U.S. patent application number 15/713278 was filed with the patent office on 2018-03-29 for method and apparatus for pasteurization, hydrolysis and carbonization.
The applicant listed for this patent is D.C. Water & Sewer Authority. Invention is credited to Haydee De Clippeleir, Matthew Higgins, Sudhir N. Murthy, Bernhard Wett.
Application Number | 20180086656 15/713278 |
Document ID | / |
Family ID | 61688286 |
Filed Date | 2018-03-29 |
United States Patent
Application |
20180086656 |
Kind Code |
A1 |
Murthy; Sudhir N. ; et
al. |
March 29, 2018 |
METHOD AND APPARATUS FOR PASTEURIZATION, HYDROLYSIS AND
CARBONIZATION
Abstract
This invention proposes the use of Thermal Hydrolysis (or
Thermal Carbonization) at different temperatures and pressures in
alternate waste streams to achieve an optimal mix of high digestion
rates and pasteurization rates while still achieving large
viscosity reduction. In the disclosed embodiments means of
combining Thermal Hydrolysis (or Thermal Carbonization) and
Pasteurization including but not limited to placing the waste
streams in parallel, placing them in series, utilizing heat input
in parallel and heat exchangers in series are explored to optimize
hydrolysis rates, minimize the use of high pressure tanks, optimize
energy used, and manage viscosity characteristics of the
solids.
Inventors: |
Murthy; Sudhir N.; (Herndon,
VA) ; Higgins; Matthew; (Lewisburg, PA) ; De
Clippeleir; Haydee; (Washington, DC) ; Wett;
Bernhard; (Innsbruck, AT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
D.C. Water & Sewer Authority |
Washington |
DC |
US |
|
|
Family ID: |
61688286 |
Appl. No.: |
15/713278 |
Filed: |
September 22, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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62398936 |
Sep 23, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C02F 2201/009 20130101;
Y02W 10/37 20150501; Y02W 10/30 20150501; C02F 2209/02 20130101;
C02F 2103/32 20130101; B09B 3/00 20130101; C02F 2303/10 20130101;
C02F 2209/09 20130101; C02F 11/185 20130101; Y02A 20/212 20180101;
C02F 11/10 20130101; C02F 2303/04 20130101; C02F 11/12 20130101;
C02F 11/18 20130101; C02F 11/04 20130101; C02F 2103/28 20130101;
B09B 3/0083 20130101; C02F 1/025 20130101 |
International
Class: |
C02F 11/10 20060101
C02F011/10; C02F 1/02 20060101 C02F001/02; B09B 3/00 20060101
B09B003/00 |
Claims
1. An apparatus for Hydrolysis (or Thermal Carbonization) treatment
wherein temperature of wastewater solids is increased between 60
and 220 degrees Celsius to decrease digester volume requirements,
increase throughput rates of anaerobic treatment, increase cake
solids, improve microbial hydrolysis rates, inactivate pathogens or
indicators, or decrease head loss, mixing or pumping energy, and
that reduces viscosity of the solids; a. wherein the mostly waste
activated sludge, cellulosic waste, slowly digestible organic waste
is hydrolyzed (using thermal, thermophilic aerobic, chemical,
enzyme, or electron beam) at temperatures between 60 and 180
degrees Celsius (or up to 220 degrees Celsius for thermal
carbonization) and; b. wherein the mostly primary solids, food
waste or any other organic waste or products is pasteurized at
temperatures between 60 and 100 degrees Celsius, or
2. The apparatus as described in claim 1 further comprising a
dewatering mechanism capable of dewatering the solids produced
after treatment to increase cake solids of a content of 7-55% total
dry solids prior to anaerobic digestion or composting of these
solids.
3. The apparatus described in claim 1 further comprising piping
connecting the removed liquid of the dewatering process to the
biological nutrient removal, anaerobic digestion, capable of using
it as a carbon source.
4. The apparatus described in claim 3 further comprising a
mechanism for harvesting as a sterilized product for agriculture,
fermentation feed stock, antimicrobial blends, or chelation the
removed liquid of the dewatering process.
5. The apparatus as described in claim 3 wherein the dewatering
mechanism is capable of retaining in the removed liquid of the
dewatering process any humic and fulvic substances.
6. The apparatus as described in claim 1 further comprising a
device to dewater the solids produced after additional anaerobic
digestion enough to increase cake solids to a content of 7-55%
total dry solids.
7. The apparatus as described in claim 1 further comprising a
device to dewater the solids produced before treatment to increased
cake solids of a content of 3-35% total dry solids.
8. The apparatus as described in claim 1 further comprising any
number of components to regulate a minimum temperature of 75 degree
Celsius for 20-40 minutes as required to address resuscitation and
regrowth of indicator and pathogens.
9. The apparatus as described in claim 1 further comprising devices
for decreasing the microbe to substrate proximity, microbe-microbe
proximity, or increasing diffusivity through decreased viscosity
such that the microbial hydrolysis rates are improved.
10. The apparatus as described in claim 1 further comprising
components in pasteurization to regulate temperature directly or
indirectly based on viscosity characteristics of the solids.
11. The apparatus as described in claim 7 further comprising system
of devices calculates head loss in pumps, torque in a mixer to
regulate indirect control and in-line or off-line or lab measured
viscosity may be used to regulate direct control.
12. The apparatus as described in claim 1 further comprising solid
dilution or thickening devices to control viscosity of solids.
13. The apparatus as described in claim 1 further comprising mixers
in the solid streams or heat exchangers for recovering heat from
the Thermal Hydrolysis (or Thermal Carbonization) process.
14. The apparatus as described in claim 1 further comprising a
reactor for retaining sterilized solids are bioaugmented with
specialized micro-organism to promote anaerobic digestion,
dewatering and agricultural use of solids.
15. The apparatus as described in claim 13 further comprising any
number of devices for retaining the sterilized solids long enough
for the specialized micro-organisms are used to consume hydrogen,
to increase Firmicutes over Bacteroidetes ratio or increase
anaerobic nitrogen fixation.
16. The apparatus of claim 1 wherein the production of refractory
substances during the thermal hydrolysis or carbonization processes
are managed or controlled using a sensor that controls a pump,
valve or other devices.
17. The apparatus of claim 1 wherein the production of refractory
substances during thermal hydrolysis or carbonization is minimized
through more rapid heat dissipation using better mixing, heat
transfer or heat management approaches.
18. The apparatus of claim 1, wherein the temperature can be
increases using solar energy or solar cells that directly or
indirectly heat sludge.
19. An apparatus for Hydrolysis (or Thermal Carbonization)
treatment comprising: a reactor, wherein temperature of wastewater
solids is increased between 60 and 220 degrees Celsius to decrease
digester volume requirements, increase throughput rates of
anaerobic treatment, increase cake solids, improve microbial
hydrolysis rates, inactivate pathogens or indicators, or decrease
head loss, mixing or pumping energy, and that reduces viscosity of
the solids, wherein more viscous waste streams are hydrolyzed
(using thermal, thermophilic aerobic, chemical, enzyme, or electron
beam) at temperatures between 60 and 180 degrees Celsius (or up to
220 degrees Celsius for thermal carbonization), wherein the less
viscous waste stream is hydrolyzed and/or pasteurized between 60
and 100 degrees Celsius, and wherein the heat generator can
regulate higher temperatures of 135 to 180 degrees Celsius as
reserved for the higher viscosity solids or less digestible solids;
and a dewatering mechanism, wherein the stream for the
high-temperature hydrolyses (or carbonization) process is dewatered
to a solids concentration of approximately >8, while the stream
for the pasteurization or low temperature hydrolysis process is
thickened to a solids concentration of approximately <8% in
order to manage the relative viscosities and the heat balances of
the two streams.
Description
RELATED APPLICATION
[0001] This application claims priority to U.S. provisional
application No. 62/398,936 entitled A Method and Apparatus for
Pasteurization with Thermal Hydrolysis, filed Sep. 23, 2016. The
entire disclosure of the provisional application is incorporated
herein by reference.
BACKGROUND
[0002] Thermal hydrolysis is now becoming a widely practiced
technology to improve digestion rates (usually at temperatures
greater than 100 degrees Celsius, and simultaneously pasteurize
wastewater solids (or other wastes) and to decrease the viscosity
of wastewater solids and other wastes. The combined thermal
hydrolysis and pasteurization at temperature greater than 100
degrees Celsius will henceforth be referred to as Thermal
Hydrolysis. Other forms of hydrolysis include chemical hydrolysis
(such as alkaline hydrolysis, acid hydrolysis), enzyme (natural or
manufactured) hydrolysis and electron beam (E-Beam) hydrolysis. The
individual form or combination (2 or more) of thermal, alkaline,
acid, natural or manufactured enzyme, E-beam hydrolysis is
generically henceforth called hydrolysis. Pasteurization can also
be practiced at atmospheric pressure (henceforth simply referred to
as pasteurization to differentiate from high pressure thermal
hydrolysis >100 C). While the digestion rates and pasteurization
can be increased by operating the process at lower temperatures and
at atmospheric pressure, the viscosity reduction of some types of
solids is best achieved at higher temperatures and pressures.
Thermal Carbonization is the practice of heating sludge to
temperatures (at different retention times) approximately greater
than 180.degree. C. under pressure and up to approximately
220.quadrature., henceforth referred to as Thermal Carbonization.
The scope of the invention is to develop an approach to manage and
co-mix streams of wastes by performing the thermal or hydrolysis
treatment at one, two (or more); depending on number of parallel or
series waste streams) temperatures to achieve the optimized
solution. The hydrolysis or pasteurization step can be replaced by
a thermal carbonization step. Or, alternative some of these
processes can be combined in a single step. For example,
pasteurization and chemical hydrolysis can be combined in a single
step. This way enhanced digestability and higher loading rate of
solids can be achieved while minimizing requirement of volume of
high pressure vessels and achieving overall pasteurization of all
of the solids.
SUMMARY OF THE INVENTION
[0003] In this invention we propose the use of pasteurization,
hydrolysis (inclusive of thermal hydrolysis) and/or carbonization
at a plurality of temperatures and pressures in alternate waste
streams in order to effectively achieve an optimal mix of high
digestion rates and pasteurization rates while still achieving
large viscosity reduction and high dewatered cake solids
concentrations. This may be achieved through the use of separate
waste streams feeding alternate Thermal Hydrolysis (or Thermal
Carbonization) and Pasteurization processes before co-mixing.
[0004] In some embodiments of the present disclosure waste
activated sludge and primary sludge would feed a Thermal Hydrolysis
(or Thermal Carbonization) and Pasteurization Process in parallel
while being heat treated before being mixed in an Anaerobic
digester and ultimately dewatered such that the end cake product is
separated from the residual centrate/filtrate. In other
embodiments, while the sludge would feed the treatment processes in
series, the heat input would occur in parallel in the Thermal
Hydrolysis and Pasteurization process. In some other embodiments, a
heat exchanger would connect the Thermal Hydrolysis (or Thermal
Carbonization) process to the Pasteurization process such that only
the mass of the sludge is treated in parallel by each process,
while the heat transfer occurs prior to the digester. In some such
embodiments the heat exchange connection will still exist between
Thermal Hydrolysis (or Thermal Carbonization) and Pasteurization,
however the Thermal Hydrolysis (or Thermal Carbonization) mass flow
will also be in series with Pasteurization such that neither mass
nor heat flow in parallel. In yet other embodiments optional
blending may be used in lieu of the forced anaerobic digester, such
that each parallel process can go through dewatering separately
prior to cake digestion, and centrate/filtrate separation. Finally
a mix of the aforementioned variations is envisioned in the present
disclosure.
[0005] There may further exist other reactions within the spirit of
the invention not explicitly described herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] The accompanying drawings which are incorporated in and form
a part of the specification, illustrate several embodiments of the
invention wherein:
[0007] FIG. 1 is a graph depicting Time vs Temperature for solids
post-Thermal Hydrolysis (or Thermal Carbonization) Process (THP)
with or without recovery as shown where t=time in hours, and
Temp=temperature in degrees Celsius.
[0008] FIG. 2 is a graph showing the apparent viscosity profiles
for solids concentration of about 10.5% before and after THP where
treatment is at 130, 150, or 170 degrees C. respectively.
[0009] FIG. 3 is a graph representing the Thermal Pretreatment
Temperature in degrees C. vs Viscosity at a shear rate of 7/s
(mPa-s).
[0010] FIG. 4 is a flowchart depicting waste activated sludge and
primary sludge feeding a Thermal Hydrolysis (or Thermal
Carbonization) and Pasteurization Process in parallel while being
heat treated before being mixed in an Anaerobic digester and
ultimately dewatered such that the end cake product is separated
from the residual centrate/filtrate.
[0011] FIG. 5 is a flowchart showing waste activated sludge feeding
a Thermal Hydrolysis (or Thermal Carbonization) and simultaneously
primary sludge fed Pasteurization Process in series, as heat input
occurs in parallel in the Thermal Hydrolysis (or Thermal
Carbonization) and Pasteurization process.
[0012] FIG. 6 is a flowchart representing waste activated sludge
and primary sludge feeding a Thermal Hydrolysis (or Thermal
Carbonization) and Pasteurization Process in parallel while a heat
exchanger connects the Thermal Hydrolysis (or Thermal
Carbonization) process to the Pasteurization process such that only
the mass of the sludge is treated in parallel by each process,
while the heat transfer occurs prior to the anaerobic digester.
[0013] FIG. 7 is a flowchart displaying waste activated sludge
feeding a Thermal Hydrolysis (or Thermal Carbonization) and
simultaneously primary sludge fed Pasteurization Process in series,
as heat input occurs in parallel in the Thermal Hydrolysis (or
Thermal Carbonization) and Pasteurization process while a heat
exchanger connects the Thermal Hydrolysis (or Thermal
Carbonization) process to the Pasteurization process such neither
the sludge treatment nor the heat transfer occur in parallel prior
to the anaerobic digester.
[0014] FIG. 8 is a flowchart presenting waste activated sludge and
primary sludge feeding a Thermal Hydrolysis (or Thermal
Carbonization) and Pasteurization Process, respectively, in
parallel while being heat treated before being mixed in an optional
blending tank or remaining in parallel before being ultimately
dewatered such that the cake is further anaerobically digested
while separated first from the residual centrate/filtrate.
[0015] FIG. 9 is a flowchart depicting waste activated sludge
feeding a Thermal Hydrolysis (or Thermal Carbonization) and
simultaneously primary sludge fed Pasteurization Process in series,
as heat input occurs in parallel in the Thermal Hydrolysis (or
Thermal Carbonization) and Pasteurization process prior to the mix
being dewatered and the cake is further anaerobically digested
while separated first from the centrate/filtrate.
[0016] FIG. 10 is a flowchart illustrating waste activated sludge
and primary sludge feeding a Thermal Hydrolysis (or Thermal
Carbonization) and Pasteurization Process in parallel while a heat
exchanger connects the Thermal Hydrolysis (or Thermal
Carbonization) process to the Pasteurization process such that only
the mass of the sludge is treated in parallel by each process,
while the heat transfer occurs prior to being mixed in an optional
blending tank or remaining in parallel before being ultimately
dewatered such the cake is further anaerobically digested while
separated first from the centrate/filtrate
[0017] FIG. 11 is a flowchart depicting waste activated sludge
feeding a Thermal Hydrolysis (or Thermal Carbonization) and
simultaneously primary sludge fed Pasteurization Process in series,
as heat input occurs in parallel in the Thermal Hydrolysis (or
Thermal Carbonization) and Pasteurization process while a heat
exchanger connects the Thermal Hydrolysis (or Thermal
Carbonization) process to the Pasteurization process such neither
the sludge treatment nor the heat transfer occur in parallel prior
to the mix being dewatered and the cake is further anaerobically
digested while separated first from the centrate/filtrate
[0018] FIG. 12 is a flowchart that shows an implementation of
hydrolysis (thermal, alkaline, acid, E-Beam or a combination
thereof) associated with recuperative thickening. Influent solids
is optionally pasteurized or optionally thickened and optionally
added directly to digestion, or, upstream or downstream of the
hydrolysis or recuperative thickening process.
[0019] FIG. 13 is a flowchart showing an implementation of
pre-pasteurization and hydrolysis ((thermal, alkaline, acid, E-Beam
or a combination thereof) associated with recuperative thickening.
In this case the influent thickened solids is optionally sent
partly of fully to pasteurization and the remainder is sent to a
digester either upstream or downstream of hydrolysis step.
[0020] FIG. 14 is a flowchart showing an implementation of
pre-digestion hydrolysis (thermal, alkaline, acid, E-Beam or a
combination thereof) with separate solids and liquid digestion.
[0021] FIG. 15 is a flowchart that shows pasteurization and
hydrolysis (thermal, alkaline, acid, E-Beam or a combination
thereof) before anaerobic digestion.
[0022] It is envisioned that FIGS. 4-11 may be preceded by a
thickening or dewatering device in certain embodiments. The
dewatering step can also be a final step immediately after
hydrolysis or carbonization.
DETAILED DESCRIPTION OF THE INVENTION
[0023] Some of the preferred embodiments of the present disclosure
are illustrated in the attached drawings:
[0024] FIG. 1 is a graph depicting Time vs Temperature for solids
post-Thermal Hydrolysis (or Thermal Carbonization) Process with or
without recovery as shown where t=time in hours, and
Temp=temperature in degrees Celsius.
[0025] FIG. 2 is a graph showing the apparent viscosity profiles
for solids concentration of about 10.5% before and after THP where
treatment is at 130, 150, or 170 degrees C. respectively.
[0026] FIG. 3 is a graph representing the Thermal Pretreatment
Temperature in degrees Celsius versus Viscosity at a shear rate of
7/s (mPa-s).
[0027] FIG. 4 is a flowchart depicting waste activated sludge 402
feeding a Thermal Hydrolysis (or Thermal Carbonization) 404 as Heat
Input is provided 406 and a heat exchanger cycles residual heat
408. Simultaneously Primary Sludge 410 feeds a Pasteurization
Process 412 in parallel as Heat Input is provided 414 and a heat
exchanger cycles residual heat 416 before being mixed in an
Anaerobic Digester 418 (which also sends residual heat to the
aforementioned heat exchangers 408,416) and sent to dewatering 420
so that the end cake produced 422 is separated from the residual
centrate/filtrate 424.
[0028] FIG. 5 is a flowchart depicting waste activated sludge 502
feeding a Thermal Hydrolysis (or Thermal Carbonization) 504 as Heat
Input is provided 506 and a heat exchanger cycles residual heat 508
before the sludge is sent to Pasteurization 512 in series.
Simultaneously Primary Sludge 510 feeds the Pasteurization Process
512 as Heat Input is provided 514 and a heat exchanger cycles
residual heat 516 before being mixed in an Anaerobic Digester 518
(which also sends residual heat to the aforementioned heat
exchangers 508,516) and sent to dewatering 520 so that the end cake
produced 522 is separated from the residual centrate/filtrate
524.
[0029] FIG. 6 is a flowchart representing waste activated sludge
602 feeding a Thermal Hydrolysis (or Thermal Carbonization) 604 as
Heat Input is provided 606 and a heat exchanger cycles residual
heat 608. Simultaneously Primary Sludge 610 feeds a Pasteurization
Process 612 in parallel as Heat Input is provided 614 and a heat
exchanger cycles residual heat 616 before being mixed in an
Anaerobic Digester 618 (which also sends residual heat to the
aforementioned heat exchangers 608,616) and sent to dewatering 620
so that the end cake produced 622 is separated from the residual
centrate/filtrate 624. Heat is balanced between the parallel
thermal hydrolysis (or thermal carbonization) 604 and
Pasteurization 612 processes through the use of a heat exchanger
626 directly connecting the two.
[0030] FIG. 7 is a flowchart displaying waste activated sludge 702
feeding a Thermal Hydrolysis (or Thermal Carbonization) 704 as Heat
Input is provided 706 and a heat exchanger cycles residual heat 708
before the sludge is sent 725 to Pasteurization 712 in series.
Simultaneously Primary Sludge 710 feeds the Pasteurization Process
712 as Heat Input is provided 714 and a heat exchanger cycles
residual heat 716 before being mixed in an Anaerobic Digester 718
(which also sends residual heat to the aforementioned heat
exchangers 708,716) and sent to dewatering 720 so that the end cake
produced 722 is separated from the residual centrate/filtrate 724.
Heat is also balanced between the parallel THP 704 and
Pasteurization 712 processes through the use of a heat exchanger
726 directly connecting the two so that neither mass nor heat truly
run in parallel in this embodiment.
[0031] FIG. 8 is a flowchart presenting waste activated sludge 802
feeding a Thermal Hydrolysis (or Thermal Carbonization) 804 as Heat
Input is provided 806 and a heat exchanger cycles residual heat
808. Simultaneously Primary Sludge 810 feeds a Pasteurization
Process 812 in parallel as Heat Input is provided 814 and a heat
exchanger cycles residual heat 816 before being mixed in an
optional blending tank 818 or remaining in parallel before being
sent to dewatering in either case 820 such that the cake digestion
process final cake product 822 is separated from the residual
centrate/filtrate 824.
[0032] FIG. 9 is a flowchart depicting waste activated sludge 902
feeding a Thermal Hydrolysis (or Thermal Carbonization) 904 as Heat
Input is provided 906 and a heat exchanger cycles residual heat 908
before the sludge is sent 925 to Pasteurization 912 in series.
Simultaneously Primary Sludge 910 feeds the Pasteurization Process
912 as Heat Input is provided 914 and a heat exchanger cycles
residual heat 916 prior to the mix being sent to dewatering 918 and
the centrate/filtrate 920 separated from the cake digestion
processes final cake product 922.
[0033] FIG. 10 is a flowchart illustrating waste activated sludge
1002 feeding a Thermal Hydrolysis (or Thermal Carbonization) 1004
as Heat Input is provided 1006 and a heat exchanger cycles residual
heat 1008. Simultaneously Primary Sludge 1010 feeds a
Pasteurization Process 1012 in parallel as Heat Input is provided
1014 and a heat exchanger cycles residual heat 1016 before being
mixed in an optional blending tank 1018 or remaining in parallel
before being sent to dewatering in either case 1020 such that the
cake digestion process final cake product 1022 is separated from
the residual centrate/filtrate 1024. Heat is balanced between the
parallel THP 1004 and Pasteurization 1012 processes through the use
of a heat exchanger 1026 directly connecting the two.
[0034] FIG. 11 is a flowchart depicting waste activated sludge 1102
feeding a Thermal Hydrolysis (or Thermal Carbonization) 1104 as
Heat Input is provided 1106 and a heat exchanger cycles residual
heat 1108 before the sludge is sent 1125 to Pasteurization 1112 in
series. Simultaneously Primary Sludge 1110 feeds the Pasteurization
Process 1112 as Heat Input is provided 1114 and a heat exchanger
cycles residual heat 1116 prior to the mix being sent to dewatering
1118 and the centrate/filtrate 1120 separated from the cake
digestion processes final cake product 1122. Heat is also balanced
between the parallel THP 1104 and Pasteurization 1112 processes
through the use of a heat exchanger 1126 directly connecting the
two so that neither mass nor heat truly run in parallel in this
embodiment.
[0035] FIG. 12 is a flowchart showing an implementation of
hydrolysis (thermal, alkaline, acid, E-Beam or a combination
thereof) associated with recuperative thickening. Influent solids
is optionally pasteurized or optionally thickened and optionally
added directly to digestion, or, upstream or downstream of the
hydrolysis or recuperative thickening process.
[0036] FIG. 13 is a flowchart showing an implementation of
pre-pasteurization and hydrolysis ((thermal, alkaline, acid, E-Beam
or a combination thereof) associated with recuperative thickening.
In this case the influent thickened solids is optionally sent
partly of fully to pasteurization and the remainder is sent to a
digester either upstream or downstream of hydrolysis step.
[0037] FIG. 14 is a flowchart showing an implementation of
pre-digestion hydrolysis (thermal, alkaline, acid, E-Beam or a
combination thereof) with separate solids and liquid digestion.
[0038] FIG. 15 is a flowchart that shows pasteurization and
hydrolysis (thermal, alkaline, acid, E-Beam or a combination
thereof) before anaerobic digestion.
[0039] It is envisioned that FIGS. 4-11 may be preceded by a
thickening or dewatering device in certain embodiments. The
pasteurization process in the above figures can be replaced with a
hydrolysis or thermal carbonization process; or can also be
combined with hydrolysis. The utility of the proposed components
for these embodiments is explicitly detailed below:
[0040] Reactors and Process Streams: The solids are heated in
reactors. The heat for pasteurization can be provided using solar
cells that can directly or indirectly heat sludge. The fluid can be
air, water or other heat transfer material. The reactor can be
operated as a continuous flow through process, a batch process, a
sequencing batch process, or a plug-flow process. Any pressurized
solids can be depressurized either slowly or rapidly. The reactor
can be heated using steam, heat exchangers or heat pumps and
pressurized using solar, thermal, hydraulic or mechanical
approaches. Single or multiple reactors can be comprised within two
or more influent heat and/or mass flow streams that are either
fully in parallel or are in series (such as a tributary) to an
overall heat and/or mass flow stream or in combination of parallel
or series as desired. The heat and mass flows streams can be
uncoupled as desired. For example, the heat stream could flow in as
a tributary for a fully parallel mass flow stream.
[0041] Proposed Treatment Temperature for Reactors: The invention
proposes a method or apparatus wherein temperature of wastewater
solids (or other products and wastes) is increased between 60 and
220 degrees Celsius (<180.degree. C. is thermal hydrolysis and
>180.degree. C. is thermal carbonization) to increase feed
solids concentration to anaerobic digestion, decrease digester
volume requirements, increase throughput rates of anaerobic
treatment, increase cake solids, improve microbial hydrolysis
rates, inactivate pathogens or indicators, or decrease head loss,
mixing or pumping energy, and that reduces viscosity of the solids.
Additional hydrolysis (chemical (acid, alkaline or other
compounds), manufactured enzyme, naturally produced enzyme such as
through aerobic thermophilic pretreatment), or E-beam) or
combination of approaches can be mixed in to achieve desired
performance and much lower temperatures than those typically
preferred (100.degree. C.-180.degree. C.) for thermal hydrolysis.
In one approach of this method or apparatus, a more viscous or more
slowly hydrolysable solids such as waste activated sludge,
cellulosic waste, slowly digestible organic waste is thermally (or
other forms or combinations of hydrolysis) hydrolyzed at higher
temperatures between 60 and 180 degrees Celsius (or up to
220.degree. C. for thermal carbonization) and wherein the more
easily hydrolysable (non-rate limiting solids) such as primary
solids, food waste or any other organic waste or products is
pasteurized at lower temperatures between 60 and 100 degrees
Celsius. More than two streams with multiple wastes and
temperatures are also possible. This approach allows for managing
and optimizing the use of temperature and heat for the two streams
and to simultaneously achieve optimized reductions in viscosity
(and thereby increased process throughput rates), while achieving
pasteurization, increased digestion rates and/or increased
dewatered cake solids. The two (or multiple) streams could be in
parallel or series of each other, with the possibility of heat
transfer/sharing or stream mixing. In the case of series approach
the lower temperature stream is usually pasteurized downstream of
the higher temperature stream (with mass or heat transfer occurring
between the two (or multiple) streams).
[0042] Proposed Viscosity Characteristics: The higher viscosity
solids (approximately >2500 mPa-s when operated at a solids
concentration of about 10%, a temperature of about 20 C, and a
shear rate of 7 s-1) or less hydrolysable/digestible solids
(requiring an overall solids retention time approximately greater
than 5-7 days) are typically heated to higher temperatures (and its
corresponding pressure) of 100 to 180 degrees Celsius (or
220.degree. C. for thermal carbonization) or undergo other forms of
hydrolysis (alkaline, acid, enzymic (externally manufactured (at a
manufacturing process for such production) or naturally produced),
E-Beam. Lower viscosity solids (approximately <3500 mPa-s when
operated at a solids concentration of about 10%, a temperature of
about 20.degree. C., and a shear rate of 7 s-1) are typically
heated to lower temperatures of 60 to 100 degrees Celsius. Solids
in between 2500 mPa-s and 3500 mPa-s can be heated in either of the
two approaches to create the appropriate `mix` of viscosity
characteristics for anaerobic digestion.
[0043] Proposed Thickened/Dewatered Solids Concentration: The
solids are typically pre-thickened or dewatered to approximately
3-15% solids before the heat `reactions`, although much higher
solids of 35% is also possible. After the heating reaction, the
solids can be either diluted, thickened or dewatered to a solids
concentration of between 7-55%, the higher solids concentration
occurring to promote `dry digestion`. For the special case of dry
digestion, a single stream is permitted (a multiple mix stream is
not needed), where the thickening/dewatering step occurs between
the heating reactors and the anaerobic digestion process. The
filtrate or centrate liquor obtained after thickening/dewatering
(when thickening or dewatering occurs between `heating reactors`
and `digestion` steps) can be used as a carbon source for
biological nutrient removal or anaerobic digestion as needed. The
thickening/dewatering that occurs before the heating step could
allow for concomitant phosphorus release in the filtrate on
centrate if desired. Dewatering can also be the final step of the
overall process (without including a digestion step
thereafter).
[0044] In another embodiment of this invention, the stream for the
high-temperature hydrolyses (or carbonization) process is dewatered
to a solids concentration of >8, while the stream for the
pasteurization process is thickened to a solids concentration
<8% in order to manage the relative viscosities and the heat
balances of the two streams.
[0045] In some embodiments of the present disclosure, a heat
generator can regulate higher temperatures of 135 to 180 degrees
Celsius as reserved for the higher viscosity solids or less
digestible solids.
[0046] In an another approach to manage the solids concentration, a
portion of the solids is sent to the pre-treatment involving high
temperature and high solids concentration is controlled in order to
match a pre-defined hydraulic retention time in the down-stream
anaerobic digester. Dilution water can be added to additionally
manage the solid concentration and/or hydraulic retention time.
This management of the solids concentration and time will allow for
the achievement of stable digestion. In some embodiments, the
management of solids concentration and dilution will address
inhibition (such as from ammonia) or toxicity.
[0047] Proposed use of the filtrate or centrate (after the heating
reaction). The removed liquid of the dewatering process can consist
of refractory material or substance that is produced during the
thermal hydrolysis or carbonization processes. The liquid can be
harvested as a sterilized product for agriculture, fermentation
feed stock, antimicrobial blends or for chelation. The removed
liquid of the dewatering process can comprise humic and fulvic
substances. The removed liquid could consist of inhibitors or
growth promoters of bacteria for selecting specific reactions
within microbial cycles. The production of these constituents (such
as chelators or other inhibitors) in this liquid can be controlled
using sensors (such as ultraviolet (UV) scan, UV, Raman, infrared,
FTIR, or other forms of spectroscopy). This control can thus manage
(through feedback control controlled using a sensor that controls a
pump, valve or other devices), the temperatures used for the
thermal hydrolysis or carbonization reactions. The thermal
hydrolysis and carbonization reactions are expected to in many
cases produce these refractory compounds at the very point of
impact of high temperature steam or other heat exchange material
(by scalding, scorching, charring or otherwise changing molecular
structures of the sludge) on a sludge particle. The production of
the refractory constituents can be decreased or mitigated by better
`direct heat` dissipation by any method available including the use
of water baths, lower temperature steam baths, better mixing (flash
mixing or other approaches of rapid mixing), or any other
approaches that are available for such purpose of preventing the
scalding, scorching, charring or otherwise changing molecular
structures of the sludge.
[0048] The production of refractory substances (refractory
material) during the thermal hydrolysis or carbonization processes
can be managed or controlled using a sensor that controls a pump,
valve or other devices. The production of refractory substances
during thermal hydrolysis or carbonization can be minimized through
more rapid heat dissipation using better mixing, heat transfer or
heat management approaches.
[0049] In another embodiment of the invention, the temperature can
be increased using solar energy or solar cells that directly or
indirectly heat sludge.
[0050] Proposed use of thickened or dewatered solids. The
sterilized solids can be bioaugmented with specialized
micro-organism prior to anaerobic digestion, prior to or after
dewatering, or prior to agricultural use of solids. These
microorganisms could comprise specialized bacteria or fungi (such
as nitrogen fixers or Trichoderma) that could promote its
agricultural use. The specialized micro-organisms could also be
specifically used to consume excess hydrogen in digesters, produce
excess hydrogen in digesters, or to increase Firmicutes over
Bacteroedetes ratio, or to increase anaerobic nitrogen
fixation.
[0051] Recuperative Thickening: Recuperative thickening (the
thickening of sludge in the recirculation loop of an anaerobic
digester) is also possible as shown in some figures. The influent
solids of the two streams can be added at different locations prior
to the recuperative thickening process, hydrolysis process,
pasteurization process or directly to digestion.
[0052] Pasteurization to address regrowth of indicators and
pathogens: A minimum temperature of 75 degrees Celsius for about 30
minutes is usually required to address resuscitation and regrowth
of indicator and pathogens, especially if approximately more than
3-4 logs (10.sup.3-10.sup.4 colony forming units/gram dry solids,
10.sup.3-10.sup.4 most probable number/g dry solids, or
10.sup.3-10.sup.4 unique DNA copies/g dry solids of these organisms
are present. Thermophilic or high temperature aerobic pretreatment
(that can also improve hydrolysis) can also be used in lieu of, or
in combination with pasteurization.
[0053] Proposed approach to improve hydrolysis/particle destruction
rates in anaerobic digester: Microbial hydrolysis/particle
destruction rates are improved by decreasing microbe to substrate
(especially particulate substrate) proximity (by
thickening/dewatering the solids), microbe-microbe proximity (by
thickening/dewatering the solids), or increasing diffusivity
through decreased viscosity (associated with destruction/release of
structured or bound water). Forms of hydrolysis include, thermal,
chemical, enzymic or E-Beam or combinations thereof. Chemical
hydrolysis can include but is not limited to acid or alkaline
hydrolysis. Alkaline hydrolysis can include (but not limited to)
the use of potassium hydroxide, sodium hydroxide, calcium
oxide/hydroxide or magnesium oxide/hydroxide or a combination of
these chemicals. Acid hydrolysis can be achieved using naturally
produced (VFA) or synthetic acids.
[0054] Proposed control of temperature based on viscosity
characteristics. The pasteurization temperature can be controlled
directly or indirectly based on viscosity characteristics of the
solids. The viscosity could be measure directly or through indirect
control based on head loss in pumps or torque in a mixer, or any
such approach. Direct viscosity based control can occur using an
in-line or off-line or lab measured viscosity value using a shear
rate as required.
[0055] Proposed control of viscosity characteristics using solids
dilution. The solid dilution or thickening is used to control
viscosity of solids through direct or indirect viscosity
measurement as desired. The viscosity could be measure directly or
through indirect control based on head loss in pumps or torque in a
mixer, or any such approach. Direct viscosity based control can
occur using an in-line or off-line or lab measured viscosity value
using a shear rate as required.
[0056] In some embodiments of the present disclosure, a refractory
substance is produced. The production of refractory substances
during the thermal hydrolysis or carbonization processes can be
managed or controlled using a sensor that controls a pump, valve or
other devices. The production of refractory substances during
thermal hydrolysis or carbonization can be minimized through more
rapid heat dissipation using better mixing, heat transfer or heat
management approaches.
[0057] In another embodiment of the invention, the temperature can
be increased using solar energy or solar cells that directly or
indirectly heat sludge.
[0058] The invention also relates to a method for Hydrolysis (or
Thermal Carbonization) treatment wherein temperature of wastewater
solids is increased between 60 and 220 degrees Celsius to increase
feed solids concentration to digestion, decrease digester volume
requirements, increase throughput rates of anaerobic treatment,
increase cake solids, improve microbial hydrolysis rates,
inactivate pathogens or indicators, or decrease head loss, mixing
or pumping energy, and that reduces viscosity of the solids,
wherein the mostly waste activated sludge, cellulosic waste, slowly
digestible organic waste is hydrolyzed (using thermal, thermophilic
aerobic, chemical, enzyme, or electron beam) at temperatures
between 60 and 180 degrees Celsius (or up to 220 degrees Celsius
for thermal carbonization) and wherein the mostly primary solids,
food waste or any other organic waste or products is pasteurized at
temperatures between 60 and 100 degrees Celsius. The higher
temperatures for hydrolysis or carbonization approaches are
reserved for the higher viscosity solids or less digestible
solids
[0059] In some embodiments of the present disclosure, the solids
produced after treatment are dewatered to increase cake solids of a
content of 7-55% total dry solids prior to anaerobic digestion or
composting of these solids.
[0060] In some embodiments of the present disclosure, the stream
for the high-temperature hydrolyses process is dewatered to a
solids concentration greater than approximately 8%, while the
stream for the pasteurization process is thickened to a solids
concentration less than approximately 8%.
[0061] In other embodiments, the portion of the solids sent to the
pre-treatment involving high temperature and high solids
concentration is controlled in order to match a pre-defined
hydraulic retention time in the down-stream anaerobic digester.
[0062] In another embodiment of the invention, removed liquid of
the dewatering process is used as a carbon source for biological
nutrient removal, anaerobic digestion. The removed liquid of the
dewatering process may be harvested as a sterilized product for
agriculture, fermentation feed stock, antimicrobial blends, or
chelation. The removed liquid of the dewatering process can
increase breakdown of humic-towards fulvic substances if
targeted.
[0063] In another embodiment of the invention, solids produced
after additional anaerobic digestion are dewatered to increase cake
solids to a content of 7-55% total dry solids.
[0064] In another embodiment of the invention, the solids produced
before treatment are dewatered to increase cake solids of a content
of 3-35% total dry solids.
[0065] In some embodiments of the present disclosure, a minimum
temperature of 75 degrees Celsius for 20-40 minutes is required to
prevent resuscitation and regrowth of indicator and pathogens.
[0066] In some embodiments of the present disclosure, the microbial
hydrolysis rates are improved by decreasing microbe to substrate
proximity, microbe-microbe proximity, or increasing diffusivity
through decreased viscosity.
[0067] In another embodiment of the invention, the thermal
hydrolyses time or pasteurization temperature is controlled
directly or indirectly based on viscosity characteristics of the
solids. The indirect control is based on head loss in pumps, torque
in a mixer, and direct control is based on an in-line or off-line
or lab measured viscosity.
[0068] In another embodiment of the invention, solid dilution or
thickening is used to control viscosity of solids.
[0069] The pasteurization process can use heat recovered from the
Thermal Hydrolysis (or Thermal Carbonization) process by either
mixing the solids streams or by using heat exchangers.
[0070] In some embodiments of the present disclosure, sterilized
solids are bioaugmented with specialized micro-organisms to promote
anaerobic digestion, dewatering and agricultural use of solids. The
specialized micro-organisms may be used to consume hydrogen, to
increase Firmicutes over Bacteroidetes ratio, or increase anaerobic
nitrogen fixation.
[0071] It is understood that the various disclosed embodiments are
shown and described above to illustrate different possible features
of the disclosure and the varying ways in which these features may
be combined. Apart from combining the features of the above
embodiments in varying ways, other modifications are also
considered to be within the scope of the disclosure. The disclosure
is not intended to be limited to the preferred embodiments
described above, but rather is intended to be limited only by the
claims set out below. Thus, the disclosure encompasses all
alternate embodiments that fall literally or equivalently within
the scope of these claims.
[0072] The invention is not limited to the structures, methods and
instrumentalities described above and shown in the drawings. The
claims proposed are examples and additional claims or modifications
of these claims are likely. The invention is defined by the claims
set forth below. What is claimed and desired to be protected by
Letters Patent of the United States is:
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