JP2016083609A - Treatment device and treatment method for ammonia-containing waste water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high concentration ammonium sulfate solution in treatment where, using a gas-liquid separation membrane, ammonia is removed from ammonia-containing waste water, and is recovered as an ammonium sulfate solution.SOLUTION: Provided is an ammonia-containing waste water treatment device 1 equipped with: a gas-liquid separation membrane 26; an ammonia removing apparatus 16 including a first liquid chamber 24a provided adjacently to either side of the gas-liquid separation membrane 26 and a second liquid chamber 24b provided adjacently to the other side, passing ammonia-containing waste water through the first liquid chamber 24a to remove ammonia, and, in the second liquid chamber 24b, contacting a sulfuric acid solution with the ammonia removed by liquid passing in a confronted flow to recover the same as an ammonium sulfate solution; an inlet side valve 56 for opening and closing the inlet side of the sulfuric acid solution in the second liquid chamber 24b and the outlet side valve 58 for opening and closing the outlet side; and a controlling means, when the passing of the sulfuric acid solution to the second liquid chamber 24b is stopped, making the inlet side valve 56 and the outlet side valve 58 into closed conditions.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an ammonia-containing wastewater treatment apparatus and treatment method for treating ammonia-containing wastewater discharged from an electronics industry factory, chemical factory, etc. and recovering it as ammonium sulfate.

  Conventionally, a relatively high concentration of ammonia-containing wastewater discharged from an electronic industry factory such as a semiconductor factory, a chemical factory, a thermal power plant, etc. is, for example, an ammonia stripping method (for example, see Patent Document 1), an evaporation concentration method ( For example, it is processed by a catalyst wet oxidation method (for example, see Patent Document 3) or the like. Moreover, the ammonia containing waste water of comparatively low concentration is processed by the biological treatment method etc., for example.

Ammonia stripping method is a treatment method in which ammonia in wastewater is moved to the gas side by adding alkaline solution to ammonia-containing wastewater, heating it, passing it through a diffusion tower filled with packing, and bringing it into contact with steam and air It is. Although this method is a comparatively simple process, there exists a subject that the installation of a stripping tower is large. In addition, it is necessary to treat the ammonia that has moved to the gas side using heat energy such as warming and steam, by catalytic oxidation at a higher temperature, resulting in a problem of high processing costs. Further, NO _x , N ₂ O, etc. may be generated during catalytic oxidation.

  The evaporative concentration method is a treatment method in which ammonia-containing waste water is heated and evaporated, and the generated ammonia-containing vapor is condensed and recovered as ammonia water. This method has problems such as heating energy cost for evaporation and scale adhesion on the heat transfer surface of the evaporator.

  The catalytic wet oxidation method is a method of treating ammonia-containing wastewater by applying a temperature and pressure of 100 to 370 ° C. in the presence of a catalyst. This method has problems in safety and cost due to high temperature and high pressure processing.

  In recent years, a gas-liquid separation membrane method has been proposed in which ammonia is removed from ammonia-containing wastewater using a hydrophobic porous gas-liquid separation membrane that does not allow liquid to pass through but allows ammonia to pass (see, for example, Patent Document 4). This method gasifies ammonia in the wastewater by making the ammonia-containing wastewater alkaline at pH 10 or higher, and removes ammonia from the ammonia-containing wastewater by sucking the secondary side of the gas-liquid separation membrane with a vacuum pump. Is the method. However, in this method, it is necessary to install an ammonium sulfate scrubber separately.

  Further, in the gas-liquid separation membrane method, a method of recovering as an ammonium sulfate solution by flowing a sulfuric acid solution to the secondary side of the hydrophobic hollow fiber membrane that is a gas-liquid separation membrane and bringing it into countercurrent contact has been proposed (for example, (See Patent Document 5). In this method, ammonia-containing wastewater adjusted to a pH of 10 or more is flowed outside the hollow fiber membrane, and a sulfuric acid solution having a pH of 2 or less is flowed countercurrently to the inside of the hollow fiber membrane, thereby removing and recovering ammonia in the wastewater. Technology. The gasified ammonia contacts with sulfuric acid flowing inside the hollow fiber membrane and is recovered as ammonium sulfate.

  In the method using a gas-liquid separation membrane, ammonia-containing wastewater can be treated economically with simple equipment and can be reused via an ammonium sulfate solution. However, the ammonium sulfate concentration in the ammonium sulfate solution is low. In the case of reuse and recovery of valuable materials, there is a problem that the ammonium sulfate solution needs to be further concentrated. In particular, if the concentration of the ammonium sulfate solution is less than 25% by mass, it may be difficult to collect as a valuable material and may be handled as waste. Therefore, it is further concentrated separately by reverse osmosis membrane (RO membrane) treatment, ion exchange resin treatment, etc. There was a need.

Japanese Patent No. 39987896 JP 2011-153043 A Japanese Patent No. 3272859 Japanese Patent No. 3240694 JP 2013-202475 A

  An object of the present invention is to remove ammonia from ammonia-containing wastewater using a gas-liquid separation membrane, and to treat ammonia-containing wastewater that is recovered as an ammonium sulfate solution by contacting the removed ammonia with a sulfuric acid solution, for example, 25% by mass or more. It is to obtain a high concentration ammonium sulfate solution.

  The present invention provides a gas-liquid separation membrane, a first liquid chamber provided adjacent to one surface of the gas-liquid separation membrane, and a first liquid chamber provided adjacent to the other surface of the gas-liquid separation membrane. 2 liquid chambers, the ammonia-containing wastewater is passed through the first liquid chamber to remove ammonia, and the sulfuric acid solution is passed through the second liquid chamber in a counterflow with the ammonia-containing wastewater. An ammonia removing means for contacting the removed ammonia to recover it as an ammonium sulfate solution, an inlet side valve for opening and closing the inlet side of the sulfuric acid solution in the second liquid chamber, and an outlet side for opening and closing the outlet side An ammonia-containing wastewater treatment apparatus comprising: a valve; and a control unit that closes the inlet-side valve and the outlet-side valve when the flow of the sulfuric acid solution into the second liquid chamber is stopped. .

  The ammonia-containing wastewater treatment apparatus further comprises pressure relief means for releasing pressure between the inlet side valve and the outlet side valve, and the control means includes the sulfuric acid solution to the second liquid chamber. When the liquid flow is stopped, it is preferable that the inlet side valve and the outlet side valve are closed and the pressure relief means is operated.

  In the ammonia-containing wastewater treatment apparatus, when the flow of the sulfuric acid solution into the second liquid chamber is stopped, the treated water obtained by the ammonia removing means is discharged from the outlet side of the first liquid chamber. It is preferable to provide a treated water circulating means for circulating operation to the inlet side.

  The ammonia-containing wastewater treatment apparatus includes a sulfuric acid addition means for adjusting the sulfuric acid concentration of the sulfuric acid solution flowing through the second liquid chamber, and the sulfuric acid concentration of the sulfuric acid solution added from the sulfuric acid addition means is 50. It is preferable that it is mass% or more.

  In the ammonia-containing wastewater treatment apparatus, an ammonium sulfate solution circulating means for circulating the recovered ammonium sulfate solution from the outlet side to the inlet side of the second liquid chamber, and an ammonium sulfate concentration for measuring the ammonium sulfate concentration of the recovered ammonium sulfate solution Measuring means, and when the measured ammonium sulfate concentration is a predetermined value or more, the recovered ammonium sulfate solution is preferably taken out.

  In the ammonia-containing wastewater treatment apparatus, the temperature of the ammonia-containing wastewater in the ammonia removing means is preferably in the range of 30 to 55 ° C.

  In the ammonia-containing wastewater treatment apparatus, the ammonia-containing wastewater in the ammonia removing means preferably has a pH of 11 or more.

  In the ammonia-containing wastewater treatment apparatus, when the ammonia-containing wastewater contains an oxidizing agent, an oxidizing agent removing means for removing the oxidizing agent from the ammonia-containing wastewater before passing through the first liquid chamber. It is preferable to provide.

  The present invention also provides a gas-liquid separation membrane, a first liquid chamber provided adjacent to one surface of the gas-liquid separation membrane, and the other surface of the gas-liquid separation membrane. The ammonia-containing wastewater is passed through the first liquid chamber of the ammonia removing apparatus having the second liquid chamber to remove ammonia, and the sulfuric acid solution is counterflowed with the ammonia-containing wastewater into the second liquid chamber. In the second liquid chamber when the flow of the sulfuric acid solution into the second liquid chamber is stopped. This is a method for treating ammonia-containing wastewater in which the inlet side valve for opening and closing the inlet side of the sulfuric acid solution and the outlet side valve for opening and closing the outlet side are closed.

  In the method for treating ammonia-containing wastewater, an inlet-side valve for opening and closing the inlet side of the sulfuric acid solution in the second liquid chamber when the flow of the sulfuric acid solution into the second liquid chamber is stopped Preferably, the outlet side valve for opening and closing the outlet side is closed, and the pressure relief means for releasing the pressure between the inlet side valve and the outlet side valve is operated.

In the method for treating ammonia-containing wastewater, when the flow of the sulfuric acid solution into the second liquid chamber is stopped, the treated water obtained by the ammonia removal step is discharged from the outlet side of the first liquid chamber. It is preferable to include a treated water circulation step of circulating operation to the inlet side.

  In the method for treating ammonia-containing waste water, the sulfuric acid concentration of the sulfuric acid solution for adjusting the sulfuric acid concentration of the sulfuric acid solution flowing through the second liquid chamber is preferably 50% by mass or more.

  In the method for treating ammonia-containing wastewater, the recovered ammonium sulfate solution is circulated from the outlet side to the inlet side of the second liquid chamber, the ammonium sulfate concentration of the recovered ammonium sulfate solution is measured, and the measured ammonium sulfate concentration When is more than a predetermined value, it is preferable to take out the recovered ammonium sulfate solution.

  In the method for treating ammonia-containing wastewater, the temperature of the ammonia-containing wastewater in the ammonia removal step is preferably in the range of 30 to 55 ° C.

  In the method for treating ammonia-containing wastewater, the pH of the ammonia-containing wastewater in the ammonia removing step is preferably 11 or more.

  In the method for treating ammonia-containing wastewater, when the ammonia-containing wastewater contains an oxidizing agent, an oxidizing agent removing step of removing the oxidizing agent from the ammonia-containing wastewater before passing through the first liquid chamber. It is preferable to include.

  In the present invention, ammonia is removed from ammonia-containing wastewater using a gas-liquid separation membrane, and in the treatment of ammonia-containing wastewater that is recovered as an ammonium sulfate solution by contacting the removed ammonia with a sulfuric acid solution, for example, a high concentration of 25% by mass or more. A concentrated ammonium sulfate solution can be obtained.

It is a schematic block diagram which shows an example of the processing apparatus of the ammonia containing waste_water | drain which concerns on embodiment of this invention. It is a schematic block diagram which shows the other example of the processing apparatus of the ammonia containing waste_water | drain which concerns on embodiment of this invention.

  Embodiments of the present invention will be described below. This embodiment is an example for carrying out the present invention, and the present invention is not limited to this embodiment.

  The outline of an example of the processing apparatus of the ammonia containing waste_water | drain based on embodiment of this invention is shown in FIG. 1, and the structure is demonstrated. The ammonia-containing wastewater treatment apparatus 1 includes an ammonia removal device 16 as an ammonia removal unit and a circulation tank 18 as an ammonium sulfate solution circulation unit. The ammonia-containing wastewater treatment apparatus 1 may include a raw water tank 10, a heat exchanger 12 as a heating means, a pH adjustment tank 14, a sulfuric acid storage tank 20 as a sulfuric acid addition means, and a pH adjuster storage tank 22. .

  The ammonia removing device 16 includes a gas-liquid separation membrane 26, and a first liquid chamber 24a and a second liquid chamber 24b partitioned by the gas-liquid separation membrane 26. The gas-liquid separation membrane 26 is a membrane such as a hollow fiber membrane that does not pass liquid but passes gaseous ammonia. The first liquid chamber 24 a is provided adjacent to one surface of the gas-liquid separation membrane 26, and the second liquid chamber 24 b is provided adjacent to the other surface of the gas-liquid separation membrane 26. Ammonia-containing wastewater is supplied to the first liquid chamber 24a, and a sulfuric acid solution is supplied to the second liquid chamber 24b.

  In the ammonia-containing wastewater treatment apparatus 1 of FIG. 1, the raw water pipe 30 is connected to the raw water inlet of the raw water tank 10. The outlet of the raw water tank 10 and the raw water inlet of the heat exchanger 12 are connected by a raw water supply pipe 32, and the raw water outlet of the heat exchanger 12 and the inlet of the pH adjustment tank 14 are connected by a raw water supply pipe 34. An outlet of the pH adjusting tank 14 and an inlet of the first liquid chamber 24 a provided on one end side of the ammonia removing device 16 are connected by a pH adjusting water pipe 36. The outlet of the first liquid chamber 24a provided on the other end side of the ammonia removing device 16 and the treated water inlet of the heat exchanger 12 are connected by a treated water circulation pipe 38, and the treated water outlet of the heat exchanger 12 and the raw water inlet of the heat exchanger 12 are connected. The treated water inlet of the water tank 10 is connected by a treated water circulation pipe 40 via a valve 62. A treated water discharge pipe 54 is connected between the treated water outlet of the heat exchanger 12 and the valve 62 via a treated water discharge valve 64. The outlet of the circulation tank 18 and the inlet of the second liquid chamber 24 b provided on the other end side of the ammonia removing device 16 are connected by an ammonium sulfate solution circulation pipe 42 via the inlet side valve 56, and one end of the ammonia removing device 16 is connected. The outlet of the second liquid chamber 24 b provided on the side and the inlet of the circulation tank 18 are connected by an ammonium sulfate solution circulation pipe 44 via an outlet side valve 58. A recovered ammonium sulfate solution pipe 50 is connected to the outlet of the circulation tank 18. The outlet of the sulfuric acid storage tank 20 is connected to the circulation tank 18 by a sulfuric acid pipe 46. The outlet of the pH adjusting agent storage tank 22 is connected to the pH adjusting tank 14 by a pH adjusting agent pipe 48. An ammonium sulfate concentration measuring device 66 may be set in the circulation tank 18.

  The operation of the ammonia-containing wastewater treatment method and the ammonia-containing wastewater treatment apparatus 1 according to this embodiment will be described.

  The ammonia-containing waste water of raw water is stored in the raw water tank 10 as needed through the raw water pipe 30 and then sent to the heat exchanger 12 as needed through the raw water supply pipe 32. The ammonia-containing waste water of the raw water is heated and exchanged with the treated water sent through the treated water pipe 38 in the heat exchanger 12 as necessary (heating step). If the temperature of the ammonia-containing wastewater is a predetermined value, the heating step may not be performed.

  The ammonia-containing waste water heated as necessary in the heat exchanger 12 is sent to the pH adjusting tank 14 through the raw water supply pipe 34 as needed. In the pH adjusting tank 14, the pH adjusting agent is supplied from the pH adjusting agent storage tank 22 through the pH adjusting agent pipe 48 as necessary, and the pH of the ammonia-containing waste water is adjusted to a predetermined value (pH adjusting step). The pH adjusting agent used in the pH adjusting step is, for example, an alkali such as a sodium hydroxide solution or an acid such as hydrochloric acid. In the pH adjustment step, the ammonia-containing wastewater is preferably adjusted to pH 11 or higher in order to dissociate ammonium ions in the ammonia-containing wastewater into ammonia gas and increase the ammonia removal rate in the ammonia removal step described below. Moreover, when the influence on a membrane, piping material, etc. is considered, it is more preferable to adjust to the range of pH11-12. If the pH of the ammonia-containing wastewater is a predetermined value, the pH adjustment step may not be performed.

  The pH-adjusted water whose pH has been adjusted as needed is sent to the first liquid chamber 24a from the inlet provided on one end side of the ammonia removing device 16 through the pH-adjusted water pipe 36. In the ammonia removing device 16, ammonia is removed from the ammonia-containing wastewater by using a gas-liquid separation membrane 26 that allows ammonia to pass through without passing through a liquid. The treated water from which ammonia has been removed is sent to the heat exchanger 12 through the treated water pipe 38 from the outlet of the first liquid chamber 24 a provided on the other end side of the ammonia removing device 16. On the other hand, the inlet side valve 56 and the outlet side valve 58 are opened, and the sulfuric acid solution stored in the circulation tank 18 from the sulfuric acid storage tank 20 through the sulfuric acid pipe 46 is provided on the other end side of the ammonia removing device 16 through the ammonium sulfate solution circulation pipe 42. It is supplied from the inlet to the second liquid chamber 24b and flows in a counterflow with the ammonia-containing wastewater in the first liquid chamber 24a. For example, ammonia-containing wastewater may be flowed outside the hollow fiber membrane (first liquid chamber 24a), and a sulfuric acid solution may be flowed inside the hollow fiber membrane (second liquid chamber 24b). The ammonia that has passed through the gas-liquid separation membrane 26 comes into contact with the sulfuric acid solution flowing through the second liquid chamber 24b of the ammonia removing device 16, and ammonium sulfate is generated (the ammonia removing step).

  The treated water sent to the heat exchanger 12 is heat-exchanged with the ammonia-containing wastewater sent through the raw water supply pipe 32 in the heat exchanger 12 as necessary, and cooled (cooling step). The cooled treated water is discharged through the treated water discharge pipe 54 with the valve 62 closed and the valve 64 opened.

  The ammonium sulfate produced in the second liquid chamber 24b of the ammonia removing device 16 is dissolved in the sulfuric acid solution and passes through the ammonium sulfate solution circulation pipe 44 from the outlet of the second liquid chamber 24b provided on one end side of the ammonia removing device 16. The solution is sent to the circulation tank 18. The sulfuric acid solution is circulated through the circulation tank 18 and the ammonium sulfate solution circulation pipes 42 and 44 until the ammonium sulfate has a predetermined concentration (ammonium sulfate solution circulation step). At this time, the sulfuric acid solution is supplied from the sulfuric acid storage tank 20 to the circulation tank 18 through the sulfuric acid pipe 46, and the pH of the circulated sulfuric acid solution is adjusted to a predetermined value. When the concentration of the recovered ammonium sulfate in the circulated sulfuric acid solution becomes a predetermined concentration or more, the recovered ammonium sulfate solution is discharged from the circulation tank 18 through the recovered ammonium sulfate solution pipe 50.

  As a result of studies by the present inventors, it has been found that when ammonia-containing wastewater is treated using a gas-liquid separation membrane, water vapor also moves through the gas-liquid separation membrane in addition to ammonia gas. For this reason, the recovered ammonium sulfate solution is diluted with water vapor, so that the concentration of ammonium sulfate in the ammonium sulfate solution does not reach a predetermined value and may be lower than expected. In particular, in the treatment of ammonia-containing wastewater having a relatively low concentration, for example, a concentration of about 3,000 mg / L or less, it becomes clear that the movement of water vapor cannot be ignored when trying to obtain an ammonium sulfate solution of 25% by mass or more. It was.

  As a result of further diligent examination of the movement of water vapor in the gas-liquid separation membrane, the present inventors permeate through the gas-liquid separation membrane and move the water vapor even while the flow of ammonia-containing wastewater to the gas-liquid separation membrane is stopped. It became clear that the density | concentration of the produced | generated ammonium sulfate solution was falling. Specifically, for example, in FIG. 1, the flow of the ammonia-containing wastewater to the gas-liquid separation membrane 26 is stopped, for example, when left for about half a day, or the water level of the raw water tank 10 becomes low, and the flow is stopped. In this case, movement of water vapor occurred in the gas-liquid separation membrane 26, and the water level of the ammonium sulfate solution continued to increase in the circulation tank 18 storing the ammonium sulfate solution, and the ammonium sulfate concentration decreased.

  Therefore, the inventors of the present invention use a gas-liquid separation membrane to remove ammonia from ammonia-containing wastewater and recover an ammonium sulfate solution, so that the secondary side of the gas-liquid separation membrane 26, that is, the second liquid chamber 24b. An inlet side valve 56 and an outlet side valve 58 were respectively installed on the inlet side and outlet side of the sulfuric acid solution to be passed. When the flow of the sulfuric acid solution into the second liquid chamber 24b is stopped, both the inlet side valve 56 and the outlet side valve 58 are closed, so that the water vapor passes through the gas-liquid separation membrane 26. It has been found that even if it has moved, it is possible to suppress the movement of water vapor to the circulation tank 18 through the ammonium sulfate solution circulation pipes 42 and 44, and to obtain a high concentration ammonium sulfate solution of, for example, 25% by mass or more. The opening and closing of the inlet side valve 56 and the outlet side valve 58 may be performed by a control device (not shown). For example, when the water level of the raw water tank 10 is low or the water level of the circulation tank 18 is high, the “standby” state, that is, the flow of the sulfuric acid solution into the second liquid chamber 24 b is stopped, and the inlet side valve 56 Both the outlet valve 58 and the outlet valve 58 may be closed so as to prevent a decrease in the concentration of the ammonium sulfate solution due to the inflow of water vapor.

  It is preferable that the operation of the ammonia-containing wastewater treatment apparatus 1 is set to the “standby” state, and the sulfuric acid solution accumulated in the second liquid chamber 24b is blown before the operation is resumed. Thereby, the fall of the density | concentration of the ammonium sulfate solution collect | recovered after restarting operation can be suppressed more.

  In the study by the present inventors, even if the inlet side valve 56 and the outlet side valve 58 are closed when the flow of the sulfuric acid solution into the second liquid chamber 24b is stopped, the secondary side of the gas-liquid separation membrane 26 is closed. That is, the concentration of the ammonium sulfate solution remaining in the second liquid chamber 24b or the like significantly decreases, for example, after a few days, and the pressure between the inlet side valve 56 and the outlet side valve 58 is, for example, 0.05 to 0.4 MPa. It became clear that it rose to some extent. Therefore, as in the ammonia-containing wastewater treatment apparatus 3 shown in FIG. 2, for example, the pressure between the inlet side valve 56 and the outlet side valve 58 is set between the inlet side valve 56 and the inlet of the second liquid chamber 24b. A pressure relief pipe 52 is connected via a pressure relief valve 60 as a pressure relief means for relief. Then, when the flow of the sulfuric acid solution into the second liquid chamber 24b is stopped, the inlet side valve 56 and the outlet side valve 58 are closed, and the pressure relief valve 60 is opened. Thereby, even when the operation is stopped for a long time, the pressure increase on the secondary side of the gas-liquid separation membrane 26 can be suppressed, and an excessive pressure can be suppressed from being applied to the gas-liquid separation membrane 26. The pressure relief pipe 52 and the pressure relief valve 60 may be installed between the outlet of the second liquid chamber 24 b and the outlet side valve 58. The opening and closing of the inlet side valve 56, the outlet side valve 58, and the pressure relief valve 60 may be performed by a control device (not shown).

  When the flow of the sulfuric acid solution into the second liquid chamber 24b is stopped, the valve 62 is opened and the valve 64 is closed, so that the treated water flows from the outlet side of the first liquid chamber 24a as the treated water circulation means. It may be circulated through the treated water circulation pipes 38 and 40 and the raw water tank 10 to the inlet side of the first liquid chamber 24a (treated water circulation step). By circulating the treated water from the primary side of the gas-liquid separation membrane 26, that is, the first liquid chamber 24a, to the raw water tank 10, the temperature of the ammonia-containing waste water is determined by keeping or heating the ammonia-containing waste water that is the raw water. By keeping in this range, it is possible to stabilize the processing after the restart of operation.

  The ammonia-containing wastewater to be treated is, for example, ammonia-containing wastewater discharged from an electronic industry factory such as a semiconductor factory, a chemical factory, a thermal power plant, or the like.

  When the ammonia-containing wastewater contains an oxidizing agent such as hydrogen peroxide, such as the ammonia-containing wastewater discharged from an electronic industrial factory such as a semiconductor factory, activated carbon treatment as an oxidizing agent removing means is performed before the ammonia removing device 16. The oxidant may be removed by an apparatus or the like (oxidant removal step). Thereby, the fall of the ammonia removal rate in the ammonia removal process resulting from oxidizing agents, such as hydrogen peroxide, and the deterioration of a gas-liquid separation membrane can be suppressed.

  The ammonia concentration in the ammonia-containing waste water of the raw water is not particularly limited. It is preferable to operate at 900 mg / L or more and 2,200 mg / L or less in order to make the concentration of ammonium sulfate in the recovered ammonium sulfate solution 25% by mass or more and to make the ammonium sulfate hardly precipitate.

  If the ammonia concentration in the ammonia-containing wastewater is low (for example, less than 900 mg / L), ammonia may be concentrated by reverse osmosis membrane treatment or the like before the ammonia removal device 16. Moreover, in order to concentrate ammonium sulfate, the ammonium sulfate solution produced | generated by processing the ammonia containing waste_water | drain with low density | concentration may be returned to the raw | natural water tank 10 etc. from the circulation tank 18, and ammonia treatment may be performed again.

  It is preferable to feed the ammonia-containing wastewater to the ammonia removing device 16 by heating the raw water at a temperature of, for example, 30 to 55 ° C., preferably in the range of 35 to 55 ° C. by a heating device such as the heat exchanger 12. . When the temperature of the raw water is less than 30 ° C., the ammonia in the ammonia-containing wastewater becomes difficult to gasify, and the ammonia removal rate in the ammonia removal device 16 tends to decrease. Instead of the heat exchanger 12 as a heating device, at least one of the raw water tank 10, the raw water pipe 30 and the raw water supply pipe 32 may be provided with a warmable facility such as a heater to heat the raw water.

  In the ammonia removal step, the pH of the ammonia-containing wastewater to be treated is preferably 11 or more from the viewpoint of the ammonia removal rate. When the pH of the ammonia-containing wastewater to be treated is less than 11, the ammonia in the ammonia-containing wastewater becomes difficult to gasify, and the ammonia removal rate tends to decrease.

  The gas-liquid separation membrane 26 is not particularly limited as long as it does not pass liquid but passes gaseous ammonia. Examples of the gas-liquid separation membrane 26 include a hydrophobic porous hollow fiber membrane. For example, a hollow fiber membrane having a hollow fiber diameter of about 300 μm, a pore size of about 0.03 μm, and an (average) porosity of about 40 to 50% may be used. By such a gas-liquid separation membrane 26, gaseous ammonia contained in the ammonia-containing wastewater passes through the gas-liquid separation membrane 26 and is removed from the ammonia-containing wastewater.

  It is preferable to inject the sulfuric acid solution from the sulfuric acid storage tank 20 so that the pH of the circulated sulfuric acid solution is maintained at 2 or less, for example, in the range of 1-2, preferably in the range of 1.5-2. If the pH of the circulated sulfuric acid solution exceeds 2, the ammonia removal rate may be reduced.

  The sulfuric acid solution added from the sulfuric acid storage tank 20 is preferably as high as possible. From the viewpoint of handling and the like, the sulfuric acid concentration of the sulfuric acid solution added from the sulfuric acid storage tank 20 is preferably 50% by mass or more.

  As described above, when the concentration of the recovered ammonium sulfate in the circulated sulfuric acid solution is equal to or higher than a predetermined concentration, for example, 25% by mass or higher, the recovered ammonium sulfate solution is discharged from the circulation tank 18 through the ammonium sulfate solution pipe 50.

  The concentration of ammonium sulfate in the circulated sulfuric acid solution may be measured using an ammonium sulfate concentration measuring device 66 as an ammonium sulfate concentration measuring means such as a hydrometer or a concentration meter. Based on the measured concentration of ammonium sulfate, when the concentration of ammonium sulfate is equal to or higher than a predetermined concentration, for example, 25% by mass (for example, when the specific gravity of the 25% by mass ammonium sulfate solution is about 1.14 or higher) Alternatively, the recovered ammonium sulfate solution may be automatically taken out from the circulation tank 18 through the recovered ammonium sulfate solution pipe 50. 1 and 2, the ammonium sulfate concentration measuring device 66 is installed in the circulation tank 18, but may be installed in the ammonium sulfate solution circulation pipe 42. Moreover, you may provide the equipment which supplies and dilutes automatically based on the measured density | concentration of ammonium sulfate so that it may become a density | concentration (for example, 40 mass% or less) which ammonium sulfate does not precipitate easily.

  Even if the gas-liquid separation membrane 26 is contaminated by metal salts and the ammonia removal rate decreases, or in order to suppress the decrease in the ammonia removal rate, the gas-liquid separation membrane 26 may be subjected to acid cleaning at a predetermined time. Good (acid cleaning step). For example, an acid storage tank may be installed separately, and the acid solution may be sent to the first liquid chamber 24a of the ammonia removing device 16 through the pH adjustment water pipe 36 to wash the gas-liquid separation membrane 26, or the sulfuric acid storage tank A part of the sulfuric acid solution from 20 may be sent to the first liquid chamber 24a.

  As the acid solution used in the acid washing step, an acid solution such as sulfuric acid, hydrochloric acid, citric acid or the like can be used.

  Hereinafter, although an example and a comparative example are given and the present invention is explained more concretely in detail, the present invention is not limited to the following examples.

The ammonia-containing wastewater was treated under the following test conditions.
[Test conditions]
・ Gas-liquid separation membrane: Polypropylene porous hollow fiber membrane module ・ Membrane area: 1.4 m ²
・ Water flow rate: 0.0145m ³ / h
・ Water temperature: 30 ℃
・ Ammonia-containing wastewater pH: 12 or more ・ Acid side pH: 2 or less

  Ammonia-containing wastewater having an ammonia concentration of 1796 mg / L was passed through the primary side (first liquid chamber) of the gas-liquid separation membrane for 6 hours. The flow rates of the primary side (first liquid chamber) and the secondary side (second liquid chamber) in this experimental system were 14.5 L / h and 19.0 L / h, respectively. The ammonia-containing wastewater that flows into the first liquid chamber is adjusted to pH 12 or more by adding a sodium hydroxide solution, and the solution that flows into the second liquid chamber is 50% by mass in the initial 14% by mass ammonium sulfate solution. A pH of 2 or less was maintained using a sulfuric acid solution.

<Example 1>
After processing the ammonia-containing wastewater for 6 hours, stop the ammonia-containing wastewater and the sulfuric acid solution for 17 hours, and open and close the inlet side valve and the outlet side for opening and closing the inlet side of the sulfuric acid solution. The outlet side valve was controlled to be closed.

<Comparative Example 1>
After the ammonia-containing wastewater was passed for 6 hours for treatment, the ammonia-containing wastewater and the sulfuric acid solution water flow were stopped for 17 hours, and both the inlet side valve and the outlet side valve were opened.

(Experimental result)
The experimental results are shown in Table 1.

  In Example 1, the ammonium sulfate solution could be stably recovered at 25% by mass or more, but in Comparative Example 1, the final concentration of the ammonium sulfate solution decreased to less than 25% by mass (22.5% by mass). In Comparative Example 1, since both the inlet side valve and the outlet side valve were opened during the 17-hour stoppage, water vapor movement occurred through the gas-liquid separation membrane, and the ammonium sulfate solution in the circulation tank was diluted with water vapor. It is thought that the concentration of was decreased.

  1,3 Ammonia-containing wastewater treatment device, 10 Raw water tank, 12 Heat exchanger, 14 pH adjustment tank, 16 Ammonia removal apparatus, 18 Circulation tank, 20 Sulfuric acid storage tank, 22 pH adjuster storage tank, 24a First liquid chamber, 24b Second liquid chamber, 26 Gas-liquid separation membrane, 30 Raw water piping, 32, 34 Raw water supply piping, 36 pH adjustment water piping, 38, 40 Treated water circulation piping, 42, 44 Ammonium sulfate solution circulation piping, 46 Sulfuric acid piping, 48 pH Conditioner piping, 50 recovered ammonium sulfate solution piping, 52 pressure relief piping, 54 treated water discharge piping, 56 inlet side valve, 58 outlet side valve, 60 pressure relief valve, 62 valve, 64 treated water extraction valve, 66 ammonium sulfate concentration measuring device .

Claims (10)

A gas-liquid separation membrane, a first liquid chamber provided adjacent to one surface of the gas-liquid separation membrane, and a second liquid chamber provided adjacent to the other surface of the gas-liquid separation membrane The ammonia-containing wastewater was passed through the first liquid chamber to remove ammonia, and the sulfuric acid solution was passed through the second liquid chamber in a counterflow with the ammonia-containing wastewater to remove the ammonia. An ammonia removal means that is brought into contact with ammonia and recovered as an ammonium sulfate solution;
An inlet side valve for opening and closing the inlet side of the sulfuric acid solution in the second liquid chamber and an outlet side valve for opening and closing the outlet side;
Control means for closing the inlet side valve and the outlet side valve when the flow of the sulfuric acid solution into the second liquid chamber is stopped;
An ammonia-containing wastewater treatment apparatus, comprising: The ammonia-containing wastewater treatment apparatus according to claim 1,
Furthermore, a pressure relief means for releasing the pressure between the inlet side valve and the outlet side valve is provided,
The control means closes the inlet side valve and the outlet side valve when the flow of the sulfuric acid solution into the second liquid chamber is stopped, and operates the pressure relief means. Ammonia-containing wastewater treatment equipment. An apparatus for treating ammonia-containing wastewater according to claim 1 or 2,
A treated water circulating means for circulating the treated water obtained by the ammonia removing means from the outlet side to the inlet side of the first liquid chamber when the flow of the sulfuric acid solution into the second liquid chamber is stopped. An ammonia-containing wastewater treatment apparatus, comprising: The ammonia-containing wastewater treatment apparatus according to any one of claims 1 to 3,
A sulfuric acid addition means for adjusting the sulfuric acid concentration of the sulfuric acid solution passed through the second liquid chamber is provided, and the sulfuric acid concentration of the sulfuric acid solution added from the sulfuric acid addition means is 50% by mass or more. An ammonia-containing wastewater treatment device. The ammonia-containing wastewater treatment apparatus according to any one of claims 1 to 4,
An ammonium sulfate solution circulating means for circulating the recovered ammonium sulfate solution from the outlet side to the inlet side of the second liquid chamber;
Ammonium sulfate concentration measuring means for measuring the ammonium sulfate concentration of the recovered ammonium sulfate solution;
With
The ammonia-containing wastewater treatment apparatus, wherein the collected ammonium sulfate solution is taken out when the measured ammonium sulfate concentration is a predetermined value or more. The ammonia-containing wastewater treatment apparatus according to any one of claims 1 to 5,
The ammonia-containing wastewater treatment apparatus, wherein the temperature of the ammonia-containing wastewater in the ammonia removing means is in the range of 30 to 55 ° C. The ammonia-containing wastewater treatment apparatus according to any one of claims 1 to 6,
The ammonia-containing wastewater treatment apparatus, wherein the ammonia-containing wastewater has a pH of 11 or more in the ammonia removing means. The ammonia-containing wastewater treatment apparatus according to any one of claims 1 to 7,
When the ammonia-containing wastewater contains an oxidant, the ammonia-containing wastewater is provided with an oxidant removing means for removing the oxidant from the ammonia-containing wastewater before passing through the first liquid chamber. Processing equipment. A gas-liquid separation membrane, a first liquid chamber provided adjacent to one surface of the gas-liquid separation membrane, and a second liquid chamber provided adjacent to the other surface of the gas-liquid separation membrane The ammonia-containing wastewater is passed through the first liquid chamber of the ammonia removing device having the following structure to remove ammonia, and the sulfuric acid solution is passed through the second liquid chamber in a counterflow with the ammonia-containing wastewater. Including an ammonia removal step of contacting the removed ammonia and recovering as an ammonium sulfate solution;
An inlet side valve for opening and closing the inlet side of the sulfuric acid solution in the second liquid chamber and an outlet for opening and closing the outlet side when the flow of the sulfuric acid solution into the second liquid chamber is stopped A method for treating ammonia-containing wastewater, wherein the side valve is closed. A method for treating ammonia-containing wastewater according to claim 9,
An inlet side valve for opening and closing the inlet side of the sulfuric acid solution in the second liquid chamber and an outlet for opening and closing the outlet side when the flow of the sulfuric acid solution into the second liquid chamber is stopped A method for treating ammonia-containing wastewater, comprising closing a side valve and operating pressure relief means for releasing pressure between the inlet side valve and the outlet side valve.

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