Land-Based Evaluations of the 

Severn Trent De Nora BalPureTM BP-1000

Ballast Water Management System

Maritime(Environmental(Resource(Center

June 2010

c/o Chesapeake Biological Laboratory

University of Maryland Center for Environmental Science

PO Box 38, Solomons, Maryland 20688, USA

UMCES Technical Report Series: Ref. No. [UMCES]CBL 10-015
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Notice

The objective of this Maritime Environmental Resource Center (MERC) evaluation was 

to provide shipping lines, classification societies, regulators, and flag states with an independent 

and credible assessment of treatment performance under realistic conditions. Therefore, the 

ballast water treatment system was tested in accordance with the International Maritime 

Organization (IMO) International Convention for the Control and Management of Ships’ Ballast 

Water and Sediment (2004), Resolution MEPC.174(58) Guidelines for Approval of Ballast 

Water Management Systems (G8) and Resolution MEPC.169(57) Procedure for Approval of 

Ballast Water Management Systems That Make Use of Active Substances (G9). The evaluation 

was conducted under specific, predetermined, agreed-upon protocols, criteria, and quality 

assurance procedures to assess the treatment system's performance.

MERC does not label or list technologies as acceptable or unacceptable but will present 

the results in an objective way that can be used to determine regulatory compliance by 

appropriate administrations, agencies or certification societies. Subsequent data on the 

technology's performance characteristics is presented to allow for comparison with the IMO

Convention discharge standards, Regulation D-2, Ballast Water Performance Standard. 

MERC and the MERC Advisory Board do not provide certification for technologies, or 

certify that a technology will always operate as demonstrated. Additionally, no expressed or 

implied guarantee is provided as to the performance of the technology, or that a technology will 

always operate at the levels verified. MERC does guarantee the levels verified during the 

evaluation under the conditions, circumstances, and operations encountered as fully independent 

and credible. 

This report has been reviewed by the MERC Advisory Board and provided to Severn 

Trent De Nora and MERC funding agencies prior to public release. Mention of trade names or 

commercial products does not constitute endorsement or recommendation by MERC.

Questions and comments should be directed to Dr. Mario Tamburri, tamburri@umces.edu.
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Table of Contents

Page No.

1. MERC Background and Objectives...............................................................................1

2. Description of the Severn Trent De Nora Ballast Water Management System.............1

3. Summary of IMO Standards..........................................................................................2

4. Summary of Test Protocols............................................................................................2

5. Summary of Results.......................................................................................................4

6. Results Trial 1................................................................................................................6

7. Results Trial 2................................................................................................................8

8. Results Trial 3..............................................................................................................11

9. Results Trial 4..............................................................................................................14

10. Results Trial 5..............................................................................................................17

11. Chemical Analysis of Discharge..................................................................................20

12. Acknowledgements......................................................................................................21

Appendix A. Vendor Interpretation .........................................................................................22

Note: Detailed Test Plan, Protocols and Standard Operating Procedures (SOPs) can be 

downloaded from www.maritime-enviro.org.
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1. MERC Background and Objectives

The Maritime Environmental Resource Center (MERC) is a State of Maryland initiative 

that provides test facilities, information, and decision tools to address key environmental issues 

facing the international maritime industry. The Center’s primary focus is to evaluate the 

mechanical and biological efficacy, associated costs, and logistical aspects of ballast water 

treatment systems and the economic impacts of ballast water regulations and management 

approaches. A full description of MERC’s structure, products, and services can be found at 

www.maritime-enviro.org.

To address the need for effective, safe, and reliable ballast water treatment systems to 

prevent the introduction of non-native species, MERC has developed as a partnership between 

the Maryland Port Administration (MPA), Chesapeake Biological Laboratory/ University of 

Maryland Center for Environmental Science (CBL/UMCES), U.S. Maritime Administration 

(MARAD), Smithsonian Environmental Research Center (SERC), and University of Maryland 

(UMD) to provide independent performance testing and to help facilitate the transition of new 

treatment technologies to shipboard implementation and operations. 

This report describes the MERC evaluation of the Severn Trent De Nora BalPureTM BP1000 Ballast Water Management System through objective and quality assured land-based 

testing (dockside at a flow rate of 200m3

/hr). The goal of this evaluation was to provide shipping 

lines, regulators, classification societies, and flag states with an independent and credible 

assessment of treatment performance under realistic conditions. Therefore, the data and 

information on performance characteristics covers legitimate information to meet the 

evaluation's objective, and performance is presented in a way to allow for comparison against the 

International Maritime Organization (IMO) International Convention for the Control and 

Management of Ships' Ballast Water and Sediments (2004), Regulation D-2 Ballast Water 

Performance Standard.

2. Description of the Severn Trent De Nora (STDN) Ballast Water Management System

The STDN Ballast Water Treatment System (BWTS) applies established chlorination 

technology to oxidize and disinfect aquatic invasive species. The BALPURE® BWTS is an 

electrolytic process for the on-site generation of dilute hypochlorite on demand without storage 

during the ballasting operation and the neutralization of residual oxidants during the deballasting operation. Sodium hypochlorite is generated by means of electrolysis of seawater. In 

this process, seawater flows through the electrolytic cells in a ratio of 1 part for every 100 parts 

of ballast water. The system can operate effectively in brackish water to 15 PSU. Because the 

amount of seawater required to effectively treat ballast water is small, even fresh water ballast 

can be treated by BALPURE® BWT with supplemental salt or stored seawater in designated 

ballast tanks such as aft peak tanks. The current passing through the seawater causes the salt 

(NaCl) and water (H2O) to form sodium hypochlorite (NaOCl) and hydrogen (H2) as a secondary 

by-product. Hypochlorite solution and Hydrogen are produced and separated immediately upon 

exit from the electrolytic cells. The weak hypochlorite solution (1 g/L) is injected back into the 

ballast stream. Hydrogen that is separated from the hypochlorite is immediately diluted to less 

than 1% hydrogen by forced air blowers and discharged to a safe location. The hypochlorite is 
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generated automatically on demand and is matched to the ballast flow rate and the oxidant 

demand of the ballast water. Initial oxidant concentration is dosed at 1.5 times the TOC 

concentration, which remains effective for several days. To minimize potential regrowth of 

(micro) organisms a background level of chlorine is maintained (1 mg/L) until discharge. To 

eliminate the release of chlorine, sodium sulfite or bisulfite is added prior to discharge. 

For this land-based test, the water is filtered through a 40 micron BallastSafeTM BSFc 

Automatic Electric Filter, Model BSFc-V-1.6 prior to treatment. The sintered stainless steel 

screen technology enables it to remove zooplankton. BallastSafe’s filter features continuous 

cleaning of large volumes of dirt during ballasting without interruption, and a reversible screw 

system for smooth, reliable and rapid cleaning of the entire screen surface. 

 All test facility equipment and instrumentation was operated by MERC personnel. The 

ballast water treatment system was operated by STDN.

3. Summary of IMO Standards

This evaluation was designed to determine if the BalPure® BWMS could meet IMO D2 

standards in accordance with both the IMO Guidelines for Approval of Ballast Water 

Management Systems (G8) and the Procedure for Approval of Ballast Water Management 

Systems that make use of Active Substances (G9). The IMO Convention performance standard 

states that ships must discharge:

1) Less than 10 viable organisms per m3

, greater than or equal to 50 μm in minimum 

dimension;

2) Less than 10 viable organisms per ml, less than 50 μm in minimum dimension and greater 

than or equal to 10 μm in minimum dimension and

3) Less than the following concentrations of indicator microbes, as a human health standard:

1. Toxigenic Vibrio cholerae (serogroups O1 and O139), less than 1 colony forming unit 

(cfu) per 100 ml 

2. Escherichia coli, less than 250 cfu per 100 ml;

3. Intestinal Enterococci, less than 100 cfu per 100 ml.

4. Summary of Test Protocols

The following is a brief summary of the testing approach and methods. For complete 

details on protocols, data management, and quality control / quality assurance procedures for this 

MERC evaluation, please refer to the Test Plan for the Performance Evaluation of the Severn 

Trent De Nora BalPureTM BP-1000 Ballast Water Management System (August 2009), available 

for download at www.maritime-enviro.org.

The protocols described below are based upon the IMO G8/G9 guidelines and the U.S. 

Coast Guard supported ETV protocols under development. Any deviation from IMO G8/G9

guidelines or draft ETV protocols were explained and justified in the Test Plan. MERC 

evaluated the biological efficacy of the STDN ballast water treatment system onboard the U.S. 

Maritime Administration (MARAD) Ro-Ro vessel MV Cape Washington while docked in the 

Port of Baltimore. The ballast system on MV Cape Washington was modified to allow for water 

at a flow rate of 400m3/hr to be split equally at flow rates of 200 m3/hr. Just before this split,

challenge condition concentrations of total suspended solids (TSS) and particulate organic 

carbon (POC) were augmented by injecting a concentrated slurry of Arizona test dust and humic 
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acid (developed and validated by the Naval Research Laboratory, Key West, Florida). The water 

was then delivered simultaneously to either a “control” (untreated) ballast tank or a “treated” 

(passing first through the STDN system) ballast tank. These two tanks on the MV Cape

Washington were used for the required holding time of five days and were essentially identical in 

size and structure. Each tank was filled to approximately 250 m3 for each test trial.

Temperature, salinity, dissolved oxygen, chlorophyll fluorescence, turbidity and pH were 

measured every 15 minutes during the test trials by two identical multi-parameter probes placed, 

one each, into the control and test tanks. Initial inline samples of ballast water during the filling 

of the control and test tanks were collected, filtered, and analyzed (using USEPA methods) for 

the water quality parameters of particulate organic carbon (POC), dissolved organic carbon 

(DOC) and total suspended solids (TSS) by the CBL/UMCES Nutrient Analytical Services 

Laboratory (NASL).

A total of 10 identical 1.1 m3 conical bottom mesocosms were also used for controlled 

sampling during each trial. Using the mesocosms, five sequential, time-integrated, continuous 

samples were taken during: (A) initial filling of tanks, just prior to the split of control and treated 

water (T0 Control), (B) initial filling of test tank, just downstream of the BALPURE system 

during filling of test tank (T0 Treated), (C) during discharge of control water after a five-day 

holding time (TF Control), and (D) during discharge of treated water after a five-day holding 

time (TF Treated). 

Immediately after filling, 1.0 m3 of water in each mesocosm was filtered through a 35 μm 

plankton net to concentrate the zooplankton for qualitative and quantitative analyses under a 

dissecting microscope. The proportion and total concentration of live versus dead organisms was 

determined using standard movement and response-to-stimuli techniques within one hour of 

collecting the individual samples. Zooplankton samples were also fixed and returned to the 

laboratory for additional taxonomic evaluations. 

Ten liters of well-mixed, but unfiltered, water from each mesocosm were also collected 

immediately after filling, to determine concentrations of organisms in the 10 to 50 micron size 

class using four distinct methods: (A) One sub-sample was fixed with standard Lugol’s solution 

to determine total cell abundances under an inverted compound microscope using grid settlement 

columns and phase contrast lighting. (B) A second sub-sample was stained using CMFDA (5-

chloromethylfluorescein diacetate) as a selective live/viable indicator. Stained sub-samples were 

incubated and observed on a Sedgewick Rafter slide using a Leitz Laborlux S modified for 

epifluorescence. (C) A third sub-sample was filtered and frozen until analysis of total and active 

chlorophyll-a by the NASL. (D) Finally, a fourth sub-sample was used to determine chlorophylla levels after allowed to regrow under favorable conditions. An increase in chlorophyll, or 

positive regrowth, indicates that viable phytoplankton were in the samples, whereas chlorophyll 

levels at or below detection limits of the laboratory analytical method suggests that there was no 

viable phytoplankton. 

Additional subsamples of unfiltered water were also collected from each mesocosm to 

determine concentrations of total heterotrophic bacteria and three specific indicator pathogens, E. 

coli, intestinal Enterococci, and toxigenic Vibrio cholerae. Total heterotrophic bacteria were 

enumerated by spread plate method using NWRI agar. The presence and abundance of intestinal 

Enterococci was determined using a commercially available chromogenic substrate method. 

Culturable E. coli concentrations were determined using a standard USEPA method: membrane 

filtration on modified mTEC agar. Abundances of total and toxigenic V. cholerae were 

calculated by filtration and selection on TCBS agar and enumerated using a species-specific 
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RNA colony blot and ctxA DNA colony blot hybridization. Viable toxigenic V. cholerae was 

assayed with a commercial DFA kit specific for serogroup O1 using monoclonal antibodies 

tagged with fluorescein isothiocyanate.

To evaluate the toxicity of treated water at the completion of each trial, samples from 

each mesocosm were collected and tested for acute and chronic toxicity, and for total residual 

chlorine. Filter “backflush” (retenate/filtrate during initial treatment of water) was also tested for 

total residual chlorine. The toxicity protocols and species used were consistent with the USEPA 

methods for Whole Effluent Toxicity (WET). The algal species tested was Isochrysis galbana, 

the fish species was the Sheepshead minnow (Cyprinodon variegatus) while the invertebrate 

species was the Mysid shrimp (Americamysis bahia). A chlorine concentration in samples was 

analyzed immediately upon collection to avoid potential loss of oxidant with time. The Standard 

Methods for the Examination of Water and Wastewater Low-Level Amperometric Titration

method 4500-Cl D and DPD Colorimetric method 4500-Cl G were used to measure Total 

Residual Oxidants (TRO) and Total Residual Chlorine (TRC). A Fischer and Porter amperometric 

titrator was also used for amperometric measurements.

5. Summary of Results

Biological Performance - The Severn Trent De Nora BALPURE Ballast Water 

Management System dramatically reduced the numbers of live organisms in ballast water during 

MERC land-based testing in the Port of Baltimore. For all biological categories, the treatment 

system consistently met IMO D2 discharge standards.

Discharge Toxicity - Treated ballast water upon discharge was not chronically toxic to 

either mysid shrimp or sheepshead minnows for any of the trials conducted. All five of these 

samples, however, were chronically toxic to the marine algal species Isochrysis galbana. 

Additional testing of several dilutions of the treated ballast water was conducted on the last three 

samples (STDN-03 through -05). EC50’s, measured as a reduction in growth, were found at 

22%, 42% and 53% for STDN 03, STDN-04 and STDN-05 respectively. 

Additional toxicity testing has revealed that under certain circumstances dechlorinated 

estuarine water remains toxic to some types of algae. The continued toxicity of dechlorinated 

water is species specific with several golden brown algal species (Isochrysis galbana and 

Pavlova lutheri) exhibiting decreased growth after TRO is at or below detection (DPD method). 

In contrast, similarly treated water was non toxic to the diatom Phaeodactylum tricornutum. 

Toxicity was found in samples that were chlorinated by either electrochlorination or sodium 

hypochlorite addition; and aged for five days.

Toxicity in high initial TRO samples was found after dechlorination with one of two 

sulfur-based reducing compounds, sodium thiosulfate or sodium bisulfite. Neither of these 

reducing compounds alone was found to be toxic at relevant concentrations with NOECs of 100 

and 200 mg/l for sodium thiosulfate and sodium bisulfite, respectively. Additional algal toxicity 

tests are being conducted to investigate the cause, as well as the extent, of toxicity caused by 

dechlorinated water. Results of this investigation are being submitted to a peer-reviewed journal 

for publication.

Chemical Analysis of Discharge – Detailed chemical analyses of various consitients (e.g., 

chloroform, bromoform, trichloroacetic acid, etc.) of treated water upon discharge were 

conducted by Analytical Laboratory Services, Inc. (www.analyticallab.com). Summary of 

reuslts can be found in Appendix B.
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Mechanical Performance - The BALPURE system itself experienced no mechanical 

failures during formal test trials.

QA/QC - Finally, the MERC Quality Control and Quality Assurance plan was completed 

as described in the Test Plan. In summary, there were no adverse findings or problems requiring 

corrective action in any of the audits. The testing, sampling, analyses and data handling for this 

evaluation met or exceeded MERC test requirements. 

* Additional datasets (e.g., in tank values for temperature, salinity, dissolved oxygen, etc., every 

15 minutes during hold time) are available upon request.
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6. Results Trial 1 (STDN-CAL): 15-20 October 2009

Physical Parameters

TSS mg/l DOC mg/l POC mg/l

T0 Initial Ave StDev Ave StDev Ave StDev

Conditions 20.6 4.1 3.96 0.31 1.997 0.271

Temp oC Salinity psu Dis. Oxygen mg/l Turbidity NTU

Ave StDev Ave StDev Ave StDev Ave StDev

T0 Control 16.97 0.02 13.26 0.01 7.11 0.06 8.16 0.86

T0 Treated 17.10 0.01 13.21 0.01 7.74 0.09 9.75 0.63

TF Control 16.24 0.02 13.57 0.00 7.09 0.17 1.21 0.09

TF Treated 16.27 0.01 13.36 0.00 8.31 0.01 4.20 0.14

Live Organisms > 50 μm

T0 Ave #/m3 T0 StDev #/m3 TF Ave #/m3 TF StDev #/m3

Control 60,000 11,250 72,000 3,000

Treated ND ND 1.4 1.7

* Taxa listed in order of abundance.

Live Organisms 10 - 50 μm 

Vital Stain Results - It is important to note that the specific approach used underestimates

the abundances of live organisms in this size class because it has been found that not all live 

organisms reliably take up the CMFDA stain. 

T0 Ave #/ml T0 StDev #/ml TF Ave #/ml TF StDev #/ml

Control 258 50.6 4 2.4

Treatment 0 0 0 0

*TF Control *TF Treated

Spionid polychaete Rotifera

Copepod nauplii Spionid polychaete

Rotifera

Calanoida (Acartia sp.)

Cirripedia nauplii

Turbellaria

Dominant species Type Other

Skeletonema costatum Diatom Chain-forming

Thalassiosira sp. Diatom Chain-forming

Oxyrrhis marina Dinoflagellate
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Active Chlorophyll-a - Chlorophyll is used as ancillary data and as a general

presence/absence indicator of viable photosynthetic organism (MDL = 0.56 μg/l).

T0 Ave μg/l T0 StDev μg/l TF Ave μg/l TF StDev μg/l

Control 6.27 0.47 0.88 0.05

Treated 0.56 0.00 0.56 0.00

Regrowth Control 2.61 1.59

Regrowth Treated 0.56 0.00

Live Microbes (cfu = colony forming units)

E. coli T0 Ave 

cfu/100ml

T0 StDev 

cfu/100ml

TF Ave 

cfu/100ml

TF StDev 

cfu/100ml

Control 13.6 4.93 0.2 0.45

Treated 0 0 0 0

Enterococci T0 Ave 

cfu/100ml

T0 StDev 

cfu/100ml

TF Ave 

cfu/100ml

TF StDev 

cfu/100ml

Control 11.28 3.05 12.08 5.16

Treated 0 0 0 0

V. cholerae – No detectable culturable toxigenic Vibrio cholerae were detected in any 

samples during any of the trials.

Heterotrophic 

Bacteria 

T0 Ave 

cfu/100ml

T0 StDev 

cfu/100ml

TF Ave 

cfu/100ml

TF StDev 

cfu/100ml

Control 547 93.24 613 237.51

Treated 0.9 0.78 1.2 2.45

Discharge Toxicity

Residual Chlorine Analysis - Levels of residual chlorine (or total residual oxidants -

TRO) were at or below the method detection limit (MDL) of 0.02 ppm in all TF treated samples. 

Acute Toxicity - There were no statistically significant survival effects in any test for 

either acutely tested species (Mysid shrimp or Sheepshead minnows). 

Chronic Toxicity - Results showed that ballast water discharge was not chronically toxic 

to either mysids or sheepshead minnows. All samples, however, were chronically toxic to the 

marine algal species Isochrysis galbana with a statistically significant inhibition in growth in 

treated ballast discharge compared to controls (see details under Summary of Results on page 4).
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7. Results Trial 2 (STDN-01): 22 – 27 October 2009

Physical Parameters

TSS mg/l DOC mg/l POC mg/l

T0 Initial Ave StDev Ave StDev Ave StDev

Conditions 28.7 5.1 3.98 0.14 2.912 0.163

Temp oC Salinity psu Dis. Oxygen mg/l Turbidity NTU

Ave StDev Ave StDev Ave StDev Ave StDev

T0 Control 16.00 0.00 12.14 0.01 8.48 0.04 9.70 0.85

T0 Treated 16.02 0.00 12.17 0.01 8.59 0.05 8.92 0.64

TF Control 15.86 0.01 12.14 0.01 7.34 0.04 1.99 0.12

TF Treated 15.85 0.00 12.23 0.00 8.63 0.02 3.46 0.10

Live Organisms > 50 μm

T0 Ave #/m3 T0 StDev #/m3 TF Ave #/m3 TF StDev #/m3

Control 70,000 5,625 30,000 1,500

Treated No data 0.2 0.4

* Taxa listed in order of abundance.

Live Organisms 10 - 50 μm 

Vital Stain Results - It is important to note that the specific approach used underestimates 

the abundances of live organisms in this size class because it has been found that not all live 

organisms reliably take up the CMFDA stain. 

T0 Ave #/ml T0 StDev #/ml TF Ave #/ml TF StDev #/ml

Control 267 14.8 38 25.6

Treatment 0 0 0 0

Lugol’s Total Counts - This approach commonly overestimates the abundances of live 

organisms in this size class because all individuals in fixed samples are counted unless obviously 

dead (significant damage to organism). Lugol’s staining alone does not distinguish live from 

dead cells.

*TF Control *TF Treated

Copepoda nauplii Harpacticoida

Spionid polychaete

Calanoida (Acartia sp.)

Cyclopoida (Oithona sp.)

Harpacticoida

Nematoda
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T0 Ave #/ml T0 StDev #/ml TF Ave #/ml TF StDev #/ml

Control Diatom 980 90

1,133 60

Treated Diatom 758 104 15

Dinoflagellate 250 19 12

Note: 2,300/ml = Average counts for T-Final-Treated, for picoplankton <10μm.

Active Chlorophyll-a - Chlorophyll is used as ancillary data and as a general 

presence/absence indicator of viable photosynthetic organisms (MDL = 0.56 μg).

T0 Ave μg/l T0 StDev μg/l *TF Ave μg/l *TF StDev μg/l

Control 4.20 0.56 1.39 0.27

Treated 0.56 0.00 0.56 0.00

Regrowth Control 38.23 22.23

Regrowth Treated 0.56 0.00

Live Microbes (cfu = colony forming units)

E. coli T0 Ave 

cfu/100ml

T0 StDev 

cfu/100ml

TF Ave 

cfu/100ml

TF StDev 

cfu/100ml

Control 30.8 16.29 6.2 3.63

Treated 0 0 0 0

Enterococci T0 Ave 

cfu/100ml

T0 StDev 

cfu/100ml

TF Ave 

cfu/100ml

TF StDev 

cfu/100ml

Control 31.65 6.38 15.54 1.31

Treated 0 0 0 0

V. cholerae – No detectable culturable toxigenic Vibrio cholerae were detected in any 

samples during any of the trials.

Heterotrophic 

Bacteria 

T0 Ave 

cfu/100ml

T0 StDev 

cfu/100ml

TF Ave 

cfu/100ml

TF StDev 

cfu/100ml

Control 517 495.26 144.9 81.53

Treated 0 0 0 0

Dominant species Type Other

Skeletonema costatum Diatom Chain-forming

Thalassiosira sp. Diatom Chain-forming

Oxyrrhis marina Dinoflagellate
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Discharge Toxicity

Residual Chlorine Analysis - Levels of residual chlorine (or total residual oxidants -

TRO) were at or below the method detection limit (MDL) of 0.02 ppm in all TF treated samples. 

Acute Toxicity - There were no statistically significant survival effects in any test for 

either acutely tested species (Mysid shrimp or Sheepshead minnows). 

Chronic Toxicity - Results showed that ballast water discharge was not chronically toxic 

to either mysids or sheepshead minnows. All samples, however, were chronically toxic to the 

marine algal species Isochrysis galbana with a statistically significant inhibition in growth in 

treated ballast discharge compared to controls (see details under Summary of Results on page 4).
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8. Results Trial 3 (STDN-02): 29 October – 3 November 2009

Physical Parameters

TSS mg/l DOC mg/l POC mg/l

T0 Initial Ave StDev Ave StDev Ave StDev

Conditions 37.0 3.3 3.84 0.24 4.242 0.505

Temp oC Salinity psu Dis. Oxygen mg/l Turbidity NTU

Ave StDev Ave StDev Ave StDev Ave StDev

T0 Control 15.79 0.02 10.68 0.01 7.69 0.30 6.07 0.91

T0 Treated 15.83 0.01 10.64 0.01 8.66 0.07 7.22 0.39

TF Control 15.69 0.00 10.67 0.00 6.94 0.03 1.69 0.04

TF Treated 15.67 0.01 10.73 0.00 8.61 0.01 4.12 0.12

Live Organisms > 50 μm

T0 Ave #/m3 T0 StDev #/m3 TF Ave #/m3 TF StDev #/m3

Control 79,500 3,750 49,500 4,500

Treated No data 0.4 0.9

* Taxa listed in order of abundance.

Live Organisms 10 - 50 μm 

Vital Stain Results - It is important to note that the specific approach used underestimates 

the abundances of live organisms in this size class because it has been found that not all live 

organisms reliably take up the CMFDA stain. 

T0 Ave #/ml T0 StDev #/ml TF Ave #/ml TF StDev #/ml

Control 165 75.2 23 9.2

Treatment 0 0 0 0

Lugol’s Total Counts - This approach commonly overestimates the abundances of live 

organisms in this size class because all individuals in fixed samples are counted unless obviously 

dead (significant damage to organism). Lugol’s staining alone does not distinguish live from 

dead cells.

*TF Control *TF Treated

Copepoda nauplii Harpacticoida

Calanoida (Acartia sp.) Spionid polychaete

Spionid polychaete

Rotifera

Harpacticoida

Tintinnid

Cirripedia nauplii
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T0 Ave #/ml T0 StDev #/ml TF Ave #/ml TF StDev #/ml

Control Diatom 523 119

Dinoflagellate 455 125

Treated Diatom 276 55 3

Dinoflagellate 169 40 19

Note: 3,000/ml = Average counts for T-Final-Treated, for picoplankton <10μm.

Active Chlorophyll-a - Chlorophyll is used as ancillary data and as a general 

presence/absence indicator of viable photosynthetic organisms (MDL = 0.56 μg).

T0 Ave μg/l T0 StDev μg/l TF Ave μg/l TF StDev μg/l

Control 2.31 0.11 0.56 0.00

Treated 0.56 0.00 0.56 0.00

Regrowth Control 0.56 0.00

Regrowth Treated 0.56 0.00

Live Microbes (cfu = colony forming units)

E. coli T0 Ave 

cfu/100ml

T0 StDev 

cfu/100ml

TF Ave 

cfu/100ml

TF StDev 

cfu/100ml

Control 19.4 3.16 14.6 3.51

Treated 0 0 0 0

Enterococci T0 Ave 

cfu/100ml

T0 StDev 

cfu/100ml

TF Ave 

cfu/100ml

TF StDev 

cfu/100ml

Control 14.84 3.11 16.08 7.15

Treated 0 0 0 0

V. cholerae – No detectable culturable toxigenic Vibrio cholerae were detected in any 

samples during any of the trials.

Heterotrophic 

Bacteria 

T0 Ave 

cfu/100ml

T0 StDev 

cfu/100ml

TF Ave 

cfu/100ml

TF StDev 

cfu/100ml

Control 1,970 214.48 425 118.39

Treated 0.1 0.33 0 0

Dominant species Type Other

Skeletonema costatum Diatom Chain-forming

Thalassiosira sp. Diatom Chain-forming

Oxyrrhis marina

Gyrodinium estuarale

Dinoflagellate

Dinoflagellate
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Discharge Toxicity

Residual Chlorine Analysis - Levels of residual chlorine (or total residual oxidants -

TRO) were at or below the method detection limit (MDL) of 0.02 ppm in all TF treated samples. 

Acute Toxicity - There were no statistically significant survival effects in any test for 

either acutely tested species (Mysid shrimp or Sheepshead minnows). 

Chronic Toxicity - Results showed that ballast water discharge was not chronically toxic 

to either mysids or sheepshead minnows. All samples, however, were chronically toxic to the 

marine algal species Isochrysis galbana with a statistically significant inhibition in growth in 

treated ballast discharge compared to controls (see details under Summary of Results on page 4).
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9. Results Trial 4 (STDN-03): 5 – 10 November 2009

Physical Parameters

TSS mg/l DOC mg/l POC mg/l

T0 Initial Ave StDev Ave StDev Ave StDev

Conditions 29.4 6.1 3.65 0.10 3.070 0.536

Temp oC Salinity psu Dis. Oxygen mg/l Turbidity NTU

Ave StDev Ave StDev Ave StDev Ave StDev

T0 Control 15.14 0.03 10.46 0.01 7.28 0.09 7.79 0.74

T0 Treated 15.13 0.01 10.44 0.01 8.13 0.13 8.18 0.74

TF Control 14.50 0.02 10.38 0.00 6.81 0.02 1.71 0.03

TF Treated 14.51 0.01 10.49 0.00 8.15 0.01 4.92 0.17

Live Organisms > 50 μm

T0 Ave #/m3 T0 StDev #/m3 TF Ave #/m3 TF StDev #/m3

Control 84,000 1,875 40,500 3,000

Treated No data 0.8 0.8

* Taxa listed in order of abundance.

Live Organisms 10 - 50 μm 

Vital Stain Results - It is important to note that the specific approach used underestimates 

the abundances of live organisms in this size class because it has been found that not all live 

organisms reliably take up the CMFDA stain. 

T0 Ave #/ml T0 StDev #/ml TF Ave #/ml TF StDev #/ml

Control * 28 3.2

Treatment * 0 0

*No data available at T0 

Lugol’s Total Counts - This approach commonly overestimates the abundances of live 

organisms in this size class because all individuals in fixed samples are counted unless obviously 

dead (significant damage to organism). Lugol’s staining alone does not distinguish live from 

dead cells.

*TF Control *TF Treated

Copepoda nauplii Rotifera

Rotifera

Spionid polychaete

Calanoida (Acartia sp.)

Cirripedia nauplii

Harpacticoida
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T0 Ave #/ml T0 StDev #/ml TF Ave #/ml TF StDev #/ml

Control Diatom 1,223 128

Dinoflagellate 1,463 163

Treated Diatom 253 36 25

Dinoflagellate 408 33 34

Note: 1,200/ml = Average counts for T-Final-Treated, for picoplankton <10μm.

Dominant species Type Other

Gyrodinium estuarale

Glenodinium danicum

Dinoflagellate

Dinoflagellate

Skeletonema costatum Diatom Chain-forming

Oxyrrhis marina

Apedinella sp.

Chaetoceros sp.

Dinoflagellate

Chrysophyceae

Diatom

Active Chlorophyll-a - Chlorophyll is used as ancillary data and as a general 

presence/absence indicator of viable photosynthetic organisms (MDL = 0.56 μg).

T0 Ave μg/l T0 StDev μg/l TF Ave μg/l TF StDev μg/l

Control 6.51 2.24 1.19 0.05

Treated 0.56 0.00 0.56 0.00

Regrowth Control 4.05 4.87

Regrowth Treated 0.56 0.00

Live Microbes (cfu = colony forming units)

E. coli T0 Ave 

cfu/100ml

T0 StDev 

cfu/100ml

TF Ave 

cfu/100ml

TF StDev 

cfu/100ml

Control 28.8 2.39 2.8 2.77

Treated 0 0 0 0

Enterococci T0 Ave 

cfu/100ml

T0 StDev 

cfu/100ml

TF Ave 

cfu/100ml

TF StDev 

cfu/100ml

Control 8.7 5.05 4.94 1.35

Treated 0 0 0 0

V. cholerae – No detectable culturable toxigenic Vibrio cholerae were detected in any 

samples during any of the trials.

Heterotrophic 

Bacteria 

T0 Ave 

cfu/100ml

T0 StDev 

cfu/100ml

TF Ave 

cfu/100ml

TF StDev 

cfu/100ml

Control 712 376.94 287.3 166.88

Treated 0.1 0.33 0 0
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Discharge Toxicity

Residual Chlorine Analysis - Levels of residual chlorine (or total residual oxidants -

TRO) were at or below the method detection limit (MDL) of 0.02 ppm in all TF treated samples. 

Acute Toxicity - There were no statistically significant survival effects in any test for 

either acutely tested species (Mysid shrimp or Sheepshead minnows). 

Chronic Toxicity - Results showed that ballast water discharge was not chronically toxic 

to either mysids or sheepshead minnows. All samples, however, were chronically toxic to the 

marine algal species Isochrysis galbana with a statistically significant inhibition in growth in 

treated ballast discharge compared to controls (see details under Summary of Results on page 4).
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10. Results Trial 5 (STDN-04): 12 – 17 November 2009

Physical Parameters

TSS mg/l DOC mg/l POC mg/l

T0 Initial Ave StDev Ave StDev Ave StDev

Conditions 38.3 5.6 4.04 0.17 7.198 0.369

Temp oC Salinity psu Dis. Oxygen mg/l Turbidity NTU

Ave StDev Ave StDev Ave StDev Ave StDev

T0 Control 12.90 0.02 9.49 0.04 10.23 0.10 8.96 0.96

T0 Treated 12.95 0.02 9.48 0.01 10.29 0.03 10.00 0.69

TF Control 14.51 0.00 9.44 0.00 4.20 0.07 1.14 0.12

TF Treated 14.52 0.00 9.47 0.00 9.88 0.03 4.40 0.13

Live Organisms > 50 μm

T0 Ave #/m3 T0 StDev #/m3 TF Ave #/m3 TF StDev #/m3

Control 92,250 7,125 25,125 1,875

Treated No data 0 na

* Taxa listed in order of abundance.

Live Organisms 10 - 50 μm 

Vital Stain Results - It is important to note that the specific approach used underestimates 

the abundances of live organisms in this size class because it has been found that not all live 

organisms reliably take up the CMFDA stain. 

T0 Ave #/ml T0 StDev #/ml TF Ave #/ml TF StDev #/ml

Control 6,315 523.1 2,139 158.8

Treatment 6 1.5 0 0

Lugol’s Total Counts - This approach commonly overestimates the abundances of live 

organisms in this size class because all individuals in fixed samples are counted unless obviously 

dead (significant damage to organism). Lugol’s staining alone does not distinguish live from 

dead cells.

*TF Control *TF Treated

Copepoda nauplii None live observed 

Spionid polychaete

Calanoida (Acartia sp.)

Rotifera

Cirripedia Nauplii

Bivalvia veliger
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T0 Ave #/ml T0 StDev #/ml TF Ave #/ml TF StDev #/ml

Control Diatom 1,886 84 398 87

Dinoflagellate 16,125 1,715 3,733 100

Treated Diatom 1,818 272 236 107

Dinoflagellate 15,437 1,819 812 316

Note: 19,000/ml = Average counts for T-Final-Treated, for picoplankton <10μm.

Dominant species Type Other

Gyrodinium estuarale Dinoflagellate

Prorocentrum minimum Dinoflagellate

Oxyhrris marina Dinoflagellate

Apedinella sp. Chrysophyceae

Chaetoceros Diatom

Skeletonema costatum Diatom Chain-forming

Gymnodinium sp.

Scenedesmus quadricauda

Asterionella glacialis

Dinoflagellate

Chlorophyceae

Diatom

Active Chlorophyll-a - Chlorophyll is used as ancillary data and as a general 

presence/absence indicator of viable photosynthetic organisms (MDL = 0.56 μg).

T0 Ave μg/l T0 StDev μg/l TF Ave μg/l TF StDev μg/l

Control 78.28 9.87 12.50 0.86

Treated 0.56 0.00 0.56 0.00

Regrowth Control 41.86 15.67

Regrowth Treated 0.56 0.00

Live Microbes (cfu = colony forming units)

E. coli T0 Ave 

cfu/100ml

T0 StDev 

cfu/100ml

TF Ave 

cfu/100ml

TF StDev 

cfu/100ml

Control 74.4 40.3 6.8 3.19

Treated 0 0 0 0

Enterococci T0 Ave 

cfu/100ml

T0 StDev 

cfu/100ml

TF Ave 

cfu/100ml

TF StDev 

cfu/100ml

Control 18.8 6.46 3.7 0.89

Treated 1.33 0.58 0 0
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V. cholerae – No detectable culturable toxigenic Vibrio cholerae were detected in any 

samples during any of the trials.

Heterotrophic 

Bacteria 

T0 Ave 

cfu/100ml

T0 StDev 

cfu/100ml

TF Ave 

cfu/100ml

TF StDev 

cfu/100ml

Control 2,692 408.14 2136 467

Treated 0.1 0.33 0 0

Discharge Toxicity

Residual Chlorine Analysis - Levels of residual chlorine (or total residual oxidants -

TRO) were at or below the method detection limit (MDL) of 0.02 ppm in all TF treated samples. 

Acute Toxicity - There were no statistically significant survival effects in any test for 

either acutely tested species (Mysid shrimp or Sheepshead minnows). 

Chronic Toxicity - Results showed that ballast water discharge was not chronically toxic 

to either mysids or sheepshead minnows. All samples, however, were chronically toxic to the 

marine algal species Isochrysis galbana with a statistically significant inhibition in growth in 

treated ballast discharge compared to controls (see details under Summary of Results on page 4).
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11. Chemical Analysis of Discharge

Summary table for chemical analyses of treated water upon discharge.

______________________________________________________________________________
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12. Acknowledgments

The MERC Testing Team included J. Barnes, M. Carroll, J. Choi, D. Fisher, C. Grim, B. 

Haley, A. Huq, R. Kanzleiter, T. Mullady, G. Ruiz, G. Smith, D. Sparks, M. Tamburri. E. 

Taviani, M. Wilkinson, L. Yonkos, and G. Ziegler. Test protocols were developed in

consultation with the Great Ships Initiative (GSI), Bundesamt fuer Seeschifffahrt und 

Hydrographie (BSH) and Royal Netherlands Institute for Sea Research (NIOZ). We wish thank 

the crew of the MV Cape Washington who provided critical input and support on all aspects of 

these trials, and the Maryland Port Administration and U.S. Maritime Administration for funding 

and supporting this ballast water treatment evaluation.

June 7, 2010

June 7, 2010

Date Approved By: Dr. Mario Tamburri

MERC Executive Director

Date Approved By: Ross Kanzleiter

MERC Program Coordinator and

Chief Engineer