JPS5854634B2 - Treatment method for wastewater containing heavy metals - Google Patents
Treatment method for wastewater containing heavy metalsInfo
- Publication number
- JPS5854634B2 JPS5854634B2 JP51068779A JP6877976A JPS5854634B2 JP S5854634 B2 JPS5854634 B2 JP S5854634B2 JP 51068779 A JP51068779 A JP 51068779A JP 6877976 A JP6877976 A JP 6877976A JP S5854634 B2 JPS5854634 B2 JP S5854634B2
- Authority
- JP
- Japan
- Prior art keywords
- wastewater
- sulfate
- heavy metals
- added
- heavy metal
- 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.)
- Expired
Links
Landscapes
- Processing Of Solid Wastes (AREA)
- Removal Of Specific Substances (AREA)
- Treatment Of Sludge (AREA)
Description
【発明の詳細な説明】
本発明は重金属含有廃水の処理方法に関し、詳しくは、
重金属イオンを溶存している廃水に硫酸塩、消石灰を添
加してスラッジを生成せしめ、これを乾燥後水を加えて
生成固形物の固化を図るようにした重金属含有廃水の処
理方法に関する。[Detailed Description of the Invention] The present invention relates to a method for treating wastewater containing heavy metals.
This invention relates to a method for treating wastewater containing heavy metals, in which sulfate and slaked lime are added to wastewater containing dissolved heavy metal ions to produce sludge, and after drying, water is added to solidify the produced solids.
従来より、亜鉛、クロム、銅、カドミウムその他の重金
属イオンを含有している廃水の処理方法としては、種々
の手段が提案され実用に供されている。Conventionally, various means have been proposed and put into practical use as methods for treating wastewater containing heavy metal ions such as zinc, chromium, copper, cadmium, and others.
なかでも凝集剤の添加による廃水処理は広く採用される
ようになっている。Among these, wastewater treatment by adding coagulants has become widely adopted.
また、最近になって、廃水中の重金属イオンをフェリツ
ク化させて不溶化せしめ除去する廃水処理方法が提案さ
れている。Furthermore, recently, a wastewater treatment method has been proposed in which heavy metal ions in wastewater are made into ferrites, insolubilized, and removed.
この方法は、重金属含有廃水に第」鉄塩を加え、さらに
苛性ソーダを加えて中性付近に調整すると沈降性の悪い
沈澱(水酸化第1鉄)が生成し、重金属イオンはこの水
酸化鉄によって共沈され、これに空気などを吹き込むと
水酸化第1鉄は酸化され水酸化第2鉄となって放置して
おくと沈降するので、分離後の上澄液には重金属類が一
切含まれないというものである。In this method, ferrous salt is added to heavy metal-containing wastewater, and then caustic soda is added to adjust it to near neutrality. A precipitate with poor settling properties (ferrous hydroxide) is produced, and heavy metal ions are removed by this iron hydroxide. When the ferrous hydroxide is co-precipitated and air is blown into it, the ferrous hydroxide is oxidized and becomes ferric hydroxide, which will settle if left to stand, so the supernatant liquid after separation will contain no heavy metals. There is no such thing.
しかし乍ら、これらの廃水処理方法は、いずれも処理水
の水質にのみ重点がおかれ、重金属類を含んだ生成スラ
ッジの取扱いについてはあまり注意がはられれていなか
ったのであるが、近時はこれら有害物質を多量に含有し
た生成スラッジの処理が問題となってきた。However, in all of these wastewater treatment methods, emphasis was placed only on the quality of the treated water, and little attention was paid to the handling of the produced sludge containing heavy metals. The treatment of generated sludge containing large amounts of these harmful substances has become a problem.
すなわち、こうしたスラッジが野積されたり、土中に埋
められたりしている場合には、風雨による飛散、流出な
どによる環境再汚染が生じる可能性が充分に考えられる
からである。In other words, if such sludge is piled up in the open or buried in the ground, there is a strong possibility that environmental re-contamination will occur due to scattering or runoff due to wind and rain.
従って、現在では前記の従来の廃水処理方法によった場
合には、生成スラッジに固化剤を添加して固化せしめ環
境再汚染を防いでいるのが実情である。Therefore, at present, when using the conventional wastewater treatment method described above, a solidifying agent is added to the generated sludge to solidify it to prevent environmental recontamination.
しかし、こうした固化剤を利用した固化処理にあっては
、(1)処理物の体積が増大する、(2)充分な強度を
得るには数日間を要する。However, in solidification treatment using such a solidification agent, (1) the volume of the treated product increases, and (2) it takes several days to obtain sufficient strength.
(3)フェリツク化法では中和剤に苛性ソーダが使用さ
れるため廃水処理コストが高くなる、などの欠点がある
。(3) The ferriticization method uses caustic soda as a neutralizing agent, which has drawbacks such as increased wastewater treatment costs.
また、フェリツク化法では、生成するす)−IJウム塩
が水溶性であるため処理水に多量の塩類が流出する、と
いった欠点もある。In addition, the ferriticization method has the disadvantage that a large amount of salts flows out into the treated water because the S)-IJium salts produced are water-soluble.
本発明の目的は、廃水中に含有されている重金属イオン
を除去し清浄な処理水が得られると同時に、有害物質含
有スラッジを取扱いの容易な自硬性の固形物に変え安全
に処分できるようにした、重金属含有廃水の処理方法を
提供することにある。The purpose of the present invention is to remove heavy metal ions contained in wastewater to obtain clean treated water, and at the same time, to convert sludge containing harmful substances into self-hardening solids that are easy to handle and safely dispose of. An object of the present invention is to provide a method for treating wastewater containing heavy metals.
すなわち本発明は、重金属含有廃水に硫酸塩を硫酸根と
して0.02 mol/j?以上添加し、さらに消石灰
を添加して中和反応を行なわしめて、前記廃水中の重金
属イオンを水酸化物の共沈生成物として沈澱させた後、
この得られたスラッジを110〜163℃で乾燥し、次
いでこれに水を加え混練し生成固形物の固化を促進せし
めることを特徴とする重金属含有廃水の処理方法である
。That is, in the present invention, 0.02 mol/j? of sulfate is added to heavy metal-containing wastewater as a sulfate group. After adding the above and further adding slaked lime to carry out a neutralization reaction to precipitate the heavy metal ions in the wastewater as a co-precipitation product of hydroxide,
This method for treating wastewater containing heavy metals is characterized in that the obtained sludge is dried at 110 to 163° C., and then water is added thereto and kneaded to promote solidification of the produced solids.
本発明方法において処理対象となる重金属含有廃水とし
ては、各種工場からの廃水を始めとして、学校、公共施
設からの廃水などがあげられ、またこれに含有される重
金属イオンとしては、亜鉛、クロム、銅、カドミウム、
水銀、錫、鉛、砒素、コバルトなどのイオンがあげられ
る。Heavy metal-containing wastewater to be treated in the method of the present invention includes wastewater from various factories, schools, and public facilities, and the heavy metal ions contained in this include zinc, chromium, copper, cadmium,
Examples include ions such as mercury, tin, lead, arsenic, and cobalt.
なお廃水中に含有される重金属イオンは1種に限られる
ものではなく、2種以上であってもよく、またそれらが
錯体の格好で存在されていてもよい。Note that the number of heavy metal ions contained in the wastewater is not limited to one type, but may be two or more types, or they may be present in the form of a complex.
また、重金属イオンの含有量は特に問題とはならない。Moreover, the content of heavy metal ions does not pose a particular problem.
本発明では、こうした重金属含有廃水に硫酸塩が添加さ
れた後、消石灰を添加して中和反応させることによって
、有害物質(重金属類、その他懸濁物質など)を含有し
た固形物と石膏(CaSO4・2H20)との混合物が
得られる。In the present invention, after sulfate is added to such heavy metal-containing wastewater, slaked lime is added to cause a neutralization reaction, and solids containing harmful substances (heavy metals, other suspended substances, etc.) are combined with gypsum (CaSO4).・2H20) is obtained.
ここで生成した石膏は水に対する溶解度が小さいためほ
とんど沈澱する。Since the gypsum produced here has low solubility in water, most of it precipitates.
すなわち凝集沈澱法にあっては、凝集剤として硫酸塩(
例えば硫酸アルミニウム、硫酸第1鉄、硫酸亜鉛など)
が硫酸根として0.02mo I /1以上になるよう
に添加されると、廃水中の重金属類はイオンを失ない凝
集するようになり、また凝集剤の一部がアルミニウム、
鉄、亜鉛などの水酸化物(ゲル状の沈澱固形物)を形成
しこれが前記の凝集物(濁質物質)を包含するようにな
る。In other words, in the coagulation-sedimentation method, sulfate (
(e.g. aluminum sulfate, ferrous sulfate, zinc sulfate, etc.)
When is added as a sulfate group at a concentration of 0.02 mo I /1 or more, heavy metals in wastewater will coagulate without losing ions, and some of the flocculants will be aluminum,
Hydroxides (gel-like precipitated solids) of iron, zinc, etc. are formed, and these come to contain the above-mentioned aggregates (turbid substances).
次いで、消石灰が硫酸塩溶液が中和されるように、すな
わち残余の硫酸根と等量の水酸基が含まれるように消石
灰が添加されると、残余の硫酸塩と消石灰とが反応し2
水石膏が生成される。Then, when slaked lime is added in such a way that the sulfate solution is neutralized, i.e. contains an equal amount of hydroxyl groups to the remaining sulfate groups, the remaining sulfates and slaked lime react with each other.
Hydrogypsum is produced.
方、フェリツタ化法にあっては、硫酸第1鉄が硫酸根と
して0.02mol/1以上になるように添加され、こ
れに空気の吹き込みが行なわれると水酸化第1鉄は酸化
されて水酸化第2塩になり、廃水中の重金属イオンは水
酸化第2鉄によって一層速く共沈する。On the other hand, in the ferritization method, ferrous sulfate is added as a sulfate radical at a concentration of 0.02 mol/1 or more, and when air is blown into this, the ferrous hydroxide is oxidized and becomes water. It becomes a ferric oxide salt, and the heavy metal ions in the wastewater are co-precipitated more quickly by the ferric hydroxide.
次いで消石灰が加えられると重金属イオンはフェリツク
化して不溶化すると同時に、残余の硫酸塩と消石灰とが
反応して2水石膏が生成される。When slaked lime is then added, the heavy metal ions become ferritic and insolubilized, and at the same time, the remaining sulfate and slaked lime react to produce dihydrate gypsum.
なお、凝集沈澱法においてはpHは凝集の良否に重要な
因子となるものであり、またフェリツク化法においても
重要であり、pH6〜8の範囲、好ましくは中性付近で
操作が行なわれるのが望ましい。In addition, pH is an important factor in determining the quality of flocculation in the coagulation-sedimentation method, and is also important in the ferriticization method, and the operation is preferably carried out in the pH range of 6 to 8, preferably near neutrality. desirable.
凝集剤(フェリツク化法では硫酸第1鉄)の添加量は、
硫酸根として0.02 mo f、41?以上となるよ
うな量であり、これより少ないと充分な強度をもった固
化体をつくる固形物を得ることができない。The amount of flocculant (ferrous sulfate in the ferriticization method) added is as follows:
0.02 mo f as sulfate root, 41? If the amount is less than this, it will not be possible to obtain a solid material with sufficient strength.
以上のような一連の反応が完結したところで、有害物質
を含有したスラッジを沈澱物として分離する。When the series of reactions described above is completed, the sludge containing harmful substances is separated as a precipitate.
分離後の上澄液には重金属類などがまったく含まれてい
ない。The supernatant liquid after separation does not contain any heavy metals.
次いで分離されたスラッジは脱水後、110〜163℃
で乾燥されることによって、スラッジ中の石膏(CaS
04・2H20)は焼石膏(Ca S 04 ・% H
20)とされ、自硬性、速硬性をもった固形物となる。The separated sludge is then dehydrated and heated to 110-163°C.
Gypsum (CaS) in the sludge is dried by
04・2H20) is calcined gypsum (Ca S 04 ・% H
20), and it becomes a solid material with self-hardening and quick-hardening properties.
110℃未満又は163℃を越えた温度で乾燥されると
所期の目的を達成する固形物を得ることができない。When dried at temperatures below 110°C or above 163°C, it is not possible to obtain a solid that achieves the intended purpose.
次いで、これに水を加えて混練すると数分のうちに強固
な固化体となる。Next, when water is added to this and kneaded, it becomes a strong solidified body within a few minutes.
図面は、本発明方法の実施の一例をフローシートで表わ
したもので、1は中和反応装置、2は固液分離装置、3
は乾燥装置、4は混練装置を示している。The drawing shows an example of the implementation of the method of the present invention in the form of a flow sheet, in which 1 is a neutralization reactor, 2 is a solid-liquid separator, and 3 is a flow sheet.
4 indicates a drying device, and 4 indicates a kneading device.
重金属イオン含有廃水は中和反応装置1に導入され、そ
こに硫酸塩(フェリツク化法では硫酸第1鉄)と消石灰
とが添加される。Heavy metal ion-containing wastewater is introduced into the neutralization reactor 1, and sulfate (ferrous sulfate in the ferritization method) and slaked lime are added thereto.
硫酸塩と消石灰の添加順序は、硫酸塩が先行して行なわ
れる必要がある。The order of addition of sulfate and slaked lime requires that sulfate be added first.
中和反応装置1内では、硫酸化鉄が使用された場合を例
にすると、下記の反応がおこり、2水石膏と水酸化第1
鉄
FeSO4+Ca(OH)2→Fe(OH)2+CaS
O4・2I−(20とが生成され、石膏に沈降性の悪い
水酸化第1鉄が包含されるような格好で、これらは沈澱
する。In the neutralization reactor 1, taking the case where iron sulfate is used as an example, the following reaction occurs, and dihydrate gypsum and hydroxide
Iron FeSO4+Ca(OH)2→Fe(OH)2+CaS
O4.2I-(20) are formed and these precipitate out in such a way that the gypsum contains ferrous hydroxide, which has poor settling properties.
また重金属イオンはイオンを失ない凝集しこれも石膏に
包含されるようになる。In addition, heavy metal ions aggregate without losing ions and are also included in gypsum.
フェリツク化法では、空気が導入されてFe(OH)2
はF e (OH) sとされ沈降性が改善される。In the ferritization method, air is introduced to form Fe(OH)2
is converted into F e (OH) s, and the sedimentation property is improved.
なお上記反応は中性付近で行なわれる。Note that the above reaction is carried out near neutrality.
次いで、これらは固液分離装置2に移され、上澄液は処
理水として放出される。These are then transferred to the solid-liquid separator 2, and the supernatant liquid is discharged as treated water.
脱水後、有害物質を含有したスラッジは乾燥装置3に移
され乾燥され、2水石膏は半水石膏(CaSO4・3A
H20)とされる。After dehydration, the sludge containing harmful substances is transferred to the drying device 3 and dried, and the dihydrate gypsum is converted into hemihydrate gypsum (CaSO4.3A
H20).
次いでこの自硬性、速硬性の固形物は混練装置4で水に
より混練され、固化体として取出される。Next, this self-hardening, fast-hardening solid material is kneaded with water in a kneading device 4, and taken out as a solidified material.
上記の例は回分式操業に適するものであるが、凝集剤の
添加と、中和反応とを別個の槽にして、連続的操業にし
て行なってもよい。Although the above example is suitable for batch operation, the addition of the flocculant and the neutralization reaction may be carried out in separate tanks for continuous operation.
このようにして取出された固化体は、前記固形物に水を
加えて数分間程度で硬化して得られるため、従来のよう
な長時間の養生期間を必要としない。The solidified material extracted in this way is obtained by adding water to the solid material and hardening in about a few minutes, so it does not require a long curing period as in the conventional method.
また有害物質の再溶出、風雨による飛散、流出などによ
る環境再汚染の危険性もない。Furthermore, there is no risk of re-contamination of the environment due to re-elution of harmful substances, scattering by wind and rain, or spillage.
特に本発明方法をフェリツク化法による重金属イオンを
含有した廃水の処理に適用すれば、処理水に多量の塩類
が流出するのを防ぐことができるのは勿論回収物の再利
用をはからず投棄処分する場合には苛性ソーダによる中
和に比べてコスト安である。In particular, if the method of the present invention is applied to the treatment of wastewater containing heavy metal ions using the ferriticization method, it is possible not only to prevent large amounts of salts from flowing into the treated water, but also to dump the recovered material without reusing it. When disposing of it, the cost is lower than neutralization with caustic soda.
督固化物は建材などへの有効利用も可能である。The hardened material can also be effectively used as building materials.
次に実施例を示す。Next, examples will be shown.
実施例 l
Zn2+、 Cr” 、 Cu2+、 Cd2+、 H
g”+を各々20.0pl)fit含む廃水に硫酸第1
鉄を加え、消石灰で中和し、空気酸化して得られたスラ
ッジを脱水後150℃で乾燥して得られた固形物につい
て、環境庁告示22号の再溶出試験方法で再溶出試験(
pH調整水(PH6,0) 20 omlに上記スラッ
ジ209を加え6時間振盪後、濾紙5種Cで濾過)を行
なった。Example l Zn2+, Cr", Cu2+, Cd2+, H
Add sulfuric acid to the wastewater containing 20.0 pl of each
The sludge obtained by adding iron, neutralizing with slaked lime, and air oxidation was dehydrated and dried at 150°C. The solid material obtained was subjected to a re-elution test (
The above sludge 209 was added to 20 oml of pH-adjusted water (PH6, 0), shaken for 6 hours, and then filtered using filter paper 5C.
結果は表−1のとおりで、極めて安定であった。The results are shown in Table 1, and it was extremely stable.
実施例 2
実施例1で用いたと同じ廃水に硫酸第1鉄を加え、消石
灰で中和して得られたスラッジを脱水後150℃で乾燥
し、次いでこれに水を加えて混練して得られた同化体の
30分後の圧壊強度を測定した結果は表−2のとおりで
あった。Example 2 The sludge obtained by adding ferrous sulfate to the same wastewater used in Example 1 and neutralizing it with slaked lime was dried at 150°C after dehydration, and then water was added and kneaded to obtain a sludge. The results of measuring the crushing strength of the assimilated product after 30 minutes are shown in Table 2.
表−2から判るように、硫酸根が0.02 mo 17
73以上であれば、投棄処分するのに適する強度が短時
間で得られるため硬化までの養生期間がほとんど不要で
ある。As can be seen from Table 2, the sulfate group is 0.02 mo 17
If it is 73 or higher, a strength suitable for disposal can be obtained in a short period of time, so there is almost no need for a curing period until hardening.
図面は本発明方法の実施の一例を示すフローシートであ
る。
1・・・・・・中和反応装置、2・・・・・・固液分離
装置、3・・・・・・乾燥装置、4・・・・・・混練装
置。The drawing is a flow sheet showing an example of implementing the method of the present invention. 1... Neutralization reaction device, 2... Solid-liquid separation device, 3... Drying device, 4... Kneading device.
Claims (1)
ol/J以上添加し、さらに消石灰を添加して中和反応
を行なわしめて、前記廃水中の重金属イオンを水酸化物
の共沈生成物として沈澱させた後、この得られたスラッ
ジを110〜163℃で乾燥し、次いでこれに水を加え
混練し生成固形物の固化を促進せしめることを特徴とす
る重金属含有廃水の処理方法。1 0.02m of sulfate as a sulfate group in wastewater containing heavy metals
ol/J or more and further add slaked lime to perform a neutralization reaction to precipitate the heavy metal ions in the wastewater as a coprecipitated product of hydroxide. 1. A method for treating wastewater containing heavy metals, which comprises drying the wastewater at a temperature of 0.degree.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP51068779A JPS5854634B2 (en) | 1976-06-14 | 1976-06-14 | Treatment method for wastewater containing heavy metals |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP51068779A JPS5854634B2 (en) | 1976-06-14 | 1976-06-14 | Treatment method for wastewater containing heavy metals |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS52152655A JPS52152655A (en) | 1977-12-19 |
JPS5854634B2 true JPS5854634B2 (en) | 1983-12-06 |
Family
ID=13383551
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP51068779A Expired JPS5854634B2 (en) | 1976-06-14 | 1976-06-14 | Treatment method for wastewater containing heavy metals |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS5854634B2 (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS54147172A (en) * | 1978-05-11 | 1979-11-17 | Nippon Sheet Glass Co Ltd | Treatment of waste containing lead |
EP0743280A1 (en) * | 1995-05-16 | 1996-11-20 | The Procter & Gamble Company | Process for the manufacture of hypochlorite bleaching compositions |
-
1976
- 1976-06-14 JP JP51068779A patent/JPS5854634B2/en not_active Expired
Also Published As
Publication number | Publication date |
---|---|
JPS52152655A (en) | 1977-12-19 |
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