KR20110134028A - Dehydration material of sludge with high water containing rate and method of the same using - Google Patents

Abstract

PURPOSE: A dehydrating material for sludge of a high water containing rate and a method for dehydrating the sludge of the high water containing rate are provided to reduce the generation of bad odor by effectively suppressing the generation of ammonia. CONSTITUTION: A dehydrating material for sludge of a high water containing rate includes 100 parts by weight of alkaline chemicals and 20-200 parts by weight of oxidizing chemicals. The alkaline chemicals are composed of calcined dolomite or quick lime. The oxidizing chemicals are composed of sodium alum, potassium alum, or aluminum sulfate. The dehydrating material for sludge of a high water containing rate further includes 250-1000 parts by weight of incineration residues based on 100 parts by weight of the alkaline chemicals. The calcium oxide content of the incineration residues is between 20 and 70%.

Description

High Water Sludge Dewatering Material and High Water Sludge Dewatering Method Using the Same

The present invention relates to a high water content sludge dewatering material and a dewatering method using the same, and more particularly, to a high water content sludge dewatering material using exothermic and dewatering action by hydration reaction of neutralization heat and CaO.

Sewage sludge, wastewater sludge, purified water sludge, dredged sludge and mud sludge with high moisture content are representative environmental pollutants, which have been treated by ocean dumping, landfilling, etc., and now restore the environment contaminated by the pollutants. There are many ways to make it happen.

For example, sewage sludge discharged more than 6,000 tons per day has been banned from landfills since July 2003, and even the most easily disposed of dumping at sea is a London dumping treaty.

In particular, Korea, which has a narrow territory, should urgently seek efficient and safe treatment methods to prevent pollution of the surrounding environment and to prevent contamination of the leachate from sludge.

Currently, local governments around the country, including metropolitan landfills, are preparing a dehydration facility that manufactures artificial soil that can be used as a variety of ground materials such as cover soils, landfills, backfills, and backfills by reducing the water content of high-water sludges. As the dewatering treatment of the watery sludge is efficiently carried out, the development of excellent dehydrating materials in terms of productivity and economics is critical.

Conventional research on sewage sludge dewatering materials has caused problems of odor and reslurrying due to the use of strong alkaline materials such as quicklime and cement, as well as the addition of expensive acidic materials such as sulfuric acid and iron sulfate to supplement them. Although it aims to reduce ammonia emissions, it is not economically viable due to the high price of raw materials. In addition, attempts to solve the problem through the drying and curing of the treatment apparatus to compensate for the above material defects, but the treatment itself has a structure that causes a high cost and it is difficult to operate the heating curing plant smoothly.

In particular, CO ₂ of cement and calcium oxide is limestone _{(CaCO 3, CaO · CO 2} ) About 0.55 tons of carbon dioxide is emitted in the calcining process for decomposition, and about 0.40 tons of carbon dioxide is burned when burning fossil fuel in the firing process, and thus, about 1 ton of carbon dioxide is produced every time 1 ton of cement and quicklime is produced. _{2 The} concentration and the production of cement and quicklime are highly correlated.

The present invention has been made to solve the above-mentioned problems, an object of the present invention is to provide a high-functional sludge dehydrating material using the exothermic and dehydrating action by the hydration reaction of the heat of neutralization and CaO and a dewatering method using the same.

In order to solve the above technical problem, the high water content sludge dewatering material according to the present invention is based on 100 parts by weight of an alkali agent made of at least one of light dolomite or quicklime, and an oxidizing agent made of at least one of sodium alum, potassium alum and alumina sulfate 20 to 200 It includes parts by weight.

In addition, it is preferable to further include 250 to 1,000 parts by weight of the incineration residue having a calcium oxide (CaO) content of 20% to 70% with respect to 100 parts by weight of the alkali chemicals.

In addition, the incineration residue is one or a mixture of two or more selected from the group consisting of coal ash, biomass incineration residue, sewage sludge incineration residue, paper sludge incineration residue, RDF (Refuse Derived Fuel) incineration residue and RPF (Refuse Plastic Fuel) incineration residue. Is preferably.

High water sludge dewatering method according to the present invention comprises the steps of 1) preparing the dehydrating material of any one of claims 1 to 3; 2) mixing 5 to 100 parts by weight of the dehydrating material with respect to 100 parts by weight of high water content sludge; And 3) curing the mixture of the high water content sludge and the dehydrating material.

In addition, step 3) is preferably carried out by room temperature curing or heating curing the mixture.

In addition, the sludge is preferably any one of sewage sludge, wastewater sludge, purified water sludge, mud sludge and dredging sludge or a mixture of two or more.

According to the present invention, there is an effect that the water content of the high functional sludge is sharply lowered by using the heat of neutralization generated by the reaction of the alkali agent and the oxidant.

Furthermore, the effect of reducing moisture content is increased by the exothermic and dehydration action of CaO contained in light dolomite and quicklime or incineration residues.

In addition, by adjusting the pH to weak alkali effectively suppress the generation of ammonia is possible to reduce the odor.

1 is a photograph showing a mixture of a dehydrating material and a high water content sludge according to the present invention.
2 is a photograph showing a mixture of a dehydrating material and a high function sludge using only quicklime and incineration residues without using an oxidizing agent as a comparative example.

Hereinafter, a high water content sludge dewatering material and a dewatering method using the same according to the present invention will be described in detail.

First, the components and actions of the high water content sludge dewatering material according to the present invention will be described.

The high water content sludge dewatering material according to the present invention includes an alkali agent made of at least one of light dolomite or quicklime and an oxidizing agent made of at least one of sodium alum, potassium alum and alumina sulfate.

When the alkali and oxidants react with water contained in the high-functional sludge, a neutralization reaction occurs.

Oxidizing agents such as sulphates, alkalis such as quicklime and light dolomite cause rapid reactions and generate heat of neutralization. These heats lower the water content due to evaporation of the water contained in the high functional sludge.

In addition, the oxidizing agent not only plays a role of causing a neutralization reaction with the alkaline agent, but also exerts a cohesive effect to prevent adhesion to the facility when mixed with high-functional sludge, thereby improving facility mobility.

The mixing ratio of the alkali agent and the oxidant is preferably 20 to 200 parts by weight based on 100 parts by weight of the alkali agent. If the oxidizing agent is less than 20 parts by weight, the neutralization reaction does not occur sufficiently, so that the amount of neutralization heat is not generated and the effect of lowering the pH does not appear. In addition, when the oxidizing agent is more than 200 parts by weight, the amount of neutralization heat is generated so that the water evaporation effect is also less than expected, the pH is sharply lowered to reduce the ammonia, but on the contrary, it has a strong acidity.

The dehydrating material according to the present invention further includes an incineration residue having a calcium oxide (CaO) content of 20% to 70%.

Calcium oxide contained in a large amount in the incineration residue reacts with water to be absorbed, exothermic, and expand to form calcium hydroxide. Therefore, the water content of the high functional sludge can be reduced. The reaction scheme is as follows.

CaO + H ₂ O-> Ca (OH) ₂ + 15.6kcal mol ^-1

Although such calcium oxide is contained in the light dolomite, quicklime, and the like, it is preferable to utilize incineration residue having a calcium oxide content of 20% or more in terms of cost reduction and environmental aspects.

Although incineration residues are generally recycled to concrete admixtures, incineration residues containing a large amount of calcium oxide are incapable of being used as concrete admixtures because of their absorption, heat generation, and expansion characteristics.

Therefore, the present invention is to use incineration residues that can not be utilized as a concrete admixture.

That is, when the incineration residue containing a large amount of calcium oxide is mixed with the sludge having a high water content, the water of the sludge is reduced while calcium hydroxide is produced by the above reaction. In addition, since the heat generated by the above reaction evaporates the water of the sludge, it is possible to further reduce the water content of the sludge. Incineration residues containing 20% or more of calcium oxide include coal ash, biomass incineration residue, sewage sludge incineration residue, paper sludge incineration residue, RDF (Refuse Derived Fuel) incineration residue and RPF (Refuse Plastic Fuel) incineration residue.

The coal ash is produced a lot in the power plant, in particular, the coal ash produced in the power plant having a desulfurization method in the furnace has a high content of calcium oxide. In the furnace desulfurization method, coal and limestone are mixed and burned, so the coal ash contains a large amount of free CaO.

In contrast, coal ash produced in power plants with separate desulfurization facilities has less than about 7% calcium oxide.

Table 1 shows the differences between coal ash in power plants with separate wet desulfurization equipment and coal ash in power plants by furnace desulfurization.

Item Power plant coal ash with separate desulfurization Furnace  Desulfurization Power Plant Coal Ash Combustion fuel Coal (Import Bituminous Coal) Coal, limestone, waste tire (some power plants) Combustion temperature About 1350 ℃
-High combustion efficiency for economic power plant operation, reduction of coal ash generation rate and high quality coal ash discharge About 850 ℃
-Nitrogen emission reduction while decarbonation temperature range Exhaust Gas Desulfurization Facility Separate wet desulfurization facility Desulfurization Reaction with Limestone Mixture Exhaust gas denitrification plant Separate denitrification equipment Maintain low combustion temperatures and spray ammonia and other chemicals into boilers Chemical composition SiO _{2 ,} Al ₂ O _{3 ,} Fe ₂ O ₃ Due to limestone mixing
High free CaO component. Vitrification Degree high low Main recycling purpose Peak season with concrete admixture
Recycle all generation Clay substitute cement raw material,
Landfill of waste disposal site through long distance transportation Advantages and problems of using concrete admixture -Increased long-term strength with pozzolanic activity
- Improved workability
-Reduced unit quantity (durability, improved strength)
-Reduced heat of hydration (structure crack prevention) -Free CaO exothermic reaction
-Unit quantity increase (strength, durability decline)
-Increased heat of hydration (structure cracking)
-Reduced workability Etc KS L 5405 conformity product generation Do not satisfy the chemical composition and physical performance of KS L 5405

That is, the coal ash produced by the furnace desulfurization method contains a large amount of calcium oxide, but the coal ash produced in a facility equipped with a separate desulfurization device contains a very small amount of calcium oxide. Therefore, as described above, the coal ash produced in the facility equipped with a separate desulfurization device contains a small amount of calcium oxide, so that it does not have heat generation and absorption properties, and thus it can be recycled as a concrete admixture.

In other words, the incineration residue used in the dehydrating material of the present invention is a coal ash produced by the desulfurization method with a high CaO content.

At this time, it is preferable that 250-1,000 weight part of said incineration residues mix with respect to 100 weight part of said alkali chemicals.

If the amount of the incineration residue is less than 250 parts by weight, the amount of alkali and oxidant is relatively increased, and thus economic efficiency is insufficient. In particular, as the amount of powder of the incineration residue in the form of fine powder is insufficient, the viscosity of the dehydrating material and the high-functional sludge mixture It is increased and attached to the equipment, which affects the equipment mobility.

In addition, when the mixing amount of the incineration residue is more than 1,000 parts by weight, the mixing amount of the alkali agent and the oxidizing agent is relatively reduced, so that the neutralization heat is generated less and the water evaporation effect is reduced, thereby affecting the facility operability.

On the other hand, the incineration residue will contain unburned carbon, depending on the combustion environment, it usually contains 1 to 20%. The unburned carbon has a property of adsorbing ammonia gas and heavy metal generated when the dehydrated material is incorporated into the sludge because it is porous.

Hereinafter, a high water content sludge dewatering method according to the present invention will be described.

First, the above-described dehydrating material is prepared, and then 5 to 100 parts by weight of the dehydrating material is uniformly mixed with respect to 100 parts by weight of the sludge. If the dehydrating material is mixed at less than 5 parts by weight, the moisture content is not sufficiently reduced. If it is mixed at more than 100 parts by weight, the moisture content is too low, and the mixture is scattered, and transportation and laying operations are difficult.

Finally, room temperature curing or heating curing until the water content of the mixture of the sludge and the dehydrating material is less than 60%.

Example  One

With respect to 100 parts by weight of light dolomite, a dehydration material was prepared, which was composed of 70 parts by weight of alumina alumina and 600 parts by weight of RPF incineration residue having a calcium oxide content of 42%.

Next, with respect to 100 parts by weight of the dyeing wastewater sludge having a water content of 83.2%, 50 parts by weight of the dehydrating material was mixed to prepare artificial soil.

Example  2

With respect to 100 parts by weight of quicklime, a dewatering material was prepared, which was composed of 150 parts by weight of alum alum and 400 parts by weight of biomass incineration residue having a calcium oxide content of 22%.

Next, the artificial soil was prepared by mixing 20 parts by weight of the dehydrating material with respect to 100 parts by weight of sewage sludge having a water content of 82.3%.

Comparative example  One

With respect to 100 parts by weight of quicklime, a dehydration material was prepared, comprising 400 parts by weight of biomass incineration residue having a calcium oxide content of 22%.

Next, the artificial soil was prepared by mixing 20 parts by weight of the dehydrating material with respect to 100 parts by weight of sewage sludge having a water content of 82.3%.

Performance Test Method and Result of Artificial Soil

As shown in Table 2 below, the water content was measured by the KS F 2306 method and the compressive strength test was performed by the KS F 2343 method.

Experiment Way Remarks Water content KS F 2306 How to measure the water content of soil Compressive strength KS F 2343 Uniaxial compressive strength method

(1) water content change

The moisture content of artificial soils prepared by Examples 1, 2 and Comparative Example 1 according to time is shown in Table 3 below. As confirmed in Table 3, as the dehydrating material according to the present invention is mixed, the water content of the dyeing wastewater sludge was 83.2%, but it can be seen that the water content decreases rapidly over time. The moisture content is greatly reduced because, as described above, the exothermic reaction occurs immediately after the dehydrating material is mixed with the sludge and the hydration reaction proceeds simultaneously. In addition, the water content gradually decreases due to hydrate formation and natural drying over time. 1 is a photograph showing the appearance after 1 day of the mixture produced by Example 2, Figure 2 is a photograph showing the appearance after 1 day of the mixture produced by Comparative Example 1.

In Example 2, after one day of natural curing, strong cohesiveness disappeared and transferred to a physical state such as natural soil with a little moisture, but Comparative Example 1 still remained strong cohesive in sludge form and remained in a high water content mud state. have.

division Immediately after improvement 3 hours 1 day 3 days 5 days 7 days Example 1 53.5% 49.1% 47.0% 44.1% 41.3% 38.3% Example 2 62.9% 59.2% 51.3% 50.8% 47.5% 43.5% Comparative Example 1 63.1% 61.3% 54.9% 54.6% 50.2% 47.2%

(2) Uniaxial compressive strength  change

Table 4 shows the change in uniaxial compressive strength of the artificial soil prepared by Example 1, Example 2 and Comparative Example 1, respectively. As it can be seen from Example 1, showed the results of 1.5kgf / cm ^2, Example 2 is 1.21kgf / cm ^2, Comparative Example 1 is 0.47kgf / cm ² to cure 7 days. Example 1 and Example 2 is 0.5kgf / cm ² which is the strength standard of cover and fill material And values exceeding 1.0 kgf / cm ² and exhibited strength expressions that can be utilized as a lining material and various ground materials. This is because water absorption and the surface modification of the sludge occurs due to the absorption and heating reaction when mixed with the dehydrating material to achieve the consolidation promoting effect by the unity of the particles to enhance the strength. In addition, the water content of the sludge is relatively lowered by the absorbency of the dehydrated material, and the fine clay and colloidal components are separated by the absorbent and ion exchange, pozzolanic and carbonation reaction of the dehydrated material, and the particle size distribution is changed to improve the uniaxial compression. Strength is increased.

On the other hand, the dehydrating material in which the oxidant is not mixed in Comparative Example 1 does not generate heat of neutralization, so the initial moisture evaporation amount is small and there is no coagulation effect. I do not think it was.

division Compressive strength (kgf / cm ² ) 3 days 7 days 28 days Example 1 0.92 1.5 2.13 Example 2 0.89 1.21 1.93 Comparative Example 1 0.34 0.47 0.89

(3) before and after immersion Uniaxial compressive strength  change

When the artificial soil manufactured by the present invention is used as a daily cover material for landfills, it must have the required strength and at the same time, the reslurrification phenomenon and the strength reduction phenomenon caused by the inundation such as heavy rain and heavy snow, which are the climatic characteristics of Korea, should not occur. something to do. Therefore, in this experiment, the uniaxial compressive strength changes before and after 1 day immersion were investigated for artificial soils cured for 7 days.

The change in uniaxial compressive strength before and after immersion is shown in Table 5 below. As can be seen through this, the artificial soil prepared by Example 1 and Example 2 is -0.10kg / kg / cm ² , and the artificial soil prepared by Example 2 is -0.14kg / cm ^2. The rate of change of strength was shown. On the other hand, Comparative Example 1 showed a large decrease in strength compared to the Example according to the present invention of -0.26kg / cm ² .

As can be seen from the above results, the change in uniaxial compressive strength before and after immersion of the artificial soil produced by the present invention showed a relatively small decrease rate, which is obvious even when the sludge is changed to a dense crystal structure while generating a hydrate by dehydration treatment. It seems that absorption does not occur. Therefore, when the mixture prepared according to the present invention is used in landfills, reslurrying or strength deterioration in flooding due to snowfall is insignificant, and even when used as a cover material of landfills, it is expected that it will not significantly affect the operation of vehicles and equipment during rainy weather. .

Before immersion (kg /) After immersion (kg /) Intensity change Example 1 1.57 1.47 -0.10 Example 2 1.46 1.32 -0.14 Comparative Example 1 0.47 0.21 -0.26

(4) heavy metal elution

Table 6 below shows the heavy metal elution test results of the artificial soil prepared by Example 1. As can be seen from this, most of heavy metals were not eluted, and when applied to the waste dissolution test method in Korea, trace amounts of lead, mercury, and arsenic were detected, but the environmental standards were satisfied. This is because the heavy metal is substituted or fixed into the crystal structure by being fixed by the hydrate generated in the hydration reaction. Therefore, the dissolution concentration in all these experiments is much lower than the standard value or is not detected. Therefore, even if the sludge is dehydrated and used as daily cover material for landfills, secondary contamination due to heavy metal leaching is not considered to be a concern.

 Hazardous Substances
 Dissolution method CD As Pb Hg Cr ⁶⁺ Cu Org.P TCE PCE Waste Dissolution Test Method
(KSLP) standard 0.3 1.5 3.0 0.05 1.5 3.0 1.0 0.1 0.3 mixture N.D. N.D. N.D. N.D. N.D. 0.26 N.D. N.D. N.D. US EPA
(TCLP) standard 1.0 - 5.0 0.2 5.0 - - - - mixture N.D. - 0.004 N.D. N.D. - - - - * N.D: Not Detected

Claims (6)

A high water content sludge dewatering material comprising 20 to 200 parts by weight of an oxidizing agent made of at least one of sodium alum, potassium alum and alumina sulfate, based on 100 parts by weight of an alkali agent composed of at least one of light dolomite or quicklime.
The method of claim 1,
A high water content sludge dewatering material, characterized in that it further comprises 250 to 1,000 parts by weight of incineration residue having a calcium oxide (CaO) content of 20% to 70% by weight based on the alkali agent.
The method of claim 2,
The incineration residue is any one or a mixture of two or more selected from the group consisting of coal ash, biomass incineration residue, sewage sludge incineration residue, paper sludge incineration residue, RDF (Refuse Derived Fuel) incineration residue and RPF (Refuse Plastic Fuel) incineration residue. High water sludge dewatering material characterized in that.
1) preparing a dehydrating material of any one of claims 1 to 3;
2) mixing 5 to 100 parts by weight of the dehydrating material with respect to 100 parts by weight of high water content sludge; And
3) curing the mixture of the high water content sludge and the dewatering material; high water content sludge dewatering method comprising a.
The method of claim 4, wherein
Step 3) is a high water content sludge dewatering method characterized in that the mixture is carried out by heating or curing at room temperature.
The method of claim 4, wherein
The sludge dewatering sludge, wastewater sludge, purified water sludge, mud sludge and dredging sludge any one or a mixture of two or more of the high water content sludge.

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