JP5516874B2 - Water treatment method and ultrapure water production method - Google Patents

Water treatment method and ultrapure water production method Download PDF

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JP5516874B2
JP5516874B2 JP2010105151A JP2010105151A JP5516874B2 JP 5516874 B2 JP5516874 B2 JP 5516874B2 JP 2010105151 A JP2010105151 A JP 2010105151A JP 2010105151 A JP2010105151 A JP 2010105151A JP 5516874 B2 JP5516874 B2 JP 5516874B2
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JP2011230093A (en
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伸説 新井
哲朗 深瀬
太郎 飯泉
望 育野
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Kurita Water Industries Ltd
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Priority to US13/643,199 priority patent/US20130105389A1/en
Priority to PCT/JP2011/056309 priority patent/WO2011135942A1/en
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Description

本発明は、原水の水処理方法及びこの水処理方法で処理した処理水を用いた超純水製造方法に関し、特に原水中の尿素を高度に除去することができる水処理方法及びこの水処理方法で処理した処理水を用いた超純水製造方法に関する。   The present invention relates to a raw water treatment method and an ultrapure water production method using treated water treated by the water treatment method, and more particularly, a water treatment method capable of highly removing urea in raw water and the water treatment method. It is related with the manufacturing method of the ultrapure water using the treated water processed by this.

従来、市水、地下水、工水等の原水から超純水を製造する超純水製造装置は、基本的に、前処理装置、一次純水製造装置及び二次純水製造装置から構成される。このうち、前処理装置は、凝集、浮上、濾過装置で構成される。一次純水製造装置は、例えば、2基の逆浸透膜分離装置及び混床式イオン交換装置、あるいはイオン交換純水装置及び逆浸透膜分離装置で構成される。また、二次純水製造装置は、例えば、低圧紫外線酸化装置、混床式イオン交換装置及び限外濾過膜分離装置で構成される。   Conventionally, an ultrapure water production apparatus that produces ultrapure water from raw water such as city water, groundwater, and industrial water basically includes a pretreatment apparatus, a primary pure water production apparatus, and a secondary pure water production apparatus. . Among these, the pretreatment device is composed of agglomeration, levitation, and filtration devices. The primary pure water production apparatus includes, for example, two reverse osmosis membrane separation devices and a mixed bed ion exchange device, or an ion exchange pure water device and a reverse osmosis membrane separation device. Further, the secondary pure water production apparatus is composed of, for example, a low-pressure ultraviolet oxidizer, a mixed bed ion exchanger, and an ultrafiltration membrane separator.

このような超純水製造装置においては、その純度の向上への要求が高まってきており、これに伴いTOC成分の除去が求められている。超純水中のTOC成分のうち、特に尿素はその除去が困難であり、TOC成分を低減すればするほど尿素の除去がTOC成分の含有率に与える影響が大きい。そこで、超純水製造装置に供給される水中から尿素を除去することにより、超純水中のTOCを十分に低減することが特許文献1〜3に記載されている。   In such an ultrapure water production apparatus, there is an increasing demand for improvement in the purity, and accordingly, removal of the TOC component is required. Of the TOC components in ultrapure water, it is particularly difficult to remove urea, and the lower the TOC component, the greater the influence of urea removal on the TOC component content. Therefore, Patent Documents 1 to 3 describe that TOC in ultrapure water is sufficiently reduced by removing urea from the water supplied to the ultrapure water production apparatus.

特許文献1には、前処理装置に生物処理装置を組み込み、この生物処理装置で尿素を分解することが開示されている。また、特許文献2には、前処理装置に生物処理装置を組み込み、被処理水(工業用水)と半導体洗浄回収水との混合水を通水する。この半導体洗浄回収水中に含有される有機物が生物処理反応の炭素源となり、尿素の分解速度を向上させることが開示されている。なお、この半導体洗浄回収水中にはアンモニウムイオン(NH )が多量に含有されている場合があり、これが尿素と同様に窒素源となり、尿素の分解を阻害することがある。さらに、特許文献3には、特許文献2の上記問題点を解決するために、被処理水(工業用水)と半導体洗浄回収水とを別々に生物処理した後に混合し、一次純水製造装置及び二次純水製造装置に通水することが記載されている。 Patent Document 1 discloses that a biological treatment device is incorporated in a pretreatment device and urea is decomposed by this biological treatment device. Further, in Patent Document 2, a biological treatment apparatus is incorporated into a pretreatment apparatus, and mixed water of treated water (industrial water) and semiconductor cleaning / collecting water is passed through. It is disclosed that an organic substance contained in the semiconductor cleaning / collecting water serves as a carbon source for a biological treatment reaction and improves the decomposition rate of urea. In addition, there are cases where a large amount of ammonium ions (NH 4 + ) are contained in this semiconductor cleaning / recovered water, which becomes a nitrogen source in the same manner as urea and may inhibit the decomposition of urea. Further, in Patent Document 3, in order to solve the above-mentioned problem of Patent Document 2, the water to be treated (industrial water) and the semiconductor cleaning / collecting water are mixed after being biologically treated separately, It is described that water is passed through a secondary pure water production apparatus.

特開平6−63592号公報JP-A-6-63592 特開平6−233997号公報JP-A-6-233997 特開平7−313994号公報JP-A-7-313994

しかしながら、特許文献2に記載の水処理方法のように、被処理水に炭素源を添加すると、生物処理装置の尿素分解除去効率は向上するものの、生物処理装置内の菌体の増殖量が増加し、当該生物処理装置からの菌体の流出量が増加する、という問題点がある。   However, when a carbon source is added to the water to be treated as in the water treatment method described in Patent Document 2, although the urea decomposition and removal efficiency of the biological treatment apparatus is improved, the amount of growth of bacterial cells in the biological treatment apparatus is increased. However, there is a problem that the amount of bacterial cells flowing out from the biological treatment apparatus increases.

また、特許文献2に記載の水処理方法では、炭素源としてアンモニウムイオンの含有量の多い半導体洗浄回収水を用いると、アンモニウムイオンが尿素の分解を阻害する、という問題点がある。   Further, the water treatment method described in Patent Document 2 has a problem in that when semiconductor cleaning / collecting water having a high ammonium ion content is used as a carbon source, ammonium ions inhibit the decomposition of urea.

本発明は、上記課題に鑑みてなされたものであり、原水中のTOC、特に尿素を高度に分解することができる水処理方法を提供することを目的とする。また、本発明は、この水処理方法を利用した超純水製造方法を提供することを目的とする。   This invention is made | formed in view of the said subject, and it aims at providing the water treatment method which can decompose | degrade TOC in raw | natural water, especially urea, highly. Moreover, an object of this invention is to provide the ultrapure water manufacturing method using this water treatment method.

上記課題を解決するために、第一に本発明は、有機物を含有する原水を生物処理する水処理方法において、原水にアンモニア性の窒素源を添加した後、生物処理を行うことを特徴とする水処理方法を提供する(発明1)。 In order to solve the above problems, first, the present invention is characterized in that in a water treatment method for biologically treating raw water containing organic matter, biological treatment is performed after adding an ammoniacal nitrogen source to the raw water. A water treatment method is provided ( Invention 1).

上記発明(発明1)によれば、尿素の除去には硝化菌群が関与しており、原水にアンモニア性の窒素源を添加することにより、これら硝化菌群が増殖するとともにその活性が高まり、尿素を分解除去することができる。このようにして尿素の分解除去ができる理由は、以下の通りであると考えられる。 According to the above invention ( Invention 1), nitrifying bacteria are involved in the removal of urea, and by adding an ammoniacal nitrogen source to the raw water, these nitrifying bacteria grow and their activity increases, Urea can be decomposed and removed. The reason why urea can be decomposed and removed in this way is considered as follows.

すなわち、特許文献2に記載された水処理方法では、硝化菌ではなく、BOD資化細菌(従属栄養細菌)が有機物を分解・資化するに当たり、窒素源として尿素及び尿素誘導体を分解し、アンモニアとして摂取することで、尿素及び尿素誘導体を除去する処理機構であると推測される。これに対し、上記発明(発明1)では、硝化菌群が、アンモニアを亜硝酸、硝酸に酸化する過程において、尿素及び尿素誘導体をアンモニア又は直接亜硝酸に酸化することで尿素及び尿素誘導体が除去される機構であるため、アンモニア性の窒素源を添加しても尿素の分解の阻害とはならず、むしろ、これら硝化菌群の増殖、活性を高める要因となる。この結果、活性の高まった硝化菌群により、尿素及び尿素誘導体の除去性能が向上すると推察される。 That is, in the water treatment method described in Patent Document 2, when BOD assimilating bacteria (heterotrophic bacteria) decompose and assimilate organic matter, not nitrifying bacteria, urea and urea derivatives are decomposed as nitrogen sources, ammonia It is presumed that this is a treatment mechanism for removing urea and urea derivatives. On the other hand, in the above invention ( Invention 1), the nitrifying bacteria group removes urea and urea derivatives by oxidizing urea and urea derivatives directly to ammonia or nitrous acid in the process of oxidizing ammonia to nitrous acid and nitric acid. Therefore, the addition of an ammoniacal nitrogen source does not inhibit urea decomposition, but rather increases the growth and activity of these nitrifying bacteria. As a result, it is presumed that the removal performance of urea and urea derivatives is improved by the group of nitrifying bacteria having increased activity.

上記発明(発明1)においては、生物担持担体を有する生物処理手段により前記生物処理を行うのが好ましい(発明2)。かかる発明(発明2)によれば、生物処理手段が生物担持担体を用いた生物膜法であるため、流動床の場合よりも生物処理手段からの菌体の流出を抑制することができ、処理の効果が高く、かつその効果を長期間維持することができる。 In the said invention ( invention 1), it is preferable to perform the said biological treatment by the biological treatment means which has a biological support | carrier ( invention 2). According to this invention ( Invention 2), since the biological treatment means is a biofilm method using a biological carrier, it is possible to suppress the outflow of bacterial cells from the biological treatment means more than in the case of a fluidized bed. The effect is high and the effect can be maintained for a long time.

上記発明(発明1,2)においては、前記アンモニア性の窒素源が、アンモニウム塩であるのが好ましい(発明3)。 In the above inventions ( Inventions 1 and 2), the ammoniacal nitrogen source is preferably an ammonium salt ( Invention 3).

上記発明(発明3)によれば、塩化アンモニウム等のアンモニウム塩は、硝化菌群の活性化に好適であり、また、その添加・制御も容易であり、尿素の濃度を低く維持するのに好適である。 According to the said invention ( invention 3), ammonium salts, such as ammonium chloride, are suitable for activation of a nitrifying bacteria group, the addition and control are also easy, and it is suitable for keeping the urea density | concentration low. It is.

上記発明(発明1〜3)においては、前記生物処理の後段において還元処理を行うのが好ましい(発明4)。 In the said invention ( invention 1-3), it is preferable to perform a reduction process in the back | latter stage of the said biological treatment ( invention 4).

上記発明(発明4)によれば、生物処理の原水には、塩素系の酸化剤(次亜塩素酸など)が存在することが多いが、これらはアンモニア性の窒素源と反応し結合塩素化合物を形成することがある。結合塩素は遊離塩素と比較して酸化力は低いが、後段の処理において処理部材の酸化劣化を引き起こす可能性があるので、還元処理することにより、この結合塩素化合物を無害化することができる。 According to the above invention ( Invention 4), the raw water for biological treatment often contains a chlorine-based oxidant (such as hypochlorous acid), which reacts with an ammoniacal nitrogen source to form a combined chlorine compound. May form. Although bonded chlorine has lower oxidizing power than free chlorine, it may cause oxidative deterioration of the processing member in the subsequent processing, so that the combined chlorine compound can be rendered harmless by reduction treatment.

また、第二に本発明は、上記発明(発明1〜4)に係る水処理方法で得られた処理水を一次純水装置及び二次純水装置で処理して超純水を製造することを特徴とする超純水製造方法を提供する(発明5)。 Moreover, 2nd this invention processes the treated water obtained with the water treatment method which concerns on the said invention ( invention 1-4) with a primary pure water apparatus and a secondary pure water apparatus, and manufactures an ultrapure water. A method for producing ultrapure water is provided ( Invention 5).

上記発明(発明5)によれば、一次純水装置及び二次純水装置の前段の生物処理(水処理)において、尿素が十分に分解除去されているため、高純度の超純水を効率よく製造することができる。
According to the said invention ( invention 5), since urea is fully decomposed and removed in the biological treatment (water treatment) in the first stage of the primary pure water device and the secondary pure water device, high purity ultrapure water is efficiently used. Can be manufactured well.

本発明の水処理方法によれば、有機物を含有する原水にアンモニア性の窒素源を添加した後、生物処理を行っているので、これら硝化菌群が増殖するとともにその活性が高まることで、尿素を分解除去することができる。このような水処理方法による水処理を一次純水装置及び二次純水装置の前段において行うことにより、TOC濃度の低い高純度の超純水を効率よく製造することができる。   According to the water treatment method of the present invention, biological treatment is performed after adding an ammoniacal nitrogen source to raw water containing organic matter. Can be decomposed and removed. By performing the water treatment by such a water treatment method in the previous stage of the primary pure water device and the secondary pure water device, high purity ultrapure water having a low TOC concentration can be efficiently produced.

本発明の第一の実施形態に係る水処理方法を示す系統図である。It is a systematic diagram which shows the water treatment method which concerns on 1st embodiment of this invention. 本発明の第二の実施形態に係る水処理方法を示す系統図である。It is a systematic diagram which shows the water treatment method which concerns on 2nd embodiment of this invention. 本発明の一実施形態に係る水処理方法を利用した超純水製造方法を示す系統図である。It is a systematic diagram which shows the ultrapure water manufacturing method using the water treatment method which concerns on one Embodiment of this invention. 実施例1、2の尿素除去効果を示すグラフである。It is a graph which shows the urea removal effect of Example 1,2.

以下、添付図面を参照して本発明の実施形態について説明する。図1は、本発明の第一の実施形態に係る水処理方法を示す概略図である。   Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic view showing a water treatment method according to the first embodiment of the present invention.

図1において、1は、前処理装置から供給される原水Wを貯留しておく給水槽であり、この給水槽1から供給された原水Wは、生物処理手段2で生物処理された後、処理水W1として一次純水装置3に供給される。そして、生物処理手段2の前段でアンモニア性の窒素源(NH−N)を添加する In FIG. 1, reference numeral 1 denotes a water supply tank for storing raw water W supplied from a pretreatment device. The raw water W supplied from the water supply tank 1 is biologically treated by the biological treatment means 2 and then treated. The water W1 is supplied to the primary pure water device 3. Then, an ammoniacal nitrogen source (NH 3 -N) is added before the biological treatment means 2.

このような処理フローにおいて、処理対象となる原水Wとしては、地下水、河川水、市水、その他の工業用水、半導体製造工程からの回収水等が用いられる。また、これらの水を浄化処理したものであってもよい。この浄化処理としては、超純水の製造工程における前処理システム又はこれと同様の処理が好適である。具体的には、凝集・加圧浮上・濾過等の処理やこれらの処理の組合せが好適である。   In such a processing flow, as raw water W to be processed, ground water, river water, city water, other industrial water, recovered water from a semiconductor manufacturing process, and the like are used. Moreover, what purified these water may be used. As this purification treatment, a pretreatment system in the production process of ultrapure water or a treatment similar thereto is suitable. Specifically, a treatment such as agglomeration, pressure levitation, filtration, or a combination of these treatments is preferable.

原水(処理対象水)中の尿素濃度は5〜200μg/L、特に5〜100μg/L程度が好適である。   The urea concentration in the raw water (treatment target water) is preferably 5 to 200 μg / L, particularly about 5 to 100 μg / L.

本実施形態において、生物処理手段2とは、下水等の廃水中の汚濁物質を生物学的作用により分解、安定化させる処理を行う手段のことであり、好気性処理と嫌気性処理とに区別される。一般的に有機物は、生物処理により酸素呼吸・硝酸呼吸・発酵過程等で分解されて、ガス化されるか、微生物の体内に取り込まれ、汚泥として除去される。また、窒素(硝化脱窒法)やりん(生物学的リン除去法)の除去処理もできる。このような生物処理を行う手段を一般に生物反応槽という。このような生物処理手段2としては、特に制限はないが、生物担持担体の固定床を有するものが好ましい。特に、菌体の流出が少ない下向流方式の固定床が好ましい。   In the present embodiment, the biological treatment means 2 is a means for performing a treatment for decomposing and stabilizing pollutants in wastewater such as sewage by biological action, and distinguishes between aerobic treatment and anaerobic treatment. Is done. In general, organic matter is decomposed by biological treatment through oxygen respiration, nitric acid respiration, fermentation processes, etc., and is gasified or taken into the body of microorganisms and removed as sludge. Moreover, the removal process of nitrogen (nitrification denitrification method) and phosphorus (biological phosphorus removal method) can also be performed. A means for performing such biological treatment is generally called a biological reaction tank. Such a biological treatment means 2 is not particularly limited, but preferably has a fixed bed of a biological carrier. In particular, a fixed bed of a downward flow type with less bacterial cell outflow is preferred.

生物処理手段2を固定床とする場合、固定床を必要に応じて洗浄するのが好ましい。これにより、生物(菌体)の増殖による固定床の閉塞、マッドボール化、尿素の分解除去効率の低下等が生じることが防止される。この洗浄方法には特に制限はなく、例えば逆洗、すなわち、原水の通水方向と逆方向に洗浄水を通水して担体を流動化させ、堆積物の系外への排出、マッドボールの粉砕、生物の一部の剥離等を行うようにするのが好ましい。   When the biological treatment means 2 is a fixed bed, it is preferable to wash the fixed bed as necessary. As a result, it is possible to prevent the occurrence of blockage of the fixed bed, mudballing, a decrease in the decomposition and removal efficiency of urea, and the like due to the growth of organisms (bacteria). There is no particular limitation on this cleaning method. For example, backwashing, that is, flowing the cleaning water in the direction opposite to the direction of passing raw water to fluidize the carrier, discharging sediment out of the system, It is preferable to perform pulverization, exfoliation of a part of the organism, and the like.

また、固定床の担体の種類に特に制限はなく、活性炭、アンスラサイト、砂、ゼオライト、イオン交換樹脂、プラスチック製成形品等が用いられるが、酸化剤及び/又は殺菌剤の存在下で生物処理を実施するためには、酸化剤及び/又は殺菌剤の消費量の少ない担体を用いるのが好ましい。ただし、生物処理手段に高濃度の酸化剤及び/又は殺菌剤が流入する可能性がある場合には、酸化剤及び/又は殺菌剤を分解し得る活性炭等の担体を用いるのが好ましい。このように活性炭等を用いた場合、被処理水中の酸化剤及び/又は殺菌剤の濃度が高い場合であっても、菌体が失活、死滅することが防止される。   There are no particular restrictions on the type of carrier for the fixed bed, and activated carbon, anthracite, sand, zeolite, ion exchange resin, plastic molded products, etc. are used, but biological treatment is carried out in the presence of an oxidizing agent and / or a bactericidal agent. In order to carry out the above, it is preferable to use a carrier that consumes less oxidizing agent and / or fungicide. However, when there is a possibility that a high concentration of oxidizing agent and / or fungicide may flow into the biological treatment means, it is preferable to use a carrier such as activated carbon that can decompose the oxidizing agent and / or fungicide. Thus, when activated carbon etc. are used, even if it is a case where the density | concentration of the oxidizing agent and / or disinfectant in to-be-processed water is high, it is prevented that a microbial cell is inactivated and killed.

生物処理手段2への通水速度は、SV5〜50hr−1程度とするのが好ましい。この生物処理手段2への給水の水温は常温、例えば10〜35℃であり、pHはほぼ中性、例えば4〜8であることが好ましい。したがって、必要に応じて、生物処理手段の前段に熱交換機やpH調整剤添加手段を設けるのが好ましい。 The water flow rate to the biological treatment means 2 is preferably about SV5 to 50 hr- 1 . It is preferable that the temperature of water supplied to the biological treatment means 2 is normal temperature, for example, 10 to 35 ° C., and pH is approximately neutral, for example, 4 to 8. Therefore, it is preferable to provide a heat exchanger and a pH adjuster addition means in front of the biological treatment means as necessary.

この原水Wを生物処理手段2に導入する前に、アンモニア性の窒素源を添加する。このアンモニア性の窒素源としては、特に制限はなく、アンモニウム塩(無機化合物)、アンモニア水(水酸化アンモニウム)、さらには蛋白等の生分解によりアンモニウムイオン又は遊離アンモニアが生成され得る有機物等を好適に用いることができる。これらの中では、塩化アンモニウム等の無機アンモニウム塩が好ましい。   Before introducing the raw water W into the biological treatment means 2, an ammoniacal nitrogen source is added. The ammoniacal nitrogen source is not particularly limited, and is preferably an ammonium salt (inorganic compound), aqueous ammonia (ammonium hydroxide), or an organic substance that can generate ammonium ions or free ammonia by biodegradation of proteins and the like. Can be used. Among these, inorganic ammonium salts such as ammonium chloride are preferable.

上述したようなアンモニア性の窒素源の添加量は、0.1〜5mg/L(NH 換算)とすればよい。具体的には、原水W中のアンモニウムイオンの濃度が上記範囲内となるように添加すればよい。原水W中のアンモニウムイオン濃度が0.1mg/L(NH 換算)未満では、硝化菌群の活性を維持するのが困難となる一方、5mg/L(NH 換算)を超えても、さらなる硝化菌群の活性が得られないばかりか、生物処理手段2からのリーク量が多くなりすぎるため好ましくない。 The addition amount of the ammoniacal nitrogen source as described above may be 0.1 to 5 mg / L (converted to NH 4 + ). Specifically, it may be added so that the concentration of ammonium ions in the raw water W is within the above range. If the ammonium ion concentration in the raw water W is less than 0.1 mg / L (converted to NH 4 + ), it becomes difficult to maintain the activity of the nitrifying bacteria group, but even if it exceeds 5 mg / L (converted to NH 4 + ) Further, not only the activity of the nitrifying bacteria group is not obtained, but also the amount of leakage from the biological treatment means 2 becomes too large, which is not preferable.

アンモニア性の窒素源を、原水W中のアンモニウムイオンの濃度が上記範囲内となるように添加することにより、約10〜30日経過後の生物処理手段2における処理水W1中の尿素濃度を5μg/L以下、特に2μg/L以下に維持することができる。   By adding an ammoniacal nitrogen source so that the concentration of ammonium ions in the raw water W is within the above range, the urea concentration in the treated water W1 in the biological treatment means 2 after about 10 to 30 days has elapsed is 5 μg / L or less, particularly 2 μg / L or less can be maintained.

このように原水Wにアンモニア性の窒素源を添加することにより、TOCとしての尿素及び尿素誘導体を安定的に分解することができる、という驚くべき効果を奏し得ることを本発明者らは発見した。これは以下のような理由によるものと推測される。すなわち、尿素及び尿素誘導体の濃度は、市水、工業用水においては季節により変動があることが知られており、原水W中の尿素及び尿素誘導体の濃度が低くなれば硝化菌群の活性が低下し、その後急激に濃度上昇しても、硝化菌群の活性が追従できず、分解しきれないため、処理水W1にリークする。このため、アンモニア性の窒素源を添加して硝化菌群の活性を維持することで、原水W中の尿素及び尿素誘導体の濃度変動に追従し、生物処理手段2での処理水W1の尿素濃度を低く維持することができる。   As described above, the present inventors have found that by adding an ammoniacal nitrogen source to the raw water W, urea and urea derivatives as TOC can be stably decomposed, which can have a surprising effect. . This is presumably due to the following reasons. That is, it is known that the concentrations of urea and urea derivatives vary depending on the season in city water and industrial water. If the concentrations of urea and urea derivatives in raw water W are low, the activity of the nitrifying bacteria group decreases. However, even if the concentration increases rapidly thereafter, the activity of the nitrifying bacteria group cannot follow and cannot be completely decomposed, and therefore leaks into the treated water W1. For this reason, by adding an ammoniacal nitrogen source to maintain the activity of the nitrifying bacteria group, the urea concentration of the treated water W1 in the biological treatment means 2 follows the concentration fluctuations of urea and urea derivatives in the raw water W. Can be kept low.

アンモニア性の窒素源は、常時添加する必要はなく、例えば生物担体交換時の立上げ期間のみ添加する方法、あるいは一定期間毎に添加、無添加を繰り返す方法等を用いることができる。このように常時アンモニア性の窒素源を添加しないことにより、アンモニア性の窒素源の添加コストを低減することもできる、という効果も奏する。   The ammoniacal nitrogen source does not need to be added constantly. For example, a method of adding only during the start-up period at the time of exchanging the biological carrier, a method of repeating addition or non-addition every certain period, etc. can be used. Thus, by not always adding the ammoniacal nitrogen source, there is also an effect that the addition cost of the ammoniacal nitrogen source can be reduced.

なお、硝化細菌は、溶存酸素の存在下において、餌(アンモニア性の窒素源、尿素、尿素誘導体等)の存在しない状態(空曝気状態)が続くと活性が低下する。この活性低下を回避するための具体策としては、(1)常時又は間欠的にアンモニア性の窒素源を添加する方法(本発明に係る方法)、(2)生物処理給水又は処理水中のアンモニア性窒素、尿素等の濃度に応じてアンモニア性窒素源を添加制御する方法、(3)上記(2)と同様に溶存酸素濃度を制御する方法(脱酸素剤の添加、還元剤の添加、脱気処理、窒素ガス曝気による溶存酸素除去等)が挙げられる。簡便性及びコストの観点から、本発明の方法(上記(1)の方法)がより好ましい方法と考えられる。   In addition, the activity of nitrifying bacteria decreases when the state (air aeration state) in which bait (ammonia nitrogen source, urea, urea derivatives, etc.) does not exist continues in the presence of dissolved oxygen. Specific measures for avoiding this decrease in activity include (1) a method of constantly or intermittently adding an ammoniacal nitrogen source (method according to the present invention), and (2) ammoniacal treatment in biologically treated feed water or treated water. (3) A method for controlling the dissolved oxygen concentration in the same manner as (2) above (addition of oxygen absorber, addition of reducing agent, degassing) Treatment, removal of dissolved oxygen by nitrogen gas aeration, etc.). From the viewpoint of simplicity and cost, the method of the present invention (method (1) above) is considered to be a more preferable method.

なお、この原水W中には、必要に応じさらに酸化剤及び/又は殺菌剤を添加することができる。添加する酸化剤及び/又は殺菌剤の種類には特に制限はなく、尿素を効率的に分解する菌種を優先化し得るものが好適に用いられる。具体的には、次亜塩素酸ナトリウム、二酸化塩素等の塩素系酸化剤、モノクロラミン、ジクロラミン等の結合塩素剤(安定化塩素剤)等を好適に用いることができる。   In addition, in this raw | natural water W, an oxidizing agent and / or a disinfectant can be further added as needed. There is no restriction | limiting in particular in the kind of oxidizing agent and / or disinfectant to add, What can give priority to the bacterial species which decomposes | disassembles urea efficiently is used suitably. Specifically, a chlorine-based oxidizing agent such as sodium hypochlorite and chlorine dioxide, a combined chlorine agent (stabilized chlorine agent) such as monochloramine and dichloroamine, and the like can be suitably used.

次に本発明の第二の実施形態に係る水処理方法について、図2を参照して説明する。第二の実施形態に係る水処理方法は、上述した第一の実施形態において、生物処理手段2の後段で一次純水装置3の前に還元処理手段4を有する以外は同様の構成を有する。   Next, a water treatment method according to the second embodiment of the present invention will be described with reference to FIG. The water treatment method according to the second embodiment has the same configuration as that in the first embodiment described above except that the reduction treatment means 4 is provided after the biological treatment means 2 and before the primary pure water apparatus 3.

このような構成を採用することにより、上述した第一の実施形態において、塩素系酸化剤(次亜塩素酸等)を使用し、余剰塩素が存在する場合には、これらがアンモニア性の窒素源と反応して結合塩素化合物となる。この結合塩素化合物は、遊離塩素と比較して酸化力は低いものの、後段の一次純水装置3等において、これらの構成要素の部材の酸化劣化を引き起こす可能性があるが、還元処理を施すことによりこれら結合塩素化合物を無害化することができる。   By adopting such a configuration, in the first embodiment described above, when a chlorine-based oxidizing agent (such as hypochlorous acid) is used and surplus chlorine is present, these are ammoniacal nitrogen sources. Reacts with bound chlorine compounds. Although this bonded chlorine compound has lower oxidizing power than free chlorine, it may cause oxidative deterioration of the components of these components in the primary deionized water device 3 etc. in the latter stage, but it should be reduced. Thus, these bonded chlorine compounds can be rendered harmless.

なお、生物処理手段2の生物担持担体の固定床として活性炭を用いた場合、活性炭は塩素系酸化剤を触媒反応により還元処理できることが知られているが、結合塩素化合物を迅速に還元できないためにリークし易く、後段の一次純水装置3まで残存し影響する可能性があることから、活性炭を用いる場合であっても、還元処理手段4を設けるのが好ましい。   In addition, when activated carbon is used as the fixed bed of the biological support carrier of the biological treatment means 2, it is known that activated carbon can reduce the chlorine-based oxidant by catalytic reaction, but it cannot rapidly reduce the bound chlorine compound. Even if activated carbon is used, it is preferable to provide the reduction treatment means 4 because it easily leaks and may remain and affect the subsequent primary pure water device 3.

上記還元処理手段4としては、例えば、水素ガス等の気体;二酸化硫黄等の低級酸化物;チオ硫酸塩、亜硫酸塩、重亜硫酸塩、亜硝酸塩等の低級酸素酸塩;鉄(II)塩等の低原子価金属塩;ギ酸、シュウ酸、L−アスコルビン酸等の有機酸又はその塩;ヒドラジン、アルデヒド類、糖類等のその他の還元剤を添加すればよい。これらの中で、亜硝酸塩、亜硫酸塩、鉄(II)塩、二酸化硫黄、重亜硫酸塩、又はシュウ酸、L−アスコルビン酸若しくはそれらの塩を好適に用いることができる。また、還元処理手段4として、活性炭塔を設けて、活性炭によりさらに還元してもよい。   Examples of the reduction treatment means 4 include gases such as hydrogen gas; lower oxides such as sulfur dioxide; lower oxyacid salts such as thiosulfate, sulfite, bisulfite and nitrite; iron (II) salt and the like. Low-valent metal salts of organic acids such as formic acid, oxalic acid and L-ascorbic acid or salts thereof; other reducing agents such as hydrazine, aldehydes and saccharides may be added. Among these, nitrite, sulfite, iron (II) salt, sulfur dioxide, bisulfite, oxalic acid, L-ascorbic acid or a salt thereof can be preferably used. Further, as the reduction treatment means 4, an activated carbon tower may be provided and further reduction may be performed with activated carbon.

還元剤を添加する場合、還元剤の添加量は、酸化剤濃度に応じて適宜調整するのが好ましい。例えば、還元剤として亜硫酸ナトリウムを用い残留塩素を還元する場合、亜硫酸イオン(SO 2−)と次亜塩素酸イオン(ClO)とが当モルとなるように添加すればよく、安全率を考慮し1.2〜3.0倍量を添加すればよい。処理水の酸化剤濃度には変動があることから、より好ましくは、処理水の酸化剤濃度を監視し、酸化剤濃度に応じ還元剤添加量を制御することが好ましい。また、簡易的には、定期的に酸化剤濃度を測定し、測定濃度に応じた添加量を適宜設定する方法を用いてもよい。なお、酸化剤濃度の検出手段としては、酸化還元電位(ORP)、また残留塩素に関しては残留塩素計(ポーラログラフ法等)が挙げられる。 When adding a reducing agent, it is preferable to adjust the addition amount of a reducing agent suitably according to an oxidizing agent density | concentration. For example, when residual chlorine is reduced using sodium sulfite as a reducing agent, sulfite ions (SO 3 2− ) and hypochlorite ions (ClO ) may be added in equimolar amounts, and the safety factor is increased. In consideration, 1.2 to 3.0 times the amount may be added. Since there is a fluctuation in the oxidizing agent concentration of the treated water, it is more preferable to monitor the oxidizing agent concentration of the treating water and control the reducing agent addition amount according to the oxidizing agent concentration. For simplicity, a method may be used in which the oxidant concentration is measured periodically and the addition amount corresponding to the measured concentration is set appropriately. Examples of means for detecting the oxidant concentration include an oxidation-reduction potential (ORP) and a residual chlorine meter (such as a polarographic method) for residual chlorine.

次に、本発明の一実施形態に係る水処理方法を利用した超純水製造方法について、図3を参照して説明する。本実施形態における超純水製造方法では、原水Wを、前処理システム11、生物処理手段12、菌体分離手段13、還元処理手段14で処理した後、処理水W1を一次純水装置15及びサブシステム(二次純水装置)19でさらに処理する。なお、菌体分離手段13としては、濾過器、カートリッジフィルタ、精密濾過膜分離装置、限外濾過膜分離装置等を用いることができる。   Next, an ultrapure water production method using the water treatment method according to an embodiment of the present invention will be described with reference to FIG. In the ultrapure water production method according to the present embodiment, the raw water W is treated by the pretreatment system 11, the biological treatment means 12, the fungus body separation means 13, and the reduction treatment means 14, and then the treated water W1 is treated with the primary pure water device 15 and Further processing is performed by a subsystem (secondary pure water device) 19. As the bacterial cell separation means 13, a filter, a cartridge filter, a microfiltration membrane separation device, an ultrafiltration membrane separation device, or the like can be used.

一次純水装置15は、第1の逆浸透膜(RO)分離装置16と、第2の逆浸透膜(RO)分離装置17と、混床式イオン交換装置18とをこの順に配置してなる。ただし、この一次純水処理システム15の装置構成はこのような構成に制限されるものではなく、例えば、逆浸透膜分離装置、イオン交換処理装置、電気脱イオン交換処理装置、UV酸化処理装置等を適宜組み合わせて構成されていてもよい。   The primary pure water device 15 includes a first reverse osmosis membrane (RO) separation device 16, a second reverse osmosis membrane (RO) separation device 17, and a mixed bed ion exchange device 18 arranged in this order. . However, the device configuration of the primary pure water treatment system 15 is not limited to such a configuration. For example, a reverse osmosis membrane separation device, an ion exchange treatment device, an electrodeionization exchange treatment device, a UV oxidation treatment device, etc. May be combined as appropriate.

サブシステム19は、サブタンク20と、熱交換器21と、低圧紫外線酸化装置22と、混床式イオン交換装置23と、UF膜分離装置24とをこの順に配置してなる。ただし、このサブシステム19の装置構成はこのような構成に制限されるものではなく、例えば、脱気処理装置、UV酸化処理装置、イオン交換処理装置(非再生式)、限外濾過膜処理装置(微粒子除去)等を組み合わせて構成されていてもよい。   The sub-system 19 includes a sub-tank 20, a heat exchanger 21, a low-pressure ultraviolet oxidizer 22, a mixed bed ion exchanger 23, and a UF membrane separator 24 in this order. However, the apparatus configuration of the subsystem 19 is not limited to such a configuration. For example, a degassing apparatus, a UV oxidation apparatus, an ion exchange apparatus (non-regenerative type), an ultrafiltration membrane apparatus (Particle removal) or the like may be combined.

このような超純水製造システムによる超純水製造方法を以下に説明する。まず、前処理システム11は、凝集、加圧浮上(沈殿)、濾過(膜濾過)装置等よりなる。この前処理システム11において、原水中の懸濁物質やコロイド物質が除去される。また、この前処理システム11では高分子系有機物、疎水性有機物等の除去も可能である。   An ultrapure water production method using such an ultrapure water production system will be described below. First, the pretreatment system 11 includes agglomeration, pressurized flotation (precipitation), filtration (membrane filtration) apparatus, and the like. In the pretreatment system 11, suspended substances and colloidal substances in the raw water are removed. The pretreatment system 11 can also remove high molecular organic substances, hydrophobic organic substances, and the like.

この前処理システム11からの流出水に、アンモニア性の窒素源(NH−N)を添加し、必要に応じさらに酸化剤及び/又は殺菌剤を添加し、生物処理手段12により上述した生物処理が行われる。この生物処理手段12の下流側に設置された菌体分離手段13では、生物処理手段12から流出する微生物や担体微粒子等を分離除去する。この菌体分離手段13は省略してもよい。生物処理手段12の流出水には、上述したように結合塩素化合物が含まれていることがあるため、還元処理手段14により、結合塩素化合物を無害化する。原水W中の塩素系酸化剤の濃度がほとんどない場合には、生物処理手段12の流出水中にも結合塩素化合物がほとんど含まれないので、還元処理手段14における還元剤の添加を省略してもよい。 To the effluent from this pretreatment system 11, an ammoniacal nitrogen source (NH 3 —N) is added, and if necessary, an oxidizing agent and / or a bactericidal agent is further added. Is done. The bacterial cell separation means 13 installed on the downstream side of the biological treatment means 12 separates and removes microorganisms, carrier fine particles, and the like flowing out from the biological treatment means 12. This microbial cell separation means 13 may be omitted. Since the effluent water of the biological treatment means 12 may contain a bound chlorine compound as described above, the reduced chlorine means detoxifies the bound chlorine compound. When there is almost no concentration of the chlorine-based oxidizing agent in the raw water W, since the bound chlorine compound is hardly contained in the effluent of the biological treatment means 12, the addition of the reducing agent in the reduction treatment means 14 can be omitted. Good.

一次純水処理装置15では、第1の逆浸透(RO)膜分離装置16と、第2の逆浸透(RO)膜分離装置17と、混床式イオン交換装置18とにより、生物処理手段12の処理水W1中に残存するイオン成分等を除去する。   In the primary pure water treatment device 15, the first reverse osmosis (RO) membrane separation device 16, the second reverse osmosis (RO) membrane separation device 17, and the mixed bed ion exchange device 18 are used to treat the biological treatment means 12. The ionic component remaining in the treated water W1 is removed.

さらに、サブシステム19では、一次純水装置15の処理水をサブタンク20及び熱交換器21を経て低圧紫外線酸化装置22に導入し、含有されるTOC成分をイオン化又は分解する。このうち、イオン化された有機物は、後段の混床式イオン交換装置23で除去される。この混床式イオン交換装置23の処理水は更にUF膜分離装置24で膜分離処理され、超純水を得ることができる。   Further, in the sub-system 19, the treated water of the primary pure water device 15 is introduced into the low-pressure ultraviolet oxidizer 22 through the sub-tank 20 and the heat exchanger 21, and the contained TOC component is ionized or decomposed. Among these, the ionized organic matter is removed by the mixed bed ion exchanger 23 at the subsequent stage. The treated water of the mixed bed type ion exchange device 23 is further subjected to membrane separation treatment by the UF membrane separation device 24, and ultrapure water can be obtained.

上述したような超純水製造方法によると、生物処理手段12において、尿素を十分に分解除去し、その後段の一次純水装置15及びサブシステム19でその他のTOC成分、金属イオン、その他の無機・有機イオン成分を除去することにより、高純度の超純水を効率よく製造することができる。   According to the method for producing ultrapure water as described above, the biological treatment means 12 sufficiently decomposes and removes urea, and the TOC component, metal ions, and other inorganic substances in the primary pure water device 15 and the subsystem 19 in the subsequent stage. -By removing the organic ion component, highly pure ultrapure water can be efficiently produced.

また、上記超純水製造方法によれば、原水Wを生物処理手段12に導入する前に前処理システム11に導入して原水W中の濁質を除去している。このため、生物処理手段12での尿素の分解除去効率が濁質のために低下することが防止されるとともに、濁質によって生物処理手段12の圧力損失が増加することが抑制される。また、この超純水製造方法によると、生物処理手段12の下流側に菌体分離手段13、一次純水システム15及びサブシステム19が設けられているため、生物処理手段12から流出する生物又は担体を、これら菌体分離手段13、一次純水システム15及びサブシステム19によって良好に除去することができる、という効果も奏する。   Moreover, according to the said ultrapure water manufacturing method, before introducing raw | natural water W into the biological treatment means 12, it introduce | transduces into the pre-processing system 11 and removes the turbidity in the raw | natural water W. For this reason, the decomposition and removal efficiency of urea in the biological treatment means 12 is prevented from decreasing due to turbidity, and an increase in pressure loss of the biological treatment means 12 due to the turbidity is suppressed. Moreover, according to this ultrapure water production method, since the bacterial cell separation means 13, the primary pure water system 15 and the subsystem 19 are provided on the downstream side of the biological treatment means 12, organisms flowing out from the biological treatment means 12 or There is also an effect that the carrier can be satisfactorily removed by the cell separation means 13, the primary pure water system 15, and the subsystem 19.

以下の実施例により本発明をさらに詳細に説明する。   The following examples illustrate the invention in more detail.

〔実施例1〕
図1に示すフローを用いて、市水(野木町水:平均尿素濃度10μg/L、平均TOC濃度500μg/L)に試薬尿素(キシダ化学社製)を必要に応じ添加したものを用いた。
[Example 1]
Using the flow shown in FIG. 1, a city water (Nogi-cho water: average urea concentration 10 μg / L, average TOC concentration 500 μg / L) to which reagent urea (manufactured by Kishida Chemical Co., Ltd.) was added as needed was used.

また、生物処理手段2としては、生物担体としての粒状活性炭(「クリコール WG160、10/32メッシュ」、栗田工業社製)を円筒容器に10L充填して固定床としたものを用いた。なお、生物処理手段2の粒状活性炭としては新炭を用いた。   Further, as the biological treatment means 2, granular activated carbon (“Crycol WG160, 10/32 mesh”, manufactured by Kurita Kogyo Co., Ltd.) as a biological carrier was filled into a cylindrical container and used as a fixed bed. In addition, new charcoal was used as the granular activated carbon of the biological treatment means 2.

まず、市水(試薬尿素無添加)に対し、尿素を濃度が約500μg/Lとなるように添加して原水Wを調製し、この原水Wを生物処理手段2に下向流にて通水した。通水速度SVは20/hr(毎時通水流量÷充填活性炭量)とした。通水後の生物処理水について、70日間にわたり尿素濃度の分析を行った。その結果を図4に示す。なお、上記通水処理においては、1日1回、10分間の逆洗を実施した。逆洗は、生物処理水にて、円筒容器下部から上部の上向流にて、LV=25m/hr(毎時通水流量÷円筒容器断面積)にて実施した。   First, raw water W is prepared by adding urea to a city water (no reagent urea added) so as to have a concentration of about 500 μg / L, and this raw water W is passed through the biological treatment means 2 in a downward flow. did. The water flow rate SV was 20 / hr (water flow rate per hour ÷ filled activated carbon amount). The biologically treated water after passing through was analyzed for urea concentration over 70 days. The result is shown in FIG. In the water flow treatment, back washing was performed once a day for 10 minutes. Backwashing was performed with biologically treated water in an upward flow from the lower part of the cylindrical container to LV = 25 m / hr (per hour water flow rate ÷ cylinder container sectional area).

尿素濃度の分析の手順は以下の通りである。すなわち、まず、検水の全残留塩素濃度をDPD法にて測定し、相当量の重亜硫酸ナトリウムで還元処理する(その後、DPD法にて全残留塩素を測定して、0.02mg/L未満であることを確認する。)。次に、この還元処理した検水をイオン交換樹脂(「KR−UM1」、栗田工業社製)にSV50/hrで通水し、脱イオン処理してロータリーエバポレータにて10〜100倍に濃縮した後、ジアセチルモノオキシム法にて尿素濃度を定量する。   The procedure for analyzing the urea concentration is as follows. That is, first, the total residual chlorine concentration of the test water is measured by the DPD method and reduced with a considerable amount of sodium bisulfite (then, the total residual chlorine is measured by the DPD method, and less than 0.02 mg / L). Confirm that it is.) Next, this reduced test water was passed through an ion exchange resin (“KR-UM1”, Kurita Kogyo Co., Ltd.) at SV50 / hr, deionized, and concentrated 10 to 100 times with a rotary evaporator. Thereafter, the urea concentration is quantified by the diacetyl monooxime method.

なお、通水試験期間中にpH調整は実施しなかった。試験期間中のpHは6.8〜7.5であった。また、試験期間中の市水の水温は15℃未満であったため、生物処理手段2の前段に温度調節槽を配し、水温を20〜22℃に昇温し、生物処理手段2に給水した。さらに、試験期間中の原水Wの溶存酸素(DO)濃度は6mg/L以上、生物処理手段2の処理水W1の溶存酸素濃度は2mg/L以上であったため、溶存酸素不足はないと判断し、溶存酸素濃度の調節は実施しなかった。   In addition, pH adjustment was not implemented during the water flow test period. The pH during the test period was 6.8-7.5. Moreover, since the water temperature of the city water during the test period was less than 15 ° C., a temperature control tank was arranged in front of the biological treatment means 2, the water temperature was raised to 20-22 ° C., and the biological treatment means 2 was supplied with water. . Furthermore, since the dissolved oxygen (DO) concentration of the raw water W during the test period was 6 mg / L or more and the dissolved oxygen concentration of the treated water W1 of the biological treatment means 2 was 2 mg / L or more, it was determined that there was no shortage of dissolved oxygen. The dissolved oxygen concentration was not adjusted.

図4から明らかなように、アンモニア性の窒素源を添加しない通水開始から通水25日目までは、給水と生物処理水との尿素濃度はほぼ同値(約500μg/L)で、尿素の除去は認められなかった。   As is clear from FIG. 4, from the start of water flow without adding an ammoniacal nitrogen source to the 25th day of water flow, the urea concentrations in the feed water and the biologically treated water are almost the same (about 500 μg / L). Removal was not observed.

次に、通水開始から25日目に、原水Wに対して、アンモニア性の窒素源として塩化アンモニウム(キシダ化学社製)を、アンモニウムイオン濃度が約1mg/L(NH 換算)となるように添加を開始した。 Next, on the 25th day from the start of water flow, ammonium chloride (manufactured by Kishida Chemical Co.) is used as the ammoniacal nitrogen source with respect to the raw water W, and the ammonium ion concentration becomes about 1 mg / L (converted to NH 4 + ). The addition was started as follows.

その結果、通水開始から30日目には尿素の除去効果が確認でき、通水の継続に伴い尿素の除去性能が向上し、通水開始から40日目(塩化アンモニウム添加開始より約2週間後)には生物処理水の尿素濃度2μg/L以下を達成した。   As a result, the urea removal effect can be confirmed on the 30th day from the start of the water flow, and the urea removal performance is improved with the continuation of the water flow. The 40th day from the start of the water flow (about 2 weeks from the start of the ammonium chloride addition) After), the urea concentration of biologically treated water was 2 μg / L or less.

その後も生物処理水の尿素濃度2μg/L以下を維持したので、通水開始から55日目には塩化アンモニウムの添加を停止し、通水開始から62日目には給水尿素濃度を500μg/Lから100μg/Lに変更したが、生物処理水の尿素濃度2μg/L以下で変化は認められなかった。これは、塩化アンモニウムの添加により菌体が増殖し又はその活性が向上したが、塩化アンモニウム添加停止後であってもその菌数及び活性を維持できている結果であると考えられる。このことから、塩化アンモニウムを代表とするアンモニア性の窒素源の添加が、例えば立上げ時のみ又は間欠的であっても十分に効果が得られると推測される。   After that, since the urea concentration of biologically treated water was maintained at 2 μg / L or less, addition of ammonium chloride was stopped on the 55th day from the start of water flow, and the feed water urea concentration was 500 μg / L on the 62nd day from the start of water flow. However, no change was observed at a urea concentration of 2 μg / L or less in biologically treated water. This is considered to be a result of maintaining the number and activity of the cells even after the ammonium chloride addition was stopped, although the bacterial cells grew or the activity was improved by the addition of ammonium chloride. From this, it is presumed that the addition of an ammoniacal nitrogen source typified by ammonium chloride can provide a sufficient effect even at the time of start-up only or intermittently.

〔実施例2〕
実施例1において、生物処理手段2として、試薬尿素にて馴養を実施し、給水尿素100μg/Lに対して、生物処理水の尿素が2μg/L以下となるように尿素分解能が既に発現しているものを用いた以外は、実施例1と同様に通水試験を行い、70日間にわたり尿素濃度の分析を行った。その結果を図4にあわせて示す。
[Example 2]
In Example 1, the biological treatment means 2 was conditioned with reagent urea, and urea resolution was already expressed so that urea of biological treatment water was 2 μg / L or less with respect to 100 μg / L of feed water urea. A water flow test was conducted in the same manner as in Example 1 except that those used were used, and the urea concentration was analyzed over 70 days. The results are also shown in FIG.

図4から明らかなように、通水開始から通水4日目以降、処理水W1の尿素濃度は若干低下傾向が認められるものの、350μg/L前後で推移していた。   As is clear from FIG. 4, the urea concentration of the treated water W <b> 1 changed slightly around 350 μg / L after the fourth day from the start of water flow, although a slight tendency to decrease was observed.

そして、通水開始から40日目以降、実施例1と同条件にて、塩化アンモニウムの添加を開始した。   Then, from the 40th day after the start of water flow, addition of ammonium chloride was started under the same conditions as in Example 1.

その結果、通水開始から50日目(塩化アンモニウム添加開始より10日後)には生物処理水の尿素濃度2μg/L以下を達成した。   As a result, the urea concentration of biologically treated water was 2 μg / L or less on the 50th day from the start of water flow (10 days after the start of ammonium chloride addition).

その後も生物処理水の尿素濃度2μg/L以下を維持したので、通水開始から55日目には塩化アンモニウムの添加を停止し、通水開始から62日目には給水尿素濃度を500μg/Lから100μg/Lに変更したが、生物処理水の尿素濃度2μg/L以下で変化は認められなかった。   After that, since the urea concentration of biologically treated water was maintained at 2 μg / L or less, addition of ammonium chloride was stopped on the 55th day from the start of water flow, and the feed water urea concentration was 500 μg / L on the 62nd day from the start of water flow. However, no change was observed at a urea concentration of 2 μg / L or less in biologically treated water.

これらの実施例1及び実施例2の結果から、アンモニア性の窒素源の添加により、原水W中の尿素を除去することができることが確認された。   From the results of Example 1 and Example 2, it was confirmed that urea in the raw water W could be removed by adding an ammoniacal nitrogen source.

1…給水槽
2…生物処理手段
3…一次純水装置
4…還元処理手段
12…生物処理手段
14…還元処理手段
15…一次純水装置
19…サブシステム(二次純水装置)
W…原水
W1…処理水
DESCRIPTION OF SYMBOLS 1 ... Water tank 2 ... Biological treatment means 3 ... Primary pure water apparatus 4 ... Reduction treatment means 12 ... Biological treatment means 14 ... Reduction treatment means 15 ... Primary pure water apparatus 19 ... Subsystem (secondary pure water apparatus)
W ... Raw water W1 ... treated water

Claims (5)

尿素を含有する原水から生物処理により尿素を除去する水処理方法において、
原水にアンモニア性の窒素源を添加した後、生物処理を行うことを特徴とする水処理方法。
In a water treatment method for removing urea by biological treatment from raw water containing urea ,
A water treatment method comprising performing biological treatment after adding an ammoniacal nitrogen source to raw water.
生物担持担体を有する生物処理手段により前記生物処理を行うことを特徴とする請求項1に記載の水処理方法。   The water treatment method according to claim 1, wherein the biological treatment is performed by a biological treatment means having a biological carrier. 前記アンモニア性の窒素源が、アンモニウム塩であることを特徴とする請求項1又は2に記載の水処理方法。   The water treatment method according to claim 1 or 2, wherein the ammoniacal nitrogen source is an ammonium salt. 前記生物処理の後段において還元処理を行うことを特徴とする請求項1〜3のいずれか1項に記載の水処理方法。   The water treatment method according to any one of claims 1 to 3, wherein a reduction treatment is performed after the biological treatment. 請求項1〜4のいずれか1項に記載の水処理方法で得られた処理水を一次純水装置及び二次純水装置で処理して超純水を製造することを特徴とする超純水製造方法。   Ultrapure water characterized by producing ultrapure water by treating the treated water obtained by the water treatment method according to any one of claims 1 to 4 with a primary pure water device and a secondary pure water device. Water production method.
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