extent of piping 

modifications needed. 

 $.02-$.035 /MT. 

FTE Depends on extent of piping 

modifications needed. 

$.06-$.08 /MT. 

Filtration $40,000. Unknown. 

Biocides $400,000 - $800,000 for electrolytic 

system. $1,600 for dosing systems or 

negligible if a service company applies 

the biocide. 

For some non-oxidizing biocides $.16- 

$.20 /MT. Less for oxidizing biocides. 

Heat $28,000 – $45,000 for heat exchangers. 

$60,000 – $600,000 for boiler systems 

not including piping system 

modifications. 

$.03 /MT. 

UV $10,000-$545,000 excluding installation. 

$140,000 for a cyclonic separation and 

UV system (cost estimates estimated). 

Undetermined but there are several 

combined systems presently being tested. 

Ultrasound $500,000 estimated cost for two 600-gpm 

systems. 

At $.03 /kWh for 30,000 gpm unit power 

consumption, approximately 

$18,144/month. 

Magnetic For a scale and hardness control system: 

1. Non-electric – to treat 1000 gpm, 

$10,000 excluding installation, 

2. electromagnetic - 1000 gpm, up to 

$1,000,000. 

Unknown for onboard ship applications. 

Ozonation Oxygen gas unit and compressor system: 

$245,000, destruct unit $800 to $1,200. 

$1,200, approximately 90 kw for power 

plus $6,500 for filter replacement and etc. 

Pulse Plasma $100,000 to $200,000 not including 

installation. 

$150/hour excluding cost for electrical 

power. 

Deoxygenation Unknown. Unknown. 

Anti-fouling coatings Unknown. Unknown. 
60 

Conclusions 

1. At present there is not enough conclusive information to recommend a 

single treatment option or a combination of treatment options for 

certification in California. 

Most of the treatment technologies discussed in this report are under 

development or potentially available in the future. Some have been 

tested under laboratory conditions and only a few have undergone fullscale testing aboard ship. There are many fundamental scientific and 

engineering questions that need to be answered. Technologies such as 

filtration, biocides, heat, UV, ultrasound, magnetic, and ozone 

treatment either need further testing and refinement or are considered 

effective but systems have not as yet been designed and tested for 

shipboard application. 

2. Preliminary evaluation indicates that most of the technologies are 

either developing or in the conceptual stage. 

An initial assessment of the status of various treatment options using 

the information collected is presented in Table 8. Each treatment 

technology or procedure has been classified according to the following 

categories: 

• Established – Technology or practice whose quality has been 

demonstrated through laboratory and shipboard tests. 

• Developing – Technology or practice whose capabilities need to be 

brought to a more advanced and effective state. 
61 

• Emerging – New technology or practice in the conceptual stage, in 

the process of being developed, or not tested yet. 

TABLE 8: INITIAL ASSESSMENT OF THE STATUS OF THE TREATMENT OPTIONS

Treatment Option Category 

Ballast Water Uptake/Release Practices Established 

BWE Established 

Filtration Developing 

Biocides Developing 

Heat Developing 

Ultraviolet Developing 

Ultrasound Emerging 

Magnetic Emerging 

Ozonation Developing 

Pulse Plasma Emerging 

Deoxygenation Emerging 

Anti-fouling coatings Emerging 

3. Although BWE is considered an established practice, it should not be 

used to determine the biological effectiveness of technologies because 

its effectiveness has not been established and varies widely. 

California Public Resources Code section 71204(a)(3) requires that 

any alternative method of ballast water management be at least as 

effective as BWE in removing or killing nonindigenous organisms. 

Ballast water exchange procedures (ERE or FTE) have been 

established for some time and are recommended under IMO 

guidelines. However, there are many uncertainties associated with 

BWE procedures regarding the effectiveness and locations where 

exchange might be carried out. At the First International Ballast Water 

Treatment Research and Development Symposium and Standard 
62 

Workshop held on March 2001 at IMO headquarters in London, it was 

concluded that it was not appropriate to use equivalency to BWE as a 

standard for evaluating and approving new BWT technologies. BWE 

should be used as a temporary measure only to be replaced by a safer 

and more effective treatment alternative in the future. 

Both BWE and BWT are intended to reduce the concentration of 

nonindigenous organisms in ballast water discharges to receiving 

waters. However, while all of the proposed technologies kill or 

remove organisms, BWE results in an unpredictable combination of 

killing, removing, and adding organisms. It is difficult to 

meaningfully compare BWE replacement results with BWT killing 

results because BWE assumes (1) a kill ratio effectiveness based on a 

volumetric exchange of ballast water, and (2) the likelihood of those 

organisms that are replaced and discharged to tolerate coastal, 

estuarine, and freshwater environments (Ballast Water News, 

GloBallast, 2001). 

4. Regardless of technology or methods used, the state should continue to 

require the use of ballast water uptake/release procedures as primary 

avoidance strategies whenever possible. 

These practices are presently recommended by IMO and required 

under California Public Resources Code section 71204 as long as ship 

safety is not compromised. However, the procedures should only 

serve as primary avoidance strategies to be used in combination with 

other treatment methods or technologies. 

5. Onshore treatment alternatives may be possible for smaller port 

facilities with a limited number of dedicated ship visits, or as an option 

for older vessels that are unable to retrofit because they are either 

nearing the end of their service life or it would be too costly to retrofit. 

This treatment alternative would require that ballast water be 

transferred to an onshore facility for treatment. Onshore treatment 

could be very effective in eliminating introduced species because the 

treatment process would be carried out in a full-scale treatment plant 

designed and fully capable to treat and dispose of ballast water. In 

some ports enough shore space could be available to establish shorebased facilities, or treatment could be accomplished in already existing 

facilities. It would be technically feasible to retrofit vessels and 

berths, develop transportation system to collect ballast from ships, 

build onshore storage tanks and treatment facilities, and dispose of the 

treated water in an environmentally safe manner. 
63 

Recommendation 

As stated in the Conclusions, there is not enough conclusive 

information to recommend a single treatment option or a combination 

of treatment options for certification in the state. Further research and 

onboard testing are necessary to determine the effectiveness and 

feasibility of various technologies. 

The increasing awareness of the problem of discharged ballast water, 

the stated limitations of BWE, and the lack of proven treatment 

alternatives to address the problem have caused various regulatory 

jurisdictions to adopt regulations requiring ballast water management. 

This has caused concerns in the shipping industry because the 

regulations adopted by different jurisdictions have oftentimes resulted 

in different and disparate responses to manage the ballast water 

problem. 

There is no doubt that there is a strong demand for environmentally 

sound and effective ballast water treatment technologies. The shipping 

industry seems very interested in advancing these efforts and 

developing treatment alternatives that would be generally acceptable 

across those jurisdictional boundaries. However, the industry is 

understandably reluctant to fully invest large amounts of capital on 

partially tested, largely unproven technologies unless there are 

assurances that the technology will likely meet regulatory requirements 

now and for the reasonably foreseeable future. 
64 

In many cases, research efforts to test and establish treatment 

alternatives have been initiated by private companies that lack 

experience in dealing with technological effectiveness, environmental 

soundness, vessel and crew safety, engineering integration, operational 

and maintenance requirements, and cost. These fundamental scientific, 

engineering, and operational issues need to be addressed for each of the 

proposed systems. 

The most efficient and practical way to assure that these fundamental 

scientific and engineering issues are appropriately addressed would be 

through the implementation of a well-designed research, development 

and certification program with built-in incentives for the shipping 

industry to promote the development of treatment options. Since the 

ballast water issue is an international concern, it should be addressed by 

the federal government in coordination with the state and the shipping 

industry. 

Currently, SLC is the lead state agency working with USCG on ballast 

water management issues. The two agencies are implementing a joint 

detailed procedure to evaluate experimental or prototype ballast water 

treatment systems with demonstrated potential for effective destruction 

of nonindigenous aquatic organisms. This joint program approves 

installation and testing of experimental treatment systems and grants 

conditional approval for use in-lieu of BWE. The approval is granted 

for a determined period of time regardless of regulatory requirements 

for treatment that might be promulgated during the testing and 

evaluation period. The program requires demonstration tests contingent 

upon the implementation of a rigorous experimental study deemed 

appropriate by an independent panel of scientists. Participation in the 

advance approval program requires compliance with various review 

steps. The ship owner, operator, manufacturer, or developer is required 

to submit a study plan, accompanied by supporting documentation 

including environmental compliance, small-scale demonstration 

experiments, and a letter of commitment stating the intent to carry out 

all components of the study plan for which they are responsible. The 

eventual result of this program will provide the shipping industry a set 

of scientifically tested and certified treatment technologies that will 

comply with any international or local regulation. 

Additional efforts that could be included in this joint program are: 

• Focused research and engineering studies that would guide the 

development of promising treatment alternatives towards a working 

prototype. The research and development would incorporate the 

specific constraints and requirements of defined classes of vessels. 

This could include land-based testing where the technologies are 

evaluated in an environmentally safe location that would facilitate 
65 

objective testing using scientifically designed protocols for 

standardized land-based tests under controlled conditions. 

• Shipboard installation and testing that would guide the research and 

development of a prototype system toward application onboard 

ship. This would include fitting and refining prototypes through 

shipboard trials over extended periods and under a broad range of 

operating conditions and biological testing to evaluate the 

effectiveness of the system. 

• Tested technologies that are proven effective would subsequently 

be certified as suitable for use and implemented throughout the 

maritime industry. 

 
66 

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