JPH04161292A - Method for purifying biologically treated waste water - Google Patents
Method for purifying biologically treated waste waterInfo
- Publication number
- JPH04161292A JPH04161292A JP2289409A JP28940990A JPH04161292A JP H04161292 A JPH04161292 A JP H04161292A JP 2289409 A JP2289409 A JP 2289409A JP 28940990 A JP28940990 A JP 28940990A JP H04161292 A JPH04161292 A JP H04161292A
- Authority
- JP
- Japan
- Prior art keywords
- waste liquid
- biological treatment
- waste water
- biologically treated
- cod
- 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
Links
- 238000000034 method Methods 0.000 title claims description 31
- 239000002351 wastewater Substances 0.000 title abstract description 11
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 26
- 229940043430 calcium compound Drugs 0.000 claims abstract description 17
- 150000001674 calcium compounds Chemical class 0.000 claims abstract description 17
- 239000007788 liquid Substances 0.000 claims description 50
- 239000002699 waste material Substances 0.000 claims description 42
- 239000000126 substance Substances 0.000 abstract description 9
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 abstract description 7
- 239000000292 calcium oxide Substances 0.000 abstract description 5
- 241000251468 Actinopterygii Species 0.000 abstract description 4
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 abstract description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 3
- 239000002846 particulate organic matter Substances 0.000 description 9
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 6
- 235000011116 calcium hydroxide Nutrition 0.000 description 6
- 238000000746 purification Methods 0.000 description 6
- 239000000920 calcium hydroxide Substances 0.000 description 5
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 4
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 4
- 235000012255 calcium oxide Nutrition 0.000 description 4
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 4
- 239000007787 solid Substances 0.000 description 4
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 239000008394 flocculating agent Substances 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- DIZPMCHEQGEION-UHFFFAOYSA-H aluminium sulfate (anhydrous) Chemical compound [Al+3].[Al+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O DIZPMCHEQGEION-UHFFFAOYSA-H 0.000 description 2
- VSCWAEJMTAWNJL-UHFFFAOYSA-K aluminium trichloride Chemical compound Cl[Al](Cl)Cl VSCWAEJMTAWNJL-UHFFFAOYSA-K 0.000 description 2
- 229910001424 calcium ion Inorganic materials 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- 238000005342 ion exchange Methods 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- IXPNQXFRVYWDDI-UHFFFAOYSA-N 1-methyl-2,4-dioxo-1,3-diazinane-5-carboximidamide Chemical compound CN1CC(C(N)=N)C(=O)NC1=O IXPNQXFRVYWDDI-UHFFFAOYSA-N 0.000 description 1
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 1
- 241000195493 Cryptophyta Species 0.000 description 1
- 241000196324 Embryophyta Species 0.000 description 1
- 241001465754 Metazoa Species 0.000 description 1
- 235000010627 Phaseolus vulgaris Nutrition 0.000 description 1
- 244000046052 Phaseolus vulgaris Species 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- 235000011941 Tilia x europaea Nutrition 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 230000001580 bacterial effect Effects 0.000 description 1
- 238000005119 centrifugation Methods 0.000 description 1
- 230000015271 coagulation Effects 0.000 description 1
- 238000005345 coagulation Methods 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 238000005189 flocculation Methods 0.000 description 1
- 230000016615 flocculation Effects 0.000 description 1
- 235000013305 food Nutrition 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 150000004677 hydrates Chemical class 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000010985 leather Substances 0.000 description 1
- 239000004571 lime Substances 0.000 description 1
- 244000144972 livestock Species 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 235000013372 meat Nutrition 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 235000012149 noodles Nutrition 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- -1 polypropylene Polymers 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 238000001223 reverse osmosis Methods 0.000 description 1
- 238000012216 screening Methods 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- 235000010413 sodium alginate Nutrition 0.000 description 1
- 229940005550 sodium alginate Drugs 0.000 description 1
- 239000000661 sodium alginate Substances 0.000 description 1
- 239000006228 supernatant Substances 0.000 description 1
Landscapes
- Separation Of Suspended Particles By Flocculating Agents (AREA)
Abstract
Description
【発明の詳細な説明】
発明の技術分野
本発明は、生物処理廃液の浄化方法に関し、さらに詳し
くは生物処理廃液の化学的酸素要求量（ＣＯＤ）などを
大幅に低減する方法に関する。DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a method for purifying biological treatment waste liquid, and more particularly to a method for significantly reducing the chemical oxygen demand (COD), etc. of biological treatment waste liquid.
発明の技術的背景
動植物を含む生物の処理過程で生じる廃液（以下、生物
処理廃液という）、たとえば魚加工廃液は、生物化学的
酸素要求量（ＢＯＤ）、化学的酸素要求量（ＣＯＤ）
、浮遊物質量（Ｓ Ｓ）などの値が異常に高く、浄化に
よりこれらの値を大幅に低減する必要がある。Technical Background of the Invention Waste liquids generated during the treatment of living things including animals and plants (hereinafter referred to as biological treatment waste liquids), such as fish processing waste liquids, have a biochemical oxygen demand (BOD) and a chemical oxygen demand (COD).
, the amount of suspended solids (SS), etc. are abnormally high, and it is necessary to significantly reduce these values through purification.
またこのようなりＯＤ、ＣＯＤおよびＳＳなどの値を低
減する方法としては、多層濾過法、マイクロスクリーニ
ング法、蒸留法、凍結法、逆浸透法などの物理的処理方
法、硫酸アルミニウム、アルギン酸ソーダ、ポリ塩化ア
ルミニウム（ＰＡＣ）などの凝集剤を用いて行なう凝集
処理法、活性炭吸着法、イオン交換法などの化学的処理
方法、バクテリア同化法、藻類採集法などの生物処理方
法が知られている。Methods for reducing OD, COD, and SS values include physical treatment methods such as multilayer filtration, micro-screening, distillation, freezing, and reverse osmosis, aluminum sulfate, sodium alginate, and polypropylene. Coagulation treatment methods using flocculants such as aluminum chloride (PAC), chemical treatment methods such as activated carbon adsorption methods and ion exchange methods, and biological treatment methods such as bacterial assimilation methods and algae collection methods are known.
しかしながら上述したような物理的処理方法は、高価な
設備が必要であり、生物処理方法は、ＢＯＤＸＣＯＤお
よびＳＳなどの値が低減されるまでに時間がかかるとい
う問題がある。However, the above-mentioned physical treatment methods require expensive equipment, and the biological treatment methods have a problem in that it takes time to reduce values such as BODXCOD and SS.
また化学的処理方法のうち、イオン交換法は、高価な設
備が必要であり、活性炭吸着法は、高価な活性炭が大量
に消費され、従来の凝集剤を用いて行なう凝集処理法は
、その処理効果が不充分であるなどの問題がある。In addition, among chemical treatment methods, the ion exchange method requires expensive equipment, the activated carbon adsorption method consumes a large amount of expensive activated carbon, and the conventional flocculation treatment method using a flocculant There are problems such as insufficient effectiveness.
従来、硫酸アルミニウムなどの無機凝集剤を用いて下水
などの凝集処理を行なう場合に、これらの無機凝集剤と
併せて消石灰が多量に用いられているが、この消石灰は
、これ等の無機凝集剤の性能を発揮させるためにスラリ
ーの液性をアルカリ性に保つためのもので、それ以外に
濾過助剤としての役目を果たす（「高分子凝集剤」株式
会社高分子刊行会発行、第７刷版、第９８頁参照）もの
の、消石灰自体を凝集剤として用いる試みはなされてい
ない。Conventionally, when inorganic flocculants such as aluminum sulfate are used to coagulate sewage, a large amount of slaked lime is used together with these inorganic flocculants; It is used to keep the slurry liquid alkaline in order to exhibit its performance, and also serves as a filter aid ("Polymer flocculant", published by Kobunshi Publishing Co., Ltd., 7th printing edition) , p. 98), but no attempt has been made to use slaked lime itself as a flocculant.
本発明者らは、上記のような問題を解決するために種々
の研究を行なった結果、酸化カルシウムおよびその水和
物などの塩基性カルシウム化合物を生物処理廃液に添加
し、次いで特定量の硫酸を添加した後に透明液を分離し
て回収すると、この回収された透明な上澄液は、浄化処
理以前の生物処理廃液に比較してＣＯＤなどの値が大幅
に低減することを見出し、本発明を完成するに至った。The present inventors conducted various studies to solve the above problems, and found that they added basic calcium compounds such as calcium oxide and its hydrate to biological treatment wastewater, and then added a specific amount of sulfuric acid. It has been found that when the transparent liquid is separated and collected after adding , the collected transparent supernatant liquid has significantly reduced values such as COD compared to the biological treatment waste liquid before purification treatment, and the present invention I was able to complete it.
発明の目的
したがって本発明は、高価な設備を必要とせす、安価な
薬品で、しかも短時間のうちに生物処理廃液のＣＯＤな
どの値を大幅に低減することかできるような生物処理廃
液の浄化方法を提供することを目的としている。Purpose of the Invention Accordingly, the present invention provides a purification method for biological treatment waste liquid that can significantly reduce the COD and other values of biological treatment waste liquid in a short period of time using inexpensive chemicals that do not require expensive equipment. The purpose is to provide a method.
発明の概要
本発明の生物処理廃液の浄化方法は、生物処理廃液中に
塩基性カルシウム化合物を添加し、次いでこの生物処理
廃液のｐＨが６．０〜８．０となるまで硫酸を添加する
ことを特徴としている。Summary of the Invention The method for purifying biological treatment waste liquid of the present invention includes adding a basic calcium compound to biological treatment waste liquid, and then adding sulfuric acid until the pH of this biological treatment waste liquid becomes 6.0 to 8.0. It is characterized by
発明の詳細な説明
以下、本発明に係る生物処理廃液の浄化方法について具
体的に説明する。Detailed Description of the Invention The method for purifying biological treatment waste liquid according to the present invention will be specifically described below.
本発明方法の浄化対象は、既に説明したように、ＣＯＤ
などが異常に高い値を示す生物処理廃液である。たとえ
ば２００ｐｐｍ以上のＣＯＤを有する生物処理廃液か、
本発明方法の浄化対象である。As already explained, the object of purification in the method of the present invention is COD
This is biological treatment wastewater that shows abnormally high values. For example, biological treatment wastewater with COD of 200 ppm or more,
This is the object of purification in the method of the present invention.
このような生物処理廃液として、具体的には、魚加工廃
液、製麺、製ハム、製あんおよび食肉加工などの食品加
工の際に生しる廃液、なめし皮製造工程で生しる廃液、
畜産加工廃液などが挙げられる。Specifically, such biological processing waste liquid includes fish processing waste liquid, waste liquid produced during food processing such as noodle making, ham making, bean paste making, and meat processing, waste liquid produced in the tanning leather manufacturing process,
Examples include livestock processing waste liquid.
本発明に係る生物処理廃液の浄化方法においては、塩基
性カルシウム化合物が用いられる。In the method for purifying biological treatment waste liquid according to the present invention, a basic calcium compound is used.
ここで塩基性カルシウム化合物とは、水溶性であって水
に溶解した際に塩基性の水溶液を形成するカルシウム化
合物を意味する。このような塩基性カルシウム化合物と
して、具体的には酸化カルシウムおよびその水和物など
が挙げられ、特に生石灰および消石灰が、入手がし易く
安価であるなどの点において好ましい。Here, the basic calcium compound means a calcium compound that is water-soluble and forms a basic aqueous solution when dissolved in water. Specific examples of such basic calcium compounds include calcium oxide and hydrates thereof, and quicklime and slaked lime are particularly preferred because they are easily available and inexpensive.
このような塩基性カルシウム化合物の添加量は、浄化対
象となっている生物処理廃液の種類、性質などに応じて
異なるが、生物処理廃液の０．１〜１．０重量％とする
ことが好ましい。The amount of such a basic calcium compound added varies depending on the type and properties of the biological treatment waste liquid to be purified, but it is preferably 0.1 to 1.0% by weight of the biological treatment waste liquid. .
またこのような塩基性カルシウム化合物は、粉末状で添
加することもできるし、あるいは石灰乳のごときスラリ
ー状またはペースト状で添加することもできる。Further, such a basic calcium compound can be added in the form of a powder, or in the form of a slurry or paste such as milk of lime.
本発明においては、上述したような塩基性カルシウム化
合物を生物処理廃液中に添加した後、この生物処理廃液
のｐＨが６．０〜８．０となるまて硫酸が添加される。In the present invention, after the basic calcium compound as described above is added to the biological treatment waste liquid, sulfuric acid is added until the pH of the biological treatment waste liquid reaches 6.0 to 8.0.
そしてこの硫酸を添加した後の生物処理廃液から、たと
えば遠心分離機などでＣＯＤなどの値が大幅に低減して
いる透明液を分離して回収することができる。Then, from the biological treatment waste liquid to which sulfuric acid has been added, a clear liquid with significantly reduced COD values can be separated and recovered using a centrifuge, for example.
発明の効果
上述したような本発明に係る生物処理廃液の浄化方法に
よれば、生物処理廃液中に、塩基性カルシウム化合物を
添加した後、硫酸を添加して、この生物処理廃液のｐＨ
が６．０〜８．０となれば直ちに透明液を分離して回収
することができる。Effects of the Invention According to the method for purifying biological treatment waste liquid according to the present invention as described above, after adding a basic calcium compound to the biological treatment waste liquid, sulfuric acid is added to adjust the pH of the biological treatment waste liquid.
When the value becomes 6.0 to 8.0, the transparent liquid can be immediately separated and collected.
この透明液は、浄化処理以前の生物処理廃液に比較して
、ＣＯＤなどの値が大幅に低減している。This transparent liquid has significantly reduced values such as COD compared to the biologically treated waste liquid before purification treatment.
したがって本発明方法によれば、上述したように塩基性
カルシウム化合物を添加した後、所定量の硫酸を添加す
れば直ちに透明液を分離して回収することができるので
、生物処理廃液の浄化が短時間のうちに行なえる。しか
も上述したような簡単な操作で生物処理廃液の浄化が行
なえるので高価な設備を用いる必要はない。Therefore, according to the method of the present invention, the clear liquid can be immediately separated and recovered by adding a predetermined amount of sulfuric acid after adding the basic calcium compound as described above, so that the biological treatment waste liquid can be purified in a short time. It can be done in time. Moreover, since the biological treatment waste liquid can be purified by the simple operation described above, there is no need to use expensive equipment.
また本発明方法で用いられるたとえば消石灰、生石灰な
どの塩基性カルシウム化合物、および硫酸は安価な薬品
である。Furthermore, basic calcium compounds such as slaked lime and quicklime, and sulfuric acid used in the method of the present invention are inexpensive chemicals.
以上の説明から明らかなように本発明方法によれば、高
価な設備を必要とせず、安価な薬品で、しかも短時間の
うちに生物処理廃液のＣＯＤなどの値を大幅に低減する
ことができる。As is clear from the above explanation, according to the method of the present invention, the COD and other values of biological treatment waste liquid can be significantly reduced in a short time without the need for expensive equipment and with inexpensive chemicals. .
本発明方法によって生物処理廃液のＣＯＤなとの値を大
幅に低減することができる理由は明らかではないが、以
下のように推定される。The reason why the method of the present invention can significantly reduce the COD value of biological treatment waste liquid is not clear, but it is presumed as follows.
生物処理廃液中に塩基性カルシウム化合物を添加するこ
とにより、塩基性カルシウム化合物が生物処理廃液中に
溶解してカルシウムイオンを生成し、このカルシウムイ
オンが、生物処理廃液上に浮遊している微粒状の有機物
および生物処理廃液中に懸濁している微粒状の有機物に
付着する。By adding a basic calcium compound to the biological treatment waste liquid, the basic calcium compound dissolves in the biological treatment waste liquid and generates calcium ions, and this calcium ion forms fine particles floating on the biological treatment waste liquid. and fine particulate organic matter suspended in biological treatment wastewater.
次いでこの生物処理廃液のｐＨが６．０〜８．０となる
まで硫酸を添加することにより、微粒状の有機物に付着
しているカルシウムイオンが、微粒状の有機物に付着し
たままの状態で硫酸イオンと反応して硫酸カルシウムを
生成する。この微粒状の有機物に付着している硫酸カル
シウムは、比重が大きく、微粒状の有機物の見かけ比重
を大きくし、微粒状の有機物を沈降させる。Next, by adding sulfuric acid until the pH of this biological treatment waste liquid becomes 6.0 to 8.0, the calcium ions attached to the fine particulate organic matter are removed by sulfuric acid while remaining attached to the fine particulate organic matter. Reacts with ions to produce calcium sulfate. Calcium sulfate adhering to this fine particulate organic matter has a high specific gravity, increases the apparent specific gravity of the fine particulate organic matter, and causes the fine particulate organic matter to settle.
ところで生物処理廃液上に浮遊している微粒状の有機物
および生物処理廃液中に懸濁している微粒状の有機物が
、生物処理廃液のＣＯＤなどの値を異常に高くしている
原因と考えられる。このためこのような微粒状の有機物
が沈降して除去された透明液は、ＣＯＤなどの値が大幅
に低減する。Incidentally, it is thought that the fine particulate organic matter floating on the biological treatment waste liquid and the fine particulate organic matter suspended in the biological treatment waste liquid are the cause of abnormally high COD values of the biological treatment waste liquid. Therefore, the value of COD etc. of the transparent liquid from which such fine particulate organic matter is precipitated and removed is significantly reduced.
実施例
以下に実施例を示し、本発明をさらに具体的に説明する
。EXAMPLES The present invention will be explained in more detail with reference to Examples below.
魚加工物廃液１１ （ＣＯＤ ３８００ｐｐｍ）に
石灰粉末５ｇを添加し、次いて均一に混合した後、ｐＨ
が６．５となるまで１０％希硫酸を６５ｍ１添加した後
、遠心分離（毎分３０００回転）を３０分間行なったと
ころ、得られた透明水のＣＯＤは５８ｐｐｍであった。Add 5g of lime powder to fish processed waste liquid 11 (COD 3800ppm), then mix uniformly, then adjust the pH.
After adding 65 ml of 10% dilute sulfuric acid until the pH value reached 6.5, centrifugation (3000 revolutions per minute) was performed for 30 minutes, and the COD of the resulting transparent water was 58 ppm.
Claims (1)
し、次いでこの生物処理廃液のｐＨが６．０〜８．０と
なるまで硫酸を添加することを特徴とする生物処理廃液
の浄化方法。(1) A method for purifying a biological treatment waste liquid, which comprises adding a basic calcium compound to the biological treatment waste liquid, and then adding sulfuric acid until the pH of the biological treatment waste liquid becomes 6.0 to 8.0.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2289409A JPH04161292A (en) | 1990-10-26 | 1990-10-26 | Method for purifying biologically treated waste water |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2289409A JPH04161292A (en) | 1990-10-26 | 1990-10-26 | Method for purifying biologically treated waste water |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH04161292A true JPH04161292A (en) | 1992-06-04 |
Family
ID=17742868
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2289409A Pending JPH04161292A (en) | 1990-10-26 | 1990-10-26 | Method for purifying biologically treated waste water |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH04161292A (en) |
-
1990
- 1990-10-26 JP JP2289409A patent/JPH04161292A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5543056A (en) | Method of drinking water treatment with natural cationic polymers | |
| CN106082502B (en) | A kind of method for removing thallium in waste water | |
| CN114249405A (en) | Efficient defluorinating agent and preparation method and use method thereof | |
| JPH05161803A (en) | Waste water purifying treatment agent and production thereof | |
| JP2003093804A (en) | Purification agent for turbid wastewater and sludge | |
| JP4688126B2 (en) | Organic waste liquid treatment method in food processing factory | |
| JP2000246013A (en) | Flocculating sedimentation agent and flocculation treatment method | |
| CN110342710A (en) | High chlorine low-sulfur acid group waste water treatment system and its technique | |
| JP2002205077A (en) | Method and apparatus for treating organic sewage | |
| JP2007209886A (en) | Fluorine removing agent, and method and apparatus for treating drain containing fluorine using the agent | |
| JPH0366036B2 (en) | ||
| JP2009050752A (en) | Flocculant | |
| JPH04161292A (en) | Method for purifying biologically treated waste water | |
| EP3818013A1 (en) | Anolyte as an additive for wastewater treatment | |
| JP4145406B2 (en) | Method for preventing phosphorus from being eluted in sludge and phosphorus elution preventing agent for sludge | |
| WO1994002418A1 (en) | A method of and an apparatus for purifying aqueous suspensions containing organic material and cations | |
| RU2725315C1 (en) | Method of purifying water from arsenic compounds | |
| JP4259700B2 (en) | Sludge aggregation method and water treatment method | |
| JP2007216201A (en) | Natural flocculation precipitant for water purification | |
| JPH0553521B2 (en) | ||
| RU2006484C1 (en) | Method of purifying sewage against chromium | |
| JPH0433518B2 (en) | ||
| JPH0783875B2 (en) | Wastewater treatment method by activated sludge method | |
| RU2122524C1 (en) | Water treatment process | |
| JP3272216B2 (en) | Treatment of chromium-containing wastewater |