JPH0631282A - Preventing agent for water pollution - Google Patents

Abstract

PURPOSE:To provide a water pollution preventing agent for absorbing alkali calcium eluted into water because of hydraulic materials such as cement, lime, a solidifying material containing cement or lime, concrete and mortar used at the time of solidifying mud or constructing an artificial pond or a waterway. CONSTITUTION:A water quality turbidity preventing agent contains calcium oxide, calcium sulfate, aluminum oxide and silicon dioxide cured materials, and is prepared by mixing one or more of slaked lime, quick lime, gypsum and volcanic ash with coal ash or 1 used coal waste gas treatment agent and hydrated curing, and then treating by means of smoke containing sulfur oxide and nitrogen oxide. The water pollution preventing agent is prepared by utilizing a used smoke treatment agent of lime family, and the elusion of alkali calcium and the rise of pH can be reduced and controlled easily and effectively by the agent. As the pollution preventing agent itself is cured in water to form a solidified body, neither outflow from the water nor scattering in the water is generated, and secondary pollution is also prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is to prevent water pollution by absorbing calcium alkali dissolved in water by a hydraulic material used when solidifying mud and constructing artificial ponds and waterways to reduce increase in pH. Regarding agents.

[0002]

2. Description of the Related Art Sludge and sludge deposited on the bottom of water such as lakes and rivers, and bottom sediment have become major problems in environmental protection.

These deposited substances (hereinafter also simply referred to as mud) may contain harmful heavy metals and organic substances such as cadmium, lead, hexavalent chromium, and cyan compounds, and prevent elution and sealing. In order to prevent flotation and pollution, mud is solidified using hydraulic materials.

The hydraulic materials used include cement, cement-based solidifying material, lime and lime-based solidifying material.

During the hydration process when these come into contact with water
And lime type, Ca (OH) ₂Will dissolve and
Ment materials,

[0006]

[Chemical formula 1] 2Ca ₃ SiO ₅ + 6H ₂ O = Ca ₃ Si ₂ O ₇ · 3
H ₂ O + 3Ca (OH) ₂

[0007]

Embedded image 2Ca ₂ SiO ₄ + 4H ₂ O = Ca ₃ Si ₂ O ₇ · 3
H ₂ O + Ca (OH) ₂

Ca (OH) ₂ is liberated by the reaction of.
Ca (OH) ₂ is

[0009]

Embedded image Ca (OH) ₂ = Ca (OH) ⁺ + OH ⁻

[0010]

[Chemical 4] Ca (OH) ₂= Ca²⁺ + 2OH^-

It dissociates to increase the amount of hydroxide ion and greatly raise the pH.

In the high pH range, Fe, Mn, Pb,
Ions of metals such as Cu form hydroxides and precipitate.

If the hydraulic material is a cement-based solidifying material, Al such as Mn, Pb, As, Cr or SO ₄
Elements having an ionic radius and structural properties similar to ^2- are very effective in sealing harmful metals because they are solid-dissolved by substitution in ettringite.

When the mud is organic sludge, the hydraulic material kills aerobic, anaerobic bacteria, Escherichia coli, etc. in a short time by the action of calcium alkali, and disinfects it.
Fixes by reacting with various acidic gases that cause a bad odor, and exhibits a deodorizing effect.

As described above, solidification treatment of sludge and bottom sediment with a hydraulic material is a useful countermeasure for environmental maintenance and conservation.

In addition, for the purpose of ensuring water immersion stability and watertightness in the construction of artificial ponds and reservoirs, revetment of waterways and rivers, and floor stop construction, the soil on the wall surface and bottom surface is made of a hydraulic material. It is used to consolidate.

[0017] Instead of solidifying the soil, cement concrete, mortar, cement paste, etc. are also placed.

[0018]

When a hydraulic material is used, the water in contact with it is Ca eluted from the hydraulic material.
Due to the dissociation of (OH) ₂ , OH ⁻ ions increase and the pH rises significantly.

The increase in pH adversely affects aquatic organisms and agricultural crops and destroys the habitat or growth environment.

Also, Ca (OH) saturated in water ₂Analysis
It emerges and floats on the surface of the water to form a white dusty "Aku"
Then, a scale-like substance is produced on the bottom of the water and becomes cloudy.

The rise in pH, which was useful for containing harmful substances and detoxifying organic substances in the solidification of sludge and sediment, is a harmful factor from the viewpoint of water pollution.

According to the discharge standard based on the Water Pollution Control Law, the pH is between 5.8 and 8.6, and at a pH higher than this, neutralization treatment must be performed to reduce the pH to within the range.

When the solidified mud, or the artificial pond or waterway created is related to aquaculture ponds or habitats for living things, it is necessary to take measures such as replacing contacting water until it enters the neutral range, It is necessary to take measures to prevent the strong alkaline water from flowing out carelessly.

Therefore, an object of the present invention is to provide a water pollution preventing agent which absorbs the above-mentioned calcium alkali and reduces an increase in pH of water.

[0025]

Means for Solving the Problems As a result of various studies to achieve the above object, the inventors have surprisingly found that a lime composition which has already been developed by the inventors as a flue gas treating agent is treated with flue gas. After being used for absorption of calcium alkali, p
It was found that it is effective in reducing the increase in H.

That is, the present invention is based on CaO and CaSO.
₄ , containing Al ₂ O ₃ , SiO ₂ type hardened material, slaked lime, quick lime, as a coal ash and / or a used lime type exhaust gas treatment agent,
At least one selected from the group consisting of gypsum and volcanic ash is mixed and hydrated and hardened, and then treated with flue gas containing sulfur oxides and nitrogen oxides, which is hardened with a hydraulic material. It is a water pollution control agent, which is characterized by coating the surface of a fish.

Here, CaO, CaSO ₄ , Al ₂ O ₃ and S
As the raw material of the iO ₂ -based cured product, a single industrial product such as industrial alumina or silica may be used, or a natural product, industrial waste, or the like may be used.

That is, as the CaO and CaSO ₄ sources,
Examples include by-products such as quick lime, slaked lime, lime carbonate, gypsum, cement, slag, dolomite plaster (containing lime), and acetylene slag.

As the Al ₂ O ₃ source, for example, alumina, aluminum hydroxide, aluminum silicate, sulphate sulfate,
Reactive aluminum such as alum, aluminum sulfide, aluminum sulfate, aluminum chloride, calcium aluminate, bentonite, kaolin, diatomaceous earth, zeolite, perlite, bauxite, sodium aluminate, cryolite, aluminum washing residue (alcite) The compound etc. which are contained are mentioned.

Examples of the SiO ₂ source include silicic acid, hydrous silicic acid, metasilicic acid, aluminum silicate, water glass,
Examples include compounds containing reactive silicon dioxide such as calcium silicate and cristobalite, tridymite, kaolin, bentonite, talc, perlite, shirasu, diatomaceous earth, glass, fir shell ash, and incineration ash such as charcoal.

Further, as examples of substances which can be supplied simultaneously in at least two or more kinds out of the above-mentioned four kinds of components, coal ash and volcanic ash, coal fluidized bed combustion ash (calcium oxide, silicon dioxide, aluminum oxide, calcium sulfate source), Cement and cement clinker (calcium oxide, silicon dioxide, aluminum oxide source), slag and shirasu,
Reactive silicon dioxide such as andesite, chert, quartz trachyte, opal, zeolite, feldspar, clay mineral, ettringite (calcium sulphate, silicon dioxide, aluminum oxide, calcium oxide source), and oxides such as aluminum and calcium, chloride Substances, minerals containing sulfate, etc.,
Furnace desulfurization ash such as fluidized bed combustion ash and used lime-based exhaust gas treatment agent, sludge incineration ash, municipal waste incineration ash, cement waste, acetylene slag, used wastewater treatment agent and the like.

Here, the used lime-based exhaust gas treating agent is
Already used calcium-based desulfurizing agent produced from CaO, Ca (OH) ₂ , CaCO _3, etc.
-209038, JP-A-63-283745 and the like, which have already used desulfurization agents composed of CaO, Al ₂ O ₃ , SiO ₂ and CaSO ₄ type compositions. Table 1 and 2
Tables and Table 3 show examples of chemical analysis of these typical raw materials.

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

[Table 3]

In the present invention, CaO, CaSO ₄ , Al ₂ obtained by mixing these raw materials and hydration hardening
The proportion of each component in the O ₃ , SiO ₂ -based cured product and the cured product after the flue gas treatment described below is CaO 2-8% CaSO ₄ 0.1-70% Al ₂ O ₃ 5-70% SiO ₂ 5 ~ 80%.

A preferred combination of the above raw materials is at least one combination selected from the group consisting of coal ash and / or a used lime-based exhaust gas treatment agent, slaked lime, quick lime, gypsum and volcanic ash.

In the present invention, the hydration hardening means that water is added to the raw material mixture to carry out a hydration treatment to be hardened, and specifically, it is the following treatment.

The hydration treatment is carried out, for example, in Japanese Patent Laid-Open No. 64-3813.
As disclosed in No. 0, it refers to a treatment necessary for promoting the hydration reaction between the above-mentioned substances (raw materials), and includes, for example, wet air curing, hot water curing, steam curing and the like.

In the treatment, the mixing ratio (solid-liquid ratio) of the raw materials and water is set to be small, for example, 1: 0.2 to 1: 0.99 to promote bonding between the material particles and to cure. The body is obtained, and if necessary, it can be divided into two stages.

Moist air curing in the curable hydration treatment is preferably carried out at a temperature of 10 ° C. to 40 ° C. and a relative humidity of 50% to 100% for several minutes or several tens of days.
It is preferable that the temperature is 0 ° C. to 180 ° C. and the relative humidity is 100% for several minutes to several days.

The cured product thus obtained is dried, conditioned, crushed or further molded to obtain a composition.

Crushing of a hardened product which has been wet or dried, compression molding of a crushed product and a dried product of a slurry-like substance can be carried out by using a marmelizer, a disk pelleter, a briquette machine, a tablet molding machine, an extrusion molding machine or the like. This can be done by the pressure formable equipment used.

The composition described above is then subjected to a known flue gas treatment. Some of the gas components in the flue gas include oxygen, water (steam), nitrogen oxides and sulfur oxides.

By this processing, SO _X and NO _{X in the} flue gas are discharged.
Upon contact with the active calcia in the composition reacts and fixes them.

[0046]

[Function] The pollution control action of the water pollution control agent is considered as follows.

In the production process of the present pollution control agent, since the solid-liquid ratio was made small and hydration curing was carried out, many fine voids are held between the material particles in the pollution control agent.

In addition, a large number of fine needle-shaped substances similar to ettringite are produced on the surface of the pollution preventive agent by the flue gas treatment. For this reason, the specific surface area becomes remarkably large and the adsorption ability becomes strong.

The sulfur oxides and nitrogen oxides fixed during the flue gas treatment are negatively charged in water. Thereby,
The cations liberated from the hydraulic material into the water are electrically sorbed.

The counter ion OH ⁻ ion is also ion-adsorbed in the electric double layer around the trapped cation. Thus, it is considered that the concentration of free Ca (OH) _{2 in} water is reduced, and therefore the pH of water is not increased.

The antifouling agent contains a high concentration of anhydrous calcium sulfate, and when it comes into contact with water, hydration of calcium sulfate occurs and the antifouling agents are solidified.

When the surface of the cured product is coated from 2 to 3 cm to a few tens of cm and then immersed in water, the coated product itself becomes a solidified body, and there is no outflow or dispersion in water and secondary pollution does not occur.

[0053]

EXAMPLE 30 parts by weight of coal ash B (overseas) shown in Table 1 was added and kneaded with 30 parts by weight of slaked lime, 40 parts by weight of a used treatment agent (used lime-based exhaust gas treatment agent) and 45 parts by weight of water. After that, it was cured in a moist air until it had a strength enough to withstand molding. Next, extrusion molding was performed and steam curing was performed at 90 to 100 ° C. for 12 hours.

Using the particulate composition obtained by sizing and drying the cured product, smoke exhaust treatment was performed under the conditions shown in Table 4.

[0055]

[Table 4]

Thus, the flue gas treatment was performed to obtain the water pollution inhibitor (water content 1%) of the present invention (Property Table 5).

[0057]

[Table 5]

The performance test as a water pollution preventing agent was conducted as follows.

Hobart type soil was obtained by adding 4.5% by weight of cement-based solidifying material Nittetsu Earthtite 104 having the properties shown in Table 7 to the sample soils having the properties shown in Table 6 with respect to each sample soil. After sufficiently stirring with a mixer, 1300 g each was put into a polystyrene wide-mouth bottle having a volume of 3 l and appropriately compacted using round steel. Further, a mold having a diameter of 5 cm and a height of 10 cm was also filled and used for measuring the compressive strength.

Also, 10 parts by weight of ordinary Portland cement and 4 parts by weight of water were added to 30 parts by weight of fine aggregate for concrete and kneaded with a mixer to prepare a mortar.
Into the same wide-mouth bottle as above, g was tapped and filled.
Table 8 shows the compressive strength after 24 hours.

[0061]

[Table 6]

[0062]

[Table 7]

[0063]

[Table 8]

After molding of each solidified product, a wide-mouthed bottle was coated with 85 g of the above-mentioned water pollution inhibitor so that the surface of the solidified product had a thickness of 7 to 8 mm, and a thickness of 20 mm. 220g was put and coated, nothing was added for comparison, 220g of coal ash was put to make coated, and after 24 hours, 1200g of distilled water was injected into each, and the lid was tightened and allowed to stand, It was used as a sample for measurement.

For comparison, distilled water 120 was added to the water pollution control agent.
The one to which 0 g was added was also prepared. Table 9 shows them.

The pH of water in each sample was measured 3 hours, 1 day, 3 days, and 7 days after water injection. After visually observing the water of each sample 7 days after the water injection, water was collected, added KOH solution to make it alkaline, added NN indicator, and titrated with EDTA to determine Ca.
(OH) ₂ was quantified. The results are shown in Table 10.

[0067]

[Table 9]

[0068]

[Table 10]

[0069]

[Table 11]

If the solidified product is volcanic ash cohesive soil, Comparative Example 1 containing no pollution inhibitor and Comparative Example 2 containing coal ash
Was a strong alkali having a pH of 11 or more, but Examples 1 and 2 in which the antifouling agent was added had a pH of 7 and were neutral.

Examples 3, 4 in which the solidified product is silt
The same applies to Comparative Examples 3 and 4.

In the sand in which the solidified product was mixed with fine particles, the amount of the calcium alkali eluted was large, and therefore the pH was slightly high on the execution side 5 where the amount of the pollution inhibitor was small. In Example 6 where the amount was increased, the pH was lowered.

Examples 7 and 8 in which the solidified product is mortar
Was also the same.

In Comparative Example 9 in which distilled water was simply added to the antifouling agent, the pH was 7. It is considered that the antifouling agent does not neutralize alkali as an acidic substance but adsorbs and fixes the alkaline substance.

[0075]

Example 9 The antifouling agent obtained in Example 1 was treated with a diameter of 5c.
After being placed in a mold having a height of 10 cm and a height of 10 cm, the mold was lightly tapped, and then water was poured to the upper surface of the mold and allowed to stand. After 7 days of demolding and allowing water to flow out, the uniaxial compressive strength was measured.

The result was 1.7 kgf / cm ² . Thus, the antifouling agent forms a solid when immersed in water.

[0077]

As described above, the water pollution control agent of the present invention utilizes a lime-based used smoke control agent, and facilitates elution of calcium alkali and increase of pH by a hydraulic material. It can be effectively and effectively reduced and suppressed.

Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number in the agency FI Technical indication location E02B 3/12 7150-2D (72) Inventor Kunihiro Mori 461-6 Satozuka, Toyohira-ku, Sapporo, Hokkaido Hokkaido Electric Power Co., Inc. (72) Inventor Masahiro Takeda 5-chome Kita 1jo Nishi, Chuo-ku, Sapporo-shi, Hokkaido 6th floor, Kita Ichijo Building Nittetsu Cement Co., Ltd. (72) Inventor Yoshiyuki Niizaki 64 Nakamachi, Muroran-shi, Hokkaido Nikko Cement Co., Ltd. In-house

Claims (4)

[Claims] 1. Used for coating a surface of a cured body obtained by treating a portion immersed in water with a hydraulic material, to absorb calcium alkali generated from the cured body and reduce an increase in pH of water. A water pollution preventive agent characterized by: 2. CaO, CaSO ₄ , Al ₂ O ₃ , SiO ₂
Containing a system hardened product, and mixed with at least one selected from the group consisting of slaked lime, quick lime, gypsum, and volcanic ash in a coal ash and / or a used lime-based exhaust gas treatment agent to hydrate and harden it, and then sulfur The water pollution control agent according to claim 1, which is treated with flue gas containing oxides and nitrogen oxides. 3. The hardened material is earth or sand or mud solidified with at least one of lime, cement, lime-based solidifying material and cement-based solidifying material, concrete, mortar,
The water pollution control agent according to claim 1, which is a hardened cement product. 4. The water pollution control agent according to claim 1, wherein the water pollution control agent coating the surface of the cured body is cured in water to form a solidified body.