U.S. patent application number 12/064603 was filed with the patent office on 2010-10-07 for process for the treatment of substrate-variable methane emissions.
This patent application is currently assigned to Newlight Technologies, LLC. Invention is credited to Markus Herrema, Kenton Kimmel.
Application Number | 20100255540 12/064603 |
Document ID | / |
Family ID | 37771900 |
Filed Date | 2010-10-07 |
United States Patent
Application |
20100255540 |
Kind Code |
A2 |
Herrema; Markus ; et
al. |
October 7, 2010 |
PROCESS FOR THE TREATMENT OF SUBSTRATE-VARIABLE METHANE
EMISSIONS
Abstract
The invention relates generally to a system and method the
treatment of substrate-variable gaseous emissions comprising
dynamic concentrations of organic materials comprising methane and
one or more non-methane organic compounds that can be metabolized
by methane-oxidizing microorganisms, and in one specific
embodiment, to a system and method for the treatment of
substrate-variable methane emissions through the use of
methanotrophic microorganisms in a species-universal polymer
production process. Certain embodiments of the invention are
particularly advantageous because they reduce
environmentally-destructive methane emissions and produce
harvestable end-products.
Inventors: |
Herrema; Markus; (Laguna
Niguel, CA) ; Kimmel; Kenton; (Dana Point,
CA) |
Correspondence
Address: |
KNOBBE MARTENS OLSON & BEAR LLP
2040 MAIN STREET
FOURTEENTH FLOOR
IRVINE
CA
92614
UNITED STATES
949-760-0404
949-760-9502
efiling@kmob.com
|
Assignee: |
Newlight Technologies, LLC
2973 Harbor Blvd., #770
Costa Mesa
CA
92626
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20080241886 A1 |
October 2, 2008 |
|
|
Family ID: |
37771900 |
Appl. No.: |
12/064603 |
Filed: |
December 29, 2005 |
PCT Filed: |
December 29, 2005 |
PCT NO: |
PCTUS2005047415 |
371 Date: |
February 22, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11/208,808 |
Aug 22, 2005 |
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12064603 |
Feb 22, 2008 |
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10/687,272 |
Jan 3, 2006 |
6982161 |
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11/208,808 |
Aug 22, 2005 |
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60/721,938 |
Sep 29, 2005 |
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60/603,857 |
Aug 24, 2004 |
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Current U.S.
Class: |
435/71.1 ;
435/135; 435/189; 435/289.1; 435/41 |
Current CPC
Class: |
F02D 41/0087 20130101;
F02D 35/025 20130101; A61K 35/42 20130101; C12P 7/62 20130101; Y02E
50/30 20130101; C12P 7/42 20130101; C12N 1/30 20130101; B01D
2258/05 20130101; C08G 63/06 20130101; C12N 1/38 20130101; F02D
17/02 20130101; Y02E 50/343 20130101; C12N 9/0073 20130101; A61K
38/05 20130101; Y02E 50/346 20130101; C12P 7/625 20130101 |
Class at
Publication: |
435/071.1 ;
435/041; 435/135; 435/189; 435/289.1 |
International
Class: |
C12P 21/04 20060101
C12P021/04; C12P 1/00 20060101 C12P001/00; C12P 7/62 20060101
C12P007/62; C12M 1/00 20060101 C12M001/00; C12N 9/02 20060101
C12N009/02 |
Claims
1-35. (canceled)
36. A method of directing a plurality of microorganisms to produce
a single type of harvestable polymer, the method comprising:
providing a gaseous emission, wherein said gaseous emission
comprises methane, one or more non-methane organic compounds, and a
plurality of methanotrophic microorganisms that metabolize said
methane and said non-methane organic compounds; providing a
microorganism growth-culture medium, wherein said medium comprises
one or more growth-culture compounds; exposing said gaseous
emission to said growth-culture medium over a course of time,
wherein the concentration of at least one of the methane and the
one or more non-methane organic compounds within said emission is
variable, wherein said methanotrophic microorganisms use at least a
portion of said methane as a source of carbon or energy to
inoculate said medium to create a naturally-equilibrating
consortium; and varying the concentration of said one or more
growth-culture compounds to cause substantially all of said
methanotrophic microorganisms within said medium to generate a
single type of polymer, thereby directing a plurality of diverse
microorganisms to produce a single type of harvestable polymer.
37. The method of claim 36, wherein said single type of polymer
consists essentially of polymers that are structurally similar.
38. The method of claim 36, wherein said single type of polymer
consists essentially of polymers that are functionally
equivalent.
39. The method of claim 36, further comprising adding additional
methanotrophic microorganisms to said medium.
40. The method of claim 36, wherein said plurality of
methanotrophic microorganisms comprise at least two different
species of methanotrophic microorganisms.
41. The method of claim 36, wherein said polymer is selected from
the group consisting of one or more of the following:
polyhydroxyalkanoate (PHA), polyhydroxybutyrate (PHB),
polyhydroxybutyrate-valerate (PHB/V), methane monooxygenase, and
single cell protein.
42. The method of claim 36, wherein the step of varying the
concentration of said one or more growth-culture compounds
comprises reducing or eliminating copper.
43. The method of claim 36, wherein said one or more growth-culture
compounds are selected from the group consisting of one or more of
the following: nitrogen, copper, magnesium, phosphorus, oxygen,
carbon, potassium, and iron.
44. The method of claim 36, further comprising removing impurities
from said gaseous emission.
45. The method of claim 36, wherein said gaseous emission comprises
methane at a concentration in the range of about 0.1% to about
60%.
46. The method of claim 36, wherein said gaseous emission is
generated by a system selected from the group consisting of one or
more of the following: coal mine, wastewater treatment operation,
agricultural digester, enclosed feedlot, petroleum transport
system, petroleum recovery system, landfill, ruminant animal, and
compost facility.
47. The method of claim 36, wherein said methanotrophic
microorganisms comprise at least one of a naturally-occurring or
genetically-modified microorganism that uses methane as a source of
carbon or energy for growth or reproduction.
48. The method of claim 36, wherein said one or more non-methane
organic compounds are partially or fully metabolized by one or more
said methanotrophic microorganisms.
49. The method of claim 36, wherein said one or more non-methane
organic compounds are partially or fully oxidized by one or more
said methanotrophic microorganisms.
50. A system for directing a plurality of microorganisms to produce
a single type of harvestable polymer, comprising: a source of
gaseous emissions, wherein said gaseous emissions comprise methane,
at least one non-methane organic compound that influences the
metabolism of methanotrophic microorganisms, and methanotrophic
microorganisms capable of metabolizing said methane and said
non-methane organic compound; a growth-culture medium, comprising
one or more growth-culture compounds; a bioreactor that encloses or
contains said emissions and said medium; a conveyer that conveys
said gaseous emissions into said bioreactor and varies the
concentration of at least one of said methane or said non-methane
compound; wherein said methanotrophic microorganisms use a portion
of said methane to inoculate said medium to generate a
naturally-equilibrating consortium; and wherein said methanotrophic
microorganisms generate a single type of polymer after said one or
more growth culture compounds are altered.
51. The system of claim 50, wherein said single type of polymer
consists essentially of polymers that are structurally similar.
52. The system of claim 50, wherein said single type of polymer
consists essentially of polymers that are functionally
equivalent.
53. The system of claim 50, further comprising an additional source
methanotrophic microorganisms that is independent of said gaseous
emission.
54. The system of claim 50, wherein said one or more growth-culture
compounds are selected from the group consisting of one or more of
the following: nitrogen, copper, magnesium, phosphorus, oxygen,
carbon, potassium, and iron.
55. The system of claim 50, wherein said gaseous emission comprises
methane at a concentration in the range of about 0.1% to about
60%.
56. The system of claim 50, wherein said gaseous emission is
generated by a system selected from the group consisting of one or
more of the following: coal mine, wastewater treatment operation,
agricultural digester, enclosed feedlot, petroleum transport
system, petroleum recovery system, landfill, ruminant animal, and
compost facility.
57. The system of claim 50, wherein said methanotrophic
microorganisms comprise at least one of a naturally-occurring or
genetically-modified microorganism that use methane as a source of
carbon or energy for growth or reproduction.
58. The system of claim 50, wherein said plurality of
methanotrophic microorganisms comprise at least two different
species of methanotrophic microorganisms.
Description
RELATED APPLICATIONS
[0001] This application is the U.S. National Phase application
under 35 U.S.C. .sctn.371 of International Application
PCT/US2005/047415 filed Dec. 29, 2005, (published as WO
2007/024255), which claims the benefit of Provisional Application
No. 60/721,938, filed Sep. 29, 2005, and is a continuation-in-part
of co-pending patent application Ser. No. 11/208,808, filed Aug.
22, 2005, which claims the benefit of Provisional Application No.
60/603,857, filed Aug. 24, 2004; wherein patent application Ser.
No. 11/208,808 is a continuation-in-part of co-pending patent
application Ser. No. 10/687,272, filed Oct. 15, 2003, now issued as
U.S. Pat. No. 6,982,161; and wherein the disclosures of all of
these applications are incorporated by reference herein.
BACKGROUND OF THE INVENTION
[0002] 1. Field of Invention
[0003] This invention relates generally to a system and method for
the treatment of methane emissions, and in one specific embodiment,
to a system and method for the treatment of methane emissions
through the use of methanotrophic microorganisms.
[0004] 2. Description of the Related Art
[0005] Methane emissions, or methane off-gases, are generated by a
variety of natural and human-influenced processes, including
anaerobic decomposition in solid waste landfills, enteric
fermentation in ruminant animals, organic solids decomposition in
digesters and wastewater treatment operations, and methane leakage
in fossil fuel recovery, transport, and processing systems. As a
particularly potent greenhouse gas, methane emissions are
responsible for about twenty percent of planetary warming, and thus
represent a significant environmental concern. Accordingly, there
have been numerous efforts in the past to remediate, control,
and/or otherwise treat methane emissions.
[0006] In addition to processing methane that is emitted from
landfills, coal mines, wastewater treatment plants, manure
digesters, agricultural digesters, compost heaps, enclosed
agricultural feedlots, leaking or otherwise emitting petroleum
systems, several embodiments of the present invention are directed
to capturing and processing methane emitted by ruminant animals.
Methane emissions from ruminant animals account for about twenty
percent of total global methane emissions, and atmospheric methane
accounts for about twenty percent of planetary warming. In addition
to the environmentally destructive effects of ruminant animal
methane emissions, such emissions represent wasted energy, as a
significant percentage of the food ruminant animals eat is lost as
methane. Accordingly, there have been significant efforts in the
past to reduce ruminant animal methane emissions.
[0007] Ruminant animal methane emissions, or, more specifically,
enteric fermentation methane emissions, originate in the
four-stomach digestive tract common to all ruminant animals, which
includes the rumen, a large forestomach connected to the
four-stomach digestive tract. The rumen contains a host of
digestive enzymes, fungi, bacterium, and protozoa, and the bulk of
digestion, as well as methane production via enteric fermentation,
takes place here. Not surprisingly, all prior efforts to reduce
enteric fermentation methane emissions from ruminant animals, which
include dairy cows, beef cattle, sheep, goats, water buffalo, and
camels, have focused on modifications associated with the rumen or
digestive tract.
[0008] Several methods are known for the treatment of natural and
human-influenced methane emissions Used in conjunction with
well-known methane emissions collection methods, such as landfill
gas extraction wells/blowers and coal mine methane ventilation
systems, the treatment of air containing captured methane emissions
includes the use of turbines, microturbines, engines, reverse-flow
reactors, fuel cells, and boilers to convert methane emissions into
heat and/or electricity. Other well-known methods for the treatment
of methane emissions include the conversion of methane emissions
into pipeline-quality, liquefied, or compressed natural gas.
[0009] The treatment and utilization of methane off-gases for the
production of fuel, heat, and/or electricity is described by a
number of patents, including U.S. Pat. Nos. 5,642,630, 5,727,903,
5,842,357, 6,205,704, 6,446,385, and 6,666,027, herein incorporated
by reference. U.S. Pat. No. 5,642,630 describes the use of landfill
gas to produce high quality liquefied natural gas, liquefied carbon
dioxide, and compressed natural gas products. U.S. Pat. No.
5,727,903 describes the use of landfill gas to create vehicle grade
fuel. U.S. Pat. No. 5,842,357 describes the use of landfill gas to
create high grade fuel and food-grade carbon dioxide. U.S. Pat.
Nos. 6,205,704 and 6,446,385 describe the use of landfill gas to
provide heat, electricity, and/or carbon dioxide to enhance
greenhouse operations. U.S. Pat. No. 6,666,027 describes the use of
off-gas from landfills and digesters to power turbines for
electricity generation.
[0010] Although each of these methods is effective at treating
methane emissions under a specific range of conditions, none are
known to be economically and/or technologically feasible under a
range of sub-optimal methane-in-air conditions, including
conditions where the flow rate, concentration, or purity of methane
gas emissions is variable, unpredictable, low, and/or otherwise
unfavorable.
[0011] Methane-utilizing, or methanotrophic, microorganisms are
well-known in the microbiology art for their capacity to grow and
reproduce using methane as a source of carbon and/or energy,
particularly in a wide range of diverse methane availability
conditions. Accordingly, methanotrophic microorganisms have been
proposed in the past as a potential tool for the remediation of
methane emissions, particularly in conditions where other treatment
methods are technologically and/or economically unfeasible.
[0012] Two methods have been proposed for the utilization of
methanotrophic microorganisms to treat methane emissions. In one
proposed process, methanotrophic microorganisms are naturally
present or purposefully situated in high-methane emissions
environments, such as landfill covers or coal mines, are provided
with growth-stimulating nutrients, such as oxygen, water, or
mineral salts, to encourage increased microbial methane emission
uptake rates. This method may be carried out using nutrient
injection methods such as air or water sparging to induce increased
methanotrophic growth and oxidation rates in high emissions
environments. U.S. Pat. No. 6,749,368, for example, describes
methanotrophic microorganisms that are placed in an aerated soil
cover above a municipal landfill in order to oxidize and reduce
methane emissions.
[0013] In a second proposed process, air containing methane
emissions is diverted into an environment containing methanotrophic
microorganisms in order to cause the microbial breakdown of methane
emissions. This method may be carried out by diverting air
containing methane emissions into a biofiltration column containing
methanotrophic microorganisms, water, and a microorganism growth
medium, whereby electricity, water, nitrogen, trace minerals, and
other materials are continuously added to and consumed by the
system in order to effect the microbial breakdown of methane
emissions.
[0014] Both of these prior methanotrophic treatment techniques
cannot effectively or efficiently reduce methane emissions. Indeed,
the application of these processes has been precluded in practice
because while both generate continuous and costly requirements for
supply-limited materials, such as electricity and minerals, neither
generates direct economic benefits to recover the capital costs of
treatment, and the use of methanotrophic microorganisms for the
treatment of methane emissions is simply too costly to operate and
sustain over time. Prior to the applicants' discovery, no methods
were known to enable the practical sustainability of the biological
treatment of methane emissions, and, accordingly, the utilization
of methanotrophic microorganisms for the treatment of methane
emissions has been precluded in practice.
[0015] Accordingly, there exists a significant need to develop a
system that enables methanotrophic methane emissions treatment to
be technologically, financially, and logistically sustainable and,
thus, viable in practice
SUMMARY OF THE INVENTION
[0016] Preferred embodiments of the present invention address the
need for a system that enables methane emissions treatment to be
technologically, financially, and logistically sustainable and
viable. Prior to applicants' invention, gaseous emissions
comprising methane have never been used in conjunction with
methanotrophic microorganisms to effectively reduce the amount of
environmentally destructive methane pollution and to create a
harvestable product from that methane.
[0017] In one preferred embodiment, the gaseous emissions (which
comprise some amount of methane) from landfills, coal mines,
agricultural sites, or petroleum sites are captured and conveyed to
a bioreactor containing methanotrophic microorganisms. The gaseous
emissions do not need to undergo substantial purification. The
microorganisms use the methane as a source of carbon or energy,
and, in some embodiments produce useful end-products such as
polymers. The polymers can then be used to synthesize various types
of biodegradable materials. For example, the polymers can be used
to produce plastics because, in some cases, the physical properties
of the polymers produced by the methanotrophic microorganisms are
very similar to those of polypropylene. However, the polymers
produced by the methanotrophic microorganisms are biodegradable,
and therefore environmentally friendly. Thus, some preferred
embodiments of the invention offer a tremendous benefit to the
environment in at least two ways: first, methane emissions are
substantially reduced on the front end, and second, a biodegradable
polymer is produced in useful quantities as the end-product.
[0018] The term "gaseous emission" as used herein shall mean
off-gases and/or gases emitted by natural and/or human-influenced
processes, including anaerobic decomposition in solid waste
landfills, enteric fermentation in ruminant animals, organic
decomposition in digesters and wastewater treatment operations,
agricultural sites, and in fossil fuel recovery, transport, and
processing systems.
[0019] Although the prior art recognized that methanotrophic
organisms could use methane to produce polymers, the prior art did
not teach or suggest an effective method by which destructive
gaseous emissions that comprise methane could be used to produce
polymers. Thus, prior to applicants' invention, the production of
useful quantities of polymers by methanotrophic organisms was not
feasible, because the process, which (among other drawbacks)
required a pure and/or concentrated source of methane, could only
be done on a small scale. Moreover, because a pure and/or
concentrated source of methane was required, the costs of operating
the system was extremely high. Preferred embodiments of the present
invention, however, do not require an artificial laboratory grade
methane as the primary source of carbon or energy for the
methanotrophic organisms. Instead, environmentally destructive
gases that are already present in the environment can be used as
the source of methane.
[0020] Moreover, preferred embodiments of the present invention are
particularly advantageous because they can use gaseous emissions
comprising low concentrations of methane, rather than pure methane.
Although certain turbine systems can convert gaseous emissions into
energy, the concentration of methane must be high. Although certain
fuel cells can use methane in low concentrations, gaseous emissions
cannot be used (the methane must be substantially pure). In one
preferred embodiment of the current invention, gaseous emissions
comprising methane in a concentration of less than about 40%, less
than about 30%, less than about 20%, less than about 10%, less than
about 5%, and less than about 1% can be used. Thus, several
embodiments of the present invention are particularly useful for
older landfills, which may produce methane in concentrations of
about 0.1% to less than about 20% of total gaseous emissions as
they age. Likewise, several embodiments of the present invention
are particularly useful for coal mines, which may produce methane
in concentrations of less than about 5% of total gaseous emissions,
and in some cases about 1% methane. Thus, without the benefit of
certain preferred embodiments of applicants' invention, these
polluting systems--which alone produce methane as a small part of
their total gaseous emissions--cumulatively contribute
significantly to the total amount of methane in the environment and
thus ultimately to the greenhouse effect.
[0021] In one embodiment of the invention, the system comprises
means to enable the practical application of methanotrophic
microorganisms to methane emissions treatment, particularly in a
manner that does not rely on a reduction in the operating costs of
treatment. In other words, in one embodiment, methanotrophic
microorganisms can be used to reduce methane pollutants in the
environment without relying on altering the methanotrophic
microorganisms (e.g., by genetic engineering, etc.). In one
embodiment, naturally occurring methanotrophic microorganisms are
used to reduce the methane concentration of gaseous emissions.
[0022] As discussed previously, methane is an
environmentally-destructive material and previously unusable source
of energy, which, according to one preferred embodiment of the
invention, is used to produce a useful end-product that can be used
or sold for use, providing an economic incentive to a methane
emissions reduction effort. Although in one embodiment, the
harvestable useful end-product is a polymer, another harvestable
good is the microorganism culture itself. Thus, in another
embodiment, gaseous emissions comprising methane are used to grow a
microorganism culture to a density that is capable of being
harvested and commercially traded. In sufficient quantities, the
microorganism culture can be used, for example, as a nutrition
source for livestock. In one embodiment, the end-product is a
culture of microorganisms, or the products generated by those
microorganisms.
[0023] In one embodiment of the invention, methane emissions are
processed to produce useful and harvestable products. These
products include, but are not limited to: protein-rich biomass,
polyhydroxyalkanoate (PHA), polyhydroxybutyrate (PHB),
polyhydroxybutyrate-valerate (PHB/V), particulate or soluble
methane monooxygenase (pMMO or sMMO, respectively), vaccine
derivatives, enzymes, polymers, cellular materials, formaldehyde,
and methanol, or a combination thereof. In the commercial and
industrial biotechnology art, methanotrophic microorganisms can be
manipulated and processed according to several embodiments of the
present invention to generate useful, defined, and harvestable
goods in sterile, semi-sterile, and non-sterile conditions.
[0024] In one embodiment of the invention, a culture of suitable
microorganisms is provided for the efficient and effective
treatment of methane emissions. The prior art generally criticizes
the use of methanotrophic organisms to treat methane emissions,
primarily because such a process was thought to be unpredictable,
inefficient, and unreliable. For example, the prior art teaches
that bioremediation and biofiltration generates a microorganism
conglomerate that is non-specific, non-defined, and/or highly
variable according to shifts in nutrient availability, air
contamination, species interaction, and so on. As emphasized in
U.S. Pat. No. 6,599,423, "prior art teaches that ex situ biofilters
and bioreactors are akin to microorganism zoos, with the
microorganism cultures naturally adapting, dominating, and
maintaining themselves according the various compounds, food
sources, and contaminants present or fed to the biodegradation
media . . . changes, adaptations, and dominance of certain cultures
will occur even in such isolated and inoculated cultures after
operation begins and the biofilters or bioreactors are subjected to
complex mixtures of food sources, contaminants, and microorganisms
present in the natural environment." Microbial cultures and the
byproducts generated from the growth thereof may be incidentally
created in the course of bioremediation, as in the course of any
microorganism growth, but, according to the prior art, only in a
variable, non-specific, diffuse, unpredictable, speculative, or
otherwise non-useful manner. By contrast, in a preferred embodiment
of the present invention, a system of using microorganisms in a
highly controlled manner for the treatment of gaseous emissions is
provided.
[0025] The viability and utility of methanotrophic emissions
treatment may be augmented by increasing the growth or emissions
oxidation rate of methanotrophic microorganisms in order to reduce
the capital and operating costs of treatment. While this
optimization method renders methanotrophic treatment more
efficient, it does not overcome the challenge associated with the
continuous generation of non-recoverable costs, and no methods are
known in the prior art to optimize the methanotrophic
bioremediation process in such a way as to enable practical
sustainability. Prior to the applicants' invention, the only
methods available for treating methane emissions involved
environmental degradation and wasted energy associated with the
venting, compression, conversion, and/or combustion of methane
emissions.
[0026] Prior to the applicants' discovery, it was not recognized
that commercial, academic, and/or industrial growth and processing
methods known to enable the microbial creation of harvestable
products could be applied to overcome previously impassable and
fundamental treatment challenges in the field of methane emissions
treatment. In particular, it was not known that the use of
methanotrophic processes able to engender defined and harvestable
bio-based goods, specifically in sterile, semi-sterile, and
non-sterile conditions, could be used as a novel methane emissions
treatment method to overcome previously impassable practical
viability and sustainability challenges. Thus, according to a
preferred embodiment of the present invention, a method is provided
to enable the practical viability of the biological treatment and
utilization of methane emissions. In one embodiment, the method
enables the utilization of methane emissions through the production
of harvestable goods.
[0027] In a preferred embodiment of the invention, an apparatus or
system for processing methane emissions and producing harvestable
products is provided. In one embodiment, the system comprises (i) a
source of gaseous emissions, wherein the gaseous emissions comprise
methane and at least one non-methane compound, (ii) methanotrophic
microorganisms that use methane as a source of carbon or energy,
(iii) a bioreactor that encloses or contains the methanotrophic
microorganisms, and (iv) a conveyer that conveys the gaseous
emissions into the bioreactor, thereby exposing the methanotrophic
microorganisms to the gaseous emissions and causing the
methanotrophic microorganisms to produce a harvestable product
after using the methane as a source of carbon or energy.
[0028] In accordance with one embodiment of the invention, a novel
method for enabling the viable treatment of air containing methane
emissions is provided. In one embodiment, methanotrophic
microorganisms and air containing methane emissions are
mutually-exposed to cause or enable harvestable product formation.
The harvestable product may be used or sold. In another embodiment
of the invention, air containing methane emissions may be used to
create single cell protein, enzymes, polymers, or other bio-based
products in a manner that enables product harvest.
[0029] In one embodiment, the invention comprises a method of
processing methane emissions for the production of a harvestable
product, comprising: providing a gaseous emission comprising
methane and methanotrophic microorganisms, exposing the
methanotrophic microorganisms to the gaseous emission, wherein the
methanotrophic microorganisms use at least a portion of the methane
as a source of carbon or energy, and wherein the methanotrophic
microorganisms produce a harvestable product after using the
methane as a source of carbon or energy.
[0030] In one embodiment, the harvestable product comprises a
polymer (such as polyhydroxyalkanoate (PHA), polyhydroxybutyrate
(PHB), and polyhydroxybutyrate-valerate (PHB/V)). In another
embodiment, the harvestable product comprises one or more of the
following: microorganism biomass, methane monooxygenase,
protein-rich biomass, enzymes, and cellular contents. In yet
another embodiment, the harvestable product comprises a
quantifiable reduction in methane emissions.
[0031] In several embodiments, the gaseous emission comprises a gas
selected from the group consisting of one or more of the following:
carbon dioxide, ammonia, nitrous oxide, and ozone. In one
embodiment, the gaseous emission comprises unpurified landfill gas
or partially purified landfill gas. In one embodiment, one or more
impurities are removed from the gaseous emission. In another
embodiment, the gaseous emission is disinfected using ultraviolet
light.
[0032] In one embodiment, the invention comprises harvesting the
harvestable product for commercial or industrial sale or use.
[0033] In one embodiment, the invention comprises substantially
reducing or eliminating the concentration of nitrogen available to
the methanotrophic microorganisms.
[0034] In one embodiment, the invention comprises using gaseous
emissions having methane concentrations in the range of about 0.1%
to about 10%, in the range of about 10% to about 20%, and at
concentrations greater than about 20%. In another embodiment, the
methane concentration is less than about 5%. In yet another
embodiment, the methane concentration is between about 30% to about
60% of the total gaseous emissions, and carbon dioxide
concentration is about 30% to about 60%. The latter numbers are
typical of certain landfill emissions.
[0035] In one embodiment, the gaseous emission is generated by one
or more of the following: coal mine, wastewater treatment
operation, agricultural digester, enclosed feedlot, petroleum
transport system, and petroleum recovery system. In another
embodiment, the gaseous emission is generated by one or more
ruminant animals.
[0036] In one embodiment, the microorganisms comprise
naturally-occurring or genetically-modified microorganisms, or a
combination thereof, that use methane as a source of carbon or
energy for growth or reproduction. The methanotrophic
microorganisms may include one or more of the following:
Methylococcus capsulatus, Alcaligenes acidovorans, Bacillus firmus,
and Bacillus brevis.
[0037] In a further embodiment, the gaseous emission comprises a
non-methane compound, wherein the non-methane compound is an
organic compound. In another embodiment, the gaseous emission
comprises a non-methane compound such as toluene, benzene,
methanol, propylene, alkenes, alcohol, ether, and
trichloroethylene, or a combination thereof. Non-methane compounds
may also include non-methane gases such as carbon dioxide, ammonia,
nitrous oxide, and ozone.
[0038] In one embodiment, the non-methane compound is metabolized,
consumed, or used by the methanotrophic microorganisms.
[0039] In yet another embodiment, the invention comprises reducing
the concentration of methane to a concentration compliant with
applicable environmental regulations or laws. In the United States,
for example, preferred embodiments of the invention reduce methane
to concentrations suggested or mandated by local, state, and
federal EPA guidelines.
[0040] In one embodiment, the present invention comprises a method
of producing a biodegradable polymer from landfill gas. In one
embodiment, the method comprises obtaining landfill gas, wherein
the landfill gas comprises methane, enclosing the landfill gas in a
bioreactor containing methanotrophic microorganisms and growth
medium, and inducing the methanotrophic microorganisms to produce
biodegradable polymer by substantially reducing or depleting the
growth medium of any nitrogen. In one embodiment, the method
further comprises harvesting the biodegradable polymer.
[0041] In one embodiment of the present invention, a system to
reduce methane emissions or gaseous emissions comprising methane is
provided. In one embodiment, the emissions are produced by land
fills, waste processing sites, coal mines, and other similar
systems created by humans. In another embodiment, the emissions are
produced by ruminant animals.
[0042] Thus, in accordance with several embodiments, methane
produced through ruminant animal enteric fermentation is used as a
source of carbon and/or energy for the induction of a
methane-driven process and/or for the production of methane-derived
materials, such as methane-utilizing microorganisms, heat, and/or
electricity.
[0043] In one preferred embodiment, the present invention comprises
a system or apparatus for processing methane emissions produced by
one or more ruminant animals. In one embodiment, the system
comprises (i) one or more ruminant animals that emit gaseous
emissions through enteric fermentation, wherein the gaseous
emissions comprise methane and at least one non-methane compound,
(ii) an enclosure for enclosing the ruminant animals, (iii) a
methane-consumption means that uses methane for the production of a
product, and (iv) a conveyer that conveys the gaseous emissions to
the methane-consumption means, wherein the methane-consumption
means is exposed to the methane in the gaseous emissions and uses
the methane to generate a harvestable product.
[0044] In one embodiment, the present invention comprises a method
for processing methane emissions produced by one or more ruminant
animals comprising providing one or more ruminant animals that emit
gaseous emissions through enteric fermentation. The gaseous
emissions comprise methane, airborne materials, and at least one
other gas. The method further comprises enclosing the ruminant
animals in an enclosure, thereby at least partially enclosing the
gaseous emissions. The method also comprises providing a
methane-consumption means, or methane consumer, that uses methane
to produce a product, and conveying the gaseous emissions to the
methane-consumption means. In one embodiment, the method includes
causing the methane-consumption means to process the methane to
generate a product. The term "causing" is a broad term and includes
the act of simply causing methane to come into contact with the
methane consumer, and letting nature take its course. In
embodiments where engines, turbines or fuel cells are used, the act
of causing includes supplying energy to the various components.
[0045] In one embodiment, this process of treating gaseous
emissions emitted by ruminant animals comprises a) enclosing one or
more ruminant animals in an enclosure means, such as a barn, and b)
contacting air contained in such an enclosure means, including the
enteric fermentation methane contained therein, with a
methane-consumption system, whereby enteric fermentation methane
emissions are utilized as a novel source of carbon and/or energy
for the induction of a methane-based process and/or for the
production of methane-based products, such as heat, electricity,
and/or methane-utilizing microorganisms.
[0046] In a further embodiment, the method of treating ruminant
emissions comprises: (a) providing one or more ruminant animals,
(b) providing enteric fermentation-derived methane gas that has
been emitted by the animals, including air containing the methane,
(c) providing means to capture, consolidate, and/or direct the
methane, including providing an enclosure means to enclose the
animals, the air, and the methane and providing an air conveyor to
direct the air and the methane, (d) providing a methane-consumption
means which can use the methane as a source of carbon and/or energy
in a methane-based process and/or for the production of
methane-based goods, and (e) contacting the methane with the
methane-consumption means to cause the methane-consumption means to
oxidize, consume, and/or otherwise utilize the methane for the
operation of a methane-based process or for the production of one
or more methane-based products, including methane-utilizing
microorganisms, heat, and/or electricity.
[0047] In another embodiment, this method comprises: (a) providing
one or more ruminant animals, (b) providing an enclosure means to
fully or partially enclose and/or otherwise encapsulate the
animals, (c) providing enteric fermentation-derived methane gas
that has been emitted by the animals, (d) providing enclosure air
that has been combined with the methane in the enclosure means, (e)
providing a methane-consumption means which can use the methane as
a source of carbon and/or energy for the induction of a
methane-based process or the production of methane-based goods, (f)
providing a means for contacting the air containing the methane
with the methane-consumption means, including a means for the
conveying the air to the methane-consumption means whereby the
methane can be utilized as a source of carbon and/or energy by the
methane-consumption means, (g) mutually-contacting and/or exposing
the methane and the methane-consumption means to cause the
methane-consumption means to oxidize, consume, and/or otherwise
utilize the methane for the induction of one or more methane-based
processes or for the production of one or more methane-based
products, including methane-utilizing microorganisms, heat, and/or
electricity, whereby the methane produced by the animals is
utilized for the sustained production of the process and/or the
products in a specified apparatus.
[0048] As discussed previously, methane is an
environmentally-destructive material and previously unusable source
of energy, which, according to one preferred embodiment of the
invention, is used to produce a useful end-product that can be used
or sold for use, providing an economic incentive to a ruminant
animal methane emissions reduction effort. In one embodiment, the
end-product is heat. In another embodiment, the end-product is
fuel. In yet another embodiment, the end-product is electricity. In
yet another embodiment, the end-product is another form of energy.
In a further embodiment, the end-product is the culture of
microorganisms.
[0049] In one embodiment using ruminant animal emissions, the
enclosure means, or enclosure, includes any means by which the
animals are fully or partially enclosed or encapsulated. The
enclosure includes, but is not limited to, a barn, greenhouse,
and/or any other suitable enclosures or housing.
[0050] In one embodiment, the term "air" as used herein shall be
given its ordinary meaning, and shall include all airborne and
gaseous components of air that has been contacted with the methane
in the enclosure means, including the methane emitted by the
animals contained within the enclosure means, as well as ammonia
gas, dust, and/or other airborne materials that may be present in
the air.
[0051] In one embodiment, methane-consumption means includes any
means by which the methane is oxidized, consumed, and/or otherwise
used as a form of carbon and/or energy. Methane-consumption means
includes, but is not limited to, methane-utilizing microorganisms,
fuel cells, turbines, reverse-flow reactors, engines,
microturbines, and/or any other methane-consumption means.
Accordingly, in some embodiments, methane emissions are conveyed
from ruminant animals (or another source) to a fuel cell, turbine,
or reactor to produce fuel or other energy. Thus, in some
embodiments, methanotrophic microorganisms need not be used.
[0052] In one embodiment, the ammonia contained within the air is
contacted with liquid water and converted into ammonium and used as
a source of nitrogen by the methane-utilizing microorganisms. In
one embodiment, the dust and/or other airborne material within the
enclosed air is reduced prior to or in the course of using the
methane within the air as a source of carbon and/or energy.
[0053] In one embodiment, the methane within the air is used by the
methane-consumption means in conjunction with alternative sources
of methane, such as coal mine methane, landfill gas methane,
natural gas methane, manure digester methane, wastewater treatment
methane, and/or other sources of methane.
[0054] In one embodiment, an air conveyor is provided to direct,
move, and/or otherwise convey enclosure air, wherein the conveyor
can be used to contact the air with the methane-consumer. In
another embodiment, a conveyer is used to move gaseous and/or
methane emissions from one location to another, and may include
pipes, tubing, containment means, ducts, channels\and other
conduits. In one embodiment, the conveyer is large and/or
compartmentalized such that at least a portion of the conveyer
serves as the bioreactor, in that it contains methanotrophic
organisms.
[0055] In one embodiment, the enclosure is erected, modified,
and/or used to enclose the animals and to make the methane
available for use by the methane-consumer. In one embodiment, the
enclosure is provided and utilized to collect the air containing
the methane.
[0056] In one embodiment, the methane emissions provided to the
methanotrophic organism or other methane consumption means is
provided in conjunction with air, dust, methane, ammonia, gases,
insects, particulate matter, and/or other airborne matter. In some
embodiments, one of skill in the art will appreciate that one or
more of the above steps described herein is modified or omitted.
Further, the steps need not be conducted in the order set forth
herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0057] FIG. 1 is a side perspective view of an apparatus used to
carry out a process in accordance with one embodiment of the
invention. In the illustration, the apparatus is self-contained and
maintained entirely on the body of a ruminant animal. FIGS. 2A, 2B,
3A, and 3B describe this apparatus in greater detail.
[0058] FIG. 2A is a top cross-sectional view of one of two parts of
the apparatus depicted in FIG. 1. The part of the apparatus
illustrated is the permanent exhalation conveyance structure that
is attached to the body of a ruminant animal.
[0059] FIG. 2B is a side perspective view of one of two parts of
the apparatus depicted in FIG. 1. The part of the apparatus
illustrated is the permanent exhalation conveyance structure that
is attached to the body of a ruminant animal.
[0060] FIG. 3A is a side cross-sectional view of one of two parts
of the apparatus depicted in FIG. 1. The part of the apparatus
illustrated is the removable microorganism containment capsule that
is inserted into the permanent exhalation conveyance structure.
[0061] FIG. 3B is a side perspective view of one of two parts of
the apparatus depicted in FIG. 1. The part of the apparatus
illustrated is the removable microorganism containment capsule that
is inserted into the permanent exhalation conveyance structure.
[0062] FIG. 4 is a schematic of a preferred embodiment of a process
carried out in accordance with one embodiment of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0063] While this invention comprises embodiments in many different
forms, there will herein be described in detail preferred methods
of carrying out a process in accordance with the invention with the
understanding that the present disclosure is to be considered as an
exemplification of the principles of the invention and is not
intended to limit the broad aspect of the invention to the
embodiments illustrated.
[0064] In a preferred embodiment of the invention, methane
emissions are treated through the use of a product-generating
methanotrophic growth system. In one embodiment, this growth system
is designed to enable the production of harvestable bio-based
goods. For example, in a preferred embodiment, methanotrophic
microorganisms and air containing methane emissions are
mutually-exposed in an apparatus, such as a bioreactor, filled with
methanotrophic bacteria, whereby methanotrophic bacteria use
methane emissions for the creation of a harvestable bio-based
product.
[0065] In one embodiment, the harvestable bio-based product
includes, but is not limited to, a polymer such as
polyhydroxybutyrate (PHB), single cell protein, enzymes,
homogenized biomass, and other harvestable methanotrophic products.
This process may be carried out in sterile, semi-sterile, or
non-sterile conditions.
[0066] The term "harvestable" as used herein shall be given its
ordinary meaning and shall also mean usable, producible,
collectable, useful, yieldable, and capable of being harvested.
Likewise the term "harvest" is a broad term that shall be given its
ordinary meaning and shall also mean gather, collect, amass,
accumulate, and assemble.
[0067] In one embodiment, methane emissions are captured, exposed
to, and treated with one or more species of methanotrophic
microorganisms to produce a harvestable single cell protein. Single
cell protein (or SCP) includes microbial biomass or proteins
containing therein or extracted therefrom, and may be used as
animal feed, for human nutrition, or for industrial uses. One
particularly suitable method for the production of single cell
protein is the use of a self-containing conglomerate of
microorganisms that promotes product and species stability in
non-sterile or semi-sterile conditions. The production process used
by Norferm A/S in Norway to create SCP from methane is one example
of a methanotrophic growth process that may be applied to carry out
one embodiment of the present invention.
[0068] Another suitable method for the production of a harvestable
product (including, but not limited to SCP) is the use of methods
to promote product stability and harvestability. These methods
include, but are not limited to: air disinfection, water
disinfection, mineral media disinfection, system sterility
management, directed species symbiosis, growth conditions
management, incoming air gaseous components separation, and others.
Accordingly, in one embodiment, product stability and/or
harvestability is enhanced or facilitated by one or more of these
methods.
[0069] In another embodiment of the invention, methane emissions
are used to effect the growth of microorganisms, wherein
microorganisms are subsequently manipulated to produce harvestable
PHB by depriving microorganisms of a particular nutrient, such as
nitrogen, on a batch, semi-batch, or continuous basis.
Methanotrophic microorganisms (such as Alcaligenes eutrophus)
employ a polymer (such as PHB) as a form of an energy storage
molecule to be metabolized when other common energy sources are not
available. Thus, in one embodiment, methanotrophic organisms are
periodically or continuously exposed to methane emissions in a
nitrogen-poor environment. Partial, substantial, or complete
depletion of nitrogen can occur before the organisms are exposed to
methane or after such exposure has occurred. Alternatively,
nitrogen depletion can occur at some point during exposure of the
organisms to methane. As is well known in the art of microbial PHA
and PHB production, the depletion of an essential nutrient such as
nitrogen in the presence of a sufficient carbon supply will cause
bacterial cultures to store energy in the form of PHA, PHB, or,
depending on growth conditions, some similar energy storage
material, with the aim of accessing this stored energy once all
essential growth and reproduction components are fully present at a
later time. PHB, or similar energy storage materials, may account
for a significant percentage of the weight and/or volume of a
single microorganism cell, and may be harvested by any number of
well known techniques, such as centrifugation, cell lysis,
homogenization, chloroform dissolution, sodium hydroxide
dissolution, cell parts extraction, and so on.
[0070] In another embodiment of the invention, methanotrophic
microorganisms are used to oxidize a quantifiable, monitored, and
certifiable volume of methane in a sterile or non-sterile
environment, thereby creating a greenhouse gas reduction product
which may be "harvested" and sold in a market which purchases
and/or trades greenhouse gas reduction credits, such as a carbon
dioxide credit trading market. Thus, in one embodiment, the
harvestable product is the quantifiable reduction of methane,
especially as it pertains to air pollution reductions credits
and/or global warming gas emissions reductions credits.
Accordingly, in one embodiment of the invention, a system to
quantify how much methane has been used is provided. This
embodiment will be particularly advantageous for those
organizations that need to comply with certain environmental
regulations or need to certify that specific volumes of methane
have been biologically oxidized.
[0071] In another embodiment of the invention, methane emissions
may be used to create harvestable enzymes. In one embodiment, the
enzyme is methane monooxygenase. In one embodiment, the cell
contents may be accessed physically, chemically, enzymatically, or
otherwise to enable harvesting in defined or non-defined microbial
cultures. The maintenance of copper concentrations will be useful
to effect the consistent production of either soluble or
particulate methane monooxygenase, as is well known in the art. In
particular, if the concentration of copper in a methanotrophic
growth medium is minimized and kept below specific and well known
concentrations, such as 5.times.10.sup.-9 M, the production of
soluble methane monooxygenase may be effected in most or all
methanotrophic cells accessing that copper-limited medium. Soluble
or particulate methane monooxygenase may be harvested using any
well known methane monooxygenase extraction and purification
method.
[0072] The processes disclosed herein may be carried out and
directed in a controlled bioreactor, wherein liquid, semi-liquid,
particulate, or solid mineral media may be used to enhance the
growth of methanotrophic microorganisms. Alternatively, the
processes described herein may be carried out in reaction tanks,
vessels, or other containment systems.
[0073] In another aspect of the invention, various processing
techniques known in the art may be used to preferentially extract
harvestable products of methanotrophic growth, such as chemical
treatment, centrifugation, drying, and homogenization.
[0074] In a preferred embodiment of the invention, landfill gas is
used as the source of methane. In one embodiment, impurities from
landfill gas, such as non-methane and/or volatile organic
compounds, water vapor, and/or carbon dioxide are partially,
substantially, or completely removed. In another embodiment, the
landfill gas is disinfected.
[0075] In one embodiment, UV treatment is used to disinfect the
gas. Mechanical, activated carbon, or chemical filtration may also
be used.
[0076] In one embodiment methane emissions within landfill gas are
exposed to methanotrophic microorganisms. In one embodiment,
gaseous emissions comprising methane are fed into a bioreactor
containing methanotrophic microorganisms suspended in or on a
liquid, semi-liquid, or solid growth-culture medium containing
water and mineral salts. In another embodiment, after
methanotrophic microorganisms have grown and reproduced using
methane emissions as a source of carbon and/or energy, these
microorganisms are harvested as single cell protein through various
extraction and de-watering processes.
[0077] In one embodiment, a method of treating gaseous emissions
(e.g., landfill gas) is provided. In one embodiment, the method
comprises: (i) enclosing the landfill gas in a bioreactor
containing methanotrophic microorganisms; and (ii) harvesting the
microorganisms and/or the products produced by the microorganisms
in the bioreactor. In another embodiment, the method comprises: (i)
removing impurities from the landfill gas; (ii) disinfecting the
landfill gas; (iii) enclosing the landfill gas in a bioreactor
containing methanotrophic microorganisms; and (iv) harvesting the
microorganisms and/or the products produced by the microorganisms
in the bioreactor.
[0078] In one embodiment, a portion of the microorganisms may be
directed into a bioreactor containing a nitrogen depleted growth
medium and a constant supply of gaseous emissions (e.g., landfill
gas), whereby microorganisms synthesize intracellular PHB. In one
embodiment, the PHB-filled cells are subsequently removed from the
reactor in order to process and harvest intracellular PHB. These
processes are preferentially carried out on a continuous,
semi-continuous, semi-batch, or batch-wise basis, and methane
emissions from any source, including landfills, coal mine,
wastewater treatment plants, agricultural systems, or petroleum
systems, may be used.
[0079] The term "methanotrophic microorganisms" refers to any
microorganisms that utilize methane as a source of carbon and/or
energy for growth and reproduction, including naturally-occurring
and/or genetically engineered microorganisms. It also refers to the
combination or mixture of methanotrophic and non-methanotrophic
microorganisms that promote the growth of methanotrophic
microorganisms. In one preferred embodiment, this combination
comprises Methylococcus capsulatus, Alcaligenes acidovorans,
Bacillus firmus, and Bacillus brevis, since this combination has
been shown to limit or reduce bacterial contamination in non- and
semi-sterile bioreactor conditions, thereby enabling stable product
formation. In another preferred embodiment, this combination
comprises any methanotrophic microorganisms that may be used to
produce polymers such as PHB, enzymes such as methane
monooxygenase, and/or any other cellular components. In another
preferred embodiment, this combination comprises a non-defined mix
of methanotrophic and non-methanotrophic microorganisms that can be
used to create a harvestable product from the oxidation (or
alternate processing) of methane emissions.
[0080] The terms "methanotrophic microorganism growth-culture
medium" and "growth medium" refer to any medium promoting the
growth of microorganisms, including any one or more of the
following: liquid, semi-liquid, gas, particulate, ceramic, foam,
plastic, alginate gel, methanol-enriched, copper-enriched, clay,
nutrient, or other appropriate growth-culture medium. In a
preferred embodiment, this growth culture medium comprises an
aqueous solution containing mineral salts, copper, and other trace
minerals necessary for the growth and reproduction of
methanotrophic bacteria.
[0081] In another preferred embodiment, a system comprising
methanotrophic organisms is used to degrade or otherwise reduce a
pollutant other than methane as a method to enable the viable
treatment of methane emissions. In one embodiment, the growth of
methanotrophic microorganisms using methane emissions is carried
out in the presence of a non-methane material that can be
broken-down, oxidized, consumed, and/or otherwise changed in form
through the action of such microorganisms, wherein such non-methane
material includes, but is not limited to, one or more of the
following: toluene, benzene, methanol, propylene, any alkenes,
alcohols, ethers, alicyclics, aromatics, and/or chlorinated organic
compounds, such as the pollutant TCE, wherein a product, including
the oxidized chemical or quantifiable pollutant treatment, may be
harvested in a controlled, directed, and/or quantifiable
manner.
[0082] In another preferred embodiment of the invention, following
the growth of methanotrophic microorganisms in a bioreactor, some
or all of the contents of the bioreactor are removed from the
bioreactor and are either processed or used and sold directly.
Processing may include any number of methods that enable product
harvest, such as centrifugation, filtration, drying,
homogenization, chemical treatment, physical treatment, enzymatic
treatment, or any other processing means. Processing means may be
used to extract products out of defined or non-defined
conglomerates of methanotrophic microorganisms. The application and
utilization of processing techniques, such as centrifugation and
homogenization, may be used to effect the overall harvestability of
the methanotrophic growth and treatment process, especially where
the maintenance of a defined culture is unfeasible.
[0083] Preferred embodiments of the present invention offer one or
more advantages. For example, one or more embodiments provide one
or more of the following benefits:
[0084] (i) enables the viable and economical utilization of
methanotrophic microorganisms in the treatment and utilization of
methane emissions;
[0085] (ii) enables methanotrophic methane emissions treatment
without depending on a reduction in capital or operating costs;
[0086] (iii) enables the viable and economical application of
methanotrophic microorganisms to methane emissions treatment in
environments where a reduction in the concentration of methane
emissions is not required;
[0087] (iv) provides a methanotrophic methane emissions treatment
process that is economically competitive with alternative methods
of methane emissions treatment;
[0088] (v) provides a process that applies well-known methods of
harvestable methanotrophic product-generation as a novel method to
enable the sustained treatment and utilization of methane
emissions;
[0089] (vi) overcomes previously insurmountable practical
challenges in the field of methane emissions treatment; and/or
[0090] (vii) provides a process which, if widely applied, has the
capacity to significantly reduce global methane emissions.
[0091] Preferred embodiments of the invention comprise one or more
of the foregoing advantages and/or objects. Further objects and
advantages will become apparent from the ensuing description.
[0092] In another preferred embodiment, methane emissions may be
used from landfills, coal mines, wastewater treatment plants,
manure digesters, agricultural digesters, compost heaps, enclosed
agricultural feedlots, leaking or otherwise emitting petroleum
systems, and any other source of methane emissions or off-gas
whereby the creation of harvestable bio-based is enabled. The
methane emitted by ruminant animals can also be used as a source of
methane according to several embodiments of the present invention.
The processing of methane emissions produced by ruminant animals is
discussed below.
[0093] Prior to the applicants' discovery, no methods were known to
reduce ruminant animal methane emissions by using such methane as a
source of energy in energy consumption systems maintained outside
of the digestive tracts of ruminant animals. In the past, all
ruminant animal methane reduction processes have focused on
limiting ruminant animal methane production rather than reducing
overall atmospheric emissions through a system of methane
utilization. Thus, it is one feature of several embodiments of the
present invention that ruminant methane emissions are reduced
through the utilization of ruminant animal methane as a source of
energy. No methods are believed known to capture and/or consolidate
enteric fermentation methane emissions in a way that would convert
them into a state suitable for use as a fuel stream for the
production of methane-based goods or processes. Enteric
fermentation methane originates as diffuse emissions, and no
methods are known to convert such emissions into a usable form. For
these and other reasons, ruminant animal methane emissions have
never been considered as a viable source energy, and the connection
between enteric fermentation methane emissions and methane-driven
process and goods production has never occurred.
[0094] Mechanical ventilation systems are well known in the
livestock and agricultural science art for their capacity to draw,
push, or pull air through a fully or partially enclosed ruminant
animal holding, feeding, or enclosure area. The main function of
mechanical ventilation systems, including tunnel ventilation
systems and other ventilation systems, is to provide air flow or
air exchange in order to maintain or improve the health of ruminant
animals in a fully or partially enclosed holding or feeding area.
It is also well known in the livestock and agricultural science art
that some mechanical ventilation systems, particularly tunnel
ventilation systems, have the capacity to force all or some of the
air inside a fully or partially enclosed ruminant animal holding or
feeding area through specific vents or fans. The outflow air coming
out of ventilation fans have even been forced, directed, or led
into mulch, compost, and/or other platforms designed to limit or
reduce outflow air odor or dust emissions. Prior to the applicants'
discovery, though, such ventilation systems used in conjunction
with enclosure structures had never been considered as means to
enable the capture, consolidation, and utilization of ruminant
animal methane emissions as a source of energy. It is one feature
of several embodiments of the present invention that animal
enclosure structures and/or ventilation systems are applied as
means to capture, consolidate, direct, and/or convey ruminant
animal methane emissions to enable the use of such emissions as a
source of energy. Prior to the applicants' discovery, ventilation
systems and/or enclosure structures had never been used to capture
ruminant animal enteric fermentation methane emissions, nor had
such emissions ever been used to grow bacteria in a bioreactor
optionally equipped with means to harvest any of the microbial
products associated with bioreactor activity, particularly
microbial biomass.
[0095] Further, prior to the applicants' discovery, ventilation
systems and/or enclosure structures had never been used to capture
enteric fermentation methane for utilization by a
methane-consumption system such as a reverse-flow reactor or
microturbine. The utilization of air conveyance systems to capture
enteric fermentation methane for use as a source of carbon and/or
energy overcomes a range of practical problems associated with a
system for capturing methane emissions from the nose and/or mouth
of a ruminant animal using on-animal apparatuses such as
bioreactors or microturbines, including animal mobility problems
and reactor size requirements for optimal methane conversion. The
straightforward utilization of structures, means, and systems that
are well known and/or commonly used also overcomes a range of prior
emissions capture problems, including practicability, palatability,
and viability. One of skill in the art will understand that
currently available and other ventilation systems can be used in
accordance with embodiments of the invention.
[0096] As described herein, several embodiments of the present
invention provide a novel process for the utilization of methane
emitted by ruminant animals. Preferred embodiments of the invention
involving ruminant animal emissions are particularly advantageous
because they provide one or more of the following benefits:
[0097] (i) converts a previously wasted form of energy into a
useful end-product,
[0098] (ii) converts an environmentally-destructive greenhouse gas
into a useful end-product,
[0099] (iii) provides a direct economic incentive for a ruminant
animal methane emissions reduction effort,
[0100] (iv) reduces atmospheric ruminant animal methane emissions
without altering the chemical or microbial make-up of the digestive
tract of ruminant animals,
[0101] (v) reduces atmospheric ruminant animal methane emissions
without requiring ruminant animals to alter their normal/natural
behavior patterns, including sleeping and nutrient-consumption,
[0102] (vi) reduces atmospheric ruminant animal methane emissions
without requiring feed reformulations, selective breeding
activities, or chemical or microbial modifications to the digestive
systems of ruminant animals,
[0103] (vii) utilizes as a source of energy a material never
previously considered a viable source of energy, and/or
[0104] (viii) has the potential, especially if used widely, to
significantly reduce ruminant animal methane emissions.
[0105] As used herein, the terms "ruminant animal methane",
"enteric fermentation methane", and "ruminant animal enteric
fermentation methane" shall be given their ordinary meaning and
shall also refer to any methane produced and emitted by one or more
ruminant animals as a result of processes associated with enteric
fermentation. An average adult dairy cow will emit approximately
150 kg of enteric fermentation methane per year, while beef cattle
will each produce about two-thirds of that volume, or 100 kg per
year. Methane emitted by ruminant animals is a particularly
important greenhouse gas, since on a ton-to-ton basis it has 21 to
23 times the heat-trapping capacity of carbon dioxide.
[0106] The term "consolidation means" shall be given its ordinary
meaning and shall also refer to any means by which enclosure air is
unified, mutually-directed, and/or otherwise consolidated for
conveyance. In one preferred embodiment, a consolidation means
comprises an air-tight ducting tube running from an air outlet to a
mutual-exposure means, as described below, wherein enclosure air is
directed out of an enclosed area, through a consolidation means,
and into a mutual-exposure means. In another preferred embodiment,
a consolidation means comprises multiple ducting tubes connected to
air outlets and situated to consolidate outflowing enclosure air
into a single ducting tube that ultimately leads as one or more air
streams into a methane-consumption system.
[0107] The term "ventilation means" shall be given its ordinary
meaning and shall also refer to any means by which air, gases,
and/or other airborne material is mechanically forced, pushed,
pulled, drawn, moved, conveyed, or otherwise directed into,
through, and/or out of a spatial area enclosed by an enclosure
means. In one preferred embodiment, well-known ventilation fans,
such as rotating ventilation fans and/or tunnel ventilation fans,
operate in a well-known barn ventilation process, whereby air may
be drawn into a barn through one or more open spaces in a barn wall
and directed out of a barn through ventilation fans. In one
preferred embodiment, an enclosure means is provided with
ventilation means, wherein air is moved into and out of an
enclosure means at an overall combined rate of 10 cubic feet per
minute per dairy cow. In one preferred embodiment, means for the
cooling of barn-enclosed air are also provided in order to ensure
animal well-being in an enclosed area. A number of air-cooling
means are well known, such as cooling pads, water sprayers, and air
conditioning units.
[0108] The term "ruminant animal" shall be given its ordinary
meaning and shall also refer to one or more ruminant animals,
including, as in one preferred embodiment, a dairy or beef cow.
[0109] The terms "enclosure means" and "means for enclosure" shall
be given their ordinary meaning and shall also refer to any means
by which some or all of the space in which one or more ruminant
animals exist is partially or fully confined, isolated,
encapsulated, and/or enclosed, such as a barn or greenhouse
structure. In one preferred embodiment, a barn with a specified air
inlet, such as a window, and a specified air outlet, such as a
window housing a ventilation fan, encloses a ruminant animal (e.g.,
dairy cow).
[0110] The term "air inlet" shall be given its ordinary meaning and
shall also refer to any location where air, gas, and/or other
airborne material enters into an area or chamber fully or partially
enclosed by an enclosure means. In one preferred embodiment, an air
inlet comprises a spatial opening, such as a window, in the wall of
an enclosure means.
[0111] The term "air outlet" shall be given its ordinary meaning
and shall also refer to any location where air, gas, and/or other
airborne material exits out an area or chamber fully or partially
enclosed by an enclosure means. In one preferred embodiment, an air
outlet comprises a spatial opening housing a ventilation means
located in the wall of an enclosure means.
[0112] The term "enclosure air" shall be given its ordinary meaning
and shall also refer to the air, gases, and/or other airborne
material that have been mixed with enteric fermentation methane in
the space fully or partially enclosed by an enclosure means,
including enteric fermentation methane, ammonia, dust, and/or other
airborne material contained within an enclosure means containing a
ruminant animal.
[0113] Methane-utilizing microorganisms represent one embodiment of
a "methane-consumption system" or "methane consumption means." The
latter two terms include a biological system that utilizes enteric
fermentation methane as a source of carbon and/or energy, a
mechanical system that uses or consumes methane, and/or a chemical
system that uses, degrades, consumes, or reacts with methane.
[0114] The term "methane-utilizing microorganism" or
"methanotrophic microorganism" shall be used interchangeably, shall
be given their ordinary meaning, and shall also refer to any
microorganism, naturally-occurring or genetically-engineered, that
utilizes methane, including enteric fermentation methane, as a
source of carbon and/or energy. The term "methane-utilizing
microorganisms" also refers to the combination of methane-utilizing
and non-methane-utilizing microorganisms that are collectively
associated with the growth of methane-utilizing microorganisms. In
one embodiment, this microorganism combination includes one or more
of the following: Methylococcus capsulatus, Alcaligenes
acidovorans, Bacillus firmus, and Bacillus brevis. In one
embodiment, a combination of these microorganisms is used because
among other advantages, this combination is known to promote the
long-term growth of Methylococcus capsulatus. The term
"methane-utilizing microorganisms" also includes any methanotrophic
organisms and organisms that use or "take-up" methane.
Methane-utilizing microorganisms may be confined in a microorganism
holding tank containing methane-utilizing microorganisms and a
microorganism growth-culture medium. They may also be present in a
biofiltration system containing methane-utilizing microorganisms
wherein microorganisms either are or are not attached to a
microorganism support substrate and are continuously or
intermittently contacted with a microorganism growth-culture
medium. They may also be used in a bioreactor containing
methane-utilizing microorganisms and a microorganism growth-culture
medium wherein the growth-culture medium is in liquid, foam, solid,
semi-solid, or any other suitable form and methane-utilizing
microorganisms are naturally-occurring and/or genetically
engineered and may or may not have been selectively inserted as
part of a pre-determined microbial consortium. While the use of
specified microorganism consortium may provide some benefits, a
non-specified and naturally-equilibrating consortium of one or more
microorganisms may also be employed. Typical examples of
methane-utilizing microorganisms useful in several embodiments of
the present invention include, but are not limited to, bacteria and
yeast.
[0115] Suitable yeasts include species from the genera Candida,
Hansenula, Torulopsis, Saccharomyces, Pichia, 1-Debaryomyces,
Lipomyces, Cryptococcus, Nematospora, and Brettanomyces. The
preferred genera include Candida, Hansenula, Torulopsis, Pichia,
and Saccharomyces. Examples of suitable species include: Candida
boidinii, Candida mycoderma, Candida utilis, Candida stellatoidea,
Candida robusta, Candida claussenii, Candida rugosa, Brettanomyces
petrophilium, Hansenula minuta, Hansenula saturnus, Hansenula
californica, Hansenula mrakii, Hansenula silvicola, Hansenula
polymorpha, Hansenula wickerhamii, Hansenula capsulata, Hansenula
glucozyma, Hansenula henricii, Hansenula nonfermentans, Hansenula
philodendra, Torulopsis candida, Torulopsis bolmii, Torulopsis
versatilis, Torulopsis glabrata, Torulopsis molishiana, Torulopsis
nemodendra, Torulopsis nitratophila, Torulopsis pinus, Pichia
farinosa, Pichia polymorpha, Pichia membranaefaciens, Pichia pinus,
Pichia pastoris, Pichia trehalophila, Saccharomyces cerevisiae,
Saccharomyces fragilis, Saccharomyces rosei, Saccharomyces
acidifaciens, Saccharomyces elegans, Saccharomyces rouxii,
Saccharomyces lactis, and/or Saccharomyces fractum.
[0116] Suitable bacteria include species from the genera Bacillus,
Mycobacterium, Actinomyces, Nocardia, Pseudomonas, Methanomonas,
Protaminobacter, Methylococcus, Arthrobacter, Methylomonas,
Brevibacterium, Acetobacter, Methylomonas, Brevibacterium,
Acetobacter, Micrococcus, Rhodopseudomonas, Corynebacterium,
Rhodopseudomonas, Microbacterium, Achromobacter, Methylobacter,
Methylosinus, and Methylocystis. Preferred genera include Bacillus,
Pseudomonas, Protaminobacter, Micrococcus, Arthrobacter and/or
Corynebacterium. Examples of suitable species include: Bacillus
subtilus, Bacillus cereus, Bacillus aureus, Bacillus acidi,
Bacillus urici, Bacillus coagulans, Bacillus mycoides, Bacillus
circulans, Bacillus megaterium, Bacillus licheniformis, Pseudomonas
ligustri, Pseudomonas orvilla, Pseudomonas methanica, Pseudomonas
fluorescens, Pseudomonas aeruginosa, Pseudomonas oleovorans,
Pseudomonas putida, Pseudomonas boreopolis, Pseudomonas pyocyanea,
Pseudomonas methylphilus, Pseudomonas brevis, Pseudomonas
acidovorans, Pseudomonas methanoloxidans, Pseudomonas aerogenes,
Protaminobacter ruber, Corynebacterium simplex, Corynebacterium
hydrocarbooxydans, Corynebacterium alkanum, Corynebacterium
oleophilus, Corynebacterium hydrocarboclastus, Corynebacterium
glutamicum, Corynebacterium viscosus, Corynebacterium dioxydans,
Corynebacterium alkanum, Micrococcus cerificans, Micrococcus
rhodius, Arthrobacter rufescens, Arthrobacter parafficum,
Arthrobacter citreus, Methanomonas methanica, Methanomonas
methanooxidans, Methylomonas agile, Methylomonas albus,
Methylomonas rubrum, Methylomonas methanolica, Mycobacterium
rhodochrous, Mycobacterium phlei, Mycobacterium brevicale, Nocardia
salmonicolor, Nocardia minimus, Nocardia corallina, Nocardia
butanica, Rhodopseudomonas capsulatus, Microbacterium
ammoniaphilum, Archromobacter coagulans, Brevibacterium butanicum,
Brevibacterium roseum, Brevibacterium flavum, Brevibacterium
lactofermentum, Brevibacterium paraffinolyticum, Brevibacterium
ketoglutamicum, and/or Brevibacterium insectiphilium.
[0117] The term "microorganism growth-culture medium" shall be
given its ordinary meaning and shall also refer to any medium
promoting the growth of microorganisms. It shall also refer to any
substrate, aside from methane, which microorganisms oxidize or
otherwise break down. It shall also refer to any substrate or
material that concentrates methane, preferentially sequesters
methane, "traps" methane, increases the solubility and/or
availability of methane, and/or otherwise enables the enhanced
breakdown, oxidation, and/or utilization of methane by
microorganisms. The term "microorganism growth-culture medium"
includes, but is not limited to, any substrate and/or microorganism
immobilization means, such as liquid, semi-liquid, gas,
particulate, ceramic, foam, plastic, alginate gel,
methanol-enriched, copper-enriched, clay, nutrient, or other
appropriate growth-culture medium. In one preferred embodiment,
this growth culture medium comprises aqueous solution containing
water, nitrogen, ammonium, trace minerals, and other well-known
microorganism growth-culture medium components necessary for the
growth and reproduction of methane-utilizing bacteria. In another
preferred embodiment, this growth culture medium comprises a
microorganism immobilization means, such as organic or inorganic
particles, on which a liquid or semi-liquid mineral medium solution
is continuously or periodically contacted and on which
microorganisms are attached. In another preferred embodiment, this
growth-culture medium comprises waste organic materials, which
methane-utilizing microorganisms may or may not break down to
produce a byproduct of organic materials that may or may not be
useful. In another preferred embodiment, this growth-culture medium
comprises a liquid foam substrate.
[0118] In yet another preferred embodiment, the growth-culture
medium is combined with various materials which methane-utilizing
microorganisms may or may not convert to more desirable materials.
Examples of various materials include, but are not limited to,
toluene, trichloroethylene (TCE), propylene, and agricultural
byproduct materials which microorganisms may preferentially
breakdown or oxidize.
[0119] In one embodiment, the invention comprises conveying enteric
fermentation methane to an apparatus situated entirely on the body
of a ruminant animal which mutually-exposes methane-utilizing
microorganisms, enteric fermentation methane, and a microorganism
growth-culture medium, causing methane-utilizing microorganisms to
grow using enteric fermentation methane as a source of carbon
and/or energy. Preferred embodiments of the invention are described
below and illustrated by FIGS. 1, 2, and 3.
[0120] FIG. 1 is a side perspective view of an apparatus used to
carry out a process in accordance with the invention. In this
illustration, all of the means necessary for carrying out a process
in accordance with the invention are maintained and situated
entirely on the body of ruminant animal, including means for
conveying ruminant animal exhalation, and the exhalation methane
therein, to a means for mutually-exposing enteric fermentation
methane, methane-utilizing microorganisms, and a microorganism
growth-culture medium, as well as a means for harvesting the
product of methane-utilizing microorganism growth. In other
embodiments, one or more components are not located on the animal,
but instead are coupled to or in communication with the animal.
[0121] In FIG. 1, exhalation collection tubes 15a and 15b are
situated one on either side of the head of ruminant animal 14.
Tubes 15a and 15b are held in place by stationary head harness 16
and lead up to the nostrils of ruminant animal 14. Tubes 15a and
15b run from the nostrils of ruminant animal 14 to where they both
converge into exhalation collection tube convergence T-pipe 18.
T-pipe 18 connects to exhalation inflow tube 19, which leads into
permanent exhalation conveyance structure 20. Structure 20 is
described in further detail by FIGS. 2A and 2B. Structure 20 is
held in place on the back of ruminant animal 14 by stabilizing leg
straps 17a, 17b, 17c, and 17d, as illustrated.
[0122] FIG. 2A is a top cross-sectional view of structure 20, and
FIG. 2B is a side perspective view of structure 20. Tube 19 passes
through air pump housing front wall 29 and leads into exhalation
flow pipe chamber 43. Inside chamber 43, tube 19 connects to inflow
pump chamber tube 21, which leads through chamber 43, through air
pump housing middle wall 30, and into diaphragm-enclosed chamber
23. Where tube 21 opens into chamber 23 is inflow one-way flap
sphincter 22, which, being a one-way flap, allows air to travel
into chamber 23, but does not allow air to travel from chamber 23
into tube 21.
[0123] Chamber 23 is enclosed by rubber diaphragm 44. The open end
of diaphragm 44 is attached to wall 30 so that an air-tight seal is
made, and chamber 23 is formed. Diaphragm pump plunger 31 is
inserted through and into diaphragm 44 on the side of diaphragm 44
farthest from wall 30. Plunger 31 extends out of diaphragm 44 to
where it is joined perpendicularly to rotational gear tooth 32,
which is attached to rotational gear 33. Gear 33 is mounted on
motor axle 36, which leads into direct-current rotational motor 34.
Motor 34 is located inside exhalation motor pumping chamber 45.
Positive motor electrical terminal 46 is connected to permanent
structure positive conduction plate 37 by positive electrical
conduction wire 35. Negative motor electrical terminal 47 is
connected to permanent structure negative conduction plate 38 by
negative electrical conduction wire 48. Plate 37 and plate 38 are
mounted on air pump housing back wall 27 with portions of each
plate protruding through and outside of wall 27. Connected to the
end of plate 37 on the end farthest from chamber 45 is positive
conduction continuation spring 39. Connected to the end of
permanent structure negative conduction plate 38 on the end
farthest from chamber 45 is negative continuation spring 40.
Structurally, an electric current can now flow from spring 39 to
terminal 46 as well as from spring 40 to terminal 47.
[0124] Returning to chamber 23, outflow one-way flap sphincter 24
leads out from chamber 23 and into outflow pump chamber tube 25.
Sphincter 24 allows air to travel out of chamber 23, but it does
not allow air to travel from tube 25 into chamber 23. Tube 25 runs
from chamber 23, through wall 30, and through chamber 43 to where
it finally connects with outflow insertion needle 26. Needle 26
runs from the inside of chamber 43, protrudes through wall 27, and
extends beyond wall 27 directly away from tube 19. Needle 26 is
open on the end farthest from tube 25.
[0125] Half-cylindrical shell 42 is attached to wall 27. The
orientation of shell 42 is depicted in FIG. 2B. Running the length
of shell 42 is inlaid guidance groove 41. As will be described
later, groove 41 has the purpose of guiding removable microorganism
containment capsule 99 into correct orientation with needle 26,
spring 39, and spring 40. Capsule 99 is described in greater detail
in FIGS. 3A and 3B.
[0126] FIG. 3A and FIG. 3B depict capsule 99. Specifically, FIG. 3A
is a side cross-sectional view of capsule 99, and FIG. 3B is a side
perspective view of capsule 99. Structure 20 is designed to support
and feed ruminant animal exhalation (and the methane contained
therein) into capsule 99. Designed accordingly, capsule 99 is
described in three parts: threaded inflow attachment pipe 60,
threaded outflow attachment pipe 62, and microorganism growth
capsule pipe 80. Capsule 99, as a whole, consists of each of these
three pieces connected together, as will be described.
[0127] Pipe 80 is threaded on the outer side of both ends and
contains methane-utilizing microorganisms 92 and microorganism
growth-culture medium 93. In the present embodiment, 5 grams of
Methylococcus capsulatus, methane-utilizing microorganisms which
can be obtained from a number of biological supply depots
(including Chang Bioscience, located at 125 Cambon Drive #6H, San
Francisco, Calif. 94132) are placed in an aqueous microorganism
growth-culture medium containing ammonium, nitrogen, and mineral
salts.
[0128] Attached to one end of pipe 80 is pipe 60. Attached on the
other end of pipe 80 is pipe 62. Pipe 60 houses D-size battery 75,
which is situated between removable capsule positive electrical
conduction terminal 70, removable capsule negative electrical
conduction plate 74, and inflow attachment pipe inner wall 76.
Plate 74 rests against wall 76 and sits adjacent to battery 75.
Terminal 70 sits adjacent to battery 75 and protrudes through the
front side of pipe 60. Similarly, terminal 71 protrudes through the
front side of pipe 60 from the inside of pipe 60. Capsule negative
electrical conduction wire 49 runs from terminal 71 to plate 74.
Running from the outer edge of the front side of pipe 60, passing
through wall 76, and extending beyond wall 76 into pipe 80 is air
dispersion capillary tube 72. Tube 72 is a solid tube except for
the portion extending into pipe 80, which contains tiny capillary
holes in its walls that allow air to pass out of tube 72 but do not
allow medium 93 to pass into tube 72. Tube 72 is open at the end
meeting the outer edge of the front side of pipe 60, and closed at
its opposite end. Attached to the outside of pipe 60 is inflow
guidance ridge 89, a solid piece of material which will eventually
fit into groove 41 illustrated in FIG. 2A and FIG. 2B.
[0129] Attached to pipe 80 on the end opposite pipe 60 is pipe 62.
Pipe 62 is an elbow-shaped pipe that allows air to escape after it
has passed through the small holes in the walls of tube 72. Pipe 62
is a hollow piece of piece of pipe at the end where it is connected
to pipe 80, though, at its other end, pipe 62 is a solid piece of
pipe. Wire mesh grating 61 is located inside pipe 62 at the border
of where pipe 62 turns from hollow to solid. Still inside of pipe
62, adjacent to grating 61 in the solid portion of pipe 62, leak
prevention holes 63a and 63b are drilled through the solid piece of
pipe 62. Inside of hole 63a are plug balls 64a and 64b. Inside of
hole 63b are plug balls 64c and 64d. Balls 64a, 64b, 64c, and 64d
are rubber balls which can float on the surface of medium 93. Holes
63a and 63b are partially blocked at both the ends farthest and the
ends closest to the hollow portion of pipe 62. Holes 63a and 63b
are partially blocked by grating 61 at the end closest to the
hollow portion of pipe 62. While the diameters of holes 63a and 63b
are constant throughout, the diameters decrease at the ends
farthest from the hollow portion of pipe 62 such that a single ball
(64a or 64c) cannot pass through that end. Similar to ridge 89,
outflow guidance ridge 90, which is able to slide into groove 41,
is located on the outside of pipe 62.
[0130] The following is a description of one method by which an
apparatus is used to carry out a process in accordance with one
embodiment of the invention.
[0131] First, structure 20 is situated on the back of ruminant
animal 14 using straps 17a, 17b, 17c, and 17d. Next, harness 16 is
attached to the head of ruminant animal 14, and tubes 15a and 15b
are connected to harness 16 such that tubes 15a and 15b lead from
T-pipe 18 up to the nostrils of ruminant animal 14.
[0132] Second, capsule 99 is placed into shell 42 of structure 20.
This is accomplished by inserting ridge 89 and ridge 90 on capsule
99 into groove 41 inlaid in shell 42 of structure 20. With capsule
99 aligned with structure 20, capsule 99 is slid towards wall 27 up
to the point where needle 26 is inserted into tube 72, and spring
39 and spring 40 are placed, respectively, into contact with
terminal 70 and terminal 71. With terminal 70 and terminal 71
placed into contact with spring 39 and spring 40, respectively, an
electrical current now runs from battery 75 in capsule 99 to motor
34 in structure 20. Specifically, a positive electrical current
runs from battery 75, through terminal 70, through spring 39,
through plate 37, though wire 35, to terminal 46. A negative
electrical current runs from battery 75, through plate 74, through
wire 49, through terminal 71, through spring 40, through plate 38,
through wire 48, to terminal 47.
[0133] With an electrical current running from battery 75 to motor
34, axle 36 on motor 34 begins to rotate rapidly. As axle 36
rotates, gear 33 and gear tooth 32 also rotate rapidly, which in
turn causes plunger 31 to rapidly push and pull diaphragm 44. With
diaphragm 44 oscillating towards and away from wall 30, the motion
of diaphragm 44 causes air to flow from tubes 15a and 15b, into
chamber 23, and into needle 26. To expand, air is pulled through
tubes 15a and 15b, through T-pipe 18, through tube 19, through tube
21, past sphincter 22, through chamber 23, past sphincter 24,
through tube 25, and into needle 26.
[0134] With capsule 99 inserted, as described above, into structure
20, air now travels from needle 26 into tube 72. Since tube 72 is
blocked at the end located in pipe 80 and since air cannot travel
from tube 72 back into chamber 23, air is forced out through the
tiny holes which exist in the walls of tube 72. To reiterate a
detail mentioned above, in one embodiment, tiny holes exist in the
walls of tube 72 only where tube 72 extends into pipe 80. The
result is that air is conveyed from needle 26, through tube 72, and
into pipe 80. Eventually, with no other means of escape, the air
inside pipe 80 flows into the hollow portion of pipe 62, past
grating 61, into holes 63a and 63b, past plug balls 64a, 64b, 64c,
and 64d, out of holes 63a and 63b.
[0135] The result of this conveyance of air is that as ruminant
animal 14 exhales, this exhalation, as well as exhalation methane
therein, is conveyed and directed into tubes 15a and 15b, which are
situated just above the nostrils of ruminant animal 14. Exhalation
methane now travels through tubes 15a and 15b to needle 26. With
capsule 99 inserted, as described above, into structure 20,
exhalation methane of ruminant animal 14 travels through needle 26
into pipe 80.
[0136] Pipe 80 contains microorganisms 92 and medium 93, and when
exhalation methane is conveyed into pipe 80, microorganisms 92 grow
and reproduce using this exhalation methane as a source of carbon
and/or energy. Put differently, exhalation methane, microorganisms
92, and medium 93 are mutually-exposed in pipe 80. Thus, as more
exhalation methane from ruminant animal 14 is exposed to
microorganisms 92 in medium 93, microorganisms 92 grow and
reproduce using exhalation methane as a source of carbon and/or
energy. All excess gases, including waste carbon dioxide and waste
exhalation methane, exit capsule 99 as described above.
[0137] Although medium 93 is an aqueous medium, holes 63a and 63b,
balls 64a, 64b, 64c, and 64d, and grating 61 act together to
prevent medium 93 from spilling or escaping out of capsule 99.
Specifically, since plug balls 64a, 64b, 64c, and 64d are designed
to float on the surface of medium 93, if medium 93 travels past
grating 61 and moves into holes 63a and/or 63b, balls 64a and 64c
will plug the small-diameter end of holes 63a and 63b,
respectively, before the aqueous medium 93 can pass out of capsule
99.
[0138] The process continues when, after a certain amount of time
(in this embodiment approximately 7 days) it is determined that
microorganisms 92 within capsule 99 are no longer growing at
optimal rates or have stopped growing completely, and capsule 99 is
removed from structure 20. The microorganism growth process is
re-started and continued simply by replacing previously-used
capsule 99 with a new apparatus structurally identical to capsule
99 containing new methane-utilizing microorganisms and a new
microorganism growth-culture medium. The process may also be
continued by re-using capsule 99 and, after removing all or most of
microorganisms 92 and medium 93, filling it with new microorganism
growth-culture medium and an optimal number of new or previously
used methane-utilizing microorganisms. In such a manner, exhalation
methane is continually used as a source of carbon and/or energy for
the growth and harvesting of methane-utilizing microorganisms.
[0139] Finally, microorganisms 92, having been grown in capsule 99
using exhalation methane as a source of carbon and/or energy, are
removed from capsule 99 and harvested as useful biomass.
(Methylococcus capsulatus has a biomass which consists of about
seventy percent protein by weight). Such biomass can be processed
and sold as a nutritional foodstuff or converted into other useful
products, such as adhesives or cosmetics.
[0140] In one preferred embodiment, as detailed by FIG. 4,
"mutual-exposure means" shall be given its ordinary meaning and
shall also refer to any apparatus housing, holding, or containing a
methane-consumption system such as microorganisms, fuel cells, or
microturbines. In one embodiment, this apparatus comprises a
holding tank containing methane-utilizing microorganisms and a
microorganism growth-culture medium. In another embodiment, this
apparatus comprises the materials housing and/or supporting the
operation of a reverse-flow reactor, an engine, a fuel cell, and/or
a microturbine. In another embodiment, this means comprises a
temperature-controlled, stainless-steel cylindrical bioreactor
apparatus containing, holding, or enclosing methanotrophic
microorganism growth-culture medium and methane-utilizing
microorganisms, into which enclosure air, including ammonia and
ruminant animal methane, is fed, conveyed, or directed, which
subsequently allows microorganisms to grow and reproduce utilizing
ruminant animal methane as a source of carbon and/or energy for
growth. In another embodiment, the growth of random, non-specified,
genetically-engineered, pre-determined, and/or non-pre-determined
methane-utilizing microorganisms in such a bioreactor may be used
to lower the concentration of ammonia in enclosure air. In another
embodiment, means are provided to trap or capture dust and other
airborne matter in the enclosure air such that any or all of such
matter does not actually contact a methane-consumption means, such
as methane-utilizing microorganisms or a methane-driven
microturbine, reverse-flow reactor, or fuel cell. In this way, a
mutual-exposure means may be used not only to carry out
methane-driven processes, but also to lower the dust, ammonia,
and/or airborne matter contents in enclosure air.
[0141] Several embodiments of the subject invention pertain to the
utilization of the enteric fermentation methane produced by
ruminant animals for the production of methane-based goods. More
particularly, some embodiments of the present invention pertain to
the process of utilizing ruminant animal enteric fermentation
methane emissions in which the method comprises: (a) providing one
or more ruminant animals, (b) providing enteric
fermentation-derived methane gas that has been emitted by the
animals, including air containing the methane, (c) providing means
to capture, consolidate, and/or direct the methane, including an
enclosure means to enclose the animals, the air, and the methane
contained in the air, and, preferentially, a ventilation means to
direct the air, (d) providing a methane-consumption means which can
use the methane as a source of carbon and/or energy for the
induction of a methane-based process and/or for the production of
methane-based goods, and (e) contacting the methane with the
methane-consumption means to cause the methane-consumption means to
oxidize, consume, and/or otherwise utilize the methane for the
operation of a methane-based process or for the production of one
or more methane-based products, including methane-utilizing
microorganisms, heat, and/or electricity. Another embodiment of the
invention pertains to the process wherein: a) one more ruminant
animals are fully or partially enclosed by a well-known enclosure
means, such as a barn, and b) air contained in an ruminant animal
enclosure means, including the enteric fermentation methane
contained therein, is further directed and exposed to a
methane-consumption system, whereby enteric fermentation methane is
used as a novel source of carbon and/or energy for the production
of heat, electricity, or, as in one preferred embodiment,
methane-utilizing microorganisms.
[0142] In one preferred embodiment, the method of the subject
invention involves contacting enteric fermentation methane
contained within enclosed barn air with a microbiological
methane-consumption system, wherein enteric fermentation methane,
methane-utilizing microorganisms, and a microorganism
growth-culture medium are mutually-exposed, causing
methane-utilizing microorganisms to grow using enteric fermentation
methane as a source of carbon and/or energy.
[0143] FIG. 4 is a flow chart of a process carried out in
accordance with the invention. In the schematic, ruminant animal
114 is situated in enclosure means 115, whereby ruminant animal 114
is substantially enclosed, isolated, and contained by and in
enclosure means 115. In one preferred embodiment, enclosure means
115 includes a barn with four sidewalls and a roof
[0144] Enclosure means 115, in one embodiment, contains enclosure
air 120. Enclosure means 115 is equipped with air inlet 116 and air
outlet 117, through which air, gases, and other airborne materials
are substantially confined to enter and exit enclosure means 115,
respectively. In one preferred embodiment, air inlet 116 consists
of a spatial opening, such as a window, in a side wall of enclosure
means 115, and air outlet 117 consists of a spatial opening housing
ventilation means 113, through which air, gases, and other airborne
material exit out of inside enclosure means 115. In one preferred
embodiment, ventilation means 113 consists of a well-known
ventilation fan that is used to pull air into enclosure means 115
through air inlet 116 and convey air out of enclosure means 115
through air outlet 117.
[0145] Consolidation means 118, in one embodiment, is a duct that
directs enclosure air 120 coming out of air outlet 117 in such a
way that it can be contacted with confined methane-utilizing
microorganisms 121. In the embodiment depicted, mutual-exposure
means 119 is a holding tank containing a methane-consumption means,
embodied as methane-utilizing microorganisms 121, and microorganism
growth-culture medium 122. In the embodiment depicted,
methane-utilizing microorganisms 121 are present in growth-culture
medium 122 at a concentration of 20 grams of microorganisms per
liter of medium, and consist of methane-utilizing microorganisms
such as Methylococcus capsulatus that can be obtained from any
number of well known biological supply depots (including Chang
Bioscience, located at 125 Cambon Drive #6H, San Francisco, Calif.
94132). Growth-culture medium 122, as herein embodied, is an
aqueous medium containing suitable ammonium, mineral salts, and
other well-known growth-culture components, which support the
growth of methane-utilizing microorganisms 121.
[0146] The following is a description of one method by which to
carry out a process in accordance with one embodiment of the
invention. First, ruminant animal 114 is enclosed by enclosure
means 115, and ruminant animal emits methane gas into enclosure air
120 through processes associated with enteric fermentation. Next,
through the force of ventilation means 113, air is conveyed into
enclosure means 115 through air inlet 116, through enclosure means
115, and out of enclosure means 115 through air outlet 117.
Enclosure air 120 containing enteric fermentation methane is next
conveyed out of air outlet 117, through consolidation means 118 to
be contacted with methane utilizing microorganisms 121 in
mutual-exposure means 119 through the force created by ventilation
means 113. Inside mutual-exposure means 119, enteric fermentation
methane contained within enclosure air 120 is exposed to
methane-utilizing microorganisms 121 and growth-culture medium 122,
causing methane-utilizing microorganisms 121 to grow and reproduce
using enteric fermentation methane as a source of carbon and/or
energy. The process continues when, after a certain amount of time
(in this embodiment approximately 7 days) it is determined that
methane-utilizing microorganisms 121 within mutual-exposure means
119 are no longer growing at optimal rates, and the microorganism
growth process is augmented by removing portions of growth-culture
medium 122 and methane-utilizing microorganisms 121 from
mutual-exposure means 119 and adding new portions of growth-culture
medium 122 and/or methane-utilizing microorganisms 121. In such a
manner, enteric fermentation methane is continually used as a
source of carbon and/or energy for the continuous growth and
harvesting of methane-utilizing microorganisms. Finally,
methane-utilizing microorganisms 121, having been grown in
mutual-exposure means 119 using enteric fermentation methane as a
source of carbon and/or energy, are removed from mutual-exposure
means 119 and harvested as useful biomass. Such biomass can be
processed and sold as a range of useful biomass-based products.
[0147] In one preferred embodiment, as described earlier,
ventilation means 113 are employed to move 10 cubic feet of
enclosure air 120 out of air outlet 117 each minute, such that
fresh air enters into enclosure means 115 at the same rate, and
enclosure air 120 is cooled by the air cooling means described
earlier. As described, a dairy cow produces approximately 150
kilograms of methane per year, which correlates to the production
of approximately 0.4 liters per minute of enteric fermentation
methane. Thus, by enclosing ruminant animal 114 with enclosure
means 115 and employing ventilation means 113, the concentration of
methane in enclosure air 120 conveyed into mutual-exposure means is
at least 0.1% methane by volume, or 1000 parts per million. By
decreasing or increasing ventilation rates, the concentration of
methane in enclosure air 120 increases or decreases accordingly.
Methane-utilizing microorganisms are able to grow and reproduce
using methane as a source of carbon and/or energy in an environment
wherein the concentration of methane-in-air is at least 1.7 parts
per million. Thus, methane-utilizing microorganisms 121 are enabled
to grow and reproduce using enteric fermentation methane as a novel
source of energy in one preferred embodiment.
[0148] Several embodiments of the present invention pertain to the
utilization of enteric fermentation as a novel source of energy for
the production of methane-based goods in a confined
methane-consumption apparatus existing outside the digestive tract
of a ruminant animal. There are a number of potential methods that
can be used to carry out a process in accordance with embodiments
of the invention. In particular, there are a number of methods that
can be utilized to capture enteric fermentation methane with
enclosure and ventilation means and mutually-expose enteric
fermentation methane and a methane-consumption means for the
purpose of causing enteric fermentation methane to be utilized as a
source of carbon and/or energy.
[0149] In some embodiments, such methods include, but are not
limited to, providing methane-consumption means to convert enteric
fermentation methane into heat and/or electricity. In one
embodiment, methane is capable of being used at a methane-in-air
volumetric concentration down to abut 0.1% methane-in-air,
specifically by catalytic and thermal flow-reversal reactors. Thus,
systems such as these could be used as a means to utilize enteric
fermentation as a viable, low-concentration source of energy in
accordance with the invention. Specifically, microturbines, fuel
cells, reverse-flow reactors and other means capable of utilizing
methane at low concentrations can be used as a methane-consumption
means in accordance with the invention, allowing enclosure air to
be used in an unadulterated state as viable feedstock fuel. Gas
concentrators that increase methane-in-air concentrations of
exhaust gas could also be employed to increase methane
concentrations to levels more suitable for use by a range of
methane-consumption means. Thus, although one preferred embodiment
details the use of methane-utilizing microorganism as a preferred
methane-consumption means, in another embodiment, any number of
methane-consumption means may be employed in accordance with
embodiments of the invention to convert enteric fermentation
methane into useful products such as heat and/or electricity.
[0150] In some embodiments, such methods also include the combined
use of non-enteric fermentation methane and enteric fermentation
methane in or by a methane-consumption means, such that enteric
fermentation methane can be partially used to drive one or more
methane-consumption means, such as fuel cells, turbines,
microturbines, methane-utilizing microorganisms, and other
methane-based systems. Such alternative sources of supplemental
methane might include: methane from agricultural manure digesters,
agricultural manure holding structures, landfills, coal mines,
wastewater treatment facilities, and/or natural gas.
[0151] In some embodiments, such methods further include the
utilization of a chemical-based methane-consumption means to use
enteric fermentation methane as a source of carbon and/or energy.
Specifically, a number of methods are well known to convert methane
into industrial feedstock products, such as methanol, through the
mutual exposure of methane and various chemicals under a variety of
conditions. Suitable chemical processing methods of this nature
could be applied to enteric fermentation methane in accordance with
the principles of the invention, especially through the combined
use of enteric fermentation methane and alternative sources of
methane, as enumerated above, to increase the yields, viability,
and efficiency of the process.
[0152] In several embodiments, such methods also include using
methane-utilizing microorganisms to simultaneously reduce both
ammonia and methane emissions from ruminant animal feedlots. In one
preferred embodiment, enclosure air 120 will likely contain varying
amounts of ammonia gas. It is well known that contacting ammonia
gas with liquid water changes ammonia gas into aqueous ammonium, as
would occur in mutual-exposure means 119 of one preferred
embodiment listed above when enclosure gas 120 is contacted with
growth-culture medium 122. It is well known that methane-utilizing
microorganisms utilize ammonium in water as a source of nitrogen
for growth. Thus, one embodiment of the invention may include the
use of unadulterated enteric fermentation to not only produce
methane-utilizing microorganisms, but to simultaneously reduce
feedlot ammonia emissions as well.
[0153] In some embodiments, such methods also include using
enclosure means and/or methane-consumption means, as detailed
above, to reduce dust or suspended particles emissions associated
with ruminant animals. In order to increase the efficiency of a
methane-driven system as detailed above, a filter may be used to
prevent dust and/or other airborne particles from entering into
mutual exposure means 119. Thus, a process employed in accordance
with the invention may be used to reduce enteric fermentation
methane emissions while simultaneously reducing emissions of
suspended particles typically associated with ruminant animals.
[0154] In some embodiments, such methods further include providing
means to convey enclosure air 120 from areas enclosed by enclosure
means 115 where enteric fermentation methane is known to
accumulate, such as near feeding tracts, roof lines, or other
potential methane accumulation areas. Such methods also include
situating a means for mutual-exposure containing a
methane-consumption means inside of an area enclosed an enclosure
means, wherein means may or may not be provided to continuously or
mechanically direct enclosure air to contact a methane-consumption
system, but in either case causing enteric fermentation to be
utilized as a source of energy for the production of methane-based
goods.
[0155] In one embodiment, enteric fermentation methane is used as a
novel source of energy for the production of methane-utilizing
microorganisms in a confined growth-and-harvest apparatus existing
outside of the digestive tract of a ruminant animal. There are a
number of potential methods that can be used to carry out a process
in accordance with the invention. In particular, there are a number
of methods that can be used to mutually-expose enteric fermentation
methane, methane-utilizing microorganisms, and a microorganism
growth-culture medium for the purpose of causing methane-utilizing
microorganisms to grow using enteric fermentation methane as a
source of carbon and/or energy.
[0156] In some embodiments, such methods include confining a
ruminant animal to a site provided with means to funnel, convey,
and/or direct enteric fermentation methane into an apparatus
whereby such enteric fermentation methane is used to grow
methane-utilizing microorganisms in a confined apparatus, and
whereby the means used to carry out this process are either
partially situated on a ruminant animal or not at all situated on a
ruminant animal.
[0157] In some embodiments, such methods also include providing
means to convey enteric fermentation methane from a site where
ruminant animals are known to frequent, such as feeding or sleeping
areas, to a means for the mutual-exposure of enteric fermentation
methane, methane-utilizing microorganisms, and a microorganism
growth-culture medium, whereby methane-utilizing microorganisms
grow using enteric fermentation methane as a source of carbon
and/or energy in an apparatus existing outside of the digestive
tract of a ruminant animal.
[0158] In some embodiments, such methods also include causing
methane-utilizing microorganisms to grow by mutually-exposing
enteric fermentation methane, methane-utilizing microorganisms, and
a microorganism growth-culture medium in a confined apparatus,
wherein some or all of the methane-utilizing microorganisms are
genetically-engineered.
[0159] In some embodiments, such methods also include growing
methane-utilizing microorganisms using enteric fermentation methane
as a source of carbon and/or energy for such growth, whereby the
means used to carry out the process are powered by solar, wind,
methane-based, or other suitable form of power different from the
source of power--battery power--mentioned in the above detailed
description.
[0160] There are also a number of methods in accordance with
several embodiments of the invention that can be used to
mutually-expose enteric fermentation methane, methane-utilizing
microorganisms, and a microorganism growth-culture medium for the
purpose of causing methane-consumption systems to operate using
enteric fermentation methane as a source of carbon and/or
energy.
[0161] In some embodiments, such methods also include collecting,
storing, and/or transporting ruminant animal methane (or gaseous
emissions from non-animal sources) for later use in a process
carried out in accordance with the invention.
[0162] The following Example illustrates some embodiments of the
present invention and is not intended in any way to limit the
invention. Moreover, the methods described in the following example
need not be performed in the sequence presented.
Example 1
[0163] The following example describes the processing of methane
emissions from a landfill site. One of skill in the art will
understand that the method described herein can also be used for
any site that produces methane, such as coal mines, wastewater
treatment plants, manure digesters, agricultural digesters, compost
heaps, or enclosed agricultural feedlots.
[0164] In one embodiment, a landfill site that produces methane
emissions will be identified. Landfill gas extraction wells and
blowers are employed to draw landfill gas out of the landfill using
equipment and technology that is used by any landfill gas
extraction or environmental services firm, such as LFG Technologies
of Fairport, N.Y., USA or SCS Engineers of Long Beach, Calif., USA.
The methane content of the extracted landfill gas can be monitored
for the production of methane using any methane detector commonly
used by an environmental services firm. If the methane
concentration is greater than about 1%, the landfill will be deemed
suitable for methane recovery and processing. In some embodiments,
the methane concentration is between about 10% and 60%, more
preferably between 40% and 50%. In other embodiments, methane
emissions comprise methane in a concentration in the range of about
0.1% to about 10%, in the range of about 10% to about 20%, or in
the range of about 20% to about 40%, or greater than about 20%.
Landfill sites (or other sites) having methane concentrations less
than 1% and greater than 60% may also be used in some embodiments
of the invention.
[0165] After a suitable landfill site has been identified, the
landfill gas will be captured from the landfill using an air
compressor, blower, vacuum, or other suitable capturing means.
Impurities will then be removed from the landfill gas. For example,
non-methane organic compounds can be removed by passing the
landfill gas through activated carbon, leaving mostly methane and
carbon dioxide as the main components of the landfill gas. Although
impurities need not be removed in every embodiment of the
invention, the removal of impurities is advantageous in some
embodiments. One advantage of removing impurities (such as water
vapor, volatile organic compounds, particulate materials, and/or
carbon dioxide) is minimizing the possibility of hindering
microorganism growth as microorganisms contact the landfill
gas.
[0166] The landfill gas is optionally disinfected using UV light.
In those embodiments in which impurities are removed, UV
irradiation can be used before, after or during the removal
process. UV irradiation may also be used in embodiments that do not
employ impurities removal. UV light is believed to disinfect the
landfill gas by disrupting the nucleic acid structures within
microorganisms in the landfill gas, subsequently eliminating the
capacity of these microorganisms to reproduce. Impurities removal
and disinfection do not have to be employed, however, because
methanotrophic microorganisms can withstand a range of
impurities.
[0167] The landfill gas (which in a preferred embodiment is
purified and disinfected) as well as air or oxygen (which in one
embodiment is purified and/or disinfected) will be fed into a
self-contained enclosure using an air compressor, air blower, or
similar means. The self-contained enclosure is preferably a
bioreactor that contains at least one species of methanotrophic
microorganisms and growth medium. The bioreactor is preferably
sized to accommodate the flow rate of landfill gas to be treated.
For example, a bioreactor treating 1000 cubic feet per minute of
landfill gas should be approximately twice as large in volume as a
bioreactor treating 500 cubic feet per minute of landfill gas.
Preferably, a bioreactor treating 1000 cubic per minute of landfill
gas will contain about 100,000-800,000 liters of growth medium
containing suspended methanotrophic microorganisms. Growth medium
can be a liquid, semi-liquid, or solid substrate. For example, the
growth medium may be water containing growth nutrients such as
nitrogen and trace minerals, in which microorganisms are
suspended.
[0168] In one embodiment, the growth medium can be tailored to meet
the specification of the end-product of microorganism growth. If
the bioreactor is being used to create soluble methane
monooxygenase, for example, it will be preferable to keep the
copper concentration in the growth medium sufficiently low, for
example, below about 5.times.10.sup.-9 M, which may be achieved
through continuous monitoring of the growth medium and calculated
metering of copper into the growth medium.
[0169] The growth medium solution may consist of water filled with
a range of mineral salts. For example, each liter of growth medium
may be comprised of 1 g KH.sub.2PO.sub.4, 1 g K.sub.2HPO.sub.4, 1 g
KNO.sub.3, 1 g NaCl, 0.2 g MgSO.sub.4, 26 mg CaCl.sub.2*2H.sub.2O,
5.2 mg EDTA Na.sub.4(H.sub.2O).sub.2, 1.5 mg FeCl.sub.2*4H.sub.2O,
0.12 mg CoCl.sub.2*6H.sub.2O, 0.1 mg MnCl.sub.2*2H.sub.2O, 0.07 mg
ZnCl.sub.2, 0.06 mg H.sub.3BO.sub.3, 0.025 mg NiCl.sub.2*6H.sub.2O,
0.025 mg NaMoO.sub.4*2H.sub.2O, 0.015 mg CuCl.sub.2*2H.sub.2O, or a
combination thereof. In another embodiment, the growth medium
comprises solid and/or liquid media. In yet another embodiment, the
growth medium comprises agar.
[0170] Methanotrophic microorganisms may be present in the
bioreactor in any concentration. Preferably, in one embodiment,
there are about 1 to 100 grams of microorganisms per liter of water
(or other aqueous solution) in the bioreactor, preferably about
10-50 grams per liter, more preferably about 40-50 grams per liter,
over the course of treatment. The methanotrophic microorganisms are
exposed to the methane within landfill gas for about 1-200 hours,
preferably about 24-96 hours, whereupon a portion of the
microorganisms within the bioreactor, preferably about 10-50%, are
removed and replaced with fresh growth media or growth media
containing a low concentration of microorganisms, in order to allow
more methanotrophic microorganisms to grow in the bioreactor and
continue to treat the methane within the landfill gas at high
rates.
[0171] The microorganisms that are removed from the bioreactor are
processed further according to the specification of the end-product
of microorganism growth. For example, if the microorganism biomass
is to be used directly as a protein source, the suspended biomass
may be dewatered in a belt filter press, bag filter, spray drier,
and/or centrifuge, all of which may be used to reduce the water
content of the biomass, preferably below about 10-20% total biomass
weight. If the microorganism biomass is to be used to generate a
polymer such as PHB, the microorganisms may be exposed to a
bioreactor receiving a continuous supply of landfill gas and air or
oxygen, wherein the growth medium is deprived of a specific
essential nutrient, such as nitrogen, in order to cause the
microorganisms to synthesize intracellular PHB. After a period of
about 1-3 days, some portion of the bioreactor may then be removed
in order to harvest the products of bioreactor growth, in this case
PHB. PHB may be harvested through a variety of well known cell
extraction and polymer purification techniques. Dewatering methods
may include, but are not limited to, the use of centrifuges, spray
driers, or belt filter presses. Cell lysis and cell parts
separation methods may include, but are not limited to, the use of
hot chloroform, sodium hydroxide, cell freezing, sonication, and
homogenization. For homogenization, the pressure drop is preferably
between about 5000 and 10,000 bar to effect sufficient cellular
lysis. For the use of sodium hydroxide, the concentration of sodium
hydroxide is preferably raised to approximately 2 M. Isolated,
dried, and harvested microorganism product, such as biomass,
polymer, or enzyme, may be used or sold for use.
[0172] While the above description of preferred systems and methods
of carrying out processes in accordance with embodiments of
invention contains many specificities, these should not be
construed as limitations on the scope of the invention. As stated,
there are a number of ways to carry out a process in accordance
with invention. Accordingly, the scope of the invention should be
determined not by the preferred systems and methods described, but
by the appended claims and their legal equivalents.
* * * * *