Infusion of combustion gases into ballast water preferably under less than atmospheric pressure to synergistically kill harmful aquatic nuisance species by simultaneous hypercapnia, hypoxia and acidic ph level

Abstract

Aquatic nuisance species (ANS) in ship's ballast water are killed by permeating to equilibrium a gaseous mixture consisting essentially of, preferably, ≧84% nitrogen, ≧11% carbon dioxide and ≦4% oxygen through ship's ballast water until the ballast water itself becomes (i) hypercapnic to ≧20 ppm carbon dioxide, and, by association, (ii) acidic to pH≦7, while preferably further, and also, being rendered (iii) hypoxic to ≦1 ppm oxygen. The permeating is preferably realized by bubbling the gaseous mixture preferably obtained from an inert gas generator through the ballast water over the course of 2+ days while the ballast water is continually maintained a pressure less than atmosphere, preferably −2 p.s.i. or less. The (i) hypercapnic, (ii) acidic and (iii) hypoxic conditions—each of which can be independently realized—synergistically cooperate to kill a broad range of ANS in the ballast water without deleterious effect on the environment when, and if, the ballast water in which the balance of dissolved gases has been changed is discharged.

Description

RELATION TO A RELATED PATENT APPLICATION[0001]The present patent application is related as a Continuation-in-Part to U.S. patent application Ser. No. 10 / 120,339 filed on Apr. 9, 2002, for CLOSED LOOP CONTROL OF BOTH PRESSURE AND CONTENT OF BALLAST WATER TANK GASES TO AT DIFFERENT TIMES KILL BOTH AEROBIC AND ANAEROBIC ORGANISMS WITHIN BALLAST WATER to inventor Henry Hunter assigning to the same MH Systems, San Diego, Calif., that is the assignee of the present invention. That application is itself a Continuation-In-Part (C-I-P) of U.S. patent application Ser. No. 09 / 865,414 filed May 25, 2001 now U.S. Pat. No. 6,539,884, for CLOSED LOOP CONTROL OF VOLATILE ORGANIC COMPOUND EMISSIONS FROM THE TANKS OF OIL TANKERS, INCLUDING AS MAY BE SIMULTANEOUSLY SAFEGUARDED FROM SPILLAGE OF OIL BY AN UNDERPRESSURE SYSTEM, now issued as U.S. Pat. No. 6,539,884. The contents of the related predecessor patent applications are incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]1. Field o...

AI Technical Summary

Benefits of technology

[0029]The present invention contemplates the infusion of inert, or combustion, gases into ballast water—preferably as is maintained under less than atmospheric pressure—in order to kill harmful aquatic nuisance species by simultaneous, synergistic, inducement of (1) hypercapnia (elevated concentration of dissolved CO2), (2) hypoxia (depressed concentration of dissolved O2), and (3) acidic pH level. The inert combustion gases may be obtained, for example, from (i) a ship's inert gas generator (of the Holec, or equivalent types), and / or from (ii) ship's own flue gases. These gases are highly noxious, having CO2 significantly increased and O2 significantly depleted, from normal atmospheric levels. An air-breathing animal—not only humans, but lower animals—would soon be stifled by these gases. Thus one way to think about the prophylactic action of present invention is to consider that the present invention effectively and efficiently alters the mixture of atmospheric gases, including oxygen (O2), that normally are dissolved in ballast water in favor of, predominantly, carbon dioxide (CO2). Aquatic marine organisms—at least of the aerobic types—can scarcely tolerate these noxious gases any better than can air-breathing animals, and a widespread and severe die-off of multiple marine organisms, is experienced in the presence of these noxious gases dissolved in sea water.1. The Present Invention Starts With Inducing (1) Hypercapnia, and, in Association with Elevated CO2, (2) Depressed pH

[0057]In another of its aspects the present invention may be considered to be embodied in a quantitative method of reducing survival of aquatic nuisance species in ship's ballast water that is, in the preferred parameters of its conduct, quite unlike any prior art with which the inventors are acquainted. In simple terms, the method of the present invention renders ballast water triply deadly to aquatic nuisance species due to each of hypoxia, hypercapnic and acidic conditions.

[0062]In yet another of its aspects, the present invention is embodied in a system for reducing survival of aquatic nuisance species in ship's ballast water.

[0073]This is achieved at a rate that will, most preferably, permit the entire maximum ballast water of a ship to be treated to these levels in a period less than, most preferably, one-half the normal voyage duration of the ship minus the required time for aquatic nuisance species to die to the 90% level. This is only to say that the shipboard ballast water gaseous infusion system is sized to (i) the task at hand, (ii) the time available for the completion of the task, and (iii) the resilience to die off (from hypercapnia, anoxia and acidic conditions) of the ANS to hand, all at an adequate safety margin. Most typically all the ballast water on a ship will be treated so as to reach desired dissolved gas levels in less than, most preferably, one day, and will be held at those levels for, most preferably, at least two days, and more commonly more than four days. It is, or course, totally acceptable and beneficial to hold the conditions that kill ANS for weeks and longer, should the usage of the ship and its ballast tanks so permit. There is no harm incurred in dumping ballast water having those gas concentrations that are, in accordance with the present invention, different from normal seawater into the sea, where the evacuated ballast water is so quickly diluted that it is not deemed capable of harming even the most delicate marine organisms proximate the release point.

Problems solved by technology

Aquatic marine organisms—at least of the aerobic types—can scarcely tolerate these noxious gases any better than can air-breathing animals, and a widespread and severe die-off of multiple marine organisms, is experienced in the presence of these noxious gases dissolved in sea water.

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