JP3823222B2 - Phosphorus removal method in activated sludge treatment - Google Patents
Phosphorus removal method in activated sludge treatment Download PDFInfo
- Publication number
- JP3823222B2 JP3823222B2 JP2001219795A JP2001219795A JP3823222B2 JP 3823222 B2 JP3823222 B2 JP 3823222B2 JP 2001219795 A JP2001219795 A JP 2001219795A JP 2001219795 A JP2001219795 A JP 2001219795A JP 3823222 B2 JP3823222 B2 JP 3823222B2
- Authority
- JP
- Japan
- Prior art keywords
- sludge
- phosphorus
- tank
- reaction tank
- liquid
- 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 - Fee Related
Links
Images
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W10/00—Technologies for wastewater treatment
- Y02W10/10—Biological treatment of water, waste water, or sewage
Landscapes
- Activated Sludge Processes (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、活性汚泥処理におけるリン除去方法に関し、特に、下水等の有機性の汚水を、凝集剤添加活性汚泥法と汚泥の可溶化とを組合せて処理することにより、最小限の汚泥を余剰汚泥として引抜くだけで、有機物の除去と脱リンを行うとともに、発生する汚泥量を最小限にすることができる活性汚泥処理におけるリン除去方法に関するものである。
【０００２】
【従来の技術】
従来、下水処理場等に流入する汚水を処理するために、活性汚泥の曝気槽に汚水を流入し、これを曝気、攪拌して生物処理を行う活性汚泥法が用いられている。水処理工程で発生する余剰汚泥は、通常、脱水を行った後、埋立処分されているが、処分地が次第になくなりつつあることから、余剰汚泥に対し、オゾン等を添加して汚泥を可溶化し、系内で生物分解することにより、汚泥発生量をゼロにする方法が試みられている。
【０００３】
しかしながら、このような汚泥をゼロにする技術は、汚泥として回収していたリンが全く除去できなくなるため、処理水中のリン濃度が高くなるという問題を招来する。
【０００４】
【発明が解決しようとする課題】
本発明は、上記従来の活性汚泥処理におけるリン除去方法が有する問題点に鑑み、有機性汚水を、凝集剤添加活性汚泥法と汚泥の可溶化とを組合せて処理することにより、最小限の汚泥を余剰汚泥として引抜くだけで、有機物の除去と脱リンを行うとともに、発生する汚泥量を最小限にすることができる活性汚泥処理におけるリン除去方法を提供することを目的とする。
【０００５】
【課題を解決するための手段】
上記目的を達成するため、本発明の活性汚泥処理におけるリン除去方法は、反応槽の活性汚泥により有機性汚水を生物処理する活性汚泥処理におけるリン除去方法において、反応槽、又は反応槽から最終沈殿槽への流入部で汚水に鉄塩等の金属塩系凝集剤を添加してリンを不溶化させた後、反応槽から発生する汚泥に酸を添加して、汚泥の可溶化とリンの溶出を行うとともに、該可溶化汚泥の固液分離を行い、該分離液にアルカリ剤を添加してリンを再び不溶化させ、該分離液中の不溶化したリンを固液分離することにより、リンを分離し排出することを特徴とする。
【０００６】
この活性汚泥処理におけるリン除去方法は、反応槽、又は反応槽から最終沈殿槽への流入部で汚水に鉄塩等の金属塩系凝集剤を添加してリンを不溶化させた後、反応槽から発生する汚泥に酸を添加して汚泥の可溶化とリンの溶出を行うとともに、該可溶化汚泥の固液分離を行い、該分離液にアルカリ剤を添加してリンを再び不溶化させ、該分離液中の不溶化したリンを固液分離することによりリンを分離し排出することから、可溶化した汚泥を反応槽に返送して生物処理をすることにより、有機汚泥の排出をほとんど無くすとともに、酸により溶出したリンをアルカリ剤により不溶化し、リンを含む無機物主体の汚泥として排出することができ、これにより、場外に排出する汚泥を従来の活性汚泥法の１割程度に削減しながら、処理水の脱リンを実現することができる。
さらに、排出する汚泥は、無機物が主体であるため、一時貯留する間にも嫌気腐敗して悪臭を発生するなどの問題が生じることがない。
【０００７】
この場合において、酸の添加後に固液分離した汚泥と、アルカリ剤によるリンの不溶化後に固液分離した分離液とを、反応槽に返送することができる。
【０００８】
これにより、酸添加後に分離した汚泥と、アルカリ剤のリン不溶化後に分離した分離液とを、反応槽にて活性汚泥により生物処理することができる。
【０００９】
また、反応槽で処理された汚水を、最終沈殿槽又は膜分離装置で固液分離を行うことにより汚泥と処理水とに分離することができる。
【００１０】
これにより、酸を添加する汚泥を、最終沈殿槽より得たり、反応槽より直接得たりすることができる。
【００１１】
さらに、酸を添加して汚泥のｐＨを２以下とし、アルカリ剤を添加して分離液のｐＨを３以上とすることができる。
【００１２】
これにより、汚泥の可溶化性能を高め、リンの溶出を効率よく行うとともに、その後、リンを不溶化することができる。
【００１３】
そして、酸を添加した汚泥に対し、１時間以上、３０℃以上の加熱処理を行うことができる。
【００１４】
これにより、汚泥の可溶化性能を高めることができる。
【００１５】
【発明の実施の形態】
以下、本発明の活性汚泥処理におけるリン除去方法の実施の形態を図面に基づいて説明する。
【００１６】
この活性汚泥処理におけるリン除去方法は、活性汚泥法又は膜分離活性汚泥法において、リンの凝集剤を反応槽又は最終沈殿槽への流入部に添加して、汚水中のリン酸を不溶化させるとともに、最終沈殿槽又は反応槽から所定量の汚泥を汚泥可溶化槽に導き、酸を添加して汚泥の可溶化とリンの溶出を促進する。
そして、所定の反応時間の後、この可溶化汚泥を第１沈殿槽に送泥して固液分離を行い、沈殿した汚泥は反応槽へと返送する。
一方、分離液は、オーバーフロー又はポンプにより引抜き、これにアルカリ剤を添加、混合することにより、リンを再び不溶化させて第２沈殿槽に導く。
この第２沈殿槽で沈殿分離した汚泥は、一時貯留の後、場外に搬出し、また、分離液は反応槽に返流し、生物処理を行う。なお、汚泥可溶化槽において、可溶化性能を高めるために、酸の添加後に３０℃以上に加熱し、１時間以上かけて反応させることも可能である。
【００１７】
活性汚泥法又は膜分離活性汚泥法において、汚水中に含まれるリンの内、固形物状のものは、活性汚泥に付着又は吸着され、汚水から除去される。
これに対し、溶解性のリン酸は、一部が微生物体内に取込まれるが、残りは処理水とともに流出するため、鉄塩等の金属塩系凝集剤を反応槽又は最終沈殿槽への流入部に添加することにより、リン酸化合物として不溶化させる。
最終沈殿槽や反応槽から、所定量の汚泥とともに汚泥可溶化槽に導かれたリン酸化合物や固形物状のリンは、酸を添加してｐＨを５以下、好ましくは２以下に下げることにより、微生物体内から溶出したり、液中に溶解した状態となる。
このとき、汚泥微生物も酸により死滅し、細胞壁や細胞膜の一部が破壊されるため、微生物体内の成分が液中に溶け出す。さらに３０℃以上に加熱し、１時間以上かけて反応させれば、汚泥の可溶化を促進することができる。
【００１８】
次に、可溶化した汚泥を第１沈殿槽に導いて固液分離を行い、沈殿した汚泥分を反応槽に返送すると、可溶化していない汚泥微生物も、死滅したり細胞壁や細胞膜の一部が傷つけられているため、反応槽内の汚泥微生物の作用により、分解処理される。
一方、この第１沈殿槽の分離液には、溶出したリンやリン酸が含まれているが、これを第２沈殿槽に導く間にアルカリ剤を添加し、ｐＨを３以上に上げることにより、リンの大半は再び固形物状となり、リン酸も金属塩と反応して不溶化する。
このとき、酸によって溶解していた無機物も、ｐＨ上昇に伴い固形物に戻るため、第２沈殿槽で沈殿した汚泥は、リン酸化合物などの無機物主体の汚泥となる。
なお、第２沈殿槽の分離液には、可溶化処理により溶出した有機物が含まれているため、沈殿分離液として反応槽に返流し、生物学的に処理を行う。
【００１９】
以上により、反応槽で増加する汚泥は、可溶化処理により他の微生物の栄養源として分解処理され、また、第２沈殿槽で沈殿し場外に搬出される汚泥は、凝集したリン酸化合物と、酸で可溶化した後アルカリ剤で再度不溶化した無機物主体の汚泥となるため、汚泥量が従来の１／１０程度となるのに加え、脱リンも可能なプロセスとなる。
【００２０】
（実施例）
図１に、本発明の活性汚泥処理におけるリン除去方法の一実施例を処理フローにより示す。
下水処理場のような汚水の処理施設に流入した汚水Ａは、前処理設備１で砂分やし渣を除去した後、反応槽２へと送水され、活性汚泥により生物的に処理される。
反応槽２で処理された汚水は、汚泥混合液として、最終沈殿槽３へと送水され、固液分離されて処理水Ｂとしてオーバーフローし、消毒等の処理を施した後、外部に放流される。
この場合、４は凝集剤供給装置であり、汚水中のリン酸と反応し化合物を生成する、鉄やアルミ等の金属塩系の凝集剤を反応槽２に添加する。この凝集剤供給装置４の位置は、反応槽２に直接注入する以外に、反応槽２から最終沈殿槽３に送水する間で注入することも可能である。
【００２１】
一方、沈殿した汚泥Ｃは、汚泥移送ポンプ５により間欠的又は連続的に引抜かれ、反応槽２へと返送される。
また、沈殿汚泥Ｃの一部は、余剰汚泥として、汚泥投入ポンプ６により汚泥可溶化槽７に投入され、酸供給装置８から供給された硫酸等の酸により、汚泥の可溶化とリンの溶出が行われる。
このとき、汚泥可溶化槽７の汚泥を３０℃以上に加熱し、１時間以上反応させることにより、さらに汚泥の可溶化を促進することができる。
【００２２】
汚泥可溶化槽７で所定の時間反応を行った後、可溶化汚泥Ｄを第１沈殿槽９に導く。
汚泥可溶化槽７で加熱処理を行わない場合は、汚泥の沈殿に時間を要するが、加熱処理を行った汚泥は、汚泥濃度が低く、沈降性も良いため、より短い時間で沈殿分離することができる。
この第１沈殿槽９で沈殿した可溶化濃縮汚泥Ｆは、汚泥移送ポンプ５等を用いて、反応槽２に返送し、再び生物処理を行う。
【００２３】
これに対し、第１沈殿槽９の分離液Ｅは、オーバーフローさせるか、又はポンプにより第２沈殿槽１１に導くが、この間にアルカリ剤供給装置１０により、アルカリ剤を注入してｐＨを調整する。
第２沈殿槽１１で沈殿した汚泥Ｈは、汚泥排出ポンプ１２により、汚泥濃縮貯留槽１３に送泥し、一時貯留する。
貯留した汚泥Ｉは、バキューム車等により処理場外に搬出するが、汚泥濃縮貯留槽１３に脱水設備等の設備を設け、定期的に引抜いて後処理を行うことも可能である。
なお、第２沈殿槽１１の沈殿分離液Ｇは、反応槽２へと返流させるが、汚泥濃縮貯留槽１３でも、一時貯留する間に上澄液ができるため、分離液を返流させる配管を設けることが望ましい。
【００２４】
次に、本実施例の活性汚泥処理におけるリン除去方法の作用について説明する。
汚泥投入ポンプ６により、汚泥可溶化槽７に投入された汚泥には、微生物体内に取込まれたリン酸、凝集剤により不溶化したリン酸化合物、及び固形物状のリンが含まれている。
汚泥可溶化槽７では、酸供給装置８により、酸を所定量、又は汚泥可溶化槽７内に設けたｐＨセンサーにより５以下、好ましくは２以下の所定の値になるまで、酸を注入する。
この汚泥可溶化槽７には、攪拌機を設け、緩やかに攪拌しながら１時間以上反応させるが、このとき、槽内を加熱して汚泥の温度を３０℃以上とすれば、汚泥の可溶化が促進される。
すなわち、酸と温度の作用で、微生物は死滅し、微生物を構成する細胞壁や細胞膜の一部が加水分解されて、細胞内の細胞質が溶出する。
また、このとき、微生物体内に取込まれていたリンが可溶化汚泥の液中に溶出するとともに、酸の作用により、リン酸化合物や固形物状のリンが液中に溶解する。
【００２５】
所定の時間、可溶化処理を施された可溶化汚泥Ｄは、全量が第１沈殿槽９へと送水され、固液分離が行われる。
この固液分離により沈殿した可溶化濃縮汚泥Ｆは、大部分が死滅した微生物であるが、これを汚泥移送ポンプ５等により、反応槽２に返送すると、活性汚泥の微生物が分泌する酵素の作用により、徐々に炭酸ガス等に分解される。
【００２６】
一方、固液分離された第１沈殿槽９の分離液Ｅは、オーバーフロー又はポンプにより、第２沈殿槽１１へと移送される。
そして、この移送の間に、アルカリ剤供給装置１０により、アルカリ剤を注入してｐＨを３以上に上昇させると、溶解していたリンの大半は再び固形物状となり、リン酸も凝集剤の金属塩と反応してリン酸化合物となり不溶化する。
このとき、酸によって溶解していた無機物も、ｐＨ上昇に伴い固形物に戻るため、第２沈殿槽１１で沈殿した汚泥は、リン酸化合物などの無機物主体の汚泥となる。
なお、第２沈殿槽１１の分離液には、可溶化処理により溶出した有機物が含まれているため、沈殿分離液Ｇとして反応槽２に返流し、活性汚泥により再び生物学的に処理を行う。
【００２７】
このように、本実施例の活性汚泥処理におけるリン除去方法は、活性汚泥法又は膜分離活性汚泥法において、凝集剤を反応槽２又は最終沈殿槽３への流入部に添加して、汚水中のリン酸を不溶化させるため、従来の凝集剤添加方式と同等の安定したリン除去性能を得ることができる。
また、最終沈殿槽３又は反応槽２から汚泥を引抜いて汚泥可溶化槽７に導き、酸を添加するとともに、必要により加熱処理を行って可溶化を促進した後、反応槽２に返送して、活性汚泥により生物処理を行うため、発生する余剰汚泥をほとんどゼロにすることができる。
さらに、汚泥可溶化槽７で、汚泥から溶出したリンや溶解したリン酸化合物は、沈殿分離後、アルカリ剤を添加してｐＨを調整することにより、再度不溶化して無機物主体の汚泥Ｈとして沈殿分離するため、場外に排出する汚泥量を、従来の活性汚泥法の１／１０程度に削減でき、埋立処分する際にも必要な用地が少なくて済み、一時貯留する間にも、嫌気腐敗して悪臭を発生するなどの問題が生じないという効果を有する。
【００２８】
以上、実施例では、反応槽２と最終沈殿槽３からなるフローにおいて、最終沈殿槽３から引抜いた汚泥を可溶化処理しているが、最終沈殿槽３での沈殿後にさらに濃縮を行い、この濃縮汚泥に対して可溶化処理を行うことも可能である。
また、固液分離は、重力式の沈殿槽を用いているが、遠心分離など、他の固液分離装置を用いることも可能である。
さらに、最終沈殿槽３の代わりに、反応槽２内に膜分離装置（図示省略）を設け、精密濾過膜、限外濾過膜等の膜により、汚水を濾過する膜分離活性汚泥法を採用し、膜を用いることにより汚泥濃度を高め、反応槽２から直接引抜いた汚泥に対し、可溶化処理を行うことも可能である。
【００２９】
【発明の効果】
本発明の活性汚泥処理におけるリン除去方法によれば、反応槽、又は反応槽から最終沈殿槽への流入部で汚水に鉄塩等の金属塩系凝集剤を添加してリンを不溶化させた後、反応槽から発生する汚泥に酸を添加して汚泥の可溶化とリンの溶出を行うとともに、該可溶化汚泥の固液分離を行い、該分離液にアルカリ剤を添加してリンを再び不溶化させ、該分離液中の不溶化したリンを固液分離することによりリンを分離し排出することから、可溶化した汚泥を反応槽に返送して生物処理をすることにより、有機汚泥の排出をほとんど無くすとともに、酸により溶出したリンをアルカリ剤により不溶化し、リンを含む無機物主体の汚泥として排出することができ、これにより、場外に排出する汚泥を従来の活性汚泥法の１割程度に削減しながら、処理水の脱リンを実現することができる。
さらに、排出する汚泥は、無機物が主体であるため、一時貯留する間にも嫌気腐敗して悪臭を発生するなどの問題が生じることがない。
【００３０】
また、酸の添加後に固液分離した汚泥と、アルカリ剤によるリンの不溶化後に固液分離した分離液とを、反応槽に返送することにより、酸添加後に分離した汚泥と、アルカリ剤のリン不溶化後に分離した分離液とを、反応槽にて活性汚泥により生物処理することができる。
【００３１】
また、反応槽で処理された汚水を、最終沈殿槽又は膜分離装置で固液分離を行うことによって汚泥と処理水とに分離することにより、酸を添加する汚泥を、最終沈殿槽より得たり、反応槽より直接得たりすることができる。
【００３２】
さらに、酸を添加して汚泥のｐＨを２以下とし、アルカリ剤を添加して分離液のｐＨを３以上とすることにより、汚泥の可溶化性能を高め、リンの溶出を効率よく行うとともに、その後、リンを不溶化することができる。
【００３３】
そして、酸を添加した汚泥に対し、１時間以上、３０℃以上の加熱処理を行うことにより、汚泥の可溶化性能を高めることができる。
【図面の簡単な説明】
【図１】 本発明の活性汚泥処理におけるリン除去方法の一実施例を示す汚水処理のフロー図である。
【符号の説明】
１ 前処理設備
２ 反応槽
３ 最終沈殿槽
４ 凝集剤供給装置
５ 汚泥移送ポンプ
６ 汚泥投入ポンプ
７ 汚泥可溶化槽
８ 酸供給装置
９ 第１沈殿槽
１０ アルカリ剤供給装置
１１ 第２沈殿槽
１２ 汚泥排出ポンプ
１３ 汚泥濃縮貯留槽
Ａ 汚水
Ｂ 処理水
Ｃ 沈殿汚泥
Ｄ 可溶化汚泥
Ｅ 分離液
Ｆ 可溶化濃縮汚泥
Ｇ 沈殿分離液
Ｈ 排出汚泥
Ｉ 貯留汚泥[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for removing phosphorus in activated sludge treatment, and in particular, organic sludge such as sewage is treated with a combination of a flocculant-added activated sludge method and sludge solubilization, so that a minimum amount of sludge is surplus. The present invention relates to a method for removing phosphorus in activated sludge treatment that can remove organic matter and remove phosphorus, and minimize the amount of generated sludge, simply by extracting as sludge.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in order to treat sewage flowing into a sewage treatment plant or the like, an activated sludge method is used in which sewage is introduced into an activated sludge aeration tank, and this is aerated and agitated to perform biological treatment. Excess sludge generated in the water treatment process is usually landfilled after dehydration, but because the disposal site is gradually disappearing, ozone is added to the excess sludge to solubilize the sludge. Attempts have been made to eliminate sludge generation by biodegradation in the system.
[0003]
However, such a technique for reducing sludge to zero causes a problem that the phosphorus concentration in the treated water becomes high because phosphorus recovered as sludge cannot be removed at all.
[0004]
[Problems to be solved by the invention]
In view of the problem of the phosphorus removal method in the conventional activated sludge treatment described above, the present invention treats organic sewage in combination with a flocculant-added activated sludge method and sludge solubilization, thereby minimizing sludge. It is an object of the present invention to provide a method for removing phosphorus in activated sludge treatment that can remove organic matter and remove phosphorus and minimize the amount of generated sludge by simply pulling out as excess sludge.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the phosphorus removal method in the activated sludge treatment of the present invention is a final removal from the reaction tank or the reaction tank in the phosphorus removal method in the activated sludge treatment in which organic sludge is biologically treated with the activated sludge in the reaction tank. After adding a metal salt-based flocculant such as iron salt to the sewage at the inlet to the tank to insolubilize phosphorus, acid is added to the sludge generated from the reaction tank to solubilize the sludge and dissolve phosphorus. And separating the phosphorus by solid-liquid separation of the solubilized sludge, adding an alkaline agent to the separated liquid to insolubilize phosphorus again, and solid-liquid separating the insolubilized phosphorus in the separated liquid. It is characterized by discharging.
[0006]
The phosphorus removal method in this activated sludge treatment is made by adding a metal salt-based flocculant such as iron salt to the sewage at the inflow part from the reaction tank or the reaction tank to the final sedimentation tank, and then insolubilizing phosphorus. Acid is added to the generated sludge to solubilize sludge and phosphorus is eluted. Solid-liquid separation of the solubilized sludge is performed, and an alkaline agent is added to the separated liquid to insolubilize phosphorus again. Since phosphorus is separated and discharged by solid-liquid separation of the insolubilized phosphorus in the liquid, the solubilized sludge is returned to the reaction tank for biological treatment, so that almost no organic sludge is discharged and acid Phosphorus eluted by the alkaline agent can be insolubilized with an alkaline agent and discharged as inorganic sludge containing phosphorus, thereby reducing the sludge discharged outside the site to about 10% of the conventional activated sludge process, Removal of It can be realized.
Furthermore, since the discharged sludge is mainly composed of inorganic substances, problems such as anaerobic rot and generation of bad odors do not occur even during temporary storage.
[0007]
In this case, the sludge separated into solid and liquid after the addition of acid and the separated liquid separated into solid and liquid after insolubilization of phosphorus with an alkaline agent can be returned to the reaction vessel.
[0008]
Thereby, the sludge separated after the acid addition and the separation liquid separated after the phosphorus insolubilization of the alkaline agent can be biologically treated with the activated sludge in the reaction tank.
[0009]
Moreover, the sewage treated in the reaction tank can be separated into sludge and treated water by performing solid-liquid separation in a final sedimentation tank or a membrane separator.
[0010]
Thereby, the sludge to which an acid is added can be obtained from the final sedimentation tank or directly from the reaction tank.
[0011]
Furthermore, an acid can be added to make the sludge pH 2 or less, and an alkaline agent can be added to make the separation solution pH 3 or more.
[0012]
Thereby, the solubilization performance of sludge can be improved, phosphorus can be eluted efficiently, and then phosphorus can be insolubilized.
[0013]
And it can heat-treat at 30 degreeC or more for 1 hour or more with respect to the sludge which added the acid.
[0014]
Thereby, the solubilization performance of sludge can be improved.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a phosphorus removal method in activated sludge treatment of the present invention will be described based on the drawings.
[0016]
In the activated sludge process or the membrane separation activated sludge method, the phosphorus removal method in this activated sludge treatment adds a phosphorus flocculant to the inflow part to the reaction tank or the final sedimentation tank, and insolubilizes phosphoric acid in the sewage. Then, a predetermined amount of sludge is introduced from the final sedimentation tank or reaction tank to the sludge solubilization tank, and acid is added to promote sludge solubilization and phosphorus elution.
Then, after a predetermined reaction time, the solubilized sludge is sent to the first settling tank for solid-liquid separation, and the precipitated sludge is returned to the reaction tank.
On the other hand, the separation liquid is drawn out by overflow or a pump, and an alkaline agent is added to and mixed with this to insolubilize phosphorus again and lead it to the second precipitation tank.
The sludge precipitated and separated in the second settling tank is temporarily stored and then taken out of the field, and the separated liquid is returned to the reaction tank for biological treatment. In addition, in a sludge solubilization tank, in order to improve solubilization performance, it is also possible to heat to 30 degreeC or more after addition of an acid, and to make it react over 1 hour or more.
[0017]
In the activated sludge method or the membrane-separated activated sludge method, solid substances in the phosphorus contained in the sewage are attached or adsorbed to the activated sludge and removed from the sewage.
In contrast, a part of soluble phosphoric acid is taken into the body of the microorganism, but the rest flows out with the treated water, so the metal salt-based flocculant such as iron salt flows into the reaction tank or final sedimentation tank. By adding to the part, it is insolubilized as a phosphate compound.
Phosphoric acid compounds and solid phosphorous led from the final sedimentation tank and reaction tank to the sludge solubilization tank together with a predetermined amount of sludge are reduced by adding acid to lower the pH to 5 or less, preferably 2 or less. , Elution from the body of the microorganism, or dissolved in the liquid.
At this time, the sludge microorganisms are also killed by the acid, and part of the cell wall and cell membrane are destroyed, so that the components in the microorganism body are dissolved in the liquid. Furthermore, if it heats to 30 degreeC or more and it is made to react over 1 hour or more, solubilization of sludge can be accelerated | stimulated.
[0018]
Next, the solubilized sludge is guided to the first sedimentation tank for solid-liquid separation, and when the precipitated sludge is returned to the reaction tank, the unsolubilized sludge microorganisms are killed or part of the cell wall or cell membrane. Is damaged by the action of sludge microorganisms in the reaction tank.
On the other hand, the separation liquid of the first precipitation tank contains eluted phosphorus and phosphoric acid. By introducing an alkaline agent while introducing this into the second precipitation tank, the pH is raised to 3 or more. Most of the phosphorus becomes solid again, and phosphoric acid reacts with the metal salt to become insoluble.
At this time, since the inorganic substance dissolved by the acid also returns to a solid substance as the pH rises, the sludge precipitated in the second settling tank becomes a sludge mainly composed of inorganic substances such as phosphate compounds.
In addition, since the organic substance eluted by the solubilization process is contained in the separation liquid of the second precipitation tank, it is returned to the reaction tank as a precipitation separation liquid and biologically processed.
[0019]
As described above, the sludge increasing in the reaction tank is decomposed as a nutrient source for other microorganisms by solubilization treatment, and the sludge precipitated in the second settling tank and carried out of the field is an aggregated phosphate compound, Since it becomes an inorganic-based sludge that has been solubilized with an acid and then insolubilized again with an alkali agent, the amount of sludge becomes about 1/10 of the conventional amount, and in addition, a process capable of dephosphorization is achieved.
[0020]
(Example)
In FIG. 1, one Example of the phosphorus removal method in the activated sludge process of this invention is shown with a processing flow.
The sewage A that has flowed into a sewage treatment facility such as a sewage treatment plant is removed from the sand and scum by the pretreatment facility 1 and then sent to the reaction tank 2 where it is biologically treated with activated sludge.
The sewage treated in the reaction tank 2 is sent to the final sedimentation tank 3 as a sludge mixed liquid, separated into solid and liquid, overflowed as treated water B, treated for disinfection, etc., and then discharged to the outside. .
In this case, 4 is a flocculant supply device, and a metal salt-based flocculant such as iron or aluminum that reacts with phosphoric acid in wastewater to form a compound is added to the reaction tank 2. The position of the flocculant supply device 4 can be injected while water is fed from the reaction tank 2 to the final sedimentation tank 3 in addition to direct injection into the reaction tank 2.
[0021]
On the other hand, the precipitated sludge C is withdrawn intermittently or continuously by the sludge transfer pump 5 and returned to the reaction tank 2.
Further, a part of the precipitated sludge C is supplied as surplus sludge to the sludge solubilization tank 7 by the sludge input pump 6, and the sludge is solubilized and phosphorus is eluted by the acid such as sulfuric acid supplied from the acid supply device 8. Is done.
At this time, sludge solubilization can be further promoted by heating the sludge in the sludge solubilization tank 7 to 30 ° C. or higher and reacting for 1 hour or longer.
[0022]
After reacting for a predetermined time in the sludge solubilization tank 7, the solubilized sludge D is guided to the first sedimentation tank 9.
When heat treatment is not performed in the sludge solubilization tank 7, it takes time for the sludge to settle. However, the sludge that has been heat-treated has a low sludge concentration and good sedimentation, so that it should be separated in a shorter time. Can do.
The solubilized and concentrated sludge F precipitated in the first settling tank 9 is returned to the reaction tank 2 using the sludge transfer pump 5 and the like, and biological treatment is performed again.
[0023]
On the other hand, the separation liquid E in the first settling tank 9 is overflowed or led to the second settling tank 11 by a pump. During this period, the alkaline agent is supplied by the alkaline agent supply device 10 to adjust the pH. .
The sludge H precipitated in the second sedimentation tank 11 is sent to the sludge concentration storage tank 13 by the sludge discharge pump 12 and temporarily stored.
The stored sludge I is carried out of the treatment plant by a vacuum vehicle or the like. However, it is also possible to provide equipment such as a dewatering facility in the sludge concentration storage tank 13 and periodically withdraw it for post-treatment.
In addition, although the sediment separation liquid G of the 2nd sedimentation tank 11 is returned to the reaction tank 2, since the supernatant liquid is made in the sludge concentration storage tank 13 during temporary storage, the piping for returning the separation liquid is used. It is desirable to provide
[0024]
Next, the effect | action of the phosphorus removal method in the activated sludge process of a present Example is demonstrated.
The sludge charged into the sludge solubilization tank 7 by the sludge charging pump 6 contains phosphoric acid taken into the microorganism, a phosphoric acid compound insolubilized by the flocculant, and solid solid phosphorus.
In the sludge solubilization tank 7, the acid is injected until a predetermined amount of acid is supplied by the acid supply device 8 or a predetermined value of 5 or less, preferably 2 or less, by the pH sensor provided in the sludge solubilization tank 7. .
This sludge solubilization tank 7 is provided with a stirrer and allowed to react for 1 hour or more with gentle stirring. At this time, if the inside of the tank is heated to a temperature of 30 ° C. or more, the sludge is solubilized. Promoted.
That is, the action of acid and temperature kills the microorganism, hydrolyzes part of the cell wall and cell membrane constituting the microorganism, and elutes the cytoplasm in the cell.
At this time, phosphorus taken into the microorganism is eluted into the solubilized sludge liquid, and the phosphate compound and solid phosphorus are dissolved in the liquid by the action of the acid.
[0025]
The total amount of the solubilized sludge D that has been solubilized for a predetermined time is sent to the first settling tank 9 for solid-liquid separation.
The solubilized and concentrated sludge F precipitated by this solid-liquid separation is mostly dead microorganisms, but when this is returned to the reaction tank 2 by the sludge transfer pump 5 or the like, the action of the enzyme secreted by the activated sludge microorganisms. Is gradually decomposed into carbon dioxide gas or the like.
[0026]
On the other hand, the separated liquid E in the first sedimentation tank 9 subjected to solid-liquid separation is transferred to the second sedimentation tank 11 by an overflow or a pump.
And during this transfer, when the alkaline agent is injected by the alkaline agent supply device 10 and the pH is raised to 3 or more, most of the dissolved phosphorus becomes solid again, and phosphoric acid is also a coagulant. Reacts with metal salts to become phosphate compounds and insolubilizes.
At this time, since the inorganic substance dissolved by the acid also returns to a solid substance as the pH rises, the sludge precipitated in the second settling tank 11 becomes sludge mainly composed of inorganic substances such as a phosphoric acid compound.
In addition, since the organic substance eluted by the solubilization process is contained in the separation liquid of the second precipitation tank 11, it is returned to the reaction tank 2 as the precipitation separation liquid G and biologically treated again with activated sludge. Do.
[0027]
Thus, in the activated sludge process or the membrane separation activated sludge method, the phosphorus removal method in the activated sludge treatment of the present embodiment is performed by adding a flocculant to the inflow portion to the reaction tank 2 or the final sedimentation tank 3 to obtain sewage Since the phosphoric acid is insolubilized, stable phosphorus removal performance equivalent to that of the conventional flocculant addition method can be obtained.
In addition, the sludge is extracted from the final sedimentation tank 3 or the reaction tank 2 and led to the sludge solubilization tank 7, and acid is added, and heat treatment is performed as necessary to promote solubilization, and then returned to the reaction tank 2. Since biological treatment is performed with activated sludge, the generated surplus sludge can be made almost zero.
Furthermore, in the sludge solubilization tank 7, the phosphorus eluted from the sludge and the dissolved phosphate compound are precipitated and separated as sludge H mainly composed of inorganic matter by adding an alkaline agent and adjusting the pH after precipitation separation. Because it separates, the amount of sludge discharged outside the site can be reduced to about 1/10 of the conventional activated sludge method, requiring less land for landfill disposal. Therefore, there is an effect that a problem such as generation of a bad odor does not occur.
[0028]
As described above, in the example, the sludge extracted from the final sedimentation tank 3 is solubilized in the flow composed of the reaction tank 2 and the final sedimentation tank 3, but further concentrated after precipitation in the final sedimentation tank 3, It is also possible to perform a solubilization treatment on the concentrated sludge.
Moreover, although the gravity type precipitation tank is used for solid-liquid separation, other solid-liquid separation apparatuses, such as centrifugation, can also be used.
Furthermore, instead of the final sedimentation tank 3, a membrane separation device (not shown) is provided in the reaction tank 2, and a membrane separation activated sludge method is used in which sewage is filtered by a membrane such as a microfiltration membrane or an ultrafiltration membrane. It is also possible to increase the sludge concentration by using a membrane and solubilize the sludge drawn directly from the reaction tank 2.
[0029]
【The invention's effect】
According to the method for removing phosphorus in the activated sludge treatment of the present invention, after adding a metal salt-based flocculant such as iron salt to the sewage at the inflow portion from the reaction tank or the reaction tank to the final sedimentation tank, phosphorus is insolubilized. In addition, acid is added to the sludge generated from the reaction tank to solubilize the sludge and elute phosphorus, and solid-liquid separation of the solubilized sludge is performed, and an alkaline agent is added to the separated liquid to insolubilize phosphorus again. Since the phosphorus is separated and discharged by solid-liquid separation of the insolubilized phosphorus in the separated liquid, the organic sludge is hardly discharged by returning the solubilized sludge to the reaction tank and performing biological treatment. At the same time, phosphorus eluted by acid can be insolubilized with alkaline agent and discharged as inorganic-based sludge containing phosphorus, thereby reducing the amount of sludge discharged off-site to about 10% of the conventional activated sludge method. While It is possible to realize the dephosphorization of water.
Furthermore, since the discharged sludge is mainly composed of inorganic substances, problems such as anaerobic rot and generation of bad odors do not occur even during temporary storage.
[0030]
In addition, sludge separated after solid-liquid separation after acid addition and separated liquid separated after solid-liquid separation by alkaline agent are returned to the reaction tank, so that the sludge separated after acid addition and phosphorus insolubilization of alkaline agent are added. The separated liquid separated later can be biologically treated with activated sludge in a reaction tank.
[0031]
In addition, by separating the sludge treated in the reaction tank into sludge and treated water by performing solid-liquid separation in the final sedimentation tank or membrane separator, the sludge to which acid is added can be obtained from the final sedimentation tank. Can be obtained directly from the reaction vessel.
[0032]
Furthermore, by adding an acid to make the pH of the sludge 2 or less and adding an alkaline agent to make the pH of the separation liquid 3 or more, the solubilization performance of the sludge is improved and phosphorus is eluted efficiently, Thereafter, phosphorus can be insolubilized.
[0033]
And the solubilization performance of sludge can be improved by performing the heat processing for 30 hours or more with respect to the sludge which added the acid for 1 hour or more.
[Brief description of the drawings]
FIG. 1 is a flow diagram of sewage treatment showing an embodiment of a phosphorus removal method in activated sludge treatment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pretreatment equipment 2 Reaction tank 3 Final sedimentation tank 4 Coagulant supply apparatus 5 Sludge transfer pump 6 Sludge input pump 7 Sludge solubilization tank 8 Acid supply apparatus 9 1st sedimentation tank 10 Alkaline agent supply apparatus 11 2nd sedimentation tank 12 Sludge Discharge Pump 13 Sludge Concentrated Reservoir A Sewage B Treated Water C Precipitated Sludge D Solubilized Sludge E Separation Fluid F Solubilized Concentrated Sludge G Precipitate Separation Fluid H Discharged Sludge I Storage Sludge
Claims (5)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001219795A JP3823222B2 (en) | 2001-07-19 | 2001-07-19 | Phosphorus removal method in activated sludge treatment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001219795A JP3823222B2 (en) | 2001-07-19 | 2001-07-19 | Phosphorus removal method in activated sludge treatment |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2003024968A JP2003024968A (en) | 2003-01-28 |
| JP3823222B2 true JP3823222B2 (en) | 2006-09-20 |
Family
ID=19053727
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2001219795A Expired - Fee Related JP3823222B2 (en) | 2001-07-19 | 2001-07-19 | Phosphorus removal method in activated sludge treatment |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3823222B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR101141928B1 (en) * | 2011-10-19 | 2012-05-14 | 코오롱워터앤에너지 주식회사 | A sewage or wastewater treatment apparatus and method using phosphorus collection and recycling coagulant |
-
2001
- 2001-07-19 JP JP2001219795A patent/JP3823222B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JP2003024968A (en) | 2003-01-28 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP2000000592A (en) | Treatment of organic waste water | |
| KR101099869B1 (en) | Method and apparatus for treating anaerobic digestive fluid | |
| JP5128735B2 (en) | Recovery and reuse of phosphorus and flocculant in wastewater | |
| CN107055963A (en) | The efficient advanced treatment apparatus of percolate and processing method | |
| CN106830559A (en) | A kind of waste water of heat-engine plant treatment and reclaiming system and method | |
| JP3823222B2 (en) | Phosphorus removal method in activated sludge treatment | |
| JP4124902B2 (en) | Wastewater treatment equipment | |
| CN100395192C (en) | Treatment method of waste water arising from process of extracting ganglioside from animal brain tissue | |
| JPS6254075B2 (en) | ||
| JP2002059190A (en) | Method of treating sewage and sludge | |
| JP3511430B2 (en) | Organic wastewater treatment method | |
| JP2007050386A (en) | Apparatus for treating organic waste liquor | |
| JP2002059200A (en) | Method of treating sewage and sludge | |
| JP2000263091A (en) | Sewage and sludge treatment method | |
| JP2000296399A (en) | Waste water treating apparatus | |
| JP2001149981A (en) | Method for treating sewage and sludge | |
| JP4161113B2 (en) | Sludge treatment method | |
| JP2000084596A (en) | Treatment of sludge | |
| JP2006122861A (en) | Apparatus for treating organic waste water | |
| JP3707272B2 (en) | Sewage treatment method and apparatus | |
| JP3832808B2 (en) | Method for recovering phosphorus in sludge | |
| JP2004167368A (en) | Sludge treatment method | |
| JP2004351354A (en) | Sludge treatment method | |
| JPS62250997A (en) | Treatment of sewage | |
| JP2004188256A (en) | Method of treating sewage and sludge |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20040608 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20050712 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20050726 |
|
| A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20050926 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20060104 |
|
| A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20060124 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20060516 |
|
| A711 | Notification of change in applicant |
Free format text: JAPANESE INTERMEDIATE CODE: A712 Effective date: 20060613 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20060613 |
|
| R150 | Certificate of patent or registration of utility model |
Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| S531 | Written request for registration of change of domicile |
Free format text: JAPANESE INTERMEDIATE CODE: R313531 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090707 Year of fee payment: 3 |
|
| R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090707 Year of fee payment: 3 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100707 Year of fee payment: 4 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100707 Year of fee payment: 4 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110707 Year of fee payment: 5 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120707 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120707 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130707 Year of fee payment: 7 |
|
| LAPS | Cancellation because of no payment of annual fees |