December 1, 2022
The number one global environmental problem carries the label of potable water. I believe it is or will soon be the number one global problem. At a minimum, it will achieve greater significance in the years ahead this century.
The world’s total water supply is enormous compared with the presently conceivable needs of man, yet there is a growing potable water concern. Approximately 98% of the 320 million cubic miles of water in the Earth’s crust is salty and useful neither for irrigation by present techniques nor for the majority of man’s other needs. Precipitation provides many times the world’s annual water needs, but fresh water supplies vary widely not only over the Earth’s surface but also from time to time in a given region. This accounts for what has come to be referred to as the “water problem.”
An obvious way to increase water availability is to recover fresh potable water through desalination from seawater or from some other source. Your favorite author has recently and is currently investigating new processes for producing potable water. This month’s article introduces the reader to the desalination process and reviews the essence of two recent potable water patents.
In the overall desalination process, feed water is introduced to the desalination unit where – following the application of some form of energy – it is separated into (relatively) pure potable water, and a more concentrated brine solution.
Of all of the desalination processes, the only ones which are known to currently be economically feasible are: (1) evaporation, (2) reverse osmosis, and (3) crystallization (freezing). At present, the economic feasibility of all other processes is considered doubtful. Each of these three processes is briefly discussed below.
The oldest and best developed process for saline water conversion is the evaporation method. In many desalination technologies in use or being developed today, desalination began using evaporative processes. These evaporative desalination techniques were recognized over 2,000 years ago when Aristotle wrote in 320 B.C., “saltwater, when it turns into vapor, becomes sweet and the vapor does not form saltwater again when it condenses.” It remains one of the major methods today for commercial production of fresh water from seawater. In principle, seawater is boiled in an evaporator by passing hot steam through an enclosure (a steam chest) where the steam condenses on the inside of the tubes of the chest and is usually returned to a boiler. The vapors rising form the seawater feed are cooled in a condenser and thus converted into pure liquid water which is collected in a storage vessel. The accompanying resulting concentrated brine solution is continuously or intermittently withdrawn from the evaporator.
Electrodialysis was the membrane separation process employed for desalination a century ago. However, in recent years, reverse osmosis (RO) has displaced electrodialysis as the primary membrane separation desalination process, leaving the latter as the choice for medical kidney applications. An RO system consists of an intake, a pre-treatment component, a high-pressure pump, a membrane apparatus, remineralization, and pH adjustment components, as well as a disinfection step. Generally, a pressure of about 1.7 to 6.9 MPa is required to overcome membrane resistance to flow. The aforementioned pressure must be applied to the solvent or water and the membrane must be relatively impermeable to the solute or order to make water pass through the membrane in the desired direction (i.e., away from a concentrated salt solution). The membranes used for RO processes are characterized by a high degree of semi-permeability. These membranes may be configured into a variety of geometries for system operation, including: plate and frame, tubular, spiral wound (composite), and hollow fiber.
Crystallization processes were also employed over 2,000 years ago. Today, these processes are important industrial operations that are often employed in the preparation of a pure product, e.g., sugar, coffee, etc. A crystal usually separates out as a substance of specific composition from a solution of varying composition. There are several different ways that crystallization can occur. The three most often encountered in practice are
- Cooling and evaporation.
Process 1 is the most commonly employed.
World-wide development of potable water techniques in the last half century has been driven out of necessity due both to water scarcity and population growth. The private sector has primarily led the investment in research and development since water has begun to be seen not as a commodity, but as a product to be sold at a profit. With this in mind, your favorite author recently developed two processes that are presently utility patents. The two processes are described below.
1. The WOFF (Water Obtained from Fossil Fuels) Process, Patent #17,579,045:
A process of producing potable water by combining a hydrocarbon-containing fossil fuel with oxygen in a combustion device such as a utility boiler or home heating to produce a flue gas of water vapor and carbon dioxide, and condensing the water vapor in the flue gas to yield potable water. The combustion device can produce heat or electricity. The water vapor can be condensed with one or more heat exchange devices. The source of oxygen can be air, pure oxygen, or nitrogen reduced air. The source of oxygen can be humidified, such as with a non-potable water source , or non-potable water can be added to the flue gas. The carbon dioxide and / or nitrogen in the flue gas can be reduced or removed before the condensation step(s). The pressure of the flue gas can be increased prior to condensation of the water vapor. Natural gas is the preferred fuel.
2. The THEOGEO Process (Theodore Geothermal) Patent #17,736,235:
A system and method for converting non-potable water into potable water employing Geothermal energy. Non-potable water, such as seawater or non-potable ground water, and the like, is fed down a conduit into a deep underground enclosure. Due to its extreme depth, the enclosure is geothermally heated above the boiling point of water at the pressure within the enclosure. The water boils and creates water vapor. The water vapor rises and can be drawn up through a vapor conduit to the surface. The water vapor can be condensed (and further purified, if necessary) into potable water. The steam can be used in a hybrid system where it is condensed after being used for heating purposes or the production of electricity.
Your thoughts on the two patents would be appreciated. I can tell you that no individual or business entity has yet expressed an interest in either patent, both of which have cost me a pretty penny. HELP!
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