Patent Application
20140017161
The present invention is directed to a method of production of certifiably organic ammonium sulfate for use as a fertilizer by aerobic composting of manure through highly selective bacterial action and without addition of external heat.
Aerobic and anaerobic composting of manure has been practiced by default for thousands of years. However, in recent years, concern for the environment and for pathogen control led to study and refinement of the composting processes. A commonly used composting method is anaerobic composting of manure with the intent of capturing the produced methane and marketing it to offset the costs of composting. However, the current anaerobic processes may release harmful gases such as methane and hydrogen sulfide into the air, and may not produce an organic fertilizer product. The U.S. Department of Agriculture has established requirements regarding preparing fertilizer in order to maintain an “organic” label certification on the fertilizer packaging. One of these requirements is to use only organic additives in the manufacturing process.
While the demand for fertilizer in general and organic fertilizer in particular increases, the farming community continuously strives to control ammonia emissions from enclosed rearing and living buildings commonly referred to as Concentrated Animal Feeding Operations (“CAFOs”). CAFOs have recently been identified as a major source of atmospheric pollution. Conventional agricultural wisdom has identified nitrogen in ammonia as a very unstable component of raw manure fertilizer, with as much as 50% of the nitrogen component of this type of fertilizer being lost into the atmosphere during aging and handling associated with manure application. In addition, CAFOs are faced with the problems of excessive amounts of manure on the farms and/or issues related to the smell of manure.
Therefore, a cost-effective method that uses ammonia and carbon dioxide for production of ammonium sulfate for use as fertilizer or as a stable form of ammonia for further conversion is of considerable commercial interest. Because anhydrous ammonia is manufactured from natural gas, the cost of the end product, ammonium sulfate, is driven by the cost of natural gas. Increasing demands for energy continues to result in increasing costs of the ammonium sulfate. The use of natural gas in fertilizer production instead of using it for heating or for other natural gas applications also reduces the amount of natural gas available for ammonium sulfate production.
As such, there is a need for a method to produce organic ammonium sulfate from captured ammonia and carbon dioxide found in a typical composting operation that is economical, energy efficient, is not harmful to the environment, and that utilizes only organic nitrogen and organic gypsum and produces an organic ammonium sulfate through highly selective bacterial action and without addition of outside heat. While a goal of conventional composting methods is to eliminate the majority of ammonia emissions and to retain a high nitrogen concentration in the compost for use as a fertilizer, a goal of the aerobic composting method according to the present invention is to convert substantially all of the nitrogen present in manure into ammonia and to capture and use the resulting ammonia to manufacture solid ammonium sulfate for use as fertilizer or as a stable form of ammonia for further conversion.
In accordance with the present invention, organic ammonium sulfate product is produced by aerobically composting a source of nitrogen, such as animal waste or manure mixed with a carbon source to create a biomass having a high solids content, through highly selective aerobic bacteria action without addition of external heat. Preferably, the production process includes the steps of providing a composting apparatus located inside a composting building such as a barn, a shed, or a greenhouse, housing a composting trench; placing the animal waste or manure preferably collected from a CAFOs facility in said composting trench; mixing said animal waste or manure with a source of carbon to form a biomass having a high solids content; providing aerobic bacteria and supplying said aerobic bacteria with water and oxygen in sufficient amounts to highly selectively convert the waste amino acids, proteins, uric acid and any other available nitrogen compounds from the biomass into NH3 and/or NH4 and CO2 without addition of external heat; moving said biomass down the composting trench as the aerobic composting process progresses; capturing the NH3 and/or NH4 and CO2 from the atmosphere of the composting apparatus in an aqueous solution; adding a source of sulfate to said aqueous solution containing captured NH3 and/or NH4 and CO2, and processing said aqueous solution containing a source of sulfate and captured NH3 and/or NH4 and CO2 to obtain ammonium polycarbonate and/or solid or concentrated liquid ammonium sulfate product. Preferably, the obtained ammonium sulfate product is certifiable as organic.
The invention may be more readily understood by referring to the accompanying drawing in which:
Like numerals refer to like parts throughout the several views of the drawings.
It will be appreciated that terms such as “front,” “back,” “top,” “bottom,” “left,” “right,” “horizontally,” “up,” “down,” and “side” used herein are merely for ease of description and refer to the orientation of the components as shown in the figures. It is to be understood that any orientation of the apparatus, and the components thereof described herein, is within the scope of the present invention.
In a preferred embodiment, the term “organic” as used herein is a labeling certification term that refers to an agriculture product produced in accordance with the Code of Federal Regulations (“CFR”) Title 7 (Subtitle B, Chapter I, Subchapter M, Part 205). As used hereinafter, “organic ammonium sulfate” is interchangeable with “ammonium sulfate,” “organic ammonium sulfate product,” and/or “product.” As used herein, “plurality” means “one or more.”
Referring to
In a preferred embodiment, composting trench 102 is from about 1 foot to about 10 feet deep; more preferably from about 2 feet to about 6 feet deep; and most preferably from about 4 feet to 5 feet deep. In a preferred embodiment, composting trench 102 is from about 50 feet to about 500 feet long; more preferably from about 100 feet to about 350 feet long; and most preferably from about 200 to about 300 feet long. In a preferred embodiment, composting trench 102 is from about 3 feet to about 25 feet wide; more preferably from about 5 feet to about 20 feet wide; and most preferably from about 8 feet to about 14 feet wide. In a preferred embodiment, the dimensions of composting trench 102 are as follows: about 4 feet deep, about 250 feet long, and about 10 to about 12 feet wide. In other embodiments, composting trench 102 may have dimensions greater than, less than, or different from those described above.
In a preferred embodiment, composting trench 102 is configured to hold from about 20 days to about 50 days of manure, and more preferably from about 25 days to about 30 days of manure. In other embodiments, composting trench 102 is configured to hold less than about 20 days of manure or greater than about 50 days worth of manure. In a preferred embodiment, composting trench 102 is configured such that the last few days of compost, preferably the last three days of compost, are covered. The cover captures gases that will be used for bioburden reduction and/or for killing the bacteria as the composting process ceases.
Referring to
Referring to
In a preferred embodiment, the temperature of the biomass does not exceed about 70° C. during the aerobic composting process according to present invention. Most preferably, the temperature of the biomass is kept between 50° C. and 70° C. In order to regulate the compost temperature, the heat generated by the aerobic composting process may be distributed as follows. For example, the aerobic composting process heats water in the pipes of heat conducting water system 112. These pipes may distribute heat up and down composting trench 102 by distributing hot water up and down composting trench 102. For example, hot water may be sent to any part of composting trench 102 via these pipes from a high temperature section of composting trench 102.
In a preferred embodiment, a hood may be used to capture rising water vapor and/or NH3 and/or NH4 and CO2 from the biomass as it generates heat. In yet other embodiments, in lieu of, or in addition to, using a hood to capture rising water vapor or NH3 and/or NH4 and CO2, at least a portion of the roof of composting building 104 may also be used. Preferably, the roof of the composting building 104 includes steep eaves or a narrowed roof area to allow a more efficient capture and removal of NH3 and/or NH4 and CO2 from inside composting building 104.
The present invention generally operates as follows. Manure is collected from a CAFOs facility on a continuing basis, as soon as feasible. Preferably, manure is collected from a CAFOs facility within 12 hours of production. The collected manure has a moisture content of about 70-80% by weight. A source of carbon is added, preferably at a ratio of manure to carbon source of about 3:2, resulting in a biomass with a moisture content of preferably about 30%-70% by weight. Most preferably, the resulting biomass has a moisture content of about 50% by weight. Preferably, the source of carbon is sawdust. Other sources of carbon may be used in lieu of, or in conjunction with, sawdust. In addition to providing a carbon source during the aerobic composting process, the nature of the carbon source may also provide porosity to the biomass, improving the speed and efficiency of the capture of composting gases.
According to an embodiment of the invention, the floor of a CAFOs facility containing manure may be washed periodically, and the water and manure may be collected in a containment pool. The containment pool is preferably enclosed or shielded, such that the NH3 and CO2 gasses from the manure composting process cannot escape into the environment. The shielding or enclosure of the containment pool preferably contains a suitable air handling system manufactured to withstand the corrosion associated with NH3 and CO2 gases, which is used to collect the NH3 and CO2 gasses and to transfer the collected NH3 and CO2 gasses to one or more collection tank(s) 201 which contain an aqueous solution. According to an embodiment of the invention, additional CO2 gasses may be collected from the atmosphere of the CAFOs facility by means of a suitable air handling system manufactured to withstand the corrosion associated with NH3 and CO2 gases. The CO2 gases collected from the atmosphere of the CAFOs facility are transferred via the air handling system to one or more collection tank(s) 201.
In a preferred embodiment, the source of carbon includes carbon to nitrogen in the ratio of at least about 6:1. In other embodiments, the volume/amount of manure and/or carbon source used in the input may vary, depending on, for example, the capacity of composting trench 102. In yet other embodiments, the carbon to nitrogen ratio of the source of carbon may be less than about 6:1 or greater than about 6:1. In yet other embodiments, an additional source of carbon may not be added to the manure, and the manure alone may be used in the composting process of the present invention.
Referring to
Temperature, pH and moisture content of the biomass are controlled by aeration of the biomass both by a physical moving and mixing process, and by the addition of O2 into composting trench 102. Within the biomass, the dissolved ammonia gas NH3 is in a chemical equilibrium with the NH4. The ratio of NH4 to NH3 in this equilibrium is pH dependent. Preferably, the pH of the biomass is controlled to keep the alkalinity level of the biomass high so that most of the NH4 in the biomass is converted to NH3 and released into the air, and not nitrified by the bacteria present in the biomass. Preferably, the pH of the biomass is also controlled so that the aerobic bacteria are not killed by the NH3 production. In a preferred embodiment, the pH of the biomass is between 8.0 and 10.1.
Each day's biomass may be moved once during the day, several times during the day, and/or continuously throughout the day. As the composting process commences, a rototiller may be used to mix/agitate and aerate the biomass. In other embodiments, other means of moving and/or aerating the biomass may be used in lieu, or in conjunction with, the rototiller. In yet other embodiments, biomass may not be added to the composting trench 102 daily, but may be added more often than that, or less often than that, i.e., every other day. In this manner, the next load of biomass may be added the same day as the previous load, or every other day. The amount of biomass and time intervals between each addition may vary.
In a preferred embodiment, O2 is added to the biomass during the aerobic composting process to facilitate the composting reaction. Preferably, the form of O2 addition is air. Preferably, the rate of O2 addition is determined by the temperature of the biomass. Preferably, O2 is added to any one or more of the day 1 to day 15 allotments of biomass. Preferably, the amount of O2 added over the length of composting trench 102 decreases. In this manner, preferably, the amount of O2 added on day 10 is less than the amount of O2 added on day 1. In other embodiments, other sources of O2 may be used and/or other means of controlling O2 addition may be used. Air ducts 106 may be used to regulate airflow. This may ensure that bacteria in the biomass receive an adequate supply of O2 to complete the composting process. In other embodiments, other means of regulating airflow, in lieu of, or in conjunction with air ducts 106, may be used.
Aerobic bacteria are provided to highly selectively convert all or substantially all of the waste amino acids, proteins, uric acid and any other available nitrogen compounds in the biomass into NH3 and/or NH4 and CO2. Preferably, the specific strains of aerobic bacteria used in the present invention include uricolytic bacteria such as Bacillus pasteurii and/or Peptostreptococcus anaerobius, Clostridium sticklandii, Clostridium aminophilum, and Eubacterium pyruvativorans. Thermophilic bacteria are preferred because their presence reduces the population of harmful bacteria such as E. coli, Salmonella and fecal coli-form bacteria. During the aerobic composting process, the biomass should remain at a temperature of 50° C. to 70° C. to promote the growth of thermophilic bacteria. The heat to maintain this temperature is supplied by the aerobic composting process and is distributed by heat conducting water system 112. Regular aeration of the biomass helps to regulate the temperature as well as supplies the oxygen to the bacteria. It is not necessary to add external heat to the aerobic composting process to manufacture ammonium sulfate according to the present invention.
As the aerobic process progresses, the aerobic bacteria highly selectively convert all or substantially all of the waste amino acids, proteins, uric acid and any other available nitrogen compounds in the biomass into NH3 and/or NH4 and CO2. The resulting NH3 and CO2 gasses are collected from the atmosphere of the composting building 100 by means of hood 114 and/or air flow ducts 106, or another suitable air handling system manufactured to withstand the corrosion associated with NH3 and CO2 gases. Preferably, the air handling system should be capable of changing the building volume of air in less than one hour.
Referring to
The captured NH3 and/or NH4 react with the aqueous solution in collection tank(s) 201, and are converted to ammonium hydroxide. The ammonium hydroxide reacts with captured CO2 to form ammonium polycarbonate. Preferably, the process is allowed continued until the pH in the collection tank(s) 201 reaches 8.5 to 9.35. Preferably, the process is allowed to continue until the concentration of ammonium polycarbonate in the aqueous solution of the collection tank(s) 201 reaches a concentration of between 1,600 ppm and 4,500 ppm as measured with an electrical conductivity meter.
In the preferred embodiment, after the concentration of ammonium polycarbonate in the aqueous solution of the collection tank(s) 201 reaches a concentration of between 1,600 ppm and 4,500 ppm, the aqueous solution containing ammonium polycarbonate, ammonium hydroxide and CO2, is removed from the collection tank(s) 201 through a piping system 203, and is transferred to one or more pre-osmosis holding tank(s) 204. In order to increase the concentration of the ammonium polycarbonate in the aqueous solution, the aqueous solution containing ammonium polycarbonate, ammonium hydroxide and CO2 is transferred from pre-osmosis holding tank(s) 204 to one or more reverse osmosis devices 206 through piping system 205. The reverse osmosis devices may include a DOW™ FILMTEC™ XLE-440 reverse osmosis membrane, or a similar reverse osmosis membrane. The reverse osmosis process allows water to be removed from the aqueous solution resulting in a more concentrated ammonium polycarbonate solution. The removed water is transferred from reverse osmosis device(s) 206 through a piping system 207 to a water holding tank 208, and may be reused in the process or discarded. The reverse osmosis process may be repeated as necessary to increase the concentration of the ammonium polycarbonate in the aqueous solution. In other embodiments, the reverse osmosis process may be replaced by other processes suitable for increasing the concentration of the ammonium polycarbonate solution in the aqueous solution, or it may be omitted.
The aqueous solution containing concentrated ammonium polycarbonate is transferred from reverse osmosis device(s) 206 through a piping system 209 to one or more reaction tank(s) 210. Sulfate 301 is added to reaction tank(s) 210 at a ratio of approximately 5 pounds of sulfate for each 1 gallon of ammonia solution. Preferably, the source of sulfate 301 is Organic Materials Review Institute (“OMRI”) certified organic gypsum. According an embodiment of the present invention, in order to improve the yield of ammonium sulfate, excess sulfate 301 may be added to reaction tank(s) 210, at a ratio of approximately 6 pounds of sulfate for each 1 gallon of ammonia solution.
The temperature of the aqueous solution containing concentrated ammonium polycarbonate and sulfate 301 in reaction tank(s) 210 is raised to 50° C. or allowed to rise to 50° C. due to the chemical reaction between the ammonium carbonate and sulfate 301. During the initial reaction period (preferably four hours), the aqueous solution containing concentrated ammonium polycarbonate and sulfate 301 is mixed and circulated inside reaction tank(s) 210, resulting in the formation of ammonium sulfate suspension 401 and calcium carbonate. The pressure may be allowed to increase in the reaction tank(s) 210 in order to increase the rate and yield of ammonium sulfate. Preferably, the pressure is allowed to increase to two atmospheric pressures or greater. Calcium carbonate is allowed to settle to the bottom of reaction tank(s) 210 in the form of the calcium carbonate sludge. In a preferred embodiment, the calcium carbonate sludge is removed from reaction tank(s) 210 through a floor drain and a piping system 211 to one or more bag filters 212 which capture the calcium carbonate sludge. The resulting captured calcium carbonate sludge can be recovered and used as a separate product for various agricultural and non-agricultural purposes.
After the initial reaction period (preferably four hours), the aqueous solution containing concentrated ammonium polycarbonate, sulfate 301 and ammonium sulfate suspension 401 is moved from reaction tank(s) 210 through a piping system 213 to one or more holding area tank(s) 214, where the presence of unreacted sulfate 301 in said aqueous solution allows the formation of ammonium sulfate suspension 401 to proceed for an additional period of time, preferably for more than 5 days. Most preferably, the formation of additional ammonium sulfate suspension 401 in holding area tank(s) 214 is allowed to proceed for a period of 10 days.
According to an embodiment of the invention, the resulting ammonium sulfate suspension 401 may be centrifuged to remove excess water in order to concentrate the ammonium sulfate suspension 401 to a desired density for use as a liquid fertilizer. In other embodiments, the centrifugation process may be replaced by other processes suitable for increasing the concentration of the ammonium sulfate suspension 401. According to an embodiment of the invention, the ammonium sulfate suspension 401 may be dried to form crystals of dry ammonium sulfate. The resulting liquid or dry ammonium sulfate is certifiable as organic. The term “organic” as used herein, is a labeling certification term that refers to an agriculture product produced in accordance with the Code of Federal Regulations (“CFR”) Title 7 (Subtitle B, Chapter I, Subchapter M, Part 205).
The foregoing embodiments are merely examples of the present invention. Those skilled in the art may make numerous uses of, and departures from, such embodiments, without departing from the scope and spirit of the present invention. Accordingly, the scope of the present invention is not to be limited or defined by such embodiments in any way, but rather, is defined solely by the following claims.
