JP5172882B2 - Water treatment equipment - Google Patents

Description

  The present invention relates to a water treatment apparatus for recovering phosphorus contained in water to be treated. In particular, the present invention is used for sewage containing organic pollutants, industrial wastewater treatment of food processing plants, etc. The present invention relates to a water treatment apparatus for recovering phosphorus contained in water to be treated in a water treatment apparatus discharged from a treatment process of organic waste liquid and sludge discharged from biological wastewater treatment.

  Currently, it is predicted that there will be a future depletion of phosphorus resources in the world, and the technology for recovering phosphorus in wastewater is attracting attention due to domestic circumstances that depend on imports to secure phosphorus resources. Until now, phosphorus present in the form of phosphate ions in wastewater has been considered to be essential for removal and management of the state of discharge because it contributes to eutrophication of the environment. . For this reason, conventionally, the most emphasis has been on removing phosphorus from wastewater. As a typical phosphorus removal technique, there are a biological phosphorus removal method using the phosphorus accumulation ability of microorganisms, and a phosphorus removal method by an aggregation precipitation method.

  In order to use these phosphorus removal methods as direct phosphorus recovery and utilization means, for example, a process such as incineration and chemical treatment of surplus sludge generated from biological phosphorus removal methods is required. It is necessary to arrange processing steps. For example, in order to reuse phosphorus as a resource, it is necessary to eliminate the influence of impurities contained in chemicals to be used, derived sludge, and the like, so that adjustment and purification steps are required. In view of these circumstances, attention has been drawn to water treatment technology for selectively recovering phosphorus from wastewater from the treatment process of surplus sludge discharged from biological phosphorus removal and food wastewater containing phosphorus in high concentration. Yes. Among them, in the wastewater containing ammonia nitrogen in addition to phosphorus, regarding the application of the MAP method, phosphorus is taken out as magnesium ammonium phosphate (MAP) which is a phosphate crystal generated by addition of a magnesium salt or the like. Many methods have been proposed.

  Most of the phosphorus recovery technology by this MAP method is that water to be treated and MAP generation source are introduced into a complete mixing tank represented by a fluidized bed using agitation by gas introduction of MAP particles from wastewater containing ammonia nitrogen and phosphorus. Introducing magnesium-containing water derived from the magnesium salt and pH-adjusted water to promote MAP generation, but it is not possible to suppress MAP microparticle generation, and a recovery and circulation mechanism for MAP microparticles discharged from the MAP generation system Measures were taken to increase the phosphorus recovery rate by installing it.

  Patent Documents 1 to 3 are examples of a phosphorus recovery system that circulates and uses a part of treated water proposed to solve this problem.

  In Patent Document 1, a liquid discharged from the primary reaction tank is introduced into the secondary reaction tank using two reaction tanks, and at the same time, a magnesium source and an alkali component which are chemical liquids and, in some cases, water to be treated. It is described that the MAP particle-containing slurry obtained in the secondary reaction tank and the water to be treated are introduced into the upward reaction type primary reaction tank after being introduced and subjected to MAP crystallization reaction.

  In Patent Document 2, in a plug flow reactor filled with MAP particles without aeration, an inlet for phosphorus-containing water is provided at the bottom of the reactor, and at least one of magnesium salt, alkali agent and ammonia is added to the MAP packed bed. A plurality of phosphorus recovery systems arranged at different height positions are described. In the examples, treated water discharged from the reactor is circulated and introduced into the lower part of the reactor, and after premixing with raw water mixed with magnesium salt It is described that it is introduced into a MAP particle packed bed and passed through an alkali agent and a supply part.

  Patent Document 3 describes a phosphorus recovery system that controls the circulation flow rate according to the phosphorus concentration of raw water and circulating water in a dephosphorization apparatus that introduces part of the treated water of the MAP reaction tower to the lower part of the reaction tower, In the examples, a supply part of magnesium salt, ammonium salt and alkaline agent to the MAP reaction column is described.

Japanese Patent No. 4004725 Japanese Patent No. 3271556 Japanese Patent No. 4186251

  However, in the water treatment apparatus of Patent Document 1, a supersaturated region is generated in the secondary reaction tank by ionic phosphorus remaining in the treated water of the primary reaction tank and injection of a chemical solution such as magnesium, and phosphorus in the treated water is generated. MAP is crystallized, and the crystal is returned from the secondary reaction tank to the primary reaction tank. At that time, the MAP crystal is formed by adjusting the supersaturation degree to the MAP nucleation zone in the secondary reaction tank. Since ionic phosphorus is consumed for nucleation and crystal nucleus growth, the ionic phosphorus remaining in the treated water is used for growth of MAP crystals that are retained in the primary reaction tank and drawn out from the treatment system as a phosphorus recovery product. Cannot be used effectively. Moreover, in this conventional apparatus, in order to add an alkali component in a secondary reaction tank, when arranging the next process which purifies the treated water discharged | emitted from a secondary reaction tank, the pH of treated water according to the next process Adjustment is required again.

  Moreover, in the water treatment apparatus of patent document 2, the ionic phosphorus in treated water and raw | natural water in the dephosphorization apparatus by circulation utilization of the illustrated treated water is introduce | transduced in steps in a MAP packed bed. The effect of being consumed for MAP crystallization is expected by adjusting the supersaturation to the growth region of the MAP crystal by the pH adjuster. However, the ionic phosphorus concentration in the raw water is higher than the ionic phosphorus concentration in the treated water, and the effect of diluting the ionic phosphorus concentration in the treated water is stable in the raw water and the treated water. However, when the phosphorus concentration in the raw water or the treated water increases, it becomes difficult to obtain the supersaturation adjusting effect due to the dilution effect.

  Moreover, in the water treatment apparatus of patent document 3, in the dephosphorization apparatus by the circulation utilization of the illustrated treated water, under the pretreatment of the raw water and the treated water and under the control of the treated water circulation water quantity by measuring the phosphorus concentration of the premixed water However, since the chemical solution introduced into the lower part of the reaction column and the premixed water merge at a time, the degree of supersaturation increases significantly at the contact portion with the chemical solution, and MAP nucleation occurs. Is promoted, and the production of fine MAP crystals is promoted.

  The present invention has been made to solve the above-mentioned problems, and can appropriately promote the MAP crystal growth of phosphate ions in the water to be treated and efficiently recover phosphorus from the water to be treated. The purpose is to provide.

  The water treatment apparatus according to the present invention includes a phosphorus recovery reactor that reacts magnesium with the raw water to generate magnesium ammonium phosphate to recover phosphorus from the raw water containing ammoniacal nitrogen and phosphate ions, An additive injection line for injecting an additive into an additive injection part in the phosphorus recovery reactor, and an upward flow of raw water into the raw water introduction part located above the additive injection part in the phosphorus recovery reactor A raw water introduction line to be introduced, and a pH adjustment source supplier that supplies a pH adjuster as the additive and a magnesium source supplier that supplies a magnesium source as the additive. And a stirrer provided in the additive injection line for stirring and mixing the additive and the treated water, and from the phosphorus recovery reactor. A treated water line through which the treated water flows, and branched from the treated water line and connected to the additive injection line, and a part of the treated water together with the additive is added to the phosphorus via the additive injected line. And a first treated water reflux line for refluxing the recovery reactor so as to have an upward flow.

  In the present invention, by mixing the treated water from the first treated water reflux line with the additive solution of the additive injection line, the additive solution is diluted to lower the additive concentration, and changes depending on the addition of the additive. In order to suppress the rapid increase in MAP supersaturation and to suppress the formation of new MAP fine particles, that is, to suppress nucleation, the decrease in MAP retention capacity in the MAP reactor accompanying the formation of new MAP fine particles leads to an increase in phosphorus recovery rate. Reduction is suppressed.

  Furthermore, in the present invention, a branch from the treated water line is connected to the raw water introduction line, and a part of the treated water is located above the additive injection part through the raw water introduction line together with the raw water. The raw water introduction part can further have a second treated water reflux line for refluxing to be an upward flow.

  In the present invention, by mixing the treated water from the second treated water reflux line with the raw water in the raw water introduction line, the raw water is diluted to lower the phosphorus concentration, and the raw water having a lowered phosphorus concentration is introduced into the reactor. Then, in the state where excessive increase in MAP supersaturation is suppressed, the MAP particles are brought into contact with the MAP particles held in the reactor, and phosphorus is consumed for the growth of the MAP particles. Reduction in recovery rate is suppressed.

  According to the water treatment device of the present invention, by mixing treated water from the first treated water reflux line with the additive solution of the additive injection line, the additive solution is diluted to lower the additive concentration, and MAP A rapid increase in the degree of supersaturation is suppressed. This suppresses the formation of new MAP microparticles, that is, nucleation, reduces the MAP retention capacity in the MAP reactor accompanying the formation of new MAP microparticles, and appropriately promotes MAP crystal growth of phosphate ions in raw water As a result, phosphorus can be efficiently recovered from raw water.

The block diagram which shows the water treatment apparatus which concerns on the 1st Embodiment of this invention. The cross-sectional top view which shows the raw | natural water introduction pipe | tube for notching a MAP reactor and introducing raw | natural water into a raw | natural water introduction part so that it may flow upwards. The cross-sectional top view which shows another raw | natural water introduction pipe | tube as a modification. The block diagram which shows the water treatment apparatus which concerns on the 2nd Embodiment of this invention. The block diagram which shows the water treatment apparatus which concerns on the 3rd Embodiment of this invention. The block diagram which shows the water treatment apparatus which concerns on the 4th Embodiment of this invention.

  (1) The water treatment apparatus of the present invention comprises a phosphorus recovery reactor for reacting magnesium with the raw water to produce magnesium ammonium phosphate to recover phosphorus from the raw water containing ammoniacal nitrogen and phosphate ions. The raw water is directed upward into the additive injection line for injecting the additive into the additive injection part in the phosphorus recovery reactor and the raw water introduction part located above the additive injection part in the phosphorus recovery reactor. A raw water introduction line that introduces the liquid into a stream, a pH adjustment source supplier that supplies a pH adjuster as the additive, and a magnesium source supplier that supplies a magnesium source as the additive From the phosphorus recovery reactor, and a stirrer provided in the additive injection line for stirring and mixing the additive and the treated water. A treated water line through which the treated water comes, branched from the treated water line and connected to the additive injection line, and a part of the treated water together with the additive through the additive injected line And a first treated water reflux line for refluxing the phosphorus recovery reactor so as to have an upward flow.

  In the present invention, the first treated water recirculation line is joined to the additive injection line, so that treated water having a low phosphorus concentration is introduced into the local high additive concentration region (additive injection portion), and the high concentration addition is performed. A rapid increase in the degree of MAP supersaturation that changes due to the injection of the agent is suppressed. That is, according to the present invention, by mixing treated water from the first treated water reflux line with the additive solution of the additive injection line, the additive solution is diluted to lower the additive concentration, and the MAP supersaturation degree is reduced. Rapid increase is suppressed. This suppresses the formation of new MAP fine particles, that is, nucleation, and reduces the MAP retention capacity in the MAP reactor accompanying the formation of new MAP fine particles, and as a result, the decrease in phosphorus recovery rate is suppressed.

  (2) In the above (1), the raw water introduction part branched from the treated water line and connected to the raw water introduction line, and a part of the treated water is located above the additive injection part with the raw water through the raw water introduction line It is preferable to further have a second treated water reflux line for refluxing so as to have an upward flow.

  According to the present invention, by mixing the treated water from the second treated water reflux line with the raw water in the raw water introduction line, the raw water is diluted to lower the phosphorus concentration, and the raw water having the lowered phosphorus concentration is put into the reactor. When introduced, it is in contact with the MAP particles held in the reactor while suppressing an excessive increase in MAP supersaturation, and phosphorus is consumed for the growth of the MAP particles, thereby suppressing the formation of new MAP fine particles. , The decrease in phosphorus recovery rate is suppressed.

  (3) In the above (1) or (2), it is preferable to have a plurality of raw water introduction lines (FIGS. 2 and 3). When raw water is introduced into a plurality of locations of the raw water introduction section via a plurality of raw water introduction lines, the raw water is uniformly dispersed in the phosphorus recovery reactor, and local MAP supersaturation in the MAP reactor is suppressed, Formation of new MAP fine particles is suppressed, and a decrease in phosphorus recovery rate is effectively suppressed.

  (4) In the above (1) to (3), the treated water that is provided on the treated water line and that stores the treated water, and the treated water that is provided between the reservoir and the raw water introduction line and is stored in the reservoir. It is preferable to further have a storage tank water return line that returns the water to the phosphorus recovery reactor via the raw water introduction line (FIG. 4).

  In the present invention, by returning the storage tank water (treated water) to the raw water introduction line, the amount of treated water mixed with the raw water is further increased to dilute the raw water, and the raw water introduction section in the reactor passes through the raw water introduction line. The phosphorus concentration of the treated water introduced into the water decreases. In the MAP reactor circulation reaction system of the treated water, the raw water having a lowered phosphorus concentration causes the high concentration of phosphorus in the treated water introduced into the MAP reactor when the phosphorus concentration in the raw water is high. Local MAP supersaturation in the MAP reactor is suppressed, and formation of MAP fine particles due to MAP nucleation and a decrease in phosphorus recovery ability due to outflow are suppressed.

  (5) In the above (1) to (4), a pH measurement device that is provided in the additive injection line downstream of the stirring device and measures the pH of the fluid flowing through the additive injection line, and the pH measurement And a control device for controlling the magnesium source supplier based on the pH measurement result from the device. In the present invention, when a pH change in the system is caused by the magnesium source to be used, the magnesium source can be supplied without excess or deficiency by monitoring and controlling the magnesium concentration introduced into the system, and MAP of phosphorus derived from raw water Appropriate operation of phosphorus recovery by particle growth.

  (6) In the above (1) to (4), a pH measurement device that is provided in the additive injection line downstream of the stirring device and measures the pH of the fluid flowing through the additive injection line; and a control device for controlling the pH adjuster feeder based on the pH measurement result. In the present invention, the pH adjusting agent can be supplied without excess and deficiency, and phosphorus recovery by growth of MAP particles of phosphorus derived from raw water can be appropriately operated.

(7) In the above (1) to (6),
It is preferable to further have a biological treatment tank that is connected to the phosphorus recovery reactor via the treated water line and performs biological water treatment. In the present invention, it is possible to appropriately purify ammonia nitrogen remaining in the treated water after recovery of phosphorus by MAP growth from wastewater containing ammonia nitrogen, BOD components, and the like.

  (8) In said (1)-(7), it is preferable that a biological treatment tank has a film | membrane which performs a membrane separation activated sludge process. In the present invention, by using a membrane activated sludge process in the biological water treatment process disposed downstream of the treated water for MAP phosphorus recovery, the biological water treatment process can be made compact, and the MAP reaction as the previous stage can be achieved. Since the ability to form MAP in the wastewater is reduced by the phosphorus recovery in the vessel, water purification that suppresses blockage due to inorganic salt generation at the membrane separation portion can be performed.

  (9) In the above (1) to (8), it is preferable to further have a solid-liquid separator and an anaerobic digester upstream of the phosphorus recovery reactor. As an advantage of installing the solid-liquid separation device on the upstream side, mixing of solid impurities into MAP, which is phosphorus crystals recovered in the phosphorus recovery reactor, is suppressed. In addition, as an advantage of installing an anaerobic digester on the upstream side, water purification can be performed along with biogas generation from the BOD component flowing into the treatment system, so that the BOD component contained in the wastewater can be recycled, Phosphorus recovery and recycling can be achieved by MAP, and further, both water purification and recycling of valuable resources in drainage can be achieved by consuming and removing part of the nitrogen content in the drainage for MAP formation.

  (10) In the above (9), the anaerobic digester is preferably an upward flow type anaerobic sludge bed (UASB) type methane fermentation tank. In the present invention, a UASB type methane fermenter is installed as an anaerobic digester in the upstream (upstream side) of the phosphorus recovery reactor, thereby purifying the raw water at a high speed and at the same time purifying the raw water for a long time. By suppressing the production and accumulation of MAP particles in the inside, phosphorus can be efficiently and appropriately recovered in the MAP reaction tank. Incidentally, in a water treatment apparatus having no UASB type methane fermenter, it took a long time, for example, about 20 to 30 days to process one batch, but the anaerobic digester having the UASB type methane fermenter of the present invention. Then, this processing time can be greatly shortened to several hours to several days.

  Hereinafter, various embodiments for carrying out the present invention will be described with reference to the accompanying drawings.

(First embodiment)
A first embodiment of the present invention will be described with reference to FIG.

  The water treatment apparatus 1 of the present embodiment includes a raw water tank 2, a solid-liquid separation apparatus 3, a UASB type methane fermentation tank 4 as an anaerobic digestion tank, a MAP reactor 5 as a phosphorus recovery reactor, and a biological treatment in order from the upstream side. A tank 6 and a membrane separation tank 7 are provided, and these devices are connected approximately in series by piping lines L1 to L6 including accessory parts such as pumps and / or valves and / or various measuring instruments. The entire system of the water treatment apparatus 1 of the present embodiment is controlled comprehensively by a controller (not shown). The raw water to be treated is sent out from the upstream raw water tank 2 and subjected to various purification treatments up to the downstream membrane separation tank 7 to become clean treated water that satisfies a predetermined water quality standard. Released to the ocean. Furthermore, the water treatment apparatus 1 includes a pH adjuster solution supplier 8 that supplies a pH adjuster solution as an additive to a line L50 for injecting the additive into the lower part of the MAP reactor 5, and an additive to the line L50. And a magnesium source supplier 9 for supplying a solution containing magnesium salt or magnesium ion.

  The raw water tank 2 stores wastewater containing ammonia nitrogen and phosphate ions discharged from factories such as food, oil production, iron making, machinery, metal, and fiber. Raw water made up of such industrial wastewater contains a considerable amount of solids. The raw water tank 2 is connected to the upper inlet of the solid-liquid separator 3 by a piping line L1 having a pump P1, and the solid content in the raw water is removed by the solid-liquid separator 3.

  The solid-liquid separation device 3 is not limited to a specific type of device as long as it has a function capable of removing the solid content from the raw water up to the solid content concentration required in the subsequent wastewater treatment process. . For example, the solid-liquid separation device 3 may be a precipitation tank (thickener) that settles solids in the presence of a flocculant, or forms a swirling flow of water to be treated and centrifuges the solids from the liquid. A solid-liquid separator (cyclone) may be used.

  The drain of the solid-liquid separator 3 is connected to the methane fermentation tank 4 through a line L2 having a pump P2, and raw water with a small amount of solids from the solid-liquid separator 3 is driven through the line L2 by driving the pump P2. It is supplied to the tank 4.

  The methane fermentation tank 4 holds the methane fermentation bacteria inside in order to cause the solid-liquid separated water discharged from the solid-liquid separator 3 to undergo a methane fermentation reaction. The methane fermentation tank 4 has a circulation line L31 that circulates the contents in the piping in order to promote the internal fermentation reaction. This circulation line L31 branches from the fermentation treated water discharge line L3, which is the main flow path, at the three-way valve V1 disposed on the downstream side of the pump P3, and further communicates with the bottom of the methane fermentation tank 4. On the other hand, a biogas discharge line L32 is provided in the upper part of the methane fermentation tank 4, and biogas (methane gas or the like) generated by the fermentation reaction is discharged from the methane fermentation tank 4 to the biogas recovery container (not shown) through the line L32. It has become so.

  Here, the water to be treated can be purified at high speed by using an anaerobic digester, particularly a UASB type methane reactor, for the methane fermentation tank 4. Furthermore, it is possible to contribute to appropriately recovering phosphorus in the MAP reactor 5 by suppressing the MAP particle production and accumulation in the pre-stage tank 4 of the MAP reactor 5 due to a long stay of the water to be treated. In addition, you may make it attach a heating apparatus, a pH adjuster, etc. to the methane fermentation tank 4 as needed.

  As described above, in the fermented water discharge line L3, one branch channel of the three-way valve V1 communicates with the circulation line L31 on the methane fermentation tank 4 side, and the other branch channel of the three-way valve V1 is on the MAP reactor 5 side. Are connected to the circulation lines L52 and L4. That is, the fermented treated water discharge line L3 meets the second treated water recirculation line L52, and the two lines L3 and L52 that have met are unified into the raw water introduction line L4. L4 passes through the side wall of the MAP reactor 5, and a dispersion introduction pipe 51 at the tip thereof is led to an internal raw water introduction portion 55.

  Next, the dispersion introduction pipes 51 and 51A of various forms for introducing the water to be treated into the raw water introduction section 55 in the reactor will be described with reference to FIGS.

  The dispersion introduction pipe 51 of the form shown in FIG. 2 is disposed so that two straight raw water introduction pipes 51 respectively communicating with the raw water introduction line L4 are orthogonal to each other. The end of each raw water introduction pipe 51 is closed by a blind plate. A plurality of holes 52 are opened above each raw water introduction pipe 51. The water to be treated is ejected upward from the plurality of holes 52, and an upward flow toward the upper discharge port communicating with the discharge line L5 is formed.

  In the raw water introduction part 55 in the reactor, the dispersion introduction pipe 51A of the form shown in FIG. 3 is arranged oppositely so that two T-shaped raw water introduction pipes 51A respectively communicating with the raw water introduction line L4 face each other. Yes. A plurality of holes 52A are opened in the upper part of each raw water introduction pipe 51A. From the plurality of holes 52A, the water to be treated is ejected upward, and an upward flow toward the upper discharge port communicating with the discharge line L5 is formed.

  The MAP reactor 5 is a reactor that is derived from raw water or methane fermentation treated water, grows MAP particles by reaction from a liquid containing ammoniacal nitrogen and phosphate ions, and recovers phosphorus in the form of MAP particles. . Mixed dilution water is introduced into the MAP reactor 5 through the above-described raw water introduction line L4 (methane fermentation treated water + phosphorus recovery treated water) into the raw water introduction section 55, and additive through the additive injection line L50. Is injected into the lower part 56 of the reactor. Further, a MAP discharge line L53 having an on-off valve V5 is connected to the bottom of the MAP reactor 5. Furthermore, the phosphorus-recovered treated water after the phosphorus is recovered by the MAP reaction through the treated water discharge line L5 is discharged from the MAP reactor 5. Here, the raw water introduction line L4 communicates with the interior of the MAP reactor 5 above the additive injection line L50. The additive injection line L50 communicates with the lower part of the MAP reactor 5, and a predetermined additive solution is injected into the MAP reactor 5 from the additive supply sources 8 and 9 through the line L50. Yes. The additive injected from the additive injection line L50 rises in the MAP reactor 5 and encounters the upward flow of water to be treated introduced from the dispersion introduction pipe 55 of the raw water introduction line L4. It has come to be.

  Two stirrers 81 and 91 are provided in the additive injection line L50. One stirrer 81 is connected to a line L8 connected to the pH adjuster supply source 8, and the other stirrer 91 is connected to a line L9 connected to the magnesium source supply source 9. The supply lines L8 and L9 have pumps P8 and P9, respectively, and a desired pH adjuster solution is supplied from the pH adjuster supply source 8 to the stirrer 81 of the additive injection line L50 by driving the pump P8. The desired magnesium-containing solution is supplied from the magnesium source supply source 9 to the stirrer 91 of the additive injection line L50.

  The treated water discharge line L5 includes two treated water reflux lines L51 and L52 that respectively branch from the main flow path. The first treated water reflux line L51 is branched from the main flow path by the three-way valve V3, is continuously connected to the additive injection line L50, and is connected to the lower part 56 of the MAP reactor via the additive injection line L50. Yes. As a result, a first treated water circulation circuit (hereinafter simply referred to as a first circulation circuit) composed of the reactor 5 → the line L5 → L51 → L50 → the reactor 5 is formed. The second treated water recirculation line L52 is branched from the main flow path by the three-way valve V2, is continuously connected to the raw water introduction line L4, and is connected to the raw water introduction section 55 of the MAP reactor via the raw water introduction line L4. Has been. As a result, a second treated water circulation circuit (hereinafter simply referred to as a second circulation circuit) composed of the reactor 5 → the line L5 → L52 → L4 → the reactor 5 is formed. These first and second circulation circuits respectively return a part of the treated water recovered from the phosphorus recovered from the MAP reactor 5 to the MAP reactor 5, and the former dilutes the additive solution injected into the lower part 56. Thus, the additive concentration is lowered, and the latter reduces the phosphorus concentration by diluting the water to be treated introduced into the raw water introduction portion 55.

  The biological treatment tank 6 has an inlet connected to the MAP reactor 5 via the line L5, and a carrier carrying aerobic microorganisms for biologically treating the treated water discharged from the MAP reactor 5 after the recovery of phosphorus. I have it. An aeration line L10 communicating with the blower 10 is connected to the bottom of the biological treatment tank 6. When compressed air is sent from the blower 10, bubbles are ejected from a plurality of openings of the aeration line L10 so that the water to be treated is air bubbled. It has become. In this biological treatment tank 6, it is possible to purify ammonia nitrogen remaining in the treated water, BOD components, and the like after phosphorus recovery by MAP growth from wastewater containing ammonia nitrogen. The biological treatment tank here can be a known technique such as a standard activated sludge method, a biological denitrification method, or a membrane separation activated sludge method, but a treatment tank having a nitrogen removal ability by biological treatment is applied. It is desirable.

  The membrane separation tank 7 has an inlet connected to the biological treatment tank 6 via the line L6, receives the treated water after biological treatment from the biological treatment tank 6, and solid-liquid separates the sludge contained in the treated water. It has a film. The outlet of the membrane separation tank 7 is connected to a discharge line L71 having a pump P6, and the separated liquid is discharged as treated water to a storage tank or a discharge port (not shown). The aeration line L10 and the reflux line L72 described above are connected to the bottom of the membrane separation tank 7, respectively. The reflux line L72 is provided with an on-off valve V4 and a pump P7. By opening and closing the on-off valve V4 and driving the pump P7, the treated water is returned from the membrane separation tank 7 to the biological treatment tank 6 via the line L72. Water can be circulated between the membrane separation tank 7 and the biological treatment tank 6.

  By providing such a membrane separation tank 7 in the subsequent stage of the biological treatment tank 6, the biological treatment tank 6 can be made compact, and the ability of forming MAP in wastewater can be improved by collecting phosphorus in the MAP reactor 5 in the previous stage. Since it falls, the water quality purification which suppressed the membrane blockage by the inorganic salt production | generation in the membrane separation tank 7 can be performed. The membrane separation tank 7 referred to here may be a known technique and is not limited to a specific type.

  Next, the operation of this embodiment will be described.

  The solid content contained in the raw water is removed by the solid-liquid separator 3. When the fermentation reaction proceeds in the next methane fermentation tank 4, the BOD component contained in the solid-liquid separation water is removed from the solid-liquid separation water discharged from the solid-liquid separation device 3 with the generation of biogas. Next, methane fermentation treated water that is treated water in the methane fermentation tank 4 is introduced into the MAP reactor 5. Here, the MAP reactor 5 is filled with a MAP crystal as a seed crystal inside, and the MAP crystal and the MAP treated water (raw water + treated water) introduced into the raw water introduction unit 55 in an upward flow. The MAP crystal to be filled is structured such that the filled MAP crystal does not flow out during operation, the bottom is formed in an inverted cone shape (cone shape), and the bottom of the MAP reactor 5 has a phosphorus content by crystal growth. It is connected to a MAP-containing water discharge line L53 for taking out the collected MAP.

  The MAP crystal filled in the MAP reactor 5 may be determined in accordance with the amount of phosphorus load to be introduced, the processing speed, the upward flow rate, and the filling amount and the crystal diameter may be determined, but at least above the water level of the raw water introduction part 55 Must be filled with MAP crystals. The treated water discharged from the MAP reactor 5 is circulated and supplied to the bottom of the MAP reactor 5 from the three-way valve V3 of the line L5, through the first treated water reflux line L51, and further through the additive injection line L50. . That is, the additive solution is injected from the additive injection line L50 into the lower part 56 of the MAP reactor, rises in the reactor 5 and reaches the raw water introduction part 55, and is introduced from the dispersion introduction pipe 51 of the raw water introduction line L4. The MAP crystal grows by reacting with the mixed dilution water (methane fermentation treated water + phosphorus recovery treated water) and reacting with the MAP crystal in the reactor 5.

  In the first circulation circuit including the first treated water reflux line L51, the liquid having the highest additive concentration among the liquids supplied to the MAP reactor 5 that is the most upstream part of the upward flow is the MAP crystal. It is introduced at the point 56 to be filled. On the other hand, in the second circulation circuit including the second treated water recirculation line L52, the MAP treated water (raw water) is disposed at a location 55 (upward position) downstream of the MAP crystal filling location 56 in the upward flow. + Treated water) is introduced. This introduction positional relationship is such that after mixing the treated water and the additive, the MAP crystal is grown on the MAP particles held in the reactor 5, and the liquid in which the additive and phosphorus are consumed in the system is the raw water in the reactor. Since it is mixed with the phosphorus-containing water introduced into the introduction part 55, it is in contact with the MAP particles held in the reactor 5 in a state in which an excessive supersaturation increase due to the additive concentration being reduced is suppressed, Since phosphorus is consumed for the growth of MAP particles, formation of new MAP fine particles is suppressed, and a decrease in phosphorus recovery rate is suppressed.

  The effect of this embodiment will be described.

  According to the present embodiment, in the first circulation circuit consisting of the reactor 5 → line L5 → L51 → L50 → reactor 5, the water to be treated has a higher flow rate than the MAP water to be treated from the raw water introduction line L4. By supplying, the fluctuation range of the supersaturation degree of the MAP crystallization accompanying the fluctuation in the concentration of the component related to the MAP formation of the MAP treated water 11 can be reduced.

  In addition, according to the present embodiment, by supplying the pH adjusting liquid and the magnesium source from the pH adjusting liquid supply source 8 and the magnesium source supplying source 9 to the first circulation circuit, the reflux treated water flowing through the first circulation circuit. As a result of the dilution of the additive solution, the rapid increase in the MAP supersaturation level that is changed by the addition of the magnesium source is suppressed in the reactor lower portion 56 where the concentration of the additive is the highest in the reaction system. For this reason, formation of new MAP fine particles, that is, nucleation can be suppressed, and a decrease in phosphorus recovery rate due to a decrease in MAP retention ability in the MAP reactor accompanying the formation of new MAP fine particles can be suppressed.

  In the present embodiment, by providing a plurality of raw water introduction portions in the MAP reactor into which the MAP treated water (raw water) is introduced, high-concentration MAP generation derived from the MAP treated water in the MAP reactor is generated. Because it is possible to suppress the uneven distribution of the active component, it is possible to suppress the formation of a nucleation region due to an increase in the MAP supersaturation level accompanying the generation of a high concentration region of a local MAP-forming component, and to suppress the formation of new MAP fine particles, that is, nucleation Further, it is possible to suppress a decrease in phosphorus recovery rate due to a decrease in MAP retention ability in the MAP reactor accompanying the formation of new MAP fine particles.

  In this embodiment, a part of the treated water is mixed with the MAP treated water (raw water) using the second circulation circuit, so that it is introduced into the MAP reactor when the phosphorus concentration in the treated water is high. Since the local MAP supersaturation in the MAP reactor caused by the high phosphorus concentration in the water to be treated can be suppressed and the formation of new MAP fine particles can be suppressed, a decrease in phosphorus recovery rate can be suppressed. By disposing the biological treatment tank 6 in the subsequent stage of the MAP reactor 5, it is possible to appropriately purify the ammonia nitrogen remaining in the treated water after recovery of phosphorus by MAP growth from the waste water containing ammonia nitrogen, the BOD component, and the like. it can. The biological treatment tank here may be a known technology such as a standard activated sludge method, biological denitrification method, membrane separation activated sludge method, etc., but one having a nitrogen removal ability by biological treatment should be applied. Is desirable. Moreover, the biological treatment tank 6 can be made compact by providing the membrane separation tank 7 at the subsequent stage of the biological treatment tank 6.

  According to the present embodiment, the BOD component contained in the water to be treated in the water treatment apparatus is purified as biogas, water purification and resource recovery can be achieved, and ammonia nitrogen and phosphate ions are contained in MAP fine crystals. Since it can be recovered as MAP crystals by suppressing the formation, water quality purification and resource recovery are achieved, and liquid with reduced BOD, nitrogen, and phosphorus content is purified by the membrane activated sludge method. Water quality purification can be achieved by reducing the salt production capacity, and it is possible to appropriately reduce the load on water treatment equipment, water quality purification, and resource recovery.

  In the present embodiment, after mixing the treated water and the additive, a liquid (treated water) in which the MAP crystal is grown on the MAP particles held in the reactor and the additive and phosphorus are consumed in the system is treated in the reactor. It is mixed with phosphorus-containing treated water flowing from the treated water introduction part inside. By mixing the treated water and the treated water, the treated water is diluted, the concentration of the additive is reduced, and the excessive MAP supersaturation is suppressed, and the MAP particles held in the reactor are brought into contact with each other. Since phosphorus is consumed for the growth of MAP particles, the formation of new MAP fine particles is suppressed, and the decrease in phosphorus recovery rate is suppressed.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. In addition, description of the part which this embodiment overlaps with said embodiment is abbreviate | omitted.

  In the water treatment apparatus 1A of the present embodiment, the storage tank 11 is provided on the downstream side of the three-way valve V3 where the first treated water recirculation line L51 branches on the treated water line L5, and further from the storage tank 11 to the raw water introduction line L4. A storage tank water return line L11 having a pump P11 is provided therebetween. The storage tank 11 is located immediately before the biological treatment tank 6 and temporarily stores treated water discharged from the MAP reactor 5.

  The operation of this embodiment will be described.

  When a predetermined amount of treated water is stored in the storage tank 11, the pump P11 is activated, and the storage tank water is returned from the storage tank 11 to the line L4 of the second circulation circuit via the line L11. That is, the [raw water + treated water] mixed water flowing through the second circulation circuit is further combined with the storage tank water (a part of the treated water), the dilution rate is increased, and the treated water is reduced in the phosphorous concentration state. Introduce into the MAP reactor 5. As described above, in the present embodiment, when the phosphorus concentration in the water to be treated is high due to the liquid in which the phosphorus concentration is reduced in the circulation reaction system of the MAP reactor 5 in the treated water, the MAP reactor 5 is introduced. The local MAP supersaturation in the MAP reactor 5 caused by the high phosphorus concentration in the water to be treated is suppressed, and the decrease in phosphorus recovery ability due to the formation and outflow of MAP fine particles due to MAP nucleation is suppressed.

  The effect of this embodiment will be described.

  According to the present embodiment, in response to fluctuations in the phosphorus concentration in the water to be treated, the production of MAP fine crystals can be suppressed and recovered as MAP crystals, so that nitrogen, phosphorus, BOD load and inorganic salt production ability are reduced. Water quality purification, reducing the load on the water treatment equipment, water quality purification, and resource recovery can be operated properly.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIG. In addition, description of the part which this embodiment overlaps with said embodiment is abbreviate | omitted.

  The water treatment device 1 </ b> B of the present embodiment includes a pH measurement device 21 and a control device 20. The pH measuring device 21 is attached at the most downstream side of the additive injection line L50, that is, downstream of the two stirrers 81 and 91. In the control device 20, the signal line from the pH measurement device 21 is connected to the input unit, and the output unit is connected to the drive circuit of the magnesium source supply pump P9.

  The operation of this embodiment will be described.

  When a magnesium ion component such as a magnesium hydroxide salt is used as the magnesium source, the pH value in the system fluctuates due to the supply thereof, so that the fluctuation of the MAP supersaturation in the MAP reactor 5 increases. In the present embodiment, the supply state of the magnesium source is measured by the pH measurement device 21, the pH measurement signal S1 is sent to the input unit of the control device 20, and the control device 20 controls the drive circuit of the pump P9 based on the input signal S1. The signal S2 is output. Thereby, the pump P9 is stopped or decelerated, and the supply of the magnesium source from the magnesium source supply source 9 to the additive injection line L50 is stopped or reduced, thereby reducing the amount of the magnesium source injected into the reactor lower part 56. Thus, an excessive increase in MAP supersaturation derived from the magnesium source is suppressed.

  The effect of this embodiment will be described.

  According to the present embodiment, by controlling the supply amount of the magnesium source, it is possible to suppress the formation of a system having an excessive degree of MAP supersaturation, and therefore, the generation of MAP fine crystals can be suppressed and recovered as MAP crystals. Nitrogen, phosphorus, BOD load and inorganic salt generation ability can be reduced to purify water, reducing the load on water treatment equipment, purifying water, and recovering resources appropriately.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described with reference to FIG. In addition, description of the part which this embodiment overlaps with said embodiment is abbreviate | omitted.

  The water treatment device 1 </ b> C of the present embodiment includes a pH measurement device 21 and a control device 20. The pH measuring device 21 is attached at the most downstream side of the additive injection line L50, that is, downstream of the two stirrers 81 and 91. In the control device 20, the signal line from the pH measurement device 21 is connected to the input unit, and the output unit is connected to the drive circuit of the pH adjusting agent solution supply pump P8.

  The operation of this embodiment will be described.

  When adjusting the pH of the treated water by adding a pH adjuster and adjusting the pH in the MAP reactor 5, if the pH value is lower than the desired set value, it becomes a region below the MAP dissolution saturation, and the MAP crystal Does not grow and phosphorus flows out of the system. On the other hand, when the pH value is higher than a desired set value, it becomes an excessive supersaturation region, which may cause suppression of MAP growth and reduction of phosphorus recovery rate due to generation of MAP fine particles in the reaction system. In the present embodiment, the pH abnormality of the liquid derived from the treated water supplied to the MAP reactor 5 is suppressed by controlling the pH value.

  The effect of this embodiment will be described.

  According to the present embodiment, the MAP supersaturation degree can be appropriately maintained by controlling the supply amount of the pH adjusting chemical solution, so that water purification can be achieved by reducing nitrogen, phosphorus, BOD load and inorganic salt generating ability, Reduces the load on the treatment equipment, cleans water, and recovers resources appropriately.

  In the present embodiment, the control device 20 controls only the pH adjuster solution supply pump P8. However, the present invention is not limited to this, and the present embodiment is not limited to the third embodiment. It can also be used in combination with the embodiment. That is, the controller 20 controls the operations of the two pumps P8 and P9 simultaneously in parallel to control both the supply amount of the pH adjuster solution and the supply amount of the magnesium source, so that excessive MAP in the reactor is increased. An increase in the degree of supersaturation can be suppressed.

1, 1A, 1B, 1C ... water treatment device,
2 ... Raw water tank, 3 ... Solid-liquid separator, 4 ... Methane fermentation tank,
5 ... Phosphorus recovery reactor (MAP reactor),
6 ... biological treatment tank, 7 ... membrane separation tank,
8 ... pH adjustment liquid supply source, 81 ... Stirrer, P8 ... pH adjustment liquid supply (pump),
9 ... Magnesium source supply source, 91 ... Stirrer, P9 ... Magnesium source supply device (pump),
10 ... Blower, 11 ... Storage tank,
20 ... Controller, 21 ... pH measuring device,
51, 51A ... dispersion introduction pipe, 52, 52A ... injection hole,
55 ... Raw water introduction part, 56 ... Additive injection part,
L11 ... Storage tank water return line,
L32 ... Biogas discharge line,
L4 ... Raw water introduction line,
L5 ... treated water line,
L50 ... Additive injection line,
L51 ... first treated water reflux line,
L52 ... Second treated water reflux line,
L53 ... MAP collection line,
P1-P9 ... pump, V1-V5 ... valve.

Claims (10)

In order to recover phosphorus from raw water containing ammoniacal nitrogen and phosphate ions, a phosphorus recovery reactor that reacts magnesium with the raw water to generate a magnesium ammonium phosphate salt;
An additive injection line for injecting the additive into the additive injection section in the phosphorus recovery reactor;
A raw water introduction line for introducing the raw water into the raw water introduction section located above the additive injection section in the phosphorus recovery reactor so as to flow upward;
At least one of a pH adjustment source supplier that is provided in the additive injection line and supplies a pH adjuster as the additive and a magnesium source supplier that supplies a magnesium source as the additive;
A stirring device that is provided in the additive injection line and stirs and mixes the additive and the treated water;
A treated water line through which treated water coming out of the phosphorus recovery reactor flows,
A branch from the treated water line is connected to the additive injection line so that a part of the treated water flows upward together with the additive into the phosphorus recovery reactor via the additive injected line. A first treated water reflux line for reflux;
A water treatment apparatus comprising: Branched from the treated water line and connected to the raw water introduction line, and a part of the treated water is upwardly directed to the raw water introduction part located above the additive injection part through the raw water introduction line together with the raw water. The water treatment apparatus according to claim 1, further comprising a second treated water reflux line for refluxing to form a flow. The water treatment apparatus according to claim 1, comprising a plurality of the raw water introduction lines. A storage tank provided on the treated water line and storing treated water;
A storage tank water return line that is provided between the storage tank and the raw water introduction line and returns treated water stored in the storage tank to the phosphorus recovery reactor through the raw water introduction line, The water treatment apparatus according to any one of claims 1 to 3. A pH measurement device that is provided in the additive injection line downstream of the stirring device and measures the pH of the fluid flowing through the additive injection line, and the magnesium source based on the pH measurement result from the pH measurement device The water treatment device according to claim 1, further comprising a control device that controls the feeder. A pH measurement device that is provided in the additive injection line downstream of the stirring device and measures the pH of the fluid flowing through the additive injection line, and the pH adjustment based on the pH measurement result from the pH measurement device The water treatment device according to claim 1, further comprising a control device that controls the agent supply device. The water treatment apparatus according to claim 1, further comprising a biological treatment tank connected to the phosphorus recovery reactor via the treated water line and performing biological water treatment. The said biological treatment tank has a membrane which performs a membrane separation activated sludge process, The water treatment apparatus of any one of the Claims 1 thru | or 7 characterized by the above-mentioned. The water treatment apparatus according to any one of claims 1 to 8, further comprising a solid-liquid separation device and an anaerobic digestion tank upstream of the phosphorus recovery reactor. The water treatment apparatus according to claim 9, wherein the anaerobic digester is a USB type methane fermenter.

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