JPH09323090A - Washing method of water treatment device - Google Patents
Washing method of water treatment deviceInfo
- Publication number
- JPH09323090A JPH09323090A JP16532396A JP16532396A JPH09323090A JP H09323090 A JPH09323090 A JP H09323090A JP 16532396 A JP16532396 A JP 16532396A JP 16532396 A JP16532396 A JP 16532396A JP H09323090 A JPH09323090 A JP H09323090A
- Authority
- JP
- Japan
- Prior art keywords
- water
- washing
- metal particles
- cleaning
- air
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Landscapes
- Treatment Of Water By Oxidation Or Reduction (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、水処理装置の洗浄
方法に関する。さらに詳しくは、本発明は、鉄金属粒子
の充填層に通水して水中の不純物を還元処理する水処理
装置において、洗浄水の使用量が少なく、洗浄に要する
時間が短く、しかも鉄金属粒子の表面に付着した汚染物
質を効率よく除去することができる水処理装置の洗浄方
法に関する。TECHNICAL FIELD The present invention relates to a method for cleaning a water treatment device. More specifically, the present invention relates to a water treatment device for reducing impurities in water by passing water through a packed bed of iron metal particles, in which a small amount of washing water is used, the time required for washing is short, and the iron metal particles are TECHNICAL FIELD The present invention relates to a method for cleaning a water treatment device capable of efficiently removing contaminants attached to the surface of water.
【０００２】[0002]
【従来の技術】石炭又は石油を燃焼した際に発生する排
ガスの脱硫装置から排出される排煙脱硫排水は、重金
属、非金属類などの種々の有害物質を含有するので、排
煙脱硫排水よりこれらの有害物質を除去する必要があ
る。排煙脱硫排水の水質は、燃料の燃焼の効率化や、排
煙脱硫方式の改良により変化し、水質の変化に対応した
排煙脱硫排水の処理方法が必要とされている。排水にペ
ルオキソ硫酸、ヨウ素酸、セレン酸などが含まれている
場合は、これらの除去は容易ではなかったが、本発明者
らは先に、これらの有害物質を含む排水のpHを５以下に
調整して鉄金属と接触させたのち、凝集処理及び固液分
離を行うことにより、排水中のペルオキソ硫酸、ヨウ素
酸、セレン酸などが溶出した２価の鉄イオンによって還
元され、さらに、凝集処理により水中に溶解している鉄
イオンを水不溶性の水酸化鉄として沈殿させるとき、重
金属、フッ素などの有害物質も同時に効率的に除去され
ることを見いだした。排水を鉄金属と接触させる方法と
しては、米国特許第４,４０５,４６４号明細書、米国特
許第５,２００,０８２号明細書などに提案されている、
反応槽において排水に鉄金属微粒子を添加して撹拌する
撹拌接触法と、特開平７−２５０２号公報などに提案さ
れている、排水を鉄金属の充填層に通水する通水接触法
が知られている。撹拌接触法は、充填層の洗浄操作は不
要であるが、還元反応が十分でなく、排水中の有害物質
の除去が通水接触法にくらべて劣る上に、鉄金属微粒子
の添加量や、鉄金属微粒子を均一に分散させるための撹
拌強度を管理したり、分散した鉄金属微粒子の流出を防
止するなど、運転管理上の問題が多い。これに対して、
鉄金属粒子の充填層に通水する通水接触法は、運転管理
が比較的容易であり、通水初期には排水中の有害物質が
効率的に除去されるが、長期間通水を続けると鉄金属の
表面に汚染物質が付着したり、目詰まりを生じたりし
て、排水処理効率が低下するという問題がある。長期間
の通水による汚染の問題を回避するために、鉄線材を繊
維状に束ねたものを用いる試みがなされているが、還元
反応を十分に行うためには排水を循環させる必要がある
など、実用化は困難である。このため、本発明者らは、
鉄金属粒子表面に付着した汚染物質を容易に除去し、安
定した排水処理を継続して行うことを可能とする水処理
装置の洗浄方法の研究を行った。2. Description of the Related Art Flue gas desulfurization wastewater discharged from a desulfurization device for exhaust gas generated when coal or petroleum is burned contains various harmful substances such as heavy metals and non-metals. It is necessary to remove these harmful substances. The water quality of flue gas desulfurization effluent changes due to the efficiency of fuel combustion and the improvement of flue gas desulfurization system, and there is a need for a method of treating flue gas desulfurization wastewater that corresponds to the change in water quality. When the wastewater contains peroxosulfuric acid, iodic acid, selenate, etc., it was not easy to remove them. However, the present inventors previously set the pH of the wastewater containing these harmful substances to 5 or less. After adjusting and contacting with iron metal, by performing coagulation treatment and solid-liquid separation, peroxosulfuric acid, iodic acid, selenate, etc. in the wastewater are reduced by the eluted divalent iron ions, and further coagulation treatment It was found that when iron ions dissolved in water are precipitated as water-insoluble iron hydroxide, harmful substances such as heavy metals and fluorine are efficiently removed at the same time. As a method of contacting waste water with ferrous metal, it is proposed in US Pat. No. 4,405,464, US Pat. No. 5,200,082, and the like.
A stirring contact method in which iron metal fine particles are added to waste water in a reaction tank and stirred is known, and a water contact method in which waste water is passed through a packed bed of iron metal is proposed, such as JP-A-7-2502. Has been. The stirring contact method does not require a washing operation of the packed bed, but the reduction reaction is not sufficient, the removal of harmful substances in wastewater is inferior to the water contact method, and the addition amount of iron metal fine particles and There are many operational management problems such as controlling the stirring strength for uniformly dispersing the iron metal particles and preventing the dispersed iron metal particles from flowing out. On the contrary,
The water contact method, in which water is passed through the packed bed of ferrous metal particles, is relatively easy to operate and manage, and the harmful substances in the wastewater are efficiently removed in the early stages of water passage, but water is continued for a long time. There is a problem that pollutants adhere to the surface of iron metal and clogging occurs, and the efficiency of wastewater treatment decreases. In order to avoid the problem of pollution due to long-term water flow, attempts have been made to use a bundle of iron wire rods in the form of fibers, but it is necessary to circulate wastewater in order to carry out the reduction reaction sufficiently. , Practical application is difficult. Therefore, we have
A study was conducted on a cleaning method for a water treatment device that makes it possible to easily remove pollutants adhering to the surface of iron metal particles and continue stable wastewater treatment.
【０００３】[0003]
【発明が解決しようとする課題】本発明は、鉄金属粒子
の充填層に通水して排水中の不純物を還元処理する水処
理装置において、鉄金属粒子の表面に付着した汚染物質
を容易に剥離、除去することができ、長期間にわたり安
定して排水中の有害物質を除去することができる水処理
装置の洗浄方法を提供することを目的としてなされたも
のである。DISCLOSURE OF THE INVENTION The present invention provides a water treatment device for reducing impurities in wastewater by passing water through a packed bed of iron metal particles to easily remove contaminants adhering to the surface of the iron metal particles. The object of the present invention is to provide a method for cleaning a water treatment device, which can be peeled off and removed, and which can stably remove harmful substances in wastewater over a long period of time.
【０００４】[0004]
【課題を解決するための手段】本発明者らは、上記の課
題を解決すべく鋭意研究を重ねた結果、鉄金属粒子の充
填層に洗浄水を通水して洗浄したのち、洗浄水及び空気
の混合流を上向流で供給して洗浄することにより、鉄金
属粒子の表面に付着した汚染物質を効率的に剥離、除去
し得ることを見いだし、この知見に基づいて本発明を完
成するに至った。すなわち、本発明は、（１）鉄金属粒
子の充填層に通水して排水中の不純物を還元処理する水
処理装置において、充填層に洗浄水を通水して洗浄した
のち、さらに洗浄水及び空気の混合流を上向流で供給
し、鉄金属粒子の充填層の汚染物質を除去することを特
徴とする水処理装置の洗浄方法、を提供するものであ
る。さらに、本発明の好ましい態様として、（２）洗浄
水の通水速度が、ＬＶ＝３０〜１５０ｍ・hr-1である第
(１)項記載の水処理装置の洗浄方法、（３）洗浄水の通
水を、１〜５分間行う第(１)項又は第(２)項記載の水処
理装置の洗浄方法、（４）洗浄水及び空気の混合流の供
給において、洗浄水の供給速度が、ＬＶ＝３０〜１５０
ｍ・hr-1である第(１)項、第(２)項又は第(３)項記載の
水処理装置の洗浄方法、（５）洗浄水及び空気の混合流
の供給において、空気の供給量が、鉄金属粒子の充填層
に対し、体積比で１分間に０.１〜１０倍量である第
(１)項、第(２)項、第(３)項又は第(４)項記載の水処理
装置の洗浄方法、（６）洗浄水及び空気の混合流の供給
を、１〜５分間行う第(１)項、第(２)項、第(３)項、第
(４)項又は第(５)項記載の水処理装置の洗浄方法、
（７）洗浄水及び空気の混合流による洗浄を行ったの
ち、さらに洗浄水のみによる洗浄を行う第(１)項、第
(２)項、第(３)項、第(４)項、第(５)項又は第(６)項記
載の水処理装置の洗浄方法、及び、（８）洗浄水及び空
気の混合流による洗浄後の、洗浄水のみによる洗浄にお
ける通水速度が、ＬＶ＝３０〜１５０ｍ・hr-1である第
(７)項記載の水処理装置の洗浄方法、及び、（９）洗浄
水及び空気の混合流による洗浄後の、洗浄水のみによる
洗浄を、１〜５分間行う第(７)項又は第(８)項記載の水
処理装置の洗浄方法、を挙げることができる。Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that after washing water is passed through a packed bed of iron metal particles to wash it, It was found that contaminants adhering to the surface of the iron metal particles can be efficiently separated and removed by supplying a mixed flow of air in an upward flow for cleaning, and the present invention is completed based on this finding. Came to. That is, the present invention relates to (1) in a water treatment apparatus for reducing impurities in waste water by passing water through a packed bed of iron metal particles, after washing water is passed through the packed bed for washing, And a method for cleaning a water treatment device, characterized in that a mixed flow of air is supplied in an upward flow to remove contaminants in a packed bed of iron metal particles. Furthermore, as a preferred embodiment of the present invention, (2) a water flow rate of washing water is LV = 30 to 150 m · hr −1
The method for cleaning a water treatment device according to item (1), (3) the method for cleaning a water treatment device according to item (1) or (2), in which washing water is passed for 1 to 5 minutes, (4) ) In supplying a mixed flow of cleaning water and air, the supply rate of cleaning water is LV = 30 to 150
m · hr −1 , (1), (2) or (3) the method for cleaning a water treatment apparatus according to (3), in the supply of a mixed flow of cleaning water and air, supply of air The amount is 0.1 to 10 times the volume of the packed bed of iron metal particles in 1 minute.
(1), (2), (3) or (4) The method for cleaning a water treatment device according to (4), (6) The supply of a mixed flow of cleaning water and air is performed for 1 to 5 minutes. Item (1), Item (2), Item (3), Item
A method for cleaning the water treatment device according to item (4) or (5),
(7) After cleaning with a mixed flow of cleaning water and air, further cleaning with only cleaning water is performed.
(2), (3), (4), (5) or (6) method of cleaning the water treatment apparatus according to (6), and (8) a mixed flow of cleaning water and air After the washing, the water flow rate in washing with only washing water is LV = 30 to 150 m · hr −1 .
The method for cleaning a water treatment device according to (7), and (9) cleaning with only cleaning water after cleaning with a mixed flow of cleaning water and air is performed for 1 to 5 minutes. The method for cleaning a water treatment device described in the item 8) can be mentioned.
【０００５】[0005]
【発明の実施の形態】本発明方法は、排水を鉄金属粒子
の充填層に通水して、排水中の不純物を還元処理する水
処理装置の洗浄に使用することができる。排水のpHを５
以下に調整し、鉄金属と接触させると、鉄金属より次式
にしたがって２価の鉄イオンが水中に溶出する。 Ｆｅ＋２Ｈ+ → Ｆｅ2+＋Ｈ2 排水中に含まれるペルオキソ硫酸、ヨウ素酸及びセレン
酸は、それぞれ以下に示す式にしたがって２価の鉄イオ
ンと反応し、還元処理される。 Ｓ2Ｏ8 2-＋２Ｆｅ2+ → ２ＳＯ4 2-＋２Ｆｅ3+ ２ＩＯ3 -＋１０Ｆｅ2+＋１２Ｈ+ → Ｉ2＋１０Ｆｅ3+＋
６Ｈ2Ｏ ＳｅＯ4 2-＋６Ｆｅ2+＋８Ｈ+ → Ｓｅ0＋６Ｆｅ3+＋４
Ｈ2Ｏ さらに、酸化還元電位が−４００〜−１００ｍＶの場合
は、次式にしたがって鉄金属とセレン酸の反応が起こ
る。 ＳｅＯ4 2-＋３Ｆｅ＋８Ｈ+ → Ｓｅ0＋３Ｆｅ2+＋４Ｈ2
Ｏ このようにして排水中に含まれる不純物を鉄金属と接触
して還元処理したのち、被処理水にアルカリ剤を添加し
てpHを７以上とすると、水中の鉄イオンは、例えば、下
記の式のように水不溶性の水酸化鉄となってフロックを
形成する。 Ｆｅ2+＋２ＮａＯＨ → Ｆｅ(ＯＨ)2＋２Ｎａ+ Ｆｅ3+＋３ＮａＯＨ → Ｆｅ(ＯＨ)3＋３Ｎａ+ このとき、還元されたセレンのほか、排水中に含まれる
重金属類、懸濁物質、フッ素、ＣＯＤ成分なども同時に
凝集、沈降して分離することができる。pHを５以下に調
整した排水を接触させる鉄金属粒子としては、純鉄、粗
鋼、合金鋼、その他の鉄合金などの粒子を挙げることが
できる。鉄金属が鉄合金であるときは、鉄の含有率が８
５重量％以上であることが好ましい。BEST MODE FOR CARRYING OUT THE INVENTION The method of the present invention can be used for washing a water treatment device for reducing impurities in waste water by passing waste water through a packed bed of iron metal particles. PH of wastewater is 5
When adjusted below and brought into contact with iron metal, divalent iron ions are eluted from the iron metal into water according to the following formula. Fe + 2H + → Fe 2+ + H 2 The peroxosulfuric acid, iodic acid and selenic acid contained in the wastewater react with divalent iron ions according to the formulas shown below and undergo reduction treatment. S 2 O 8 2+ 2Fe 2+ → 2SO 4 2+ 2Fe 3+ 2IO 3+ 10Fe 2+ + 12H + → I 2 + 10Fe 3+ +
6H 2 O SeO 4 2- + 6Fe 2+ + 8H + → Se 0 + 6Fe 3+ +4
H 2 O Further, when the oxidation-reduction potential is −400 to −100 mV, the reaction between iron metal and selenate occurs according to the following equation. SeO 4 2- + 3Fe + 8H + → Se 0 + 3Fe 2+ + 4H 2
O After the impurities contained in the waste water are brought into contact with iron metal and subjected to a reduction treatment in this way, and then an alkaline agent is added to the water to be treated to adjust the pH to 7 or higher, iron ions in the water are, for example, As in the formula, it becomes water-insoluble iron hydroxide and forms flocs. Fe 2+ + 2NaOH → Fe (OH) 2 + 2Na + Fe 3+ + 3NaOH → Fe (OH) 3 + 3Na + At this time, in addition to the reduced selenium, heavy metals, suspended substances, fluorine, and COD components contained in the wastewater. Etc. can be aggregated and settled at the same time to be separated. Examples of the iron metal particles with which the waste water having a pH adjusted to 5 or less is brought into contact include particles of pure iron, crude steel, alloy steel, and other iron alloys. When the iron metal is an iron alloy, the iron content is 8
It is preferably at least 5% by weight.
【０００６】排水と鉄金属粒子の接触は、排水を鉄金属
粒子を充填したカラムなどに通水することにより、効率
的に行うことができる。しかし、鉄金属粒子の充填層に
排水の通水を続けると、汚染物質の鉄金属粒子の表面へ
の付着や、鉄金属粒子の充填層の目詰まりなどが生じ、
排水中の不純物の除去効率が次第に低下してくる。この
ような汚染物質には、鉄金属又は鉄イオンの反応により
生成する酸化鉄、炭化鉄、硫化鉄や、排水中の懸濁物質
などがある。本発明方法においては、鉄金属粒子の充填
層に排水を通水し、不純物の還元処理を続けたのち、排
水の通水を停止し、鉄金属粒子の充填層に洗浄水を通水
して洗浄し、さらに洗浄水及び空気の混合流を上向流で
供給し、鉄金属粒子の表面に付着した汚染物質を剥離、
除去し、あるいは、鉄金属粒子の充填層に目詰まりを起
こしている汚染物質を除去する。本発明方法において、
排水の通水を停止し、鉄金属粒子の充填層に洗浄水を通
水して洗浄することにより、鉄金属粒子の充填層内に存
在する２価又は３価の鉄イオンを含有する水が、鉄イオ
ンを含有しない洗浄水により置換される。鉄金属粒子の
充填層内に鉄イオンが存在する状態で、洗浄水及び空気
の混合流を供給すると懸濁物が発生し、さらに懸濁物に
よって鉄金属粒子の表面も汚染され、不純物の還元処理
効果が十分に回復しない。発生する懸濁物の構造は明ら
かではないが、酸化鉄、水酸化鉄又はＦｅＯ(ＯＨ)など
の構造式により表される鉄化合物と推定される。鉄金属
粒子の充填層に洗浄水を供給して通水したのち、洗浄水
及び空気の混合流を供給すれば、懸濁物が発生すること
はなく、洗浄により不純物の還元処理効果が十分に回復
する。The contact between the waste water and the iron metal particles can be carried out efficiently by passing the waste water through a column filled with the iron metal particles. However, when the drainage water continues to flow through the packed bed of iron metal particles, adhesion of pollutants to the surface of the iron metal particles, clogging of the packed bed of iron metal particles, and the like,
The efficiency of removing impurities in the wastewater gradually decreases. Such pollutants include iron oxides, iron carbides, iron sulfides produced by the reaction of iron metal or iron ions, and suspended substances in wastewater. In the method of the present invention, drainage is passed through the packed bed of iron metal particles, and after continuing the reduction treatment of impurities, the passage of drainage is stopped, and washing water is passed through the packed bed of iron metal particles. Washing, further supplying a mixed flow of washing water and air in an upward flow to remove contaminants adhering to the surface of the ferrous metal particles,
Alternatively, the contaminants that clog the packed bed of iron metal particles are removed. In the method of the present invention,
Water containing divalent or trivalent iron ions present in the packed bed of iron metal particles is removed by stopping the flow of waste water and washing the packed bed of iron metal particles with washing water. , Is replaced by washing water that does not contain iron ions. When iron ions are present in the packed bed of iron metal particles, a mixture of cleaning water and air is supplied to generate a suspension, and the suspension also contaminates the surface of the iron metal particles, reducing impurities. The treatment effect does not recover sufficiently. Although the structure of the generated suspension is not clear, it is presumed to be an iron compound represented by a structural formula such as iron oxide, iron hydroxide or FeO (OH). If washing water is supplied to the packed bed of iron metal particles and water is passed through, and then a mixed flow of washing water and air is supplied, no suspension is generated, and the effect of reducing treatment of impurities is sufficient by washing. Recover.
【０００７】本発明方法において、鉄金属粒子の充填層
に洗浄水を通水するときの流れ方向には特に制限はな
く、上向流又は下向流のいずれともすることができる。
しかし、pHを５以下に調整した排水の通水は、水素ガス
が発生するため通常は上向流で行い、洗浄水及び空気の
混合流の供給も上向流で行うので、設備設計及び運転管
理上からは、鉄金属粒子の充填層への洗浄水の通水も上
向流とすることが好ましい。本発明方法において、洗浄
水の通水速度は、ＬＶ＝３０〜１５０ｍ・hr-1とするこ
とが好ましい。洗浄水の通水速度が３０ｍ・hr-1未満で
あると、洗浄水が層流となって流れ、鉄金属粒子の充填
層内にデッドスペースを生じて、鉄イオンの除去が不十
分となるおそれがある。洗浄水の通水速度が１５０ｍ・h
r-1を超えると、消費する洗浄水の量が多くなる上に、
鉄金属粒子が流出するおそれがある。洗浄水の通水時間
は、１〜５分間とすることが好ましい。洗浄水の通水が
１分間未満であると、鉄イオンの除去が不十分となるお
それがある。洗浄水の通水は、通常は５分間以内で十分
であり、通常は５分間の通水により鉄金属粒子の充填層
内の鉄イオンは除去される。本発明方法においては、鉄
金属粒子の充填層に洗浄水を通水して充填層内の鉄イオ
ンを除去したのち、洗浄水及び空気の混合流を上向流で
供給する。洗浄水及び空気の混合流を上向流として供給
することにより、鉄金属粒子の充填層は展開、流動化す
るとともに、空気の気泡を含む混合流により激しく撹拌
され、鉄金属粒子表面から付着した汚染物質が剥離さ
れ、目詰まりを起こしている汚染物質とともに水流に伴
われて排出される。洗浄水のみによる洗浄では、鉄金属
粒子の充填層が展開しても、汚染物質の剥離効果が小さ
く、多量の洗浄水を消費しても洗浄効果は上がらない。
本発明方法においては、あらかじめ鉄金属粒子の充填層
内の鉄イオンを洗浄水を通水して除去しているので、洗
浄水と混合流を形成するガスとして窒素ガスを使用する
必要はなく、空気を使用しても鉄の酸化物や水酸化物な
どの懸濁物が発生するおそれがない。洗浄水と混合流を
形成するガスとして空気を使用することができるので、
窒素ガスを使用するための初期設備投資及びランニング
コストが不要となり、経済的に水処理装置の洗浄を行う
ことができる。In the method of the present invention, there is no particular limitation on the flow direction when the washing water is passed through the packed bed of iron metal particles, and either upward flow or downward flow can be used.
However, because the hydrogen gas is generated, the drainage water whose pH is adjusted to 5 or less is usually run in an upward flow, and the mixed flow of cleaning water and air is also supplied in an upflow flow. From the viewpoint of management, it is preferable that the flow of washing water to the packed bed of iron metal particles is also upward flow. In the method of the present invention, the flow rate of wash water is preferably LV = 30 to 150 m · hr −1 . When the water flow rate of the wash water is less than 30 m · hr −1 , the wash water flows as a laminar flow, causing dead spaces in the packed bed of iron metal particles, resulting in insufficient removal of iron ions. There is a risk. Wash water flow rate is 150m ・ h
If it exceeds r -1 , the amount of wash water consumed will increase and
Iron metal particles may flow out. The passage time of the wash water is preferably 1 to 5 minutes. If the wash water is passed for less than 1 minute, the removal of iron ions may be insufficient. It is usually sufficient to pass the wash water within 5 minutes, and the iron ions in the packed bed of iron metal particles are usually removed by passing the wash water for 5 minutes. In the method of the present invention, after washing water is passed through the packed bed of iron metal particles to remove iron ions in the packed bed, a mixed flow of the washing water and air is supplied in an upward flow. By supplying a mixed flow of washing water and air as an upward flow, the packed bed of iron metal particles was developed and fluidized, and was vigorously stirred by the mixed flow containing air bubbles and adhered from the surface of the iron metal particles. The pollutants are stripped and discharged together with the clogging pollutants along with the water stream. In the case of washing with only the washing water, even if the packed layer of iron metal particles develops, the effect of removing contaminants is small, and even if a large amount of washing water is consumed, the washing effect does not improve.
In the method of the present invention, since the iron ions in the packed bed of iron metal particles are removed by passing the wash water in advance, it is not necessary to use nitrogen gas as a gas forming a mixed flow with the wash water, Even if air is used, there is no possibility that a suspension of iron oxide or hydroxide will be generated. Since air can be used as a gas to form a mixed flow with the wash water,
Initial equipment investment and running cost for using nitrogen gas are unnecessary, and the water treatment device can be economically cleaned.
【０００８】本発明方法において、洗浄水及び空気の混
合流を形成するための洗浄水の通水速度は、ＬＶ＝３０
〜１５０ｍ・hr-1とすることが好ましい。洗浄水の通水
速度は、鉄金属粒子の大きさなどに応じて選択すること
ができるが、洗浄水及び空気の混合流を供給したとき、
鉄金属粒子の充填層が１０〜５０％展開する程度とする
ことが好ましい。洗浄水の通水速度が３０ｍ・hr-1未満
であると、鉄金属粒子の充填層の展開が少なく、鉄金属
粒子の表面に付着した汚染物質が十分に剥離しないおそ
れがある。洗浄水の通水速度が１５０ｍ・hr-1を超える
と、消費する洗浄水の量が多くなる上に、鉄金属粒子が
流出するおそれがある。本発明方法において、洗浄水及
び空気の混合流を形成するための空気の供給量は、鉄金
属粒子の充填層に対し、体積比で１分間に０.１〜１０
倍量であることが好ましい。空気の供給量が、鉄金属粒
子の充填層に対し体積比で１分間に０.１倍量未満であ
ると、撹拌力が弱く洗浄効果が十分に向上しないおそれ
がある。空気の供給量は、通常は鉄金属粒子の充填層に
対し体積比で１分間に１０倍量で十分であり、それ以上
の空気を供給しても、空気の供給量の増加に見合って洗
浄効果は向上しない。本発明方法においては、洗浄水及
び空気の混合流の供給を１〜５分間行うことが好まし
い。混合流の供給が１分間未満であると、鉄金属粒子の
充填層の洗浄が不十分となるおそれがある。混合流の供
給は、通常は５分間以内で十分であり、それ以上混合流
を供給しても洗浄効果は向上しない。本発明方法におい
ては、洗浄水及び空気の混合流を供給して洗浄を行った
のち、ふたたび洗浄水のみによる洗浄を行うことが好ま
しい。洗浄水のみによる洗浄により、洗浄水及び空気の
混合流によって剥離した汚染物質を洗い流すとともに、
鉄金属粒子の充填層から気泡を追い出すことができ、さ
らに、鉄金属粒子の充填層を均一に形成することができ
る。本発明方法においては、洗浄水及び空気の混合流の
供給後の洗浄水のみによる洗浄は、１〜５分間行うこと
が好ましい。洗浄水のみによる洗浄時間が１分間未満で
あると、剥離した汚染物質の洗い流し及び気泡の追い出
しが不十分となるおそれがある。洗浄水のみによる洗浄
は、通常は５分間以内で十分であり、それ以上洗浄水の
みによる洗浄を継続しても洗浄効果は向上しない。洗浄
水のみによる洗浄を終了したのち、洗浄水の供給を停止
して沈静化することにより、鉄金属粒子の充填層をふた
たび形成する。In the method of the present invention, the flow rate of the wash water for forming the mixed flow of wash water and air is LV = 30.
It is preferably set to 150 m · hr −1 . The flow rate of the wash water can be selected according to the size of the iron metal particles, etc., but when a mixed flow of wash water and air is supplied,
It is preferable that the filling layer of iron metal particles be spread to 10 to 50%. If the water flow rate of the washing water is less than 30 m · hr −1 , the packed layer of iron metal particles is less developed, and the contaminants adhering to the surfaces of the iron metal particles may not be sufficiently peeled off. If the water flow rate of the wash water exceeds 150 m · hr −1 , the amount of wash water consumed will increase and the ferrous metal particles may flow out. In the method of the present invention, the supply amount of air for forming a mixed flow of cleaning water and air is 0.1 to 10 per minute in volume ratio with respect to the packed bed of iron metal particles.
It is preferable that the amount is double. If the amount of air supplied is less than 0.1 times the volume ratio of the packed bed of iron metal particles per minute, the stirring force may be weak and the cleaning effect may not be sufficiently improved. It is usually sufficient to supply 10 times the volume of air per minute to the packed bed of iron metal particles, and even if more air is supplied, cleaning is performed in proportion to the increase in air supply. The effect does not improve. In the method of the present invention, it is preferable to supply a mixed flow of cleaning water and air for 1 to 5 minutes. If the mixed flow is supplied for less than 1 minute, the packed bed of iron metal particles may be insufficiently washed. The supply of the mixed flow is usually sufficient within 5 minutes, and the cleaning effect is not improved even if the mixed flow is further supplied. In the method of the present invention, it is preferable to perform the cleaning by supplying a mixed flow of the cleaning water and the air, and then perform the cleaning only with the cleaning water again. By washing only with wash water, the contaminants that have separated due to the mixed flow of wash water and air are washed away,
Bubbles can be expelled from the packed layer of iron metal particles, and the packed layer of iron metal particles can be formed uniformly. In the method of the present invention, it is preferable that the cleaning with only the cleaning water after the supply of the mixed flow of the cleaning water and the air is performed for 1 to 5 minutes. If the cleaning time with the cleaning water alone is less than 1 minute, the peeled contaminants may be washed out and bubbles may not be expelled sufficiently. The washing with the washing water alone is usually sufficient within 5 minutes, and the washing effect is not improved even if the washing with only the washing water is continued. After the cleaning with only the cleaning water is completed, the supply of the cleaning water is stopped to calm down, so that the packed layer of iron metal particles is formed again.
【０００９】図１は、本発明の水処理装置の洗浄方法の
説明図である。本図に示す水処理装置は、円筒状のカラ
ム１の底部に排水、洗浄水及び空気の導入口２を備え、
上部に還元処理水及び洗浄水のための水排出口３を備え
ている。カラムの下部には砂利を充填して支持床４と
し、支持床の上に多孔板５を取り付け、さらにその上に
鉄金属粒子を充填して鉄金属粒子の充填層６を形成す
る。カラムの頭部には多孔板７を取り付け、還元処理時
に発生する水素ガス及び洗浄時に供給する空気の排出口
とする。排水の還元処理においては、pHを５以下、好ま
しくはpHを２〜３に調整した排水を導入口より供給し、
鉄金属粒子の充填層において、排水中に含まれるペルオ
キソ硫酸、ヨウ素酸、セレン酸などの不純物を還元処理
する。排水は上向流として導入されるので、還元処理に
際して発生する水素ガスは、水流とともに上方へ移動
し、カラム頭部の多孔板より排出される。水排出口より
流出する還元処理水は、さらに凝集沈澱設備に導き、ア
ルカリ剤を添加してpH７以上に調整し、必要に応じてさ
らに高分子凝集剤などを添加して凝集沈澱処理を行って
処理水を得る。一定時間経過後、あるいは、処理水中の
不純物が増加する傾向が認められたとき、水処理装置の
洗浄を行う。水処理装置の洗浄を行うためには、排水の
供給を停止し、導入口から洗浄水を通水することによ
り、鉄金属粒子の充填層内の水中に溶出している鉄イオ
ンを洗い流し、除去する。次いで、鉄金属粒子の充填層
に洗浄水及び空気の混合流を供給することにより、鉄金
属粒子の充填層を展開、流動化する。鉄金属粒子の充填
層の展開、流動化により、鉄金属粒子の表面に付着した
汚染物質は剥離され、目詰まりを起こしていた汚染物質
とともに、水流に伴われて水排出口より排出される。洗
浄水及び空気の混合流を所定時間供給したのち、必要に
応じて空気の供給のみを停止し、洗浄水のみによる洗浄
を行うことができる。洗浄水のみによる洗浄を行うこと
により、剥離した汚染物質を完全に洗い流すとともに、
鉄金属粒子の充填層から気泡を追い出す。洗浄水のみに
よる洗浄を行ったのち、洗浄水の供給を停止し、鉄金属
粒子を沈静化して充填層を形成する。その後、pH調整を
行った排水を導入口より供給し、還元処理を再開する。 本発明方法によれば、少ない量の洗浄水を用い、窒素ガ
スのような不活性ガスを使用することなく、鉄金属粒子
の充填層の洗浄を効率的に行うことができ、長期間にわ
たって安定して排水中の不純物の還元処理を行うことが
できる。FIG. 1 is an explanatory view of a cleaning method for a water treatment device according to the present invention. The water treatment device shown in this figure is provided with an inlet 2 for drainage, washing water and air at the bottom of a cylindrical column 1.
A water outlet 3 for reducing treated water and washing water is provided on the upper part. The lower part of the column is filled with gravel to form a support bed 4, a perforated plate 5 is attached on the support bed, and iron metal particles are further packed on the porous plate 5 to form a packed bed 6 of iron metal particles. A perforated plate 7 is attached to the head of the column to serve as an outlet for hydrogen gas generated during the reduction process and air supplied during the cleaning. In the reduction treatment of the waste water, the waste water whose pH is adjusted to 5 or less, preferably pH 2 to 3, is supplied from the inlet,
Impurities such as peroxosulfuric acid, iodic acid, and selenate contained in the waste water are reduced in the packed bed of iron metal particles. Since the waste water is introduced as an upward flow, the hydrogen gas generated during the reduction process moves upward together with the water flow and is discharged from the perforated plate at the column head. The reduction treated water flowing out from the water discharge port is further led to a coagulation-precipitation facility, an alkaline agent is added to adjust the pH to 7 or more, and a macromolecular coagulant or the like is further added for coagulation-precipitation treatment. Obtain treated water. After a certain period of time, or when impurities in the treated water tend to increase, the water treatment equipment is washed. In order to wash the water treatment equipment, stop the supply of waste water and pass the wash water through the inlet to wash out and remove the iron ions eluted in the water in the packed bed of iron metal particles. To do. Next, a mixed flow of washing water and air is supplied to the packed bed of iron metal particles to expand and fluidize the packed bed of iron metal particles. Due to the development and fluidization of the packed bed of iron metal particles, the pollutants adhering to the surfaces of the iron metal particles are peeled off, and the pollutants that have been clogged are discharged from the water outlet along with the water flow. After supplying a mixed flow of cleaning water and air for a predetermined time, it is possible to stop only the supply of air as needed and perform cleaning with only cleaning water. By cleaning with only cleaning water, the contaminants that have peeled off can be completely washed away, and
Bubbles are expelled from the packed bed of ferrous metal particles. After performing the cleaning with only the cleaning water, the supply of the cleaning water is stopped and the ferrous metal particles are calmed down to form the packed bed. After that, the pH-adjusted wastewater is supplied from the inlet, and the reduction treatment is restarted. According to the method of the present invention, a small amount of cleaning water can be used, and the packed bed of iron metal particles can be efficiently cleaned without using an inert gas such as nitrogen gas, which is stable for a long period of time. Then, reduction treatment of impurities in the wastewater can be performed.
【００１０】[0010]
【実施例】以下に、実施例を挙げて本発明をさらに詳細
に説明するが、本発明はこれらの実施例によりなんら限
定されるものではない。 実施例１ 内径２８mm、高さ６００mmのアクリル樹脂製カラム下部
に、直径５〜１０mmの砂利を１００mmの高さに充填して
支持床とし、この支持床の上に、孔径３mm、ピッチ１０
mmの多孔板を取り付けた。多孔板上に、粒子径０.６mm
の均一な球状の鉄金属粒子２００ml（約１kg）を充填
し、図１に示す形状の鉄金属粒子の充填層を有するカラ
ムを作製した。セレン０.７mg／リットルを含有する排
水に塩酸を添加してpHを２〜３に調整し、カラム下部に
設けた導入口から、上向流で通水速度ＳＶ＝２０hr-1で
通水し、還元処理を行った。カラム上部に設けた水排出
口から流出する還元処理水に、水酸化ナトリウム水溶液
を添加してpHを９〜９.５に調整して凝集処理を行い、
沈殿を分離して処理水を得た。処理水中のセレン濃度
は、通水５時間後、２４時間後、３０時間後及び４８時
間後において、いずれも０.０２mg／リットルであっ
た。通水４８時間後にいったん排水の通水を止め、カラ
ムの洗浄を行った。工業用水を導入口から上向流で通水
速度ＬＶ＝１００ｍ・hr-1で通水を開始し、２分後に空
気を導入口から１リットル／分で工業用水とともに送り
始めた。さらにその３分後に空気の供給を止めて、工業
用水のみの通水を３分間行い、合計８分間でカラムの洗
浄を終えた。ふたたびpH調整を行ったセレン含有排水の
通水に切り替え、上と同様に処理を続けたところ、処理
水中のセレン濃度は、通水５４時間後０.０２mg／リッ
トル、７２時間後０.０２mg／リットル、９６時間後０.
０３mg／リットルであった。 比較例１ 実施例１に用いたものと同じ鉄金属粒子を充填したカラ
ムに、全く洗浄を行うことなく、実施例１と同じセレン
０.７mg／リットルを含有し塩酸によりpHを２〜３に調
整した排水を連続して９６時間通水して還元処理を行っ
た。還元処理水は、水酸化ナトリウム水溶液を添加して
pHを９〜９.５に調整して凝集処理を行い、沈殿を分離
して処理水を得た。処理水中のセレン濃度は、通水５時
間後、２４時間後、３０時間後及び４８時間後において
は、いずれも０.０２mg／リットルであったが、通水５
４時間後０.１５mg／リットル、７２時間後０.２２mg／
リットル、９６時間後０.２５mg／リットルと上昇し
た。 比較例２ 実施例１に用いたものと同じ鉄金属粒子を充填したカラ
ムに、実施例１と同じセレン０.７mg／リットルを含有
し塩酸によりpHを２〜３に調整した排水を通水して還元
処理を行った。さらに還元処理水に、水酸化ナトリウム
水溶液を添加してpHを９〜９.５に調整して凝集処理を
行い、沈殿を分離して処理水を得た。処理水中のセレン
濃度は、通水５時間後、２４時間後、３０時間後及び４
８時間後においては、いずれも０.０２mg／リットルで
あった。ここで、工業用水によるカラムの洗浄のみを行
った。すなわち、排水の通水を止め、工業用水を導入口
から上向流で通水速度ＬＶ＝１００ｍ・hr-1で８分間通
水し、カラムの洗浄を終えた。ふたたびpH調整を行った
セレン含有排水の通水に切り替え、上と同様に処理を続
けたところ、処理水中のセレン濃度は、通水５４時間後
０.０９mg／リットル、７２時間後０.１１mg／リット
ル、９６時間後０.１２mg／リットルであった。 比較例３ 実施例１に用いたものと同じ鉄金属粒子を充填したカラ
ムに、実施例１と同じセレン０.７mg／リットルを含有
し塩酸によりpHを２〜３に調整した排水を通水して還元
処理を行った。さらに還元処理水に、水酸化ナトリウム
水溶液を添加してpHを９〜９.５に調整して凝集処理を
行い、沈殿を分離して処理水を得た。処理水中のセレン
濃度は、通水５時間後、２４時間後、３０時間後及び４
８時間後において、いずれも０.０２mg／リットルであ
った。ここで工業用水のみによる洗浄を行うことなく、
工業用水及び空気の混合流をカラムに供給して洗浄を行
った。すなわち、排水の通水を止め、工業用水を導入口
から上向流で通水速度ＬＶ＝１００ｍ・hr-1で通水を開
始し、同時に空気を導入口から１リットル／分で工業用
水とともに送り始めた。３分後に空気の供給を止めて、
工業用水のみの通水を３分間行い、合計６分間でカラム
の洗浄を終えた。ふたたびpH調整を行ったセレン含有排
水の通水に切り替え、上と同様に処理を続けたところ、
処理水中のセレン濃度は、通水５４時間後０.０８mg／
リットル、７２時間後０.１０mg／リットル、９６時間
後０.１１mg／リットルであった。 実施例１及び比較例１〜３の結果を、第１表及び図２に
示す。EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. Example 1 A lower part of an acrylic resin column having an inner diameter of 28 mm and a height of 600 mm was filled with gravel having a diameter of 5 to 10 mm to a height of 100 mm to form a supporting bed, and a hole diameter of 3 mm and a pitch of 10 were formed on the supporting bed.
A mm perforated plate was attached. Particle size 0.6 mm on perforated plate
Was packed with 200 ml (about 1 kg) of uniform spherical iron metal particles of Example 1 to prepare a column having a packed layer of iron metal particles having the shape shown in FIG. Hydrochloric acid was added to the wastewater containing 0.7 mg / liter of selenium to adjust the pH to 2-3, and water was passed through the inlet provided at the bottom of the column at an upward flow rate of SV = 20 hr -1. , Reduction treatment was performed. An aqueous sodium hydroxide solution is added to the reduction treated water flowing out from the water discharge port provided at the top of the column to adjust the pH to 9 to 9.5, and the aggregation treatment is performed.
The precipitate was separated to obtain treated water. The selenium concentration in the treated water was 0.02 mg / liter after 5 hours, 24 hours, 30 hours and 48 hours after passing water. After 48 hours of passing water, the drainage was stopped once and the column was washed. The industrial water was started to flow through the inlet at an upward flow rate of LV = 100 m · hr −1 , and 2 minutes later, air was started to be sent from the inlet at 1 liter / minute together with the industrial water. 3 minutes later, the air supply was stopped, and only the industrial water was passed for 3 minutes, and the column washing was completed in a total of 8 minutes. After switching to selenium-containing wastewater whose pH had been adjusted again and continuing the treatment in the same manner as above, the selenium concentration in the treated water was 0.02 mg / liter after 54 hours and 0.02 mg / liter after 72 hours. Liters, 96 hours later.
It was 03 mg / liter. COMPARATIVE EXAMPLE 1 A column packed with the same iron metal particles as used in Example 1 contained 0.7 mg / liter of selenium, which was the same as in Example 1, without washing, and the pH was adjusted to 2-3 with hydrochloric acid. The adjusted wastewater was continuously passed for 96 hours to carry out a reduction treatment. For the reduction treated water, add sodium hydroxide aqueous solution.
The pH was adjusted to 9 to 9.5, aggregation treatment was performed, and the precipitate was separated to obtain treated water. The selenium concentration in the treated water was 0.02 mg / liter after 5 hours, 24 hours, 30 hours, and 48 hours after passing water.
0.15 mg / liter after 4 hours and 0.22 mg / liter after 72 hours
The liter increased to 0.25 mg / liter after 96 hours. Comparative Example 2 A column filled with the same iron metal particles as that used in Example 1 was passed through a waste water containing the same selenium (0.7 mg / liter) as in Example 1 and having its pH adjusted to 2-3 with hydrochloric acid. And reduction treatment was performed. Further, an aqueous sodium hydroxide solution was added to the reduced treated water to adjust the pH to 9 to 9.5, an aggregation treatment was performed, and a precipitate was separated to obtain treated water. The selenium concentration in the treated water was 5 hours, 24 hours, 30 hours and 4 hours after passing water.
After 8 hours, all were 0.02 mg / liter. Here, only the column was washed with industrial water. That is, the drainage was stopped, and industrial water was passed through the inlet at an upward flow rate of LV = 100 m · hr −1 for 8 minutes to complete the column washing. When the selenium-containing wastewater whose pH had been adjusted again was passed and the treatment was continued as above, the concentration of selenium in the treated water was 0.09 mg / liter after 54 hours of water passage and 0.11 mg / liter after 72 hours. It was 0.12 mg / liter after 96 hours. Comparative Example 3 A column filled with the same iron metal particles as used in Example 1 was passed through a waste water containing the same selenium (0.7 mg / liter) as in Example 1 and having a pH adjusted to 2 to 3 with hydrochloric acid. And reduction treatment was performed. Further, an aqueous sodium hydroxide solution was added to the reduced treated water to adjust the pH to 9 to 9.5, an aggregation treatment was performed, and a precipitate was separated to obtain treated water. The selenium concentration in the treated water was 5 hours, 24 hours, 30 hours and 4 hours after passing water.
After 8 hours, all were 0.02 mg / liter. Here, without cleaning with only industrial water,
A mixed stream of industrial water and air was supplied to the column for washing. That is, the drainage is stopped, industrial water is started to flow upward from the inlet at a water flow rate LV = 100 m · hr −1 , and at the same time, air is supplied from the inlet at 1 liter / min together with the industrial water. I started sending. Turn off the air supply after 3 minutes,
Only the industrial water was passed for 3 minutes, and the column washing was completed in a total of 6 minutes. After switching to selenium-containing wastewater whose pH was adjusted again, and continuing the treatment as above,
The selenium concentration in the treated water was 0.08 mg / 54 hours after passing water.
Liter, 0.10 mg / liter after 72 hours and 0.11 mg / liter after 96 hours. The results of Example 1 and Comparative Examples 1 to 3 are shown in Table 1 and FIG.
【００１１】[0011]
【表１】 [Table 1]
【００１２】第１表及び図２の結果から、鉄金属粒子の
充填層に洗浄水のみを通水して洗浄を行ったのち、洗浄
水及び空気の混合流を供給して洗浄した実施例１におい
ては、処理水中のセレン濃度が０.０２〜０.０３mg／リ
ットルと安定して低いことが分かる。これに対して、全
く洗浄を行わない比較例１においては、通水時間が５０
時間を超えると処理水中のセレン濃度は急速に上昇す
る。また、洗浄を洗浄水のみを用いて行った比較例２
と、洗浄水のみの通水による洗浄を行うことなく、洗浄
水及び空気の混合流を供給して洗浄した比較例３は結果
には大差はなく、いずれも通水時間７２時間で処理水中
のセレン濃度は、規制値である０.１mg／リットル以上
となる。これらの結果から、鉄金属粒子の充填層に洗浄
水のみの通水による洗浄を行ったのち、洗浄水及び空気
の混合流を供給して洗浄する本発明方法が、排水中のセ
レンを安定して除去する上で、非常に有効であることが
分かる。From the results shown in Table 1 and FIG. 2, Example 1 was conducted in which only the washing water was passed through the packed bed of iron metal particles for washing, and then a mixed flow of the washing water and air was supplied for washing. In Example 1, the selenium concentration in the treated water is stable and is as low as 0.02 to 0.03 mg / liter. On the other hand, in Comparative Example 1 in which no cleaning is performed, the water passage time is 50
The selenium concentration in the treated water rises rapidly over time. In addition, Comparative Example 2 in which washing was performed using only washing water
And Comparative Example 3 in which cleaning was performed by supplying a mixed flow of cleaning water and air without performing cleaning by passing the cleaning water alone, there was no great difference in the results. The selenium concentration is not less than the regulated value of 0.1 mg / liter. From these results, the method of the present invention in which the packed bed of iron metal particles is cleaned by passing only the cleaning water, and then the mixed flow of the cleaning water and the air is supplied to clean the selenium in the waste water is stabilized. It turns out that it is very effective in removing it.
【００１３】[0013]
【発明の効果】本発明方法によれば、排水中の不純物を
還元処理するための鉄金属粒子の充填層の洗浄を、窒素
ガスなどの不活性ガスを使用することなく、少ない量の
洗浄水を用いて効率的に行うことができ、ペルオキソ硫
酸、ヨウ素酸、セレン酸などの酸化性物質を不純物とし
て含有する排水の還元処理を、長期間にわたって安定し
て行うことができる。According to the method of the present invention, a small amount of cleaning water is used for cleaning the packed bed of iron metal particles for reducing impurities in waste water without using an inert gas such as nitrogen gas. Can be efficiently used, and reduction treatment of wastewater containing an oxidizing substance such as peroxosulfuric acid, iodic acid, or selenic acid as impurities can be stably performed over a long period of time.
【図１】図１は、本発明の水処理装置の洗浄方法の説明
図である。FIG. 1 is an explanatory diagram of a cleaning method for a water treatment device according to the present invention.
【図２】図２は、通水時間と処理水中のセレン濃度の関
係を示すグラフである。FIG. 2 is a graph showing the relationship between water passage time and selenium concentration in treated water.
１ カラム ２ 導入口 ３ 水排出口 ４ 支持床 ５ 多孔板 ６ 鉄金属粒子の充填層 ７ 多孔板 1 Column 2 Inlet 3 Water Outlet 4 Support Bed 5 Perforated Plate 6 Packing Layer of Iron Metal Particles 7 Perforated Plate
Claims (1)
純物を還元処理する水処理装置において、充填層に洗浄
水を通水して洗浄したのち、さらに洗浄水及び空気の混
合流を上向流で供給し、鉄金属粒子の充填層の汚染物質
を除去することを特徴とする水処理装置の洗浄方法。1. A water treatment apparatus for reducing impurities in wastewater by passing water through a packed bed of iron metal particles, after washing water through the packed bed for cleaning, and then mixing the cleaning water and air. A method for cleaning a water treatment device, which comprises supplying an upward flow to remove contaminants in a packed bed of iron metal particles.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16532396A JP3237524B2 (en) | 1996-06-05 | 1996-06-05 | Cleaning method for water treatment equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16532396A JP3237524B2 (en) | 1996-06-05 | 1996-06-05 | Cleaning method for water treatment equipment |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH09323090A true JPH09323090A (en) | 1997-12-16 |
| JP3237524B2 JP3237524B2 (en) | 2001-12-10 |
Family
ID=15810153
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP16532396A Expired - Lifetime JP3237524B2 (en) | 1996-06-05 | 1996-06-05 | Cleaning method for water treatment equipment |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3237524B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007216228A (en) * | 2007-05-16 | 2007-08-30 | Chiyoda Corp | Method for selenium removal from waste water |
-
1996
- 1996-06-05 JP JP16532396A patent/JP3237524B2/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007216228A (en) * | 2007-05-16 | 2007-08-30 | Chiyoda Corp | Method for selenium removal from waste water |
| JP4532522B2 (en) * | 2007-05-16 | 2010-08-25 | 千代田化工建設株式会社 | Wastewater de-selenium treatment method |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3237524B2 (en) | 2001-12-10 |
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