JP6565966B2 - Water treatment method - Google Patents

Water treatment method Download PDF

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JP6565966B2
JP6565966B2 JP2017082942A JP2017082942A JP6565966B2 JP 6565966 B2 JP6565966 B2 JP 6565966B2 JP 2017082942 A JP2017082942 A JP 2017082942A JP 2017082942 A JP2017082942 A JP 2017082942A JP 6565966 B2 JP6565966 B2 JP 6565966B2
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JP2018176116A (en
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勝郎 依田
勝郎 依田
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Kurita Water Industries Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
    • B01D61/04—Feed pretreatment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
    • B01D61/12—Controlling or regulating
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/50—Treatment of water, waste water, or sewage by addition or application of a germicide or by oligodynamic treatment

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  • Chemical & Material Sciences (AREA)
  • Water Supply & Treatment (AREA)
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  • Treatment Of Water By Oxidation Or Reduction (AREA)
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Description

本発明は水処理方法に係り、詳しくは、海水淡水化用逆浸透膜（ＲＯ膜）装置等の水処理装置におけるバイオファウリングを抑制する水処理方法に関する。   The present invention relates to a water treatment method, and more particularly to a water treatment method for suppressing biofouling in a water treatment device such as a reverse osmosis membrane (RO membrane) device for seawater desalination.

工業用水、市水、井水、海水、河川水、湖沼水、工場廃水などを水処理して純水等を製造する手段として、ＲＯ膜装置が広く利用されている。この場合、これらの被処理水に含まれる微生物によるバイオファウリングを抑制するために、塩素、次亜塩素酸ナトリウム、亜塩素酸ナトリウム等の塩素系酸化剤が被処理水（供給水）に添加される。また、電気分解により塩素を生成させることも行われている。   RO membrane devices are widely used as means for producing pure water by treating industrial water, city water, well water, seawater, river water, lake water, factory wastewater, and the like. In this case, chlorine-based oxidizing agents such as chlorine, sodium hypochlorite, and sodium chlorite are added to the treated water (feed water) in order to suppress biofouling by microorganisms contained in these treated water. Is done. In addition, chlorine is also generated by electrolysis.

塩素系酸化剤の添加や電気分解により遊離塩素を存在させた水をＲＯ膜処理すると、ＲＯ膜が酸化劣化を受ける。特にポリアミド系のＲＯ膜では酸化劣化し易い。このため、従来、ＲＯ膜装置の前段に活性炭塔を設置して塩素等の残留酸化剤を除去するか（特許文献１）、ＲＯ膜装置の前段で亜硫酸水素ナトリウム（ＳＢＳ）や亜硫酸ナトリウムなどの還元剤を添加して塩素を分解除去する（特許文献２）等の処理がなされている。   When RO membrane treatment is performed on water in which free chlorine is present by addition of a chlorine-based oxidant or electrolysis, the RO membrane undergoes oxidative degradation. In particular, polyamide-based RO membranes are susceptible to oxidative degradation. For this reason, conventionally, an activated carbon tower is installed in the front stage of the RO membrane apparatus to remove residual oxidizers such as chlorine (Patent Document 1), or sodium bisulfite (SBS), sodium sulfite, etc. are used in the front stage of the RO membrane apparatus. Treatments such as adding a reducing agent to decompose and remove chlorine (Patent Document 2) have been performed.

ただし、活性炭塔を設置した場合、塔内でバイオファウリングが発生して後段装置を汚染することがある、イニシャルコストがかかる、などの欠点があり、一般的には還元剤の添加による残留酸化剤の分解除去が行われている。   However, when an activated carbon tower is installed, there are disadvantages such as biofouling occurring in the tower and contamination of the subsequent equipment, and it costs initial cost. Generally, residual oxidation is caused by the addition of a reducing agent. The agent is decomposed and removed.

図２は、従来の海水淡水化設備の一例を示す系統図であり、塩素系酸化剤の添加による図２（ａ）では、海水が送水ポンプにより原水槽１に送給される過程で次亜塩素酸ナトリウム（ＮａＣｌＯ）等の塩素系酸化剤が添加され、その後、原水槽１から反応槽２に送給される過程で塩化第二鉄（ＦｅＣｌ３）等の無機凝集剤が添加されて反応槽２で凝集処理され、次いで二層濾過器３で濾過された後、給水槽４、保安フィルター５を経てＲＯ膜装置６でＲＯ膜処理され、ＲＯ膜透過水が処理水として取り出されるが、保安フィルター５の入口側では、残留酸化剤を分解除去するために、亜硫酸水素ナトリウム（ＳＢＳ）等の還元剤が添加される。電気分解による図２（ｂ）では、海水が電解装置７で電気分解され、電気分解で生成した塩素を含む海水が原水槽１を経て、図２（ａ）におけると同様に凝集、濾過された後、ＳＢＳ等の還元剤が添加されてＲＯ膜装置６で処理される。
なお、この還元剤の添加により、供給水中に遊離塩素が存在しなくなる結果、ＲＯ膜装置にバイオファウリングが起こることを防止するために、還元剤の添加後、ＲＯ膜に対する劣化影響の少ない結合塩素系スライムコントロール剤（例えば栗田工業（株）製「クリバーターＩＫ−１１０」）が添加される場合もある。 FIG. 2 is a system diagram showing an example of a conventional seawater desalination facility. In FIG. 2 (a) with the addition of a chlorinated oxidant, seawater is fed into the raw water tank 1 by a water pump. Chlorine oxidant such as sodium chlorate (NaClO) is added, and then inorganic flocculant such as ferric chloride (FeCl 3 ) is added and reacted in the process of being fed from raw water tank 1 to reaction tank 2 After being agglomerated in the tank 2 and then filtered through the two-layer filter 3, the RO membrane device 6 is subjected to RO membrane treatment through the water supply tank 4 and the safety filter 5, and the RO membrane permeated water is taken out as treated water. On the inlet side of the safety filter 5, a reducing agent such as sodium bisulfite (SBS) is added to decompose and remove the residual oxidant. In FIG. 2 (b) by electrolysis, seawater was electrolyzed by the electrolyzer 7, and seawater containing chlorine produced by electrolysis was aggregated and filtered through the raw water tank 1 as in FIG. 2 (a). Thereafter, a reducing agent such as SBS is added and processed by the RO membrane device 6.
In order to prevent biofouling from occurring in the RO membrane device as a result of the elimination of free chlorine in the supply water by the addition of this reducing agent, the binding with less degradation effect on the RO membrane after the addition of the reducing agent. A chlorine-based slime control agent (for example, “Kuriverter IK-110” manufactured by Kurita Kogyo Co., Ltd.) may be added.

特開平１０−３３７５６３号公報Japanese Patent Laid-Open No. 10-337563 特開平７−３０８６７１号公報JP-A-7-308671

上記従来の海水淡水化ＲＯ膜処理では、次のような問題があった。
（１） 次亜塩素酸ナトリウム等の塩素系酸化剤の添加や海水の電気分解で生成した遊離塩素は、海水中の有機物や、臭素、ヨウ素により分解され易いため、分解分を補ってバイオファウリング抑制効果を十分に得るための薬品添加量や消費電力量が多い。
（２） 海水に塩素系酸化剤を添加すると、有害なトリハロメタン等の有機塩素化合物が生成するため、特に飲料水用途では問題となる。
（３） ＲＯ膜の酸化劣化の防止のために、ＲＯ膜の入口側で還元剤の添加や活性炭塔設置による処理が必要となり、処理が複雑である。
（４） ＲＯ膜装置の前段で還元剤の添加や活性炭処理で遊離塩素を除去してしまうため、ＲＯ膜装置におけるバイオファウリングの抑制が不十分である。
（５） ＲＯ膜装置の入口で結合塩素系スライムコントロール剤を添加することにより、上記（４）の問題を解決することができるが、この場合には、更に添加する薬剤が増えることになる。 The conventional seawater desalination RO membrane treatment has the following problems.
(1) Free chlorine produced by the addition of chlorinated oxidants such as sodium hypochlorite and electrolysis of seawater is easily decomposed by organic matter, bromine and iodine in seawater. There are many chemical additions and power consumption to obtain a sufficient ring suppression effect.
(2) Addition of a chlorinated oxidant to seawater produces harmful organic chlorinated compounds such as trihalomethane, which is particularly problematic for drinking water applications.
(3) In order to prevent oxidative degradation of the RO membrane, it is necessary to add a reducing agent or install an activated carbon tower on the RO membrane inlet side, and the treatment is complicated.
(4) Since free chlorine is removed by addition of a reducing agent or activated carbon treatment at the front stage of the RO membrane device, suppression of biofouling in the RO membrane device is insufficient.
(5) The problem of the above (4) can be solved by adding the combined chlorine-based slime control agent at the entrance of the RO membrane device. In this case, however, the amount of the agent to be added further increases.

本発明は上記した従来法の課題を解決する水処理方法を提供することを目的とする。   An object of this invention is to provide the water treatment method which solves the subject of the above-mentioned conventional method.

本発明者は、上記課題を解決すべく、鋭意検討した結果、塩素系酸化剤の添加或いは電気分解による塩素の発生に先立ち、供給水に塩素安定化剤として窒素化合物を添加し、供給水中の塩素を安定化させることにより、塩素の分解やトリハロメタン等の生成を防止することができると共に、遊離塩素濃度の低減でＲＯ膜の酸化劣化を防止することができ、ＲＯ膜入口側での還元剤の添加や活性炭塔の設置を不要とした上で、ＲＯ膜のバイオファウリングを効果的に抑制することが可能となることを見出した。   As a result of intensive studies to solve the above problems, the present inventor added a nitrogen compound as a chlorine stabilizer to the feed water before adding chlorine-based oxidant or generating chlorine by electrolysis, By stabilizing the chlorine, it is possible to prevent the decomposition of chlorine and the generation of trihalomethane, etc., and it is possible to prevent the oxidative deterioration of the RO membrane by reducing the free chlorine concentration, and the reducing agent on the RO membrane inlet side The present inventors have found that it is possible to effectively suppress biofouling of RO membranes without the need for addition of carbon and installation of an activated carbon tower.

即ち、本発明は以下を要旨とする。   That is, the gist of the present invention is as follows.

［１］ 水処理装置への供給水に、塩素系酸化剤を添加するか或いは電気分解で塩素を発生させることにより遊離塩素を存在させた後該水処理装置に供給する水処理方法において、該供給水に遊離塩素を存在させるに先立ち、該供給水に塩素安定化剤として窒素化合物を添加することを特徴とする水処理方法。 [1] In a water treatment method of supplying free water to a water treatment apparatus after adding free chlorine by adding a chlorine-based oxidant to the water supplied to the water treatment apparatus or generating chlorine by electrolysis, A water treatment method characterized by adding a nitrogen compound as a chlorine stabilizer to the feed water prior to the presence of free chlorine in the feed water.

［２］ ［１］において、前記水処理装置が逆浸透膜装置であることを特徴とする水処理方法。 [2] The water treatment method according to [1], wherein the water treatment device is a reverse osmosis membrane device.

［３］ ［１］又は［２］において、前記供給水が海水であることを特徴とする水処理方法。 [3] The water treatment method according to [1] or [2], wherein the supplied water is seawater.

［４］ ［１］ないし［３］のいずれかにおいて、前記窒素化合物がスルファミン酸化合物及び／又は有機窒素化合物であることを特徴とする水処理方法。 [4] The water treatment method according to any one of [1] to [3], wherein the nitrogen compound is a sulfamic acid compound and / or an organic nitrogen compound.

［５］ ［１］ないし［４］のいずれかにおいて、前記塩素系酸化剤として次亜塩素酸塩及び／又はジクロロイソシアヌル酸を前記供給水に添加することを特徴とする水処理方法。 [5] The water treatment method according to any one of [1] to [4], wherein hypochlorite and / or dichloroisocyanuric acid is added to the feed water as the chlorinated oxidant.

［６］ ［１］ないし［５］のいずれかにおいて、前記窒素化合物を前記供給水に０．３〜５０ｍｇ／Ｌ添加することを特徴とする水処理方法。 [6] The water treatment method according to any one of [1] to [5], wherein the nitrogen compound is added to the feed water in an amount of 0.3 to 50 mg / L.

［７］ ［１］ないし［６］のいずれかにおいて、前記遊離塩素を存在させた後の前記供給水の残留塩素濃度を０．１〜１０ｍｇ−Ｃｌ２／Ｌに維持することを特徴とする水処理方法。 [7] In any one of [1] to [6], the residual chlorine concentration of the feed water after the presence of the free chlorine is maintained at 0.1 to 10 mg-Cl 2 / L. Water treatment method.

本発明によれば、塩素系酸化剤の添加或いは電気分解による塩素の発生に先立ち、供給水に塩素安定化剤として窒素化合物を添加し、その後、供給水中に添加又は生成させた遊離塩素を安定化させることにより、塩素の分解やトリハロメタン等の有害物質の生成を防止することができる。また、塩素を安定化塩素として供給水中に存在させ、遊離塩素濃度を低減することにより、供給水のＲＯ膜酸化劣化性が低減されるため、ＲＯ膜入口側での還元剤の添加や活性炭塔の設置を不要とすることができ、処理を簡素化することができると共に、安定化塩素によりＲＯ膜装置におけるバイオファウリングを効果的に抑制することが可能となる。   According to the present invention, prior to the addition of a chlorine-based oxidant or generation of chlorine by electrolysis, a nitrogen compound is added to the feed water as a chlorine stabilizer, and then the free chlorine added or generated in the feed water is stabilized. By making them, decomposition of chlorine and generation of harmful substances such as trihalomethane can be prevented. In addition, the presence of chlorine as stabilized chlorine in the feed water and the reduction of free chlorine concentration reduces the RO membrane oxidation degradation of the feed water, so the addition of a reducing agent on the RO membrane inlet side and the activated carbon tower Installation can be made unnecessary, the processing can be simplified, and biofouling in the RO membrane device can be effectively suppressed by the stabilized chlorine.

本発明の水処理方法の実施の形態の一例を示す海水淡水化設備の系統図である。It is a systematic diagram of the seawater desalination equipment which shows an example of embodiment of the water treatment method of this invention. 従来の海水淡水化設備の系統図である。It is a systematic diagram of the conventional seawater desalination equipment. 実験例１の結果を示すグラフである。6 is a graph showing the results of Experimental Example 1. 実験例２の結果を示すグラフである。10 is a graph showing the results of Experimental Example 2. 実験例３の結果を示すグラフである。10 is a graph showing the results of Experimental Example 3. 実験例４の結果を示すグラフである。10 is a graph showing the results of Experimental Example 4. 実験例５の結果を示すグラフである。10 is a graph showing the results of Experimental Example 5. 実験例６の結果を示すグラフである。10 is a graph showing the results of Experimental Example 6. 比較実験例１の結果を示すグラフである。6 is a graph showing the results of Comparative Experimental Example 1.

以下に図面を参照して本発明の実施の形態を詳細に説明する。   Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

図１（ａ），（ｂ）は、本発明の水処理方法を適用した海水の淡水化設備の一例を示す系統図であり、それぞれ、図２（ａ），（ｂ）に示す海水の淡水化設備と同一機能を奏する部材に同一符号を付してある。
図１（ａ），（ｂ）に示すように、本発明の水処理方法は、次亜塩素酸ナトリウム（ＮａＣｌＯ）等の塩素系酸化剤の添加又は電気分解による塩素の発生に先立ち、塩素安定化剤として窒素化合物を供給水に添加して供給水中の塩素を安定化させることを特徴とする。 1 (a) and 1 (b) are system diagrams showing an example of seawater desalination equipment to which the water treatment method of the present invention is applied. Seawater fresh water shown in FIGS. 2 (a) and 2 (b), respectively. The members having the same functions as those of the control equipment are denoted by the same reference numerals.
As shown in FIGS. 1 (a) and 1 (b), the water treatment method of the present invention provides chlorine stabilization prior to generation of chlorine by addition of a chlorine-based oxidizing agent such as sodium hypochlorite (NaClO) or by electrolysis. A nitrogen compound is added to the feed water as an agent to stabilize chlorine in the feed water.

塩素の安定化のために添加する窒素化合物としては、供給水中の塩素を安定化結合塩素又は活性化結合塩素として安定化することができるものであればよく、特に制限はないが、例えばスルファミン酸、スルファミン酸のナトリウム塩、カリウム塩、カルシウム塩、アンモニウム塩等のスルファミン酸化合物、グリシン、タウリン、トレオニン、オルニチン（Ｌオルニチン）、アラニン、フェニルアラニン（Ｌフェニルアラニン）等の有機窒素化合物が挙げられる。これらの窒素化合物は１種のみを用いてもよく、２種以上を併用してもよい。   The nitrogen compound added to stabilize the chlorine is not particularly limited as long as it can stabilize the chlorine in the feed water as stabilized bonded chlorine or activated bonded chlorine. For example, sulfamic acid Sulfamic acid compounds such as sodium salt, potassium salt, calcium salt and ammonium salt of sulfamic acid, and organic nitrogen compounds such as glycine, taurine, threonine, ornithine (L-ornithine), alanine and phenylalanine (L-phenylalanine). These nitrogen compounds may use only 1 type and may use 2 or more types together.

供給水へのこれらの窒素化合物の添加量は、用いる窒素化合物の種類、その後段で添加する塩素系酸化剤の添加量、電気分解により発生させる塩素量、それにより供給水中に維持すべき塩素濃度等によっても異なるが、０．３〜５０ｍｇ／Ｌ、特に０．３〜２０ｍｇ／Ｌ程度とすることが好ましい。窒素化合物の添加量が少な過ぎると、供給水中の塩素を十分に安定化することができず、多過ぎても処理コストが高くなったり、ファウリングの原因となり不適切である。   The amount of these nitrogen compounds added to the feed water depends on the type of nitrogen compound used, the amount of chlorinated oxidant added in the subsequent stage, the amount of chlorine generated by electrolysis, and the chlorine concentration to be maintained in the feed water. Although it varies depending on the like, it is preferably 0.3 to 50 mg / L, particularly about 0.3 to 20 mg / L. If the amount of the nitrogen compound added is too small, the chlorine in the feed water cannot be sufficiently stabilized, and if it is too large, the treatment cost becomes high or fouling is inappropriate.

本発明においては、塩素安定化剤としての窒素化合物を上記の好適な添加量で添加して、供給水中で窒素化合物が十分に均一に拡散された後に塩素系酸化剤を添加するか電気分解により塩素を発生させることが好ましく、例えば、塩素系酸化剤を添加する場合には、図１（ａ）に示すように、塩素安定化剤としての窒素化合物を送水ポンプの吐出側で添加し、原水槽１で滞留する間に均一化させた後、原水槽１の出口側でＮａＣｌＯ等の塩素系酸化剤をＦｅＣｌ３等の無機凝集剤と共に添加することが好ましい。また、電気分解による場合は、図１（ｂ）に示すように、送水ポンプの吐出側で塩素安定化剤を添加し、電解装置７における電気分解中に均一化させると共に塩素を発生させるようにすることが好ましい。 In the present invention, a nitrogen compound as a chlorine stabilizer is added at the above-mentioned preferable addition amount, and after the nitrogen compound is sufficiently uniformly diffused in the feed water, a chlorine-based oxidant is added or electrolysis is performed. It is preferable to generate chlorine. For example, when adding a chlorine-based oxidizer, a nitrogen compound as a chlorine stabilizer is added on the discharge side of the water pump as shown in FIG. It is preferable to add a chlorine-based oxidizing agent such as NaClO together with an inorganic flocculant such as FeCl 3 on the outlet side of the raw water tank 1 after homogenization while staying in the water tank 1. In the case of electrolysis, as shown in FIG. 1 (b), a chlorine stabilizer is added on the discharge side of the water pump so that it is made uniform during electrolysis in the electrolyzer 7 and chlorine is generated. It is preferable to do.

図１（ａ）に示すように、塩素安定化剤添加後に塩素系酸化剤を添加する場合、塩素系酸化剤としては、従来公知のものをいずれも用いることができるが、製品安全性の観点から、次亜塩素酸ナトリウム等の次亜塩素酸塩、或いはジクロロイソシアヌル酸、ジクロロイソシアヌル酸ナトリウム等のジクロロイソシアヌル酸塩等が好ましく、特に、次亜塩素酸ナトリウム或いはジクロロイソシアヌル酸を用いることが好ましい。これらの塩素系酸化剤は１種のみを用いてもよく、２種以上を併用してもよい。   As shown in FIG. 1 (a), when adding a chlorine-based oxidizing agent after adding a chlorine stabilizer, any conventionally known one can be used as the chlorine-based oxidizing agent, but from the viewpoint of product safety. From these, hypochlorites such as sodium hypochlorite, or dichloroisocyanurates such as dichloroisocyanuric acid and sodium dichloroisocyanurate are preferred, and it is particularly preferable to use sodium hypochlorite or dichloroisocyanuric acid. . These chlorine-based oxidizing agents may be used alone or in combination of two or more.

塩素系酸化剤の添加量は、処理対象水系のバイオファウリングの発生傾向によっても異なるが、通常０．１〜１．０ｍｇ／Ｌ、特に０．３〜０．７ｍｇ／Ｌ程度とすることが好ましく、塩素安定化剤の窒素化合物添加後に塩素系酸化剤を上記範囲で添加することにより、ＲＯ膜装置の入口での残留塩素濃度が０．３〜１．０ｍｇ−Ｃｌ２／Ｌ、特に０．５〜０．７ｍｇ−Ｃｌ２／Ｌ程度となるように制御することが好ましい。ＲＯ膜装置入口での残留塩素濃度が上記下限よりも少ないと十分なバイオファウリング抑制効果を得ることができず、上記上限を超えると残留塩素中の遊離塩素の割合にもよるが、ＲＯ膜劣化のおそれがある。 The amount of the chlorine-based oxidant added is usually 0.1 to 1.0 mg / L, particularly about 0.3 to 0.7 mg / L, although it varies depending on the tendency of biofouling to occur in the water to be treated. Preferably, by adding a chlorine-based oxidizing agent in the above range after adding the nitrogen compound of the chlorine stabilizer, the residual chlorine concentration at the entrance of the RO membrane device is 0.3 to 1.0 mg-Cl 2 / L, particularly 0. It is preferable to control so as to be about 5 to 0.7 mg-Cl 2 / L. If the residual chlorine concentration at the RO membrane device inlet is less than the lower limit, a sufficient biofouling suppression effect cannot be obtained, and if the upper limit is exceeded, the RO membrane depends on the ratio of free chlorine in the residual chlorine. There is a risk of deterioration.

また、電気分解による場合においても、塩素安定化剤の窒素化合物添加後の電気分解による塩素の発生で、ＲＯ膜装置の入口での残留塩素濃度が上記範囲となるように電気分解条件を制御することが好ましい。   Even in the case of electrolysis, the electrolysis conditions are controlled so that the residual chlorine concentration at the entrance of the RO membrane device is within the above range due to the generation of chlorine by electrolysis after addition of the nitrogen compound of the chlorine stabilizer. It is preferable.

特に本発明では、塩素系酸化剤による塩素又は電気分解により生成した塩素を窒素化合物により安定化することで、ＲＯ膜装置入口での残留塩素濃度が上記範囲であって、遊離塩素濃度は０．１ｍｇ−Ｃｌ２／Ｌ以下、特に０．０５ｍｇ−Ｃｌ２／Ｌ以下となるように制御することで、遊離塩素によるＲＯ膜の酸化劣化を防止した上でバイオファウリング抑制効果を十分に得ることができ、ＲＯ膜装置前段での還元剤の添加や活性炭塔の設置を不要とすることができる。
とりわけ、ＲＯ膜装置入口での残留塩素に占める結合塩素（活性化結合塩素と安定化結合塩素との合計）の割合は９０％以上であることが好ましく、更に、安定化結合塩素が８０％以上であることが好ましい。そして、このような割合となるように、塩素安定化剤としての窒素化合物の種類や添加量を制御することにより、ＲＯ膜の劣化を防止した上で良好なバイオファウリング抑制効果を得ることができる。 In particular, in the present invention, the residual chlorine concentration at the RO membrane apparatus inlet is in the above range by stabilizing chlorine by a chlorine-based oxidizing agent or chlorine generated by electrolysis with a nitrogen compound, and the free chlorine concentration is 0.1. By controlling to be 1 mg-Cl 2 / L or less, particularly 0.05 mg-Cl 2 / L or less, it is possible to obtain a sufficient biofouling suppression effect while preventing oxidative degradation of the RO membrane due to free chlorine. It is possible to eliminate the need for addition of a reducing agent and installation of an activated carbon tower in the previous stage of the RO membrane device.
In particular, the proportion of bonded chlorine (total of activated bonded chlorine and stabilized bonded chlorine) in the residual chlorine at the entrance of the RO membrane device is preferably 90% or more, and more preferably 80% or more of stabilized bonded chlorine. It is preferable that And by controlling the kind and addition amount of the nitrogen compound as the chlorine stabilizer so as to be such a ratio, it is possible to obtain a good biofouling suppression effect while preventing the deterioration of the RO membrane. it can.

なお、ここで、遊離塩素、活性化結合塩素、安定化結合塩素とは、後述の実施例の項に記載の方法で測定される塩素に該当し、残留塩素とは、これら遊離塩素、活性化結合塩素及び安定化結合塩素の合計である。   Here, free chlorine, activated bound chlorine, and stabilized bound chlorine correspond to chlorine measured by the method described in the Examples section below, and residual chlorine refers to these free chlorine, activated chlorine. The sum of bound chlorine and stabilized bound chlorine.

本発明では、上記の通り、残留塩素濃度を制御することにより、ＲＯ膜装置の入口での還元剤の添加や活性炭塔の設置を不要とすることができるが、何らこれらの操作や装置を排除するものではなく、必要に応じて少量の還元剤を添加してもよい。   In the present invention, as described above, by controlling the residual chlorine concentration, it is not necessary to add a reducing agent at the entrance of the RO membrane device or install an activated carbon tower, but these operations and devices are excluded. A small amount of a reducing agent may be added as necessary.

図１では、本発明を海水の淡水化設備に適用した場合を例示したが、本発明において、水処理装置はＲＯ膜装置に限らず、バイオファウリング抑制のために塩素系酸化剤の添加又は電気分解を行うが、装置の劣化防止のために、その入口側で遊離塩素を除去する必要があるイオン交換装置等の水処理装置による水処理にも適用することができる。また、供給水は海水に限らず、河川水や井水、湖沼水、各種排水等を供給水とする場合にも適用することができる。ただし、塩素の分解、トリハロメタン等の有機塩素化合物の生成、ＲＯ膜劣化といった課題の解決の面から、海水のＲＯ膜装置による淡水化設備に適用した場合、特に本発明の効果が有効に発揮される。   In FIG. 1, although the case where this invention was applied to the desalination equipment of seawater was illustrated, in this invention, a water treatment apparatus is not restricted to RO membrane apparatus, addition of a chlorine-type oxidizing agent for biofouling suppression, or Although electrolysis is performed, it can also be applied to water treatment by a water treatment device such as an ion exchange device in which free chlorine needs to be removed on the inlet side in order to prevent deterioration of the device. Further, the supply water is not limited to seawater, but can also be applied to the case where river water, well water, lake water, various waste waters, or the like is used as supply water. However, the effect of the present invention is particularly effective when applied to a desalination facility using an RO membrane device for seawater from the viewpoint of solving problems such as decomposition of chlorine, generation of organic chlorine compounds such as trihalomethane, and RO membrane deterioration. The

以下に実施例に代わる実験例を挙げて本発明をより具体的に説明する。   Hereinafter, the present invention will be described more specifically with reference to experimental examples instead of the examples.

以下の実験例において、塩素濃度（ｍｇ−Ｃｌ２／Ｌ）の測定には、東亜ＤＫＫ社製ポケット塩素測定器「ＨＡＣＨ２４７０」を用い、以下の測定方法ないし算出方法で各塩素濃度を求めた。 In the following experimental examples, the chlorine concentration (mg-Cl 2 / L) was measured using a pocket chlorine measuring device “HACH2470” manufactured by Toa DKK, and each chlorine concentration was determined by the following measurement method or calculation method.

遊離塩素濃度：遊離塩素測定用試薬であるＤＰＤ（Ｆｒｅｅ）試薬による５〜３０秒後
の塩素濃度測定結果（ｍｇ−Ｃｌ２／Ｌ）
活性化結合塩素濃度：遊離塩素測定用試薬であるＤＰＤ（Ｆｒｅｅ）試薬による３００
秒後の塩素濃度測定結果（ｍｇ−Ｃｌ２／Ｌ）から、上記遊離塩素濃度
（ｍｇ−Ｃｌ２／Ｌ）の測定結果を差し引いた値
安定化結合塩素濃度：全塩素測定用試薬であるＤＰＤ（Ｔｏｔａｌ）試薬による１８０
秒後の塩素濃度測定結果（ｍｇ−Ｃｌ２／Ｌ）から、遊離塩素測定用試
薬であるＤＰＤ（Ｆｒｅｅ）試薬による３００秒後の塩素濃度測定結果
（ｍｇ−Ｃｌ２／Ｌ）を差し引いた値
残留塩素濃度：上記遊離塩素濃度と活性化結合塩素濃度と安定化結合塩素濃度の合計
（ｍｇ−Ｃｌ２／Ｌ） Free chlorine concentration: 5 to 30 seconds after DPD (Free) reagent, which is a reagent for measuring free chlorine
The chlorine concentration measurements (mg-Cl 2 / L)
Activated bound chlorine concentration: 300 by DPD (Free) reagent which is a reagent for measuring free chlorine
From the chlorine concentration measurement result (mg-Cl 2 / L) after 2 seconds, the free chlorine concentration
Value obtained by subtracting the measurement result of (mg-Cl 2 / L) Stabilized bound chlorine concentration: 180 by DPD (Total) reagent which is a reagent for measuring total chlorine
From the chlorine concentration measurement result (mg-Cl 2 / L) after 2 seconds, the test for free chlorine measurement
Chlorine concentration measurement results after 300 seconds with the drug DPD (Free) reagent
Value obtained by subtracting (mg-Cl 2 / L) Residual chlorine concentration: Sum of the above free chlorine concentration, activated bound chlorine concentration and stabilized bound chlorine concentration
(Mg-Cl 2 / L)

海水としては大洗海水を用い、ビーカー試験を実施した。   Oarai seawater was used as seawater, and a beaker test was conducted.

［実験例１］
海水に塩素安定化剤としてスルファミン酸を添加したときの効果を調べる実験を行った。
スルファミン酸３０ｍｇ／Ｌを海水に添加して１分間均一に撹拌混合した後、次亜塩素酸ナトリウムを１．５ｍｇ−Ｃｌ２／Ｌ添加し、５分後と６０分後の各塩素濃度を調べた。
別に、海水に次亜塩素酸ナトリウムを１．５ｍｇ−Ｃｌ２／Ｌ添加した後、１分経過後にスルファミン酸３０ｍｇ／Ｌを添加し、５分後と６０分後の各塩素濃度を調べた。
これらの結果を図３に示す。
図３中、「（後）スルファミン酸」は次亜塩素酸ナトリウム添加後にスルファミン酸を添加した場合を示し、「（先）スルファミン酸」は次亜塩素酸ナトリウム添加前にスルファミン酸を添加した場合を示す。以下の実験例２〜６においても同様である。 [Experimental Example 1]
An experiment was conducted to investigate the effect of adding sulfamic acid as a chlorine stabilizer to seawater.
After the sulfamic acid 30 mg / L were uniformly stirred and mixed for 1 minute is added to seawater, the sodium hypochlorite was added 1.5mg-Cl 2 / L, examine each chlorine concentration after five minutes and 60 minutes It was.
Separately, 1.5 mg-Cl 2 / L of sodium hypochlorite was added to seawater, 30 mg / L of sulfamic acid was added after 1 minute, and each chlorine concentration after 5 minutes and 60 minutes was examined.
These results are shown in FIG.
In FIG. 3, “(after) sulfamic acid” indicates the case where sulfamic acid is added after the addition of sodium hypochlorite, and “(previous) sulfamic acid” indicates the case where sulfamic acid is added before the addition of sodium hypochlorite. Indicates. The same applies to Experimental Examples 2 to 6 below.

［実験例２〜６］
スルファミン酸３０ｍｇ／Ｌの代わりにそれぞれ以下のものを７．５ｍｇ／Ｌ添加したこと以外は実験例１と同様に、各々添加効果を調べ、結果をそれぞれ図４〜８に示した。
実施例２：グリシン
実施例３：フェニルアラニン
実施例４：トレオニン
実施例５：オルニチン
実施例６：タウリン [Experimental Examples 2 to 6]
Each of the addition effects was examined in the same manner as in Experimental Example 1 except that 7.5 mg / L of the following was added instead of sulfamic acid 30 mg / L, and the results are shown in FIGS.
Example 2: Glycine Example 3: Phenylalanine Example 4: Threonine Example 5: Ornithine Example 6: Taurine

［比較実験例１］
海水に次亜塩素酸ナトリウム（ＮａＣｌＯ）を１．５ｍｇ−Ｃｌ２／Ｌ又は２．５ｍｇ−Ｃｌ２／Ｌ添加し、５分後又は６０分後の各塩素濃度を測定し、結果を図９に示した。 [Comparative Experiment Example 1]
Sodium hypochlorite (NaClO) was added to seawater at 1.5 mg-Cl 2 / L or 2.5 mg-Cl 2 / L, and the chlorine concentrations after 5 or 60 minutes were measured. The results are shown in FIG. It was shown to.

図３〜９から次のことが分かる。
次亜塩素酸ナトリウムのみの添加の場合、１．５ｍｇ−Ｃｌ２／Ｌの添加では、残留塩素濃度は６０分後に残留塩素濃度０．４ｍｇ−Ｃｌ２／Ｌにまで低下してしまい、２．５ｍｇ−Ｃｌ２／Ｌの高濃度添加でも６０分後には１．２ｍｇ−Ｃｌ２／Ｌを下回る結果となる（図９）。
これに対して、塩素安定化剤として窒素化合物を添加した後次亜塩素酸ナトリウムを添加することにより、遊離塩素濃度は低減しても活性化結合塩素及び安定化結合塩素濃度が増え、次亜塩素酸ナトリウムのみを添加した場合に比べて残留塩素濃度を高く維持することができ、次亜塩素酸ナトリウム１．５ｍｇ−Ｃｌ２／Ｌの添加で、６０分後でも残留塩素濃度を１．２〜１．５ｍｇ−Ｃｌ２／Ｌ程度に維持することができている。しかし、同じ窒素化合物であっても、次亜塩素酸ナトリウム添加後に添加した場合には、このような効果は得られない（図３〜８）。 The following can be seen from FIGS.
In the case of adding only sodium hypochlorite, when 1.5 mg-Cl 2 / L is added, the residual chlorine concentration drops to a residual chlorine concentration of 0.4 mg-Cl 2 / L after 60 minutes. resulting in less than 1.2mg-Cl 2 / L even after 60 minutes at high concentrations the addition of 5mg-Cl 2 / L (Fig. 9).
On the other hand, by adding a nitrogen compound as a chlorine stabilizer and then adding sodium hypochlorite, even if the free chlorine concentration is reduced, the activated bound chlorine and the stabilized bound chlorine concentration are increased. The residual chlorine concentration can be maintained higher than when only sodium chlorate is added, and by adding 1.5 mg-Cl 2 / L of sodium hypochlorite, the residual chlorine concentration becomes 1.2 even after 60 minutes. It can be maintained at about ˜1.5 mg-Cl 2 / L. However, even if the same nitrogen compound is added after addition of sodium hypochlorite, such an effect cannot be obtained (FIGS. 3 to 8).

これらの結果より、本発明によれば、予め塩素安定化剤として窒素化合物を添加した後、次亜塩素酸ナトリウム等の塩素系酸化剤を添加したり電気分解で遊離塩素を発生させることにより、供給水中の塩素を安定化させることができ、
１） 海水中の有機物、臭素、ヨウ素による塩素の分解や消費を抑えることができるので、バイオファウリングの抑制に必要な塩素系酸化剤添加量の削減又は電気分解装置の消費電力の低減を図ることができる。
２） 遊離塩素濃度を低減することでＲＯ膜の劣化などの影響を低減することができる。場合によってはＲＯ膜装置の手前で還元剤や活性炭塔での分解処理を行うことなく、ＲＯ膜のバイオファウリングを抑制することができる。
３） 塩素を安定化することにより、トリハロメタンなどの有害物の生成を抑制することができる。
といった優れた効果を得ることができることが分かる。
また、窒素化合物の後添加では、先添加におけるような効果が得られないことから、本発明の効果は、単に塩素系酸化剤を窒素化合物で安定化させて結合塩素系酸化剤として添加するものとは全く異なるものであることが分かる。 From these results, according to the present invention, by previously adding a nitrogen compound as a chlorine stabilizer, by adding a chlorine-based oxidant such as sodium hypochlorite or generating free chlorine by electrolysis, Can stabilize the chlorine in the supply water,
1) Since the decomposition and consumption of chlorine by organic matter, bromine and iodine in seawater can be suppressed, the amount of chlorinated oxidant added necessary to suppress biofouling is reduced or the power consumption of the electrolyzer is reduced. be able to.
2) By reducing the free chlorine concentration, it is possible to reduce the influence of RO membrane deterioration and the like. In some cases, biofouling of the RO membrane can be suppressed without performing decomposition treatment with a reducing agent or activated carbon tower before the RO membrane device.
3) By stabilizing chlorine, it is possible to suppress the generation of harmful substances such as trihalomethanes.
It can be seen that such excellent effects can be obtained.
In addition, the effect of the present invention can be obtained simply by stabilizing the chlorine-based oxidant with the nitrogen compound and adding it as a combined chlorine-based oxidant because the post-addition of the nitrogen compound does not provide the same effect as in the previous addition. It turns out that it is completely different.

１ 原水槽
２ 反応槽
３ ２層式濾過器
４ 給水槽
５ 保安フィルター
６ ＲＯ膜装置
７ 電解装置 DESCRIPTION OF SYMBOLS 1 Raw water tank 2 Reaction tank 3 Two-layer type filter 4 Water supply tank 5 Security filter 6 RO membrane apparatus 7 Electrolyzer

Claims (6)

水処理装置への供給水に、塩素系酸化剤を添加するか或いは電気分解で塩素を発生させることにより遊離塩素を存在させた後該水処理装置に供給する水処理方法において、
該供給水に遊離塩素を存在させるに先立ち、該供給水に塩素安定化剤として、グリシン、タウリン、トレオニン、オルニチン、アラニン及びフェニルアラニンよりなる群から選ばれる１種又は２種以上の有機窒素化合物を添加することを特徴とする水処理方法。 In the water treatment method of supplying free water to the water treatment apparatus after adding free chlorine by adding a chlorine-based oxidizing agent to the water supplied to the water treatment apparatus or generating chlorine by electrolysis,
Prior to the presence of free chlorine in the feed water, the feed water contains one or more organic nitrogen compounds selected from the group consisting of glycine, taurine, threonine, ornithine, alanine and phenylalanine as a chlorine stabilizer. A water treatment method characterized by adding. 請求項１において、前記水処理装置が逆浸透膜装置であることを特徴とする水処理方法。   The water treatment method according to claim 1, wherein the water treatment device is a reverse osmosis membrane device. 請求項１又は２において、前記供給水が海水であることを特徴とする水処理方法。   The water treatment method according to claim 1, wherein the supply water is seawater. 請求項１ないし３のいずれか１項において、前記塩素系酸化剤として次亜塩素酸塩及び／又はジクロロイソシアヌル酸を前記供給水に添加することを特徴とする水処理方法。   4. The water treatment method according to claim 1, wherein hypochlorite and / or dichloroisocyanuric acid is added to the feed water as the chlorine-based oxidant. 5. 請求項１ないし４のいずれか１項において、前記窒素化合物を前記供給水に０．３〜５０ｍｇ／Ｌ添加することを特徴とする水処理方法。   5. The water treatment method according to claim 1, wherein 0.3 to 50 mg / L of the nitrogen compound is added to the supply water. 請求項１ないし５のいずれか１項において、前記遊離塩素を存在させた後の前記供給水の残留塩素濃度を０．１〜１０ｍｇ−Ｃｌ２／Ｌに維持することを特徴とする水処理方法。 The water treatment method according to any one of claims 1 to 5, wherein the residual chlorine concentration of the supplied water after the presence of the free chlorine is maintained at 0.1 to 10 mg-Cl 2 / L. .
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