JP6012402B2 - Apparatus and method for treating wastewater containing heavy metals - Google Patents

Description

  The present invention relates to an apparatus and a method for treating waste water containing heavy metals such as iron, manganese, zinc, lead, cadmium, arsenic, copper, and chromium.

Groundwater has a low concentration of dissolved oxygen and a strong reducibility, and due to rock minerals and geology, ammonia, arsenic, iron, manganese, and other heavy metal ions are contained in high concentrations and pH is also sulfuric acid. It has water quality characteristics that it is easy to become. Particularly in the suburbs of volcanoes and mines, the pH is low, acidic wastewater containing heavy metals and fluorine is generated, and a vicious cycle is likely to occur where the metal concentration is high.
In addition, acidic wastewater contains very little organic matter that can be taken up as living things. Moreover, aluminum is often contained in the acid waste water in many cases.

These water quality features are unique to acidic drainage not found in surface water such as river water, pond / lake water, and dam water.
As a purification system for acidic wastewater that uses acidic wastewater with such water quality characteristics as raw water, neutralization with slaked lime, oxidation with sodium hypochlorite, and metal removal by alkali agglomeration, followed by ion exchange and fluorine Removal by chelate adsorption is the mainstream.

  However, in the above-mentioned conventional technology in which chlorine oxidation with sodium hypochlorite or the like is performed in the former stage and solid-liquid separation is performed in the latter stage, the chlorine-containing byproduct and chloric acid are increased by increasing the amount of chlorine used. There is a problem that a lot of sludge is generated. Also, alkali agglomeration requires an operation on the alkali side, and fluorine treatment by ion exchange or chelate adsorption requires pH to be lowered to 3 to 3.5. In order to perform the fluorine treatment, it was necessary to reduce the pH twice again. Aggregation of lead and cadmium and manganese oxidation agglomeration require operation on the alkali side, and if fluorine is adsorbed to an ion exchange resin without removing it, there is a problem that fluorine cannot be adsorbed due to interference with components such as aluminum. is there. Therefore, it is necessary to perform a metal treatment and a fluorine treatment. The pH needs to be raised and lowered, and it is necessary to neutralize it after the removal, so that the operation management cost of chemicals for adjusting the pH is high.

  In addition, when fluorine ions are contained in the waste water, almost no treatment can be performed by agglomeration treatment of metal ions, and a method of removing fluorine ions using a crystallization method or a precipitation method is also known. For example, a crystallization method using hydroxyapatite as a seed crystal described in Patent Document 1 and a method of adsorbing calcium phosphate described in Patent Document 2 by adding it to a precipitation tank are used. The method described in Patent Document 1 has a drawback that the treated water after crystallization becomes cloudy and requires sand filtration as a post-treatment, and fluorine cannot be treated without sand filtration. In addition, in the method based on the precipitation method of Patent Document 2, it is difficult to say that the adsorbent is used efficiently because calcium phosphate is added to the settling tank as an adsorbent and is agglomerated and removed by the polymer flocculant. It is conceivable that

JP 2004-122113 A JP 2011-200777 A

  The present invention has been made in view of the above-mentioned problems, and its purpose is to treat a wastewater containing heavy metals that can reduce the amount of chemicals for pH adjustment, reduce the amount of generated sludge, and reduce operation management costs. And providing a processing method.

As a result of intensive studies, the present inventors have found that the above problems can be solved by the following processing apparatus and processing method, and have reached the present invention.
That is, the present invention is as follows.
(1) A bio-oxidation apparatus in which a filter medium having a particle size of 4 mm or more and 20 mm or less is filled, and a microorganism is supported on the filter medium, and a filter medium having a particle size of 0.5 mm or more and 4 mm or less is filled. And a biological contact filtration device carried in order, wherein the microorganism is a microorganism containing iron bacteria and manganese oxidation bacteria, and the biological oxidation device includes an air diffuser for supplying air or oxygen. Wastewater treatment equipment containing heavy metals.
(2) The bio-oxidation device includes a pH adjuster supply device that adjusts the pH of the water to be treated flowing into the bio-oxidation device to a range of 3.0 to 5.5, and the bio-contact filtration device includes the bio-contact filtration device. The apparatus for treating wastewater containing heavy metals according to (1) above, comprising a pH adjuster supply device for adjusting the pH of the water to be treated flowing into the filtration device to a range of 5.5 to 7.0.
(3) The wastewater containing the heavy metal contains fluorine, and is provided with a phosphate ion supply device after the biological contact filtration device, and has a crystallizer that crystallizes fluorine by adding phosphate ions. The wastewater treatment apparatus containing heavy metal according to (1) or (2), characterized in that it is characterized in that
(4) The crystallization apparatus includes a device in which calcium carbonate having an average particle diameter of 0.2 mm or more and 0.8 mm or less is filled as a seed crystal, water to be treated is passed from the bottom, and gas is blown into an inflow portion. The wastewater treatment apparatus containing heavy metal according to (3) above,
(5) The waste water containing heavy metal according to (3) or (4), wherein the crystallizer includes a calcium ion supply device that adds calcium ions to the water to be treated flowing into the crystallizer. Processing equipment.
(6) The biooxidation apparatus includes an iron ion supply apparatus that adds divalent iron ions to water to be treated that flows into the biooxidation apparatus, and / or a manganese ion supply apparatus that adds manganese ions. The waste water treatment apparatus containing the heavy metal according to any one of (1) to (5).
(7) The biooxidation apparatus includes a manganese ion supply apparatus that adds manganese ions to water to be treated that flows into the biooxidation apparatus, and an ammoniacal nitrogen supply apparatus that adds ammoniacal nitrogen. ) To (5) A wastewater treatment apparatus containing the heavy metal according to one item.
(8) A method for treating wastewater containing heavy metals, wherein the wastewater is filled with a filter medium having a particle size of 4 mm or more and 20 mm or less, and microorganisms are supported on the filter medium to supply air or oxygen. A bio-oxidation treatment step for treating with a bio-oxidation device, and then a bio-contact filtration treatment in which a filter medium having a particle size of 0.5 mm or more and 4 mm or less is filled and microorganisms are supported on the filter medium. possess a step, the processing method of waste water containing heavy metals, wherein said microorganism is a microorganism containing iron bacteria, manganese-oxidizing bacteria.
(9) The pH of the water to be treated flowing into the biological oxidizer is adjusted to a range of 3.0 to 5.5, and the pH of the water to be treated flowing into the biological contact filtration device is 5.5 to 7.0. The method for treating wastewater containing heavy metal according to (8), wherein the range is adjusted.
(10) The wastewater containing the heavy metal contains fluorine, and has a fluorine crystallization step of removing fluorine by a crystallizer that crystallizes fluorine by adding phosphate ions after the biological contact filtration treatment step. A method for treating wastewater containing heavy metal as described in (8) or (9) above.
(11) The phosphoric acid ion is added so that the phosphoric acid phosphorus concentration is 4 to 9 times (mass ratio) with respect to the fluorine concentration of the water to be treated flowing into the crystallizer. A method for treating waste water containing heavy metals as described in 10).
(12) The crystallizer is filled with calcium carbonate having an average particle diameter of 0.2 mm or more and 0.8 mm or less as seed crystals, water to be treated is passed from the bottom, and crystallization is performed while blowing gas into the inflow portion. The method for treating wastewater containing heavy metal according to (10) or (11), wherein:
(13) It has a calcium ion supply step of adding calcium ions to the water to be treated flowing into the crystallizer, and the calcium ions are 10 to 20 times (Ca / F mass) with respect to the fluorine concentration of the water to be treated. The method for treating wastewater containing heavy metal according to any one of (10) to (12), wherein the wastewater is added so as to be a ratio.
(14) Wastewater containing heavy metal according to any one of (10) to (13), wherein the pH of the water to be treated flowing into the crystallizer is 6.0 to 7.0. Processing method.
(15) The ratio of the concentration of divalent iron ions in the water to be treated flowing into the biological oxidizer to the concentration of heavy metals other than divalent iron ions and manganese ions (mass of heavy metals other than Fe ²⁺ / Fe ²⁺ and Mn) If the ratio is less than 5, divalent iron ions are added to the water to be treated so that the ratio is 5 to 10. One of the above (8) to (14), The processing method of the waste_water | drain containing the heavy metal of description.
(16) When the heavy metal other than the divalent iron ion and manganese ion contains arsenic and lead, and the ratio of the concentration of the divalent iron ion to the arsenic and lead concentration (Fe ²⁺ / As + Pb mass ratio) is less than 5 The method for treating wastewater containing heavy metals according to (15), wherein divalent iron ions are added to the water to be treated so that the ratio is 5 to 10.
(17) The ratio of the concentration of manganese ions of water to be treated flowing into the biological oxidation apparatus to the concentration of heavy metals other than divalent iron ions and manganese ions (the mass ratio of heavy metals other than Mn / Fe ²⁺ and Mn) is 0. In the case of less than 5, manganese ions are added to the water to be treated so that the ratio is 0.5 to 1, according to any one of (8) to (16), A method for treating wastewater containing heavy metals.
(18) The concentration of divalent iron ions in the water to be treated flowing into the biological oxidizer is 0.5 mg / L or less, and the ratio of the concentration of manganese ions to the concentration of heavy metals other than divalent iron ions and manganese ions ( When the mass ratio of heavy metals other than Mn / Fe ²⁺ and Mn is less than 0.5, manganese ions are added to the water to be treated so that the ratio is 0.5 to 1, and ammonia nitrogen is added. method of processing waste water containing heavy metals according to (17), characterized in that the addition of 0.5 times the Mn concentration to be 1-fold (NH ₄ -N / Mn weight ratio).
(19) When the filtration rate of the biological oxidizer is 20 mg / L or more when the sum of the iron concentration and the aluminum concentration in the water to be treated flowing into the biological oxidizer is 0.8 mg / L · min or more and 1.5 mg / L · If the total of the iron concentration and aluminum concentration in the water to be treated flowing into the biological contact filtration device is 15 mg / L or more, the filtration rate of the biological contact filtration device shall be 1.2 mg / L · min or less. A method for treating wastewater containing heavy metal according to any one of the above (8) to (18).

  According to the apparatus and method for treating wastewater containing heavy metals according to the present invention, heavy metals such as iron, manganese, cadmium, lead, and zinc contained in wastewater containing heavy metals, and aluminum and fluorine are also suitably removed. can do. In the removal, the operation management cost can be reduced without using any flocculant or oxidizing agent, and it is less expensive than the conventional method and produces less sludge and has excellent cost performance.

It is the schematic of an example of the processing apparatus of the waste_water | drain containing the heavy metal of this invention.

  The biological oxidation apparatus and biological contact filtration apparatus in the treatment apparatus for wastewater containing heavy metals according to the present invention are a biooxidation apparatus and a biological contact filtration apparatus in which a filter medium is filled and microorganisms are supported on the filter medium, The particle size of the filter medium is 4 mm or more and 20 mm or less in the former, and 0.5 mm or more and 4 mm or less in the latter, and the bio-oxidation apparatus includes an air diffuser that supplies air or oxygen.

  Wastewater containing heavy metal that is treated using the wastewater treatment apparatus containing heavy metal of the present invention includes at least one kind of heavy metals such as iron, manganese, cadmium, lead, tin, copper, zinc, and arsenic. In addition, it may contain light metals such as aluminum and calcium, and fluorine. Examples of such wastewater containing heavy metals include mine wastewater, tunnel spring water, soil polluted water, underground polluted water, hot spring drainage, geothermal power drainage, and the like. ~ About several hundred mg / L, cadmium, lead, tin, copper, zinc, arsenic, etc. contain several mg / L, aluminum, calcium contain several tens mg / L, fluorine contain several mg / L In most cases, it is neutral to acidic. The higher the concentration of iron and aluminum, the greater the acidity.

  Pretreatment of waste water containing heavy metals is performed by the bio-oxidation device, and then finishing treatment is performed by a biological contact filtration device. That is, in the first stage, most of heavy metals such as iron, lead, arsenic, etc. are oxidized by biological treatment, aluminum is flocked by neutralization, and about half of it is removed. Remove chromium, cadmium, etc. Moreover, metals such as iron and aluminum left behind in the bio-oxidation apparatus are removed.

The biooxidation apparatus oxidizes metals by microorganisms. Therefore, an air diffuser for supplying air or oxygen is provided. The bio-oxidation apparatus blows air or oxygen from the bottom by a diffuser, and feeds water to be treated from the top and filters it. The amount of air or oxygen is preferably determined by the concentration of iron and manganese in the water to be treated. Moreover, when ammoniacal nitrogen is contained, it is preferable to consider the density | concentration.
For example, when air is blown, the amount of air is preferably about 30 to 40 times the amount of iron in the water to be treated. When oxygen is blown in, about 7 to 9 times is preferable.

  It is important that the particle size of the filter medium of the biooxidation apparatus is 4 mm or more and 20 mm or less. A filter medium having a larger particle size than that used in the biofiltration apparatus is preferable, and insolubilized colloidal iron can be adsorbed on the biofilm by microorganisms adhering to the filter medium and removed. If the particle size is smaller than 4 mm, the filtration rate cannot be increased, and clogging may occur. If the particle size exceeds 20 mm, the processing capacity is lowered.

  It is important that the particle size of the filter medium of the biological contact filtration device is 0.5 mm or more and 4 mm or less. Since most of the iron and aluminum are removed by the bio-oxidation apparatus, the filter medium of the bio-contact filtration apparatus can have a smaller particle size than that of the bio-oxidation apparatus. When the particle size is less than 0.5 mm, the filtration rate is slow, and when it exceeds 4 mm, the treatment capacity is lowered. Moreover, since it diffuses with a bio-oxidation apparatus, oxygen is dissolved in the to-be-processed water which flows into a biological contact filtration apparatus, and contact filtration may be sufficient.

In the treatment apparatus according to the present invention, it is preferable that the particle size of the filter medium is selected based on the metal ion concentration in the water to be treated for both the biooxidation apparatus and the biological contact filtration apparatus.
The particle size of the filter medium of the bio-oxidation apparatus is 4 mm or more and 20 mm or less, and the biological contact filtration apparatus in the latter stage is filled with a filter medium having a particle diameter of 0.5 mm or more and 4 mm or less.
The filter medium diameter of the bio-oxidation device is 5 mm or more and less than 10 mm when the total concentration of iron and aluminum in the water to be treated flowing into the bio-oxidation device is 20 mg / L or more and less than 60 mg / L. When the total of the iron concentration and the aluminum concentration is 60 mg / L or more, the particle size of the filter medium is preferably 10 mm or more and 20 mm or less.
In addition, the particle size of the filter medium filled in the biological contact filtration device is 0.5 mm or more when the sum of the iron concentration and the aluminum concentration of the water to be treated flowing into the biological contact filtration device is less than 40 mg / L. When the sum of the iron concentration and the aluminum concentration is less than 2 mm and the sum of the iron concentration and the aluminum concentration is 40 mg / L or more and less than 60 mg / L, the particle size of the filter medium is 1 mm or more and 3 mm or less, and when the sum of the iron concentration and aluminum concentration is 60 mg / L or more It is preferable to install another series of the same contact filtration device.
The particle size of the filter medium is obtained by sorting with a test sieve defined in JIS Z 8801, and excluding those having a particle size outside the range by the sieve. That is, a filter medium having a particle size of 4 mm or more and 20 mm or less means a filter medium excluding those having a particle diameter of less than 4 mm and more than 20 mm by sieving.

  As the filter medium, a porous filter medium capable of supporting microorganisms is preferable, the width of variation in particle size is small, lighter than sand, and porous, such as zeolite, anthracite, garnet. Various things such as pumice and activated carbon can be used. When water is passed through the filtration device from above, it is preferable to sink in water.

As the microorganisms to be supported on the filter medium, microorganisms that oxidize heavy metals such as iron and manganese are preferable.
As microorganisms that oxidize iron and manganese, the microorganisms contained in the raw water basically exhibit removal performance by adhering to and growing on the porous filter medium packed in the biological filtration device. It may take 3 months, so in order to shorten the period, it is not particularly limited as long as it contains iron bacteria, manganese oxidizing bacteria, etc. that are already used for removing iron and manganese. There are no known ones. Examples include Gallionella, Thiobacillus, Leptothrix, Caldimonas, Hyphomicrobium, Nitrosomonas, Nitosospira, Nitrobacter, Nitrospira, Geobacter, Geothrix and the like.

As the microorganism used in the biological oxidizer, since the concentration of heavy metals such as iron and manganese in the water to be treated is high, a microorganism having a high treatment capacity when the concentration is high is preferable.
The microorganism used in the biological contact filtration device is preferably a microorganism having a high oxidation treatment capacity when the concentration is low because the concentration of heavy metals such as iron and manganese in the water to be treated is low.

The treatment apparatus according to the present invention preferably includes a pH adjuster supply device that controls the pH of the liquid to be treated that flows into the biooxidation apparatus and the biological contact filtration apparatus.
The pH adjuster adjusts the pH of the water to be treated flowing into the biological oxidizer in the range of 3.0 to 5.5, and the pH of the water to be treated flowing into the biological contact filtration device is 5.5 to 7.0. It is preferable to adjust to.
By setting the pH of the liquid to be treated flowing into the biological oxidation apparatus to be in the range of 3.0 to 5.5, iron oxidation and aluminum hydroxylation are possible. By setting the pH of the biological contact filtration device to 5.5 to 7.0, manganese can be oxidized and other heavy metals remaining by the oxide can be adsorbed and removed.
In the biooxidation apparatus, manganese is partially oxidized depending on the pH of the liquid to be treated, and manganese, cadmium, zinc and the like are also removed.
When the content of heavy metals other than iron and manganese in the wastewater containing heavy metals is small, especially when the pH of the liquid to be treated flowing into the biooxidation apparatus is controlled to 3 to 4, only iron can be deposited on the filter medium. Further, manganese and remaining iron can be precipitated at a pH of 5.5 to 7.0 of the water to be treated flowing into the biological contact filtration device. Since iron and manganese serve as a hazardous metal recovery agent, a filter medium on which only iron and manganese are adsorbed can be backwashed to recover iron and manganese, and can be effectively used as a hazardous metal recovery agent.
Further, when the waste water contains aluminum, some of aluminum is precipitated at pH 3.0 to 4.5, and some is dissolved. Since it precipitates as aluminum hydroxide under the condition of pH 4.5 to 5.5, a part of aluminum can be removed by the biooxidation apparatus. Fine flocs are filtered by a biological contact filtration device at the subsequent stage.

  In particular, the pH of the liquid to be treated flowing into the biological contact filtration device is important. By setting the pH within the range of 5.5 to 7.0, it is possible to treat metals such as cadmium, zinc, and manganese.

As a pH adjuster, an alkali or an acid generally used for adjusting the pH can be used.
For example, sodium hydroxide, potassium hydroxide, sodium carbonate, magnesium hydroxide or the like can be used as the alkali.
As the acid, hydrochloric acid, sulfuric acid and the like can be used.

According to said structure, about half of metal ions, such as arsenic, iron, aluminum, and lead, are removed by biological treatment in the front | former stage, and the load to the biological contact filtration apparatus of finishing treatment can be reduced.
With regard to iron, oxidation with a normal oxidizing agent lowers pH because divalent iron is oxidized as shown in formula (1) to become trivalent iron and hydrogen ions are generated, but wastewater containing heavy metals In many cases, is acidic with sulfuric acid, and as shown in the formula (2), by changing the form to basic iron sulfate, hydrogen ions are consumed and oxidation is possible without lowering the pH.
In addition, manganese is oxidized by biological contact filtration to remove zinc, chromium and cadmium, and metals such as iron and aluminum left behind in the biological oxidizer are also removed.
As for the oxidation of manganese, manganese oxidation with a normal oxidant results in tetravalent manganese as shown in equation (3), but biological oxidation results in trivalent manganese as shown in equation (4), generating hydrogen ions. Therefore, the amount of the pH adjuster used in the next step can be reduced, and a processing apparatus capable of reducing the operation management cost can be realized.
If iron and manganese ions can be treated, the remaining metal ions such as lead, cadmium, zinc, and arsenic are adsorbed on iron hydroxide and manganese oxide and removed together.
Fe ²⁺ + O ₂ + 3 / 2H ₂ O → Fe (OH) ₃ + 2H ⁺ (1)
Fe (OH) ₃ + 2H ⁺ + SO ₄ ²⁻ → Fe (OH) SO ₄ + 2H ₂ O (2)
Mn ²⁺ + NaClO + 2H ₂ O → MnO ₂ .H ₂ O ↓ + NaCl + 2H ⁺
... (3)
Mn ²⁺ + 1 / 2O ₂ + 1 / 2H ₂ O → 1 / 2Mn ₂ O ₃ + H ⁺ (4)

  The biological oxidizer may include an iron ion supply device that adds divalent iron ions to the water to be treated that flows into the biological oxidizer, and / or a manganese ion supply device that adds manganese ions. In addition, the biological oxidation apparatus can include a manganese ion supply apparatus that adds manganese ions to water to be treated that flows into the biological oxidation apparatus, and an ammoniacal nitrogen supply apparatus that adds ammoniacal nitrogen.

Divalent iron ions are highly effective in removing heavy metals, especially arsenic and lead, and the concentration of divalent iron ions in the concentration of the divalent iron ions in the water to be treated flowing into the bio-oxidation apparatus. When the ratio to the mass (mass ratio of heavy metals other than Fe ²⁺ / Fe ²⁺ and Mn) is less than 5, divalent iron ions may be added to the water to be treated so that the ratio is 5 to 10. preferable.
In particular, when the ratio of the concentration of divalent iron ions to the arsenic and lead concentrations (mass ratio of Fe ²⁺ / As + Pb) is less than 5, divalent iron ions are added to the water to be treated so that the ratio is 5-10. It is preferable to add.
By setting the ratio to 5 to 10, the arsenic concentration in the treated water treated by the treatment apparatus of the present invention can be treated to a reference value or less such as 0.005 ppm.

The ratio of the concentration of manganese ions in the water to be treated flowing into the bio-oxidizer to the concentration of heavy metals other than divalent iron ions and manganese ions (heavy metal mass ratio other than Mn / Fe ²⁺ and Mn) is less than 0.5. In this case, it is preferable to add manganese ions to the water to be treated so that the ratio is 0.5 to 1.
Manganese-oxidizing bacteria need to coexist with iron bacteria that use iron as a nutrient salt, or coexist with nitrifying bacteria that oxidize ammonia nitrogen, and growth with manganese-oxidizing bacteria alone is unthinkable. Therefore, when the content of divalent iron ions is low and the concentration of other heavy metals is high, it is necessary to supply divalent iron ions and manganese ions or manganese ions and ammoniacal nitrogen to remove heavy metals. It becomes.
When the water to be treated contains cadmium and zinc, the adsorption by manganese oxide is excellent, and the manganese in the water to be treated absorbs and removes heavy metals such as cadmium, lead, zinc and chromium. If the ratio of the concentration of ions to the concentration of heavy metals other than divalent iron ions and manganese ions (mass ratio of heavy metals other than Mn / Fe ²⁺ and Mn) is less than 0.5, 0.5 to 1 times the amount Of manganese is generally required. Mines and tunnel springs may contain about 5 mg / L of zinc, so that the required manganese concentration is 2.5-5 mg / L. In general ground water, manganese is insufficient at a manganese concentration of 0.5 mg / L, so it is preferable to add manganese.

Further, the concentration of divalent iron ions in the water to be treated flowing into the biooxidation apparatus is 0.5 mg / L or less, and the ratio of the concentration of manganese ions to the concentration of heavy metals other than divalent iron ions and manganese ions (Mn / Heavy metal mass ratio other than Fe2 ⁺ and Mn) is less than 0.5, manganese ions are added to the water to be treated so that the ratio is 0.5 to 1, and ammonia nitrogen is added to Mn. It is preferable to add such that the concentration is 0.5 times to 1 time (NH ₄ —N / Mn mass ratio).
If the proportion of manganese added is greater than 1 time, excessive addition leads to an increase in the amount of generated sludge. If it is less than 0.5 times, it will not be possible to treat it below the environmental standard value for heavy metals. The proportion is preferably 0.7 to 1 times.
Further, increasing the amount of ammonia nitrogen added is not preferable because the amount of oxygen consumed increases.

As the compound for adding divalent iron ions, ferrous sulfate is preferable, and as the compound for adding ammoniacal nitrogen, ammonium chloride, urea, aqueous ammonia and the like are preferable.
As a compound for adding Mn ions, manganese sulfate is suitable.

  The concentrations of heavy metals and aluminum in the water to be treated can be measured by ICP or ICP-MS.

  According to the above configuration, ammonia, arsenic, iron, manganese, and other metal ions contained in wastewater containing heavy metals such as acidic wastewater can be suitably removed, and the filtration flow rate of water to be treated can be increased. It is possible to increase the size, and it is possible to increase the cleaning interval of the filter medium. If aluminum ions are present, adjust the pH and filter media particle size in the bio-oxidation device, and filter as aluminum hydroxide in the bio-oxidation device to reduce the burden on the later-stage biological contact filtration device. The remaining aluminum floc is removed with a contact filtration device.

  Further, in the case where fluorine ions are contained in the water to be treated, it is hardly possible to treat with metal ions, and it is removed using a crystallization method.

  In the treatment apparatus of the present invention, when water to be treated contains fluorine ions, the biological oxidation apparatus for pretreatment, the biological contact filtration apparatus for finishing metal ions, and further for removing fluorine. A combination of crystallizers can remove heavy metals such as iron, manganese, cadmium, lead, zinc, arsenic, aluminum, and fluorine ions.

  The crystallizer is equipped with a phosphate ion supply device, in which calcium carbonate having an average particle diameter of 0.2 mm or more and 0.8 mm or less is filled as a seed crystal, water to be treated is passed from the bottom, and gas is introduced into the inflow portion. It is preferable to provide a device for blowing in.

Fluorine ions are precipitated in the seed crystal as a crystalline substance called calcium fluorophosphate when the pH is set to 6 to 7 due to the presence of phosphate ions and calcium ions. Therefore, it is preferable that the crystallizer has a phosphate ion supply device for adding phosphate ions to the water to be treated flowing into the crystallizer. Further, the water to be treated usually contains calcium ions, but when it does not contain calcium ions or when the amount of calcium ions contained is small, it is preferable to provide a calcium ion supply device and add calcium ions. .
As a compound for supplying phosphate ions, any compound capable of supplying phosphate ions may be used, and examples thereof include phosphoric acid, ammonium phosphate, and potassium phosphate. In consideration of cost, phosphoric acid is preferable. .
Examples of the compound for adding calcium ions include calcium hydroxide, calcium chloride and the like, and it is also preferable to add calcium hydroxide also serving as a pH adjuster.

Fluorine treatment with calcium fluorophosphate is crystallized and removed based on chemical formula (5).
5Ca ²⁺ + 3PO ₄ ^3- + F ⁻ → Ca ₅ (PO ₄ ) ₃ F (5)
The addition amount of calcium ions is 10 to 20 times (mass ratio) of the fluorine concentration, and the addition amount of phosphate ions needs to be added such that the phosphoric acid phosphorus concentration is 4 to 9 times (mass ratio) of the fluorine concentration. It is.

In addition, when calcium fluorophosphate is precipitated on the seed crystal of the crystallizer, the seed crystals easily stick to each other, and if the seed crystals stick to each other, they become a block, and the inflow site is easily clogged. It is possible to prevent a block by providing a device for blowing gas at the inflow location and blowing the gas.
Calcium carbonate used in the crystallizer of the present invention has stronger crystal particles than hydroxyapatite, and even if gas is blown from the bottom, the crystal particles are not broken, and the treated water does not become cloudy. ing.
As the gas, air is preferable, and it is preferable to blow at 0.05 to 0.1 times the amount of raw water.

In addition, by selecting the seed crystal particle size, it became possible to treat the environmental standard fluorine ion concentration of 0.8 mg / L or less. As a seed crystal, it is preferable to select a particle diameter in the range of an average particle diameter of 0.2 mm to 0.8 mm.
More preferably, it is the range of 0.3-0.4 mm. When the particle size is less than 0.2 mm, the substrate is blown up, so that separation becomes difficult. When the particle size exceeds 0.8 mm, it is difficult to set the environmental standard to 0.8 mg / L or less, and crystallization is performed. The flow of the product deteriorates, and the crystallized products are bonded to each other so as to block up.
The average particle diameter indicates a 50% diameter of the weight cumulative particle size distribution.

The treatment apparatus for water to be treated containing heavy metal according to the present invention may include two or more systems of the biological apparatus.
According to said structure, when abnormality arises in the process by a biological apparatus, a biological apparatus can be switched and the stable water quality can be ensured continuously.

  The apparatus for treating wastewater containing heavy metals according to the present invention is designed to be sized according to the metal ion concentration in the water to be treated, and is determined in particular from the iron and aluminum ion concentrations.

The filtration rate of the biological oxidizer is 0.8 mg / L · min or more and 1.5 mg / L · min or less when the sum of the iron concentration and aluminum concentration in the water to be treated flowing into the biological oxidizer is 20 mg / L or more, When the total concentration of iron and aluminum in the water to be treated flowing into the biological contact filtration device is 15 mg / L or more, the filtration rate of the biological contact filtration device is preferably 1.2 mg / L · min or less. In the case of a device having a higher filtration rate, the deterioration of the treated water and the frequency of cleaning the biological treatment device increase, and the treatment efficiency of the treated water decreases. If it is small, the apparatus becomes large and the equipment for backwashing becomes large.
The said filtration rate is a value calculated | required by the following formula | equation.
(Inflow iron concentration-iron concentration of treated water) / residence time The residence time is obtained by dividing the volume filled with the filter medium by the flow rate.

The method for treating wastewater containing heavy metals according to the present invention uses the bio-oxidation device and the biological contact filtration device described above to pass wastewater containing heavy metals as raw water, iron, manganese, lead, cadmium, arsenic, zinc Remove heavy metals such as copper and chromium. When the raw water contains fluorine ions, a crystallization device is provided after the biological contact filtration device, and the fluorine ions contained in the treated water can be crystallized as calcium fluorophosphate by adding phosphoric acid. .
According to said structure, heavy metals, such as iron, manganese, lead, arsenic, zinc, cadmium, copper, and chromium, and a fluorine ion can be removed efficiently, and it can be made below an environmental standard value. In addition, operation management costs can be reduced without using any flocculant or oxidizing agent.
Specifically, for cadmium, lead, hexavalent chromium and arsenic, environmental standard values of cadmium 0.01 mg / L or less, lead 0.01 mg / L or less, hexavalent chromium 0.05 mg / L or less, arsenic 0 0.01 mg / L or less. Zinc can be 2 mg / L or less, fluorine is 0.8 mg / L or less, copper is 2 mg / L or less, manganese is 2 mg / L or less, and iron is 2 mg / L or less.

Next, a treatment apparatus and a treatment method for wastewater containing heavy metal according to the present invention will be described with reference to the drawings.
FIG. 1 is a schematic view of an example of a treatment apparatus for wastewater containing heavy metals according to the present invention. The treatment apparatus includes a biological oxidation apparatus 3 and a biological contact filtration apparatus 12, and further includes a fluorine crystallizer 20.
The biooxidation apparatus 3 is filled with a filter medium having a particle size of 4 mm or more and 20 mm or less, and microorganisms are supported on the filter medium. The biological contact filtration device 12 is filled with a filter medium having a particle size of 0.5 mm or more and 4 mm or less, and microorganisms are supported on the filter medium. The biooxidation device 3 includes an air diffuser 7 that supplies air or oxygen.
The flow will be described sequentially. The waste water that has flowed into the raw water tank 1 is transferred to the bio-oxidation device 3 by the raw water pump 2 and diffused from the bottom of the bio-oxidation device 3 by the blower 8 to supply air for oxidizing iron ions and manganese ions. However, iron removal and aluminum removal are mainly performed, and some manganese removal is also performed. The pH is measured before flowing into the bio-oxidation apparatus 3, the pH is adjusted to 3.0 to 5.5, more preferably 4 to 5, and iron removal and aluminum removal are performed. Iron ions are removed by the filtration effect due to oxidation by microorganisms, and aluminum ions are hydroxylated by addition of hydroxide ions. In order to oxidize iron ions, air or oxygen needs to be supplied, and the reaction apparatus adopts a gravity system with a free upper part.

The filter medium of the biological oxidation apparatus has a particle size of 4 mm or more and 20 mm or less, and when the total concentration of iron ions and aluminum ions is 20 mg / L or more and 40 mg / L or less, it is preferably 5 mm or more and less than 10 mm. When the particle size of the filter medium is too fine, the gap between the filter mediums is quickly blocked by iron oxide or aluminum hydroxide, and it is necessary to immediately backwash. On the other hand, if it is too rough, the oxidation rate cannot be obtained, so that the treatment is hardly possible.
The treatment rate of the bio-oxidation device varies depending on the iron ion and aluminum ion concentrations in the raw water. If the total iron ion concentration and aluminum ion concentration is 20 mg / L or more, 0.8 mg / L · min to 1.5 mg. / L · min or less. Although aluminum ions are not related to oxidation by living organisms, when the aluminum ion concentration is high, the filter medium is clogged quickly, and in order to maintain the washing interval, a certain reaction time and filtration rate are provided. If the reaction rate is too fast, the cleaning interval becomes shorter. Conversely, if the reaction rate is too slow, there is a disadvantage that the processing equipment becomes large.
The filter medium is washed when the water level of the bio-oxidation device rises due to the blockage of the filter medium, for example, when the differential pressure reaches 1 m or by a predetermined timer. In the washing method, water is drained until the water level of the bio-oxidation device 3 reaches a predetermined position, and then air is diffused from the bottom of the bio-oxidation device 3 by the washing compressor 10 to separate sludge between the filter media, Next, the treated water in the treated water tank 16 is sent from the bottom of the biological oxidizer 3 by the backwash pump 25, the sludge is discharged from the top, and sent to the sludge concentration tank 30. Before the inflow of the sludge concentration tank, the anionic polymer in the polymer tank 26 is supplied by the polymer supply pump 29 to concentrate the sludge. The concentrated sludge is sent to the sun drying bed 31 by the sludge transfer pump 32 and filtered by the filled sand, and the water evaporates by the sun to form a cake with a low water content. If there is no place, the sun drying may be a dehydrator, and a method that can reduce sludge efficiently is selected. Sludge filtrate is returned to the raw water tank.

  Then, it pressurizes with the pressurization pump 11, and supplies it to the biological contact filtration apparatus 12. FIG. Here, since iron ions are almost oxidized and the dissolved oxygen concentration is high, a pressure-type filtration facility in which treated water flows in from the top and the treated water flows out from the bottom. It mainly removes fine iron and aluminum floc that could not be removed by oxidation and oxidation removal of manganese. Before flowing into the biological contact filtration device 12, the pH is adjusted again to 5.5 or more and 7.0 or less.

The filter medium is filled with a filter medium having a particle diameter of 0.5 mm or more and 4 mm or less so that manganese oxidation can be performed more efficiently, fine flocs can be filtered, and a cleaning interval can be maintained by blocking the filter medium. More preferably, a filter medium having a particle size of 0.5 mm or more and less than 3 mm is desirable.
The filtration rate of the biological contact filtration device is 1.2 mg / L · min or less when the total concentration of iron and aluminum in the water to be treated flowing into the biological contact filtration device is 15 mg / L or more. Manganese oxidation does not increase the amount of sludge so much and is affected by the concentration of iron ions and aluminum ions that could not be removed.

The biological contact filtration device 12 performs cleaning with a timer. In the cleaning, the water level in the apparatus is lowered to a predetermined position, and then air is sent from the cleaning compressor 10 to the cleaning air pipe 15 at the bottom of the apparatus, the sludge between the filter media is peeled off, the cleaning waste water is discharged from the top, and the sludge concentration tank 30 Save on. In the sludge concentration tank, the anionic polymer is supplied to concentrate the sludge in the same manner as the cleaning of the biooxidation apparatus, and then the water is sent to the sun drying bed 31 and dried. Since the water filtered in the sun-dried bed contains fluorine, it is returned to the raw water tank.
The treated water of the biological contact filtration device 12 is stored in the treated water tank 16 and is fed to the fluorine crystallizer 20 which is the next step by the crystallization pump 19. The fluorine crystallizer 20 has a mechanism in which raw water is supplied from the lower part and treated water flows out from the upper part, and a crystallized product is filled in the middle. As the crystallized product, it is desirable to use inexpensive and harmless calcium carbonate crystals. Calcium carbonate crystals are difficult to dissolve and are strong and easy to use. In addition, there are examples such as hydroxyapatite described in the reference patent, but since the crystal is weak against friction and the treated water becomes cloudy, it is not recommended for water treatment. The particle size is 0.2 mm or more and 0.8 mm or less which is highly reactive and difficult to overflow from the upper part. Preferably 0.3 mm to 0.4 mm is desired.

Raw water containing fluorine ions and calcium ions is flowed into the crystallizer from the lower part, and phosphoric acid is added to the raw water from the phosphoric acid tank 21 by the phosphoric acid supply pump 22.
5Ca ²⁺ + 3PO ₄ ³⁻ + F ⁻ → Ca ₅ (PO ₄ ) ₃ F
Precipitate around calcium carbonate as calcium fluorophosphate.
Since the removal ability decreases when the crystal substance grows large, it is preferable to pull out when the calcium carbonate grows and the particle diameter exceeds 0.8 mm.
In the extraction, the raw water supply is stopped, and the crystallized substance extraction valve 23 is opened to recover the crystallized substance recovery pack 24.

Examples and comparative examples are shown below.
Example 1
Microorganism obtained from iron bacterial sludge of a water purification plant filled with 1.6 m of natural zeolite having a particle diameter of 5 to 10 mm as a filter medium in a reaction tank having an inner diameter of 0.2 m and a height of 2.8 m. Is loaded with 1.6 mm of 0.5 to 2.0 mm of natural zeolite as a filter medium in a bio-oxidation apparatus having an inner diameter of 0.2 m and a height of 2.8 m. Wastewater containing the following heavy metals was treated using a treatment apparatus as shown in FIG. 1 having a biological contact filtration device on which microorganisms obtained from iron bacterial sludge of a water purification plant were carried. The bio-oxidation apparatus diffused air at 3 L / min from the bottom and supplied air.
Raw water is pH 3.4,
Iron 28mg / L
Aluminum 8.8mg / L
Manganese 2.5mg / L
Zinc 1.4mg / L
Lead 0.1mg / L
Copper 0.5mg / L
Cadmium 0.1mg / L
Met. The pH of the raw water was adjusted to pH 4.5 by adding sodium hydroxide with a pH adjuster supply device, and filtered with a biooxidation device at a flow rate of 107 L / hr (LV 4 m / hr).

The treated water treated by the bio-oxidizer has a pH of 5.0,
Iron 4.4mg / L
Aluminum 2.2mg / L
Manganese 1.4mg / L
Zinc 0.7mg / L
Lead 0.01mg / L
Copper 0.2mg / L
Cadmium 0.01mg / L
Met.
Removal rate is (28 + 8.8-4.4-2.2) (mg / L) / 28 (min)
= 1.08 (mg / L · min)
And
The residence time is determined by the volume filled with the filter medium.
0.2 × 0.2 ÷ 4 × 3.14 × 1.6 = 0.050 (m ³ )
Because
0.05 (m ³ ) ÷ 107 (L / hr) = 28 (min)
Met.

Next, the pH of the treated water treated by the biological oxidation treatment was adjusted to pH 6.0 by adding sodium hydroxide with a pH adjuster supply device, and filtered with a biological contact filtration device.
The treated water treated by the biological contact filtration device has a pH of 6.0,
Iron 0.1mg / L
Aluminum 0.2mg / L
Manganese 0.1mg / L
Zinc 0.1mg / L
Lead 0.01mg / L
Copper 0.1mg / L
Cadmium 0.01mg / L
Met.
The total amount of iron and aluminum in the treated water flowing into the biological contact filtration device is 6.6 mg / L, and the removal rate is (4.4 + 2.2−0.1−0.2) (mg / L) / 25 (min)
= 0.25 (mg / L · min)
Met.
The residence time is determined by the volume filled with the filter medium.
0.2 × 0.2 ÷ 4 × 3.14 × 1.6 = 0.050 (m ³ )
Because
0.05 (m ³ ) ÷ 120 (L / hr) = 25 (min)
Met.

Example 2
In Example 1, the following raw water treatment was performed using the same treatment apparatus having the same biooxidation apparatus and biological contact filtration apparatus as Example 1 except that the filter medium of the biooxidation apparatus was changed to natural zeolite having a particle diameter of 10 mm to 20 mm. Went.
PH 3.2 of raw water,
Iron 40mg / L
Aluminum 30mg / L
Manganese 20mg / L
Zinc 6mg / L
Lead 1mg / L
Copper 8mg / L
Cadmium 0.04mg / L
The raw water was adjusted to pH 5 by adding sodium hydroxide with a pH adjuster supply device, and filtered with a bio-oxidation device at a flow rate of 88 L / hr.

The treated water of the bio-oxidizer is pH 5.5
Iron 10mg / L
Aluminum 10mg / L
Manganese 15mg / L
Zinc 3mg / L
Lead 0.01mg / L
Copper 4mg / L
Cadmium 0.02mg / L
Met.
Removal rate is (40 + 30-10-10) (mg / L) / 34 (min)
= 1.47 (mg / L · min)
And
The residence time is determined by the volume filled with the filter medium.
0.2 × 0.2 ÷ 4 × 3.14 × 1.6 = 0.050 (m ³ )
Because
0.05 (m ³ ) ÷ 88 (L / hr) = 34 (min)
Met.

Next, the pH of the treated water treated by the biological oxidation treatment was adjusted to pH 6.0 by adding sodium hydroxide with a pH adjuster supply device, and filtered with a biological contact filtration device.
The treated water of the biological contact filtration device is pH 6,
Iron 0.3mg / L
Aluminum 0.3mg / L
Manganese 1mg / L
Zinc 0.1mg / L
Lead 0.01mg / L
Copper 0.1mg / L
Cadmium 0.01mg / L
Met.
Removal rate is (10 + 10-0.3-0.3) (mg / L) / 28 (min)
= 0.69 (mg / L · min)
And
The residence time is determined by the volume filled with the filter medium.
0.2 × 0.2 ÷ 4 × 3.14 × 1.6 = 0.050 (m ³ )
Because
0.05 (m ³ ) ÷ 107 (L / hr) = 28 (min)
Met.

Example 3
The reaction tank with an inner diameter of 1.6 m and a height of 2 m is filled with 1.6 m of natural zeolite having a particle size of 10 to 20 mm as a filter medium, and the filter medium carries microorganisms obtained from iron bacterial sludge from a water purification plant using groundwater as raw water. The biooxidation apparatus and a reaction tank having an inner diameter of 0.2 m and a height of 2.8 m are filled with 1.6 mm of natural zeolite of 0.5 to 2.0 mm as a filter medium, and the filter medium uses groundwater as raw water. Wastewater containing the following heavy metals was treated using a treatment apparatus as shown in FIG. 1 having a biological contact filtration device on which microorganisms obtained from iron-bacteria sludge in the field were supported. The bio-oxidation apparatus diffused air at 3 L / min from the bottom and supplied air.
Raw water
Iron 60mg / L
Aluminum 25mg / L
Manganese 5mg / L
Zinc 2mg / L
Lead 0.04mg / L
Copper 2.0mg / L
Cadmium 0.02mg / L
Met. The pH of the raw water was adjusted to pH 5.6 by adding sodium hydroxide with a pH adjuster supply device, and filtered with a biological oxidizer at a flow rate of 9 m ³ / hr. The reaction time was 38.5 minutes.

The treated water treated by the bio-oxidizer is
Iron 35mg / L
Aluminum 10mg / L
Manganese 4mg / L
Zinc 1.5mg / L
Lead 0.02mg / L
Copper 1.1mg / L
Cadmium 0.02mg / L
Was processed.
The removal rate is (60−35 + 25−10) /38.5×60=1.04 (mg / L · h)
Met.

Next, the pH of the treated water treated by the biological oxidation treatment was adjusted to pH 7.0 by adding sodium hydroxide with a pH adjuster supply device, and filtered with a biological contact filtration device.
The treated water of biological contact filtration equipment
Iron 1.5mg / L
Aluminum 1mg / L
Manganese 1.8mg / L
Zinc 0.8mg / L
Lead 0.01mg / L
Copper 0.01mg / L
Cadmium 0.01mg / L
Until processed. Cleaning was performed once every two days, and the treatment of iron and manganese became stable.
The removal rate is
(35-1.5 + 10-1) /38.5×60=1.1 (mg / L · hr)
Met.

Comparative Example 1
In Example 3, raw water was treated in the biooxidation apparatus in the same manner as in Example 3 except that the filter medium used in the biooxidation apparatus was natural zeolite having a particle size of 10 to 30 mm.
The obtained treated water is iron 55mg / L
Aluminum 20mg / L
Manganese 5mg / L
Zinc 1.8mg / L
Lead 0.03mg / L
Copper 2.0mg / L
Cadmium 0.02mg / L
Was processed, but the processing hardly proceeded.

Comparative Example 2
In Example 3, the raw water was treated in the bio-oxidation apparatus in the same manner as in Example 3 except that the filter medium used in the biological contact filtration device was natural zeolite having a particle size of 0.3 to 1.5 mm. Processed with the device.
The treated water of the obtained biological contact filtration device is iron 3mg / L
Aluminum 1mg / L
Manganese 4mg / L
Zinc 1.4mg / L
Lead 0.01mg / L
Copper 0.8mg / L
Cadmium 0.01mg / L
Although it was processed as described above, cleaning was necessary twice a day, the processing performance of iron and manganese could not be ensured, and the processing performance of zinc and copper was poor.

Example 4
Regarding the treatment of fluorine when the water to be treated contains fluorine, fluorine removal was performed by a fluorine crystallizer.
The crystallizer is filled with calcium carbonate having an average particle size of 0.3 mm (Sankyo Seiyaku Co., Ltd., granular charcoal K-1) as a seed crystal, water to be treated is passed from the bottom, and into the inflow area. Air was supplied at 6 L / hr.
Calcium concentration 80mg / L
Fluorine concentration 2.4mg / L
To the water to be treated, 74.4 mg / L of 85% phosphoric acid is added so that phosphoric acid phosphorus is 20 mg / L, the pH is adjusted to 6.2 with sodium hydroxide, and the water flow rate is 13 m / hr. As a result, the treated water had a fluorine concentration of 0.75 mg / L.

Example 5
In Example 4, the water to be treated was treated in the same manner as in Example 4 except that calcium carbonate having an average particle diameter of 0.5 mm was used as a seed crystal in the crystallizer. The treated water had a fluorine concentration of 1.7 mg / L.

DESCRIPTION OF SYMBOLS 1 Raw water tank 2 Raw water pump 3 Bio-oxidizer 4 pH meter 5 Caustic tank 6 Caustic supply pump 7 Air diffuser 8 Blower 9 Backwash air pipe 10 Washing compressor (backwashing compressor)
DESCRIPTION OF SYMBOLS 11 Pressurization pump 12 Biological contact filtration apparatus 13 pH meter 14 Caustic supply pump 15 Washing air pipe 16 Treated water tank 19 Crystallization pump 20 Fluorination crystallizer 21 Phosphoric acid tank 22 Phosphoric acid supply pump 23 Crystallized drawing valve 24 Crystallization Waste collection pack 25 Backwash pump 26 Polymer tank 29 Polymer supply pump 30 Sludge concentration tank 31 Sun drying bed 32 Sludge transfer pump

Claims (19)

A bio-oxidation apparatus in which a filter medium having a particle size of 4 mm or more and 20 mm or less is filled and microorganisms are supported on the filter medium, and a filter medium having a particle size of 0.5 mm or more and 4 mm or less is filled, and microorganisms are supported on the filter medium. Comprising a heavy metal, characterized in that the microorganism is a microorganism containing iron bacteria and manganese oxidizing bacteria in order , and the biological oxidizing apparatus includes an air diffuser for supplying air or oxygen Wastewater treatment equipment.   The bio-oxidation device includes a pH adjuster supply device that adjusts the pH of the water to be treated flowing into the bio-oxidation device to a range of 3.0 to 5.5, and the bio-contact filtration device is connected to the bio-contact filtration device. The apparatus for treating wastewater containing heavy metals according to claim 1, further comprising a pH adjuster supply device that adjusts the pH of the influent water to be treated to a range of 5.5 to 7.0.   The wastewater containing heavy metal contains fluorine, and is provided with a phosphate ion supply device after the biological contact filtration device, and has a crystallizer that crystallizes fluorine by adding phosphate ions. An apparatus for treating waste water containing the heavy metal according to claim 1.   The crystallization apparatus includes a device in which calcium carbonate having an average particle diameter of 0.2 mm or more and 0.8 mm or less is filled as a seed crystal, water to be treated is passed from the bottom, and a gas is blown into an inflow portion. The processing apparatus of the waste_water | drain containing the heavy metal of Claim 3.   The said crystallizer is equipped with the calcium ion supply apparatus which adds calcium ion to the to-be-processed water which flows into a crystallizer, The processing apparatus of the waste_water | drain containing the heavy metal of Claim 3 or 4 characterized by the above-mentioned.   The said bio-oxidation apparatus is provided with the iron ion supply apparatus which adds a bivalent iron ion to the to-be-processed water which flows in into a bio-oxidation apparatus, and / or the manganese ion supply apparatus which adds a manganese ion. The processing apparatus of the waste_water | drain containing the heavy metal as described in any one of 1-5.   The said biological oxidation apparatus is equipped with the manganese ion supply apparatus which adds manganese ion to the to-be-processed water which flows in into a biological oxidation apparatus, and the ammoniacal nitrogen supply apparatus which adds ammonia nitrogen. A wastewater treatment apparatus comprising the heavy metal according to any one of the above. A method for treating wastewater containing heavy metals, wherein the wastewater is filled with a filter medium having a particle size of 4 mm or more and 20 mm or less, a microorganism is supported on the filter medium, and a living body provided with an air diffuser for supplying air or oxygen A biological oxidation treatment step for treating with an oxidizer, and a biological contact filtration treatment step for treating with a biological contact filtration device in which a filter medium having a particle size of 0.5 mm or more and 4 mm or less is filled and microorganisms are supported on the filter medium. Yes, and processing method of waste water containing heavy metals, wherein said microorganism is a microorganism containing iron bacteria, manganese-oxidizing bacteria.   The pH of the water to be treated flowing into the bio-oxidation device is adjusted to a range of 3.0 to 5.5, and the pH of the water to be treated flowing into the biological contact filtration device is adjusted to a range of 5.5 to 7.0. A method for treating wastewater containing heavy metal according to claim 8.   The wastewater containing heavy metal contains fluorine, and has a fluorine crystallization step of removing fluorine by a crystallizer that crystallizes fluorine by adding phosphate ions after the biological contact filtration treatment step. The processing method of the waste_water | drain containing the heavy metal of Claim 8 or 9.   The phosphate ion is added so that the phosphoric acid phosphorus concentration is 4 to 9 times (mass ratio) with respect to the fluorine concentration of the water to be treated flowing into the crystallizer. Of waste water containing heavy metals.   The crystallizer is filled with calcium carbonate having an average particle size of 0.2 mm or more and 0.8 mm or less as a seed crystal, water to be treated is passed from the bottom, and crystallization is performed while blowing gas into the inflow portion. The processing method of the waste_water | drain containing the heavy metal of Claim 10 or 11 characterized by these.   A calcium ion supply step of adding calcium ions to the water to be treated flowing into the crystallizer, and the calcium ions are 10 to 20 times (Ca / F mass ratio) with respect to the fluorine concentration of the water to be treated. It adds so that it may become, The processing method of the waste_water | drain containing the heavy metal as described in any one of Claims 10-12 characterized by the above-mentioned.   The method for treating wastewater containing heavy metals according to any one of claims 10 to 13, wherein the pH of the water to be treated flowing into the crystallizer is 6.0 to 7.0. The ratio of the concentration of divalent iron ions in the water to be treated flowing into the biological oxidizer to the concentration of heavy metals other than divalent iron ions and manganese ions (heavy metal mass ratio other than Fe ²⁺ / Fe ²⁺ and Mn) is When the ratio is less than 5, divalent iron ions are added to the water to be treated so that the ratio is 5 to 10. The heavy metal according to any one of claims 8 to 14, Wastewater treatment method including. If the heavy metal other than the divalent iron ion and manganese ion contains arsenic and lead, and the ratio of the concentration of the divalent iron ion to the arsenic and lead concentration (Fe ²⁺ / As + Pb mass ratio) is less than 5, The method for treating wastewater containing heavy metals according to claim 15, wherein divalent iron ions are added to water so that the ratio is 5 to 10. The ratio of the concentration of manganese ions in the water to be treated flowing into the bio-oxidizer to the concentration of heavy metals other than divalent iron ions and manganese ions (heavy metal mass ratio other than Mn / Fe ²⁺ and Mn) is less than 0.5. In the case, manganese ion is added to the water to be treated so that the ratio is 0.5 to 1, treatment of wastewater containing heavy metal according to any one of claims 8 to 16. Method. The concentration of divalent iron ions in the water to be treated flowing into the biological oxidizer is 0.5 mg / L or less, and the ratio of the manganese ion concentration to the concentration of divalent iron ions and heavy metals other than manganese ions (Mn / Fe ^{When the} mass ratio of heavy metals other than ²⁺ and Mn is less than 0.5, manganese ions are added to the water to be treated so that the ratio is 0.5 to 1, and ammonia nitrogen is added to the Mn concentration. 18. The method for treating wastewater containing heavy metals according to claim 17, wherein the treatment is performed so that the amount is 0.5 to 1 times (NH ₄ —N / Mn mass ratio).   When the total concentration of iron and aluminum in the water to be treated flowing into the biological oxidizer is 20 mg / L or more, the filtration rate of the biological oxidizer is 0.8 mg / L · min to 1.5 mg / L · min. The filtration rate of the biological contact filtration device is 1.2 mg / L · min or less when the total concentration of iron and aluminum in the water to be treated flowing into the biological contact filtration device is 15 mg / L or more. The processing method of the waste_water | drain containing the heavy metal in any one of Claims 8-18.

Images