Food or edible material: processes – compositions – and products – Products per se – or processes of preparing or treating... – Animal derived material is an ingredient other than extract...
Reexamination Certificate
2000-03-01
2001-05-22
Sayala, Chhaya D. (Department: 1761)
Food or edible material: processes, compositions, and products
Products per se, or processes of preparing or treating...
Animal derived material is an ingredient other than extract...
C426S480000, C426S481000, C426S489000, C426S495000, C426S805000, C426S807000, C210S749000
Reexamination Certificate
active
06235339
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to methods of treating organic waste streams, and more particularly to a method of treating the waste stream of an animal processing plant to recycle the fat, blood, tissue and other organic solids typically found in the stream.
BACKGROUND OF THE INVENTION
It is well known that meat-processing plants generate significant amounts of solid organic waste material daily, and that the waste from such plants can be difficult and expensive to treat. Meat processing plant waste streams typically contain blood, fat, muscle, bone, and intestinal contents, mixed into many gallons of wash-down water. Thus, the waste effluent may potentially contaminate water supplies if not properly treated, and the amount of organic matter lost through that treatment may be large.
For economic as well as environmental reasons then, many meat-processing facilities strive to reclaim solid organic material from the processing stream. As indicated above, the removal of organic waste is critical from an environmental standpoint, and in fact both federal and municipal governments typically place tight restrictions on the total dissolved solids, chemical oxygen demand (COD), biological oxygen demand (BOD) and total organic carbon (TOC) of water discharged into local sewers, rivers, or municipal wastewater treatment plants.
To comply with these standards, waste material is typically treated with industrial strength FeCl
3
followed by the addition of cationic or anionic polymers to induce flocculation and facilitate subsequent solids removal. This process generally occurs at a low pH of about 6.
While the above process is generally effective to decontaminate the water, the removed solids have not been shown to have any independent commercial value. In particular, the removed solids have not been accepted as an animal feed ingredient due to the fact that many animals refuse to eat feeds containing significant amounts of FeCl
3
. Consequently, the removed organic solids are typically transported to and deposited in a landfill. Not only does this entail significant transportation and dumping costs, but this practice results in the continued buildup of already overcrowded landfills.
A need therefore exists for a process that removes organic material from waste streams while simultaneously creating a product with independent commercial value. The present invention addresses that need.
SUMMARY OF THE INVENTION
Briefly describing one aspect of the present invention, there is provided a method of treating an organic waste stream to substantially remove solid organic matter from the stream. The preferred method comprises substituting MgCl
2
(and sometimes a small amount of AlCl
3
) for the FeCl
3
that previously has been added to a processing plant waste stream, and adjusting the pH to at least about 7.0. Polymeric flocculents are then added as they were in the prior art, and the solid precipitate is removed by centrifugation.
The removed organic matter finds utility as an animal feedstuff, thus minimizing waste disposal problems while simultaneously generating a product with commercial value.
One object of the present invention is to provide a method of treating a waste stream that avoids the addition of large amounts of FeCl
3
.
A further object is to provide a method that reduces the BOD level of the clarified liquid to less than 800 ppm.
Further objects and advantages of the present invention will be apparent from the following description.
DESCRIPTION OF THE PREFERRED EMBODIMENT
For the purposes of promoting an understanding of the principles of the invention, reference will now be made to preferred embodiments and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications of the invention, and such further applications of the principles of the invention as illustrated herein, being contemplated as would normally occur to one skilled in the art to which the invention relates.
As briefly described above, the present invention provides a method for removing organic mater from a waste product stream. The waste stream can contain plant or animal matter. Most typically, the waste stream contains organic animal matter such as blood, fine bone, muscle, etc, from a food-animal packing plant. As will be appreciated by persons skilled in the art however, other organic waste streams may be treated by the present invention.
The effluent from a meat packing plant typically contains organic animal matter in concentrations of 0.3% to 3% (or even more), with concentration of about 1% being most common. The present method is applicable throughout this entire concentration range, with the amounts of the various components being adjusted according to the particular waste stream involved. It is appreciated that it is difficult to determine and/or control the concentration or makeup of solids in a plant effluent stream, and those skilled in the art recognize that fluctuations are normal. The following method and amounts may be altered to account for fluctuations from the typical range.
In one aspect of the present invention two salts are used to replace (in whole or in substantial part) the FeCl
3
used in the prior art. The first of those salts is a soluble magnesium salt, which is dissolved in the organic waste stream. The Mg salt is provided in an amount effective to induce flocculation of organic material when used in conjunction with the other materials. Preferably the magnesium salt is MgCl
2
.
In the preferred embodiments between 1 L and 10 L of technical grade MgCl
2
(approximately 32% MgCl
2
solution) per 1000 L of effluent is added to the aqueous waste stream. Between 2.0 and 4.0 L per 1000 L of effluent is even more preferred, although no adverse effects other than economic waste result from the addition of larger amounts of magnesium compound. In other preferred embodiments MgCl
2
is added to provide between about 0.5-5.0% MgCl
2
by volume of waste material, with 0.75% to 1.5% MgCl
2
being more preferred.
In some embodiments combinations of waste stream components flocculation is enhanced when a small amount of minute quantities of a soluble aluminum-based compound (preferably an aluminum salt) is dissolved into the effluent in addition to the MgCl
2
. Many aluminum salts can be used, with AlCl
3
, alum, aluminum chlorohydrate, sulfonated PAC (aluminum chloride and acrylamide), and aluminum sulfate being most effective in testing to date. AlCl
3
is most preferred.
As with the magnesium compound, the aluminum salt is provided in an amount effective to induce flocculation in conjunction with MgCl
2
and polymer addition. Generally, an effective amount is between about 0.05% and about 0.25% aluminum salt (w/v). When a 50% solution is used, about 0.1 L to about 0.5 L per 1000 L of effluent is preferred, although as with the MgCl
2
, somewhat greater amounts may be required for a particular waste stream.
The addition of the aluminum salt may lower the pH of the solution to 6.0 or less, but it is preferable to elevate the pH to above 7.0. More preferably the pH should be about 8.0, with a pH of between about 9 and about 10 being preferred with certain waste streams. Any base may be used to elevate the pH, with NaOH working quite effectively in testing to date. Typically, approximately 0.5-2 L of NaOH (50% solution caustic soda) is needed per 1000 L of effluent, with the specific amount varying with the organic waste stream being treated. As is known to the art, the pH should be monitored to ensure the appropriate level. In certain preferred embodiments the pH is kept slightly below 9 to avoid damaging equipment used in the process.
The solution thus made is preferably agitated to induce complete mixing of the salts with the waste stream. Any type of mixing apparatus may be used, as is known to the art.
To the foregoing solution is added a polymeric flocculent in an amount effective to flocculate the solid organic matter
Barlow Stacey L.
Harmon Bud G.
Purdue Research Foundation
Sayala Chhaya D.
Woodard Emhardt Naughton Moriarty & McNett
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