JP6376951B2 - Phosphorus recovery equipment and phosphorus recovery method - Google Patents

Description

  The present invention relates to a phosphorus recovery facility and a phosphorus recovery method.

  Phosphorus ore, which is necessary for the production of phosphorous fertilizer and industrial phosphoric acid, is an important resource that is designated as a strategic material in Europe and the United States as a depleted resource. Recovery of phosphorus resources from waste has become an important issue. In particular, phosphorus concentrated in organic sludge such as sewage sludge is assumed to account for 10-20% of imported phosphorus ore, and various phosphorus recovery facilities for recovering phosphorus from organic sludge have been proposed. ing.

  Such a phosphorus recovery facility includes a sludge receiving part for receiving organic sludge containing phosphorus, a mixing processing part for adding a polymer flocculant to the organic sludge received by the sludge receiving part, and a mixing processing part. The sludge separation processing part which isolate | separates a liquid component from the organic sludge mixed-processed in (4) and the phosphorus collection | recovery processing part which collect | recovers phosphorus from the separated liquid isolate | separated in the sludge separation processing part are provided. In the phosphorus recovery processing section, a crystallization method such as a MAP method or a HAP method is used.

  For example, in Patent Document 1, after applying a crystallization method in which phosphorus can be recovered in a form that can be reused as fertilizer or the like, phosphorus is recovered with high efficiency, and at the same time, dehydrated sludge having a low water content is discharged, In addition, a sludge treatment apparatus or the like that does not use a pH adjuster or diluting water or can reduce the amount of use thereof is disclosed.

  Specifically, a polymer flocculant addition means for adding a polymer flocculant to sludge, and at least a part of the sludge after the addition of the polymer flocculant is solid-liquid separated, and the flocculent sludge and the separated liquid are discharged. A concentration part that collects phosphorus by applying a crystallization method to the separated liquid, and a phosphorus recovery part that discharges the remaining alkaline dephosphorization liquid, and an inorganic flocculant added to add inorganic flocculant to the flocculated sludge Means, a dehydrating part for dewatering the coagulated sludge after adding the inorganic flocculant, and discharging the dehydrated sludge and the acidic dehydrated liquid, and the neutralized liquid by mixing the alkaline dephosphorization liquid and the acidic dehydrated liquid And a mixing section for discharging the sludge.

  According to the sludge treatment apparatus, a dehydrated sludge having a low water content suitable as a combustion aid can be obtained by further adding an inorganic flocculant to the agglomerated sludge to which the polymer flocculant has been added and performing solid-liquid separation.

  In addition, Patent Document 2 discloses a liquid to be treated containing human waste and septic tank sludge for the purpose of providing a water treatment apparatus and the like that can increase the amount of phosphorus recovered during treatment of liquid to be treated containing human waste and septic tank sludge. Pre-dehydration equipment that has a polymer supply means for adding a polymer, mainly removes SS in the liquid to be treated, biological treatment equipment for biological treatment of the dehydrated filtrate of the pre-dehydration equipment, and biological treatment through the biological treatment equipment It has a calcium supply means for adding calcium to water and a pH adjuster supply means for adding a pH adjuster, and is equipped with a phosphorus recovery facility for precipitating and separating and removing by crystallizing phosphorus in biologically treated water as hydroxyapatite. A water treatment apparatus characterized by the above is disclosed.

  In any case, by adding a polymer flocculant to the sludge and performing solid-liquid separation, phosphorus remains on the separation liquid side without being taken into the solid side and can be efficiently recovered. When an inorganic flocculant such as polyferric sulfate or ferric chloride is added to the sludge, phosphate ions dissolved in the sludge react with these inorganic flocculants to form phosphate solids, resulting in solid-liquid separation. Since the concentration of phosphate ions contained in the subsequent separation liquid decreases and the phosphorus recovery efficiency decreases, a polymer flocculant has been used instead of the inorganic flocculant.

Japanese Patent No. 5439439 Japanese Patent No. 4660247

  In Patent Document 1, an alkaline dephosphorization solution discharged from a phosphorus recovery unit and an acidic dehydration solution obtained by dehydrating agglomerated sludge to which an inorganic flocculant has been added are mixed in a mixing unit to obtain a neutralization treatment solution. It is described that it can be biologically processed or discharged after use without using a pH adjuster or dilution water, and FIG. 4 of Patent Document 1 shows one of the neutralization treatment liquids mixed in the mixing unit. The aspect which circulates and supplies a part to a phosphorus collection | recovery part is disclosed.

  However, since some phosphorus components remain in the treated water after biological treatment, an inorganic flocculant is added to the treated water after biological treatment to obtain high-quality treated water including advanced treatment. Therefore, it is necessary to agglomerate and separate phosphorus components and the like, and a separate solid-liquid separation device such as a filter press is required to process the agglomerates at that time, resulting in a problem that equipment costs increase.

  In addition, when a part of the neutralization treatment liquid mixed in the mixing unit is circulated and supplied to the phosphorus recovery unit, the acidic dehydrating liquid containing the inorganic flocculant component is supplied to the phosphorus recovery unit. In this case, phosphate ions dissolved in the treatment liquid react with the inorganic flocculant to form phosphate solids, and the concentration of phosphate ions contained in the treatment liquid may decrease, leading to a decrease in phosphorus recovery efficiency. It was.

  In Patent Document 2, some 10 to 20 mg / L of phosphorus remaining in the treatment liquid after phosphorus recovery is taken into the activated sludge by the biological treatment facility, and the phosphorus concentration becomes about 10 mg / L or less. Although it is described that it is not necessary to provide a coagulation / separation facility in the subsequent stage, in order to obtain high-quality treated water, an inorganic flocculant is further added to the treated water after biological treatment to coagulate and separate phosphorus components, etc. There is a need and a problem similar to the above is inherent.

  In the case of Patent Document 2, in order to obtain dehydrated sludge having a low water content, when an inorganic flocculant is added to the concentrated sludge of the pre-dehydration facility and solid-liquid separation is performed, the separated liquid containing the inorganic flocculant is recovered by phosphorus. Since it cannot be put into the facility, a separate water treatment device for purifying the separated liquid is required, resulting in an increase in facility cost.

  In view of the above-described problems, the object of the present invention is to recover phosphorus which can efficiently recover phosphorus and obtain a dehydrated sludge having a low water content that can be used as a combustion aid without causing an increase in equipment cost. It is in providing facilities and phosphorus recovery methods.

In order to achieve the above-mentioned object, the first characteristic configuration of the phosphorus recovery facility according to the present invention is, as described in claim 1 of the claims, a sludge receiving part for receiving organic sludge containing phosphorus, and the sludge A mixing treatment unit for adding and mixing a polymer flocculant to the organic sludge received in the receiving unit, a sludge separation processing unit for separating a liquid component from the organic sludge mixed in the mixing treatment unit, and A phosphorus recovery processing unit that recovers phosphorus from the separated liquid separated by the sludge separation processing unit, wherein an inorganic flocculant is added to the concentrated sludge separated by the sludge separation processing unit. A dehydration processing unit for dehydrating, a return mechanism for returning the dehydrated liquid generated in the dehydration processing unit to the sludge receiving unit,
It is in the point equipped with.

  As a result of intensive research on the dehydrating solution containing the inorganic flocculant generated in the dehydration processing unit, the present inventors have unexpectedly found that the inorganic flocculant in the inorganic flocculant is returned to the sludge receiving unit. The reaction between the inorganic metal ions in the organic sludge and phosphoric acid in the organic sludge does not proceed, and the metal ions contained in the inorganic flocculant react preferentially with the hydrogen sulfide contained in the organic sludge containing phosphorus, and the metal sulfide The new knowledge that the bad smell generated from the sludge is greatly reduced.

  According to conventional wisdom, since the dewatered liquid obtained by adding an inorganic flocculant to sludge and dewatering contains an inorganic flocculant, if this liquid is returned to the sludge receiving part, Metal ions and phosphate ions in organic sludge react to precipitate as metal phosphate, reducing the concentration of phosphorus in the liquid, and it is expected that the amount of phosphorus recovered in the phosphorus recovery processing section will decrease. However, the results were contrary to the prediction.

  According to the above-described configuration, not only the amount of phosphorus recovered in the phosphorus recovery processing unit is not reduced, but also a separate water treatment facility for the dehydration liquid generated in the dehydration processing unit is not required, and organic sludge is not required. By reacting with the hydrogen sulfide contained in it to produce metal sulfide, hydrogen sulfide that causes malodor is removed from the organic sludge, so that no separate equipment is required to remove the malodor It is.

  As described in claim 2, the second characteristic configuration is an aggregation process in which an inorganic flocculant is added to the separation liquid from which phosphorus is recovered by the phosphorus recovery processing unit in addition to the first characteristic configuration described above. And an inorganic aggregate return mechanism that returns the aggregate that has been aggregated by the aggregation processing section to the sludge receiving section.

  An inorganic flocculant is added to the separation liquid from which phosphorus has been recovered by the phosphorus recovery processing section, and a small amount of remaining phosphorus is also agglomerated and removed, so that high-quality treated water can be obtained. Then, the aggregate containing the inorganic flocculant is returned to the sludge receiving unit, so that the hydrogen sulfide causing the malodor is removed from the organic sludge and the aggregate is processed, as in the first characteristic configuration. This eliminates the need for a separate solid-liquid separation device.

  In the third feature configuration, as described in claim 3, in addition to the first feature configuration described above, agglomeration treatment in which an inorganic flocculant is added to the separation liquid from which phosphorus is recovered by the phosphorus recovery processing unit And an inorganic aggregate return mechanism that returns the aggregate that has been subjected to the aggregation treatment in the aggregation treatment section to the dehydration treatment section.

  The agglomerates that have been agglomerated in the agglomeration part are returned to the dehydration part by the inorganic agglomerate return mechanism, and dehydrated in the dewatering part together with the concentrated sludge separated in the sludge separation part, making it suitable for combustion aid Thus, dehydrated sludge having a low water content is obtained, and the liquid content is returned to the sludge receiving part by the return mechanism, so that hydrogen sulfide causing bad odor is effectively removed from the organic sludge.

  Similarly to the second characteristic configuration described above, an inorganic flocculant is added to remove phosphorus remaining in the separation liquid from which the phosphorus has been collected by the phosphorus collection processing unit, and a large amount of inorganic flocculant is also present in the aggregate. include. Therefore, the amount of the inorganic flocculant added in the dehydration processing unit can be reduced.

  In the fourth feature configuration, in addition to any one of the first to third feature configurations described above, the phosphorus recovery processing unit is separated by the sludge separation processing unit. The phosphorus is recovered from the separated solution based on the HAP method or the MAP method.

  As a method for recovering phosphorus, a crystallization method for recovering phosphorus based on a reaction for crystallizing phosphorus in a liquid on a seed crystal surface, an adsorption dephosphorization method for recovering phosphorus using an adsorbent from a water treatment system, An alkali extraction method for recovering calcium phosphate from incinerated ash, a reductive melting method for manufacturing phosphate fertilizer from incinerated ash, and the like are known. As the crystallization method, a HAP method for recovering HAP (hydroxyapatite) from a water treatment system and a MAP method for recovering MAP (magnesium ammonium phosphate) from a water treatment system are known. The HAP method and the MAP method are methods suitable for recovering phosphorus from a liquid having a relatively high phosphorus concentration. Further, the recovered HAP and MAP can be used as it is as a soluble fertilizer. From the viewpoint of recovering phosphorus in the liquid and using the recovered phosphorus as a fertilizer, it is preferable to recover phosphorus using a crystallization method, and it is more preferable to recover phosphorus using a HAP method or a MAP method. preferable.

  In the fifth feature configuration, as described in claim 5, in addition to any one of the first to third feature configurations described above, a living organism that biologically processes the separated liquid separated in the sludge separation processing section. The phosphorus collection | recovery process part is provided with the process part, and is in the point comprised so that phosphorus may be collect | recovered based on HAP method from the to-be-treated liquid biologically processed by the said biological process part.

  The HAP method is a method in which calcium ions and a pH adjuster are added to a phosphorus-containing liquid, and phosphorus in the liquid is crystallized on the seed crystal surface to obtain HAP (hydroxyapatite). Nitrogen is removed by biological treatment. Phosphorus is recovered by applying the HAP method to the biological treatment liquid. Therefore, since phosphorus is recovered in the absence of ammonia in the phosphorus recovery processing section, it can be treated hygienically without generating odor, and the phosphorus recovery product is also hygienic without generating odor. Phosphorus can be effectively recovered under a favorable environment, and the recovered HAP can be effectively used as a soluble phosphate fertilizer.

  In the sixth feature configuration, in addition to any one of the first to fifth feature configurations described above, the organic sludge containing phosphorus is human waste and / or septic tank sludge. .

  This is because human waste and / or septic tank sludge is a liquid containing a high concentration of phosphorus, and is therefore suitable for application of the present invention, which is the recovery of phosphorus from the liquid.

The first characteristic configuration of the phosphorus recovery method according to the present invention is, as described in claim 7, a sludge receiving step of receiving organic sludge containing phosphorus in the sludge receiving portion, and the organicity accepted in the sludge receiving portion. The sludge was separated in the mixing treatment step of adding the polymer flocculant to the sludge and mixing, the sludge separation processing step of separating the liquid from the organic sludge mixed in the mixing treatment step, and the sludge separation processing step. A phosphorus recovery process for recovering phosphorus from the separation liquid, and adding the inorganic flocculant to the dewatering section to dehydrate the concentrated sludge separated in the sludge separation process And a return step of returning the dehydrated liquid generated in the dehydration step to the sludge receiving part.

  According to the second characteristic configuration of the phosphorus recovery method according to the present invention, as described in claim 8, in addition to the first characteristic configuration described above, inorganic agglomeration is performed in the separation liquid from which phosphorus is recovered in the phosphorus recovery processing step. A coagulation treatment step of adding an agent, and an inorganic aggregate return step of returning the aggregate coagulated in the coagulation treatment step to the sludge receiving part.

  The third characteristic configuration of the phosphorus recovery method according to the present invention is, as described in claim 9, in addition to the first characteristic configuration described above, an inorganic agglomeration in the separation liquid from which phosphorus has been recovered in the phosphorus recovery processing step A coagulation treatment step of adding an agent, and an inorganic aggregate return step of returning the aggregate coagulated in the coagulation treatment step to the dehydration processing unit.

  The fourth characteristic configuration of the phosphorus recovery method according to the present invention is the separation separated in the sludge separation treatment step in addition to any of the first to third characteristic configurations described above, as described in claim 10. A biological treatment step of biologically treating the solution, wherein the phosphorus recovery treatment step is a step of collecting phosphorus from the biological treatment liquid biologically treated in the biological treatment step based on the HAP method.

  As described above, according to the present invention, phosphorus recovery equipment capable of efficiently recovering phosphorus and obtaining dehydrated sludge having a low water content that can be used as a combustion aid without incurring an increase in equipment cost, and It has become possible to provide a phosphorus recovery method.

Explanatory drawing of the phosphorus collection | recovery installation by the 1st Embodiment of this invention Flow chart of phosphorus recovery method according to the first embodiment of the present invention Explanatory drawing of the phosphorus collection | recovery installation by the 2nd Embodiment of this invention Flow diagram of the phosphorus recovery method according to the second embodiment of the present invention Explanatory drawing of the phosphorus collection | recovery installation by the 3rd Embodiment of this invention Flow diagram of the phosphorus recovery method according to the third embodiment of the present invention Explanatory drawing of the phosphorus collection | recovery installation by the 4th Embodiment of this invention Flow diagram of phosphorus recovery method according to the fourth embodiment of the present invention

Hereinafter, embodiments of the phosphorus recovery facility and phosphorus recovery method of the present invention will be described.
(Embodiment 1)
FIG. 1 shows a phosphorus recovery facility 1 according to a first embodiment of the present invention. The phosphorus recovery facility 1 is an apparatus for recovering phosphorus from organic sludge containing phosphorus, and a sludge receiving unit including the receiving tank 2 and the relay tank 4 for receiving organic sludge containing phosphorus, and organic sludge containing phosphorus. Separated by the mixing treatment unit 5 for adding and mixing the polymer flocculant, the sludge separation processing unit 6 for separating the liquid from the organic sludge mixed by the mixing treatment unit 5, and the sludge separation processing unit 6. A phosphorus recovery processing unit 10 that recovers phosphorus from the separated liquid is provided. In the present specification, “organic sludge containing phosphorus” may be simply referred to as “organic sludge”.

  The sludge receiving unit 2 receives organic sludge containing phosphorus. The organic sludge containing phosphorus received in the receiving tank 2 is sent from the sludge receiving unit 2 to the pretreatment unit 3 with a desired supply amount. The pretreatment unit 3 is composed of a screen or the like, and solids in organic sludge containing phosphorus and contaminants in sewage such as long-fiber dust such as tissue paper are removed as “sediment”.

The organic sludge from which impurities have been removed is stored in the relay tank 4 and sent to the blending processing section 5 at a supply amount corresponding to the processing capacity of the blending processing section 5 and the like connected to the relay tank 4. In the mixing treatment unit 5, a polymer flocculant is added to the organic sludge and mixed. The polymer flocculant aggregates SS (floating matter) in the organic sludge to facilitate dehydration. By this treatment, phosphate phosphorus (PO ₄ ³⁻ ) contained in the organic sludge is contained in the liquid component of the organic sludge. The admixing unit 5 may be provided with a polymer flocculant supply means for supplying a desired amount of the polymer flocculant, and a stirring means for efficiently mixing the organic sludge and the polymer flocculant. May be provided.

  In the sludge separation processing unit 6, the liquid component is separated from the organic sludge mixed with the polymer flocculant in the mixing processing unit 5. The sludge separation processing unit 6 can use a known screen. The liquid component separated in the sludge separation processing unit 6 is stored in the storage unit 8 as a separation liquid, and a desired amount is sent to the biological processing unit 9 for nitrification and denitrification.

  The biological treatment unit 9 includes a nitrification / denitrification tank that removes ammonia in the separation liquid by converting nitrifying bacteria into nitric acid, and denitrifying bacteria changing nitric acid into nitrogen gas, and a membrane separation tank that separates the treated liquid after membrane treatment. I have. Part of the membrane-separated sludge is returned to the nitrification / denitrification tank as return sludge, and part is returned to the relay tank 4 as surplus sludge.

  In the phosphorus recovery processing unit 10, phosphorus is recovered from the biological treatment liquid that has been subjected to nitrification / denitrification processing in the biological processing unit 9. The recovery of phosphorus in the present embodiment is performed by the HAP method. The biological treatment liquid is supplied to the phosphorus recovery processing unit 10 together with a calcium ion source that supplies calcium ions and a pH adjuster that adjusts the pH.

  The biological treatment liquid after phosphorus is collected contains about 15 to 20 mg / L of phosphorus. In the agglomeration processing unit 11, an inorganic flocculant is added to remove residual phosphorus. The resulting aggregate and the inorganic flocculant contained in the aggregate are returned to the sludge receiving tank 2 through the inorganic aggregate return mechanism 14. The agglomeration processing unit 11 may be provided with an inorganic flocculant supply means for supplying a desired amount of the inorganic flocculant, and a stirring means for efficiently mixing the biological treatment liquid and the inorganic flocculant. It may be provided.

  In the sludge receiving tank 2, the metal ions contained in the inorganic flocculant react preferentially with the hydrogen sulfide contained in the organic sludge containing phosphorus to produce metal sulfides, and the odor generated from the sludge is greatly reduced. Will come to be.

  In the advanced treatment / disinfection facility 12, activated carbon or the like is used to remove and release pollutants such as COD and chromaticity-causing substances contained in the biological treatment liquid discharged from the coagulation treatment unit 11.

  The concentrated sludge separated in the above-described sludge separation processing unit 6 is added with an inorganic flocculant and dehydrated in the dehydration processing unit 7 to obtain a dehydrated sludge having a low water content. For this reason, the transportation and transportation cost to the outside of the treatment site can be reduced due to the volume reduction effect, or it can be used as a combustion aid by utilizing the amount of heat generated when burned. The liquid dehydrated by the dehydration processing unit 7 is returned to the sludge receiving unit 2 via the return mechanism 13.

  The liquid returned via the return mechanism 13 or the aggregate returned to the inorganic aggregate return mechanism 14 and the inorganic flocculant contained in the aggregate are mainly the sludge receiving tank 2. These return destinations may be the relay tank 4 constituting the sludge receiving unit 2 together with the sludge receiving tank 2, or may be both the sludge receiving tank 2 and the relay tank 4.

FIG. 2 shows a flowchart of the phosphorus recovery method according to the first embodiment of the present invention.
The sludge receiving process in which the organic sludge containing phosphorus is received by the sludge receiving section described above is executed, and the mixing treatment section 5 adds the polymer flocculant to the organic sludge received by the sludge receiving section 2 and mixes them. Processing steps are performed.

  A sludge separation processing step is performed to separate the liquid component from the organic sludge mixed by the mixing treatment unit 5 by the sludge separation processing unit 6, and the separation liquid separated from the sludge separation processing unit 6 by the phosphorus recovery processing unit 10 is used. A phosphorus recovery process for recovering phosphorus is executed, and a dehydration process for adding and dehydrating the inorganic flocculant to the concentrated sludge separated in the sludge separation process by the dehydration processing unit 7 is executed. Then, a return process is performed in which the liquid component dehydrated in the dehydration process by the return mechanism 13 is returned to the sludge receiving unit 2.

The organic sludge containing phosphorus is not particularly limited as long as it is a mud-like waste having a solid and liquid intermediate state containing phosphate phosphorus (PO ₄ ³⁻ ). In addition to those generated from various fields such as pollution control facilities such as sewage, human waste treatment, and wastewater treatment.

As organic sludge containing phosphorus, human waste and / or septic tank sludge is particularly preferable. This is because human waste and / or septic tank sludge has a high phosphorus content and also contains hydrogen sulfide (H ₂ S) that causes malodor. There is no restriction | limiting in particular as organic sludge suitable for the collection | recovery method of the phosphorus of this invention, For example, 30-500 mg / L as phosphorus content (total phosphorus), 30-300 mg / L as phosphoric acid state phosphorus density | concentration Organic sludge containing phosphorus is mentioned.

  In the sludge receiving step, the sludge receiving unit 2 settles and removes foreign substances that damage the subsequent apparatus such as earth and sand, stones, and metal pieces contained in the organic sludge containing phosphorus.

  In the organic sludge accepted by the sludge receiving unit 2, contaminants in the sewage such as solid matter and tissue-like waste such as tissue paper are present. In the pretreatment step, these impurities are removed by the pretreatment unit 3.

  In the mixing treatment step, the polymer flocculant is added to the organic sludge in the mixing treatment unit 5. The polymer flocculant added to the organic sludge in the mixing treatment unit 5 can be added to the organic sludge, and aggregates SS (floating matter) in the organic sludge to facilitate solid-liquid separation. Known polymer flocculants can be used as such. The ionicity of the polymer flocculant may be an anion, cation, nonion or amphoteric, and the polymer flocculant may be a liquid type (emulsion type) or a powder type.

  Examples of these polymer flocculants include polyacrylamide polymer flocculants, polyacrylate polymer flocculants, polymethacrylate polymer flocculants, and the like. As the polymer flocculant to be used, the optimum type can be selected depending on the properties of the organic sludge to be treated.

  The addition ratio of the polymer flocculant may be an amount that allows most phosphorous phosphorus contained in the organic sludge to be separated from the sludge separation processing unit and aggregate SS (floating matter) in the sludge, The optimum addition amount is determined depending on the properties of the organic sludge to be treated. For example, it is 1.0% by weight to 3.0% by weight, preferably 1.5% by weight to 2.5% by weight, based on the solid matter dry amount (DS) in the organic sludge.

  In the sludge separation treatment step, the liquid component is separated from the organic sludge mixed with the polymer flocculant in the mixing treatment step.

  The screen used in the sludge separation process is not particularly limited as long as it can reduce the volume of organic sludge by dehydrating the organic sludge in the dewatering section and is less likely to clog. And a known screen can be used.

  Examples of screens that can be used include known screens such as wedge wire screens, rotary screens, and honeycomb screens. The opening of the screen is about 0.5 mm to 1.0 mm. It is also possible to use a concentration unit incorporating a known screen.

  In the dehydration process, an inorganic flocculant is added to the concentrated sludge separated in the sludge separation process and dehydrated. The inorganic flocculant aggregates SS in organic sludge in the same manner as the polymer flocculant. The reason why the inorganic flocculant is added in the present embodiment is that it is added to the concentrated sludge concentrated by the polymer flocculant to make the floc stronger and more easily dewatered. By adding an inorganic flocculant to the concentrated sludge, the dehydration treatment can be facilitated.

  The inorganic flocculant that can be used is not particularly limited as long as it exhibits the above-described function, and a known inorganic flocculant can be used. For example, ferric chloride, aluminum sulfate, aluminum chloride, polyaluminum chloride, ferric sulfate, polyiron sulfate, polyferric sulfate, polyferric chloride and the like are preferable, preferably polyferric sulfate. is there.

  The amount of the inorganic flocculant added varies depending on the nature of the concentrated sludge, and also varies depending on the type of inorganic flocculant used. What is necessary is just to add about 2.0 weight%-7.0 weight% with respect to the solid substance dry amount (DS) in concentrated sludge, Preferably about 5.0 weight% is added.

  As a device for dewatering the concentrated sludge to which the inorganic flocculant is added in the dehydration treatment step, a known dewatering separation device can be used. For example, a screw press dehydrator, a belt press dehydrator, a centrifugal dehydrator and the like. The dewatered sludge dehydrated in the dehydration process can be reused as a combustion aid.

  The dehydrated liquid generated in the dehydration process is returned to the acceptance processing unit 2. The dehydrating liquid contains an inorganic flocculant added in the dehydration process. As described above, when the inorganic flocculant is returned to the mixing unit 5, the dehydrating liquid containing the inorganic flocculant is supplied to the phosphorus recovery step, and the phosphorus recovery rate is reduced. On the other hand, when the dehydrating liquid containing the inorganic flocculant is returned to the acceptance processing unit 2, the inorganic flocculant reacts with a substance causing odor such as hydrogen sulfide contained in the organic sludge to reduce the bad odor, It has the effect that the recovery processing efficiency of phosphorus does not decrease.

  The return mechanism 14 that returns the dehydrated liquid generated in the dehydration process to the sludge receiving unit is not particularly limited as long as it can transfer the liquid component, and a known transfer mechanism can be used. The return mechanism is, for example, a pipe or a pipe provided with a forced transfer device such as a pump.

  In the biological treatment process, the separation liquid separated in the above-described sludge separation treatment process is biologically treated as a biological treatment liquid. The biological treatment process includes a nitrification / denitrification process in which ammonia in the biological treatment liquid is converted into nitric acid by nitrifying bacteria and nitric acid is converted into nitrogen gas by denitrifying bacteria, and a membrane that separates the processed liquid after treatment. A separation step is included. For the biological treatment process, a known method for biological treatment may be used. In the biological treatment process, only a part of phosphorus is used for microbial cell synthesis, and a high phosphorus concentration separation liquid can be obtained. A biological treatment process employing a high-load (membrane separation) denitrification system has less ammonia and impurities, and is a suitable mode for recovering phosphoric acid using the HAP method.

In the present embodiment, phosphorus is recovered using the HAP method, which is one of the crystallization methods, in the phosphorus recovery step. In the HAP method, HAP (hydroxyapatite) is recovered from the biological treatment liquid. HAP is a complex of calcium phosphate and calcium hydroxide, and is basic calcium phosphate represented by the chemical formula Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ .

In the HAP method, HAP is added to the surface of the seed crystal from a phosphoric acid solution which is supersaturated by adding a calcium ion source to phosphate phosphorus (PO ₄ ³⁻ ) in a biological treatment liquid and further adjusting the pH. To crystallize.

  As a source of calcium ions that can be added, any ionic substance may be used as long as the cation is composed of calcium. For example, calcium salts such as calcium chloride, slaked lime (calcium hydroxide), calcium nitrate, etc. A single substance or a plurality of substances selected from any one are preferably used.

  What is necessary is just to use the compound which has a hydroxyl group as a pH adjuster. For example, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alkaline earth metal hydroxides such as calcium hydroxide, and the like can be used. When calcium hydroxide is used as the calcium ion source, both functions of the calcium ion source and the pH adjuster can be achieved.

  Since the HAP method is used in the phosphorus recovery step of the present embodiment, the phosphorus recovery is performed by extracting a part of the crystal crystallized on the surface of the seed crystal from the phosphorus recovery processing unit 10. The remaining crystals are used as seed crystals in the next reaction in the phosphorus recovery processing unit 10. In the phosphorus recovery process of the present embodiment, when the phosphorus concentration in the biological treatment liquid becomes 20 mg / L or less, the amount of chemicals for recovery decreases. In order to recover phosphorus with a high yield, the phosphorus recovery step may be performed so that the phosphorus concentration in the biological treatment liquid after the phosphorus recovery step is 15 mg / L or more. For example, the recovery rate of phosphorus from a biological treatment solution having a phosphorus concentration of 50 mg / L is 70%, and the recovery rate of phosphorus from a biological treatment solution having a phosphorus concentration of 100 mg / L is 85%.

  The phosphorus recovered by the HAP method contains about 30% soluble phosphoric acid. Moreover, since a phosphorus collection | recovery process is performed using the to-be-biologically processed liquid in which the biological treatment was performed, the obtained HAP has no odor and is hygienic. The diameter of the collected HAP is several tens of μm, and dehydration may be performed as necessary.

  The biological treatment liquid from which phosphorus has been collected contains about 15 mg / L to 20 mg / L of phosphorus. In the aggregation treatment step, an inorganic flocculant is added to the biological treatment liquid from which phosphorus has been collected, and the remaining phosphorus is agglomerated. By this treatment, phosphorus (TP) can be set to a very small concentration of 1.0 mg / L or less.

  As the inorganic flocculant used in the flocculation treatment step, the same inorganic flocculant as the above-mentioned inorganic flocculant can be used. The separation liquid that has been subjected to the aggregation treatment is subjected to solid-liquid separation by membrane separation or the like, and the aggregate is separated. The separated aggregate contains an inorganic flocculant. The separated aggregate and the inorganic flocculant contained in the aggregate can be returned to the sludge receiving unit 2 via the inorganic aggregate return mechanism 14. By returning the separated agglomerates to the sludge receiving unit 2, not only a separate processing facility for treating the agglomerates is required, but also the inorganic aggregating agent contained in the separated agglomerates causes The bad odor of organic sludge is effectively suppressed without inhibiting the phosphorus recovery process.

  In the advanced treatment / disinfection treatment process, COD, colored substances, and the like contained in the liquid to be treated after the aggregation treatment process are removed. The advanced treatment / disinfection treatment step is performed, for example, by introducing the liquid to be treated into an activated carbon adsorption tower or the like. The liquid to be treated that has undergone the advanced treatment / disinfection treatment process is discharged.

(Second Embodiment)
Hereinafter, another phosphorus recovery facility and phosphorus recovery method according to the present invention will be described.
FIG. 3 is an explanatory diagram of the phosphorus recovery facility according to the second embodiment of the present invention, and FIG. 4 is a flowchart of the phosphorus recovery method according to the second embodiment of the present invention. The present embodiment is different from the first embodiment in that the aggregation processing is performed in the aggregation processing step, and the separated aggregate is returned to the dehydration processing unit 7 via the inorganic aggregate return mechanism 14. In the following description, only portions different from the first embodiment will be described.

  In the flocculation process, an inorganic flocculating agent is added to perform the flocculation process. In order to obtain a sufficient aggregating effect, the inorganic aggregating agent is added in an amount more than necessary. By returning the agglomerate obtained in the agglomeration treatment step to the dehydration processing unit 7 via the inorganic agglomerate return mechanism 14, the amount of the inorganic flocculant added in the dehydration treatment unit 7 can be reduced. .

  In addition, the aggregate returned via the inorganic aggregate return mechanism 14 is collected and reused together with the dewatered sludge. On the other hand, since the liquid after the dehydration process is returned to the sludge receiving part via the return mechanism 13, the inorganic flocculant reacts with a substance causing odor such as hydrogen sulfide contained in the organic sludge to cause bad odor. As well as the effect that the phosphorus recovery efficiency does not decrease.

(Third embodiment)
Hereinafter, another phosphorus recovery facility and phosphorus recovery method according to the present invention will be described.
FIG. 5 shows an explanatory diagram of the phosphorus recovery facility according to the third embodiment of the present invention, and FIG. 6 shows a flow chart of the phosphorus recovery method according to the third embodiment of the present invention. In the present embodiment, the MAP method is used as the phosphorus recovery method. For this reason, the biological treatment part 9 which collect | recovers phosphorus by the phosphorus collection | recovery process part 10 using the separated liquid isolate | separated by the sludge separation process part 6, and biologically processes the separated liquid from which phosphorus was collect | recovered as a to-be-treated liquid. This is different from the first embodiment. In the following description, only portions different from the first embodiment will be described.

In the present embodiment, phosphorus is recovered using the MAP method, which is one of the crystallization methods, in the phosphorus recovery step. In the MAP method, MAP (magnesium ammonium phosphate) is recovered from the liquid to be treated. MAP is represented by the chemical formula MgNH ₄ PO ₄ .

In the MAP method, in the state where phosphate phosphorus (PO ₄ ³⁻ ) and ammonia coexist, a magnesium ion source is added, and the pH is adjusted to obtain MAP from nitrogen and phosphorus to obtain the surface of the seed crystal. Crystallize. In the MAP method, it is essential that ammonia ions exist. In the present embodiment, since ammonia ions are present in the organic sludge, the step of adding ammonia can be omitted. Moreover, when there is little content of ammonia in organic sludge, ammonia may be added.

  As the magnesium ion source that can be added, any ionic substance may be used as long as the cation is composed of magnesium. For example, the magnesium ion source may be any one of magnesium salts such as magnesium chloride, magnesium hydroxide, and magnesium nitrate. A single substance or a plurality of selected substances are preferably used.

  What is necessary is just to use the compound which has a hydroxyl group as a pH adjuster. For example, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alkaline earth metal hydroxides such as magnesium hydroxide, and the like can be used. In addition, when magnesium hydroxide is used as the magnesium ion source, both functions of the magnesium ion source and the pH adjuster can be achieved.

  Since the MAP method is used in the phosphorus recovery process of the present embodiment, the phosphorus recovery is performed by extracting a part of the crystal crystallized on the surface of the seed crystal from the phosphorus recovery processing unit 10. The remaining crystals are used as seed crystals in the next reaction in the phosphorus recovery processing unit 10. In the phosphorus recovery process of the present embodiment, the amount of phosphorus recovered is the phosphorus concentration in the liquid to be treated after the phosphorus recovery process and the phosphorus concentration in the separated liquid separated by the sludge separation processing unit, as in the first embodiment. It can be determined as appropriate based on the above.

  The diameter of phosphorus (MAP) recovered by the MAP method is in mm units, and dehydration can be performed with a screen. MAP contains three major elements of fertilizer, phosphorus and nitrogen, and the essential element magnesium. It can be used alone as a fertilizer.

  In addition, since ammonia is required in the MAP method, human waste or septic tank sludge is preferably used as the organic sludge. For this reason, odor and hygiene measures are required.

  In the biological treatment process, the separation liquid treated in the above-described phosphorus recovery process is biologically treated as a biological treatment liquid. In the biological treatment process, the nitrification bacteria removes ammonia that has not been consumed in the phosphorus recovery process in the biological treatment liquid by nitrifying bacteria, and denitrifying bacteria converts nitric acid to nitrogen gas. It consists of a membrane separation step for membrane separation of biological treatment liquid. For the biological treatment process, a known method for biological treatment may be used. It is desirable to perform a biological treatment process employing a high load (membrane separation) denitrification system.

(Fourth embodiment)
Hereinafter, another phosphorus recovery facility and phosphorus recovery method according to the present invention will be described.
FIG. 7 is an explanatory diagram of the phosphorus recovery facility according to the fourth embodiment of the present invention, and FIG. 8 is a flowchart of the phosphorus recovery method according to the fourth embodiment of the present invention. In the present embodiment, the MAP method is used as the phosphorus recovery method, and the phosphorus recovered by the phosphorus recovery processing unit 10 is recovered using the separation liquid separated by the sludge separation processing unit 6. The point that the biological treatment part 9 which performs biological treatment as a biological treatment liquid is provided is the same as that of Embodiment 3. Moreover, the structure which returns the aggregate aggregated by the aggregation process part 11 to the dehydration process part 7 via an inorganic-type aggregate return mechanism is the same as that of Embodiment 2.

(Other embodiments)
In the above-described embodiment, the inorganic aggregate return mechanism is configured to return the aggregate aggregated by the aggregation processing unit 11 to the sludge receiving unit, or the aggregate aggregated by the aggregation processing unit 11 is dehydrated. Although the structure returned to 7 was demonstrated, you may be comprised so that the aggregate which the aggregation process part 11 performed the aggregation process may be returned to both the sludge receiving part and the dehydration process part 7. FIG.

  In the first to fourth embodiments, phosphorus is recovered using a crystallization method. Other known phosphorus removal methods such as adsorption dephosphorization method that recovers phosphorus from water treatment system using adsorbent, alkali extraction method that recovers calcium phosphate from incinerated ash, or reductive melting method that produces phosphate fertilizer from incinerated ash It is also possible to apply the recovery method to the phosphorus recovery processing unit 10 of each of the above embodiments.

An experimental example will be described below.
(Experimental example 1)
80 ml of urine etc. (BOD: 3,700 mg / l, SS: 5,700 mg / l, TN: 1,300 mg / l) and 10 ml of K facility concentrated sludge (SS: 2,800 mg / l) and water The test sample of Experimental Example 1 was made with 10 mL as a total of 100 mL. The K facility inorganic concentrated sludge used ferric sulfide as an inorganic flocculant and a membrane separation high-load denitrogenation treatment system as a biological treatment.

(Experimental example 2)
80 ml of urine etc. (BOD: 3,700 mg / l, SS: 5,700 mg / l, TN: 1,300 mg / l) and 10 ml of I facility concentrated sludge (SS: 2,400 mg / l) and water The test sample of Experimental Example 2 was created with 10 mL as a total of 100 mL. The K facility inorganic concentrated sludge used ferric sulfide as an inorganic flocculant and a membrane separation high-load denitrogenation treatment system as a biological treatment.

(Experimental example 3)
The test sample of Experimental Example 3 was prepared by bringing the K facility into urine and the like (BOD: 3,700 mg / l, SS: 5,700 mg / l, TN: 1,300 mg / l) 80 mL and water 20 mL as a whole to 100 mL. .

(Phosphoric acid concentration and hydrogen sulfide concentration confirmation test)
Each of Experimental Examples 1 to 3 was placed in a 200 mL vial with 200 mL of the above Experimental Examples 1 to 3, respectively, and sealed at room temperature using a shaker at 50 times / min. . The phosphoric acid concentration and hydrogen sulfide concentration in the liquid were measured immediately after sealing (0 hours) and after shaking for 72 hours. The phosphoric acid concentration was measured using a molybdenum blue absorbance method, and the hydrogen sulfide concentration was measured using a gas chromatographic method. The results are shown in Table 1.

  From Table 1, it can be seen that in Experimental Examples 1 and 2 where the agglomerated aggregate was added to and infiltrated into urine or the like, the phosphoric acid concentration was hardly changed, whereas the hydrogen sulfide concentration was greatly reduced. Recognize. From this result, it was considered that hydrogen sulfide reacted with ferric sulfide to generate iron sulfide (FeS). In Experimental Example 3, the increase in hydrogen sulfide after 72 hours was thought to be due to the reduction reaction of sulfide in human urine by sulfate bacteria contained in human waste.

  The above-described embodiment is one aspect of the present invention, and the present invention is not limited by the description. Specific configurations and control aspects of each part can be appropriately changed and designed within the scope of the effects of the present invention. Needless to say.

1: Phosphorus recovery device 2: Sludge receiving part (receiving tank)
3: Pretreatment part 4: Sludge receiving part (relay tank)
5: Mixing processing unit 6: Sludge separation processing unit 7: Dehydration processing unit 8: Storage unit 9: Biological processing unit 10: Phosphorus recovery processing unit 11: Aggregation processing unit 12: Advanced processing / disinfection equipment 13: Return mechanism 14: Inorganic Aggregate return mechanism

Claims (10)

A sludge receiving portion for receiving organic sludge containing phosphorus; a mixing treatment portion for adding a polymer flocculant to the organic sludge received in the sludge receiving portion; and an organic material mixed in the mixing treatment portion. A sludge recovery facility comprising a sludge separation processing unit for separating liquid from the activated sludge, and a phosphorus recovery processing unit for recovering phosphorus from the separated liquid separated by the sludge separation processing unit,
A dehydration processing unit for adding an inorganic flocculant to the concentrated sludge separated by the sludge separation processing unit and dehydrating;
A return mechanism for returning the dehydrated liquid generated in the dehydration processing unit to the sludge receiving unit;
Phosphorus recovery facility equipped with. An agglomeration processing unit for adding an inorganic flocculant to the separation liquid from which phosphorus is recovered by the phosphorus recovery processing unit;
An inorganic aggregate return mechanism for returning the aggregate subjected to the aggregation treatment in the aggregation treatment section to the sludge receiving section;
The phosphorus collection | recovery installation of Claim 1 provided with. An agglomeration processing unit for adding an inorganic flocculant to the separation liquid from which phosphorus is recovered by the phosphorus recovery processing unit;
An inorganic aggregate return mechanism for returning the aggregate that has been agglomerated in the agglomeration unit to the dehydration unit;
The phosphorus collection | recovery installation of Claim 1 provided with.   The phosphorus recovery processing unit according to any one of claims 1 to 3, wherein the phosphorus recovery processing unit is configured to recover phosphorus from the separated liquid separated by the sludge separation processing unit based on a HAP method or a MAP method. Facility.   A biological treatment unit that biologically treats the separation liquid separated by the sludge separation treatment unit, and the phosphorus recovery treatment unit collects phosphorus from the biological treatment liquid biologically treated by the biological treatment unit based on the HAP method The phosphorus collection | recovery equipment in any one of Claim 1 to 3 comprised so that it may do.   The phosphorus recovery facility according to any one of claims 1 to 5, wherein the organic sludge containing phosphorus is human waste and / or septic tank sludge. Mixing in the sludge receiving step for receiving organic sludge containing phosphorus in the sludge receiving portion, a mixing treatment step for adding a polymer flocculant to the organic sludge received in the sludge receiving portion, and mixing in the mixing treatment step It is a phosphorus recovery method comprising: a sludge separation treatment step for separating a liquid component from a treated organic sludge; and a phosphorus recovery treatment step for collecting phosphorus from the separated liquid separated in the sludge separation treatment step. ,
A dehydration process for adding an inorganic flocculant to the dewatering process part to the concentrated sludge separated in the sludge separation process process, and a returning process for returning the dehydrated liquid generated in the dehydration process process to the sludge receiving part; A phosphorus recovery method comprising:   A coagulation treatment step of adding an inorganic coagulant to the separation liquid from which phosphorus has been collected in the phosphorus collection treatment step, and an inorganic aggregate return step of returning the aggregate coagulated in the coagulation treatment step to the sludge receiving part. And a phosphorus recovery method according to claim 7.   An aggregation treatment step of adding an inorganic flocculant to the separation liquid from which phosphorus has been collected in the phosphorus collection treatment step, and an inorganic aggregate return step of returning the aggregate subjected to the aggregation treatment in the aggregation treatment step to the dehydration processing unit And a phosphorus recovery method according to claim 7. A biological treatment step for biologically treating the separation liquid separated in the sludge separation treatment step, wherein the phosphorus recovery treatment step recovers phosphorus from the biological treatment liquid biologically treated in the biological treatment step based on the HAP method; The method for recovering phosphorus according to any one of claims 7 to 9, which is a step of performing.

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