KR20100124418A - Method and equipment for treating sludge to reduce chemical - Google Patents

Abstract

PURPOSE: A method and a facility for treating sludge to reduce chemical are provided to increase condensation efficiency by mixing combustion gases, thereby reducing the amount of injecting coagulant. CONSTITUTION: A sludge treating facility includes an extinguishing tank(70), a boiler(78), a mixing tank, a combustion gas inflow line, and a sludge flocculator. The boiler heats the extinguishing tank. The mixing tank mixes a combustion gas generated in the boiler with sludge. The combustion gas inflow line provides the combustion gas to the mixing tank. The sludge flocculator mixes coagulant with the sludge.

Description

Sludge treatment method and treatment equipment for chemical reduction {METHOD AND EQUIPMENT FOR TREATING SLUDGE TO REDUCE CHEMICAL}

The present invention relates to a sludge treatment method and a treatment facility, and more particularly, in the flocculation and treatment of sludge generated in a treatment plant such as sewage / wastewater using a chemical (coagulant), the combustion gas generated in the sludge treatment facility. It is related to the sludge treatment method and treatment equipment that can reduce the chemical injection rate (drug usage) by reducing the inflow / mixing of the sludge to reduce the cost of the sludge treatment and reduce air pollution.

Sewage / wastewater treatment plants are used to purify sewage / wastewater generated from homes, industrial sites, and livestock farming sites. In this sewage / wastewater treatment plant, a sludge treatment facility for coagulating and treating sludge is constructed. Sludge is generally treated through physical methods such as precipitation, flocculation and dehydration, and biological methods using microorganisms.

For example, sewage / wastewater (inflow water) generated from households goes through sedimentation basins, initial sedimentation basins (primary sedimentation basins), aeration basins, and final sedimentation basins (secondary sedimentation basins). Fresh sludge discharged from the initial settler and surplus sludge discharged from the final settler are concentrated through a concentration process and then digested in a digester. The digested sludge is also stored in the digested sludge concentration tank, then mixed with the medicine (coagulant) in a dehydrator, coagulated, dehydrated and then caked. In addition, the dehydrated cake is marine dumping, landfilling, drying, incineration, or part of it may be recycled as rust soil or cement raw materials.

Sludge treatment costs make up a large portion of sewage / wastewater treatment costs. For example, in the case of sewage / wastewater treatment plants for treating sewage / wastewater sludge generated at home, approximately 13% of the total operating costs are spent on sludge treatment. Also, among the sludge treatment costs, the cost of medicine purchase and the cost of waste disposal of cakes (dewatered sludge) take up most of the cost. Particularly, among the chemicals used for sewage / wastewater treatment, flocculants (polymer coagulants) for flocculating sludge have a high unit cost and a large amount of use, which accounts for most of the cost of chemicals for sewage / wastewater treatment plants. Therefore, in order to reduce the sludge treatment costs, the amount of chemicals (particularly flocculants) must be reduced.

However, according to the prior art, there is a problem in that the amount of chemicals (coagulant) is used a lot and the cost of sludge treatment is high. As a method of lowering the injection rate (usage) of the flocculant, a method of increasing the TS (solid content) in the sludge may be considered. Conventionally, many concentrators are provided in order to keep TS high. However, this adds to the cost of installing a thickener. In addition, when the content of VS (volatile solids) of the sludge is lowered, the injection rate (usage) of the flocculant can be lowered. However, there is a real difficulty in keeping VS low.

Meanwhile, in the digester, a digestion gas containing a component such as methane is generated, and the digestion gas is used as a heat source of a boiler for heating the digester. In addition, the extinguishing gas may be used as an energy source of a generator (combustion of gas-> rotational force-> electric power) installed in the sludge treatment facility. At this time, the combustion gas (exhaust gas) is generated in the boiler and the generator. The generated combustion gases are generally released into the atmosphere after some of the pollutants have been removed through air pollution prevention facilities (cleaning dust collectors). In addition, it is pointed out that the cost of the sludge treatment due to the installation cost of the conventional air pollution prevention facility (cleaning dust collecting device) is generated. Therefore, there is a need for improved process for utilization of the combustion gas and prevention of air pollution.

The present invention is to solve the problems of the prior art as described above, in the flocculation and treatment of the sludge with a chemical (coagulant), by introducing the combustion gas generated in the sludge treatment equipment into the sludge, the chemical injection rate It is an object of the present invention to provide a sludge treatment method and a treatment facility capable of reducing the amount of chemicals used, thereby reducing the cost of sludge treatment and reducing the emission of combustion gas to the air.

The present invention to achieve the above object,

Mixing the combustion gas generated in the sludge treatment facility with the sludge; And

It provides a sludge treatment method for reducing the chemical, comprising the step of mixing the sludge mixed with the combustion gas with a flocculant.

In addition, the present invention,

Digester;

A boiler for warming the digester;

A mixing tank for mixing the combustion gas generated in the boiler with sludge;

Combustion gas inlet line for introducing the combustion gas into the mixing tank; And

It provides a sludge treatment equipment for reducing the chemicals, including a sludge flocculator for mixing the flocculant and the sludge introduced from the mixing tank.

In addition, the present invention,

Digester;

A boiler for warming the digester;

A generator for generating electric power by using the digestion gas generated in the digester;

A mixing tank for mixing the combustion gas generated in at least one selected from the boiler and the generator with the sludge;

Combustion gas inlet line for introducing the combustion gas into the mixing tank; And

It provides a sludge treatment facility for reducing the chemicals, including a sludge flocculator for mixing the flocculant and the sludge introduced from the mixing tank.

At this time, the combustion gas is preferably introduced into the lower portion of the mixing tank.

According to the present invention, the flocculation efficiency is improved by mixing the combustion gas, which has the effect of reducing the injection amount of the chemical (coagulant). Accordingly, the amount of chemicals (coagulant) is reduced, thereby reducing the cost of sludge treatment.

In addition, according to the present invention, since the combustion gas generated in the sludge treatment facility is not discharged into the atmosphere, the sludge is introduced into the sludge and is treated, thereby reducing the air pollution.

The present inventors conducted a study for reducing the flocculant which is a dehydration medicine, and the research for reducing the sludge processing cost. In the course of this study, the combustion gas generated in the boiler was introduced into the sludge and mixed, and then mixed with the flocculant and treated to reduce the injection amount (usage) of the flocculant. In addition, it can be seen that the combustion gas is treated with a cake and treated with sludge to reduce the air pollution caused by the combustion gas emissions.

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

1 shows a schematic diagram of a sludge treatment plant according to an exemplary embodiment of the present invention. The sludge treatment facility shown in Figure 1 is provided only to explain the present invention in more detail, whereby the technical scope of the present invention is not limited.

Sludge treatment method according to the invention, the step of mixing the sludge and the combustion gas; And mixing the sludge mixed with the combustion gas with a flocculant.

The sludge and the combustion gas may be mixed through the mixing tank 100. The sludge and the combustion gas may be mixed in the sludge flow lines L1, L2 and L3. For example, the sludge and the combustion gas are flow lines installed between the digestion tank 70 and the digestion sludge distribution tank 71, and the flow between the digestion sludge distribution tank 71 and the digestion sludge concentration tank 72. It may be mixed in the line (L2) or the flow line (L3) installed between the digestion sludge concentration tank 72 and the dehydrator (80). Preferably, the sludge and the combustion gas are mixed through the mixing tank 100, but the combustion gas is introduced into the lower portion of the mixing tank 100 and mixed.

The mixing tank 100 is included here as long as it can mix sludge and combustion gas, and the mixing tank 100 may be provided with an agitator therein. In addition, the mixing tank 100 may be selected from the sludge receiving tank installed in the existing facility. In this case, the sludge containing tank includes any sludge contained therein, and may be selected from, for example, a digested sludge distribution tank 71 and a digested sludge concentration tank 72.

At this time, the combustion gas is generated in the sludge treatment facility, for example, one generated in at least one selected from the boiler 78 and the generator 77 installed in the sludge treatment facility. The combustion gas is introduced into the mixing tank 100 or the sludge flow line (L1) (L2) (L3) in which the sludge is accommodated through the inlet line (L4) and mixed with the sludge. The combustion gas is preferably introduced into the mixing tank 100, it is preferably introduced into the lower portion of the mixing tank 100. As such, when the combustion gas is introduced into the lower portion of the mixing tank 100, the contact efficiency with the sludge is improved because the combustion gas is up from the bottom up.

The treatment method according to the present invention can be implemented through the sludge treatment facility of the present invention described below. Hereinafter, a sludge treatment facility according to the present invention will be described with reference to FIG. 1.

The sludge treatment facility shown in FIG. 1 exemplarily shows that it can be applied to, for example, a sewage treatment plant.

Referring to Figure 1, the treatment plant according to the present invention is a digestion tank 70 for extinguishing the introduced sludge; A boiler (78) for heating the digester; A mixing tank 100 for mixing the combustion gas and sludge; Combustion gas inlet line (L4) for introducing the combustion gas into the mixing tank (100); And a sludge flocculator 200 for mixing the flocculant and the sludge introduced from the mixing tank 100.

At this time, the treatment facility according to the present invention may further include a generator (77). The generator 77 generates power using the digestion gas generated in the digestion tank 70 as usual (combustion of the digestion gas-> rotational force-> power), and in the treatment facility according to the present invention 1 Can be installed two or more.

As shown in FIG. 1, the sludge treatment facility includes, for example, a sedimentation basin 10 into which raw water, such as sewage / wastewater, flows when sewage / wastewater generated in a home or an industrial site is treated. An initial settler cell (20, primary sedimentation basin) into which the treated water (supernatant) introduced from the settling basin 10 is introduced; Aeration tank 30 into which the treated water (supernatant) processed by the initial settler 20 is introduced; And a final settling basin 40 into which the sludge mass (aeration tank mixed solution) treated in the aeration tank 30 is introduced.

At this time, the landslide 10 removes contaminants such as soil, sand, wood chips, vinyl, etc., from the introduced raw water, and can prevent mechanical damage and the like of each device used in subsequent processes by the landslide 10. have. The first settler 20 is a place for removing some of the contaminants (including BOD, SS, etc.) contained in the inlet water of the first settler 20 by retaining and settling the treated water from which the contaminants have been removed through the settling paper 10. By the first sedimentation treatment process through the first settler 20, contaminants having high specific gravity (fresh sludge) are precipitated and transferred to the sludge treatment process, and the lighter contaminants are introduced into the aeration tank 30. do.

The aeration tank 30 feeds organic matter (BOD) in the sewage / wastewater (treated water) by oxidative assimilation (activation) of microorganisms and forms a sludge mass (aeration tank mixed liquor) in which particulate matter (SS) is used as a nucleus. The biological reaction proceeds, in which the aeration tank 30 is supplied with air (or oxygen) for the activation of microorganisms through the blower 35. In the final settler 40, the sludge mass (aeration tank mixed liquor) formed in the aeration tank 30 is introduced and subjected to secondary precipitation through gravity settling. At this time, some of the sludge precipitated in the final settler 40 is referred to as excess sludge is transferred to the sludge treatment process, and some are conveyed to the front end of the aeration tank 30, referred to as conveying sludge, microorganisms in the aeration tank 30 To supplement. The clean supernatant (final discharged water) of the final settler 40 is disinfected through the disinfection facility 50 and then discharged.

In addition, the raw sludge discharged from the first settler 20 and the surplus sludge settled out of the final settler 40 are transferred to the concentration facility 60 and subjected to the concentration process, and then supplied to the digester 70 to extinguish (消 火) Can be. The digested sludge may be caked through coagulation and dehydration after undergoing storage and concentration through the digested sludge thickening tank 72. In addition, the dewatering cake may be landfilled, dried, incinerated or recycled to rust soil, cement raw materials, and the like. At this time, the digestion sludge distribution tank 71 may be further installed between the digestion tank 70 and the digestion sludge concentration tank 72 as necessary. The digested sludge distribution tank 71 is installed when two or more digested sludge thickening tanks 72 are disposed. An agitator may be provided inside the fire extinguishing sludge distribution tank 71.

Digestion gas, such as methane gas is generated in the digester 70, the digested gas is desulfurized through the desulfurization tower 75, and then stored in the gas storage tank 76, the generator 77 or the boiler 78 Can be recycled as an energy source. In addition, the power generated by the generator 77 may be supplied to the power of the blower 35, the heat generated in the boiler 78 is used as a heat source for heating the sludge of the digester (70). .

At this time, in the boiler 78 and the generator 77, combustion gas is generated by combustion, and the combustion gas is mixed in the mixing tank 100. Combustion gas generated from the boiler 78 and the generator 77 is introduced into the mixing tank 100 through the inlet line (L4). The combustion gas inlet line (L4) is preferably connected to the lower portion of the mixing tank 100 so that the combustion gas flows into the lower portion of the mixing tank (100). When the combustion gas is introduced into the lower portion of the mixing tank 100, as described above, the combustion gas is increased from the bottom up to improve the contact efficiency with the sludge. At this time, the combustion gas flowing into the mixing tank 100 is at least one selected from the boiler 78 and the generator 77. Specifically, the combustion gas flowing into the mixing tank 100 may be a combustion gas generated in the boiler 78 or a combustion gas generated in the generator 77, or both may be used.

As described above, the mixing tank 100 is included here as long as it can mix the sludge and the combustion gas. And the mixing tank 100 may be provided with a stirrer inside. The mixing tank 100 may be selected from the sludge receiving tank installed in the existing facility. The mixing tank 100 may be one or more selected from the digestion sludge distribution tank 71 and the digestion sludge concentration tank 72 as shown in FIG. 1.

In addition, in the present invention, the sludge aggregator 200 includes the coagulant and the sludge (sludge mixed with the combustion gas) introduced from the mixing tank 100 so as to coagulate the sludge. At this time, the flocculant may be supplied to the mixing tank 100 from the chemical storage tank (not shown) installed in the treatment facility. The agglomerator 200 includes a batch type in which a stirrer is mounted on a cylindrical body, or a continuous type in which a screw is built in the tubular body, but is not limited thereto. . In addition, in the present invention, the agglomerator 200 may be capable of advancing coagulation and dehydration at the same time. For example, the agglomerator 200 may be a dehydrator 80 as shown in FIG. 1. At this time, the dehydrator 80 is a sludge (sludge mixed with combustion gas) and a flocculant to be mixed and then dehydrated (concentrated) to produce a cake, for example, a centrifugal dehydrator, a belt dehydrator that is commonly used , Centrifugal thickeners, mechanical thickeners and the like.

In addition, the flocculant in the present invention can be used as long as the flocculant can aggregate the sludge, and includes a powder, an emulsion phase (including more than 20% by weight of the flocculant active ingredient) and a liquid phase (including at least 2% by weight of the flocculant active ingredient). . The flocculant may be an inorganic flocculant, a polymer flocculant or a mixture thereof. Although not particularly limited, the inorganic flocculant includes, for example, ferrous chloride, ferric chloride, aluminum sulfate (aluminum sulfate), modified basic aluminum sulfate (PACS), polyaluminum chloride (PAC), and polyaluminum silicate sulfate (PASS). ), And one or more selected from the group consisting of soda aluminate and the like, and the polymer flocculant may use one or more selected from the group consisting of cationic, anionic, nonionic, and amphoteric polymers. In this case, the cationic polymer flocculant includes (co) polymer of acryloyloxyethyltrimethylammonium chloride, (co) polymer of methacryloyloxyethyltrimethylammonium chloride, and (meth) acryloyloxyethylbenzyldi Acrylics such as (co) polymers of methylammonium chloride; Amidine-based compounds such as polyamidine; And amines such as polyvinylamine, and the like. Anionic polymer flocculants include copolymers of acrylamide and acrylic acid (or salts thereof), copolymers of acrylamide and acrylamide-2-methylpropanesulfonic acid, And acryl-amides such as copolymers of acrylamide, acrylic acid salts, and acrylamide-2-methylpropanesulfonic acid. Examples of the nonionic polymer coagulant include polymers of acrylamide, and the amphoteric polymer coagulant includes (meth) acryloyloxyethyltrimethylammonium chloride-acrylamide-acrylic acid terpolymer. Can be. In the present invention, the flocculant is not limited to those listed above, and may be used as a sale product commonly used in the art.

According to the present invention described above, the flocculation efficiency is improved by mixing the combustion gas, and the amount of injected chemical (coagulant) is reduced. It is determined that the combustion gas acts as an oxidant of the sludge to increase the coagulation reactivity. Accordingly, according to the present invention can reduce the amount of flocculant which occupies most of the drug cost, thereby reducing the cost for sludge treatment.

In addition, according to the present invention, the air pollution can be reduced due to the inflow treatment into the sludge without discharging the combustion gas generated in the sludge treatment facility to the atmosphere. Specifically, since the combustion gas is included in the cake and treated with the sludge, it is possible to reduce the air pollution by the discharge of the combustion gas.

1 shows a schematic diagram of a sludge treatment plant according to an exemplary embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

10: sedimentation area 20: the first settling basin

30: aeration tank 35: blower

40: final settlement 50: disinfection equipment

60: concentration facility 70: digester

71: digestion sludge distribution tank 72: digestion sludge thickening tank

75: desulfurization tower 76: gas storage tank

77: generator 78: boiler

80: dehydrator 100: mixing tank

200: agglomerator L4: combustion gas inlet line

Claims (6)

Mixing the combustion gas generated in the sludge treatment facility with the sludge; And And a sludge mixed with the combustion gas and a flocculant. The method of claim 1, Sludge treatment method for reducing the chemicals, characterized in that for mixing the combustion gas flows into the lower portion of the mixing tank. The method according to claim 1 or 2, The combustion gas is sludge treatment method for reducing chemicals, characterized in that generated in at least one selected from a boiler and a generator installed in the sludge treatment facility. Digester; A boiler for warming the digester; A mixing tank for mixing the combustion gas generated in the boiler with sludge; Combustion gas inlet line for introducing the combustion gas into the mixing tank; And And a sludge agglomerator for mixing the flocculant and the sludge introduced from the mixing tank. Digester; A boiler for warming the digester; A generator for generating electric power by using the digestion gas generated in the digester; A mixing tank for mixing the combustion gas generated in at least one selected from the boiler and the generator with the sludge; Combustion gas inlet line for introducing the combustion gas into the mixing tank; And And a sludge agglomerator for mixing the flocculant and the sludge introduced from the mixing tank. The method according to claim 4 or 5, The combustion gas inlet line is a sludge treatment facility for reducing, characterized in that connected to the lower portion of the mixing tank.

Images