JP3635619B2 - Water purification method using powdered activated carbon and photocatalyst - Google Patents
Water purification method using powdered activated carbon and photocatalyst Download PDFInfo
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- JP3635619B2 JP3635619B2 JP03889099A JP3889099A JP3635619B2 JP 3635619 B2 JP3635619 B2 JP 3635619B2 JP 03889099 A JP03889099 A JP 03889099A JP 3889099 A JP3889099 A JP 3889099A JP 3635619 B2 JP3635619 B2 JP 3635619B2
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- activated carbon
- titanium oxide
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims description 60
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims description 60
- 238000000034 method Methods 0.000 title claims description 39
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- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 47
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- IISBACLAFKSPIT-UHFFFAOYSA-N bisphenol A Chemical compound C=1C=C(O)C=CC=1C(C)(C)C1=CC=C(O)C=C1 IISBACLAFKSPIT-UHFFFAOYSA-N 0.000 description 4
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- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 3
- 231100000507 endocrine disrupting Toxicity 0.000 description 3
- 238000007539 photo-oxidation reaction Methods 0.000 description 3
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- PUKLDDOGISCFCP-JSQCKWNTSA-N 21-Deoxycortisone Chemical compound C1CC2=CC(=O)CC[C@]2(C)[C@@H]2[C@@H]1[C@@H]1CC[C@@](C(=O)C)(O)[C@@]1(C)CC2=O PUKLDDOGISCFCP-JSQCKWNTSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- FCYKAQOGGFGCMD-UHFFFAOYSA-N Fulvic acid Natural products O1C2=CC(O)=C(O)C(C(O)=O)=C2C(=O)C2=C1CC(C)(O)OC2 FCYKAQOGGFGCMD-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 229910010413 TiO 2 Inorganic materials 0.000 description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 2
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- Treatment Of Water By Oxidation Or Reduction (AREA)
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Description
【０００１】
【発明の属する技術分野】
本発明は、チタン塩、光および活性炭を用いて水を高度に浄化する方法に関する。
【０００２】
【従来の技術】
光触媒化学酸化による水処理方法が研究レベルで検討されているが、以下に記載するような問題があり、実用化された例はまだない。
(1) 酸化チタンなどの光触媒の活性が必ずしも高くなく、かつ高価格な光触媒を多量に必要とし、コスト的にも実用化の大きな障害となっている。
(2) 光触媒反応は、触媒粒子の表面のみに起こる光化学反応であるため、光触媒を粒状にしたり各種担体に固定化したりすると、有効表面積が減少し、反応効率が大きく劣化してしまう。従って、表面積の大きい粉末状の光触媒を用いる方法が、顆粒状の光触媒を利用する方法より反応速度が著しく速く、光触媒反応にとって最も有利となる。しかし、従来の粉末状光触媒は粒径がミクロンオーダであるため、沈降分離がきわめて困難か、もしくは不可能であり実用化が困難である。
【０００３】
例えば、最近の文献「ゾルゲル法による二酸化チタン薄膜を用いた水中のトリクロロエチレンの光触媒分解」（水環境学会誌、第１７巻第５号３２４〜３２９ページ）には、“粉末光触媒を用いると粉末光触媒を回収できず実用化が困難である”と記載されている。
なお、粉末状光触媒はＵＦ膜（限外ろ過膜）を用いて膜分離できるが、被処理水量が多い場合には膜分離のポンプ動力コスト、膜モジュールのコストが高く実用性に欠ける。
【０００４】
一方、粉末活性炭による水処理方法は、主に上水処理分野でかび臭などの異臭味（ジオスミンが主成分）の除去に利用されているが、一度使用した活性炭は使い捨てをせざるを得ないことから、粉末活性炭の注入コストが問題になっている。
【０００５】
【発明が解決しようとする課題】
本発明は、上記従来技術の問題点を解決することを課題とする。
すなわち、本発明の目的は、酸化チタンなどの高価な光触媒を使用する必要がなく、また、粉末活性炭を使い捨てにする必要がなく、かつ粉末活性炭と光触媒粒子を被処理水から簡単に沈降分離でき、分離した光触媒を再利用できる新たな水の浄化方法を提供することである。
【０００６】
【課題を解決するための手段】
本発明のかかる目的は、以下の水の浄化方法により解決された。
１． 原水に粉末活性炭及びチタン塩を添加し、チタン塩を加水分解させて水和酸化チタン−活性炭−複合フロックを生成せしめつつ又は生成せしめた後、光照射処理により原水中の有機物を化学酸化した後、前記水和酸化チタン−活性炭−複合フロックを固液分離することを特徴とする水の浄化方法。
２． 前記固液分離された水和酸化チタン−活性炭−複合フロックを光照射処理工程に返送することを特徴とする前項１記載の水の浄化方法。
３． 前記チタン塩が塩化チタン又は硫酸チタニルであることを特徴とする前項１記載の水の浄化方法。
【０００７】
本発明者は、粉末活性炭およびチタン塩（特に４価チタンイオンを含む凝集剤、例えば、塩化チタン、硫酸チタニルなど）を、原水に添加して撹拌すると、該チタン塩が水中で加水分解され強力な光触媒活性を持つ水酸化チタン（水和酸化チタンＴｉＯ2・Ｈ2Ｏ）フロックが生成し、このフロックに粉末活性炭が取り込まれ、水和酸化チタン−活性炭−複合フロックが生成し、この複合フロックが有機物吸着能力および光照射による有機物分解能力に優れ、且つ沈降分離性に優れていることを見出した。
【０００８】
すなわち、本発明は、原水に粉末活性炭とチタン塩（チタン系凝集剤）とを添加すると、原水中の有機物（例えば、内分泌撹乱物質いわゆる環境ホルモン、農薬、フミン酸、フルボ酸などのトリハロメタン前駆物質などの各種微量有機物）が活性炭及び水和酸化チタンに吸着され、この水和酸化チタン−活性炭−複合フロック存在下で被処理水に光（好ましくは、波長４００ｎｍ以下の紫外線を含む光）を照射すると、吸着された有機物が水和酸化チタンの光触媒作用によって効果的に酸化分解され、活性炭が再生されることを発見して、完成されたものである。
【０００９】
【発明の実施の態様】
次に、本発明の実施の形態について、図面を参照して詳細に説明する。
図１は、本発明に係る粉末活性炭と光触媒による水の浄化方法の一実施の形態を説明する概略説明図である。
【００１０】
（水和酸化チタン生成工程）
図１において、処理対象の原水１に、粉末活性炭２とチタン塩３（Ｔｉ4+塩、例えば、四塩化チタンＴｉＣｌ4、硫酸チタニルＴｉＯＳＯ4等) とを添加し、光反応器４へ移送し撹拌すると、水中でチタン塩が急速に加水分解し、先ず水和酸化チタン超微粒子（肉眼で観察できない）が生成する。
その後、この超微粒子が凝集により漸次成長し、最終的に肉眼で観察可能な程度の粒子径に凝集成長して、沈降性の良好な水和酸化チタン−活性炭−複合フロックが生成する。
この過程で、原水中の有機物は大部分が活性炭に、一部が水和酸化チタンに吸着される。
チタン塩の原水に対する添加量は、ＴｉＯ2として、５〜４０mg／リットルが好ましく、１０〜３０mg／リットルがより好ましい。
また、粉末活性炭の原水に対する添加量は、５０〜１０００mg／リットルが好ましく、１００〜３００mg／リットルがより好ましい。
【００１１】
（光照射工程）
水和酸化チタン−活性炭−複合フロックが生成した被処理水に、光源５より光が照射されると、前記水和酸化チタン生成工程で生成した水和酸化チタン超微粒子および水和酸化チタンフロックの高い光触媒効果によって、活性炭に吸着された有機物（フルボ酸、農薬、有機塩素化合物、内分泌撹乱物質等）が強力に酸化分解される。
光照射に用いる光は、波長４００ｎｍ以下の紫外線を含む光が好ましく、光強度および光照射時間としては、１〜５mw／cm2 で０．５〜１時間程度が好ましい。
光照射工程における被処理水に対する光触媒の量は、水和酸化チタンとして、５００〜３０００mg／リットルが好ましく、１０００〜３０００mg／リットルがより好ましい。
また、光照射工程における被処理水に対する粉末活性炭の量は、５００〜３０００mg／リットルが好ましく、１０００〜２０００mg／リットルがより好ましい。
【００１２】
なお、光反応器４内にオゾン又は／及び過酸化水素６を添加すると、有機物分解反応をさらに促進させることができ、好ましい。これらオゾン又は／及び過酸化水素の添加量は、好ましくは５〜２０mg／リットルである。
また、水和酸化チタン−活性炭−複合フロックを懸濁流動化させるための撹拌に、空気曝気を用いると、酸素供給と撹拌が同時に行なえるので好ましい。
【００１３】
水和酸化チタン生成工程の後に光照射工程を設けるよりも、水和酸化チタン−活性炭−複合フロック生成工程中に紫外線を照射すると、表面積が大きく且つ高活性な、超微粒子状の水和酸化チタン（水和酸化チタン超微粒子）を光化学酸化反応に寄与させることができ、より有利である。
【００１４】
（沈降分離工程）
次いで、光照射工程で光化学酸化反応が施された光照射処理水７を、沈降分離槽８に移送し、水和酸化チタン−活性炭−複合フロックを固液分離すると、高度に浄化された処理水９が得られる。
なお、この複合フロックは、光反応器４内で光照射工程滞留中に撹拌されるのでフロックの径が減少するが、斯かる状態でも従来の市販酸化チタン微粒子よりも沈降性が著しく大きいので、容易に沈降分離できる。
沈降分離槽８で沈降分離された上記複合フロックは、沈降分離槽８の底部から抜き出され、返送汚泥１０として光反応器４に返送され、光触媒として再利用される。
【００１５】
なお、沈降分離工程で微量の高分子凝集剤を添加すると、水和酸化チタン−活性炭−複合フロックの粒径が顕著に増加し、沈降分離性が改善され、より高速の沈降分離が可能となり、より好ましい。
高分子凝集剤の種類としては、カチオン系は効果が少なく、アニオン系、ノニオン系および両性系の高分子凝集剤が適している。このような高分子凝集剤としては、例えば、ポリアクリルアミド、ポリアクリル酸ソーダ、ポリアクリルエステル等が好ましい。また、高分子凝集剤の被処理水に対する添加量は、高分子凝集剤の種類および被処理水の水質によっても異なるが、０．１〜１０mg／リットルが好ましく、０．１〜１mg／リットルがより好ましい。
【００１６】
なお、沈降分離工程において前記高分子凝集剤を利用した場合、水和酸化チタン−活性炭−複合粒子に吸着した前記高分子凝集剤は、分離された複合フロックを返送汚泥１０として光反応器４に返送すると、光触媒による強力な酸化反応により高分子の鎖が切断され、さらに酸化分解される。この結果、水和酸化チタン粒子の界面が更新され、再び光触媒効果を発揮するようになる。
そして、再び新たな高分子凝集剤が沈降分離工程において添加されると、高分子凝集剤分子が水和酸化チタン表面に吸着し、フロック形成が効果的に進み、確実に沈降性を向上できることが明らかになった。
【００１７】
（好気性生物処理工程）
原水１に含まれる種々の微量有機物は、光反応器４内に所要時間滞留する過程で光触媒光化学酸化反応により酸化され、大部分が炭酸ガス、水に酸化分解されるが、一部は炭酸ガス、水にまで分解されず易生物分解性有機物に変化する。
従って、沈降分離工程の後に、図示しない生物膜を利用する好気性生物処理工程（例えば、生物ろ過装置、流動媒体生物処理装置、ハニカム接触材生物膜処理生装置など）を配置して、処理水９を好気性生物処理すると、更に高度に浄化された処理水を得ることができ、より好ましい。
この生物処理工程では、沈降分離水（処理水９）中の易生物分解性有機物（難生物分解性の有機物が光酸化により生物分解性有機物に変化したもの）が、好気性微生物により生物学的に除去される。
【００１８】
なお、この生物処理水の一部を再び光反応器４に循環させると、ＣＯＤ除去効果が向上する。この原因は、光触媒による光酸化を難生物分解性有機物のみに作用させることができるためと考えられる。
生物処理水を光反応器４に循環させない場合は、原水１中の難生物分解性有機物が易生物分解性有機物に変化し、微生物学的に容易に除去できる易生物分解性有機物に対しても光反応が進行してしまうため、無駄な光化学反応が多くなってしまい、光エネルギーの浪費になるものと思われる。
【００１９】
（チタン塩の添加方法）
本発明において、チタン塩の添加方法には下記３つの方法が挙げられる。
第１の添加方法は、原水１にチタン塩３を連続的に添加して、水和酸化チタンを連続的に生成させる方法である。
この場合は、余剰の水酸化チタンスラッジが生じるので、適宜引き抜き処分するか、もしくはスラッジを塩酸、硫酸に溶解して再びチタン系凝集剤として再利用する。
【００２０】
第２の添加方法は、光反応器４内に必要濃度の粉末活性炭、水和酸化チタンが蓄積するまで粉末活性炭、チタン塩を添加し、その後は粉末活性炭と水和酸化チタンの添加を停止する方法である。
この方法は、余剰スラッジが発生しないので汚泥処理が不要となるが、反面、水和酸化チタンが長時間系内に滞留する間に、表面性状が変化し、光触媒活性がやや低下する場合がある。
【００２１】
第３の添加方法は、第１と第２の添加方法を併用した方法であり、最も推奨できる方法である。
この方法は、間欠的に外部からチタン塩と粉末活性炭を注入し、新鮮な水和酸化チタン−活性炭−複合フロックを生成させる一方で、少量の余剰スラッジを間欠的に引抜く方法である。
【００２２】
なお、水和酸化チタン−活性炭−複合粒子の沈降分離工程の前に、好気性生物膜処理工程を設けてもよい。
この場合、光照射処理水７を直接、ＳＳによる閉塞が起きない流動媒体または固定生物接触材による、好気性生物膜処理工程に供給し、光酸化の結果生成した易生物分解性有機物を生物学的に除去し、生物処理水（水和酸化チタン−活性炭−複合粒子が含まれた状態）の一部を光反応器４に循環する。そして、生物処理水の残部を沈降分理槽８に供給し、水和酸化チタン−活性炭−複合粒子を沈降分離し、分離スラッジを光反応器４に返送する。
【００２３】
【実施例】
以下、実施例により本発明を更に詳細に説明するが、本発明はこの実施例により制限されるものではない。
実施例
上水処理取水源になっているＡ河川水（ｐＨ：７．７、ＳＳ：７．３mg／リットル、ＣＯＤ：２．１mg／リットル、色度：７度、ＴＨＭ（トリハロメタン）生成能：２４．６μg/リットル）を採水し、内分泌撹乱物質であるビスフェノールＡを１０ppb 添加したものを試験用原水とし、図１に示す構成の装置により本発明の実験を行なった。
実験の条件は表１のとおりである。
【００２４】
【表１】
表１に示す試験条件で、６ケ月連続試験を実施した結果、硫酸チタニルの加水分解で生成した水和酸化チタン粒子は効果的に沈降分離でき、処理水の水質は安定して平均値で、ＳＳ：１．２mg／リットル、ＣＯＤ：０．５mg／リットル、色度：ゼロ、ＴＨＮ生成能：３．６μg/リットル、ビスフェノールＡ：０．５ppb の極めて高度に浄化された処理水が得られた。
なお、従来の酸化チタン光触媒を購入して添加する必要は全くなかった。
【００２６】
【発明の効果】
本発明によれば、以下の効果がもたらされる。
▲１▼ 活性炭の有機物吸着能力とチタン塩の加水分解によって生成した水和酸化チタンフロックの光触媒効果によって、高度に浄化された処理水を得ることができる。
▲２▼ 高価格な光触媒を購入・使用する必要がなく、更に、四塩化チタン、硫酸チタニルの価格は、酸化チタン有効成分当たりの価格の１／１０程度なので、ランニングコストの大幅低減が可能になる。
▲３▼ 粉末活性炭が光触媒によって再生されるので、活性炭がほぼ永久的に使用できる。
▲４▼ 粉末活性炭と光触媒粒子を、固液分離コストの高い膜分離法を用いることなく、沈降分離法により効率よく分離できる。
【図面の簡単な説明】
【図１】本発明に係る粉末活性炭と光触媒による水の浄化方法の一実施の形態を説明する概略説明図である。
【符号の説明】
１ 原水
２ 粉末活性炭
３ チタン塩
４ 光反応器
５ 光源
６ オゾン又は／及び過酸化水素
７ 光照射処理水
８ 沈降分離槽
９ 処理水
１０ 返送汚泥[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for highly purifying water using titanium salt, light and activated carbon.
[0002]
[Prior art]
A water treatment method by photocatalytic chemical oxidation has been studied at the research level, but there are problems as described below, and no examples have been put to practical use.
(1) The activity of photocatalysts such as titanium oxide is not necessarily high, and a large amount of expensive photocatalysts are required, which is a major obstacle to practical use in terms of cost.
(2) Since the photocatalytic reaction is a photochemical reaction that occurs only on the surface of the catalyst particles, if the photocatalyst is granulated or immobilized on various carriers, the effective surface area decreases and the reaction efficiency is greatly degraded. Therefore, the method using a powdery photocatalyst having a large surface area has a significantly higher reaction rate than the method using a granular photocatalyst, and is most advantageous for the photocatalytic reaction. However, since the conventional powdery photocatalyst has a particle size on the order of microns, sedimentation separation is extremely difficult or impossible and practical application is difficult.
[0003]
For example, a recent document “Photocatalytic degradation of trichlorethylene in water using a titanium dioxide thin film by the sol-gel method” (Journal of the Water Environment Society, Vol. 17, No. 5, pages 324-329) Cannot be recovered and is difficult to put into practical use. "
The powder photocatalyst can be separated by using a UF membrane (ultrafiltration membrane). However, when the amount of water to be treated is large, the pump power cost for membrane separation and the cost of the membrane module are high and lack practicality.
[0004]
On the other hand, the water treatment method using powdered activated carbon is mainly used to remove musty odors and other off-flavors (diosmin is the main component) in the field of water treatment, but activated carbon once used must be disposable. Therefore, the injection cost of powdered activated carbon has become a problem.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to solve the above-described problems of the prior art.
That is, the object of the present invention is that it is not necessary to use an expensive photocatalyst such as titanium oxide, it is not necessary to dispose the powdered activated carbon, and the powdered activated carbon and the photocatalyst particles can be easily separated from the water to be treated. Another object of the present invention is to provide a new water purification method capable of reusing the separated photocatalyst.
[0006]
[Means for Solving the Problems]
This object of the present invention has been solved by the following water purification method.
1. After adding powdered activated carbon and titanium salt to raw water, hydrolyzing titanium salt to form hydrated titanium oxide-activated carbon-composite floc or after chemical oxidation of organic matter in raw water by light irradiation treatment A method for purifying water, characterized by solid-liquid separation of the hydrated titanium oxide-activated carbon-composite floc.
2. 2. The method for purifying water according to item 1, wherein the solid-liquid separated hydrated titanium oxide-activated carbon-composite floc is returned to the light irradiation treatment step.
3. 2. The method for purifying water according to item 1, wherein the titanium salt is titanium chloride or titanyl sulfate.
[0007]
The present inventor added powdered activated carbon and a titanium salt (particularly a flocculant containing tetravalent titanium ions, such as titanium chloride, titanyl sulfate, etc.) to raw water and stirred, the titanium salt was hydrolyzed in water and strongly Titanium hydroxide (hydrated titanium oxide TiO 2 · H 2 O) flocs with excellent photocatalytic activity is generated, and powdered activated carbon is taken into these flocs, and hydrated titanium oxide-activated carbon-composite flocs are formed, and this composite flocs Has been found to be excellent in organic matter adsorption ability and organic matter decomposition ability by light irradiation, and also excellent in sedimentation separation.
[0008]
That is, in the present invention, when powdered activated carbon and titanium salt (titanium-based flocculant) are added to raw water, organic substances in the raw water (for example, endocrine disrupting substances, so-called environmental hormones, agricultural chemicals, humic acid, fulvic acid, and the like trihalomethane precursors) Are adsorbed on activated carbon and hydrated titanium oxide, and light (preferably, light containing ultraviolet rays having a wavelength of 400 nm or less) is irradiated to the water to be treated in the presence of this hydrated titanium oxide-activated carbon-composite floc. Then, the adsorbed organic substance was effectively oxidized and decomposed by the photocatalytic action of the hydrated titanium oxide, and the activated carbon was regenerated.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic explanatory view illustrating one embodiment of a water purification method using powdered activated carbon and a photocatalyst according to the present invention.
[0010]
(Hydrohydrate titanium oxide production process)
In FIG. 1, powdered activated carbon 2 and titanium salt 3 (Ti 4+ salt, for example, titanium tetrachloride TiCl 4 , titanyl sulfate TiOSO 4, etc.) are added to raw water 1 to be treated, and transferred to a photoreactor 4. Upon stirring, the titanium salt rapidly hydrolyzes in water, and firstly, hydrated titanium oxide ultrafine particles (not observable with the naked eye) are formed.
Thereafter, the ultrafine particles gradually grow by agglomeration, and finally agglomerate to a particle size that can be observed with the naked eye, thereby producing a hydrated titanium oxide-activated carbon-composite floc having a good sedimentation property.
In this process, most of the organic matter in the raw water is adsorbed on the activated carbon and partly on the hydrated titanium oxide.
The amount of titanium salt added to the raw water is preferably 5 to 40 mg / liter, more preferably 10 to 30 mg / liter as TiO 2 .
Moreover, 50-1000 mg / liter is preferable and, as for the addition amount with respect to raw | natural water of powdered activated carbon, 100-300 mg / liter is more preferable.
[0011]
(Light irradiation process)
When the water to be treated produced by the hydrated titanium oxide-activated carbon-composite floc is irradiated with light from the light source 5, the hydrated titanium oxide ultrafine particles and the hydrated titanium oxide floc produced in the hydrated titanium oxide production step Due to the high photocatalytic effect, organic substances adsorbed on the activated carbon (fulvic acid, agricultural chemicals, organochlorine compounds, endocrine disrupting substances, etc.) are strongly oxidatively decomposed.
The light used for light irradiation is preferably light containing ultraviolet light having a wavelength of 400 nm or less, and the light intensity and light irradiation time are preferably 1 to 5 mw / cm 2 and about 0.5 to 1 hour.
The amount of the photocatalyst with respect to the water to be treated in the light irradiation step is preferably 500 to 3000 mg / liter, more preferably 1000 to 3000 mg / liter, as hydrated titanium oxide.
Moreover, 500-3000 mg / liter is preferable and, as for the quantity of the powdered activated carbon with respect to the to-be-processed water in a light irradiation process, 1000-2000 mg / liter is more preferable.
[0012]
In addition, it is preferable to add ozone or / and hydrogen peroxide 6 to the photoreactor 4 because the organic substance decomposition reaction can be further promoted. The amount of ozone or / and hydrogen peroxide added is preferably 5 to 20 mg / liter.
Further, it is preferable to use air aeration for stirring for suspending and fluidizing the hydrated titanium oxide-activated carbon-composite floc because oxygen supply and stirring can be performed simultaneously.
[0013]
Rather than providing a light irradiation step after the hydrated titanium oxide production step, when irradiated with ultraviolet rays during the hydrated titanium oxide-activated carbon-composite floc production step, the ultra-fine particulate hydrated titanium oxide has a large surface area and high activity. (Hydrohydrated titanium oxide ultrafine particles) can contribute to the photochemical oxidation reaction, which is more advantageous.
[0014]
(Sediment separation process)
Next, when the light irradiation treated water 7 subjected to the photochemical oxidation reaction in the light irradiation step is transferred to the
In addition, since this composite floc is stirred during the light irradiation process staying in the photoreactor 4, the floc diameter is reduced, but even in such a state, the sedimentation is significantly larger than the conventional commercially available titanium oxide fine particles, Easily settled and separated.
The composite floc that has been separated by settling in the
[0015]
In addition, when a small amount of a polymer flocculant is added in the sedimentation separation step, the particle size of the hydrated titanium oxide-activated carbon-composite flocs is remarkably increased, the sedimentation separation is improved, and faster sedimentation separation is possible, More preferred.
As the kind of the polymer flocculant, the cationic system is less effective, and anionic, nonionic and amphoteric polymer flocculants are suitable. As such a polymer flocculant, for example, polyacrylamide, sodium polyacrylate, polyacryl ester and the like are preferable. The amount of the polymer flocculant added to the water to be treated varies depending on the type of the polymer flocculant and the quality of the water to be treated, but is preferably 0.1 to 10 mg / liter, preferably 0.1 to 1 mg / liter. More preferred.
[0016]
When the polymer flocculant is used in the sedimentation separation step, the polymer flocculant adsorbed on the hydrated titanium oxide-activated carbon-composite particles is returned to the photoreactor 4 using the separated composite floc as the
When a new polymer flocculant is added again in the sedimentation separation step, the polymer flocculant molecules are adsorbed on the surface of the hydrated titanium oxide, and floc formation is effectively advanced, so that sedimentation can be improved with certainty. It was revealed.
[0017]
(Aerobic biological treatment process)
Various trace organic substances contained in the raw water 1 are oxidized by the photocatalytic photochemical oxidation reaction in the process of staying in the photoreactor 4 for a required time, and most of them are oxidatively decomposed into carbon dioxide gas and water. However, it is not decomposed into water and is easily biodegradable organic matter.
Therefore, an aerobic biological treatment step (for example, a biological filtration device, a fluidized medium biological treatment device, a honeycomb contact material biological membrane treatment raw device, etc.) using a biological membrane (not shown) is arranged after the sedimentation separation step to treat the treated water. When 9 is treated with an aerobic organism, treated water that has been further purified can be obtained, which is more preferable.
In this biological treatment process, the readily biodegradable organic matter (the hardly biodegradable organic matter converted into the biodegradable organic matter by photooxidation) in the sedimentation separated water (treated water 9) is biologically converted by the aerobic microorganism. Removed.
[0018]
If a part of this biologically treated water is circulated again to the photoreactor 4, the COD removal effect is improved. This is considered to be because photooxidation by the photocatalyst can be applied only to the hardly biodegradable organic matter.
When the biologically treated water is not circulated in the photoreactor 4, the hardly biodegradable organic matter in the raw water 1 is changed to a readily biodegradable organic matter, and the easily biodegradable organic matter that can be easily removed microbiologically Since the photoreaction proceeds, the useless photochemical reaction increases, and it is thought that light energy is wasted.
[0019]
(Method of adding titanium salt)
In the present invention, the following three methods may be mentioned as the method for adding the titanium salt.
The first addition method is a method in which titanium salt 3 is continuously added to raw water 1 to continuously produce hydrated titanium oxide.
In this case, surplus titanium hydroxide sludge is generated, and therefore, it is appropriately drawn out or disposed of, or the sludge is dissolved in hydrochloric acid and sulfuric acid and reused again as a titanium-based flocculant.
[0020]
In the second addition method, powdered activated carbon and titanium salt are added until the required concentration of powdered activated carbon and hydrated titanium oxide are accumulated in the photoreactor 4, and thereafter the addition of powdered activated carbon and hydrated titanium oxide is stopped. Is the method.
This method eliminates the need for sludge treatment because excess sludge does not occur, but on the other hand, while the hydrated titanium oxide stays in the system for a long time, the surface properties may change and the photocatalytic activity may be slightly reduced. .
[0021]
The third addition method is a method in which the first and second addition methods are used in combination, and is the most recommended method.
In this method, titanium salt and powdered activated carbon are intermittently injected from the outside to produce fresh hydrated titanium oxide-activated carbon-composite floc, while a small amount of excess sludge is intermittently extracted.
[0022]
In addition, you may provide an aerobic biofilm process process before the sedimentation-separation process of hydrated titanium oxide-activated carbon-composite particle.
In this case, the light-irradiated treated water 7 is directly supplied to the aerobic biofilm treatment process using a fluid medium or a fixed biological contact material that is not blocked by SS, and the biodegradable organic matter generated as a result of photooxidation is biologically used. The biologically treated water (a state in which hydrated titanium oxide-activated carbon-composite particles are contained) is circulated to the photoreactor 4. Then, the remainder of the biologically treated water is supplied to the
[0023]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not restrict | limited by this Example.
EXAMPLE River water (pH: 7.7, SS: 7.3 mg / liter, COD: 2.1 mg / liter, chromaticity: 7 degrees, THM (trihalomethane) producing ability: 24.6 μg / liter) was collected, and 10 ppb of bisphenol A, an endocrine disrupting substance, was added as test raw water, and the experiment of the present invention was conducted using the apparatus having the configuration shown in FIG.
Table 1 shows the experimental conditions.
[0024]
[Table 1]
Under the test conditions shown in Table 1, as a result of carrying out a continuous test for 6 months, the hydrated titanium oxide particles produced by the hydrolysis of titanyl sulfate can be effectively settled and separated, and the quality of the treated water is stable and average. SS: 1.2 mg / liter, COD: 0.5 mg / liter, chromaticity: zero, THN production capacity: 3.6 μg / liter, bisphenol A: 0.5 ppb .
There was no need to purchase and add a conventional titanium oxide photocatalyst.
[0026]
【The invention's effect】
According to the present invention, the following effects are brought about.
(1) Highly purified treated water can be obtained by the organic matter adsorption ability of activated carbon and the photocatalytic effect of hydrated titanium oxide floc produced by hydrolysis of titanium salt.
(2) There is no need to purchase and use expensive photocatalysts. Furthermore, the price of titanium tetrachloride and titanyl sulfate is about 1/10 of the price per titanium oxide active ingredient, so running costs can be greatly reduced. Become.
(3) Since the powdered activated carbon is regenerated by the photocatalyst, the activated carbon can be used almost permanently.
{Circle around (4)} Powdered activated carbon and photocatalyst particles can be efficiently separated by a sedimentation separation method without using a membrane separation method having a high solid-liquid separation cost.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory view illustrating one embodiment of a water purification method using powdered activated carbon and a photocatalyst according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Raw water 2 Powdered activated carbon 3 Titanium salt 4 Photoreactor 5 Light source 6 Ozone or / and hydrogen peroxide 7 Light irradiation treated
Claims (3)
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| CN102826722B (en) * | 2012-09-20 | 2014-12-17 | 江苏艾特克环境工程有限公司 | Treatment method for wastewater generated by producing cephalosporin medicines |
| CN112174279B (en) * | 2020-11-13 | 2022-08-02 | 陕西科技大学 | Polymeric aluminosilicate inorganic flocculant and preparation method and application thereof |
| CN113145096A (en) * | 2021-04-30 | 2021-07-23 | 四川大学 | Preparation method of composite photocatalyst for sewage treatment and product thereof |
| JP7454303B1 (en) | 2023-04-05 | 2024-03-22 | 海賀 信好 | Water purification system, water purification method, and fulvic acid decomposition treatment method |
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