JP4185725B2 - Waste water treatment apparatus and waste water treatment method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wastewater treatment apparatus and a wastewater treatment method for treating wastewater containing hydrogen peroxide and fluorine. Furthermore, the present invention relates to a wastewater treatment apparatus and a wastewater treatment method that can recycle the chemicals to be used without waste. Furthermore, the present invention relates to a wastewater treatment apparatus and a wastewater treatment method that can stabilize the hydrogen peroxide concentration and fluorine concentration of treated water at a low level.
[0002]
[Prior art]
Since April 2001, the PRTR (Pollutant Release and Transfer Register) Act (Act on Understanding of the Release of Specific Chemical Substances into the Environment and Promotion of Improvements in Management) has led to the environment of harmful chemical substances such as fluorine. The amount of emissions is attracting attention.
[0003]
In addition, today, when global environmental efforts have become the most important items, it is important to reduce the amount of sludge generated from wastewater treatment equipment and the amount of fluorine as a hazardous chemical that is discharged into the environment through treated water. It is a theme.
[0004]
For example, hydrogen peroxide and fluorine-containing wastewater in a semiconductor factory with a large amount of wastewater has generally been treated by equipment such as a two-stage coagulation sedimentation apparatus.
[0005]
With reference to FIG. 4, the processing method of the fluorine-containing waste water in a prior art is demonstrated. After the fluorine-containing wastewater is introduced and stored in the raw water tank 132, the wastewater is introduced into the first rapid stirring tank 121 by the raw water tank pump 133, and further, slaked lime slurry is injected and stirred. As a result, fluorine in the wastewater reacts with calcium derived from slaked lime to form stable fine calcium fluoride.
[0006]
Next, this fine calcium fluoride is introduced into the first slow stirring tank 122, and a polymer flocculant and a reducing agent such as sodium bisulfite for treating hydrogen peroxide as an oxidizing agent are added. Being a big stable floc. Next, it is introduced into the first settling tank 123 for solid-liquid separation. The sludge precipitated in the first settling tank 123 contains a large amount of unreacted slaked lime due to the short reaction time with the waste water in the first rapid stirring tank 121 and the first slow stirring tank 122.
[0007]
In general, the reason why the reaction time in the first rapid stirring tank 121 and the first slow stirring tank 122 cannot be taken sufficiently is that if the reaction time is taken sufficiently, the capacity of the water tank becomes enormous, and the construction cost and installation space of the water tank This is because there are difficulties. Then, the waste water firstly treated in the first sedimentation tank 123 is further introduced into the second rapid stirring tank 125 to reduce the fluorine concentration in the waste water, and polyaluminum chloride as an inorganic chemical is added.
[0008]
A small amount of fluorine in the waste water is adsorbed by aluminum hydroxide caused by polyaluminum chloride added in a large amount to form fine flocs, and is introduced into the second slow stirring tank 126. In the second slow agitation tank 126, a polymer flocculant is added, and the fine floc becomes a larger and more stable floc and is introduced into the second precipitation tank 127 for solid-liquid separation. Precipitate at 127. The floc precipitated in the second settling tank 127, that is, sludge, contains a large amount of aluminum hydroxide. The fluorine value of the treated water discharged from the second sedimentation tank 127 varies depending on the fluctuation of the fluorine concentration in the fluorine-containing wastewater flowing into the raw water tank 132. The sludge precipitated in the first sedimentation tank 123 and the second sedimentation tank 127 is introduced into the concentration tank 129 by the pumps 124 and 128 and concentrated, and further transferred to the filter press 131 by the pump 130 for dehydration. Is done.
[0009]
Another conventional method for treating fluorine-containing wastewater is described in JP-A-10-137769 (NEC Corporation). This conventional technology desorbs the fluorine adsorbed on aluminum hydroxide as calcium fluoride and facilitates separation of calcium fluoride by-product when regenerating aluminum hydroxide as a fluorine adsorbent and is necessary for wastewater treatment. The purpose is to reduce the use of various chemicals.
[0010]
More specifically, in the aluminum dissolution tank, when aluminum hydroxide is made alkaline and dissolved as aluminate ions, aluminum hydroxide is not completely dissolved but partially remains, and the remaining aluminum hydroxide is agglomerated. As an auxiliary agent, insoluble components are precipitated in the third settling tank. The sedimentation property of the insoluble component in the third sedimentation tank is monitored by a sedimentation monitor, and the dissolution of aluminum hydroxide in the aluminum dissolution tank is controlled so as to obtain a predetermined sedimentation property.
[0011]
The generated highly treated sludge is returned to the primary treatment tank by calcium fluoride generation, and aluminum hydroxide contained in the highly treated sludge is reused as part of the calcium fluoride aggregation aid. However, this conventional technique cannot treat hydrogen peroxide simultaneously.
[0012]
As another conventional technique, there is a treatment method and treatment apparatus (NEC Corporation) described in JP-A 2000-84570.
[0013]
This conventional technology does not require high-level treatment for high-concentration fluorine wastewater, and always treats fluorine stably and sufficiently to a low concentration in one step, and also occurs due to the amount of chemicals required for treatment and treatment. The purpose is to greatly reduce the amount of sludge. More specifically, the fluorine ions in the wastewater are fixed as calcium fluoride in the reaction tank, and the precipitate slurry composed of calcium fluoride and aluminum hydroxide is precipitated and separated in the settling tank using aluminum hydroxide as a coagulant aid. Pull out a part and return it to the aluminum recycling tank. In this aluminum regeneration tank, high concentration of calcium is allowed to act on the fluorine adsorbed on the aluminum hydroxide at a pH of 9 or less and fixed as calcium fluoride, and then returned to the reaction tank. Thereby, the aluminum hydroxide having fluorine adsorptivity is circulated so as to have a high concentration in the system. However, this conventional technique cannot treat hydrogen peroxide simultaneously.
[0014]
Therefore, for example, the fluorine-containing wastewater discharged from the semiconductor factory contains hydrogen peroxide, but the fluorine in the wastewater and the hydrogen peroxide in the wastewater are treated in separate water tanks. That is, fluorine in wastewater is treated with a combination of slaked lime, polyaluminum chloride, and polymer flocculant, while hydrogen peroxide in wastewater has been treated by adding sodium bisulfite as a reducing agent.
[0015]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to treat wastewater that can simultaneously treat hydrogen peroxide in the treatment of fluorine-containing wastewater, and can reduce the amount of chemicals used by recycling unreacted chemicals and the amount of sludge generated. It is in providing an apparatus and a waste-water-treatment method.
[0016]
[Means for Solving the Problems]
  In order to achieve the above object, a wastewater treatment apparatus of the present invention is a wastewater treatment apparatus for treating wastewater containing hydrogen peroxide and fluorine as treated water,
  A recycling tank into which the water to be treated is introduced, and a precipitation tank at the rear stage of the recycling tank,
  A mixture obtained by mixing microbial treated water obtained from another system and sludge generated from the settling tank is introduced into the recycling tank, and the recycling tank causes the mixture to contact with the treated water.Wastewater treatment equipment,
  A first recycling tank on the front side and a second recycling tank on the rear side,
  The pH setting value in the first recycling tank was pH 7, and the pH setting value in the second recycling tank was pH 5.
[0017]
In the wastewater treatment apparatus of the present invention, a mixture obtained by mixing microbial treated water obtained from another system and sludge generated from the settling tank is contacted with wastewater containing hydrogen peroxide and fluorine by the recycling tank. . Therefore, the amount of chemicals used and sludge generation can be reduced by recycling the unreacted chemical in the sludge by bringing it into contact with the water to be treated again in the recycling tank. Moreover, since the hydrogen peroxide contained in the waste water can be treated with the microbially treated water obtained from the separate system, chemical costs for treating the hydrogen peroxide can be saved. Therefore, according to the present invention, in the treatment of fluorine-containing wastewater, hydrogen peroxide can be simultaneously treated, and the amount of chemicals used and the amount of sludge generated can be reduced by recycling unreacted chemicals.
[0018]
Moreover, the waste water treatment apparatus of one Embodiment is provided with two or more said recycling tanks. Moreover, the sludge generated from the settling tank contains calcium and aluminum.
[0019]
In this embodiment, by providing a plurality of the recycling tanks, one of the plurality of recycling tanks can be the calcium recycling tank corresponding to the calcium. Another one of them can be the aluminum recycling tank corresponding to the aluminum. That is, a recycling tank corresponding to each of the two components calcium and aluminum contained in the sludge generated from the settling tank can be constructed. Therefore, the treatment efficiency in the waste water treatment apparatus can be increased. Moreover, the fluorine value of the treated water can be stabilized by providing a plurality of the recycling tanks.
[0020]
Moreover, the waste water treatment apparatus of one Embodiment is provided with the 1st recycling tank of the front | former stage side, and the 2nd recycling tank of the back | latter stage side. The pH setting value in the first recycling tank was set to approximately pH 7, and the pH setting value in the second recycling tank was set to approximately pH 5.
[0021]
The wastewater treatment apparatus of this embodiment includes first and second recycle tanks, and the pH set value in the first recycle tank is set to approximately pH 7, and the pH set value in the second recycle tank is approximately set. The pH was 5. Therefore, the first recycling tank can be set to a pH setting (around pH 7) adapted to calcium recycling, and the second recycling tank can be set to a pH setting (around pH 5) adapted to aluminum recycling. . Thereby, in the said 1st recycle tank, the said calcium is utilized for the fluorine process in waste_water | drain, and the calcium in the said sludge can be recycled effectively. In the second recycling tank, the aluminum in the sludge can be effectively recycled by making use of the aluminum for the fluorine treatment in the waste water. As a result, it is possible to reduce the amount of chemicals used and the amount of sludge generated, stabilize the fluorine value of the treated water, and increase the wastewater treatment efficiency.
[0022]
For example, in the first recycling tank, since the pH setting value is approximately pH 7, unreacted slaked lime in the sludge can be consumed by the acid component in the raw water, and in the second recycling tank, the pH setting value is approximately Since the pH is 5, aluminum can be easily eluted from the sludge from which unreacted slaked lime has disappeared. Therefore, the eluted aluminum can be used for the fluorine treatment in the waste water, and the aluminum can be recycled.
[0023]
Moreover, the waste water treatment apparatus of one Embodiment has a coagulation sedimentation apparatus in the back | latter stage of the said 1st, 2nd recycling tank. Waste water containing hydrogen peroxide and fluorine is introduced as treated water into the lower portions of the first and second recycling tanks. Moreover, the mixture which mixed microbial treated water and the sludge from the said coagulation sedimentation apparatus is introduce | transduced into the upper part of a said 1st recycle tank.
[0024]
In the wastewater treatment apparatus of this embodiment, the mixture obtained by mixing the microbial treated water and the sludge from the coagulation sedimentation apparatus is introduced into the upper part of the first recycling tank and settles in the lower part of the first recycling layer. . On the other hand, the wastewater containing hydrogen peroxide and fluorine is introduced into the lower part of the first and second recycling tanks and moves to the upper part of the first and second recycling tanks. As a result, the mixture falls from the top to the bottom, and the drainage rises from the bottom to the top, and moves in opposite directions. Therefore, even without a stirrer, the efficiency of the reaction between the waste water and the mixture can be improved and the processing efficiency can be improved.
[0025]
Further, in the wastewater treatment apparatus of this embodiment, by introducing the mixture into the upper part of the first recycling tank, the unreacted chemical (for example, unreacted slaked lime) contained in the sludge contained in the mixture is first added. In addition, it is possible to recycle in the first recycling tank. And if it becomes the environment of about pH 7 in a 1st recycle tank, the unreacted chemical | medical agent (for example, unreacted slaked lime) corresponding to this pH setting value will be consumed. Thereafter, sludge that has used up unreacted chemicals is introduced into the second recycle tank 11, and aluminum contained in the sludge can be eluted in an environment of approximately pH 5 in the second recycle tank. Therefore, this aluminum can be used for the fluorine treatment contained in the waste water and can be recycled.
[0026]
Moreover, the waste water treatment apparatus of one Embodiment introduce | transduces the sludge settled in the said 1st recycle tank into the said 2nd recycle tank.
[0027]
In the wastewater treatment apparatus of this embodiment, the sludge in which the unreacted substance (for example, unreacted slaked lime) contained in the sludge is consumed by the first recycle tank is introduced into the second recycle tank, and the pH is adjusted. Since it is managed in the vicinity of 5, the aluminum can be easily eluted from the sludge, and this aluminum can be used for the fluorine treatment in the waste water, so that the aluminum can be recycled efficiently.
[0028]
Moreover, the waste water treatment method of one Embodiment is equipped with the mixing process which mixes the sludge from a coagulation sedimentation apparatus, and microorganisms treated water. Furthermore, this wastewater treatment method introduces wastewater containing hydrogen peroxide and fluorine into water to be treated into a plurality of recycling tanks having different pH setting values, and mixes the mixture mixed in the mixing step into the recycling tank. A first processing step to be introduced is provided. Furthermore, this waste water treatment method includes a second treatment step of treating the treated water obtained from the recycling tank by introducing it into the coagulation sedimentation apparatus.
[0029]
In this embodiment, since the sludge from the coagulation sedimentation apparatus and the microbially treated water are mixed by the mixing step, the microorganisms in the microbially treated water are fixed to the sludge. Therefore, anaerobic microorganisms propagate using this sludge as an immobilization carrier. In addition, the first treatment step introduces the wastewater containing hydrogen peroxide and fluorine, and the mixture of the sludge and the microorganism treated water into a plurality of recycling tanks having different pH set values. In addition, processing suitable for a plurality of components having different pH (for example, calcium and aluminum) can be performed, and the processing efficiency can be improved.
[0030]
Furthermore, in the second treatment step, since the water to be treated is treated in the plurality of recycling tanks and then further treated in the coagulation sedimentation apparatus, the quality of the treated water is reduced and the water quality is reduced. There is an effect of further stabilization.
[0031]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on illustrated embodiments.
[0032]
(First embodiment)
In FIG. 1, the structure of 1st Embodiment of the waste water treatment equipment of this invention is shown. In FIG. 1, reference numeral 1 denotes a first recycle tank, and this first recycle tank 1 is composed of a first recycle tank lower part 8 and a first recycle tank upper part 9.
[0033]
The waste water treatment apparatus of the first embodiment includes a first recycle tank 1, a second recycle tank 11, a first rapid agitation tank 21, a first slow agitation tank 22, a first precipitation tank 23, and a second rapid agitation. A tank 25, a second slow stirring tank 26, a second precipitation tank 27, a concentration tank 29 and a mixing tank 35 are provided. The first rapid agitation tank 21, the first slow agitation tank 22 and the first precipitation tank 23 constitute a coagulation sedimentation apparatus. Further, the second rapid stirring tank 25, the second slow stirring tank 26, and the second precipitation tank 27 constitute another coagulating sedimentation apparatus.
[0034]
In the first embodiment, hydrogen peroxide and fluorine-containing wastewater having pH 2 to pH 3 are supplied from the introduction pipe 2 installed in the lower part 8 of the first recycling tank 1 to the first recycling tank 1. Introduced. The introduction pipe 2 can be of various types, such as a type in which a large number of holes are opened in a polyvinyl chloride (vinyl chloride) pipe, but is not particularly limited. As long as it can be introduced evenly.
[0035]
Microbial treated water obtained from a system different from this waste water treatment apparatus is introduced into the mixing tank 35, and sludge precipitated in the first settling tank 23 is introduced by the first settling tank pump 24. In the mixing tank 35, mixed sludge is formed as a mixture in which the microorganism-treated water and the sludge are mixed. The mixed sludge is introduced from the mixing tank 35 into the first recycling tank 1, and the mixed sludge mixed in the mixing tank 35 is introduced into the first recycling tank 1 and precipitated at the first recycling tank lower portion 8. is doing.
[0036]
The mixed sludge is used as a microorganism-immobilized carrier (that is, “Suika”), and anaerobic microorganisms are propagated in the mixed sludge. The reason why anaerobic microorganisms are propagated in this mixed sludge is that the first recycle tank 1 is not aerated, so that anaerobic microorganisms propagate in a large amount in the microbial treated water contained in the mixed sludge. is there. On the other hand, the hydrogen peroxide and fluorine-containing wastewater introduced into the first recycling tank 1 is acidic with a pH of 2 to 3, but as a result of reacting with unreacted slaked lime in the mixed sludge, the mixed sludge has a pH of 7 Nearby neutrality. Thereby, anaerobic microorganisms can be propagated in the mixed sludge.
[0037]
And the hydrogen peroxide in the said hydrogen-containing wastewater and fluorine-containing waste water is processed by the reducibility which an anaerobic microorganism has. Incidentally, aerobic microorganisms are oxidizing because they like oxygen.
[0038]
Further, the sludge precipitated in the first recycle tank lower portion 8 contains a large amount of unreacted slaked lime, aluminum hydroxide and microorganisms. Unreacted slaked lime reacts with the water to be treated (that is, the hydrogen peroxide and fluorine-containing waste water) at the lower part of the lower part 8 of the first recycling tank, and the treated sludge gradually moves to the first barrier 3. It passes below and stays in the first sedimentation section 10. The first blocking wall 3 is a blocking wall for preventing the introduced fluorine-containing wastewater from being discharged by the first supernatant discharge pump 6 without reacting with the sludge. In addition, the first sedimentation portion 10 has an inclined portion 5 that is recessed toward the bottom. The presence of the inclined portion 5 makes it easier to collect the sludge at the bottom. Further, the waste water that has reacted with the sludge becomes the first sedimentation supernatant 7 and is transferred to the first rapid stirring tank 21 by the first supernatant discharge pump 6.
[0039]
The sludge that does not contain unreacted slaked lime that has moved to the first sedimentation unit 10 is, by the first sludge discharge pump 4, the second recycling tank upper part 19 included in the second recycling tank 11 subsequent to the first recycling tank 1. To be introduced. The pH of the sludge from the first recycle tank 1 introduced into the second recycle tank upper portion 19 is controlled around 7. The sludge introduced into the second recycle tank upper portion 19 gradually settles and moves to the second recycle tank lower portion 18.
[0040]
An introduction pipe 12 is installed in the second recycling tank lower portion 18 of the second recycling tank 11, and hydrogen peroxide and fluorine-containing waste water is discharged from the introduction pipe 12 to the second recycling tank lower portion 18 as treated water. To do. The hydrogen peroxide in the waste water is treated by the reducing property of anaerobic microorganisms. Incidentally, aerobic microorganisms are oxidizing because they like oxygen.
[0041]
In the second recycle tank 11, hydrogen peroxide and fluorine-containing waste water having a low pH (that is, pH 2 to pH 3) are discharged from the introduction pipe 12 to the second recycle tank lower portion 18. As a result, the sludge near pH 7 introduced from the first sedimentation section 10 of the first recycle tank 1 into the second recycle tank 11 reacts with the wastewater having the pH 2 to 3 so that the pH is around 5. Become. The sludge can be easily managed in the vicinity of pH 5 by adjusting and managing the amount of the water to be treated introduced from the introduction pipe 12 into the second recycling tank lower portion 18 with an introduction pump (not shown).
[0042]
In the second recycle tank lower portion 18, when the pH of the sludge becomes around 5, aluminum ions are eluted from the aluminum hydroxide in the sludge into the water. The waste water from which the aluminum ions are eluted becomes the second sedimentation supernatant 17 and is introduced into the first rapid stirring tank 21 by the second supernatant discharge pump 16, and the first slow stirring tank 22, the first It is introduced into the second rapid stirring tank 25 via the precipitation tank 23. Thus, aluminum ions can be supplied to the second rapid stirring tank 25, and the amount of polyaluminum chloride added in the second rapid stirring tank 25 can be reduced. That is, aluminum as a chemical is recycled.
[0043]
The sludge in the lower part 18 of the second recycle tank is weakly acidic near pH 5, but anaerobic microorganisms grow along with the environment near pH 5 over time, and thus peroxidize in the wastewater. Hydrogen can be decomposed.
[0044]
The second blocking wall 13, the second supernatant discharge pump 16, and the second sludge discharge pump 14 in the second recycling tank 11 are the same as the first blocking wall 3, the first supernatant pump 6 in the first recycling tank 1, It has the same function as the first sludge discharge pump 4. However, the sludge from which aluminum near pH 5 discharged by the second sludge discharge pump 14 is eluted is transferred to the concentration tank 29 and concentrated. The concentrated sludge is transferred to the filter press 31 by the concentration tank pump 30 and dehydrated to form a dehydrated cake. Moreover, the 2nd sedimentation part 20 of this 2nd recycle tank 11 is the same as the 1st recycle tank 1 in the point which has the inclination part 15 which swelled toward the bottom. The presence of the inclined portion 15 makes it easy to collect the sludge at the bottom.
[0045]
On the other hand, the supernatant obtained from the first sedimentation supernatant 7 and the second sedimentation supernatant 17 is first agitated by the first supernatant drainage pump 6 and the second supernatant drainage pump 16. It is transferred to the tank 21 and excess slaked lime is added. The wastewater containing fluorine and the excess slaked lime added react with stirring by a rapid stirrer (not shown) to form fine and chemically stable calcium fluoride. Next, the wastewater flows into the first slow agitation tank 22, and a polymer flocculant is added and stirred by a slow agitator (not shown). It becomes a frock. And this large stable floc flows into the 1st sedimentation tank 23 from the 1st slow stirring tank 22, and precipitates.
[0046]
Further, the slaked lime added excessively in the first rapid stirring tank 21 is precipitated in the first settling tank 23 together with the calcium fluoride floc. And since the slaked lime is excessive, the sludge containing unreacted slaked lime is returned to the first recycle tank 1 from the first settling tank 23 via the mixing tank 35 by the first settling tank pump 24, In the first recycling tank 1, unreacted slaked lime is recycled by contact reaction with hydrogen peroxide and fluorine-containing waste water.
[0047]
Here, the reason why the sludge from the mixing tank 35 is introduced only into the tank upper part 9 of the first recycling tank 1 is to first recycle unreacted slaked lime in the sludge. And if it becomes the environment of pH7 vicinity, the said unreacted slaked lime is consumed, Then, the sludge which used up the unreacted slaked lime is introduce | transduced into the 2nd recycle tank 11, and aluminum is eluted in the environment of pH5 vicinity, Aluminum can be recycled. Moreover, the elution of aluminum will become more reliable if the sludge which has used up unreacted slaked lime is introduced into the second recycling tank 11. The reason why the pH in the recycling tanks 1 and 11 of the first and second tanks is not set to 5 from the beginning is that the elution of aluminum does not proceed smoothly even if the pH is adjusted to around 5 in the presence of unreacted slaked lime. Because.
[0048]
Next, the supernatant obtained in the first sedimentation tank 23 is transferred to the second rapid stirring tank 25, and excess polyaluminum chloride is added thereto. In the second rapid agitation tank 25, the waste water containing fluorine and the excess polyaluminum chloride added are agitated and reacted by a rapid agitator (not shown), and the formed aluminum hydroxide flocs are discharged into the waste water. Fluorine is comprehensively adsorbed and processed.
[0049]
Next, the wastewater flows into the second slow agitation tank 26, and the polymer flocculant is added and stirred by a slow agitator (not shown). It becomes a frock. This floc flows into the second settling tank 27 and precipitates.
[0050]
Further, the aluminum hydroxide floc formed by adding excess polyaluminum chloride in the second rapid stirring tank 25 is returned to the first rapid stirring tank 21 by the second settling tank pump 28, and in order, It returns to the 1st recycle tank 1 through the 1 slow stirring tank 22, the 1st sedimentation tank 23, and the mixing tank 35.
[0051]
The aluminum hydroxide floc (that is, aluminum hydroxide sludge) is introduced into the second recycle tank 11 by the first sludge discharge pump 4 of the first recycle tank 1. In the second recycle tank 11, when the pH of the second recycle tank 11 is around 5, aluminum is eluted from the aluminum hydroxide sludge and aluminum is recycled.
[0052]
In addition, it became clear by experiment that aluminum elutes from aluminum hydroxide sludge in the environment below pH 5 or less. Further, in the environment of pH 4 or pH 3 lower than pH 5, aluminum is further eluted from the aluminum hydroxide sludge. However, it is not economical to lower the pH too much in the second recycle tank 11 in view of raising the pH to alkaline in the next step in the first rapid stirring tank 21. Therefore, in the second recycling tank 11, aluminum can be sufficiently recycled at a pH of around 5.
[0053]
By the way, the reason why slaked lime is excessively added in the first rapid stirring tank 21 and polyaluminum chloride is excessively added in the second rapid stirring tank 25 is that if these chemicals are not added excessively, the value of fluorine This is because does not decrease to the target fluorine value.
[0054]
In this 1st Embodiment, since the 2 tanks, the 1st recycling tank 1 and the 2nd recycling tank 11, are installed, these 1st, 2nd recycling tanks 1 and 11 also have the function of an adjustment tank, Even if the fluorine concentration in the hydrogen peroxide and fluorine-containing wastewater fluctuates, the fluorine concentration in the treated water obtained from the second precipitation tank 27 can be stabilized.
[0055]
As described above, according to the first embodiment, the first and second unique recycling tanks 1 and 11 are constructed in the waste water treatment apparatus, and fluorine is treated in three stages. Since the treatment is performed in three stages, the fluorine concentration of the treated water can be stably reduced. The three-stage treatment means that the fluorine in the waste water is three-stage treated with three kinds of chemicals. That is, the first stage is a treatment with unreacted slaked lime of fluorine in the first recycling tank 1, the second stage is a treatment with eluted aluminum with pH 5 in the second recycling tank 11, and the third stage is the first stage. This is a process for forming a larger floc by the polymer flocculant in the slow stirring tank 22.
[0056]
In addition, since the 1st rapid stirring tank 21 becomes a front water tank of the 1st recycle tank 1, and the reaction time of what adds slaked lime is short, it becomes a water tank in which a large amount of unreacted slaked lime is generated. That is, the first rapid stirring tank 21 is an alias, an unreacted slaked lime water tank. Accordingly, the first stage treatment of fluorine is basically carried out in the first recycle tank 1 having a sufficient reaction time.
[0057]
In the first embodiment, the unique first and second recycle tanks 1 and 11 are different from each other by setting a difference in the pH setting value in the management of the two recycle tanks 1 and 11. We are trying to improve the efficiency of recycling.
[0058]
According to the first embodiment, fluorine in the waste water and hydrogen peroxide in the waste water can be treated in the same water tank (first and second recycle tanks 1 and 11). Further, unreacted slaked lime in the sludge precipitated in the first settling tank 23 can be introduced into the first recycle tank 1 and reused. In addition, the aluminum hydroxide floc precipitated in the second settling tank 27 is first introduced into the first rapid stirring tank 21, and a part of the floc is reused. Precipitating in 1 settling tank 23 and further introducing into the first recycle tank 1, reusing the unreacted slaked lime in the sludge, and remaining aluminum hydroxide in the second recycle tank 11 at a pH of around 5 Elution from the sludge can be reused.
[0059]
Moreover, in this 1st Embodiment, the process of the hydrogen peroxide as an oxidizing agent in waste_water | drain is processed by making anaerobic microorganisms (having reducibility) propagate in sludge. For this purpose, a new mixing tank 35 is installed, microbial treated water is introduced, and the floc in the sludge is propagated as a microbial immobilization carrier (a microbial reservoir). The microorganism in the microbial treated water is preferably an anaerobic microorganism, but even if it is an aerobic microorganism, the phenomenon that anaerobic microorganisms propagate over time has actually occurred. There is no particular problem with treated water containing other microorganisms. The point is to mix the microorganism-treated water and sludge in the mixing tank 35.
[0060]
In the wastewater treatment apparatus of the first embodiment, the mixture obtained by mixing the microbial treated water and the sludge from the first sedimentation tank 23 as the coagulation sedimentation apparatus is introduced only into the upper part 9 of the first recycle tank 1. Then, it settles in the lower part 8 of the first recycling tank 1. On the other hand, the waste water containing hydrogen peroxide and fluorine is introduced into the lower parts 8 and 18 of the first and second recycling tanks 1 and 11, and the upper parts 9 and 19 of the first and second recycling tanks 1 and 11, respectively. Move to. As a result, the mixture falls from the top to the bottom, and the drainage rises from the bottom to the top, and moves in opposite directions. Therefore, in the first and second recycling tanks 1 and 11, the efficiency of the reaction between the wastewater (acid wastewater) and the mixture (weak alkaline because it contains unreacted slaked lime) without a stirrer. It is possible to improve the processing efficiency.
[0061]
(Second embodiment)
Next, FIG. 2 shows a second embodiment of the waste water treatment apparatus of the present invention. The waste water treatment apparatus of the second embodiment differs from the first embodiment only in the following point (1). Accordingly, the same components as those in the first embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted.
[0062]
(1) In the second embodiment, the high reaction part 34 is installed in the first rapid stirring tank 21.
[0063]
A high reaction section 34 is installed in the first rapid stirring tank 21, slaked lime is charged into the high reaction section 34, and polyaluminum chloride is passed from the second precipitation tank 27 via the second precipitation tank pump 28. Sludge containing a large amount of aluminum hydroxide resulting from this is introduced. Thereby, since the pH of the high reaction part 34 becomes pH 12 vicinity and becomes alkaline, aluminum elutes to some extent from the said sludge.
[0064]
As shown in FIG. 2, in the second embodiment, the high reaction part 34 is arranged in the upper part in the first rapid stirring tank 21, and the bottom 34 </ b> A is open. And it arrange | positions so that the said slaked lime and the said sludge may be injected | thrown-in directly from the opening above this high reaction part 34. FIG.
[0065]
In the high reaction part 34 of the first rapid stirring tank 21, aluminum is eluted to some extent from the sludge, so that fine calcium fluoride formed by the reaction between slaked lime and fluorine in the waste water is further aggregated by the aluminum. be able to. The reason for this is that the elution of aluminum from sludge containing a large amount of aluminum hydroxide has been experimentally found to be possible to some extent even in an alkaline environment.
[0066]
(Third embodiment)
Next, FIG. 3 shows a third embodiment of the waste water treatment apparatus of the present invention. The waste water treatment apparatus of the third embodiment differs from the first embodiment only in the following point (1). Accordingly, the same components as those in the first embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted.
[0067]
(1) The sludge precipitated in the second settling tank 27 is returned to the second recycle tank 11 instead of the first rapid stirring tank 21 by the second settling tank pump 28.
[0068]
In the third embodiment, the sludge precipitated in the second settling tank 27 is returned to the second recycle tank 11 by the second settling tank pump 28. Thereby, the sludge containing a large amount of aluminum hydroxide from the second settling tank 27 can be introduced into the second recycle tank 11 as a water tank managed near pH 5. Therefore, in this 2nd recycle tank 11, aluminum will elute from the introduced sludge and aluminum can be recycled.
[0069]
It has been experimentally found that the amount of aluminum eluted from sludge containing a large amount of aluminum hydroxide increases rapidly under the condition of pH 5 or lower.
[0070]
(Experimental example)
Next, as a specific experimental example, an experimental example of a wastewater treatment apparatus using an actual apparatus having the same structure as that of the first embodiment shown in FIG.
[0071]
In this experimental example, the capacity of the first recycling tank 1 and the second recycling tank 11 is 300 tons, and the first rapid stirring tank 21, the first slow stirring tank 22, the second rapid stirring tank 25, and the second slow stirring tank. The experiment was conducted by setting the capacity of the tank 26 to 80 tons, the capacity of the first sedimentation tank 23 to 600 tons, and the capacity of the second sedimentation tank 27 to 900 tons.
[0072]
As a result, inflow water (hydrogen peroxide and fluorine-containing wastewater) as treated water had a fluorine concentration of 100 ppm to 300 ppm, but after treatment, treated water having a fluorine concentration of 5 ppm was stably obtained. I was able to.
[0073]
Moreover, in this experimental example, compared with the sludge generation amount in the conventional waste water treatment apparatus shown in FIG. 4, the sludge generation amount was able to be reduced by about 30% in the basic unit per waste water amount.
[0074]
In the first to third embodiments, the first and second recycling tanks 1 and 11 are provided. However, three or more recycling tanks may be provided.
[0075]
【The invention's effect】
As is clear from the above, the wastewater treatment apparatus of the present invention contains a mixture of microbial treated water obtained from another system and sludge generated from a settling tank, containing hydrogen peroxide and fluorine in a recycling tank. React with the wastewater to be contacted. Therefore, the amount of chemicals used and sludge generation can be reduced by recycling the unreacted chemical in the sludge by bringing it into contact with the water to be treated again in the recycling tank. Moreover, since the hydrogen peroxide contained in the waste water can be treated with the microbially treated water obtained from the separate system, chemical costs for treating the hydrogen peroxide can be saved. Therefore, according to the present invention, in the treatment of fluorine-containing wastewater, hydrogen peroxide can be simultaneously treated, and the amount of chemicals used and the amount of sludge generated can be reduced by recycling unreacted chemicals.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a first embodiment of a waste water treatment apparatus of the present invention.
FIG. 2 is a configuration diagram showing a second embodiment of the waste water treatment apparatus of the present invention.
FIG. 3 is a configuration diagram showing a third embodiment of the waste water treatment apparatus of the present invention.
FIG. 4 is a configuration diagram showing an embodiment of a conventional waste water treatment apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... 1st recycle tank, 2 ... Introducing pipe, 3 ... 1st barrier
4 ... 1st sludge discharge pump, 5 ... Inclined part, 6 ... 1st supernatant liquid discharge pump,
7 ... First sedimentation supernatant, 8 ... Lower first recycling tank,
9 ... Upper part of the first recycling tank, 10 ... First sedimentation part, 11 ... Second recycling tank,
12 ... Introducing pipe, 13 ... Second barrier, 14 ... Second sludge discharge pump,
15 ... Inclined part, 16 ... Second supernatant discharge pump, 17 ... Second sedimentation part supernatant,
18 ... lower part of second recycling tank, 19 ... upper part of second recycling tank,
20 ... 2nd sedimentation part, 21 ... 1st rapid stirring tank, 22 ... 1st slow stirring tank,
23 ... 1st sedimentation tank, 24 ... 1st sedimentation tank pump, 25 ... 2nd rapid stirring tank,
26 ... 2nd slow stirring tank, 27 ... 2nd sedimentation tank, 28 ... 2nd sedimentation tank pump,
29 ... Concentration tank, 30 ... Concentration tank pump, 31 ... Filter press,
34 ... High reaction part, 35 ... Mixing tank.

Claims (4)

A wastewater treatment apparatus for treating wastewater containing hydrogen peroxide and fluorine as treated water,
A recycling tank into which the water to be treated is introduced, and a precipitation tank at the rear stage of the recycling tank,
A mixture obtained by mixing microbial treated water obtained from another system and sludge generated from the settling tank is introduced into the recycling tank, and the recycling tank is a wastewater treatment device that causes the mixture to react with the water to be treated. Yes,
A first recycling tank on the front side and a second recycling tank on the rear side,
A wastewater treatment apparatus, wherein the pH set value in the first recycle tank is set to pH 7, and the pH set value in the second recycle tank is set to pH 5 . The waste water treatment apparatus according to claim 1 ,
A coagulation sedimentation device at the latter stage of the first and second recycling tanks;
Waste water containing hydrogen peroxide and fluorine is introduced as treated water into the lower part of the first and second recycling tanks,
A wastewater treatment apparatus, wherein a mixture obtained by mixing microbial treated water and sludge from the coagulation sedimentation apparatus is introduced into an upper portion of the first recycling tank. The waste water treatment apparatus according to claim 1 ,
A wastewater treatment apparatus, wherein sludge precipitated in the first recycling tank is introduced into the second recycling tank. A mixing step of mixing the sludge from the coagulation sedimentation device and the microbially treated water;
A first treatment step of introducing wastewater containing hydrogen peroxide and fluorine as treated water into a plurality of recycling tanks having different pH setting values and introducing the mixture mixed in the mixing step into the recycling tank;
A wastewater treatment method comprising: a second treatment step of introducing the treated water obtained from the recycling tank into the coagulation sedimentation apparatus and treating the treated water.

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