Chemistry: fertilizers – Processes and products – Bacterial
Reexamination Certificate
2003-03-04
2004-08-17
Sayala, C. (Department: 1761)
Chemistry: fertilizers
Processes and products
Bacterial
C071S008000, C071S009000, C071S010000, C071S015000, C071S021000, C071S034000, C071S061000
Reexamination Certificate
active
06776816
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a process for producing forms of magnesium ammonium phosphate (struvite) for various commercial applications to include slow-release fertilizer and possible crack repair in concrete. Fertilizer may be derived from a process for composting animal manure with a magnesium-rich compound and selected enzymes to which certain bacteria may be added to facilitate the production of a magnesium ammonium phosphate hydrate.
BACKGROUND
The formation of magnesium ammonium phosphate hexahydrate assisted by bacteria has been reported by Nabil Ben Mar et al.,
Chemosphere
, vol. 36, No. 3, p 475-481, (1998). The removal of phosphate from supernatant liquors of anaerobically digested sludge by formation of struvite (magnesium ammonium phosphate) is reported by Battistoni et al.,
Wat. Res
., Vol. 31, No. 11, pp. 2925-2929, 1997. The formation of struvite by Azobacter in chemically defined media has been described by Rivadeneira et al.,
Microbiol
. 30, 55-57 (1985).
U.S. Pat. No. 6,206,945 BI,
Method of Producing Artificial Guano
, to Weiss et al., Mar. 27, 2001, assigned to the same assignee as this patent and incorporated herein by reference, provides a much more complicated and costly multi-step process for precipitating magnesium ammonium phosphate than the instant invention. It involves mixing manure with soft-burned dolomite at elevated temperature, recovering ammonia thus liberated in an acid, neutralizing the mixture, combining the recovered ammonium salt with the mixture, adding guano-forming bacteria, and allowing the resultant mixture to ferment.
The '945 patent requires the following steps, each incurring expense avoided in the present invention:
a) water is added
b) carbon dioxide gas is added (and released, possibly being recaptured at additional expense)
c) high heat is generated, requiring more expensive containers
d) high alkalinity conditions require more expensive containers
e) a separate container and handling system is needed to handle the ammonia
f) acid must be supplied to mix with the ammonia
Further, work done by the present inventors indicates that magnesium ammonium phosphate need not necessarily be precipitated in large batches, but may also be suitable for “growing” in cracks in concrete. Ringelberg, David B. et al.,
Development of Techniques for Strengthening Deteriorated Concrete Using Bacterially
-
Precipitaied and Enzymatically
-
Precipitated Mineral Phases
, 22
nd
Army Science Conference, Baltimore, Md., pp. 17-18, 11-13 Dec. 2000.
The combination of complementing enzymes with added bacteria in an energy efficient, simplified, cost-effective and safe process in accordance with a preferred embodiment of the present invention accelerates the production of crystalline magnesium ammonium phosphate when compared to previous methods while also increasing yield as compared to previous methods.
SUMMARY
In general, an enhanced process produces struvite quicker and at higher yields than existing methods while employing energy efficient steps. In one embodiment, a basic form of the enhanced process yields an efficient fertilizer from animal excreta added to a mix that is then composted. The basic form of the process involves cost-effective measures of first determining the nitrogen content of the animal excreta, and then adding only that pre-specified amount of a magnesium compound to the animal excreta necessary to interact with the measured nitrogen content. Again using a cost effective means, the pH of the resultant mix is adjusted to within a pre-specified range of pH, followed by the addition of a pre-specified amount of at least one enzyme to the mix. Adding one or more enzymes increases the rate of breakdown of the urea and uric acid, thus getting ammonia production started earlier than would occur, with any existing bacteria alone. The resultant composted mix is maintained within a pre-specified temperature range, optimally requiring minimal added heat, for a pre-specified time. Pre-specified species of bacteria may then be added, providing a “booster” shot of enzymes as the bacteria grow and produce their own enzymes “internally.” Upon fulfilling these conditions, struvite is formed earlier in the composting process, and at higher yields, than it would be formed using processes heretofore available.
Preferred magnesium compounds include a magnesium carbonate and a magnesium hydroxide, and combinations thereof, in amounts between preferably about 1.5 and 2.0 parts, and more preferably of about 1.7 parts, of either of these magnesium compounds, or like compounds, or combinations thereof, per part of the nitrogen in the animal excreta. The enzyme, or enzymes, are added in the pre-specified amount of preferably between 0.25 and 0.75 g/l and most preferably at about 0.5 g/l (total enzyme mass) of the composted mix.
In another embodiment, the composted mix is inoculated with pre-specified species of bacteria after the enzyme (enzymes) is (are) added to the compost mix. These bacteria, through excretion of enzymes internal to them, further promote the formation of struvite as crystals outside the cell structure of the composted mix. These “internal enzymes” raise the pH of the composted mix, facilitating the added bacteria to become the dominant organism in the composted mix because of the elevated pH. These pre-specified species of bacteria also contribute to maintaining high levels of the added enzyme (or enzymes) and assure that the nitrogen and phosphorous are released on an accelerated timetable and struvite formed at higher yields than previously possible.
A preferred strain of these pre-specified bacteria is the species
Bacillus sphaericus
. In particular, a species of Bacillus designated Bacillus sp. SB1, derived from processing bat and seabird guano, has proven to be the optimum bacteria in terms of accelerating the formation process and increasing yield of struvite. However, bacteria that have been shown to facilitate the process may be any of
Bacillus sphaericus, Bacillus globisporus
, and
Bacillus fusiformis.
Enzymes may be an urease, an uricase (also known as urate oxidase), intermediates such as allantoinase and allantoicase (also known as allantoine amidinohydroiase) and a phosphatase or any combination of the non-phosphatase types and phosphatase, i.e., a phosphatase and any one or more of the other enzymes. The complete pathway for the conversion of uric acid to ammonia may be described as: uric acid conversion to allantoin (due to action of uricase)—allantoin conversion to allantoic acid (due to action of allantoinase)—allantoic acid conversion to urea (due to action of allantoicase)—urea conversion to ammonia (due to action of urease).
A preferred urease is jack bean urease. A preferred phosphatase enzyme is a 1000 units/microliter (&mgr;l) concentration of bovine alkaline phosphatase added to result in about 50 milliliter per liter (ml/l) of the composted mix after it has been mixed therein.
The pH may be adjusted within a preferred range of about 7-10 by simple aeration of the composted mix, while the mixture is maintained within a preferred temperature range of about 20-30° C. for a preferred period of about 10-20 days and more preferably for about 14 days.
Also provided as an embodiment of the present invention is a slow-release fertilizer that efficiently provides nitrogen and phosphorous as nutrients to plants. The fertilizer is produced, at least in part, by mixing animal excreta; a pre-specified amount of a magnesium compound, and a pre-specified amount of at least one enzyme, to comprise a composted mix having a cell structure. The composted mix is then maintained within a pre-specified range of pH and a pre-specified temperature range for a pre-specified time. As a result of this process, nitrogen and phosphorous precipitate from the composted mix in a precipitate comprising at least struvite. The preferred pH range for producing this fertilizer is about 7-10. The preferred temperature range at which the composted mix is maintained is about 20-30° C. The preferred period of compos
Malone Philip G.
Ringelberg David B.
Weiss, Jr. Charles A.
Baugher Jr. Earl H.
Sayala C.
The United States of America as represented by the Secretary of
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