Liquid purification or separation – Processes – Making an insoluble substance or accreting suspended...
Reexamination Certificate
2000-03-17
2002-09-03
Simmons, David A. (Department: 1724)
Liquid purification or separation
Processes
Making an insoluble substance or accreting suspended...
C210S727000, C210S730000, C210S908000, C127S050000
Reexamination Certificate
active
06444128
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to methods for the precipitation and removal of starch and other carbohydrate and sugar unit containing organic waste, typically measured as either chemical oxygen demand (“COD”) or biological oxygen demand (“BOD”), and other suspended solids from a wide range of process streams.
The presence of undissolved organic particles and soluble components which contain starch or other carbohydrates in industrial process streams represents significant environmental problems due to the COD/BOD levels resulting from the starch's presence. Increasingly stringent regulations on the COD/BOD levels in water which can be discharged into the environment places many facilities presently outside of compliance with these environmental regulations. The presence of these starch particles in any given process stream may result from starch addition to upstream processes such as in paper manufacturing, or simply as a natural result of cleaning raw vegetables of dirt in preparation for further processing. Additionally preparation of foods high in starch such as pasta, rice, wheat, corn etc. also naturally results in water streams containing significant amounts of starch.
While the relatively large pieces of vegetable matter which become detached and suspended in solution during the washing of the vegetable may be easily removed through filtration or settling, small suspended vegetable pieces and other starch particles intermixed with other suspended solids such as dirt, silica, or any other process component typically cannot be removed by simple filtration, flocculation, or settling. Consequently more complex measures must be taken in order to remove these suspended particles.
Some facilities presently resort to simply dumping large quantities of high COD starch-containing water into fields where the organic matter is decomposed on the ground. While such activity prevents the high COD water from introduction into lakes, rivers and streams, it prevents the reuse of large volumes of process water and can result in the release of significant odors which make it undesirable in even sparsely populated regions.
Other processes, such as ultrafiltration, can ultimately remove almost any suspended solid particle, even the suspended starches, thereby allowing for the reuse and recycling of the now clarified water back into the process. While such methods can significantly reduce the quantity of water required in a given process and prevent the discharge of high COD water into the environment, the high cost of capital equipment, maintenance and operation make such processes prohibitively expensive for a large number of applications.
A process capable of easy, efficient and nearly quantitative removal of suspended starch and other COD-producing components from a wide range of industrial process streams thereby allowing for ready discharge of said streams into the environment or reuse and recycle of said streams would be a great advancement in the art.
SUMMARY AND OBJECTS OF THE INVENTION
The present invention provides a process for the precipitation and easy removal of suspended starch, other carbohydrate or sugar unit containing organic particles and components which organic matter creates high quantities of Chemical Oxygen Demand (“COD”) or Biological Oxygen Demand (“BOD”), as well as other suspended solids from a given solution. The process includes the steps of adding a complexing agent, such as multivalent metal ions and their complexes, capable of interacting with the organic particles and components and subsequently adding a flocculating agent to facilitate the precipitation of the organic containing particles and components. Once the suspended particles and components have been precipitated into larger, more easily filtered particles, they can be readily removed by conventional filtration or other known methods in the art. A wide variety of complexing agents can be employed. These complexing agents can be multivalent metal ions and their complexes. The choice of the complexing agent used to create the interaction with the organic particles and components and the specific flocculating agent used will dictate the required process parameters.
Where the interaction between the complexing agent and organic particles and components is relatively weak, addition of a base to raise the pH and thereby deprotonate the hydroxyl groups found in sugars and other polysaccharides and/or the addition of excess complexing agent to facilitate the complexing agent particles and components interaction may be advantageous. Where the interaction between the complexing agent and the organic particles and components is relatively strong, a lower pH and comparatively lower concentrations of metal ions can still produce the desired results. Additionally, mixtures of different complexing agents can also be employed to produce the disired interactions.
With the complexing agents now associated with the organic particles and components, the subsequently introduced flocculating agent will then also interact with the complexing agents associated with the organic particles and components. This interaction of the flocculating agent with the complexing agents then produces a large, neutral and substantially organic complex which is insoluble in the solution and which will more easily precipitate so as to assist in removing the organic content from the solution. As the flocculating agent precipitates the organic particles and components, it will also capture the other suspended solids such as silica, dirt, etc.
Different types of flocculating agents can be employed to produce the desired precipitation. Typically, large synthetic organic polymers may be used depending on the type and quantity of complexing agent used. Additionally, naturally occurring polymers, such as pectin, can also be used as a flocculent to provide an all “natural” process free of “man-made” chemicals.
With the organic particles and components now in the form of large precipitated floc, any number of conventional processes can be employed to facilitate removal of the precipitated particles. Additionally, the proper combination of added complexing agent and flocculating agent can be employed to produce a precipitate capable of use in animal feed, thereby reducing the quantity of material introduced into solid waste disposal systems or landfills.
With the organic particles and components and other suspended particles now precipitated and removed from the process stream, the process stream water can be legally discharged into the environment within government regulations, or else recycled or otherwise reused as desired within existing processes.
Accordingly, an object of the present invention is to create a process which produces readily removable precipitated organic particles and components and other suspended solids to facilitate these particles easy removal.
Yet another object of the present invention is to create a process which allow for the reuse and recycling of the water in process streams initially containing high amounts of organic particles and components by reducing the COD/BOD content, thereby facilitating recycling of the process stream and thereby reducing the net quantity of water required by a particular process.
It is a further object of the present invention to create a process which produces products which can be readily incorporated into animal feed.
It is yet another object of the present invention to create a process for removal of the COD/BOD content from water without adding additional contaminants to the water so as to not hamper disposal of the water into the environment.
It is yet another object of the present invention to create an all natural process for removal of the organic particles and components.
These advantages in addition to other objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The objects and advantages of the inventi
Hancock Robert D.
Tarbet Bryon J.
Zidek Jeffrey W.
Lawrence Frank M.
Power Engineering Company
Simmons David A.
Workman & Nydegger & Seeley
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