JP3767800B2 - Nitrogen-phosphorus-containing wastewater treatment method and apparatus - Google Patents

Description

【００２０】
（試験条件）
以下に試験条件、方法を記す。
直径１５ｃｍ、高さ３ｍの円筒カラムに、粒状ゼオライト（山形県産出、平均粒径３．５ｍｍ）を、充填高さ２ｍに装填して吸着槽を構成した。
この吸着器に、前記試験対象水を、ろ過速度１２０ｍ／ｄで下向流で通水した。原水には、水酸化第２鉄微粒子（製造法は、塩化第２鉄液に苛性ソーダを添加して、ｐＨ６に中和して、水酸化第２鉄微粒子を生成させた）を２０ｍｇ／リットル添加し、かつ、アニオン性高分子凝集剤（エバグロースＬＥＡ６０１；荏原製品）を０．５ｍｇ／リットル添加し、管路内で２０秒攪拌させた後、ゼオライト充填層に供給した。
【００２１】
この条件で運転を続けた結果、ろ過抵抗（水柱圧で）が１ｍに達するまでのろ過継続時間は、約３２時間であった。また、３２時間通水後の処理水水質は、ＳＳ０．５ｍｇ／リットル、リン０．４ｍｇ／リットル、アンモニア性窒素１．５ｍｇ／リットルと効果的にＳＳ、リン、アンモニアが除去された。
３２時間後に原水の通水を止め、ゼオライト充填層の洗浄を行った。
洗浄は、原水を上向流（流速５００ｍ／ｄ）で１０分間供給し、充填層内のＳＳを追い出して、水酸化第２鉄微粒子を含む排水を流出させた。
【００２２】
しかる後、このゼオライト充填層に対し、原水に後記するリン回収工程からのアルカリ排水を添加することにより調製したゼオライト生物再生用水をＳＶ２（１／ｈ）で供給し、かつ、空気を散気装置２１から該充填層に散気して、再生排水の溶存酸素を１ｍｇ／リットル以上に制御した。該充填層にこの条件で２４時間通水した結果、ゼオライトに吸着されていたアンモニアは完全に硝化され、ゼオライトのアンモニア吸着能力が回復した。回復したかの確認方法は、生物再生後のゼオライト充填層に、ｐＨ１２のＮａＯＨ水溶液を供給し、流出水のアンモニア濃度を測定する方法によった。生物再生が不十分である場合は、アンモニア性窒素が検出される。
【００２３】
生物再生時に流出する生物再生排水には、亜硝酸性もしくは硝酸性窒素が含まれているので、この再生排水を、下水の２次処理工程の生物学的脱窒素工程（図示せず）に供給すると、下水中のＢＯＤを水素供与体として、再生排水中の亜硝酸性もしくは硝酸性窒素の生物学的脱窒素（窒素ガスへの還元）が進行するので、ゼオライト充填層生物再生排水の処理装置を、設置する必要はない。
【００２４】
次に、先の洗浄操作で出たリンを吸着した水酸化鉄微粒子を含有するゼオライト充填層洗浄排水に、苛性ソーダを添加し、ｐＨ１２に調整し、３０分攪拌した後、リンが脱着した水酸化鉄微粒子を沈殿させ、沈殿後のリン分を含有する分離水にＣａイオン（塩化カルシウムを使用）を、リン（濃度３５ｍｇ／リットル）に対しモル比で２になるように添加し、１０分間攪拌してＨＡＰの結晶を析出させ後、析出したＨＡＰを沈殿させ、リン資源として回収した。沈殿により分離したリン脱着水酸化鉄微粒子は、循環的に使用し定量的（２０〜２５ｍｇ／リットル）に原水に添加し、リン吸着材として再利用した。その際に出るＨＡＰ回収後のｐＨ１２のアルカリ性分離液はアルカリ排水として、ゼオライト生物再生用水に添加した。
【００２５】
以上のような態様で６ヶ月間運転を継続したところ、ゼオライト充填層処理水の水質は、ＳＳ０．７ｍｇ／リットル、リン０．３〜０．６ｍｇ／リットル、アンモニア性窒素１．１〜２．３ｍｇ／リットルが安定して得られ、ゼオライトの生物学的再生、及びリン吸着水酸化鉄からのリン脱着が良好に行われたことが確認された。
【００２６】
【発明の効果】
以上のように、本発明によれば次のような顕著な効果を発揮でき、下水の生物処理水等から、リンを有価資源として回収可能な革新的な汚水処理プロセスが得られる。
（１）単一の充填層によって、ＳＳ、リン、アンモニアの高度の除去が一挙に達成できる。すなわち、従来行われたいる、下水の活性汚泥処理水を砂ろ過層に通水しＳＳをろ過除去する三次処理工程における砂ろ過材の代わりに、粒状ゼオライトを充填し、窒素−リン含有排水にリン吸着性微粒子を添加するだけでＳＳ、リン、アンモニアが同時に除去できるという顕著な効果がある。
（２）従来の脱リン用の無機凝集剤を使用しないので、水酸化アルミニウム、水酸化鉄などを含有する難脱水性の凝集沈殿汚泥が発生しないため、汚泥処理が不要である。
（３）リンが、ＨＡＰ、ＭＡＰなどの有価リン資源として回収できる。
（４）リン回収工程から流出するアルカリ排水を、ゼオライトの生物再生時に必要な硝化反応のアルカリとして有効利用できるので、ゼオライトの生物再生時にｐＨ低下が起きず、生物再生が効果的に行われる。
【図面の簡単な説明】
【図１】本発明のリン−窒素含有排水の処理方法を示すブロック図である。
【符号の説明】
１ 生物処理水（原水）
２ リン吸着性微粒子
３ 吸着槽
３Ａ ゼオライト充填層
４ 処理水
５ 洗浄用水
６ 洗浄排水
７ 沈殿槽
８ 沈殿スラリ
９ 分離水
１０ アルカリ剤
１１ 攪拌槽
１２ 固液分離槽
１３ 脱着リン含有水
１４ Ｃａ剤又はＭｇ剤
１５ 脱着リン吸着性微粒子
１６ 晶析装置
１７ ＨＡＰ又はＭＡＰ
１８ アルカリ排水
１９ 再生用水
２０ 酸素含有ガス
２１ 散気装置
２２ 生物再生水[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a new technology capable of simultaneously removing phosphorus and nitrogen from phosphorus and nitrogen-containing wastewater such as biologically treated water of sewage and recovering phosphorus as a valuable resource.
[0002]
[Prior art]
A typical technique for removing nitrogen components from organic wastewater is a biological nitrification denitrification method. The basic idea of this technology is to biologically nitrify ammoniacal nitrogen in wastewater almost completely, circulate the nitrification solution to the denitrification section, and biologically denitrify using BOD of the wastewater. Is. Accordingly, there is a feature that almost no compound containing ammonia and ammonia nitrogen remains in the treated water, and NO _x remains. Since the residual NO _x concentration is governed by the BOD / N ratio of raw water and the nitrification liquid circulation rate, in the case of sewage with a small BOD / N ratio, the nitrogen removal rate is about 80% and the nitrogen removal rate is 90%. In order to achieve the above, it was impossible to provide a second denitrification section and add an expensive organic carbon source such as methanol from the outside.
[0003]
As a chemical removal method of ammonia, a selective ion exchange method of ammonia using zeolitic minerals (zeolite, clinobutyrite, mordenite, synthetic zeolite, etc.) is known. It was not possible to remove phosphorus and nitrogen simultaneously from the sewage. As a phosphorus removal technique, a biological dephosphorization method is known. However, there is a drawback that the phosphorus removal effect is unstable, and that skilled and careful operation management is required.
The phosphorus removal method by adding a flocculant such as aluminum sulfate can surely remove phosphorus, but has a disadvantage that hardly dewatering sludge is generated. These phosphorus removal techniques cannot remove phosphorus and nitrogen from sewage simultaneously. Moreover, phosphorus could not be recovered as a resource that can be easily reused.
[0004]
[Problems to be solved by the invention]
The present invention broadly and fully utilizes the advantages of conventional individual technologies, solves the drawbacks of conventional individual technologies, achieves simultaneous removal of phosphorus and nitrogen, and enhances the removal rate. The objective is to establish new technologies that can be used. Another object of the present invention is to provide a new technology that not only removes phosphorus but also recovers it as a resource.
Most of the phosphorus in our sewage comes from imported foreign phosphorus ore resources. Since it has been pointed out that phosphorus ore resources will be depleted in the near future, it is extremely important to establish technology that can recover phosphorus resources from sewage.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, the present invention has the following configuration.
(1) Phosphorus-adsorbing fine particles are added to nitrogen-phosphorus-containing wastewater, and water is passed through the granular zeolite packed bed, so that the ammoniacal nitrogen content in the drainage is adsorbed and removed by the granular zeolite, and the filtration resistance of the packed bed When A increases to a predetermined value, the packed bed is washed with water to discharge the captured fine particles A,
An insoluble phosphorus compound is prepared by adding an alkaline agent to the suspended water containing the fine particles discharged from the packed bed, desorbing phosphorus adsorbed on the fine particles, and adding Ca or Mg agent to the desorbed phosphorus-containing water. Step B in which particles are precipitated and solid-liquid separated,
In passing water through the granular zeolite packed bed of nitrogen-phosphorus containing wastewater to which phosphorus-adsorbing fine particles have been added, when the concentration of ammoniacal nitrogen in the packed bed effluent increases to a predetermined value, Nitrification in which the insoluble phosphorus compound is precipitated in Step B and aerated with oxygen-containing gas while supplying alkaline drainage that is produced when solid-liquid separation is performed, so that ammonia adsorbed on the granular zeolite is immobilized on the zeolite surface. Step C, which is biologically nitrified by fungi and causes nitrate-containing water to flow out of the zeolite packed bed,
A method for treating phosphorus-nitrogen-containing wastewater, comprising three steps comprising:
(2) In step B, when Ca or Mg agent is added to desorbed phosphorus-containing water to precipitate insoluble phosphorus compound particles, anaerobic digestion and desorption liquid of sewage sludge, sludge dewatered separation liquid in desorbed phosphorus-containing water The method for treating phosphorus-nitrogen-containing wastewater according to (1) above, wherein ammonia content is replenished by adding at least one of the sludge concentrate and separation liquid.
[0006]
(3) An adsorption tank having a granular zeolite packed bed equipped with a measuring device for measuring flow resistance, an introduction pipe for nitrogen-phosphorus-containing wastewater to which phosphorus-adsorbing fine particles are added, and an electromagnetic valve that operates according to the signal of the measuring device. wash water inlet, detergent drain discharge pipe, inlet tube for introducing alkali waste water during biological reproduction, and only set the diffuser tube ejecting placed oxygen containing gas in the bottom, connected to the other end of the prior SL detergent drain discharge pipe Solid-liquid separation device, alkali treatment device for adding alkali to sludge from the solid-liquid separation device and desorbing phosphorus from phosphorus-adsorbed fine particles, treatment liquid from the alkali treatment device desorbing phosphorus-adsorbing fine particles and desorbed phosphorus Solid-liquid separation device for solid-liquid separation into contained water, crystallization device for adding Ca or Mg agent to desorbed phosphorus-containing water from the solid-liquid separation device to precipitate insoluble phosphorus compound particles, A liquid feed pipe for sending the desorbed phosphorus-adsorbing fine particles to a nitrogen-phosphorus-containing waste water introduction pipe, and a liquid feed pipe for sending the alkaline waste water from the crystallizer to the adsorption tank during biological regeneration of the adsorption tank. A phosphorus-nitrogen-containing wastewater treatment apparatus.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described based on FIG. 1 showing an application example to treated sewage water.
In FIG. 1, the case where the biologically treated water 1 which biologically treated the sewage by the activated sludge method etc. is shown as an example of phosphorus-nitrogen containing waste water. An adsorption tank having a packed bed 3A in which phosphorus-adsorbing fine particles 2 such as ferric hydroxide are added to biologically treated water (hereinafter also referred to as “raw water”) 1 and filled with granular zeolite mineral having a particle size of about 1 to 3 mm. Pass water through 3. Examples of the zeolite mineral include substances that adsorb ammonia, such as zeolite, clinobutyrite, mordenite, and synthetic zeolite.
[0008]
Phosphate ions in raw water 1 are adsorbed and removed by phosphorus-adsorbing fine particles 2 such as iron hydroxide fine particles, and fine particles adsorbing phosphorus are filtered and trapped in zeolite packed bed 3A, and ammonia nitrogen in raw water 1 is It is adsorbed and removed by the ion exchange action of the granular zeolite mineral.
Further, SS such as fine activated sludge in the raw water 1 is removed by filtration while passing through the zeolite packed bed 3A. Thus, SS, phosphorus, and ammonia are removed all at once in the course of the raw water 1 passing through the zeolite packed bed 3A, and the clear treated water 4 flows out.
As described above, in the present invention, it is a feature not seen in the prior art that a single packed bed exhibits a combined function of removing SS, phosphorus, and ammonia all at once.
[0009]
However, if the raw water flow into the zeolite packed bed 3A is continued, the amount of SS in the raw water 1 and the amount of phosphorus adsorbing fine particles 2 trapped in the zeolite packed bed 3A increases, and the filtration resistance increases. When the value (usually set to about 1 m with water head) is reached (usually 12 to 24 hours after the start of operation), the washing water 5 flows upward in the zeolite packed bed 3A, and the zeolite particles flow. And backwash (backwash). 6 is washing waste water. The washing waste water 6 is allowed to flow into an apparatus for solid-liquid separation such as precipitation and membrane filtration, in this case, the precipitation tank 7, and the fine particles 2 in the washing waste water 6 are separated. The settling tank 7 can also serve as a storage tank for washing waste water.
The zeolite packed bed 3A, whose filtration resistance has been reduced after the backwashing, is continued by passing the raw water 1 again, and by repeating this operation, the concentration of SS, phosphorus, ammonia from the zeolite packed bed 3A is repeated. Treated water 4 is obtained.
When the operation is continued in this way, the ammonia adsorption capacity of the granular zeolite in the zeolite packed bed 3A approaches the saturation (usually after passing water for 1-2 days), and the ammonia concentration of the treated water 4 in the granular zeolite packed bed 3A Only deteriorates to a predetermined value (usually set to 5 mg / liter).
[0010]
At this time, the flow of the raw water is stopped, and after performing step A, the biological regeneration treatment of the zeolite packed bed 3A is started.
In the following case, the raw water flow to the zeolite packed bed is stopped.
Case (1): When the trapped amount of SS in the packed bed 3A increases and the filtration resistance reaches a predetermined value.
Case (2) When the ammonia concentration in the effluent water (treated water) 4 of the packed bed 3A reaches a predetermined value.
In this case (1), water flow can be resumed if the zeolite packed bed is only backwashed as described above. However, in case (2), the ammonia adsorption capacity of the zeolite packed bed is saturated. Therefore, the water flow cannot be resumed unless the zeolite packed bed is regenerated.
The regeneration treatment of the zeolite packed bed 3A is performed as follows. The regeneration treatment of the zeolite packed bed 3A (meaning the treatment to restore again the ammonia adsorption ability of the zeolite mineral whose ammonia adsorption ability has decreased) is caused to flow downwardly into the zeolite packed bed 3A with the regeneration water 19 added with an alkali component. This is performed effectively by ventilating an oxygen-containing gas 20 such as air, pure oxygen, or oxygen-enriched air from an air diffuser 21 provided at the bottom of the adsorber 3 while passing water upward.
[0011]
That is, when water for regeneration 19 having sufficient oxygen and alkalinity is supplied to zeolite particles in which a large amount of ammonia has been adsorbed, they are adsorbed to the zeolite by the nitrifying bacteria that naturally grow and adhere to the surface of the zeolite particles. The resulting ammonia is biologically oxidized to nitrate nitrogen or nitrite nitrogen.
Since nitrate nitrogen or nitrite nitrogen has the property that zeolite is not adsorbed, it is desorbed from the zeolite and flows out of the system together with the biological regeneration waste water 22.
[0012]
One of the most important points of the present invention is the idea that an alkaline drainage 18 containing an alkali component flowing out from a phosphorus recovery step described later is added to the regeneration water 19 for granular zeolite.
That is, in order to biologically nitrify 1 kg of ammonia adsorbed on zeolite and oxidize it to nitrate nitrogen, it requires about 8 kg of alkali, so water and oxygen-containing gas are simply passed through the zeolite packed bed 3A. When supplied to, the pH is lowered by hydrogen ions generated by nitrification of ammonia, the nitrification activity is remarkably deteriorated, and the biological nitrification of ammonia adsorbed on zeolite does not proceed smoothly.
In the present invention, this problem can be solved by adding the alkaline waste water 18 discharged from the phosphorus recovery process described later to the regeneration water 19. As the regeneration water 19, raw water 1, treated water 4 and the like are used.
[0013]
Next, the phosphorus recovery process will be described.
The washing wastewater 6 or the biological regeneration wastewater 22 of the zeolite packed bed 3A to which the phosphorus-adsorbing fine particles 2 in the state of adsorbing phosphorus are attached is supplied to a solid-liquid separation process such as a sedimentation tank 7 to separate the phosphorus-adsorbing fine particles 2. When caustic alkaline agent 10 such as NaOH or KOH is added to the precipitation slurry 8, the pH is adjusted to 11 or more (preferably pH 11.2 to 12.2), and stirred in the stirring tank 11 for 10 to 30 minutes. OH ions are adsorbed on the fine particles 2 such as iron hydroxide, and as a result, the phosphorus adsorbed on the fine particles 2 is desorbed from the phosphorus-adsorbing fine particles 2.
[0014]
Then, it isolate | separates with the solid-liquid separation tank 12, and the alkaline desorption phosphorus containing water 13 containing the phosphorus adsorption | suction fine particle 15 by which phosphorus was desorbed, and desorption phosphorus is obtained.
Phosphorus-adsorbing fine particles 15 from which phosphorus has been desorbed have recovered their phosphorus adsorption capacity, so when added to raw water 1 again, phosphate ions in raw water 1 are adsorbed and removed.
When Ca agent or Mg agent 14 is added to desorbed phosphorus-containing water 13 and stirred under alkaline conditions, calcium phosphate such as hydroxyapatite (HAP) or magnesium ammonium phosphate (MAP) 17 crystallizes. Solid-liquid separation is performed by the crystallizer 16 and effectively used as resources such as fertilizer raw materials. As the crystallization device 16, any known device can be used.
[0015]
Since the waste water 18 from the crystallizer (solid-liquid separator) 16 for depositing phosphorus has high alkalinity, it is used as the alkali for bioregeneration of the zeolite packed bed 3 as described above. Therefore, this waste water is called alkaline waste water 18.
Therefore, there is a remarkable effect that the alkali agent 10 such as NaOH can be used for the dual purpose of alkali for desorption from the phosphorus-adsorbing fine particles 2 and nitrification for biological regeneration of the zeolite packed bed.
[0016]
Ammonia nitrogen is indispensable when producing MAP 17 from the desorbed phosphorus-containing water 13, but in the present invention, the following means have been devised to supply ammonia.
That is, when the present invention is applied to sewage treatment, the anaerobic digestion and desorption liquid of sewage sludge, the sludge dehydrated separation liquid, and the sludge concentrated separation liquid are rotted as a result of the sludge being exposed to anaerobic and ammonia nitrogen. Is produced in large quantities from sludge, so any one of the anaerobic digestion and desorption liquid, sludge dewatering separation liquid, and sludge concentration separation liquid is used as the inflow water to the phosphorus precipitation step (crystallizer 16) of the present invention step. When mixed, a sufficient amount of ammonia nitrogen can be replenished, and a MAP production reaction can be effectively caused. Therefore, there is no need to purchase chemicals such as ammonium chloride, the cost can be reduced, and the back load of ammonia from the sludge treatment system can be reduced.
[0017]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not restrict | limited at all by this Example.
[0018]
Example 1
The standard activated sludge process water of the A sewage treatment facility was collected as nitrogen-phosphorus-containing water and tested by the method of the present invention. The water quality of the nitrogen-phosphorus-containing water (raw water) is shown in Table 1.
[0019]
[Table 1]

[0020]
(Test conditions)
The test conditions and methods are described below.
A cylindrical column having a diameter of 15 cm and a height of 3 m was charged with granular zeolite (produced in Yamagata Prefecture, average particle size of 3.5 mm) at a packing height of 2 m to constitute an adsorption tank.
The test object water was passed through the adsorber in a downward flow at a filtration speed of 120 m / d. 20 mg / liter of ferric hydroxide fine particles (manufactured by adding caustic soda to ferric chloride solution and neutralizing to pH 6 to produce ferric hydroxide fine particles) in raw water In addition, 0.5 mg / liter of an anionic polymer flocculant (Ebagulose LEA601; Ebara product) was added, and the mixture was stirred for 20 seconds in a pipe, and then supplied to the zeolite packed bed.
[0021]
As a result of continuing the operation under these conditions, the filtration duration time until the filtration resistance (in water column pressure) reached 1 m was about 32 hours. In addition, SS, phosphorus and ammonia were effectively removed from the treated water after passing for 32 hours with SS 0.5 mg / liter, phosphorus 0.4 mg / liter and ammoniacal nitrogen 1.5 mg / liter.
After 32 hours, the flow of raw water was stopped, and the zeolite packed bed was washed.
In the cleaning, raw water was supplied in an upward flow (flow rate 500 m / d) for 10 minutes, the SS in the packed bed was driven out, and the waste water containing ferric hydroxide fine particles was discharged.
[0022]
Thereafter, the zeolite bioregeneration water prepared by adding alkaline waste water from the phosphorus recovery step described later to the raw water is supplied to the zeolite packed bed by SV2 (1 / h), and air is diffused. The gas was diffused from 21 to the packed bed, and the dissolved oxygen in the reclaimed waste water was controlled to 1 mg / liter or more. As a result of passing water through the packed bed under these conditions for 24 hours, the ammonia adsorbed on the zeolite was completely nitrified, and the ammonia adsorption ability of the zeolite was recovered. The recovery method was based on a method in which a pH 12 NaOH aqueous solution was supplied to the zeolite packed bed after bioregeneration and the ammonia concentration of the effluent water was measured. If the biological regeneration is insufficient, ammoniacal nitrogen is detected.
[0023]
Biological regeneration wastewater that flows out during biological regeneration contains nitrite or nitrate nitrogen, so this regeneration wastewater is supplied to the biological denitrification process (not shown) in the secondary treatment process of sewage. Then, biological denitrification (reduction to nitrogen gas) of nitrite or nitrate nitrogen in the reclaimed wastewater proceeds using BOD in the sewage as a hydrogen donor. Need not be installed.
[0024]
Next, caustic soda is added to the zeolite packed bed washing wastewater containing the iron hydroxide fine particles adsorbing the phosphorus adsorbed in the previous washing operation, adjusted to pH 12, stirred for 30 minutes, and then the hydroxylated desorbed phosphorus. Precipitating iron fine particles, adding Ca ions (using calcium chloride) to the separated water containing phosphorus after precipitation so that the molar ratio is 2 with respect to phosphorus (concentration 35 mg / liter) and stirring for 10 minutes Then, after HAP crystals were precipitated, the precipitated HAP was precipitated and recovered as phosphorus resources. Phosphorus-desorbed iron hydroxide fine particles separated by precipitation were cyclically used, added quantitatively (20 to 25 mg / liter) to raw water, and reused as a phosphorus adsorbent. At that time, the alkaline separation liquid having a pH of 12 after the recovery of HAP was added to the water for zeolite bioregeneration as alkaline drainage.
[0025]
When the operation was continued for 6 months in the above manner, the quality of the zeolite packed bed treated water was SS 0.7 mg / liter, phosphorus 0.3 to 0.6 mg / liter, ammoniacal nitrogen 1.1 to 2. 3 mg / liter was stably obtained, and it was confirmed that the biological regeneration of zeolite and phosphorus desorption from phosphorus-adsorbed iron hydroxide were performed satisfactorily.
[0026]
【The invention's effect】
As described above, according to the present invention, the following remarkable effects can be exhibited, and an innovative sewage treatment process capable of recovering phosphorus as a valuable resource from biologically treated water of sewage can be obtained.
(1) A high degree of removal of SS, phosphorus and ammonia can be achieved at once by a single packed bed. That is, instead of the sand filter material in the tertiary treatment process in which the activated sludge treated water of sewage is conventionally passed through the sand filtration layer and SS is removed by filtration, it is filled with granular zeolite to form nitrogen-phosphorus-containing wastewater. There is a remarkable effect that SS, phosphorus, and ammonia can be simultaneously removed by simply adding phosphorus-adsorbing fine particles.
(2) Since a conventional inorganic deaggregating agent for dephosphorization is not used, sludge treatment is unnecessary because hardly dewatering coagulating sedimentation sludge containing aluminum hydroxide, iron hydroxide or the like is not generated.
(3) Phosphorus can be recovered as valuable phosphorus resources such as HAP and MAP.
(4) Since the alkaline drainage flowing out from the phosphorus recovery step can be effectively used as an alkali for the nitrification reaction necessary for the biological regeneration of the zeolite, the pH is not lowered during the biological regeneration of the zeolite, and the biological regeneration is performed effectively.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a method for treating phosphorus-nitrogen-containing wastewater according to the present invention.
[Explanation of symbols]
1 Biologically treated water (raw water)
2 Phosphorus-adsorbing fine particles 3 Adsorption tank 3A Zeolite packed bed 4 Treated water 5 Washing water 6 Washing drainage 7 Precipitation tank 8 Precipitation slurry 9 Separation water 10 Alkaline agent 11 Stirring tank 12 Solid-liquid separation tank 13 Desorbed phosphorus-containing water 14 Ca agent or Mg agent 15 Desorbed phosphorus-adsorbing fine particles 16 Crystallizer 17 HAP or MAP
18 Alkaline drainage 19 Reclaimed water 20 Oxygen-containing gas 21 Aeration device 22 Biologically reclaimed water

Claims (3)

Phosphorus-adsorbing fine particles are added to the nitrogen-phosphorus-containing waste water, and water is passed through the granular zeolite packed bed, so that the ammonia nitrogen content in the drained water is adsorbed and removed by the granular zeolite. Step A in which the fine particles that have been trapped are discharged by washing the packed bed with water.
An insoluble phosphorus compound is prepared by adding an alkaline agent to the suspended water containing the fine particles discharged from the packed bed, desorbing phosphorus adsorbed on the fine particles, and adding Ca or Mg agent to the desorbed phosphorus-containing water. Step B in which particles are precipitated and solid-liquid separated,
In passing water through the granular zeolite packed bed of nitrogen-phosphorus containing wastewater to which phosphorus-adsorbing fine particles have been added, when the concentration of ammoniacal nitrogen in the packed bed effluent increases to a predetermined value, Nitrifying bacteria in which ammonia adsorbed on the granular zeolite was immobilized on the zeolite surface by aeration with an oxygen-containing gas while supplying the alkaline drainage produced when the insoluble phosphorus compound was precipitated and separated into solid and liquid in Step B Step C for biologically nitrifying by the process and allowing the nitrate nitrogen-containing water to flow out of the zeolite packed bed,
A method for treating phosphorus-nitrogen-containing wastewater, comprising three steps comprising: In step B, when Ca or Mg agent is added to desorbed phosphorus-containing water to precipitate insoluble phosphorus compound particles, anaerobic digestion and desorption liquid of sewage sludge, sludge dewatered separation liquid, sludge concentration in desorbed phosphorus-containing water The method for treating phosphorus-nitrogen-containing wastewater according to claim 1, wherein at least one of the separated liquids is added to replenish the ammonia content. Washing water equipped with an adsorption tank having a granular zeolite packed bed equipped with a measuring device for measuring the flow resistance, a nitrogen-phosphorus-containing drainage pipe added with phosphorus-adsorbing fine particles, and an electromagnetic valve operated by the signal of the measuring device inlet tube, washed drainage discharge tube, inlet tube for introducing alkali waste water during biological reproduction, and only set the diffuser tube ejecting placed oxygen containing gas in the bottom, the solid was connected to the other end of the prior SL detergent drain discharge pipe A liquid separation device, an alkali treatment device for adding phosphorus to sludge from the solid-liquid separation device to desorb phosphorus from the phosphorus-adsorbed fine particles, a treatment liquid from the alkali treatment device, desorbing phosphorus-adsorbing fine particles, and desorbed phosphorus-containing water; A solid-liquid separation apparatus for solid-liquid separation, a crystallization apparatus for adding Ca or Mg agent to desorbed phosphorus-containing water from the solid-liquid separation apparatus to precipitate insoluble phosphorus compound particles, and desorption from the solid-liquid separation apparatus A liquid feed pipe for sending phosphorus-adsorbing fine particles to a nitrogen-phosphorus-containing waste water introduction pipe, and a liquid feed pipe for sending alkaline waste water from the crystallizer to the adsorption tank during biological regeneration of the adsorption tank, To treat wastewater containing phosphorus and nitrogen.

Images