KR20030024766A - The manufacturing method of block for sewage-sludge - Google Patents

Abstract

PURPOSE: Provided is a manufacturing method of pavement blocks excellent in bend strength and water absorption by using wastewater sludge generated from water purification plants. CONSTITUTION: The manufacturing method of pavement blocks comprises the steps of: firing dehydrated sludge, generated from wastewater facilities, at 850deg.C for 1hr, and cooling by blowing air; mixing 3-12kg(2.5-10.0wt.%, based on the mount of cement) of obtained sludge ash, 410kg of stone powder, 200kg of sand, 19kg of water and 120kg of cement.

Description

The manufacturing method of block for sewage-sludge}

The present invention manufactures a sidewalk block that helps human life rather than wastewater sludge, which is one of malignant wastes that is inevitably generated after treatment of sewage and wastewater discharged from various industries through a water treatment plant and the like. By applying recycling as a major member, it relates to a manufacturing method that provides double and triple advantages such as not only reducing the costs associated with the treatment of malignant waste, but also reducing production costs and improving quality.

In general, the sidewalk block has various shapes and types, and the materials used are also blocks made of various materials such as cement and waste synthetic resins, but the most widely applied cement is manufactured only from construction aggregates (sand, gravel, etc.). It is a sidewalk block. This is derived from the evaluation that it is the most suitable for reality based on the consideration of manufacturing cost, function, and quality, and in fact, it is almost a sidewalk block installed in the field.

However, as described above, since most of the materials are manufactured using only aggregate (sand, gravel, cement, etc.) as described above, the burden of manufacturing cost is considerably high considering that a small amount is consumed, and the strength and durability thereof are increased. In addition to the normal performance of the material can be expected in terms of quality, as well as far from the environmentally-needed eco-friendly requirements in the present day, the need for improvement is emerging at this time.

On the other hand, wastewater sludge is the waste that is collected during the treatment of wastewater discharged from various industrial sites through a water treatment plant or a wastewater treatment plant, and a large amount of waste is discharged nationwide. It is accompanied by environmental destruction.

In other words, sludge generated nationwide as of December 1999 was about 3.3 million tons, with 100,000 tons of industrial wastewater sludge, 7,000 tons of agricultural wastewater sludge, 1.17 million tons of sewage treatment sludge, and 1.8 million tons from other dischargers. Is being pulled. In addition, their treatment methods include landfilling, incineration and recycling in the order of 26.4% landfilling, 22.8% incineration, 12.8% recycling, and 38.1% offshore dumping. In the case of incineration, it is estimated to be about 0.8% in actual sewage treatment plants, and the rest is incinerated at the discharger. Since 2003, the government has banned the direct landfilling of sludge from sewage and wastewater treatment from 2003, but this will increase ocean dumping, but this is also planned to be banned in the future. I am in desperate need. The Waste Management Act proposes methods of incineration, solidification, composting, land cover or land reform as sludge treatment and disposal methods. In general sewage and wastewater treatment process, sludges are inevitably generated according to the treatment process, and the concentration of pollutants contained in these sludges is gradually increasing in proportion to the increase in efficiency of the treatment process. In terms of quantity, the sewage treatment rate is increasing in accordance with the government's clear water supply measures, and the quantity of sludge is also increasing at each emission company as the emission allowance standard is strengthened. In particular, the amount of sludge generated during the dyeing wastewater treatment process is large, and as a treatment method, all of them have been dumped at sea so that not only the pollution of the ocean but also many dyeing companies bear the sludge treatment cost. For example, Daegu Non-acid Industrial Complex is producing 120,000 tons of sludge per month and its disposal cost is more than W300mn per month. If sludge is included, the sludge volume and treatment costs will increase further.

In addition, until recently, the treatment of sludge from sewage and wastewater treatment plants has been dewatered and reclaimed directly or relying on ocean dumping.However, in the case of landfill, it is difficult to secure landfills. Various harmful heavy metals remain in the soil, contaminating groundwater and surface water and causing increased leachate. In the case of dumping at sea, new measures have to be taken, as the international level is being banned to protect shared seas. In accordance with this trend, recently, the government has attempted to use it for various purposes in terms of governmental recycling.

On the other hand, since the main components of the sludge generated in the sewage and wastewater treatment plant consists of inorganic components and organic components, the organic components are volatilized, i.e., gasified during incineration, and most of the inorganic components are composed of soil powder. Since these sludges pay a certain cost per ton of treatment, other economic treatment methods are required. In advanced countries, incineration is generally used as a method of reducing and stabilizing sludge, but research on the treatment of incineration ash, a by-product, is ongoing. In Korea, sewage and wastewater sludge is expected to be converted to incineration in the long term, and development of technology for incineration ash generated in such a case is urgent.

In addition, the Korean Waste Management Act seeks to manage and treat sludge from various sewage and wastewater treatment facilities by setting a limited period of time according to the facility size. Organic sludge (organic substance content of 40% or more) among general wastes generated at the workplace is incinerated or dehydrated and dried to 75% or less of water, and then landfilled in a managed landfill facility, but in the future, incineration, solidification, composting, It is regulated to treat and use landfill cover material and land improvement system. So it's time for a new approach.

Therefore, by using wastewater sludge, which is one of the malignant wastes that causes enormous cost waste due to environmental destruction and treatment in the present invention, as a major constituent raw material in the manufacture of the sidewalk block, it is also possible to promote scaffolding of wastewater sludge, which is a malignant waste, as well as sidewalk blocks. It is a technical task that focuses on providing the manufacturing method that provides the side effects such as quality improvement (strength, durability, etc.) and manufacturing cost reduction.

In order to achieve the above technical problem, the present application suggests the following specific manufacturing methods and experiments.

That is, the manufacturing process of the wastewater sludge press block of the present invention largely proposes the press block manufacturing process of the sludge firing process and the mixing process of aggregate, cement and sludge, forming process, curing process, etc. The quality evaluation stages such as bending strength measurement, water absorption rate measurement, SEM analysis, and elution degree evaluation of the sludge press block were analyzed. Hereinafter, it is as follows.

1. Before producing the press block, first, dewatered sludge from wastewater treatment plant or water treatment plant is collected and calcined for about 1 hour through a sintering furnace.The firing condition is performed at 850 ℃, which is a general sludge incineration condition. The heat source used is liquefied petroleum gas (LPG) and at the same time heated up to 850 ° C. over 2 hours, then air is introduced into the contents to cool over 2 hours 30 minutes to obtain the final calcined sludge ash.

The sludge material thus obtained was manufactured by mixing it with stone powder, sand, cement, and water in three ways, as follows.

Example 1

410 kg of stone powder, 200 kg of sand, 19 kg of water, and 120 kg of cement were mixed together with 3 kg of sludge ash (2.5% by weight of cement input).

Example 2)

Stone powder 410kg, sand 200kg, water 19kg, cement 120kg, sludge 6kg (5.0% by weight of the cement input) was molded and manufactured,

Example 3

Stone powder 410kg, sand 200kg, water 19kg, cement 120kg, sludge 12kg (10.0% by weight compared to the cement input) was prepared by molding.

The molding process is a continuous vibratory compression molding machine, and the molding conditions were simultaneously supplied with vibration and compression to increase the compressive strength as shown in <Table 1>, and the mixture was supplied in the first and second parts.

The molded press block is subjected to curing, which is an important process in the development of compressive strength.

The curing process is similar to the outside air at the curing room temperature is 10 ℃ and cured in an environment that blocks the flow of air and the curing days were 3 days, 7 days, 14 days, 28 days.

〈Table 1〉 Vibration compression molding condition

2. Evaluation of Press Block Production Results

The produced sidewalk blocks shall meet the standards of the sidewalk blocks set by the Korean Industrial Standards. The standards of the press block set by the Korean Industrial Standard (KSF4419) are shown in <Table 2>. In other words, the width and length of the deviation should be ± 2mm or less, the thickness should be ± 3mm, the flexural strength should be 50kg / cm ² or more and the absorption rate should be within 7% on average.

<Table 2> Standards of the sidewalk blocks specified by the Korean Industrial Standards

(1) flexural strength

In general, the most important factor in the evaluation of the quality of the manufactured sidewalk blocks is the use of bending strength and water absorption. These indicators are an important factor in evaluating the recyclability of building and civil engineering materials on specimens. The method of measuring flexural strength specified in Korean Industrial Standards can be expressed as Equation (1).

Where P is the maximum fracture load (N) indicated by the tester.

ℓ: Distance between points (mm)

b: Average width of the points perpendicular to each other (mm)

d: average thickness of blocks (mm)

The result of measuring the bending strength of the sidewalk block manufactured according to the above equation is shown in <Figure 1>, and the bending strength of the specimen according to the curing time was in accordance with the Korean Industrial Standard.

Bending strength in accordance with the sludge / cement ratio measurement results. However to 25kg / cm ² at 30kg / cm ^2, 10.0% at 34kg / cm ^2, 5.0% from 2.5% in the third day the specimen below the Korea Industrial Standard 50kg / cm ² 7 day Among the specimens, 2.5% to 55kg / cm ² , 5.0% to 50kg / cm ² , and 10.0% to 46kg / cm ² , 2.5% and 5.0% met Korean Industrial Standard 50kg / cm ² . Some of the specimens increased slightly in strength as the curing period progressed, but the degree was almost insignificant. Therefore, in the case of manufacturing the press block by firing the dyed sludge, it can be seen that if the sludge / cement ratio is mixed with 2.5% and 5.0%, respectively, after 7 days of curing period, the flexural strength that can be recycled into construction and civil engineering materials can be obtained. .

(2) Absorption rate

In the case of absorption rate defined by the Korean Industrial Standards, the individual sidewalk blocks should be less than 10% and less than 7% on average, and the measurement method can be expressed as shown in (2).

Where m ₁ : dry weight of the sample (g)

m ₂ : Saturation weight of the sample (g)

The absorption rate was measured by drying the sidewalk block at a temperature of 100 to 110 ° C for at least 24 hours in a drier and drying it until the weight difference measured between two hours did not exceed 0.2% of the sample measured beforehand. The weight was measured by cooling over time. Thereafter, the sample was immersed in water at 15.5 to 30 ° C. for at least 24 hours, and then the sample was taken out, and the surface water was wiped with a cloth and then weighed.

According to the measurement method, the measurement result of absorption ratio according to sludge / cement ratio is shown as 6.8%, 5.0%, 6.5%, 10.0%, and 6.3% in 2.5% of specimens on the first day as shown in <Table 3> and <Figure 2>. The average rate was 7% (10% each) set by Korean Industrial Standards. As the curing period elapsed, there was a change in absorption rate but the change was moderate.

<Table 3> Absorption rate of sidewalk blocks

Therefore, it was found that when the press block was manufactured by calcining the wastewater treatment sludge, the absorption rate which can be recycled as a construction and civil engineering material was obtained when the sludge / cement ratio was mixed with 2.5%, 5.0% and 10.0%, respectively.

(3) Dissolution test

In order to evaluate the dissolution degree of heavy metals, the dissolution test was performed. In addition, the significance of the dissolution test is to estimate the dissolution of heavy metals and harmful substances in the surrounding area when using the sidewalk block as a civil engineering and building material, and to predict how much and how long the hazardous substance is released from the sidewalk block. Can be used. The dissolution test was conducted in accordance with the Waste Management Act, and the experimental process is shown in <Figure 3>.

As an analytical sample, crushed specimens measured at flexural strength to 2 to 9.5 mm, and then immersed in 1000 ml of eluting solvent with pH 5.8-6.3 in 100 g of the specimen. It was. As an analyzer for heavy metals, the atomic absorption photometer of SHIMADZU company AA-6401F was used.

Table 8 shows the results of the dissolution test on 11 items including Cu on the coverage block. The results of the dissolution according to the mixing ratio showed that some of Si, Al, and Cr were generally detected, and in particular, Al and Si were most of the residues because the sludge was incinerated at 850 ° C for 1 hour for many reasons. . On the whole, it was difficult to find a special trend according to the mixing ratio of sludge and cement.

<Table 4> Dissolution test results for sidewalk block specimens

As described in detail above, the press block manufacturing method using the wastewater sludge of the present invention has a curing period of 7 days when mixing 2.5% and 5.0% of the cement input amount, respectively, as can be seen from the test results of the specimen prepared through the above examples. After this, not only the sufficient flexural strength as a sidewalk block was obtained, but also the amount of sludge to 2.5%, 5.0%, and 10.0% of cement input, respectively, was enough to burn the wastewater sludge. It can be seen that if manufactured, it can be recycled sufficiently.

Claims (1)

In manufacturing the sidewalk block, 3 ~ 12kg (2.5% ~ 10.0% by weight of cement input) of sludge obtained by firing dehydrated sludge from wastewater treatment plant or water treatment plant together with 410kg of stone powder, 200kg of sand, 19kg of water and 120kg of cement are mixed together. Press block manufacturing method using wastewater sludge, characterized in that the molding production.