KR100575077B1 - A recycling method of waste water produced during manufacturing concrete products - Google Patents

Abstract

The present invention is 1) to separate and separate the equipment washing water and curing tank waste water discharged from the concrete product manufacturing plant; 2) Equipment washing waste water is treated by chemical wastewater treatment in a wastewater treatment plant according to a conventional method, or sludge such as aggregate or cement is removed by physical wastewater treatment, or precipitated and filtered to be removed, and the supernatant water is recycled to equipment washing water; 3) A method of recycling wastewater generated in the concrete product manufacturing process, wherein the curing tank wastewater, which is about 90% of the total wastewater, is recycled to high boiler water having high alkaline energy or recycled to concrete mixing water. By the method of the present invention, energy can be drastically reduced, wastewater generation can be drastically reduced, recycled, environmental burdens can be reduced, and a small wastewater treatment plant can be operated, thereby significantly reducing investment costs. .

Equipment washing water, curing tank waste water, equipment washing waste water, strong alkaline, recycling

Description

A recycling method of waste water produced during manufacturing concrete products}

The present invention relates to a method for recycling wastewater generated in a concrete product manufacturing process.

Ready-made concrete products produced at the factory include high strength concrete piles, concrete poles, sleepers, fume pipes, PC pipes, plum pipes, bricks, blocks, etc., and these products are usually used as basic materials for construction sites.

 The manufacturing process of these concrete products is reinforcement (reinforcement in the mold) ⇒ mixing process (cement, sand, gravel, water, etc.) ⇒ feeding process (injecting fresh concrete into the mold) ⇒ compaction molding process (by vibration or centrifugal force) Concrete compaction molding) ⇒ Steam curing process (Spray steam to concrete to express concrete strength early) ⇒ Demolding process (separate product from the mold) ⇒ Correcting, marking (finishing and printing of letters) ) ⇒ It is classified into shipping process.

 Curing concrete is a measure to promote the hydration reaction between cement and water. To make high-quality concrete with high strength and cracks, it is necessary to maintain sufficient wet conditions at a proper temperature. This is called.

 The purpose of curing is to keep the concrete close to the catcher until the space, which had not yet been hardened, was originally filled with water and filled with the hydration product of cement.

 Steam curing, which is an important process of wastewater generation in the present invention, involves spraying steam around a concrete in a confined space (curing tank) and heating it in a wet state (atmospheric steam curing: 75-90 ° C., high pressure steam curing: about 10㎏ / ㎠ 180 ℃) is a curing method that promotes hydration reaction, condensation, and hardening of concrete. This increases the speed of strength increase as the curing temperature of concrete increases, so the strength of concrete is rapidly increased by steam curing. Since it is a product of high strength within a short time after striking concrete, it is a curing method that is favored mostly by many economic effects such as reduction of mold turnover, required amount of storage, reduction of yard space, and reduction of inventory cost.

 As described above, the steam curing of concrete requires not only the heat of steam but also moisture, and the hydration reaction of cement that is not supplied with water is extremely low, and it is destroyed only by the expansion of concrete materials and micropores by heat. Water is transferred to concrete hardening, part of which evaporates into the atmosphere, and most of it transfers latent heat of steam and changes into alkaline contaminated wastewater by hydration of strong alkali cement.

 This curing tank waste water is alkaline (pH8.5 ~ 11) waste water of high temperature (55 ~ 95 ℃) by hydration reaction of cement with strong alkali (pH11 ~ 12), and it is more than 90% of the total wastewater generated in the manufacturing process. The water quality of wastewater is somewhat different depending on the manufacturing method of the product and the water treatment method of the boiler water, but the water quality of M alkali, total hardness, chlorine ion and phosphoric acid is good except for pH (hydrogen ion concentration).

 If the wastewater generated in this way remains in the steam cultivation tank, it is a major obstacle to the heat transfer of the steam (water conductivity is 1/90 of the metal is low), which is immediately discharged to increase the heat transfer efficiency and reduce the amount of wastewater generated. For this reason, the waste water of alkaline curing tanks is naturally hot.

 Another manufacturing process wastewater

  1) Extremely poor quality alkaline washing equipment with high concentration of residual amount of concrete (sand, gravel, cement) from concrete mixing and concrete input process

  2) Extremely poor quality of facility washing wastewater generated by excessive concentration of foreign matter such as leitans sludge and cement paste and oil generated in compaction molding process (vibration and centrifuge). It is extremely poor water quality and waste water that does not contain thermal energy.

 Conventionally, various types of wastewater are not classified and separated according to their characteristics, and the waste water quality (a large amount of cement and sand, sludge, oil, etc.) is treated by mixing a small amount of wastewater with extremely poor water quality and a large amount of good quality wastewater. It is difficult to recycle due to the overconcentration of foreign matters and waste of excessive wastewater treatment costs due to the large amount of wastewater treatment.

 In some cases, mixed wastewater is recycled as mixed water, but concrete strength and other problems due to turbid water are avoided, and use is avoided. Or it is lost.

 In some cases, only a portion of heat (20-30%) is recovered through a heat exchanger, and the wastewater containing a large amount of high temperature thermal energy is discharged to a stream through chemical water treatment at a wastewater treatment plant, or the mixed wastewater is chemically purified and recycled. By disposing of reusable thermal energy and water, it has become the main culprit of waste water treatment cost, excessive oil energy waste and environmental destruction.

As such, alkaline wastewater containing high thermal energy is neutralized at a cost and disposed of. Instead, the temperature (10 ~ 20 ℃) is low so that there is no energy and only groundwater and tap water having a pH of 6 ~ 9. In order to re-supply industrial water and make it into suitable boiler water, alkali treatment is performed again to supply strong alkaline boiler water with pH (9.4 ~ 11.8), so that water of low temperature (10 ~ 15 ℃) is weak. To produce steam with 174 ℃, it consumes a large amount of fuel (oil) to raise the temperature to about 160 ℃, and it consumes excessive fuel unnecessarily to increase fuel cost and unnecessary wastewater treatment, and thus air and water pollution. It is increasing and wasting and disposing of high thermal energy water.

The present invention provides a method for recycling strong alkaline wastewater generated in the concrete product manufacturing process.

The present invention is to provide a method for recycling the strong alkaline wastewater generated in the concrete product manufacturing process.

   The method of the present invention

    1) separate the facility washing wastewater and curing wastewater, which is about 10% of the total wastewater;

    2) Equipment washing waste water is treated by chemical wastewater treatment in a wastewater treatment plant according to a conventional method, or sludge such as aggregate and cement is removed by physical wastewater treatment, or precipitated and filtered, and the supernatant water is recycled to equipment washing water. ;

   3) Concrete products, which account for about 90% of the total wastewater, are expensive industrial water with alkaline high thermal energy without any wastewater treatment, and are provided for recycling into boiler water or using concrete mixing water.

 Concrete products (concrete piles, poles, sleepers, blocks, bricks, road boundary stones, fume pipes, plum pipes, pc pipes, etc.) that are mainly used in construction sites of civil engineering or construction, etc. Steam to the concrete and heated to wet state (atmospheric steam curing: 75 ~ 90 ℃, high pressure steam curing: about 10㎏ / ㎠ 180 ℃) to promote hydration, condensation and hardening of concrete. The steam curing method is commonly used, which increases the curing temperature of the concrete and speeds up the strength increase, so that the strength of the concrete is rapidly increased by steam curing. In this process, large amount of alkaline contaminated high temperature (approximately 55 ~ 100 ℃) waste water is generated in steam curing tank due to strong alkali cement (more than 90% of manufacturing process waste water). The.

 Another source of wastewater is

  1) Extremely poor water quality alkaline washing equipment with high concentration of residual amount of concrete (components of sand, gravel and cement) generated by concrete mixing and concrete input process

  2) Raretan sludge produced in compaction shaping process (vibration, centrifuge) and facility washing wastewater without extremely poor water quality with excessive concentration of foreign substances such as cement and oil are generated.

 In the present invention, if various kinds of wastewater are classified according to their characteristics,

  1) Classification wastewater: facility washing wastewater with very low temperature and low temperature without heat energy

The wastewater recycling method for sorting equipment is chemical wastewater treatment in a wastewater treatment plant with a small amount, small amount of heat energy, low temperature, extremely poor water quality, and strong alkalinity, and the facility is simple and maintained. Physical wastewater treatment with low management cost is used to settle sludge, such as aggregates and cement, and recycle the supernatant water to equipment washing water regardless of the quality of the water.

  2) Curing tank wastewater: It is a method of recycling the wastewater of most (more than 90%) without wastewater treatment (chemical treatment, physical treatment) by dividing into two kinds of curing tank wastewater of high temperature and good quality with high heat energy. .

  The steam cure wastewater recycling method is a large quantity of over 90% of the total waste water generation, has high temperature heat energy, and alkaline water contaminated good quality curing wastewater is separated from the facility washing wastewater of 1). It is transformed into industrial water of high quality with high alkaline and high thermal energy of itself without going through the process, and this curing waste water can be recycled into boiler water and strong alkaline water quality is required due to the characteristics of boiler water. Alkaline wastewater is better for groundwater than for groundwater under boiler water.

 In addition, curing wastewater separated from wastewater can be used as concrete mixing water.

That is, the basic skeleton contamination of the present invention is low in quantity, high in quantity, high temperature curing wastewater, small amount of water quality is extremely poor, and high quality industrial water and high temperature thermal energy that are discarded by separating high-contamination facility washing wastewater. Recycling is a way to solve the company's environmental problems by reducing costs and drastically reducing fuel consumption and water consumption.

 Conventional method and flow chart from groundwater water supply to wastewater treatment of the present invention is as follows.

Conventional method: wastewater treatment by mixing different kinds of wastewater

 Low temperature, neutral water (ground water) water supply ⇒ Alkaline water treatment (boiler water treatment facility (hard water softening, cationic resin, anion resin)) ⇒ elevated temperature (injecting steam into the process by operating the boiler) ⇒ high temperature, alkaline water generation Poor water turbidity by mixing) ⇒ Neutral by temperature and chemical water treatment (some heat exchange after high heat energy, wastewater treatment plant) ⇒ Discharge or recycling (water that loses heat energy, river water pollution) ⇒ Low temperature, neutral water (ground water) Rewatering

The present invention: Separation treatment by classifying according to characteristics (temperature, degree of contamination)

1) Facility cleaning wastewater with classification (low temperature, high pollution strength)

Low temperature, strong alkaline wastewater generation (concrete mixer, feeder, compaction molding machine) ⇒ pollutant precipitation (gravel, sand, cement) ⇒ supernatant water (alkaline wastewater) with reduced pollution intensity Reuse as a washing function)

2) Steam curing wastewater of classification (high temperature, low pollution intensity)

High temperature, alkaline waste water generation (alkali pollution due to steam curing of strong alkali concrete) ⇒ High temperature, alkaline waste water recycling (instead of waste water treatment, boiler water, mixing water input, boiler existing water treatment facility) ⇒ General water (ground water, water Some, etc.) (about 20-40%)

According to KS standard water supply of various boilers and water quality of boiler water are as following Table 1 and Table 2.

Table 1: Water quality of copper boiler (circulating boiler) feed water and boiler water (KS B 6209)

Table 2: Water Supply of Water Boiler (Circulation Boiler) and Water Quality of Boiler Water (KS B 6209)

Note 1) Applicable only when fresh water is always used in live cast iron boilers.

   2) Raw water refers to tap water, industrial water, ground water, river water, tap water, etc., and softened water refers to water or raw water treated with raw water with a softening device (filled with cation exchange resin). Refers to water treated with.

    3) Hexane extract or carbon tetrachloride extract (see KS B6224).

    4) It is desirable to keep it low.

    5) Idiomatically referred to as M-alkalido.

    6) Idiomatically called P-alkalido.

    7) Applies when phosphate is added.

8) Applicable when sulfite is added as a deoxidizer. If deaerator is used, it is recommended to adjust to 10-20 mg SO ₃ ^2- / l.

9) Applied when hydrazine is added to the feed water as a deoxidizer to copper boilers and water pipe boilers with a maximum working pressure of 2MPa (20kgf / cm ² or less), except that 0.1 ~ 0.5 mg N ₂ H ₄ / l It is desirable to adjust.

    10) Applied when hydrazine is added to water supply as an oxygen scavenger

   11) Water purified by ion exchanger using strong acid cation exchange resin and strong basic anion exchange resin. Idiomatically termed demineralized water. Also included is water (condensed water) purified by neutralizer.

    12) If the pipe material of feed water heater is steel pipe, it is desirable to adjust pH high.

    13) It is preferable to keep it below 0.02mg Fe / l.

    14) It is preferable to keep it at 0.01 mg Fe / l or less.

   15) The sample was measured through a column packed with hydrogen acid strong acid cation exchange resin.

16) In the case of waste heat recovery boiler, it is preferable to adjust pH 9 ~ 10.5, phosphate ion 2 ~ 20mg PO ₄ ^3- / l.

   17) If calcium, magnesium, and pH-lowering ingredients are mixed due to seawater leakage from the condenser, phosphate is required for emergency treatment corresponding to the mixing of calcium, magnesium, and pH-lowering ingredients.

18) From the relationship between the silica concentration in the boiler water and the silica concentration in the steam, the silica concentration in the boiler water is maintained so that the silica concentration in the steam is 0.02 mg SiO ₂ / l or less.

Remarks:

1) In principle, hydrazine and sulfite used as deoxidizer should be added without mixing.

     2) Samples to be tested for boiler water should be taken where boiler water is most concentrated.

Example 1

A company's curing tank wastewater, groundwater boiler irrigation and boiler port standards, which produce concrete products such as domestic concrete piles, are shown in the following table.

Test method: According to KS B 6224.

Date of test: February 19, 2004

Exam completion date: February 23, 2004

Test results: The test results are shown in Table 3 below.

Table 3: Test Results

As can be seen from the above experimental results, the curing tank waste water is suitable as boiler water in all items such as pH, M alkalinity, Cl ion and PO ₄ ion, and is superior to groundwater or used water. In addition, curing tank waste water can be used as irrigation water for boilers without chemical treatment, and since hot waste water can be used as boiler water as it is, it has an excellent effect of drastically reducing energy costs and most of waste water treatment costs. .

Example 2

1) separate the facility washing water and the curing tank waste water discharged from the concrete product manufacturing plant, respectively;

2) Equipment washing waste water is treated by chemical wastewater treatment in a wastewater treatment plant according to a conventional method, or sludge such as aggregate and cement is removed by physical wastewater treatment, or precipitated and filtered, and the supernatant water is recycled to equipment washing water. ;

3) The curing tank waste water, which is about 90% of the total waste water, is recycled into expensive boiler water with high alkaline energy or used as concrete mixing water.

The present invention has the following advantages.

1) Three kinds of wastewater are generated in the production method of concrete products currently used, and the present invention can be recycled by weakening the strength of pollution by separating and classifying two kinds according to the characteristics (temperature, degree of pollution) of the wastewater. ,

2) The method of recycling sorted facility wastewater is chemical wastewater treatment in a wastewater treatment plant, which is a small amount, small amount of heat energy, low temperature, extremely poor water quality and strong alkaline due to the conventional method. Simple and inexpensive maintenance of physical wastewater precipitates sludge such as aggregates and cements, and recycles the supernatant to facility washing water, regardless of the quality of the water.

3) Classification The method of recycling steam curing wastewater is alkaline steam curing wastewater which has high temperature heat energy with high quality water quality of over 90% of total wastewater generation, and does not wastewater treatment (chemical treatment, etc.). The curing wastewater itself is transformed into industrial water with good alkaline high thermal energy, which can be recycled into boiler water, and the alkaline alkaline wastewater is required because strong alkaline water quality is required due to the nature of boiler water. Is the condition of boiler water, which is better than groundwater.

 In this way, if the wastewater is classified and separated according to its characteristics, most of the wastewater is recycled as it is without the conventional chemical wastewater treatment in the wastewater treatment plant, and more effective recycling methods are generated.

1. In terms of energy saving

   1) Significant savings in fuel consumption (about 15-30%) by recycling a large amount of wastewater (55 ~ 95 ℃) of high temperature (approximately 60% of steam generation) into boiler water to produce steam (about 170 ℃). ) And the reduction of industrial water and the energy cost of equipment operation.

   2) The amount of wastewater required for chemical water treatment in the wastewater treatment plant is drastically reduced, thereby reducing the power cost by reducing the wastewater treatment plant uptime.

   3) Since there is no need for alkali treatment of boiler water, water treatment cost is reduced.

2. Environmental aspects

   1) Reduce air pollution by drastically reducing fuel consumption (15 ~ 30%),

   2) Since the wastewater is not discharged by recycling all or most of the wastewater, water pollution is prevented.

  3) By reducing fuel consumption and recycling wastewater, the discharged water is drastically reduced and it can be operated as a small wastewater treatment plant, so it is possible to change and maintain the water quality and air environment grade to low species, thereby reducing environmental charges and other environmental costs. Become,

   4) Many problems caused by the environment are solved.

3. In terms of facility investment, a small wastewater treatment plant can be operated, reducing the investment cost of prevention facilities.

As mentioned above, the use of petroleum energy, which relies on total imports, is greatly reduced, thereby improving national competitiveness and contributing to the environmental protection of the country by recycling wastewater in the situation of Korea where water resources are scarce.

 In addition, environmental problems are serious and regulations are being tightened. In the future, environmental management is directly related to the existence of the company.

According to the present invention,

1) When three kinds of wastewater are generated in the method of manufacturing concrete products currently used, the present invention classifies and separates two kinds according to the characteristics of wastewater (temperature, degree of pollution).

2) The method of recycling sorted facility wastewater is chemical wastewater treatment in a wastewater treatment plant, which is a small amount, small amount of heat energy, low temperature, extremely poor water quality and strong alkaline due to the conventional method. Simple and inexpensive maintenance of physical wastewater precipitates sludge such as aggregates and cements, and recycles the supernatant to facility washing water, regardless of the quality of the water.

3) Classification The recycling method of steam curing wastewater is alkaline steam curing wastewater which has high temperature heat energy with a large amount of high quality water quality which is more than 90% of total wastewater generation without wastewater treatment (chemical treatment, etc.). Curing waste water itself is transformed into industrial water with good alkaline high thermal energy, and this curing waste water can be recycled into boiler water and strong alkaline water quality is required due to the characteristics of boiler water. The condition of boiler water provides better water than ground water.

Claims (1)

1) separate the facility washing water and the curing tank waste water discharged from the concrete product manufacturing plant, respectively; 2) Equipment washing waste water is treated by chemical wastewater treatment in a wastewater treatment plant according to a conventional method, or sludge such as aggregate and cement is removed by physical wastewater treatment, or precipitated and filtered, and the supernatant water is recycled to equipment washing water. ; 3) A method for recycling wastewater generated in the concrete product manufacturing process, wherein the curing tank wastewater, which is about 90% of the total wastewater, is recycled to high boiler water having high alkaline energy or recycled to concrete mixing water.