JPS5829159B2 - Tennen Suino Seichiyouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved method for reducing turbidity in natural raw or natural waters.

More particularly, the present invention relates to a method for reducing turbidity in natural waters by treatment with a polyquaternary coagulant, such as when at least a portion of the turbidity is associated with very fine suspended particles.

Coagulation is an operation that removes solids present in an aqueous dispersion.

Aqueous dispersion refers to a system in which solid particles are dispersed in water forming a continuous phase, and refers to a wide range of systems in which the size and composition of the dispersed particles vary.

Natural water is water from rivers, lakes, reservoirs and similar natural sources that is used for various purposes.

Most of these waters have a turbidity due to solids suspended in them and require some treatment before use.

Generally speaking, the ideal coagulant is one that mixes easily with the suspension to be treated, causes rapid aggregation of suspended solid particles to form flocs, and results in rapid settling of the resulting flocs. It is.

An ideal coagulant with such properties would be able to rapidly process large quantities of aqueous suspensions in a highly effective manner.

The coagulants that have been developed for industrial use until recently are far from what can be called ideal coagulants.

A recent development in the coagulant field is the development of high molecular weight quaternary coagulants.

These polyquaternary coagulants are more effective than conventional coagulants and have performance close to that of ideal coagulants.

In industrial applications, these high molecular weight polyquaternary coagulants have been used effectively to treat a variety of natural waters, industrial wastewaters, and municipal wastewaters.

Such high molecular weight polyquaternary coagulants have shown good performance in special applications such as dewatering of sewage sludge.

A convenient laboratory method for comparatively evaluating the efficiency of various coagulants is the use of kaolin clay suspensions.

When properly prepared, these suspensions closely resemble many natural waters.

Laboratory tests using kaolin clay suspensions have shown that efficiency increases with increasing molecular weight of the polyquaternary coagulant.

Despite the many advantages exhibited by high molecular weight polyquaternary coagulants, the degree of clarification is less than desired when using the coagulants to clarify a variety of natural waters. is found.

Many modifications to processing methods and equipment have been introduced to improve performance.

These changes have complicated the clarification process, but still it has not been possible to achieve the desired high degree of clarification with high molecular weight polyquaternary coagulants.

There is therefore a wide need for improved methods that can be applied to natural waters of this type to achieve the desired degree of clarification.

The improved process provided by the present invention is for the clarification of natural waters containing suspended solids, wherein a portion of the suspended solids has a diameter ranging from 0.09 to 1.5 millimeters, In colloidal particles, the natural water has J , T , U of about 4 to 250 or more.

At least 0.5 J, T, U of the total turbidity in the range of (Jackson turbidity units) is due to this suspended solids.

J, T, and U were used here as turbidity units. The ASTM Handbook on Industrial Water and Industrial Wastewater (ASTM
manual on IndustrialWater
and Industrial WasteWat
er), 2nd edition, 1964, page 118, in which it is specifically stated that turbidity can be measured by using a Jackson candle turbidimeter.

This turbidity meter consists of a glass tube with a scale, a standard candle, and a support for these. Water is poured into the tube until the image of the candle's flame is no longer visible, and the turbidity is determined from the depth of the water at that point.

It can be directly converted into turbidity units using the table usually attached to the equipment.

The Jakun water turbidity meter is commercially available from various sources, and is also listed in the American Scientific Products Catalog 1981-1982, page 1019.

The method of the present invention provides a polyquaternary compound in which the cation component weight of the polyquaternary compound is 37% by weight in an aqueous solution and the viscosity of the solution is about 40 to 150 centistokes at 25°C. Add an effective amount of coagulant to natural water,
Mixing until an initial floc is formed that remains suspended in the water; Allowing to remain suspended in water: A method consisting of subsequent settling of the settleable flocs together with the colloidal particles adsorbed thereon.

When the method of the present invention is used to clarify natural water as described above, it is possible to obtain greater clarity than when using a polyquaternary coagulant with a high viscosity under the same measurement conditions. This can be determined by measuring.

This is extremely surprising and completely unexpected.

Thus, the process of the present invention, when applied to the natural waters specified above, provides purified water that is clearer and has less suspended solids than conventional processes.

It is not known for certain why it is observed that the use of low molecular weight polymers exhibits a better clarification effect, and the applicant does not wish to be bound by any theory. However, the high molecular weight polyquaternary coagulant is probably unable to effectively induce coagulation of the colloidal suspended fine particles due to its rapid coagulation, and therefore has an effect comparable to that of the coagulant of the present invention. It is considered that it cannot be done.

In order to carry out the method of the invention, J, T, U in the range of about 4 to 250 as the natural water to be treated.

and at least about 0.5 of its turbidity, more typically 0.5 to 10 J, and T-U- has a diameter of about 0.09 to 1
．． 5□ It is necessary to choose one related to the suspended colloidal particles of Limicron.

Not all natural waters meet this requirement, and therefore the method of the present invention is not necessarily applicable to all natural waters.

There are several ways to determine specific properties of natural waters.

One detailed method consists of measuring the particle size of suspended solid particles and determining the contribution that particles of various sizes make to water turbidity.

A convenient method is to clarify the water using conventional high molecular weight polyquaternary coagulants and measure the turbidity of the treated water.

If the natural water treated in this way has an unacceptable turbidity, it is clear that the residual turbidity is exhibited by particulates with specific properties, and the method of the invention can eliminate such turbidity. Natural waters can be effectively clarified to acceptable turbidity.

After deciding on the specific natural water to be treated, the first thing that needs to be done is to infuse the sample water with a polyurethane solution with a specific solution viscosity.
mixing an effective amount of class coagulant.

As previously mentioned, the polyquaternary coagulant should have a solution viscosity at 25° C. in the range of about 40 to 150 centistokes as an aqueous solution containing 37% by weight of the cationic portion of the coagulant.

The benefits of clarification are significantly reduced if the measured solution viscosity exceeds about 150 centistokes.

Cationic coagulants useful in the method of the invention are those obtained by reacting an amide with an epoxy compound until a specified solution viscosity is obtained.

A more preferred method of preparation is by reacting shrimp chlorohydrin with a mostly secondary amine such as dimethylamine.

Small amounts of polyfunctional amines may also be used in combination with dimethylamine, generally up to 15 mole percent of the total amine usage.

Suitable polyfunctional amines are polyalkylene polyamines having the general formula % where n is an integer from O to about 4, such as ethylenediamine, diethylenetriamine, triethylenetetramine and tetraethylenepentamine.

These polyquaternary compounds and their methods of preparation are well known; the only requirement is that the polyquaternary compound have a specific solution viscosity.

Another type of polyquaternary coagulant used in the process of the present invention is one in which a primary amine is reacted with a difunctionally engineered poxy compound and is quaternized after polymerization so that the solution viscosity reaches the desired value. It is.

For example, methylamine can be reacted with shrimp chlorohydrin to form a polymer, and the resulting polymer can be quaternized with methyl chloride to reach a suitable solution viscosity.

For the preparation of the polymers, US Pat. Nos. 3,567,659 and 3,738,945 and the references cited therein are suitable references.

The amount of polyquaternary coagulant required for the process of the present invention will vary depending on the particular natural water to be clarified and the particular polyquaternary coagulant used.

Generally speaking, the effective usage amount is 0.00% based on the weight of the water to be treated. True polymer weight ranges from 1 ppm to 100 ppm.

This polymer weight means the total amount of cationic parts and anionic parts of the polyquaternary coagulant.

The most common usage levels range from 1 to 40 ppm, preferably from 0.5 to 25 ppm on the same basis.

Actual usage levels will vary at different times of the year due to climatic conditions and other factors governing the amount of water from natural sources and the type and amount of suspended solids present in natural waters. .

The desired degree of clarity also influences the level of coagulant used.

In any case, the amount of polyquaternary coagulant effective to obtain the desired degree of clarity is readily determined by trial.

In practicing the present invention, the addition of the required amount of polyquaternary coagulant to natural water is preferably carried out under conditions that create a vortex.

Generally, the coagulant is distributed throughout the natural water and maintained in contact with the suspended solids until the desired initiation of coagulation occurs.

The treated water is moved to the coagulation section of the clarifier where the coagulant and suspended flocs and particles are given time to remain in further contact with the coagulant.

Although increasing the residence time increases clarity, it is not always possible to use longer times due to limitations imposed by the equipment implementing the method.

Water and coagulant are mixed together under turbulent flow conditions and treated within a short period of time, e.g. 1 to 5 minutes, and the treated water is filtered without passing through a normal clearing tank or settling tank. It is also possible to implement the invention in this manner.

Thus, it is possible that the naturally occurring water brine obtained from the water source may function effectively as at least part of the treatment device.

In this case, it is desirable to add a precipitant when performing the sedimentation operation.

The clarity of the water obtained by the present invention is higher than by conventional methods.

The residual turbidity value is at least about 0.5 J, TJJ, than in the conventional method.

Low, more typically about 2-5 J, T-U, even lower.

Two lines are shown in the drawing, the curve representing the residual turbidity of the kaolin clay suspension as a function of the solution viscosity of the polyquaternary coagulant.

The straight line shows the turbidity remaining after clarification of natural water as a function of the viscosity of the coagulant solution.

The following examples are presented to explain the invention in further detail.

Parts and percentages in the examples are by weight unless otherwise indicated.

Comparative Example A Initial turbidity is J, T, U (Jackson turbidity unit) and 2
Prepare a kaolin clay suspension in water as in step 5.

In order to evaluate the clarification effect on this suspension, 37% of polyquaternary coagulant was added to water based on the weight of the cationic part of the quaternary coagulant.
A series of dissolved polyquaternary coagulant coagulant solutions of different solution viscosities at 25°C were tested.

1 weight of treated water for the same amount of aliquot of prepared suspension
Add 2 parts of the true polyquaternary compound weight, including the cationic and anionic parts, per million parts.

After stirring for 1 minute at 10100 rpm using an electric stirrer and further stirring for 15 minutes at 40 rpm,
Let stand for 15 minutes.

The supernatant liquid was removed, the residual turbidity was measured, the percentage of the obtained turbidity with respect to the initial turbidity was calculated, and the 25°
Plot against solution viscosity at C.

The solution viscosity refers to the solution viscosity when the cation part weight of the polyquaternary coagulant is contained in the solution at 37% as described above.

The results are shown as curves in the accompanying drawings.

As shown in the figure, when coagulating the kaolin clay suspension, the percentage of residual turbidity decreases as the solution viscosity of the polyquaternary coagulant increases.

This is discussed in US Pat. No. 3,738,945 (Panzer
Others are stated in the article (dated June 12, 1973).

Examples 1-5 In this series of examples, the natural water to be clarified is the Lower New Esses of the Authority Canal in Texas.
Water obtained from the valley has an initial turbidity of 42 J, T,
It is U.

Finely suspended colloidal solid particles in water are approximately 5J in the above turbidity.
,T.U.

It was determined in a preliminary experiment that it contributed to

In this series of Examples, a coagulant was added to the same amount of natural water and the method of Comparative Example A was followed.

Remove the supernatant and analyze the residual turbidity. The residual turbidity is calculated as a percentage of the initial turbidity and is plotted against the solution viscosity at 25° C. of a solution containing 37% of the coagulant in solution based on the cationic weight of the polycoagulant.

Polyquaternary coagulants of various solution viscosities are prepared by reaction of shrimp chlorohydrin and dimethylamine according to the method of US Pat. No. 3,738,945.

Various solution viscosities were evaluated and the results obtained using 2 ppm coagulant as in Comparative Example A are shown in Table 1 in contrast to solution viscosities.

In this case, the correlation between residual turbidity and solution viscosity forms a straight line as shown in the figure.

Table 1 Solution Viscosity* Residual turbidity example (centistokes) (%) 1 50 112
75 173
100 214
125 295
140 32 Comparative implementation flow side B※※ 385 91* Viscosity of a solution containing 37% of the polyquaternary compound in the solution based on the cation moiety (25°C) **Comparison implementation flow side is used Same as Examples 1 to 5, except that the solution viscosity at 25°C of the solution containing 37% by weight based on the cation part of the high molecular weight quaternary coagulant was higher than 150 centistokes. It is done.

From the results in Table 1 and the plots shown in the figure, it can be seen that the flocculation performance increases as the solution viscosity decreases in the treatment of the natural water used.

This is in direct contrast to the performance shown with kaolin clay suspensions.

Comparative Example B shows typical performance of high molecular weight polyquaternary compounds used by conventional methods.

Next, embodiments of the present invention will be listed.

(1) The turbidity contribution of colloidal particles to the total turbidity is 0.5
10J, T, U.

(2) A method according to the claims, wherein the polyquaternary coagulant is obtained by reaction of dimethylamine and shrimp chlorohydrin.

(3) A polyquaternary coagulant is obtained by the reaction of dimethylamine, a polyalkyleneboryan, and shrimp chlorohydrin, and the polyalkylenepolyamine accounts for up to 15 mole percent of the total amount of amine used. the method of.

(4) The method according to the preceding item (3), wherein the polyquaternary coagulant is obtained by the reaction of dimethylamine, ethylenediamine, and shrimp chlorohydrin.

(5) The method according to item (1) above, wherein the polyquaternary coagulant is obtained from the reaction of dimethylamine and shrimp chlorohydrin.

(6) A polyquaternary coagulant is obtained from the reaction of dimethylamine, a polyalkylene borian, and shrimp chlorohydrin, and the polyalkylene polyamine comprises up to 15 mol% of the total amount of amine used. Section method.

(7) The method according to the preceding item (6), wherein the polyquaternary coagulant is obtained by the reaction of dimethylamine, ethylenediamine, and shrimp chlorohydrin.

(8) A method according to claims, in which a precipitant is used in the precipitation step.

(9) The turbidity contribution of colloidal particles to the total turbidity is 0.5
to 10J, T, U, the method of the preceding paragraph (8).

[Brief explanation of the drawing]

The accompanying figure shows the relationship between cationic polymer coagulant and residual turbidity of water.

Claims (1)

[Claims] 1. The solution viscosity of an aqueous solution of a polyquaternary compound coagulant containing 37% by weight of cation parts in the aqueous solution is about 40 to 1.
An effective amount of polyquaternary coagulant that is 50 centistokes is applied to a total turbidity ranging from 4 to 250 J, T, U, (Jackson turbidity units) and at least 0.5 of the total turbidity.
J, T-U- is added to natural water containing suspended solids, such as due to the presence of colloidal particles ranging in diameter from about 0.09 to 1.5 mμ, and an initial floc is added to the natural water. After generation, the flocs are left suspended in water to adsorb an effective amount of the colloidal particles onto the flocs to form a sedimentary floc, and then the sedimentary flocs are sedimented and removed together with the adsorbed colloidal particles. The method for clarifying natural water as described above.