Liquid purification or separation – Processes – Liquid/liquid solvent or colloidal extraction or diffusing...
Reexamination Certificate
2001-04-14
2003-09-02
Upton, Christopher (Department: 1724)
Liquid purification or separation
Processes
Liquid/liquid solvent or colloidal extraction or diffusing...
C210S710000, C210S747300, C210S806000, C210S170050, C210S202000, C210S242100, C210S257200, C210S321690
Reexamination Certificate
active
06613232
ABSTRACT:
BACKGROUND OF THE INVENTION
In the marine environment the generation and discharge of contaminated wastewaters need to be controlled to avoid polluting said environment. In particular, sea-going vessels must discharge ballast water, graywater from laundry and dishwashing etc., and blackwater sewage directly into a body of water, such as an ocean. In addition, during sediment dredging operations excess waters are generated that can be contaminated if the sediments being excavated contain pollutants such as heavy metals or problematic organic compounds.
Current strategies to control these discharges vary from location to location, but in general wastewaters from sea-going vessels are managed by either discharging said waters in deeper ocean waters away from the coastline, installing treatment systems on-board the offending sea-going vessel, or storing said waters on the offending vessel and pumping said waters to a treatment or transfer facility at the docking port. Wastewaters generated during dredging operations, if such waters are contaminated, are, in almost all cases, pumped to an on-shore impoundment or treatment facility for management.
This invention includes methods and processes for managing such waters using a mobile floating water treatment vessel with membrane filtration treatment technology capable of achieving highly efficient degrees of treatment that can readily address the primary concerns associated with marine wastewater discharges. This can be accomplished without the need for on-board or on-shore treatment systems. As will be readily apparent upon further elaboration of these marine wastewater discharges and the water treatment approach associated with this invention, the development of such a mobile treatment system lends itself not only to the treatment of ballast water, graywaters, blackwaters, and contaminated dredge waters, but also to the treatment or pretreatment of raw marine water for potable water use or near-shore industrial discharges should such treatment be necessary.
Ballast Water
Ballast in the form of water is taken on board vessels to reduce the stresses in the hull of the ship, to provide for transverse stability, to aid propulsion by controlling submergence of the propeller, and to aid in maneuverability by submerging the rudder and reducing the amount of exposed hull surface (free board and windage) and to compensate for weight loss from fuel and water consumption. Dry bulk carriers, ore carriers, tankers, container ships, general cargo vessels, passenger vessels, and military vessels all take on ballast water either in port or during a voyage. Most ships deballast (discharge ballast water) during cargo loading operations and take on ballast water during cargo unloading operations.
As a result of ballasting and deballasting operations, oceangoing vessels can be expected to transport marine organisms, contained in the ballast water, from any port in the world to any other port in the world. The development of effective methods to control the transport and/or release of nuisance organisms that are found in ballast water is a problem facing the international maritime community. When such nuisance organisms (mollusks, crustaceans, worms, seaweed, algae, fungi, and protozoa) present in the ballast water (taken on board from a foreign port) are introduced into a new ecosystem (by discharging of the ballast water into a secondary port's coastal environment), there are often no natural predators for these organisms (commonly referred to as aquatic nuisance species). Introducing aquatic nuisance species into new environments can have serious environmental consequences. The threat of non-indigenous species introduced through ship deballasting is a worldwide problem. Ships deballast in ports everywhere in the world impacting local fishing industries and the ecology (National Research Council, 1996. Stemming the Tide: Controlling Introductions of Nonindigenous Species by Ships' Ballast Water, National Academy Press, Washington, D.C.).
At the present time, the most common strategy for controlling foreign species present in ballast water is the ballast water exchange process. In this process cargo vessels unload ballast water (taken on board at a local port after discharging cargo) into the open ocean and exchange the discharged ballast water with mid-ocean seawater (International Maritime Organization, 1998. Guidelines for the Control and Management of Ships' Ballast Water to Minimize the Transfer of Harmful Aquatic Organisms and Pathogens, London, 1998). While currently the standard recommended practice, this method is generally not considered to be very effective in controlling aquatic nuisance species because 1) organisms often continue to survive in the sediment and residual water in ballast tanks; 2) the process can take 6 to 24 hours and subject a vessel to instability during turbulent weather, resulting in serious safety issues; and 3) mid-ocean ballast water exchange can also stress the structural integrity of cargo vessels, particularly under turbulent weather conditions (Motor Ship, 2000, Ballast Water Management: Balancing Green Issues with Safety, Motor Ship, May 2000).
Other technologies being proposed or investigated for treating ballast water include particle filtration processes, gravity processes (sedimentation, flotation, and centrifugation), thermal processes (pasteurization at 60° C. to kill organisms), electromagnetic radiation (UV lamps), chemical treatment (including chlorination, ozonation, pH adjustment, deoxygenation, and salinity adjustment), and gaseous sterilization (using the exhaust gases from the ship's engine to kill organisms) (National Research Council, 1996. Stemming the Tide: Controlling Introductions of Nonindigenous Species by Ships' Ballast Water. National Academy Press. Washington, D.C.).
A number of recent U.S. patents have been issued on proposed ballast water treatment approaches. Gill, Method for Controlling Zebra Mussels in Ship Ballast Tanks, U.S. Pat. No. 5,128,050, Jul. 7, 1992, proposes to control zebra mussels or its larvae by introducing the chemical didecyl dimethyl ammonia halide into ballast water tanks. Eguisa and Fukuyo, Method for Destroying Cyst of Noxious Plankton, U.S. Pat. No. 5,256,423, Oct. 26, 1993, propose a strategy to control the cyst of noxious plankton by introducing hydrogen peroxide. Sherman, Ballast Water Treatment System, U.S. Pat. No. 5,816,181, Oct. 6, 1998, proposes to pump the ballast water through heat exchangers on board a vessel using the waste energy from the propulsion system of the vessel as the heat source. Browning, Method and Apparatus for Killing Microorganisms in Ship Ballast Water, U.S. Pat. No. 5,932,112, Aug. 3, 1999, proposes a deoxygenation approach designed to suffocate the organisms contained in the ballast water. Rodden, Ballast Water Treatment, U.S. Pat. No. 6,125,778, Oct. 3, 2000, proposes the treatment of ballast water with ozone while the vessel is in transit between ports. Rodden describes several proposed methods for contacting the ballast water with the ozone to effect this treatment approach.
While all of the above methods offer some potential treatment options, the introduction of chemical reagents into ballast water tanks to kill nuisance organisms could have adverse impacts on receiving waters when the ballast water is discharged. Heat treatment and deoxygenation strategies may be possible in theory, but many microbes are capable of overcoming such environments through spore formation and anaerobic activity. Ultraviolet radiation is untested at such high flow rates and the effectiveness of these approaches with liquids containing high levels of suspended solids are questionable. In short, none of the currently proposed strategies offers solutions that appear practical. In addition, the focus of essentially all the aforementioned treatment applications has been to consider the siting of such treatment systems on-board the offending vessel. Siting these facilities on-board the offending vessel means that all existing v
Chesner Warren Howard
Melrose James
Upton Christopher
Walker Alfred M.
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