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S PE C I FI CAT ION
TITLE OF THE INVENTION
A COAGULANT FOR USE OF WATER PURIFICATION AND A WATER PURIFYING
METHOD AND A WATER PURIFYING APPARATUS WITH APPLYING THE SAME
BACKGROUND OF THE INVENTION
The present invention relates to a coagulant for use of water
purification, and it also relates to a water purifying method and
a water purifying apparatus with applying the same therein.
In wastewater or sewage generated in mining of an oil field
are included a large amount of organic acid (for example, acetic
acid, valeric acid, naphthenic acid, etc.) coexisting in a crude
oil. In case of being discharged into seas or rivers, together
with such organic matters, it affects large ill influences upon
an ecological system. Accordingly, it is necessary to discharge
it after removing those organic acids from it. However, an amount
of the wastewater or sewage generated is massive, and therefore
a technology is required for processing the large amount or volume
thereof at high speed.
As a method for removing or extracting the impurity or
pollution in the wastewater, a removal or extracting method of
contaminated grains or particles suspending in water is shown in
Fig. 1. Poly aluminum chloride (so-called "PAC") or iron sulfide
is added therein, so as to form small aggregates, e.g., micro flocs
1, being approximately several tens to several hundreds mm in the
particle diameter thereof. Thereafter, with adding
polyacryl-amide therein, continuously, the contamination
particles 2 in the water are formed into large aggregates, being
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so-called a "floc" 3, approximately several hundreds to several
thousands m in the particle diameter thereof. Thereafter, this
wastewater is divided or separated by means of a filtering container
or tank, or is separated with using magnetism, after forming flocs
by adding magnetic powder or particles 4 therein, in advance, when
forming the flocs, and thereby removing them, and such methods
are already known. Also, ion sulfide may be used in the place of
PAC. With any one of those methods, it is possible to remove or
extract the contamination particles at high speed. However, it
is difficult to remove the organic acid, such as, acetic acid,
valeric acid, naphthenic acid, etc., which are dissolved in the
water.
On the other hand, it is common to remove or extract the
organic acid, with applying a method of absorbing them into active
carbon and/or an ion-exchange resin, etc. For example, in the
following Patent Document 1, there is described a method for
absorbing/removing the organic acidwith applying a contact member,
including fibrous active carbon therein. Also, as a method for
removing or extracting the impurity or pollutant in the wastewater,
for example, in the following Patent Document 2 is proposed a method
for condensing oils as aggregate, by adding water-soluble polymer
having ammonium salt structure and water-soluble anodic polymer
into drain including the oils therein, thereby to remove or extract
them therefrom.
<Prior Art Document(s)>
<Patent Document>
[Patent Document 1] Japanese Patent Laying-Open No.
2003-144839 (2003); and
[Patent Document 2] Japanese Patent Laying-Open No.
2004-255349 (2004).
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BRIEF SUMMARY OF THE INVENTION
Certain exemplary embodiments provide a coagulant for
condensing an organic acid as an aggregate with an aid of
ionic bond, comprising: a
water-soluble polymer having an
amino group; a water-soluble polymer having an acidic group;
and an inorganic salt.
Other certain exemplary embodiments provide a water
purifying method for condensing an organic acid comprising a
carboxyl group or a sulfonyl group as an aggregate with an
aid of ionic bonds and for removing the aggregate from the
water, comprising steps of: adding a water-soluble polymer
comprising an amino group to the organic acid; and
thereafter adding a water-soluble polymer comprising an
acidic group; and wherein said organic acid, said water-
soluble polymer comprising the amino group and said water-
soluble polymer comprising the acidic group satisfy the
relation of PAPBMA, where a number of the acidic groups of
said organic acid is "MA", a number of the amino groups of
said water-soluble polymer having the amino group is "PB",
and a number of the acidic groups of said water-soluble
polymer having the acidic group is "PA".
Other certain exemplary embodiments provide a water
purifying apparatus, for condensing an organic acid as an
aggregate with an aid of ionic bonds and for removing the
aggregate from the water, comprising: a first mixing tank
for mixing said organic acid and a water solution of a
water-soluble polymer comprising an amino group; a second
mixing tank for mixing a liquid within said first mixing
tank with a water solution of a water-soluble polymer
comprising an acidic group and a magnetic powder; a first
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pipe provided for said organic acid to move said organic
acid to said first mixing tank; a second pipe provided for
the liquid within said first mixing tank to move the liquid
to said second mixing tank; a third tank for storing a
mixture of the water-soluble polymer comprising the acidic
group and the magnetic powder; a third pipe for moving the
mixture from said third tank to said second mixing tank; and
a magnetic drum for separating said aggregate.
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As was mentioned above, with the method for removing or
extracting the contaminant particles with applying the coagulant,
it is suitable for processing a large amount of wastewater at high
speed, but is impossible to remove or extract the organic acid
dissolved in the water.
On the other hand, when letting the active carbon and/or
the ion-exchange resin or the like to absorb them therein, an amount
or volume of absorption is determined upon surface areas of the
active carbon and/or the ion-exchange resin. For this reason, the
smaller of the particle size, the larger of the surface areas thereof.
However, if the particle size is too small, then it is impossible
to hold the active carbon and/or the ion-exchange resin, then it
is difficult to handle them. Also, in any one of them, there is
a limit in the processing capacity thereof, and therefore it is
necessary to replace or renew the active carbon and/or the
ion-exchange resin or a reverse-penetration membrane to be applied
therein, frequently. Further, since the active carbon also absorbs
organic matters other than the organic acid, an absorbing
efficiency thereof is lowered, soon. On the other hand, the
reverse-penetrationmembrane comes to be unusable if small cavities
on a surface of the membrane are clogged with, not only the organic
acid, but also the contaminants. Accordingly, it is impossible
to process a large amount of wastewater at high speed.
As was mentioned above, with the conventional technologies,
it is difficult to remove or extract the organic acid from the
large amount of wastewater at high speed. An object of the present
invention is to remove or extract the organic acid from the large
amount of wastewater at high speed.
According to the present invention, for accomplishing the
object mentioned above, firstly there is provided a coagulant for
condensing an organic acid as an aggregate with an aid of ionic
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bond, comprising: a water-soluble polymer having an amino group;
and a water-soluble polymer having an acidic group.
Further, according to the present invention, there is also
provided a water purifying method for condensing an organic acid
as an aggregate with an aid of ionic bond, comprising the following
steps of: preparing said organic acid having a carboxyl group or
a sulfonyl group; adding a water-soluble polymer having an amino
group in said organic acid; and thereafter adding a water-soluble
polymer having an acidic group.
Further, according to the present invention, there is also
provided a water purifying apparatus, for condensing an organic
acid as an aggregate with an aid of ionic bond, comprising: a first
mixing tank for mixing said organic acid and a water solution of
water-soluble polymer having an amino group; a second mixing tank
for mixing a liquid within said first mixing tank with a water
solution of water-soluble polymer having an acidic group; a first
pipe provided for said organic acid to move to said first mixing
tank; a second pipe provided for the liquid within said first mixing
tank to move to said second mixing tank; and a filtering portion
for filtering said aggregate.
According to the present invention, it is possible to remove
or extract a large amount or volume of organic acid within the
wastewater at high speed.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
Those and other objects, features and advantages of the
present invention will become more readily apparent from the
following detailed description when taken in conjunction with the
accompanying drawings wherein:
Fig. 1 is a view for showing a conventional method for
condensing contaminant particles as aggregate;
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Fig. 2 is a view for showing scheme for forming flocs (i.e.,
aggregate), according to the present invention;
Fig. 3 is a block diagram of a water purifying apparatus,
according to an embodiment 1 of the present invention;
Fig. 4 is a block diagram of a water purifying apparatus,
according to an embodiment 2 of the present invention;
Fig. 5 is a block diagram of a water purifying apparatus,
according to an embodiment 3 of the present invention;
Fig. 6 is a block diagram of a water purifying apparatus,
according to an embodiment 4 of the present invention;
Fig. 7 is a block diagram of a water purifying apparatus,
according to an embodiment 5 of the present invention;
Fig. 8 is a block diagram of a water purifying apparatus,
according to an embodiment 6 of the present invention; and
Fig. 9 is a block diagram of a water purifying apparatus,
according to an embodiment 7 of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Hereinafter, embodiments according to the present invention
will be fully explained by referring to the attached drawings.
By referring to Fig. 2, explanation will be made on the present
invention for changing the organic acid in the wastewater into
aggregate thereof.
First of all, water-soluble polymer 6 having an amino group
is put or added into wastewater including the organic acid 5 therein.
Herein, in relation to the organic acid 5, there is one having
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a sulfonyl group. In the present invention, although the
explanation will be given only on the case where the organic acid
having a carboxyl group, but the behavior is similar to the case
where it has the sulfonyl group. With adding the water-soluble
5 polymer 6 having the amino group into the wastewater including
the organic acid therein, an ionic bond 7 is produced, being composed
of the water-soluble polymer 6 having the organic acid and the
amino group. In this manner, the organic acid 5 is trapped on the
water-soluble polymer 6 having the amino group. Herein, the amino
group of the water-soluble polymer 6, having the amino group, forms
the ionic bond at a ratio 1:1, together with the carboxyl group
within the wastewater. For this reason, it is preferable that an
amount of addition of the water-soluble polymer 6 having the amino
group, when considering it as a number of the amino groups, to
be larger than the number of the carboxyl groups in the wastewater.
Next, a solution of water-soluble polymer 8 having the
carboxyl group is added. Herein, though description is made of
the carboxyl group; however, the behavior is similar to that
mentioned below even when it has the sulfonyl group. With addition
of the water-soluble polymer 8 having the carboxyl group, an ionic
bond 9 is produced, being composed of the carboxyl group of the
water-soluble polymer 8 having the carboxyl group therein, and
the amino group of the water-soluble polymer 6 having the amino
group therein. With this, a bridge (i.e., crosslink) is built up
between the water-soluble polymer 6 having the amino group and
the water-soluble polymer 8 having the carboxyl group. With this,
this cross-linked polymer 10 can be separated from, with guiding
it to pass through a filtering tank, and as a result thereof, it
is possible to remove or extract the organic acid 5 therefrom.
With the ion-exchange resin, which is mostly applied in the
conventional art, for removing or extracting the organic acid,
in general, the organic acid is trapped on the amino group on the
surface of the resin particle, being from 0.1 to 2 mm in the particle
diameter thereof. Since the surface area of the particle is large,
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as diameter of the particle is small, therefore it can trap the
organic acidthereon, muchmore . However, the water-soluble polymer
6 having the amino group, according to the present invention, is
soluble in water. Therefore, in the similar manner to that as if
applying an ion-exchanger resin, having the particle diameter of
several angstroms, it is possible to trap the organic acid at a
high efficiency. For this reason, comparing to the case where the
conventional ion-exchanger resin therein, an amount or volume of
the organic acid becomes large, greatly, which can be trapped where
the same amount of the ion-exchanger resin is added therein.
Detailed explanation will be made below, in particular, on
the water-soluble polymer having the amino group therein. As the
water-soluble polymer having the amino group, polyethylene-imine
is suitable or preferable, judging from an aspect that the ratio
of the amino group is largest in the same molecular weight. Or,
a water-soluble polymer having the amino group in a chain, such
as, polyvinyl-amine or polyallyl-amine, etc., is also suitable
or preferable, judging from an aspect that it is relatively cheap
and can be dissolved in water easily. Chitosan is low in the
solubility in water, but since it can be obtained through hydrolysis
of chitin, i.e., the main or principle composition of the carapace
of crab, the external skeleton of a shrimp, or the external skeleton
of a living thing, such as, a beetle or a cockroach, for example,
it has a characteristic of being small of a load upon the environment,
judging from an aspect that a raw material thereof originates from
a living thing. Polylisine or polyarginine has characteristics
of originating from an amino acid and having a low toxicity.
The water-soluble polymer having the amino group generates
an odor specific to amine, when a number average molecular weight
thereof is small, even under a room temperature. In more details,
it comes to be remarkable in case where the number average molecular
weight thereof is less than 200. Then, it is preferable that the
water-soluble polymer having the amino group is equal to or greater
than 200 in the number average molecular weight thereof. Also,
.
_
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for the purpose of lowering the odor to be almost non-sensible,
it is preferable that it has the number average molecular weight
equal to or greater than 500, if possible.
On the other hand, if the number average molecular weight
is large, even a water solution thereof comes to be high in the
viscosity thereof; therefore, it is difficult to manage or control
of a casting amount thereof, and to handle it in the operation
when casting or throwing it into the wastewater. In more detail,
when the number average molecular weight thereof exceeds 1,000,000,
then the viscosity is equal to or more than 3,000 Pa=s, even if
obtaining a water solution of 10 weight%. Then, it is preferable
that the water-soluble polymer having the amino group has the number
average molecular weight equal to or less than 1,000,000. Also,
for the purpose of lowering the viscosity to be equal to or lower
than 1,000 Pa=s, even if obtaining the water solution of 10 weight%,
and thereby achieving convenience in management or control of the
casting amount thereof, or in handling of the operation when casting
it into the wastewater, it is desirable that the water-soluble
polymer having the amino group is equal to or less than 200,000
in the number average molecular weight thereof.
However, among the water-soluble polymers having the amino
group therein, it is possible to increase or improve the solubility
thereof into the water, by replacing or changing the amino group
with chlorate structure or nitrate structure, if water solubility
thereof is low. After changing into the chlorate structure or the
nitrate structure, the water-soluble polymer having the amino group
is added into the wastewater, and thereby it is possible to build
up the ionic bond together with the organic acid, efficiently.
Detailed explanation will be made below, in particular, on
the water-soluble polymer having the acidic group. It can be
considered that the water-soluble polymer having the acidic group
has the carboxyl group or the sulfonyl group, as the acidic group
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thereof. Among those, as the water-soluble polymer having the
carboxyl group, polyacrylic acid is suitable, judging from an
aspect that it is cheap and it can easily build up the ionic bond
with the amino group. Other than this, also polyasparagine acid,
polyglutamic acid, etc., coming from the amino acid, have the
characteristics of being low in the toxicity. Argine acid is a
kind of main components of a seaweed, such as, sea tangle, etc.,
for example, it has characteristics that the load upon the
environment is small in an aspect that the raw material thereof
originates from a living thing. As the water-soluble polymers
having sulfonyl group can be listed polyvinyl sulfonic acid or
polystyrene sulfonic acid. Since those sulfonyl groups are large
in acidity thereof than that of the carboxyl group, and therefore
a ratio of building up the ionic bond with the amino group, then
they are desirable or preferable from an aspect that the aggregate
thereof.
However, among those water-soluble polymers having the
acidic group, it is possible to increase or improve the solubility
into the water, by replacing or changing the acidic group with
ammonium salt structure, sodium salt structure or potassium salt
structure, if the water solubility thereof is low. After changing
into the ammonium salt structure, the sodium salt structure or
the potassium salt structure, the water-soluble polymer having
the acidic group is added into the wastewater, and thereby it is
possible to build up the ionic bond together with the water-soluble
polymer having the amino group, efficiently.
In relation with the number average molecular weight of the
water-soluble polymer having the acidic group, if it is too low,
then a number of the bridging portions of the aggregate is small,
and a stability of the aggregate goes down. Also, it shows a tendency
that the aggregate is liquefied, but to have high viscosity thereof .
With this, it is difficult to remove the aggregate through the
filtration. Then, it is desirable or preferable that the number
average molecular weight of the water-soluble polymer having the
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acidic group is equal to or greater than 2,000. Also, when
temperature of the wastewater is equal or higher than 40 C, in
particular, in the case of the number average molecular weight
is 2,000, the aggregate begins to have the viscosity. In case of
the industrial drain, there is a possibility that the temperature
thereof increases to be high, about 60 C. In this case, it is possible
to solidify the aggregate by increasing the number average
molecular weight, further, even under the high temperature. In
more details, with bringing up the number average molecular weight
to 5, 000 orhigher thanthat, it ispossible to solidifythe aggregate
even if the temperature of the wastewater is 40 C. Therefore, it
is desirable or preferable that the number average molecular weight
of the water-soluble polymer having the acidic group is equal to
or greater than 5,000. Furthermore, with bringing up the number
average molecular weight to be equal to or greater than 10,000,
it is possible to solidify the aggregate even if the temperature
of the wastewater is 60 C. Therefore, it is further desirable or
preferable that the number average molecular weight of the
water-soluble polymer having the acidic group is equal to or greater
than 10,000.
Also, if the number average molecular weight of the
water-soluble polymer having the acidic group becomes too large,
the solubility into the water is lowered down, on the way
of building up the bridge between the amino group; i.e., showing
a tendency of being separated out or deposited. Thus, this means
there is a possibility that they are separated out in the wastewater,
before building up the bridges for all of the organic acid in the
wastewater and the water-soluble polymer having the amino group,
which are connected with the ionic bond. Due to this, a part of
those combining the organic acid and the waster soluble polymer
having the amino group, being connected through the ionic bond
is remained under the condition of being melted in the wastewater.
For that reason, it is desirable that the number average molecular
weight of the water-soluble polymer having the acidic group is
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=
equal to or less than 200,000.
Explanation will be made in more detail thereof, about a
measure for increasing of the solubility of the water-soluble
polymer having the amino group or the water-soluble polymer having
the acidic group. In case where the solubility of the water-soluble
polymer having the amino group into the water is low, it is possible
to increase the solubility into the water, by changing the amino
group into the ammonium salt structure. In more detail, the
solubility into the water can be improved, greatly, with changing
it into chlorate, nitrate, or sulfate, etc., by adding hydrochloric
acid, nitric acid or sulfuric acid, etc.
Also, in case where the solubility of the water-soluble
polymer having the acidic group into the water is low, it is possible
to increase or improve the solubility into the water, with changing
the acidic group into a salt structure by strong acid. In more
details, the solubility into the water is improved, greatly, with
changing the acidic group to alkali metal salt or alkaline earth
metal salt, etc., by adding hydride of alkali metal or alkaline
earth metal, such as, sodium hydroxide, magnesium hydroxide, etc.,
for example.
Explanation will be made in more detail thereof, about an
additive for increasing trapping of organic acid. In case where
the acidity of the acidic group of the organic acid is low, a ratio
is lowered of building up the ionic bond together with the amino
group. Then, with adding an inorganic salt, such as, sodium chloride,
or potassium chloride, etc., into the wastewater, before adding
the water-soluble polymer having the acidic group, a ratio of the
organic acid, which builds up the ionic bond between the amino
group, goes up. This can be considered because an allowable ratio
of the organic acid, which can be dissolved into the wastewater,
is lowered, due to the effect similar to the salting out, i .e. ,
separating or depositing the organic matters dissolved in the water
by adding a salt. As the inorganic salt to be added can be listed
_
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the followings: a hydrochloride of alkali metal or alkaline earth
metal, such as, sodium chloride, potassium chloride, magnesium
chloride, or calcium chloride, etc.; a sulfate of alkali metal
or alkaline earth metal, such as, sodium sulfate, potassium sulfate,
magnesium sulfate, or calcium sulfate, etc.; a nitride of alkali
metal or alkaline earth metal, such as, sodium nitrate, potassium
nitrate, magnesium nitrate, or calcium nitrate, etc., for example.
Explanation will be made on an outline of an aggregating
method according to the present invention. There two (2) methods
for collecting the organic acid as the aggregate, as were mentioned
previously. Describing them in short, they are as (1) to (4) below.
Although the explanation will be made that the acidic group is
the carboxyl group in Fig. 2, but it is same to that when it is
the sulfonyl group. (1) : the water-soluble polymer having the amino
group is added into the wastewater having the organic acid therein.
(2) : The carboxyl group builds up the ionic bond with the amino
group of the water-soluble polymer having the amino group, and
the organic acid is trapped by the water-soluble polymer having
the amino group. (3) : The water-soluble polymer having the carboxyl
group is added. (4) : The amino group of the water-soluble polymer
having the amino group and the carboxyl group of the water-soluble
polymer having the carboxyl group combine each other, by a unit
of the molecule thereof, through a large number of ionic bonds,
and thereby building up the bridges. With this, those dissolving
in the water as the polymers with each other are changed to be
insoluble into the water, and come to be the aggregate.
Explanation will be made about the ratio of addition of a
coagulant. Herein, it is assumed that a number of the acidic group (s)
of the organic acid in the wastewater is "MA", a number of the
amino group (s) of the water-soluble polymer having the amino group
to be added is "PA". An adjustment is made on addition amounts
of the water-soluble polymer having the amino group and the
water-soluble polymer having the acidic group into the water, so
as to satisfy the following inequalities mentioned below, and
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thereby enabling to enhance a removal or extraction ratio of the
organic acid.
PA PB ...(Eq. 2)
PA PB 1)
The equation (Eq. 1) means that the number of the amino groups
of the water-soluble polymer having the amino group is larger than
that of the acidic groups of the organic acid in the wastewater.
According to the present invention, a reaction of building up the
ionic bond between the amino group of the water-soluble polymer
having the amino group and the acidic group of the organic acid
can be considered an equilibrium reaction, originally. For that
reason, if the amino group of the water-soluble polymer having
the amino group is too much, compared to the organic acid, it
is possible to enhance the trap ratio of the organic acid. If in
case where the equation (Eq. 1) is B<MA, since the amino group
for trapping the organic acid is less comparing to the organic
acid, then there remains the organic acid, which cannot be trapped,
in the wastewater, necessarily.
Also, the equation (Eq. 2) means that the number of the acidic
groups of the water-soluble polymer having the acidic group is
larger than the number of the amino groups of the water-soluble
polymerhaving the amino group . With this, it is possible to separate
or precipitate almost all of the water-soluble polymers having
the amino groups, each trapping the organic acid thereon, as the
aggregate insoluble in the water. If coming out from the addition
ratio of this inequality, greatly, then the water-soluble polymers,
each having the amino group trapping the organic acid dissolving
in the water, are detected as the organic matters dissolving in
the water. Accordingly, it is preferable to conduct the processing
on the wastewater at the addition ratio of this inequality, judging
from an aspect of water quality. In case where the equation (Eq.
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2) is PA<PB, no water-soluble polymer having the amino group,
trapping the organic acid thereon, is separated or deposited as
the aggregate, but staying under the condition of being dissolved
in the water, therefore there brings about a problem that the removal
or extraction ratio of the organic acid is lowered down, finally.
As was mentioned above, it is important to keep the ratio
so as to satisfy the inequalities mentioned above, for the purpose
of maintaining the removal or extraction ratio of the organic acid
in the wastewater. Also, concluding the equations (Eq. 1) and (Eq.
2) , the following equation can be obtained.
PA ?_. PB MA... (Eq. 3)
In the processing of wastewater, with conducting the process
under the condition of the equation (Eq. 2) , it is possible to
process them, but without increasing an amount of organic compounds
dissolving in the water due to the processing of waster water
according to the present invention. Also, with conducting the
process under the condition of the equation (Eq. 3) , it is possible
to remove or extract the organic acid in the wastewater with high
efficiency.
As a measure for increasing the removal or extraction of
the organic acid other than the above-mentioned, the water-soluble
polymer having the amino group should be added, as large as possible,
in an addition amount or volume thereof, when considering it to
be the number of the amino groups, more than the number of the
carboxyl groups in the wastewater. Also, when adding a solution
of the water-soluble polymer having the acidic group into the
wastewater, with agitating or stirring them as hard as possible,
the water-soluble polymer having the acidic group can be spread
in the entire of the wastewater; i.e., it is possible to form or
build up the aggregate with superior efficiency. Accordingly, with
an enhancement of the agitation condition when adding the
water-soluble polymer having the acidic group, an improvement is
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made of the removal or extraction ratio of the organic acid.
Other method for enhancing the removal or extraction ratio
of the organic acid, there can be listed up a method of adding
an inorganic salt into the wastewater, before adding the
water-soluble polymer having the acidic group therein. This can
be considered that the removal or extraction ratio is enhanced
due to the effect similar to the salting out. The inorganic salt
to be added is, preferably, sodium chloride existing abundantly
in the nature. This is suitable or, in particular, in case when
processing the wastewater in a submarine oil field, since the
averaged concentration of sodium chloride of the seawater is about
3%, and if adding the salt up to that level, an ill influence is
slight or insignificant, which is affected upon the environment.
As an order of adding the inorganic salt, it may be done before
or after addition of the water-soluble polymer having the amino
group, or may be added the organic salt m to the coagulant, for
the purpose of accelerating the aggregation effect thereof. However,
it must be added, necessarily, before addition of the water-soluble
polymer having the acidic group. This is because the aggregation
will not occur more than that if adding the water-soluble polymer
having the acidic group therein.
Explanation will be given about large-growing of the
aggregate. As was mentioned previously, when adding the water
solution of the water-soluble polymer having the acidic group,
the organic acid can be trapped on the aggregate, effectively,
if agitating or stirring it as hard as possible. However, if the
agitation is too hard, the size of the aggregate becomes too
small, and it clogs easily when passing through the filtering
tank. Then, after building up the aggregate, poly aluminum chloride
or polyacryl amide is added, thereby growing up the aggregate,
to be large in size thereof. This brings about an improvement or
increase of the filtering speed of the filtering tank, and in its
turn, it results in an improvement or increase of processing
of the wastewater.
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Explanation will be given about an application of magnetic
separation. With containing magnetic powder or iron powder
therein when forming or building up the aggregate, it is
possible to remove the aggregate with an aid of magnetic
separation. However, it is difficult to put the magnetic powder
or the iron powder into the aggregate after adding the water-soluble
polymer having the acidic group. Accordingly, by adding the magnetic
powder or iron powder, before adding the water-soluble polymer having
the acidic group therein, or mixing with the water-soluble polymer
having the acidic group, into the wastewater, it can be contained
within the aggregate. However, for the purpose of large-growing of the
aggregate, there may be a case where polyaluminum chloride and
polyacryl amide may be added therein. In this case, even after adding
the water-soluble polymer having the acidic group, it is possible to
separate the aggregate through the magnetic separation by adding the
magnetic powder or the iron powder before adding the polyacryl
amide therein.
(1) Embodiment 1 of water purifying apparatus of the present
invention
Next, explanation will be made on an embodiment of the water
purifying apparatus, according to the present invention. First
of all, explanation will be made on the basic or fundamental
structure of the water purifying apparatus according to the present
invention, by referring to Fig. 3. Wastewater is cast into a first
mixing tank 13, with an aid of a pump 11, passing through a pipe
12. The liquid therein is agitated or stirred bymeans of an overhead
stirrer 14. With using a pump 16, a water solution of the
water-soluble polymer having the amino group is cast into the first
mixing tank 13, from a tank 15 and passing through a pipe 17.
After mixing up the liquid in the first mixing tank 13, the
liquid in the first mixing tank 13 is cast into a second mixing
tank 20, with using a pump 18 and passing through a pipe 19. The
liquid in the second mixing tank 20 was already agitated or stirred
CA 02689716 2012-03-08
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by an overhead stirrer 21.
Next, a water solution of the water-soluble polymer having
the acidic group is cast into the second mixing tank 20, with using
a pump 23 and passing through a pipe 24. With this, aggregate is
produced in the second mixing tank 20 . The liquid under the condition
of mixing the aggregate therein flows or rushes into a filtering
portion 26a or a filtering portion 26b, by opening a valve 25a
or a valve 25b. The liquid flowing therein is filtered within a
filtering tank 27a or a filtering tank 27b, each being made of
sand for use of filtration, and thereafter it is filtered, again,
by means of a porous member 28a or a porous member 28b, and thereby
coming out as a water reduced of the organic acid thereof.
In Fig. 3 is shown an apparatus having the filtering portion
26a and the filtering portion 26b. In beginning, filtering
processing is conducted in the filtering portion 26a, and if in
the filtering tank 27a is clogged and the filtering speed is lowered
down, then the filtering processing is conducted within the
filtering portion 26b. With exchanging the filtering tank 27a,
etc., during the filtering processing within the filtering portion
26b, it is possible reduce retardation of the filtering process,
as small as possible.
By the way, when the capacity is low of removing the organic
acid, a water solution of sodium chloride is cast into the first
mixing tank 13, with an aid of a pump 30, from a tank 29 passing
through a pipe 31. With this, the ratio of the organic acid trapping
on the amino group comes to be large, and thereby improving or
increasing the capacity of removing or extracting the organic acid.
In the place of the sodium chloride may be used other organic salt,
such as, potassium chloride, etc. In case of discharging the water
purified within the water purifying apparatus into the sea water,
since the sea water is salt water, it is desirable to use the sodium
chloride since the ill influences affected on an ecosystem is slight
or insignificant.
CA 02689716 2012-03-08
-18-
A tip 32a of the pipe 24 for casting the water solution of the
water-soluble polymer having the acidic group into the second tank
is made up, not straight, but to be widened like a fan, or widened
like a showerhead, etc., so that the water solution of the
water-soluble polymer having the acidic group can be cast into
the second mixing tank 20 within an extent, as wide as possible.
This is because, since the aggregation starts, simultaneously,
accompanying the cast of the water solution of the water-soluble
polymer having the acidic group, if it is cast within a narrow
area, the water solution of the water-soluble polymer having the
acidic group, which is cast, is contained within the aggregate,
and therefore it is not practically used for further producing
the aggregation. As to the tip 32a of the pipe 24 and the tip 32b
of the pipe 19, for casting the liquid into the second mixing tank
20, ports for casting liquid are provided above a surface of the
liquid, so that they do not contact with that liquid surface. This
is for the purpose of preventing holes or openings at the tip from
being clogged or blocked, with adhesion of the aggregate, which
is produced within the second mixing tank 20, at the tip 32a of
the pipe 24 and at the tip 32b of the pipe 19.
(2) Embodiment 2 of water purifying apparatus of the present
invention
Explanation will be given on the basic or fundamental
structure of one, having a sedimentation tank, among the water
purifying apparatuses according to the present invention, by
referring to Fig. 4. The structure of the apparatus shown in Fig.
4 has a sedimentation tank 33 therein. With such structure, the
aggregate is settled down or precipitated on a lower portion of
the sedimentation tank, and thereby obtaining a top or supernatant
liquid can be obtained as purified water.
(3) Embodiment 3 of water purifying apparatus of the present
invention
CA 02689716 2012-03-08
-19-
Explanation will be given on the basic or fundamental
structure of one, having a mechanism for protecting the filtering
tank from clogging, at the filtering portion thereof, among the
water purifying apparatuses according to the present invention,
by referring to Fig. 5. Continuing the filtering process, the
filtering tank 27 causes clog on a surface thereof, due to the
aggregate, and the filtering speed is lowered down, gradually.
Then, within the apparatus shown in Fig. 5, in vicinity of an upper
surface of the filtering tank 27 is disposed a disc having
concave/convex on the surface thereof, and for rotating this by
a motor, there is provided a filtering tank stirrer mechanism 34.
With this, an upper surface of the filtering tank 27 is cut off,
so as to dissolve the clog with the aggregate, and thereby enabling
a smooth filtration.
(4) Embodiment 4 of water purifying apparatus of the present
invention
Explanation will be given on the basic or fundamental
structure of one, utilizing the magnetic separationmethod therein,
among the water purifying apparatuses according to the present
invention, by referring to Fig. 6. The wastewater is cast into
a first mixing tank 37, with an aid of a pump 36, passing through
a pipe 35. The liquid in this is agitated by means of an overhead
stirrer 38. Herein, with an aid of a pump 40, the water solution
of the water-soluble polymer having the amino group is cast into
the first mixing tank 37, from a tank 39 passing through a pipe
41.
After fully mixing up the liquid in the first mixing tank
37, with using a pump 42, the liquid in the first mixing tank 37
is cast into a second mixing tank 44, passing through a pipe 43.
The liquid in this was already agitated, by means of an overhead
stirrer 45.
Next, from a tank 46, by means of a pump 47, a liquid mixed
CA 02689716 2012-03-08
. -20-
up with the water solution of the water-soluble polymer having
the acidic group and the magnetic powder is cast into the second mixing
tank 44, passing through a pipe 48. With this, aggregate is produced
in the second mixing tank 44. The aggregate is in the condition
of mixed up with the magnetic powder. This aggregate adheres on a
drum 49, having a mesh-like surface and being magnetized. The drum
49 rotates in the clock-wise direction in Fig. 6, and the aggregate
adhering on the surface thereof is stripped out from the mesh of
the drum 49 by means of a scraper 50. The aggregate stripped out
is collected in an aggregate collecting container 51 having a lower
surface mesh-liked. Since the aggregate just after being collected
includes water, well enough, then the water is discharged from
the mesh of the lower surface of the aggregate collecting container.
On the other hand, the water passing through the mesh of
the drum 49 is in the condition of being removed or extracted from
the aggregate by the mesh. This water comes out as the water reduced
in the impurity thereof, passing through a pipe lying at a center
portion of the drum 49.
In case where the capacity is low of removing or extracting
the organic acid, with an aid of a pump 54, a water solution of
the sodium chloride is put into the first mixing tank 37, from
a tank 53 passing through a pipe 55. With this, the radio of the
organic acid trapping on the amino group comes to be large, and
thereby improving or increasing the capacity of removing or
extracting the organic acid. In the place of the sodium chloride
may be used other organic salt, such as, potassium chloride, etc.
In case of discharging the water purified within the water purifying
apparatus into the sea water, since the sea water is salt water,
it is desirable to use the sodium chloride from an aspect that
the ill influences affected on an ecosystem is slight or
insignificant.
A tip 56a of the pipe 48, for casting the water solution of
the water-soluble polymer having the acidic group into the second
CA 02689716 2012-03-08
. -21-
tank, is made up to be widened like a fan, or widened like a showerhead,
etc . , so that the water solution of the water-soluble polymer having
the acidic group can be cast into the second mixing tank 44 within
an extent, as wide as possible. This is because, since the
aggregation starts, simultaneously, accompanying the cast of the
water solution of the water-soluble polymer having the acidic group,
if it is cast within a narrow area, the water solution of the
water-soluble polymer having the acidic group, which is cast, is
contained within the aggregate, and therefore it is not practically
used for further producing the aggregation.
As to the tip 56a of the pipe 48 and the tip 56b of the pipe
43, for casting the liquid into the second mixing tank 44, ports
for casting liquid are provided above a surface of the liquid,
so that they do not contact with that liquid surface. This is for
the purpose of preventing holes or openings at the tip from being
clogged or blocked, with adhesion of the aggregate, which is
produced within the second mixing tank 44, at the tip 56a of the
pipe 48 and at the tip 56b of the pipe 43.
Within the tank 46 is provided an overhead stirrer 57 (an
impeller, etc., provided in the tank is not illustrated) , for mixing
the water solution of the water-soluble polymer having the acidic
group and the magnetic powder therewith.
Further, the water solution of the water-soluble polymer
having the acidic group and the magnetic powder can be put into the
second mixing tank 44, separately. However, because of a tendency
of generating a deviation or offset in density of the magnetic powder
contained in the aggregate per a unit of volume, it is desirable
to put it into the second mixing tank 44, in advance, after mixing
thereof, as is done in the present apparatus.
In this apparatus, without provision of the drum 49 for
conducting the magnetic separation, but a mechanismmay be provided
for filtering the aggregate, after the sedimentation thereof. Since
-
CA 02689716 2012-03-08
-22-
the aggregate contains the magnetic powder therein, and then a
specific gravity thereof is large, therefore it can settle down
easily. Then, bringing almost all of the aggregate to settle down on
the lower of the secondmixing tank 44, and filtering the supernatant
liquid thereof, the purification of water can be made without
conducting the magnetic separation therein.
(5) Embodiment 5 of water purifying apparatus of the present
invention
Explanation will be given on the basic or fundamental
structure of one, applying a magnetic separation method and
comparing two (2) sets of drums therein, among the water purifying
apparatuses according to the present invention, by referring to
Fig. 7. In this apparatus, after collecting the aggregate on the
drum 49, made to be mesh-like on the surface thereof, a small amount
or volume of water comes out from an inside of the drum. With this,
the aggregate is stripped out from the mesh surface of the drum
49, directed to a drum 58, and thereby adhering on the surface
of the drum 58. The surface of this drum 58 is made of a metal
plate, but not mesh surface. When stripping out the aggregate
therefrom, the mesh surface is scraped out by a scraper 50, but
at this time, there is a possibility that the scraper is caught
on the mesh, and thereby damaging the mesh. However, within the
present apparatus, when stripping out the aggregate by the scraper
50, since that contacting on the mesh is the metal plate being
strong compared to the mesh, and therefore such damage will be
hardly caused by the scraper 50; i.e., it is preferable or suitable.
(6) Embodiment 6 of water purifying apparatus of the present
invention
Explanation will be given on the basic or fundamental
structure of one, applying a magnetic separation method and
providing an aggregate removal tank 59 separately, among the water
purifying apparatuses according to the present invention, by
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referring to Fig. 8. In this, the aggregate building up in the
second mixing tank 44, not being magnetically separated in the
same tank, but is moved to another tank (i.e., the aggregate removal
tank 59), wherein the magnetic separation thereof is conducted.
An amount or volume of processing water put into the aggregate
removal tank 59 is controlled by means of a valve 60. With applying
such structure, before the magnetic separation, a considerable
ratio of the aggregate remains in the second mixing tank 44, then
an amount or volume of the aggregate to be removed through the
magnetic separation comes to be small. For this reason, clogging
hardly occurs on the mesh of the drum 49, and reduction can be
achieved on maintenance of the mesh, and therefore is preferable
or suitable.
(7) Embodiment 7 of water purifying apparatus of the present
invention
Explanation will be given on the basic or fundamental
structure of one, applying a magnetic separation method and
providing one (1) set of drum and an aggregate removal tank 61
separately, among the water purifying apparatuses according to
the present invention, by referring to Fig. 9. In this, bringing
the distance to be short between a bottom of the aggregate removal
tank 61 and the drum causes the aggregate to adhere on the drum
58, almost completely. In this manner, purification is conducted
with using only one (1) set of drum. The aggregate adhering on
the drum 58 is stripped out by means of the scraper 50. With this
method, since the purification can be done with using only one
(1) set of drum 58, and thereby achieving space saving of the
aggregate removal tank 61, and in its turn, of the apparatus,
therefore being preferable or suitable.
Examples of the present invention will be shown below.
<Example 1>
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During the time when agitating one (1) liter of test water
dissolving benzoic acid therein, as the organic acid, at 110 ppm
(1 mmol as benzoic acid), 1 g of a water solution at 10 weight%
of polyethylene-imine (the number average molecular weight is
70,000) is added therein (2.33 mmol as the number of amino groups) ,
as the water-soluble polymer having the amino group. Next, when
adding 2 g of a water solution at 10 weight% of polyacrylate (the
number average molecular weight is 25,000) , as the water-soluble
polymer having the carboxyl group (2.78 mmol as the number of
carboxyl groups), then an aggregate deposits or separates out.
Obtaining this aggregate through filtration, and when measuring
an amount of benzoic acid in the filtered liquid with using a liquid
chromatography, the concentration of benzoic acid goes down to
10 ppm in the filtered liquid. Therefore, it is confirmed that
the organic acid dissolving in the water can be removed or extracted,
with using the water-soluble polymer having the amino group and
the water-soluble polymer having the carboxyl group.
<Example 2>
Trying a test similar to that of the Example 1, but except
for using one (1) liter of test water dissolving acetic acid therein,
at 60 ppm, in the place of one (1) liter of test water dissolving
benzoic acid therein, at 110 ppm, then the concentration of acetic
acid goes down to 8 ppm in the filtered liquid. Therefore, it is
confirmed that the organic acid dissolving in the water can be
removed or extracted, with using the water-soluble polymer having
the amino group and the water-soluble polymer having the carboxyl
group.
<Example 3>
Trying a test similar to that of the Example 1, but except
for using 1.2 g of water solution of polyallylamine (the number
average molecular weight is 10,000) at 10 weight% (2.16 mmol as
the number of amino groups) , in the place of 1 g of the water solution
CA 02689716 2012-03-08
. -25-
of polyethyleneimine (the number average molecular weight is
70,000) at 10 weight% , then the concentration of benzoic acid goes
down to 11 ppm in the filtered liquid. Therefore, it is confirmed
that the organic acid dissolving in the water can be removed or
extracted, with using the water-soluble polymer having the amino
group and the water-soluble polymer having the carboxyl group.
<Example 4>
Trying a test similar to that of the Example 3, but except
for using 2 g of water solution of polyallylamine chlorate (the
number average molecular weight is 10,000) at 10 weight% (2.14
mmol as the number of structures of changing from the amino group
into the chlorate), in the place of 1.2 g of the water solution
of polyallylamine (the number average molecular weight is 10,000),
and using 3 g of sodium polyacrylate (3.16 mmol as the number of
structures of changing from the carboxyl groups to sodium salt),
in the place of 2 g of water solution polyacrylate (the number
average molecular weight is 25,000) at 10 weight%, then the
concentration of benzoic acid goes down to 12 ppm in the filtered
liquid. Therefore, it is confirmed that the organic acid dissolving
in the water can be removed or extracted, with using the
water-soluble polymer having the amino group and the carboxyl group,
which are changed to the salt structures thereof.
<Example 5>
Trying a test similar to that of the Example 4, but except
for using 3 g of water solution of sodium polymethacrylate at 10
weight% (2.75 mmol as the number of structures of changing from
the carboxyl groups to sodium salt), in the place of 3 g of the
water solution of sodium polyacrylate at 10 weight%,
polyallylamine (the number average molecular weight is 10,000),
then the concentration of benzoic acid goes down to 12 ppm in the
filtered liquid. Therefore, it is confirmed that the organic acid
dissolving in the water can be removed or extracted, with using
-
CA 02689716 2012-03-08
= -26-
the polymethacrylate in the place of the polyacrylate.
<Example 6>
Trying a test similar to that of the Example 4, but except
for using 6 g of water solution of sodium polystyrene sulfo at
10 weight% (2. 91 mmol as the number of structures of changing from
the sulfonyl group to sodium salt), in the place of 3 g of the
water solution of sodium polyacrylate at 10 weight%, then the
concentration of benzoic acid goes down to 12 ppm in the filtered
liquid. Therefore, it can be confirmed that the organic acid
dissolving in the water can be removed or extracted, with using
the water solution having the sulfonyl group as the water-soluble
polymer having the acidic group.
<Example 7>
Trying a test similar to that of the Example 1, but except
for adding a water solution of sodium chloride at 5.83 weight%,
after adding a water solution of polyethyleneimine, but before
adding the water solution of polyacrylate at 10 weight%, then the
concentration of benzoic acid goes down to 8 ppm in the filtered
liquid. Therefore, it is confirmedthat the organic aciddissolving
in the water can be further reduced, by adding sodium chloride,
comparing to the case of not adding it therein.
<Example 8>
Trying a test similar to that of the Example 7, but except
for changing the addition amount or volume of sodium chloride at
5.85 weight%, from 1 g to 10 g, then the concentration of benzoic
acid goes down to 4 ppm in the filtered liquid. Furthermore, trying
a test similar to that of the Example 7, but except for changing
the addition amount or volume of sodium chloride at 5.85 weight%,
from 1 g to 100 g, then the concentration of benzoic acid goes
down to 2 ppm in the filtered liquid. Therefore, it is confirmed
CA 02689716 2012-03-08
-27-
that the organic acid dissolving in the water can be further reduced,
by enlarging an amount or volume of sodium chloride to be added.
<Example 9>
Trying a test similar to that of the Example 7, but except
for using 1 g of a water solution of potassium chloride at 7.45
weight%, in the place of 1 g of water solution of sodium chloride
at 5.85 weight%, then the concentration of benzoic acid goes down
to 8 ppm in the filtered liquid. Also, trying a test similar to
that of the Example 7, but except for using 2 g of a water solution
of sulfate of magnesia at 6 weight%, in the place of 1 g of the
water solution of sodium chloride at 5.85 weight%, then the
concentration of benzoic acid goes down to 6 ppm in the filtered
liquid. Therefore, it is confirmed that the organic acid dissolving
in the water can be further reduced, by adding various kinds of
inorganic salts therein.
<Example 10>
During the time when agitating one (1) liter of test water
dissolving benzoic acid therein, as the organic acid, at 110 ppm
(1 mmol as benzoic acid), a water solution of polyethyleneimine
(the number average molecular weight is 70,000) at 10 weight% is
added as the water-soluble polymer having the amino group, by an
amount or volume shown in Table 1 . Next, as the water-soluble polymer
having the carboxyl group, 2g of a water solution of polyacrylate
(the number average molecular weight is 25,000) at 10 weight% (2.78
mutol as the number of the carboxyl groups), then an aggregate deposits
or separates out. Obtaining this aggregate through filtration,
and when measuring an amount of benzoic acid in the filtered liquid
with using a liquid chromatography, the concentrations of benzoic
acid in the filtered liquids result as shown in the Table 1.
CA 02689716 2012-03-08
= -28-
TABLE 1
Addition amount or volume of water solution Concentration (ppm)
of polyethylene-imine at 10 weight% of benzoic acid in
test water
Weight (g) Number of amino
groups (mmol)
0.30 0.70 48
0.40 0.93 22
0.43 1.00 15
0.50 1.12 14
0.70 1.63 12
1.00 2.33 10
From this result, it is confirmed that, in the relationship
between the number of the acidic groups (MA) in the wastewater
and the number of the amino groups (PB) of the water-soluble polymer
having the amino group, the removal or extraction ratio of the
organic acid is low when PB<MA. Thus, it is confirmed that, as
is the inequality of the equation (Eq. 1) mentioned above, the
removal or extraction ratio of the organic acid can be improved
by brining the number of the amino group (PB) in the wastewater
and the number of the amino groups to be equal to or greater than
the number of the acidic groups (MA) in the wastewater, i.e., PB
> MA.
The ionic bond between the acidic group of the organic acid
and the amino group of the water-soluble polymer having the amino
group can be an equilibrium reaction. For this reason, it can be
considered that an excess of the amino groups increases an amount
of traps (i.e., the number of the ionic bonds) .
<Example 11>
During the time when agitating one (1) liter of test water
CA 02689716 2012-03-08
. -29-
dissolving benzoic acid therein, as the organic acid, at 110 ppm
(1 mmol as benzoic acid) , 1 g of a water solution of
polyethylene-imine (the average molecular weight is 70,000) at
weight% is added as the water-soluble polymer having the amino
5
group (2.33 mmol as the number of amino groups) . Next, as the
water-soluble polymer having the carboxyl group, the water solution
of polyacrylate (the number average molecular weight is 25,000)
at 10 weight% is added, by an amount or volume shown in a Table
2, then an aggregate deposits or separates out. Obtaining this
10 aggregate through filtration, and when measuring an amount of
benzoic acid in the filtered liquid with using a liquid
chromatography, the concentrations of benzoic acid in the filtered
liquids result as shown in the Table 2.
TABLE 2
Addition amount or volume of water solution Concentration (ppm)
of polyacrylate at 10 weight% of benzoic acid in
test water
Weight (g) Number of carboxyl
groups (mmol)
1.40 1.94 82
1.60 2.22 36
1.66 2.32 18
1.68 2.33 12
1.70 2.36 12
2.00 2.78 10
3.00 4.17 9
From this result, it is confirmed that, in the relationship
between the number of the amino groups (PB) of the water-soluble
polymer having the amino group, and the number (PA) of the acidic
groups of the water-soluble polymer having the acidic group, the
removal or extraction ratio of the organic acid is low when PA<PB.
Thus, for the purpose of increasing or heightening the removal
CA 02689716 2012-03-08
. -30-
or extraction ratio of the organic acid, it is important that PA>PB.
A reason of this can be considered that, when PA<PB, the
water-soluble polymer having the amino group, which traps the
organic acid, does not separate out as an aggregate, and it remains
in the wastewater under the condition of dissolving therein;
therefore, the organic acid cannot be removed or extracted, fully,
through the filtration, and as a result thereof, the removal or
extraction ratio of the organic acid is lowered.
<Example 12>
Trying a test similar to that of the Example 1, but except
for selecting the number average molecular weight of polyacrylate,
not 25,000, but to be 800, 1,600, 2,000 or 3,000. Then, in case
of applying polyacrylate of 800 and 1,600 in the number average
molecular weight thereof, the aggregate comes to be liquid-like,
and when being filtered, it sticks or adheres on surface of a filter
paper, spreading thereon, and then it clogs the meshes of the filter
paper, soon. Then, filtration is conducted with using a plural
number of filter papers. In case of applying polyacrylate of 2,000
and 3,000 in the number average molecular weight thereof, the
aggregate comes to be solid-like, then the meshes of the filter
paper is hardly clogged therewith. Therefore, it is preferable
or desirable that the number average molecular weight of
polyacrylate, which is added when forming or building up the
aggregate, is equal to or greater than 2,000.
Also, trying a test similar to that of the Example 1, but
except for selecting the number average molecular weight of
polyacrylate, not 25,000, but to be 100,000, 200,000 or 1,000,000.
Then, in case of applying polyacrylate of 100,000 and 200,000 in
the number average molecular weight thereof, 2 g of water solution
at 10 weight% thereof is added, and the aggregate produced is
filtered, and then measurement is made upon the concentration of
benzoic acid in the filtered liquid, then it is 10 ppm. On the
contrary thereto, when applying the same amount of polyacrylate
CA 02689716 2012-03-08
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of 250,000 and 1,000,000 in the number average molecular weight
thereof, then the concentrations of benzoic acid in the filtered
liquid are 30 ppm and 80 ppm, respectively. Further, when the number
average molecular weight is heightened, then the water solution
thereof comes tobehigh intheviscositythereof, andit is difficult
to control an addition amount or volume thereof. Then, 10 g of
a water solution is applied by each, at 2 weight% of polyacrylate
of 250,000 and 1,000,000 in the number average molecular weight
thereof.
Next, when increasing an amount or volume of polyacrylate
to be added, up to two (2) times for that of 250,000 in the number
average molecular weight thereof, and up to four (4) times for
that of 1,000,000 in the number average molecular weight thereof,
then concentration of benzoic acid in the filtered liquid goes
down to 10 ppm in both cases. This can be considered that the
polyacrylate, when the number average molecular weight thereof
comes to be large, only builds up the ionic bonds with the amino
groups of polyethylene-imine, and has a tendency of building up
an aggregate being insoluble in water. For that reason, it is
considered that, comparing to the cases when adding polyacrylate
being small in the number average molecular weight thereof (the
number average molecular weight is 25,000, 100,000 or 200,000),
a relatively large proportion of the ionic bonds made of
polyethylene-imine andbenzoicacidis remained under the condition
of dissolving in the water, and as a result thereof, the removal
or extraction ratio of benzoic acid is heightened.
From the above, in an aspect that a quantity of using the
water-soluble polymer having the acidic group can be reduced when
building up the aggregate, determination can bemade that the number
average molecular weight of the water-soluble polymer having the
acidic group be equal to 200,000 or less than that, preferably
or desirably. Concluding the above, from the present example, it
is shown that the number average molecular weight of the
water-solublepolymerhavingthe acidic group be applied, according
CA 02689716 2012-03-08
. -32-
to the present invention, is 2,000 to 200,000, preferably or
desirably.
<Example 13>
In the embodiment 1, when adding the water solution of
polyacrylate at 10 weight%, agitation is made with using the
overhead stirrer, and the rotation speed at that time is set at
200 rpm. Then, size of the aggregate produced is about 1 to 3mm.
Therefore, in the present example, the rotation speed of the
overhead stirrer is changed to 500 rpm, then the size of the aggregate
produced comes down to 0.01 to 0.3 mm, and large in dispersion
of the particle diameter thereof. For that reason, this can easily
clog meshes of filter papers, having various kinds mesh sizes;
therefore, an efficiency of the process is lowered down.
Then, 1.5 g of water solution of polyaluminum chloride (PAC)
at 1 weight% is added in the test water, in which the fine particles
are produced, when condensing corruption particles into the large
aggregate thereof, and after agitation thereof, 1 g of water
solution of polyacryleamide at 0.1 weight%, and further it is
continued to be agitated under the condition of lowering the
rotation speed of the overhead stirrer down to 200 rpm, then the
aggregate becomes large, such as, 1 to 3 mm in size thereof.
Since the aggregate becomes large, filtration of the aggregate
with using the filter paper can be conducted, easily, with hardly
clogging the mesh of the filter paper. Therefore, in case where
the aggregate is small, it is possible to enlarge the size of the
aggregate with adding polyaluminum chloride and polyacryleamide
therein, to be filtered easily.
<Example 14>
In the example 1, 100 mg of magnetic powder of ferrite group
is added into the test water before adding the water solution of
polyacrylate. Thereafter, a water solution of polyacrylate is added
-
CA 02689716 2012-03-08
-33-
and after the aggregate is produced therein, a permanent magnet
is put into the test water and then is lifted up after passing
30 seconds, then about 90% of the aggregate adheres on the magnet
surface. The remaining sticks on a surface of the overhead
stirrer, which is dipped in the test water. The concentration of
benzoic acid is 10 ppm. From the above, it is confirmed that the
organic acid can be removed or extracted from the test water without
conducting the filtration, but with using the magnetic powder and
the permanent magnet.
<Example 15>
Trying a test similar to the example 14, but except for
applying a half of magnetic powder, i.e., 50 mg, then the aggregate
about 50% of the entire thereof attaches on the magnetic powder is.
About 40% of the aggregate, not attach on the magnet, but drifts
in the test water. Namely, it indicates that an amount or volume
of the magnetic powder is insufficient for removing or extracting
the aggregate in this method. However, in case where the magnetic
powder is added into the test water after mixing the magnetic
powder with the water solution of polyacrylate, i.e., adding the
polyacrylate and the magnetic powder at the same time, 90% of the
entire aggregate attaches on the magnetic powder. Also, after
processing the test water with this method, the concentration of
benzoic acid goes down 10 ppm. From the above, it is shown that
the necessary amount or volume of the magnetic powder can be
reduced, by adding the magnetic powder and the water-soluble
polymer having the acidic group, simultaneously, when adding the
magnetic powder into the test water.
Compared to the test water and the water solution of
polyacrylate, because the specific gravity of the magnetic powder
is large, it hardly exists or breaks up in the test water, uniformly,
even if increasing the agitation speed for the test water. For
this reason, the ratio of the magnetic powder contained within the
aggregate can easily differ from, depending upon that aggregate.
CA 02689716 2012-03-08
, -34-
Then, it can be considered that the magnetic powder is contained
almost in uniform, with respect to the aggregate produced, by
adding the magnetic powder together with the water solution of
polyacrylate, and as a result thereof, the aggregate can attach
on the magnet with a small amount or volume of magnetic powder.
