U.S. patent application number 13/911519 was filed with the patent office on 2013-10-10 for method for preparing pellets from rice husk and apparatus for removing odor using rice husk pellet bio-media.
This patent application is currently assigned to Korea Institute of Construction Technology. The applicant listed for this patent is Korea Institute of Construction Technology. Invention is credited to Kwang-Soo KIM, Jun-Ho Park.
Application Number | 20130267018 13/911519 |
Document ID | / |
Family ID | 43010095 |
Filed Date | 2013-10-10 |
United States Patent
Application |
20130267018 |
Kind Code |
A1 |
KIM; Kwang-Soo ; et
al. |
October 10, 2013 |
METHOD FOR PREPARING PELLETS FROM RICE HUSK AND APPARATUS FOR
REMOVING ODOR USING RICE HUSK PELLET BIO-MEDIA
Abstract
A method for preparing pellets from rice husk includes: grinding
rice husk; adding ammonia water to a mixture of ethylene vinyl
acetate and poly(vinylacetate) to prepare a mixed, liquid binder;
mixing the mixed, binder with the ground rice husk to obtain a
binder/rice husk mixture; extruding the binder/rice husk mixture
through an extruder; and cooling the extruded mixture at room
temperature.
Inventors: |
KIM; Kwang-Soo;
(Gyeonggi-do, KR) ; Park; Jun-Ho; (Gyeonggi-do,
KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Korea Institute of Construction Technology |
Gyeonggi-do |
|
KR |
|
|
Assignee: |
Korea Institute of Construction
Technology
|
Family ID: |
43010095 |
Appl. No.: |
13/911519 |
Filed: |
June 6, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12958070 |
Dec 1, 2010 |
|
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13911519 |
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Current U.S.
Class: |
435/289.1 |
Current CPC
Class: |
Y02A 50/20 20180101;
B01D 2251/606 20130101; Y02A 50/2358 20180101; B01D 2257/90
20130101; B01D 2251/304 20130101; B01J 2/20 20130101; B01D 2257/304
20130101; B01D 2257/406 20130101; B01D 53/58 20130101; B01D 53/52
20130101; B01D 2258/06 20130101; B01D 53/84 20130101; A61L 9/013
20130101 |
Class at
Publication: |
435/289.1 |
International
Class: |
A61L 9/013 20060101
A61L009/013 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 29, 2009 |
KR |
10-2009-0132940 |
Claims
1-5. (canceled)
6. An apparatus for removing odor using rice husk pellet bio-media,
the apparatus comprising: a circulating spray water reservoir; a
spray water pump connected to the circulating spray water reservoir
and serving to move circulating spray water; an odor air blower for
injecting an odor air; a bed layer of rice husk pellets located
upstream of an odor air supply region into which the odor air is
injected by the odor air blower; and a circulating spray water
injection nozzle located above the bed layer of rice husk
pellets.
7. The apparatus of claim 6, wherein the rice husk pellets in the
bed layer have a cylindrical shape having a diameter of 2 cm and a
length of 10 cm.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] Exemplary embodiments of the present invention relate to a
method for preparing pellets from rice husk and an apparatus for
removing odor using rice husk pellet bio-media; and, more
particularly, to a method for preparing cylindrical rice husk
pellets, including grinding rice husk, a by-product of rice
milling, and extruding the ground rice husk with a binder through
an extruder at high temperature, and to an apparatus for removing
atmospheric odor using the prepared rice hush pellets as
bio-media.
[0003] 2. Description of Related Art
[0004] In biological deodorization methods which have recently
attracted attention, materials for media on which microorganisms
grow include ceramics, wood barks, porous polymer media, etc.
However, the existing media have problems in that water and
nutrients essential for the growth of microorganisms should be
supplied in order for each medium to be used as a bio-medium and
also that a decrease in pH of water caused by the oxidation of
odor-causing compounds leads to the death of microorganisms.
[0005] In an attempt to solve the problems associated with the
existing bio-media, Korean Patent Registration No. 0375163
discloses a biological deodorization method employing rice husk and
rice-straw and an apparatus for carrying out the method. According
to the disclosure of the Korean Patent, the problem that the pH of
spray water decreases is overcome by using rice husk as media for
providing a carbon source to microorganisms and oxidizing
odor-causing compounds and by using rice-straw as microbial media
carrier for reducing oxidized odor compounds. Also, micronutrients
released from each of the media act as nutrients essential for the
growth of microorganisms to eliminate the need to supply external
carbon sources and nutrients.
[0006] However, in the above Korean Patent, the particle size of
rice husk, a by-product of rice milling, is as small as about 0.5
cm or smaller, a water film is formed in pores between rice husk
particles after wafer spray, and as the operating time becomes
longer, the rice husk layer settles under load to reduce the
porosity of the rice husk layer. For these reasons, there is a
problem in that, when odor-containing air is introduced, a great
pressure loss and channeling occur. In addition, there is a problem
in that the structure of the apparatus is complex, because, in
order to prevent the pH of circulating spray wafer from decreasing,
rice-straw and rice husk are placed separately in a water bath for
reduction and a water bath for oxidation, respectively, such that
the water baths are operated separately.
SUMMARY OF THE INVENTION
[0007] An embodiment of the present invention is directed to a
method for preparing pellets from rice husk, including grinding
rice husk, and compressing the ground rice husk with a hinder to
high density.
[0008] Another embodiment of the present invention is directed to
an apparatus for removing odor using rice husk pellet bio-media
prepared in accordance with the method of the present invention,
wherein the rice husk pellets have uniform porosity and may contain
a large amount of water so as to function as bio-media to which
microorganisms can adhere, and also wherein a high concentration of
an organic matter elated from the rice husk pellets during water
supply serves as an alkalinity source, such that a decrease in the
pH of circulating spray water does not occur over a long period of
time and further wherein the operating time of the apparatus can
further be extended by supplying chemicals, and an odor removal
operation may be carried out in one reactor without needing a water
bath for reduction.
[0009] Other objects and advantages of the present invention can be
understood by the following description, and become apparent with
reference to the embodiments of the present invention. Also, it is
obvious to those skilled in the art to which the present invention
pertains that the objects and advantages of the present invention
can be realized by the means as claimed and combinations
thereof.
[0010] In accordance with an embodiment of the present invention,
there is provided a method of preparing pellets from rice husk,
including: grinding rice husk; adding ammonia water to a mixture of
ethylene vinyl acetate and poly(vinylacetate) to prepare a mixed
liquid binder; mixing the mixed mixture with the ground rice husk
to obtain a binder/rice husk mixture; extruding the binder/rice
husk mixture through an extruder; and cooling the extruded mixture
at room temperature.
[0011] in accordance with still another embodiment of the present
invention, there is provided an apparatus for removing odor using
rice hush pellet bio-media prepared in accordance with the
above-described method of the present invention, the apparatus
including: a circulating spray water reservoir; a spray water pump
connected to the circulating spray water reservoir and serving to
move circulating spray water; an odor air blower for injecting an
odor air; a bed layer of rice husk pellets located upstream of an
odor air supply region into which the odor air is injected by the
odor air blower; and a circulating spray water injection nozzle
located above the bed layer of rice husk pellets.
BRIEF DESCRIPTION OP THE DRAWINGS
[0012] FIG. 1 is a flow chart schematically showing a method for
preparing rice husk pellets in accordance with an embodiment of the
present invention.
[0013] FIG. 2 schematically shows the structure of an apparatus for
removing odor using rice husk pellet bio-media in accordance with
an embodiment of the present invention.
[0014] FIGS. 3 to 6 show the results of measuring the outlet gas
concentrations and the changes in pH and alkalinity of spray
water.
DESCRIPTION OF SPECIFIC EMBODIMENTS
[0015] Exemplary embodiments of the present invention will be
described below in more detail with reference to the accompanying
drawings. The present invention may, however, be embodied in
different forms and should not be constructed as limited to the
embodiments set forth herein. Rather, these embodiments are
provided so that this disclosure will be thorough and complete, and
will fully convey the scope of the present invention to those
skilled in the art. Throughout the disclosure, like reference
numerals refer to like parts throughout the various figures and
embodiments of the present invention.
[0016] The method of preparing pellets from rice husk according to
the present invention includes: grinding rice husk; adding ammonia
water to a mixture of ethylene vinyl acetate and poly(vinylacetate)
to prepare a mixed liquid binder; mixing the mixed binder with the
ground rice husk to obtain a binder/rice husk mixture; extruding
the binder/rice husk mixture through an extruder; and cooling the
extruded mixture at room temperature.
[0017] Also, the rice husk may be ground to a particle size of 1 mm
or less, and the binder/rice husk mixture may be extruded through
the extruder maintained at a temperature between 80.degree. C. and
90.degree. C.
[0018] Moreover, in the adding ammonia water to the mixture of
ethylene vinyl acetate and poly(vinylacetate), the mixing ratio of
ethylene vinyl acetate: poly(vinylacetate): ammonia water may be
1:1:0.1. Moreover, the mixing ratio of the mixed binder: the ground
rice husk may be 10:2.
[0019] Another embodiment of the present invention is an apparatus
for removing odor using rice husk pellet bio-media prepared in
accordance with the above-described method of the present
invention, the apparatus including: a circulating spray water
reservoir; a spray water pump connected to the circulating spray
water reservoir and serving to move circulating spray water; an
odor air blower for injecting an odor air; a bed layer of rice husk
pellets located upstream of an odor air supply region into which
the odor air is injected by the odor air blower; and a circulating
spray water injection nozzle located above the bed layer of rice
husk pellets.
[0020] The rice husk pellet may have a cylindrical shape having a
diameter of 2 cm and a length of 3 cm.
[0021] Hereinafter, the construction, function and effect of
preferred embodiments of the method for preparing pellets from rice
husk according to the present invention and the apparatus for
removing odor using the rice husk pellet bio-media will be
described in detail.
[0022] FIG. 1 is a flow chart schematically showing a method for
preparing rice husk pellets in accordance with an embodiment of the
present invention. As shown therein, the method for preparing
pellets from rice husk includes: grinding rice husk; adding ammonia
water to a mixture of ethylene vinyl acetate and poly(vinylacetate)
to prepare a mixed liquid binder; mixing the mixed binder with the
ground rice husk to obtain a binder/rice husk mixture; extruding
the binder/rice husk mixture through an extruder; and cooling the
extruded mixture at room temperature,
[0023] The grinding of rice husk may be carried out by ball
milling. Also, the mixed liquid binder is prepared in the following
manner. First, water-soluble ethylene vinyl acetate (EVAc) and
poly(vinylacetate) (PVAc) are mixed with each other.
[0024] More specifically, if gum-state ethylene vinyl acetate and
highly viscous poly(vinylacetate) are combined with each other and
water is added thereto, the ethylene vinyl acetate will be
dissolved, but the poly(vinylacetate) will be set, thus making it
impossible to mix the two components. On the contrary, if ammonia
water that is an alkaline solution is added to the EVAc/PVAc
mixture, the PVAc will also be dissolved so that the mixed binder
of ethylene vinyl acetate and PVAc will be uniformly mixed with the
ground rice husk. Herein, the mixing weight ratio of ethylene vinyl
acetate:poly(vinylacetate):ammonia water (30%) may be 1:1:0.1, and
the mixing ratio of the mixed binder and the ground rice hush may
be 10:2 by weight ratio.
[0025] Then, the mixture of the ground rice husk and the binder is
placed in an extruder maintained at a temperature between about
80.degree. C. and 90.degree. C. In the extruder, the mixed binder
is melted and more uniformly mixed with the ground rice husk, and
the melted binder induces slippage during extrusion to facilitate
extrusion. Also, in the high-temperature extrusion process, ammonia
evaporates as gas, and thus the produced rice husk pellets are soft
in the initial stage after extrusion and become hardened after they
have been cooled at room temperature. When the pellets after being
hardened are immersed in water, the ethylene vinyl acetate
component will absorb a large amount of water due to its
hydrophobic nature so as to be swollen, and the poly(vinylacetate)
component from which the ammonia component evaporated will strongly
fix the ground rice husk particles, thereby providing pellets
contain water and, at the same time, are soft and elastic.
[0026] When raw rice husks are used as bio-media for odor removal,
there are problems in that influent odor gas is difficult to
uniformly pass through the rice husk bed layer, because the number
of pores between the rice husk particles is small such that the
rice husk bed layer is blocked by microorganisms, and water films
are formed in the pores. In addition, there is problem in that, as
the operating time become longer, the rice husk bed layer settles.
According to the present invention, such problems can be solved by
grinding raw rice husk and compressing the ground rice husk with a
binder to form pellet bio-media.
[0027] Odor gases such as ammonia and sulfide gases are oxidized to
nitrate or nitrite or sulfate ions by microorganisms in water, so
that the alkalinity of circulating spray water is consumed and the
pH of circulating spray water is lowered to the acidic range. If
the pH of circulating spray water is lowered to 6 or less, the
metabolism of nitrifying bacteria will be inhibited due to a lack
of alkalinity, so that the concentration of ammonia in circulating
spray water will be increased to produce odor gas. For this reason,
for the biological oxidation of ammonia gas, it is required to
continuously supplement alkalinity with an inorganic carbon
source.
[0028] In order to continuously supplement alkalinity, according to
the present invention, rice husk is ground and prepared into
pellets. The prepared pellets have a density which is about 30
times higher than that in Korean Patent Registration No. 0375163 in
which raw rice husk is used as bio-media. Accordingly, the pellets
of the present invention can supplement alkalinity for a long
period of time, and thus allows the odor removal apparatus to be
operated for a long period of time without lowering the pH of
circulating spray water. In addition, when carbon components in the
rice husk pellets are completely eluted and exhausted, a mixture of
sodium carbonate (Na.sub.2CO.sub.3) and sodium hydrogen carbonate
(NaHCO.sub.3) as alkaline agents, mixed at a molar ratio of 1:2 or
more, may be introduced so that they can act as a carbon source for
the growth of bacteria and as an alkalinity source, whereby the
odor removal apparatus can be operated for a more extended period
of time without lowering the pH of circulating spray water. Sodium
carbonate and sodium hydrogen carbonate coexist as the electron
donor carbonate (CO.sub.3.sup.-) and the electron acceptor hydrogen
carbonate (HCCV), so that they are used not only as a buffer to
inhibit the change in pH of water, but also as a carbon source for
nitrifying bacteria that grow using inorganic carbon
(CO.sub.2).
[0029] Accordingly, by using rice husk pellets (obtained by
compressing rice husk) as bio-media and by additionally using
sodium carbonate and sodium hydrogen carbonate, circulating spray
water can be used for a long period of time, and as a result, odor
removal can be achieved even by one spray water reservoir without
needing to place a separate water bath for reduction.
[0030] Hereinafter, an apparatus for removing odor using the rice
husk pellet bio-media prepared according to the above-described
method will be described in detail.
[0031] FIG. 2 schematically shows an apparatus for removing odor
using rice husk pellet bio-media according to the present
invention.
[0032] As shown in FIG. 2, an odor removal apparatus 100 according
to the present invention includes a circulating spray water
reservoir 110, a spray water pump 120, an odor air blower 140, a
bed layer of rice husk pellet media 130, and a circulating spray
water injection nozzle 150.
[0033] The circulating spray water reservoir 110 serves to store
circulating spray water, and the spray wafer pump 120 serves to
spray circulating spray water to the bed layer of rice husk pellet
media 130. Also, the odor air blower 140 serves to inject odor air,
and the bed layer of rice husk pellet media 130 is located such
that it is supported by a mesh-shape member upstream of an odor air
supply region into which odor air is injected by the odor air
blower 140. Furthermore, the circulating spray water injection
nozzle 150 is placed above the bed layer of rice husk pellet media
130 and serves to inject circulating spray water.
[0034] The above-described elements are arranged in a vertical
direction and included in a body.
[0035] In the apparatus constructed as described above, the rice
husk swell upon water absorption to become elastic, and carbon,
phosphorus and the like required for microbial growth are eluted
from the rice husk pellets and contained in water in the
circulating spray water reservoir 110.
[0036] Also, when spray of water to the bed layer of rice husk
pellet media 130 is continued, atmospheric microorganisms adhere to
and live on the surface of the rice husk pellets. When an odor air
containing ammonia and sulfide gases is injected by the blower 140
and moved upward to contact with the rice husk pellet which has
microorganisms attached thereto, the ammonia and sulfide gases are
adsorbed and oxidized by the microorganisms to nitrate nitrogen and
sulfate, and an odor-free clean air is discharged from the odor
removal apparatus.
[0037] When the nitrate nitrogen and sulfate oxidized in the bed
layer of rice husk pellet media 130 is washed by the downwardly
sprayed water and accumulated in the circulating spray water
reservoir 110, the pH and alkalinity of circulating spray water in
the reservoir are lowered. However, due to the supply of alkalinity
by carbon components which are continuously elated from the rice
husk pellets, the pH-lowering rate is very slow. After alkalinity
resulting front the rice husk pellets has been completely
exhausted, when an alkaline carbonate mixture of sodium carbonate
and sodium hydrogen carbonate as a buffer to inhibit the change in
pH of water is introduced into the circulating spray water
reservoir, it is possible to continuously treat odor gas without
lowering the pH of circulating spray water.
[0038] Also, at a microbial inoculation stage, spray water is
sprayed at high frequency, but after microbial inoculation, spay
water may be sprayed 2-3 times a day, because the rice husk pellets
are made such that they contain water.
[0039] Accordingly, the process of removing odor using the rice
husk pellet media of the present invention is as follows. An odor
air is introduced through the blower 140 into the odor removal
apparatus, and the introduced odor air is moved upward, and then
the odor components of the odor air are oxidized by microorganisms
attached to the bed layer of rice husk pellet media 130, while a
clean air is discharged from the apparatus. The odor gas oxidized
in the bed layer of pellet media is washed by the sprayed water and
accumulated in the circulating water spray reservoir 110. Water in
the circulating spray water reservoir 110 is treated with carbon
sources eluted from the rice husk pellets by water spray, and then
is treated with alkaline carbonates which are additionally
supplied.
[0040] Hereinafter, the results of comparative experiments carried
out in the present invention will be described. In the present
invention, plain rice husk and rice husk pellets containing a
binder were compared to each other with respect to water content
upon introduction of odor air, head loss according to air flow
rate, the ability to prevent the pH of spray water from decreasing
due to the oxidation of ammonia gas and sulfide gas, and the
ability to remove odor gas.
[0041] In order to carry out the comparative experiments, a
cylindrical acrylic column having a diameter of 10 cm and a height
of 1.2 m was divided into an odor gas chamber having a height of 30
cm, a wafer spray chamber having a height of 30 cm and a rice husk
media layer having a height of about 60 cm, and as a circulating
spray water reservoir, a vessel having a volume of about 8 L was
provided separately from the column. Using this arrangement,
circulating spray water was sprayed to the rice husk media layer
for 5 minutes at 1-hour intervals.
[0042] The same two reactors were used to compare plain rice husk
with the bed layer of rice husk pellets. Plain rice husk was used
in a raw state and filled in the rice husk media layer, and the
pellet rice husk of the present invention was used in a cylindrical
shape having a diameter of 2 cm and a length of 3 cm and was filled
in the in the rice husk media layer
TABLE-US-00001 TABLE 1 Plain rice husk Pellet rice husk Weight
Weight Initial after water Increase Initial after water Increase
weight absorption in weight weight absorption in weight (g) (g) (%)
(g) (g) (%) 3 4.6 150 3 6.2 210 8 10.7 134 8 18.4 230 12 17 140 12
25.2 210
[0043] Table 1 above compares the water content between plain rice
husk and the pellet rice husk after water spray. As can be seen in
Table 1, plain rice husk showed an increase in weight of about 140%
compared to the initial weight, whereas the pellet rice husk of the
present invention showed an increase in weight of about 220%
compared to the initial weight. This suggests that the pellet rice
husk prepared by mixing the ground rice husk with the mixed binder
(ethylene vinyl acetate and poly (vinylacetate) has a very high
water content, and thus it can reduce the frequency of water spray
and is not dried even when odor air is introduced for a long period
of time.
TABLE-US-00002 TABLE 2 Air flow rate Residence Head loss of Head
loss of (L/min) time (sec) plain rice husk pellet rice husk 4 60 0
0 8 30 40 mm 0 12 20 30 mm 1 mm
[0044] Table 2 compares the head loss according to the change in
residence time caused by the change in air flow rate between plain
rice husk and the pellet rice husk. As can be seen in Table 2, in
the case of plain rice husk, the porosity was about 40%, water
films were formed in the pores of the rice husk particles, and thus
the higher the air flow rate, the higher was the head loss. On the
contrary, in the case of the pellet rice husk, the porosity reached
about 60-70%, no water film was formed, and thus little or no head
loss occurred.
[0045] FIGS. 3 to 6 show the results of measuring the outlet gas
concentrations and the changes in pH and alkalinity of spray water
while injecting an odor air containing 30 ppm ammonia gas and 3 ppm
hydrogen sulfide to each of plain rice husk and pellet rice husk
with a nominal residence time of 1 minute and operating the
apparatus for 140 days under the same conditions as above.
[0046] As can be seen in FIGS. 3 to 6, in the case of plain rice
husk, the outlet concentrations of ammonia and sulfide gases
increased from about 40 days after the start of the experiment, and
the odor air treatment efficiency also decreased after that time.
This is believed to be because the rice husk bed layer was settled,
a channeling phenomenon occurred in the bed layer due to the
formation of water films, and also the amount of plain rice husk
loaded in the bed was very small, and thus the pH of spray water
was rapidly lowered and the alkalinity of spray water was rapidly
exhausted.
[0047] On the contrary, because the rice husk pellets were
standardized to a given size and hard, the porosity thereof did not
change even after a long-term operation. Also, because the rice
husk pellets were compressed, they could continuously supply
alkalinity, and thus allowed odor air to be continuously treated
without lowering the pH of circulating spray wafer. In addition, it
can be seen that, if the alkalinity of spray water is exhausted, an
inorganic carbon source and an alkaline carbonate as an alkaline
supplementing agent may be provided to the spray water to improve
the odor air treatment efficiency.
[0048] As described above, the embodiment of the present invention
provides a method of preparing pellets from rice husk, including
grinding rice husk and compressing the ground rice husk with a
binder to high density. Also, the present invention an odor removal
apparatus including rice husk pellet bio-media prepared in
accordance with the method of the present invention, wherein the
rice husk pellets have uniform porosity and may contain a large
amount of water so as to function as bio-media to which
microorganisms can adhere and also wherein a high concentration of
an organic matter eluted from the rice husk pellets during water
supply serves as an alkalinity source, such that a decrease in the
pH of circulating spray water does not occur over a long period of
time, and further wherein the operating time of the apparatus can
further be extended by injection of chemicals, and an odor removal
operation may be carried out in one reactor without needing a water
bath for reduction.
[0049] While the present invention has been described with respect
to the specific embodiments, it will be apparent to those skilled
in the art that various changes and modifications may be made
without departing from the spirit and scope of the invention as
defined in the following claims.
* * * * *