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As of 2004, this project is no longer current. Please see the Research Programs page for a list of current research projects.
Disinfection of Ballast Water with Chemical Disinfectants
Currently there is no active research on this project which was completed in 2003
The unintentional establishment of nonindigenous aquatic species through the release of ballast water has had a profound impact on aquatic ecosystems worldwide. This impact is particularly evident in the Laurentian Great Lakes, where the introduction of species such as the zebra mussel (Dreissena polymorpha) has affected populations of organisms and altered important ecological processes. The recent discovery of several new nonindigenous species in the Great Lakes demonstrates the urgent need for ballast water management in order to reduce the risk of future introductions.
In a 1996 report, the National Research Council (NRC 1996) identified a range of promising options for treating ballast water. Included in this list were biocides, which can be added to both ballasted and non-ballasted vessels in order to eliminate viable organisms. Biocide treatment is a potentially attractive option since it can be readily incorporated into both existing and future vessel designs and may be effective against a broad range of organisms; however, the safety of such a treatment option may be limited by the degradation rate of the biocide and the potential release of biocidal concentrations into receiving waters. In addition, although biocides have been used extensively in certain industries for disinfection, the ballast tank environment is unique and may not be compatible with certain biocides, which can react rapidly with organic material or may be corrosive at higher concentrations.
There are several issues that need to be addressed to provide NOAA and
other 
regulatory agencies
with materials that can be used safely and effectively to treat ballast
water: (1) The operational safety of disinfection chemicals needs to be
determined in order to identify those chemicals that are not reactive
with on-board chemical products; (2) The potencies of disinfectants need
to be established so that appropriate concentrations can be selected;
(3) The confidence limits of the toxicity of compounds are needed in order
to establish the limits associated with biocide treatments; (4) Data on
degradation rates and pulsed exposures are needed to mesh with dilution
models so that safe discharge of treated ballast can be determined; and
(5) The effectiveness of the biocides in the ballast water environment
needs to be demonstrated. The objectives of this research are designed
to address most of the above questions for hypochlorite and glutaraldehyde
plus adjuvant. This work will directly measure the potency of two biocides
with a wide range of organisms and test them in the presence of sediments
that might reduce the effectiveness of the compounds. The effectiveness
of the biocides in ballast water samples is determined and compared with
both a positive and negative control. Finally, the degradation of the
active ingredients will be followed to provide data for determination
of safe discharge conditions. This work will likely have best application
for vessels that transit with "no ballast on board (NOBOB)" to treat the
residual slop in the ballast tanks. In addition, the information generated
from this work can be directly applied to a field test of shipboard treatment
of NOBOB vessels.
This project is an outgrowth of a collaborative effort with scientists from the University of Michigan and our work for FY 2000 on the use of glutaraldehyde as a potential ballast water disinfectant. The results of that collaboration can be found under a project on the effects of contaminants.
2002 Plans
The objective of the work for the upcoming year is to complete the initial studies with glutaraldehyde and hypochlorite to address the questions needed to provide the toxicological profile for the potential use of these two materials as ballast water disinfectants. The testing will include completion of acute bioassays, measurement of degradation rates and testing under simulated ballast tank conditions.
2001 Accomplishments
The focus of the studies for this year were acute bioassays with hypochlorite and glutaraldehyde with adjuvant in both water-only and water and sediment environments. The bioassays were for 24 h with a goal of assessing the LC90. The toxicity tests employed primarily the amphipod, Hyalella azteca, that had been shown to be one of the more resistant organisms to glutaraldehyde and the oligochaete worm, Lumbriculus variegatus. Additional work was performed with Daphnia magna and with an algal bioassay. The hypochlorite was very toxic to all species tested in water only, but in the presence of sediment, it required substantially increased concentrations to overcome the reaction with sediment. The LC90 for L. variegatus ranges from 2,904 - 25,586 ppm in the presence of sediment depending on the type of sediment used (Table FY01-1). As expected the higher the organic carbon content of the sediment the more of the active chlorine could be absorbed by the sediment and the more hypochlorite was required to produce mortality. For the glutaraldehyde, two surfactants were tested as potential adjuvants, Hyde Mud Remover (Hyde Marine Cleveland, OH) and a proprietary non-polar surfactant in Disinfekt 1000 (Diversified Nutri-Agri Technologies, Inc., Gainesville, GA). Both compounds enhanced the toxicity of glutaraldehyde, however the Disinfekt 1000 was more effective (Table FY01-1). In the presence of sediment, the concentration of glutaraldehyde in the Disinfekt material required to produce 90% mortality was about half that for systems with glutaraldehyde alone.
Table FY01-1 Toxicity of hypochlorite and glutaraldehyde to selected aquatic organisms
|
Organism
|
Water: Sed. Ratio
|
Sediment Type
|
LC90 (mg/L)
|
|
Disinfect
|
|
|
|
|
H. azteca
|
1:0
|
None
|
178
|
|
H. azteca
|
8:1
|
Gallup Park
|
214
|
|
L variegatus
|
1:0
|
None
|
< 7.6
|
|
L variegatus
|
1:0
|
None
|
13.3
|
|
L variegatus
|
8:1
|
Gallup Park
|
33.4
|
|
L variegatus
|
4:1
|
Gallup Park
|
130.1
|
|
L variegatus
|
2:1
|
Gallup Park
|
764
|
|
L variegatus
|
4:1
|
Lake Michigan
|
49.3
|
|
L variegatus
|
4:1
|
Terwilligers Pond
|
244
|
|
|
|
|
|
|
Hyde
|
|
|
|
|
L variegatus @ 20 ppm
|
1:0
|
None
|
12.5
|
|
L variegatus @ 100 ppm
|
1:0
|
None
|
12.1
|
|
L variegatus @600 ppm
|
1:0
|
None
|
9.5
|
|
H. azteca @ 600 ppm
|
1:0
|
None
|
206
|
|
L variegatus @ 600 ppm
|
8:1
|
Gallup Park
|
21
|
|
L variegatus @ 100 ppm
|
8:1
|
Gallup Park
|
23
|
|
|
|
|
|
|
Hypochlorite
|
|
|
|
|
L variegatus
|
1:0
|
None
|
1.0
|
|
L variegatus
|
1:0
|
None
|
1.6
|
|
L variegatus
|
4:1
|
Gallup Park
|
2,904
|
|
L variegatus
|
4:1
|
Lake Michigan
|
11,561
|
|
L variegatus
|
4:1
|
Terwilligers Pond
|
25,586
|
|
H. azteca
|
1:0
|
None
|
4.7
|
|
D. Magna
|
1:0
|
None
|
0.1
|
In addition to toxicity tests, some degradation tests were performed with hypochlorite. The material degraded very rapidly in the presence of sediment reflecting its high reactivity. This is the primary reason that high concentrations were required to produce mortality in benthic organisms in the presence of sediment.
Last updated: 2004-04-23 mbl