JPH07163998A - Treatment of muddy water and device therefor - Google Patents

Abstract

PURPOSE:To continuously dehydrate a waste muddy water into a cake having a low content of water by using this small-sized device excellent in dehydration and filtration effect and economical efficiency. CONSTITUTION:A waste muddy water is sent to a dehydrator 11 from a construction site and dehydrated. In this case, a first static mixer 6 and a second static mixer 8 are arranged in the middle of a supply route R leading to the dehydrator 11. An alpha soln. as the primary flocculant is admixed on this side of the mixer 6, a beta soln. as the secondary flocculant is admixed on this side of the mixer 8, and the waste muddy water is supplied to the dehydrator 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention eliminates waste mud generated from, for example, construction of an improved body in the ground, construction of a continuous underground wall, a column-type continuous wall or a structure such as a shield tunnel. The present invention relates to a waste mud water treatment method and a treatment device for efficiently and continuously treating it with a small-scale device.

[0002]

2. Description of the Related Art For example, in a soil improvement work in which a cement-based chemical is injected into the ground and agitated with the soil, a continuous underground wall or pile construction work, or a tunnel construction work using a shield construction method, waste with a high water content is used. A large amount of muddy water is generated. Conventionally, this kind of waste mud water is transported to the disposal site by "raw" by a vacuum car or a sludge-only carrier, and discarded, or batch dewatering with a filter press or a hardening agent such as cement is added. After the improved treatment, the raw mud was adjusted to a concentration and pH suitable for treatment and subjected to continuous treatment or batch treatment, and if the waste mud contains a hardening material, wait for solidification by leaving it in the site. I was carrying out a dump.

[0003]

However, the transportation by the vacuum vehicle and the like has problems such as high transportation cost and enormous processing cost, and recently, it has become more difficult to secure a disposal site. There is.

Further, in the case of batch processing by a filter press, a large amount of sludge cannot be efficiently processed, and a storage tank for temporarily storing mud, a specific gravity adjusting tank and a stirring tank with a coagulant are required. As a result, the overall size of the processing equipment becomes large, and it is often impossible or difficult to employ it in urban construction work or small-scale construction work. In this case, the amount of waste cannot be reduced, resulting in an increase in waste disposal cost.

On the other hand, the method of naturally drying requires a large yard for that purpose, so even if it is good to secure a yard in the case of landfill or dam construction, in urban civil engineering, it is extremely dedicated yard for that purpose. Is in a situation where it cannot be secured. Therefore, the main problem of the present invention is to reduce the size of the device, and also excellent in dehydration and filtration effects, excellent in economic efficiency, and a mudwater treatment method and a treatment device therefor capable of continuously performing dehydration treatment to a low water content cake. Is provided.

[0006]

[Means for Solving the Problems] In the waste mud treatment method of sending waste mud water from a construction site to a dehydrator to perform drainage processing of the waste mud, the static mud is provided in the middle of a feed path to the dehydrator. The problem can be solved by disposing a mixer, adding a coagulant at a position before or in the middle of this static mixer, and mixing it with waste mud water.

In this case, as the coagulant, a two-component coagulant comprising a latex as a primary additive and a hydrophilic protective colloid-forming substance as a secondary additive is used, and mixing and hydrophilic protection after addition of the latex are used. Mixing after addition of the colloid-forming substance is preferably carried out by a series of static mixers arranged in the waste mud water supply passage or each static mixer. In addition, it is preferable to change the amount of the coagulant added depending on the flow rate and density of the waste mud water.

In order to continuously perform the dehydration treatment, as the dehydrator, a drum press dehydrator, a belt press dehydrator, a centrifugal dehydrator, a gravity type dehydrator or the like which can be continuously treated is selected.

[0009]

In the present invention, a static mixer is arranged in the middle of the feed passage leading to the dehydrator, and a coagulant is added before or at the intermediate position of the static mixer to mix with the waste mud water. In the past, a stirring tank was separately prepared for stirring waste mud water and a flocculant, but in the case of the present application, a static mixer was installed in the line, so a stirring tank, adjustment tank, etc. are not required. Next, the entire device becomes compact. Therefore, it becomes possible to mount the muddy water treatment device of the present invention on a truck, which is excellent in mobility and can be used even in a site where the installation space of the treatment equipment cannot be secured, such as in a small site, and at the site where the amount of waste sludge greatly changes. It can also be used for peak cut. Also,
By selecting a drum press dehydrator, belt press dehydrator, centrifugal dehydrator, gravity dehydrator as the dehydrator,
Continuous treatment is possible, and a large amount of waste mud can be treated compared to the equipment scale.

On the other hand, in the present invention, when a two-component coagulant comprising a latex as a primary additive and a hydrophilic protective colloid-forming substance as a secondary additive is used as the coagulant, the effect is particularly remarkable. Here, first, the two-component coagulant will be described in detail.

The above-mentioned two-component flocculant is disclosed in JP-A-3-2326.
It is a completely new type of aggregating agent which is newly disclosed in Japanese Patent Publication No. 00 and is different from the conventional one. Specifically, NBR latex, SBR latex, SB latex, Hist latex, acrylate latex, PVC latex or the like is used as the latex, and sodium alginate or carboxymethyl cellulose soda is used as the hydrophilic protective colloid-forming substance. Salts, chito acids, anionic gums, cationic gums, nonionic gums, sodium acrylates are used.

The conventionally used inorganic coagulant imparts an opposite electric charge to the electric charge (generally negatively charged) carried by the suspended matter in the waste mud to make it electrically neutral, so that the particles are mutually reciprocated. The polymer flocculating agent eliminates repulsion and causes aggregation, and the polymer flocculating agent neutralizes surface charges of colloids and fine particles suspended in water to cause the particles to aggregate and form large flocs by an adsorptive crosslinking action.

On the other hand, a two-component flocculant comprising the above-mentioned latex (hereinafter referred to as α liquid) and a hydrophilic protective colloid-forming substance (hereinafter referred to as β liquid) is as shown in FIG. 5 (a). First, when the α liquid is put into the waste mud, the particles are contacted with the fine particles (clay, silt) 50, 50 ... The functional polymer electrolyte membrane 51 having numerous pores for adsorbing and immobilizing and adsorbing and encapsulating water encloses the fine particles. Next, when β solution is added to this, as shown in FIG. 5B, the functional polymer electrolyte membrane 51 becomes insoluble while the fine particles 50 are still taken in. At this time, since it has a property of contracting, the fine particles 50 wrapped in the functional polymer electrolyte membrane 51 discharge water from innumerable pores and separate into water and flocs of fine particles. The flocs formed in this way form much stronger flocs than those made with conventional inorganic flocculants and polymeric flocculants. Then, when the waste mud water to which the two-liquid coagulant is added is dehydrated, the surface of the treated cake is not made water-repellent by the two-liquid coagulant, so that the filter cloth is not clogged, It can be filtered quickly. In addition, the dehydrated cake does not become mud again due to rainfall or the like. Furthermore, p
Since H is also neutral and does not contain heavy metals or harmful substances, it has various advantages such as that the separated water can be discharged as it is.

However, when the two-liquid coagulant α liquid is added and mixed by high-speed stirring, the functional polymer electrolyte membrane 51 on the surface is broken and does not become flocs. Therefore, according to the present invention, the static mixer is used. Thus, by performing mixing and stirring, flocs in good condition can be formed.

Although the total addition rate of the two-liquid flocculant depends on the property of the waste mud, it is desirable that the 10% solution is approximately 12 to 25% per 1 m ³ of the waste mud volume. When the total addition rate is less than 12%, good flocs are not formed, the amount of drainage is reduced, and the water content of the dehydrated cake is increased. Further, if the total addition rate exceeds 25%, the drainage efficiency does not increase in spite of the increase in the addition rate, which is uneconomical. In addition, as a general rule, the addition ratio is 5: 5, a preliminary dehydration test is performed, and the ratio is appropriately adjusted within the range of 9: 1 to 1: 9. On the other hand, the stirring time by the static mixer is 5 to 20 seconds, preferably about 8 to 15 seconds. If the stirring time is less than 5 seconds, the coagulant to be added cannot be uniformly dispersed. If the stirring time exceeds 20 seconds, flocs may be broken and turbidity may increase depending on the amount of the coagulant added.

[0016]

EXAMPLES The present invention will be described in detail below based on examples.
FIG. 1 is a block diagram showing a specific example of the case where the two-liquid coagulant composed of the above-mentioned α liquid and β liquid is used as the coagulant to perform the dehydration treatment of waste mud water.

The waste mud water generated from the construction site is temporarily stored in the waste mud storage tank 1. Since the waste mud water storage tank 1 continuously performs the dehydration treatment, a small capacity is sufficient as compared with the storage tank volume in the case of the conventional filter press treatment.
The level of the stored waste mud water is monitored by the level sensor 2, the weight is monitored by the weight sensor 3 such as a load cell, and the pH is measured by the pH meter 17.

The waste mud water stored in the waste mud water storage tank 1 is fed to the dehydrator 11 by the feed pump 15 to be dehydrated. In this embodiment, the waste mud water is fed to the middle of the waste mud feed passage R. Equipped with static mixers 6 and 8 in order,
Each coagulant added to the waste mud and waste mud water are mixed and stirred in a line.

More specifically, the primary coagulant storage tank 20 for separately storing the α liquid and the secondary coagulant storage tank 21 for storing the β liquid are separately provided, and the supply from the primary coagulant storage tank 20 is performed. The passage is connected to the waste mud water feed passage 12, and the first static mixer 6 is arranged immediately downstream of this connection point, and the feed passage from the secondary flocculant storage tank 21 is connected to the static mixer 6 While connecting to the downstream side position,
The second static mixer 8 is located immediately downstream of this connection point.
Are installed. As shown in FIG. 2, the first and second static mixers 6 and 8 are provided with flanges 41 and 41 at both ends of a tubular housing 40, and a rectangular plate is twisted in the housing 40 by 180 °. The right element 42 and the left element 43 are arranged in a continuous state while alternately intersecting each other by 90 °, and the fluid passing therethrough undergoes the dividing action and the converting action by the element groups 42, 43. Mixed effectively. It should be noted that the first static mixer 6 and the second static mixer 8 are not separated from each other, and they are composed of one long static mixer as shown by the broken line, and the α solution is added in the front and the β solution is added at the intermediate position. It may be done. Also,
The first static mixer 6 and the second static mixer 8 may be plural. In short, after the α liquid and the β liquid are added, the static mixer provided in the line may be provided so as to perform stirring for an appropriate stirring time in relation to the flow rate and the flow rate.

The amount of flocculant added is controlled on the upstream side of the first static mixer 6 by a flowmeter 4 such as an electromagnetic flowmeter, a mass flowmeter, a differential pressure flowmeter, an area flowmeter, an impeller flowmeter, and gamma rays. Alternatively, a density meter 5 such as a differential pressure type is provided, and it is mainly based on the flow rate information and the density information of the waste mud water obtained from these sensors 4 and 5, but the first static is used to evaluate the mixing degree of stirring. A mixing degree measuring device for visually observing the flocs M passing through the transparent portion by interposing a straight pipe or a curved pipe made of a transparent pipe on the downstream side of the mixer 6 as shown in FIGS. 7 is provided, and the transparent tube shown in FIG. 3 is interposed downstream of the second static mixer 8 for the evaluation of the degree of separation, thereby measuring the light transmittance or measuring the density. Flock formation sensor 9 to measure the state In addition, an infrared monitor 1 is provided for the dehydrator 11 to evaluate the water content of the dehydrated cake.
2 is provided, and the separated water flow meter 1 is provided downstream of the dehydrator 11.
3, the amount of coagulant added is determined in consideration of the information obtained from each of these sensors, the processing speed of the dehydrator 11 is determined, and the coagulant pumps 22 and 2 are determined.
The motor rotational speed of 3 and the motor rotational speed of the dehydrator 11 are adjusted to control the water content of the cake.

On the other hand, as the dehydrator 11, a drum press dehydrator is preferably used. When using a drum press dehydrator, continuous and high-speed dehydration processing is possible, and a large amount of processing is possible despite its small size. In addition, the space of processing equipment can be significantly reduced. Since the processing system can be made compact, the processing system can be mounted on a truck of about 4 tons and can be transported, thus improving maneuverability. In this case, vacuum force can also be used as preliminary dehydration.
For example, specifically, the dehydrator shown in FIG. 4 is used. In the illustrated example, three static mixers 6a to 6c are used as the first static mixer 6, and three static mixers 8a to 8c are used as the second static mixer 8. The sensors are not shown.

The waste mud water flocculated by the addition of the coagulant is put into the drum press dehydrator 11. In the feeding section, the spreading roller 30A and the leveling roller 30B spread the sheet uniformly on the filter cloth 31, and the vacuum hopper 32 disposed below the filter cloth performs vacuum suction dehydration. The dehydrated water is sent to the separated water tank 33 as separated water and discharged from here. The vacuum-dehydrated flocs are compressed and dehydrated by the main drum 34, peeled off by the soil discharging plate 35, and discharged as a dehydrated cake. The filter cloth 31 which circulates around the vacuum dewatering section and the main drum section is constantly washed by the washing shower 36 so that the fine grain soil does not cause clogging. Further, the water content ratio of the dehydrated cake is adjusted by the addition amount of the coagulant, the vacuum suction force and the compression force of the main drum 34. Specifically, the compression force of the main drum 34 is adjusted by changing the tension of the pressure filter cloth 38 by the pressure roller 37. The water squeezed by the main drum 34 and the wash water are temporarily stored in the water tank 39, and then returned to the floc input section again. If the turbidity is small, it will be discharged from the separation water tank.

As an alternative dehydrator, continuous dehydrators such as a belt press dehydrator, a centrifugal dehydrator, and a gravity dehydrator are preferably used. A batch type dehydrator such as a filter press can also be used.

The water content of the dehydrated cake obtained in such a waste mud water treatment system is about 40 to 60%, and dumped and disposed of as residual soil and recycled soil. On the other hand, the pH of the separated water is measured by the pH sensor 14, and if the pH treatment is required, it is neutralized by the pH adjuster 16 and then reused or discharged.

[0025]

As described in detail above, according to the present invention, the size of the apparatus is reduced, the dehydration and filtration effects are excellent, the economy is excellent, and waste mud water is continuously dehydrated into a low water content cake. You will be able to process.

[Brief description of drawings]

FIG. 1 is a block diagram of a waste mud treatment system according to the present invention.

FIG. 2 is a vertical sectional view of a static mixer.

3 (a) to 3 (c) are enlarged views of main parts showing respective examples of the mixing degree measuring instrument.

FIG. 4 is a schematic diagram of a waste mud water treatment system.

FIG. 5 is an explanatory diagram of a floc formation mechanism by a two-liquid type flocculant.

[Explanation of symbols]

1 ... Waste mud storage tank, 2 ... Level sensor, 3 ... Weight scale,
4 ... Flowmeter, 5 ... Density meter, 6 ... 1st static mixer, 7 ... Mixing degree measuring device, 8 ... 2nd static mixer, 9 ... Flock formation degree sensor, 10 ... Controller, 11
... dehydrator, 12 ... infrared monitor, 13 ... flow meter, 14
... pH sensor, 20 ... Primary coagulant storage tank, 21 ... Secondary coagulant storage tank, 24/25 ... Flowmeter, 30A ... Extension roller, 30B ... Leveling roller, 31 ... Filter cloth, 32 ... Vacuum hopper, 34 … Main drum, 38… Pressure filter cloth

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshinori Hata 4-12-20 Nihonbashi Honcho, Chuo-ku, Tokyo Sato Industry Co., Ltd. (72) Inventor Yurio Mitsui 2-21-13 Yanagibashi, Taito-ku, Tokyo No. Toyo Kogyo Co., Ltd. (72) Inventor Masaru Shibata 26-30 Eki-cho, Suita City, Osaka Prefecture Sekisui Environment Co., Ltd.

Claims (6)

[Claims] 1. A method for treating waste mud by sending waste mud from a construction site to a dehydrator to dehydrate the waste mud, wherein a static mixer is provided in the middle of a feed path to the dehydrator, and a static mixer is provided. A method for treating waste mud, which comprises adding a coagulant before or in the middle of the mixer and mixing it with the waste mud. 2. A two-component flocculant comprising a latex as a primary additive and a hydrophilic protective colloid-forming substance as a secondary additive is used as the aggregating agent, and mixing and latex formation of a hydrophilic protective colloid after addition of the latex are used. 2. The method for treating waste mud water according to claim 1, wherein the mixing after the addition of the substances is performed by a series of static mixers arranged in the waste mud water supply passage or each static mixer. 3. The method for treating waste mud water according to claim 1, wherein the amount of coagulant added is changed according to the flow rate or density of the waste mud water. 4. The dehydrator is a drum press dehydrator, a belt press dehydrator, a centrifugal dehydrator, or a gravity type dehydrator.
~ The method for treating waste mud as described in 3 above. 5. A waste mud water storage tank, a flocculant storage tank, and a dehydrator are provided, and a static mixer is disposed in the middle of a waste mud water feed passage from the waste mud water storage tank to the dehydrator. A treatment device for waste mud water, characterized in that a feed passage from the flocculant storage tank is connected to a front side or an intermediate position. 6. A storage tank for a primary flocculant and a storage tank for a secondary flocculant are provided, and a series or a static mixer is provided for each flocculant in the waste mud water supply passage. The treatment device for waste mud water according to claim 5, which is characterized in that.