JP2017087122A - Water treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water treatment apparatus capable of efficiently discharging from a reaction vessel a recovery agent that adsorbs and fixes dissolved compounds.SOLUTION: A water treatment apparatus includes a reaction vessel, a water introducing port, a recovery agent loading device, a discharge port, an introduction port, and a recovery port. The reaction vessel has a cylindrical side wall and a bottom wall with a gentle slope. The water introducing port supplies the reaction vessel with water to be treated containing dissolved compounds. The recovery agent loading device supplies the reaction vessel with a granular recovery agent to adsorb the dissolved compounds. The discharge port discharges the water to be treated from a position higher than the level of the recovery agent precipitating on the bottom of the reaction vessel. The introduction port introduces part of the water to be treated discharged from the reaction vessel to the reaction vessel in the tangential direction of the side wall of the reaction vessel. The recovery port is disposed at the lowermost part of the bottom wall of the reaction vessel.SELECTED DRAWING: Figure 1

Description

  Embodiments of the present invention relate to a water treatment apparatus that recovers dissolved compounds in water using a granular recovery agent.

  Depending on the dissolved compounds contained in the wastewater, eutrophication is involved, so there is a removal device for removing dissolved compounds. As a typical removal technique, a biological removal method or a removal method in which a chemical reaction is caused to aggregate and precipitate is known. In any method, it is necessary to further process the removed material as waste, and therefore, it is considered to reuse the removed material as a resource.

  As methods for recovering dissolved compounds, recovery agents that take in dissolved compounds with porous materials such as activated carbon, and recovery agents that selectively adsorb and fix specific substances so that the dissolved compounds can be easily reused are being studied. . A recovery agent that adsorbs and fixes a specific substance adsorbs dissolved compounds in wastewater by a chemical reaction. When the dissolved compound is recovered by such a method, the dissolved compound is generated as a crystalline salt on the surface of the recovery agent.

  A water treatment apparatus that treats wastewater handles a large amount of the recovery agent at a time, but if handled in a complicated manner, the crystal salt adsorbed on the surface layer may be peeled off. The crystal salt may grow secondarily with the peeled crystal salt as a nucleus. Such a crystal salt not only deteriorates the flow of the piping of the water treatment apparatus, but also causes a failure.

  There is a water treatment apparatus provided with a solid-liquid separation mechanism in order to collect fine particles generated in a reaction tank. There is also a water treatment apparatus provided with a cyclone for solid-liquid separation of particles mixed in the treated water discharged from the reaction tank. Furthermore, there is a resource recovery device that takes out an object by crystallization. This resource recovery apparatus includes a stirring device in a reaction layer, and recovers a product from the bottom.

JP 2004-321992 A

  By the way, when taking out the object by crystallization, ion control in the reaction vessel is important. When the degree of supersaturation in the reaction vessel increases, crystal nuclei (fine particles) are generated even without a seed. This fine particle not only lowers the recovery rate by flowing out downstream of the reaction vessel, but also raises a concern that it may cause clogging by growing crystals in the piping and subsequent processes. Accordingly, there is a need for a water treatment apparatus including a recovery apparatus that can reduce the risk of generating fine products and can be stably operated.

  In order to collect all the fine particles such as crystal nuclei, it is necessary to provide an inclination at an angle larger than the angle of repose of the target particles at the bottom of the reaction vessel. Increasing the angle of repose means that the bottom becomes a funnel shape, so that the reaction tank becomes higher and the position of the center of gravity increases. As a result, a large installation area is required to install the reaction tank safely, and the installation cost as a water treatment facility is increased.

  Then, this invention provides the water treatment apparatus which discharges | emits efficiently the collection | recovery agent which adsorb | sucked the dissolved compound from the reaction tank.

  A water treatment apparatus according to an embodiment includes a reaction tank, a water injection port, a recovery agent input device, a discharge port, an introduction port, and a recovery port. The reaction vessel has a cylindrical side wall and a gently angled bottom wall. The water injection port supplies the treated agent containing the dissolved compound into the reaction tank, and the recovery agent charging device supplies the granular recovery agent that adsorbs the dissolved compound to the reaction tank. A discharge port takes out to-be-processed water from a position higher than the collection | recovery agent settled to the bottom part of the reaction tank. The introduction port allows a part of the water to be treated taken out from the reaction tank to flow in the tangential direction of the side wall of the reaction tank. The recovery port is opened at the bottom of the bottom wall of the reaction tank.

Schematic of the water treatment apparatus of a 1st embodiment. The horizontal sectional view which passes along the water inlet of the reaction tank shown in FIG. Schematic of the valve mechanism installed in the collection | recovery port of the reaction tank shown in FIG. The figure which shows the relationship between the operation time of the stirrer shown in FIG. 1, and stirring intensity.

  The water treatment apparatus 100 of 1st Embodiment is demonstrated with reference to FIGS. 1-4. A water treatment apparatus 100 according to the first embodiment shown in FIG. 1 is applied to the treatment of wastewater containing organic water pollutants such as sewage and industrial wastewater from food processing plants, and is a dissolved compound that becomes a useful resource in wastewater. In order to collect the above, a collection device 10 and a pretreatment device 101 are provided. A water treatment apparatus 100 shown in FIG. 1 includes a biological wastewater treatment apparatus such as an activated sludge method upstream of the range illustrated in the treatment process, and generates organic waste liquid and sludge. The water treatment apparatus 100 treats this organic waste liquid and sludge in a post-process, and selectively collects the dissolved compounds of useful resources in the wastewater generated by the collection apparatus 10 shown in FIG. The pretreatment device 101 is installed upstream of the recovery device 10, and wastewater that has been treated upstream flows into the pretreatment device 101. The pretreatment apparatus 101 is installed to settle and separate suspended substances (SS) in waste water. The supernatant liquid, which is the waste water from which the suspended matter is settled and separated, is supplied to the recovery device 10 as the treated water Ws.

  As shown in FIG. 1, the recovery device 10 includes a reaction tank 11, a water injection port 12, a recovery agent input device 13, a discharge port 151, an introduction port 161, and a recovery port 113. In this embodiment, a stirrer 14, a drainage channel 15, a circulation channel 16, and a valve mechanism 17 are further provided. The reaction tank 11 has a cylindrical side wall 111 and a bottom wall 112 with a gentle angle that protrudes downward. In the present embodiment, the bottom wall 112 is formed in a hemispherical shape or a semi-elliptical shape connected to the lower end of the side wall 111 as shown in FIG. The bottom wall 112 may have a conical surface convex downward, a so-called mortar shape.

  The water injection port 12 is provided in the upper part of the side wall 111 and supplies the water to be treated Ws treated by the pretreatment device 101 to the reaction tank 11. The treated water Ws to be supplied is filled in the reaction tank 11 up to the liquid level WH lower than the water inlet 12. Supply or stop of the water to be treated Ws is controlled by a water injection valve 121 installed between the pretreatment device 101 and the water injection port 12.

  The recovery agent charging device 13 is installed above the reaction tank 11 and supplies the recovery agent S to the reaction tank 11 in conjunction with the control of the water injection valve 121. The recovery agent S is a material formed into a granular shape that adsorbs and fixes a dissolved compound on its surface by crystallization, chemical reaction, ion exchange, or the like. The settling rate of the recovery agent S in the water to be treated Ws is determined according to the particle size. Here, the sedimentation speed means the time until the recovery agent S suspended in the water to be treated Ws sinks to the bottom of the reaction tank 11. Therefore, the fast sedimentation speed means that the time for collecting the recovery agent S in the water to be treated Ws is short, and the slow sedimentation speed means that the time for collecting the recovery agent S in the water to be treated Ws is long. Means that.

  In order to properly control the contact time with the water to be treated Ws, that is, the time that contributes to adsorbing the dissolved compounds in the water to be treated Ws, the recovery agent S is classified and adjusted to have a uniform particle size. Is adopted. As an example of the physical quantity of the recovery agent S, the particle size is 0.5 to 2.0 mm, the average value is 1.0 to 1.5 mm, and the specific gravity is about 1.5 to 3.0 mm. The main component of the recovery agent S is one that can be easily treated when the recovered dissolved compound is recycled, such as one that can be easily separated if separation is necessary, or one that can be used as is if there is no harm in use. Selected.

  The stirrer 14 includes a rotary blade 141, a drive device 142, and a drive shaft 143. The rotary blade 141 is located at a position lower than the liquid level WH of the water to be treated Ws stored in the reaction tank 11, in this embodiment, the upper limit when the recovered agent S supplied to the reaction tank 11 settles to the bottom. It is arranged between the level SH and the liquid level WH. The drive device 142 is disposed above the reaction tank 11 and is connected to the rotary blade 141 by a drive shaft 143 to rotate the rotary blade 141. The rotating blade 141 causes the water to be treated Ws to flow downward by being rotated.

  When the rotational speed of the rotary blade 141 is higher than a certain speed, that is, when the downward flow is strong, the treated water Ws that has gone downward has the recovered wall T on the bottom wall 112 to the outer peripheral side than the rotary blade 141. While winding up, an annular circulation flow Vs is formed along the torus surface with the drive shaft 143 as the center. In addition, when the rotational speed of the rotary blade 141 is slower than a certain speed, that is, when the flow for directing the treated water Ws downward to the extent that the collected agent S is not wound up is weak, the collected agent floating in the treated water Ws. S gradually settles to the bottom of the reaction tank 11 due to its specific gravity.

  The drainage flow path 15 pumps out the to-be-processed water Ws after the recovery process of the dissolved compound is performed in the reaction tank 11. The drainage channel 15 has a discharge port 151 that communicates with the reaction tank 11. The discharge port 151 is provided at a position WL higher than the upper limit level SH of the recovery agent that has settled at the bottom of the reaction tank 11. In FIG. 1, the drainage flow path 15 is connected to a drainage tank 152 installed around the upper part of the reaction tank 11 and lower than the reaction tank. When the water to be treated Ws is discharged, the water to be treated Ws remains at the bottom of the reaction tank 11 in a range lower than the position of the recovery agent S that has adsorbed the dissolved compound and the position WL of the discharge port 151.

  The circulation channel 16 is a channel that connects the drain tank 152 and the reaction tank 11 and returns a part of the water to be treated Ws stored in the drain tank 152 to the reaction tank 11. The circulation channel 16 has an inlet 161 connected to the side wall 111 of the reaction tank 11 and a pump 162 that pumps the water to be treated Ws from the drain tank 152. As shown in FIG. 2, the inlet 161 is installed at the upper limit level SH of the recovered recovery agent S, and allows the water to be treated Ws to flow in the tangential direction along the inner peripheral surface of the side wall of the reaction tank 11. In the present embodiment, the inlet 161 is provided in the vicinity of the boundary between the side wall 111 and the bottom wall 112.

  As shown in FIGS. 1 and 3, the recovery port 113 is opened at a position that is the lowest part of the bottom wall 112 of the reaction tank 11. As shown in FIG. 3, when the recovery port 113 is opened while the water to be treated Ws is stored in the reaction tank 11, the recovery port 113 maintains the state opened by buoyancy, and the water to be treated Ws. It has a valve mechanism 17 that is closed when the water level falls below a certain level.

  When the valve mechanism 17 is opened, the recovery agent S is discharged from the recovery port 113 together with the water to be treated Ws. At this time, in order to maintain the fluidity of the recovery agent S, the water to be treated Ws of the drainage tank 152 is introduced from the introduction port 161 in a tangential direction along the inner surface of the side wall of the reaction tank 11. As shown in FIG. 2, the treated water Ws introduced introduces the recovery agent S while swirling along the inner surface of the side wall 111 of the reaction tank 11, and does not leave the recovery agent S remaining at the bottom of the reaction tank 11. Wash away.

  Therefore, the bottom wall 112 of the reaction tank 11 may be inclined at an angle smaller than the angle of repose with respect to the recovery agent S. The bottom wall 112 of the reaction tank 11 shown in FIG. 1 has a hemispherical shape, and therefore the periphery of the recovery port 113 is substantially substantially horizontal at an angle smaller than the repose angle. Even in such a case, since the inlet 161 introduces the water to be treated Ws in the tangential direction, even if the recovery agent S is left on the bottom wall in the range formed at an angle smaller than the angle of repose, It can be discharged from the recovery port 113 by the treated water Ws.

  The treated water Ws supplied to the reaction tank 11 from the inlet 161 in order to wash away the recovery agent S is the treated water Ws stored in the drain tank 152, and after the treatment for recovering the dissolved compound in the reaction tank 11. The water quality after the dissolved compound is adsorbed and fixed to the recovery agent S, that is, the water quality of the ion balance suitable for maintaining a stable state in which the dissolved compound is not dissolved and eluted. It is. Therefore, the dissolved compound adsorbed on the recovery agent S can be efficiently recovered by using the water to be treated Ws in the drainage tank 152.

  Since the bottom wall 112 is formed in a hemispherical shape or a semi-elliptical shape, the connection from the side wall 111 to the bottom wall 112 becomes smooth. Since the to-be-processed water Ws which flowed into the reaction tank 11 from the introduction port 161 smoothly moves from the swirling flow along the side wall 111 to the swirling flow along the bottom wall 112, the momentum due to the water flow is maintained. Therefore, the recovery agent S can be effectively discharged from the recovery port 113 even with a small amount of water. Moreover, since the bottom wall 112 can be set to an angle smaller than the angle of repose with respect to the recovery agent S, the reaction vessel 11 can be lowered. Since the position of the center of gravity of the reaction vessel 11 is lowered, the stability is good and the area occupied by the installation can be reduced.

  In the recovery apparatus 10 of the water treatment apparatus 100 of this embodiment, the stirrer 14 can stir the treated water Ws and the recovery agent S in the reaction tank 11 with at least two stages of stirring intensity. In the present embodiment, since the recovery agent S adjusted so that the particle size is in a certain range is adopted, the stirring strength when being wound up by the flow of the water to be treated Ws, and the recovery agent S are treated. The sedimentation speed when sedimenting in the water Ws is stable. That is, since it is easy to control the diffusion and settling of the recovery agent S in the water to be treated Ws and the recovery agent S can be brought into homogeneous contact with the water to be treated Ws, the time for treating the water to be treated Ws is set. It's easy to do.

  When the dissolved compound is adsorbed and fixed on the surface of the recovery agent S based on a chemical reaction such as crystallization or ion exchange, the reaction rate is limited. Excessive stirring not only hinders or accelerates the chemical reaction on the surface of the recovery agent S, but also causes the dissolved compound to become supersaturated, thereby precipitating a crystalline salt of the dissolved compound and using this as a nucleus. May generate grown fine particles. Therefore, in the present embodiment, as shown in FIG. 4, the rotating blade 141 is rotated so as to alternately repeat rapid stirring A1 having a high stirring strength and slow stirring A2 having a low stirring strength.

  In the rapid stirring A1, most of the recovery agent S in the reaction tank 11 is wound up by the flow created by the rotary blade 141 and floats in the water to be treated Ws. That is, the stirring intensity of the rapid stirring A1 exceeds the total stirring state Ma in which the recovery agent S is evenly diffused in the water to be treated Ws as shown in FIG. Further, in the slow stirring A2, the recovery agent S in the reaction tank 11 settles without being rolled up from the bottom. That is, the stirring intensity of the slow stirring A2 is weaker than the floating limit Mb that makes it impossible to keep the recovered agent S wound up and suspended from the bottom of the reaction tank 11 as shown in FIG. If the stirring strength is too strong, the layer of the dissolved compound formed on the surface may be destroyed due to collision of the recovery agents S. Therefore, the stirring strength of the rapid stirring A1 is set to a stirring strength that does not exceed the stirring limit Mc, which is the stirring strength for peeling the dissolved compound from the recovery agent S.

  The time interval at which the rapid stirring A1 and the slow stirring A2 are repeated varies depending on the time until the recovery agent S wound up in the rapid stirring A1 settles in the slow stirring A2. The operation pattern shown in FIG. 4 that repeats the rapid stirring A1 and the slow stirring A2 is merely an example, but the ratio of the operating time of the slow stirring A2 to the operating time of the rapid stirring A1 is about 1 to 3. Good. The recovery rate of the dissolved compound in the water to be treated Ws is improved by continuously increasing the stirring strength stepwise and repeating the sales and settling of the recovery agent S for a certain period of time. The ratio of operation time can also vary depending on the composition and physical quantity of the recovery agent S, the dissolved compound to be collected, the temperature of the water to be treated Ws, the physical quantity of the water to be treated Ws such as the concentration of dissolved compound, and the like.

  Since the water treatment apparatus 100 of this embodiment is equipped with the stirrer 14 in the reaction tank 11 of the collection apparatus 10, the collection agent S and the water to be treated Ws can be mixed gently and uniformly. Therefore, even when the recovery agent S of the type in which the dissolved compound is crystallized on the surface is used, it is possible to suppress the crystallization of the crystallized product salt. That is, the crystal of the generated salt is prevented from further growing using the peeled crystal as a nucleus.

  A number of embodiments of the invention have been described. These embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 100 ... Water treatment apparatus, 101 ... Pretreatment apparatus, 10 ... Collection | recovery apparatus, 11 ... Reaction tank, 111 ... Side wall, 112 ... Bottom wall, 113 ... Collection port, 12 ... Water injection port, 13 ... Collection | recovery agent input apparatus, 14 ... Stirrer 141 ... Rotating blade 151 ... Discharge port 161 ... Inlet port 17 ... Valve mechanism Ws ... Water to be treated, S ... Recovery agent, A1 ... Quick stirring, A2 ... Slow stirring.

Claims (7)

A reaction vessel having a cylindrical side wall and a gently angled bottom wall;
A water inlet for supplying water to be treated containing dissolved compounds in the reaction tank;
A recovery agent charging device for supplying a granular recovery agent that adsorbs the dissolved compound to the reaction tank;
A discharge port for taking out the water to be treated from a position higher than the recovery agent settled at the bottom of the reaction tank;
An inlet through which a part of the water to be treated taken out from the reaction tank flows in a tangential direction of the side wall of the reaction tank;
A recovery port opened at the bottom of the bottom wall of the reaction vessel;
A water treatment apparatus comprising: The water treatment apparatus according to claim 1, wherein the bottom wall is inclined at an angle smaller than an angle of repose with respect to the recovery agent. The recovery port maintains a state opened by buoyancy when the water to be treated is stored in the reaction tank, and is closed when the water to be treated is below a certain water level. The water treatment apparatus according to claim 1, further comprising a valve mechanism. The water according to any one of claims 1 to 3, further comprising a stirrer that stirs the water to be treated and the recovery agent stored in the reaction tank with at least two stages of stirring intensity. Processing equipment. 5. The water treatment apparatus according to claim 4, wherein the stirrer includes a rotary blade that alternately repeats rapid stirring with high stirring strength and slow stirring with low stirring strength. In the rapid stirring, the recovery agent is diffused into the treated water by the rotor blades,
6. The water treatment apparatus according to claim 4, wherein, in the slow stirring, the recovery agent settles to the bottom of the reaction tank even if the rotor blades rotate. The water treatment device according to any one of claims 1 to 6, further comprising a pretreatment device that is installed upstream of the water injection port and settles and separates suspended substances in the water to be treated.

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