JPH11169869A - Treatment of selenium-containing waste water - Google Patents
Treatment of selenium-containing waste waterInfo
- Publication number
- JPH11169869A JPH11169869A JP34016997A JP34016997A JPH11169869A JP H11169869 A JPH11169869 A JP H11169869A JP 34016997 A JP34016997 A JP 34016997A JP 34016997 A JP34016997 A JP 34016997A JP H11169869 A JPH11169869 A JP H11169869A
- Authority
- JP
- Japan
- Prior art keywords
- selenium
- iron metal
- water
- metal particles
- iron
- 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
- Removal Of Specific Substances (AREA)
- 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、セレン含有排水の
処理方法に関する。さらに詳しくは、本発明は、６価の
セレンを含有する排水を鉄金属と接触させてセレンを還
元処理する方法において、鉄金属粒子の洗浄頻度を少な
くすることができ、多量の懸濁物質を含むセレン含有排
水もそのまま処理することができるセレン含有排水の処
理方法に関する。[0001] The present invention relates to a method for treating selenium-containing wastewater. More specifically, the present invention provides a method for reducing selenium by contacting wastewater containing hexavalent selenium with iron metal, in which the frequency of washing the iron metal particles can be reduced, and a large amount of suspended substances can be removed. The present invention relates to a method for treating selenium-containing wastewater which can also treat selenium-containing wastewater as it is.
【０００２】[0002]
【従来の技術】石炭火力発電所の排煙脱硫排水や石油精
製工場排水は、セレンを含有する場合がある。また、セ
レンは工業原料として、ガラスの脱色剤や着色剤、高級
顔料、鉄鋼や銅への添加剤に使われるほか、ウレタンや
尿素の合成時の触媒としても使用されるので、これらの
工場排水にもセレンが含有される可能性がある。セレン
は排水中に高濃度に含有されることは稀であるが、環境
保全のためにセレンに対する規制が行われるにいたり、
排水中のセレンの処理が必要となり、水質汚濁防止法に
基づくセレンの排水基準は、０.１mg／リットルと示さ
れている。排水中のセレンは、通常コロイド状のセレ
ン、４価の亜セレン酸イオン（ＳｅＯ3 2-）又は６価の
セレン酸イオン（ＳｅＯ4 2-）として存在することが多
い。このようなセレン含有排水の処理方法としては、凝
集沈殿法とイオン交換法が知られている。しかし、これ
らの方法では最終処理水中のセレン濃度は０.２〜０.４
mg／リットルにまでしか低下せず、０.１mg／リットル
という排水基準を達成することができない。本発明者ら
は、凝集沈殿法によって排水中のセレンを０.１mg／リ
ットル以下に除去することが困難である原因について研
究し、その原因は含有される６価のセレンの除去が困難
であるため、あるいは、排水中に凝集沈殿を阻害、妨害
する物質が存在するためであることを見いだした。この
知見に基づき、本発明者らは、先にセレン含有水の処理
方法として、酸の添加によりpHを調整したセレン含有水
を鉄金属粒子充填層に通水し、溶出した２価の鉄イオン
により６価のセレンを次式にしたがって還元処理する方
法を提案した。 ＳｅＯ4 2-＋６Ｆｅ2+＋８Ｈ+ → Ｓｅ0＋６Ｆｅ3+＋４Ｈ2Ｏ …［１］ 還元されたセレンを含む被処理水は、アルカリを添加し
てpHを７以上とすることにより、水中の鉄イオンを水不
溶性の水酸化鉄とし、還元されたセレンを水酸化鉄のフ
ロックに吸着させて凝集分離する。この方法によれば、
最終処理水中のセレン濃度を安定して０.１mg／リット
ル以下にすることができるが、鉄金属粒子表面の汚濁を
生ずることなく、長時間継続して処理するためには、鉄
金属粒子充填層に通水するセレン含有排水中の懸濁物質
が５０mg／リットル以下であることが望ましい。しか
し、排煙脱硫排水などの排水には、懸濁物質が７００〜
１,０００mg／リットル程度含まれる場合が多く、その
まま処理することはほとんど不可能で、あらかじめ沈殿
分離した上澄水を対象にして６価のセレンの還元処理を
行う必要がある。また、懸濁物質の量が５０mg／リット
ル以下の排水であっても、通水接触を継続すると鉄金属
粒子の表面が汚濁されるため、洗浄を行う必要がある。
鉄金属粒子の洗浄は、鉄金属粒子充填層を流速の高い水
で展開して洗浄し、さらに空気を吹き込んで懸濁物質を
鉄金属粒子から剥離して除去するが、洗浄の頻度が多
く、また、装置が複雑になるという問題がある。特に、
鉄金属粒子の粒径が大きい場合は、鉄金属粒子を浮上展
開させるために必要な水の流速が速いために、洗浄用の
ポンプが必要になり、動力費が高くなるという問題もあ
る。このために、鉄金属粒子の洗浄頻度を少なくし、か
つ容易に洗浄することができ、多量の懸濁物質を含むセ
レン含有排水もそのまま処理することができるセレン含
有排水の処理方法の開発が求められていた。2. Description of the Related Art In some cases, flue gas desulfurization effluent from coal-fired power plants and effluent from petroleum refineries contain selenium. In addition, selenium is used as an industrial raw material as a decolorizing agent and coloring agent for glass, as a high-grade pigment, as an additive to steel and copper, and as a catalyst for the synthesis of urethane and urea. May also contain selenium. Selenium is rarely contained in high concentrations in wastewater, but as selenium is regulated for environmental protection,
It is necessary to treat selenium in wastewater, and the selenium wastewater standard based on the Water Pollution Control Law is set at 0.1 mg / liter. Selenium in the wastewater is usually present as colloidal selenium, tetravalent selenite ion (SeO 3 2− ) or hexavalent selenite ion (SeO 4 2− ) in many cases. As a method for treating such selenium-containing wastewater, a coagulation sedimentation method and an ion exchange method are known. However, in these methods, the selenium concentration in the final treated water is 0.2 to 0.4.
It can only be reduced to mg / l, and the wastewater standard of 0.1 mg / l cannot be achieved. The present inventors have studied the reason why it is difficult to remove selenium in wastewater to 0.1 mg / liter or less by the coagulation sedimentation method. The cause is that it is difficult to remove hexavalent selenium contained. Or the presence of substances that inhibit or hinder coagulation and sedimentation in the wastewater. Based on this finding, the present inventors have previously proposed a method for treating selenium-containing water, in which selenium-containing water whose pH has been adjusted by the addition of an acid is passed through the packed bed of iron metal particles to elute divalent iron ions. Proposed a method of reducing hexavalent selenium according to the following formula. SeO 4 2- + 6Fe 2+ + 8H + → Se 0 + 6Fe 3+ + 4H 2 O [1] The water to be treated containing reduced selenium is adjusted to a pH of 7 or more by adding an alkali to reduce the iron in the water. The ions are converted to water-insoluble iron hydroxide, and the reduced selenium is adsorbed on flocks of iron hydroxide to cause coagulation and separation. According to this method,
The selenium concentration in the final treated water can be stably reduced to 0.1 mg / liter or less. However, in order to continue treatment for a long time without causing contamination on the surface of the iron metal particles, a layer filled with iron metal particles is required. It is desirable that the amount of suspended matter in the selenium-containing wastewater passing through the selenium is 50 mg / liter or less. However, in wastewater such as flue gas desulfurization wastewater, suspended substances are 700 ~
It is often contained at about 1,000 mg / liter, and it is almost impossible to treat it as it is. Therefore, it is necessary to carry out a reduction treatment of hexavalent selenium with respect to the supernatant water which has been precipitated and separated in advance. In addition, even if the amount of the suspended substance is 50 mg / liter or less, the surface of the iron metal particles is polluted if the flow contact is continued.
Washing of the iron metal particles is performed by spreading the iron metal particle packed layer with high-velocity water, washing the air, and then blowing air to remove suspended substances from the iron metal particles and removing them. There is also a problem that the device becomes complicated. Especially,
When the particle size of the iron metal particles is large, the flow rate of water required for floating and developing the iron metal particles is high, so that a cleaning pump is required, and there is also a problem that power cost is increased. Therefore, there is a need for the development of a method for treating selenium-containing wastewater, which can reduce the frequency of cleaning of iron metal particles, can be easily washed, and can directly treat selenium-containing wastewater containing a large amount of suspended substances. Had been.
【０００３】[0003]
【発明が解決しようとする課題】本発明は、６価のセレ
ンを含有する排水を鉄金属と接触させてセレンを還元処
理する方法において、鉄金属粒子の洗浄頻度を少なく
し、かつ容易に洗浄することができ、多量の懸濁物質を
含むセレン含有排水もそのまま処理することができるセ
レン含有排水の処理方法を提供することを目的としてな
されたものである。SUMMARY OF THE INVENTION The present invention relates to a method for reducing selenium by contacting wastewater containing hexavalent selenium with iron metal to reduce the frequency of cleaning of iron metal particles and to facilitate the cleaning. It is an object of the present invention to provide a method for treating selenium-containing wastewater, which can directly treat selenium-containing wastewater containing a large amount of suspended substances.
【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、鉄金属粒子充填
塔を固定床でなく、流動層とすることにより、多量の懸
濁物質を含むセレン含有排水も沈殿分離をすることなく
通水することができ、鉄金属粒子の洗浄頻度を少なく
し、かつ容易に洗浄することができることを見いだし、
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）セレン含有排水を、鉄金属粒子流
動層に通水して排水中のセレンを還元処理することを特
徴とするセレン含有排水の処理方法、（２）鉄金属粒子
の平均粒径が０.２５〜０.３５mmである第(１)項記載の
セレン含有排水の処理方法、及び、（３）鉄金属粒子流
動層の展開率が３〜２０％である第(１)項記載のセレン
含有排水の処理方法、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、（４）通水速度が３０〜
６０ｍ／hrである第(１)項記載のセレン含有排水の処理
方法、及び、（５）鉄金属粒子の８０重量％以上が、粒
径０.１８〜０.５mmの範囲にある第(２)項記載のセレン
含有排水の処理方法、を挙げることができる。Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, a large amount of suspension has been achieved by using a fluidized bed instead of a fixed bed for the iron metal particle packed tower. It has been found that selenium-containing wastewater containing suspended substances can be passed through without sedimentation and separation, and that the frequency of washing iron metal particles can be reduced and easily washed.
Based on this finding, the present invention has been completed. That is, the present invention provides (1) a method for treating selenium-containing wastewater, which comprises passing selenium-containing wastewater through a fluidized bed of iron metal particles to reduce selenium in the wastewater; (1) wherein the average particle diameter of the selenium-containing wastewater is 0.25 to 0.35 mm; and (3) the method of (3) wherein the spreading rate of the iron metal particle fluidized bed is 3 to 20%. 1) A method for treating selenium-containing wastewater according to item 1). further,
As a preferred embodiment of the present invention, (4) the water passage speed is 30 to
(1) The method for treating selenium-containing wastewater according to (1), wherein the selenium-containing wastewater has a particle diameter of 0.18 to 0.5 mm in a range of 0.18 to 0.5 mm. )), A method for treating selenium-containing wastewater.
【０００５】[0005]
【発明の実施の形態】本発明方法は、セレン含有排水、
特に６価のセレンを含有する排水に効果的に適用するこ
とができる。このようなセレン含有排水としては、例え
ば、火力発電所排水などを挙げることができる。本発明
方法においては、セレンを含有する排水に塩酸又は硫酸
を注入して、排水が酸性になるように調整し、鉄金属粒
子流動層に通水することが好ましい。酸性のセレン含有
排水と鉄金属粒子が接触したとき、次式により２価の鉄
イオンが水中へ溶出する。 Ｆｅ＋２Ｈ+ → Ｆｅ2+＋Ｈ2 …［２］ 水中に溶出した２価の鉄イオンは、水中の６価のセレン
と反応し、６価のセレンは次式にしたがって還元される
と考えられる。 ＳｅＯ4 2-＋６Ｆｅ2+＋８Ｈ+ → Ｓｅ0＋６Ｆｅ3+＋４Ｈ2Ｏ …［３］DETAILED DESCRIPTION OF THE INVENTION The method of the present invention comprises the steps of:
In particular, it can be effectively applied to wastewater containing hexavalent selenium. Examples of such selenium-containing wastewater include thermal power plant wastewater. In the method of the present invention, it is preferable to inject hydrochloric acid or sulfuric acid into the wastewater containing selenium to adjust the wastewater to be acidic, and to pass water through the fluidized bed of iron metal particles. When the acidic selenium-containing wastewater comes into contact with iron metal particles, divalent iron ions are eluted into water according to the following equation. Fe + 2H + → Fe 2+ + H 2 [2] It is considered that the divalent iron ion eluted in the water reacts with hexavalent selenium in the water, and the hexavalent selenium is reduced according to the following formula. SeO 4 2- + 6Fe 2+ + 8H + → Se 0 + 6Fe 3+ + 4H 2 O [3]
【０００６】本発明方法においては、セレン含有排水を
鉄金属粒子流動層に通水する。すなわち、鉄金属粒子充
填層にセレン含有排水を通水することにより、充填層が
展開して流動層を形成する状態となるように、セレン含
有排水を通水する。鉄金属粒子流動層において６価のセ
レンの還元反応処理を行うことにより、懸濁物質の大部
分は鉄金属粒子充填塔から流出し、排水中の懸濁物質が
鉄金属粒子の表面に付着して、汚濁することが少なくな
る。鉄金属粒子充填塔から流出した懸濁物質は、次の凝
集処理工程において、還元処理されたセレンとともに容
易に除去することができる。また、懸濁物質や還元処理
されたセレンなどは、膜分離法によっても除去すること
ができる。鉄金属粒子充填層を固定床として使用する従
来法においては、セレン含有排水中の懸濁物質を５０mg
／リットル以下とする必要があったが、本発明方法によ
れば、７００〜１,０００mg／リットルの懸濁物質を含
む排煙脱硫排水のようなセレン含有排水も、懸濁物質除
去のための前処理を行うことなく、直接鉄金属粒子流動
層に通水して処理することができる。In the method of the present invention, selenium-containing wastewater is passed through a fluidized bed of iron metal particles. That is, by passing the selenium-containing wastewater through the iron metal particle packed bed, the selenium-containing wastewater is allowed to flow such that the packed bed is expanded to form a fluidized bed. By performing a hexavalent selenium reduction reaction treatment in the iron metal particle fluidized bed, most of the suspended solids flow out of the iron metal particle packed tower, and the suspended solids in the wastewater adhere to the surface of the iron metal particles. Contamination is reduced. The suspended matter flowing out of the iron metal particle packed tower can be easily removed together with the reduced selenium in the next aggregation treatment step. Suspended substances and selenium subjected to reduction treatment can also be removed by a membrane separation method. In the conventional method using a bed packed with iron metal particles as a fixed bed, 50 mg of suspended solids in selenium-containing wastewater is used.
However, according to the method of the present invention, selenium-containing wastewater such as flue gas desulfurization wastewater containing 700 to 1,000 mg / liter of suspended solids is also required according to the method of the present invention. The treatment can be performed by passing water directly through the fluidized bed of iron metal particles without performing pretreatment.
【０００７】本発明方法において、鉄金属粒子流動層を
形成する鉄金属粒子としては、その８０重量％以上が、
特に好ましくは９０重量％以上が、粒径０.１８〜０.５
mmの範囲にあり、かつ平均粒径が０.２５〜０.３５mmで
あるものが特に好ましい。鉄金属粒子の平均粒径が０.
２５mm未満であると、展開率を適正とするために通水速
度を低くする必要があるため、カラム底面積を広くしな
ければならず、装置の設置面積が大きくなる。また、鉄
金属粒子の補充時に飛散しやすいなど、取り扱いが不便
となるおそれがある。平均粒径が０.３５mmを超える鉄
金属粒子を用いると、鉄金属粒子を流動させるための通
水速度が大きくなり、必要な動力が大きくなる。本発明
方法において、鉄金属粒子流動層の展開率は、３〜２０
％であることが好ましく、５〜１０％であることがより
好ましい。鉄金属粒子流動層の展開率が３％未満である
と、鉄金属粒子の表面に懸濁物質が付着して汚濁を生ず
るおそれがある。鉄金属粒子流動層の展開率は、鉄金属
粒子表面への懸濁物質の付着を防ぐためには、通常は２
０％以下で十分であり、展開率が２０％を超えると、鉄
金属粒子充填塔の容量が大きくなるのみならず、鉄金属
粒子を流動させるための通水速度が大きくなり、必要な
動力が大きくなる。また、鉄金属粒子どうしの間隔が広
がるため、被処理水との接触が不充分となるので、セレ
ンの除去率が低下する。本発明方法において、鉄金属粒
子の平均粒径が０.２５〜０.３５mmである場合、セレン
含有排水の通水速度は３０〜６０ｍ／hrであることが好
ましく、３５〜５０ｍ／hrであることがより好ましい。
通水速度を３０〜６０ｍ／hrとすることにより、鉄金属
粒子流動層の展開率を容易に好適な範囲である３〜２０
％とすることができる。In the method of the present invention, 80% by weight or more of the iron metal particles forming the fluidized iron metal particle bed are:
Particularly preferably, 90% by weight or more has a particle size of 0.18 to 0.5.
Those having a diameter in the range of 0.2 mm to 0.25 mm to 0.35 mm are particularly preferred. The average particle size of the iron metal particles is 0.
If it is less than 25 mm, it is necessary to lower the water flow rate in order to make the expansion rate appropriate, so that the column bottom area must be widened and the installation area of the apparatus becomes large. In addition, handling may be inconvenient, for example, the iron metal particles are easily scattered when replenished. When iron metal particles having an average particle size of more than 0.35 mm are used, the water flow rate for flowing the iron metal particles increases, and the required power increases. In the method of the present invention, the spreading rate of the fluidized bed of iron metal particles is 3 to 20.
%, More preferably 5 to 10%. When the spreading rate of the fluid bed of the iron metal particles is less than 3%, the suspended substance may adhere to the surface of the iron metal particles to cause pollution. The spreading rate of the fluidized bed of the iron metal particles is usually 2 to prevent the adhesion of suspended substances to the surface of the iron metal particles.
0% or less is sufficient, and if the expansion rate exceeds 20%, not only the capacity of the iron metal particle packed tower becomes large, but also the water flow rate for flowing the iron metal particles increases, and the required power is reduced. growing. In addition, since the distance between the iron metal particles is widened, the contact with the water to be treated becomes insufficient, and the selenium removal rate decreases. In the method of the present invention, when the average particle size of the iron metal particles is 0.25 to 0.35 mm, the flow rate of the selenium-containing wastewater is preferably 30 to 60 m / hr, and more preferably 35 to 50 m / hr. Is more preferable.
By setting the water flow rate to 30 to 60 m / hr, the spreading rate of the fluidized bed of iron metal particles is easily within a suitable range of 3 to 20.
%.
【０００８】本発明方法においても、通水を長期間継続
すると、鉄金属粒子表面に懸濁物質が付着し、圧力損失
上昇や６価のセレンの還元反応速度の低下が生ずるの
で、定期的に、あるいは、鉄金属粒子流動層の圧力損失
や処理水のセレン濃度を測定して必要に応じて、鉄金属
粒子の洗浄を行うことが好ましい。本発明方法において
は、鉄金属粒子の洗浄は、通常の条件で通水を継続した
まま、鉄金属粒子流動層の体積に対し、体積比で１分間
に０.１〜１０倍量の空気を鉄金属粒子充填塔の下部か
ら１〜５分間吹き込むことによって行うことができる。
また、空気のかわりに窒素ガス等の不活性ガスを用いて
もよい。鉄金属粒子充填層を固定床として用いる従来の
方法においては、通水処理をいったん停止し、通水速度
９０ｍ／hrのような高流速の水による洗浄と、空気の吹
き込みを併用する必要があった。本発明方法において
は、高流速洗浄の必要がなく、通常の通水処理を行いつ
つ、空気吹き込みのみで洗浄することができるので、設
備面からも、運転面からも、経済的にセレン含有排水を
処理することができる。本発明方法においては、鉄金属
粒子流動層に通水することにより排水中の６価のセレン
を還元したのち、鉄金属粒子充填塔より流出する水の凝
集処理を行うことが好ましい。凝集処理の方法には特に
制限はないが、アルカリ剤を添加することにより、水中
の２価の鉄イオン及び３価の鉄イオンを水不溶性の水酸
化第一鉄及び水酸化第二鉄とし、鉄フロックを形成して
凝集することが好ましい。アルカリ剤の添加により、被
処理水のpHを７以上とすることが好ましく、pHを９〜１
０とすることがより好ましい。被処理水のpHが７未満で
あると、鉄フロックなどの凝集が不十分となるおそれが
ある。被処理水のpHを７以上とすることにより、次式の
ように、水中の２価の鉄イオンは水不溶性の水酸化第一
鉄となり、３価の鉄イオンは水不溶性の水酸化第二鉄と
なる。 Ｆｅ2+＋２ＮａＯＨ → Ｆｅ(ＯＨ)2＋２Ｎａ+ …［４］ Ｆｅ3+＋３ＮａＯＨ → Ｆｅ(ＯＨ)3＋３Ｎａ+ …［５］ このとき、還元されたセレンは、生成する水酸化鉄のフ
ロックに吸着され、凝集分離される。In the method of the present invention, if water is continuously passed for a long period of time, suspended substances adhere to the surface of the iron metal particles, causing an increase in pressure loss and a reduction in the reduction reaction rate of hexavalent selenium. Alternatively, it is preferable to measure the pressure loss of the fluidized bed of the iron metal particles and the selenium concentration of the treated water to wash the iron metal particles as necessary. In the method of the present invention, the washing of the iron metal particles is carried out at a volume ratio of 0.1 to 10 times the volume of the air per minute with respect to the volume of the fluidized bed of the iron metal particles while continuing the flow of water under normal conditions. It can be performed by blowing from the lower part of the iron metal particle packed tower for 1 to 5 minutes.
Further, an inert gas such as nitrogen gas may be used instead of air. In the conventional method in which the bed packed with iron metal particles is used as a fixed bed, it is necessary to temporarily stop the water passage treatment, and to simultaneously use washing with water at a high flow rate such as a water passage speed of 90 m / hr and blowing air. Was. In the method of the present invention, high-flow rate washing is not required, and washing can be performed only by blowing air while performing normal water passing treatment. Can be processed. In the method of the present invention, it is preferable to reduce the hexavalent selenium in the wastewater by passing water through the fluidized bed of iron metal particles, and then to perform a coagulation treatment of the water flowing out of the iron metal particle packed tower. The method of the aggregation treatment is not particularly limited, but by adding an alkali agent, divalent iron ions and trivalent iron ions in water are converted into water-insoluble ferrous hydroxide and ferric hydroxide, It is preferable to form iron flocs and aggregate. The pH of the water to be treated is preferably adjusted to 7 or more by adding an alkali agent,
More preferably, it is set to 0. If the pH of the water to be treated is less than 7, aggregation of iron flocs and the like may be insufficient. By adjusting the pH of the water to be treated to 7 or more, divalent iron ions in water become water-insoluble ferrous hydroxide as shown in the following formula, and trivalent iron ions become water-insoluble ferric hydroxide. Becomes iron. Fe 2+ + 2NaOH → Fe (OH) 2 + 2Na + ... [4] Fe 3+ + 3NaOH → Fe (OH) 3 + 3Na + ... [5] At this time, the reduced selenium is adsorbed on the flocs of the iron hydroxide produced. And agglomerated and separated.
【０００９】本発明方法においては、鉄金属粒子充填塔
より流出する水の凝集処理の際に、アルカリ剤の添加に
加えて、凝集剤を併用することができる。使用する凝集
剤には特に制限はなく、例えば、硫酸アルミニウム、ポ
リ塩化アルミニウム、硫酸第一鉄、塩化第二鉄などの無
機凝集剤、ポリアクリル酸ナトリウム、アクリル酸ナト
リウムとアクリルアミドの共重合体、ポリ−２−アクリ
ルアミド−２−メチルプロパンスルホン酸ナトリウムな
どの高分子凝集剤などを挙げることができる。凝集処理
においては、必要に応じて、マンガン除去のため過マン
ガン酸カリウムなどを添加することができる。本発明方
法においては、鉄金属粒子を流動状態としてセレン含有
排水を通水するので、セレン含有排水が多量の懸濁物質
を含んでいても、懸濁物質が鉄金属粒子の表面に付着す
ることなく流出し、６価のセレンの還元反応が阻害され
ることがない。本発明のセレン含有排水の処理方法によ
れば、排水中の懸濁物質をあらかじめ除去する必要がな
く、例えば、７００〜１,０００mg／リットルの懸濁物
質を含む排煙脱硫排水をそのまま処理することができ
る。また、鉄金属粒子の洗浄において、高流速の水によ
る洗浄の必要がなく、単に空気の吹き込みを行うことに
より、鉄金属粒子を洗浄することができる。In the method of the present invention, a coagulant can be used in addition to the addition of the alkali agent during the coagulation treatment of the water flowing out of the iron metal particle packed tower. There are no particular restrictions on the flocculant used, for example, aluminum sulfate, polyaluminum chloride, ferrous sulfate, inorganic flocculants such as ferric chloride, sodium polyacrylate, a copolymer of sodium acrylate and acrylamide, Polymer flocculants such as sodium poly-2-acrylamido-2-methylpropanesulfonate can be mentioned. In the agglomeration treatment, potassium permanganate or the like can be added as needed to remove manganese. In the method of the present invention, since the selenium-containing wastewater flows through the iron metal particles in a fluidized state, even if the selenium-containing wastewater contains a large amount of suspended substances, the suspended substances adhere to the surfaces of the iron metal particles. Without flowing out, and the reduction reaction of hexavalent selenium is not inhibited. According to the method for treating selenium-containing wastewater of the present invention, it is not necessary to remove suspended substances in the wastewater in advance, and for example, flue gas desulfurization wastewater containing 700 to 1,000 mg / liter of suspended substances is directly treated. be able to. Further, in the cleaning of the iron metal particles, there is no need to perform cleaning with water at a high flow rate, and the iron metal particles can be cleaned by simply blowing air.
【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４０mm、高さ１,０００mm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
１０mmの多孔板を取り付けた。多孔板上に、平均粒径
０.３mm、９０重量％以上が粒径０.１８〜０.５mmの球
状の鉄金属粒子１,０００ml（約５kg）を充填した。６
価セレン濃度０.５mg／リットル、懸濁物質１００mg／
リットルを含有する石炭火力発電所の排煙脱硫排水に、
塩酸を濃度６００mg／リットルになるよう注入して、カ
ラム下部に設けた導入口から、上向流で通水速度４０ｍ
／hrで通水し、還元処理を行った。鉄金属粒子流動層の
展開率は、５％であった。カラム上部に設けた水排出口
から流出する還元処理水をサンプリングして鉄溶出量を
測定した。また、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、ポリ塩化アルミニ
ウムを濃度５００mg／リットル、過マンガン酸カリウム
を濃度５０mg／リットル、高分子凝集剤［栗田工業
(株)、ウエルクリン］を濃度１０mg／リットルになるよ
う添加して凝集処理を行い、沈殿を分離して処理水を得
た。通水２０時間後において、処理水中のセレン濃度は
０.０３mg／リットルであった。鉄溶出量は４００mg／
リットルであった。通水開始時から２０時間後までの間
の圧力損失増加は０.０２kgf／cm2であった。 実施例２ 実施例１と同じ鉄金属粒子を充填したカラムを用い、６
価セレン濃度０.３mg／リットル、懸濁物質５００mg／
リットルを含有する石炭火力発電所の排煙脱硫排水に、
塩酸を濃度４００mg／リットルになるよう注入して、カ
ラム下部に設けた導入口から、上向流で通水速度４０ｍ
／hrで通水し、還元処理を行った。鉄金属粒子流動層の
展開率は、６％であった。実施例１と同様に、カラム上
部に設けた水排出口から流出する還元処理水をサンプリ
ングして鉄溶出量を測定した。また、実施例１と同様に
して還元処理水の凝集処理を行い、沈殿を分離して処理
水を得た。通水２０時間後において、処理水中のセレン
濃度は０.０５mg／リットルであった。鉄溶出量は２５
０mg／リットルであった。通水開始時から２０時間後ま
での間の圧力損失増加は０.０５kgf／cm2であった。 比較例１ 内径４０mm、高さ１,０００mm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
１０mmの多孔板を取り付けた。多孔板上に、粒径０.６m
mの均一な球状の鉄金属粒子１,０００ml（約５kg）を充
填した。実施例１と同じ６価セレン濃度０.５mg／リッ
トル、懸濁物質１００mg／リットルを含有する石炭火力
発電所の排煙脱硫排水に、塩酸を濃度６００mg／リット
ルになるよう注入して、カラム下部に設けた導入口か
ら、上向流で通水速度４０ｍ／hrで通水し、還元処理を
行った。カラム中の鉄金属粒子は展開することなく、固
定床の状態を保っていた。カラム上部に設けた水排出口
から流出する還元処理水をサンプリングして鉄溶出量を
測定した。また、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、ポリ塩化アルミニ
ウムを濃度５００mg／リットル、過マンガン酸カリウム
を濃度５０mg／リットル、高分子凝集剤［栗田工業
(株)、ウエルクリン］を濃度１０mg／リットルになるよ
う添加して凝集処理を行い、沈殿を分離して処理水を得
た。通水２０時間後において、処理水中のセレン濃度は
０.２０mg／リットルであった。鉄溶出量は３５０mg／
リットルであった。通水開始時から２０時間後までの間
の圧力損失増加は０.７５kgf／cm2であった。 比較例２ 比較例１と同じ鉄金属粒子を充填したカラムを用い、実
施例２と同じ６価セレン濃度０.３mg／リットル、懸濁
物質５００mg／リットルを含有する石炭火力発電所の排
煙脱硫排水に、塩酸を濃度４００mg／リットルになるよ
う注入して、カラム下部に設けた導入口から、上向流で
通水速度４０ｍ／hrで通水し、還元処理を行った。カラ
ム中の鉄金属粒子は展開することなく、固定床の状態を
保っていた。比較例１と同様に、カラム上部に設けた水
排出口から流出する還元処理水をサンプリングして鉄溶
出量を測定した。また、比較例１と同様にして還元処理
水の凝集処理を行い、沈殿を分離して処理水を得た。通
水２０時間後において、処理水中のセレン濃度は０.１
５mg／リットルであった。鉄溶出量は２００mg／リット
ルであった。通水開始時から２０時間後までの間の圧力
損失増加は１.０５kgf／cm2であった。実施例１〜２及び
比較例１〜２の結果を、第１表に示す。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 40 mm and a height of 1,000 mm was filled with gravel having a diameter of 5 to 10 mm to a height of 100 mm to form a support floor, and a hole diameter of 3 mm and a pitch of 10 mm were formed on the support floor. Was attached. The perforated plate was filled with 1,000 ml (about 5 kg) of spherical iron metal particles having an average particle diameter of 0.3 mm and having a particle diameter of 0.18 to 0.5 mm at 90% by weight or more. 6
Selenium concentration 0.5 mg / liter, suspended substance 100 mg /
Liters of coal-fired power plant flue gas desulfurization wastewater,
Hydrochloric acid was injected at a concentration of 600 mg / liter, and the water flow rate was 40 m in upward flow from the inlet provided at the bottom of the column.
Water was passed at / hr to perform a reduction treatment. The spreading rate of the fluidized bed of iron metal particles was 5%. The reduced effluent flowing out of the water outlet provided at the top of the column was sampled to measure the amount of iron eluted. Also, an aqueous solution of sodium hydroxide was added to the reduced water to adjust the pH to 9 to 9.5, the concentration of polyaluminum chloride was 500 mg / l, the concentration of potassium permanganate was 50 mg / l, and the polymer flocculant [Kurita Industry
Co., Ltd., Welculin] was added to give a concentration of 10 mg / liter, and aggregation treatment was carried out, and the precipitate was separated to obtain treated water. After 20 hours of passing water, the selenium concentration in the treated water was 0.03 mg / liter. The iron elution amount is 400mg /
Liters. The pressure loss increase from the start of water flow to 20 hours later was 0.02 kgf / cm 2 . Example 2 Using a column packed with the same iron metal particles as in Example 1, 6
Selenium concentration 0.3 mg / l, suspended substance 500 mg /
Liters of coal-fired power plant flue gas desulfurization wastewater,
Hydrochloric acid was injected to a concentration of 400 mg / liter, and the water flow speed was 40 m in upward flow from the inlet provided at the bottom of the column.
Water was passed at / hr to perform a reduction treatment. The spreading ratio of the fluidized bed of iron metal particles was 6%. In the same manner as in Example 1, reduction-treated water flowing out from a water outlet provided at the top of the column was sampled to measure the amount of iron eluted. In addition, coagulation treatment of the reduction treatment water was performed in the same manner as in Example 1, and the precipitate was separated to obtain treatment water. After 20 hours of passing water, the selenium concentration in the treated water was 0.05 mg / liter. Iron elution amount is 25
It was 0 mg / liter. The pressure loss increase from the start of water flow to 20 hours later was 0.05 kgf / cm 2 . Comparative Example 1 A gravel having a diameter of 5 to 10 mm was filled to a height of 100 mm under an acrylic resin column having an inner diameter of 40 mm and a height of 1,000 mm to form a support floor. On this support floor, a hole diameter of 3 mm and a pitch of 10 mm were provided. Was attached. Particle size 0.6m on perforated plate
m of uniform spherical iron metal particles of 1,000 ml (about 5 kg). Hydrochloric acid was injected into the flue gas desulfurization effluent of a coal-fired power plant containing the same hexavalent selenium concentration of 0.5 mg / L and suspended material of 100 mg / L as in Example 1, so that the concentration became 600 mg / L. From the inlet provided in the above at a flow rate of 40 m / hr in an upward flow to perform a reduction treatment. The iron metal particles in the column did not expand and maintained the state of the fixed bed. The reduced effluent flowing out of the water outlet provided at the top of the column was sampled to measure the amount of iron eluted. Also, an aqueous solution of sodium hydroxide was added to the reduced water to adjust the pH to 9 to 9.5, the concentration of polyaluminum chloride was 500 mg / l, the concentration of potassium permanganate was 50 mg / l, and the polymer flocculant [Kurita Industry
Co., Ltd., Welculin] was added to give a concentration of 10 mg / liter, and aggregation treatment was carried out, and the precipitate was separated to obtain treated water. After 20 hours of passing water, the selenium concentration in the treated water was 0.20 mg / liter. 350mg / iron
Liters. The pressure loss increase from the start of water flow to 20 hours later was 0.75 kgf / cm 2 . Comparative Example 2 Using a column packed with the same iron metal particles as in Comparative Example 1, the same flue gas desulfurization of a coal-fired power plant containing the same hexavalent selenium concentration of 0.3 mg / L and suspended material of 500 mg / L as in Example 2. Hydrochloric acid was injected into the waste water so as to have a concentration of 400 mg / liter, and water was passed upward at a flow rate of 40 m / hr through an inlet provided at the lower part of the column to perform a reduction treatment. The iron metal particles in the column did not expand and maintained the state of the fixed bed. In the same manner as in Comparative Example 1, reduction-treated water flowing out from a water outlet provided in the upper part of the column was sampled to measure the amount of iron eluted. In addition, in the same manner as in Comparative Example 1, the coagulation treatment of the reduced treatment water was performed, and the precipitate was separated to obtain treated water. After 20 hours of passing water, the concentration of selenium in the treated water is 0.1.
It was 5 mg / liter. The iron elution amount was 200 mg / liter. The pressure loss increase from the start of water flow to 20 hours later was 1.05 kgf / cm 2 . Table 1 shows the results of Examples 1 and 2 and Comparative Examples 1 and 2.
【００１１】[0011]
【表１】 [Table 1]
【００１２】実施例１と比較例１、実施例２と比較例２
の結果を対比すると、同一の排煙脱硫排水に同じ量の塩
酸を注入しても、鉄金属粒子が流動層を形成する実施例
の方が、鉄金属粒子が固定床となっている比較例より
も、鉄の溶出量が多いことが分かる。これは、実施例に
おいては、鉄金属粒子の表面の汚濁はほとんど生じてい
ないのに対して、比較例においては、排水中に含まれる
懸濁物質によって、鉄金属粒子の表面が汚濁されたため
と考えられる。これに伴って、実施例においては、処理
水中のセレン濃度が十分に低下しているのに対して、比
較例においては、６価セレンの還元反応が不十分とな
り、処理水中のセレン濃度が高い。また、実施例におい
ては、２０時間通水後も圧力損失はほとんど増加してい
ないが、比較例においては、圧力損失の増加が大きい。
これは、実施例においては、鉄金属粒子流動層には懸濁
物質が蓄積しないのに対して、比較例においては、鉄金
属粒子充填層に懸濁物質が蓄積したためと考えられる。Example 1 and Comparative Example 1, Example 2 and Comparative Example 2
Comparing the results of the above, even when the same amount of hydrochloric acid is injected into the same flue gas desulfurization effluent, the example in which the iron metal particles form a fluidized bed is a comparative example in which the iron metal particles form a fixed bed. It can be seen that the elution amount of iron is larger than that of iron. This is because the surface of the iron metal particles was hardly polluted by the suspended substances contained in the wastewater in the comparative example, whereas the surface of the iron metal particles was hardly polluted in the examples. Conceivable. Accordingly, in the examples, the selenium concentration in the treated water is sufficiently reduced, whereas in the comparative example, the reduction reaction of hexavalent selenium is insufficient, and the selenium concentration in the treated water is high. . Further, in the example, the pressure loss hardly increased even after passing water for 20 hours, but in the comparative example, the increase in the pressure loss was large.
This is considered to be because the suspended substance did not accumulate in the iron metal particle fluidized bed in the example, whereas the suspended substance accumulated in the iron metal particle packed bed in the comparative example.
【００１３】[0013]
【発明の効果】本発明のセレン含有排水の処理方法によ
れば、排水中の懸濁物質をあらかじめ除去する必要がな
く、例えば、７００〜１,０００mg／リットルの懸濁物
質を含む排煙脱硫排水をそのまま処理することができ
る。また、鉄金属粒子の洗浄において、高流速の水によ
る洗浄の必要がなく、通水処理を継続したまま単に空気
の吹き込みを行うことにより、鉄金属粒子を洗浄するこ
とができる。According to the method for treating selenium-containing wastewater of the present invention, it is not necessary to remove suspended substances in the wastewater in advance, and for example, flue gas desulfurization containing 700 to 1,000 mg / liter of suspended substances. Wastewater can be treated as it is. Further, in the cleaning of the iron metal particles, it is not necessary to perform the cleaning with water at a high flow rate, and the iron metal particles can be cleaned by simply blowing air while continuing the water passage treatment.
Claims (3)
水して排水中のセレンを還元処理することを特徴とする
セレン含有排水の処理方法。1. A method for treating selenium-containing wastewater, comprising passing selenium-containing wastewater through a fluidized bed of iron metal particles to reduce selenium in the wastewater.
mmである請求項１記載のセレン含有排水の処理方法。2. The iron metal particles have an average particle size of 0.25 to 0.35.
The method for treating selenium-containing wastewater according to claim 1, wherein
ある請求項１記載のセレン含有排水の処理方法。3. The method for treating selenium-containing wastewater according to claim 1, wherein the development rate of the fluidized bed of iron metal particles is 3 to 20%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP34016997A JP3870405B2 (en) | 1997-12-10 | 1997-12-10 | Treatment of selenium-containing wastewater |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP34016997A JP3870405B2 (en) | 1997-12-10 | 1997-12-10 | Treatment of selenium-containing wastewater |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH11169869A true JPH11169869A (en) | 1999-06-29 |
| JP3870405B2 JP3870405B2 (en) | 2007-01-17 |
Family
ID=18334401
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP34016997A Expired - Fee Related JP3870405B2 (en) | 1997-12-10 | 1997-12-10 | Treatment of selenium-containing wastewater |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3870405B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001025777A (en) * | 1999-07-15 | 2001-01-30 | Kurita Water Ind Ltd | Water treating method |
| JP2002126758A (en) * | 2000-10-30 | 2002-05-08 | Taiheiyo Cement Corp | Method for treating water |
| JP2007216228A (en) * | 2007-05-16 | 2007-08-30 | Chiyoda Corp | Method for selenium removal from waste water |
-
1997
- 1997-12-10 JP JP34016997A patent/JP3870405B2/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001025777A (en) * | 1999-07-15 | 2001-01-30 | Kurita Water Ind Ltd | Water treating method |
| JP4507267B2 (en) * | 1999-07-15 | 2010-07-21 | 栗田工業株式会社 | Water treatment method |
| JP2002126758A (en) * | 2000-10-30 | 2002-05-08 | Taiheiyo Cement Corp | Method for treating water |
| 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 |
|---|---|
| JP3870405B2 (en) | 2007-01-17 |
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