JP4743627B2 - Water or sludge treatment equipment containing ions in liquid - Google Patents

Description

  The present invention relates to an apparatus for separating and concentrating crystals contained in water containing ions in liquid, anaerobic or aerobic sludge, and crystals obtained by crystallizing ions. The present invention also relates to an apparatus for treating digested sludge generated by anaerobic digestion of organic waste and wastewater. Furthermore, the present invention relates to an apparatus for crystallizing, separating and concentrating ions contained in waste water.

  In a treatment facility for organic wastewater containing phosphorus and nitrogen such as sewage, wastewater, human waste, etc., first, raw sludge (hereinafter also referred to as primary sedimentation sludge) is first solid-liquid separated at the first sedimentation site, and the separated supernatant is The organic sludge was removed by the activated sludge treatment. In the activated sludge treatment, the activated activated sludge is discharged as excess sludge. By the way, when organic waste such as raw sludge, surplus sludge, human waste, garbage is anaerobically digested, the organic matter in the waste is decomposed by the action of acid-producing bacteria and methanogenic bacteria, and the sludge can be reduced. At the same time, gas containing methane, carbon dioxide, etc., and wastewater with high nitrogen and phosphorus concentrations are produced. Today, active studies are being conducted on the use of generated methane gas as a heat source, and the production of MAP (magnesium ammonium phosphate) from digested and desorbed liquid obtained by dewatering digested sludge for effective use as fertilizers and chemical raw materials. (Patent Document 1).

  Furthermore, today, anaerobic digesters are being made more efficient in terms of further energy recovery and sludge reduction. For example, raw sludge, surplus sludge, mixed sludge mixed with raw sludge and sludge is solubilized by physical / mechanical treatment, chemical liquefaction treatment, heating treatment, etc. The process improves the recovery rate of methane gas and promotes sludge reduction. Such physical / mechanical treatment includes ultrasonic treatment, crushing treatment with a mill, etc., and chemical liquefaction treatment includes treatment with ozone, hydrogen peroxide, acid, alkali, and heating treatment is There are treatments with thermophilic bacteria. For example, (Patent Document 2) describes a method of solubilizing sludge by treating it in an ultrasonic treatment process.

As described above, the higher the efficiency of anaerobic digestion, the higher the nitrogen / phosphorus concentration in the digested sludge. Originally, organic waste contains elements such as nitrogen, phosphorus, and magnesium. When the organic waste is solubilized, these elements are transferred to the liquid.
Today, in order to use digested sludge effectively and efficiently, each sewage treatment plant is connected by pipes (pipe lines), and the generated digested sludge is transported by pipes. There are also areas where aggregation processes are performed that are collected at the venue and processed there. The construction cost of pipes is cheaper than that of treatment facilities, and sludge treatment facilities have the advantage of scale (the increase in scale reduces the cost per unit). It is said to be economical in the close proximity.

By the way, in the digestion tank, so-called MAP precipitates were formed in which magnesium ions in the sludge, phosphate ions and ammonium ions were combined. Similarly, when the digested sludge and its effluent are transported by piping, MAP deposits are generated, which may block the sludge pipe.
In order to solve the above problem, in (Patent Document 3), when sludge is sent to the mud pipe, digested sludge is aerated in the reactor in advance to generate MAP particles, and then the sludge containing the MAP particles is removed. A method is known in which the MAP is removed and collected by centrifugation and then fed. In addition, a part or all of the MAP particles after being centrifuged are returned to the reactor to form new MAP particle nuclei in the reactor. By performing such an operation, problems such as blockage in the sludge pipe due to MAP particles can be avoided.
JP 2003-117306 A JP 2002-336898 A JP 2001-162300 A

  As described above, the higher the efficiency of anaerobic digestion, the more wastewater with higher nitrogen / phosphorus concentration is produced. Originally, organic waste contains elements such as nitrogen, phosphorus, and magnesium. When the organic waste is solubilized, these elements are transferred to the solution. Nitrogen, phosphorus, and magnesium are components that make up MAP, and when it becomes a high concentration in the liquid or when alkali rises, it easily exceeds the solubility product of MAP and naturally occurs in the digestion tank. MAP was precipitated on the surface. In the digestion tank, MAP was deposited on the draft tube, so that the flow of digested sludge deteriorated, and scale troubles such as piping blockage at the time of pump drawing occurred frequently. In addition, these MAPs are disposed of together with dehydrated sludge without being collected, and there has been a demand for providing an efficient method for collecting MAP.

In addition, when such digested sludge containing MAP is transported by piping to a sludge collection facility, a large number of MAP scales are generated in the piping, which hinders efficient transport of sludge. Once the MAP scale is generated, it has the property of growing further. If the MAP scale is left in the pipe, the entire pipe will eventually be covered with the MAP scale, making it difficult to transport sludge, so regular cleaning is indispensable and maintenance is complicated. .
Furthermore, digested sludge contains several hundred mg / liter (L) of soluble phosphorus, and returning them to the water treatment system will cause problems such as failure to comply with the water quality standards for discharged water. Therefore, there is a demand for providing a technique for removing soluble phosphorus.
Moreover, in the method of recovering MAP by aeration and centrifuging MAP, not only MAP but also digested sludge and residue are mixed in the recovered material, and MAP with high purity cannot always be recovered. There wasn't. When phosphorus is reused, purity is also required, and there has been a particular demand for providing a method for recovering MAP with high purity.

The present invention solves the above-mentioned problems, satisfies both the removal and recovery of phosphorus, recovers high-purity MAP, and performs stable processing with a high MAP recovery rate without clogging the liquid cyclone. It is an object of the present invention to provide a processing method and an apparatus that can be used.
The present invention can be applied not only to the separation and recovery of MAP crystals from the above-described anaerobic digested sludge but also to the separation and recovery of various crystals from various wastewaters. For example, calcium phosphate (Ca ₃ (PO ₄ ) ₂ ) or hydroxyapatite (Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ ): HAP) from wastewater such as secondary treated water of sewage and return water from the sludge treatment system Crystal recovery of calcium fluoride (CaF ₂ ) from semiconductor factory wastewater, etc .; Recovery of calcium carbonate crystals from water, wastewater, and waste leachate from groundwater; high in carbonate ions The present invention can be applied to recovery of crystals of calcium carbonate (CaCO ₃ ) from hard water; recovery of Mn, which is an impurity in tap water, as crystals of manganese carbonate (MnCO ₃ );
In the present specification, a case where MAP crystals are separated and recovered mainly from anaerobic digested sludge will be described as an example.

The problems of the present invention have been solved by the following means.
(1) A liquid cyclone, a crystallization reactor for precipitating crystals by adding chemicals to water or sludge containing ions in the liquid, and an input pipe A for introducing the sludge from the crystallization reactor into the liquid cyclone, A return pipe B for returning part or all of the crystals concentrated in the hydrocyclone to the crystallization reactor, and a return for returning a part of the treated sludge flowing out from the overflow riser pipe of the hydrocyclone to the sludge input pipe A A pipe C is provided, a washing pipe D for washing water is connected to the input pipe A or the return pipe C, and a recovery pipe E for discharging a part or all of the concentrated crystals out of the system is connected to the return pipe B. An apparatus for treating water or sludge containing ions in liquid.
(2) After solid-liquid separation of crystals concentrated in a liquid cyclone, a part or all of the separated separated water is introduced into the liquid cyclone, or water containing ions in the liquid according to (1) or Sludge treatment equipment.
(3) The return pipe B, the return pipe C, the cleaning pipe D, and the recovery pipe E each have a valve that can be opened and closed, and when the return pipe B and the return pipe C are open, the cleaning pipe D and the recovery pipe are opened. (1) characterized in that a control mechanism is provided for opening the valves of the cleaning pipe D and the recovery pipe E when the valves of the pipe E are closed and the valves of the return pipe B and the return pipe C are closed. Or the processing apparatus of the water or sludge containing the ion in a liquid as described in (2).
(4) The return pipe B or the recovery pipe E is provided with a cleaning pipe F provided with a valve, and the input pipe A and the overflow riser pipe are provided with a flow meter or a pressure gauge, and the difference between the two is detected. The apparatus for treating water or sludge containing ions in liquid according to any one of (1) to (3), wherein a control mechanism for supplying cleaning water through the cleaning pipe F is provided.

According to the present invention, in an apparatus for separating phosphorus in water and sludge containing ions in liquid, particularly digested sludge generated by anaerobic digestion of organic waste, by a crystallization reactor and a hydrocyclone, removal of phosphorus In addition to recovering MAP with good purity, stable processing can be performed with a high MAP recovery rate without clogging the liquid cyclone.
According to the present invention, when digested sludge containing MAP is transported to a sludge consolidation facility, a large number of MAP scales are generated in the piping, which hinders efficient transport of sludge. Therefore, sludge can be easily transported, the number of periodic cleanings can be reduced, and maintenance can be simplified.
The present invention can be applied not only to separation / recovery of MAP crystals but also to separation / recovery of various crystals from various wastewaters. For example, calcium phosphate (Ca ₃ (PO ₄ ) ₂ ) or hydroxyapatite (Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ ): HAP) from wastewater such as secondary treated water of sewage and return water from the sludge treatment system Crystal recovery of calcium fluoride (CaF ₂ ) from semiconductor factory wastewater, etc .; Recovery of calcium carbonate crystals from water, wastewater, and waste leachate from groundwater; high in carbonate ions Recovery of crystals of calcium carbonate (CaCO ₃ ) from hard water; recovery of Mn, which is an impurity in tap water, as crystals of manganese carbonate (MnCO ₃ ); and the like, these crystals and salts can be obtained. .

The present invention will be described in detail with reference to the drawings. In the drawings, components having the same function are described with the same reference numerals.
Examples of the sludge to be treated in the present invention include human waste, septic tank sludge, sewage sludge, agricultural sludge, livestock manure, garbage, food waste, and the like. It is quite a lot. In order to carry out the treatment smoothly, it is preferable to treat the non-slurry product itself as a slurry by adding waste water or the like. Hereinafter, the case where digested sludge is employ | adopted as an organic waste is demonstrated to an example.

FIG. 1 is a processing flow for recovering MAP and soluble phosphorus in digested sludge using a crystallization reactor 1 and a hydrocyclone 2.
In an anaerobic digester (not shown), surplus sludge and / or primary sedimentation sludge is charged. In the anaerobic digester, it is heated to maintain about 55 ° C or about 35 ° C. In the anaerobic digester, the sludge is decomposed into gas such as methane, carbon dioxide and hydrogen sulfide, water-soluble nitrogen, phosphorus and the like by the action of acid-fermenting bacteria and methanogenic bacteria. The generated methane gas can be used for energy by recovery. By adding not only excess sludge but also readily degradable raw sludge, the amount of methane gas generated further increases. When the sludge is decomposed, phosphorus, magnesium, and ammonium move to the liquid side, and when the concentration is higher than the solubility product of MAP, MAP crystals are spontaneously generated in the anaerobic digester. The generated MAP repeats nucleation and growth, and exists in a wide particle size distribution of several μm to several hundred μm. In addition, some of them adhered to and grew on the bottom of a draft tube, an anaerobic digester, or sludge discharge piping, etc., causing scale trouble.

Of course, the MAP generation phenomenon is also affected by the properties of sludge thrown into the anaerobic digester, the presence or absence of chemicals, etc., so that a large amount of MAP is generated at the treatment plant A or the treatment plant B Then, it may not be generated at all. Digested sludge contains several hundred mg / L of soluble phosphorus and several hundred to several thousand mg / L of ammoniacal nitrogen.
Digested sludge withdrawn from the anaerobic digester is put into a hydrocyclone through a crystallization reactor.

The crystallization reactor 1 shown in FIG. 1 reacts with the PO ₄ -P dissolved in the liquid by adding the magnesium compound 4 to the digested sludge 3 extracted from the anaerobic digestion tank, thereby allowing MAP to react. Precipitate. At this time, when aeration treatment, decompression treatment, or the like is used in combination, decarboxylation increases the pH, and MAP can be precipitated more efficiently. Of course, chemicals such as sodium hydroxide, magnesium hydroxide, and magnesium oxide may be added to raise the pH. As the magnesium compound 4 to be added, magnesium hydroxide, magnesium oxide, seawater and the like can be used in addition to magnesium chloride. The amount of magnesium added is 0.1 to 10, preferably 0.5 to 3.0, more preferably 0.8 to 1.2 in terms of molar ratio to the soluble orthophosphoric acid concentration in the digested sludge 3. Good. The pH in the reaction is 7.0 to 11.0, preferably 7.5 to 8.5.
Further, seed crystals are added to the crystallization step in order to efficiently generate MAP. As the seed crystal, MAP deposited in the crystallization step, MAP deposited in a separate reactor can be used, and further, MAP deposited spontaneously in a digestion tank can be used.

Further, fine particles containing MAP recovered by the hydrocyclone 2 can also be used. When MAP is contained in the separation water in the middle of the separation process, effluent water, or the like, these may be used. In addition, powders or granular materials such as phosphate ore, dolomite, bone charcoal, activated carbon, silica sand, and calcium silicate can be used.
The grain size of the seed crystal may be arbitrary, but is preferably 0.05 to 3.0 mm, more preferably 0.1 to 0.5 mm. By separating new MAP on the surface of the seed crystal, the separation of digested sludge and MAP in the subsequent hydrocyclone 2 becomes good. In order to precipitate on the surface of the seed crystal, the filling amount of the seed crystal is very important. In consideration of the input amount of phosphorus and the seed crystal particle size, the filling amount is 100 g-P / m ² / d or less, preferably 30 g- P / m ² / d or less, more preferably 10 g-P / m ² / d or less. That is, for the same particle diameter, maintaining a high concentration of MAP in the reactor makes it possible to reduce the reactor volume and reduce the initial cost.

Here, the reactor in the crystallization step is not particularly limited, and a fully mixed reactor equipped with a mechanical stirring device, a jet stirring reactor using a pump, a fluidized bed filled with seed crystals at a high density A type reactor, an internal circulation type reactor equipped with a draft tube, an external circulation type reactor, or the like can be used.
The MAP precipitated in the crystallization process and the MAP generated in the digestion tank are collected by the liquid cyclone 2.

The hydrocyclone 2 shown in FIG. 1 has an inverted conical lower structure, a hydrocyclone input pipe A5 (also referred to as an inflow pipe) at the side, and a return pipe B6 connected to the crystal discharge pipe 9 at the lower part. An overflow riser pipe 7 is provided at the top. In the hydrocyclone 2, the digested sludge containing MAP is passed through the hydrocyclone input pipe A5 by pumping, and descends while creating a swirling flow inside the inverted cyclone wall inside the hydrocyclone 2, and the specific gravity is higher than the digested sludge. Crystals containing heavy MAP are collected and concentrated on the lower wall side by the action of centrifugal force. The concentrated crystals are continuously or intermittently extracted from the return pipe B6. Further, the sludge from which crystals containing MAP have been removed (treated sludge 8) is taken out from the overflow riser pipe 7 and discharged.
The diameter of the discharge pipe 9 of the crystal of the hydrocyclone 2 and the diameter of the overflow riser pipe 7 (sludge discharge pipe) can be changed, and the flow rate and particle size distribution can be changed by changing both. .

By the way, the concentrated MAP recovered from the crystal discharge pipe 9 contains about 10 to 30 g / L of sludge and other impurities (sulfide, Al salt, Fe salt, etc.) in addition to MAP. . Conventionally, when MAP is reused, good purity is required, and depending on the application, when it is reused as fertilizer, it is generally required to be 80% or more, preferably 90% or more. However, the conventional method of simply separating MAP from digested sludge has a maximum of about 70%, and in order to increase the purity, a washing step of the recovered MAP is necessary at a later stage.
In the present invention, the washing water washing pipe D11 is connected to the MAP-containing sludge charging pipe A5 or the return pipe C10, and the sludge is diluted or washed with the washing water 12, and the crystals in the sludge are concentrated by the hydrocyclone 2. While collecting. Further, a return pipe C10 is connected for returning a part of the treated sludge 8 flowing out from the overflow riser pipe 7 to the sludge input pipe A5. Further, a recovery pipe E14 for discharging the concentrated MAP 13 out of the system is connected to the crystal return pipe B6.

(Return tube C)
The flow rate supplied to the hydrocyclone 2 is preferably constant, and the processing performance is affected if the input flow rate or input pressure changes. For example, in the case of a 2-inch cyclone, the input flow rate is preferably 4 m ³ / hr, and in the case of a 4-inch cyclone, the input flow rate is preferably 20 m ³ / hr. Further, the MAP concentration in the sludge to be input is an important factor for determining whether or not the cyclone is blocked, and should be 100 g / L or less, preferably 50 g / L or less, more preferably 20 g / L or less. . When the MAP concentration is high, the cyclone is blocked. In view of the above, the treated sludge 8 that has flowed out of the cyclone overflow ascending pipe 7 contains almost no MAP, and the treated sludge 8 is returned to the charging pipe A5, so that the MAP concentration of the cyclone charged Is preferable, and the sludge flow rate can be kept constant.

(Cleaning tube D)
By providing the cleaning pipe D11 as in the present invention and supplying the cleaning water 12 when collecting the MAP, high-purity MAP can be efficiently obtained without installing a special device.
The washing water 12 supplied from the washing pipe D11 is not particularly limited, but at least the SS concentration is lower than that of the digested sludge, preferably several hundred mg / L or less, more preferably several tens mg / L or less. Specifically, it is preferable that there is no SS such as industrial water, secondary treated water, and tertiary treated water. Sludge and washing water can be mixed at an arbitrary ratio (dilution ratio). As the ratio of washing water increases, the subsequent draining operation becomes easier and the purity of the recovered crystal 13 improves.
In the draining operation, the lower the sludge viscosity, the easier the discharge of waste water (supernatant) containing organic matter, so the higher the dilution ratio, the better. Generally, digested sludge has a viscosity of 10 to 50 mPas, but is preferably diluted with washing water to at least 10 mPas or less, preferably 5 mPas or less, more preferably 3 mPas or less.
In view of the above, the dilution ratio is preferably 1 to 20, and 1 to 10 is preferable in consideration of reducing the amount of washing water used.

  As described above, when the diameter of the crystal discharge pipe 9 and the diameter of the overflow riser 7 are changed, the flow rate ratio (Qu / Qo) between the discharge pipe 9 and the overflow riser 7 changes. The smaller the flow rate ratio, the smaller the discharge flow rate of the discharge pipe 9, thereby reducing the absolute amount of sludge discharge. When the amount of sludge discharged is reduced, the amount of sludge per unit weight of crystals is relatively reduced, so that the purity tends to be improved.

(Return tube B, recovery tube E)
In normal operation, the MAP concentrated in the hydrocyclone 2 is returned to the reactor 1 through the return pipe B6. By returning the concentrated MAP to the reactor 1, the MAP concentration in the reactor can be maintained high, and the reactor 1 is downsized. By the way, since the MAP concentration in the reactor increases with the progress of the crystallization reaction, it is necessary to draw MAP out of the system in a timely manner. In that case, the concentrated MAP can be discharged out of the system from the collection pipe E14 connected to the return pipe B6. In this way, the MAP concentration in the reactor is kept constant. The extraction frequency can be set arbitrarily and may be kept constant by extracting once / day or by measuring the MAP concentration in the reactor.

(Valve control)
By the way, the return pipe B6, the return pipe C10, the cleaning pipe D11, and the recovery pipe E14 are each provided with an openable and closable valve in order to make them function appropriately.
In normal operation, the purity of the concentrated MAP returned through the return pipe B6 does not need to be particularly high, so that it is not necessary to supply cleaning water in normal operation. When recovering concentrated MAP through the recovery pipe E14, the higher the purity of the recovered product, the better. Therefore, in such a case, the cleaning water 12 is supplied from the cleaning pipe D11 of the cleaning water 12 to dilute and clean the sludge. It is good to collect while performing.

  However, in the present invention, when the valves of the return pipe B6 and the return pipe C10 are open, the valves of the cleaning pipe D11 and the recovery pipe E14 are closed, and when the valves of the return pipe B6 and the return pipe C10 are closed, cleaning is performed. Since it is necessary to open the valves of the pipe D11 and the recovery pipe E14 in order to perform the above-described action, a control mechanism for controlling the valves so as to operate is provided. In this way, during normal operation, the amount of washing water is reduced without using the washing water 12, and when concentrated MAP is recovered, it is diluted and washed with washing water, so the purity is high. Crystals can be obtained.

(Solid-liquid separation of recovered crystals)
In another embodiment of the present invention shown in FIG. 2, the MAP recovered by the hydrocyclone is further subjected to solid-liquid separation 15 (also referred to as “draining”) to obtain a MAP having a reduced moisture content, and a fine MAP. This is a processing flow for improving the MAP recovery rate of the whole system by sending the separated water containing the crystallization reactor 1 to the liquid cyclone 2 again.
The concentrated MAP recovered through the recovery tube E14 is subjected to solid-liquid separation to obtain MAP13 from which the separated water 16 has been removed. As a method of solid-liquid separation, as a method of separating using a difference in specific gravity, there are a liquid cyclone, a centrifugal sedimentator, a sedimentation separation tank using gravity separation, etc., and as a method of separation using a difference in particle diameter, A vibration sieve, a drum screen, a filtration tank, a classification tank type separation tank, or the like can be used. In any method, a part or the whole amount of separated water is charged into the hydrocyclone 2. The separated water 16 may be returned to the input pipe A5, may be returned to the crystallization reactor 1, or may be returned to the return pipe C10. In any case, the liquid cyclone 2 is passed again.
In the separation device 15 described above, not a little fine MAP is discharged to the separation water side, so that the separation water 16 containing MAP is returned to the hydrocyclone 2 to increase the recovery rate of the entire system. be able to. Moreover, when returning to the crystallization reactor 1, it can use as a seed crystal.

(Cleaning tube F)
In another embodiment of the invention shown in FIG. 6, the cyclone underflow blockage detection is performed by calculating a difference between values detected by a flow meter or a pressure gauge installed in the input pipe A5 and the overflow riser pipe 7, respectively. Thus, it is a processing flow for recognizing whether or not the block is closed and supplying the cleaning water when the block is closed. Hereinafter, a case where a flow meter is mainly installed will be described.
As shown in FIG. 6, flowmeters 17 and 18 are installed in the input pipe A5 and the overflow riser pipe 7, respectively. Further, a cleaning pipe F19 provided with an openable / closable valve is installed in the return pipe B6 or the recovery pipe E14. Further, a control mechanism 20 is provided that detects the values of the flow meters 17 and 18, calculates the difference between them, and controls the opening and closing of the valve installed in the cleaning pipe F19 according to the calculation result.

FIG. 7 is a flowchart illustrating an example of the control mechanism. A description will be given based on FIG. In normal operation, the valve of the return pipe B6 is open and the valve of the cleaning pipe F19 is closed. Since the valve of the return pipe B6 is open, the valve of the recovery pipe E is also closed. Further, the difference (ΔF) between the flow rate of the input pipe A5 (referred to as F1) and the flow rate of the overflow ascending pipe 7 (referred to as F2) is a predetermined value. Here, ΔF is usually 0.8 m ³ / hr. This value is the underflow flow rate. When the cyclone underflow is blocked, ΔF becomes zero. At this time, the valve of the cleaning pipe F19 is opened, the return pipe B6 valve is closed, and the cleaning water 12 flows back through the cyclone. In this case, the valve of the recovery pipe E14 is kept closed. In this way, the cyclone is washed. After washing for a predetermined time, normal operation is performed. Note that the flowchart of FIG. 7 also incorporates control for abnormally stopping if the problem is not solved even if the above operation is repeated several times.
When controlling by pressure, the flowchart of FIG. 7 can be generally taken.

  Hereinafter, the present invention will be described in more detail by way of examples.

Example 1
In Example 1, processing was performed using a processing flow as shown in FIG. The treatment target sludge was digested sludge extracted from a digestion tank (not shown). The raw sludge 3 was sludge obtained by removing screens and the like in the digested sludge with a screen.
In the crystallization reactor 1, magnesium chloride 4 was added so that the Mg / P molar ratio = 1 with respect to the orthophosphate ion concentration of the digested sludge, and a pH adjuster was added so that the pH was 8.0. . The MAP concentration in the crystallizer was maintained at 80 g / L.

Input amount of sludge at 0.25 m ³ / hr, with withdrawal of the sludge from the crystallization reactor 1 1.5m ³ / hr, and return the treated sludge hydrocyclone at 2.5 m ³ / hr, the hydrocyclone 2 Was 4 m ³ / hr. The liquid cyclone 2 was charged intermittently, and the water level in the crystallization reactor 1 was detected with a pressure type level meter and controlled on-off. The liquid cyclone used an inch cyclone, and the MAP concentrated by the liquid cyclone was returned to the normal crystallization reactor. In order to collect the concentrated MAP once / day, the valve of the collection tube E14 was opened to collect MAP13. At this time, the bubble of the return pipe C10 was closed and the valve of the cleaning pipe D11 was opened. In addition, the input amount of the washing water 12 was 2.5 m ³ / hr.
The properties of the recovered MAP were MAP concentration of 180 g / L, organic matter concentration of 7 g / L, and MAP purity of 96%. Compared with the comparative example 1 mentioned later, the purity improved 10 points or more.

Example 2
In Example 2, the test which collect | recovers phosphorus in the form of magnesium ammonium phosphate was done for the digested sludge extracted from the digestion tank of a sewage treatment plant. The processing flow is shown in FIG.
The processing flow consists of a sieve-type inspection and removal device 21, a crystallizer 1, a hydrocyclone 2, and a circulating water tank 22.
The crystallizer 1 adds magnesium chloride 4 with respect to the orthophosphate ion concentration of the digested sludge 3 so that the Mg / P molar ratio = 1, and also adds a pH adjuster so that the pH becomes 8.0. did. The MAP concentration in the crystallizer 1 was maintained at 80 g / L.

The sludge extracted from the sludge extraction pipe 24 was supplied to the input pipe A5 and continuously supplied to the hydrocyclone 2. As the liquid cyclone 2, a 2-inch cyclone was used. The sludge discharge pipe diameter was 14 mm, and the particle discharge pipe diameter was 9.4 mm. The input flow rate of the hydrocyclone 2 was 4 m ³ / hr, and the input pressure was 0.40 Mpa.
The raw sludge supply amount was 0.25 m ³ / hr, and the withdrawal amount was 1.5 m ³ / hr. In order to collect the concentrated MAP once / day, the valve of the collection tube E14 was opened to collect the MAP. At this time, the bubble of the return pipe C10 was closed and the valve of the cleaning pipe D11 was opened. The amount of washing water used was 2.5 m ³ / hr.
The properties of the recovered MAP were MAP concentration of 180 g / L, organic matter concentration of 7 g / L, and MAP purity of 96%. Compared with the comparative example 1 mentioned later, the purity improved 10 points or more.

Example 3
The third embodiment is a flow in which the collected liquid-solid separation device 15 is installed in the processing flow of the second embodiment and the separated water 25 is returned to the circulating water tank (FIG. 4). As the solid-liquid separator 15, a sieve having an opening of 50 μm was used. The entire amount of the separated water of the solid-liquid separator was returned to the circulating water tank 22. When draining was performed by allowing the solid-liquid separator 15 to stand for about 1 day, the water content decreased from 60% to 20%. Furthermore, when the purity of MAP after draining was examined, it was 95%.

Example 4
Example 4 was processed with the processing flow of FIG. The processing flow in FIG. 3 was the same except that the cleaning tube F19 and the clogging elimination system 20 were installed. In the clogging elimination system 20, flow meters 17 and 18 are installed in the input pipe A5 and the overflow riser pipe 7. When the difference between the flow meters becomes 0.8 m ³ / hr or less, cleaning water is supplied from the cleaning pipe F19. This is a system for cleaning the inside of a cyclone with an upward flow.
After 30 hours from the start of water flow, the cyclone under blockage occurred, the blockage elimination system 20 was activated, the valve of the cleaning pipe F19 was opened, and cleaning water was supplied. The problem was not solved at the first time, and the blockage was solved at the second time. After that, stable treatment could be performed. The blockage was due to the inclusion of foreign matter entangled with MAP and hair.

Example 5
In Example 5, the calcium salt was removed by precipitating calcium carbonate particles in the treatment of the waste leachate. The processing apparatus includes a crystallization reactor 1 and a hydrocyclone 2. The processing flow is shown in FIG.
In the crystallization reactor, waste leachate (hereinafter referred to as raw water 26) was supplied to the upper part of the crystallization reactor 1, and a 5% sodium carbonate aqueous solution 27 as a carbonic acid source was also supplied to the crystallization reactor 1. The properties of the raw water 26 were a calcium concentration of 2000 mg / L and an SS concentration of 3000 mg / L. The amount of sodium carbonate added was set so that the CO ₃ / Ca molar ratio = 1: 1 with respect to the calcium concentration of the raw water 26 charged into the crystallization reactor 1. The reaction pH was 8.0. The calcium carbonate concentration in the crystallization reactor 1 was maintained at 20 g / L.

The input amount of the raw water 26 is 0.25 m ³ / hr, and the waste water containing crystals is drawn from the crystallization reactor 1 at 1.5 m ³ / hr, and the treated water of the cyclone is returned at 2.5 m ³ / hr, The input amount of the liquid cyclone 2 was 4 m ³ / hr. The liquid cyclone 2 was intermittently charged, and the water level in the reactor 1 was detected by a pressure type level meter and controlled on-off. The liquid cyclone 2 was a 2-inch cyclone, and the calcium carbonate concentrated by the liquid cyclone was returned to the normal crystallization reactor 1. In order to collect the concentrated calcium carbonate once / day, the valve of the collection pipe E14 was opened to collect the calcium carbonate. At this time, the bubble of the return pipe C10 was closed and the valve of the cleaning pipe D11 was opened. In addition, the input amount of the washing water 12 was 2.5 m ³ / hr.
The properties of the recovered calcium carbonate 13 were a calcium carbonate concentration of 80 g / L, an organic matter concentration of 1 g / L, and a calcium carbonate purity of 99%. Compared with the comparative example 1 mentioned later, purity improved 3 points or more.

Comparative Example 1
Comparative Example 1 is a comparative example corresponding to Example 2. The processing flow is shown in FIG. FIG. 5 is the same as FIG. 3 except that there is no cleaning water cleaning pipe D.
The properties of the recovered MAP were MAP concentration of 180 g / L, organic matter concentration of 20 g / L, and MAP purity of 85%. Compared to Example 2, the purity was lower by 10 points or more.

Comparative Example 2
This comparative example is a comparative example of Example 5. The processing flow is shown in FIG. FIG. 9 is the same as FIG. 8 except that there is no cleaning pipe D for cleaning water.
The properties of the recovered calcium carbonate were 80 g / L as calcium carbonate, 3 g / L as the organic substance concentration, and the purity of calcium carbonate was 96%. Compared with Example 5, 3-point purity was low.

  The present invention not only efficiently separates and recovers MAP crystals from anaerobic digested sludge and the like, but also calcium phosphate and hydroxyapatite from wastewater such as secondary treated water of sewage and return water from the sludge treatment system. Crystal recovery of calcium fluoride from semiconductor factory wastewater, etc .; Recovery of calcium carbonate crystals from water, wastewater and waste leachate from groundwater; Carbonation from hard water rich in carbonate ions It can be applied to the recovery of calcium crystals; the recovery of Mn, which is an impurity in tap water, as crystals of manganese carbonate;

It is a figure which shows the basic processing flow of this invention which collect | recovers MAP in digested sludge using a crystallization reactor and a liquid cyclone. It is a figure which shows the processing flow of this invention which consists of a crystallization reactor, a liquid cyclone, and a solid-liquid separator. FIG. 6 is a diagram illustrating a processing flow of Example 2. FIG. 10 is a diagram illustrating a processing flow of Example 3. 10 is a diagram showing a processing flow of Comparative Example 1. FIG. It is a figure which shows the processing flow of this invention provided with the control mechanism which controls supply of washing water. FIG. 7 is a flowchart of an example of the calculation / control mechanism of FIG. 6. FIG. 10 is a diagram illustrating a processing flow of Example 5. It is a figure which shows the processing flow of the comparative example 2. FIG.

Explanation of symbols

1 Crystallization reactor 2 Hydrocyclone 3 Raw sludge (digested sludge)
4 Mg compound (chemical supply pipe)
5 Hydrocyclone input pipe A (inflow pipe A)
6 Return tube B
7 Overflow riser 8 Processed sludge 9 Crystal discharge pipe 10 Return pipe C
11 Washing tube D
12 Washing water 13 Recovery crystal 14 Recovery tube E
15 Solid-liquid separator 16 Separated water 17 Flow meter (or pressure gauge)
18 Flow meter (or pressure gauge)
19 Washing tube F
20 Calculation / Control Mechanism 21 Screen Removal Device 22 Circulating Water Tank 23 pH Meter 24 Extraction Pipe 25 Separation Water 26 Raw Water 27 Carbon Source 28 Return Pipe G
29 Return water 30 Circulating water inflow pipe 31 Treated water 32 Raw water supply pipe 33 Chemical supply pipe

Claims (4)

  A liquid cyclone and a crystallization reactor for precipitating crystals by adding chemicals to water or sludge containing ions in the liquid are provided. An input pipe A for introducing the sludge from the crystallization reactor into the liquid cyclone, and the liquid cyclone A return pipe B for returning part or all of the concentrated crystals to the crystallization reactor, and a return pipe C for returning a part of the treated sludge flowing out from the liquid cyclone overflow riser pipe to the sludge input pipe A A washing pipe D is connected to the charging pipe A or the return pipe C, and a recovery pipe E for discharging a part or all of the concentrated crystals out of the system is connected to the return pipe B. An apparatus for treating water or sludge containing ions in the liquid.   2. The apparatus for treating water or sludge containing ions in liquid according to claim 1, wherein after the crystals concentrated in the liquid cyclone are subjected to solid-liquid separation, a part or all of the separated separated water is introduced into the liquid cyclone. .   The return pipe B, the return pipe C, the cleaning pipe D, and the recovery pipe E are each provided with a valve that can be opened and closed, and when the return pipe B and the return pipe C are open, the cleaning pipe D and the recovery pipe E 3. A control mechanism is provided wherein the valves of the cleaning pipe D and the recovery pipe E are opened when the valves are closed and the valves of the return pipe B and the return pipe C are closed. The processing apparatus of the water or sludge containing the ion in a liquid of description.   The return pipe B or the recovery pipe E is provided with a cleaning pipe F provided with a valve, and the input pipe A and the overflow riser pipe are provided with a flow meter or a pressure gauge, and the difference between the two is detected. The apparatus for treating water or sludge containing ions in liquid according to any one of claims 1 to 3, further comprising a control mechanism for supplying cleaning water through F.

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