U.S. patent application number 11/443889 was filed with the patent office on 2006-12-07 for dual hydrogen production apparatus.
Invention is credited to Harry R. Diz, Justin Felder, Mitchell S. Felder.
Application Number | 20060272956 11/443889 |
Document ID | / |
Family ID | 37482201 |
Filed Date | 2006-12-07 |
United States Patent
Application |
20060272956 |
Kind Code |
A1 |
Felder; Mitchell S. ; et
al. |
December 7, 2006 |
Dual hydrogen production apparatus
Abstract
The present invention provides an apparatus for the dual
production of hydrogen, wherein organic feed material of a primary
hydrogen production apparatus is heated with excess or diverted
heat from a secondary hydrogen production apparatus, thereby
substantially deactivating or killing methanogens within the
organic feed material. Hydrogen producing microorganisms contained
or added to the organic feed material metabolize the organic feed
material in a bioreactor to produce hydrogen in a primary hydrogen
production apparatus. As the methanogens are no longer
substantially present to convert produced hydrogen to methane, a
biogas that contains hydrogen without substantial methane can be
produced.
Inventors: |
Felder; Mitchell S.;
(Hermitage, PA) ; Felder; Justin; (Hermitage,
PA) ; Diz; Harry R.; (Erie, PA) |
Correspondence
Address: |
ECKERT SEAMANS CHERIN & MELLOTT
600 GRANT STREET
44TH FLOOR
PITTSBURGH
PA
15219
US
|
Family ID: |
37482201 |
Appl. No.: |
11/443889 |
Filed: |
May 31, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60685851 |
May 31, 2005 |
|
|
|
Current U.S.
Class: |
205/637 |
Current CPC
Class: |
C12M 47/18 20130101;
C12M 21/04 20130101; C12M 41/26 20130101; C12M 45/20 20130101; Y02P
20/129 20151101; C25B 1/02 20130101; Y02E 60/36 20130101; C25B 9/73
20210101; C25B 1/04 20130101; C12M 41/28 20130101 |
Class at
Publication: |
205/637 |
International
Class: |
C25B 1/02 20060101
C25B001/02 |
Claims
1. An apparatus for dually producing hydrogen, comprising: a
secondary hydrogen production apparatus including an apparatus that
breaks down chemical compounds, wherein hydrogen is produced from
one or a series of reactions using heated liquids, vapors or gases,
a primary hydrogen production apparatus operably combined with the
secondary hydrogen production apparatus, the primary hydrogen
production apparatus including a bioreactor adapted to produce
hydrogen from microorganisms metabolizing an organic feed material,
and a heat exchanger operably associated with the primary and
secondary hydrogen production apparatuses such that heat from the
secondary hydrogen production apparatus is transferred to the
primary hydrogen production apparatus.
2. The apparatus of claim 1, wherein the heated liquids, vapors and
gases are selected from the group comprising of water, steam,
hydrochloric acid, oxygen and sulfur dioxide.
3. The apparatus of claim 1, wherein the heated liquids, vapors and
gases in the secondary hydrogen production apparatus are at a
temperature in a range of about 100 to 1000.degree. C.
4. The apparatus of claim 1, wherein the organic feed material is
heated for a period of at least fifteen minutes.
5. The apparatus of claim 1, wherein the organic feed material is
heated by the heat to a temperature of about 60 to 100.degree.
C.
6. The apparatus of claim 1, wherein the organic feed material in
the bioreactor has a controlled pH by a pH controlling device.
7. The apparatus of claim 1, wherein the secondary hydrogen
production apparatus is a steam based high temperature
electrolyzer.
8. The apparatus of claim 1, wherein the secondary hydrogen
production apparatus is a water based high temperature
electrolyzer.
9. The apparatus of claim 1, wherein the secondary hydrogen
production apparatus is an apparatus conducive to sulfur iodide
processes.
10. The apparatus of claim 1, wherein the heat-exchanger is a
gas/liquid heat exchanger.
11. The apparatus of claim 1 wherein the heat-exchanger is a
liquid/liquid heat exchanger.
12. The apparatus of claim 1, wherein the primary hydrogen
production apparatus further comprises a passage providing entry
access to the bioreactor and providing removal access to the heat
exchanger.
13. The apparatus of claim 12, further providing treatment means
for treating an organic feed material contained within the primary
hydrogen production apparatus.
14. The apparatus of claim 12, further comprising an electronic
controller having at least one microprocessor adapted to process
signals from a one or a plurality of devices providing organic feed
material parameter information, wherein the electronic controller
is connected to the at least one actuatable terminal and is
arranged to control the operation of the heat exchanger and the
temperature of any contents therein.
15. The apparatus of claim 12, further comprising a pump operably
related to the passage.
16. An apparatus for dually producing hydrogen, comprising: a
secondary hydrogen production apparatus including an electrolyzer,
wherein hydrogen is produced from one or a series of reactions
using heated liquids, vapors or gases, a primary hydrogen
production apparatus operably combined with the secondary hydrogen
production apparatus, the primary hydrogen production apparatus
including a bioreactor adapted to produce hydrogen from
microorganisms metabolizing an organic feed material, and a heat
exchanger operably associated with the primary and secondary
hydrogen production apparatuses such that heat from the secondary
hydrogen production apparatus is transferred to the primary
hydrogen production apparatus.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims priority under 35 U.S.C.
.sctn.119(e) to U.S. Provisional Patent Application Ser. No.
60/685,851, filed May 31, 2005, entitled "COMBINATION BIOREACTOR
AND ELECTROLYZER FOR PRODUCTION OF HYDROGEN"
FIELD OF THE INVENTION
[0002] The present invention relates generally to a combination
apparatus for concentrated production of hydrogen from hydrogen
producing microorganism cultures. More particularly, the invention
relates to a method that dually combines a primary hydrogen
production apparatus with a secondary hydrogen production apparatus
that is different than the primary hydrogen production apparatus.
The primary hydrogen production apparatus uses heat or uses heat
waste that is produced during typical usage of the secondary
hydrogen production apparatus, thereby reducing energy costs of the
primary hydrogen production apparatus and conserving energy.
BACKGROUND OF THE INVENTION
[0003] The production of hydrogen is an increasingly common and
important procedure in the world today. Production of hydrogen in
the U.S. alone currently amounts to about 3 billion cubic feet per
year, with output likely to increase. Uses for the produced
hydrogen are varied, ranging from uses in welding to production of
hydrochloric acid. An increasingly important use of hydrogen
relates to the production of alternative fuels for machinery such
as motor vehicles. Successful use of hydrogen as an alternative
fuel can provide substantial benefits to the world at large. This
is important not only in that the hydrogen can be formed without
dependence on the location of specific oils or other ground
resources, but in that burning of hydrogen for fuel is
atmospherically clean. Essentially, no carbon dioxide or greenhouse
gasses are produced during the burning. Thus, production of
hydrogen is an environmentally desirable goal.
[0004] Creation of hydrogen from certain methods and apparatuses
are generally known. For example, electrolysis, which generally
involves the use of electricity to decompose water into hydrogen
and oxygen, is a commonly used process. Significant energy,
however, is required to produce the needed electricity to perform
the process. Similarly, steam reforming is another expensive method
requiring fossil fuels as an energy source. As could be readily
understood, the environmental benefits of producing hydrogen are at
least partially offset when using a process that uses
pollution-causing fuels as an energy source for the production of
hydrogen.
[0005] New methods of hydrogen generation are therefore needed. One
possible method is to create hydrogen in a biological system by
converting organic matter into hydrogen gas. The creation of a
biogas that is substantially hydrogen can theoretically be achieved
in a bioreactor, wherein hydrogen producing microorganisms and an
organic feed material are held in an environment favorable to
hydrogen production. Substantial and useful creation of hydrogen
gas from microorganisms, however, is problematic. The primary
obstacle to sustained production of useful quantities of hydrogen
by micro-organisms has been the eventual stoppage of hydrogen
production generally coinciding with the appearance of methane.
This occurs when methanogenic microorganisms invades the bioreactor
environment converting hydrogen to methane. This process occurs
naturally in anaerobic environments such as marshes, swamps, and
pond sediments. As the appearance of methanogens in a biological
system has previously been largely inevitable, continuous
production of hydrogen from hydrogen producing micro-organisms has
been unsuccessful in the past.
[0006] Microbiologists have for many years known of organisms which
generate hydrogen as a metabolic by-product. Two reviews of this
body of knowledge are Kosaric and Lyng (1988) and Nandi and
Sengupta (1998). Among the various organisms mentioned, the
heterotrophic facultative anaerobes are of interest in this study,
particularly those in the group known as the enteric
microorganisms. Within this group are the mixed-acid fermenters,
whose most well known member is Escherichia coli. While fermenting
glucose, these micro-organisms split the glucose molecule forming
two moles of pyruvate (Equation 1); an acetyl group is stripped
from each pyruvate fragment leaving formic acid (Equation 2), which
is then cleaved into equal amounts of carbon dioxide and hydrogen
as shown in simplified form below Equation 3). Glucose.fwdarw.2
Pyruvate (1) 2 Pyruvate+2 Coenzyme A.fwdarw.2 Acetyl-CoA+2 HCOOH
(2) 2 HCOOH.fwdarw.2H.sub.2+2 CO.sub.2 (3)
[0007] Thus, during this process, one mole of glucose produces two
moles of hydrogen gas. Also produced during the process are acetic
and lactic acids, and minor amounts of succinic acid and ethanol.
Other enteric microorganisms (the 2, 3 butanediol fermenters) use a
different enzyme pathway which causes additional CO.sub.2
generation resulting in a 6:1 ratio of carbon dioxide to hydrogen
production (Madigan et al., 1997). After this process, the hydrogen
is typically converted into methane by methanogens.
[0008] There are many sources of waste organic matter which could
serve as a substrate for this microbial process. One such material
would be organic-rich industrial wastewaters, particularly
sugar-rich waters, such as fruit and vegetable processing wastes.
Other sources include agricultural residues and other organic waste
such as sewage and manures.
[0009] Electrolysis is generally a chemical process in which
chemically bonded elements are separated by passing an electrical
current through them. An important application of electrolysis is
in the separation of water into hydrogen and oxygen by the equation
2H.sub.2O.fwdarw.2H.sub.2+O.sub.2. This reaction can occur on a
highly simplified level, for example, by running two leads from a
typical battery into water held in a cup. In this instance, as
electricity is passed from one lead to another, preferably with the
aid of a water soluble electrolyte, hydrogen and oxygen bubbles can
be seen bubbling up from the water.
[0010] In more industrial applications, electrolysis can create
hydrogen on a larger scale in an electrolyzer. While an
electrolyzer is functional at room temperature, doing so at an
efficient level requires a high level of electrical energy. High
temperature electrolyzers are more efficient than traditional
room-temperature electrolyzers because some of the energy is
supplied as heat, which is cheaper than electricity, and because
the electrolysis reaction is more efficient at higher temperatures.
Indeed, at 2500.degree. C., electrical input is unnecessary because
water breaks down to hydrogen and oxygen through thermolysis. As
such temperatures are impractical, however; high temperature
electrolyzers operate at about 100 to 1000.degree. C. At higher
temperature operating rates, lower levels of energy are
required.
[0011] Typical high temperature electrolyzers convey steam or
super-heated water into an electrolytic cell having an anode and a
cathode. This may occur in combination with hydrogen, for example,
at about a 50-50 ratio of steam to hydrogen. The steam or water is
split within the cell such that oxygen moves toward the anode and
hydrogen moves toward the cathode. Remaining steam (if used), prior
existing hydrogen and produced hydrogen exit the cell together,
wherein hydrogen which can be separated from the steam by a
condenser or other like apparatus. In either case, there is never a
100% efficient conversion of the water or steam to hydrogen,
resulting in left over heated steam, water and/or oxygen.
[0012] In other industrial applications, hydrogen is produced
through other reactions that occur at increased temperature levels.
Usually in these instances, for economic production, high
temperatures are required to ensure rapid throughput and high
conversion efficiencies. (Transport and the Hydrogen Economy, UIC
Nuclear Issues Briefing Paper # 73, October 2005) For example, in
an sulfur-iodine system, sulfuric acid is heated under high
temperature (800-1000.degree. C.) and low pressure. The sulfuric
acid breaks sown into water, oxygen and sulfur oxide, which combine
with iodine to form 2HI and sulfuric acid. The 2HI reacts with
water and sulfur dioxide to under temperatures of about 350.degree.
C. to produce hydrogen and sulfur dioxide. The net result of the
equation is the same as electrolysis:
2H.sub.2O.fwdarw.2H.sub.2+O.sub.2. However, as not all compounds
are converted, this process also results in heat or excess heat in
the form of several solutions or gasses of elevated temperatures at
elevated temperatures.
[0013] New apparatuses for hydrogen generation are therefore needed
that produce substantial and useful levels of hydrogen in an
inexpensive, environmentally sound apparatus that additionally
dually combine differing hydrogen production apparatuses.
SUMMARY OF THE INVENTION
[0014] Therefore, it is an object of the present invention to
create an apparatus of dual hydrogen production wherein hydrogen is
produced in a primary system with hydrogen producing microorganisms
by utilizing heat or heat waste from a secondary hydrogen
production apparatus such as electrolysis to deactivate or kill
methanogens that would otherwise metabolize the produced
hydrogen.
[0015] It is a further object of the invention to provide an
apparatus for dually producing hydrogen An apparatus for dually
producing hydrogen, comprising: a secondary hydrogen production
apparatus including an apparatus that breaks down chemical
compounds, wherein hydrogen is produced from one or a series of
reactions using heated liquids, vapors or gases, a primary hydrogen
production apparatus operably combined with the secondary hydrogen
production apparatus, the primary hydrogen production apparatus
including a bioreactor adapted to produce hydrogen from
microorganisms metabolizing an organic feed material, and a heat
exchanger operably associated with the primary and secondary
hydrogen production apparatuses such that heat from the secondary
hydrogen production apparatus is transferred to the primary
hydrogen production apparatus.
[0016] It is a further object of the invention to provide an
apparatus wherein a bioreactor is readily combinable and proximate
with secondary hydrogen production apparatus of varying types, the
bioreactor utilizing heat or heat waste from the secondary hydrogen
production apparatus with a heat exchanger bridge, wherein the
hydrogen is not substantially converted to methane subsequent to
production.
[0017] It is a further object of the invention to heat the organic
feed material prior to entry into the bioreactor, wherein heating
is achieved in any one or a multiplicity of upstream containers or
passages, such that heating the organic feed material at
temperatures of about 60 to 100.degree. C. kills or deactivates
methanogens while leaving hydrogen producing microorganisms
substantially intact.
[0018] These and other objects of the present invention will become
more readily apparent from the following detailed description and
appended claims.
BRIEF DESCRIPTION OF DRAWINGS
[0019] FIG. 1 is a plan view of a primary hydrogen production
apparatus proximate the secondary hydrogen production
apparatus.
[0020] FIG. 2 is a side view of one embodiment of the
bioreactor.
[0021] FIG. 3 is a plan view the bioreactor.
[0022] FIG. 4 is a plan view of a secondary hydrogen production
apparatus proximate the primary hydrogen production apparatus.
[0023] FIG. 5 is a plan view of a high temperature secondary
hydrogen production apparatus proximate the primary hydrogen
production apparatus.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0024] As used herein, the term "microorganisms" include bacteria
and substantially microscopic cellular organisms.
[0025] As used herein, the term "hydrogen producing microorganisms"
includes microorganisms that metabolize an organic substrate in one
or a series of reactions that ultimately form hydrogen as one of
the end products.
[0026] As used herein, the term "methanogens" refers to
microorganisms that metabolize hydrogen in one or a series of
reactions that produce methane as one of the end products.
[0027] As used herein, the term "primary hydrogen production
apparatus" refers to a hydrogen producing process from hydrogen
producing microorganisms in a bioreactor and related preparatory
steps.
[0028] As used herein, the term "secondary hydrogen production
apparatus" refers to a hydrogen producing process other than a
bioreactor hydrogen producing process wherein heat waste resultant
from the dual hydrogen producing process is used in the primary
hydrogen production apparatus.
[0029] As used herein, the term "heat waste" refers to heat that is
produced by dual hydrogen producing process that is otherwise not
recycled into the dual hydrogen producing process such as excess
heat or aqueous or gaseous compounds that have elevated
temperatures, wherein some of the heat is diverted into another
hydrogen producing process.
[0030] A dual hydrogen producing apparatus 100 in accordance with
the present invention is shown in FIG. 1, wherein primary hydrogen
production apparatus 96 is shown in detail. As shown in FIG. 1,
primary hydrogen production apparatus 96 includes bioreactor 10,
heat exchanger 12, optional equalization tank 14 and reservoir 16.
Apparatus 100 further includes secondary hydrogen production
apparatus 50, and passage 44 bridging primary hydrogen production
apparatus 96 and secondary hydrogen production apparatus 50.
Apparatus 100 produces gas in bioreactor 10, wherein the produced
gas contains hydrogen and does not substantially include any
methane. The hydrogen containing gas is produced by the metabolism
of an organic feed material by hydrogen producing
microorganisms.
[0031] In preferred embodiments, organic feed material is a sugar
containing organic feed material. In further preferred embodiments,
the organic feed material is industrial wastewater or effluent
product that is produced during routine formation of fruit and/or
vegetable juices, such as grape juice. In additional embodiments,
wastewaters rich not only in sugars but also in protein and fats
could be used, such as milk product wastes. The most complex
potential source of energy for this process would be sewage-related
wastes, such as municipal sewage sludge and animal manures.
However, any feed containing organic material is usable in hydrogen
production apparatus 100. Hydrogen producing microorganisms can
metabolize the sugars in the organic feed material under the
reactions: Glucose.fwdarw.2 Pyruvate (1) 2 Pyruvate+2 Coenzyme
A.fwdarw.2 Acetyl-CoA+2 HCOOH (2) 2 HCOOH.fwdarw.2H.sub.2+2
CO.sub.2 (3)
[0032] During this process, one mole of glucose produces two moles
of hydrogen gas and carbon dioxide. In alternate embodiments, other
organic feed materials include agricultural residues and other
organic wastes such as sewage and manures. Typical hydrogen
producing microorganisms are adept at metabolizing the high sugar
organic waste into bacterial waste products. The wastewater may be
further treated by aerating, diluting the solution with water or
other dilutants, adding compounds that can control the pH of the
solution or other treatment step. For example, the solution may be
supplemented with phosphorus (NaH.sub.2PO.sub.4) or yeast
extract.
[0033] Organic feed material provides a plentiful feeding ground
for hydrogen producing microorganisms and is naturally infested
with these microorganisms. While hydrogen producing microorganisms
typically occur naturally in an organic feed material, the organic
feed material is preferably further inoculated with hydrogen
producing microorganisms in an inoculation step. The inoculation
may be an initial, one-time addition to bioreactor 10 at the
beginning of the hydrogen production process. Further inoculations,
however, may be added as desired. The added hydrogen producing
microorganisms may include the same types of microorganisms that
occur naturally in the organic feed material. In preferred
embodiments, the hydrogen producing microorganisms, whether
occurring naturally or added in an inoculation step, are preferably
microorganisms that thrive in pH levels of about 3.5 to 6.0 and can
survive in temperature of 60-100.degree. F. or, more preferably,
60-75.degree.. These hydrogen producing microorganisms include, but
are not limited to, Clostridium sporogenes, Bacillus licheniformis
and Kleibsiella oxytoca. Hydrogen producing microorganisms can be
obtained from a microorganismal culture lab or like source. Other
hydrogen producing microorganisms or microorganisms known in the
art, however, can be used within the spirit of the invention. The
inoculation step can occur in bioreactor 10 or elsewhere in the
apparatus, for example, recirculation system 58.
[0034] Reservoir 16 is a container known in the art that can
contain an organic feed material. The size, shape, and material of
reservoir 16 can vary widely within the spirit of the invention. In
one embodiment, reservoir 16 is one or a multiplicity of storage
tanks that are adaptable to receive, hold and store the organic
feed material when not in use, wherein the one or a multiplicity of
storage tanks may be mobile. In preferred embodiments, reservoir 16
is a wastewater well that is adaptable to receive and contain
wastewater and/or effluent from an industrial facility 50. In
further preferred embodiments, reservoir 16 is adaptable to receive
and contain wastewater that is effluent from a juice manufacturing
industrial facility 50, such that the effluent held in the
reservoir is a sugar rich juice sludge.
[0035] Organic feed material contained in reservoir 16 can be
removed through passage 22 with pump 28. Pump 28 is in operable
relation to reservoir 16 such that it aids removal movement of
organic feed material 16 into passage 22 at a desired, adjustable
flow rate, wherein pump 28 can be any pump known in the art
suitable for pumping liquids. In a preferred embodiment, pump 28 is
a submersible sump pump. Reservoir 16 may further include a low pH
cutoff device 52, such that exiting movement into passage 22 of the
organic feed material is ceased if the pH of the organic feed
material is outside of a desired range. The pH cutoff device 52 is
a device known in the art operably related to reservoir 16 and pump
28. If the monitor detects a pH of a solution in reservoir 16 out
of range, the device ceases operation of pump 28. The pH cut off in
reservoir 16 is typically greater than the preferred pH of
bioreactor 10. In preferred embodiments, the pH cutoff 52 is set
between about 7 and 8 pH. In alternate embodiments, particularly
when reservoir 16 is not adapted to receive effluent from an
industrial facility 50, the pH cutoff device is not used.
[0036] Passage 22 provides further entry access into equalization
tank 14 or heat exchanger 12. Equalization tank is an optional
intermediary container for holding organic feed material between
reservoir 16 and heat exchanger 12. Equalization tank 14 provides
an intermediary container that can help control the flow rates of
organic feed material into heat exchanger 12 by providing a slower
flow rate into passage 20 than the flow rate of organic feed
material into the equalization tank through passage 22. The
equalization tank can be formed of an), material suitable for
holding and treating the organic feed material. In the present
invention, equalization tank 14 is constructed of high density
polyethylene materials. Other materials include, but are not
limited to, metals or acrylics. Additionally, the size and shape of
equalization tank 14 can vary widely within the spirit of the
invention depending on throughput and output and location
limitations. In preferred embodiments, equalization tank 14 further
includes a low level cut-off point device 56. The low-level cut-off
point device ceases operation of pump 26 if organic feed material
contained in equalization tank 14 falls below a predetermined
level. This prevents air from entering passage 20. Organic feed
material can be removed through passage 20 or through passage 24.
Passage 20 provides removal access from equalization tank 14 and
entry access into heat exchanger 12. Passage 24 provides removal
access from equalization tank 14 of solution back to reservoir 16.
Passage 24 provides a removal system for excess organic feed
material that exceeds the cut-off point of equalization tank 14.
Both passage 20 and passage 24 may further be operably related to
pumps to facilitate movement of the organic feed material. In
alternate embodiments, equalization tank 14 is not used and organic
feed material moves directly from reservoir 16 to heat exchanger
12. In these embodiments, passages connecting reservoir 16 and heat
exchanger 12 are arranged accordingly.
[0037] The organic feed material is heated prior to conveyance into
the bioreactor. The heating can occur anywhere upstream. In one
embodiment, the heating is achieved in one or a multiplicity of
heat exchangers 12, wherein the organic feed material is heated
within the heat exchanger 12 by liquids or gasses of elevated
temperatures from secondary hydrogen production apparatus 50
conveyed through passage 44. Passage 44 may further be associated
with a pump device to control flow rates. After exiting heat
exchanger 12, gases or liquids originally conveyed through passage
44 may be discarded through an effluent pipe (not pictured) or
recycled back into the secondary hydrogen production apparatus.
Organic feed solution can be additionally heated at additional or
alternate locations in the hydrogen production apparatus. Passage
20 provides entry access to heat exchanger 12, wherein heat
exchanger 12 is any apparatus known in the art that can contain and
heat contents held within it. Passage 20 is preferably operably
related to pump 26. Pump 26 aids the conveyance of solution from
equalization tank 14 or reservoir 16 into heat exchanger 12 through
passage 20, wherein pump 26 is any pump known in the art suitable
for this purpose. In preferred embodiments, pump 26 is an air
driven pump for ideal safety reasons. However, motorized pumps are
also found to be safe and are likewise usable.
[0038] To allow hydrogen producing microorganisms within the
bioreactor 10 to metabolize the organic feed material and produce
hydrogen without subsequent conversion of the hydrogen to methane
by methanogens, methanogens contained within the organic feed
material are substantially killed or deactivated. In preferred
embodiments, the methanogens are substantially killed or
deactivated prior to entry into the bioreactor. In further
preferred embodiments, methanogens contained within the organic
feed material are substantially killed or deactivated by being
heated under elevated temperatures in heat exchanger 12.
Methanogens are substantially killed or deactivated by elevated
temperatures. Methanogens are generally deactivated when heated to
temperatures of about 60-75.degree. C. for a period of at least 15
minutes. Additionally, methanogens are generally damaged or killed
when heated to temperatures above about 90.degree. C. for a period
of at least 15 minutes. Heat exchanger 12 enables heating of the
organic feed material to temperature of about 60-100.degree. C. in
order to substantially deactivate or kill the methanogens while
leaving any hydrogen producing microorganisms substantially
functional. This effectively pasteurizes or sterilizes the contents
of the organic feed material from active methanogens while leaving
the hydrogen producing microorganisms intact, thus allowing the
produced biogas to include hydrogen without subsequent conversion
to methane. The size, shape and numbers of heat exchangers 12 can
vary widely within the spirit of the invention depending on
throughput and output required and location limitations. In
preferred embodiments, retention time in heat exchanger 12 is at
least 20 minutes. Retention time marks the average time any
particular part of organic feed material is retained in heat
exchanger 12.
[0039] At least one temperature sensor 48 monitors a temperature
indicative of the organic feed material temperature, preferably the
temperature levels of equalization tank 14 and/or heat exchanger
12. In preferred embodiments, an electronic controller is provided
having at least one microprocessor adapted to process signals from
one or a plurality of devices providing organic feed material
parameter information, wherein the electronic controller is
operably related to the at least one actuatable terminal and is
arranged to control the operation of and to controllably heat the
heat exchanger 12 and/or any contents therein. The electronic
controller is located or coupled to heat exchanger 12 or
equalization tank 14, or can alternatively be at a third or remote
location. In alternate embodiments, the controller for controlling
the temperature of heat exchanger 12 is not operably related to
temperature sensor 48.
[0040] Passage 18 connects heat exchanger 12 with bioreactor 10.
Organic feed material is conveyed into the bioreactor through
transport passage 18 at a desired flow rate. System 100 is a
continuous flow system with organic feed material in constant
motion between containers such as reservoir 16, heat exchanger 12,
bioreactor 10, equalization tank 14 if applicable, and so forth.
Flow rates between the container can vary depending on retention
time desired in any particular container. For example, in preferred
embodiments, retention time in bioreactor 10 is between about 6 and
12 hours. To meet this retention time, the flow rate of passage 18
and effluent passage 36 are adjustable as known in the art so that
organic feed material, on average, stays in bioreactor 10 for this
period of time.
[0041] The organic feed material is conveyed through passage 18
having a first and second end, wherein passage 18 provides entry
access to the bioreactor at a first end of passage 18 and providing
removal access to the heat exchanger 12 at a second end of passage
18. Any type of passage known in the art can be used, such as a
pipe or flexible tube. The transport passage may abut or extend
within the bioreactor and/or the heat exchanger 12. Passage 18 can
generally provide access to bioreactor 10 at any location along the
bioreactor. However, in preferred embodiments, passage 18 provides
access at an upper portion of bioreactor 10.
[0042] Bioreactor 10 provides an anaerobic environment conducive
for hydrogen producing microorganisms to grow, metabolize organic
feed material, and produce hydrogen. While the bioreactor is
beneficial to the growth of hydrogen producing microorganisms and
the corresponding metabolism of organic feed material by the
hydrogen producing microorganisms, it is preferably restrictive to
the proliferation of unwanted microorganisms such as methanogens,
wherein methanogens are microorganisms that metabolize carbon
dioxide and hydrogen to produce methane and water. Methanogens are
obviously unwanted as they metabolize hydrogen. If methanogens were
to exist in substantial quantities in bioreactor 10, hydrogen
produced by the hydrogen producing bacteria will subsequently be
converted to methane, reducing the percentage of hydrogen in the
produced gas.
[0043] Bioreactor 10 can be any receptacle known in the art for
holding an organic feed material. Bioreactor 10 is substantially
airtight, providing an anaerobic environment. Bioreactor 10 itself
may contain several openings. However, these openings are covered
with substantially airtight coverings or connections, such as
passage 18, thereby keeping the environment in bioreactor 10
substantially anaerobic. Generally, the receptacle will be a
limiting factor for material that can be produced. The larger the
receptacle, the more hydrogen producing bacteria containing organic
feed material, and, by extension, hydrogen, can be produced.
Therefore, the size and shape of the bioreactor can vary widely
within the sprit of the invention depending on throughput and
output and location limitations.
[0044] A preferred embodiment of a bioreactor is shown in FIG. 2.
Bioreactor 80 can be formed of any material suitable for holding an
organic feed material and that can further create an airtight,
anaerobic environment. In the present invention, bioreactor 10 is
constructed of high density polyethylene materials. Other
materials, including but not limited to metals or plastics can
similarly be used. A generally silo-shaped bioreactor 80 has about
a 300 gallon capacity with a generally conical bottom 84. Stand 82
is adapted to hold cone bottom 84 and thereby hold bioreactor 80 in
an upright position. The bioreactor 80 preferably includes one or a
multiplicity of openings that provide a passage for supplying or
removing contents from within the bioreactor. The openings may
further contain coverings known in the art that cover and uncover
the openings as desired. For example, bioreactor 80 preferably
includes a central opening covered by lid 86. In alternate
embodiments of the invention, the capacity of bioreactor 80 can be
readily scaled upward or downward depending on needs or space
limitations.
[0045] To maintain the solution volume level at a generally
constant level, the bioreactor preferably provides a system to
remove excess solution, as shown in FIGS. 1 and 3. In the present
embodiment, the bioreactor includes effluent passage 36 having an
open first and second end that provides a passage from inside
bioreactor 10 to outside the bioreactor. The first end of effluent
passage 36 may abut bioreactor 10 or extend into the interior of
bioreactor 10. If effluent passage 36 extends into the interior of
passage 10, the effluent passage preferably extends upwards to
generally upper portion of bioreactor 10. When bioreactor 10 is
filled with organic feed material, the open first end of the
effluent passage allows an excess organic feed material to be
received by effluent passage 36. Effluent passage 36 preferably
extends from bioreactor 10 into a suitable location for effluent,
such as a sewer or effluent container, wherein the excess organic
feed material will be deposited through the open second end.
[0046] Bioreactor 10 preferably contains one or a multiplicity of
substrates 90 for providing surface area for attachment and growth
of bacterial biofilms. Sizes and shapes of the one or a
multiplicity of substrates 90 can vary widely, including but not
limited to flat surfaces, pipes, rods, beads, slats, tubes, slides,
screens, honeycombs, spheres, object with latticework, or other
objects with holes bored through the surface. Numerous substrates
can be used, for example, hundreds, as needed. The more successful
the biofilm growth on the substrates, the more fixed state hydrogen
production will be achieved. The fixed nature of the hydrogen
producing microorganisms provide the sustain production of hydrogen
in the bioreactor.
[0047] Substrates 90 preferably are substantially free of interior
spaces that potentially fill with gas. In the present embodiment,
the bioreactor comprises about 100-300 pieces of 1'' plastic media
to provide surface area for attachment of the bacterial biofilm. In
one embodiment, substrates 90 are Flexiring.TM. Random Packing
(Koch-Glitsch.) Some substrates 90 may be retained below the liquid
surface by a retaining device, for example, a perforated acrylic
plate. In this embodiment, substrates 90 have buoyancy, and float
on the organic feed material. When a recirculation system is
operably, the buoyant substrates stay at the same general
horizontal level while the organic feed material circulates,
whereby providing greater access to the organic feed material by
hydrogen producing microorganism- and nonparaffinophilic
microorganism-containing biofilm growing on the substrates.
[0048] In preferred embodiments, a recirculation system 58 is
provided in operable relation to bioreactor 10. Recirculation
system 58 enables circulation of organic feed material contained
within bioreactor 10 by removing orgYanic feed material at one
location in bioreactor 10 and reintroduces the removed organic feed
material at a separate location in bioreactor 10, thereby creating
a directional flow in the bioreactor. The directional flow aids the
microorganisms within the organic feed material in finding food
sources and substrates on which to grown biofilms. As could be
readily understood, removing organic feed material from a lower
region of bioreactor 10 and reintroducing it at an upper region of
bioreactor 10 would create a downward flow in bioreactor 10.
Removing organic feed material from an upper region of bioreactor
10 and reintroducing it at a lower region would create an up-flow
in bioreactor 10.
[0049] In preferred embodiments, as shown in FIG. 1, recirculation
system 58 is arranged to produce an up-flow of any solution
contained in bioreactor 10. Passage 60 provides removal access at a
higher point than passage 62 provides entry access. Pump 30
facilitates movement from bioreactor 10 into passage 60, from
passage 60 into passage 62, and from passage 62 back into
bioreactor 10, creating up-flow movement in bioreactor 10. Pump 30
can be any pump known in the art for pumping organic feed material.
In preferred embodiments, pump 30 is an air driven centrifugal
pump. Other arrangements can be used, however, while maintaining
the spirit of the invention. For example, a pump could be operably
related to a single passage that extends from one located of the
bioreactor to another.
[0050] Bioreactor 10 may optionally be operably related to one or a
multiplicity of treatment apparatuses for treating organic feed
material contained within bioreactor 10 for the purpose of making
the organic feed material more conducive to proliferation of
hydrogen producing microorganisms. The one or a multiplicity of
treatment apparatuses perform operations that include, but are to
limited to, aerating the organic feed material, diluting the
organic feed material with water or other dilutant, controlling the
pH of the organic feed material, and adding additional chemical
compounds to the organic feed material. The apparatus coupled to
the bioreactor can be any apparatuses known in the art for
incorporating these treatments. For example, in one embodiment, a
dilution apparatus is a tank having a passage providing
controllable entry access of a dilutant, such as water, into
bioreactor 10. An aerating apparatus is an apparatus known in the
art that provides a flow of gas into bioreactor 10, wherein the gas
is typically air. A pH control apparatus is an apparatus known in
the art for controlling a pH of a solution. Additionally chemical
compounds added by treatment apparatuses include anti-fungal
agents, phosphorous supplements, yeast extract or hydrogen
producing microorganism inoculation. In other embodiments, the one
or a multiplicity of treatment apparatuses may be operably related
to other parts of the bioreactor system. For example, in one
example, the treatment apparatuses are operably related to
equalization tank 14 or recirculation system 58. In still other
embodiments, multiple treatment apparatus of the same type may be
located at various points in the bioreactor system to provide
treatments at desired locations.
[0051] Certain hydrogen producing bacteria proliferate in pH
conditions that are not favorable to methanogens, for example,
Kleibsiella oxytoca. Keeping organic feed material contained within
bioreactor 10 within this favorable pH range is conducive to
hydrogen production. In preferred embodiments, pH controller 34
monitors the pH level of contents contained within bioreactor 10.
In preferred embodiments, the pH of the organic feed material in
bioreactor 10 is maintained at about 3.5 to 6.0 pH, most preferably
at about 4.5 to 5.5 pH, as shown in Table 2. In further preferred
embodiments, pH controller 34 controllably monitors the pH level of
the organic feed material and adjustably controls the pH of the
solution if the solution falls out of or is in danger of falling
out of the desired range. As shown in FIG. 1, pH controller 34
monitors the pH level of contents contained in passage 62, such as
organic feed material, with pH sensor 64. As could readily be
understood, pH controller 34 can be operably related to any
additional or alternative location that potentially holds organic
feed material, for example, passage 60, passage 62 or bioreactor 10
as shown in FIG. 3.
[0052] If the pH of the organic feed material falls out of a
desired range, the pH is preferably adjusted back into the desired
range. Precise control of a pH level is necessary to provide an
environment that enables at least some hydrogen producing bacteria
to function while similarly providing an environment unfavorable to
methanogens. This enables the novel concept of allowing
microorganism reactions to create hydrogen without subsequently
being overrun by methanogens that convert the hydrogen to methane.
Control of pH of the organic feed material in the bioreactor can be
achieved by any means known in the art. In one embodiment, a pH
controller 34 monitors the pH and can add a pH control solution
from container 54 in an automated manner if the pH of the
bioreactor solution moves out of a desired range. In a preferred
embodiment, the pH monitor controls the bioreactor solution's pH
through automated addition of a sodium or potassium hydroxide
solution. One such apparatus for achieving this is an Etatron DLX
pH monitoring device. Preferred ranges of pH for the bioreactor
solution is between about 3.5 and 6.0, with a more preferred range
between about 4.0 and 5.5 pH.
[0053] The hydrogen producing reactions of hydrogen producing
bacteria metabolizing organic feed material in bioreactor 10 can
further be monitored by oxidation-reduction potential (ORP) sensor
32. ORP sensor 32 monitors redox potential of organic feed material
contained within bioreactor 10. Once ORP drops below about -200 mV,
gas production commences. Subsequently while operating in a
continuous flow mode, the ORP was typically in the range of -300 to
-450 mV.
[0054] In one embodiment, the wastewater is a grape juice solution
prepared using Welch's Concord Grape Juice.TM. diluted in tap water
at approximately 32 mL of juice per Liter. The solution uses
chlorine-free tap water or is aerated previously for 24 hours to
substantially remove chlorine. Due to the acidity of the juice, the
pH of the organic feed material is typically around 4.0. The
constitutional make-up of the grape juice solution is shown in
Table 1. TABLE-US-00001 TABLE 1 Composition of concord grape juice.
Source: Welch's Company, personal comm., 2005. Concentration (unit
indicated) Constituent Mean Range Carbohydrates.sup.1 15-18%
glucose 6.2% 5-8% fructose 5.5% 5-8% sucrose 1.8% 0.2-2.3% maltose
1.9% 0-2.2% sorbitol 0.1% 0-0.2% Organic Acids.sup.1 0.5-1.7%
Tartaric acid 0.84% 0.4-1.35% Malic acid 0.86% 0.17-1.54% Citric
acid 0.044% 0.03-0.12% Minerals.sup.1 Calcium 17-34 mg/L Iron
0.4-0.8 mg/L Magnesium 6.3-11.2 mg/L Phosphorous 21-28 mg/L
Potassium 175-260 mg/L Sodium 1-5 mg/L Copper 0.10-0.15 mg/L
Manganese 0.04-0.12 mg/L Vitamins.sup.1 Vitamin C 4 mg/L Thiamine
0.06 mg/L Riboflavin 0.04 mg/L Niacin 0.2 mg/L Vitamin A 80 I.U. pH
3.0-3.5 Total solids 18.5% .sup.1additional trace constituents in
these categories may be present.
[0055] Bioreactor 10 further preferably includes an overflow
cut-off switch 66 to turn off pump 26 if the solution exceeds or
falls below a certain level in the bioreactor.
[0056] Bioreactor 10 further includes an apparatus for capturing
the hydrogen containing gas produced by the hydrogen producing
bacteria. Capture and cleaning methods can vary widely within the
spirit of the invention. In the present embodiment, as shown in
FIG. 1, gas is removed from bioreactor 10 through passage 38,
wherein passage 38 is any passage known in the art suitable for
conveying a gaseous product. Pump 40 is operably related to passage
38 to aid the removal of gas from bioreactor 10 while maintaining a
slight negative pressure in the bioreactor. In preferred
embodiments, pump 40 is an air driven pump. The gas is conveyed to
gas scrubber 42, where hydrogen is separated from carbon dioxide.
Other apparatuses for separating hydrogen from carbon dioxide may
likewise be used. The volume of collected gas can be measured by
water displacement before and after scrubbing with concentrated
NaOH. Samples of scrubbed and dried gas may be analyzed for
hydrogen and methane by gas chromatography with a thermal
conductivity detector (TCD) and/or with a flame ionization detector
(FID). Both hydrogen and methane respond in the TCD, but the
response to methane is improved in the FID (hydrogen is not
detected by an FID, which uses hydrogen as a fuel for the
flame).
[0057] Exhaust system 70 exhausts gas. Any exhaust system known in
the art can be used. In a preferred embodiment, as shown in FIG. 1,
exhaust system includes exhaust passage 72, backflow preventing
device 74, gas flow measurement and totalizer 76, and air blower
46.
[0058] The organic feed material may be further inoculated in an
initial inoculation step with one or a multiplicity of hydrogen
producing bacteria, such as Clostridium sporogenes, Bacillus
licheniformiis and Kleibsiella oxytoca, while contained in
bioreactor 10. These hydrogen producing bacteria are obtained from
a bacterial culture lab or like source. Alternatively, the hydrogen
producing bacteria that occur naturally in the waste solution can
be used without inoculating the solution. In further alternative
embodiments, additional inoculations can occur in bioreactor 10 or
other locations of the apparatus, for example, heat exchanger 12,
equalization tank 14 and reservoir 16.
[0059] In the present embodiment, the preferred hydrogen producing
bacteria is Kleibsiella oxytoca, a facultative enteric bacterium
capable of hydrogen generation. Kleibsiella oxytoca produces a
substantially 1:1 ratio of hydrogen to carbon dioxide through
organic feed material metabolization, not including impurities. The
source of both the Kleibsiella ocytoca may be obtained from a
source such yeast extract. In one embodiment, the continuous input
of seed organisms from the yeast extract in the waste solution
results in a culture of Kleibsiella oxytoca in the bioreactor
solution. Alternatively, the bioreactor may be directly inoculated
with Kleibsiella oxyfoca. In one embodiment, the inoculum for the
bioreactor is a 48 h culture in nutrient broth added to diluted
grape juice and the bioreactor was operated in batch mode until gas
production commenced.
[0060] The heating source preferably is heat exchanger 14 that uses
heat or heat waste from dual hydrogen producing apparatus 16 to
heat the organic feed material, wherein passage 44 is a bridge
between the primary and secondary hydrogen production apparatus.
Any heat exchanger known in the art designed for efficient heat
transfer can be used in the apparatus including but not limited to
parallel flow, counter flow, cross flow, shell and tube, plate,
regenerative, adiabatic wheel, boiler and steam generator heat
exchangers. Heat exchangers that heat a fluid separated from the
heat source by a solid wall are preferred.
[0061] The method preferably includes at least one temperature
sensor for sensing a temperature indicative of the organic feed
material temperature. In preferred embodiments, an electronic
controller is provided having at least one microprocessor adapted
to process signals from one or a plurality of devices providing
organic feed material parameter information, wherein the electronic
controller is connected to the at least one actuatable terminal and
is arranged to control the operation of and to controllably heat
the heat exchanger 12 and/or any contents therein. The electronic
controller operable related to heat exchanger 14 or heat exchanger
12 and may be located or coupled to those locations or be at a
third or remote location.
[0062] A heating source for system 100 preferably is heat exchanger
12 that uses heat or heat waste from industrial facility 50 to heat
the organic feed material, wherein the heat exchanger is a heat
exchanger known in the art. The heat exchanger can be a liquid
phase-liquid phase or gas-phase/liquid phase as dictated by the
phase of the heat waste. A typical heat exchanger, for example, is
a shell and tube heat exchanger which consists of a series of
finned tubes, through which a first fluid runs. A second fluid runs
over the finned tubes to be heated or cooled. Another type of heat
exchanger is a plate heat exhanger, which directs flow through
baffles so that fluids to be ehated and cooled are separated by
plates with very large surface area.
[0063] Heat is captured from secondary hydrogen production
apparatus 50 and is used to partially or fully heat the organic
feed material to the temperatures of about 60 to 100.degree. C. The
secondary hydrogen production apparatus can include any hydrogen
producing apparatus wherein that includes heat. In preferred
embodiments, the secondary hydrogen production apparatus is an
apparatus that produces hydrogen with by separating H.sub.2O into
hydrogen or water in one or a series of reactions. In further
preferred embodiments, the secondary hydrogen production apparatus
is an electrolyzer or a sulfur-iodine system. In one embodiment, a
steam based high temperature electrolyzer is combined with the
primary hydrogen production apparatus 96 of the invention as shown
in FIG. 4. Electrolyzer 114 includes cell 102 having a cathode 104
and an anode 106, wherein applied electrical current 112 is applied
to the cell. The cell may further include a membrane 108 as needed.
Steam and hydrogen stream 110 is conveyed into cell 102, wherein
the steam is heated at a temperature from about 100-1000.degree. C.
The amount of energy needed as a function of temperature is
generally known in the art, as shown in Table 4. The thermal and
electro forces will cause a portion of the water or steam to split,
wherein oxygen will pass through ion conducting membrane 108 to the
anode side and is removed on that side. A mixture of steam and
hydrogen, including hydrogen newly formed from separation of the
water, exits the cell on the cathode side with heated temperatures.
The hydrogen can then be removed from the steam with a condenser.
The condenser can function as heat exchanger 12 or can be a
separate condenser that functions in tandem with heat exchanger 12.
Either way, the heat exchanger 12 obtains heat from the steam that
exits cell 102 and uses the heat to dually produce hydrogen in the
primary hydrogen production apparatus by elevate the temperature of
organic feed material to about 60 to 100.degree. C.
[0064] Alternatively, secondary hydrogen production apparatus is a
high temperature electrolyzer that uses heated water, as in FIG. 5.
Here, an electrical current is applied to cathode 116 and anode 118
under heated temperatures of about 100-1000.degree. C., separating
a portion of the heated water into oxygen and hydrogen. The oxygen
migrates to the anode side across diaphragm 120, while hydrogen
migrates to the cathode side. Heat exchanger 12 can obtain heat
from the heated water remaining the electrolyzer or by the
released, heated oxygen.
[0065] In further embodiments, the secondary hydrogen production
apparatus is a sulfur-iodide system. In an sulfur-iodine system,
sulfuric acid is heated under high temperatures of about
750-1000.degree. C. and low pressure under the reaction
H.sub.2SO.sub.4.fwdarw.H.sub.2O+SO.sub.2+1/2O.sub.2. In certain
embodiments, iodine can combine with the resultant sulfur dioxide
and water under conditions known in the art under the reaction
I.sub.2+SO.sub.2+2H.sub.2O.fwdarw.2HI+H.sub.2SO.sub.4. The 2HI
reacts with water and sulfur dioxide to under temperatures of about
350.degree. C. to produce hydrogen and sulfur dioxide under the
reaction 2HI.fwdarw.H.sub.2+I.sub.2. The net result of the process
is the same as electrolysis: 2H.sub.2O.fwdarw.2H.sub.2+O.sub.2.
None of the reactions occur with 100 percent efficiency, resulting
in super-heated byproducts for heat exchanger 44 to remove heat
from in order to heat organic solution in primary hydrogen
production apparatus 96. Heat exchanger 14 can use heat from any
heat source from this process, for example, the heated
H.sub.2SO.sub.4, heated H.sub.2O or oxygen. Regardless of where
heat exchanger 44 acquires heat, the dual method enables two
separate methods of hydrogen production, wherein the primary system
uses heat energy from the secondary system in order to treat
organic feed material for use in bioreactor 10.
EXAMPLE 1
[0066] The apparatus combines a bioreactor with a high temperature
electrolyzer. The organic feed material is a grape juice waste
product diluted in tap water at approximately 32 mL of juice per
liter. The solution uses chlorine-free tap water or is aerated
previously for 24 hours to substantially remove chlorine. The
dilution and aeration occur in a treatment container. The organic
feed material is then conveyed into the heat exchanger 12 through a
passage.
[0067] The organic feed material is heated in the heat exchanger 12
to about 65.degree. C. for about 10 minutes to substantially
deactivate methanogens. The organic feed material is heated with
excess heat from the high temperature electrolyzer with a heat
exchanger. The organic feed material is conveyed through a passage
to the bioreactor wherein it is further inoculated with Kleibsiella
oxytoca. The resultant biogases produced by the microorganisms
metabolizing the organic feed material include hydrogen without any
substantial methane.
EXAMPLE 2
[0068] A multiplicity of reactors were initially operated at pH 4.0
and a flow rate of 2.5 mL min.sup.-1, resulting in a hydraulic
retention time (HRT) of about 13 h (0.55 d). This is equivalent to
a dilution rate of 1.8 d.sup.-1. After one week all six reactors
were at pH 4.0, the ORP ranged from -300 to -450 mV, total gas
production averaged 1.6 L d.sup.-1 and hydrogen production averaged
0.8 L d.sup.-1. The mean COD of the organic feed material during
this period was 4,000 mg L.sup.-1 and the mean effluent COD was
2,800 mg L.sup.-1, for a reduction of 30%. After one week, the pHs
of certain reactors were increased by one half unit per day until
the six reactors were established at different pH levels ranging
from 4.0 to 6.5. Over the next three weeks at the new pH settings,
samples were collected and analyzed each weekday. It was found that
the optimum for gas production in this embodiment was pH 5.0 at
1.48 L hydrogen d.sup.-1 (Table 2). This was equivalent to about
0.75 volumetric units of hydrogen per unit of reactor volume per
day. TABLE-US-00002 TABLE 2 Production of hydrogen in 2-L anaerobic
bioreactors as a function of pH. Total H2 H2 per gas H2 L/g Sugar
pH L/day L/day COD moles/mole 4.0.sup.a 1.61 0.82 0.23 1.81
4.5.sup.b 2.58 1.34 0.23 1.81 5.0.sup.c 2.74 1.48 0.26 2.05
5.5.sup.d 1.66 0.92 0.24 1.89 6.0.sup.d 2.23 1.43 0.19 1.50
6.5.sup.e 0.52 0.31 0.04 0.32 .sup.amean of 20 data points
.sup.bmean of 14 data points .sup.cmean of 11 data points
.sup.dmean of 7 data points .sup.emean of 6 data points
[0069] Also shown in Table 2 is the hydrogen production rate per g
of COD, which also peaked at pH 5.0 at a value of 0.26 L g.sup.-1
COD consumed. To determine the molar production rate, it was
assumed that each liter of hydrogen gas contained 0.041 moles,
based on the ideal gas law and a temperature of 25.degree. C. Since
most of the nutrient value in the grape juice was simple sugars,
predominantly glucose and fructose (Table 1 above), it was assumed
that the decrease in COD was due to the metabolism of glucose.
Based on the theoretical oxygen demand of glucose (1 mole glucose
to 6 moles oxygen), one gram of COD is equivalent to 0.9375 g of
glucose. Therefore, using those conversions, the molar H.sub.2
production rate as a function of pH ranged from 0.32 to 2.05 moles
of H.sub.2 per mole of glucose consumed. As described above, the
pathway appropriate to these organisms results in two moles of
H.sub.2 per mole of glucose, which was achieved at pH 5.0. The
complete data set is provided in Tables 3a and 3b.
[0070] Samples of biogas were analyzed several times per week from
the beginning of the study, initially using a Perkin Elmer
Autosystem GC with TCD, and then later with a Perkin Elmer Clarus
500 GC with TCD in series with an FID. Methane was never detected
with the TCD, but trace amounts were detected with the FID (as much
as about 0.05%).
[0071] Over a ten-day period, the waste solution was mixed with
sludge obtained from a methane-producing anaerobic digester at a
nearby wastewater treatment plant at a rate of 30 mL of sludge per
20 L of diluted grape juice. There was no observed increase in the
concentration of methane during this period. Therefore, it was
concluded that the preheating of the feed to 65.degree. C. as
described previously was effective in deactivating the organisms
contained in the sludge. Hydrogen gas production rate was not
affected (data not shown).
[0072] Using this example, hydrogen gas is generated using a
microbial culture over a sustained period of time. The optimal pH
for this culture consuming simple sugars from a simulated fruit
juice bottling wastewater was found to be 5.0. Under these
conditions, using plastic packing material to retain microbial
biomass, a hydraulic residence time of about 0.5 days resulted in
the generation of about 0.75 volumetric units of hydrogen gas per
unit volume of reactor per day.
[0073] Whereas particular embodiments of this invention have been
described above for purposes of illustration, it will be evident to
those skilled in the art that numerous variations of the details of
the present invention may be made without departing from the
invention as defined in the appended claims. TABLE-US-00003 TABLE
3a Bioreactor Operating Data GAS Total after Liquid Readings
collection volume scrubbing Effluent NaOH Net Feed Date Reactor
hours (mL) (mL) (mL) (mL) (mL) ORP pH 14-Nov A 5 540 220 780 0 780
-408 4.0 14-Nov B 5 380 220 840 0 840 -413 4.1 14-Nov C 5 350 170
870 0 870 -318 4.1 14-Nov D 5 320 130 920 0 920 -372 4.1 14-Nov E 5
240 100 920 0 920 -324 4.3 14-Nov F 5 50 25 810 0 810 -329 4.0
15-Nov A 5.5 450 230 1120 25 1095 -400 4.0 15-Nov B 5.5 450 235
1180 35 1145 -384 4.0 15-Nov C 5.5 250 130 640 0 640 -278 4.0
15-Nov E 5.5 455 225 1160 0 1160 -435 4.0 15-Nov F 5.5 430 235 1160
0 1160 -312 4.0 16-Nov A 5 380 190 1020 27 993 -414 4.0 5-Dec A 4.5
200 110 500 35 465 -439 4.0 18-Nov A 5 360 190 200 0 200 -423 4.0
21-Nov A 4 320 170 800 40 760 -429 4.0 22-Nov A 3.75 285 190 725 21
704 -432 4.0 29-Nov A 4.25 310 155 750 24 726 -439 4.0 2-Dec A 3.75
250 120 660 26 634 -438 4.0 6-Dec A 3 150 75 540 0 540 -441 4.0
17-Nov A 5.5 300 160 1010 30 980 -414 4.0 averages 4.81 324 164 830
13 817 -392 4.0 16-Nov B 5 400 200 1125 45 1080 -397 4.5 16-Nov D 5
400 165 960 60 900 -360 4.5 16-Nov E 5 490 240 1100 72 1028 -324
4.5 1-Dec B 3.5 500 260 570 45 525 -415 4.5 6-Dec B 3 470 240 650
40 610 -411 4.5 21-Nov B 4 560 300 930 50 880 -397 4.5 2-Dec B 3.75
640 320 830 50 780 -407 4.5 17-Nov B 5.5 450 220 1165 50 1115 -406
4.5 18-Nov B 5 390 220 860 42 818 -406 4.5 22-Nov B 3.75 585 395
835 50 785 -397 4.5 29-Nov B 4.25 620 320 920 42 878 -410 4.5 5-Dec
B 4.5 390 190 750 37 713 -417 4.5 16-Nov F 5 400 200 1082 93 989
-324 4.5 16-Nov C 5 400 200 950 74 876 -325 4.6 averages 4.45 478
248 909 54 856 -385 4.5 COD Performance Feed Effluent Removal
Loading Consumed Total gas H2 H2 Date (mg/L) (mg/L) (mg/L) (g) (g)
L/day L/day L/g COD 14-Nov 4,480 2,293 2,187 3.494 1.706 2.59 1.06
0.13 14-Nov 4,480 2,453 2,027 3.763 1.702 1.82 1.06 0.13 14-Nov
4,480 2,293 2,187 3.898 1.902 1.68 0.82 0.09 14-Nov 4,480 1,920
2,560 4.122 2.355 1.54 0.62 0.06 14-Nov 4,480 2,773 1,707 4.122
1.570 1.15 0.48 0.06 14-Nov 3,307 2,080 1,227 2.679 0.994 0.24 0.12
0.03 15-Nov 3,307 3,787 (480) 3.621 -0.525 1.96 1.00 -0.44 15-Nov
3,307 3,253 54 3.787 0.061 1.96 1.03 3.82 15-Nov 3,307 3,520 (213)
2.116 -0.138 1.09 0.57 -0.95 15-Nov 3,307 3,467 (160) 3.836 -0.165
1.99 0.98 -1.21 15-Nov 3,307 3,413 (106) 3.836 -0.123 1.88 1.03
-1.91 16-Nov 4,693 3,627 1,066 4.660 1.059 1.82 0.91 0.18 5-Dec
4,267 4,160 107 1.984 0.050 1.07 0.59 2.21 18-Nov 3,680 5,227
(1,547) 0.736 -0.309 1.73 0.91 -0.61 21-Nov 3,493 3,680 (187) 2.655
-0.142 1.92 1.02 -1.20 22-Nov 4,107 2,293 1,813 2.891 1.277 1.82
1.22 0.15 29-Nov 5,013 3,520 1,493 3.640 1.084 1.75 0.88 0.14 2-Dec
4,587 3,893 694 2.908 0.440 1.60 0.77 0.27 6-Dec 4,853 3,093 1,760
2.621 0.950 1.20 0.60 0.08 17-Nov 4,907 3,520 1,387 4.809 1.359
1.31 0.70 0.12 averages 4,092 3,213 879 3.344 0.718 1.61 0.82 0.23
16-Nov 4,693 3,520 1,173 5.068 1.267 1.92 0.96 0.16 16-Nov 4,693
3,573 1,120 4.224 1.008 1.92 0.79 0.16 16-Nov 4,693 3,413 1,280
4.824 1.315 2.35 1.15 0.18 1-Dec 5,173 3,680 1,493 2.716 0.784 3.43
1.78 0.33 6-Dec 4,853 3,360 1,493 2.960 0.911 3.76 1.92 0.26 21-Nov
3,493 3,147 346 3.074 0.305 3.36 1.80 0.98 2-Dec 4,587 3,413 1,174
3.578 0.915 4.10 2.05 0.35 17-Nov 4,907 2,933 1,974 5.471 2.201
1.96 0.96 0.10 18-Nov 3,680 2,960 720 3.010 0.589 1.87 1.06 0.37
22-Nov 4,107 2,720 1,387 3.224 1.089 3.74 2.53 0.36 29-Nov 5,013
3,307 1,707 4.402 1.498 3.50 1.81 0.21 5-Dec 4,267 3,840 427 3.042
0.304 2.08 1.01 0.62 16-Nov 4,693 3,093 1,600 4.641 1.582 1.92 0.96
0.13 16-Nov 4,693 2,933 1,760 4.111 1.541 1.92 0.96 0.13 averages
4,539 3,278 1,261 3.883 1.079 2.58 1.34 0.23
[0074] TABLE-US-00004 TABLE 3b Bioreactor Operating Data Continued
GAS Total after Liquid Readings collection volume scrubbing
Effluent NaOH Net Feed Date Reactor hours (mL) (mL) (mL) (mL) (mL)
ORP pH 17-Nov C 5.5 360 200 840 120 720 -344 4.9 18-Nov C 5 370 200
1120 70 1050 -328 4.9 29-Nov C 4.25 415 200 920 50 870 -403 4.9
17-Nov E 5.5 490 270 1210 115 1095 -352 5.0 1-Dec D 3.5 540 250 710
85 625 -395 5.0 17-Nov F 5.5 475 225 1120 130 990 -367 5.0 5-Dec D
4.5 580 310 710 77 633 -423 5.0 6-Dec D 3 450 240 490 43 447 -420
5.0 17-Nov D 3.5 680 415 580 83 497 -326 5.0 2-Dec D 3.75 640 340
830 66 764 -412 5.0 22-Nov C 3.75 460 295 800 50 750 -349 5.0
averages 4.34 496 268 848 81 767 -374.5 5.0 5-Dec C 4.5 470 250 900
103 797 -429 5.4 18-Nov F 5 90 45 600 55 545 -451 5.5 21-Nov D 4
130 70 830 80 750 -454 5.5 22-Nov D 3.75 360 250 765 69 696 -461
5.5 29-Nov D 4.25 100 50 940 100 840 -456 5.5 2-Dec C 3.75 550 290
810 93 717 -430 5.5 6-Dec C 3 250 130 570 45 525 -428 5.5 averages
4.04 279 155 774 78 696 -444.1 5.5 21-Nov E 4 350 250 930 130 800
-400 6.0 22-Nov E 3.75 380 280 820 127 693 -411 6.0 29-Nov E 4.25
360 230 870 71 799 -467 6.0 1-Dec E 3.5 420 250 770 127 643 -471
6.0 2-Dec E 3.75 280 170 540 85 455 -443 6.0 5-Dec E 4.5 410 240
930 156 774 -487 6.0 6-Dec E 3 280 170 660 105 555 -490 6.0
averages 3.82 354 227 789 114 674 -453 6.0 29-Nov F 4.25 90 45 870
150 720 -501 6.5 2-Dec F 3.75 20 0 810 136 674 -497 6.5 22-Nov F
3.75 120 105 790 128 662 -477 6.5 5-Dec F 4.5 10 0 670 121 549 -532
6.5 6-Dec F 3 60 50 480 90 390 -515 6.5 21-Nov F 4 200 100 910 150
760 -472 6.5 averages 3.88 83 50 755 129 626 -499 6.5 COD
Performance Feed Effluent Removal Loading Consumed Total gas H2 H2
Date (mg/L) (mg/L) (mg/L) (g) (g) L/day L/day L/g COD 17-Nov 4,907
2,880 2,027 3.533 1.459 1.57 0.87 0.14 18-Nov 3,680 2,480 1,200
3.864 1.260 1.78 0.96 0.16 29-Nov 5,013 3,093 1,920 4.362 1.670
2.34 1.13 0.12 17-Nov 4,907 4,747 160 5.373 0.175 2.14 1.18 1.54
1-Dec 5,173 3,573 1,600 3.233 1.000 3.70 1.71 0.25 17-Nov 4,907
3,760 1,147 4.858 1.135 2.07 0.98 0.20 5-Dec 4,267 3,573 694 2.701
0.439 3.09 1.65 0.71 6-Dec 4,853 3,253 1,600 2.169 0.715 3.60 1.92
0.34 17-Nov 4,907 4,213 694 2.439 0.345 4.66 2.85 1.20 2-Dec 4,587
3,787 800 3.504 0.611 4.10 2.18 0.56 22-Nov 4,107 1,280 2,827 3.080
2.120 2.94 1.89 0.14 averages 4,664 3,331 1,333 3.579 1.023 2.74
1.48 0.26 5-Dec 4,267 3,413 854 3.401 0.680 2.51 1.33 0.37 18-Nov
3,680 3,440 240 2.006 0.131 0.43 0.22 0.34 21-Nov 3,493 3,360 133
2.620 0.100 0.78 0.42 0.70 22-Nov 4,107 2,880 1,227 2.858 0.854
2.30 1.60 0.29 29-Nov 5,013 3,307 1,707 4.211 1.434 0.56 0.28 0.03
2-Dec 4,587 3,573 1,014 3.289 0.727 3.52 1.86 0.40 6-Dec 4,853
3,627 1,226 2.548 0.644 2.00 1.04 0.20 averages 4,286 3,371 914
2.982 0.636 1.66 0.92 0.24 21-Nov 3,493 2,987 506 2.794 0.405 2.10
1.50 0.62 22-Nov 4,107 2,453 1,653 2.846 1.146 2.43 1.79 0.24
29-Nov 5,013 1,973 3,040 4.006 2.429 2.03 1.30 0.09 1-Dec 5,173
2,933 2,240 3.326 1.440 2.88 1.71 0.17 2-Dec 4,587 3,360 1,227
2.087 0.558 1.79 1.09 0.30 5-Dec 4,267 3,253 1,014 3.303 0.785 2.19
1.28 0.31 6-Dec 4,853 2,293 2,560 2.693 1.421 2.24 1.36 0.12
averages 4,499 2,750 1,749 3.033 1.179 2.23 1.43 0.19 29-Nov 5,013
1,707 3,307 3.610 2.381 0.51 0.25 0.02 2-Dec 4,587 3,573 1,014
3.092 0.683 0.13 0.00 0.00 22-Nov 4,107 2,240 1,867 2.719 1.236
0.77 0.67 0.08 5-Dec 4,267 2,827 1,440 2.343 0.791 0.05 0.00 0.00
6-Dec 4,853 2,240 2,613 1.893 1.019 0.48 0.40 0.05 21-Nov 3,493
2,613 880 2.655 0.669 1.20 0.60 0.15 averages 4,387 2,533 1,853
2.745 1.160 0.52 0.31 0.04
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References