KR100905908B1 - Sludge treatment method - Google Patents

Abstract

A method for processing sludge is provided to prevent environmental contamination according to sludge disuse by minimizing generation of final sludge through decomposition of the sludge. A method for processing sludge includes the following steps of: preparing the sludge(S10); decomposing the sludge with anaerobic microscopic organisms biologically(S20); decomposing the sludge with aerobic microscopic organisms biologically(S30); processing the sludge with acid(S40); separating the sludge(S50); and oxidizing the sludge(S60). The method for processing the sludge further includes a filtration step(S21) and a concentration step(S23).

Description

Sludge Treatment Method

The present invention relates to a sludge treatment method, and more specifically, using a biological treatment and a chemical treatment in combination, after the chemical treatment and the solid-liquid separation, by circulating the process several times to decompose the sludge, to minimize the final sludge generation sludge disposal The present invention relates to a sludge treatment method that can prevent environmental pollution.

As urban concentration of the population and the development of various industries, living sewage and factory wastewater discharged from homes and factories are increasing. Since the amount of such wastewater increased sometime beyond the limit of natural purification, a purification facility for artificially purifying the wastewater was proposed. Waste water means dirty water and mixed water or waste, and the waste water purification treatment device is to remove the dirt or waste from the water. The kind of wastewater purification treatment apparatus has been developed in various ways. Most wastewater treatment systems generally accept wastewater and settle the heavy contaminants once, add microorganisms to light organic matter that has not yet settled, and decompose and remove the organic matter, and the microbially treated water. Is physically filtered through a filter, and finally chemically chlorinated.

On the other hand, various sludges are obtained during the above sewage treatment process. That is, chemically precipitated sludge is obtained in the first stage, activated sludge is obtained by a drop filter, and then immersed sludge is obtained. Conventionally, such sludge was generally landfilled, but was banned due to environmental pollution, and as such landfilling was banned, most of the sludge was disposed of at a low-cost offshore dumping method, but this plan is also to be banned in the future. to be.

Accordingly, in the conventional sewage treatment, an anaerobic digester was installed and operated to stabilize and destroy sludge generated during sewage treatment, but the sludge destruction efficiency of the anaerobic digester was about 30%. The sludge was mostly. And the sludges carried out in this way were transported to an offshore dumping, landfill or waste facility for incineration, which requires a lot of cost and has a problem of causing secondary environmental pollution due to sludge disposal.

As a solution to this problem, a method of improving the destruction efficiency of sludge through biodegradation by microorganisms and hydrolysis by chemical treatment has been proposed. The process consists of a high temperature aerobic bioreaction step, solid-liquid separation step and chemical treatment step, and the sludge introduced is passed through each step in order to be destroyed, and each step is cycled several times, It will improve the breaking efficiency. However, this method has almost 100% destruction efficiency for uniform sludge, but complex sludge, especially sludge that contains a lot of fibers that are insoluble in water or other solvents such as sewage sludge. The destruction efficiency for is less than expected. In addition, in order to improve the sludge destruction efficiency, operating costs for power and chemicals are increased. For example, defoamers are frequently blocked by waste included in the sludge, thereby increasing maintenance costs. That is, such a method is effective in destroying sludge composed of a uniform or single component, but there are many problems to apply to various sludge destruction, which is a very complex component like sewage sludge.

The present invention has been made to solve the above problems, by using a combination of biological treatment and chemical treatment, the solid-liquid separation after the chemical treatment, and by circulating the process several times to decompose the sludge, to minimize the final sludge generation to sludge disposal It is an object of the present invention to provide a sludge treatment method that can prevent environmental pollution.

Another object of the present invention is to provide a sludge treatment method capable of exhibiting excellent sludge destruction efficiency regardless of constituents of sludge by removing a fiber or garbage by introducing a filtration step.

In addition, another object of the present invention is to provide a sludge treatment method capable of minimizing odor generation by controlling microorganisms and acidity in the reaction tank.

Another object of the present invention is to provide a sludge treatment method which can reduce sludge treatment costs by recycling methane gas and heat generated during the process to the driving energy and other processes of the sludge treatment system.

The sludge treatment method according to the present invention for achieving the above object comprises the steps of preparing a sludge; An anaerobic bioreaction step of biologically decomposing the sludge introduced by the anaerobic microorganism; A high temperature aerobic bioreaction step for biologically decomposing sludge discharged and introduced after the progress of the anaerobic bioreaction step by high temperature aerobic microorganism; A first chemical treatment step of acid treatment of sludge discharged after the high temperature aerobic bioreaction step; A solid-liquid separation step of separating the solid-liquid sludge discharged after the first chemical treatment step proceeds; And a second chemical treatment step of oxidizing sludge discharged after the solid-liquid separation step proceeds, wherein the sludge discharged after the second chemical treatment step is performed several times in the anaerobic bioreaction step or the high temperature aerobic organism. It is characterized by being returned to the reaction step and recycled.

Here, the anaerobic bioreaction step and the high temperature aerobic bioreaction step may further include a filtration step of filtering the sludge discharged after the progress of the anaerobic bioreaction step, and a concentration step of concentrating the sludge filtered from the filtration step. have.

In addition, the anaerobic bioreaction step may receive the heat generated from the high temperature aerobic bioreaction step to maintain the reaction temperature.

In addition, methane gas produced in the anaerobic bioreaction step may be recycled as energy in a process other than sludge treatment.

As described above, the present invention uses a combination of biological treatment and chemical treatment, but after the chemical treatment, the solid-liquid separation, and by circulating the process several times to decompose the sludge, to minimize the final sludge generation to reduce environmental pollution due to sludge disposal It is effective to prevent.

In addition, the present invention by introducing a filtration step to remove fibers or garbage, there is an effect that shows excellent sludge destruction efficiency regardless of the components of the sludge.

In addition, the present invention by controlling the microorganism and acidity in the reaction tank, there is an effect of minimizing the generation of odor.

In addition, the present invention has the effect of reducing the sludge treatment cost by recycling the methane gas and heat generated during the process to the driving energy and other processes of the sludge treatment system.

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

1 is a flowchart showing a sludge treatment method according to a preferred embodiment of the present invention step by step, Figure 2 is a schematic diagram showing a sludge treatment system according to a preferred embodiment of the present invention.

As shown in these figures, the sludge treatment method according to a preferred embodiment of the present invention, the preparation step (S10), anaerobic bioreaction step (S20), high temperature aerobic bioreaction step (S30), and the first chemical The treatment step (S40), the solid-liquid separation step (S50) and the second chemical treatment step (S60), the sludge discharged after the second chemical treatment step (S60) several times the anaerobic bioreaction step (S20) ) Or the high temperature aerobic bioreaction step (S30) is recycled.

First, the preparation step (S10) is to prepare a sludge treatment, collecting the various sludge generated in the sewage treatment in one place, the anaerobic bioreaction tank (S20) proceeds through the anaerobic bioreaction step (S20) through the transfer pipe 180 Inflow to (110).

Next, the anaerobic bioreaction step (S20) is a step of generating biodegradation and methane gas by anaerobic microorganisms, after receiving the incoming sludge in the anaerobic bioreactor 110 and proceeds to the biodegradation process. In the biodegradation process, the solids are broken down into water, methane gas and some carbon dioxide by anaerobic microorganisms, and some of the sludge is destroyed. In more detail, the solid in the anaerobic bioreactor 110 is heated, mixed, and decomposed by microorganisms in an environment where oxygen is not supplied. At this point, about 30% or more of the solids are converted to gas, which is mainly converted to methane and some carbon dioxide. In addition, according to a preferred embodiment of the present invention, the sludge flowing through the sludge treatment system 100 is chemically treated and returned and circulated so that biodegradation can occur more easily, so that about 40% of the active solids are decomposed and disappeared. .

On the other hand, the anaerobic bioreactor 110 is effectively operated when maintaining a temperature of about 38 ℃, while conventionally using a methane gas generated during the decomposition process to heat the reaction tank, in a preferred embodiment of the present invention the subsequent step Since the anaerobic bioreactor 110 is heated by using heat generated by itself in a high-temperature aerobic bioreaction step (S20), the methane gas generated during biodegradation becomes surplus energy and thus can be recycled for purposes other than sludge treatment. Can be.

As described above, the anaerobic bioreaction step (S20) is performed in the anaerobic bioreactor 110. The anaerobic bioreactor 110 may be formed in a variety of forms, the bottom of the concave "egg shape" is the most efficient and efficient. The reason is that the floor is concave, which requires very little energy to collect the sludge to the floor.

On the other hand, although not shown, the anaerobic bioreactor 110 should be provided with a variety of devices for the progress of the anaerobic bioreaction step (S20). That is, the anaerobic bioreactor 110 should be provided with a sludge mixing device. The sludge mixing device serves to mix the sludge mixed with the anaerobic microorganisms that enter the anaerobic bioreactor 110 and then sink and stop biodegradation. In addition, the anaerobic bioreactor 110 should be equipped with a reactor heating system. The anaerobic bioreactor 110 is effective when operated in a narrow range of temperature between approximately 32 ℃ to 38 ℃, the temperature of the sludge flowing into the anaerobic bioreactor 110 is usually 15 ℃ to 25 ℃ the anaerobic The bioreactor 110 must be additionally heated. In a preferred embodiment of the present invention uses the heat generated in the high temperature aerobic bioreaction step (S30), the reactor heating system is a device for heating the anaerobic bioreactor 110 using this heat. The reactor heating system may be installed inside or outside the anaerobic bioreactor 110, but is preferably installed outside the anaerobic bioreactor 110 to minimize energy waste. In addition, the anaerobic bioreactor 110 should be provided with a gas collection system. The gas collection system is a device for collecting and recycling methane gas and carbon dioxide generated through the anaerobic bioreaction step (S20). Such a gas collection system is preferably installed in the lid of the anaerobic bioreactor 110 due to the nature of the gas.

On the other hand, according to a preferred embodiment of the present invention, the sludge that passed through the anaerobic bioreaction step (S20) is subjected to a filtration step (S21) and a concentration step (S23) in order before entering the high temperature aerobic bioreaction step (S30). .

First, the filtration step (S21) is a step of filtering the sludge introduced from the anaerobic bioreaction step (S20), plastic, fibers that are not decomposed by the anaerobic bioreaction step (S20) using the screen 120 Filter out common waste such as hair and hair. These wastes frequently cause problems in the operation of the sludge treatment system 100 during operation or in machine operation, and should be removed beforehand to further improve the efficiency of the sludge treatment system 100.

Next, the concentration step (S23) is a step of concentrating the sludge that passed through the filtration step (S21), the sludge decomposed first through the anaerobic bioreaction step (S20) using a concentrator 130 approximately 6.5 It is concentrated to%, in order to promote the growth of high temperature bacteria inhabiting the high temperature aerobic bioreactor 140, the high temperature aerobic bioreaction step (S30) proceeds. As such, the sludge concentrated through the concentration step (S23) is introduced into the high temperature aerobic bioreactor 140 in which the high temperature aerobic bioreaction step (S30) is performed through the transfer pipe 180.

Subsequently, the high temperature aerobic bioreaction step (S30) is a step of biologically decomposing the first sludge, filtered, and concentrated sludge by the high temperature aerobic microorganism as described above, and introducing the sludge into the high temperature aerobic bioreactor 140. After receiving it in the biodegradation process. In the biodegradation process, organic matter is decomposed into water and carbon dioxide, and inorganic matter is dissolved in water to form inorganic salts. At this time, heat is generated by itself in the high temperature aerobic bioreaction step (S30), this heat is used to maintain the high temperature aerobic bioreactor 140 at 42 ℃ to 70 ℃, the rest as described above, anaerobic organism It is used to raise and maintain the temperature of the reactor (110).

 The high temperature aerobic bioreaction step (S30) is also a biological destruction step, unlike the anaerobic bioreaction step (S20) uses air-like microorganisms that develop well at high temperatures. Such high temperature microorganisms are more aggressive in sludge destruction, and these high aerobic microorganisms decompose organic matter in the concentrated sludge, thereby greatly reducing the amount of sludge. The high temperature aerobic bioreaction step (S30) is carried out by the high temperature heat generated by the microorganisms in accordance with the thermal conductivity of the high temperature aerobic bioreactor 140. Here, the oxygen used in the high temperature aerobic bioreaction step (S30) may be supplied to the air in the form of droplets or pure oxygen at the bottom portion of the high temperature aerobic bioreactor 140 using power.

Meanwhile, in the high temperature aerobic bioreaction step (S30), the sludge undergoing biodegradation is released and dehydrated, and then chemically treated to make biodegradation easier and then flows back into this step (S30) for further reduction. do. Finally, the active solids that are decomposed and left in the anaerobic bioreaction step (S20) are decomposed into water and carbon dioxide and are almost destroyed, and the inert solids are dissolved in water to form inorganic salts.

This high temperature aerobic bioreaction step (S30) is subdivided into solids decomposition process, nitrogen and phosphorus treatment process and heavy metal treatment process.

In the solid decomposition process, the active solids are converted to carbon dioxide, water and heat, and the inert solids are dissolved in water and converted to inorganic salts (N, P, K, Ca, Mg). At this time, since the inorganic salts are not suspended solids, they do not pollute the environment. Therefore, inorganic salts dissolved in water are sent back to the initial stage of sewage treatment before sludge treatment and mixed with the discharged water. In addition, the nitrogen and phosphorus treatment process is a process of treating nitrogen and phosphorus discharged in the process of sludge destruction in the high temperature aerobic bioreactor 140, the nitrogen and phosphorus may be extracted and used as a fertilizer. In addition, the heavy metal treatment process is a process of controlling the amount of heavy metal released for the environment and the efficiency of the sludge treatment system 100.

The high temperature aerobic bioreaction step (S30) is carried out in a high temperature aerobic bioreactor 140. Since the high temperature aerobic bioreactor 140 should be operated at 42 ° C. to 70 ° C. by self-generated heat, it is preferable that the high temperature aerobic bioreactor 140 is heat-insulated for energy conservation.

On the other hand, although not shown, the high temperature aerobic bioreactor 140 should be provided with a variety of devices for the progress of the high temperature aerobic bioreaction step (S30). That is, the high temperature aerobic bioreactor 140 should be provided with a jet pump. The jet pump is a device for introducing sludge into the high temperature aerobic bioreactor 140, and is formed to stably flow into the high temperature aerobic bioreactor 140 without clogging even though highly concentrated sludge. In addition, the high temperature aerobic bioreactor 140 should be provided with jet aeration. The jet aeration is an aeration device, which is very effective for mixing concentrated sludge. Moreover, it uses less air than other methods and therefore requires less energy to cool, resulting in ideal conditions for maintaining high temperatures in the high temperature aerobic bioreactor 140. The jet aeration is a jet that ejects water in the high temperature aerobic bioreactor 140 as a pump, and a jet that ejects pure oxygen or compressed air is operated together and installed inside the tank bottom. In addition, the jet aeration is made of stainless steel or fiberglass material, so there is little possibility of corrosion of the facilities. In addition, the high temperature aerobic bioreactor 140 should be provided with a defoamer. When too much foam is generated in the high temperature aerobic bioreactor 140, the bubble remover is operated to remove the generated foam. In addition, the high temperature aerobic bioreactor 140 should be provided with a variety of measuring devices for measuring the amount of inflow, temperature, acidity, dissolved oxygen, and the like.

On the other hand, the high temperature aerobic bioreaction step (S30) uses a high temperature aerobic microorganisms. Thermophilic bacteria are present everywhere on earth, so they eventually reach sludge through sewage. Given the good conditions for bacteria to multiply, they grow very quickly and consume organic matter. In this process, the temperature of the high temperature aerobic bioreactor 140 is raised to 45 ℃ to 55 ℃. At this time, the high temperature aerobic bioreactor 140 may maintain a high temperature state when the waste to be treated is sufficiently accumulated. Therefore, sludge containing a considerable amount of organic matter digested in the anaerobic bioreaction step (S20) should be regularly supplied. At this time, by adjusting the supply amount of the sludge, it is possible to control the degree of odor generation.

Next, the first chemical treatment step (S40) is to improve the dehydration of the sludge by adjusting the acidity for effective dehydration, the high temperature aerobic bioreaction step (S30) is completed and discharged after the transfer pipe 180 After receiving the sludge introduced into the acid treatment tank 150 proceeds to the acid treatment process. At this time, acidity control is controlled through sulfuric acid injection. As such, when the acidity of the sludge is lowered through the first chemical treatment step S40, the overall viscosity of the sludge is lowered, and as a result, the dewatering property of the sludge is improved. In addition, by lowering the acidity of the sludge, it is possible to effectively control the occurrence of odor.

On the other hand, the acid treatment tank 150 should be made of a material that can withstand the acidity, that is, pH less than 2.0, and even at a temperature of 80 ℃ or more, it is preferable that an appropriate vent is installed on the lid. In addition, although not shown, the acid treatment tank 150 should be provided with a mixing device. The mixing device is a device that allows the sludge solids and chemicals to be mixed well by using a propeller mounted on the shaft, and should be capable of underwater operation and maintenance, and should be sized for sludge flotation, and for sludge and hydrolysis. It should be sized to allow the reagents to react effectively. In addition, the material is preferably made of stainless steel or a corresponding material, it should be able to withstand up to pH 2.0. In addition, a foam controller must be installed in the acid treatment tank 150. The foam controller is the same as the foam controller of the high temperature aerobic bioreactor 140. In addition, the acid treatment tank 150 should be provided with a chemical group. The chemical group is a tank for storing acid, hydrogen peroxide, and defoamer, which is built on a concrete base and has a double wall structure. In addition, the acid treatment tank 150 should be provided with a variety of measuring devices for measuring the amount of inflow, temperature, acidity, dissolved oxygen, and the like.

Next, the solid-liquid separation step (S50) is a step of separating the non-decomposed solids and water, and proceeds to the solid-liquid separation using the solid-liquid separator 160. In the solid-liquid separation step (S50), the solids that are not yet decomposed are separated from the liquid (including dissolved inorganic salts), and the solids are subjected to the oxidation treatment tank 170 in which the second chemical treatment step (S60) is performed. Water is returned to the settling basin, which is the initial stage of sewage treatment. In a preferred embodiment of the present invention, the sludge passed through the first chemical treatment step (S40) is introduced into the solid-liquid separation step (S50) to separate the solids and water, and this is introduced into the second chemical treatment step (S60) to the chemical The dehydration process can be operated as efficiently as possible. On the other hand, the solid-liquid separation step (S50) may be used a general dehydrator, because the dehydration of the sludge is improved through the first chemical treatment step (S40).

Finally, the second chemical treatment step (S60) is a step of oxidizing the sludge to be introduced, the oxidation treatment tank (sludge introduced through the conveying pipe 180 after the solid-liquid separation step (S50) is completed ( 170) and the oxidation process proceeds. In addition, the second chemical treatment step (S60) is a biological process for further reduction after the partial hydrolysis to more easily biodegrade the excess biomass generated in the biological process with the organic material of the size difficult to decompose In other words, the anaerobic bioreaction step (S20) and the high temperature aerobic bioreaction step (S30) are introduced again. At this time, the amount of sludge distributed in each of the anaerobic bioreaction step (S20) and the high temperature aerobic bioreaction step (S30) is maintained in an optimal state of the high temperature aerobic bioreactor 140 of the high temperature aerobic bioreaction step (S30). It depends on the degree to which it is made. As such, by sending a portion of the sludge to the anaerobic bioreaction step (S20) after the second chemical treatment step (S60), thereby increasing the production of methane energy in the anaerobic bioreaction step (S20), thereby It is possible to reduce the power required in the high temperature aerobic bioreaction step (S30). As described above, when the bioreaction treatment and the chemical treatment are used together, the sludge is dramatically reduced. In other words, it is impossible to reduce the sludge by more than 90% without properly operating such chemical treatment steps (S40, S60). On the other hand, the oxidation treatment tank 170 is formed in the same shape, material and configuration as the acid treatment tank 150, only the difference in processing method.

The preparation step (S10), anaerobic bioreaction step (S20), high temperature aerobic bioreaction step (S30), the first chemical treatment step (S40), solid-liquid separation step (S50) and the second chemical treatment step ( Through the process of circulating through S60), sludge, that is, about 50% organic matter and 50% inert material is converted into the final three kinds and discharged. That is, inert sludge is dissolved in water and converted into inorganic salts (N, P, K, Ca, Mg), organic matter is converted into carbon dioxide, water, and heat, and general waste is filtered through the screen 120.

As described above, the present invention is the preparation step (S10), the anaerobic bioreaction step (S20), the high temperature aerobic bioreaction step (S30), the first chemical treatment step (S40) is used in combination with biological treatment and chemical treatment And, the solid-liquid separation step (S50) and the second chemical treatment step (S60), and the sludge discharged after the second chemical treatment step (S60) several times the anaerobic bioreaction step (S20) or the high temperature aerobic The sludge treatment method is returned to the bioreaction step (S30) to be recycled. Through this, the final sludge can be minimized to prevent environmental pollution due to sludge disposal. In addition, the present invention can reduce the operating and maintenance costs of the sludge treatment system 100 by recycling the methane gas and heat generated during the process to energy. In addition, the present invention exhibits an excellent sludge destruction efficiency regardless of the sludge component, it is possible to minimize the occurrence of odor to maintain a comfortable environment during the process.

Although the technical spirit of the present invention has been described in detail according to the above embodiment, it should be noted that the above embodiment is for the purpose of description and not for the purpose of limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.

1 is a flow chart showing step by step a sludge treatment method according to a preferred embodiment of the present invention.

Figure 2 is a schematic diagram showing a sludge treatment system according to a preferred embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

Sludge Treatment System: 100 Anaerobic Bioreactor: 110

Screen: 120 Thickener: 130

High temperature aerobic bioreactor: 140 acid treatment tank: 150

Solid-liquid separator: 160 Oxidation tank: 170

Transfer piping: 180

Claims (5)

In the sludge treatment method for treating the sludge discharged from the sewage treatment facility, A preparation step (S10) for preparing the sludge; Anaerobic bioreaction step (S20) for biologically decomposing the sludge introduced by anaerobic microorganisms; A high temperature aerobic bioreaction step (S30) for biologically decomposing sludge discharged and introduced after the progress of the anaerobic bioreaction step (S20) by high temperature aerobic microorganisms; A first chemical treatment step (S40) for acid-treating sludge discharged after the high temperature aerobic bioreaction step (S30) proceeds; Solid-liquid separation step (S50) for separating the solid-liquid sludge discharged after the first chemical treatment step (S40) proceeds; And A second chemical treatment step (S60) for oxidizing the sludge discharged and discharged after the solid-liquid separation step (S50); Sludge discharged after the second chemical treatment step (S60) proceeds to the anaerobic bioreaction step (S20) or the high temperature aerobic bioreaction step (S30) several times, the sludge treatment method characterized in that for recycling. The method of claim 1, Between the anaerobic bioreaction step (S20) and the high temperature aerobic bioreaction step (S30), the filtration step (S21) for filtering the sludge discharged after the progress of the anaerobic bioreaction step (S20), and from the filtration step (S21) Sludge treatment method further comprises a concentration step (S23) to concentrate the sludge to be filtered. The method according to claim 1 or 2, The anaerobic bioreaction step (S20) receives the heat generated from the high temperature aerobic bioreaction step (S30) sludge treatment method characterized in that to maintain the reaction temperature. The method according to claim 1 or 2, Sludge treatment method characterized in that the methane gas produced in the anaerobic bioreaction step (S20) is recycled as energy in a process other than sludge treatment. The method of claim 3, wherein Sludge treatment method characterized in that the methane gas produced in the anaerobic bioreaction step (S20) is recycled as energy in a process other than sludge treatment.

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