JP2023015390A - Digested sludge treatment method and its waste water treatment equipment - Google Patents

Abstract

A method for treating biomass digestate and a wastewater treatment apparatus therefor are provided.
[Solution] In a purification facility equipped with at least a mixing tank - a reaction tank - a sludge dehydrator - (neutralization tank) - a biological treatment tank, in the mixing tank, the biomass digestive liquid of the water to be treated is added to the Mp value (moisture content evaluation ) adds a dehydration aid having Mp (moisture content of cake) ≤ 55 to 55 to 70, then, in a reaction tank, a flocculant is added to the water to be treated, and the emulsified component in the biomass digestive fluid Flocs containing fine particle components; step of forming extra-large (φ10 mm or more) to large (φ5-10 mm), removing the flocs in a sludge dewatering machine, and at the same time removing the flocs, desorbed liquid and dehydrated cake; A biomass digestive liquid treatment method comprising a step of separating into a rate of 55% or less to 55 to 70%, and then a step of introducing the desorbed liquid into a biological treatment tank to perform biological treatment, and wastewater treatment thereof Device.
[Selection drawing] Fig. 1

Description

TECHNICAL FIELD The present invention relates to a method for treating biomass digestive fluid and a wastewater treatment apparatus therefor, and more particularly, to a method for treating so-called biomass digestive fluid, which is wastewater containing residues remaining after power generation at a biomass power generation facility, and the method for treating the biomass digestive fluid. The present invention relates to a biomass digestive fluid (hereinafter sometimes referred to as "wastewater") treatment apparatus for use in a treatment method. The present invention provides new technologies and new products related to the biomass digestive fluid treatment method and the wastewater treatment apparatus therefor.

Biomass power generation, which is subject to the renewable energy feed-in tariff system (purchase period: 20 years) that started in 2012, tends to increase further with the expansion of renewable energy. However, as with nuclear power generation, there is a problem that residues remain after power generation is finished, and wastewater containing such residues is called biomass digestate.

For the treatment of this biomass digestive fluid, there are examples of the development of technologies for concentration and distillation after making the filtrate, but there is no prior solid-liquid separation technology. It is used for reduction, grassland reduction, etc. Here, the reason why the solid-liquid separation technology of biomass digestive juice is impossible is that the digestive juice emulsifies to form a stable emulsion and aggregation is difficult, and solids are not decomposed. It is difficult to form flocs and dehydrate because the particles become finer and the molecules are associated to form micelles and are in a colloidal state.

Here, to summarize the technology for processing biomass digestive fluid, conventionally, for example, 1) To efficiently recycle food waste discharged from the food service industry and food manufacturing plants as feed and fuel 2) a recycling system that uses the digestive juice and gas from the food waste by methane fermentation (Patent Document 1); Anaerobic treatment method for complete decomposition (Patent Document 2), 3) Biomass fuel conversion system equipped with a methane fermentation tank for methane fermentation of solubilized biomass resources and control method thereof (Patent Document 3), 4) Biomass resources In order to efficiently utilize , a method of hydrothermally treating the residue and digestive juice produced by the methane fermentation treatment and recovering them (Patent Document 4), and the like have been proposed.

In addition, as other prior art, for example, 5) a method of introducing digestive juice containing residues generated by methane fermentation of organic waste and biomass resources into an incinerator or a melting furnace and processing equipment therefor (Patent document 5), 6) Grass-based biomass digestive juice and grass-based biomass digestion method (Patent Document 6), 7) Digestive fluid treatment system that separates and recovers solid components in a reusable form from digestive fluid generated in biomass plants (Patent Document 7), etc. have been proposed.

In general, 8) separation of water-soluble proteins is performed by treating with iron salts or aluminum salts that have the effect of aggregating by neutralization of charge. In order to facilitate the separation, a synthetic polymer flocculant is used, and a method using a pressurized flotation separation method (Non-Patent Document 1) has been proposed to solidly separate the flocs thus aggregated. .

In general, in the case of treating floss of fishery processing wastewater whose composition fluctuates greatly, for example, as in conventional facilities that collect and jointly treat fishery processing wastewater, it is not possible to dehydrate aggregated flocs using a screw press. Almost impossible. Therefore, at present, a method of dehydrating water by evaporating it with a boiler is adopted, but there are problems such as high cost, large amount of CO ₂ emission, and very large environmental load. Therefore, in this technical field, there has been a strong demand as an urgent issue to establish a new dehydration system of low environmental load to replace the dehydration system using the current boiler evaporation process.

As for the purification treatment of biomass power generation digestive juice, at present, for example, standard activated sludge purification treatment is becoming mainstream as a method for purifying the biomass digestive juice to a dischargeable level. However, in order to install a purification facility using the activated sludge method, it is necessary to install a large-scale purification facility equipped with, for example, a regulating pond, a biological treatment tank (aeration tank), a sedimentation tank, and these operating facilities. In terms of expenses and running costs, it is inefficient and uneconomical as equipment installed individually by small and medium-sized business operators. Therefore, in this technical field, there is a strong demand for development of a new purification technology and purification facility that is smaller in scale, more efficient and can be put into practical use.

JP-A-2003-88838 Japanese Patent Application Laid-Open No. 2005-6649 JP 2007-313427 A Japanese Unexamined Patent Application Publication No. 2008-43902 JP 2008-221105 A JP 2012-16652 A JP 2016-10742 A

Editing Committee of Waste Disposal/Recycling Technology Handbook, "Waste Disposal/Recycling Technology Handbook", Published by Construction Industry Research Institute, November 25, 1993, p. 407 left column line 9-32

So far, the present inventors have made various studies on the purification treatment of biomass power generation digestive juice (hereinafter sometimes referred to as "biomass digestive juice"). is emulsified and forms a stable emulsion state, solid-liquid separation is impossible, and its removal/dehydration is extremely difficult. It was found that in many cases, the water is flowing into the aeration tank).

That is, in the conventionally known existing technology, even if normal dehydration aids, coagulants, etc. are added to the contaminated waste liquid containing the digestive juice to generate (form) flocs, the moisture content of the residue cake is It is technically very difficult to reduce the content to about 70% or less, and the actual situation is that it is extremely difficult to solve it.

Under these circumstances, the present inventors found that the Mp value (moisture percentage value) is used to remove the emulsified component and fine particle component of the biomass digestive fluid before flowing into the biological treatment tank (aeration tank). Evaluation) uses a specific dewatering aid having Mp (cake moisture content) ≤ 70 and a flocculant compatible with the dewatering aid, and at least a mixing tank - reaction tank - sludge dehydrator - (neutralization tank) - In a purification facility equipped with a biological treatment tank (aeration tank), the step of adding the above-mentioned specific dehydration aid to the water to be treated in the mixing tank, and then adding the coagulant to the water to be treated in the reaction tank Then, a step of forming extra-large (φ10 mm or more) to large (φ5-10 mm) flocks, and a sludge dehydrator to remove the flocs, a highly transparent desorbed liquid, and a dehydrated cake; water content 70 % or less, and then introducing the desorbed liquid into a biological treatment tank (aeration tank) to perform biological treatment, thereby reducing the BOD volume load and the amount of sludge generated. Stable water treatment effect can be achieved by suppressing the amount of oxygen and reducing the amount of oxygen required, and biological treatment in a biological treatment tank (aeration tank) can be efficiently performed, and the present invention has been completed.

In the present invention, the Mp value (moisture percentage value; moisture content evaluation) is "a specific dehydration aid having Mp (cake moisture content) ≤ 70" means that the biomass digestive fluid of the water to be treated is added to the dehydration aid and a flocculating agent to form extra-large (φ 10 mm or more) to large (φ 5-10 mm) flocs, a desorption liquid from which the flocs are removed, and a dehydrated cake; moisture content of 70% or less. It is defined as a dehydration aid having the performance expected (expected) to be able to separate, ie, the performance capable of dehydrating the cake to a moisture content of 55% or less to 55 to 70%.

In the present invention, in order to conduct a dehydration test, in a purification facility equipped with at least a mixing tank - a reaction tank - a sludge dehydrator - (neutralization tank) - a biological treatment tank (aeration tank), in the mixing tank and the reaction tank, Various dehydration aids and flocculants were added to the water to be treated and tested. The transparency of (supernatant water) is "turbidity → transparent", and the size of flocks formed in the reaction tank is E → A, that is, E: cannot flocculate, D: small (φ 3 mm below), C: medium (φ3-5mm), B: large (φ5-10mm), A: extra-large (φ10mm or more), and the expected (expected) cake moisture content generated from the sludge dewatering machine is E → A, that is, E: 90% or more, D: 80 to 90%, C: 70 to 80%, B: 55 to 70%, A: 55% or less.

In the present invention, the evaluation of the expected (expected) cake moisture content of the dehydrated cake is the numerical value of E to A in the “evaluation” section of Table 5 (see paragraph 0067) below, which is the “Mp value (Moisture percentage value; moisture content evaluation)”. Then, in the present invention, regarding the performance of the dehydration aid, for example, in the evaluation of the cake moisture content of the dehydrated cake, if the expected (expected) cake moisture content is, for example, 55% or less, this is referred to as "Mp (Moisture content of cake) ≤ 55”, and when it is 55 to 70%, it is expressed as having performance of “Mp (moisture content of cake) = 55 to 70”.

The present invention uses the above-mentioned specific dehydration aid and a flocculant compatible with the dehydration aid together to form flocs of biomass digestive juice; By removing/dehydrating, the desorbed liquid from which flocs have been removed and the dehydrated cake are separated into a moisture content of 70% or less, more specifically, a moisture content of 55% or less to 55 to 70%, thereby reducing the BOD volume load. , A stable water treatment effect can be expected by suppressing the amount of sludge generated and reducing the amount of oxygen required, and a biomass digestive liquid treatment method characterized by making it possible to perform biological treatment in a biological treatment tank (aeration tank) It is intended to provide

In addition, in the present invention, by using the above-mentioned specific dehydration aid together with a flocculant suitable for the dehydration aid, flocs; It is possible to reduce the water content of the dehydrated cake to 70% or less, more specifically, to 55% or less to 55 to 70%, thereby making it possible to use it in a biological treatment tank (aeration tank). It is an object of the present invention to provide a biomass digestive fluid treatment method and a wastewater treatment apparatus for the biomass digestive fluid, which are characterized by enabling biological treatment.

The present invention for solving the above problems consists of the following technical means.
(1) A method for processing biomass digestive juice,
A dehydration aid having an Mp value (Moisture percentage value; moisture content evaluation) of Mp (cake moisture content) ≤ 55 to Mp (cake moisture content) = 55 to 70 in the biomass digestive fluid of the water to be treated, and flock a step of adding a flocculating agent capable of forming fluff-like precipitate) to form extra-large (φ10 mm or more) to large (φ5-10 mm) flocs; A biomass digestive liquid characterized by comprising a step of separating into a rate of 55% or less to 55 to 70%, and then a step of introducing the desorbed liquid into a biological treatment tank (aeration tank) to perform biological treatment. How to handle.
(2) In a purification facility equipped with at least a mixing tank - a reaction tank - a sludge dehydrator - (neutralization tank) - a biological treatment tank, in the mixing tank, the above-mentioned specific dehydration aid is added to the biomass digestive liquid of the water to be treated. A step of adding, then, in a reaction tank, a flocculating agent having flocculation ability is added to the water to be treated to form flocs in which the emulsified component and the fine particle component in the biomass digestive fluid are clathrated; (φ5 to 10 mm), a step of removing the flocs with a sludge dehydrator and separating into a desorbed liquid from which the flocs have been removed and a dehydrated cake; moisture content of 55% or less to 55 to 70%; The treatment method according to (1) above, further comprising the step of introducing the desorbed liquid into a biological treatment tank (aeration tank) to perform biological treatment.
(3) Add a dehydration aid having an Mp value (moisture content evaluation) of Mp (cake moisture content) = 55 to 70 and a flocculating agent having floc forming ability to form large flocs (φ5 to 10 mm). A step of forming, a step of separating into a desorbed liquid from which flocs are removed and a dehydrated cake; moisture content of 55 to 70%, and then introducing the desorbed liquid into a biological treatment tank (aeration tank) for biological treatment. The processing method according to (1) or (2) above, comprising the step of executing.
(4) Any one of (1) to (3) above, wherein before the water to be treated flows into the biological treatment tank, an operation is performed to remove flocs that clathrate the emulsified component and the fine particle component in the biomass digestive fluid. The treatment method described in .
(5) Any one of (1) to (3) above, wherein the disinfectant is neutralized in a neutralization tank, if necessary, before the water to be treated flows into the biological treatment tank (aeration tank). The treatment method described in .
(6) Any one of (1) to (3) above, wherein 0.1% or less of the dehydration aid is added to the biomass digestate of the water to be treated in the mixing tank (relative to the volume of the wastewater). Described processing method.
(7) Any one of (1) to (3) above, wherein 1% or less of a flocculant (0.2% aqueous solution) is added to the biomass digestion liquid of the water to be treated in the reaction tank. Processing method.
(8) A wastewater treatment apparatus for use in the biomass digestive fluid treatment method according to any one of (1) to (7) above,
At least a mixing tank - a reaction tank - a sludge dehydrator - (neutralization tank) - including a purification facility equipped with a biological treatment tank as a component,
1) Add a dehydration aid having an Mp value (moisture content evaluation) of Mp (moisture content of cake) ≤ 55 to Mp (moisture content of cake) = 55 to 70 to the biomass digested liquid of the water to be treated in the mixing tank. process,
2) In the reaction tank, a flocculation agent having flocculation ability is added to the water to be treated to clathrate the emulsified component and the fine particle component in the biomass digestive liquid; forming process,
3) A step of separating the desorbed liquid from which the floc has been removed and a dehydrated cake;
and the desorbed liquid is introduced into a biological treatment tank (aeration tank) for biological treatment.
(9) 1) A step of adding a dehydration aid having an Mp value (moisture content evaluation) of Mp (cake moisture content) = 55 to 70 to the biomass digested liquid of the water to be treated in the mixing tank,
2) A step of adding a flocculating agent to the water to be treated in the reaction tank to form large flocs (φ5 to 10 mm) in which the emulsified component and the fine particle component in the biomass digestive liquid are clathrated,
3) A step of separating into a desorbed liquid from which the flocs have been removed and a dehydrated cake with a water content of 55 to 70%,
The wastewater treatment apparatus according to (8) above, wherein the desorbed liquid is put into a biological treatment tank (aeration tank) to perform biological treatment by executing the above.

Next, the present invention will be described in more detail.
The biomass digestive fluid, which is an object to be treated in the present invention, means the wastewater generated from the biomass power generation facility containing residues remaining after power generation is completed. Regarding this biomass digestive fluid, in this technical field, there are cases where the biomass digestive fluid is flowed into the biological treatment tank (aeration tank) without being treated, so biological treatment (purification treatment) in the biological treatment tank (aeration tank) ) did not work well.

In addition, in the purification of biomass digestive juice, since the digestive juice is emulsified and forms a stable emulsion state, it is difficult to aggregate. By forming a colloidal state, the known existing technology can form flocs with a size of extra large (φ 10 mm or more) to large (φ 5 to 10 mm), especially in the reaction process of the reaction tank. In addition, it is quite difficult to separate the desorbed liquid and the dehydrated cake in the floc removal/dehydration process using a sludge dehydrator, and desorption is performed by removing extra large (φ10 mm or more) to large (φ5 to 10 mm) flocs. It is extremely difficult to separate the liquid and the dehydrated cake; the water content is 70% or less, that is, the water content is 55% or less to 55 to 70%. was strongly urged to do so.

The inventors of the present invention have been researching and developing various methods for treating fishery processing wastewater and parlor wastewater floss. Focusing on emulsified components and fine particle components, in order to remove them before flowing into a biological treatment tank (aeration tank), a specific dehydration aid and a flocculant compatible with the dehydration aid are used in combination. , Oversized (φ10 mm or more) to large (φ5 to 10 mm) flocs are formed in a reaction tank, and then flocs are removed/dewatered in a sludge dehydrator, and the flocs are oversized (φ10 mm or more). ) to large (φ5 to 10 mm) removed and highly transparent desorbed liquid and dehydrated cake; moisture content of 70% or less. The inventors have found new knowledge that highly efficient and highly accurate biological treatment can be performed by flowing into an aeration tank and performing biological treatment.

Biomass digestive fluid is in a colloidal state in which molecules such as emulsified components and fine particle components are associated in the digestive fluid (wastewater) to form micelles, and emulsified and fine particle components are dispersed. It is a waste liquid that is intricately and complexly contaminated with sludge containing Therefore, even if floc removal/dehydration is performed with a sludge dehydrator, it is extremely difficult to make a dehydrated cake with a moisture content of 70% or less, especially 55% or less. It has been considered extremely difficult to purify the biomass digestate efficiently with simple equipment at low cost unless purification treatment is carried out by equipment.

Therefore, in the present invention, in order to treat biomass digestive juice containing wastewater that is intricately and compositely contaminated with washing wastewater and sludge containing fine particle components, etc., we focus on emulsified components and fine particle components in the digestive juice, In order to remove these before flowing into the biological treatment tank (aeration tank), a specific dehydration aid and a flocculant compatible with the dehydration aid are used in combination to form flocs and remove/dehydrate to An attempt was made to purify the water to be treated.

That is, the present invention provides a purification facility comprising at least a mixing tank, a reaction tank, a sludge dehydrator, a neutralization tank, and a biological treatment tank. Mp (moisture content of cake) ≤ 70, more specifically, Mp (moisture content of cake) ≤ 55 to Mp (moisture content of cake) = 55 to 70. To the above, a flocculant suitable for the dehydration aid, such as a polymer flocculant, is added to form emulsified components in the biomass digestive fluid and fine particle components. 10 mm), and a sludge dehydrator to separate the desorbed liquid from which the flocs have been removed and the dehydrated cake; , the desorbed liquid is put into the biological treatment tank and the biological treatment is performed, whereby the biological treatment (purification treatment) is efficiently performed by the biological treatment tank (aeration tank).

In the present invention, the relationship between the formation of flocs in the reactor, the removal of flocs in the dehydration step, and the moisture content of the cake is extremely important. As a result of the dehydration test, as shown in Table 5 (see paragraph 0067) below, flocs were not formed when the moisture content of the cake was 90% or more, and the size of the flocs was small when the moisture content of the cake was 80 to 90%. (φ3 mm or less), the size of the floc is medium (φ3-5 mm) when the moisture content of the cake is 70 to 80%, and the size of the floc is large (φ5 to 10 mm), and when the moisture content of the cake is 55% or less, the size of the floc is extra large (φ10 mm or more). Then, in this order, for example, the transparency of the supernatant water becomes turbid → transparent, and the evaluation is found to be a rank of E → A, and these test results are the dehydration aid added in the mixing tank and the selection of the type of flocculant added in the reaction tank, especially the selection of the type of dehydration aid added in the former mixing tank.

As a result of accumulating excessive tests or more tests that far exceed normal routine considerations, the present inventors have found that at least the mixing tank - reaction tank - sludge dehydrator - (neutralization tank) - biological treatment tank (aeration tank), in the mixing tank, the water to be treated has an Mp value (moisture content evaluation) of Mp (moisture content of cake) ≤ 70, more specifically, Mp (moisture content of cake) ≤ 55 to Mp ( Cake water content) = adding a dehydration aid having a moisture content of 55 to 70, then, in a reaction tank, adding a flocculant suitable for the dehydration aid, such as a polymer flocculant, to the water to be treated, By adopting the step of forming flocs that clathrate the emulsified component and the fine particle component in the biomass digestive fluid, the moisture content of the dehydrated cake is 70% or less, more specifically, the moisture content is 55% or less to 55 to 70%. , Size of flocs: extra large (φ10 mm or more) to large (φ5 to 10 mm), Supernatant water: high transparency. Then, the sludge dehydrator removes the flocs, and at the same time, the highly transparent desorbed liquid from which the flocs are removed is put into a biological treatment tank (aeration tank), and the biological treatment is successfully carried out efficiently.

Here, further, formation of flocs containing emulsified components and fine particle components in the biomass digestive fluid using a specific dehydration aid and a flocculant compatible with the dehydration aid, and its removal / dehydration Specifically, in the present invention, floc formation and its removal/dehydration are carried out in a purification facility comprising at least a mixing tank, a reaction tank, a sludge dehydrator, a neutralization tank, and a biological treatment tank (aeration tank). , In raw water (waste water before dehydration), in a mixing tank, the Mp value (moisture content evaluation) is Mp (moisture content of cake) ≤ 70, more specifically, Mp (moisture content of cake) ≤ 55 to Mp (moisture content of cake) = 55 to 70, for example, after stirring at 500 rpm for 2 minutes, in a reaction tank, adding a flocculant suitable for the dehydration aid, such as a polymer flocculant, For example, stirring is performed at 120 rpm for 3 minutes to form flocs that clathrate the emulsified component and the fine particle component in the biomass digestive fluid. Next, the flocs are put into a sludge dehydrator to remove/dehydrate the flocs containing emulsified components and fine particle components in the biomass digestive liquid to separate into desorbed liquid and dehydrated cake, and the moisture content of the dehydrated cake is reduced to 70. % or less, more specifically, after reducing the moisture content to 55% or less to 55 to 70%, the desorbed liquid is subjected to biological treatment in a biological treatment tank (aeration tank).

In the present invention, as the specific dehydration aid, for example, a dehydration aid mainly composed of a pulverized product with a particle size of 1 to 100 μm obtained by pulverizing vegetable fibers by mechanical shearing can be used. For example, a polymer flocculant (commercially available product) compatible with the dehydration aid can be used. Here, the main component is a pulverized material with a particle size of 1 to 100 μm obtained by pulverizing vegetable fibers by mechanical shearing. It means that Examples of the vegetable fiber that is the main component of the dehydration aid include, for example, wood powder of coniferous or broad-leaved trees, powder of bamboo, which is a monocotyledonous plant with a lignified culm, pulverized chips of thinned wood and wood chips, or Examples include saw dust and waste generated during sawing, grinding dust generated during sanding, cutting dust generated during sandblasting, paper pulp, waste paper pulp, and the like. However, it is not limited to these, and any raw material (raw material) containing vegetable fibers can be appropriately used regardless of the type thereof.

These vegetable fibers are desirably used with a purity of 90% or higher as cellulose fibers. About 40 or more types of dehydration aids, which are mainly composed of pulverized vegetable fibers with a particle size of 1 to 100 μm obtained by pulverizing vegetable fibers by mechanical shearing, are commercially available. (manufactured by Reserva Co., Ltd.) can be obtained as appropriate by specifying the product number.

In the present invention, the "vegetable fiber" which is the main component of the dehydration aid includes, for example, plant fibers such as pulverized rice husk, straw, pulverized corn cob, cellulose fiber, and fine wood flour. is pulverized by mechanical shearing, for example, by pulverizing or triturating with a grinder or the like, a pulverized product (sample) mainly composed of a pulverized product with a particle size of 1 to 100 μm is preferably used. can do. However, the dehydration aid that can be used in the present invention is not limited to these, and has an Mp value (moisture content evaluation) of Mp (cake moisture content) ≤ 55 to Mp (cake moisture content) = 55 to 70. Samples, that is, samples ranked A to B in the evaluation section of Table 5 below can be used in the same manner.

In the present invention, the specific dehydration aid such as the above pulverized rice husks is used at least in the state of a sample mainly composed of pulverized material with a particle size of 1 to 100 μm, at least a mixing tank-reaction tank-sludge dehydrator-(neutralization tank ) - Can be used by adding to the water to be treated in a mixing tank in a purification facility equipped with a biological treatment tank. In order to treat the biomass digestive fluid using the specific dehydration aid, in the mixing tank, the specific dehydration aid is added to the raw water (wastewater before treatment) at, for example, 0.1% (relative to the wastewater capacity). Then, in a reaction tank, a flocculant suitable for the dehydration aid, such as an organic polymer flocculant (eg, 0.2% by mass aqueous solution) is added. As the organic polymer flocculant, a nonionic, cationic or amphoteric synthetic polymer flocculant is used.

Examples of the nonionic synthetic polymer flocculant include polyacrylamide, polyethylene oxide, urea-formalin resin, etc. Examples of the cationic synthetic polymer flocculant include polyaminomethylacrylamide, polyvinylimidazoline, Examples include chitosan, ionene-based copolymers, and epoxyamine copolymers. Examples of amphoteric synthetic polymer flocculants include lecithin-based amphoteric surfactants and casein hydrolyzate-based amphoteric surfactants. These organic polymer flocculants are appropriately available, for example, as commercial products (manufactured by Asada Kagaku Kogyo Co., Ltd., Hymo Co., Ltd., etc.). Further, in the present invention, as a flocculant suitable for the dehydration aid, inorganic flocculants such as polyiron sulfate (III), polyiron chloride (III), polyaluminum chloride, polyaluminum sulfate, and ferric chloride , aluminum sulfate and the like can be used, and an appropriate flocculant can be used as long as it is compatible with the above-mentioned specific dehydration aid.

When carrying out the biomass digestive fluid purification treatment of the present invention, the order of adding the specific dehydration aid and the flocculant compatible with the dehydration aid, such as an organic polymer flocculant, is important. In a purification facility equipped with at least a mixing tank - a reaction tank - a sludge dehydrator - (neutralization tank) - a biological treatment tank (aeration tank), the specific dehydration aid is added in the preceding mixing tank, and then reacted. In a tank, a flocculant suitable for the dehydration aid, such as an organic polymer flocculant, is added and stirred to gradually generate (form) flocs. Execute the squeezing process with a machine. The time required for the generation (formation) of this floc is usually about 5 to 15 minutes.

After sufficiently forming flocs in this manner, the liquid is squeezed by, for example, a screw press, belt press or pressure filtration to separate the desorbed liquid and the dehydrated cake, and the dehydrated cake is taken out. In the present invention, focusing on emulsified components and fine particle components in biomass digestive fluid, in a purification facility equipped with at least a mixing tank - reaction tank - sludge dehydrator - (neutralization tank) - biological treatment tank, in the mixing tank, A dehydration aid having an Mp value (moisture content evaluation) of Mp (cake moisture content) ≤ 70 in the water to be treated, for example, a pulverized product with a particle size of 1 to 100 µm obtained by pulverizing vegetable fibers by mechanical shearing is the main component. A dehydration aid is added, and then in a reaction tank, a flocculant compatible with the dehydration aid, such as a polymer flocculant, is added to the water to be treated, and emulsified components and fine particles in the biomass digestive fluid A floc containing the component is formed.

Next, with a sludge dewatering machine, the flocs; extra large (φ10 mm or more) to large (φ5 to 10 mm) are removed, and at the same time, the desorbed liquid from which the flocs are removed and the dehydrated cake; water content is 70% or less. If necessary, neutralization of the disinfectant is also carried out at the same time in the neutralization tank. Next, the desorbed liquid is introduced into a biological treatment tank (aeration tank) to perform biological treatment. In the present invention, it is important to separate the formation of extra-large (φ10 mm or more) to large (φ5-10 mm) flocs, the desorbed liquid from which the flocs are removed, and the dehydrated cake, which has a moisture content of 70% or less. , it is possible to efficiently carry out biological treatment in a biological treatment tank (aeration tank) only when all of these conditions are satisfied.

In the present invention, as the flocculant, a specific commercial product (product number: RB-PT, PB-C1805, etc.) was selected from about 30 types of commercially available flocculants, as shown in the examples below. , In the present invention, the selection of the "dehydration aid" is the most important among the selection of the dehydration aid and the flocculant. ), A to E: the highest rank to the lowest rank, a suitable flocculant suitable for the specific dehydration aid may be selected and used.

In the present invention, if the above-mentioned flocs cannot be separated into extra-large (φ10 mm or more) to large (φ5-10 mm) formation, the desorbed liquid from which the flocs are removed, and the dehydrated cake; moisture content of 70% or less, biomass Even if the digestive fluid is biologically treated in a biological treatment tank (aeration tank), it is difficult to expect a stable water treatment effect by reducing the BOD volume burden, suppressing the amount of sludge generated, and reducing the amount of oxygen required. As a result, good results cannot be obtained in the evaluation of supernatant water and evaluation of flocs (size, hardness, grip feeling), and biological treatment in biological treatment tanks (aeration tanks) does not go well, preventing water pollution. It will not be possible to construct a biomass digestive liquid treatment method and wastewater treatment equipment that meet the general wastewater standards set by the law.

The present invention provides the following special effects.
(1) In the present invention, the biomass digestive fluid containing the residue remaining after power generation is completed in the biomass power generation facility is focused on, in particular, the emulsified component and the fine particle component, and these are made to flow into a biological treatment tank (aeration tank). In order to efficiently remove it before, a specific dehydration aid and a flocculant compatible with the dehydration aid are used in combination to form flocs that clathrate the emulsified component and the fine particle component in the biomass digestive fluid, and flocs Removal/dehydration and, if necessary, neutralization of the disinfectant in the neutralization tank at the same time made it possible to carry out biological treatment in a biological treatment tank (aeration tank).
(2) By using the above specific dehydration aid together with a coagulant compatible with the dehydration aid, biomass digestive fluid can be discharged in a manner that satisfies the general wastewater standards according to the Water Pollution Control Law.
(3) It is possible to reuse the dehydrated cake with a moisture content of 70% or less, more specifically, a moisture content of 55% or less to 55-70%, generated as a residue in a composting facility.
(4) It is possible to provide a method for efficiently biologically treating biomass digestive fluid and its wastewater treatment apparatus (facilities).
(5) According to the present invention, flocs; formation of extra large (φ10 mm or more) to large (φ5 to 10 mm) size, desorbed liquid obtained by removing the flocs, and dehydrated cake; expected (expected) cake moisture content 70% or less, more specifically, the water content can be separated from 55% or less to 55 to 70%, making it possible to remove BOD from raw water to 78% or less.
(6) A stable water treatment effect can be expected by reducing the BOD volume burden, suppressing the amount of sludge generated, and reducing the amount of oxygen required.

1 is a diagram schematically showing an example of a reservoir dehydration system; FIG. In the figure, the flock separator is optional. 1 is a diagram schematically showing an example of a reservoir dehydration system; FIG. 1 is a diagram showing a processing flow of a biomass digestive liquid (wastewater) treatment apparatus including a purification facility equipped with a mixing tank, a reaction tank, a sludge dehydrator, and a biological treatment tank. FIG.

Next, embodiments of the present invention will be specifically described based on examples. However, in the following examples, /D, /day, and /d each represent a value for "one day".

In this embodiment, the wastewater treatment equipment (equipment) used for treating the biomass power generation digestive fluid of the present invention, at least the raw water tank-mixing tank-reaction tank-regulation tank-sludge dehydrator-(neutralization tank)-biological treatment tank (Aeration tank)-membrane treatment tank-treatment tank-dilution tank-disinfection tank will be described in detail.
The actual capacity of one raw water tank was W8.0m x L8.0m x H2.2m = ^140.8m3 in order to have a capacity for one day or more of the planned treatment amount. In the above raw water tank, raw water auxiliary pump; 50A × 0.75 kw 200 V 1 unit, raw water pump; 80 A × 2.2 kw 200 V 1 unit, raw water tank stirring blower; 16 molds were installed.

The pretreatment reservoir dehydration equipment has a processing amount of 140.0 m ³ /D, a load amount of BOD of 420.0 kg/day, and a removal amount of BOD of 420.0 kg/D × 83.3% = 349.8 kg/d (remaining SS: 2100.0 kg/D x 98.0% = 2058.0 kg/d (remaining amount 42.0 kg/d).

Machinery and equipment used: Sewage weighing device: 1 FRP 90° triangular weir (measurement only), Mixing/reaction tank equipment: SUS W900mm×L1,800mm×H1,260mm, actual capacity 0.81m ³ /tank×2 1 tank, 2 stirrers of 200-300 rpm x 0.75 kw x 200 V (1 of which is inverter controlled), flock separator; Attached, screw press dehydrator (RSP-300Y type); wetted part made of SUS, fixed type automatic cleaning device attached 2 units of 1.5kw x 200V (inverter control), dehydrated cake transfer conveyor; made of SUS U200 type x 5m x Two units of 0.75kw x 200V were installed.

The amount of dehydrated cake generated was (140.0 m ³ /d × 2.1%) ÷ (1 - 0.7) = 9.8 t/D assuming a raw water concentration of 2.1% and a moisture content of the dehydrated cake of 70%. rice field. The amount of flocculation aid (Reservar MT-2000) used was 140.0 m ³ /D×0.1%=140.0 kg/D as 0.1% added to the liquid. The amount of polymer flocculant used is 140.0 m ³ /D × 10.5% × 0.5% = 73.5 kg/D, assuming that flocculant 1 is added at a concentration of 0.5% and 10.5% to the liquid. , 73.5 kg/0.5% = 14.7 m ³ /D. 140.0 m ³ /D × 21% × 0.2% = 58.8 kg / D, 58.8 kg of 0.2% solution concentration ÷ 0.2% = 29.4 m ³ /D.

The adjustment tank had an actual capacity of W2.4 m×L5.0 m×H4.0 m=48.0 m ³ in order to transfer the wastewater that flows in in 22 hours in 24 hours. In the adjustment tank, one adjustment pump of 50A x 0.75kw 200V, one adjustment tank aeration stirring blower of 50A x 2.2kw 200V, and six disk-type diffusion agitation devices were installed.

The biological treatment tank is operated intermittently, and the required capacity is 140.0 m ³ /D × 500 mg/l ÷ 0.2 kg BOD/m ³ in order to reduce the inflow BOD load to 0.2 kg BOD/m ³ or less.・Day = ^350.0m3 . Actual capacity is W5.0m×L6.6m×H4.0m=132.0m ³ , W4.2m×L6.6m×H4.0m=110.88m ³ , W3.0m×L6.6m×H4.0m= 79.2 m ³ , W5.0 m×L 4.0 m×H 4.0 m (membrane treatment tank)=80.0 m ³ , total 402.08 m ³ . The required capacity is O ₂ = (0.8 x 70.2 kg/D) + (0.07 x 5 kg/m ³ x 402.08 m ³ ) = 196.89 kg/d, O ₂ = 196.89 kg/ d÷0.49 kg/m ³ ÷0.04=10,045.5 m ³ /d=10.1 m ³ /min.

The membrane treatment tank is 24H/D (8 minutes operation - 2 minutes cleaning), and the required number of membranes is 140.0 m ³ /D ÷ 0.275 m in order to set the permeation flow rate to 0.275 m ³ /m ² · D. ³ /m ² ·D/0.8m ² /sheet/0.8H = 796 sheets, and the number of membranes used was 200 sheets/unit x 4 units = 800 sheets. The amount of air required for membrane treatment was set to 10 L/min×800 sheets=8.0 m ³ /min in order to set the air amount per membrane to 10 L/min. The return circulation ratio was set to 5 times or more. Into the above-mentioned membrane treatment tank, immersion type membrane separation device: 4 units of 200 pieces/unit with pore size of 0.1 to 0.4 μm, 2 units of membrane blower: 65 A × 45 kPa × 4.1 m ³ /min × 5.5 kw, returned One circulating pump of 50A×1.5 kw and two membrane-treated water pumps of 40A×0.75 kw (corrosion-resistant type on land) were installed.

The treated water tank has a required capacity of 140.0 m ³ /D<5.84 m ³ /h×12 hours=70.08 m ³ in order to have a capacity to store membrane-treated water for 12 hours, and an actual capacity of W1. 8m x L (6.6m + 5.9m) x H3.5m = ^78.75m3 . One treated water transfer pump 65A×2.2 kw was installed in the treated water tank.

The dilution water tank has a required volume of 70 m ³ /D in order to store the dilution water (well water + membrane treated water) for one day, and the actual volume is W4.5 m × L5.0 m × H3.5 m = 79.0 ^m3 . A dilution water transfer pump 65A x 2.2 kw (well water solenoid valve 40A) was installed in the dilution water tank.

The disinfection bath equipment has a throughput of 140.0 m ³ /D. In order to inject 10 mg/L with respect to the treatment amount, the required amount of chlorine is 140.0 m ³ /D x 10 mg/L x 10-3 = 1.40 kg/D, 1.40 kg/D ÷ 70% = 2 0 kg/D. One sterilizer (hypochlorous acid tablet dissolving method, PVC type, 15 kg type) was installed in the disinfection tank facility.

In this embodiment, the raw water tank-mixing tank-floc separator-screw press dehydrator-regulating tank-measuring tank-biological treatment tank (aeration tank)-membrane treatment tank-treated water tank-dilution tank installed in the above-mentioned Example 1 - "Pulverized rice hulls" as a dehydration aid using a disinfection tank (→ outflow) (see Figure 3) and having an MP value (moisture content evaluation) MP (cake moisture content) ≤ 70; A pulverized rice husk (sample) was used, the main component of which was pulverized with a particle size of 1 to 100 μm obtained by pulverizing the husk by mechanical shearing. Further, in the following examples, as a sample, "Reserver" (product numbers: MT2000, MT5000, MT7000, manufactured by Reserver), which is a commercially available product equivalent to the above-mentioned "pulverized rice husk", was used. These reserva products are made by adding pulverized cardboard in addition to pulverized rice husks as the main ingredient, and are classified into product numbers according to the difference in content.
In addition to these reserva products, commercial products (manufactured by Reserva Co., Ltd.) to which pulverized wheat straw, straw and/or corn cobs are added in addition to crushed rice hulls as the main component, etc. Available.

(1) Selection of flocculant As a sample of the object to be treated, biomass power generation digestive fluid [water quality after pretreatment; pH value: 7.5-8.5, BOD value: 500 mg / l (removal rate 83.3%) , SS value: 300 mg / l (removal rate 98.0%)], and 0.1% (relative to sludge capacity) of the sample (commercially available product) Reserva (MT2000) is added to 100 ml of the sludge as a dehydration aid. Approximately 30 types of flocculants (polymer flocculants, etc.) were added, and the reaction was confirmed. For example, a flocculant (RB-C1805) was added at an addition rate of 46%, and floc determination was performed.

The results are shown in Table 1. Judgment conditions were A to E; A was the highest rank and E was the lowest rank. Since the evaluation of the supernatant water was the best A++ among all product numbers for the flocculant RB-C1805, from about 30 types of flocculants, the flocculant (RB-C1805) was selected as the dehydration aid Reserva (MT2000). was selected as a flocculant (polymer flocculant compatible with dehydration aid).

(2) Selection of dehydration aid Next, in order to select a specific pulverized material that can be used in the present invention from the pulverized material obtained by pulverizing vegetable fibers by mechanical shearing as a dehydration aid, 100 ml of sludge , Add 0.1% (relative to sludge capacity) of 3 types of commercially available products ("Reserver MT2000", "Reserver MT5000", and "Reserver MT7000", and determine flocs (supernatant water, size, hardness , grip feeling) and overall evaluation, and the results are shown in Table 2. The evaluation conditions were A to E, where A is the highest rank and E is the lowest rank.

When the reaction was confirmed, the evaluation of the supernatant water in the floc judgment was A+++, which was the best among all product numbers, with MT7000. Therefore, in the following dehydration test of this example, as a dehydration aid, a pulverized product (sample) whose main component is a pulverized product with a particle size of 1 to 100 μm obtained by pulverizing vegetable fiber rice husks by mechanical shearing. We decided to use the commercially available product "Reserva (MT7000)".

(3) Dehydration test To 600 ml of sludge, add the dehydration aid "Reserver (MT7000)" and add the flocculant (product number: RB-C1805) at an addition rate of 46% (relative to sludge volume, 0.2% aqueous solution). to form flocs. Next, the flocs are put into a dehydration tester equipped with a screw press dehydrator, and a dehydration test is performed. The desorbed liquid from which the flocs are removed and the dehydrated cake are separated. Analysis was carried out. The dehydration pressure and retention time assumed a screw press dehydrator. The results are shown in Table 3. By adding 0.1% reserva, the moisture content of the dehydrated cake was 59.03%.

(4) Water quality analysis of desorbed liquid Water quality analysis (BOD, COD, SS , TN analysis) was performed at a public institution. The results are shown in Table 4. Reservoir dehydration was confirmed to remove 86.5% of BOD, 91.8% of COD, 99.8% of SS, and 54% of TN.

(5) Summary Reservoir dehydration was confirmed to significantly reduce all items in the water quality analysis of the desorbed liquid. As a result, it was found that a significant reduction in the construction cost of the septic tank can be expected. It was confirmed that the moisture content of the cake was reduced to 59.3% by reserving water. .

A suitable flocculant is product number RB-C1805 and the addition rate is 46% (based on sludge volume, 0.2% aqueous solution). A suitable reservor is product number MT7000 and the addition rate is 0.2%. It was 1% (relative to sludge volume).

Evaluation of supernatant water; turbidity → transparent, evaluation of floc; , “Hardness”; soft → hard, “grip feeling”; can not be gripped → firmly gripped, expected (expected) cake moisture content; 90% or more, 80-90%, 70-80%, 55-70%, Table 5 summarizes the results of 55% or less.

According to the above dehydration test, the supernatant water was transparent (the size of the flocs was extra large (φ10 mm or more)), and the water content of the dehydrated cake was 59.3%, which is 55-70%. Further, in the present invention, not only when a dehydration aid with MP (moisture content of cake) ≤ 55 is used, but also when a dehydration aid with MP (moisture content of cake) = 55 to 70% is used, the supernatant water is almost transparent (the size of the floc is large (φ5 to 10 mm)), and if the moisture content of the dehydrated cake is in the range of 55 to 70%, the purified liquid phase can be discharged into the river. It was confirmed that it could be purified.

In this example, digested sludge from a sewage treatment plant of a municipality (K city) was used as a target sample, and the sample was purified.

(1) Selection of flocculant Sludge [Sample properties; TS (solid matter) concentration: 1.33%, pH: 7.25. Appearance: Dark turbid color, Odor: Charcoal smell, Fibrous material (100 mesh): 5.2%/ss, Fibrous material (200 mesh): 14.2%/ss] Add 0.1 of Reserva MT2000 to 100 ml. % (relative to sludge volume), about 30 types of flocculants (including those designated by K City) were added, and the reaction was confirmed. Table 6 shows the results.

When the reaction was confirmed, the evaluation of "grip feeling" in the floc evaluation was B-, so the coagulant designated by the local government (K city) was selected as the coagulant.

(2) Selection of Reserva To 100 ml of sludge, 0.1% (relative to sludge volume) of three types of reservers MT2000, MT5000, and MT7000 were added, and the reaction was confirmed. Table 7 shows the results.

As a result of checking the reaction, Reservar MT2000, which was the highest evaluation of all product numbers in terms of “feeling of grip” in the flock judgment, was selected.

(3) Dehydration Test To 500 ml of sludge, Reservor MT2000 was added, and a polymer flocculant (0.2% aqueous solution) was added to form flocs. The floc was placed in a dehydration tester (pressure area 81 cm ² , variable pressure/holding time type) to conduct a dehydration test, and the moisture content of the discharged dehydrated cake was measured. The dehydration pressure and retention time were set assuming a screw press dehydrator. Table 8 shows the results.

With the addition of 0.04% reservar (3% relative to TS addition rate), the moisture content of the cake was 78.67%. With the addition of 0.1% reserva (7.5% relative to TS), the moisture content of the cake was 74.18%. With the addition of 0.3% reserva (relative to TS addition ratio of 22.5%), the moisture content of the cake became 69.92%.

(4) Water Quality Analysis of Desorbed Water The raw water (water before dehydration), the SS value after desorption in the dehydration test, and the TP value were measured by a public institution. Table 9 shows the results.

(5) Recovery rate of SS The recovery rate of SS was 99.6% with the addition of 0.1% reserva (7.5% relative to TS addition rate) and the designated flocculant by the municipality (K city). 3% addition (22.5% of TS addition rate), 99.75% by local government (K city) designated flocculant, 0.1% reserva addition (7.5% of TS addition rate), polymer With the flocculant (0.2% aqueous solution), it was 99.7%, and with the addition of 0.3% reserva (22.5% relative to TS) and the polymer flocculant (0.2% aqueous solution), it was 99.7%. was 76%.

(6) Recovery rate of TP The recovery rate of TP is 81% due to the addition of 0.1% reserva (7.5% compared to TS addition rate) and the designated flocculant by the municipality (K city). Addition of 0.3% (addition rate of 22.5% to TS), 81% due to the local government (K city) designated flocculant, addition of 0.1% reserva (addition rate of TS to 7.5%), high polymer With the flocculant (0.2% aqueous solution), it was 78.4%, and with the addition of 0.3% reselver (22.5% relative to TS) and the polymer flocculant (0.2% aqueous solution), it was 80.4%. was 6%.

(7) Summary A suitable reservoir product number is MT2000, the addition rate is 0.04% to 0.3% (relative to sludge volume), and the addition rate to TS is 3% to 22.5% (sludge volume 0.4 kg to 3 kg was used for 1 m ³ ). In addition, the product number of the suitable flocculant is the local government (K city) designated flocculant, the addition rate is 12% (0.2% aqueous solution), and the addition rate to TS is 1.8% (sludge amount 1m 0.24 kg was used for ³ ).

The product number of a suitable flocculant is a local government (K city) designated flocculant, the addition rate is 12% (0.2% aqueous solution), and the addition rate to TS (0.24 kg is used for 1 m ³ of sludge) ) was 1.8%. By reservoir dewatering, the cake moisture content was 69.92% to 78.67%, the recovery of SS was 99.6% to 99.75%, and the recovery of TP was 81%. there were.

Evaluation of supernatant water; turbidity → transparent, evaluation of flocs; Yes, "hardness" is soft → hard, "feeling of grip" is not grippable → firmly grippable, comprehensive "evaluation" is E to A, "anticipated (anticipated) cake moisture content The rates were ≧90%, 80-90%, 70-80%, 55-70%, 55% or less (see Table 5).

In this example, it was verified whether or not the water content of the cake could be reduced by the dehydration treatment of the biomass digestate.

(1) Confirmation of sludge properties As a sample, biomass digestive fluid (wet methane fermentation digestive fluid of food waste raw material [sample properties; TS (solid matter) concentration: 5.49%, pH: 7.59. Appearance: black Turbid color, odor: nitrification odor]) was used as a control sample.

(2) Dehydration Test To 300 ml of sludge, a dehydration aid Reserva (MT2000) was added, and a polymer flocculant A (0.2% aqueous solution) was added to form flocs. The floc was placed in a dehydration tester (pressure area 81 cm ² , pressurization/holding time variable type) to conduct a dehydration test, and the moisture content of the discharged cake was measured. The dehydration pressurization/holding time was 1 minute at 2,000 G assuming a centrifuge, and 5 minutes at 490 kPa assuming a screw press. Table 10 shows the results.

Reservoir MT2000 and polymer flocculant A (0.2% aqueous solution) were added, and the cake was dehydrated as if using a centrifuge. As a result, the moisture content of the cake was 77.62%. Moreover, as a result of adding Reservar MT2000 and polymer flocculant A (0.2% aqueous solution) and dehydrating assuming a screw press, the moisture content of the cake was 67.92%. Leakage (leakage) of SS into the desorbed liquid was almost non-existent in the centrifuge simulation test, and was small in the screw press simulation test.

(3) Conclusion Due to reservoir dehydration, the moisture content of the cake was 77.62% in the centrifugal hypothetical test, and dehydration to 75% or less by the centrifugal was considered impossible due to the low dehydration pressure. In addition, since the moisture content of the cake was 67.92% in a screw press imaginary test, it was determined that dehydration to 75% or less is possible with a screw press.

In this example, dehydration treatment of digestive fluid generated in a biomass power generation facility was carried out.

As a sample, digestive juice of biomass power generation [sludge before solid-liquid separation; TS (solid matter) concentration: 4.36%, pH: 7.51, appearance: black turbid color, odor: nitrification odor, sludge after solid separation TS (solid matter) concentration: 1.04%, pH: 8.14, appearance: brown, odor: nitrification smell] was used to conduct a dehydration treatment test of the digestive juice. Before and after solid-liquid separation, there was a difference of 4 times or more in TS (solid matter) concentration.

(1) Selection of flocculant To 100 ml of sludge, add Reservar MT2000, a dehydration aid, add about 20 kinds of flocculants, check the compatibility between the reservor and sludge, and select the product number. It was confirmed. Table 11 shows the results. The compatible flocculant had the same product number for the sludge before and after solid-liquid separation. There was a 1.6-fold difference in the amount of coagulant added between the sludge before and after solid-liquid separation.

(2) Dehydration test Reserva (MT2000) was added to the sludge at an addition rate of 0.05% (relative to the volume of wastewater), and polymer flocculant A was added to form flocs. The floc was placed in a dehydration tester (pressure area 81 cm ² , variable pressure/holding time type) to conduct a dehydration test, and the moisture content of the discharged dehydrated cake was measured. Assuming a screw press dehydrator, the dehydration pressure and retention time were set at 480 kPa for 5 minutes. Table 12 shows the results.

(Sludge before solid-liquid separation)
To 500 ml of sludge, Reservar MT2000 and polymer flocculant A (0.2% aqueous solution) were added in an amount of 340 ml, and dewatered assuming a screw press.
(Sludge after solid-liquid separation)
To 700 ml of sludge, Reservar MT2000 and polymer flocculant A (0.2% aqueous solution) were added in an amount of 300 ml, and dewatered assuming a screw press.

(3) Water quality analysis Water quality analysis was performed on raw waste water (water before dehydration) and desorbed liquid in the dehydration test. TN was performed by a public institution, and BOD was performed by a BOD meter. Table 13 shows the results.

(Sludge before solid-liquid separation)
Reservoir dehydration removed 63.6% of BOD to 480 mg/l. TN remained at a removal rate of 35%. Most of the remaining nitrogen was considered ammoniacal nitrogen.
(Sludge after solid-liquid separation)
Reservoir dehydration removed 83.5% of BOD to 400 mg/l.

(4) Summary It was found that the planned installation capacity of the biological treatment tank (aeration tank) is reduced to 1/3 of that for treating raw water as it is because the BOD is reduced to 1/3 by the reservor dehydration treatment. In addition, it was found that the moisture content of the cake was in the lower half of 70%, which facilitated the subsequent treatment and facilitated planning of composting and industrial waste disposal.

In this example, the digestive juice (high concentration) of biomass power generation was used, and the digestive juice was dehydrated.

As a sample, biomass power generation digestive fluid [Wastewater properties: TS (solids) concentration: 81.17%, pH: 8.05, Appearance: dark brown, Odor: Slight nitrification odor] was used. The TS (solids) concentration was as high as 8%, and in the subsequent tests, a 2-fold dilution was used.

(1) Dehydration test To 300 ml of waste water, a dehydration aid Reserva (MT2000) was added at an addition rate of 0.05% (based on the volume of waste water), and flocculant A or B was added to form flocs. The floc was placed in a dehydration tester (pressurization area 81 cm ² , variable pressure/holding time type), a dehydration test was performed, and the moisture content of the discharged cake was measured. The dehydration pressure/holding test was performed at 480 kPa for 5 minutes assuming a screw press dehydrator. Table 14 shows the results.

Reserva MT2000, 60 ml of flocculant A (0.5% aqueous solution), 120 ml of flocculant B (0.2% aqueous solution) were added, and dehydration was performed assuming a screw press machine. As a result, the moisture content of the cake was 61. .1%.

(2) Water quality analysis A BOD meter was used to measure the BOD of raw wastewater (water before dehydration) and the desorbed liquid in the dehydration test. Table 15 shows the results.
In the reservoir dehydration, 82.2% BOD was removed to 535 mg/l. SS was almost removed by visual confirmation. The dilution ratio of the raw water is preferably 2 times or more, and in the reservor dehydration treatment, the moisture content of the cake was 61.1%, and the BOD was removed by 82.2%, resulting in 535 ml.

In this example, it was tested how much the BOD and SS concentrations could be lowered and how much the moisture content of the cake could be lowered by dehydrating the biomass digestive juice with a reservoir. FIG. 1 schematically shows an example of a reservoir dehydration system used in this example. A floc separator is shown as an option in the figure.

As the wastewater of the sample to be treated, biomass digestive fluid [sample properties; TS (solid matter) concentration: 4.17%, pH: 7.50, appearance: dark brown, odor: nitrification odor] was used. A dehydration test and a water quality analysis test were performed.

(1) Dehydration test To 500 ml of wastewater, 0.30% (relative to wastewater volume) of reserva (MT2000), a dehydration aid, is added, 150 ml of flocculant A (0.5% aqueous solution), flocculant B (0.2 % aqueous solution) was added to form flocs. Once the water is removed from the ^flocs with a filter cloth, the water is treated as desorbed water and subjected to the subsequent water quality analysis test. A test was conducted and the moisture content of the discharged cake was measured. Assuming a screw press dehydrator, the dehydration pressure and retention time were set at 480 kPa for 5 minutes. Table 16 shows the results.

As shown in the table, by adding Reservar MT2000, adding flocculants A and B, and dehydrating, the moisture content of the cake became 71.95%. The amount of the flocculant to be added varies depending on the biomass raw material, but in the case of biomass digestive juice derived from cow dung or poultry dung, the amount to be added tends to be large.

(2) Water quality analysis test BOD, SS (suspended solids), phosphorus, and nitrogen in raw waste water (water before dehydration) and dehydrated liquid in the dehydration test were measured by a public institution (environmental measurer). Table 17 shows the results.

90.5% of the BOD in raw waste water (water before dehydration) is removed, and the BOD in the dehydrated and dehydrated liquid of the reserver is reduced from 4,300 mg/l to 410 mg/l, and the water treatment effect of the reserver is remarkably exhibited. was confirmed. In addition, 99% of the SS in raw wastewater (water before dehydration) was removed, and the SS in the dehydrated and dehydrated liquid of the reserver was reduced from 26,000 mg/l to 25 mg/l. It was confirmed that it works.

By reservor dehydration, 90.5% of BOD was removed from raw wastewater (water before dehydration), and 99.9% of SS was removed from reservor desorbed liquid, resulting in 25 mg/l. In addition, the moisture content of the cake was as low as 71.95%. From these values, it was confirmed that the reservoir dehydration of biomass digestive juice is capable of highly efficient dehydration and water treatment performance.

(3) Conclusion It was confirmed that the moisture content of the dehydrated cake was reduced to 75% to 65% by the dehydration treatment using the reserver, and that the moisture content could be freely set by increasing or decreasing the amount of reserva added. According to the water quality analysis test of the dehydrated and dehydrated reservoir liquid, phosphorus of the dehydrated and dehydrated reservoir liquid was removed by an average of 95%, SS (suspended solids) was removed by an average of 95%, BOD was removed by an average of 60%, and nitrogen was removed. was confirmed to be removed by an average of 60%. It was confirmed that the dehydration system by reserva can be used as a water recycling technology as a water treatment system.

In this example, it was tested how much the BOD and the cake dehydration rate could be reduced by dehydrating the digestive fluid generated in biomass power generation by reserving. A reserva dewatering system similar to that used in Example 7 was used.

(1) Dehydration Test To 500 ml of sludge, 90 ml of a dehydration aid Reserva (MT2000) and 90 ml of polymer flocculant A (0.2% aqueous solution) were added to form flocs. The floc was placed in a dehydration tester (pressure area 81 cm ² , pressurization/holding time variable) to conduct a dehydration test, and the moisture content of the discharged cake was measured. Assuming a screw press dehydrator, the dehydration pressure and retention time were set at 480 kPa for 5 minutes. Table 18 shows the results.

As shown in the table, 0.30% of Reserva MT2000 was added (relative to wastewater volume), 90 ml of polymer flocculant A (0.2% aqueous solution) was added, and dehydration was performed assuming a screw press machine. was 72.75%.

(2) Water quality analysis test Raw wastewater (water before dehydration) and desorbed liquid in the dehydration test were measured with a BOD meter (Central Kagaku Co., OxiTop System). Table 19 shows the results. Due to the reservoir dehydration, the BOD of raw waste water (water before dehydration) of 6,920 mg/l was halved to the BOD of the reservoir dehydrated liquid (water after dehydration) of 3,450 mg/l.

It was confirmed that the BOD of the raw wastewater (water before dehydration) was halved by the reservor dehydration treatment, and the design plan capacity of the biological treatment tank (aeration tank) was halved compared to when the undiluted solution was treated as it was. In addition, it was confirmed that the moisture content of the cake was in the lower half of 70%, which facilitated the subsequent treatment and facilitated planning of composting and industrial waste disposal.

(3) Summary It was confirmed that the moisture content of the dehydrated cake was reduced to 75% to 65% by the dehydration treatment. As a result of the water quality analysis test of the desorbed liquid of the reservoir dehydration, an average of 95% of phosphorus is removed, an average of 95% of SS (suspended solids) is removed, an average of 60% of BOD is removed, and an average of 60% of nitrogen is removed. was confirmed. It was confirmed that the reservoir dewatering system can be used as a recycling technology for water treatment systems.

In this example, by dehydrating the biomass power generation digestive juice, the water content of the cake was measured and the water quality analysis test of the reservoir dehydrated and desorbed liquid was carried out.

In this example, sludge [sludge properties; TS (solids) concentration: 2.73%, pH: 7.63, appearance: dark brown, dark brown, odor: slightly putrid odor] was used as a sample, and the sludge was dehydrated. Tests and water quality analysis [phosphorus, SS (suspended solids), BOD, nitrogen] of the dehydrated and desorbed reservoir liquid were performed. FIG. 2 schematically shows an example of a reservoir dehydration system plant used in this example.

(1) Dehydration test To 800 ml of sludge, 0.10% (relative to sludge volume) of Reserva (MT2000), a dehydration aid, was added, and a polymer flocculant (0.2% aqueous solution) was added to form flocs. . The floc was placed in a dehydration tester (pressure area 81 cm ² , pressurization/holding time variable) to conduct a dehydration test, and the moisture content of the discharged cake was measured. Assuming a screw press dehydrator, the dehydration pressure and retention time were set at 480 kPa for 5 minutes. Table 20 shows the results.

As shown in the table, 0.1% of Reserva MT2000 and 100 ml of polymer flocculant (existing product) (1.5% of TS) were added, and dehydration was performed assuming a screw press, resulting in a cake moisture content of 72.11%. became. Although the sludge is originally easy to dehydrate, it was confirmed that the addition of the reservor almost eliminates SS leakage and promotes subsequent fermentation. As a result of dehydration by adding reserva, the moisture content of the cake was 72.11%, and it was confirmed that further reduction is possible by increasing the amount of addition.

(2) Water quality analysis test A water quality analysis test was conducted on the dehydrated and dehydrated liquid of the reservoir. As a result, an average of 95% of phosphorus was removed, 95% of SS (suspended solids) was removed on average, 60% of BOD was removed on average, and 60% of nitrogen was removed on average. It was confirmed that the water content can be freely set by increasing or decreasing the amount of reserva added. It was confirmed that the reservoir dewatering system can be used as a recycling technology for water treatment systems.

In this example, it was investigated how much the moisture content of the cake can be reduced by the dehydration treatment of the sludge of the ink washing wastewater.
In this embodiment, ink-washing wastewater sludge [sludge property: TS (solid concentration: 0.45%, pH: 6.24, appearance: black turbidity and slightly transparent color, odor: mineral oil odor]) is used as a sample. , reserver dehydration test, and water quality analysis test of reserver dehydrated and desorbed liquid [phosphorus, SS (suspended solids), BOD, nitrogen].

(1) Dehydration test To 800 ml of sludge, 0.3% (relative to sludge volume) of Reserva (MT2000), a dehydration aid, is added, and 75 ml of polymer flocculant A (0.2% aqueous solution) is added to form flocs. let me The floc was placed in a dehydration tester (pressure area 81 cm ² , pressurization/holding time variable), and the moisture content of the discharged cake was measured. Dehydration pressure and retention time were set to 960 kPa for 10 minutes assuming a filter press dehydrator, and 480 kPa and 5 minutes assuming a screw press. Table 21 shows the results of the dehydration test.

As shown in the table, as a result of adding Reserva MT2000 and polymer flocculant A and dehydrating assuming a filter press, the moisture content of the cake was 72.74%. It became 77.54%. The reservoir dehydration reduced the moisture content of the cake to 72.74% to 77.54%, a reduction of 15% to 20% or more from the current state. This reduced the amount of dehydrated cake to 1/3 of the current amount.

(2) Dehydration effect The moisture content of the cake can be freely set by increasing or decreasing the amount of reserva added, and as a water treatment effect, an average of 95% of phosphorus is removed and an average of 95% of SS (suspended solids) is removed. , BOD was removed on average 60%, and nitrogen was removed on average 60%. It was confirmed that the reservoir dewatering system can be used as a recycling technology for water treatment systems.

As described in detail above, the present invention relates to a biomass digestive juice treatment method and a wastewater treatment apparatus for the same, and the present invention focuses on 1) the biomass digestive juice, in particular, the emulsified component and the fine particle component, In order to efficiently remove these before flowing into the aeration tank, the Mp value (moisture content evaluation) should be Mp (moisture content of cake) ≤ 70, more specifically, Mp (moisture content of cake) ≤ 55 to Mp (moisture content of cake). ) = 55 to 70 by using a specific dehydration aid and a flocculant together to form flocs that include the emulsified component and the fine particle component in the biomass digestive fluid, and to remove the flocs / dehydrate the organism. 2) By using the above-mentioned specific dehydration aid and flocculant together, the biomass digestive fluid can be discharged in a manner that meets the general wastewater standards according to the Water Pollution Control Law. 3) It is possible to reuse the dehydrated cake generated as a residue in a composting facility. 5) According to the present invention, a desorbed liquid from which extra-large (φ10 mm or more) to large (φ5-10 mm) flocs are removed, and a dehydrated cake; moisture content of 70% or less, more specifically, moisture content of 55 % or less to 55-70%, making it possible to remove the BOD of raw water to 78% or less. 6) Reduction of BOD volume burden, suppression of sludge generation, and reduction of required oxygen It has industrial applicability that a stable water treatment effect can be expected.

Claims (5)

A method for treating digested sludge forming an emulsion, comprising:
The digested sludge of the water to be treated is mainly composed of pulverized material with a particle size of 1 to 100 μm obtained by pulverizing vegetable fibers by mechanical shearing, and the Mp value (Moisture percentage value; moisture content evaluation) is Mp (cake moisture content) ≤ 55 to Mp (moisture content of cake) = 55 to 70 by adding a dehydration aid and a flocculating agent having floc (fluff-like precipitation) forming ability to form flocs; ~ 10 mm), a step of separating the desorbed liquid from which the flocs have been removed and a dehydrated cake; a moisture content of 55% or less to 55 to 70%, and then the desorbed liquid in a biological treatment tank (aeration tank ) and carrying out biological treatment. In a purification facility equipped with at least a mixing tank, a reaction tank, a sludge dehydrator, a (neutralization tank) and a biological treatment tank, adding the specific dehydration aid to the digested sludge of the water to be treated in the mixing tank, Next, in the reaction tank, a flocculating agent having flocculation ability is added to the water to be treated, and flocs containing the emulsified component and the fine particle component in the digested sludge; A step of removing the flocs in the sludge dehydrator and simultaneously separating into a desorbed liquid from which the flocs have been removed and a dehydrated cake; a moisture content of 55% or less to 55 to 70%, 2. The treatment method according to claim 1, comprising the step of introducing the liquid into a biological treatment tank (aeration tank) to perform biological treatment. 3. The treatment method according to claim 1 or 2, wherein an operation for removing flocs containing emulsified components and particulate components in digested sludge is carried out before the water to be treated flows into the biological treatment tank. A wastewater treatment apparatus for use in the digested sludge treatment method according to any one of claims 1 to 3,
At least a mixing tank - a reaction tank - a sludge dehydrator - (neutralization tank) - including a purification facility equipped with a biological treatment tank as a component,
1) In the mixing tank, the digested sludge forming the emulsion of the water to be treated is crushed by mechanical shearing, and the main component is a pulverized product with a particle size of 1 to 100 μm, and the Mp value (moisture content evaluation) A step of adding a dehydration aid having Mp (cake moisture content) ≤ 55 to Mp (cake moisture content) = 55 to 70;
2) In the reaction tank, a flocculant with flocculation ability is added to the water to be treated to form flocs that clathrate the emulsified component and fine particle component in the digested sludge; the process of causing
3) A step of separating the desorbed liquid from which the floc has been removed and a dehydrated cake;
and the desorbed liquid is introduced into a biological treatment tank (aeration tank) for biological treatment. 1) A step of adding a dehydration aid having an Mp value (moisture content evaluation) of Mp (cake moisture content) = 55 to 70 to the digested sludge of the water to be treated in the mixing tank,
2) A step of adding a flocculating agent to the water to be treated in the reaction tank to form large flocs (φ5 to 10 mm) containing the emulsified component and the fine particle component in the digested sludge;
3) A step of separating into a desorbed liquid from which the flocs have been removed and a dehydrated cake with a water content of 55 to 70%,
5. The wastewater treatment apparatus according to claim 4, wherein the desorbed liquid is put into a biological treatment tank (aeration tank) to perform biological treatment by executing the above.

Images