JPH09253686A - Apparatus for treating waste water containing selenium - Google Patents
Apparatus for treating waste water containing seleniumInfo
- Publication number
- JPH09253686A JPH09253686A JP9004696A JP9004696A JPH09253686A JP H09253686 A JPH09253686 A JP H09253686A JP 9004696 A JP9004696 A JP 9004696A JP 9004696 A JP9004696 A JP 9004696A JP H09253686 A JPH09253686 A JP H09253686A
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- JP
- Japan
- Prior art keywords
- selenium
- biological treatment
- tank
- treatment tank
- tanks
- 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.)
- Pending
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Classifications
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- Y02W10/12—
Landscapes
- Purification Treatments By Anaerobic Or Anaerobic And Aerobic Bacteria Or Animals (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、鉱山排水、火力発
電所排水、ガラス工場排水等のセレンを含有する排水の
処理方法及び処理装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for treating selenium-containing wastewater such as mine drainage, thermal power plant wastewater and glass factory wastewater.
【０００２】[0002]
【従来の技術】前述したようなセレン含有排水中におい
て、セレンは通常、ＳｅＯ3 2-（亜セレン酸イオン：４
価セレン）及び／又はＳｅＯ4 2-（セレン酸イオン：６
価セレン）の形で溶存している。なお、これらのイオン
が排水中に単独で存在することもあるが、通常は、両者
が共存している場合が多い。このようなセレン含有排水
中に含まれるセレン除去技術に関しては、平成５年の水
質汚濁防止法改正によりセレンが新たに規制項目に加え
られたという法的背景があり、それまでは除去を特に必
要としていなかったことから、十分な検討が行われてい
ないのが実情である。2. Description of the Related Art In the selenium-containing wastewater as described above, selenium is usually contained in SeO 3 2- (selenite ion: 4
Selenium) and / or SeO 4 2− (selenate ion: 6)
It is dissolved in the form of (valent selenium). Although these ions may exist alone in the waste water, usually, both of them coexist in many cases. Regarding the technology for removing selenium contained in such selenium-containing wastewater, there is a legal background that selenium was newly added to the regulatory items due to the revision of the Water Pollution Control Act in 1993, and until that time, removal was particularly necessary. Therefore, the fact is that sufficient consideration has not been made.
【０００３】その中で、これまでセレン含有排水中に含
まれるＳｅＯ3 2-及び／又はＳｅＯ4 2-（以下セレン酸化
物ということもある）を除去する方法として検討されて
いるのは、下記〜の方法である。 セレン含有排水中に含まれるセレン酸化物を嫌気性生
物処理によって単体セレン（Ｓｅ）に還元した後、この
単体セレンを分離除去する方法。 セレン含有排水にマグネシウム塩、亜鉛塩、第二鉄塩
といった金属塩を添加して、セレンをこれらの金属の不
溶性セレン化合物として分離除去する方法。 セレン含有排水にセレン酸化物を単体セレンに還元で
きる第一鉄塩を添加して、セレン酸化物を不溶化した
後、生成した不溶化物を沈殿等によって分離除去する方
法。Among them, the following methods have been studied as methods for removing SeO 3 2− and / or SeO 4 2− (hereinafter sometimes referred to as selenium oxide) contained in selenium-containing wastewater. Is the method of. A method of reducing selenium oxide contained in selenium-containing wastewater to simple selenium (Se) by anaerobic biological treatment, and then separating and removing this simple selenium. A method of adding a metal salt such as a magnesium salt, a zinc salt, or a ferric salt to selenium-containing wastewater to separate and remove selenium as an insoluble selenium compound of these metals. A method in which a ferrous salt capable of reducing selenium oxide to elemental selenium is added to wastewater containing selenium to insolubilize the selenium oxide, and then the generated insoluble matter is separated and removed by precipitation or the like.
【０００４】[0004]
【発明が解決しようとする課題】前述したセレン除去方
法の内、薬品を添加して不溶性セレン化合物を生成させ
るの化学的処理法では、４価のＳｅＯ3 2-からは不溶
性セレン化合物が比較的容易に生成するが、６価のＳｅ
Ｏ4 2-からは不溶性セレン化合物が生成しにくく、した
がって６価のＳｅＯ4 2-を除去することが難しい。ま
た、の第一鉄塩による化学的処理法では、ＳｅＯ3 2-
及びＳｅＯ4 2-の両方を除去することが可能であるが、
この方法は第一鉄塩をかなり多量に必要とするととも
に、固液分離後の不溶化物（汚泥）が多量に発生するた
め、ランニングコスト、廃棄物処理コストの点で不利で
あった。これに対し、セレン酸化物を嫌気性生物処理に
より単体セレンに還元して除去するの生物学的処理法
では、ＳｅＯ3 2-及びＳｅＯ4 2-の両方をＳｅに還元可能
であり、しかも薬品を何ら使用しないことから経済的に
も有利な方法である。Among the above-mentioned selenium removing methods, in the chemical treatment method of adding a chemical to produce an insoluble selenium compound, the insoluble selenium compound is relatively removed from tetravalent SeO 3 2−. Easily generated, but with hexavalent Se
An insoluble selenium compound is unlikely to be produced from O 4 2− , and thus it is difficult to remove hexavalent SeO 4 2− . In addition, in the chemical treatment method with ferrous salt of, SeO 3 2-
And it is possible to remove both SeO 4 2-
This method requires a considerably large amount of ferrous salt and produces a large amount of insoluble matter (sludge) after solid-liquid separation, which is disadvantageous in terms of running cost and waste treatment cost. On the other hand, in the biological treatment method of removing selenium oxide by reducing it to simple substance selenium by anaerobic biological treatment, both SeO 3 2− and SeO 4 2− can be reduced to Se. This is an economically advantageous method because it does not use any.
【０００５】しかし、の生物学的処理法は、処理性能
の安定性の点で問題がある。例えば、本発明者らの検討
によれば、比較的高濃度のセレン含有排水や、セレン濃
度や流量が変動する排水の場合には、負荷変動等の原因
により処理水質の不安定化が生じることがわかった。However, the biological treatment method (1) has a problem in terms of stability of treatment performance. For example, according to the study by the present inventors, in the case of selenium-containing wastewater having a relatively high concentration or wastewater having a varying selenium concentration and flow rate, the treated water quality may become unstable due to a cause such as load fluctuation. I understood.
【０００６】本発明は、上記事情に鑑みてなされたもの
で、セレン含有排水中に存在するセレン酸化物を嫌気性
生物処理により単体セレンに還元して不溶化し除去する
生物処理装置であって、生物処理による処理性能の安定
化を図り、セレン含有排水中から４価のＳｅＯ3 2-又は
６価のＳｅＯ4 2-、若しくはその両方を効率的かつ安定
に除去できるようにしたセレン含有排水の処理装置を提
供することを目的とする。The present invention has been made in view of the above circumstances, and is a biological treatment apparatus for reducing selenium oxide present in selenium-containing wastewater by anaerobic biological treatment into insoluble selenium and removing it. A selenium-containing wastewater that has been treated to stabilize its treatment performance by biological treatment and is capable of efficiently and stably removing tetravalent SeO 3 2-, hexavalent SeO 4 2- , or both from the selenium-containing wastewater. An object is to provide a processing device.
【０００７】[0007]
【課題を解決するための手段】本発明者らは、前記目的
を達成するために鋭意検討を行い、下記知見を得た。Means for Solving the Problems The inventors of the present invention have made extensive studies in order to achieve the above objects, and have obtained the following findings.
【０００８】（ａ）セレン酸化物を単体セレンに還元す
る嫌気性生物処理では、連続的に処理を行っている内に
生物処理槽内に特定の水の通路が形成され、被処理水が
この通路ばかりを通る現象（ショートパス）が生じるこ
とが考えられる。このようなショートパスが起きると、
微生物と被処理水との接触効率が悪くなるので、還元反
応の反応効率及び処理の安定性が低下する。そこで、本
発明者らは、ショートパスが起こったときに処理性能が
低下することを極力防止できる手段を検討した結果、生
物処理を複数の生物処理槽によって順次行うようにする
ことにより該目的を達成でき、処理水質を安定化させる
ことができることを見い出した。(A) In the anaerobic biological treatment for reducing selenium oxide to simple selenium, a specific water passage is formed in the biological treatment tank during continuous treatment, and the water to be treated is It is conceivable that a phenomenon (short path) that only passes through the passage will occur. When such a short pass occurs,
Since the contact efficiency between the microorganisms and the water to be treated becomes poor, the reaction efficiency of the reduction reaction and the stability of the treatment decrease. Therefore, as a result of studying means for preventing the treatment performance from being deteriorated as much as possible when a short pass occurs, the present inventors have achieved the object by sequentially performing biological treatment by a plurality of biological treatment tanks. It has been found that this can be achieved and the treated water quality can be stabilized.
【０００９】すなわち、単独の生物処理槽を用いて生物
処理を行う場合、その生物処理槽でショートパスが生じ
て還元反応の反応効率及び処理の安定性が低下すると、
還元されなかったセレン酸化物は処理水中に残存したま
まとなる。これに対し、生物処理を複数の生物処理槽に
よって順次行うようにした場合には、前段の生物処理槽
でショートパスが生じたとしても、その流出水は後段の
生物処理槽で再度処理されるので、最終的な処理水質の
悪化を防止することができる。That is, when biological treatment is performed using a single biological treatment tank, if a short path occurs in the biological treatment tank and the reaction efficiency of the reduction reaction and the stability of the treatment decrease,
The unreduced selenium oxide remains in the treated water. On the other hand, in the case where the biological treatment is performed sequentially by a plurality of biological treatment tanks, even if a short path occurs in the biological treatment tank in the previous stage, the outflow water is treated again in the biological treatment tank in the subsequent stage. Therefore, deterioration of the final treated water quality can be prevented.
【００１０】（ｂ）セレン酸化物を単体セレンに還元す
る嫌気性生物処理では、処理を続行するにしたがって嫌
気性微生物が増殖するとともに、セレン酸化物の還元
後、不溶化した単体セレンが処理槽内に蓄積し、嫌気性
微生物からなる汚泥と混合状態で存在するようになるた
め、定期的に処理槽内を洗浄して蓄積した単体セレンを
余剰汚泥とともに除去する必要がある。処理槽内からの
単体セレンの除去は、浮遊式生物処理槽では、生物処理
槽の後段に沈殿槽を設け、そこから単体セレンを含む汚
泥を引き抜くことにより行う。また、固定床式生物処理
槽、流動床式生物処理槽では、空気逆洗、水逆洗等によ
って洗浄することにより、処理槽から単体セレンを含む
汚泥を排出することにより行う。(B) In the anaerobic biological treatment for reducing selenium oxide to elemental selenium, anaerobic microorganisms grow as the treatment is continued, and after the reduction of selenium oxide, insolubilized elemental selenium remains in the treatment tank. The accumulated selenium accumulates in the sludge and is present in a mixed state with the sludge composed of anaerobic microorganisms. Therefore, it is necessary to regularly wash the inside of the treatment tank to remove the accumulated selenium together with the excess sludge. In the floating biological treatment tank, the removal of elemental selenium from the inside of the treatment tank is performed by providing a settling tank after the biological treatment tank and pulling out sludge containing the elemental selenium therefrom. In the fixed-bed biological treatment tank and the fluidized-bed biological treatment tank, the sludge containing simple selenium is discharged from the treatment tank by washing by air backwashing, water backwashing, or the like.
【００１１】ところが、上述のように処理槽内を洗浄し
て単体セレンを除去する生物処理槽の場合、単体セレン
とともに汚泥も系外に排出されるため、場合によっては
処理槽の汚泥量が減少して還元反応の反応効率及び安定
性が低下し、一時的な処理水質の悪化が生じることがあ
る。特に、排水中のセレン酸化物が高濃度である場合に
は、処理槽内に蓄積する単体セレンはかなり多量となる
ため、頻繁に処理槽内を洗浄する必要が生じ、汚泥の系
外への過剰な流出による一時的な処理水質の悪化がしば
しば生じることになる。However, in the case of the biological treatment tank for cleaning the inside of the treatment tank to remove the simple selenium as described above, the sludge is discharged out of the system together with the simple selenium, so that the sludge amount in the treatment tank is reduced in some cases. As a result, the reaction efficiency and stability of the reduction reaction may decrease, and the quality of treated water may temporarily deteriorate. In particular, when the concentration of selenium oxide in the waste water is high, the amount of elemental selenium that accumulates in the treatment tank will be quite large, so it will be necessary to frequently clean the inside of the treatment tank, and sludge outside the system will be discharged. Temporary deterioration of treated water quality due to excessive runoff will often occur.
【００１２】そこで、本発明者らは、処理槽内を洗浄し
て単体セレンを除去したときに処理水質の悪化が生じる
ことを防止する手段について検討を行った結果、生物処
理を複数の生物処理槽によって順次行うようにするとと
もに、全ての生物処理槽を一度に洗浄せず、後述するよ
うに、洗浄槽を１槽ずつあるいは２槽以上を組にして、
それぞれ時期をずらして順次洗浄することにより、汚泥
が一時的に多量に系外に流出することを防止して、過剰
な汚泥の系外への流出に起因する前述したような一時的
な処理水質の悪化を低減できること、とりわけ洗浄によ
って還元性能が低下した処理槽を最終槽に移し、洗浄し
ていない還元性能の良好な処理槽を前にシフトするよう
にした場合（後述）には、処理水質の一時的な悪化をよ
り効果的に防止できることを見い出した。[0012] Therefore, the present inventors have conducted a study on means for preventing the deterioration of the quality of the treated water when the inside of the treatment tank is washed to remove the simple selenium, and as a result, the biological treatment is carried out by a plurality of biological treatments. In addition to cleaning all the biological treatment tanks at once, the cleaning tanks should be cleaned one by one or as a set of two or more tanks.
By sequentially cleaning at different times, a large amount of sludge is temporarily prevented from flowing out of the system, and the temporary treated water quality as described above due to excess sludge flowing out of the system In particular, if the treatment tank whose reduction performance has deteriorated due to cleaning is moved to the final tank and the treatment tank that has not been cleaned and has good reduction performance is shifted forward (described later), the treated water quality can be reduced. It has been found that the temporary deterioration of the can be effectively prevented.
【００１３】（ｃ）セレン含有排水中にセレン酸化物と
ともに硝酸イオンが共存する場合、これらの生物による
還元反応の起こり易さは異なる。すなわち、セレン酸化
物よりも硝酸性イオンの方が還元されやすい。したがっ
て、単独の生物処理槽で硝酸性イオンが共存するセレン
含有排水を処理する場合、硝酸性イオンが優先的に還元
されてセレン酸化物の還元が妨害され、セレン酸化物が
十分に単体セレンに還元されないことが考えられる。(C) When nitrate ions coexist with selenium oxide in the selenium-containing wastewater, the easiness of reduction reaction by these organisms differs. That is, nitrate ions are more easily reduced than selenium oxide. Therefore, when treating selenium-containing wastewater in which nitrate ions coexist in a single biological treatment tank, nitrate ions are preferentially reduced to interfere with the reduction of selenium oxide, and selenium oxide is sufficiently converted to simple selenium. It is possible that it will not be reduced.
【００１４】そこで、本発明者らは、硝酸性イオンによ
るセレン酸化物の還元の妨害をなるべき排除するための
手段について検討を行った結果、生物処理を複数の生物
処理槽によって順次行うようにした場合には、最前段の
生物処理槽で硝酸性イオンが優先的に還元される結果、
それより後段の生物処理槽では硝酸性イオン濃度が低減
した状態で、硝酸性イオンにあまり妨害されることなく
セレン酸化物が効率良くかつ安定に還元されることを知
見した。Therefore, the inventors of the present invention have studied the means for eliminating the interference of the reduction of selenium oxide by nitrate ions, and found that the biological treatment should be performed sequentially by a plurality of biological treatment tanks. In that case, as a result of the nitrate ions being preferentially reduced in the frontmost biological treatment tank,
It was found that selenium oxide is efficiently and stably reduced in the biological treatment tank at the latter stage in a state where the concentration of nitrate ion is reduced without being significantly disturbed by nitrate ion.
【００１５】また、セレン含有排水中には、硝酸イオン
とともに硫酸イオンが共存していることがあり、この硫
酸イオンも還元されるが、硫酸イオンはセレン酸化物よ
りも還元されにくいことが考えられる。そのため、単独
の生物処理槽で硝酸性イオン及び硫酸イオンが共存する
セレン含有排水を処理する場合、硝酸性イオンが優先的
に還元されてセレン酸化物及び硫酸イオンの還元が妨害
される可能性がある。In the selenium-containing wastewater, sulfate ions may coexist with nitrate ions, and the sulfate ions are also reduced, but it is considered that the sulfate ions are less likely to be reduced than the selenium oxide. . Therefore, when treating selenium-containing wastewater in which nitrate ions and sulfate ions coexist in a single biological treatment tank, nitrate ions may be preferentially reduced to interfere with the reduction of selenium oxide and sulfate ions. is there.
【００１６】したがって、生物処理を複数、好ましくは
３槽以上の生物処理槽によって順次行うようにすれば、
最前段の処理槽で硝酸性イオンが優先的に還元され、そ
れより後段の処理槽では硝酸性イオン濃度が低減した状
態でセレン酸化物が優先的に還元され、それよりさらに
後段の処理槽ではセレン酸化物濃度が低減した状態で硫
酸イオンが還元されるようになるので、セレン酸化物、
硝酸イオン及び硫酸イオンをそれぞれ良好に還元するこ
とが可能となる。Therefore, if the biological treatment is carried out sequentially by a plurality of biological treatment tanks, preferably three or more biological treatment tanks,
Nitrate ions are preferentially reduced in the first-stage treatment tank, selenium oxide is preferentially reduced in the latter-stage treatment tank while the concentration of nitrate ions is reduced, and further in the latter-stage treatment tank. Sulfate ions will be reduced with the selenium oxide concentration reduced, so selenium oxide,
It becomes possible to satisfactorily reduce nitrate ions and sulfate ions, respectively.
【００１７】（ｄ）セレン酸化物、硝酸イオン、硫酸イ
オンのように還元反応の起こり易さが異なる物質の還元
では、各物質を還元する還元生物の増殖速度に違いがあ
ると考えられ、したがって還元反応により生じる余剰汚
泥量も異なると考えられる。その結果、このような還元
反応の起こり易さが異なる物質を含む排水の処理を単独
の生物処理槽で行うと、処理槽洗浄時における汚泥排出
時に増殖の遅い生物が系外に流出してしまい、その生物
による還元反応の反応効率が悪くなる。これに対し、生
物処理を複数の生物処理槽によって順次行うようにし、
各物質を還元する還元生物の棲み分けを行うことによっ
て、汚泥排出時に増殖の遅い特定の生物が系外に過剰に
流出するようなことを防止して、各還元反応を効率的か
つ安定的に行わせることが可能となる。(D) In reducing substances such as selenium oxide, nitrate ion, and sulfate ion, which have different easiness of reduction reaction, it is considered that there is a difference in the growth rate of reducing organisms that reduce each substance. The amount of excess sludge generated by the reduction reaction is also considered to be different. As a result, if wastewater containing substances with different susceptibility to reduction reactions is treated in a single biological treatment tank, slow-growing organisms will flow out of the system when sludge is discharged during cleaning of the treatment tank. , The reaction efficiency of the reduction reaction by the organism becomes poor. On the other hand, biological treatment is performed sequentially by a plurality of biological treatment tanks,
By separating the reducing organisms that reduce each substance, it is possible to prevent specific organisms with slow growth from flowing out of the system excessively during sludge discharge, and to efficiently and stably perform each reducing reaction. It is possible to do it.
【００１８】本発明は、前記（ａ）〜（ｄ）の知見に基
づいてなされたもので、セレン含有排水中に存在するＳ
ｅＯ3 2-及び／又はＳｅＯ4 2-を嫌気性生物処理によりＳ
ｅに還元して不溶化し、除去する生物学的処理手段を備
えた排水処理装置において、前記生物学的処理手段が、
嫌気性生物処理を順次行う複数の生物処理槽を有するこ
とを特徴とするセレン含有排水の処理装置を提供する。The present invention was made on the basis of the findings of the above (a) to (d), and S existing in selenium-containing wastewater.
eO 3 2− and / or SeO 4 2− is treated by anaerobic biological treatment to give S
In a wastewater treatment device equipped with a biological treatment means for reducing to e to insolubilize and remove the biological treatment means,
Provided is a treatment device for selenium-containing wastewater, which has a plurality of biological treatment tanks for sequentially performing anaerobic biological treatment.
【００１９】以下、本発明装置につきさらに詳しく説明
する。本発明の生物学的処理手段では、セレン含有排水
（原水）中に存在するセレン酸化物を嫌気性生物処理に
より単体セレンに還元して不溶化する。この場合、嫌気
性生物処理は、通性嫌気性条件で行えばよく、絶対嫌気
性条件までは要求されない。すなわち、水中に溶存酸素
が実質的に存在しない状態（無酸素状態）であればよ
く、硝酸イオン、亜硝酸イオンといった酸素を含むイオ
ン等は存在していてもよい。The apparatus of the present invention will be described in more detail below. In the biological treatment means of the present invention, selenium oxide existing in selenium-containing wastewater (raw water) is reduced to insoluble by reducing it to simple selenium by anaerobic biological treatment. In this case, the anaerobic biological treatment may be performed under facultative anaerobic conditions, and is not required even under absolute anaerobic conditions. That is, it is sufficient that dissolved oxygen does not substantially exist in water (anoxic state), and ions containing oxygen such as nitrate ions and nitrite ions may be present.
【００２０】本発明では、前記生物学的処理手段を、嫌
気性生物処理を順次行う複数の生物処理槽によって構成
する。生物処理槽の数は２層以上の複数であれば任意に
決定することができるが、好ましくは３〜５槽とする。
各生物処理槽の構成に限定はないが、例えば、固定床式
生物処理槽、流動床式生物処理槽、浮遊式生物処理槽、
スラッジブランケット式生物処理槽等を用いることがで
きる。この場合、複数の生物処理槽としては、同じ種類
のものを組み合わせてもよく、異なる種類のものを組み
合わせてもよい。また、生物処理槽を複数にする態様と
しては、独立した個別の生物処理槽を複数槽接続するよ
うにしてもよく、１つの槽の内部を仕切り板等で仕切る
ことにより１つの槽の内部に互いに連通した複数の生物
処理槽を形成するようにしてもよい。In the present invention, the biological treatment means comprises a plurality of biological treatment tanks for sequentially treating anaerobic organisms. The number of biological treatment tanks can be arbitrarily determined as long as it is a plurality of two or more layers, but it is preferably 3 to 5 tanks.
Although the structure of each biological treatment tank is not limited, for example, a fixed-bed biological treatment tank, a fluidized-bed biological treatment tank, a floating biological treatment tank,
A sludge blanket type biological treatment tank or the like can be used. In this case, the plurality of biological treatment tanks may be of the same type or may be of different types. In addition, as a mode in which a plurality of biological treatment tanks are provided, a plurality of independent individual biological treatment tanks may be connected, and the inside of one tank may be divided into partitions by a partition plate or the like. A plurality of biological treatment tanks that are in communication with each other may be formed.
【００２１】セレン酸化物を生物処理により単体セレン
に還元するには水素供与体を必要とするが、必要な水素
供与体（有機物など）がセレン含有排水（原水）中に不
足している場合、不足分の水素供与体を被処理水に添加
して不足を解消することができる。また、原水中に硝酸
イオンや硫酸イオンが存在し、かつセレン酸化物の還元
及び硝酸イオンや硫酸イオンの還元に必要な水素供与体
が原水中に不足している場合には、硝酸イオンや硫酸イ
オンの還元に必要な水素供与体の量を考慮して不足分の
水素供与体を被処理水に添加して不足を解消することが
好ましい。これは、硝酸イオンや硫酸イオンの還元にも
水素供与体が消費されるからである。水素供与体は、全
部の槽での還元に必要な全量を最前段の生物処理槽の手
前で原水に添加したり、最前段の生物処理槽内で被処理
水に添加したりすることができる。また、各槽の手前あ
るいは各槽内でその槽での還元に必要な量をそれぞれ被
処理水に添加するようにしてもよい。A hydrogen donor is required to reduce selenium oxide to elemental selenium by biological treatment, but when the required hydrogen donor (organic matter, etc.) is insufficient in the selenium-containing wastewater (raw water), The shortage of hydrogen donor can be added to the water to be treated to eliminate the shortage. In addition, when nitrate ions and sulfate ions are present in the raw water and the hydrogen donors necessary for the reduction of selenium oxide and the reduction of nitrate ions and sulfate ions are insufficient in the raw water, nitrate ions and sulfate ions are required. Considering the amount of hydrogen donor required for ion reduction, it is preferable to add a shortage of hydrogen donor to the water to be treated to eliminate the shortage. This is because the hydrogen donor is also consumed for the reduction of nitrate ions and sulfate ions. The hydrogen donor can be added to the raw water in front of the frontmost biological treatment tank, or to the water to be treated in the frontmost biological treatment tank, in the total amount required for reduction in all the tanks. . In addition, before or in each tank, the amount necessary for reduction in the tank may be added to the water to be treated.
【００２２】水素供与体としては、例えば、メタノー
ル、エタノール等のアルコール類、酢酸等の有機酸類、
糖類といった有機物、あるいは有機物を含む他の排水を
挙げることができる。また、水素供与体の添加量は、水
中の水素供与体の量が化学量論的な必要量の１．３倍量
以上となるような添加量とすることが適当である。な
お、処理水中から有機物を除去することが必要な場合
は、例えば、本発明装置による処理を終了した水を好気
性生物処理槽に導入して有機物酸化を行うことにより有
機物を除去することができる。Examples of hydrogen donors include alcohols such as methanol and ethanol, organic acids such as acetic acid,
Organic substances such as sugars, or other wastewater containing organic substances can be mentioned. It is appropriate that the amount of the hydrogen donor added is such that the amount of the hydrogen donor in the water is at least 1.3 times the stoichiometrically required amount. When it is necessary to remove the organic matter from the treated water, for example, the organic matter can be removed by introducing the water, which has been treated by the device of the present invention, into the aerobic biological treatment tank to oxidize the organic matter. .
【００２３】[0023]
【発明の実施の形態】図１は本発明に係るセレン含有排
水処理装置の一例を示すフロー図である。本装置では、
３槽の独立した固定床式生物処理槽Ａ、Ｂ、Ｃによって
生物学的処理手段が構成されており、これら生物処理槽
Ａ、Ｂ、Ｃで順次被処理水の処理を行う。各生物処理槽
Ａ、Ｂ、Ｃの内部には、砂利、焼成骨材、各種形状のプ
ラスチック等の微生物担体が充填されているとともに、
該担体の表面に嫌気性微生物が着生しており、被処理水
中に存在するセレン酸化物を嫌気性生物処理により不溶
性の単体セレンに還元し、除去するものである。1 is a flow chart showing an example of a selenium-containing wastewater treatment apparatus according to the present invention. With this device,
The biological treatment means is composed of three independent fixed-bed biological treatment tanks A, B, and C, and these biological treatment tanks A, B, and C sequentially treat the water to be treated. Inside each of the biological treatment tanks A, B, and C, microbial carriers such as gravel, fired aggregate, and plastics of various shapes are filled,
Anaerobic microorganisms are growing on the surface of the carrier, and the selenium oxide present in the water to be treated is reduced to an insoluble elemental selenium by the anaerobic biological treatment and removed.
【００２４】図１の装置では、前述したように、処理を
続行するにしたがって嫌気性微生物が増殖するととも
に、セレン酸化物の還元後に不溶化した単体セレンが処
理槽内に蓄積するため、定期的に処理槽内を洗浄して蓄
積した単体セレンを余剰の微生物とともに除去する必要
がある。この場合、次のような洗浄方法を採用すること
が好ましい。すなわち、洗浄時に必要以上の汚泥（微生
物）が系外に流出することを防止するために、全ての生
物処理槽Ａ、Ｂ、Ｃを一度に洗浄せず、１槽ずつあるい
は２槽を組にして、それぞれ時期をずらして順次洗浄す
ることが好ましい。これにより、過剰な汚泥の系外への
流出に起因する一時的な処理水質の悪化を低減すること
ができる。In the apparatus shown in FIG. 1, as described above, the anaerobic microorganisms grow as the treatment is continued, and simple selenium insolubilized after the reduction of the selenium oxide accumulates in the treatment tank. It is necessary to wash the inside of the treatment tank and remove the accumulated selenium along with the surplus microorganisms. In this case, it is preferable to adopt the following cleaning method. That is, in order to prevent unnecessary sludge (microorganisms) from flowing out of the system during cleaning, all biological treatment tanks A, B, and C are not cleaned at one time, but one tank or two tanks are grouped together. Therefore, it is preferable that the cleaning is performed sequentially at different times. As a result, it is possible to reduce the temporary deterioration of the quality of the treated water due to the excess sludge flowing out of the system.
【００２５】洗浄による過剰汚泥の排出後の処理水質の
悪化をさらに防止したい場合は、以下のようにすること
ができる。すなわち、まず第１槽であるＡ槽のみを洗浄
し、洗浄後は図１（ｂ）に示すようにＡ槽を最終槽に変
更し、Ｂ槽を第１槽、Ｃ槽を第２槽というように１段づ
つ前にシフトする。次の洗浄時は第１槽であるＢ槽のみ
を洗浄し、洗浄後はＢ槽を最終槽とする（図１ｃ）。各
洗浄時にこれを繰り返す。この場合、処理槽の位置を実
際に入れ替えずに、原水注入位置の変更や配管弁の開閉
などにより、被処理水の流入順序を変えて同様の処理槽
のシフトを実現してもよい。このように洗浄によって還
元性能が低下した処理槽を最終槽に移し、洗浄していな
い還元性能の良好な第２槽以降をそれぞれ前にシフトす
ることにより、汚泥排出後の処理水質の悪化を最少限に
抑えることが可能となる。If it is desired to further prevent deterioration of the quality of treated water after discharging excess sludge by washing, the following can be carried out. That is, first, only the first tank A is cleaned, and after cleaning, the tank A is changed to the final tank as shown in FIG. 1B, the tank B is called the first tank, and the tank C is called the second tank. Shift one step forward. At the time of the next cleaning, only the first tank B is cleaned, and after cleaning, tank B is the final tank (Fig. 1c). Repeat this with each wash. In this case, the same treatment tank shift may be realized by changing the inflow order of the water to be treated by changing the raw water injection position or opening / closing the piping valve without actually changing the treatment tank position. In this way, by moving the treatment tank whose reduction performance has deteriorated due to washing to the final tank and shifting the second and subsequent non-washed tanks with good reduction performance forward, the deterioration of treated water quality after sludge discharge is minimized. It is possible to limit it.
【００２６】[0026]
【実施例】以下に述べる実験を行って本発明の効果を確
認した。水道水に下記成分を下記濃度で溶解したセレン
含有模擬排水を原水とし、下記の２つの処理Ｘ及びＹを
行った。なお、メタノールは水素供与体、塩化アンモニ
ウム及びリン酸２水素カリウムは微生物栄養源である。EXAMPLES The following experiments were conducted to confirm the effects of the present invention. The following two treatments X and Y were performed using selenium-containing simulated wastewater in which the following components were dissolved in tap water at the following concentrations as raw water. In addition, methanol is a hydrogen donor, and ammonium chloride and potassium dihydrogen phosphate are microbial nutrient sources.
【００２７】原水組成 セレン酸ナトリウム（６価セレン） １０ｍｇＳｅ／ｌ 亜セレン酸ナトリウム（４価セレン） ５ｍｇＳｅ／ｌ 塩化アンモニウム １ｍｇＮ／ｌ リン酸２水素カリウム ０．２ｍｇＰ／ｌ メタノール ５０ｍｇＣＨ3ＯＨ／ｌ Composition of Raw Water Sodium selenite (selenium hexavalent) 10 mg Se / l Sodium selenite (selenium tetravalent) 5 mg Se / l Ammonium chloride 1 mg N / l Potassium dihydrogen phosphate 0.2 mg P / l Methanol 50 mg CH 3 OH / l
【００２８】処理Ｘ：本発明例 ２層の独立した固定床式生物処理槽を接続して通性嫌気
性条件下で嫌気性生物処理を順次行った。各生物処理槽
としては、容量約０．９リットルの円筒状カラムに多孔
性の焼成骨材（オルガノ社製アクチライト）を見かけ容
量が０．７５リットルとなるように充填したものを用
い、２個の生物処理槽を配管を介して直列に接続した。
これらの生物処理槽に被処理水の滞留時間が合計で約５
時間となるように連続的に通水した。 Treatment X : Inventive Example An anaerobic biological treatment was sequentially carried out under a facultative anaerobic condition by connecting two independent fixed-bed biological treatment tanks. As each biological treatment tank, a cylindrical column having a capacity of about 0.9 liter was used, in which porous fired aggregate (Actilite manufactured by Organo) was packed so that the apparent capacity was 0.75 liter. The individual biological treatment tanks were connected in series via a pipe.
The total residence time of the treated water in these biological treatment tanks is about 5
Water was continuously supplied so that the time was reached.
【００２９】処理Ｙ：比較例 単独の固定床式生物処理槽を用いて通性嫌気性条件下で
嫌気性生物処理を行った。生物処理槽としては、容量約
１．８リットルの円筒状カラムに多孔性の焼成骨材（オ
ルガノ社製アクチライト）を見かけ容量が１．５リット
ルとなるように充填したもの（処理Ｘの装置の倍容量）
を用いた。この生物処理槽に被処理水の滞留時間が約５
時間となるように連続的に通水した。 Treatment Y : Comparative Example An anaerobic biological treatment was carried out under a facultative anaerobic condition using a single fixed-bed biological treatment tank. As the biological treatment tank, a cylindrical column having a capacity of about 1.8 liters was filled with a porous fired aggregate (Actilite manufactured by Organo Co., Ltd.) so that the apparent capacity was 1.5 liters (apparatus for treatment X). Double capacity)
Was used. The retention time of the treated water in this biological treatment tank is about 5
Water was continuously supplied so that the time was reached.
【００３０】Ｘ、Ｙの処理終了後の水中のＳｅＯ3 2及び
ＳｅＯ4 2の濃度をそれぞれ測定した。その結果、処理Ｘ
の最終処理水においては、９９％以上の６価セレン（Ｓ
ｅＯ4 2）が除去され、また４価セレン（ＳｅＯ3 2-）の
残留量は６価セレンの還元により４価セレンが生じるこ
ともあって約３ｍｇＳｅ／ｌであった。これに対し、処
理Ｙの処理水では、６価セレンの除去率は約９５％であ
り、また４価セレンの残留量は約６ｍｇＳｅ／ｌであっ
た。したがって、生物処理を複数の生物処理槽を用いて
順次行うことにより、セレン酸化物の還元反応がより安
定して起こることが確認された。After the treatment of X and Y, the concentrations of SeO 3 2 and SeO 4 2 in water were measured. As a result, process X
In the final treated water of 99% or more, hexavalent selenium (S
eO 4 2 ) was removed, and the residual amount of tetravalent selenium (SeO 3 2− ) was about 3 mgSe / l, because tetravalent selenium may be produced by reduction of hexavalent selenium. On the other hand, in the treated water of Treatment Y, the removal rate of hexavalent selenium was about 95%, and the residual amount of tetravalent selenium was about 6 mgSe / l. Therefore, it was confirmed that the reduction reaction of selenium oxide occurs more stably by sequentially performing the biological treatment using a plurality of biological treatment tanks.
【００３１】[0031]
【発明の効果】以上説明したように、本発明装置によれ
ば、(a)ショートパスによって生じる処理性能の安定性
低下の防止、(b)各生物処理槽を時期をずらして洗浄す
ることによる一時的な処理水質悪化の防止、(c)最前段
の生物処理槽で硝酸性イオンを還元することによる還元
反応の反応効率及び安定性の向上、(d)各物質を還元す
る還元生物の棲み分けを行うことによる還元反応の反応
効率及び安定性の向上を達成することができ、そのため
セレン含有排水中から４価のＳｅＯ3 2-及び／又は６価
のＳｅＯ4 2-を効率的かつ安定に除去することが可能で
ある。As described above, according to the apparatus of the present invention, (a) prevention of deterioration in stability of processing performance caused by short path, (b) cleaning of biological treatment tanks at different times Prevent temporary deterioration of treated water quality, (c) improve reaction efficiency and stability of reduction reaction by reducing nitrate ions in the frontmost biological treatment tank, (d) residence of reducing organisms that reduce each substance It is possible to improve the reaction efficiency and stability of the reduction reaction by carrying out the separation, and therefore tetravalent SeO 3 2− and / or hexavalent SeO 4 2− from the selenium-containing wastewater can be efficiently and stably obtained. Can be removed.
【図１】本発明に係るセレン含有排水処理装置の一例を
示すフロー図である。FIG. 1 is a flow chart showing an example of a selenium-containing wastewater treatment device according to the present invention.
Ａ 固定床式生物処理槽 Ｂ 固定床式生物処理槽 Ｃ 固定床式生物処理槽 A fixed-bed biological treatment tank B fixed-bed biological treatment tank C fixed-bed biological treatment tank
Claims (1)
及び／又はＳｅＯ4 2-を嫌気性生物処理によりＳｅに還
元して不溶化し、除去する生物学的処理手段を備えた排
水処理装置において、前記生物学的処理手段が、嫌気性
生物処理を順次行う複数の生物処理槽を有することを特
徴とするセレン含有排水の処理装置。1. SeO 3 2- existing in wastewater containing selenium
And / or SeO 4 2− in a wastewater treatment apparatus provided with a biological treatment means for reducing and insolubilizing SeO 4 by anaerobic treatment to remove it, wherein the biological treatment means sequentially performs anaerobic treatment. An apparatus for treating selenium-containing wastewater, which has a plurality of biological treatment tanks for performing.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9004696A JPH09253686A (en) | 1996-03-19 | 1996-03-19 | Apparatus for treating waste water containing selenium |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9004696A JPH09253686A (en) | 1996-03-19 | 1996-03-19 | Apparatus for treating waste water containing selenium |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH09253686A true JPH09253686A (en) | 1997-09-30 |
Family
ID=13987695
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP9004696A Pending JPH09253686A (en) | 1996-03-19 | 1996-03-19 | Apparatus for treating waste water containing selenium |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH09253686A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012192359A (en) * | 2011-03-17 | 2012-10-11 | Central Research Institute Of Electric Power Industry | Selenium containing water reduction treatment apparatus and selenium containing water reduction treatment method |
| JP2015024360A (en) * | 2013-07-25 | 2015-02-05 | オルガノ株式会社 | Selenium-containing water treatment method and apparatus |
| JP2015039651A (en) * | 2013-08-20 | 2015-03-02 | 栗田工業株式会社 | Method and apparatus for treating selenium-containing water |
| JP2019122334A (en) * | 2018-01-18 | 2019-07-25 | 電源開発株式会社 | Selenate compound reduction method, selenate compound removal method, metal selenium production method, selenate compound reduction preparation, nitrate compound reduction method, nitrate compound removal method, nitrogen gas production method, nitrate compound reduction preparation, wastewater treatment apparatus and wastewater treatment method |
-
1996
- 1996-03-19 JP JP9004696A patent/JPH09253686A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012192359A (en) * | 2011-03-17 | 2012-10-11 | Central Research Institute Of Electric Power Industry | Selenium containing water reduction treatment apparatus and selenium containing water reduction treatment method |
| JP2015024360A (en) * | 2013-07-25 | 2015-02-05 | オルガノ株式会社 | Selenium-containing water treatment method and apparatus |
| JP2015039651A (en) * | 2013-08-20 | 2015-03-02 | 栗田工業株式会社 | Method and apparatus for treating selenium-containing water |
| JP2019122334A (en) * | 2018-01-18 | 2019-07-25 | 電源開発株式会社 | Selenate compound reduction method, selenate compound removal method, metal selenium production method, selenate compound reduction preparation, nitrate compound reduction method, nitrate compound removal method, nitrogen gas production method, nitrate compound reduction preparation, wastewater treatment apparatus and wastewater treatment method |
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