Technical Field: This invention relates generally to a method of treating organic materials, such as manure, to create a plant food and soil conditioner. More specifically, the invention relates to the sequential treatment of organic materials with an acid and then a base while simultaneously introducing steam into the admixture.

Background Art: Man has used organic materials such as manure as fertilizers for years. More recently these organic materials have been pre-treated in one fashion or other to create better nutrient balanced, less odoriferous fertilizer compositions.

For example, U.S. Patent 4,743,287 to Robinson (May 10, 1988) discloses a humic acid fertilizer and method of making it. Robinson's method involves the use of a sealed reactor system, wherein orgamc material, water, and certain inorganic elements are mixed with, for example, an acid, to accomplish hydrolysis and a drastic change in pH, raising both the mix temperature and pressure. The mix is then subsequently mixed with a base, to provide a further temperature and pressure increase. The inorganic elements are added initially so that they may be available for humic acid bonding to the hydrolyzed organic molecules.

As can be determined by scratinizing Robinson's process, the organic material is dried and composted resulting in a relatively expensive, time-consuming process. Also in Robinson's process, relatively high concentrations of sulfuric acid are used to achieve hydrolysis. For example, EXAMPLE I of Robinson indicates the use of an 8% sulfur content which works out to be 73 kg of sulfur per 0.4 hectare if 0.4 hectare is treated with 909 kg of humic acid fertilizer. This amount of sulfur can become significant if the fertilizer is repeatedly applied on an annual basis. Robinson also reports a maximum of 30% water content in his process which takes place in a closed vessel to prevent the loss of ammonia vapors.

Later work attributed to Robinson is described in European Patent publication numbers 428,014 A2, 428,014 A3, 428,015 A2, and 428,015 A3, published on May 22, 1991.

-__- DISCLOSURE OF THE INVENTION

The invention includes a method of treating organic material which includes the steps of (1) admixing, for a time, the organic material with water and an acid, the acid equivalent to 5 to 12% by total weight of the end product (or 5- 20% of the dry weight of the organic material) 100% sulfuric acid (e.g. 5.4 to 21.5% by weight 93% sulfuric acid); (2) increasing the pH of the admixture, while simultaneously introducing steam (steam is preferably introduced in an amount of between about 0.01 % up to about 5% by total weight of the admixture); and (3) heating and drying the resulting admixture. In some embodiments of the invention, steam is preferably introduced in an amount of between about 0.01 % up to about 5 % by total weight of the dry weight of the organic material of the admixture. "Dry weight" of the organic material refers to the total weight of the organic material less the weight of the water content. The pH may be increased in the second step of the method by adding a base to the admixture. The resulting material makes excellent dried plant food, fertilizer, or soil conditioner which has sustained release properties.

The inventive process can be modified somewhat. For example, during the first step (i.e. the acid addition step), steam may be introduced during the mixing process in an amount sufficient to raise the total moisture content to greater than about 40% by weight of the admixture of the first step. Also, during the first step, calcium carbonate such as dolomite may be included in the admixture. If such is included in the first step, some decarbonation of the material will take place.

After the step during which the pH is increased, nutrients may be added to the admixture. Such nutrients include lime, dolomite, rock phosphate, potash, ammonium nitrate, urea, soil clays, vermiculite, forms of commercial nitrogen, and mixtures thereof.

The resulting material can be granulated, extruded or pelletized and dried for ease in storage or administration. One advantage of the method is that the organic material need not be previously composted before use with the process saving both time and labor. The inventive method acts to decrease the amount of microbial growth in the resulting mixture yielding a better shelf-life.

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The invention has the ability to accommodate for the availability of various raw materials locally (e.g. the ability to use composted or non-composted organic materials, and the ability to include additions which are needed for a local soil condition), meet the needs of various soil conditions in terms of soil tilth, oxygen uptake and improved water retention, and results in a fertilizer having different release rates and times of release for various plant nutrients.

BEST MODE OF THE INVENTION

A. Acidification: First, the weight of the organic material is preferably determined.

Next the relative amounts of acid and water (e.g. steam) to adjust the moisture content to at least 40% are then determined. These ingredients are then admixed in a preferably open container, and allowed to mix together for one to three minutes. Carbonate-free calcium may be added to the ingredients. Steam may be injected to wet the reacting components if the total mixture is less than 40% water by weight. A moisture content of the admixture of the first step (including any steam) of 40 to 45 % is preferred.

If the resulting material is to be added to alkaline soil, calcium carbonate can be added to the organic material of the first step. If the acid is totally consumed during the process, more acid or another acid such as nitric acid may be added to the admixture any carbonate present. If the product is to be applied to an already alkaline soil, calcium and magnesium in the form of magnesia containing lime or dolomite may be added to the admixture of the first step, a reaction then occurs between the acid and the lime or dolomite, generating carbon dioxide. This reaction tends to produce an improved product if the resulting material is to be applied to alkaline soils, since bicarbonate tends to tie-up trace elements when applied to alkaline soils.

Alternatively, for application to acidic soils, carbonates can be preserved by adding dolomite to the admixture after the step of increasing the pH of the admixture.

Either composted or non-composted organic materials may be used in the process. As used herein, "organic materials" include materials such as livestock and poultry manure, sewage sludge, cotton gin trash, cannery wastes, lawn

clippings, food wastes, carbon from pyrolysis and cellulose. Some raw non- composted organic waste materials may contain as much as 80% water (i.e such materials would have a dry weight of 20% of their total weight).

Ionic reactions, including acid-base reactions, have been found to proceed best in a 40-45% water environment. Below a water content of 40% by weight of the admixture of the first step, the chemical reactions and nitrogen uptake apparently proceed less efficiently. Above a water content of 45 % by weight of the admixture, the chemical reactions proceed, but product formation is more difficult since more drying of the admixture resulting from the process is necessary. By selecting a mixture of high water organic wastes (up to 85 % water in the case of sludge) and drier wastes such as mint straw (20% water), chicken manure (20-45% water), and dairy manure which can range from 20 to 75% water, it has been found that a water level of 40-45 % can be achieved.

Steam provides the best method of adding a nώiimum of additional water to support the acid-base reactions desired in the inventive process. Previous attempts of just adding additional water to promote these reactions made the mixture much wetter, expensive to dry, and difficult to extrude and form directly out of the reactor. Steam helps to efficiently achieve the desired reaction and a continual batch process. Preferred organic materials are free of heavy metals and other toxic substances.

Steam, super heated steam, water, or a mixture thereof is used as the source of additional water in the process. Steam may be 5 % of the total minimum water. Steam increases the reaction temperature, can melt frozen organic materials, provides a medium for salt formation from acid-base reactions; scrubs off the gases emitted during the reaction, and appears to increase the efficiency of the chemical reactions. Boilers capable of producing super-heated steam are available from Mechanical Services of Yalrima, Washington.

Acids for use in the invention include sulfuric acid, nitric acid, hydrochloric acid, acetic acid, phosphoric acid, citric acid, and mixtures thereof. The amount of acid added will typically be equivalent to 5-12% or less of sulfuric acid (and preferably less than 10% by total weight of the end product 100% sulfuric acid).

B. Increasing the pH:

Next, the pH is adjusted upwards (from 0.5-1.5 to 6.5-7.5) by adding a basic material such as anhydrous ammonium, or potassium hydroxide, while steam is simultaneously introduced (e.g. injected) into the mixture. This phase of the reaction takes place in 1 to 2 minutes. The admixture increases in temperature during this step. The steam, besides increasing the temperature of the admixture, acts as to "scrub" the gas emissions exiting the reactor or mixer. For example, ammonia is absorbed by the steam, incorporated into the admixture, and its release into the atmosphere is greatly diminished. Steam also acts to provide water immediately, evidently acting to enhance the reaction, and increases the temperature of the reactants which is of special assistance when the organic material to be treated is cold or frozen.

Also of importance, the steam helps provide water throughout the acidified biomass to support the following reaction: NH ₃ + H ₂ O -> NH ₄ OH

Then,

2 NH ₄ ⁺ + H ₂ S0 ₄ -> [NH ₄ ] ₂ SO ₄ the common fertilizer ammomum sulfate.

The rapid pH change is believed to cause destruction of colloidal suspensions, freeing up water contained within the organic material, which greatly aids in subsequent drying of the products, as well as in the disinfection of the product. When the product is tested for humic acid, it is shown that very little humic acid remains (less than 2% by weight).

The process in this regard is believed to be of sufficient strength to provide for organic colloidal destruction, freeing bound water and destroying micro¬ organisms.

C. Addition of nutrients:

After the acid-base reaction has been completed, dry sterile nutrients are preferably added to the admixture. Such nutrients are those used to balance out the soil to which the fertilizer will be applied. "Nutrients" as used herein include typical ingredients such as lime, dolomite, calcite, hydrobiotite, gypsum, rock phosphate, ammomum phosphate, potash, calcium peroxide, humic acid, ammomum nitrate, urea, trace minerals, or mixtures thereof.

Although not nutrients in the traditional sense, various soil clays of the medium and high water expansion types may also be added after the step in which the pH is increased. These soil clays include the 2:1 lattice crystals, such as vermiculite, that have an affinity for ammonia, potassium ions, magnesium ions, calcium ions, and other trace minerals. The clays may be pre-treated, dried and then added with other dried minerals (e.g. bentonite).

Ground paper (e.g. newspaper) may be added to the mixture to decrease the overall moisture content.

D. Heating: The mixture, after completion of the previously described processing, is preferably at a temperature of 72-82 °C (160-180 °F). At this time, the material should be about 30% moisture, which is ideal for forming granules. The resulting admixture can also be peUetized or extruded depending upon the desired form and moisture conditions. The granules are then heated to approximately 200 °C (400°F). This step in the process typically lasts 10-15 minutes and reduces the moisture content of the material to 7-10% for storage.

E. Constituent ratios:

Once produced, a preferred fertilizer according to the invention should have a complete and balanced formulation, being at the same time non-toxic while meeting the soil and the plant's needs for a growth cycle. This balance will depend on various factors such as the soil condition and content where the product is to be applied, the particular crop or vegetation to be grown, and the water requirements of the local area. A computer analysis (adapting a standard computer spread sheet program) contrasting soil condition with crop needs may be used in this regard. The invention thus also allows for the production of customized fertilizer. The resulting products will typically contain 4-6% nitrogen, and a calcium to magnesium ratio of 6-15: 1. Potassium, phosphorus, potash, calcium, magnesium, sulfur, and trace mineral ratios can be readily calculated. For sustained release, NO ₃ releases first, followed by other nitrogen forms generated from the ammonia about two weeks later. Then organic forms of nitrogen release in about a month due to bacterial degradation of the product. The clay particles slowly release whatever nitrogenous compounds they contain over a period of time.

When sulfuric acid is the acid used in the process, a maximum of 10% sulfur (by weight) is used in the reaction, which will result in an end analysis of 3.4% sulfur or 34 grams per kilogram of material ( 68 lbs. per ton of material), which is much closer to natural conditions than is that of the prior art. While not intending to be bound by one theory of the invention, the following may help those of skill in the art to understand the results described herein.

By using an acid and a carbonate of calcium or magnesium: Acid + (CaCO ₃ or MgCO ₃ ) — > calcium or magnesium salt + CO ₂ . The release of carbon dioxide increases the surface area of the resulting particles. This increased surface area allows for greater exposure of the biomass to the reaction conditions to the ionic environment at a reduced moisture content, resulting in a greater diffusion of ions into the organic material which, among other things, helps to disinfect the product. The invention is further explained by the following illustrative examples:

EXAMPLES Example I Method of production In an open 2.2 cubic meter mixer, 580 kg (1280 lbs.) of uncomposted manure (60% water) was mixed with 45 kg sewage sludge (84% water), 372 kg mint straw (20% water), 45 kg waste paper (0% water) and 98 kg of H ₂ SO ₄ (93%) for three minutes. Subsequently 31 kg of anhydrous ammonium was added to the admixture while, simultaneously 3 % steam (by total weight of the admixture) was injected into the admixture. The resulting admixture was mixed for three minutes. At this time 22 kg of dolomite, 68 kg potash, 11 kg urea and 98 kg of rock phosphate were added to the mixture, and the components allowed to mix for several minutes. The admixture was then analyzed, and it showed a nearly complete uptake of ammonia, with a strep fecalis count of 17 MPN/100 grams, carbon to nitrogen was 17:1, and humic acid analysis showed 0.07% (California method of testing). After the addition of dry nutrients, the moisture content was 35%.

Afterwards, the material was passed to a meter box, then into a drum priller and finally a dryer. The material was then rolled into small granules (1 mm diameter). The drum priller then converts into a tube dryer where the granules were heated to 204° C (400°F). The product then exits the tube dryer, and passes through a rotating trammel screen where the particles were sorted by diameter. The fines were then passed through a gear extruder.

Example π -

A side-by-side growth comparison was done for vegetables comparing:

(A) commercially available chemical fertilizer (Ortho).

(B) the fertilizer produced by the process of Example I, sans calcium and magnesium; and

(C) the fertilizer produced by the process of Example I (i.e. having 6% calcium and 1 % magnesium).

The NPK of all three fertilizers were otherwise the same. The soil was acidic and had good existing organic matter. No significant difference could be seen between a variety of garden plants grown with the fertilizers of Example π.A. and Example π.B. However, the vegetables of Example π.C. exceeded those of Examples π.A. and π.B. in quantity in an amount varying from 20 to 35 % . The plants treated with the product of Example π.C. were much more vigorous, and displayed increased stem strength, better nutrition, and disease resistance than were the plants treated with the products of Example π.A. and π.B. This pattern was consistent throughout the plot testing.

Example HI - Addition of third step:

The process of Example I was repeated, except that the 22 kg of dolomite was added to the orgamc material of the first step (pre-acid addition), and a 2:1 crystal clay (i.e. vermiculite) was added to the reactor during the step wherein the nutrients were added.

The vermiculite was previously treated with super heated steam and anhydrous ammonia to impregnate the crystals with ammomum (5%). The product was dried, then added to the reaction mixture.

Example IV -

A similar test to EXAMPLE _H was run using a dry, composted biomass (559 kg compost (17% water), 1 kg paper, 98 kg 93% sulfuric acid). Water (114 kg) was added to bring the total moisture to 30% prior to injection of ammonia (34.5 kg). No steam was injected. Dolomite (22.7 kg), potash (68 kg), urea (11.4 kg), rock phosphate (91 kg), and vermiculite (45 kg) were added. It was observed that the mixture did not retain the ammonia within the open air vessel with nearly 50% less nitrogen in the final product. It was assumed that insufficient moisture and elevated temperature created conditions contrary to the facilitation of the reaction of water and ammonia to ammonium hydroxide, thus ultimately reducing the concentration of ammonium sulfate. Bacteria counts were also 2.4 x 10 ⁶ MPN/100 g indicating a lack of disinfection.

Example V

A fertilizer was made by a method similar to that of Example _H, except for substituting the following amounts of ingredients where appropriate:

582 kg (1280 lbs.) of manure (60% water),

373 kg (820 lbs.) mint straw (20% water),

6.8 kg (15 lbs.) waste paper (0% water),

98 kg (216 lbs.) H ₂ SO ₄ (93%) (7% water), 22.7 kg (50 lbs) steam,

29.5 kg (65 lbs.) anhydrous ammomum (1 % water),

23 kg (50 lbs.) dolomite (1 % water),

68 kg (150 lbs.) potash (1% water),

16.8 kg (37 lbs.) urea (1 % water), 91 kg (200 lbs.) rock phosphate, and

45 kg (100 lbs.) vermiculite.

Example VI

A fertilizer was made by a method similar to that of Example I, except for substituting the following amounts of ingredients where appropriate: 582 kg (1280 lbs.) of manure (60% water), 355 kg (780 lbs.) mint straw (20% water), 45 kg (100 lbs.) H ₂ SO ₄ (93%) (7% water), 34 kg (75 lbs) steam, 15.4 kg (34 lbs.) anhydrous ammonium, 34 kg (75 lbs.) dolomite, 159 kg (350 lbs.) potash, and

118 kg (260 lbs.) rock phosphate.

References herein to specific Examples or embodiments should not be interpreted as limitations to the invention's scope which is determined by the claims.