JP2006110478A - Waste water treating method and apparatus for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waste water treating method and its apparatus by which the treatment efficiency is improved to reduce power consumption. <P>SOLUTION: In the batch type waste water treatment by electrolyzing waste water 1 for a prescribed treating time to decompose a nitrogen compound, the treatment is stopped to suppress the excess production of hypochlorous acid and to lower the next batch electrolysis capability (S109-S111) when the nitrogen compound is decomposed for a time shorter than an allowable treating time Tp shorter than the prescribed treating time Ts, the next electrolysis capability is enhanced (S113-S115) when the nitrogen compound is not decomposed completely within the prescribed treating time Ts and the next batch electrolysis capability is successively kept (S108) when the nitrogen compound is decomposed for a time between the prescribed treating time Ts and the allowable treating time Tp. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method and apparatus for treating organic wastewater containing nitrogen compounds such as human waste.

  Conventionally, organic waste water containing nitrogen compounds such as human waste has been decomposed by biological treatment. In such biological treatment, there is a problem that the balance between the organic matter and the nitrogen compound is lost due to the change in the properties of the urine that is carried in, and the nitrogen compound decomposition treatment performance tends to deteriorate.

  For this reason, for example, in the following Patent Document 1, etc., all or part of the wastewater is supplied to the treatment tank to be electrolyzed, and hypochlorous acid based on chloride ions contained in the wastewater. The nitrogen compound is decomposed by repeating batchwise discharging the waste water from the treatment tank after generating a strong oxidizing substance, oxidizing the nitrogen compound with the strong oxidizing substance, and decomposing it. Is trying to stabilize.

JP 2002-248473 A JP 2003-062577 A JP 2003-225672 A JP 2004-097950 A

  As described above, in a facility for treating the wastewater by electrolysis (for example, human waste treatment plant), the daily treatment amount of the wastewater is predetermined, and the time that can be treated per batch is naturally determined. Therefore, even with the above-mentioned wastewater having the maximum nitrogen compound concentration, a current having a capacity that can be reliably treated within the time (specified treatment time) is uniformly flowed in all batches.

  For this reason, when processing the batch of the waste water having a nitrogen compound concentration smaller than the expected maximum nitrogen compound concentration, the decomposition treatment ends earlier than the time (specified treatment time), and after the treatment ends. Excessive hypochlorous acid-based strong oxidizing substances are generated by the current that flows until the wastewater is discharged, and there is concern about corrosion of the tank in the latter stage and piping, and extra processing costs are incurred. In view of this, it is considered to eliminate waste of power consumption by stopping the flow of current when the disassembling process is completed.

  However, even if the flow of current is stopped when the decomposition process is completed, the amount of current (coulomb amount) required for the decomposition process is the theory necessary for decomposing the amount of nitrogen compounds in the batch. The amount of current required to decompose all the nitrogen compounds is large relative to the amount of nitrogen compounds in one batch, in other words, when the treatment is performed with the current density lowered as much as possible. It became clear that it was preferable.

  In view of the above, an object of the present invention is to provide a wastewater treatment method and apparatus that can increase the treatment efficiency and reduce the power consumption.

  In order to solve the above-mentioned problem, the wastewater treatment method according to the first invention comprises electrolyzing organic wastewater containing nitrogen compounds for a specified treatment time to decompose the nitrogen compounds in the wastewater. In a batch-type wastewater treatment method that repeats a plurality of times, when the nitrogen compound in the wastewater is decomposed in a time shorter than an allowable treatment time shorter than the specified treatment time, the treatment is terminated at that time. In addition, while suppressing the generation of excessive hypochlorous acid, the electrolysis treatment capacity of the batch to be treated next time is lowered than the treatment batch, and the nitrogen compound in the wastewater is decomposed within the specified treatment time. In the case where it has not been completed, the electrolytic treatment capacity of the batch to be processed next time is higher than that of the treatment batch, and the wastewater in the wastewater at a time between the specified treatment time and the allowable treatment time. When decomposing containing compounds, and characterized in that also maintained in batch process electrolysis processing capability of the processing batch next.

  A wastewater treatment method according to a second aspect of the present invention is the wastewater treatment method according to the first aspect, wherein the electrolysis treatment capacity is a magnitude of a current value at the time of electrolysis treatment of the wastewater, and chlorine ions added to the wastewater. Is adjusted by at least one of the following amounts.

  A wastewater treatment method according to a third aspect of the present invention is the wastewater treatment method according to the second aspect, wherein at least one of the magnitude of the current value during the electrolysis treatment of the wastewater and the amount of chlorine ions added to the wastewater. Is adjusted based on any one of a predetermined constant value, a predetermined constant ratio, and a ratio of the time required for the decomposition processing of the batch to the specified processing time.

  A wastewater treatment method according to a fourth aspect of the present invention is the second or third aspect of the invention, wherein the current value during the electrolysis treatment of the wastewater and the amount of chlorine ions added to the wastewater are as follows. Only one of them is adjusted until it reaches the upper limit value or the lower limit value, and when the adjustment of the electrolysis treatment capacity is insufficient due to the adjustment to the one upper limit value or the lower limit value, the other is adjusted to adjust the electric power It is characterized by adjusting the decomposition processing capacity.

  A wastewater treatment method according to a fifth invention is the wastewater treatment method according to any one of the first to fourth inventions, based on at least one of the pH, redox potential, and conductivity of the wastewater. The end point of the decomposition treatment of the nitrogen compound is determined.

  The wastewater treatment method according to a sixth aspect of the present invention is the wastewater treatment method according to the fifth aspect, wherein when the amount of change in pH of the wastewater per unit time is switched from a negative value to a positive value, When the amount of change per unit time increases to a specified value or more, at least one of when the amount of change in conductivity of the wastewater per unit time is less than the specified value is set as the end point of the decomposition treatment of the nitrogen compound It is characterized by that.

  In addition, a wastewater treatment apparatus according to the seventh invention for solving the above-described problem is a treatment tank for storing organic wastewater containing a nitrogen compound, and electrolyzing the wastewater in the treatment tank. In a batch-type wastewater treatment apparatus that comprises electrolyzing the wastewater for a specified treatment time and repeatedly decomposing the nitrogen compound in the wastewater, the nitrogen of the wastewater in the treatment tank. Nitrogen compound detection means for detecting the amount of the compound, and based on a signal from the nitrogen compound detection means, the nitrogen compound in the wastewater in the treatment tank is allowed to have an allowable treatment time shorter than the specified treatment time. However, when it is determined that the decomposition process has been completed in a short time, the process is terminated at that time, and the generation of excess hypochlorous acid is suppressed, and the electrolysis of the batch to be processed next time than the process batch is performed. When it is determined that the nitrogen compound in the wastewater in the treatment tank has not been decomposed within the specified treatment time, by controlling the magnitude of the current of the electrolysis means so as to reduce the ability, Control the magnitude of the current of the electrolysis means so as to increase the electrolysis processing capacity of the batch to be processed next time than the processing batch, and in the wastewater at a time between the specified processing time and the allowable processing time. When it is determined that the nitrogen compound has been decomposed, a control means for controlling the current magnitude of the electrolysis means so as to maintain the electrolysis processing capacity of the processing batch in the batch to be processed next time is provided. It is characterized by being.

  A wastewater treatment apparatus according to an eighth aspect of the present invention is the wastewater treatment apparatus according to the seventh aspect, wherein the control means determines a current value of the electrolysis means during the electrolysis treatment of the wastewater by a predetermined constant value. The adjustment is performed based on any one of a predetermined ratio and a ratio of the time required for the decomposition processing of the batch to the specified processing time.

  A wastewater treatment apparatus according to a ninth aspect of the present invention comprises a treatment tank for storing organic wastewater containing a nitrogen compound, and electrolysis means for electrolyzing the wastewater in the treatment tank, In a batch-type wastewater treatment apparatus that repeats a plurality of times by decomposing the nitrogen compound in the wastewater by electrolyzing the wastewater for a specified treatment time, chlorine ion addition means for adding chlorine ions in the treatment tank, Based on a signal from the nitrogen compound detection means for detecting the amount of the nitrogen compound in the wastewater in the treatment tank and the nitrogen compound detection means, the specified treatment of the nitrogen compound in the wastewater in the treatment tank If it is determined that the decomposition process has been performed in a time shorter than the allowable processing time, which is shorter than the time, the process is terminated at that time, and the generation of excess hypochlorous acid is suppressed while the Control the amount of chlorine ion added from the chlorine ion addition means so as to reduce the electrolysis processing capacity of the batch to be processed next time, and the nitrogen compound in the wastewater in the treatment tank within the specified treatment time. If it is determined that the decomposition treatment has not been completed, the amount of chlorine ion added from the chlorine ion addition means is controlled so as to increase the electrolysis treatment capacity of the batch to be processed next time than the treatment batch, and the prescribed treatment time When the nitrogen compound in the wastewater has been decomposed in a time between that and the allowable processing time, the chlorine can be maintained in the batch to be processed next time. And a control means for controlling the amount of chlorine ions added from the ion addition means.

  In a ninth aspect of the wastewater treatment apparatus according to the tenth aspect of the present invention, the control means sets the chlorine ion addition amount from the chlorine ion addition means to a predetermined constant value, a predetermined constant ratio. The adjustment is based on any one of the ratios of the time required for the decomposition processing of the batch to the specified processing time.

  A wastewater treatment apparatus according to a tenth aspect of the invention is the seventh aspect of the invention, further comprising chlorine ion addition means for adding chlorine ions to the treatment tank, wherein the control means is a signal from the nitrogen compound detection means. If it is determined that the nitrogen compound in the wastewater in the treatment tank has been decomposed in a time shorter than the allowable treatment time shorter than the prescribed treatment time, the treatment is terminated at that time. From the magnitude of the current of the electrolysis means and the chlorine ion addition means so as to reduce the electrolysis treatment capacity of the batch to be processed next time than the treatment batch while suppressing the generation of excessive hypochlorous acid. The amount of added chlorine ions in the treatment tank, and when it is determined that the nitrogen compound in the wastewater in the treatment tank has not been decomposed within the specified treatment time, the next time than the treatment batch A time between the specified processing time and the permissible processing time by controlling the magnitude of the current of the electrolysis means and the amount of chlorine ion added from the chlorine ion addition means so as to increase the electrolysis processing capacity of the batch to be processed. If it is determined that the nitrogen compound in the wastewater has been decomposed in step (b), the amount of current in the electrolysis means and the chloride ion are maintained so that the electrolysis processing capacity of the processing batch is maintained in the batch to be processed next time. It is characterized by controlling the amount of chlorine ion added from the adding means.

  A wastewater treatment apparatus according to a twelfth invention is the wastewater treatment apparatus according to the tenth invention, wherein the control means includes a magnitude of a current value of the electrolysis means and the chlorine ion addition means during the electrolysis treatment of the wastewater. Is adjusted based on any one of a predetermined constant value, a predetermined constant ratio, and a ratio of the time required for the decomposition processing of the batch to the specified processing time. It is characterized by that.

  A wastewater treatment apparatus according to a thirteenth invention is the wastewater treatment apparatus according to the eleventh or twelfth invention, wherein the control means has a current value magnitude of the electrolysis means during the electrolysis treatment of the wastewater and Adjust only one of the amount of chlorine ions added to the wastewater from the chlorine ion addition means until the upper limit value or the lower limit value, and the electrolysis treatment by adjusting to the upper limit value or the lower limit value of the one When the adjustment of the capacity is insufficient, the other is adjusted to adjust the electrolysis processing capacity.

  A wastewater treatment apparatus according to a fourteenth invention is the pH measurement means according to any of the seventh to thirteenth inventions, wherein the nitrogen compound detection means measures the pH of the wastewater in the treatment tank. The redox potential measuring means for measuring the redox potential of the wastewater in the treatment tank, and the conductivity measuring means for measuring the conductivity of the wastewater in the treatment tank, To do.

  A wastewater treatment apparatus according to a fifteenth invention is the wastewater treatment apparatus according to the fourteenth invention, wherein the control means measures the change in pH of the wastewater per unit time measured by the pH measurement means from a negative value to a positive value. When the change amount per unit time of the redox potential of the wastewater measured by the redox potential measuring means increases to a specified value or more, the conductivity of the wastewater measured by the conductivity measuring means is changed. It is characterized in that at least one of when the rate of change per unit time is less than or equal to a specified value is determined as the end point of the decomposition treatment of the nitrogen compound.

  According to the wastewater treatment method and the apparatus according to the present invention, the electrolysis treatment can be performed over the entire treatment time (specified treatment time) that can be used per batch according to the nitrogen compound concentration in the wastewater for each batch. As a result, it is possible to significantly reduce the excess current per unit time and to suppress the formation of excessive hypochlorous acid-based strong oxidants, and to corrode the tank and piping in the subsequent stage. Can be solved.

  Embodiments of a wastewater treatment method and apparatus according to the present invention will be described below with reference to the drawings, but the present invention is not limited to these embodiments.

[First embodiment]
A first embodiment of a wastewater treatment method and apparatus according to the present invention will be described with reference to FIGS. FIG. 1 is a schematic configuration diagram of a wastewater treatment apparatus, FIG. 2 is a flowchart of a wastewater treatment method, and FIG. 3 is a process of the next batch when the treatment is completed within a specified treatment time and shorter than an allowable treatment time. FIG. 4 is an explanatory diagram of the condition setting method, FIG. 4 is an explanatory diagram of the processing condition setting method for the next batch when processing is not completed within the specified processing time, and FIG. 5 is a time between the specified processing time and the allowable processing time. It is a graph showing the relationship between processing time, pH, and nitrogen compound density | concentration at the time of complete | finishing processing.

  As shown in FIG. 1, a treatment tank 11 provided with a stirrer 12 as a stirring means is fed with waste water feeding means for feeding organic waste water 1 containing nitrogen compounds such as human waste. The inlet side of the pump 13 communicates, and a chlorine ion liquid addition device 14 which is a chlorine ion addition means for supplying a chlorine ion liquid 2 containing chlorine ions such as saline is in communication. Inside the processing tank 11, a positive electrode plate 15a and a negative electrode plate 15b are disposed, and a pH sensor 17 serving as a pH measuring unit is disposed. The electrode plates 15 a and 15 b are connected to a DC power supply device 16.

  The pH sensor 17 is connected to an input unit of a control device 19 which is a control means. The output unit of the control device 19 is connected to the DC power supply device 16 and the chlorine ion solution addition device 14, and the control device 19 is connected to the DC power supply device 16 and the chlorine ion based on the signal from the pH sensor 17. The liquid supply device 14 can be controlled (details will be described later).

  In this embodiment, the electrode plates 15a and 15b, the DC power supply device 16 and the like constitute an electrolysis means, and the nitrogen compound detection means for detecting the amount of nitrogen compound in the waste water 1 in the treatment tank 11 is set to pH. The sensor 17 is configured. In FIG. 1, 11a is a discharge valve which is a discharge means.

  Subsequently, a wastewater treatment method using the above-described wastewater treatment apparatus 10 according to the present embodiment will be described.

  First, the feed pump 13 is actuated to supply the waste water 1 to the treatment tank 11 up to a specified amount (S101). Next, the stirrer 12 is operated to stir the wastewater 1 in the treatment tank 11, and the set current value Is (for example, the expected maximum nitrogen compound concentration) between the DC power supply device 16 and the electrode plates 15a and 15b. A current value of a capacity that can be processed within a specified processing time) and a chlorine ion solution 2 from the chlorine ion solution adding device 14 into the processing tank 11 corresponding to a set addition amount Cs (for example, an expected maximum nitrogen compound concentration). If it is input to the control device 19 so that it is added at an addition amount that provides a chlorine ion concentration), the waste water 1 is electrolyzed between the electrode plates 15a and 15b as follows (S102).

On the positive electrode plate 15a side, oxygen (O ₂ ) and hydrogen ions (H ⁺ ) are generated (the following formula (101)), and at the same time, chlorine ions contained in the waste water 1 and added chlorine ion liquid Chlorine (Cl ₂ ) is produced from the chlorine ions of 2 (the following formula (102)), and chlorine is further disproportionated and decomposed near the surface of the positive electrode plate 15a to produce hypochlorous acid and hydrochloric acid (the following formula (103)). On the other hand, hydrogen (H2) and hydroxide ions (OH-) are generated on the negative electrode plate 15b side (the following formula (104)). And the ammonia (NH3) contained from the beginning in the wastewater 1 and the ammonia generated from the negative electrode plate 15b side react with hypochlorous acid to become nitrogen gas (the following formula (105)). Thereby, the nitrogen compound is decomposed.

H ₂ O → _1/2 O ₂ + 2H ⁺ + 2e ⁻ (101)
2Cl ⁻ → Cl ₂ + 2e ⁻ (102)
Cl ₂ + H ₂ O → HClO + HCl (103)
H ₂ O + e ⁻ → 1 / 2H ₂ + OH ⁻ (104)
2NH ₃ + 3HClO → N ₂ + 3HCl + 3H ₂ O (105)

  When the electrolysis treatment is performed in this manner, the amount of hypochlorous acid produced immediately after the start of treatment is larger than the amount of decomposition of nitrogen compounds such as ammonia. Therefore, as shown in FIG. Although the amount of change per unit time (ΔpH) starts to increase (ΔpH ≧ 0 (S103)), since the nitrogen compound such as ammonia is gradually decomposed and decreases, ΔpH of the wastewater 1 begins to decrease (ΔpH <0 (S104) )).

  Then, the controller 19 switches the wastewater 1 when ΔpH switches again from a negative value (ΔpH <0) to a positive value (ΔpH> 0), that is, when all the nitrogen compounds in the wastewater 1 are decomposed. The electrolysis treatment is carried out until the start of pH increase occurs within a predetermined specified treatment time Ts (time that can be treated per batch set from the treatment amount per day of waste water 1: 10 minutes, for example). Continue (S105).

  When the waste liquid 1 does not satisfy ΔpH <0 within the specified processing time Ts, that is, when ΔpH ≧ 0 is detected, the control device 19 stops the operation of the DC power supply device 16 so as to finish the electrolysis process (S106).

  Next, when the control device 19 detects ΔpH ≧ 0, that is, when all the nitrogen compounds in the waste water 1 are decomposed, the control processing time Tp (the specified processing time is shorter than the specified processing time Ts). It is determined whether or not it is within the time (for example, 9 to 10 minutes) between the time that can be regarded as the same as Ts (for example, 9 minutes) and the specified processing time Ts (S107), and detection of ΔpH ≧ 0 is within the time In the case of (see FIG. 5), it is determined that the electrolysis processing capacity of the processing batch, that is, the current value of the DC power supply 16 and the addition amount of the chlorine ion solution 2 of the batch is appropriate, and the electrolysis is performed. The DC power supply device 16 and the chlorine ion solution addition device 14 are controlled so as to maintain the processing capacity (S108).

  Further, as shown in FIG. 3, when ΔpH ≧ 0 is detected, it is outside the time between the allowable processing time Tp and the specified processing time Ts, that is, a time T1 (for example, 8 minutes) shorter than the allowable processing time Tp. In the case of the above, the control device 19 determines whether or not the set current value Is passed between the DC power supply device 16 and the electrode plates 15a and 15b is a predetermined lower limit value (S109). When the set current value Is has not reached the lower limit value, the reduction amount of the set current value Is is calculated (S110), and the next batch is electrolyzed with the new updated current value In1, that is, The direct current power supply device 16 is controlled so as to lower the electrolysis processing capacity of the next batch than the batch. Here, the control device 19 calculates a reduction amount of the set current value Is, that is, a new update current value In1 of the next batch based on the following equation (1).

In1 = Is · (T1 / Ts) · α (1)
However, (alpha) is a safety factor (for example, 1.1).

  When the set current value Is reaches the lower limit value, the control device 19 determines that the reduction adjustment of the electrolysis processing capacity is insufficient only by reducing the current value, and adds the chlorine ion solution to be added. 2 is calculated (S111), and the next batch is electrolyzed with a new renewal addition amount Cn1, that is, chlorine is reduced so that the electrolysis capacity of the next batch is lower than that of the batch. The ionic liquid addition device 14 is controlled. Here, the control device 19 calculates a reduction amount of the set addition amount Cs, that is, a new update addition amount Cn1 of the next batch based on the following equation (2).

Cn1 = Cs · (T1 / Ts) · β (2)
However, (beta) is a safety factor (for example, 1.1).

  On the other hand, as shown in FIG. 4, the waste liquid 1 always has ΔpH <0 within the specified treatment time Ts, that is, all the nitrogen compounds in the waste water 1 can be completely decomposed within the specified treatment time Ts. If ΔpH ≧ 0 cannot be detected, the control device 19 stops the operation of the DC power supply device 16 so as to end the electrolysis processing in order to perform the next processing as scheduled (S112). .

  Then, the control device 19 determines whether or not the set current value Is passed between the electrode plates 15a and 15b from the DC power supply device 16 is a predetermined upper limit value (S113), and the set current value Is. Is not reached the upper limit value, the increase amount of the set current value Is is calculated (S114), and the next batch is electrolyzed with the new updated current value In2, that is, more than the batch. The DC power supply 16 is controlled so as to increase the electrolysis processing capacity of the next batch. Here, the control device 19 calculates the increase amount of the set current value Is, that is, the new update current value In2 of the next batch as follows.

  Based on the past processing data stored in advance, the control device 19 estimates and calculates a pH value starting from ΔpH <0 to ΔpH> 0, that is, pHm, which is the lowest pH value, as shown in FIG. After calculating the treatment time T2 required for decomposing all the nitrogen compounds in the waste liquid 1 with the electrolysis treatment capacity of the current batch based on the following equation (3), the following equation (4) Based on, the update current value In2 is calculated.

T2 = Ts + (pHs−pHm) / ΔpH (3)
In2 = Is · (T2 / Ts) · α (4)
However, pHs is the pH value of the waste liquid 1 at the specified treatment time Ts.

  When the set current value Is reaches the upper limit value, the control device 19 determines that the adjustment for increasing the electrolysis processing capacity is insufficient only by increasing the current value, and adds the chlorine ion solution to be added. 2 is calculated (S115), so that the next batch is electrolyzed with a new renewal addition amount Cn2, that is, the chlorine ion is increased so that the electrolysis capacity of the next batch is higher than that of the batch. The liquid addition apparatus 14 is controlled. Here, the control device 19 calculates the increase amount of the set addition amount Cs, that is, the new update addition liquid amount Cn2 of the next batch based on the above equation (3) and the following equation (5).

Cn2 = Cs · (T2 / Ts) · β (5)

  After determining and setting the electrolysis processing capacity of the next batch as described above (S116), the discharge valve 11a of the processing tank 11 is opened and the treated waste liquid 1a is discharged from the processing tank 11 (S117). The control device is configured to operate the feed pump 13 to newly supply the untreated waste liquid 1 into the treatment tank 11 and to restart the electrolysis process of the waste liquid 1 with the newly obtained electrolysis treatment capacity. 19 controls the DC power supply device 16 and the chlorine ion solution addition device 14. Hereinafter, the above-described operations (S101 to S117) are repeated.

  In other words, in the past, even when the waste water 1 has the maximum nitrogen compound concentration expected, the current having a capacity that can be reliably treated within the specified treatment time Ts is flowed uniformly in all batches. In the embodiment, the current value of the batch to be processed next time based on the result of the processing batch so that the nitrogen compound in the wastewater 1 can be decomposed in the time between the specified processing time Ts and the allowable processing time Tp. The electrolysis processing capacity of the was adjusted. The reason for this processing will be described below.

  As described above, in a facility that treats wastewater 1 by electrolysis (for example, a human waste treatment plant), the daily treatment amount of the wastewater 1 is determined in advance, and the time that can be treated per batch is determined. It will be decided naturally. For this reason, as described above, even in the case of waste water 1 having the maximum nitrogen compound concentration expected, conventionally, a current having a capacity that can be reliably treated within the specified treatment time Ts is uniformly flowed in all batches. It was.

  When treated in this way, when treating a batch of wastewater 1 having a nitrogen compound concentration lower than the expected maximum nitrogen compound concentration, the decomposition process ends earlier than the prescribed treatment time Ts, and after the treatment is completed. Excessive hypochlorous acid-based strong oxidizing substances are generated by the current flowing up to the discharge of the waste water 1, and there is a concern about the corrosion of the piping in the subsequent tank, and the extra processing cost For this reason, it has been considered to eliminate waste of power consumption by stopping the flow of current when the disassembling process is completed.

  However, even if the flow of current is stopped when the decomposition process is finished, the amount of current (coulomb amount) required for the decomposition process is a theory necessary for decomposing the amount of nitrogen compounds in the batch. The amount of current required to decompose all the nitrogen compounds is large relative to the amount of nitrogen compounds in one batch, that is, the processing efficiency is poor and the power consumption is reduced. It became clear that there was still waste.

  As a result of investigating the cause, it was found that the chlorine generation reaction from chlorine ions that occurs in the vicinity of the surface of the positive electrode plate 15a occurs more efficiently at a lower current density.

  Specifically, for example, when the chlorine ion solution is electrolyzed at a current value of 800 A and when the chlorine ion solution is electrolyzed at a current value of 400 A, the effective chlorine generation efficiency (with respect to the supplied current amount (coulomb amount)) The ratio of the amount of chlorine produced was about 60% in the case of 800A, and about 80% in the case of 400A.

  The reason for this is not clear, but the amount per unit time in which electrons can be exchanged between the positive electrode plate 15a and chloride ions is limited, and the excess current per unit time is used for other reactions. It is guessed that it is from.

  Therefore, the wastewater treatment method and the wastewater treatment apparatus 10 according to this embodiment cause waste in the treatment time (specified treatment time Ts) that can be used per batch according to the nitrogen compound concentration in the wastewater 1 for each batch. The electrolysis process is performed over the entire processing time without causing the current to become excessive per unit time.

  Therefore, according to the wastewater treatment method and the wastewater treatment apparatus 10 according to the present embodiment, the power consumption can be reduced and the treatment efficiency can be increased.

[Second Embodiment]
A second embodiment of the wastewater treatment method and apparatus according to the present invention will be described with reference to FIGS. FIG. 6 is a schematic configuration diagram of a wastewater treatment apparatus, FIG. 7 is a flowchart of a wastewater treatment method, and FIG. 8 is a treatment time and oxidation when the treatment is finished in a time between a prescribed treatment time and an allowable treatment time. It is a graph showing the relationship between a reduction potential and a nitrogen compound concentration. In addition, about the part similar to 1st embodiment mentioned above, by attaching | subjecting the code | symbol similar to the code | symbol used in description of 1st embodiment mentioned above to drawing etc., 1st implementation mentioned above. Description overlapping with the form is omitted.

  As shown in FIG. 6, an oxidation-reduction potential sensor (ORP sensor) 27 that is an oxidation-reduction potential measuring unit is disposed inside the processing tank 11. The ORP sensor 27 is connected to an input unit of a control device 29 that is a control means. The output unit of the control device 29 is connected to the DC power supply device 16 and the chlorine ion solution adding device 14, and the control device 29 supplies the DC power supply device 16 and the chlorine ion solution supply based on the signal from the ORP sensor 27. The device 14 can be controlled.

  That is, the wastewater treatment apparatus 20 according to this embodiment replaces the pH sensor 17 that is the nitrogen compound detection means of the wastewater treatment apparatus 10 according to the first embodiment described above with the ORP sensor 27 that is another nitrogen compound detection means. It is a replacement.

  As shown in FIG. 7, the wastewater treatment method using the wastewater treatment apparatus 20 according to this embodiment is configured to treat the untreated wastewater 1 from the treatment tank 11 as in the case of the first embodiment described above. After being fed into the inside (S101), the electrolysis process is started (S102), and when the nitrogen compound is electrolyzed, the nitrogen compound is gradually decomposed and decreases, so that the redox potential (ORP) of the waste water 1 gradually increases. (See FIG. 8).

  When the amount of change in ORP per unit time (ΔORP) increases to a specified value γ (for example, 200 mV) or more, that is, the control device 29, that is, the wastewater due to all the nitrogen compounds in the wastewater 1 being decomposed. The electrolysis process is continued until an ORP increase of 1 occurs within a predetermined specified processing time Ts (S204, S105).

  When the waste liquid 1 does not satisfy ΔORP <γ within the specified processing time Ts, that is, when ΔORP ≧ γ is detected, the control device 29 stops the operation of the DC power supply device 16 so as to finish the electrolysis process (S106).

  Next, when the control device 29 detects ΔORP ≧ γ, that is, when all the nitrogen compounds in the wastewater 1 are decomposed, it is within the time between the allowable processing time Tp and the specified processing time Ts. If the detection of ΔORP ≧ γ is within the time (see FIG. 8), as in the case of the first embodiment described above, the electrolysis processing of the processing batch It is determined that the capacity, that is, the current value of the DC power supply 16 of the batch and the addition amount of the chlorine ion solution 2 are appropriate, and the DC power supply device 16 and the chlorine ion solution addition device 14 are maintained so as to maintain the electrolysis processing capability. Is controlled (S108).

  Hereinafter, the control device 29 performs the same operation (S109 to S117) as in the first embodiment described above, and repeats the above-described operation.

  That is, in the first embodiment described above, the wastewater 1 is changed based on the pH of the wastewater 1, that is, when the ΔpH of the wastewater 1 is switched from a negative value (ΔpH <0) to a positive value (ΔpH> 0). In this embodiment, based on the ORP of the wastewater 1, that is, when the ΔORP of the wastewater 1 increases to a specified value γ or more, in this embodiment, the end point of the decomposition treatment of the nitrogen compound in the wastewater 1 is determined. The end point of the nitrogen compound decomposition treatment was determined.

  Therefore, according to the wastewater treatment method and the wastewater treatment apparatus 20 according to the present embodiment, the power consumption can be reduced and the treatment efficiency can be increased as in the case of the first embodiment described above.

[Other Embodiments]
In the first embodiment described above, based on the pH of the wastewater 1, that is, when the ΔpH of the wastewater 1 is switched from a negative value (ΔpH <0) to a positive value (ΔpH> 0), the wastewater 1 In the second embodiment described above, based on the ORP of the wastewater 1, that is, when the ΔORP of the wastewater 1 increases to a specified value γ or more, the wastewater 1 However, as another embodiment, instead of the pH sensor 17 or the ORP sensor 27, for example, a conductive material that is a conductivity measuring unit as a nitrogen compound detecting unit can be used. Applying a rate meter, based on the conductivity of the wastewater 1, that is, when the amount of change (decrease) per unit time in the conductivity of the wastewater 1 is below a specified value, Judging the end point, It is also possible to perform the same processing as in the first and second embodiments.

  Here, when the nitrogen compound concentration in the waste liquid 1 is relatively high, it is preferable to adjust the electrolysis treatment capacity based on the pH, and when the nitrogen compound concentration in the waste liquid 1 is relatively small, based on the ORP. It is preferable to adjust the electrolysis treatment capacity, and when an electrochemical reaction other than the chemical formulas (101) to (105) described above is difficult to occur in the waste liquid 1, it is preferable to adjust the electrolysis treatment capacity based on the conductivity.

  In the first and second embodiments described above, the magnitude of the current value (Is) and the amount of chlorine ions (Cs) added to the wastewater 1 during the electrolysis treatment of the wastewater 1 are determined for the decomposition of the batch. The amount (In1, In2) of the current value of the batch to be processed next time and the amount of chlorine ions to be added (Cn1) adjusted based on the ratio of the time required for processing (T1, T2) to the specified processing time (Ts) , Cn2) are calculated (equations (1) to (5)). As another embodiment, for example, the magnitude (Is) of the current value in the electrolysis of the wastewater 1 and the wastewater 1 The amount (Cs) of chlorine ions to be added to is adjusted based on a predetermined value (A1 (positive value), A2 (positive value)), that is, in the following formulas (6) to (9) Based on the current value of the batch to be processed next time (In1, In2) and It is also possible to calculate the amount of chloride ion (Cn1, Cn2) is added.

In1 = Is-A1 (6) (corresponding to the formula (1))
Cn1 = Cs−A2 (7) (corresponding to the formula (2))
In2 = Is + A1 (8) (corresponding to the formula (4))
Cn2 = Cs + A2 (9) (corresponding to the formula (5))

  Furthermore, a predetermined ratio (B1 (value less than 1), B2) of the magnitude of current value (Is) and the amount of chlorine ions (Cs) added to the wastewater 1 during the electrolysis treatment of the wastewater 1 (Value exceeding 1)), that is, based on the following formulas (10) to (13), the magnitude of the current value of the batch to be processed next (In1, In2) and the chlorine ion to be added It is also possible to calculate the quantity (Cn1, Cn2).

In1 = Is × B1 (10) (corresponding to the formula (1))
Cn1 = Cs × B1 (11) (corresponding to the formula (2))
In2 = Is × B2 (12) (corresponding to the formula (4))
Cn2 = Cs × B2 (13) (corresponding to the formula (5))

  In the first and second embodiments described above, first, the magnitude of the current value in the electrolysis treatment of the wastewater 1 is adjusted until the upper limit value or the lower limit value is reached, and the electrolysis treatment is performed by this adjustment. When the capacity adjustment is insufficient, the amount of the chlorine ion solution 2 added to the waste water 1 is adjusted to adjust the electrolysis treatment capacity. However, as another embodiment, first, the waste water 1 Adjust the amount of chlorine ion solution 2 added to the upper limit value or lower limit value, and if this adjustment is insufficient to adjust the electrolysis treatment capacity, the current value during the electrolysis treatment of the wastewater 1 It is also possible to adjust the electrolysis treatment capacity by adjusting the size.

  In the first and second embodiments described above, the electrolysis treatment capacity is adjusted by both the magnitude of the current value during the electrolysis treatment of the wastewater 1 and the amount of chlorine ions added to the wastewater 1. However, depending on various conditions such as the properties of the wastewater 1, it is possible to adjust the electrolysis treatment capacity by only one of them.

  INDUSTRIAL APPLICABILITY The wastewater treatment method and apparatus according to the present invention can increase the treatment efficiency of organic wastewater containing nitrogen compounds such as human waste and reduce power consumption. can do.

It is a schematic block diagram of 1st embodiment of the wastewater treatment apparatus which concerns on this invention. It is a flowchart of a first embodiment of the wastewater treatment method according to the present invention. In 1st embodiment, it is explanatory drawing of the processing condition setting method of the next batch at the time of finishing a process shorter than the allowable process time within a regulation process time. In 1st embodiment, it is explanatory drawing of the processing condition setting method of the next batch at the time of not finishing processing within regulation process time. In 1st embodiment, it is a graph showing the relationship between processing time, pH, and nitrogen compound density | concentration at the time of finishing processing in the time between regulation processing time and permissible processing time. It is a schematic block diagram of 2nd embodiment of the waste water treatment apparatus which concerns on this invention. It is a flowchart of 2nd embodiment of the wastewater treatment method which concerns on this invention. In 2nd embodiment, it is a graph showing the relationship between the processing time at the time of finishing processing in the time between regulation processing time and permissible processing time, oxidation-reduction potential, and nitrogen compound concentration.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Waste water 1a Treated waste water 2 Chlorine ion liquid 10 Waste water treatment apparatus 11 Treatment tank 11a Discharge valve 12 Stirrer 13 Feed pump 14 Chlorine ion liquid addition apparatus 15a Positive electrode plate 15b Negative electrode plate 16 DC power supply device 17 pH sensor 19 Controller 20 Waste water treatment equipment 27 ORP sensor 29 Control equipment

Claims (15)

In a batch-type wastewater treatment method in which organic wastewater containing nitrogen compounds is electrolyzed for a specified treatment time and the nitrogen compounds in the wastewater are decomposed multiple times.
When the nitrogen compound in the wastewater is decomposed in a time shorter than the allowable processing time shorter than the specified processing time, the processing is terminated at that time, and excessive hypochlorous acid generation is suppressed. However, the electrolysis processing capacity of the batch to be processed next time is lowered than the processing batch,
If the nitrogen compound in the wastewater has not been decomposed within the specified treatment time, increase the electrolysis treatment capacity of the batch to be processed next time than the treatment batch,
When the nitrogen compound in the wastewater is decomposed at a time between the specified treatment time and the allowable treatment time, the electrolysis treatment capacity of the treatment batch is maintained even in the next treatment batch. Wastewater treatment method. In claim 1,
The electrolysis capacity is
The wastewater treatment method characterized by being adjusted by at least one of the magnitude of the current value in the electrolysis treatment of the wastewater and the amount of chlorine ions added to the wastewater. In claim 2,
At least one of the magnitude of the current value during the electrolysis treatment of the waste water and the amount of chlorine ions added to the waste water is a predetermined constant value, a predetermined constant ratio, the batch A wastewater treatment method, characterized in that the wastewater treatment method is adjusted based on any of the ratios of the time required for the decomposition treatment to the specified treatment time. In claim 2 or claim 3,
Adjust only one of the magnitude of the current value during the electrolysis treatment of the wastewater and the amount of chlorine ions added to the wastewater until reaching the upper limit or lower limit,
A wastewater treatment method comprising adjusting the electrolysis treatment capacity by adjusting the other when adjustment of the electrolysis treatment capacity is insufficient by adjustment to the upper limit value or the lower limit value. In any one of Claims 1-4,
An end point of the decomposition treatment of the nitrogen compound in the wastewater is determined based on at least one of pH, oxidation-reduction potential, and conductivity of the wastewater. In claim 5,
When the amount of change in pH of the wastewater per unit time is switched from a negative value to a positive value, when the amount of change in the oxidation-reduction potential of the wastewater per unit time increases to a specified value or more, the conductivity of the wastewater A wastewater treatment method, wherein at least one of the rate of change per unit time of the rate is equal to or less than a specified value is set as the end point of the decomposition treatment of the nitrogen compound. A treatment tank for storing organic wastewater containing nitrogen compounds;
Electrolysis means for electrolyzing the wastewater in the treatment tank,
In a batch-type wastewater treatment apparatus that repeats a plurality of times by decomposing the nitrogen compound in the wastewater by electrolyzing the wastewater for a specified treatment time,
Nitrogen compound detection means for detecting the amount of the nitrogen compound in the wastewater in the treatment tank;
When it is determined based on the signal from the nitrogen compound detection means that the nitrogen compound in the wastewater in the treatment tank has been decomposed in a time shorter than the allowable treatment time shorter than the specified treatment time. Is the current of the electrolytic means so as to lower the electrolysis processing capacity of the batch to be processed next time than the processing batch while terminating the processing at that time and suppressing the generation of excessive hypochlorous acid. If the nitrogen compound in the wastewater in the treatment tank is determined to have not been decomposed within the specified treatment time, the electrolytic treatment of the batch to be processed next time than the treatment batch When it is determined that the nitrogen compound in the wastewater has been decomposed in a time between the specified treatment time and the allowable treatment time by controlling the magnitude of the current of the electrolyzing means so as to enhance the capacity , Waste water treatment apparatus, characterized in that a control means for controlling the magnitude of current of the electrolysis means so as to be maintained in batch process electrolysis processing capability of the processing batch next. In claim 7,
The control means is
The magnitude of the current value of the electrolyzing means during the electrolysis treatment of the waste water is a predetermined constant value, a predetermined constant ratio, a ratio of the time required for the decomposition process of the batch to the specified processing time. A wastewater treatment apparatus characterized in that it is adjusted based on any one of them. A treatment tank for storing organic wastewater containing nitrogen compounds;
Electrolysis means for electrolyzing the wastewater in the treatment tank,
In a batch-type wastewater treatment apparatus that repeats a plurality of times by decomposing the nitrogen compound in the wastewater by electrolyzing the wastewater in the treatment tank for a specified treatment time,
Chlorine ion addition means for adding chlorine ions to the treatment tank;
Nitrogen compound detection means for detecting the amount of the nitrogen compound in the wastewater in the treatment tank;
When it is determined based on the signal from the nitrogen compound detection means that the nitrogen compound in the wastewater in the treatment tank has been decomposed in a time shorter than the allowable treatment time shorter than the specified treatment time. From the chlorine ion addition means so as to lower the electrolysis processing capacity of the batch to be processed next time than the processing batch while terminating the processing at that time and suppressing the generation of excessive hypochlorous acid. When the amount of added chlorine ions is controlled and it is determined that the nitrogen compound in the wastewater in the treatment tank has not been decomposed within the specified treatment time, the batch to be treated next time than the treatment batch. The amount of chlorine ions added from the chlorine ion addition means is controlled so as to enhance the electrolysis treatment capacity, and the nitrogen in the wastewater is between the specified treatment time and the allowable treatment time. If it is determined that the compound has been decomposed, a control means for controlling the amount of chlorine ions added from the chlorine ion addition means so as to maintain the electrolysis processing capacity of the treatment batch in the next batch to be processed. A wastewater treatment apparatus characterized by comprising. In claim 9,
The control means is
The chlorine ion addition amount from the chlorine ion addition means is based on one of a predetermined constant value, a predetermined constant ratio, and a ratio of the time required for the decomposition processing of the batch to the specified processing time. A wastewater treatment device characterized by being adjusted. In claim 7,
Provided with chlorine ion addition means for adding chlorine ions in the treatment tank,
The control means is
When it is determined based on the signal from the nitrogen compound detection means that the nitrogen compound in the wastewater in the treatment tank has been decomposed in a time shorter than the allowable treatment time shorter than the specified treatment time. Is the current of the electrolytic means so as to lower the electrolysis processing capacity of the batch to be processed next time than the processing batch while terminating the processing at that time and suppressing the generation of excessive hypochlorous acid. When the amount of chlorine ions added from the chlorine ion addition means is controlled and it is determined that the nitrogen compound in the wastewater in the treatment tank has not been decomposed within the specified treatment time, the treatment Control the magnitude of the current of the electrolysis means and the amount of chlorine ions added from the chlorine ion addition means so as to increase the electrolysis processing capacity of the batch to be processed next time than the batch, When it is determined that the nitrogen compound in the wastewater has been decomposed in a period between the physical treatment time and the allowable treatment time, the electrolysis treatment capacity of the treatment batch is maintained in the next treatment batch. A wastewater treatment apparatus characterized by controlling the magnitude of current of the electrolyzing means and the amount of chlorine ions added from the chlorine ion adding means. In claim 11,
The control means is
The current value of the electrolysis means and the amount of chlorine ions added from the chlorine ion addition means during the electrolysis treatment of the waste water are set to a predetermined constant value, a predetermined constant ratio, and decomposition of the batch. The wastewater treatment apparatus, wherein the wastewater treatment apparatus is adjusted based on any one of a ratio of a time required for the treatment to the specified treatment time. In claim 11 or claim 12,
The control means is
Until either the magnitude of the current value of the electrolysis means during the electrolysis treatment of the waste water or the amount of chlorine ions added to the waste water from the chlorine ion addition means reaches the upper limit value or the lower limit value Adjust
When the adjustment of the electrolysis treatment capacity is insufficient due to the adjustment to the one upper limit value or the lower limit value, the other is adjusted to adjust the electrolysis treatment capacity. In any of claims 7 to 13,
The nitrogen compound detection means comprises
PH measurement means for measuring the pH of the wastewater in the treatment tank, oxidation-reduction potential measurement means for measuring the oxidation-reduction potential of the wastewater in the treatment tank, and conductivity for measuring the conductivity of the wastewater in the treatment tank. It is at least one of rate measuring means. In claim 14,
The control means is
When the amount of change per unit time in the pH of the wastewater measured by the pH measuring means is switched from a negative value to a positive value, the redox potential of the wastewater measured by the redox potential measuring means per unit time When the amount of change in the wastewater measured by the conductivity measuring means is less than a specified value when at least one of the changes in conductivity of the wastewater measured by the conductivity measuring means is less than a specified value A wastewater treatment apparatus characterized by determining the end point of treatment.

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