JP2015226873A - Method of treating wastewater containing aldehydes - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable efficient reuse of formaldehyde-containing wastewater by removing formaldehyde from the wastewater.SOLUTION: Wastewater from a retort apparatus 2 is stored in a first storage tank 210 and circulated to a circulation path 240. A sulfite salt is added to the circulating wastewater from a first chemical feeder 243 to perform reaction to obtain processed water containing hydroxymethanesulfonate ions converted from formaldehyde in the wastewater. A pH adjusting agent is properly added from a second chemical feeder 244 during the reaction to maintain the pH of the formaldehyde-containing wastewater at less than 7. The processed water is supplied from the first storage tank 210 to a reverse osmosis membrane device 320 through a communication path 310 to be filtered, and permeate from which the hydroxymethanesulfonate ions have been removed is returned to the retort apparatus 2 to be reused. In the reverse osmosis membrane device 320, the recovery rate of the permeate is set based on an electrical conductivity E1 of the wastewater stored in the first storage tank 210 to suppress scale generation.

Description

  The present invention relates to a method for treating aldehyde-containing wastewater, and more particularly, to a treatment method for reusing aldehyde-containing wastewater from a wastewater source in the wastewater source.

  A retort device, a paste rise device (sometimes referred to as a paste riser or a pasteurization device) and a container cleaning device (hereinafter also referred to as a “retort device or the like”) used in food factories or beverage factories, etc. A large amount of expensive tap water is used in comparison with industrial water due to food hygiene requirements, and reuse of wastewater is required from the viewpoint of cost reduction by water saving.

  However, the waste water from the retort device or the like may contain aldehydes, and typically has a concentration exceeding 0.08 mg / L, which is the water quality standard of tap water, although it is a small amount of about 1 to 5 mg / L. Contains formaldehyde as an impurity. This formaldehyde is considered to elute from organic materials such as resin materials used for containers filled with foods and beverages and printing paints for various displays, and it is necessary to remove the wastewater for reuse. However, since formaldehyde has a low molecular weight, it is difficult to separate from waste water because it easily permeates through the separation membrane even when the waste water is filtered using a high-precision separation membrane such as a reverse osmosis membrane.

  Therefore, as a method for removing aldehydes such as formaldehyde contained in waste water from a retort device or the like, a method has been proposed in which sulfite is added to the waste water and then the waste water is subjected to membrane treatment with a reverse osmosis membrane device (Patent Document 1). ). In this membrane treatment method, the sulfite added to the wastewater generates hydroxymethanesulfonate ions, which are a kind of α-hydroxysulfonate ions, by reaction with formaldehyde in the wastewater. Hydroxymethanesulfonate ions have a molecular weight greater than that of formaldehyde and are negatively charged in the wastewater, so that they do not easily pass through the reverse osmosis membrane and are separated from the wastewater. As a result, the wastewater that has permeated through the reverse osmosis membrane device can effectively remove formaldehyde and be reusable in the retort device.

  The above membrane treatment method using a reverse osmosis membrane device is economical because the amount of wastewater that can be reused increases by increasing the recovery rate in the reverse osmosis membrane device, but from the retort device etc. Since the wastewater contains a hardness component and a scale-generating component such as silica together with aldehydes, increasing the recovery rate tends to clog the membrane surface due to the generation of scale, and the filtration efficiency decreases. Therefore, in a filtration method using a semipermeable membrane separation device such as a reverse osmosis membrane device, usually the hardness component of water supplied to the semipermeable membrane separation device and the concentration of silica or the like are evaluated by measuring electrical conductivity or the like. The recovery rate is varied according to the evaluation result (for example, Patent Document 2 and Patent Document 3). That is, when the concentration is high, the recovery rate is lowered because the scale tends to be generated on the film surface, and conversely, when the concentration is low, the scale tends to be difficult to generate on the film surface. The recovery rate is increased.

  However, in the membrane treatment method described in Patent Document 1, the water supplied to the reverse osmosis membrane device contains α-hydroxysulfonic acid ions and unreacted sulfite generated by the above reaction in addition to the scale-generating component. However, depending on the electrical conductivity, it is difficult to determine the exact concentration of the scale-generating component. Therefore, if the recovery rate in the reverse osmosis membrane device is controlled according to the electrical conductivity of the feed water to the reverse osmosis membrane device, the recovery rate has to be set low from the viewpoint of increasing the reliability of scale suppression, In this case, it is inevitably necessary to dispose of a considerable amount of waste water from the retort device or the like, and it is difficult to achieve efficient reuse of waste water.

JP 2014-12281 A JP 2003-145151 A JP 2006-305499 A

  In the case where the aldehyde-containing wastewater from the drainage source such as the retort device is filtered by the reverse osmosis membrane device and reused in the drainage source, the aldehyde-containing wastewater is suppressed while suppressing the scale formation in the reverse osmosis membrane device. Is intended to be able to be reused efficiently.

  The present invention relates to a treatment method for reusing aldehyde-containing wastewater from a water source at the wastewater source. In this treatment method, sulfite is added to aldehyde-containing wastewater from a wastewater source, and process water is obtained by reacting in an environment having a pH of less than 7, and processing water is sent to a reverse osmosis membrane device and filtered. And a processing step including a step B of obtaining permeated water from the reverse osmosis membrane device. In this treatment method, the electrical conductivity E of the aldehyde-containing wastewater before the addition of sulfite is measured, and when the electrical conductivity E is relatively low, the recovery rate of the permeated water from the reverse osmosis membrane device is relative. If the electrical conductivity E is relatively high, the permeate recovery rate in step B is adjusted based on the electrical conductivity E so that the permeate recovery rate from the reverse osmosis membrane device is relatively low. To do.

  In the present application, the term “sulfite” is used as a general term for sulfite and bisulfite, except when used with the intention of excluding bisulfite.

  In Step A, aldehydes contained in the aldehyde-containing wastewater from the wastewater source are reacted with sulfite to be converted into α-hydroxysulfonic acid ions, whereby processed water containing the α-hydroxysulfonic acid ions is obtained. In step B, α-hydroxysulfonic acid ions contained in the processed water are removed by the reverse osmosis membrane device. Therefore, in the process B, the permeated water from which the α-hydroxysulfonic acid ions derived from the aldehydes contained in the aldehyde-containing wastewater are removed, that is, the permeated water from which the aldehydes are removed is obtained.

  Here, the recovery rate of the permeated water from the reverse osmosis membrane device is adjusted based on the electrical conductivity E of the aldehyde-containing wastewater before adding sulfite in the process A. Electrical conductivity E reflects the concentration of components that cause scale formation in reverse osmosis membrane devices contained in aldehyde-containing wastewater, and reflects α-hydroxysulfonate ions and unreacted sulfites that are not involved in scale generation. In step B, the recovery rate is adjusted based on the concentration of the scale generation component. That is, in the process B, the recovery rate is not adjusted in consideration of the component concentration unrelated to the scale generation. Therefore, the recovery rate can be increased, and thereby more permeated water can be obtained.

  In one aspect of the treatment method of the present invention, in the treatment step, the aldehyde-containing wastewater from the wastewater source is sequentially supplied to a plurality of water storage tanks, and the process A is executed, and the reverse osmosis membrane device is sequentially processed from the water storage tank. As the water storage tank for supplying the aldehyde-containing wastewater in the process A, the water storage tank in which the process water is supplied to the reverse osmosis membrane device among the plurality of water storage tanks is executed in the process A. Reuse.

  In this embodiment, the electrical conductivity E is measured for the aldehyde-containing wastewater for each of the plurality of water tanks, and the aldehydes contained in the process A are supplied to the reverse osmosis membrane device in the process B. It is preferable to adjust the permeate recovery rate in step B based on the electrical conductivity E of the waste water. In this case, for example, the electrical conductivity E 'of the aldehyde-containing wastewater that is being supplied from the drainage source to the water tank is measured at regular intervals, and the moving average value of the electrical conductivity E' is obtained to determine the electrical conductivity E '. Can be measured.

  In the treatment method of the present invention, for example, the permeate recovery rate in step B is adjusted based on a relationship table that summarizes the electrical conductivity E and the permeate recovery rate to be set for the value. be able to. In step A, the pH is preferably adjusted to 6.0 or more and 6.5 or less.

  In the treatment method of the present invention, when treating aldehyde-containing wastewater containing 1 to 5 mg / L of formaldehyde, 2 to 6 molar equivalents of sulfite having a concentration of formaldehyde is added to the aldehyde-containing wastewater in Step A. When the reaction time of at least 15 minutes is ensured and the recovery rate of the permeated water is adjusted in the range of 60 to 95% based on the electric conductivity E in Step B, the residual formaldehyde concentration is 0.08 mg / L or less. And the permeated water whose total organic carbon amount is 3.0 mg / L or less can be obtained.

  The present invention according to another aspect relates to a treatment system for reusing aldehyde-containing wastewater from a wastewater source at the wastewater source. The treatment system stores aldehyde-containing wastewater from a wastewater source, and a storage tank for obtaining processed water by adding sulfite to the stored aldehyde-containing wastewater and reacting in an environment having a pH of less than 7. A reverse osmosis membrane device for filtering processed water from the water storage tank to obtain permeated water and a control unit are provided. The control unit measures the electrical conductivity E of the aldehyde-containing wastewater, and when the electrical conductivity E is relatively low, the permeated water recovery rate from the reverse osmosis membrane device is relatively increased, and the electrical conductivity E is In order to lower the permeate recovery rate from the reverse osmosis membrane device when it is relatively high, the permeate recovery rate in the reverse osmosis membrane device is adjusted based on the electrical conductivity E. .

  In this treatment system, aldehydes contained in aldehyde-containing wastewater from a wastewater source stored in a water tank are converted to α-hydroxysulfonate ions by adding sulfite and reacting in an environment having a pH of less than 7. Therefore, the processed water obtained in the water storage tank contains the α-hydroxysulfonic acid ion. Then, the reverse osmosis membrane device removes α-hydroxysulfonic acid ions from the processed water by filtering the processed water from the water storage tank. Therefore, in the reverse osmosis membrane device, permeated water from which α-hydroxysulfonic acid ions derived from aldehydes contained in the aldehyde-containing wastewater are removed, that is, permeated water from which aldehydes have been removed is obtained.

  Here, a control part adjusts the collection | recovery rate of the permeated water in a reverse osmosis membrane apparatus based on the electrical conductivity E measured about the aldehyde containing waste water. Electrical conductivity E reflects the concentration of components that cause scale formation in reverse osmosis membrane devices contained in aldehyde-containing wastewater, and reflects α-hydroxysulfonate ions and unreacted sulfites that are not involved in scale generation. Therefore, the control unit adjusts the recovery rate based on the scale generation component concentration. That is, the control unit does not adjust the recovery rate in consideration of the component concentration unrelated to the scale generation, so that the recovery rate can be increased, and thereby more permeated water can be obtained.

  One form of the treatment system of the present invention includes a plurality of water storage tanks, and further includes a supply path for sequentially supplying aldehyde-containing waste water from a drainage source to an empty one of the plurality of water storage tanks. The plurality of water storage tanks can sequentially send processed water to the reverse osmosis membrane device.

  In this embodiment, the control unit measures the electrical conductivity E of the aldehyde-containing wastewater for each water tank, and supplies the processed water to the reverse osmosis membrane device from the supply path to the water tank in water. Based on the electrical conductivity E, the permeated water recovery rate in the reverse osmosis membrane device is adjusted. In this case, the control unit measures the electrical conductivity E ′ of the aldehyde-containing wastewater that is being supplied from the supply channel to the water tank at regular intervals, and obtains a moving average value of the electrical conductivity E ′. The rate E can be measured.

  In the treatment system of the present invention, the control unit includes, for example, a relational table that summarizes the electrical conductivity E and the permeate recovery rate to be set for the value, and the permeation based on this relational table is provided. Adjust water recovery. In the water storage tank, it is preferable to adjust the pH to 6.0 or more and 6.5 or less so that the processed water is obtained by reacting the sulfite.

  When the treatment system of the present invention treats aldehyde-containing wastewater containing 1 to 5 mg / L of formaldehyde, 2 to 6 molar equivalents of sulfite having a concentration of formaldehyde is added to the aldehyde-containing wastewater in the water storage tank. And at least 15 minutes of reaction time, and the control unit is set to adjust the recovery rate of the permeated water in the range of 60 to 95% based on the electric conductivity E. Is 0.08 mg / L or less, and permeated water having a total organic carbon content of 3.0 mg / L or less can be obtained.

  The drainage source of aldehyde-containing wastewater to which the treatment method and treatment system of the present invention can be applied is, for example, a retort device, a paste rise device, or a container cleaning device.

  According to the method and system for treating aldehyde-containing wastewater according to the present invention, aldehydes can be effectively removed from aldehyde-containing wastewater, and permeated water can be suppressed while suppressing scale generation in the reverse osmosis membrane device. Since the recovery rate can be increased, the aldehyde-containing wastewater can be reused efficiently.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic of one Embodiment of the processing system of the aldehyde containing wastewater which concerns on this invention. The partial figure of the operation | movement flowchart of the said form. The partial figure of the operation | movement flowchart of the said form. The partial figure of the operation | movement flowchart of the said form. The partial figure of the operation | movement flowchart of the said form. The partial figure of the operation | movement flowchart of the said form.

  With reference to a figure, the one form of the processing system of the aldehyde content drainage concerning the present invention is explained. In the figure, the processing system 1 is for reusing aldehyde-containing wastewater discharged from a retort device 2 (an example of a wastewater source) in the retort device 2, for example, an outward path 100 extending from the retort device 2, reaction Unit 200, filtration unit 300, return path 400, and control unit 500.

  The retort device 2 mainly includes a retort pot 20, a relay tank 30, and a water receiving tank 40. The retort kettle 20 is for sterilizing wet foods and beverages, such as bagging and canning, which are hermetically filled in a container, with pressurized hot water. The relay tank 30 is for temporarily storing drainage from the retort kettle 20, and a drainage channel 22 extending from the retort kettle 20 is in communication therewith. The water receiving tank 40 is for supplying hot water and cooling water in the retort kettle 20 while storing them, and has a water replenishment channel 41 and a water level sensor (not shown), and is connected to the retort kettle 20. An extending water supply path 42 is provided. The supplementary water channel 41 has an on-off valve (not shown) for controlling the supply of tap water. This open / close valve replenishes tap water by being in an open state until the water level sensor is activated, and stops replenishment of tap water by being in a closed state by actuation of the water level sensor. The water supply path 42 has a water supply pump 43 for sending water stored in the water receiving tank 40 to the retort kettle 20.

  The forward path 100 is a path for sending waste water from the retort device 2 to the reaction unit 200, and extends from the relay tank 30. The first pump 110, the cooling device 120, and the electrical conductivity sensor 130 are sequentially from the relay tank 30 side. have.

  The first pump 110 is for sending out the wastewater stored in the relay tank 30 to the forward path 100. The cooling device 120 is for cooling the waste water from the relay tank 30. For example, several cooling cooling towers are installed in parallel to increase the waste water treatment efficiency. The electrical conductivity sensor 130 is for continuously measuring the electrical conductivity of the wastewater sent from the relay tank 30 to the reaction unit 200 at regular intervals (for example, every 100 milliseconds).

  The end portion of the outward path 100 branches into three systems of a first supply path 160, a second supply path 170, and a third supply path 180 and communicates with the reaction unit 200. Each of the first supply path 160, the second supply path 170, and the third supply path 180 has an open / close valve (not shown). By switching the opening / closing of these open / close valves, water is supplied to the reaction unit 200. It can be controlled.

  The reaction unit 200 has three tanks with the same capacity for storing the waste water from the forward path 100, that is, the first water tank 210, the second water tank 220, and the third water tank 230, And a drainage circulation path 240.

  The first water tank 210 communicates with a first supply path 160, and a first discharge path 211 having an on-off valve (not shown) extends. The first water tank 210 includes a high water level sensor S1H that operates when a required amount of wastewater is stored, and a low water level sensor S1L that operates when the stored wastewater is discharged and becomes substantially empty. Have.

  The second water storage tank 220 communicates with the second supply path 170, and a second discharge path 221 having an on-off valve (not shown) extends. The second water tank 220 includes a high water level sensor S2H that operates when a required amount of wastewater is stored, and a low water level sensor S2L that operates when the stored wastewater is discharged and becomes substantially empty. Have.

  The third water tank 230 communicates with the third supply path 180, and a third discharge path 231 having an on-off valve (not shown) extends. The third water tank 230 includes a high water level sensor S3H that operates when a required amount of wastewater is stored, and a low water level sensor S3L that operates when the stored wastewater is discharged and becomes substantially empty. Have.

  The circulation path 240 is for circulating the wastewater stored in the first water tank 210, the second water tank 220, or the third water tank 230, and extends from the first water tank 210 and is an on-off valve (not shown). A first feed passage 212 having a second, a second feed passage 222 extending from the second water storage tank 220 and having an on-off valve (not shown), and an extension valve from the third water storage tank 230 having an on-off valve (not shown). The third feed channel 232 communicates, and also has an on-off valve (not shown) and a first return channel 213 that communicates with the first reservoir 210, an on-off valve (not shown), and a first The second return flow path 223 communicating with the second water storage tank 220 and the third return flow path 233 having an on-off valve (not shown) and communicating with the third water storage tank 230 are branched.

  The circulation path 240 includes a circulation pump 241, a pH sensor 242, a first chemical injection device 243, and a second chemical injection device 244. The circulation pump 241 is for feeding the wastewater stored in the first water tank 210, the second water tank 220 or the third water tank 230. The pH sensor 242 is for measuring the pH of the waste water circulating through the circulation path 240.

  The 1st chemical injection device 243 is for adding sulfite with respect to the drainage which circulates through circulation path 240, and can adjust the addition amount of sulfite. The sulfite added by the first chemical injection device 243 is not particularly limited as long as it can generate α-hydroxysulfonic acid ions by reacting with aldehydes in the aqueous phase, and is usually an alkali metal. (Preferably sodium) sulfite and bisulfite. As the sulfite, a mixture of sulfite and bisulfite can also be used. It is preferable that sulfite is normally added from the 1st chemical injection apparatus 243 in the state of aqueous solution.

  The second chemical injection device 244 is for adjusting the pH of the wastewater that circulates in the circulation path 240 by supplying the pH adjuster, and is used for adjusting the pH of the circulated wastewater (for example, hydroxylation). An alkali metal hydroxide such as sodium or potassium hydroxide) or a regulator for lowering pH (for example, hydrochloric acid or sulfuric acid) can be selectively added.

  The filtration unit 300 is for filtering the waste water from the reaction unit 200, and mainly includes a communication path 310 having a second pump 311 and a reverse osmosis membrane device 320.

  The communication path 310 is connected to the first discharge path 211 from the first water tank 210, the second discharge path 221 from the second water tank 220, and the third discharge path 231 from the third water tank 230, and vice versa. It extends to the osmotic membrane device 320. The second pump 311 is a pressurizing pump that pumps waste water toward a reverse osmosis membrane module 321 described later.

The reverse osmosis membrane device 320 includes a reverse osmosis membrane module 321 and a drainage channel 322. The reverse osmosis membrane module 321 includes one or a plurality of reverse osmosis membrane elements (not shown), and a communication path 310 communicates with the inlet side. The reverse osmosis membrane forming the reverse osmosis membrane element has a negatively charged skin layer using a cross-linked wholly aromatic polyamide or the like, that is, a skin layer that tends to be negatively charged, preferably operating pressure. The water permeability coefficient is 1.3 × 10 ^{−11 to} 1.7 × 10 ⁻ when a sodium chloride aqueous solution having a concentration of 500 mg / L, pH 7.0 and temperature of 25 ° C. is supplied under the conditions of 0.7 MPa and a recovery rate of 15%. ¹¹ m ³ · m ^-2 · s ^-1 · Pa ^-1 and a salt removal rate of 99% or more.

Here, the operating pressure refers to the average operating pressure defined in Japanese Industrial Standard JIS K3802: 1995 “Membrane Terminology”, and here, the primary side inlet pressure and the primary side outlet pressure of the reverse osmosis membrane module 321 The average value of The recovery rate refers to the ratio (%) of the flow rate (B) of the permeated water to the flow rate (A) of water supplied to the reverse osmosis membrane module 321 (that is, B / A × 100). The water permeation coefficient is a value obtained by dividing the amount of permeated water (m ³ / s) by the membrane area (m ² ) and the effective pressure (Pa), and is an index indicating the permeation performance of water through the reverse osmosis membrane. That is, the water permeation coefficient means the amount of water that permeates the unit area of the membrane per unit time when a unit effective pressure is applied. The effective pressure is defined in Japanese Industrial Standard JIS K3802: 1995 “Membrane Term”, and is a pressure obtained by subtracting the osmotic pressure difference and the secondary pressure from the operating pressure (average operating pressure). The salt removal rate is a value calculated from the concentration of specific salts before and after permeating the membrane, and is an index indicating the solute blocking performance in the reverse osmosis membrane. The salt removal rate is calculated as (1-C ₂ / C ₁ ) × from the concentration (C ₁ ) of specific salts in water supplied to the reverse osmosis membrane module 321 and the concentration (C ₂ ) of specific salts in permeated water. 100.

A reverse osmosis membrane having the above-described skin layer and properties is commercially available as a reverse osmosis membrane element. As such a reverse osmosis membrane element, for example, model name “TMG20-400” manufactured by Toray Industries, Ltd. (water permeability coefficient under the above conditions is 1.7 × 10 ⁻¹¹ m ³ · m ⁻² · s ⁻¹ · Pa ⁻¹ ), model name “RE8040-BLN” manufactured by Unjin Chemical Co., Ltd. (water permeability coefficient under the above conditions is 1.6 × 10 ⁻¹¹ m ³ · m ⁻² · s ⁻¹ · Pa ⁻¹ ) and “ESPA1” manufactured by Nitto Denko Corporation (water permeability coefficient under the above conditions is 1.6 × 10 ⁻¹¹ m ³ · m ⁻² · s ⁻¹ · Pa ⁻¹ ) and the like.

  The drainage channel 322 is a path for discharging the concentrated water generated in the reverse osmosis membrane module 321 from the reverse osmosis membrane module 321 and includes a return path 323 and a drainage control valve 324 in this order from the reverse osmosis membrane module 321 side. ing.

  The return path 323 is for returning a part of the concentrated water from the reverse osmosis membrane module 321 to the connection path 310, branches from the drainage path 322, and communicates with the upstream side of the second pump 311. The drainage control valve 324 is for controlling the amount of concentrated water discarded from the reverse osmosis membrane module 321 and thereby adjusting the recovery rate of the permeated water from the reverse osmosis membrane module 321. The drainage control valve 324 has a mechanism for adjusting the flow rate stepwise, and is configured, for example, by connecting a plurality of on-off valves incorporating a water governor in parallel. In addition, a single proportional control valve can be used as the drainage control valve 324.

  The return path 400 is a path for returning the permeated water from the reverse osmosis membrane device 320 to the retort device 2, extends from the outlet side of the reverse osmosis membrane module 321, and communicates with the water receiving tank 40 of the retort device 2. The return path 400 includes a third chemical injection device 410 and a residual chlorine meter 420. The third chemical injection device 410 is for adding a hypochlorite aqueous solution (usually a sodium hypochlorite aqueous solution) to the permeated water from the reverse osmosis membrane module 321. The residual chlorine meter 420 is for measuring the residual chlorine concentration of the permeated water returned to the retort device 2.

  The control unit 500 is a computer for operating the processing system 1 in accordance with a predetermined operation program. The control unit 500 mainly includes a central processing unit, a read-only memory in which the operation program is recorded, and a random access memory in which various information can be recorded. And an input / output unit. On the input side of the input / output unit, operation commands to the electrical conductivity sensor 130, the high water level sensors S1H, S2H and S3H, the low water level sensors S1L, S2L and S3L, the pH sensor 242, the residual chlorine meter 420 and the processing system 1 are given. An operation panel 510 or the like for inputting is in contact. On the other hand, on the output side of the input / output unit, the first pump 110, the circulation pump 241, the second pump 311, the on-off valves of the reaction unit 200, the first chemical injection device 243, the second chemical injection device 244, the third chemical agent. The injection device 410, the drainage control valve 324, the operation status indicator 520 of the processing system 1, etc. are in communication.

  The control unit 500 is a reverse osmosis membrane module to be set based on the electrical conductivity E of the wastewater sent from the relay tank 30 to the reaction unit 200 measured by the electrical conductivity sensor 130 and the measured electrical conductivity E. The relationship table which prescribed | regulated the relationship with the collection | recovery rate of the permeated water from 321 is memorize | stored. Since the electrical conductivity of the wastewater increases in proportion to the concentration of the hardness component contained in the wastewater and the scale-generating component such as silica, wastewater with a high electrical conductivity is likely to generate scale on the membrane surface in the reverse osmosis membrane module 321. Conversely, wastewater with low electrical conductivity tends to hardly generate scale on the membrane surface in the reverse osmosis membrane module 321.

  For this reason, this relationship table shows that the permeated water recovery rate from the reverse osmosis membrane module 321 is relatively increased when the electrical conductivity E is relatively low, and the reverse osmosis when the electrical conductivity E is relatively high. The relationship between the electrical conductivity E and the recovery rate to be set in the case of the electrical conductivity E is specified so that the recovery rate of the permeated water from the membrane module 321 is relatively lowered. It is as shown in Table 1 below.

  In the retort device 2, tap water stored in the water receiving tank 40 is supplied to the retort kettle 20 through a water supply path 42 by a water supply pump 43. In the retort kettle 20, foods and beverages are sterilized by heat and humidity with pressurized hot water from the supplied tap water, and the sterilized food and beverages are cooled by using the supplied tap water as cooling water as it is. And the high temperature waste_water | drain from the retort pot 20 used as pressurized hot water or cooling water flows through the drainage channel 22, and is stored by the relay tank 30. FIG. The waste water from the retort kettle 20 stored in the relay tank 30 contains a trace amount of aldehydes, usually about 1 to 5 mg / L of formaldehyde.

  The aldehyde concentration in the wastewater stored in the relay tank 30 can be measured by an absorptiometric method (MBTH method) using 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH). This measurement can be carried out by installing a measuring instrument equipped with an MBTH addition device and an absorptiometer in the drainage channel 22 or the outward channel 100. The wastewater stored in the relay tank 30 is sampled in a timely manner. It can also be carried out by applying to a commercially available measurement kit. An example of a measurement kit that can be used for measuring the formaldehyde concentration in waste water is “Pack Test Formaldehyde” (model “WAK-FOR”) manufactured by Kyoritsu Riken Corporation.

  Further, the waste water from the retort kettle 20 includes a hardness component derived from tap water (that is, fresh water) supplied from the replenishment channel 41 to the water receiving tank 40 and a scale generating component such as silica, and the concentration thereof is the retort. It may vary depending on the operating status of the device 2. When the retort device 2 is operating continuously, the concentration of scale-generating components generally decreases with time due to the treatment and reuse of wastewater by the treatment system 1, but the quality of the tap water varies. If the amount of fresh water supplied to the retort device 2 increases (for example, when the retort device 2 is operated while repeatedly stopping and restarting in a relatively short time), the decreasing trend is likely to occur. The scale-generating component concentration may turn up. Therefore, when the scale generation component concentration of the waste water from the retort kettle 20 is evaluated by the electric conductivity, the electric conductivity of the waste water is, for example, a wide range of about 10 to 1,000 μS / cm due to the variation of the scale generation component concentration. Can vary.

  Thus, since the scale generation component concentration may fluctuate greatly in the waste water from the retort device 2, the treatment system 1 is based on the electrical conductivity E of the waste water before the sulfite is added. Adjust the permeate recovery at 321. Therefore, the treatment system 1 can suppress the optimum and maximum recovery rate at that time, that is, scale generation in the reverse osmosis membrane module 321 according to the operating state of the retort device 2, and more permeated water. Can be selected.

  Next, the operation of the processing system 1 will be described based on the operation flowchart shown in FIGS. The processing system 1 may be operated at the same time as the retort device 2, or may be operated independently while the retort device 2 is stopped when drainage is stored in the relay tank 30.

  When the operator of the processing system 1 turns on the operation start switch of the processing system 1, the operation program (hereinafter simply referred to as “program”) initializes the processing system 1 in step S <b> 1. In the initial setting, in the reaction unit 200, only the on / off valve of the first supply path 160 is set to the open state, the other on / off valves are set to the closed state, and various sensors are set to the operating state.

  After step S1, the program activates the first pump 110 in step S2. Thereby, the wastewater stored in the relay tank 30 is sent to the forward path 100, cooled by the cooling device 120, and reaches the reaction unit 200. At this time, the electrical conductivity sensor 140 continuously measures the electrical conductivity of the wastewater flowing from the forward path 100 to the reaction unit 200 at a preset time interval (for example, the aforementioned 100 millisecond interval), and the result is obtained. Record in the controller 500.

  In addition, the high temperature wastewater stored in the relay tank 30 usually has a temperature in the reaction unit 200 of 20 ° C. or higher, and a permeation flux having a sufficient temperature during the filtration process in the reverse osmosis membrane module 321. By the cooling device 120, the cooling device 120 can ensure the temperature to be 20 ° C. or higher and 35 ° C. or lower which is a general heat resistance temperature of the seal member (for example, brine seal ring) used in the reverse osmosis membrane module 321. Cooling is preferred.

  The wastewater that has reached the reaction unit 200 is supplied from the first supply path 160 to the first water storage tank 210 and stored. In the next step S3, the program determines whether or not the waste water from the first supply path 160 has been stored up to the high water level sensor S1H position of the first water tank 210. If the drainage has not reached the high water level sensor S1H position, the program continues to supply water to the first water tank 210. On the other hand, when the drainage reaches the high water level sensor S1H position, the program proceeds to step S4 and executes an opening / closing operation of the opening / closing valve. Specifically, the on / off valve of the first supply path 160 is closed, and the on / off valve of the second supply path 170 is opened. Thereby, the water supply to the first water tank 210 is stopped, and the waste water from the forward path 100 is supplied to the second water tank 220 through the second supply path 170.

  After step S4, the program executes the processes after step S5 and the processes after step S100 in parallel.

  In step S5, the program determines whether or not the waste water from the second supply path 170 has been stored up to the high water level sensor S2H position of the second water tank 220. If the drainage has not reached the high water level sensor S2H position, the program continues to supply water to the second water tank 220. On the other hand, when the drainage reaches the high water level sensor S2H position, the program proceeds to step S6, and the opening / closing operation of the opening / closing valve is executed. Specifically, the on / off valve of the second supply path 170 is closed, and the on / off valve of the third supply path 180 is opened. Thereby, the water supply to the second water storage tank 220 is stopped, and the waste water from the forward path 100 is supplied to the third water storage tank 230 through the third supply path 180.

  After step S6, the program executes the processes after step S7 and the processes after step S200 in parallel.

  In step S7, the program determines whether or not the waste water from the third supply path 180 has been stored up to the high water level sensor S3H position of the third water tank 230. If the drainage has not reached the high water level sensor S3H position, the program continues to supply water to the third water tank 230. On the other hand, when the drainage reaches the high water level sensor S3H position, the program proceeds to step S8, and executes the opening / closing operation of the on-off valve. Specifically, the on / off valve of the third supply path 180 is closed, and the on / off valve of the first supply path 160 is opened. Thereby, the water supply to the 3rd water tank 230 stops.

  After step S8, the program executes the processes after step S3 and the processes after step S300 in parallel.

  As described above, when the program repeatedly executes step S3 to step S8, the reaction unit 200 repeatedly discharges the water from the outward path 100 in the order of the first water tank 210, the second water tank 220, and the third water tank 230. Supplied and stored.

  In step S100 in parallel with step S5 and subsequent steps, the program records the electrical conductivity of the wastewater supplied to the first water tank 210. Specifically, in the control unit 500, the average value of the results of the electrical conductivity E1 ′ continuously measured by the electrical conductivity sensor 130 for the wastewater that has flowed through the forward path 100 while the opening / closing valve of the first supply path 160 is open. (A moving average value such as a simple moving average value, a weighted moving average value or an exponential moving average value) is calculated, and the result is recorded as measurement data of the electrical conductivity E1 of the wastewater stored in the first water tank 210.

  In step S101 following step S100, the program determines whether or not a reaction step described later is being executed in a water tank other than the first water tank 210, that is, the second water tank 220 and the third water tank 230. Here, in the circulation path 240, of the second feed flow path 222 and the second return flow path 223 of the second water storage tank 220 and the third feed flow path 232 and the third return flow path 233 of the third water storage tank 230. When any of the on-off valves is in an open state, the program determines that the reaction process is being executed in the second water tank 220 or the third water tank 230, and enters a standby state. On the other hand, in the circulation path 240, when all the on-off valves are closed, the program determines that the reaction process is not being executed in the second water tank 220 and the third water tank 230, and proceeds to step S102. Thus, the waste water treatment subroutine for the first water tank 210 is executed.

  In the waste water treatment subroutine of the first water tank 210 (see FIG. 4), an opening / closing operation of the opening / closing valve of the circulation path 240 is executed in Step P101. Specifically, the on / off valves of the first feed channel 212 and the first return channel 213 are opened, and the other on / off valves are kept closed. After completion of step P101, the program operates the circulation pump 241 in step P102. Accordingly, the wastewater stored in the first water storage tank 210 is sent from the first feed flow path 212 to the circulation path 240 and circulates back from the first return flow path 213 to the first water storage tank 210.

  Next, the program starts a reaction process (process A) in step P103. Here, the 1st chemical injection apparatus 243 is operated, sulfite is added with respect to the waste_water | drain from the 1st storage tank 210 which flows through the circulation path 240, and pH adjustment operation | movement is started. In the pH adjustment operation, the program continuously measures the pH of the wastewater flowing through the circulation path 240 by the pH sensor 242 and appropriately supplies a pH adjuster from the second chemical injection device 244 so that the measured value of the pH becomes a predetermined value. Supply.

  In the following step P104, the program resets the timer T of the control unit 500 to 0 and starts time measurement. In the subsequent step P105, the program determines whether or not the time measured by the timer T has reached the predetermined time T1. As long as the timer T does not reach T1, the program continues the reaction process.

  The sulfite added to the wastewater in Step P103 reacts with aldehydes such as formaldehyde contained in the wastewater to generate α-hydroxysulfonic acid ions. Thereby, the waste_water | drain of the 1st water tank 210 is converted into the processed water containing the produced | generated alpha-hydroxysulfonic acid ion.

The amount of sulfite added in Step P103 is usually preferably set to 2 to 6 molar equivalents and more preferably set to 3 to 5 molar equivalents with respect to the aldehydes contained in the waste water. It is particularly preferable to set it to 5 molar equivalents. When the amount added is less than 2 molar equivalents, a part of the sulfite is consumed for reaction with dissolved oxygen contained in the circulating wastewater, and there is a possibility that sulfite and unreacted aldehydes remain in the wastewater. There is a possibility that the residual aldehyde concentration in the permeated water is increased in the filtration process in the filtration unit 300 described later. On the contrary, when the addition amount exceeds 6 molar equivalents, a large amount of unreacted sulfite remains in the waste water, and the sulfite in the permeated water increases as the permeate recovery rate increases in the filtration process in the filtration unit 300 described later. The salt concentration may increase. The permeated water obtained by the filtration treatment is generally reused after adjusting to a residual chlorine concentration (usually 1 to 3 mgCl ₂ / L) suitable for various waters used in food production. A sodium chlorite aqueous solution is added, but if the concentration of sulfite in the permeate increases, it may be necessary to increase the amount of sodium hypochlorite aqueous solution added in the return path 400.

  In addition, since the aldehyde contained in the waste water from the retort kettle 20 is usually formaldehyde and the concentration thereof is as small as about 1 to 5 mg / L as described above, the sulfite for the waste water from the retort kettle 20 is used. Assuming that the content of formaldehyde in the wastewater is 5 mg / L, it can be fixed at 5 molar equivalents.

  Further, in the pH adjustment operation in step P103, the pH of the circulating waste water is adjusted to 7 or less. The formation reaction of α-hydroxysulfonic acid ions by sulfites and aldehydes is a reversible reaction and proceeds in the direction of formation of α-hydroxysulfonic acid ions in an acidic environment, but the generated α-hydroxysulfonic acid ions in an alkaline environment. Aldehydes are regenerated from sulfonate ions. For this reason, by adjusting the wastewater to the above pH, aldehydes can be smoothly converted into α-hydroxysulfonate ions, and the regeneration of aldehydes from the generated α-hydroxysulfonate ions is suppressed. can do.

  However, in the reaction process, when the pH of the wastewater circulating through the circulation path 240 is less than 6, the concentration of hydrogen ions on the concentrated water side of the reverse osmosis membrane module 321 increases as the recovery rate increases in the filtration process in the filtration unit 300 described later. And hydrogen ions are likely to leak to the permeate side. In this case, the pH of the permeated water may be lower than 5.8, which is the standard for tap water. In this case, the pH of the permeated water is increased by adding an alkaline chemical (for example, sodium hydroxide) in order to be reused in the retort device 2. There is a need to adjust the tap water standard from 5.8 to 8.6. Therefore, the pH of the waste water circulating through the circulation path 240 is usually preferably controlled to 6.0 or more, and particularly preferably adjusted to 6.0 or more and 6.5 or less.

  In the pH adjustment operation in Step P103, the pH of the waste water circulating through the circulation path 240 is continuously measured by the pH sensor 242, and a pH adjusting agent selected from the second chemical injection device 244 is appropriately added according to the result. Here, when bisulfite such as sodium bisulfite is used as the sulfite added from the first chemical injection device 243, since the pH of the wastewater to which the sulfite is added is lowered, a regulator for increasing the pH is selected. Add as appropriate. In addition, when a sulfite such as sodium sulfite is used as the sulfite, the pH of the wastewater to which the sulfite is added is unlikely to decrease, so an adjusting agent for lowering the pH is selected and added as appropriate. When a mixture of sulfite such as sodium sulfite and bisulfite such as sodium bisulfite is used as the sulfite added from the first chemical injection device 243, the ratio of sulfite and bisulfite can be adjusted. The pH of the waste water can also be controlled within a preferable range.

  When it is confirmed in step P105 that the timer T has reached T1, the program proceeds to the next step P106. Here, T1 is the elapsed time from the start of the reaction step, and corresponds to the reaction time for reacting the aldehydes in the waste water with the added sulfite. Therefore, T1 needs to be set to a time during which it can sufficiently react with the sulfite added by the aldehydes in the waste water, and is preferably set to at least 15 minutes. However, since the reaction of the drainage of the first water storage tank 210 also proceeds when the communication path 310 is moved for the filtration process in the reverse osmosis membrane device 320 to be described later, the drainage is connected to the communication path 310 in T1. It can also be adjusted by subtracting the time it takes to move.

  In step P106, the program executes an end operation of the reaction process. Here, the circulation pump 241 is stopped, and the on-off valves of the first feed channel 212 and the first return channel 213 are closed. In subsequent step P107, the program confirms whether or not the filtration operation is being performed in any of the other water tanks of the reaction unit 200, that is, the second water tank 220 and the third water tank 230. Specifically, it is confirmed whether the open / close valve of any of the second discharge path 221 from the second storage tank 220 and the third discharge path 231 from the third water storage tank 230 is in an open state. When any one of these on-off valves is in an open state, the program determines that a filtration operation is being performed in either the second water tank 220 or the third water tank 230, and the program waits in step P107. . On the other hand, when the on-off valves of the second discharge path 221 and the third discharge path 231 are in the closed state, the program does not execute the filtration operation in any of the second water tank 220 and the third water tank 230. And the process proceeds to Step P108.

  In step P108, the program refers to the electrical conductivity E1 recorded in step S100, and selects the recovery rate to be set in the reverse osmosis membrane device 320 from the relationship table stored by the control unit 500. Then, the drainage control valve 324 is controlled so that this recovery rate is achieved. For example, when the recorded electrical conductivity E1 is 100 μS / cm or more, the recovery rate to be set according to Table 1 is 60%. Therefore, in the reverse osmosis membrane device 320, the permeate recovery rate is 60%. The drainage control valve 324 is controlled. Also, when the recorded electrical conductivity E1 is less than 10 μS / cm, the recovery rate to be set according to Table 1 is 95%, so that the reverse osmosis membrane device 320 has a permeate recovery rate of 95%. The drainage control valve 324 is controlled.

  Next, the program moves to Step P109 and starts the filtration process. Here, the on-off valve of the first discharge path 211 is opened and the second pump 311 is operated. As a result, wastewater that has undergone the reaction process in the first water tank 210, that is, processed water, flows from the first water tank 210 to the communication path 310 through the first discharge path 211 and is supplied to the reverse osmosis membrane device 320.

  In the reverse osmosis membrane device 320, the processed water from the communication path 310 is filtered in the reverse osmosis membrane module 321 to remove α-hydroxysulfonic acid ions. Then, the processed water from which α-hydroxysulfonic acid ions have been removed, that is, the permeated water of the reverse osmosis membrane module 321 flows to the return path 400 as reclaimed water from which aldehydes have been removed, and is stored in the water receiving tank 40 of the retort device 2. .

  In the filtration process, a part of the concentrated processed water in the reverse osmosis membrane module 321 flows from the drainage channel 322 to the return path 323 and a part is discarded through the drainage control valve 324. The concentrated processed water that has flowed to the return path 323 returns to the communication path 310 and is supplied to the reverse osmosis membrane module 321 again. Thereby, in the reverse osmosis membrane module 321, the cross flow filtration of the processed water sent from the 1st water tank 210 advances. With the progress of such cross flow filtration, the pH of the concentrated processed water in the reverse osmosis membrane module 321 decreases because the hydrogen ion concentration increases. For example, when the pH of the processed water is 6 to 7 as a result of pH adjustment in the reaction process, the pH of the concentrated processed water is about 5.8 to 6.5 depending on the recovery rate in the reverse osmosis membrane module 321. To drop.

  Since the filtration process in Step P109 is executed according to the recovery rate set in Step P108, permeate can be obtained at a high recovery rate while suppressing the generation of scale in the reverse osmosis membrane module 321.

  In the filtration step, the circulation ratio of the reverse osmosis membrane device 320 (the ratio of the concentrated processed water flow rate (X) flowing out from the reverse osmosis membrane module 321 and the permeate flow rate (Y) flowing out from the reverse osmosis membrane module 321 ( X / Y)) is from the viewpoint of suppressing fouling due to organic matter contained in the waste water (usually derived from organic matter attached to a beverage or food container to be treated in the retort kettle 20) or turbidity. It is preferable to set to at least 5.

In the filtration process, the residual chlorine concentration is measured by the residual chlorine meter 420 in the permeated water that has flowed to the return path 400. The third chemical feed device 410 so that the measured value of the residual chlorine meter 420 is 1~3mgCl 2 / _L suitable for various water for food production, addition of appropriate aqueous solution of sodium hypochlorite against permeate To do.

  After starting the filtration process in Step P109, the program determines whether or not the low water level sensor S1L of the first water tank 210 is activated in Step P110. Since the low water level sensor S1L does not operate while the supply of the processing water from the first water tank 210 to the communication path 310 continues, the program continues the filtration process. On the other hand, when the low water level sensor S1L is activated, it can be determined that the first water tank 210 has finished supplying the processing water to the communication path 310 and is substantially emptied, so the program goes to Step P111. It shifts and the on-off valve of the 1st discharge path 211 is closed, and the filtration process about the processing water from the 1st water tank 210 is completed.

  After the end of step P111, the program returns to step S7 of the main routine. In step S7, when the high water level sensor S3H is activated by storing the waste water from the forward path 100 in the third water tank 230, the on-off valve of the first supply path 160 is opened in the next step S8. The first water tank 210 that has been substantially emptied by discharging the processed water is again supplied with the waste water from the forward path 100 and stored.

  In step S200 parallel to step S7 and subsequent steps, the program records the electrical conductivity of the wastewater supplied to the second water tank 220. Specifically, in the control unit 500, the average value of the results of the electrical conductivity E2 ′ continuously measured by the electrical conductivity sensor 130 for the wastewater that has flowed through the forward path 100 while the on-off valve of the second supply path 170 is open. (A moving average value such as a simple moving average value, a weighted moving average value or an exponential moving average value) is calculated, and the result is recorded as measurement data of the electrical conductivity E2 of the wastewater stored in the second water tank 220.

  In step S201 following step S200, the program determines whether or not the reaction process is being performed in a water tank other than the second water tank 220, that is, in the first water tank 210 and the third water tank 230. Here, in the circulation path 240, one of the first feed flow path 212 and the first return flow path 213 of the first water storage tank 210 and the third feed flow path 232 and the third return flow path 233 of the third water storage tank 230. When any of the on-off valves is in the open state, the program determines that the reaction process is being executed in the first water tank 210 or the third water tank 230, and enters a standby state. On the other hand, in the circulation path 240, when all the on-off valves are closed, the program determines that the reaction process is not being executed in the first water tank 210 and the third water tank 230, and proceeds to step S202. Thus, the waste water treatment subroutine for the second water tank 220 is executed.

  In the waste water treatment subroutine for the second water tank 220 (see FIG. 5), an opening / closing operation of the opening / closing valve of the circulation path 240 is executed in Step P201. Specifically, the on / off valves of the second feed channel 222 and the second return channel 223 are opened, and the other on / off valves are kept closed. After completion of step P201, the program activates the circulation pump 241 in step P202. As a result, the wastewater stored in the second water storage tank 220 is sent from the second feed flow path 222 to the circulation path 240 and circulates back from the second return flow path 223 to the second water storage tank 220.

  Next, the program starts a reaction process (process A) in step P203, and executes steps P204 and P205. The operation contents in steps P203 to P205 are the same as the operation contents in steps P103 to P105 in the waste water treatment subroutine of the first water tank 210 (see FIG. 4), respectively.

  When it is confirmed in step P205 that the timer T has reached T1, the program proceeds to the next step P206. In step P206, the program executes an end operation of the reaction process. Here, the circulation pump 241 is stopped, and the on-off valves of the second feed channel 222 and the second return channel 223 are closed. In subsequent step P207, the program confirms whether or not the filtration operation is being performed in any one of the other water tanks of the reaction unit 200, that is, the first water tank 210 and the third water tank 230. Specifically, it is confirmed whether or not any of the opening / closing valves of the first discharge path 211 from the first storage tank 210 and the third discharge path 231 from the third water storage tank 230 is open. When any one of these on-off valves is in the open state, the program determines that the filtration operation is being performed in either the first water tank 210 or the third water tank 230, and the program waits in step P207. . On the other hand, when the on-off valves of the first discharge path 211 and the third discharge path 231 are in the closed state, the program is one in which the filtration operation is not executed in either the first water tank 210 or the third water tank 230 And the process proceeds to Step P208.

  In step P208, the program refers to the electrical conductivity E2 recorded in step S200, and selects the recovery rate to be set in the reverse osmosis membrane device 320 from the relationship table stored by the control unit 500. Then, the drainage control valve 324 is controlled so that this recovery rate is achieved.

  Next, the program moves to Step P209 and starts the filtration process. Since the second pump 311 has already been operated in step P109 of the wastewater treatment subroutine for the first water tank 210, the on-off valve of the second discharge path 221 is opened here. As a result, the processed water is supplied from the second water tank 220 to the reverse osmosis membrane device 320 in addition to the processed water from the first water tank 210, and this processed water is filtered in the reverse osmosis membrane device 320. Is done.

  Since the filtration process in Step P209 is executed according to the recovery rate set in Step P208, the permeation of the processed water from the second water tank 220 with a high recovery rate while suppressing the generation of scale in the reverse osmosis membrane module 321. You can get water.

  After starting the filtration process in Step P209, the program determines whether or not the low water level sensor S2L of the second water tank 220 is activated in Step P210. Since the low water level sensor S2L does not operate while the supply of the processing water from the second water tank 220 to the communication path 310 continues, the program continues the filtration process. On the other hand, when the low water level sensor S2L is activated, it can be determined that the second water tank 220 is substantially empty after finishing the supply of the processing water to the communication path 310, so the program goes to Step P211. It shifts and the on-off valve of the 2nd discharge channel 221 is closed, and the filtration process about the processed water from the 2nd water tank 220 is ended.

  After step P211, the program returns to step S3 of the main routine. In step S3, when the high water level sensor S1H is activated by storing the waste water from the forward path 100 in the first water storage tank 210, the on-off valve of the second supply path 170 is opened in the next step S4. The drainage from the forward path 100 is supplied again and stored in the second water storage tank 220 that is substantially emptied by discharging the processed water.

  In step S300 in parallel with step S3 and subsequent steps, the program records the electrical conductivity of the wastewater supplied to the third water tank 230. Specifically, in the control unit 500, the average value of the results of the electrical conductivity E3 ′ continuously measured by the electrical conductivity sensor 130 for the wastewater that has flowed through the forward path 100 while the on-off valve of the third supply path 180 is open. (A moving average value such as a simple moving average value, a weighted moving average value or an exponential moving average value) is calculated, and the result is recorded as measurement data of the electrical conductivity E3 of the wastewater stored in the third water tank 230.

  In step S <b> 301 following step S <b> 300, the program determines whether or not the reaction process is being performed in a water tank other than the third water tank 230, that is, in the first water tank 210 and the second water tank 220. Here, in the circulation path 240, one of the first feed flow path 212 and the first return flow path 213 of the first water storage tank 210 and the second feed flow path 222 and the second return flow path 223 of the second water storage tank 220. When any of the on-off valves is in an open state, the program determines that the reaction process is being executed in the first water tank 210 or the second water tank 220, and enters a standby state. On the other hand, in the circulation path 240, when all the on-off valves are closed, the program determines that the reaction process is not being executed in the first water tank 210 and the second water tank 220, and proceeds to step S302. Thus, the waste water treatment subroutine for the third water tank 230 is executed.

  In the wastewater treatment subroutine for the third water tank 230 (see FIG. 6), the opening / closing operation of the opening / closing valve of the circulation path 240 is executed in Step P301. Specifically, the on / off valves of the third feed channel 232 and the third return channel 233 are opened, and the other on / off valves are kept closed. After completion of step P301, the program activates the circulation pump 241 in step P302. Thereby, the wastewater stored in the third water storage tank 230 is sent from the third feed flow path 232 to the circulation path 240 and circulates back from the third return flow path 233 to the third water storage tank 230.

  Next, the program starts a reaction process (process A) in step P303 and executes steps P304 and P305. The operation contents in steps P303 to P305 are the same as the operation contents in steps P103 to P105 in the waste water treatment subroutine of the first water tank 210 (see FIG. 4), respectively.

  When it is confirmed in step P305 that the timer T has reached T1, the program proceeds to the next step P306. In step P306, the program executes an end operation of the reaction process. Here, the circulation pump 241 is stopped, and the on-off valves of the third feed channel 232 and the third return channel 233 are closed. In subsequent step P307, the program confirms whether or not the filtration operation is being performed in any of the other water tanks of the reaction unit 200, that is, the first water tank 210 and the second water tank 220. Specifically, it is confirmed whether or not any of the opening / closing valves of the first discharge path 211 from the first storage tank 210 and the second discharge path 221 from the second water storage tank 220 is open. When any one of these on-off valves is in the open state, the program determines that the filtration operation is being executed in either the first water tank 210 or the second water tank 220, and the program waits in step P307. . On the other hand, when the on-off valves of the first discharge path 211 and the second discharge path 221 are in the closed state, the program does not execute the filtration operation in either the first water tank 210 or the second water tank 220. And the process proceeds to Step P308.

  In step P308, the program refers to the electrical conductivity E3 recorded in step S300, and selects a recovery rate to be set in the reverse osmosis membrane device 320 from the relation table stored by the control unit 500. Then, the drainage control valve 324 is controlled so that this recovery rate is achieved.

  Next, the program moves to Step P309 and starts the filtration process. Since the second pump 311 has already been operated in step P109 of the wastewater treatment subroutine for the first water tank 210, the on-off valve of the third discharge path 231 is opened here. As a result, the processed water from the third water storage tank 230 is supplied to the reverse osmosis membrane device 320 following the processed water from the second water storage tank 220, and this processed water is filtered in the reverse osmosis membrane device 320. Is done.

  Since the filtration process in Step P309 is performed according to the recovery rate set in Step P308, the permeation of the processing water from the third water tank 230 at a high recovery rate while suppressing the generation of scale in the reverse osmosis membrane module 321. You can get water.

  After starting the filtration process in Step P309, the program determines whether or not the low water level sensor S3L of the third water tank 230 is activated in Step P310. Since the low water level sensor S3L does not operate while the supply of the processing water from the third water tank 230 to the communication path 310 continues, the program continues the filtration process. On the other hand, when the low water level sensor S3L is activated, it can be determined that the third water storage tank 230 has substantially finished emptying the supply of the processing water to the communication path 310, so the program goes to Step P311. It shifts and the on-off valve of the 3rd discharge path 231 is closed, and the filtration process about the processed water from the 3rd water tank 230 is complete | finished.

  After step P311, the program returns to step S5 of the main routine. In step S5, when the high water level sensor S2H is activated by storing the waste water from the forward path 100 in the second water tank 220, the on-off valve of the third supply path 180 is opened in the next step S6. The drainage from the forward path 100 is again supplied and stored in the third water storage tank 230 that has become substantially empty by discharging the processing water.

  As described above, in the treatment system 1, in the reaction unit 200, waste water from the forward path 100 is supplied in the order of the first water tank 210, the second water tank 220, and the third water tank 230, and waste water stored in each tank. Are converted into processed water by applying the reaction steps in the same order. Moreover, the processed water of each tank is supplied to the filtration part 300 in the same order, and a filtration process is applied. And each tank which becomes substantially empty by sequentially supplying the processing water to the filtration unit 300 is again supplied with drainage from the forward path 100 in the same order and repeats the reaction process, and the processing water to the filtration unit 300 in the same order. Repeat the supply. Therefore, the treatment system 1 continuously applies the reaction process and the filtration process to the aldehyde-containing wastewater from the retort device 2, thereby continuously returning the permeated water from the filtration unit 300 to the retort device 2. Therefore, consumption of the tap water (namely, fresh water) from the supplementary water channel 41 in the retort device 2 can be effectively suppressed.

  Moreover, the treatment system 1 measures the electrical conductivities E1, E2, and E3 of the wastewater supplied to the first water tank 210, the second water tank 220, and the third water tank 230, respectively, and the filtering unit 300 Since the recovery rate is changed for each of these electrical conductivities E1, E2, and E3 in the filtration step in FIG. 3, permeated water can be obtained at a high recovery rate while suppressing the generation of scale in the reverse osmosis membrane module 321. Therefore, the processing system 1 does not need to discard the aldehyde-containing wastewater from the retort device 2 more than necessary in order to suppress the scale generation in the filtration unit 300, and efficiently reuses the aldehyde-containing wastewater. Can do.

  In addition, the processing system 1 according to this embodiment allows the processing water from the reaction unit 200 to be supplied to the filtration unit 300 without interruption according to the above-described operation program, so that the following conditions are achieved. The water supply capacity from 100 to the reaction section 200, the capacity of each of the water storage tanks 210, 220 and 230 of the reaction section 200, the water supply capacity from the reaction section 200 to the filtration section 300, and the like are set.

-The reaction process about the waste water stored in the 2nd water tank 220 in the middle of the process water filtration process from the 1st water tank 210 is completed, and the waste water supply to the 3rd water tank 230 is completed.
-The reaction process about the waste_water | drain stored in the 3rd water tank 230 in the middle of the filtration process of the processing water from the 2nd water tank 220 is completed, and the waste_water | drain supply to the 1st water tank 210 is completed.
-The reaction process about the wastewater stored in the 1st water tank 210 in the middle of the process water filtration process from the 3rd water tank 230 is completed, and the wastewater supply to the 2nd water tank 220 is completed.

  In the processing system 1 according to the above-described embodiment, the operating pressure of the reverse osmosis membrane module 321 is set to 0.6 MPa to 1 MPa, and the permeate recovery rate is 60 to 95% based on the electrical conductivity of the drainage. When the wastewater having a formaldehyde concentration of 1 to 5 mg / L is treated while adjusting within the range of the permeated water, the permeated water that conforms to the tap water standard suitable for reuse in the retort device 2, that is, the residual formaldehyde concentration is 0.08 mg. Permeated water having a total organic carbon amount of 3.0 mg / L or less.

  In the processing system 1 according to the above-described embodiment, the reaction unit 200 is provided with three water storage tanks, and the reaction process is performed by sequentially storing the waste water therein. However, the reaction unit 200 has two water storage tanks. Or four or more tanks. In addition, when the amount of wastewater that needs to be regenerated is limited, the reaction unit 200 may have only one water storage tank corresponding to the amount of wastewater.

  In addition, the electrical conductivity E is measured for each drainage water stored in each storage tank of the reaction unit 200 before applying the reaction process, and the recovery rate in the filtration unit 300 is set based on the electrical conductivity E. It can also be changed.

  Further, the control unit 500 stores a function equation representing the relationship between the electrical conductivity E and the recovery rate to be set for the value, and sets the recovery rate in the filtration unit 300 using this function equation. It can also be changed.

  Further, the processing system 1 is a drainage source other than the retort device 2, for example, wastewater from a pasteurization device for food pasteurization treatment of food or beverage filled in a container, or a food or beverage container cleaning device, or other It can be used in the same manner when wastewater from the source of aldehyde-containing wastewater is reused.

[Experimental example]
Using the treatment system 1 according to the above-described embodiment, formaldehyde-containing wastewater having the following properties was treated.
Formaldehyde concentration: 1-5mg / L
pH: 6.5-7.5 (within tap water quality standards)
Electrical conductivity: about 150 μS / cm (value of fresh water supplied to the water receiving tank 40)
Temperature: 60 ° C (however, cooled to 30 ° C by the cooling device 120)

  Table 2 shows the operating conditions and processing results of the processing system 1.

  According to Table 2, it can be seen that, in Experimental Examples 4 and 5, in which the pH adjustment value in the reaction process exceeds 7, formaldehyde exceeding 0.08 mg / L of the tap water standard remains in the permeated water.

DESCRIPTION OF SYMBOLS 1 Processing system 2 Retort apparatus 130 Electrical conductivity sensor 160 1st supply path 170 2nd supply path 180 3rd supply path 210 1st water tank 220 2nd water tank 230 3rd water tank 243 1st chemical injection apparatus 244 2nd Chemical injection device 320 Reverse osmosis membrane device 500 Control unit

Claims (16)

A treatment method for reusing wastewater containing aldehydes from a wastewater source,
Add sulfite to the aldehyde-containing wastewater from the wastewater source and obtain a processed water by reacting in an environment having a pH of less than 7, and send the processed water to a reverse osmosis membrane device and filter it. A process step including a step B of obtaining permeated water from the reverse osmosis membrane device,
The electrical conductivity E of the aldehyde-containing wastewater before adding the sulfite is measured, and when the electrical conductivity E is relatively low, the recovery rate of the permeated water from the reverse osmosis membrane device is relatively When the electrical conductivity E is relatively high, the permeated water recovery rate in step B based on the electrical conductivity E so as to relatively reduce the permeated water recovery rate from the reverse osmosis membrane device. Adjust the
Treatment method for wastewater containing aldehydes.   The treatment step performs step A by sequentially supplying the aldehyde-containing wastewater from the wastewater source to a plurality of water storage tanks, and sequentially supplies the processed water from the plurality of water storage tanks to the reverse osmosis membrane device. Water storage for supplying the aldehyde-containing wastewater in Step A sequentially to the water storage tank that has completed the water supply of the processed water to the reverse osmosis membrane device among the plurality of water storage tanks The method for treating aldehyde-containing wastewater according to claim 1, which is reused as a tank.   The electrical conductivity E is measured for the aldehyde-containing wastewater for each of the plurality of water tanks, and the processed aldehyde is supplied to the reverse osmosis membrane device in the process B in the process B and supplied to the water tank in the process A in the process A. The processing method of the aldehyde containing wastewater of Claim 2 which adjusts the collection | recovery rate of the said permeated water in the process B based on the electrical conductivity E of containing wastewater.   Measure the electrical conductivity E by measuring the electrical conductivity E ′ of the aldehyde-containing wastewater in the course of supply from the drainage source to the water storage tank at regular intervals and calculating the moving average value of the electrical conductivity E ′. The processing method of the aldehyde containing waste water of Claim 3.   The treatment of aldehyde-containing wastewater according to any one of claims 1 to 4, wherein the recovery rate is adjusted based on a relational table summarizing the electrical conductivity E and the recovery rate to be set for the value. Method.   The method for treating aldehyde-containing wastewater according to any one of claims 1 to 5, wherein in step A, the pH is adjusted to 6.0 or more and 6.5 or less.   The aldehyde-containing wastewater contains 1 to 5 mg / L of formaldehyde, and the reaction for at least 15 minutes is performed by adding 2 to 6 molar equivalents of the sulfite having the formaldehyde concentration to the aldehyde-containing wastewater in Step A. In addition to ensuring time and adjusting the recovery rate of the permeate in the range of 60 to 95% based on the electrical conductivity E in Step B, the residual formaldehyde concentration is 0.08 mg / L or less and the total organic carbon content The processing method of the aldehyde containing wastewater in any one of Claim 1 to 6 for obtaining the said permeated water of 3.0 mg / L or less.   The method for treating aldehyde-containing wastewater according to any one of claims 1 to 7, wherein the wastewater source is a retort device, a paste rise device, or a container cleaning device. A treatment system for reusing aldehyde-containing wastewater from a wastewater source in the wastewater source,
Storing the aldehyde-containing wastewater from the wastewater source, adding a sulfite to the stored aldehyde-containing wastewater and reacting in an environment having a pH of less than 7, a water storage tank for obtaining processed water;
A reverse osmosis membrane device for filtering the processed water from the water tank and obtaining permeated water;
When the electrical conductivity E of the aldehyde-containing wastewater is measured and the electrical conductivity E is relatively low, the recovery rate of the permeated water from the reverse osmosis membrane device is relatively increased, and the electrical conductivity E is relatively In order to adjust the recovery rate of the permeated water in the reverse osmosis membrane device based on the electrical conductivity E so that the recovery rate of the permeated water from the reverse osmosis membrane device is relatively low. A control unit;
A system for treating wastewater containing aldehydes. A plurality of the water tanks, and further comprising a supply path for sequentially supplying the aldehyde-containing waste water from the drainage source to the empty one of the water tanks,
The aldehyde-containing wastewater treatment system according to claim 9, wherein the plurality of water storage tanks can sequentially feed the processed water to the reverse osmosis membrane device.   The control unit measures the electrical conductivity E of the aldehyde-containing wastewater for each of the water storage tanks, and supplies the processed water to the reverse osmosis membrane device from the supply path to the water storage tank. The processing system of the aldehyde containing waste water of Claim 10 which adjusts the collection | recovery rate of the said permeated water in the said reverse osmosis membrane apparatus based on the electrical conductivity E of the kind containing waste water.   Measure the electrical conductivity E by measuring the electrical conductivity E ′ of the aldehyde-containing wastewater in the course of supply from the supply channel to the water storage tank at regular intervals, and calculating the moving average value of the electrical conductivity E ′. The aldehyde-containing wastewater treatment system according to claim 11.   The control unit includes a relational table summarizing the electrical conductivity E and the recovery rate to be set for the value, and adjusts the recovery rate based on the relational table. The aldehyde-containing wastewater treatment system according to any one of 12 above.   The aldehyde-containing wastewater treatment system according to any one of claims 9 to 13, wherein in the water tank, the pH is adjusted to 6.0 or more and 6.5 or less.   The aldehyde-containing wastewater contains 1 to 5 mg / L of formaldehyde, and the water storage tank adds 2 to 6 molar equivalents of the sulfite having a concentration of the formaldehyde to the aldehydes-containing wastewater for at least 15 minutes. The control unit is set to ensure the reaction time, and the control unit is set to adjust the recovery rate of the permeate based on the electric conductivity E in the range of 60 to 95%. The aldehyde-containing wastewater treatment system according to any one of claims 9 to 14, wherein the permeated water having a total organic carbon amount of 3.0 mg / L or less is 0.08 mg / L or less.   The aldehyde-containing wastewater treatment system according to any one of claims 9 to 15, wherein the wastewater source is a retort device, a paste rise device, or a container cleaning device.

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