Ships – Building – Freighters
Reexamination Certificate
2001-10-18
2003-09-30
Morano, S. Joseph (Department: 3617)
Ships
Building
Freighters
C114S125000, C210S764000
Reexamination Certificate
active
06626122
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to methods for using deactivatable biocides in ballast water used on ships and other vessels.
BACKGROUND OF THE INVENTION
Ballast water is used on ships in order to maintain appropriate ship draft, trim, stability, immersion, and hull integrity. Ballast water may be taken on in special ballast tanks or may be taken on in the cargo tanks of a ship. Ships travel with ballast water when carrying no cargo or light cargo and travel with little or no ballast on board when carrying a maximum cargo. The quantity of ballast water used in a ship can be quite large. For example, a 300,000 metric ton crude tanker has a ballast water capacity of 100,000 metric tons. Typically, the ratio of ballast water to ship capacity is 1:3 to 1:2.
Ballast water is normally taken on in one coastal region and is discharged in another coastal region. For example, ships take on ballast water from one port, travel to a second port, and discharge a large amount of ballast water in order to take on cargo at the second port. The discharge of ballast water has led to the introduction of non-native life forms in many areas, as the life forms from one coastal region to another vary. Even ships reporting no ballast on board may act as vectors for non-native life forms because the ballast tanks of such ships contain an unpumpable amount of residual ballast water.
One proposed method of limiting the introduction of foreign organisms into marine environments is for ships to discharge their ballast water in the open ocean prior to entering port. However, as mentioned above, ballast water is typically needed to maintain essential operating conditions of a ship, and it may be dangerous to discharge ballast water before reaching a port.
Another method for limiting the introduction of life forms in ballast water is to exchange near-coast ballast water for mid-ocean ballast water. Presumably, the life forms taken on board the ship in a near-coast environment are flushed into the mid-ocean. It is important that the ship maintain stability, draft, and other operating parameters during this exchange, and only ships that are designed for this practice can safely exchange ballast water. Ships may be retrofitted to permit this exchange, but such retrofitting is very expensive. Currently only a small proportion of the world's cargo fleet is capable of ballast water exchange. Ballast water exchange may be completed by (1) emptying the ballast tanks and refilling them one at a time, or (2) pumping three volumes of ocean water into the tanks to flush them. Neither approach is completely effective in eliminating foreign life forms. The first method leaves a heal in the tank which can harbor life forms, and the second method allows life forms to be retained during the mixing. The effectiveness of ballast water exchange has been estimated at 90% and usually takes about 2 days to safely complete.
Because the above methods are not as effective or efficient as ideally desired, other methods of controlling the transfer of life forms have also been proposed. One of these methods is the use of biocides. However, when biocides are used to kill life forms in ballast water, the ballast water may be toxic to indigenous life forms when discharged into the environment. By way of example, chlorine has been used as a biocide, but the discharge of the ballast water treated with chlorine has been prohibited in some areas as a chlorinated waste.
Accordingly, there is a need in the art for a method of limiting the transfer of life forms via ballast water that is effective and efficient, can be used on existing vessels, and has reduced environmental toxicity compared to traditional use of biocides.
SUMMARY OF THE INVENTION
The invention relates to the use of deactivatable biocides in ballast water. Deactivatable biocides can be used with ballast water on a ship to limit or prevent the introduction of one or more life forms from one environment into another environment where the ballast water will be discharged. The deactivatable biocides can be irreversibly deactivated before or upon discharge of the ballast water to minimize potential environmental damage.
One aspect of the present invention is a method of disposing of ballast water containing a deactivatable biocide. A vessel is provided that has ballast water from a first location. The ballast water contains an effective amount of deactivatable biocide. An effective amount of a neutralizing agent is added to the ballast water to deactivate the biocide. The ballast water is then discharged from the vessel at a second location.
Another aspect of the present invention is a method of inhibiting growth and reproduction of microorganisms in a ballast water system of a vessel. Ballast water is provided to the ballast water system from a first natural environment. An effective amount of a deactivatable biocide is added to the ballast water. The deactivatable biocide can be irreversibly deactivated before or upon disposal of the ballast water.
An additional aspect of the present invention is a method of limiting the transfer of one or more life forms from a first location to a second location via ballast water. A vessel having a ballast water tank is provided. Ballast water from the first location and an effective amount of a deactivatable biocide are mixed in the ballast water tank. An effective amount of a neutralizing agent is added to the ballast water to deactivate the biocide. At least a portion of the ballast water is then discharged at the second location.
A further aspect of the present invention is a method of limiting the transfer of one or more life forms from one location to another location via ballast water using Fischer-Tropsch derived deactivatable biocides. A vessel having a ballast water tank and a cargo tank is provided. Fischer-Tropsch-derived liquid products and a Fischer-Tropsch derived deactivatable biocide are synthesized from a Fischer-Tropsch synthesis process. One or more of the Fischer-Tropsch-derived liquid products are added to the cargo tank at a first location. The Fischer-Tropsch derived deactivatable biocide is added (at the first location) to the ballast water tank and/or to a biocide storage area on the vessel. The Fischer-Tropsch-derived liquid product or products in the cargo tank are then delivered to a second location. Ballast water from the second location and an effective amount of the deactivatable biocide are mixed in the ballast water tank. An effective amount of a neutralizing agent is added to the ballast water to deactivate the biocide. At least a portion of the ballast water is then discharged at the first location or a third location.
Yet another aspect of the present invention is a method of limiting the transfer of one or more life forms from a beginning location to a final location via ballast water using a deactivatable biocide and ballast water exchange. A vessel having a ballast water tank is provided and water from the beginning location is added to the ballast water tank. A portion of the ballast water is discharged at an intermediate location, and an effective amount of a deactivatable biocide is added to the remainder of the water from the beginning location. Water from the intermediate location is added to the ballast water tank. An effective amount of a neutralizing agent is added to the ballast water to deactivate the biocide, and at least a portion of the ballast water is discharged at the final location.
Definitions
Unless otherwise stated, the following terms used in the specification and claims have the meanings given below:
“Biocide” means any substance that kills or inhibits the growth of microorganisms, such as, for example, bacteria, molds, slimes, fungi, and the like.
“Branching index” means a numerical index for measuring the average number of side chains attached to a main chain of a compound. For example, a compound that has a branching index of five means a compound having a straight main chain with an average of approximately five side chains attached thereto.
“Syngas” is a m
Buetzow Mark R.
Dorsch Brian V.
Moir Michael E.
O'Rear Dennis J.
O'Reilly Kirk T.
Chevron U.S.A. Inc
Morano S. Joseph
Olson Lars A.
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