Liquid purification or separation – Processes – Including geographic feature
Reexamination Certificate
2002-08-08
2004-04-27
Hruskoci, Peter A. (Department: 1724)
Liquid purification or separation
Processes
Including geographic feature
C210S620000, C210S758000, C210S776000, C210S170050, C210S220000, C210S242100, C210S242200, C210S242300, C210S257100, C210S258000, C222S105000, C405S064000, C405S068000, C405S066000
Reexamination Certificate
active
06726846
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a vertical membrane storage system, and to a method of storing a fluid using the storage system. Specifically, the invention relates to a submerged storage system that is capable of storing any number of fluids, including, inter alia, excess sewage emanating from a sewage system or a combined sewage-storm water system during periods of heavy flow.
2. Background of the Invention
Sewer overflow can cause significant problems, including individual home flooding with sewage, as well as dumping overflow into and consequently polluting local waterways. This overflow occurs when the flow capacity of a sewer system is exceeded by the rainwater in-flow rate into the system for combined sanitary and storm sewer systems. Sewage backup and local water pollution is present in most storm sewer systems where the storm sewers are rarely of a sufficient size to accommodate unusually heavy rainstorms.
When an overflow is encountered, the local municipalities prevent overload of the sewage treatment plant, as well as sewer backup into homes by diverting the excess flow to local waterways, such as rivers, lakes, large retention ponds, and the oceans. This diversion creates an enormous environmental hazard. Moreover, for many inland cities, there are no large natural systems that can accommodate the overflow. As a consequence, these inland cities must rely on very expensive underground storage systems.
To minimize overflow and backup problems from a storm sewer system, a number of expensive methods have been heretofore proposed. Where there are adequate spaces and tax revenues available for doing so, water drainage ponds and lakes have been constructed to collect excess rainwater run-off before the water can gain direct access to the storm sewer system. Such drainage ponds or lakes are usually not feasible. Moreover, recently it has been discovered that such drainage ponds and lakes have created drinking water contamination problems if the area obtains its drinking water from underground wells or streams into which the water in the drainage ponds and lakes can drain.
A municipality also can minimize storm sewer backup and overflow by increasing the size of the storm sewers that make up a citywide storm sewer system. This solution is extremely expensive, however, and it is an impractical solution to the problem, unless the storm sewer system has to be replaced for other reasons.
One costly solution that attempts to solve the problem of sewage backup into an individual's home is proposed in Regan, U.S. Pat. No. 4,892,440. Regan proposes burying large water storage tanks in the ground to handle the overflow. The water backup system described therein also includes a complicated system of float switches, valves and pumps to both divert the water to the storage tanks, and then to withdraw the overflow from the tanks when the overflow conditions have subsided. Regan's backup prevention system is quite costly to construct, and once in the ground, cannot readily be moved or replaced. Moreover, it is very expensive to fix leaks that inevitably develop in the storage tanks.
It is known to divert overflow water and sewage to a flexible channel that is capable of expanding when filled with the overflow liquid. For example, German patent application DE 3,426,789 discloses a plastic sack having an opening to receive supply and to discharge overflow sewage water. Overflow still may occur, however, if the plastic sack is not large enough to accommodate the excess flow, and an overflow is provided between the sewer and the plastic sack. In addition, undesirable odor may emanate from the sack because the sewer is in direct contact with the atmosphere. If the overflow capacity of the plastic sack is exceeded, non-clarified sewage still can contaminate the natural waters.
Lesh, U.S. Pat. No. 3,701,428 discloses a sewage disposal unit that comprises a plurality of flexible sewer pipes connected to a flexible plastic septic tank, or tanks, submerged in a body of water adjacent the sewer mains. Lesh states that the pressure of the body of water serves to support the submerged plastic septic tanks which avoids extensive excavation or building concrete tanks. The flexible system of Lesh is limited in size, and when its capacity is exceeded, overflow will still occur.
Clemens, WO 98/03742 proposes another flexible channel for storing sewage and clarifying the sewage in the event of heavy rainfall. Clemens utilizes a flexible plastic material, such as a geotextile (Perl E), and tension ropes to support the flexible material when filled. While providing a cheaper and more mobile solution to the overflow problem than that proposed in Regan, Clemens' system does not effectively clarify the sewage, and it is difficult to fill and withdraw liquid from the system. The tension ropes also cause considerable stress at the junction of the tension ropes and the plastic material that can cause rips or tears. The tension ropes also may cause the deposit of excess sludge that is difficult to remove.
In addition to the pollution problems associated with overflow of sewage, there are other significant environmental problems associated with the earth's natural water system. It is generally accepted that our oceans are losing life. Les Watling of the University of Maine has hours of videotape showing “before-and-after” footage of the ocean, and the effects of trawling: showing gardens of life in one segment (before), and mud and debris in the other (after).
In vast near-coastal areas and in semi-enclosed seas the water itself has been rendered sterile. The problem is believed to be caused by nutrient pollution, the smothering deluge of sewage, manure, and chemical fertilizers from land-based activities. Rising populations and the increasingly intensive agriculture and livestock operations needed to feed them have caused an explosion in nutrient run-off. This problem is even more exacerbated by the dramatic increase in bio-engineered fertilizers and feedstocks, which are now dumping numerous unknown organisms into our waters.
Although some nutrients can be beneficial to our waters, too large a quantity poisons the waterways. Phyloplankton productivity is limited by the availability of nutrients in sea water, and where there are excessive levels, these microscopic algae explode in such massive blooms that grazers cannot keep up. The dead algae fall to the bottom to be decomposed by bacteria, a process that consumes large amounts of oxygen, so much that often little or none is left to sustain anything else. This condition is called hypoxia. When hypoxic conditions occur, all animal life that cannot swim away suffocates. This is how the Black Sea's shallow life-bearing shelves were laid waste, setting the stage for the ecological collapse of the entire basin. Hypoxia also has become a chronic problem in the Gulf of Mexico, where a seven thousand square mile “dead zone” appears off the Louisiana and Texas coasts during the spring and summer, disrupting shrimp and fish migrations, and wiping out bottom fauna. Seasonal hypoxia affects many other natural waterways, including, for example, the Chesapeake Bay, N.Y. Bight, the Adriatic, North, and Baltic Seas, the Yellow Sea, and the like.
Other pollution exists as well. For example, toxic chemicals have for years been dumped into our vast oceans. Paints used on ships to keep barnacles and other parasites from clinging to the ship's hulls become dissolved in the water and ingested by the local marine life. Moving marine life from one ecosystem to another also creates a great deal of pollution.
The most common agents of what scientists call “invasive species transfer” are oceangoing tankers and container ships. When light on cargo, most ships are obliged to pump water into their holds to maintain their seaworthiness. This ballast water contains numerous plants and animals, some as adults, but most in the form of eggs, larvae, or juveniles. On reaching its destination halfway around the world, a s
Hruskoci Peter A.
Hunton & Williams LLP
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