JP5135676B2 - Operation method of reverse osmosis membrane separator - Google Patents

Operation method of reverse osmosis membrane separator Download PDF

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JP5135676B2
JP5135676B2 JP2005322400A JP2005322400A JP5135676B2 JP 5135676 B2 JP5135676 B2 JP 5135676B2 JP 2005322400 A JP2005322400 A JP 2005322400A JP 2005322400 A JP2005322400 A JP 2005322400A JP 5135676 B2 JP5135676 B2 JP 5135676B2
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望 育野
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Kurita Water Industries Ltd
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本発明は逆浸透膜分離装置(RO装置)の運転方法に係り、特に、脱塩及び/又は有機物除去を行うクリスマスツリー型多段RO装置の膜面閉塞を防止して、長期安定運転を可能とするRO装置の運転方法に関する。   The present invention relates to an operation method of a reverse osmosis membrane separation device (RO device), and in particular, can prevent long-term stable operation by preventing membrane surface blockage of a Christmas tree type multi-stage RO device that performs desalting and / or organic matter removal. The present invention relates to a method for operating an RO device.

RO装置は用水の造水プロセス、食品・医薬用水の製造プロセス、排水回収プロセスなど幅広い分野で使用されている。中でも近年、用排水のコスト低減、環境負荷低減の目的から、排水回収プロセスにおいて、RO装置を使用するケースが急激に増加している。   RO devices are used in a wide range of fields such as fresh water production processes, food / pharmaceutical water production processes, and wastewater recovery processes. In particular, in recent years, the number of cases in which RO devices are used in the wastewater recovery process has been increasing rapidly for the purpose of reducing the cost of wastewater for use and reducing the environmental burden.

通常、RO装置は、供給水に対する水回収率を高める目的から、例えば、図2に示すようなクリスマスツリーと呼ばれる配置をとる。即ち、図2において、逆浸透膜エレメント(ROエレメント)を1本又は複数本(通常1本〜10本程度)内蔵したROベッセル1A,1B,1C,1Dが4機並列配置されてなる第1バンク(ベッセル群をバンクと称す。)1と、ROベッセル2A,2Bが2機並列配置されてなる第2バンク2とでクリスマスツリー型の多段RO装置が構成されている(例えば、特許第3453881号公報)。   Usually, the RO device has an arrangement called a Christmas tree as shown in FIG. 2 for the purpose of increasing the water recovery rate with respect to the supplied water. That is, in FIG. 2, four RO vessels 1A, 1B, 1C, and 1D having one or more reverse osmosis membrane elements (RO elements) (usually about 1 to 10) are arranged in parallel. A Christmas tree-type multi-stage RO apparatus is configured by a bank (a vessel group is referred to as a bank) 1 and a second bank 2 in which two RO vessels 2A and 2B are arranged in parallel (for example, Japanese Patent No. 33483881). Issue gazette).

被処理水、即ち、RO装置の供給水(RO給水)はまず第1バンク1に流入し、透過水と濃縮水とに分離される。続いて第1バンク1の濃縮水は第2バンク2に流入し、ここでも透過水と濃縮水とに分離される。第1バンク1の透過水と第2バンク2の透過水は合流し、後段処理工程に移送される。一方、第2バンク2の濃縮水は系外に放流されるか排水処理設備等に移送される。通常、RO装置におけるクリスマスツリー構造は、要求される水回収率にもよるが、2又は3バンクで構成されることが多い。   The water to be treated, that is, the supply water (RO feed water) of the RO device first flows into the first bank 1 and is separated into permeated water and concentrated water. Subsequently, the concentrated water in the first bank 1 flows into the second bank 2 and is again separated into permeated water and concentrated water. The permeated water of the first bank 1 and the permeated water of the second bank 2 merge and are transferred to the subsequent processing step. On the other hand, the concentrated water in the second bank 2 is discharged out of the system or transferred to a wastewater treatment facility or the like. Usually, the Christmas tree structure in the RO device is often composed of two or three banks, depending on the required water recovery rate.

ところで、RO装置による水処理においては、RO膜として、1.5MPaの運転圧で透過水を得る低圧RO膜から、膜表面の構造をより一層緻密化させることにより、その約半分以下の運転圧(通常0.1〜0.75MPa)で低圧RO膜と同等の透過水量を得ることが可能な超低圧RO膜の使用が主流となってきている。
特許第3453881号公報
By the way, in the water treatment by the RO apparatus, the operating pressure of about half or less is reduced by further densifying the structure of the membrane surface from the low-pressure RO membrane that obtains permeated water at an operating pressure of 1.5 MPa as the RO membrane. The use of an ultra-low pressure RO membrane that can obtain a permeate amount equivalent to that of a low-pressure RO membrane (usually 0.1 to 0.75 MPa) has become mainstream.
Japanese Patent No. 3453881

しかしながら、近年、このように運転圧の低い、従って、わずかな圧力で透過水量を得ることができる超低圧RO膜を用いたクリスマスツリー型多段RO装置、中でもRO給水の導電率が比較的高い排水回収プロセスにおけるクリスマスツリー型多段RO装置において、超低圧RO膜の膜面閉塞等の問題が起こりやすいことが明らかとなった。   However, in recent years, the Christmas tree type multi-stage RO device using an ultra-low pressure RO membrane that can obtain the amount of permeated water at such a low pressure as described above, and in particular, drainage with relatively high conductivity of RO water supply. In the Christmas tree type multi-stage RO apparatus in the recovery process, it has become clear that problems such as blockage of the ultra low pressure RO membrane are likely to occur.

このメカニズムは次の通りである。   This mechanism is as follows.

即ち、RO装置は、上述した如く、水回収率向上の目的から一般にクリスマスツリー構造をとる。その際、後段バンクは前段バンクの濃縮水を給水とするため、給水の導電率が高く、給水の浸透圧が高くなることにより、膜面にかかる膜面有効圧力は極端に低下する。この現象は超低圧RO膜を使用した場合、給水の導電率が高い、後段バンクにいく程顕著に表れる。そして、この場合において、後段バンクにいく程透過水が出なくなるため、処理水の大部分は前段バンクすなわち第1段目のバンクから出ることとなり、この前段バンクでは相対的に濃縮水量が少なくなる。そして、膜面にかかる浸透圧が低い前段バンクにおいて、このように透過水量が極端に多くかつ濃縮水量が低下することにより、濃縮分極が進行し、膜面閉塞及びそれによる透過流束の低下、更には処理水水質の低下が観測されるようになる。一方で、後段バンクにおけるRO膜は利用度が低いものとなる。   That is, as described above, the RO device generally has a Christmas tree structure for the purpose of improving the water recovery rate. At that time, since the latter bank uses the concentrated water of the former bank as feed water, the conductivity of the feed water is high, and the osmotic pressure of the feed water is increased, so that the effective membrane surface pressure on the membrane surface is extremely reduced. This phenomenon becomes more prominent in the downstream bank where the conductivity of the water supply is high when the ultra-low pressure RO membrane is used. In this case, the permeated water does not come out as it goes to the latter bank, so that most of the treated water comes from the former bank, that is, the first bank, and the amount of concentrated water is relatively reduced in this former bank. . And, in the former bank where the osmotic pressure applied to the membrane surface is low, the amount of permeated water is extremely large and the amount of concentrated water is lowered, so that the concentration polarization proceeds, the membrane surface is blocked and the permeation flux is lowered, Furthermore, a decrease in the quality of treated water is observed. On the other hand, the RO membrane in the latter bank is low in utilization.

従って、本発明は、このようなクリスマスツリー構造のRO装置、特に超低圧RO膜を用いたクリスマスツリー型多段RO装置における膜面閉塞を防止して、長期安定運転を可能とするRO装置の運転方法を提供することを目的とする。   Accordingly, the present invention prevents the surface of the RO device having such a Christmas tree structure, particularly a Christmas tree type multi-stage RO device using an ultra-low pressure RO membrane from being blocked, and enables the operation of the RO device which enables long-term stable operation. It aims to provide a method.

本発明(請求項1)の逆浸透膜装置の運転方法は、排水回収プロセスにおいて、逆浸透膜エレメントを収納した逆浸透膜ベッセルを複数個(ただし、最終段は1個でもよい)給水に対し並列的に配置したバンクを複数段有し、前段バンクから排出される濃縮水を後段バンクの給水とする逆浸透膜装置の運転方法において、各逆浸透膜エレメントの透過水量を概ね同等とするとともに、各ベッセルにおける逆浸透膜エレメント1本あたりの透過水量とベッセルあたりの濃縮水量との比が0.3〜0.4となるように運転することを特徴とする。 The operation method of the reverse osmosis membrane device of the present invention (Claim 1) is that the drainage recovery process uses a plurality of reverse osmosis membrane vessels containing reverse osmosis membrane elements (however, the final stage may be one) for water supply. In the operation method of the reverse osmosis membrane device having a plurality of banks arranged in parallel and using the concentrated water discharged from the preceding bank as the supply water for the latter bank, the amount of permeated water of each reverse osmosis membrane element is made substantially equal. The ratio of the amount of permeated water per reverse osmosis membrane element in each vessel to the amount of concentrated water per vessel is 0.3-0 . It is characterized by driving | running so that it may be set to 4 .

請求項2の逆浸透膜装置の運転方法は、請求項1において、透過水量を弁の開度で調整することを特徴とする。   According to a second aspect of the present invention, there is provided a method for operating a reverse osmosis membrane device according to the first aspect, wherein the amount of permeated water is adjusted by the opening of a valve.

請求項3の逆浸透膜装置の運転方法は、請求項2において、前段バンクの透過水量を、前段バンクの透過水配管に設けられた弁の開度で調整し、最終段バンクの透過水量を最終段バンクの濃縮水配管に設けられた弁の開度で調整することを特徴とする。   The operation method of the reverse osmosis membrane device according to claim 3 is the method according to claim 2, wherein the amount of permeated water in the preceding bank is adjusted by the opening degree of a valve provided in the permeate piping of the preceding bank, and the amount of permeated water in the last stage bank is adjusted. It adjusts with the opening degree of the valve provided in the concentrated water piping of the last stage bank.

本発明に従って、各膜エレメント1本あたりの透過水量を概ね同等とし、かつ各ベッセルにおけるROエレメント1本あたりの透過水量とベッセルあたりの濃縮水量との比が0.4以下となるよう調整することにより、膜面閉塞を抑制し、長期安定運転を図ることができる。   In accordance with the present invention, the permeated water amount per membrane element is made substantially equal, and the ratio of the permeated water amount per RO element in each vessel to the concentrated water amount per vessel is adjusted to 0.4 or less. Thus, the membrane surface blockage can be suppressed and long-term stable operation can be achieved.

各膜エレメントあたりの透過水量を同一とする理由は以下の通りである。   The reason why the permeated water amount per membrane element is the same is as follows.

即ち、上述した如く超低圧RO膜を用いたRO装置においては、わずかな圧力で透過水を得ることが可能となるため、膜面にかかる浸透圧が低い前段バンクになる程透過水量が多くなり、膜面閉塞を起こし易く、一方で後段バンクにおけるRO膜は有効利用されなくなる。本発明では、膜エレメント1本あたりの透過水量が同等となるように透過水量を調節する。これにより、全バンクにおけるRO膜を均等に有効利用することが可能となる。   That is, in the RO device using the ultra-low pressure RO membrane as described above, it is possible to obtain the permeated water with a slight pressure. The membrane surface is likely to be blocked, while the RO membrane in the latter bank is not effectively used. In the present invention, the permeated water amount is adjusted so that the permeated water amount per membrane element is equal. As a result, the RO membranes in all banks can be effectively used equally.

また、各ROベッセルにおけるROエレメント1本あたりの透過水量とROベッセルあたりの濃縮水量の比を0.4以下とする理由は以下の通りである。   The reason why the ratio of the permeated water amount per RO element and the concentrated water amount per RO vessel in each RO vessel is 0.4 or less is as follows.

即ち、膜面閉塞物質のRO膜への付着には、膜面に対し垂直にかかる力(透過水)と剪断力(濃縮水)の割合が大きく影響する。   That is, the ratio of the force (permeated water) and the shearing force (concentrated water) applied perpendicularly to the membrane surface greatly affects the adhesion of the membrane surface blocking substance to the RO membrane.

図4は、図3に図示したRO装置を用い、超純水にRO膜面閉塞物質である非イオン性界面活性剤1mg/Lを添加したものを給水として、回収率75%の条件で、日東電工製RO膜「ES−20」を用いたROエレメントを内蔵するROベッセル11に、ROエレメント1本あたりの透過水量を15〜33m/day・本、タンク12への濃縮循環水量を48〜85m/day・本、濃縮ブロー水量を3.75〜8.25m/day・本として通水した時の、膜1本あたりの透過水量と1ROベッセルあたりの濃縮水量の比と、安定膜面透過流束Fに対する初期膜面透過流束Fの割合(F/F)をプロットしたものであるが、この比を0.4以下とすることにより膜面透過流束の低下を顕著に抑制することができることがわかる。 FIG. 4 shows an RO device shown in FIG. 3 and is supplied with ultrapure water added with 1 mg / L of a nonionic surfactant, which is a RO membrane surface blocking substance, under the condition of a recovery rate of 75%. RO vessel 11 incorporating RO element using Nitto Denko RO membrane “ES-20”, permeate amount of water per RO element is 15 to 33 m 3 / day, and concentrated circulating water amount to tank 12 is 48 ~85m 3 / day · present, when the blowdown water was passed through a 3.75~8.25m 3 / day · present, the ratio of permeate flow rate and 1RO concentrated water per vessel per one film, stable The ratio of the initial membrane permeation flux F 0 to the membrane permeation flux F (F / F 0 ) is plotted. By reducing this ratio to 0.4 or less, the membrane permeation flux is reduced. Can be significantly suppressed Hunt.

本発明において、透過水量は弁の開度で調整することが好ましく(請求項2)、特に前段バンクの透過水量は、前段バンクの透過水配管に設けられた弁の開度で調整し、最終段バンクの透過水量は最終段バンクの濃縮水配管に設けられた弁の開度で調整することが好ましい(請求項3)。   In the present invention, the amount of permeate is preferably adjusted by the opening of the valve (Claim 2). In particular, the amount of permeate in the preceding bank is adjusted by the opening of the valve provided in the permeate pipe of the preceding bank, The amount of permeated water in the stage bank is preferably adjusted by the opening degree of a valve provided in the concentrated water pipe of the last stage bank.

以下、図面を参照して本発明のRO装置の運転方法の実施の形態を詳細に説明する。図1は本発明のRO装置の運転方法の実施の形態を示す系統図である。   DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment of a method for operating an RO apparatus of the present invention will be described in detail with reference to the drawings. FIG. 1 is a system diagram showing an embodiment of a method of operating an RO device according to the present invention.

なお、以下において、ROエレメント1本あたりの透過水量を「単位膜透過水量」と称し、ベッセル1個あたりの濃縮水量を「単位ベッセル濃縮水量」と称し、単位膜透過水量と単位ベッセル濃縮水量との比を「膜透過水量/ベッセル濃縮水量比」と称す場合がある。   In the following, the permeated water amount per RO element is referred to as “unit membrane permeated water amount”, the concentrated water amount per vessel is referred to as “unit vessel concentrated water amount”, and unit membrane permeated water amount and unit vessel concentrated water amount This ratio may be referred to as “membrane permeated water amount / Bessel concentrated water amount ratio”.

図1に示すRO装置は、4個のROベッセル1A,1B,1C,1Dが並列配置されて前段の第1バンク(ベッセル群)1が構成され、2個のROベッセル2A,2Bが並列配置されて後段の第2バンク2が構成されている2段のクリスマスツリー型RO装置である。   In the RO apparatus shown in FIG. 1, four RO vessels 1A, 1B, 1C, 1D are arranged in parallel to form a first bank (vessel group) 1 in the previous stage, and two RO vessels 2A, 2B are arranged in parallel. This is a two-stage Christmas tree type RO device in which the second bank 2 in the subsequent stage is configured.

各ROベッセル1A〜1D、2A,2Bには、各々、ROエレメントが内蔵されている。また、各バンク1,2には、給水配管11,14と、透過水配管12,15と、濃縮水配管13,16とが設けられている。   Each RO vessel 1A to 1D, 2A, 2B has a built-in RO element. Each bank 1, 2 is provided with water supply pipes 11, 14, permeated water pipes 12, 15, and concentrated water pipes 13, 16.

なお、ROエレメントは、RO膜により被処理水を透過水と濃縮水とに分離するための最小ユニット(即ち、膜1本)を指し、このROエレメントの1本又は複数本(通常は1〜10本程度)を圧力容器(ベッセル)に収納したものがROベッセルである。   The RO element refers to a minimum unit (that is, one membrane) for separating the water to be treated into permeate and concentrated water by the RO membrane, and one or a plurality (usually 1 to 1) of this RO element. An RO vessel is a container in which about 10) are stored in a pressure vessel (vessel).

第1バンク1においては、給水配管11から分岐した給水分岐管11a,11b,11c,11dが各ROベッセル1A,1B,1C,1Dに接続され、被処理水が各ROベッセル1A〜1Dに並列的に供給される。また、各ベッセル1A〜1DでRO膜を透過した透過水は各々透過水分岐管12a,12b,12c,12dから透過水配管12に集められ、後段の第2バンク2の透過水と共に透過水排出管17を経て系外へ排出される。この透過水配管12には絞り弁AV1と流量計FI−1が設けられている。他方、各ベッセル1A〜1Dの濃縮水は各々濃縮水分岐管13a,13b,13c,13dから濃縮水配管13に集められ、次段の第2バンク2の給水として給水配管14及び給水分岐管14a,14bを経てROベッセル2A,2Bに並列的に供給される。   In the 1st bank 1, the water supply branch pipe 11a, 11b, 11c, 11d branched from the water supply pipe 11 is connected to each RO vessel 1A, 1B, 1C, 1D, and to-be-processed water is parallel to each RO vessel 1A-1D. Supplied. In addition, the permeated water that has passed through the RO membrane in each of the vessels 1A to 1D is collected from the permeated water branch pipes 12a, 12b, 12c, and 12d to the permeated water pipe 12, and discharged along with the permeated water of the second bank 2 in the subsequent stage. It is discharged out of the system through the pipe 17. This permeate pipe 12 is provided with a throttle valve AV1 and a flow meter FI-1. On the other hand, the concentrated water of each of the vessels 1A to 1D is collected from the concentrated water branch pipes 13a, 13b, 13c, and 13d to the concentrated water pipe 13, and supplied to the second bank 2 of the next stage as a water supply pipe 14 and a water supply branch pipe 14a. , 14b and supplied in parallel to the RO vessels 2A, 2B.

第2バンク2のROベッセル2A,2Bにおいても、RO膜を透過した透過水が各々透過水分岐管15a,15bから透過水配管15に集められ、透過水排出管17を経て、第1バンク1のROベッセル1A〜1Dからの透過水と共に系外へ排出される。一方、濃縮水は、各々濃縮水分岐管16a,16bから濃縮水配管16に集められ、系外へ排出される。この濃縮水配管16には絞り弁V2と流量計FI−2が設けられている。   Also in the RO vessels 2A, 2B of the second bank 2, the permeated water that has permeated through the RO membrane is collected from the permeated water branch pipes 15a, 15b to the permeated water pipe 15, respectively, via the permeated water discharge pipe 17, and then into the first bank 1. Are discharged out of the system together with permeated water from the RO vessels 1A to 1D. On the other hand, the concentrated water is collected from the concentrated water branch pipes 16a and 16b to the concentrated water pipe 16 and discharged out of the system. The concentrated water pipe 16 is provided with a throttle valve V2 and a flow meter FI-2.

本発明において、このようなRO装置において、各単位膜透過水量を概ね同等とすると共に、膜透過水量/ベッセル濃縮水量比が0.4以下となるように各段のバンクの透過水量を調整する。   In the present invention, in such an RO apparatus, each unit membrane permeated water amount is made substantially equal, and the permeated water amount of each bank is adjusted so that the membrane permeated water amount / Bessel concentrated water amount ratio is 0.4 or less. .

即ち、図1において、各単位膜透過水量が概ね同等となると共に膜透過水量/ベッセル濃縮水量比が0.4以下となるように、透過水配管12に設けられた絞り弁AV1と濃縮水配管16に設けられた絞り弁V2の開度を調整する。   That is, in FIG. 1, the throttle valve AV1 provided in the permeate water pipe 12 and the concentrate water pipe so that each unit membrane permeate water quantity is substantially equal and the ratio of the membrane permeate water quantity / Bessel concentrate water quantity ratio is 0.4 or less. 16 adjusts the opening degree of the throttle valve V2.

なお、各バンクにおいては、複数のROベッセルが並列に配置されているため、これにより、いずれのROベッセルからも同じ透過水量が得られるようになる。当該透過水量は、1ROベッセル内に収納された複数のROエレメントの合計の透過水量である。そして、このように絞り弁AV1,V2の開度を設定し、給水ポンプPを作動させて、被処理水を配管11から、配管11a〜11dを経て第1バンク1のROベッセル1A〜1Dに加圧供給し、透過水を配管12a〜12d,12,17を経て系外へ排出する。一方、濃縮水は配管13a〜13d,13,14,14a,14bを経て第2バンク2のROベッセル2A,2Bに導入し、透過水を配管15a,15b,15,17を経て系外へ排出する。第2バンク2の濃縮水は配管16a,16b,16より系外へ排出される。 In each bank, since a plurality of RO vessels are arranged in parallel, the same permeated water amount can be obtained from any RO vessel. The permeated water amount is the total permeated water amount of a plurality of RO elements housed in one RO vessel. Then, set the opening degree of the thus throttle valve AV1, V2, by operating the water supply pump P 1, the treated water from the pipe 11, RO vessel 1A~1D the first bank 1 through a pipe 11a~11d The permeated water is discharged out of the system through the pipes 12a to 12d, 12, and 17. On the other hand, the concentrated water is introduced into the RO vessels 2A and 2B of the second bank 2 through the pipes 13a to 13d, 13, 14, 14a and 14b, and the permeate is discharged out of the system through the pipes 15a, 15b, 15, and 17. To do. The concentrated water in the second bank 2 is discharged out of the system through the pipes 16a, 16b, and 16.

なお、濃縮水は放流又は後段の排水処理装置に送給される。透過水は更に後段の処理装置に送給される。   The concentrated water is discharged or sent to a wastewater treatment device at the subsequent stage. The permeated water is further fed to a subsequent processing device.

本発明において、「概ね同等」とは、各単位膜透過水量から求めた平均値に対して、各々の単位膜透過水量がその平均値の0.9〜1.1倍の範囲内に入ることを指す。   In the present invention, “substantially equivalent” means that each unit membrane permeate amount falls within a range of 0.9 to 1.1 times the average value with respect to the average value obtained from each unit membrane permeate amount. Point to.

また、膜透過水量/ベッセル濃縮水量比が過度に小さくても膜面透過流束の維持効果に大差はないにもかかわらず、水回収率が大きく低下することから、膜透過水量/ベッセル濃縮水量比は0.3〜0.4とする。 In addition, even if the ratio of membrane permeate / vessel concentrated water is too small, the water recovery rate is greatly reduced despite the fact that there is no significant difference in the membrane permeation flux maintenance effect. Membrane permeate / vessel concentrated water The ratio is 0 . It shall be the 3 to 0.4.

なお、図1においては、第1バンクに4個のROベッセルが並列配置され、第2バンクに2個のROベッセルが設けられたクリスマスツリー型RO装置を示したが、本発明が適用されるRO装置は何ら図1の構成のものに限定されない。バンク数やベッセル数には特に制限はないが、バンクの段数は通常2段又は3段である。ただし、4段以上の多段構成であっても良いことは言うまでもない。また、各段のバンクのROベッセル数は、処理水量とROベッセルの処理能力に応じて適宜設定されるが、一般的には上流側ほど多く、下流側ほど少なくなる。通常、2段の場合は第1バンクのベッセル数:第2バンクのベッセル数=2:1の割合でベッセル数が設定され、3段の場合は、第1バンクのベッセル数:第2バンクのベッセル数:第3バンクのベッセル数=4:2:1の割合でベッセル数が設定されることが多い。最終段のベッセル数は1個である場合もある。   Although FIG. 1 shows a Christmas tree-type RO device in which four RO vessels are arranged in parallel in the first bank and two RO vessels are provided in the second bank, the present invention is applied. The RO device is not limited to the configuration shown in FIG. The number of banks and the number of vessels are not particularly limited, but the number of bank stages is usually two or three. However, it goes without saying that a multi-stage configuration of four or more stages may be used. Further, the number of RO vessels in each bank is appropriately set according to the amount of treated water and the processing capacity of the RO vessel, but in general, the number is larger on the upstream side and smaller on the downstream side. Normally, in the case of two stages, the number of vessels in the first bank: the number of vessels in the second bank = 2: 1 is set. In the case of three stages, the number of vessels in the first bank: second bank The number of vessels is often set at a ratio of the number of vessels: the number of vessels in the third bank = 4: 2: 1. The number of vessels in the final stage may be one.

いずれの場合も、前述の如く、各ROベッセルには、ROエレメントが内蔵されており、1ベッセルにROエレメントが1本又は複数本内蔵されている。   In any case, as described above, each RO vessel has a built-in RO element, and one vessel contains one or more RO elements.

各バンク(ベッセル群)には、給水配管と、透過水配管と、濃縮水配管とが設けられている。そして、各バンクにおいて、給水配管から分岐した給水分岐管が各ROベッセルに接続され、被処理水が各ベッセルに並列的に供給される。また、各ベッセルで膜を透過した透過水は透過水配管に集められ、排出される。他方、各ベッセルの濃縮水は濃縮水配管に集められ、次段のバンクの給水として、次段の給水配管に送られる。次段においても同様に水が流れ、RO処理される。   Each bank (vessel group) is provided with a water supply pipe, a permeate pipe, and a concentrated water pipe. And in each bank, the feed water branch pipe branched from the feed water pipe is connected to each RO vessel, and to-be-processed water is supplied to each vessel in parallel. Further, the permeated water that has passed through the membrane in each vessel is collected in a permeated water pipe and discharged. On the other hand, the concentrated water of each vessel is collected in the concentrated water pipe and sent to the next-stage water supply pipe as the water supply for the next-stage bank. In the next stage, water flows in the same manner and RO treatment is performed.

透過水量は、各バンクの透過水配管に設けた絞り弁の開度を調整することにより調整することが好ましいが、最終段のバンクにおいては、濃縮水配管に設けた絞り弁の開度を調整して透過水量を間接的に調整することが好ましい。濃縮水側の弁開度の調整により、運転圧力を調整して透過水量と水回収率を所望の値に近づけるようにすることができる。   The amount of permeated water is preferably adjusted by adjusting the opening of the throttle valve provided in the permeate pipe of each bank. However, in the final bank, the opening of the throttle valve provided in the concentrated water pipe is adjusted. Thus, it is preferable to indirectly adjust the amount of permeated water. By adjusting the valve opening on the concentrated water side, the operating pressure can be adjusted so that the permeated water amount and the water recovery rate are close to desired values.

本発明のRO装置に設けられるRO膜としては、通常のRO膜、ルーズRO膜、NF膜等、脱塩可能な分離膜であれば良く、特に制限はない。   The RO membrane provided in the RO device of the present invention is not particularly limited as long as it is a separation membrane that can be desalted, such as a normal RO membrane, a loose RO membrane, and an NF membrane.

RO膜の形状としてはスパイラル型、中空糸型等各種のものが挙げられ、また、その材質としても特に制限はなく、ポリアミド、酢酸セルロース、ポリビニルアルコール等が挙げられる。   Examples of the shape of the RO membrane include various types such as a spiral type and a hollow fiber type, and the material thereof is not particularly limited, and examples thereof include polyamide, cellulose acetate, and polyvinyl alcohol.

絞り弁は手動弁、自動弁のいずれでも良いが、自動弁であれば流量計と連動して自動的に開路調整することも可能である。この絞り弁、流量計設置の順序は特に限定しない。また、絞り弁、流量計の設置は各バンク透過水合流部に設置しても良く、各ベッセル毎に設置しても良い。   The throttle valve may be either a manual valve or an automatic valve, but if it is an automatic valve, it is possible to automatically adjust the opening in conjunction with the flow meter. The order of installing the throttle valve and the flow meter is not particularly limited. Further, the throttle valve and the flow meter may be installed at each bank permeate merging section, or may be installed for each vessel.

以下に実施例及び比較例を挙げて本発明をより具体的に説明する。
(実施例1)
TOC濃度5mg/L,電気伝導率300mS/mの液晶工場総合排水を凝集・浮上・濾過で前処理した後、図1に示すRO装置に25m/hr、回収率80%の条件で通水して処理した。各ROベッセル1A〜1D,2A,2BのROエレメントとしては超低圧RO膜であるES−20(日東電工製)を用い、各々4本充填した。
Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.
Example 1
After pretreatment of liquid crystal factory general wastewater with a TOC concentration of 5 mg / L and electrical conductivity of 300 mS / m by coagulation, flotation and filtration, water was passed through the RO device shown in FIG. 1 under the conditions of 25 m 3 / hr and recovery rate of 80%. And processed. As RO elements of each of the RO vessels 1A to 1D, 2A, and 2B, ES-20 (manufactured by Nitto Denko) that is an ultra-low pressure RO membrane was used, and four RO elements were filled.

第1バンク1の透過水配管12に設けた絞り弁AV1と第2バンク2の濃縮水配管16に設けた絞り弁V2の開度を調整して、各バンク1,2の透過水量及び濃縮水量が表1に示す量となるように制御し、各バンクともに膜面透過流束が0.5m/m・dayとなるように運転を行った。 By adjusting the opening degree of the throttle valve AV1 provided in the permeate water pipe 12 of the first bank 1 and the throttle valve V2 provided in the concentrate water pipe 16 of the second bank 2, the amount of permeated water and the amount of concentrated water of each bank 1 and 2 are adjusted. Was controlled so as to be the amount shown in Table 1, and each bank was operated so that the membrane surface permeation flux was 0.5 m 3 / m 2 · day.

このときのRO装置全体の初期膜面透過流速に対する膜面透過流束の比の経時変化を図5に示した。   FIG. 5 shows the change with time in the ratio of the membrane surface permeation flux to the initial membrane surface permeation flow velocity of the entire RO device at this time.

(比較例1)
第1バンクの透過水配管12に絞り弁を設けず、表1に示す透過水量及び濃縮水量で運転を行ったこと以外は実施例1と同一条件で処理を行った。このときのRO装置全体の初期膜面透過流速に対する膜面透過流束の比の経時変化を図5に示した。
(Comparative Example 1)
The treatment was performed under the same conditions as in Example 1 except that the permeated water pipe 12 of the first bank was not provided with a throttle valve and was operated with the permeated water amount and the concentrated water amount shown in Table 1. FIG. 5 shows the change with time in the ratio of the membrane surface permeation flux to the initial membrane surface permeation flow velocity of the entire RO device at this time.

Figure 0005135676
Figure 0005135676

図5より明らかなように、単位膜透過水量を略同等とすると共に、膜透過水量/ベッセル濃縮水量比を0.4以下とした実施例1では、通水開始から2ヶ月経過しても膜面透過流束は低下しなかったのに対し、このような制御を行わなかったために、第1バンクから大量の透過水が出た比較例1においては、通水開始1ヶ月で初期膜面透過流束の90%、2ヶ月で75%にまで低下した。   As is clear from FIG. 5, in Example 1 in which the unit membrane permeated water amount was made substantially equal, and the membrane permeated water amount / Bessel concentrated water amount ratio was 0.4 or less, the membrane even after 2 months had passed since the start of water flow. The surface permeation flux did not decrease, but such control was not performed. Therefore, in Comparative Example 1 in which a large amount of permeated water came out from the first bank, the initial membrane surface permeation occurred one month after the start of water flow. It decreased to 90% of the flux and 75% in 2 months.

本発明のRO装置の運転方法の実施の形態を示す系統図である。It is a systematic diagram which shows embodiment of the operating method of RO apparatus of this invention. 一般的なクリスマスツリー型RO装置の構成を示す系統図である。It is a systematic diagram which shows the structure of a general Christmas tree type RO apparatus. 実験に用いたRO装置の系統図である。It is a systematic diagram of the RO apparatus used for experiment. 膜透過水量/ベッセル濃縮水量比とRO装置全体の初期膜面透過流速に対する膜面透過流束の比との関係を示すグラフである。It is a graph which shows the relationship between a membrane permeated water amount / Bessel concentrated water amount ratio and the ratio of the membrane surface permeation flux with respect to the initial membrane surface permeation flow velocity of the RO device as a whole. 実施例1及び比較例1におけるRO装置全体の初期膜面透過流速に対する膜面透過流束の比を示すグラフである。It is a graph which shows the ratio of the membrane surface permeation flux with respect to the initial membrane surface permeation | transmission flow velocity of the whole RO apparatus in Example 1 and Comparative Example 1.

符号の説明Explanation of symbols

1 第1バンク(第1ROベッセル群)
2 第2バンク(第2ROベッセル群)
1A,1B,1C,1D,2A,2B ROベッセル
1 First bank (first RO vessel group)
2 Second bank (second RO vessel group)
1A, 1B, 1C, 1D, 2A, 2B RO vessel

Claims (3)

排水回収プロセスにおいて、逆浸透膜エレメントを収納した逆浸透膜ベッセルを複数個(ただし、最終段は1個でもよい)給水に対し並列的に配置したバンクを複数段有し、前段バンクから排出される濃縮水を後段バンクの給水とする逆浸透膜装置の運転方法において、
各逆浸透膜エレメントの透過水量を概ね同等とするとともに、各ベッセルにおける逆浸透膜エレメント1本あたりの透過水量とベッセルあたりの濃縮水量との比が0.3〜0.4となるように運転することを特徴とする逆浸透膜装置の運転方法。
In the wastewater recovery process, there are a plurality of banks in which a plurality of reverse osmosis membrane vessels containing reverse osmosis membrane elements are arranged in parallel to the water supply (however, the final stage may be one) and discharged from the preceding bank. In the operation method of the reverse osmosis membrane device using the concentrated water as the feed water for the latter bank,
While the permeated water amount of each reverse osmosis membrane element is made substantially equal, the ratio of the permeated water amount per reverse osmosis membrane element in each vessel to the concentrated water amount per vessel is 0.3-0 . 4. A method for operating a reverse osmosis membrane device, wherein the operation is performed so as to be 4 .
請求項1において、透過水量を弁の開度で調整することを特徴とする逆浸透膜装置の運転方法。   2. The method of operating a reverse osmosis membrane device according to claim 1, wherein the amount of permeated water is adjusted by the opening of the valve. 請求項2において、前段バンクの透過水量を、前段バンクの透過水配管に設けられた弁の開度で調整し、最終段バンクの透過水量を最終段バンクの濃縮水配管に設けられた弁の開度で調整することを特徴とする逆浸透膜装置の運転方法。   In claim 2, the amount of permeated water in the preceding bank is adjusted by the opening degree of the valve provided in the permeated water piping of the preceding bank, and the amount of permeated water in the last stage bank is adjusted by the valve provided in the concentrated water piping of the last bank. A method for operating a reverse osmosis membrane device, characterized by adjusting the opening degree.
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