KR900009152B1 - Process for activated-sludge teratment of sewage or industrial waste water - Google Patents

Abstract

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Description

Activated sludge treatment of sewage or industrial wastewater

1 is a schematic diagram of a biochemical treatment apparatus for sewage treatment in which a ceramic cassette for experiment used in the present invention is focused;

FIG. 2 is a graph showing the result of measuring the sedimentation curve of activated sludge 30 days after adding shaft furnace water.

The present invention relates to a method for treating activated sludge of sewage or industrial wastewater, which will be described in more detail. The present invention relates to an active sludge treatment method of sewage or industrial wastewater. It's about how to treat sludge.

In the case of performing the activated sludge treatment using sewage as an example, the treatment is performed as follows.

First, in the case of sewage, the sewage collected in the sewage treatment plant is removed by sedimentation, initial settling, etc., and most of the sediment, coarse and large suspended solids is removed. After decomposing and sedimentation of activated sludge in the final sludge settling tank, clear water from above is discharged after chlorine disinfection and so on.

On the other hand, the activated sludge settled in the final sludge settling tank is returned to the aeration tank as the returned sludge, and some are extracted as the remaining sludge and disposed of via methane fermentation and incineration.

There are many problems in such a method of treating sewage sludge.

For example, the sewage sludge of this sewage treatment has a high SVI (Sludge Volume Index), which is an indicator of sedimentation, and it is difficult to obtain a sedimentation sludge having good consolidation in a final sludge sedimentation tank. If this large treatment is carried out or if bacteria in the shape of active sludge occur, the activated sludge will become a bulking state and settle poorly.

Therefore, in conventional activated sludge treatment of sewage, it is difficult to maintain the activated sludge of the aeration tank at a high concentration. Therefore, there is a limitation in the improvement of treatment efficiency such as shortening of treatment time and miniaturization of treatment ratio, and bulking. When it occurs, the activated sludge flows out of the sludge settling tank, which is likely to cause deterioration of the treated water quality.

For this reason, in the conventional activated sludge treatment method, when constructing a sewage treatment plant, a large land is required, and it is difficult to miniaturize the treatment process and miniaturize the treatment equipment, and therefore, a considerable cost is required for the construction of the sewage treatment plant.

As one method to solve the problem of sewage treatment, development of highly efficient activated sludge treatment technology is desired.

Conventionally, as a method of performing the activated sludge treatment of sewage or industrial wastewater with high efficiency, there is a method of maintaining the activated sludge in the aeration tank with a high concentration, and there are a flow bottom method and a fixed bottom method.

The fluidized bed method adds activated sludge to the aeration tank by adding fine particles such as diatomaceous earth, sand, ceramics, or particles of activated carbon, or porous organic polymer compounds to the aeration tank. It is a method of attaching activated sludge and improving the sedimentation of activated sludge to maintain the activated sludge at high concentration.

As an example, it is known from Japanese Patent Application Laid-Open No. 61,136,491.

The fixed bottom method is a method in which a honeycomb tube made of an organic polymer compound, a multilayer board, or ceramics is immersed in an aeration tank, and an activated sludge is attached thereto to fix it.

As a prior art in this case, there is Japanese Patent Application Laid-Open No. 61,490, which uses ceramics as an immobilization carrier of activated sludge. There are many problems with these conventional methods.

First, when inorganic microparticles are used in the fluidized bed method, since affinity with activated sludge is not sufficient, active sludge needs a long time to attach stably.

In addition, there has not been sufficiently established a method for treating activated sludge adhering to this carrier as excess sludge.

In the case of a fluidized bed method using particles of powdered activated carbon or organic polymer compound, the affinity between these particles and activated sludge is very good, and the activated sludge is stable and adheres.

However, when the remaining sludge treated by this method is treated by the methane fermentation method, a technique for regenerating these particles after methane fermentation has not been sufficiently established.

In addition, in the case of incineration of the remaining sludge, these carrier particles are higher in price than the inorganic carrier particles and cannot be used for regeneration, which causes the cost of sewage treatment.

On the other hand, in the case of the fixed bottom method using a honey-kim tubing laminate of an organic polymer compound in a fixed-bottom carrier of activated sludge, the activated sludge and its carrier have good affinity, so that the activated sludge adheres to these carriers. Occupancy of the carrier is likely to occur.

For this reason, it is necessary to carry out the cleaning by removing the carrier from the aeration tank and washing with water each time.

However, the activated sludge attached to these fixed bottom carriers generally has a fixed bottom structure, and because of its high affinity between the carrier and the activated sludge, it is difficult to regenerate by simply washing with water. It requires troublesome treatment.

In addition, as a method of using conventional ceramics for fixed-bottom carriers, as described later, the firing temperature was high, the price was high, and the activation of activated sludge was not necessarily sufficient.

As described above, the carrier for immobilizing the conventional activated sludge has problems in terms of affinity, reusability, handling, and price with the activated sludge, which is not suitable for application to large-scale activated sludge such as sewage.

The above case has been described for treating sewage as activated sludge, but other wastewater, for example, gas waste liquid discharged from coke oven of steel mill, waste gas discharged from coal gasification or liquefaction plant, waste water discharged from petroleum refining process, and food There is the same problem as in the case of sewage when the industrial wastewater such as the wastewater discharged from the plant, the wastewater discharged from the fermentation plant such as alcohol, etc. is activated.

The present invention is to solve the problems of the immobilized carrier of the activated sludge used in the conventional treatment of activated sludge of the sewage or industrial wastewater as described above to provide a high efficiency activated sludge treatment method using a novel immobilized carrier. For the purpose.

The present inventors, such as blast furnace material produced by cooling the slug (SIug) generated as a by-product from the blast furnace of the steelworks as a water in the course of studying the high efficiency sludge treatment method of sewage. In view of the fact that the activated sludge has the performance and shape that the activated sludge is easily attached to in shape and composition, the sedimentation of the activated sludge is improved by using the blast furnace material as a carrier. In addition, it has a remarkable effect on high concentration, and found that it is most suitable as an immobilization carrier of activated sludge.

In addition, when the blast furnace material was added to the aeration tank and used as a carrier for immobilization of the activated sludge, it was found to have a function of maintaining the pH of the aeration tank in a suitable range for the activated sludge as a separate effect.

Therefore, by using the blast furnace material, it is possible to suppress the occurrence of incongruity of the active duck treatment due to the pH variation and to perform a stable treatment.

The present invention has been made on the basis of these findings, and in sewage or industrial wastewater treatment using activated sludge, the fine powder of blast furnace material or ceramics whose main raw material is blast furnace material is used as immobilization carrier of activated sludge. , Sewage or industrial wastewater treatment, and ceramics containing blast furnace materials or blast furnace materials as main raw materials, as an immobilization carrier of activated sludge, and aeration tank oxidation reduction potential (ORP) It is characterized by management control in a range of a preset target value.

That is, the present invention achieves the object described above by the method described in (1) to (11) described below.

(1) A fluidized bed activated sludge treatment method for sewage or industrial wastewater, wherein fine powder of blast furnace material is added to an aeration tank of an activated sludge treatment plant, and the blast furnace material is used as an immobilization carrier of activated sludge.

(2) Flow-floor type as described in 1 above of sewage or industrial wastewater, which controls and controls the amount of air in the aeration tank to which the blast furnace powder is added so that the redox potential of the aeration tank is within the preset target value range. Activated sludge treatment method.

(3) The method according to the above item 1 or 2, wherein 1-5 wt% / aeration tank volume of blast furnace material of 0.02-0.5 m is added to the air tank.

(4) The method according to the above item 1 or 2, wherein a blast furnace material of 0.02-0.5 m is added to the aeration tank at 10-50 kg / aeration tank 1 to SP>? / SP>.

(5) A fixed bottom activated sludge treatment method for sewage or industrial wastewater, wherein ceramics composed mainly of blast furnace materials are installed in an aeration tank of an activated sludge treatment plant, and the ceramics are used as an immobilization carrier of activated sludge.

(6) The method according to the above item 5, wherein a cassette made of plate-like porous ceramics containing blast furnace material as a main raw material as an immobilization carrier of activated sludge is used.

(7) The method according to the above item 5, wherein a cassette in which tip-shaped ceramics containing blast furnace material as a main component is used as an immobilization carrier of activated sludge.

(8) The method according to the above item 5, wherein a cassette filled with saddle-shaped ceramics containing blast furnace material as a main component of the activated sludge carrier is used.

(9) The above-mentioned Paragraphs 5 to 9, wherein activated sludge is fixed to ceramics mainly composed of blast furnaces, and water is passed through the sewage or industrial wastewater in which oxygen is dissolved by preliminary air. The method described in any one of the paragraphs.

(10) When activated sludge is immobilized on ceramics mainly composed of blast furnace materials, the incident air is passed through the sewage or industrial wastewater in which oxygen is dissolved, and the oxygen reduction potential of the treated water after biochemical treatment is The method according to the above-mentioned 9, wherein the amount of air to shoot air into sewage or industrial wastewater is controlled in advance so as to be within a predetermined target value range.

(11) Plural cross-sections of sewage or industrial wastewater, using a cassette composed of porous plate-shaped ceramics mainly composed of blast furnace materials or a cassette filled with blast furnace materials as an immobilized carrier for activated sludge. Placing a cassette of biochemical treatment to extract the cassette closest to the inflow side of the sewage or industrial wastewater, and subsequently moving the subsequent cassettes in parallel to the inflow side of the sewage or industrial wastewater; Inserting a cassette or a cassette after use and regeneration, and the extracted cassette is subjected to a regeneration process to remove deposits, and to be used at the rear of the cassette group so as to sequentially exchange a plurality of cassettes. Sewage or acid characterized by chemical treatment Fixed bottom activated sludge treatment of up wastewater.

Blast furnace materials are produced by rapidly cooling slugs generated from 300 to 500 kg per tonne of pig iron in the blast furnace of steel mills with high pressure water.

The blast furnace material has a vitrification ratio of about 90% or more and is also porous.

The composition is a CaO, SiO _2, Al ₂ O ₃ as a main component as in the display examples shown in Table 1, is the other containing FeO, MgO and the like.

The easy attachment of activated sludge to this blast furnace material is due to its porosity and its composition.

[Table 1. Composition of Blast Furnace]

Hereinafter, the mechanism for attaching activated sludge to the blast furnace will be described.

In general, in activated sludge treatment, the pH of the aeration tank tends to be lowered by fatty acids produced by decomposition of acetic acid compounds, acetic acid compounds or organic soils produced by the reaction of ammonia.

When the activated sludge is out of a suitable range for reproduction, the decomposition sludge of the bulking fouling material of the activated sludge occurs, so that it is easy to cause treatment impurity.

When the blast furnace material is added to the aeration tank of activated sludge treatment, even if the pH of the aeration tank decreases, CaO of the blast furnace is dissolved to suppress the decrease of pH, so that the activated sludge is maintained at the pH range most suitable for reproduction, thereby stabilizing the activated sludge treatment, It is remarkably effective in improving the treated water quality.

At this time, CaO dissolution of the blast furnace material does not occur suddenly, but gradually dissolves.

This suppresses the rapid dissolution of CaO because the vitrification ratio of the blast furnace material is about 90% or more, so the pH does not rise rapidly.

Dissolved CaO also reacts with acetic acid compounds, acetic acid compounds and fatty acids to react with carbon dioxide gas produced by the respiratory action of activated sludge to form calcium carbonate.

The calcium carbonate thus produced is fine particles, and activated sludge is easily attached thereto.

In addition, the blast furnace material in which CaO is dissolved becomes more porous, and the activated sludge is easily attached.

Activated sludge also requires phosphorus, nitrogen, and trace metals such as iron and magnesium.

The blast furnace material contains FeO and MgO, respectively, and the activated sludge is easily attached to the blast furnace because it consumes nutrients such as iron and magnesium from the blast furnace material.

As such, the blast furnace material is porous. In addition, it is easy to adhere to the activated sludge, and has the effect of suppressing the treatment impairment, such as poor decomposition of the bulking soil of the activated sludge, and is superior to inorganic immobilized carriers such as diatomaceous earth and sand, which are inorganic immobilized carriers. It became apparent to hold the state.

In addition, it is known as Japanese Carrier Publication No. 57, No. 75,189 to use a blast furnace slug that gradually cools as a charger in a wastewater treatment method of an acid channel bottom method. However, there are many problems when such slowly cooled blast furnace slug is used for the immobilization carrier of the activated sludge of the fluidized bed reactor.

In addition, the properties and conditions of the blast furnace material and the slowly cooled blast furnace slug are shown in comparison with Table 2.

TABLE 2

[Characteristics of Blast Furnace and Slowly Cooling Blast Slug]

It is evident that blast furnace slugs, which are slowly cooled in the nature state of Table 1, are not suitable for use as immobilization carriers for activated sludge in fluidized bed reactors compared to blast furnace materials.

In other words, the blast furnace slug that slowly cools the porosity, which significantly affects the immobilization performance of activated sludge, is considerably less than that of the blast furnace, so the adhesion performance of the activated sludge is low and the nominal specific gravity of the slowly cooled blast furnace slug is high. Since it is considerably larger than that of the wood, the fluidity in the reactor is inferior. Therefore, the blast furnace slug that gradually cools is often deposited in the reactor, and the immobilization performance of the activated sludge is significantly reduced.

In addition, the slow cooling blast furnace slug is harder than glass blast furnace materials because of its crystallization, which requires a lot of energy to grind, and the CaO of the slow cooling blast furnace slug due to crystalline melts in a large amount, thus reducing the pH of the reactor. It is so alkaline that it is easy to impair the function of activated sludge.

This slow cooling blast furnace slug has a flawed flaw compared to the blast furnace material, so it is not suitable for use in the active sludge immobilization carrier of the fluidized-bed reactor.

In addition, the present inventors have found that when immersing porous ceramics in the activated sludge mixed liquid collected from the aeration tank of the sewage treatment plant, activated sludge naturally penetrates into the porous ceramics, and the activated sludge mixed liquid becomes transparent.

In addition, the inventors have filled a basket-like cassette with tip-shaped ceramics, for example, saddle-shaped, ring-shaped, and spherical-shaped ceramics, and immersed them in a mixed solution of activated sludge to obtain porous ceramics. As in the case, it was found that the activated sludge mixed into the gap of the tip-shaped ceramics became transparent.

In this fact, the inventors found that porous ceramics or cassettes filled with tip-shaped ceramics can be used for fixed sludge carriers of activated sludge, and examined the applicability of sewage treatment to activated sludge.

However, conventional porous ceramics and tip-shaped ceramics use expensive alumina, silica, etc. as the main raw materials, and have a high firing temperature of 1400-1600 ° C. or higher and high prices because they burn for a long time. It is difficult to use for water treatment in terms of price.

The inventors of the present invention have focused on the use of blast furnace material as a main raw material in developing and researching low-cost ceramics.

In other words, the blast furnace material is a by-product of steel, so the price is significantly lower than that of alumina and silica, which are the main raw materials of conventional ceramics, and the blast furnace material has a CaO of 42-45% as shown in Table 2. It is estimated that the firing temperature is significantly lower than that of alumina and silica because it contains.

In this regard, ceramics were prepared using blast furnace material as the main raw material. The firing temperature was 900-950 ° C, and the baking time was 1-2 hours, and it was found that porous ceramics and tip-shaped ceramics having various shapes were obtained. .

Therefore, ceramics made of blast furnace materials can be reduced to 1 / 5-1 / 20 compared to conventional alumina and silica ceramics, which is a problem in terms of price even when used for treatment of sewage and industrial wastewater. It became clear that there was no.

In addition, ceramics containing blast furnace material as the main raw materials have the same properties as described above to easily fix the activated sludge of blast furnace materials. Therefore, ceramics containing blast furnace material as the main raw material are conventional alumina or silica based materials. Compared with ceramics, the performance of immobilizing activated sludge is remarkably superior.

Next, the case where the fine powder of blast furnace material and ceramics which use blast furnace material as a main raw material in this invention is used as an immobilization carrier of the active sludge of sewage or industrial wastewater is demonstrated.

First, the case where the fine powder of blast furnace material is added to the aeration tank of an active sludge treatment plant and used as an immobilization carrier of a fluidized-bed activated sludge treatment is demonstrated.

When blast furnace material is used as an immobilization carrier of activated sludge, it is good to grind the blast furnace material to 0.5 mm or less and add 10-50 kg per aeration tank 1? SP>? / SP>.

The relationship between the particle size of the blast furnace and the adhesion of the activated sludge is that the thinner the blast furnace material is, the easier it is to attach the activated sludge, but the thinner the blast furnace material is, the more likely it is to flow into the treated water from the sludge settling tank.

Therefore, at this point, the particle size is preferably 0.02 mm or more.

In addition, the relationship between the particle size of the blast furnace material and the dispersibility in the aeration tank is that the particle size of the blast furnace material exceeding 0.5 mm is not enough to disperse, and it is difficult to uniformly disperse the inside of the aeration tank.

Therefore, in consideration of these matters, the particle size of the blast furnace material added to the aeration tank is preferably in the range of 0.02 to 0.5 mm.

Next, the addition amount of the blast furnace powder used in this invention is demonstrated.

The addition amount of the blast furnace material was mainly determined from the sedimentability of the activated sludge while observing the adhesion state of the activated sludge as a microscope.

In other words, if the added amount is less than 10 kg per 1㎥ of air tank, there is an active sludge that is not attached to the blast furnace material, and there is a high load treatment of biochemical oxygen demand (BOD) or a change in biochemical oxygen demand load. If large, bulking is likely to occur.

On the other hand, when the addition amount of blast furnace material becomes more than 10 kg per 1 m 3 of aeration tank, the above-mentioned problem is solved and good treatment performance is obtained.

However, the addition of more than 50 kg does not recognize any significant improvement.

Therefore, the addition amount of blast furnace material is most suitable in the range of 10-50kg per 1㎥ of aeration tank. In addition, the adhesion of the activated sludge to the blast furnace material is about 1 month after the addition of the blast furnace material, which is approximately completed.

In addition, in steel mills, in addition to blast furnace slugs, so-called steel slugs, there are steel slugs, such as converter slugs, produced in a steelmaking process performed to finish pig iron again with steel of a component suitable for use.

Table 3 shows an example of the composition of converter slugs.

This converter slug also contains 35-48% of the blast furnace material used in the present invention, and contains iron and magnesium, which are used as nutrients for activated sludge.

TABLE 3

[Composition example of converter slug (% by weight)]

The converter slug, which represents the steelmaking slug, may be expected to have the same effect as the blast furnace material, but it cannot be used as an immobilization carrier of activated sludge.

The reason is that since the converter slug does not form glassy like the blast furnace material, CaO dissolution occurs rapidly, and when used in the immobilization carrier of activated sludge, the pH of the aeration tank with the converter slug is rapidly increased, so This is because the activated sludge dies because the sludge exceeds a suitable pH range (7.0 ± 0.5).

In addition, the problem of using the converter slug is that the iron content is high, so the specific gravity is large, and in order to float it into the aeration tank, a large amount of air is required, and the destruction of activated sludge, the seriousness of the operating cost, and many other things. The damage is happening.

The converter slug which represents steelmaking slug has such a fatal flaw, and therefore, it is difficult to use it as an immobilization carrier of activated sludge.

Next, a case in which ceramics mainly composed of blast furnace materials is used for immobilization carriers of activated sludge will be described according to an example of treating sludge with activated sludge.

In the case of using the ceramics used in the present invention as a carrier for activated sludge, it is necessary to use a cassette made of a plate-shaped porous ceramic or a cassette filled with ceramics such as tip-shaped ceramics and saddle-shaped ceramics as fillers. It turned out to be the most hopeful.

Therefore, the case where the cassette constituted as the ceramics is applied to the treatment of sewage and industrial wastewater will be described according to FIG. 1 with respect to the treatment conditions and the structure of the biochemical reaction tank in the sewage treatment plant.

1 shows ceramics such as a cassette composed of a plate-shaped porous ceramic having a blast furnace material as a main component in the middle of the first aeration tank 2 and a second aeration tank 3 or a cassette filled with a filler of ceramics (for example, a tip shape). A sewage biochemical treatment apparatus in which a plurality of sets of cassettes 1 and (hereinafter referred to as the same) are disposed, and an air diffuser 11 for air shooting is disposed below the first aeration tank 2 and the second aeration tank 3. ) Is connected to a blower (9) used to shoot air through a pipe.

In addition, an ORP sensor 4 is disposed in the second aeration tank 3 on the side of discharging the treated water 12. The sensor 4 is connected to the ORP control device 5, and the ORP control device 5 A solenoid valve 10 for adjusting the amount of air shot is connected via a lead wire, and the solenoid valve 10 is a diffuser 11 used for air shooting and a blower 9 for air shooting. It is arrange | positioned in between, and it operates by the instruction | indication of the ORP control apparatus 5, and it is possible to control the amount of air shots.

6 is a recorder, 7 is a sewage supply pump, and 8 is a sewage control tank.

A method of treating sewage by the biochemical reaction tank shown in FIG. 1 will be described.

First, when a mixed liquid of activated sludge (active sludge concentration 1000-5000mg / l) is added to the first and second aeration tanks shown in FIG. 1, the activated sludge enters the pores or gaps of the ceramics. Interrupted, the first aeration tank 2 and the second aeration tank 3 become substantially transparent after 5-20 hours.

Thus, air or oxygen-enriched air or oxygen is blown from the air-spilling fusion engine 11 and the air is blown out of the first and second aeration tanks.

Next, the apparent passage time (corresponding to the processing time) through which the sewage is passed and the sewage passes through the first aeration tank 2, the ceramic cassette arranging unit and the second aeration tank 3 is adjusted to 16 hours. The treatment time is gradually shortened to form a state conforming to the environment of the activated sludge, and the treatment is normally performed for 2-6 hours.

Condition composition which conforms to this environment is good for about 10-30 days.

In addition, the decomposition of contaminants contained in sewage in a fixed-bottom bioreactor using ceramics mainly composed of blast furnace materials for immobilization carriers of activated sludge is oxygen-containing in the sewage flowing in the first aeration tank 2 of FIG. The used air saw dissolves the oxygen by blowing the gas of the dragon, and when water is passed through the ceramic cassette (1), the activated sludge attached to the cassette decomposes the sewage contaminants using dissolved oxygen. do.

In addition, by dissolving oxygen in the second aeration tank 3, dirty matter which has not been decomposed in the cassette is decomposed or odor causing substances are removed, and the treated water is brought into an aerobic state.

As a result, as described later, an excellent effect is obtained as compared with the conventional method.

Ceramics containing the blast furnace material used in the present invention as a main component are blended with conventionally known ceramic raw materials, such as alumina, silica, and other inorganic raw materials, in a blast furnace material having a weight ratio of over 50% to -90%, preferably 70-85%. In the case of using ceramics as a plate-like cassette, the pore-forming agent such as sawdust, rice husk, urethane powder, and the like is further blended, mixed with water by kneading, and then molded into a predetermined shape and then fired. Manufacture.

The shape of the pores of the porous ceramics used in the present invention is not particularly suitable, but the most suitable hole diameter is about 1-5 mm, and the size of the hole does not need to be particularly uniform. If it is distributed, it can be used sufficiently.

In addition, the structure of the pores of the porous ceramics significantly affects the blockage of the adhesive sewage treatment of activated sludge.

For example, in the case of a so-called two-dimensional structure in which the inlet and the outlet are through the air, such as honeycomb tubs, the pores of the ceramics are simply blocked when the sewage treatment is carried out, but the holes are divided into the lengths of the so-called three-dimensional structure connected to each hole. As a result, it is empirically clear that occlusion is difficult to occur.

On the other hand, in the case of a cassette filled with a ceramic filler, the shape and size of the ceramic to be filled are not particularly limited, but a simple shape may be used as much as possible.

For example, as the shape of the filler, a plate shape, a cylindrical shape, a semicircle shape, a saddle shape, or a particle shape is most suitable, and the size of the filler is about 10-100 mm in outer diameter.

If the size of the filler is less than 10 mm, it is easy to block, while if the size of the filler is more than 100 mm, there is a problem such that the attached activated sludge easily flows out.

In the case of forming a cassette using such ceramics, a container may be prepared by, for example, a metal mesh and filled with ceramics therein.

Next, the method of air-swinging to the biochemical reaction tank (aeration tank) in this invention is demonstrated.

According to the research of the inventors, the relationship between the ORP of the aeration tank and the treated water of the activated sludge treatment of sewage and industrial wastewater is 20 mg / l of the biochemical oxygen demand (BOD) of the treated water if the ORP of the aeration tank is managed within a predetermined range. It becomes clear that it can be kept below.

For example, in the case of a fluidized bed aeration tank of sewage using blast furnace powder, air-swept conditions affect the treatment performance of decomposable supernatant and activated sludge properties in addition to the dispersibility of blast furnace materials.

Therefore, air sawing satisfies both the dispersibility and processing performance of blast furnace material.

The activated sludge treatment performance is closely related to the redox potential of the aeration tank. If OSR is used as an indicator, the amount of air released can be controlled to improve the decomposition of soils, which is effective in suppressing the supernatant reaction and bulking of activated sludge.

For activated sludge treatment in sewage, the appropriate ORP range is 0–100 mV (measured by gold or gold-antimony, alloy / silver. Silver chloride composite electrodes, hereinafter ORP values indicate the measured values of these electrodes).

In the case of activated sludge treatment of sewage, there is a significant correlation between the ORP value of the aeration tank and the amount of air shooting. In the general treatment, the amount of air shooting corresponding to the ORP may be controlled. The amount of air shot is insufficient to uniformly disperse the blast furnace material having a particle diameter of 0.02-0.5 mm in the aeration tank.

For this reason, in this invention, it is necessary to supply the amount of air shot required to maintain this ORP by setting ORP setting target more than + 50mV.

On the other hand, the upper limit of ORP can be up to + 150mV in the adhesion of activated sludge to blast furnace material.

That is, in the case of no addition of the blast furnace material of the conventional method, when the ORP + 100mV or more is reached, the supernatant reaction occurs remarkably, the pH of the aeration tank decreases, the denitrification reaction in the sludge sedimentation tank causes sludge flotation and the outflow. Leads to deterioration.

By the way, when blast furnace material is added, ORP + 100mV or more, the reaction occurs like the conventional method, but the pH decreases, sludge sludge, outflow does not occur, and the treated water quality is good, and there is no problem of treatment performance. .

However, when ORP exceeds + 150mV, the activated sludge is subdivided by shooting air and it is difficult to attach to blast furnace material.

In this regard, considering the dispersibility of blast furnace material and adhesion of activated sludge, it is most appropriate to keep the aeration tank ORP in the range of + 50-150mV.

Also, as described above, firing air from a fixed-bottom biochemical reaction tank using porous ceramics or tip-shaped ceramics mainly composed of blast furnace materials as an immobilization support for activated sludge is performed in the aeration tank ORP and Since there is a close relationship between the treatment performance, the ORP sensor 4 is provided in the second aeration tank of FIG. 1, and the ORP of this second aeration tank is within a predetermined range, for example, in the case of sewage treatment, 0- + 150 mV. Air is blown into the 1st aeration tank and the 2nd aeration tank so that it may become so.

In addition, in the case of the fixed bottom activated sludge treatment using porous ceramics or tip-shaped ceramics mainly composed of blast furnace materials as the immobilization carrier of the activated sludge, the activated sludge is held almost completely inside the ceramic cassette, Since it hardly flows in the), the sludge settling existing in the general activated sludge treatment can be omitted or simplified in the case of the present invention.

Treatment of sewage with bioactive sludge by attaching activated sludge to ceramic cassettes When the long term treatment is carried out, the cassette of ceramics may be occluded due to the suspension of floating entertainment substances or activated sludge contained in the sewage.

This blockage is likely to occur in the first cassette (the portion closest to the first aeration tank 2) of the tank B, which is closed in FIG. 1, when the blockage of the cassette occurs, or when it is close to the blockage. Remove the cassette, move the second cassette to the first position, and move the third cassette to the second position in the horizontal direction in order, so that the new cassette or the closed cassette is placed in the last cassette (close to the second aeration tank 3). Install the replay.

In this way, the circulating exchange of ceramic cassettes is the most suitable method because the cassettes can be exchanged while performing sewage treatment, and the treatment efficiency and treatment water quality are not reduced.

In addition to the sewage described above, the activated sludge treatment technology of the present invention is an industrial wastewater, for example, gas waste liquid discharged from coke oven of re-iron, gasification of coal, drainage discharged from liquefaction plant, and petroleum refining process. In the case of adapting to drainage discharged from public fields and drainage from fermentation plants such as alcohol, the treatment efficiency and treatment water quality are improved in the same manner as in the case of activated sludge treatment of sewage.

Next, the Example of this invention is described.

Example 1

600 g of blast furnace material with a particle diameter of 0.02-0.2 mm (equivalent to 30 kg per 1 m3 of aeration tank, 3% by weight / volume) in the aeration tank of the ORP-controlled activated sludge treatment apparatus which controls the ORP of the aeration tank (capacity 20l) to +100 mV. In addition, a high concentration of artificial sewage having the composition and properties shown in Table 4 was treated.

The relationship between the treatment time and the quality of the treated water is shown in Table 5, and the sedimentation behavior of activated sludge after blast furnace addition is shown in Table 6, and the sedimentation behavior of activated sludge 30 days after blast furnace addition is shown in FIG.

[Table 4 Composition and Characteristics of Artificial Sewage]

TOC: All Organic Carbon

TS: All solids

CODMn: chemical oxygen demand

σ: standard deviation

[Table 5 Relationship between treatment conditions and treated water quality]

TOC: Allied Carbon

SS: Suspended material

[Table 6 Effect of Blast Furnace on Active Sludge Characteristics]

MLSS: Mixedliquor Suspended Solids

SV3O: Volume of sludge after standing for 30 minutes

SVI: Sludge Volume Index

MLVSS: Mixedliquor Volatile Suspended Solids (volatiles when MLSS is dried and heated at 600 ℃)

In the results of Table 5, the activated sludge treatment with the blast furnace material was treated with 2.4-4.8 hours, and the BOD5 of the treated water was less than 5 mg / l (more than 98% removal) and CODMn was 14-27 mg / l (control rate 93- 95%) and SS of 11-38 mg / l and the use of blast furnace material for the immobilized carrier of activated sludge can be highly effective treatment and it is clear that good treatment water quality is obtained.

In addition, the settling property of the activated sludge indicates the result of measuring the settling curve of the activated sludge 30 days after the addition of the blast furnace material.

In FIG. 2, the addition of 3% by weight / volume of blast furnace material (denoted as-○-and-◎-) indicates that the settling velocity in the free settling range is 3-4 m / hr. The one without additives (expressed as -Δ-) is 1.5-2.0 m / hour.

Thus, the blast furnace material has an action of promoting the settling speed of the activated sludge.

Table 6 shows the change over time of the activated sludge after blast furnace addition, and the MLVSS (volatile fraction of sludge) after blast furnace addition increased to 907 mg / l but to 2,200-3,200 mg / l after 10-30 days.

However, the SVI, which is an indicator of sedimentation of activated sludge, is 16-27, and the increase in MLVSS does not decrease the sedimentation.

In this way, when the blast furnace material is added to the aeration tank of the activated sludge treatment apparatus, the treatment efficiency, the treated water quality, the activated sludge properties, etc. are remarkably improved.

Example 2

According to the conditions of Example (1), the process was performed using the real sewage (classification type) of the big city which shows a characteristic in Table 7.

Table 8 shows the relationship between treatment time and treated water quality.

[Table 7 Characteristics of Urban Sewage Used in Experiments]

Table 8 Relationship between treatment time and treated water quality (mg / l)

In the results of Table 8, the treatment time was changed in the order of 6 hours, 4 hours, 3 hours, and 2 hours from the standard 8 hours treatment, but the BOD of the treated water was 5 mg / l or less (removal rate 74-94%). COD is 9.8-16.7 mg / l and TOC is 5.3-14.3 mg / l.

In view of this, the use of blast furnace material as an immobilization carrier for activated sludge in the fluidized bed treatment improved the treatment efficiency by 3-4 times and miniaturized the treatment equipment.

Example 3

Biochemical reaction tank of the experimental apparatus of FIG. 1 (30 l of activated sludge mixed liquid collected from aeration tank of municipal sewage treatment in 10 l of 2 aeration tank (3) .... Next, a cassette 1 made of five porous ceramics containing a blast furnace material having a plate-shaped hole size of 1-3 mm in the tank B as a main raw material (80% by weight) is installed.

After about 3 hours, it was confirmed that both aeration tanks 2 and 3 became transparent, and activated sludge was adsorbed inside the porous ceramics.

In this state, the time for passing the artificial sewage shown in Table 9 from the first aeration tank 2 to the second aeration tank 3 is 16 hours, 12 hours, 8 hours, 6 hours, 4 hours, 3 hours, 2 hours. The activated sludge adhered through the water was raised to adapt to artificial sewage, and then the treatment was performed for a long time with a passage time of 2 hours.

At this time, the ORP of the second aeration tank 3 was controlled to +100 mV to adjust the amount of air blown into the first aeration tank 2 and the second aeration tank 3. In addition, the dissolved oxygen concentration of the first aeration tank (2) is 0.5-1. OPPm and the 2nd aeration tank 3 were 2-5 ppm.

The processing performance is shown in Table 10.

Table 9 Composition and Properties of Artificial Sewage (mg / l)

[Table 10 Relationship between treatment time and treated water quality]

SS: Suspended material

In the results of Table 10, the biochemical reaction tank in which the five plate-shaped porous ceramic cassettes are arranged has a BOD volume load of about 4-5 times the normal activated sludge treatment, that is, BOD 2.4 kg / ㎥ days BOD5 of the treated water was 5 mg / or less (98% or more removal), CODMn (average value) was 8.7 mg / (68-89% removal) and SS (average) 10.1 mg /, and good treatment was possible.

In addition, in the method of the present invention, there is no need to provide a sludge settling tank for solid-liquid separation between the treated water and the activated sludge, and the treatment efficiency is about 4-5, compared to the general activated sludge treatment of sewage. More than doubled it became apparent.

Example 4

In place of the plate-shaped porous ceramics of Example (3), a cassette containing five pieces of porous ceramics having a plate-shaped blast furnace material having a hole size of 2-5 mm as the main raw material (75% by weight) was used. Sewage treatment was performed.

The actual sewage was treated under the same conditions as in Example (1) by collecting sewage from a sewage treatment plant flowing into a sewage treatment plant of a large city with a population of more than 1 million. Table 11 shows the characteristics of urban sewage used in the experiment. Table 12 shows the relationship between water quality and water quality.

[Table 11 Characteristics of Urban Sewage Used in Experiments]

TABLE 12

When treating real sewage with a high concentration of suspended solids (SS) compared to artificial sewage, there is a concern that the cassette of the porous ceramics is closed.

In this example, the sewage was passed through 125-175 times (2.4-3.5 m 3) with respect to the porous ceramic (about 20 L in volume), and the state became close to the blockage.

Thus, the plate-shaped porous ceramics close to the first aeration tank 2 were taken out and washed with high pressure water, and the porous ceramics were placed in the last portion close to the second aeration tank 3 to perform actual sewage treatment. As a result, the water of substantially the same quality as the treated water shown in Table 12 was obtained.

As a result, by treating the actual sewage by the method of the present invention using plate-shaped porous ceramics, a treatment efficiency of about 4-5 times or more is obtained than the activated sludge treatment of general municipal sewage, and SS of treated water is also obtained. No more than 20 mg / l of sludge settling tank is required.

Moreover, it became clear that even if the porous ceramics were blocked, it could be easily recycled and used by washing with high pressure water.

Example 5

Instead of the porous ceramics of Example (3), using a cassette filled with a ceramic (about 20 mm in diameter) made of a semi-circular blast furnace material as the main raw material (80% by weight) as a filler, Treatment was performed under the same conditions using artificial sewage.

The results are shown in Table 13.

[Table 13 Relationship between treatment time and treated water quality]

As a result of Table 13, it was evident that the treatment performance was almost unchanged even if a cassette filled with the ceramics was used instead of the plate-shaped porous ceramics.

In other words, the cassette filled with the ceramics also has the property of preserving activated sludge, and it is clear that the entertainment materials of the artificial sewage are sufficiently decomposed and removed. The treatment efficiency is also improved by about three times that of the activated sludge treatment of general sewage, and the treated water quality is also good.

Example 6

Differentiation (average particle size 0.05mm) of blast furnace wood of 0.02-0.2mm is placed in the aeration tank (fluid-filled reactor) of the uniformly mixed activated sludge treatment apparatus which is processing the gas waste liquid generated from the coke oven of steel mill. 50 kg per m3 was added, and the aeration tank ORP was again controlled at 200-250 mV (gold-silver / silver chloride composite electrode measurement), and the gas waste liquid (4-fold dilution) showing the properties in Table 14 was treated. It was. Further treatment conditions are as follows.

COD volume load 3.5-4.O㎏ / ㎥.day

Processing time 4.4-6.7 hours

Oni bounce rate 100%

Table 14 shows the quality of the treated water which has been treated as the above treatment conditions.

Table 14 Water Quality of Supply Wastewater and Treated Water (mg / l)

From the results in Table 14, it became clear that the addition of blast furnace powder to the aeration tank can treat the gas waste liquor as a high load with a COD volumetric load of 3.5-4.0 kg / m3.day and as a short time of 4.4-6.7 hours. .

The method of the present invention using the blast furnace material as an immobilized carrier for activated sludge is remarkably effective in improving the water quality of the activated sludge treated water and the sedimentation property of the activated sludge, or inhibiting the bulking of the activated sludge.

In addition, the process of the present invention can shorten the treatment time by about 1 / 2-1 / 4 of the standard activated sludge treatment without blast furnace additives without impairing the processing performance.

As a result, the treatment efficiency can be improved and the treatment equipment can be simplified. In addition, the method of the present invention using ceramics containing blast furnace material as a main raw material for immobilization carriers of activated sludge has the following effects.

(1) The method of the present invention does not require uniform mixing of activated sludge in a biochemical reaction tank (corresponding to an aeration tank), compared to a homogeneous mixed type used for treating sludge of industrial sewage or industrial wastewater. Since it is only necessary to dissolve oxygen in industrial wastewater and pass water through it, the power required for air used for air scavenging is at a minimum compared with the conventional method.

(2) Ceramics, which are mainly composed of blast furnace materials, have excellent functions of holding activated sludge, so that activated sludge hardly flows out of the treated water, so that the sludge sedimentation tank used for general activated sludge treatment can be omitted. Alternatively, the sludge settling tank can be simplified.

(3) The quality of the treated water is good even if the treatment is carried out at a load of about 3 times or more that of the general activated sludge treatment.

Therefore, the biochemical reaction tank (corresponding to the aeration tank) can be significantly miniaturized.

(4) It is possible to omit or simplify the activated sludge settling tank or to reduce the size of the biochemical reaction tank (aeration tank), which greatly simplifies the entire sewage treatment.

(5) Because activated sludge is immobilized in ceramics, bulking of activated sludge which does not occur in general homogeneous mixed sludge treatment does not occur, so the treatment is stable and good treatment can be achieved.

Claims (11)

In the sewage treatment method which uses the blast furnace slag as an immobilization carrier of activated sludge by adding the crushed product which crushed the blast furnace slag obtained by cooling the molten slag which generate | occur | produces as a by-product from a blast furnace at the time of steelmaking, and is used as an immobilization support of activated sludge, The blast furnace powder prepared by quenching slag with water is added to the aeration tanks (2) and (3) of the activated sludge treatment plant, and the blast furnace material prepared by quenching the slag with water is used as immobilization carrier for activated sludge. A fluidized bed activated sludge treatment method for sewage or industrial wastewater. The amount of air in the aeration tanks (2) and (3) to which the above-mentioned blast furnace powder is added is adjusted so that the redox potential of the aeration tanks (2) and (3) is within a predetermined target value range. A fluidized bed activated sludge treatment method of sewage or industrial wastewater, characterized by management control. The volume of 2-5 weight% / volume of aeration tanks (2) and (3) is added to the aeration tanks (2) and (3) of the blast furnace material of 0.02-0.5 mm, characterized by the above-mentioned. Active bottom sludge treatment method for sewage or industrial wastewater. 10-50 kg / aeration tank (2) and (3) 1m <3> of blast furnace materials of 0.02-0.5 mm were added to aeration tanks 2 and 3, characterized by the above-mentioned. Method of treatment of fluidized bed activated sludge for sewage or industrial wastewater. In the sewage treatment method in which the blast furnace slag obtained by crushing the blast furnace slag obtained by cooling the molten slag generated as a by-product from the blast furnace is added to the sewage equipment, and using the blast furnace slag as an immobilization carrier of activated sludge, it is generated as the by-product. Sewage or industry characterized in that ceramics, which are mainly composed of blast furnace materials, made by quenching slag with water, are installed in aeration tanks (2) and (3) of an activated sludge treatment plant and used as immobilization carriers of activated sludge. Fixed bottom activated sludge treatment method of wastewater. The fixed bottom activated sludge treatment method of sewage or industrial wastewater according to claim 5, characterized by using a cassette (1) made of plate-shaped porous ceramics whose main raw material is the blast furnace material as an immobilization carrier of the circular sludge. 6. The fixed bottom activated sludge treatment method of sewage or industrial wastewater according to claim 5, characterized in that a cassette (1) filled with tip-shaped ceramics mainly composed of blast furnace material as a main component is used as an immobilization carrier of activated sludge. . The method of claim 5, wherein a cassette (1) filled with saddle-shaped ceramics containing the blast furnace material as a main component as an immobilization carrier of activated sludge is used. . The method according to any one of claims 5 to 8, wherein the activated sludge is fixed to ceramics containing the blast furnace material as a main component, and the treatment is carried out through sewage or industrial wastewater in which oxygen is dissolved by spraying air in advance. Activated sludge treatment method of sewage or industrial wastewater. 10. The treated water according to claim 9, wherein the activated sludge is immobilized on ceramics containing the blast furnace material as a main component, and the treated water after the biochemical treatment is treated by passing air through sewage or industrial wastewater in which oxygen is dissolved. An active sludge treatment method for sewage or industrial wastewater, characterized in that for controlling the amount of air to shoot air into the sewage or industrial wastewater in advance so that the oxygen reduction potential of (12) is within a predetermined target value range. To cross the flow direction of sewage or industrial wastewater by using a cassette (1) consisting of porous plate-shaped ceramics mainly composed of blast furnace materials as the main component of the activated sludge, or a cassette filled with blast furnace materials. A plurality of cassettes are arranged to perform biochemical treatment to draw out the cassette closest to the inflow side of the sewage or industrial wastewater, and the subsequent cassettes are sequentially moved in parallel to the inflow side of the sewage or industrial wastewater. Inserting a cassette or a cassette after regeneration, while the extracted cassette is subjected to a regeneration treatment to remove deposits and used at the rear of the cassette group for biochemical treatment while exchanging a plurality of cassettes sequentially. Sewage characterized by Fixed deck activated sludge treatment process of the industrial waste water.

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