JPH0947799A - Treatment of muddy water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To flocculate a muddy water by effectively utilizing ready-mixed concrete becoming an industrial. waste and to efficiently treat both by adding the ready-mixed concrete to the muddy water to flocculate the muddy water and separating the flocculated water into the precipitate and supernatant water. SOLUTION: Ready-mixed concrete is added to a muddy water to flocculate the muddy water, and the flocculated water is separated into the precipitate and supernatant water. By this method, the muddy water is flocculated without adding other flocculants. Meanwhile, the ready-mixed concrete as the waste made useless on a job site need not be separated but is effectively reutilized. Accordingly, both to be disposed of are efficiently treated. Further, when the supernatant water is used as the mixing water, the supernatant water as it is used as the mixing water, and the water in the muddy water is effectively utilized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating muddy water discharged in, for example, construction work.
The present invention relates to a method for simply and effectively utilizing this muddy water.

[0002]

2. Description of the Related Art In excavation work sites or construction work sites, a large amount of water or ground stabilizing solution is poured into the excavation holes to stabilize the excavation holes. Therefore, at the end of excavation or the like, high-moisture muddy water in which water and soil (clay) are mixed is generated in the excavation hole and is discharged by a pump or the like.

[0003]

However, since this muddy water has a high pH and contains fine particles such as clay, it cannot be disposed of in a river or the like as it is. It had to be treated as industrial waste. On the other hand, ready-mixed concrete is generally used at construction sites and the like, but ready-mixed concrete may be left over at the site. The ready-mixed concrete in this case is no longer useful. Therefore, it has been necessary to return the so-called "recycled fresh concrete" to the factory for producing fresh concrete, and separate and treat it into gravel, sand and sludge in the factory for reuse and disposal. Therefore, the present invention relates to a method for treating muddy water which is industrial waste, and also to effectively utilize the ready-mixed concrete that has also become industrial waste to perform muddy water coagulation treatment and efficiently perform both treatments. To aim.

[0004]

According to the present invention, in order to solve the above-mentioned technical problems, raw concrete can be added to mud to separate mud into free water and precipitate. I found it. That is, the first invention is a treatment method of aggregating muddy water obtained by mixing soil and water, in which fresh concrete is added to the muddy water to agglomerate the muddy water to form a precipitate and supernatant water. It is a method for treating muddy water, which is characterized in that it is separated into According to this method, ready-mixed concrete is
It acts as a coagulant for muddy water and can coagulate muddy water without adding another coagulant. On the other hand, conventional ready-mixed concrete that is no longer needed at the site, such as recycled ready-mixed concrete (hereinafter referred to as waste ready-mixed concrete).
Can be effectively reused without separation processing. Therefore, it is possible to efficiently handle both of which need to be discarded.

The first aspect of the invention is characterized in that the supernatant water is used as mixing water for fresh concrete. According to this method, by using the supernatant water as it is as the mixing water for the fresh concrete, the water content of the muddy water can be effectively utilized, and the waste ready-mixed concrete can be efficiently reused for the production of the fresh concrete. . Thus, by effectively utilizing the muddy water and the waste fresh concrete for the production of the fresh concrete, it is possible to reduce the manufacturing cost of the concrete and the adverse effects on the environment.

The first invention is characterized in that the precipitate is dried to have a corn index of 2 or more. According to this method, the precipitate is dried to remove water. When the precipitate is dried to a corn index of 2 or more, it can be used for various purposes as various soil materials according to the corn index without waste treatment, and mud and waste concrete can be efficiently reused. .

In the first invention, the precipitate is made to have a corn index of 2 or more by adding a cement-based solidifying material and / or ordinary Portland cement to solidify the precipitate. According to this method, the precipitate separated from the muddy water is dehydrated at an early stage, and the Corn index quickly becomes 2 or more. Also, the Cone Index can be easily increased. Therefore, muddy water and waste ready-mixed concrete can be efficiently used as soil materials for various applications.

[0008]

Embodiments of the present invention will be described below in detail. The muddy water referred to in the present invention is mainly composed of, for example, soil (clay) and water generated by construction work, and specifically, waste bentonite muddy water containing a ground stabilizing solution, a river construction method, etc. Includes waste mud, mud excavations with high water content and fine particles. It should be noted that such construction includes a wide range of construction work, civil engineering work, excavation work, and the like.

In the present invention, fresh concrete is added to muddy water to agglomerate. The coagulation referred to in the present invention means that particles contained in the muddy water are aggregated to generate free water. As a result of this coagulation, the mud is a sediment (aggregate)
And clear water. Here, raw concrete is a material used in civil engineering and construction sites. In the present invention, the ready-mixed concrete is a concrete that includes cement, water, and an aggregate and has fluidity before the setting / hardening reaction by the cement begins, and the fluidity is maintained, but the fluidity is It is low, and it also includes ready-mixed concrete (disposable ready-mixed concrete) that has no utility value and needs to be disposed of on site for construction work. Examples of the waste ready-mixed concrete include reclaimed ready-mixed concrete that is no longer needed at the site and is returned to the fillet manufacturing factory, and ready-mixed concrete that has been experimentally mixed in the factory. In the present invention, it is useful to use waste ready-mixed concrete as ready-mixed concrete. According to the present invention, the waste raw concrete can be used as it is as an aggregating agent for muddy water without requiring a waste treatment. In the present invention, as long as concrete is used, it can be used without particular limitation on the material and the like.

In the present invention, the flocculating action of the fresh concrete is exerted by the interaction of the constituent materials such as cement, aggregate and water. That is, the fresh concrete is mainly composed of a cement paste composed of water and cement and an aggregate such as gravel or sand as in the case of the normal fresh concrete, but calcium which is not ionized in the cement paste. Since the ions remain abundantly, a large amount of calcium ions are eluted into the mud by adding the raw concrete to the mud. In addition, the sedimentation action of sand and gravel is combined with the aggregating action of calcium ions, which has a synergistic effect on the agglomeration of muddy water.

The amount of the fresh concrete added to the muddy water is preferably 10 vol% (hereinafter simply referred to as%) or more and 15% or less per 1 m ^{3 of the} fresh concrete. This is because if it is less than 10%, the aggregating action is recognized, but it takes a long time for the aggregating, and if it exceeds 15%, the aggregating effect and the aggregating time are the same as those at the addition of 10%. In addition, a more preferable addition amount is 10%
It is.

The addition of ready-mixed concrete to the muddy water is preferably carried out at a sludge treatment plant containing muddy water or at a ready-mixed concrete manufacturing plant. This is because in such a case, the treatment of muddy water and the reuse of recycled concrete can be efficiently performed. As shown in Fig. 1, in these factories, fresh concrete is added to the muddy water that is generated at the construction site, transported by container dump trucks and vacuum trucks, and put into the sludge treatment tank (sedimentation tank), and stirred. , And mixed, and an agglutination reaction occurs. Then, after being separated into supernatant water and a precipitate by coagulation, the supernatant water is discharged by a pump or the like, and the precipitate is also discharged from the tank.

The obtained supernatant water is strongly alkaline because it contains calcium ions derived from cement components, and it is necessary to neutralize it before it can be discharged out of the factory. If it is used as the mixing water to be used, it can be used as it is without being neutralized. In the present invention, since the raw concrete is used as the flocculant without using the flocculant, there is a possibility of adverse effects on the physical properties of the raw concrete and the cured concrete when the flocculant is mixed in the mixing water. Absent.
In particular, when returning green concrete is used as the flocculant, the returning green concrete can be effectively and efficiently reused in the green concrete factory.

On the other hand, the obtained precipitate is dried or solidified. Examples of the drying treatment include dehydration treatment using a filter press, a centrifuge or the like, natural drying such as sun drying and air drying, and the solidifying treatment includes
Cement-based solidifying material, and a drying treatment of adding cement to dry while promoting solidification are included. In particular, when natural drying is used in the drying process and the solidifying process, it is effective in that it does not take time. Further, in the solidification treatment, solidification is promoted by the addition of the solidifying material, so that the cone index of the precipitate can be easily improved.

Here, the cement-based solidifying material refers to a material in which various active ingredients are added using cement as a base material, and specifically, a cement solidifying material "Asano Clean Set" manufactured by Nippon Cement Co., Ltd. -30 series and Geolite 1 from "Geolite series" manufactured by Chichibu Onoda Cement Co., Ltd.
2 and TL of “Tough Rock” of Sumitomo Osaka Cement Co., Ltd.
-3 is preferred. Ordinary Portland cement is a type of Portland cement and has JIS standards. Generally, since the cost of ordinary Portland cement is lower than that of the cement-based solidifying material, the use of a large amount of ordinary Portland cement reduces the overall cost. In addition, as a material used for the solidification treatment, a lime-based solidifying material or a cement / coal ash-based solidifying material can be used. Further, early-strength / ultra-early-strength cement can be used because it exhibits high strength and high strength.

To evaluate the degree of solidification treatment, the Cone Index of the treated precipitate is measured. The cone index is an index of trafficability, and trafficability refers to the running performance and workability of a construction machine. That is, if the cone index [unit: kgf / cm ² ] is 3 or more, the wetland bulldozer can run, and if the cone index is 2 or more,
A super wetland bulldozer can run. The cone index is a value obtained by dividing a penetration resistance force when a cone is penetrated into soil by a bottom area of the cone. The corn index is used as a standard for soil classification of soil generated at construction sites and the like, and the usage is determined according to the corn index value. If the index is 2 or more, it can be used for landfill. Therefore, the obtained precipitate, after the solidification treatment, the cone index is measured, as various soil materials according to the cone index,
It is effectively used for various purposes.

[0017]

EXAMPLES The present invention will be described below based on specific examples.

Example 1 The muddy water of this example was collected at a road construction site (Nagoya Expressway Yotsuya (No. 2) construction section). With respect to this muddy water, samples of Examples and Comparative Examples were prepared and tested according to the formulations shown in Table 1 below. A sample was prepared by adding a predetermined amount of each material shown in Table 1 to 300 ml of a muddy water sample, stirring the mixture with a spoon, mixing and testing. In addition, in the comparative example, a commercially available product was used as the aggregating agent.

[0019]

[Table 1] The mixing ratio of the recycled green concrete is as follows. Normal Portland cement 294 kg / m ³ Coarse aggregate 943 kg / m ³ Fine aggregate 825 kg / m ³ Admixture 3.822 kg / m ³ Water 176 kg / m ³

As is clear from Table 1, the use of the returning fresh concrete as the flocculant produces free water equivalent to that of the high molecular type (Alon hook) and the inorganic type (sulfuric acid band), and is almost intermediate. A flock forming effect was obtained. Therefore, it was found that the recycled green concrete can be sufficiently used as a replacement material for a commercially available coagulant.

(Example 2) The free water obtained in Example 1 was used as the mixing water used in the production of raw concrete,
As a comparative example, the test shown in Table 2 was conducted using an example in which tap water was used as the mixing water. At this time, the composition of green concrete was as follows. The nominal strength of green concrete was 21, the slump 18, and the maximum size of coarse aggregate was 25 mm. JIS for fresh concrete test and hardened concrete test
According to the test method of. Table 2 shows the results.

[0022]

[Table 2] * 1: According to JIS A 1101. * 2: According to JIS A 1128. * 3: According to JIS A 1108. * 4: According to Annex 5 of JIS A 5308.

As is clear from Table 2, the performance of the ready-mixed concrete prepared by using the free water obtained in Example 1 as the mixing water of the ready-mixed concrete is the same as that when tap water is used as the mixing water. It was comparable to the standard and satisfied the JIS quality standard (JIS A 5308). Therefore, it was found that the free water of this example can be sufficiently used as the mixing water for the raw concrete.

(Example 3) The precipitate (initial water content 45%) obtained in Example 1 was dried under the following conditions for solidification.
The drying conditions were from December to February, the drying unit was one week, and the drying place was a concrete soil, and the sun was dried. In addition
The method of measuring the index is based on JSCE Standard (JSF T 71
6-1990).

[0025]

[Table 3]

As is apparent from Table 3, when dried in the sun, the cone index becomes 2 or more from the 4th day, and it can be effectively used as a soil material, especially for landfill.

Example 4 To the precipitate (initial water content: 45%) obtained in Example 1, 10% by weight of the weight of the precipitate, such as a cement-based solidifying material, was added, mixed, kneaded, and dried. The results of daily drying are shown in Table 4. The other drying conditions are the same as in Example 3.

[0028]

[Table 4] However, the solidifying material of Example 4 is a cement-based solidifying material (Toughlock, TL-3, manufactured by Sumitomo Osaka Cement Co., Ltd.)
The solidifying material of Example 5 is a cement-based solidifying material (Tough lock,
TL-3) is a 1: 1 mixture of ordinary Portland cement and the solidifying material of Example 6 is ordinary Portland cement.
(Commercially available product) was used.

As is clear from Table 4, when cement-based solidifying material or ordinary Portland cement is used, it takes only 1 to 2 days for drying to obtain a corn index of 2 or more. The number of drying days was shortened as compared with the case where no addition was made (Example 3: 4 days). Also, if the corn index is increased with time if the drying is continued as it is, when the corn index is 4 or more, it is used not only as a material for landfill (when the corn index is 2 or more) but also according to the index. It can be used for construction, river embankments, road bodies, backfill materials, roadbeds, backfill materials, etc.

The amount of the solidifying material added to the precipitate is
If it is less than 5 wt%, there is no solidification promoting action, and if it exceeds 15 wt%, the cost becomes high, which is not practical. Therefore, the preferable addition amount is in the range of 10 wt% to 15 wt%. Further, since the ordinary Portland cement has a slightly weaker solidification promoting effect than the cement-based solidifying material, when a part of the cement-based solidifying material of Examples 4 and 5 is replaced with the ordinary Portland cement, the cone index is 2 or more. Although the number of days required for the process is long, the cost can be reduced.

[0031]

According to the present invention, by adding fresh concrete to muddy water, muddy water can be agglomerated, and muddy water and unnecessary fresh concrete can be effectively reused.

[Brief description of drawings]

FIG. 1 is a view showing a muddy water treatment system according to the present invention.

FIG. 2 is a diagram showing a conventional muddy water treatment system.

Claims (4)

[Claims] 1. A method of coagulating muddy water, which is a mixture of soil and water, in which fresh concrete is added to the muddy water to coagulate the muddy water and separate it into a precipitate and a supernatant water. A method for treating muddy water, which is characterized in that 2. The method for treating muddy water according to claim 1, wherein the supernatant water is used as water for mixing fresh concrete. 3. The method for treating muddy water according to claim 1, wherein the precipitate is dried to have a corn index of 2 or more. 4. The method for treating muddy water according to claim 1, wherein the precipitate is solidified by adding a cement-based solidifying material and / or ordinary Portland cement to a corn index of 2 or more. A method for treating muddy water, which is characterized by: