KR100859594B1 - Advanced wastewater treatment method with the biosolids reduction and the recovery of rbdcod - Google Patents

Abstract

A method for treating wastewater by combining the reduction of sludge with the recovery of RBDCOD(Readily Bio-Degradable COD) is provided to minimize the volume of sludge by solubilizing waste sludge and reducing the volume of a solubilized liquid, recover high concentration RBDCOD by selectively injecting magnesium and calcium into the solubilized liquid, and reduce chemical costs by using the recovered high concentration RBDCOD as a carbon source. In a wastewater treatment system comprising a wastewater treatment apparatus, a sludge reduction tank having an alkali treatment tank(15) and an ozone treatment tank(16), a fermentation tank(17), and a crystallization tank(19), a method for treating wastewater by combining the reduction of sludge with the recovery of RBDCOD comprises: a first step of alkali-treating waste sludge transferred from the wastewater treatment apparatus in the alkali treatment tank, and ozone-treating the alkali-treated waste sludge in the ozone treatment tank, thereby increasing solubilization ratio of the sludge to reduce the volume of the sludge; a second step of separating a liquid solubilized in the alkali treatment tank through a membrane(18) submerged into the alkali treatment tank, and transferring only a pure solubilized liquid to the crystallization tank; a third step of producing crystallized material in the crystallization tank from a solubilized liquid transferred from the alkali treatment tank; a fourth step of separating the crystallized material and recovering supernatant from the crystallization tank; and a fifth step of returning the supernatant recovered from the crystallization tank to the wastewater treatment apparatus to use the supernatant as a carbon source.

Description

Advanced wastewater treatment method with the biosolids reduction and the recovery of RBDCOD}

1 is in the present invention This diagram shows the combination of sludge reduction tank and crystallization tank.

2 is a block diagram of an apparatus for implementing the method of the present invention.

3 is a block diagram of another apparatus for implementing the method of the present invention.

4 is another apparatus configuration diagram for practicing the method of the present invention.

<Explanation of symbols for main parts of drawing>

11, 21, 31: anaerobic tank 12, 32: alternating inflow reaction tank (first and second reaction tanks)

13,33: membrane reactor 14,34: dissolved oxygen reduction tank

5,15,25,35: alkali treatment tank 6,16,26,36: ozone treatment tank

7,17,27,37 fermenter 8,18,28 membrane

9,19,29,39: Crystallization tank 22: Anaerobic tank

23: aerobic tank 24: sedimentation tank

30: sludge storage tank

The present invention relates to a wastewater treatment method combining sludge reduction and organic matter (RBDCOD) recovery method, and more particularly, to reduce sludge by combining a sludge reduction tank and a crystallization tank to a sludge reduction tank and a crystallization tank and solubilizing the sludge. , Solubilization solution is crystallized in the form of stuvite and hydroxyapatite by adding magnesium and calcium in the crystallization tank to remove nitrogen and phosphorus, and supernatant containing a large amount of organic matter (RBDCOD) The present invention relates to a wastewater treatment method combining sludge reduction and organic matter (RBDCOD) recovery methods, which are transferred to anaerobic and anaerobic tanks of wastewater treatment apparatus and used as a carbon source.

In general, sludge is a by-product generated from the process of decomposing pollutants and treating the wastewater. The main component is composed of high concentrations of organic matter and nutrients, and it can be said that the wastewater treatment is completed only when the sludge is finally disposed of.

Among them, nutrients are composed of inorganic elements including nitrogen and phosphorus, which flow into rivers or coastal seas and promote algae growth, causing eutrophication and red tide. Therefore, these nutrients are substances to be removed before they enter rivers or coastal waters.

A common method of treating sludge is to land the sludge cake by-product through concentration, digestion, dehydration, drying and incineration. In recent years, however, sludge cannot be reclaimed immediately, and only the residues are reclaimed after incineration or composting, and marine dumping will be partially banned from 2008. Therefore, it is urgently required to develop a technology for reducing the efficiency of sewage sludge, and recently, researches on the reduction and reuse methods of the sludge have been actively conducted.

As such an example, the prior art is as follows. Korean Patent No. 10-0566321 discloses nitrogen and phosphorus using methanol as an external carbon source when the C / N ratio and C / P ratio of the influent sewage are low in the process of removing nitrogen and phosphorus from the influent sewage and return sludge. In this method, there is a problem in that the cost of operating drugs due to methanol used as a carbon source is high.

In another example, Korean Utility Model Registration No. 20-0405757 adds an alkaline agent to sewage sludge, hydrolyzes it, and radiates ultrasonic waves to change undissolved substances that are difficult to decompose by microorganisms into easily dissolved dissolved substances and molecular structures. By reducing the sludge, an apparatus for reducing sludge is devised. The above apparatus has an effect of reducing sludge, but has a problem in that nitrogen and phosphorus in the treated water need to be further removed.

In another example, Korean Patent Laid-Open Publication No. 2002-5521, in which a coagulant such as magnesium or phosphorus is added to livestock wastewater or industrial wastewater containing high concentration of nitrogen, and the molar ratio of Mg: N: P is 1 under alkaline conditions of pH 11. A method for removing nitrogen and phosphorus by introducing struvite crystals at a ratio of 1: 1 has been introduced. However, in this method, although nitrogen and phosphorus are removed, the purity of the stubbit crystal is low due to the high concentration of solids, and thus crystals cannot be used.

As described above, since the concentrations of organic substances, nitrogen, and phosphorus, which are main components of pollutants, are different depending on the characteristics of the wastewater, each process can be selectively applied according to the characteristics, but the C / N and C / P ratios are low. In the case of sewage water, organic matter, nitrogen and phosphorus must be treated at the same time. Therefore, there is a problem in that the treatment cost of sludge is high due to the generation of waste sludge as well as the cost of supplying carbon sources in the operation of the sewage water treatment system.

In order to solve the above problems, the present invention is to reduce the sludge by dissolving and solubilizing the waste sludge generated in the sewage treatment apparatus in an alkali treatment tank and an ozone treatment tank, and transfer the solubilization liquid to the alkali treatment tank again to reduce the sludge again. It aims to minimize by doing so.

In addition, the present invention is to recover the high concentration organic matter (RBDCOD) after the solubilization solution solubilized in the alkali treatment tank to the crystallization tank to selectively inject magnesium and calcium to produce a crystallized material in the form of stubbit and hydroxyapatite The purpose.

In addition, the present invention, by transporting the high concentration of organic matter (RBDCOD) recovered from the crystallization tank to the anaerobic and anoxic tank of the sewage treatment apparatus as a carbon source, by utilizing the organic material (RBDCOD) to remove nitrogen and phosphorus in the influent sewage to the carbon source input The aim is to reduce the cost of the drug.

In order to achieve the above object, in the present invention, in the wastewater treatment system consisting of a wastewater treatment apparatus, a sludge reduction tank having an alkali treatment tank and an ozone treatment tank, and a fermentation tank and a crystallization tank, a sludge reduction and organic matter (RBDCOD) recovery method is provided. Combined sewage treatment method,

A first step of reducing the sludge by increasing the solubilization rate by treating the waste sludge conveyed by the wastewater treatment apparatus with an ozone treatment after the alkali treatment in the alkali treatment tank; A second step of transferring the solubilization solution solubilized in the alkali treatment tank to the crystallization tank; A third step of producing a crystallized product in the crystallization tank (19) from the solubilization liquid transferred from the alkali treatment tank (15); A fourth step of separating the crystallization from the crystallization tank 19 and recovering the supernatant; And a fifth step of returning the supernatant liquid recovered from the crystallization tank 19 to the sewage treatment apparatus and using it as a carbon source.

In the present invention, the second step is characterized in that the solubilization liquid is separated through the membrane 18 immersed in the alkali treatment tank 15, and then only the pure solubilization liquid is transferred to the crystallization tank 19. do.

In the present invention, in the first step, the alkali treatment and ozone treatment are simultaneously performed in the alkali treatment tank 15 instead of the ozone treatment in the ozone treatment tank 16 after the alkali treatment in the alkali treatment tank 15. Characterized in that.

In the present invention, the first step is characterized in that the ultrasonic treatment instead of the ozone treatment.

In the present invention, in the first step, after the alkali treatment of the sludge in the alkali treatment tank 15, the precipitated sludge is drawn out, solubilized by ozone treatment in the ozone treatment tank 16, and then the alkali treatment tank again. It characterized in that the inflow to (15).

In the present invention, the first step is to transfer the sludge of the alkali treatment tank 15 to the fermentation tank 17, the fermentation treatment and then discard the precipitate and return the fermentation broth to the alkali treatment tank 15. It further comprises.

In the present invention, the first step is characterized in that the alkali agent (NaOH) is added to meet the pH conditions for the alkali treatment in the alkali treatment tank (15).

In the present invention, the third step is to add an alkali (NaOH) in order to meet the optimum pH conditions for crystallization in the crystallization tank 19, and selectively add magnesium and calcium in accordance with the concentration of nitrogen and phosphorus It is characterized by.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram showing the combination of the sludge reduction tank and the crystallization tank in the method of the present invention. 2 is a block diagram of an apparatus for implementing the method of the present invention. 3 is a block diagram of another apparatus for implementing the method of the present invention. 4 is another apparatus configuration diagram for practicing the method of the present invention.

An embodiment according to the present invention will be described with reference to FIG.

First, the influent sewage is introduced into the anaerobic tank 11 together with the return sludge, decomposed under anaerobic conditions, and then introduced into the membrane reaction tank 13 through nitrification and denitrification in the alternate inflow reaction tank 12.

Next, the treated water is discharged from the membrane reaction tank 13 through the membrane, and a predetermined amount of sludge is transferred to the dissolved acid tank reducing tank 14, and the remaining sludge is transferred to the alkali treatment tank 15 as waste sludge.

Thereafter, in order to solubilize the waste sludge in the alkali treatment tank 15, an alkaline agent (NaOH) is added so as to have a pH of 10-12 to decompose and solubilize the sludge. In this case, the solubilization liquid contains a large amount of organic, nitrogen, and phosphorus components.

The sludge solubilized in the alkali treatment tank 15 is transferred to the ozone treatment tank 16 disposed on one side of the alkali treatment tank 15 and subjected to ozone treatment, whereby the sludge reduction and solubilization rate is further increased. After the treatment, the solubilization liquid is transferred to the alkali treatment tank 15 again for resolubilization. The solubilization efficiency is higher when alkali and ozone are treated simultaneously than single ozone treatment or single alkali treatment. In addition, the sludge solubilized in the alkali treatment tank 15 comes into contact with ozone to destroy the cell walls of the microorganisms constituting the sludge. Is converted to (RBDCOD). At this time, the solubilization of the sludge and the degradable organic substance (RBDCOD) are increased in proportion to the ozone injection rate of 0.05 to 0.5 gO ₃ / gSS.

An ultrasonic bath may be used instead of the ozone treatment tank 16. In this case, the sludge reduction rate depends on the sludge properties, but can be up to 70 ~ 85%, and the sludge solubilization capacity increases as the ultrasonic vibration addition time increases.

In addition, instead of performing ozone treatment in the ozone treatment tank 16 after alkali treatment in the alkali treatment tank 15, the alkali treatment and ozone treatment may be performed simultaneously in the alkali treatment tank 15.

In the alkali treatment tank 15, a predetermined amount of solubilized sludge is transferred to the fermentation tank 17 in order to adjust the concentration of microorganisms in the alkali treatment tank 15 to meet the operating conditions.

The solubilized sludge transferred to the fermentation tank 17 is disposed of after the fermentation treatment, the sediment is disposed of, and the fermentation broth is returned to the alkali treatment tank 15 so as to be solubilized, so that the sludge reduction rate is further increased to minimize the sludge.

The solubilization solution solubilized in the alkali treatment tank 15 is separated through the membrane 18, and only pure solubilization liquid is sent to the crystallization tank 19. The pure solubilizing liquid from which the solid liquid is separated may result in higher purity of the crystallized product in the crystallization tank 19.

In the crystallization tank 19, an alkali chemical agent (NaOH) is added so that the pH of the solubilization solution is 9.5-10.7, and magnesium and calcium ions are added according to the concentrations of nitrogen and phosphorus to give stubbite (MgNH ₄ PO ₄ ) and hydroxy. Nitrogen and phosphorus are removed from the solubilization solution by crystallization in the form of apatite (Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ ). Sturbite and hydroxyapatite have a minimum dissolution rate at a pH of 9.5 to 10.7, and a solubilizing solution adjusted to a pH of 10-12 in the alkali treatment tank 15 satisfies the above pH conditions. . Accordingly, the crystallization tank 19 may be an optimum condition for crystallization even without additionally injecting an alkaline agent, and crystallization may be possible by only adding magnesium and calcium. In this case, the magnesium source to be injected may be MgO, MgCl ₂ , MgSO ₄ and the like, and CaCl ₂ may be used as the calcium source.

When the crystallization is completed in the crystallization tank 19, the crystallization is separated and the supernatant is recovered. At this time, a large amount of degradable organic matter (RBDCOD) is present in the supernatant, and is recovered in full and transferred to the anaerobic tank 11 and the alternating inflow reaction tank 12 of the wastewater treatment system.

The supernatant containing a large amount of decomposable organic matter (RBDCOD) is used as a carbon source (COD) for the elution and denitrification of phosphorus in the sludge by combining with the influent sewage from the anaerobic tank 11 and the shift inflow reaction tank 12. Soluble Chemical Oxygen Demand (SCOD) of alkali and ozonated solubilizing solution is 4000 ~ 5000mg / L. About 70% of SCOD is RBDCOD and 2800 ~ 3500mg / L. Therefore, by using the organic material of the supernatant (RBDCOD) as a carbon source of the sewage treatment system can reduce the drug cost.

3 is another embodiment of the present invention.

Sludge reduction consisting of an anaerobic tank 21, an anaerobic tank 22, an aerobic tank 23, a sedimentation tank 24 and a sludge storage tank 30, and other wastewater treatment devices consisting of an alkali treatment tank 25 and an ozone treatment tank 26. In the wastewater treatment system consisting of a tank, a fermentation tank 27 and a crystallization tank 29, the influent sewage is anaerobicly decomposed in the anaerobic tank 11 and after the phosphorus elution process, It enters the anoxic tank 22 and undergoes nitrification. Subsequently, nitrogen and phosphorus are removed while flowing into the aerobic tank 23 and undergoing denitrification, and are introduced into the precipitation tank 24. Waste sludge precipitated and separated by natural sedimentation in the sedimentation tank 24 is collected in the sludge storage tank 30 and then transferred to the alkali treatment tank 25.

Subsequently, it is processed in the same manner as in FIG.

The sludge is solubilized and reduced through the alkali treatment tank 25 and the ozone treatment tank 26, and the solubilized liquid contains a large amount of decomposable organic matter (RBDCOD), nitrogen and phosphorus, and the alkali treatment tank 25 Only the pure solubilization liquid separated through the membrane immersed in is introduced into the crystallization tank 29. In the crystallization tank 29, nitrogen and phosphorus are combined with magnesium and calcium to separate and remove high-purity stubite and hydroxyapatite crystals, and the supernatant containing a large amount of organic matter (RBDCOD) is recovered. The recovered supernatant is transported to the anaerobic tank 21 and the anoxic tank 22 and utilized as a carbon source to participate in the process of eluting phosphorus in the influent sewage and denitrification.

4 is another embodiment of the present invention.

Sewage water treatment device consisting of an anaerobic tank 31, alternating inflow reaction tank 32 consisting of first and second reaction tanks, a membrane reaction tank 33, and a dissolved acid tank lowering tank 34, and an alkali treatment tank (35) with no membrane coupling. In the wastewater treatment system consisting of a sludge reduction tank consisting of a) and an ozone treatment tank (36), and a fermentation tank (37) and a crystallization tank (39), the influent sewage is treated in the same manner as in FIG. The solubilizing solution solubilized in the bath (35) flows directly into the crystallization bath (39) without passing through the membrane.

Sewage sludge is transferred from the membrane reaction tank 33 to the alkali treatment tank 35 through the anaerobic tank 31 and the alternate inflow reaction tank 32. Subsequently, the sludge is solubilized and reduced through the alkali treatment tank 35 and the ozone treatment tank 36, and the solubilized solution contains a large amount of decomposable organic matter (RBDCOD), nitrogen and phosphorus. In addition, the solubilized sludge transferred to the fermentation tank 37 according to the operating conditions of the alkali treatment tank 35 is disposed of after the fermentation treatment, the waste is disposed of and the fermentation broth is returned to the alkali treatment tank 35. The solubilization liquid solubilized in the alkali treatment tank 35 flows into the crystallization tank 39. In the crystallization tank 39, nitrogen and phosphorus are combined with magnesium and calcium to separate and remove the crystals of stubite and hydroxyapatite, and the supernatant liquid containing a large amount of organic matter (RBDCOD) is recovered. The recovered supernatant is transported to the anaerobic tank 31 and the alternating inlet reaction tank 32 to be used as a carbon source to participate in the process of eluting phosphorus in the sludge. In the embodiment of FIG. By sending the solubilization liquid to the crystallization tank 39 without using, the chemical cost of magnesium and calcium in the crystallization tank 39 can be added more than when using a membrane.

As described above, the embodiments of the present invention have been described in detail. For those skilled in the art, these specific descriptions are merely preferred embodiments, and the scope of the present invention is not limited thereto. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

The wastewater treatment method combining sludge reduction and organic matter (RBDCOD) recovery method of the present invention, after separating the crystallization from the crystallization tank, recovers the supernatant containing a large amount of organic matter (RBDCOD), and transfer to the anaerobic tank and the shift inflow reaction tank to the carbon source In this case, in case of sewage treatment with low C / N and C / P ratio of influent sewage, it is possible to increase the efficiency of removing nitrogen and phosphorus without injecting external carbon source, thereby reducing the chemical cost of supplying carbon source. .

In addition, the present invention is effective in reducing the sludge treatment cost by reducing the sludge by solubilizing the waste sludge generated in the waste water treatment apparatus in an alkali treatment tank and an ozone treatment tank.

In addition, the present invention, by transferring only the solubilizing liquid from which the solid solution is separated from the alkali treatment tank and injecting magnesium and calcium from the crystallization tank, the purity of the stubite and hydroxyapatite crystallization can be increased and recycled as a fertilizer There is.

Claims (8)

In the wastewater treatment system comprising a wastewater treatment apparatus, a sludge reduction tank having an alkali treatment tank 15 and an ozone treatment tank 16, and a fermentation tank 17 and a crystallization tank 19, A first step of reducing the sludge by increasing the solubilization rate by treating the waste sludge transferred from the wastewater treatment apparatus with an alkali treatment in the alkali treatment tank 15 and then ozone treatment in the ozone treatment tank 16; A second step of separating the solubilizing solution solubilized in the alkali treatment tank (15) through the membrane (18) immersed in the alkali treatment tank (15) and transferring only the pure solubilization solution to the crystallization tank (19); A third step of producing a crystallized product in the crystallization tank (19) from the solubilization liquid transferred from the alkali treatment tank (15); A fourth step of separating the crystallization from the crystallization tank 19 and recovering the supernatant; And A fifth step of returning the supernatant liquid recovered from the crystallization tank 19 to the sewage treatment system and using it as a carbon source; Sewage reduction and organic matter (RBDCOD) method for wastewater treatment comprising a method for recovering, comprising a. delete The method of claim 1, In the first step, the alkali treatment and the ozone treatment are simultaneously performed in the alkali treatment tank 15 instead of the ozone treatment in the ozone treatment tank 16 after the alkali treatment in the alkali treatment tank 15. Wastewater treatment method for sludge reduction and organic matter (RBDCOD) recovery. The method according to claim 1 or 3, The first step is a wastewater treatment method combining sludge reduction and organic matter (RBDCOD) recovery method characterized in that the ultrasonic treatment instead of the ozone treatment. In the wastewater treatment system comprising a wastewater treatment apparatus, a sludge reduction tank having an alkali treatment tank 15 and an ozone treatment tank 16, and a fermentation tank 17 and a crystallization tank 19, A first step of reducing the sludge by increasing the solubilization rate by treating the waste sludge transferred from the wastewater treatment apparatus with an alkali treatment in the alkali treatment tank 15 and then ozone treatment in the ozone treatment tank 16; A second step of transferring the solubilization solution solubilized in the alkali treatment tank (15) to the crystallization tank (19); A third step of producing a crystallized product in the crystallization tank (19) from the solubilization liquid transferred from the alkali treatment tank (15); A fourth step of separating the crystallization from the crystallization tank 19 and recovering the supernatant; And A fifth step of returning the supernatant liquid recovered from the crystallization tank 19 to the sewage treatment system and using it as a carbon source; Including; In the first step, after alkali treatment of the sludge in the alkali treatment tank 15, the precipitated sludge is drawn, ozonated in the ozone treatment tank 16, solubilized, and then returned to the alkali treatment tank 15. Wastewater treatment method combining sludge reduction and organic matter (RBDCOD) recovery method characterized in that the inflow. In the wastewater treatment system comprising a wastewater treatment apparatus, a sludge reduction tank having an alkali treatment tank 15 and an ozone treatment tank 16, and a fermentation tank 17 and a crystallization tank 19, A first step of reducing the sludge by increasing the solubilization rate by treating the waste sludge transferred from the wastewater treatment apparatus with an alkali treatment in the alkali treatment tank 15 and then ozone treatment in the ozone treatment tank 16; A second step of transferring the solubilization solution solubilized in the alkali treatment tank (15) to the crystallization tank (19); A third step of producing a crystallized product in the crystallization tank (19) from the solubilization liquid transferred from the alkali treatment tank (15); A fourth step of separating the crystallization from the crystallization tank 19 and recovering the supernatant; And A fifth step of returning the supernatant liquid recovered from the crystallization tank 19 to the sewage treatment system and using it as a carbon source; Including; The first step, the sludge of the alkali treatment tank 15 to the fermentation tank 17 after the fermentation treatment, the precipitate is discarded and the fermentation broth further comprises returning to the alkali treatment tank 15 Wastewater treatment method combining sludge reduction and organic matter (RBDCOD) recovery method. The method of claim 1, The first step is a wastewater treatment method combining sludge reduction and organic matter (RBDCOD) recovery method characterized in that the alkali agent (NaOH) is added to meet the pH conditions for alkali treatment in the alkali treatment tank (15). In the wastewater treatment system comprising a wastewater treatment apparatus, a sludge reduction tank having an alkali treatment tank 15 and an ozone treatment tank 16, and a fermentation tank 17 and a crystallization tank 19, A first step of reducing the sludge by increasing the solubilization rate by treating the waste sludge transferred from the wastewater treatment apparatus with an alkali treatment in the alkali treatment tank 15 and then ozone treatment in the ozone treatment tank 16; A second step of transferring the solubilization solution solubilized in the alkali treatment tank (15) to the crystallization tank (19); A third step of producing a crystallized product in the crystallization tank (19) from the solubilization liquid transferred from the alkali treatment tank (15); A fourth step of separating the crystallization from the crystallization tank 19 and recovering the supernatant; And A fifth step of returning the supernatant liquid recovered from the crystallization tank 19 to the sewage treatment system and using it as a carbon source; Including; In the third step, an alkali agent (NaOH) is added to meet an optimal pH condition for crystallization in the crystallization tank 19, and magnesium and calcium are selectively added according to nitrogen and phosphorus concentrations. Wastewater treatment method that combines weight loss and organic matter (RBDCOD) recovery methods.

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