JPH08224587A - Treatment of waste water containing phosphate - Google Patents
Treatment of waste water containing phosphateInfo
- Publication number
- JPH08224587A JPH08224587A JP5797995A JP5797995A JPH08224587A JP H08224587 A JPH08224587 A JP H08224587A JP 5797995 A JP5797995 A JP 5797995A JP 5797995 A JP5797995 A JP 5797995A JP H08224587 A JPH08224587 A JP H08224587A
- Authority
- JP
- Japan
- Prior art keywords
- tank
- sludge
- phosphate
- calcium
- water
- 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.)
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- Removal Of Specific Substances (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、リン酸塩含有廃水の処
理方法に関する。さらに詳しくは、本発明は、リン酸塩
を難溶性のカルシウム塩として固液分離するリン酸塩含
有廃水の処理方法において、中性に近いpHでの処理が可
能であり、汚泥濃度が高く汚泥発生量が減少し、汚泥の
脱水性が良好で脱水ケーキの発生量を低減することがで
きるリン酸塩含有廃水の処理方法に関する。FIELD OF THE INVENTION The present invention relates to a method for treating phosphate-containing wastewater. More specifically, the present invention is a method for treating phosphate-containing wastewater in which a phosphate is solid-liquid separated as a sparingly soluble calcium salt, which can be treated at a pH close to neutral, and has a high sludge concentration. The present invention relates to a method for treating phosphate-containing wastewater, which has a reduced generation amount, good sludge dewaterability, and can reduce the generation amount of dehydrated cake.
【０００２】[0002]
【従来の技術】リン酸塩含有廃水は、一般に生物学的方
法あるいは難溶性の塩を形成する方法によって処理され
る。難溶性の塩としては、鉄塩、アルミニウム塩及びカ
ルシウム塩が一般的であるが、これらの塩の形成により
得られる沈殿汚泥はいずれもゲル状であり、濃縮しにく
く汚泥濃度が薄く、その結果、汚泥の脱水性が悪いとい
う問題がある。リン酸塩含有廃水より、難溶性のリン酸
第二鉄又はリン酸アルミニウムを形成させる反応は、pH
６〜７の中性ないし弱酸性で行うことができる。しか
し、鉄化合物及びアルミニウム化合物はカルシウム化合
物に比べて高価なため、カルシウム塩の形成による処理
が広く行われている。リン酸塩含有廃水に塩化カルシウ
ムや消石灰のようなカルシウム化合物を添加すると、リ
ン酸とカルシウムは塩を形成してＣａ5(ＰＯ4)3ＯＨの
形で沈殿するが、この反応ではpH１０以上のアルカリ性
にしなければリン酸塩を効率的に除去することができ
ず、処理水を再中和しなければならないという欠点があ
る。リン酸塩含有廃水にカルシウム化合物として塩化カ
ルシウムを添加する場合は、通常水酸化ナトリウムを添
加することによってpHの調整が行われる。カルシウム化
合物として消石灰を添加する場合は、系のpHを測定する
ことによってその添加量を制御する。しかし、原水が中
性ないしアルカリ性であると、下記の反応により生成す
る水酸化ナトリウムにより、反応当量の消石灰が添加さ
れる前に制御値であるpH１０〜１２になり、リン酸塩の
処理が不十分になる場合がある。 ３ＮａＨ2ＰＯ4＋５Ｃａ(ＯＨ)2→Ｃａ5(ＰＯ4)3ＯＨ＋
６Ｈ2Ｏ＋３ＮａＯＨ ３Ｎａ2ＨＰＯ4＋５Ｃａ(ＯＨ)2→Ｃａ5(ＰＯ4)3ＯＨ＋
３Ｈ2Ｏ＋６ＮａＯＨ ３Ｎａ3ＰＯ4＋５Ｃａ(ＯＨ)2→Ｃａ5(ＰＯ4)3ＯＨ＋９
ＮａＯＨ このような場合は原水に硫酸のような酸を添加し、例え
ば、リン酸一水素ナトリウムの形で含まれる場合は下式
の反応によりリン酸の形にして処理する事が望ましい。 Ｎａ2ＨＰＯ4＋Ｈ2ＳＯ4→Ｈ3ＰＯ4＋Ｎａ2ＳＯ4 ３Ｈ3ＰＯ4＋５Ｃａ(ＯＨ)2→Ｃａ5(ＰＯ4)3ＯＨ＋９Ｈ
2Ｏ この場合も、リン酸カルシウムを効果的に沈殿させるた
めには、pH１０〜１２にする必要がある。このため、よ
り低い、中性に近いpHで処理することができ、しかも濃
度が高く、脱水性の良好な汚泥を得ることができるリン
酸塩含有廃水の処理方法が求められている。BACKGROUND OF THE INVENTION Phosphate-containing wastewater is generally treated by biological methods or methods of forming sparingly soluble salts. As the sparingly soluble salt, iron salt, aluminum salt and calcium salt are generally used, but the precipitated sludge obtained by the formation of these salts is in the form of gel, which is difficult to concentrate and has a low sludge concentration. However, there is a problem that the sludge is poorly dehydrated. From the phosphate-containing wastewater, the reaction to form sparingly soluble ferric phosphate or aluminum phosphate is
It can be carried out at 6 to 7 neutral to weakly acidic. However, since iron compounds and aluminum compounds are more expensive than calcium compounds, treatments by forming calcium salts are widely used. When a calcium compound such as calcium chloride or slaked lime is added to phosphate-containing wastewater, phosphoric acid and calcium form a salt and precipitate in the form of Ca 5 (PO 4 ) 3 OH, but in this reaction, pH of 10 or more is used. If it is not alkaline, phosphates cannot be removed efficiently, and the treated water must be re-neutralized. When calcium chloride is added as a calcium compound to phosphate-containing wastewater, the pH is usually adjusted by adding sodium hydroxide. When slaked lime is added as a calcium compound, its amount is controlled by measuring the pH of the system. However, if the raw water is neutral or alkaline, sodium hydroxide produced by the following reaction will bring the pH to a control value of 10 to 12 before the reaction equivalent of slaked lime is added, and the phosphate treatment will be unsuccessful. It may be enough. 3NaH 2 PO 4 + 5Ca (OH) 2 → Ca 5 (PO 4 ) 3 OH +
6H 2 O + 3NaOH 3Na 2 HPO 4 + 5Ca (OH) 2 → Ca 5 (PO 4 ) 3 OH +
3H 2 O + 6NaOH 3Na 3 PO 4 + 5Ca (OH) 2 → Ca 5 (PO 4) 3 OH + 9
NaOH In such a case, it is desirable to add an acid such as sulfuric acid to the raw water, and for example, when it is contained in the form of sodium monohydrogen phosphate, it is converted into the form of phosphoric acid by the reaction of the following formula. Na 2 HPO 4 + H 2 SO 4 → H 3 PO 4 + Na 2 SO 4 3H 3 PO 4 + 5Ca (OH) 2 → Ca 5 (PO 4 ) 3 OH + 9H
2 O In this case as well, it is necessary to adjust the pH to 10 to 12 in order to effectively precipitate calcium phosphate. Therefore, there is a demand for a method for treating phosphate-containing wastewater that can be treated at a lower pH and near neutral pH, and that can obtain sludge having a high concentration and good dewaterability.
【０００３】[0003]
【発明が解決しようとする課題】本発明は、カルシウム
化合物による処理を中性に近いpHで行うことができ、脱
水性の良好な高濃度の汚泥を得ることができるリン酸塩
含有廃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。DISCLOSURE OF THE INVENTION According to the present invention, the treatment with a calcium compound can be carried out at a pH close to neutral, and a high-concentration sludge with good dehydration property can be obtained. The purpose is to provide a method.
【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、カルシウム塩の
生成によるリン酸塩含有廃水の処理方法において、生成
汚泥の一部を返送してカルシウム化合物と混合したのち
原水と混合することにより、低いpHでの処理が可能にな
り、かつ脱水性の良好な汚泥が得られることを見いだ
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）リン酸塩を難溶性のカルシウ
ム塩として固液分離するリン酸塩含有廃水の処理方法に
おいて、生成汚泥の一部を返送してカルシウム化合物と
混合したのち原水と混合し、pH７.５〜１１においてリ
ン酸塩をカルシウム塩として沈殿せしめることを特徴と
するリン酸塩含有廃水の処理方法、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、（２）生成
汚泥の返送量が、原水の０.０１〜０.４容量倍である第
(１)項記載のリン酸塩含有廃水の処理方法、（３）カル
シウム化合物が、塩化カルシウム又は消石灰である第
(１)〜(２)項記載のリン酸塩含有廃水の処理方法、
（４）カルシウム化合物の添加量が廃水中のリン酸塩の
理論当量（５Ｃａ／３Ｐ）に対し１〜１０倍である第
(１)〜(３)項記載のリン酸塩含有廃水の処理方法、及
び、（５）廃水中のリン酸塩をカルシウム塩として沈殿
せしめたのち、高分子凝集剤を添加する第(１)〜(４)項
記載のリン酸塩含有廃水の処理方法、を挙げることがで
きる。As a result of intensive studies to solve the above problems, the present inventors have found that a part of sludge produced in a method for treating phosphate-containing wastewater by production of calcium salt. By returning and mixing with a calcium compound and then mixing with raw water, it is possible to treat at a low pH, and it is found that sludge having good dehydratability can be obtained, and the present invention is completed based on this finding. Came to. That is, the present invention provides (1) a method for treating a phosphate-containing wastewater in which a phosphate is solid-liquid separated as a sparingly soluble calcium salt, and a part of the generated sludge is returned and mixed with a calcium compound before being mixed with raw water. Disclosed is a method for treating phosphate-containing wastewater, which comprises mixing and precipitating phosphate as a calcium salt at pH 7.5 to 11. Furthermore, as a preferred embodiment of the present invention, (2) the returned amount of the produced sludge is 0.01 to 0.4 times the volume of the raw water.
The method for treating phosphate-containing wastewater according to (1), (3) The calcium compound is calcium chloride or slaked lime.
A method for treating phosphate-containing wastewater according to (1) to (2),
(4) The addition amount of the calcium compound is 1 to 10 times the theoretical equivalent (5Ca / 3P) of the phosphate in the waste water.
(1) to the treatment method of phosphate-containing wastewater according to (3), and (5) after precipitating the phosphate in the wastewater as a calcium salt, adding a polymer flocculant (1) The method for treating phosphate-containing wastewater according to items (4) to (4) can be mentioned.
【０００５】本発明方法は、リン酸又はリン酸塩を含有
する廃水に適用することができる。このような廃水の発
生源としては、リン酸製造工場をはじめとして、肥料工
場、食品添加剤工場、金属表面処理工場、半導体部品製
造工場など広い分野にわたる工場が含まれるほか、一般
家庭排水や農業排水などがある。本発明方法を適用する
ことができる排水中のリン酸又はリン酸塩の濃度には特
に制限はなく、数ppmから数％までのリン酸又はリン酸
塩を含有する廃水（以下「リン酸塩含有廃水」とい
う。）を本発明方法により処理することができる。図１
は、本発明方法の一態様の工程図である。本発明方法
は、反応槽１、凝集槽２、沈殿槽３及び混合槽４よりな
る設備を用いて実施することができる。反応槽に送った
廃水は、さらに凝集槽から沈殿槽へ導き、沈殿槽におい
て沈殿した汚泥の一部を混合槽へ返送し、混合槽でカル
シウム化合物を添加混合したのち反応槽へ送る。本発明
方法において、混合槽で添加するカルシウム化合物は、
水溶性のカルシウム化合物であれば特に制限なく使用す
ることができる。このようなカルシウム化合物として
は、塩化カルシウム、消石灰、生石灰、硝酸カルシウ
ム、カーバイト滓などを挙げることができるが、安価で
取り扱いの容易な塩化カルシウム又は消石灰を特に好適
に使用することができる。カルシウム化合物は、１種を
単独で使用することができ、あるいは２種以上を混合し
て使用することができる。本発明方法においては、廃水
中に存在するリン酸塩と当量以上のカルシウム化合物を
添加する。リン酸塩とカルシウム化合物の反応生成物
は、主としてＣａ5(ＰＯ4)3ＯＨであり、リン酸塩に対
してカルシウム化合物を理論当量（５Ｃａ／３Ｐ）の１
〜１０倍、好ましくは１.２〜３倍、より好ましくは１.
５〜２倍添加する。The method of the present invention can be applied to wastewater containing phosphoric acid or phosphate. Sources of such wastewater include a wide range of factories such as a phosphoric acid manufacturing plant, a fertilizer factory, a food additive factory, a metal surface treatment factory, and a semiconductor component manufacturing factory. There is drainage. The concentration of phosphoric acid or phosphate in the wastewater to which the method of the present invention can be applied is not particularly limited, and wastewater containing phosphoric acid or phosphate of several ppm to several% (hereinafter referred to as "phosphate The “containing wastewater”) can be treated by the method of the present invention. FIG.
FIG. 3 is a process chart of one embodiment of the method of the present invention. The method of the present invention can be carried out using equipment comprising a reaction tank 1, a coagulation tank 2, a precipitation tank 3 and a mixing tank 4. The waste water sent to the reaction tank is further guided from the coagulation tank to the settling tank, a part of the sludge settled in the settling tank is returned to the mixing tank, the calcium compound is added and mixed in the mixing tank, and then sent to the reaction tank. In the method of the present invention, the calcium compound added in the mixing tank is
Any water-soluble calcium compound can be used without particular limitation. Examples of such a calcium compound include calcium chloride, slaked lime, quick lime, calcium nitrate, and slag, and calcium chloride or slaked lime, which is inexpensive and easy to handle, can be particularly preferably used. The calcium compounds may be used alone or in combination of two or more. In the method of the present invention, the calcium compound in an amount equal to or more than the phosphate present in the waste water is added. The reaction product of the phosphate and the calcium compound is mainly Ca 5 (PO 4 ) 3 OH, and the theoretical amount (5Ca / 3P) of the calcium compound relative to the phosphate is 1
-10 times, preferably 1.2 to 3 times, more preferably 1.
Add 5 to 2 times.
【０００６】本発明方法において、反応槽にアルカリを
添加して、反応槽中の処理水のpHを７.５〜１１とす
る。反応槽中の処理水のpHが７.５未満であると、処理
を終わった沈殿槽の上澄み水のリンの含有量が十分に低
下しないおそれがある。反応槽中の処理水のpHが１１を
超えても、沈殿槽の上澄み水のリンの含有量はpHの上昇
に見合って低下しない上に、上澄み水の中和に多量の酸
が必要となる。反応槽に添加するアルカリには特に制限
はなく、例えば、水酸化ナトリウム、水酸化カリウム、
炭酸ナトリウム、炭酸カリウムなどを挙げることができ
る。混合槽において添加するカルシウム化合物として消
石灰又はカーバイト滓を用いる場合には、混合槽より送
られる消石灰又はカーバイト滓により反応槽中の処理水
のpHを７.５以上とし、反応槽へ直接アルカリを添加す
ることを省くことができる。本発明方法において、カル
シウム化合物として消石灰を使用するときは、廃水中の
リン酸塩が遊離のリン酸になるように、廃水にあらかじ
め酸を添加することが好ましい。添加する酸はリン酸よ
り強い酸であれば特に制限なく使用することができ、例
えば、塩酸、硫酸などを好適に使用することができる。
酸の添加量は、処理すべき廃水のpHが３以下となるよう
添加すれば通常は十分であり、過剰の酸の添加は後工程
でアルカリの損失を招く。リン酸と消石灰の反応により
Ｃａ5(ＰＯ4)3ＯＨが生成するが、消石灰が過剰になる
と反応槽中の処理水のpHが上昇するので、反応槽中の処
理水のpHによって混合槽における消石灰の添加量を制御
することができる。In the method of the present invention, alkali is added to the reaction tank to adjust the pH of the treated water in the reaction tank to 7.5-11. If the pH of the treated water in the reaction tank is less than 7.5, the phosphorus content in the supernatant water of the precipitation tank after the treatment may not be sufficiently reduced. Even if the pH of treated water in the reaction tank exceeds 11, the phosphorus content of the supernatant water of the precipitation tank does not decrease in proportion to the increase in pH, and a large amount of acid is required to neutralize the supernatant water. . There is no particular limitation on the alkali added to the reaction tank, for example, sodium hydroxide, potassium hydroxide,
Examples thereof include sodium carbonate and potassium carbonate. When slaked lime or carbide slag is used as the calcium compound to be added in the mixing tank, the pH of the treated water in the reaction tank is adjusted to 7.5 or higher by the slaked lime or carbide slag sent from the mixing tank, and alkali is fed directly to the reaction tank. Can be omitted. In the method of the present invention, when slaked lime is used as the calcium compound, it is preferable to add an acid to the wastewater in advance so that the phosphate in the wastewater becomes free phosphoric acid. The acid to be added can be used without particular limitation as long as it is stronger than phosphoric acid, and for example, hydrochloric acid and sulfuric acid can be preferably used.
It is usually sufficient to add the acid so that the pH of the wastewater to be treated becomes 3 or less, and the addition of the excess acid causes a loss of alkali in the subsequent step. Ca 5 (PO 4 ) 3 OH is produced by the reaction between phosphoric acid and slaked lime, but when the slaked lime is excessive, the pH of the treated water in the reaction tank rises. The amount of slaked lime added can be controlled.
【０００７】本発明方法においては、凝集槽において、
高分子凝集剤を添加することが好ましい。本発明方法に
おいては、返送された汚泥表面に吸着されたカルシウム
と水中のリン酸塩が反応し、リン酸は汚泥表面で難溶性
のカルシウム塩を形成するので、凝集性及び沈降性の良
好な汚泥が形成されるが、高分子凝集剤を添加すること
により、さらに凝集性及び沈降性を改良することができ
る。使用する高分子凝集剤には特に制限はなく、例え
ば、ポリアクリルアミド、ポリエチレンオキシド、尿素
−ホルマリン樹脂などのノニオン性高分子凝集剤、ポリ
アミノアルキルメタクリレート、ポリエチレンイミン、
ハロゲン化ポリジアリルアンモニウム、キトサンなどの
カチオン性高分子凝集剤、ポリアクリル酸ナトリウム、
ポリアクリルアミド部分加水分解物、部分スルホメチル
化ポリアクリルアミド、ポリ（２−アクリルアミド）−
２−メチルプロパン硫酸塩などのアニオン性高分子凝集
剤を使用することができる。これらの高分子凝集剤の中
で、ノニオン性高分子凝集剤及びアニオン性高分子凝集
剤は凝集効果にすぐれているので、特に好適に使用する
ことができる。本発明方法において、凝集槽で凝集剤を
添加した処理水は沈殿槽に導き凝集した汚泥を沈殿させ
る。沈殿槽の形状には特に制限はなく、例えば、中央駆
動型シックナー、周辺駆動型クラリファイヤー、水平流
型沈殿装置などを使用することができる。沈殿槽におい
て沈降した汚泥は、その一部を返送汚泥として混合槽に
送ってカルシウム化合物と混合し、残余の汚泥は廃棄物
として処理する。混合槽へ送る返送汚泥の量は、原水量
に対し０.０１〜０.４容量倍であることが好ましく、
０.０２〜０.３容量倍であることがより好ましく、０.
０３〜０.２容量倍であることがさらに好ましい。返送
汚泥の量が原水量に対して０.０１容量倍未満である
と、本発明の効果が十分に発揮されないおそれがある。
返送汚泥の量が原水量に対して０.４容量倍を超える
と、返送ポンプが大きくなり設備の利用効率が低下す
る。なお、上記の説明において、生成した沈殿物の分離
に沈殿槽を利用した場合について説明してきたが、沈殿
物の分離は、膜分離、遠心分離など他の固液分離手段を
使用してもよい。In the method of the present invention, in the coagulation tank,
It is preferable to add a polymer flocculant. In the method of the present invention, the calcium adsorbed on the returned sludge surface reacts with the phosphate in water, and phosphoric acid forms a sparingly soluble calcium salt on the sludge surface. Although sludge is formed, the addition of a polymer flocculant can further improve the flocculation property and the sedimentation property. There is no particular limitation on the polymer flocculant used, for example, polyacrylamide, polyethylene oxide, nonionic polymer flocculants such as urea-formalin resin, polyaminoalkyl methacrylate, polyethyleneimine,
Cationic polymer flocculants such as halogenated polydiallylammonium, chitosan, sodium polyacrylate,
Polyacrylamide partial hydrolyzate, partially sulfomethylated polyacrylamide, poly (2-acrylamide)-
Anionic polymeric flocculants such as 2-methylpropane sulfate can be used. Among these polymer flocculants, the nonionic polymer flocculant and the anionic polymer flocculant have excellent flocculating effect and can be used particularly preferably. In the method of the present invention, the treated water added with the coagulant in the coagulation tank is introduced into the settling tank to precipitate the coagulated sludge. The shape of the settling tank is not particularly limited, and for example, a central drive type thickener, a peripheral drive type clarifier, a horizontal flow type settling device, etc. can be used. A part of the sludge settled in the settling tank is sent to the mixing tank as return sludge to be mixed with the calcium compound, and the remaining sludge is treated as waste. The amount of sludge returned to the mixing tank is preferably 0.01 to 0.4 times the volume of raw water,
It is more preferable that the capacity is 0.02 to 0.3 times, and
It is more preferable that the capacity is from 03 to 0.2 times. If the amount of returned sludge is less than 0.01 volume times the amount of raw water, the effect of the present invention may not be sufficiently exhibited.
If the amount of returned sludge exceeds 0.4 times the amount of raw water, the size of the return pump will increase and the utilization efficiency of the equipment will decrease. In the above description, the case where the settling tank is used for separating the generated precipitate has been described, but other solid-liquid separation means such as membrane separation and centrifugation may be used for separating the precipitate. .
【０００８】本発明方法においては、混合槽に返送され
た汚泥にカルシウム化合物を添加し混合する。返送汚泥
を原水と接触する前に、あらかじめカルシウム化合物を
添加し、汚泥表面にカルシウムを吸着させることによ
り、原水中のリン酸塩も汚泥表面でカルシウムと反応
し、生成したカルシウム塩は汚泥表面に強く吸着するの
で、処理水のpHが低い場合であってもリン酸塩の除去効
果がよく、生成する汚泥は従来の方法によるものとは全
く異なる特性を有し、凝集性と沈降性にすぐれたものと
なる。本発明方法において、沈殿槽において分離した汚
泥は、そのまま処分することができるが、さらに容量を
減少するために脱水処理を行うことができる。汚泥の脱
水に用いる脱水機には特に制限はなく、通常の汚泥処理
に使用される機器を使用することができる。このような
脱水機としては、例えば、ベルトプレス脱水機、遠心脱
水機、フィルタープレス脱水機、スクリュープレス脱水
機、真空脱水機などを挙げることができる。本発明方法
において、沈殿槽で生成する上澄み水は、リンの含有量
が少なく、pHは通常７.５〜８.５であり、かつＳＳの量
も少ないので、中和によるpHの再調整や膜分離によるＳ
Ｓの除去のような二次処理を施すことなく、そのまま排
水として放流することができる。In the method of the present invention, a calcium compound is added to and mixed with the sludge returned to the mixing tank. Before contacting the returned sludge with the raw water, by adding a calcium compound in advance and adsorbing calcium on the sludge surface, the phosphate in the raw water also reacts with calcium on the sludge surface, and the generated calcium salt is deposited on the sludge surface. Since it strongly adsorbs, it has a good phosphate removal effect even when the pH of treated water is low, and the sludge produced has characteristics that are completely different from those obtained by conventional methods, and it has excellent cohesiveness and sedimentability. It becomes a thing. In the method of the present invention, the sludge separated in the settling tank can be disposed of as it is, but it can be dehydrated to further reduce the volume. The dehydrator used for dewatering sludge is not particularly limited, and equipment used for ordinary sludge treatment can be used. Examples of such a dehydrator include a belt press dehydrator, a centrifugal dehydrator, a filter press dehydrator, a screw press dehydrator, and a vacuum dehydrator. In the method of the present invention, the supernatant water produced in the settling tank has a low phosphorus content, usually has a pH of 7.5 to 8.5, and has a low amount of SS. S by membrane separation
It can be discharged as waste water as it is without performing a secondary treatment such as removal of S.
【０００９】本発明方法は、従来のリン酸塩含有排水の
処理工程に対して、生成する汚泥の一部を返送し、カル
シウム化合物を混合したのち反応槽に添加するという単
純な工程からなるので、従来の処理設備に少しの変更を
加えることにより、容易に実施することができる。本発
明方法において、汚泥を返送することで従来より低いpH
でリン酸塩含有廃水を処理することができるのは、リン
酸カルシウム汚泥にカルシウムイオンが吸着されるため
である。汚泥表面では、カルシウムイオン濃度が高いた
めカルシウムイオンとリン酸イオンの反応が促進され、
通常より低いpHでリン酸のカルシウム塩が生成すると考
えられる。さらにこのカルシウム塩は汚泥表面に析出す
るため、従来の三次元ゲル状物と異なり、立体的に含ま
れる自由含水が低減する。その結果、生成する汚泥濃度
は従来法の場合の２〜３重量％に対し、本発明方法にお
いては２０〜３０重量％となり、汚泥発生量が大幅に減
少するとともに、脱水処理した場合、ケーキ含水率が従
来法に比して１５〜３０重量％低いケーキを得ることが
できる。Since the method of the present invention comprises a simple step of returning a part of the sludge produced, mixing the calcium compound and then adding the calcium compound to the reaction tank, as compared with the conventional processing step of treating phosphate-containing wastewater. It can be easily implemented by slightly modifying the conventional processing equipment. In the method of the present invention, by returning sludge, lower pH than before
The reason why the phosphate-containing wastewater can be treated with is because calcium ions are adsorbed by the calcium phosphate sludge. Since the calcium ion concentration is high on the sludge surface, the reaction between calcium ions and phosphate ions is promoted,
It is considered that calcium phosphate forms at a pH lower than usual. Furthermore, since this calcium salt precipitates on the surface of the sludge, unlike the conventional three-dimensional gel, the free water content contained in three dimensions is reduced. As a result, the concentration of sludge produced is 20 to 30% by weight in the method of the present invention, compared to 2 to 3% by weight in the case of the conventional method, and the sludge generation amount is significantly reduced, and when the dehydration treatment is performed, the cake water content is reduced. It is possible to obtain a cake whose rate is 15 to 30% by weight lower than that of the conventional method.
【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 リン酸塩を含有する半導体製造工場の廃水を用いて、リ
ン酸塩の除去処理を行った。用いた廃水は、pH８.０、
ＣＯＤ５０ppm、ＳＳ１５ppm、リン酸塩をリンとして４
５ppm含有するものであった。図１に示したものと同じ
工程の机上試験機を用いた。机上試験機は、直径１００
mm、容量１,０００mlの円筒型反応槽１、直径１００m
m、容量１,０００mlの円筒型凝集槽２、直径１５０mm、
容量２,５００mlの沈殿槽３及び直径５０mm、容量２０
０mlの円筒型混合槽４よりなり、原水は順次反応槽、凝
集槽を経由して沈殿槽へ送り、沈殿槽において沈殿した
汚泥の一部は混合槽へ返送し、混合槽でカルシウム化合
物と混合したのち反応槽へ送る。半導体製造工場廃水
を、試験機に３リットル／hrで送り込んだ。反応槽中の
処理水のpHが６.８になるように、反応槽において５重
量％水酸化ナトリウム水溶液を添加した。凝集槽におい
て、ポリアクリルアミド系のポリマー［栗田工業(株)、
クリフロックＰＡ３３１］を濃度１ppmになるよう添加
した。沈殿槽において発生する汚泥を１００ml／hrで混
合槽へ送り、原水に対してカルシウム濃度が１２０ppm
となるよう塩化カルシウムを添加して混合したのち、反
応槽へ導いた。試験機の運転が定常状態に達したとき、
沈殿槽の上澄み水のリンの含有量は１.３ppmであった。 実施例２〜６ 反応槽中の処理水のpHが、それぞれ７.８、８.７、９.
２、１０.２及び１０.８になるよう、水酸化ナトリウム
水溶液の添加量を変えた以外は、実施例１と全く同じ操
作を繰り返した。沈殿槽の上澄み水のリンの含有量は、
それぞれ０.３４、０.１９、０.１５、０.０９６及び
０.０６０ppmであった。 比較例１ 図２は、本比較例に用いた従来法の机上試験機の工程図
である。試験機は、直径１００mm、容量１,０００mlの
円筒型反応槽５、直径１００mm、容量１,０００mlの円
筒型凝集槽６、直径１５０mm、容量２,５００mlの沈殿
槽７及び直径５０mm、容量５００mlの円筒型中和槽８よ
りなり、反応槽に送られた原水は凝集槽から沈殿槽へ導
かれる。実施例１で用いた半導体製造工場廃水を、試験
機に３リットル／hrで送り込んだ。反応槽中の処理水の
pHが８.５になるように、反応槽において５重量％水酸
化ナトリウム水溶液を添加し、また、原水に対してカル
シウム濃度が１２０ppmとなるよう反応槽において塩化
カルシウムを添加した。凝集槽において、ポリアクリル
アミド系のポリマー［栗田工業(株)、クリフロックＰＡ
３３１］を濃度１ppmになるよう添加した。試験機の運
転が定常状態に達したとき、沈殿槽の上澄み水のリンの
含有量は１０.２ppmであった。 比較例２〜４ 反応槽中の処理水のpHが、それぞれ９.２、１０.２及び
１１.１になるよう、水酸化ナトリウム水溶液の添加量
を変えた以外は、比較例１と全く同じ操作を繰り返し
た。沈殿槽の上澄み水のリンの含有量は、それぞれ３.
０、０.４８及び０.０５８ppmであった。実施例１〜６
及び比較例１〜４の結果を、第１表及び図３に示す。The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Example 1 Phosphate removal treatment was performed using wastewater of a semiconductor manufacturing plant containing phosphate. The wastewater used has a pH of 8.0,
COD50ppm, SS15ppm, phosphate as phosphorus 4
It contained 5 ppm. A desktop tester with the same process as shown in FIG. 1 was used. The tabletop tester has a diameter of 100
mm, cylindrical reaction tank 1 with a capacity of 1,000 ml, diameter 100 m
m, cylindrical flocculation tank 2 with a capacity of 1,000 ml, diameter 150 mm,
Settling tank 3 with a capacity of 2,500 ml and diameter 50 mm, capacity 20
It consists of 0 ml cylindrical mixing tank 4, and the raw water is sent to the settling tank through the reaction tank and the coagulation tank one by one, and a part of the sludge settled in the settling tank is returned to the mixing tank and mixed with the calcium compound in the mixing tank. After that, send it to the reaction tank. Wastewater from a semiconductor manufacturing plant was sent to the tester at 3 liters / hr. A 5% by weight aqueous sodium hydroxide solution was added to the reaction tank so that the pH of the treated water in the reaction tank was 6.8. In the coagulation tank, polyacrylamide polymer [Kurita industry Co., Ltd.,
Cliflock PA331] was added to have a concentration of 1 ppm. Sludge generated in the settling tank is sent to the mixing tank at 100 ml / hr, and the calcium concentration is 120 ppm with respect to the raw water.
After adding and mixing calcium chloride so that When the tester operation reaches a steady state,
The phosphorus content of the supernatant water of the precipitation tank was 1.3 ppm. Examples 2 to 6 The pH values of the treated water in the reaction tank were 7.8, 8.7 and 9.
The same operation as in Example 1 was repeated except that the addition amount of the sodium hydroxide aqueous solution was changed so as to be 2, 10.2 and 10.8. The phosphorus content of the supernatant water of the sedimentation tank is
It was 0.34, 0.19, 0.15, 0.096 and 0.060 ppm, respectively. Comparative Example 1 FIG. 2 is a process diagram of a conventional tabletop tester used in this comparative example. The tester comprises a cylindrical reaction tank 5 having a diameter of 100 mm and a capacity of 1,000 ml, a cylindrical flocculation tank 6 having a diameter of 100 mm and a capacity of 1,000 ml, a precipitation tank 7 having a diameter of 150 mm and a capacity of 2,500 ml, and a diameter of 50 mm and a capacity of 500 ml. It consists of a cylindrical neutralization tank 8, and the raw water sent to the reaction tank is guided from the coagulation tank to the precipitation tank. The semiconductor manufacturing plant wastewater used in Example 1 was fed into the testing machine at 3 liters / hr. Treated water in the reaction tank
A 5 wt% sodium hydroxide aqueous solution was added to the reaction tank so that the pH was 8.5, and calcium chloride was added to the raw water so that the calcium concentration was 120 ppm. In the coagulation tank, polyacrylamide-based polymer [Kurifuku PA Co., Ltd., Cliflock PA
331] was added at a concentration of 1 ppm. When the operation of the tester reached a steady state, the phosphorus content of the supernatant water of the precipitation tank was 10.2 ppm. Comparative Examples 2 to 4 Exactly the same as Comparative Example 1 except that the addition amount of the aqueous sodium hydroxide solution was changed so that the pH of the treated water in the reaction tank was 9.2, 10.2 and 11.1, respectively. The operation was repeated. The phosphorus content of the supernatant water of the sedimentation tank is 3.
It was 0, 0.48 and 0.058 ppm. Examples 1-6
The results of Comparative Examples 1 to 4 are shown in Table 1 and FIG.
【００１１】[0011]
【表１】 [Table 1]
【００１２】実施例から、本発明方法によれば、処理水
のpHを排水放流基準内である８.５としたとき、沈殿槽
の上澄み水のリンの含有量は０.２ppmとなり、また、処
理水のpHを７.５とすれば、沈殿槽の上澄み水のリンの
含有量は安定して１ppm以下となることが分かる。これ
に対して、従来法である比較例によれば、処理水のpHを
８.５としたとき、沈殿槽の上澄み水のリンの含有量は
１０ppmと多く、また、沈殿槽の上澄み水のリンの含有
量を１ppm以下とするためには、処理水のpHを９.７以上
にする必要があることが分かる。すなわち、本発明方法
によれば、沈殿槽の上澄み水を中和することなく最終処
理水として排出することができるのに対して、従来法で
は、沈殿槽の上澄み水はpHが高いため中和しなければ最
終処理水として排出することができず、処理水のpHを高
めるために必要なアルカリの量が多く、さらに沈殿槽の
上澄み水を中和するための酸も必要となる。 実施例７ 反応槽中の処理水のpHが８.２になるように、反応槽に
おいて５重量％水酸化ナトリウム水溶液を添加したこと
以外は、実施例１と全く同じ操作を繰り返した。沈殿槽
より抜き出した汚泥の濃度は、２４０ｇ／リットルであ
った。この汚泥をフィルタープレスを用い、ろ過圧力４
kg／cm2、ろ過時間５分でろ過し、さらに、圧搾圧力７k
g／cm2、圧搾時間５分で圧搾したところ、ろ過速度は１
３.８kg／ｍ2・hr、ケーキの含水率は４４.４重量％であ
った。ろ過圧力４kg／cm2、ろ過時間５分のろ過と、圧
搾圧力７kg／cm2、圧搾時間１０分の圧搾をもう一度繰
り返したところ、今回はろ過速度は１３.１kg／ｍ2・h
r、ケーキの含水率は４４.０重量％であった。 比較例５ 反応槽中の処理水のpHが１０.５になるように、反応槽
において５重量％水酸化ナトリウム水溶液を添加したこ
と以外は、比較例１と全く同じ操作を繰り返した。沈殿
槽より抜き出した汚泥の濃度は、２５ｇ／リットルであ
った。この汚泥をフィルタープレスを用い、ろ過圧力４
kg／cm2、ろ過時間５分でろ過し、さらに、圧搾圧力７k
g／cm2、圧搾時間１０分で圧搾したところ、ろ過速度は
２.５kg／ｍ2・hr、ケーキの含水率は７０.８重量％であ
った。また、ろ過圧力４kg／cm2、ろ過時間１０分でろ
過し、さらに、圧搾圧力７kg／cm2、圧搾時間１２分で
圧搾したところ、今回はろ過速度は２.８kg／ｍ2・hr、
ケーキの含水率は７０.６重量％であった。実施例７及
び比較例５の結果を、第２表に示す。According to the method of the present invention, according to the method of the present invention, when the pH of the treated water is 8.5 which is within the discharge standard, the phosphorus content of the supernatant water of the precipitation tank is 0.2 ppm, and It can be seen that if the pH of the treated water is 7.5, the phosphorus content of the supernatant water of the sedimentation tank is stably 1 ppm or less. On the other hand, according to the comparative example, which is a conventional method, when the pH of the treated water was 8.5, the phosphorus content of the supernatant water of the precipitation tank was as high as 10 ppm, and the supernatant water of the precipitation tank was also high. It can be seen that the pH of the treated water needs to be 9.7 or higher in order to reduce the phosphorus content to 1 ppm or lower. That is, according to the method of the present invention, the supernatant water of the precipitation tank can be discharged as the final treated water without being neutralized, whereas in the conventional method, the supernatant water of the precipitation tank has a high pH and thus is neutralized. Otherwise, it cannot be discharged as the final treated water, a large amount of alkali is required to raise the pH of the treated water, and an acid for neutralizing the supernatant water of the precipitation tank is also required. Example 7 The exact same procedure as in Example 1 was repeated except that a 5 wt% aqueous sodium hydroxide solution was added in the reaction tank so that the pH of the treated water in the reaction tank was 8.2. The concentration of sludge extracted from the settling tank was 240 g / liter. This sludge is filtered with a filter press at a filtration pressure of 4
Filtered with kg / cm 2 and filtration time of 5 minutes, and squeezing pressure of 7k
When pressed at g / cm 2 for 5 minutes, the filtration rate is 1
The water content of the cake was 3.8 kg / m 2 · hr and 44.4% by weight. Filtration pressure of 4 kg / cm 2 , filtration time of 5 minutes and compression pressure of 7 kg / cm 2 and compression time of 10 minutes were repeated once again, and this time, the filtration speed was 13.1 kg / m 2 · h.
The water content of r and the cake was 44.0% by weight. Comparative Example 5 The same operation as in Comparative Example 1 was repeated except that a 5 wt% sodium hydroxide aqueous solution was added in the reaction tank so that the pH of the treated water in the reaction tank was 10.5. The concentration of sludge extracted from the settling tank was 25 g / liter. This sludge is filtered with a filter press at a filtration pressure of 4
Filtered with kg / cm 2 and filtration time of 5 minutes, and squeezing pressure of 7k
When pressed at g / cm 2 and a pressing time of 10 minutes, the filtration rate was 2.5 kg / m 2 · hr and the water content of the cake was 70.8% by weight. When the filtration pressure was 4 kg / cm 2 , the filtration time was 10 minutes, and the compression pressure was 7 kg / cm 2 and the compression time was 12 minutes, the filtration rate was 2.8 kg / m 2 · hr this time.
The water content of the cake was 70.6% by weight. The results of Example 7 and Comparative Example 5 are shown in Table 2.
【００１３】[0013]
【表２】 [Table 2]
【００１４】実施例７の本発明方法では、処理水のpHが
８.２と中性に近いにもかかわらず、処理水のpHを１０.
５とした比較例５の従来法と比較すると、汚泥濃度は高
く約１０倍であり、ろ過速度が速く約５倍であり、さら
にケーキ含水率は従来法の約７１重量％から約４４重量
％まで減少し、汚泥及びケーキともに取り扱いやすいも
のとなっている。 実施例８ 本発明方法の機構解明のために、処理水中におけるカル
シウムの挙動を調べた。実施例７において、混合槽より
塩化カルシウムを添加した返送汚泥を採取し、軽く水洗
をしたのち、遠心脱水を行った。この汚泥を０.２８〜
１４ｇ／リットルの６水準の濃度で水に分散し、溶出し
たカルシウム及びリンの量を測定した。汚泥濃度及び汚
泥１ｇ当たりのカルシウム溶出量を第２表に示す。In the method of the present invention of Example 7, although the pH of the treated water was close to neutral at 8.2, the pH of the treated water was 10.
5, the sludge concentration is high, about 10 times, the filtration rate is about 5 times faster, and the cake water content is about 71 wt% to about 44 wt% of the conventional method. The sludge and cake are easy to handle. Example 8 To clarify the mechanism of the method of the present invention, the behavior of calcium in treated water was investigated. In Example 7, the returned sludge containing calcium chloride was collected from the mixing tank, lightly washed with water, and then centrifugally dehydrated. This sludge is 0.28 ~
It was dispersed in water at a concentration of 6 levels of 14 g / liter and the amount of eluted calcium and phosphorus was measured. Table 2 shows the sludge concentration and the calcium elution amount per 1 g of sludge.
【００１５】[0015]
【表３】 [Table 3]
【００１６】汚泥濃度とカルシウム溶出量を両対数グラ
フにプロットしたところ、図４のごとく直線が得られ
た。このことから、カルシウムは汚泥表面に平衡吸着し
ていることが明らかとなった。なお、溶出したリンの濃
度はすべて０.１ppm以下であった。本発明方法において
は、汚泥表面で吸着したカルシウムとリン酸イオンが反
応するので、低いpHでの処理が可能となり、高濃度の汚
泥が得られるものと考えられる。 実施例９ 実施例１と同じ廃水及び同じ机上試験機を用い、混合槽
において塩化カルシウムの代わりに消石灰を添加し、反
応槽において水酸化ナトリウム水溶液を添加することな
く処理を行った。本実施例では、硫酸２００ppmを添加
してpH２.５としたものを原水とした。原水を試験機に
３リットル／hrで送り込んだ。沈殿槽において発生する
汚泥を１００ml／hrで混合槽へ送り、反応槽の処理水の
pHを測定し、処理水のpHが８.２以下のときは混合槽に
２.５重量％消石灰水溶液が平均４０ml／hrで注入さ
れ、処理水のpHが８.２を超えると消石灰水溶液の注入
が停止されるよう制御した。凝集槽においては、ポリア
クリルアミド系のポリマー［栗田工業(株)、クリフロッ
クＰＡ３３１］を濃度１ppmになるよう添加した。試験
機の運転が実質的に定常状態に達したのち、沈殿槽の上
澄み水のpHは８.０〜８.５であり、リンの含有量は０.
１〜０.３ppmであり、汚泥濃度は２１０〜２８０ｇ／リ
ットルであった。When the sludge concentration and the calcium elution amount were plotted on a logarithmic log graph, a straight line was obtained as shown in FIG. From this, it was revealed that calcium was equilibrium adsorbed on the sludge surface. The concentration of eluted phosphorus was 0.1 ppm or less. In the method of the present invention, since calcium adsorbed on the sludge surface reacts with phosphate ions, it is considered that treatment at a low pH is possible and sludge of high concentration can be obtained. Example 9 Using the same wastewater and the same desktop tester as in Example 1, slaked lime was added in place of calcium chloride in the mixing tank, and treatment was performed in the reaction tank without adding an aqueous sodium hydroxide solution. In this example, 200 ppm of sulfuric acid was added to adjust the pH to 2.5 and used as raw water. Raw water was fed into the tester at 3 liters / hr. Sludge generated in the settling tank is sent to the mixing tank at 100 ml / hr, and the treated water in the reaction tank is treated.
The pH was measured. When the pH of the treated water was 8.2 or less, 2.5 wt% slaked lime aqueous solution was injected into the mixing tank at an average of 40 ml / hr. The infusion was controlled to stop. In the coagulation tank, a polyacrylamide polymer [Cliflock PA331, Kurita Water Industries Ltd.] was added to a concentration of 1 ppm. After the operation of the tester has reached a substantially steady state, the pH of the supernatant water of the sedimentation tank is 8.0 to 8.5, and the content of phosphorus is 0.1.
It was 1 to 0.3 ppm, and the sludge concentration was 210 to 280 g / liter.
【００１７】[0017]
【発明の効果】本発明方法によれば、生成する汚泥の濃
度が２０〜３０重量％となるため従来法に比べ汚泥発生
量が１／１０程度に減少し、従来法より低いpHである
７.５〜８.５でリン酸塩の処理が可能となるので必要な
アルカリ及び酸の量が低減し、汚泥の脱水速度が５倍以
上となるので脱水機の小型化が可能であり、脱水性が良
好であるので発生する脱水ケーキの量が３〜４割低減す
る。According to the method of the present invention, since the concentration of sludge produced is 20 to 30% by weight, the sludge generation amount is reduced to about 1/10 of that of the conventional method, and the pH is lower than that of the conventional method. Phosphate treatment from 0.5 to 8.5 reduces the amount of alkali and acid required, and the dewatering speed of sludge becomes 5 times or more, so the dehydrator can be downsized and dehydrated. Since the property is good, the amount of dehydrated cake generated is reduced by 30 to 40%.
【図１】図１は、本発明方法の一態様の工程図である。FIG. 1 is a process drawing of one embodiment of the method of the present invention.
【図２】図２は、比較例に用いた従来法の机上試験機の
工程図である。FIG. 2 is a process diagram of a conventional desktop tester used in a comparative example.
【図３】図３は、処理水のpHと、沈殿槽の上澄み水のリ
ンの含有量の関係を示すグラフである。FIG. 3 is a graph showing the relationship between the pH of treated water and the phosphorus content of the supernatant water of the precipitation tank.
【図４】図４は、汚泥濃度とカルシウム溶出量の関係を
示すグラフである。FIG. 4 is a graph showing the relationship between sludge concentration and calcium elution amount.
１ 反応槽 ２ 凝集槽 ３ 沈殿槽 ４ 混合槽 ５ 円筒型反応槽 ６ 円筒型凝集槽 ７ 沈殿槽 ８ 円筒型中和槽 DESCRIPTION OF SYMBOLS 1 Reaction tank 2 Coagulation tank 3 Precipitation tank 4 Mixing tank 5 Cylindrical reaction tank 6 Cylindrical coagulation tank 7 Precipitation tank 8 Cylindrical neutralization tank
Claims (1)
液分離するリン酸塩含有廃水の処理方法において、生成
汚泥の一部を返送してカルシウム化合物と混合したのち
原水と混合し、pH７.５〜１１においてリン酸塩をカル
シウム塩として沈殿せしめることを特徴とするリン酸塩
含有廃水の処理方法。1. A method for treating a phosphate-containing wastewater in which a phosphate is solid-liquid separated as a sparingly soluble calcium salt, a part of the generated sludge is returned and mixed with a calcium compound and then mixed with raw water to obtain a pH of 7. 0.5 to 11, wherein the phosphate is precipitated as a calcium salt, and the phosphate-containing wastewater is treated.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP05797995A JP3468907B2 (en) | 1995-02-22 | 1995-02-22 | Continuous treatment method for wastewater containing phosphate |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP05797995A JP3468907B2 (en) | 1995-02-22 | 1995-02-22 | Continuous treatment method for wastewater containing phosphate |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH08224587A true JPH08224587A (en) | 1996-09-03 |
| JP3468907B2 JP3468907B2 (en) | 2003-11-25 |
Family
ID=13071136
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP05797995A Expired - Lifetime JP3468907B2 (en) | 1995-02-22 | 1995-02-22 | Continuous treatment method for wastewater containing phosphate |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3468907B2 (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001070951A (en) * | 1999-09-01 | 2001-03-21 | Kurita Water Ind Ltd | Method for treating phosphorus-containing water |
| WO2006074643A2 (en) * | 2005-01-14 | 2006-07-20 | Clausthaler Umwelttechnik-Institut Gmbh (Cutec-Institut) | Method for obtaining phosphate salts, in particular magnesium ammonium phosphate |
| JP2012005941A (en) * | 2010-06-23 | 2012-01-12 | Toshiba Mobile Display Co Ltd | Treatment apparatus and treatment method for phosphorus-containing wastewater |
| JP2021142468A (en) * | 2020-03-11 | 2021-09-24 | 太平洋セメント株式会社 | Waste liquid treatment method |
| JP2021142461A (en) * | 2020-03-10 | 2021-09-24 | 太平洋セメント株式会社 | Waste liquid treatment method |
| CN113461202A (en) * | 2021-06-24 | 2021-10-01 | 宜都兴发化工有限公司 | Resource treatment method for high phosphorus, high calcium and high magnesium |
-
1995
- 1995-02-22 JP JP05797995A patent/JP3468907B2/en not_active Expired - Lifetime
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001070951A (en) * | 1999-09-01 | 2001-03-21 | Kurita Water Ind Ltd | Method for treating phosphorus-containing water |
| JP4581160B2 (en) * | 1999-09-01 | 2010-11-17 | 栗田工業株式会社 | Method for treating phosphorus-containing water |
| WO2006074643A2 (en) * | 2005-01-14 | 2006-07-20 | Clausthaler Umwelttechnik-Institut Gmbh (Cutec-Institut) | Method for obtaining phosphate salts, in particular magnesium ammonium phosphate |
| WO2006074643A3 (en) * | 2005-01-14 | 2007-04-26 | Clausthaler Umwelttechnik Inst | Method for obtaining phosphate salts, in particular magnesium ammonium phosphate |
| JP2012005941A (en) * | 2010-06-23 | 2012-01-12 | Toshiba Mobile Display Co Ltd | Treatment apparatus and treatment method for phosphorus-containing wastewater |
| JP2021142461A (en) * | 2020-03-10 | 2021-09-24 | 太平洋セメント株式会社 | Waste liquid treatment method |
| JP2021142468A (en) * | 2020-03-11 | 2021-09-24 | 太平洋セメント株式会社 | Waste liquid treatment method |
| CN113461202A (en) * | 2021-06-24 | 2021-10-01 | 宜都兴发化工有限公司 | Resource treatment method for high phosphorus, high calcium and high magnesium |
| CN113461202B (en) * | 2021-06-24 | 2023-10-27 | 宜都兴发化工有限公司 | High-phosphorus and high-calcium magnesium recycling treatment method |
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| Publication number | Publication date |
|---|---|
| JP3468907B2 (en) | 2003-11-25 |
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