KR100423410B1 - Stabilization material of sewage sludge - Google Patents

Abstract

The present invention relates to a solidifying agent for solidifying industrial wastewater and sewage sludge, and a sewage sludge solidifying body mainly used as an intermediate cover material in sanitary landfills, and a solidifying agent composed of blast furnace slag powder and semi-mineral gypsum and / or anhydrous gypsum and using the same. It is to provide a sewage sludge solidified solidified sewage sludge, the purpose is to.

The present invention for achieving the above object,

In the sewage sludge solid obtained by adding and mixing solidifying agent to sewage sludge,

The solidifying agent is composed of blast furnace slag fine powder and hemihydrate gypsum and / or anhydrous gypsum,

The blast furnace slag fine powder is 5 to 20 parts by weight based on 100 parts by weight of the sewage sludge, and

The content of the hemihydrate gypsum and / or anhydrous gypsum is 10 to 30 parts by weight based on 100 parts by weight of sewage sludge,

3 parts by weight or less of quicklime based on 100 parts by weight of the sewage sludge as a pH adjusting agent, and 20 parts by weight or less of briquette material based on 100 parts by weight of the sewage sludge as admixtures. Make a point.

Description

Sewage sludge solidified body {STABILIZATION MATERIAL OF SEWAGE SLUDGE}

The present invention relates to a solidifying agent for solidifying industrial wastewater and sewage sludge, and a sewage sludge solidifying body mainly used as an intermediate cover material in sanitary landfills, and more particularly, a solidifying agent capable of reducing the occurrence of odor from the solidified body and using the same. It relates to the sewage sludge solidified body obtained.

Conventionally, sewage sludge is landfilled with general waste after dewatering. However, due to the high water content of sewage sludge and the inclusion of organic matter, it is difficult to enter a work vehicle and it is difficult to mix landfill due to the change of the characteristics of general wastes according to the change of living standard, so appropriate disposal measures are required. . In order to solve such a problem of sewage sludge disposal, in recent years, it has been considered to solidify the sewage sludge cake to facilitate the landfill work, or to utilize it as an intermediate cover material in a single landfill or sanitary landfill. Among them, in the method of solidifying sewage sludge cake, a special cement is used as a solidifying agent, which is excellent in solidifying effect, but most of them are expensive alumina-based cements. As another method of solidification, the technique disclosed in Korean Patent Publication No. 97-8689 is a method of utilizing solid wastes such as incinerator, cement kiln dust, fly ash, steelmaking slag, etc., which can serve as a solidifying agent and a solidifying aid. In order to promote economic efficiency by lowering the use ratio, there was a problem that a severe ammonia odor occurs in the solidified solidified body. That is, as in the above technique, when the solidification treatment using cement and quicklime as the main raw material as a solidifying agent, the pH of the solidified solids increases, ammonia odor is generated from the solids and does not disappear even after several years of solidification. It will continue to occur. In addition, even when such a solid is used as a cover material, there is a lack of field workability due to the generation of odor.

Accordingly, the present inventors have repeatedly conducted research and experiments to solve the above problems, and propose the present invention based on the results, and the present invention is composed of blast furnace slag fine powder, hemihydrate gypsum and / or anhydrous gypsum. The present invention aims to provide a sewage sludge solidified body which has been solidified by treating the sewage sludge with the same.

The present invention for achieving the above object,

It relates to a solidifying agent composed of 14.3 to 66.7% by weight of blast furnace slag powder and 33.3 to 85.7% by weight of hemihydrate gypsum and / or anhydrous gypsum, wherein the quickener is a pH adjusting agent based on 100 parts by weight of the It may further contain up to a weight part.

In addition, the present invention,

In the sewage sludge solid obtained by adding and mixing solidifying agent to sewage sludge,

The solidifying agent is composed of blast furnace slag fine powder and hemihydrate gypsum and / or anhydrous gypsum,

The blast furnace slag fine powder is 5 to 20 parts by weight based on 100 parts by weight of the sewage sludge, and

The content of the hemihydrate gypsum and / or anhydrous gypsum relates to the sewage sludge solidified body is 10 to 30 parts by weight based on 100 parts by weight of sewage sludge.

The sewage sludge solidified body of the present invention may further contain 3 parts by weight or less of quicklime as a pH adjusting agent and 100 parts by weight of quicklime, and a briquette material of 20 parts by weight or less as a admixture.

The sewage sludge solidified body of the present invention preferably has a pH of 6 to 9 and a uniaxial compressive strength of 0.5 kgf / cm 2 or more.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The inventors of the present invention have studied and examined odors that had been a problem when solidifying industrial wastewater, in particular, sewage sludge for use as an intermediate cover material in sanitary landfills. I found out. That is, the conventional sewage sludge solidifying agent uses a high basicity of portland cement represented by CaO / SiO ₂ as its raw material, thereby raising the pH of the resulting solid to 10 or more, causing severe odor.

Accordingly, the inventors have investigated and experimented with raw materials of low basicity and low cost solidifying agent, and found out that blast furnace regrind slag fine powder, which is a by-product of steel production, may be appropriately used. That is, the blast furnace slag fine powder not only solidifies industrial wastewater, for example, sewage sludge, but also functions to stabilize sewage sludge by solidifying heavy metals contained in sewage sludge. Such blast furnace slag fine powder is usually 93 to 98% of CaO, SiO ₂ , Al ₂ O ₃ , MgO and the like, and is composed of other small amounts of SO ₃ , Fe ₂ O ₃ , MnO and alkali. Is as shown in Table 1 below.

(Unit: weight%) CaO SiO ₂ Al ₂ O ₃ MgO SO ₃ Fe ₂ O ₃ 42.4 33.1 13.8 6.1 - 0.29

In addition, the inventors of the present invention, when the blast furnace slag fine powder is added to the blast furnace slag fine powder to the presence of an stimulant of alkali or sulfate to sufficiently present the OH ^- ions or SO ₄ ^2- ions, the blast furnace slag fine powder exhibits hydraulic properties like portland cement It was found that CaO-SiO ₂ -H ₂ O based crystal phases were formed and cured. Thus, hemihydrate gypsum and / or anhydrous gypsum that provides SO ₄ ^2- ions was used as the stimulant. Meanwhile, in the present invention, quicklime selectively added as a pH adjusting agent may also serve as a stimulant for the blast furnace slag fine powder to exhibit hydraulic properties.

When the hemihydrate gypsum and anhydrous gypsum react with water, it causes and hardens a hydration reaction as shown in the following Reactions (1) and (2), which is exothermic.

Scheme 1

CaSO ₄ 1 / 2H ₂ O + 3 / 2H ₂ O = CaSO ₄ 2H ₂ O + 4,600 ± 20 cal / mol (Half plaster)

Scheme 2

CaSO ₄ + 2H ₂ O = CaSO ₄ 2H ₂ O + 7,210 ± 10 cal / mol (anhydrous gypsum)

That is, when half-hydrated gypsum or anhydrous gypsum is added as a raw material for industrial wastewater, in particular, sewage sludge solidifying solidifying agent, when the sewage sludge solidifies, it reacts with about 80 parts by weight of water contained in the sewage sludge to reduce the water content of the solidified body. To act. As a result, the strength of the solidified body is improved.

In the present invention, the hemihydrate gypsum or anhydrous gypsum can be used as a raw material of phosphate gypsum, desulfurized gypsum, or gypsum from industrially generated by-products generated during neutralization of SO ₄ ^2- ions. It is not limited only to the above.

The solidifying agent of the present invention as described above is preferably composed of blast furnace slag fine powder of 14.3 to 66.7% by weight and hemihydrate gypsum and / or anhydrous gypsum of 33.3 to 85.7% by weight, because the content of the blast furnace slag fine powder This is because when the pH of the solid is 66.7% or more, the odor occurs due to the increase of the pH of the solid, and when it is less than 14.3%, the uniaxial compressive strength decreases to less than 0.5 kgf / cm 2. In addition, when the content of the hemihydrate gypsum and / or anhydrous gypsum is less than 33.3%, strength is difficult to express, and when the content of the hemihydrate gypsum and / or anhydrous gypsum is less than 85.7%, the content of the fine blast furnace slag fine powder is relatively low, thereby fixing the heavy metals in the waste water by the blast furnace reclaiming slag and the wastewater. There is a problem that the stabilization effect is reduced. In addition, the quickener may further contain quicklime as a pH adjusting agent, if the content is more than 20 parts by weight based on 100 parts by weight of the solidifying agent composed of blast furnace regrind slag powder and hemihydrate gypsum and / or anhydrous gypsum It is not preferable because the pH of the solid is increased to 10 or more.

On the other hand, when the solidifying agent of the present invention is used for the solidification of industrial wastewater, in particular, sewage sludge, the odor generated from the sewage sludge solidified body can be reduced, and the mechanism will be described below.

The causes of ammonia odor during solidification of sewage sludge are as follows. That is, when the sewage sludge (self pH: 6 ~ 7) is solidified by using a cement and quicklime-based solidifying agent, ammonium ions (NH ₄ ⁺ ) in the sewage sludge are converted into ammonia gas (NH ₃ ). Basic odor gas such as ammonia gas is caused to emit a specific odor. The conversion of ammonium ions into ammonia gas in sewage sludge is affected by pH. At pH 9, ammonia gas (NH ₃ ) and ammonium ions (NH ₄ ⁺ ) remain in equilibrium, but when the pH is above 9 Ions are converted to ammonia gas and released into the atmosphere.

In view of the advantages of the present invention, in order to manage the pH of the sewage sludge solidified to 9 or less, a weak alkaline solidifying agent is used as a solidifying agent instead of a high alkaline solidifying agent such as cement quicklime. However, the solidified body preferably has a pH of 9 or less in terms of odor generation, but when the temperature is lowered to 6 or less, hydrogen sulfide gas is generated. Therefore, the lower limit is preferably set to 6.

As described above, when the solidifying agent of the present invention is used to solidify sewage sludge, the solidifying agent of the present invention is preferably set based on the content of sewage sludge. That is, among the solidifying agent of the present invention composed of fine blast furnace slag powder and hemihydrate gypsum and / or anhydrous gypsum, the content of the fine blast furnace slag powder is 5 to 20 parts by weight, 100 parts by weight of the sewage sludge, and the hemihydrate gypsum and / or The content of anhydrous gypsum is preferably set to 10 to 30 parts by weight based on 100 parts by weight of sewage sludge. The reason for this is that when the content of the blast furnace slag fine powder in the solidifying agent is less than 5 parts by weight with respect to 100 parts by weight of sewage sludge, the uniaxial compressive strength decreases after 3 days of curing and the pH is increased when the content is 20 parts by weight or more. This is because ammonia ions in the sludge become ammonia gas and odor is generated. In addition, when the content of the semi-hydrated gypsum and / or anhydrous gypsum is less than 10 parts by weight based on 100 parts by weight of sewage sludge, the water content of sewage sludge is high, the strength is difficult to express strength, the content of the fine blast furnace slag fine powder is more than 30 parts by weight This lowers the problem that the solidification and stabilization effect of heavy metals in the sewage sludge by the blast furnace slag is reduced.

In addition, the sewage sludge solidified body may further contain quicklime of 3 parts by weight or less based on 100 parts by weight of the sewage sludge as a pH adjusting agent, and briquette material of 20 parts by weight or less as a admixture. At this time, when the content of quicklime is 3 parts by weight or more with respect to 100 parts by weight of sewage sludge, the pH of the solid is increased and ammonia gas is generated, causing a bad smell, and the content of the briquette material is 100 parts by weight of sewage sludge. In the case of 20 parts by weight or more, the strength of the sewage sludge solidified body is lowered, which is not preferable.

On the other hand, the briquettes are separately collected and crushed after briquettes and briquettes which are already embedded in the landfill, and added as a admixture during sewage sludge solidification. . When the briquette is added before the solidifying agent, the initial water content of the sewage sludge is reduced, the internal frictional force of the solidified body is increased, and the porosity is increased, thereby helping to cure the solidified body.

Sewage sludge solidified body prepared as described above can be mainly used as cover material in sanitary landfill, the requirements that can be utilized as cover material is as follows.

First, in order to smoothly landfill the solidified sludge, the solidified body should have a strength that does not interfere with the operation of the working vehicle. In general, the limiting strength is 0.5% of the uniaxial compressive strength since the bulldozer is generally used for the landfilling work. kgf / cm 2 or more. Therefore, the sewage sludge solidified body of the present invention preferably has a uniaxial compressive strength of 0.5 kgf / cm 2 or more.

Next, from the environmental point of view, the sewage sludge solidified body should have long-term stability after being buried. Such stability evaluation can be confirmed by performing dissolution test on solidified sludge, and it should not exceed the regulation value as a result of dissolution test of heavy metal of solidified body.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1

As shown in Table 2, the semi-mineral gypsum was added to the sewage sludge, followed by primary mixing, and then the blast furnace slag fine powder was mixed for the second time, and the amount of ammonia gas generated immediately after the final mixing was investigated, and the results are shown in Table 2 below. It was. The first and second mixing was carried out using a hammer crusher mixer, the mixture was in the form of soil. Some of the samples were taken immediately after the mixing to measure pH and the results are shown in Table 2 below. Thereafter, natural curing is made of a cover material, after three days of curing, uniaxial compressive strength was measured, and the results are shown in Table 2 below.

At this time, the semi-hydrated gypsum used is made by drying the by-product gypsum generated during the production of phosphate.

division Solidifying material (parts by weight) Right after production After 3 days dry health Sewage Sludge Half gypsum Blast Furnace Slag Powder quicklime cement pH NH ₃ (ppm) Uniaxial compressive strength (kgf / ㎠) Comparative Example 1 100 15 18 12.5 600 0.53 Comparative Example 2 100 10 30 12.0 550 0.62 Comparative Example 3 100 20 3 7.0 20 0.25 Comparative Example 4 100 5 25 11.3 520 0.45 Inventive Example 1 100 23 10 8.3 60 0.65 Inventive Example 2 100 23 * 10 8.4 65 0.63

As shown in Table 2, in Comparative Example (1) in which the sewage sludge was solidified by using a cement-quick lime hardener commonly used, the pH of the solid was immediately high after the solid production. . This caused severe odors.

In Comparative Example (2), when the blast furnace slag fine powder in the solidifying agent was excessively added, ammonia odor was generated due to the high pH of the solidified body.

Comparative Example (3) is a case where the content of blast furnace slag fine powder is small, the odor occurred immediately after production, but there was a problem that the uniaxial compressive strength decreased after three days of curing.

In addition, Comparative Example (4) is a case where the content of half-gyre gypsum is small and the blast furnace slag fine powder is excessively added. It became high and ammonia odor was generated.

On the other hand, inventive examples (1), (2) of the present invention showed a pH of 6 to 9 immediately after solidified body production and uniaxial compressive strength of 0.5kgf / cm 2 or more.

Example 2

Into the sewage sludge was added to the solidifying agent as shown in Table 3 and then cured to make a solid, and the pH, ammonia gas, and uniaxial compressive strength was measured in the same manner as in Example 1, and the results are shown in Table 3 below. It was. At this time, the quicklime used as a pH adjuster is a by-product produced by the production of quicklime using limestone as a raw material.

division Solidifying agent (parts by weight) Right after production After 3 days dry health Sewage Sludge Half gypsum Blast Furnace Slag Powder quicklime pH NH ₃ (ppm) Uniaxial compressive strength (kgf / ㎠) Inventive Example 3 100 25 10 One 8.5 90 0.65 Inventive Example 4 100 25 10 3 8.9 120 0.66 Comparative Example 5 100 25 10 5 10.1 450 0.69

As shown in Table 3, Inventive Examples (3) and (4) were added to 3 parts by weight or less with respect to 100 parts by weight of quicklime as a pH control agent, which helped to express the strength of the hemihydrate gypsum, solidified body By lowering the pH to below 9 it was possible to suppress the occurrence of odor in the field during the manufacture of a solid. In addition, when curing was used as a cover material, it was possible to suppress the generation of ammonia odor.

On the other hand, in Comparative Example (5) in which excessive quicklime was added, the pH of the solidified body was high immediately after production, resulting in ammonia gas, resulting in odor.

Example 3

In order to examine the effect of the admixture on the production of sewage sludge solidified body, as shown in Table 4 below, a solidifying agent, quicklime, and briquettes are added to sewage sludge to solidify sewage sludge, and the pH is the same as in Example 1. , Ammonia gas amount, and uniaxial compressive strength were measured, and the results are shown in Table 4 below. At this time, the briquette material used as the admixture was a pulverized fractionation of the briquette material or the briquette material currently loaded, and the particle size after fractionation pulverization was 5mm or less.

division Solidifying material (parts by weight) Right after production After 3 days dry health Sewage Sludge Half gypsum Blast Furnace Slag Powder Briquettes quicklime pH NH ₃ (ppm) Uniaxial compressive strength (kgf / ㎠) Inventive Example 5 100 20 10 20 One 8.3 58 0.62 Comparative Example 6 100 25 10 40 One 8.2 56 0.35

As shown in Table 4, Inventive Example (5) the briquette material to increase the porosity of the solidified body to help the curing of the solidified body, and serves to lower the water content of the solidified body.

However, in the comparative example (6) in which the briquette material was added excessively, the uniaxial compressive strength of the sewage sludge solidified body fell.

According to the present invention as described above, it is economical because steel production by-products and various industrial by-products are used as a solidifying agent, and it is possible to reduce the occurrence of odor in the field of solidifying sewage sludge using the solidifying agent and in the solidified state after curing. Therefore, when used as intermediate cover material at the time of sanitary landfill will have the effect of preventing environmental pollution.

Claims (5)

delete delete In the sewage sludge solid obtained by adding and mixing solidifying agent to sewage sludge, The solidifying agent is composed of blast furnace slag fine powder and hemihydrate gypsum and / or anhydrous gypsum, The blast furnace slag fine powder is 5 to 20 parts by weight based on 100 parts by weight of the sewage sludge, and The content of the hemihydrate gypsum and / or anhydrous gypsum is 10 to 30 parts by weight based on 100 parts by weight of sewage sludge, 3 parts by weight or less of quicklime based on 100 parts by weight of the sewage sludge as a pH adjusting agent, and 20 parts by weight or less of briquettes based on 100 parts by weight of the sewage sludge as admixtures. delete The sewage sludge solidified body according to claim 3, wherein the solidified body has a pH of 6 to 9 and a uniaxial compressive strength of 0.5 kgf / cm 2 or more.