JP5017922B2 - Water treatment method - Google Patents
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- JP5017922B2 JP5017922B2 JP2006132264A JP2006132264A JP5017922B2 JP 5017922 B2 JP5017922 B2 JP 5017922B2 JP 2006132264 A JP2006132264 A JP 2006132264A JP 2006132264 A JP2006132264 A JP 2006132264A JP 5017922 B2 JP5017922 B2 JP 5017922B2
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims description 181
- 238000000034 method Methods 0.000 title claims description 49
- 239000012528 membrane Substances 0.000 claims description 129
- 239000000126 substance Substances 0.000 claims description 61
- 238000011001 backwashing Methods 0.000 claims description 45
- 238000001914 filtration Methods 0.000 claims description 34
- 238000004140 cleaning Methods 0.000 claims description 33
- 238000005374 membrane filtration Methods 0.000 claims description 25
- 238000005406 washing Methods 0.000 claims description 15
- 239000002351 wastewater Substances 0.000 claims description 12
- 238000005201 scrubbing Methods 0.000 claims description 6
- 239000003795 chemical substances by application Substances 0.000 claims description 5
- 238000011010 flushing procedure Methods 0.000 claims description 5
- 239000013049 sediment Substances 0.000 claims description 5
- 239000000243 solution Substances 0.000 claims description 5
- 239000010802 sludge Substances 0.000 claims description 4
- 239000003814 drug Substances 0.000 claims 2
- 229940079593 drug Drugs 0.000 claims 1
- 239000008155 medical solution Substances 0.000 claims 1
- 238000003860 storage Methods 0.000 description 14
- 239000010865 sewage Substances 0.000 description 10
- 239000008400 supply water Substances 0.000 description 10
- 239000000706 filtrate Substances 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 7
- 239000003344 environmental pollutant Substances 0.000 description 7
- 231100000719 pollutant Toxicity 0.000 description 7
- 239000005708 Sodium hypochlorite Substances 0.000 description 6
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 6
- 239000000356 contaminant Substances 0.000 description 6
- SUKJFIGYRHOWBL-UHFFFAOYSA-N sodium hypochlorite Chemical compound [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 description 6
- 238000007654 immersion Methods 0.000 description 5
- 238000002347 injection Methods 0.000 description 5
- 239000007924 injection Substances 0.000 description 5
- 238000011084 recovery Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 238000009285 membrane fouling Methods 0.000 description 4
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 3
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 3
- 230000004907 flux Effects 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 238000000746 purification Methods 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 2
- 238000000151 deposition Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- WQYVRQLZKVEZGA-UHFFFAOYSA-N hypochlorite Chemical compound Cl[O-] WQYVRQLZKVEZGA-UHFFFAOYSA-N 0.000 description 2
- 239000008239 natural water Substances 0.000 description 2
- 238000002791 soaking Methods 0.000 description 2
- IXPNQXFRVYWDDI-UHFFFAOYSA-N 1-methyl-2,4-dioxo-1,3-diazinane-5-carboximidamide Chemical compound CN1CC(C(N)=N)C(=O)NC1=O IXPNQXFRVYWDDI-UHFFFAOYSA-N 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- 229910021578 Iron(III) chloride Inorganic materials 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- ZGOFOSYUUXVFEO-UHFFFAOYSA-N [Fe+4].[O-][Si]([O-])([O-])[O-] Chemical compound [Fe+4].[O-][Si]([O-])([O-])[O-] ZGOFOSYUUXVFEO-UHFFFAOYSA-N 0.000 description 1
- 229920006317 cationic polymer Polymers 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 239000000701 coagulant Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000012510 hollow fiber Substances 0.000 description 1
- -1 hydrogen peroxide Chemical compound 0.000 description 1
- 230000033444 hydroxylation Effects 0.000 description 1
- 238000005805 hydroxylation reaction Methods 0.000 description 1
- QWPPOHNGKGFGJK-UHFFFAOYSA-N hypochlorous acid Chemical compound ClO QWPPOHNGKGFGJK-UHFFFAOYSA-N 0.000 description 1
- 239000008235 industrial water Substances 0.000 description 1
- 238000001802 infusion Methods 0.000 description 1
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 description 1
- 238000001471 micro-filtration Methods 0.000 description 1
- 150000007522 mineralic acids Chemical class 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000001728 nano-filtration Methods 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 150000007524 organic acids Chemical class 0.000 description 1
- 235000005985 organic acids Nutrition 0.000 description 1
- 235000006408 oxalic acid Nutrition 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 229920002401 polyacrylamide Polymers 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 238000004062 sedimentation Methods 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 235000010413 sodium alginate Nutrition 0.000 description 1
- 229940005550 sodium alginate Drugs 0.000 description 1
- 239000000661 sodium alginate Substances 0.000 description 1
- 239000002352 surface water Substances 0.000 description 1
- 238000000108 ultra-filtration Methods 0.000 description 1
- 238000004065 wastewater treatment Methods 0.000 description 1
Landscapes
- Separation Using Semi-Permeable Membranes (AREA)
Description
本発明は、河川水、表流水、地下水、伏流水、工業用水、再利用水等に含まれる汚濁物質を分離除去して浄水化する水処理方法に関する。 The present invention relates to a water treatment method for separating and removing pollutants contained in river water, surface water, underground water, underground water, industrial water, reused water, etc. to purify the water.
膜を用いた水処理装置では、被処理水中の懸濁物質や有機物質等が、長時間の運転によって膜の表面に徐々に堆積していき、膜ファウリングが発生する。膜ファウリングが発生すると、膜圧力の上昇や、ろ過流束の低下等が引き起こり、浄水効率が落ち、水処理装置の全体的な運転効率が低下する。そのため水処理装置の運転サイクルでは、所定時間のろ過工程後に、膜を物理洗浄している。 In a water treatment apparatus using a membrane, suspended substances, organic substances, etc. in the water to be treated are gradually deposited on the surface of the membrane over a long period of operation, and membrane fouling occurs. When membrane fouling occurs, an increase in membrane pressure, a decrease in filtration flux, and the like are caused, water purification efficiency is lowered, and the overall operation efficiency of the water treatment device is lowered. Therefore, in the operation cycle of the water treatment apparatus, the membrane is physically washed after the filtration process for a predetermined time.
膜の物理洗浄としては、ろ過水等を膜の二次側から一次側へと逆流させる逆流洗浄（以下、逆洗という）、膜の一次側での水流によるフラッシング、空気により膜を振動させるエアースクラビング等があり、物理的な作用によって膜に付着した物質を取り除いている。 The physical cleaning of the membrane includes backwashing (hereinafter referred to as backwashing) in which filtered water flows backward from the secondary side of the membrane to the primary side, flushing by water flow on the primary side of the membrane, and air that vibrates the membrane with air. There is scrubbing, etc., which removes substances attached to the film by physical action.
しかしながら、逆洗では、ろ過水を用いて洗浄する場合が多いことから、ろ過水の回収率が低下するという問題点があった。また、エアースクラビングは膜の寿命に影響するという問題があった。また、これら物理洗浄を実施しても膜への付着物質を完全に除去することができず、物理洗浄では膜ファウリングの発生を抑制できなくなるので、やがては膜に対して薬品洗浄を実施する必要が生じる。 However, since backwashing is often performed using filtered water, there is a problem that the recovery rate of filtered water is reduced. In addition, air scrubbing has a problem of affecting the life of the membrane. In addition, even if these physical cleanings are performed, the substances adhering to the film cannot be completely removed, and the physical cleaning cannot suppress the occurrence of film fouling. Need arises.
薬品洗浄は、物理洗浄では除去しきれない物質を薬品によって分解または溶解させて除去する洗浄方法であって、例えば下記特許文献１に開示されているように、膜ろ過処理と、水による逆洗等の物理洗浄等を所定の回数繰り返した後、次亜塩素酸ナトリウム等の次亜塩素酸塩や、硫酸等の薬品を膜に浸漬注入している。このように、物理洗浄ではろ過性能が回復しきれなくなった膜に薬品洗浄を施すことで、膜のろ過能力をほぼ初期状態まで回復することができる。 The chemical cleaning is a cleaning method in which a substance that cannot be removed by physical cleaning is removed by decomposing or dissolving with a chemical. For example, as disclosed in Patent Document 1 below, membrane filtration treatment and backwashing with water are performed. After repeating physical washing such as a predetermined number of times, hypochlorite such as sodium hypochlorite and chemicals such as sulfuric acid are immersed and injected into the membrane. In this way, by performing chemical cleaning on the membrane whose filtration performance cannot be recovered by physical cleaning, the filtration capability of the membrane can be almost restored to the initial state.
しかしながら、薬品洗浄は、薬品コスト、薬品洗浄後の排水処理コスト、膜の劣化等の観点から、できるだけ効率よく実施する必要があり、膜ファウリングの発生をできるだけ抑制することが望まれている。 However, chemical cleaning must be performed as efficiently as possible from the viewpoints of chemical cost, wastewater treatment cost after chemical cleaning, membrane deterioration, and the like, and it is desired to suppress the occurrence of membrane fouling as much as possible.
膜ファウリングの発生を抑制する方法の一つとして、膜表面にあらかじめプレコート層（プリコート層）と呼ばれる層を形成させて、この層の働きによって膜ファウリングを抑制する方法が提案されている。例えば、下記特許文献２には、逆洗後のろ過開始時に、逆洗排水を用いて、該逆洗排水中の凝集粒子を膜表面にコーティングする方法が開示されている。
膜表面にプレコート層を形成させて被処理水を膜ろ過処理することで、膜ファウリングの発生を抑制できる。 By forming a precoat layer on the membrane surface and subjecting the water to be treated to membrane filtration, the occurrence of membrane fouling can be suppressed.
しかしながら、上記特許文献２のように、膜表面に高濃度の逆洗排水粒子をコーティングした状態で膜ろ過処理を行った場合、得られるろ過水は、衛生面の点について課題を有していた。 However, when the membrane filtration treatment is performed in a state where the membrane surface is coated with high-concentration backwash drainage particles as in Patent Document 2, the obtained filtrate has a problem in terms of hygiene. .
また、膜表面にプレコート層を形成させることで、ろ過流速が低下する傾向にあり、膜表面にプレコート層を形成しない場合に比べて水処理効率が劣る傾向にあった。 Further, by forming a precoat layer on the membrane surface, the filtration flow rate tends to decrease, and the water treatment efficiency tends to be inferior as compared to the case where the precoat layer is not formed on the membrane surface.
よって、本発明の目的は、水処理効率に優れ、物理洗浄による洗浄効果が高く、薬品洗浄の頻度を低減もしくは薬品洗浄を省くことのできる水処理方法を提供することにある。 Therefore, an object of the present invention is to provide a water treatment method that is excellent in water treatment efficiency, has a high washing effect by physical washing, and can reduce the frequency of chemical washing or omit chemical washing.
上記目的を達成するにあたり、本発明の水処理方法は、被処理水を膜を用いてろ過する膜ろ過処理工程と、前記膜に逆洗水を流す逆洗工程とを繰り返して行う水処理方法において、少なくとも一部の逆洗工程は、該逆洗工程に先立って、前記被処理水の濁度に対して通常の水質変動を超える高濁度の汚濁水を前記膜でろ過した後、前記逆洗工程を行うようにしたことを特徴とする。 In achieving the above object, the water treatment method of the present invention is a water treatment method in which a membrane filtration treatment step for filtering water to be treated using a membrane and a backwash step for flowing backwash water through the membrane are repeated. In at least a part of the backwashing step, prior to the backwashing step, after filtering the turbid water with high turbidity exceeding the normal water quality fluctuation with respect to the turbidity of the water to be treated with the membrane, A backwashing process is performed.
膜を逆洗する前に、被処理水の濁度に対して通常の水質変動を超える高濁度の汚濁水をろ過することで、膜表面に汚濁物質が堆積していき、該汚濁物質によって堆積層が形成される。そして、この堆積層が形成された状態で逆洗することで、通常の逆洗では除去できず、膜内部に堆積していくような汚濁物質を除去することができ、膜ファウリングの発生を長期にわたって抑制できる。 Before the membrane is backwashed, by filtering high-turbidity polluted water that exceeds normal water quality fluctuations relative to the turbidity of the water to be treated, contaminants accumulate on the membrane surface. A deposited layer is formed. And by washing back in the state where this deposited layer is formed, it is possible to remove contaminants that cannot be removed by normal backwashing and accumulate inside the film, and film fouling is generated. It can be suppressed for a long time.
これは、膜の一次側に堆積層が形成された状態で逆洗を行うことで、膜面にかかる抵抗が大きくなり、洗浄強度の分布が均一になる。また、膜に捕捉された汚濁物質は、逆洗によって圧縮されて、剥離しやすい形態へと変化する。そして、この圧縮された汚濁物質が膜内を流通する際に、膜に捕捉された汚濁物質を削り取るような形で通過していくためであると推測できる。 This is because backwashing is performed in a state where a deposited layer is formed on the primary side of the film, so that the resistance applied to the film surface is increased and the distribution of the cleaning strength becomes uniform. Further, the pollutant trapped in the film is compressed by backwashing and changes into a form that is easy to peel off. And when this compressed pollutant distribute | circulates the inside of a film | membrane, it can be estimated that it is for passing in the form which scrapes off the polluted substance trapped by the film | membrane.
本発明の水処理方法において、前記汚濁水が、前記逆洗工程で排出された逆洗排水、又は凝集沈殿汚泥を含有させた水であることが好ましい。 In the water treatment method of the present invention, the polluted water is preferably water containing backwash wastewater discharged in the backwashing step or coagulated sediment sludge.
また、本発明の水処理方法において、少なくとも一部の逆洗工程の後に、薬液洗浄工程、エアースクラビング工程及びフラッシング工程から選ばれた処理工程を行うことが好ましい。 In the water treatment method of the present invention, it is preferable to perform a treatment step selected from a chemical solution washing step, an air scrubbing step, and a flushing step after at least a part of the backwashing step.
また、本発明の水処理方法において、前記薬液洗浄工程は、ろ過水に薬品を添加混合して逆洗し、膜を該薬品の添加水に所定時間浸漬させた後、膜の一次側から取出して排水する処理からなることが好ましい。 Further, in the water treatment method of the present invention, the chemical solution washing step is performed by adding a chemical to filtered water, backwashing, immersing the membrane in the chemical-added water for a predetermined time, and then removing from the primary side of the membrane. It is preferable to consist of the process which drains.
本発明の水処理方法によれば、逆洗による膜の洗浄効果が高いので、物理洗浄によって膜の一次側と二次側の膜差圧の上昇を効率的に抑制でき、薬品洗浄を行わなくても、安定した水処理を長期にわたって継続することができる。このため、薬品洗浄の頻度や、薬品洗浄に用いる薬品濃度を低下することが可能となり、水処理工程全体のランニングコストの低下および膜の長寿命化が図れる。 According to the water treatment method of the present invention, since the membrane cleaning effect by back washing is high, the increase in membrane differential pressure between the primary side and the secondary side of the membrane can be effectively suppressed by physical washing, and chemical washing is not performed. However, stable water treatment can be continued for a long time. For this reason, it becomes possible to reduce the frequency of chemical cleaning and the chemical concentration used for chemical cleaning, thereby reducing the running cost of the entire water treatment process and extending the life of the membrane.
本発明での被処理水としては、不溶解性有機物を含む水であればどのような水でも使用でき、具体的には河川水、湖沼水、下水、工場廃水等が好ましい。 As the water to be treated in the present invention, any water containing insoluble organic substances can be used. Specifically, river water, lake water, sewage, factory waste water, and the like are preferable.
以下、本発明について図面を用いて更に詳細に説明する。図１には、本発明の水処理方法に用いることができる水処理装置の一実施形態の概略構成図が示されている。 Hereinafter, the present invention will be described in more detail with reference to the drawings. FIG. 1 shows a schematic configuration diagram of an embodiment of a water treatment apparatus that can be used in the water treatment method of the present invention.
まず、図１の水処理装置について説明すると、この水処理装置は、水処理の対象となる被処理水（以下、原水とする）を貯留する供給水タンク１０と、原水中の汚濁物質を捕捉してろ過水を得る膜モジュール２０と、原水の濁度に対して通常の水質変動を超える高濁度の汚濁水（以下、高濁度汚濁水とする）を貯留する高濁度汚水貯留槽３０と、ろ過水を貯留する貯水槽４０とで主に構成されている。 First, the water treatment apparatus of FIG. 1 will be described. This water treatment apparatus captures a supply water tank 10 for storing water to be treated (hereinafter referred to as raw water) and contaminants in the raw water. Membrane module 20 for obtaining filtered water and high turbidity sewage storage tank for storing highly turbid water (hereinafter referred to as high turbidity polluted water) exceeding normal water quality fluctuations relative to the turbidity of raw water 30 and a water storage tank 40 for storing filtered water.
供給水タンク１０は、膜供給水バルブ１１と、運転ポンプ１２と、膜入口バルブ１３とを配置された配管１を介して膜モジュール２０の一次側２０ａに連結している。 The feed water tank 10 is connected to the primary side 20a of the membrane module 20 via the pipe 1 in which the membrane feed water valve 11, the operation pump 12, and the membrane inlet valve 13 are arranged.
膜モジュール２０に用いる膜は、一般的なろ過膜であれば全て使用でき、精密ろ過膜（ＭＦ膜）、限外ろ過膜（ＵＦ膜）、ナノろ過膜（ＮＦ膜）等が挙げられる。また、膜モジュール２０の形態としては、特に限定は無く、中空糸膜モジュール、平膜型モジュール、スパイラル型モジュール、管型モジュール等が使用可能である。 Any membrane can be used for the membrane module 20 as long as it is a general filtration membrane, and examples thereof include a microfiltration membrane (MF membrane), an ultrafiltration membrane (UF membrane), and a nanofiltration membrane (NF membrane). Moreover, there is no limitation in particular as a form of the membrane module 20, A hollow fiber membrane module, a flat membrane type module, a spiral type module, a tube type module, etc. can be used.
膜供給水バルブ１１と、運転ポンプ１２とを連結する配管の一部は分岐しており、高濁度汚水供給バルブ３１を介して高濁度汚水貯留槽３０に接続している。 A part of the pipe connecting the membrane supply water valve 11 and the operation pump 12 is branched and connected to the high turbidity sewage storage tank 30 via the high turbidity sewage supply valve 31.
膜モジュール２０の原水の流入側である一次側２０ａには、図示しない逆洗排水排出口が設けられており、逆洗排水排出バルブ２１の配置された配管２から、逆洗排水を膜モジュール２０の系外に排出できるように構成されている。また、膜モジュール２０のろ過水の流出側である二次側２０ｂは、膜出口バルブ２２の配置された配管３を介して、貯水槽４０に連結している。 The primary side 20a which is the inflow side of the raw water of the membrane module 20 is provided with a backwash drainage outlet (not shown), and the backwash drainage is supplied from the pipe 2 where the backwash drainage valve 21 is arranged to the membrane module 20. It can be discharged out of the system. Moreover, the secondary side 20b which is the outflow side of the filtrate water of the membrane module 20 is connected to the water storage tank 40 via the piping 3 in which the membrane outlet valve 22 is arranged.
貯水槽４０の上部には、図示しないろ液排出口が設けられており、ろ液の一部を配管４から、貯水槽４０の系外に排出できる。また、貯水槽４０の下部は、逆洗水供給ポンプ４１と、逆洗水供給バルブ４２とを配置された配管５を介して配管３に接続している。 A filtrate discharge port (not shown) is provided in the upper part of the water storage tank 40, and a part of the filtrate can be discharged out of the system of the water storage tank 40 from the pipe 4. The lower part of the water storage tank 40 is connected to the pipe 3 via the pipe 5 in which the backwash water supply pump 41 and the backwash water supply valve 42 are arranged.
次に、この水処理装置を用いた本発明の水処理方法について説明する。 Next, the water treatment method of the present invention using this water treatment apparatus will be described.
まず、供給水タンク１０に流入した原水を、運転ポンプ１２を稼動させ、膜供給水バルブ１１、膜入口バルブ１３及び膜出口バルブ２２を開とし、それ以外のバルブは閉とし、膜モジュール２０の一次側２０ａへと通水して、膜ろ過を行いろ過水を得る膜ろ過処理工程を行う。膜モジュール２０で膜ろ過処理されたろ過水は、貯水槽４０へと貯留された後、大部分は配管４から引き抜かれて次工程へと通水し、貯留されたろ過水の一部は、膜モジュール２０の洗浄を行うための逆洗水として使用する。 First, the raw water flowing into the supply water tank 10 is operated by the operation pump 12, the membrane supply water valve 11, the membrane inlet valve 13 and the membrane outlet valve 22 are opened, the other valves are closed, and the membrane module 20 A membrane filtration treatment step is performed in which water is passed through the primary side 20a and membrane filtration is performed to obtain filtrate. After the filtrate filtered by the membrane module 20 is stored in the water storage tank 40, most of the filtrate is withdrawn from the pipe 4 and passed to the next process. Used as backwash water for cleaning the membrane module 20.
上記膜ろ過処理工程を所定時間行った後、運転ポンプ１２の稼動を停止し、膜供給水バルブ１１、膜入口バルブ１３及び膜出口バルブ２２を閉とし、逆洗排水排出バルブ２１及び逆洗水供給バルブ４２を開とし、逆洗水供給ポンプ４１を稼動させて、貯水槽４０に貯留されたろ過水を膜モジュール２０の二次側２０ｂから一次側２０ａへと通水する逆洗工程を行う。そして、一次側２０ａへと通水された逆洗排水は、配管２から系外に排水する。なお、特に図示していないが、上記逆洗工程の後に、膜モジュール２０の一次側２０ａ及び／又は二次側２０ｂに、エアーコンプレッサー等を用いて圧縮空気を供給してエアースクラビング処理を更に行ってもよく、また、原水を膜面へと通水するフラッシング処理を更に行ってもよい。エアースクラビング処理やフラッシング処理を行うことで、逆洗では除去しきれなかった汚濁物質が除去できる。 After performing the membrane filtration process for a predetermined time, the operation pump 12 is stopped, the membrane supply water valve 11, the membrane inlet valve 13, and the membrane outlet valve 22 are closed, and the backwash drainage discharge valve 21 and the backwash water are closed. The backwashing process is performed in which the supply valve 42 is opened and the backwash water supply pump 41 is operated to pass the filtrate stored in the water storage tank 40 from the secondary side 20b of the membrane module 20 to the primary side 20a. . Then, the backwash wastewater that has been passed to the primary side 20a is drained out of the system from the pipe 2. Although not particularly illustrated, after the backwashing step, air scrubbing treatment is further performed by supplying compressed air to the primary side 20a and / or the secondary side 20b of the membrane module 20 using an air compressor or the like. Alternatively, a flushing process of passing raw water through the membrane surface may be further performed. By performing air scrubbing treatment or flushing treatment, it is possible to remove pollutants that could not be removed by backwashing.
上記膜ろ過処理工程と逆洗工程とを繰り返して水処理を行うと、逆洗工程では除去しきれなかった汚濁物質が徐々に膜表面あるいは膜内部に堆積していく。本発明においては、膜差圧が所定値を越えたとき、あるいは、上記膜ろ過処理工程と逆洗工程とのサイクルが、設定した所定の回数を超えた時、膜ろ過処理工程の後、以下の処理を行う。 When water treatment is performed by repeating the membrane filtration treatment step and the backwashing step, contaminants that could not be removed by the backwashing step gradually accumulate on the membrane surface or inside the membrane. In the present invention, when the membrane differential pressure exceeds a predetermined value, or when the cycle between the membrane filtration treatment step and the backwash step exceeds a predetermined number of times, after the membrane filtration treatment step, the following Perform the process.
すなわち、上記膜ろ過処理工程を終えた後、膜供給水バルブ１１を閉とし、高濁度汚水供給バルブ３１を開として、膜モジュール２０の一次側２０ａに高濁度汚濁水を供給する。高濁度汚濁水は、膜表面の汚濁堆積量が、原水の膜ろ過処理工程で膜モジュール２０の一次側２０ａの膜面上に堆積した汚濁堆積量の５倍以上となるように通水することが好ましい。また、汚濁物質の密度などにもよるが、膜表面の汚濁堆積量がトータルで０．１〜１０ｇ／ｍ２となるように通水することが好ましく、１〜５ｇ／ｍ２がより好ましい。 That is, after finishing the membrane filtration process, the membrane supply water valve 11 is closed, the high turbidity sewage supply valve 31 is opened, and high turbidity turbid water is supplied to the primary side 20a of the membrane module 20. High turbidity polluted water is passed through so that the amount of polluted sediment on the membrane surface is 5 times or more of the amount of polluted sediment deposited on the membrane surface of the primary side 20a of the membrane module 20 in the membrane filtration process of raw water. It is preferable. Also, depending like the density of the contaminants, it is preferable that the contamination amount of deposition of the film surface is passed through so that 0.1 to 10 g / m 2 in total, and more preferably 1 to 5 g / m 2.
高濁度汚濁水の通水時間、通水速度は、膜面への濁質堆積量に応じて適宜調整し、特に限定はしない。高濁度汚濁水の通水時間は、水処理の処理効率の観点から考慮すると短いことが好ましく、通常のろ過工程に引き続いて数分間実施することがより好ましい。また、ろ過流束は、通常のろ過流束と同じが好ましい。 The water passage time and water passage speed of the highly turbidity polluted water are appropriately adjusted according to the amount of turbidity deposited on the membrane surface, and are not particularly limited. In consideration of the treatment efficiency of water treatment, it is preferable that the passing time of highly turbidity polluted water is short, and it is more preferable to carry out for several minutes following the normal filtration step. Further, the filtration flux is preferably the same as a normal filtration flux.
高濁度汚濁水としては、処理時間を短くするために、ポンプや配管などに問題ないレベルにおいてできるだけ高濁度であることが好ましい。しかしながら高濁度原水が得られない場合や処理時間を気にしない場合などは、通常のろ過工程において供給水だけ変更しても問題ない。 The high turbidity polluted water preferably has as high a turbidity as possible at a level where there is no problem with pumps and piping in order to shorten the treatment time. However, when high turbidity raw water cannot be obtained or when processing time is not a concern, there is no problem even if only the supply water is changed in a normal filtration process.
高濁度汚濁水の具体例としては、逆洗排水や、原水及び／又は逆洗排水に、ポリ塩化アルミニウム（ＰＡＣ）、塩化第二鉄（ＦｅＣｌ３）、硫酸バンド、ポリ硫酸第二鉄、重合珪酸―鉄塩（ＰＳＩ）、ポリアクリルアミド系高分子、カチオン系高分子、アルギン酸ナトリウム等の凝集剤を注入して凝集処理することにより得られるマイクロフロック、凝集フロック等もしくはそれら混合物からなる凝集粒子を含む凝集沈殿汚泥等が挙げられる。 Specific examples of high turbidity contaminated water include backwash wastewater, raw water and / or backwash wastewater, polyaluminum chloride (PAC), ferric chloride (FeCl 3 ), sulfate band, polyferric sulfate, Agglomerated particles composed of micro floc, agglomerated floc, etc. obtained by injecting a coagulant such as polymerized silicic acid-iron salt (PSI), polyacrylamide polymer, cationic polymer, sodium alginate and the like or a mixture thereof. Agglomerated sedimentation sludge and the like.
そして、膜モジュール２０に高濁度汚濁水を供給し、膜モジュール２０の一次側２０ａの膜面上に所定量の汚濁物質を堆積させた後、運転ポンプ１２を停止し、高濁度汚水供給バルブ３１及び膜入口バルブ１３を閉とし、逆洗排水排出バルブ２１及び逆洗水供給バルブ４２を開とし、逆洗水供給ポンプ４１を稼動させて、上記逆洗工程を行い、そして、上記膜ろ過処理工程と逆洗工程とを繰り返す一連のサイクルを行う。 And after supplying high turbidity polluted water to the membrane module 20 and depositing a predetermined amount of pollutant on the membrane surface of the primary side 20a of the membrane module 20, the operation pump 12 is stopped and high turbidity sewage is supplied. The valve 31 and the membrane inlet valve 13 are closed, the backwash drainage discharge valve 21 and the backwash water supply valve 42 are opened, the backwash water supply pump 41 is operated, the backwash process is performed, and the membrane A series of cycles for repeating the filtration process and the backwash process is performed.
このように、逆洗工程を行う前に、膜モジュール２０の一次側２０ａの膜面上に、所定量の汚濁物質を堆積させることで、膜全体を剥がすようにして効率よく逆洗することができ、通常の逆洗では除去できず、膜内部に堆積していくような汚濁物質も効率よく除去することができる。 Thus, before performing the backwashing process, a predetermined amount of pollutant is deposited on the membrane surface of the membrane module 20 on the primary side 20a, so that the entire membrane can be efficiently backwashed. In addition, it is possible to efficiently remove contaminants that cannot be removed by ordinary backwashing and accumulate in the film.
これは、膜の一次側２０ａに堆積層が形成された状態で逆洗を行うことで、膜面にかかる抵抗が大きくなり、洗浄強度の分布が均一になる。また、膜に捕捉された汚質は、逆洗によって圧縮されて、剥離しやすい形態へと変化する。そして、この圧縮された汚質が膜内を流通する際に、膜に捕捉された汚質を削り取るような形で通過していくためであると推測できる。 This is because backwashing is performed in a state where a deposited layer is formed on the primary side 20a of the film, so that the resistance applied to the film surface increases and the distribution of the cleaning strength becomes uniform. In addition, the dirt trapped in the film is compressed by backwashing and changes into a form that is easy to peel off. And when this compressed dirt flows through the inside of the film, it can be presumed that it passes through the form so as to scrape off the dirt caught by the film.
図２には、本発明の水処理方法に用いることができる水処理装置の他の実施形態が示されている。なお、前記実施形態と実質的に同一部分には、同符号を付してその説明を省略することとする。 FIG. 2 shows another embodiment of a water treatment apparatus that can be used in the water treatment method of the present invention. Note that parts that are substantially the same as those of the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted.
前記図１に示した実施形態による処理装置との変更点は、（１）膜モジュール２０の一次側２０ａに設けられた逆洗排水口から伸びた配管２の一部が分岐し、逆洗排水回収バルブ２３を介して高濁度汚水貯留槽３０に接続している点、（２）逆洗水供給ポンプ４１と逆洗水供給バルブ４２とを連結する配管の一部が分岐し、薬品注入バルブ５２と薬品注入ポンプ５１とを介して薬品タンク５０に連結している点である。 1 is different from the processing apparatus according to the embodiment shown in FIG. 1 in that (1) a part of the pipe 2 extending from the backwash drain provided on the primary side 20a of the membrane module 20 branches off, and backwash drainage. The point connected to the high turbidity sewage storage tank 30 through the recovery valve 23, (2) a part of the pipe connecting the backwash water supply pump 41 and the backwash water supply valve 42 branches off, and chemical injection It is connected to the chemical tank 50 via the valve 52 and the chemical injection pump 51.
次にこの水処理装置を用いた水処理方法について説明する。なお、基本的な工程は前記実施形態と同様であり、異なる点について詳述する。 Next, a water treatment method using this water treatment apparatus will be described. The basic steps are the same as in the above embodiment, and different points will be described in detail.
供給水タンク１０に流入した原水を、膜モジュール２０の一次側２０ａへと通水し、原水中の汚濁物質を膜で捕捉させてろ過水を得る膜ろ過処理工程を行う。 The raw | natural water which flowed into the supply water tank 10 is passed to the primary side 20a of the membrane module 20, and the membrane filtration process process which capture | acquires the pollutant in raw | natural water with a film | membrane and obtains filtered water is performed.
上記膜ろ過処理工程を所定時間行った後、貯水槽４０のろ過水（逆洗水）を膜モジュール２０へ供給し、膜モジュール２０の逆洗工程を行う。そして、一次側２０ａへと通水された逆洗排水は、配管２から系外に排水する。 After performing the said membrane filtration process process for the predetermined time, the filtered water (backwash water) of the water storage tank 40 is supplied to the membrane module 20, and the membrane module 20 is backwashed. Then, the backwash wastewater that has been passed to the primary side 20a is drained out of the system from the pipe 2.
上記膜ろ過処理工程と逆洗工程とを、繰り返して水処理を行い、膜差圧が所定値を越えたとき、あるいは、上記膜ろ過処理工程と逆洗工程とのサイクルが、設定した所定の回数を超えた時、膜ろ過処理工程の後、膜モジュール２０に高濁度汚濁水を供給し、膜モジュール２０の一次側２０ａの膜面上に、高濁度汚濁水による堆積層を形成させる。 The membrane filtration treatment step and the backwashing step are repeated for water treatment, and when the membrane differential pressure exceeds a predetermined value, or the cycle between the membrane filtration treatment step and the backwashing step is a predetermined predetermined value. When the number of times is exceeded, high turbidity polluted water is supplied to the membrane module 20 after the membrane filtration treatment step, and a deposited layer of high turbidity polluted water is formed on the membrane surface of the primary side 20a of the membrane module 20. .
そして、膜モジュール２０に高濁度汚濁水を供給し、膜モジュール２０の一次側２０ａの膜面上に所定量の堆積層を形成させた後、逆洗工程を行うが、この実施形態においては、高濁度汚濁水をろ過した直後の逆洗工程で排出される逆洗排水を高濁度汚水貯留槽３０へと供給し再利用する。すなわち、高濁度汚濁水をろ過した直後の逆洗工程では、逆洗排水排出バルブ２１を閉とし、逆洗排水回収バルブ２３を開として逆洗工程を行う。 Then, after supplying high turbidity polluted water to the membrane module 20 and forming a predetermined amount of deposited layer on the membrane surface of the primary side 20a of the membrane module 20, a backwashing step is performed. In this embodiment, The backwash wastewater discharged in the backwashing process immediately after filtering the high turbidity polluted water is supplied to the high turbidity sewage storage tank 30 and reused. That is, in the backwashing process immediately after filtering the highly turbid water, the backwashing drainage valve 21 is closed and the backwashing drainage recovery valve 23 is opened to perform the backwashing process.
高濁度汚濁水をろ過した直後の逆洗工程で排出される逆洗排水は、通常の逆洗排水よりも汚濁濃度が高く、特に凝集剤等を添加して凝集処理を行わなくても、高濁度汚濁水として再利用することができる。このため、この実施形態によれば、凝集剤の使用量を低減することができる。また、逆洗排水を再利用することで、ろ過水の回収率を向上させることができる。 The backwash wastewater discharged in the backwash process immediately after filtering the high turbidity polluted water has a higher turbidity concentration than normal backwash wastewater, especially without adding a flocculant etc. It can be reused as highly turbid water. For this reason, according to this embodiment, the usage-amount of a flocculant can be reduced. Moreover, the collection rate of filtered water can be improved by reusing backwash waste water.
そして、上記逆洗工程を終えた後、薬品注入バルブ５２及び逆洗水供給バルブ４２を開とし、膜入口バルブ１３、逆洗排水排出バルブ２１、及び逆洗排水回収バルブ２３を閉とし、薬品注入ポンプ５１を稼動させて、膜モジュール２０の二次側２０ｂに薬品を供給し薬品洗浄工程を行う。 Then, after the backwashing process is finished, the chemical injection valve 52 and the backwash water supply valve 42 are opened, the membrane inlet valve 13, the backwash drainage discharge valve 21, and the backwash drainage recovery valve 23 are closed, and the chemical The infusion pump 51 is operated to supply a chemical to the secondary side 20b of the membrane module 20 and perform a chemical cleaning process.
薬品としては、次亜塩素酸、硝酸、塩酸、硫酸等の無機酸、クエン酸、シュウ酸等の有機酸、次亜塩素酸ナトリウム等の酸化剤、過酸化水素のような還元剤、水酸化ナトリウムのようなアルカリ剤を単独または併用して用いることができる。なかでも、浄水場において一般的に使用されているという理由から硫酸および次亜塩素酸ナトリウムが好ましい。 Chemicals include inorganic acids such as hypochlorous acid, nitric acid, hydrochloric acid and sulfuric acid, organic acids such as citric acid and oxalic acid, oxidizing agents such as sodium hypochlorite, reducing agents such as hydrogen peroxide, hydroxylation Alkaline agents such as sodium can be used alone or in combination. Of these, sulfuric acid and sodium hypochlorite are preferred because they are generally used in water purification plants.
薬品濃度および浸漬時間は、ろ過条件とその目詰まり具合によって適宜調整する必要がある。薬品濃度および浸漬時間が足りない場合は洗浄が不十分となり膜差圧が上昇してしまうこととなり、逆に薬品濃度および浸漬時間が十分すぎる場合は膜への損傷が問題となる。このことから、薬品濃度としては３０〜５００ｍｇ／Ｌが好ましく、５０〜３００ｍｇ／Ｌがより好ましい。また浸漬時間としては５〜６０分が好ましく、１０〜３０分がより好ましい。 The chemical concentration and the immersion time need to be appropriately adjusted depending on the filtration conditions and the degree of clogging. When the chemical concentration and the immersion time are insufficient, the cleaning is insufficient and the film differential pressure increases, and conversely, when the chemical concentration and the immersion time are excessive, damage to the film becomes a problem. Therefore, the chemical concentration is preferably 30 to 500 mg / L, more preferably 50 to 300 mg / L. Moreover, as immersion time, 5 to 60 minutes are preferable and 10 to 30 minutes are more preferable.
所定時間浸漬させた後、逆洗水供給バルブ４２を開とし、逆洗水供給ポンプ４１を稼動させて、膜モジュール２０の二次側２０ｂにろ過水を供給して、膜モジュール２０にリンス処理を行う。そして、薬品洗浄排水は、逆洗排水排出バルブ２１から系外に排出して、中和処理等の処理を行う。 After soaking for a predetermined time, the backwash water supply valve 42 is opened, the backwash water supply pump 41 is operated, filtered water is supplied to the secondary side 20b of the membrane module 20, and the membrane module 20 is rinsed. I do. Then, the chemical cleaning wastewater is discharged out of the system from the backwash drainage discharge valve 21 and is subjected to processing such as neutralization.
上記薬品洗浄工程を終えた後、原水を膜ろ過処理してろ過水を得る上記膜ろ過工程へと戻り、膜ろ過工程と逆洗工程とを繰り返して水処理を行う。 After finishing the chemical washing step, the raw water is subjected to membrane filtration to return to the membrane filtration step to obtain filtered water, and the membrane filtration step and the backwashing step are repeated to perform water treatment.
この実施形態によれば、逆洗工程の後に、薬品洗浄を行うようにしたので、膜のろ過能力をほぼ初期状態まで回復することができる。また、上述のように、本発明によれば、逆洗による膜の洗浄効果が高いので、薬品洗浄の頻度や、薬品洗浄に用いる薬品濃度を低下することができる。 According to this embodiment, since chemical cleaning is performed after the backwashing step, the filtration ability of the membrane can be recovered to almost the initial state. Further, as described above, according to the present invention, since the effect of cleaning the film by backwashing is high, the frequency of chemical cleaning and the chemical concentration used for chemical cleaning can be reduced.
（実施例１）
図１に示す水処理装置を用いて水処理を行った。膜は、膜面積０．０４ｍ２の膜モジュールを用いた。被処理水は人工原水（濁度１度、ＴＯＣ３ｍｇ／Ｌ）を用いた。高濁度汚濁水は、別途、浄水場にて入手した凝集沈殿汚泥を濁度３０度となるように人工原水に混合して用いた。
運転条件は、被処理水の膜ろ過流速２．５ｍ／ｄ、被処理水のろ過時間３０ｍｉｎ、逆洗流速６．６ｍ／ｄとした。そして、４６回目のろ過工程を終えた後、高濁度汚濁水を通常のろ過工程と同じ条件（ろ過流速２．５ｍ／ｄ、ろ過時間３０ｍｉｎ）にて膜へ通液させ、次いで、逆洗（逆洗流速６．６ｍ／ｄ、逆洗時間１ｍｉｎ）した後、再度上記運転条件で水処理を行った。なお、高濁度汚濁水を膜へ通液させる間隔は、２３．８ｈｒ毎／１回であった。
Example 1
Water treatment was performed using the water treatment apparatus shown in FIG. As the membrane, a membrane module having a membrane area of 0.04 m 2 was used. Artificial raw water (turbidity 1 degree, TOC 3 mg / L) was used as the water to be treated. The high turbidity polluted water was separately used by mixing the coagulated sediment sludge obtained at the water purification plant with artificial raw water so that the turbidity was 30 degrees.
The operating conditions were a membrane filtration flow rate of 2.5 m / d for treated water, a filtration time of 30 minutes for treated water, and a backwash flow rate of 6.6 m / d. After the 46th filtration step, high turbidity polluted water was passed through the membrane under the same conditions as the normal filtration step (filtration flow rate 2.5 m / d, filtration time 30 min), and then backwashed (Backwashing flow velocity 6.6 m / d, backwashing time 1 min), water treatment was performed again under the above operating conditions. The interval at which the highly turbidity polluted water was passed through the membrane was 23.8 hrs / once.
（比較例１）
図１に示す水処理装置を用いて水処理を行った。膜は膜面積０．０４ｍ２の膜モジュールを用いた。被処理水は人工原水（濁度１度、ＴＯＣ３ｍｇ／Ｌ）を用いた。
運転条件は、被処理水の膜ろ過流速２．５ｍ／ｄ、被処理水のろ過時間３０ｍｉｎ、逆洗流速６．６ｍ／ｄとした。
(Comparative Example 1)
Water treatment was performed using the water treatment apparatus shown in FIG. As the membrane, a membrane module having a membrane area of 0.04 m 2 was used. Artificial raw water (turbidity 1 degree, TOC 3 mg / L) was used as the water to be treated.
The operating conditions were a membrane filtration flow rate of 2.5 m / d for treated water, a filtration time of 30 minutes for treated water, and a backwash flow rate of 6.6 m / d.
実施例１、比較例１の運転条件で水処理を３０日間行い、膜の膜差圧変化を測定した。結果を表１にまとめて記す。 Water treatment was performed for 30 days under the operating conditions of Example 1 and Comparative Example 1, and changes in membrane differential pressure were measured. The results are summarized in Table 1.
上記結果より、比較例1の運転条件では、経時で膜差圧が上昇する傾向にあり、水処理開始３０日後には、膜差圧が３５ｋＰａとなった。これに対し、実施例１の運転条件では、運転初期に膜差圧の増加は見られたが、その後は膜差圧の増加を抑制することができ、水処理開始３０日後における膜差圧は２６ｋＰａであった。 From the above results, the membrane differential pressure tends to increase over time under the operating conditions of Comparative Example 1, and the membrane differential pressure became 35 kPa 30 days after the start of water treatment. In contrast, in the operating conditions of Example 1, an increase in the membrane differential pressure was observed in the initial stage of operation, but thereafter the increase in the membrane differential pressure can be suppressed, and the membrane differential pressure after 30 days from the start of water treatment is It was 26 kPa.
（実施例２）
図２に示す水処理装置を用いて水処理を行った。膜は膜面積０．０４ｍ２の膜モジュールを用いた。被処理水は人工原水（濁度１度、ＴＯＣ３ｍｇ／Ｌ）を用いた。薬品洗浄液は次亜塩素酸ナトリウム（薬品濃度１５０ｍｇ／ｍｌ）を用いた。高濁度汚濁水は逆洗排水（濁度６００度）を用いた。
運転条件は、被処理水の膜ろ過流速２．５ｍ／ｄ、被処理水のろ過時間３０ｍｉｎ、逆洗流速６．６ｍ／ｄ、逆洗時間１ｍｉｎとした。そして、４６回目のろ過工程を終えた後、高濁度汚濁水を膜へ通液（ろ過流速２．５ｍ／ｄ、ろ過時間３ｍｉｎ）させ、次いで、逆洗（逆洗流速６．６ｍ／ｄ、逆洗時間１ｍｉｎ）する操作を３回連続して行い、その後、薬品洗浄（薬品浸漬時間２０ｍｉｎ）を行ったのち、再度上記運転条件で水処理を行った。なお、薬品洗浄の間隔は、２４ｈｒ毎／１回であった。
(Example 2)
Water treatment was performed using the water treatment apparatus shown in FIG. As the membrane, a membrane module having a membrane area of 0.04 m 2 was used. Artificial raw water (turbidity 1 degree, TOC 3 mg / L) was used as the water to be treated. Sodium hypochlorite (chemical concentration 150 mg / ml) was used as the chemical cleaning solution. As the high turbidity polluted water, backwash drainage (turbidity: 600 degrees) was used.
The operating conditions were a membrane filtration flow rate of 2.5 m / d for treated water, a filtration time of 30 minutes for treated water, a backwash flow rate of 6.6 m / d, and a backwash time of 1 min. After the 46th filtration step, high turbidity polluted water was passed through the membrane (filtration flow rate 2.5 m / d, filtration time 3 min), and then backwashed (backwash flow rate 6.6 m / d). , Back washing time 1 min) was continuously performed 3 times, and then chemical cleaning (chemical soaking time 20 min) was performed, followed by water treatment again under the above operating conditions. The chemical cleaning interval was every 24 hr / once.
（比較例２）
図２に示す水処理装置を用いて水処理を行った。膜は膜面積０．０４ｍ２の膜モジュールを用いた。被処理水は人工原水（濁度１度、ＴＯＣ３ｍｇ／Ｌ）を用いた。薬品洗浄液は次亜塩素酸ナトリウム（薬品濃度３００ｍｇ／ｍｌ）を用いた。
運転条件は、被処理水の膜ろ過流速２．５ｍ／ｄ、被処理水のろ過時間３０ｍｉｎ、逆洗流速６．６ｍ／ｄ、逆洗時間１ｍｉｎとした。そして、４６回目のろ過工程を終えた後、薬品洗浄（薬品浸漬時間２０ｍｉｎ）を行い、その後再度上記運転条件で水処理を行った。なお、薬品洗浄の間隔は、２４ｈｒ毎／１回であった。
(Comparative Example 2)
Water treatment was performed using the water treatment apparatus shown in FIG. As the membrane, a membrane module having a membrane area of 0.04 m 2 was used. Artificial raw water (turbidity 1 degree, TOC 3 mg / L) was used as the water to be treated. Sodium hypochlorite (chemical concentration 300 mg / ml) was used as the chemical cleaning solution.
The operating conditions were a membrane filtration flow rate of 2.5 m / d for treated water, a filtration time of 30 minutes for treated water, a backwash flow rate of 6.6 m / d, and a backwash time of 1 min. And after finishing the 46th filtration process, the chemical | medical agent washing | cleaning (chemical | medical immersion time 20min) was performed, and the water treatment was again performed on the said operating conditions after that. The chemical cleaning interval was every 24 hr / once.
実施例２、比較例２の運転条件で水処理を３０日間行い、膜の膜差圧変化を測定した。結果を表２にまとめて記す。 Water treatment was performed for 30 days under the operating conditions of Example 2 and Comparative Example 2, and changes in the membrane differential pressure were measured. The results are summarized in Table 2.
上記結果より、実施例２では、比較例２に比べ薬品洗浄に用いる次亜塩素酸ナトリウム注入量を１／２に減少したにもかかわらず、比較例２と同等の洗浄効果が得られ、安定した運転状態を維持することができた。このことより、本発明によれば、薬品洗浄に用いる薬品の濃度や頻度を低減することができる。 From the above results, in Example 2, although the amount of sodium hypochlorite used for chemical cleaning was reduced by half compared to Comparative Example 2, the cleaning effect equivalent to that of Comparative Example 2 was obtained and stable. It was possible to maintain the operating state. From this, according to this invention, the density | concentration and frequency of the chemical | medical agent used for chemical | medical agent washing | cleaning can be reduced.
１〜５：配管
１０：供給水タンク
１１：膜供給水バルブ
１２：運転ポンプ
１３：膜入口バルブ
２０：膜モジュール
２１：逆洗排水排出バルブ
２２：膜出口バルブ
２３：逆洗排水回収バルブ
３０：高濁度汚水貯留槽
３１：高濁度汚水供給バルブ
４０：貯水槽
４１：逆洗水供給ポンプ
４２：逆洗水供給バルブ
５０：薬品タンク
５１：薬品注入ポンプ
５２：薬品注入バルブ
1-5: Pipe 10: Supply water tank 11: Membrane supply water valve 12: Operation pump 13: Membrane inlet valve 20: Membrane module 21: Backwash drainage discharge valve 22: Membrane outlet valve 23: Backwash drainage recovery valve 30: High turbidity sewage storage tank 31: High turbidity sewage supply valve 40: Water storage tank 41: Backwash water supply pump 42: Backwash water supply valve 50: Chemical tank 51: Chemical injection pump 52: Chemical injection valve
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