JP2004097932A - Water treatment apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the treatment capacity of water to be treated in a water treatment apparatus. <P>SOLUTION: An electrolytic tank 100 for removing nitrogen is equipped with a membrane 108, an aeration pipe 109 and a pump 109P for sending air to the aeration pipe 109. A flocculation tank 600 is equipped with a flocculant tank 601 for housing a flocculant to be introduced into the flocculation tank 600, a pump 602 for sending the flocculant in the flocculant tank 601 to the flocculation tank 600, a membrane 603 for separating a solid component in water to be treated discharged from the flocculation tank 600, an aeration pipe 604 and a pump 604P for sending air to the aeration pipe 604. As the flocculant, a biodegradable polymer such as a ferrous compound such as iron polysulfate, an aluminum compound such as aluminum polychloride, polyglutamic acid, or the like, is designated. The water to be treated introduced into the electrolytic tank 100 is discharged through a phosphorus removing electrolytic tank 59, the flocculation tank 600 and a sedimentation tank 190. <P>COPYRIGHT: (C)2004,JPO

Description

【００６６】
電解槽１００内の被処理水中では、塩化ナトリウムが添加されることにより、上記した式（２），（３）の平衡が成立っている。また、電極１０３近傍では、上記の式（４）〜（６）に示すように、水の電気分解により酸素ガスが発生し、塩素イオンは塩素ガスとなり、塩素ガスの一部は水和して次亜塩素酸となる。また、電極１０４近傍では、上記した式（７），（８）に示すように、水の電気分解により水素ガスが発生し、ナトリウムイオンが水酸化物イオンと反応して水酸化ナトリウムが生成される。これにより、電極１０４近傍は、被処理水がアルカリ性となる。
【００６７】
そして、電解槽１００内に導入された被処理水中の硝酸イオンは、電極１０４表面で、亜硝酸イオンを経て、アンモニアに還元される（式（９）〜式（１１）参照）。なお、電極１０４がアルミニウムや亜鉛等の両性金属を含む場合には、当該両性金属が強アルカリ性で電極１０４から溶出するときに生成される電子も、式（１１）において硝酸イオンの還元に使われると考えられる。また、硝酸イオンは、電極１０４上において還元されて直接窒素ガスとなる場合がある。
【００６８】
上記のように生成したアンモニアは、上記のように生成した次亜塩素酸と結合して、以下の式（１２）〜（１４）のようにクロラミン類を生成する。また、生成したクロラミン類は、式（１５），（１６）のように、窒素ガスや一酸化二窒素に変換される。
【００６９】
【数２】

【００７０】
また、上記のように電極１０４から溶出したアルミニウム（以下の式（１７）参照）は、式（１８）に示すように、アルミニウムイオンとして被処理水中の水酸化物イオンと反応して水酸化アルミニウムとなったり、式（１９）に示すように、アルミン酸としてナトリウムイオンと反応しアルミン酸ナトリウムとなる。
そして、生成したこれらの化合物によって、水中のコロイド（水中のＳＳ（Ｓｕｓｐｅｎｄｅｄ　Ｓｏｌｉｄｓ）成分で粒径１〜０．０１×１０^−６ｍ程度の微細なもの）の電荷が中和され、粒子間の引力が働き、やがてフロックになり沈降する。
【００７１】
【数３】

【００７２】
さらに、電極１０４から溶出したアルミニウムイオンは、以下の式（２０）に示すように、被処理水中のリン酸イオンと反応して、水に不溶性なリン酸アルミニウムとなり、沈降する。これにより、アルミニウムイオンによって、被処理水中のリン酸成分を除去できる。なお、本実施の形態では、陰極で、アルミニウムに代表される、リン酸成分およびＳＳ成分を除去できる金属を溶出させるため、陽極でこれを溶出させる場合よりも、このような金属が電極付近で不動態化することを回避できる。
【００７３】
【数４】

【００７４】
本実施の形態では、電極１０４が、デバルダ合金のように、銅を主成分とし、銅よりもイオン化傾向の高い金属を含む合金によって構成された場合には、特に、硝酸イオンの還元が促進される。なお、被処理水中の窒素酸化物および／またはリン酸を除去を除去することのみを目的とするのであれば、電極１０４は、アルミニウム等の両性金属、当該電極１０４内の成分が溶出し、電解槽１００内の陰イオンと反応して凝集剤として作用する化合物であって水に不溶性の化合物を生成する金属、または、酸化されてリン酸イオンと反応することにより水に不溶性の化合物を生成する金属の単体で構成されてもよい。
【００７５】
図４に、固液分離装置１３０の一例を示す。
固液分離装置１３０には、その底部付近に、分離膜１３０Ａが備えられている。分離膜１３０Ａは、固液分離装置１３０内を上下に完全に仕切るものである。
【００７６】
固液分離装置１３０の上方には、電解槽１００へと被処理水を送る排出口１１５が設けられている。排出口１１５は、ポンプ１３１が接続されている。
【００７７】
固液分離装置１３０内では、導かれた被処理水内の固体成分は、分離膜１３０Ａを通りぬけることができない。これにより、固液分離装置１３０からは、固体成分を除かれた被処理水が、電解槽１００に送られることになる。
【００７８】
固液分離装置１３０の底部は、ホッパー型であり、弁１３０Ｃの開閉を適宜制御回路１２０に制御されることにより、当該底部の排出口１３０Ｂより、沈殿物等の固体成分が排出される。
【００７９】
次に、電極１０３，１０４により構成される電極対１０１の構造について、より詳細に説明する。図５は、当該電極対の斜視図である。
【００８０】
図５を参照して、電極対を構成する電極１０３，１０４は、電極支持部１０１Ａ，１０１Ｂに取付けられている。電極支持部１０１Ａ，１０１Ｂは、後述するように、それぞれ電極１０３，１０４を支持し、かつ、互いに組合されている。
電極支持部１０１Ａ，１０１Ｂの上部からは、電極１０３，１０４を制御回路１２０に接続する配線１０１Ｘが延びている。
【００８１】
図６に、電極１０３，１０４および電極支持部１０１Ａ，１０１Ｂの構造を示す。また、図７に、電極１０３，１０４および電極支持部１０１Ａ，１０１Ｂが、電解槽１００上に取付けられるために組合わされた状態を側方から見た図を示す。
【００８２】
電極１０３，１０４は、それぞれ、電極支持部１０１Ａ，１０１Ｂに取付けられている。電極支持部１０１Ａ，１０１Ｂは、電極１０３，１０４の上部に位置し、電解槽１００内の処理水には、浸らないように、適宜支持されている。
【００８３】
図６および図７を参照して、電極１０３，１０４は、それぞれ、その上部を、電極支持部１０１Ａ，１０１Ｂにネジ止されている。電極支持部１０１Ａには、電極支持部１０１Ｂと対向すべき面に、スペーサ１０１Ｃが取付けられている。
そして、電極支持部１０１Ａと電極支持部１０１Ｂは、図７に示すように、スペーサ１０１Ｃを介して、対向するように組合わされ、固定される。スペーサ１０１Ｃの巾を適宜調整することにより、電極１０３と電極１０４の距離が調整される。
【００８４】
ここで、電極支持部１０１Ａ，１０１Ｂの構成を説明する。図８は、電極支持部１０１Ａの斜視図である。電極支持部１０１Ａは、直流電源１０５と電極１０３とを接続させるための配線を内包している。当該配線の一端は、コネクタ１０１０であり、他端は、コネクタ１０１１である。電極１０３は、電極支持部１０１Ａにネジ止されることにより、コネクタ１０１０に、電気的に接続される。また、コネクタ１０１１は、直流電源１０５に、電気的に接続される。これにより、電極１０３は、電極支持部１０１Ａにネジ止されることにより、直流電源１０５と、電気的に接続される。また、電極支持部１０１Ｂも、電極支持部１０１Ａと同様に、２つのコネクタを有し、配線を内包している。そして、電極１０４は、電極支持部１０１Ｂにネジ止されることにより、直流電源１０５と、電気的に接続される。
【００８５】
電極１０３，１０４および電極支持部１０１Ａ，１０１Ｂがこのように構成されるため、電極１０３，１０４と電源装置３８を結ぶ配線が、処理水内に横たわることを回避でき、また、これらの接続部であるコネクタが、処理水内に浸され腐食することを回避できる。
【００８６】
図９に、電極１０３，１０３の、電極支持部１０１Ａ，１０１Ｂへの取付態様を説明するための図を示す。
【００８７】
電極支持部１０１Ａには、電極１０３の上部を嵌め込むことができる切り欠き部１０１Ｅが形成されている。また、電極支持部１０２Ａにも、同様の切り欠き部が形成されている。電極１０３，１０４は、それぞれ切り欠き部に、その上部を嵌め込まれ、ネジ止される。これにより、電解槽１００内での電極１０３，１０４の位置がより確実に固定されるため、電解槽１００内で電極反応の起こる位置が安定する。
【００８８】
電極支持部１０１Ａ，１０１Ｂと電極１０３，１０４とが、ユニット化されて輸送される場合、図１０に示すように、ケースに収納されて輸送されることが好ましい。詳しくは、ユニット化された電極支持部１０１Ａ，１０１Ｂと電極１０３，１０４は、電極１０３，１０４部分がケース１０２０の内部に収まるように、ケース１０２０と組合される。なお、組合される際に、電極支持部１０１Ａ，１０１Ｂは、ケース１０２０に、ネジ１０２Ａ，１０２Ｂによりネジ止される。
【００８９】
図１１に、電解槽１００内の電解反応を模式的に示す。
電極１０３，１０４は、直流電源１０５により通電される。そして、電極１０３，１０４の一方をカソード電極とし他方をアノード電極として通電された場合、アノード側では、被処理水中に存在するハロゲンイオン（図１１では塩化物イオン）が酸化され、ハロゲンガス（塩化物イオンが酸化された場合は塩素）が生成された後、当該ガスが被処理水中の水と反応して次亜塩素酸が生成される。一方、カソード側では、被処理水中の窒素成分（被処理水中の有機系窒素化合物等）が硝酸イオンに変換され、さらに、硝酸イオンがアンモニウムイオンに変換される。そして、このように電気化学的に生成された次亜塩素酸とアンモニウムイオンが反応することにより、窒素成分は、クロラミン類を経て、窒素ガスに変換される。本実施の形態では、電極１０３，１０４へは、互いに反対の極性の電位が与えられるが、当該極性は、交換可能とされている。したがって、電極１０３，１０４の一方を鉄を含む材料によって構成された場合には、当該鉄を含む電極を、あるときは、カソード側電極として、硝酸イオンを還元する電極として利用でき、またあるときは、アノード側電極として、鉄イオンを溶出させる電極として利用できる。
【００９０】
また、図３および図１１には、電解槽１００内に、電極１０３，１０４からなる電極対１０１が１対だけセットされる状態が示されているが、これに限定されない。電極対１０１は、図１２に示されるように、複数、セットされてもよい。
【００９１】
次に、電解槽５９内の電極対５１の構成について、図１３および図１４を参照しつつ説明する。図１３は、電極対５１の斜視図である。また、図１４は、電極対５１を一部破断した場合の斜視図である。電極対５２は、電極対５１と同様の構成を有している。
【００９２】
電極対５１は、電極５１１，５１２の２枚の金属板を含む。該金属板は、たとえば、鉄やアルミニウムからなる。
【００９３】
また、電極対５１は、支持体５１０を含む。支持体５１０の上部には、取っ手５１０ａが取付けられている。支持体５１０の左側面には、カバー５１３が取付けられている。詳しくは、カバー５１３には６個のネジ孔が形成され、それぞれのネジ孔を所定のネジでネジ止されることにより、カバー５１３が支持体５１０の左側面に取付けられる。カバー５１３には、ナット５１１ａ，５１１ｂにより、電極５１１が取付けられる。なお、上記したネジ孔には、ネジ孔５１３ａ，５１３ｂ（図１５参照），５１３ｃ，５１３ｄ，５１３ｅが含まれる。また、上記した所定のネジには、図１５に示すネジ５１７ａ，５１７ｂ，５１７ｃ，５１７ｄが含まれる。
【００９４】
支持体５１０の上部後方には、ガイド５１９ｄが取付けられ、ガイド５１９ｄから支持体５１０の上方に向けて、配線５１９が突出している。ガイド５１９ｄは、円筒状であり、配線５１９は、ガイド５１９ｄの内部に通されている。配線５１９の一端には、電源５７に接続するためのコネクタ５１９ｃが接続されている。配線５１９の、ガイド５１９ｄより先（下方）にある部分から他端までは、支持体５１０とカバー５１３が組合されたものに内蔵される。なお、配線５１９は複数の配線（後述する配線５１９ａを含む）を内包している。そして、配線５１９の他端は、内包された複数の配線のそれぞれに、後述する端子５１８（図１５参照）等の端子が取付けられた状態となっている。
【００９５】
ここで、図１５および図１６に、電極対５１の、部分的な、一部破断された、分解斜視図を示す。なお、図１６では、便宜上、配線５１９、コネクタ５１９ｃ、配線５１９ａおよび端子５１８を省略している。
【００９６】
図１５および図１６をさらに参照して、カバー５１３と支持体５１０との間には、鉄やステンレス等からなる電極固定用治具５１５，５１６が備えられている。電極固定用治具５１５，５１６は、導伝体であって、腐食しにくい材料で構成されることが好ましい。
【００９７】
電極固定用治具５１５は、突起部５１５ａ，５１５ｂを形成された板体である。突起部５１５ａ，５１５ｂは、カバー５１３に形成された孔を貫通できるように構成されている。電極５１１は、ナット５１１ａ，５１１ｂにより、突起部５１５ａ，５１５ｂと電気的に接続されるように、取付けられる。
【００９８】
支持体５１０の中央よりやや後方であって、電極固定用治具５１５と電極固定用治具５１６との間には、端子５１８が備えられている。端子５１８は、配線５１９ａの末端を構成している。配線５１９ａは、配線５１９に内包される複数の配線の中の一つである。
【００９９】
端子５１８は、電極固定用治具５１５がカバー５１３に取付けられ、かつ、カバー５１３が支持体５１０に取付けられたときに、突起部５１５ａと接触する位置に配置されている。これにより、電極５１１は、突起部５１５ａを介して、端子５１８と、電気的に接続される。
【０１００】
なお、電極固定用治具５１６にも、突起部５１５ａ，５１５ｂと同様の突起部が形成されている。該突起部は、支持体５１０の左側面上に突出している。また、支持体５１０の中央よりやや前方であって、電極固定用治具５１５と電極固定用治具５１６との間には、端子５１８とは別の端子が備えられている。ここで言う別の端子は、配線５１９に内包される複数の配線の中の、配線５１９ａとは別の配線の末端を構成している。そして、この別の端子は、電極固定用治具５１６に形成された突起部に電気的に接続され、該突起部は、電極５１２に接続される。これにより、該別の端子と電極５１２が、電気的に接続される。
【０１０１】
図示は省略したが、電極固定用治具５１５と電極固定用治具５１６との間であって該端子と端子５１８の間には、絶縁体が備えられている。これにより、支持体５１０とカバー５１３が組合されたものの内部で、電極５１１と電極５１２が短絡することを、確実に回避できる。
【０１０２】
電極固定用治具５１５は、ネジ５１４ａ〜５１４ｃにより、カバー５１３にネジ止される。また、電極固定用治具５１６は、ネジ５１４ｄ〜５１４ｆにより、支持体５１０にネジ止される。
【０１０３】
支持体５１０とカバー５１３の間であって、カバー５１３がネジ止される場所よりも外側には、パッキン５１０ｂが設けられている。また、支持体５１０と電極固定用治具５１６の間であって、電極固定用治具５１６がネジ止される場所よりも外側には、パッキン５１０ｃが設けられている。さらに、カバー５１３と電極固定用治具５１５の間であって、電極固定用治具５１５がネジ止される場所よりも外側には、パッキン５１０ｃと同様のパッキンが設けられている。
【０１０４】
これにより、支持体５１０とカバー５１３とが組合された場合、支持体５１０とカバー５１３は、内部に水が入らないように、端子５１８および上記の別の端子を内蔵できる。
【０１０５】
図２に示したタンク１内では、電解槽５９は、接触バッキ槽１４に設けられている。なお、電解槽５９は、第一嫌気漏床槽５、第二嫌気漏床槽１０、または、沈殿槽１９のように、タンク１内の他の槽に設けられても良い。さらに、電解槽５９は、タンク１の外に、流入口６や排水口２３に隣接するように、設けられても良い。
【０１０６】
また、本実施の形態の電解槽５９は、電極対５１，５２が、ケース５４に囲まれている。なお、電解槽５９において、ケース５４を、底を有し、該底に弁を有するような槽とすることもできる。ここで、弁は、槽外へ、槽内で生じる不溶性の沈殿物を排出するために設けられる。このような槽内に、電極対５１，５２が設置されることにより、電極対５１，５２における電解反応が他の槽（第一嫌気漏床槽５等）の汚泥に阻害されることを回避できる。
【０１０７】
なお、タンク１の循環流量は、３Ｑである。なお、Ｑとは、タンク１に流入する水量である。つまり、タンク１内では、流入する水量の３倍の水量が、循環される。
【０１０８】
また、電極対５１，５２における電解反応は、溶出する鉄イオンまたはアルミニウムイオンの濃度が、処理水中のリンのモル濃度の１〜３倍となるように、行なわれる。なお、上記の電解反応は、鉄イオンまたはアルミニウムイオンの濃度が、好ましくは、処理水中のリンのモル濃度の１〜２倍程度、さらに好ましくは、１．５倍程度になるように、制御される。このために、電解反応において、電極における電流密度は、０．１ｍＡ／ｃｍ^２　以上になるように制御され、多くの場合、０．３ｍＡ／ｃｍ^２　程度となるように制御される。
【０１０９】
このように、電極における電流密度が制御されることにより、電極表面の酸化物皮膜や有機性付着物の生成を防止でき、かつ、これらを除去できると考えられる。アノード側の電極で生成されると考えられる水酸化鉄や有機性付着物を、カソード側で発生する水素ガスや第三散気管５３によるバッキによって除去できると考えられるからである。したがって、上記の電解反応における電流密度が低すぎる場合は、カソード側で発生する水素ガス量が低く、十分に、アノード側の付着物を除去できないと考えられる。なお、電解槽５９における、第三散気管５３のバッキ量は、１５Ｌ／ｍｉｎ程度とされる。
【０１１０】
たとえば、一日にタンク１に流入される生活排水の量を１２００Ｌとし、タンク１内の各槽における循環流量を６０００Ｌとした場合、電極５１１，５１２および電極対５２を構成する電極に流される電流は６５０ｍＡ程度に制御される。
各電極における電流密度は、各電極の浸水面積を変化させることにより、制御できる。また、電極５１１と電極５１２の間隔は２５ｍｍ程度にされ、電極間の電圧は常にモニタされる。また、各電極の極性は、所定時間（たとえば２４時間）ごとに反転させることが好ましい。
【０１１１】
また、電極５１１，５１２の一方は、不溶性金属電極からなる。また、その他方は、周期表ＶＩＩＩ族の金属、好ましくは鉄、を含む導電体からなる。
【０１１２】
また、本実施の形態では、図１および図２から理解されるように、電解槽１００は、タンク１の後段に、つまり、２次処理後の被処理水が導入されるように、設置されていた。このように、被処理水の３次処理用の装置として電解槽１００を利用する際の処理の流れとして、図１７（Ｂ），（Ｃ）に、その変形例を示す。なお、図１７（Ａ）は、図１７（Ｂ），（Ｃ）の処理の流れの一部分を示している。
【０１１３】
図１７（Ａ）および図１７（Ｂ）を参照して、この例では、まず、被処理水は、工程２００において、嫌気性処理および好気性処理がなされる。
【０１１４】
工程２００での処理とは、図１７（Ａ）に示される工程での処理である。具体的には、嫌気ろ床槽２０１で処理された被処理水が、接触ばっ気槽２０２に送られる。接触ばっ気槽２０２での処理後の被処理水は、一部が剥離汚泥と共に嫌気ろ床槽２０１に返送され、一部は沈殿槽２０３に送られる。沈殿槽２０３内の被処理水は、一部は、沈殿汚泥と共に接触ばっ気槽２０２に返送されるが、一部は、次の工程へと送られる。
【０１１５】
そして、図１７（Ｂ）を参照して、工程２００での処理後の被処理水は、接触ばっ気槽２１０に送られる。当該接触ばっ気槽２１０の処理水は、沈殿槽２１１に送られる。なお、接触ばっ気槽２１０の剥離汚泥は、別途設けられた、沈殿槽、汚泥濃縮貯留槽、汚泥濃縮設備等に送られる。沈殿槽２１１の被処理水は、一部は、沈殿汚泥と共に、嫌気ろ床槽２０１（図１７（Ａ）参照）に送られ、一部は、砂ろ過原水槽２１２に送られた後、砂ろ過装置２１３に送られる。
【０１１６】
砂ろ過装置２１３で生じた洗浄排水は、リン除去用の電解槽２１４に送られた後、嫌気ろ床槽２０１に（図１７（Ａ）参照）返送される。砂ろ過装置２１３のろ過後の被処理水は、砂ろ過処理水槽２１５に送られた後、消毒槽２１６で消毒され、窒素除去用の１００で処理された後、施設外に放流される。
【０１１７】
次に、図１７（Ａ）および図１７（Ｃ）を参照して、図１７（Ｂ）の変形例について説明する。
【０１１８】
この例でも、まず、被処理水は、工程２００において、嫌気性処理および好気性処理がなされる。そして、工程２００における処理後の被処理水は、中間流量調整槽２２０，凝集槽２２１，凝集沈殿槽２２２，リン除去用の電解槽２２３を循環される。なお、リン除去用の電解槽２２３の被処理水は、工程２００内の嫌気ろ床槽２０１に送られる。凝集沈殿槽２２２内の上澄みは、消毒槽２２４に送られた後、窒素除去用の電解槽１００で処理された後、施設外に放流される。
【０１１９】
また、以上説明した本実施の形態では、電解槽１００では、所定時間ごとに被処理水を入れ替えるようにして、電解処理を行なわれてもよい。また、電解槽１００では、電解槽１００内の被処理水の硝酸イオン濃度および／またはリン酸イオン濃度を検知し、これらの濃度が予め定められた値を下回った時点で、制御回路１２０が弁１１０Ａ，１１１Ａ，１１３Ａを適宜開閉し、電解槽１００内の被処理水を入替えられて、電解処理が行なわれても良い。
【０１２０】
［第２の実施の形態］
図１８は、本発明の第２の実施の形態である水処理装置を含む水処理システムを構成する装置の模式的な縦断面図である。
【０１２１】
電解槽１００は、図２に示したようにタンク１の外に設置されても良いし、図１８に示すようにタンク１内に設置されても良い。
【０１２２】
なお、電解槽１００がタンク１内に設置される際には、電極１０３，１０４の間に流す電流値の制御は、電解槽１００内の、ハロゲンイオン濃度および次亜ハロゲン酸イオン濃度、または、ｐＨ値に基づいて行なわれる必要がある。
【０１２３】
第１の実施の形態において、式（３）、式（６）等を用いて説明したように、電解槽１００内には、ハロゲンイオンや次亜ハロゲン酸イオンが生成される。これらのイオンは、高濃度になれば、タンク１内の微生物に対して悪影響を及ぼすことが考えられる。
【０１２４】
このことから、本実施の形態では、電解槽１００内のハロゲンイオン濃度および次亜ハロゲン酸イオン濃度が所定の濃度を越えないように、または、ｐＨが所定の値を下回らないように、電極１０３，１０４の間に流される電流値が制御される。
【０１２５】
電解槽１００が図１８に示すようにタンク１内に設置された場合、図１に示した処理工程は、図１９（Ａ）に示すものに変更されることになる。また、図１７（Ｂ），（Ｃ）に示した工程において、電解槽１００をタンク１内に設置すると、それぞれの工程は、図１９（Ｂ），（Ｃ）に示された工程に変更されることになる。
【０１２６】
［第３の実施の形態］
本実施の形態の水処理装置は、電解槽１００がタンク１の外部等に取付けられた場合に、当該電解槽１００から、改めて設けられた沈殿槽１９０を介して、外部に排出されるものである。
【０１２７】
本実施の形態では、図２０に示すように、電解槽１００には、導入口１１０から被処理水を導入される。電解槽１００内には、電極１０３，１０４が、被処理水に浸されている。電解槽１００の被処理水は、側部の排出口１１４から沈殿槽１９０に導入される。なお、電解槽１００の底部には、排出口１１７が形成されている。排出口１１７は、バルブ１１７Ａにより開閉される。本実施の形態の電解槽１００では、排出口１１７から、沈殿物等を外部へ排出できる。なお、バルブ１１７Ａの開閉は、制御回路１２０等、適宜設けられた制御部により、一定時間電極１０３，１０４への通電が行なわれるごと等に行なわれる。
【０１２８】
沈殿槽１９０には、分離膜１９０Ａが備えられている。沈殿槽１９０に導入された被処理水の大部分は、分離膜１９０Ａを通過して、外部に排出される。なお、沈殿槽１９０の底部には、当該沈殿槽１９０内で生じた沈殿物を排出するための排出口１９０Ｃが形成されており、排出口１９０Ｃは、バルブ１９０Ｂにより開閉される。バルブ１９０Ｂの動作も、制御回路１２０等の図示しない制御部により制御される。
【０１２９】
［第４の実施の形態］
本実施の形態の水処理装置は、図２１に示すように、第３の実施の形態の電解槽１００と沈殿槽１９０との間に、凝集槽６００が備えられたものである。
【０１３０】
図２１を参照して、本実施の形態では、電解槽１００には、ＳＳ成分や沈殿物等を電極１０３等に近づけないようにするための膜１０８、電解槽１００内に気泡を発することにより攪拌等を行なうためのバッキ管１０９、および、バッキ管１０９に空気を送るためのポンプ１０９Ｐが備えられている。また、凝集槽６００には、当該凝集槽６００内に導入する凝集剤を収容する凝集剤タンク６０１、導入剤タンク６０１内の凝集剤を凝集槽６００内に送るポンプ６０２、凝集槽６００から排出する被処理水内の固形成分を分離するための膜６０３、凝集槽６００内に気泡を発することにより攪拌等を行なうためのバッキ管６０４、および、バッキ管６０４に空気を送るためのポンプ６０４Ｐが備えられている。
【０１３１】
電解槽１００内に導入された被処理水は、電解処理を施された後、凝集槽６００に送られる。凝集槽６００では、凝集剤タンク６０１から凝集剤を添加されることにより、被処理水から、リン酸成分をリン化合物として凝集させ、除去できる。凝集剤としては、ポリ硫酸鉄等の鉄系化合物、ポリ塩化アルミニウム等のアルミニウム系化合物、ポリグルタミン酸等の生分解性高分子を挙げることができる。そして、凝集槽６００内の上澄み液が沈殿槽１９０に送られ、沈殿槽１９０から、外部に放出される。
【０１３２】
［第５の実施の形態］
本実施の形態の水処理装置は、図２２に示すように、第４の実施の形態の凝集槽６００の代わりに、リン除去用の電解槽５９が備えられたものである。本実施の形態では、電解槽１００内に導入された被処理水は、電解槽５９に送られた後、沈殿槽１９０に送られて、そして、外部に放出される。なお、本実施の形態では、リン除去用の電解槽５９に、凝集剤タンク６０１から凝集剤が添加される。
【０１３３】
［第６の実施の形態］
本実施の形態の水処理装置は、図２３に示すように、第４の実施の形態の電解槽１００と凝集槽６００の間に、リン除去用の電解槽５９が追加さられたものである。凝集槽６００が備えられているため、本実施の形態の電解槽５９では、第５の実施の形態の電解槽５９のように、凝集剤は添加されない。
【０１３４】
本実施の形態の水処理装置では、電解槽１００内に導入された被処理水は、電解槽５９に送られ、凝集槽６００に送られ、そして、沈殿槽１９０に送られて、外部に放出される。
【０１３５】
［第７の実施の形態］
本実施の形態の水処理装置では、電解槽１００内にセットされる電極およびその制御態様に特徴を有する。本実施の形態の電解槽１００内では、図２４に示すように、円柱状の電極９０１の周りに、複数枚の板状の電極９０２〜９０５が設置されている。
【０１３６】
図２５に、水処理装置の制御ブロック図の中の、電極９０１〜９０５の制御に関連のある部分のみを示す。
【０１３７】
電極９０１〜９０５は、直流電源９００から電力を供給される。直流電源９００は、制御部９１０によって動作を制御される。電極９０１は、不溶性の金属電極によって構成される。電極９０２〜９０５は、鉄を含む合金から構成される。
【０１３８】
電極９０１は、アノード電極とされる。また、電極９０２は、カソード電極とされる。そして、電極９０３〜９０５は、アノード電極とされる場合もあれば、カソード電極とされる場合もある。
【０１３９】
制御部９１０は、電解槽１００内のリン濃度を検知するリン濃度センサ９２０および電解槽１００内の窒素濃度を検知する窒素濃度センサ９３０の検知出力を参照できる。そして、制御部９１０は、リン濃度が当該リン濃度についての所定値よりも高く、窒素濃度が当該窒素濃度についての所定値よりも低い場合には、電解槽１００においてリン除去を重点的に行なえるように、電極９０３〜９０５の中でアノード電極とされる電極がより多くなるように、直流電源９００を制御する。これらの電極をアノード電極として、より多くの鉄イオンを溶出させるためである。
【０１４０】
また、制御部９１０は、電解槽１００内のリン濃度および／または窒素濃度に応じて、電極９０１〜９０５に流す電流値を制御する。これにより、リン濃度および／または窒素濃度に応じて、電解によるリン除去および／または窒素除去の能力を調節できるとともに、特に電極９０１〜９０５がアノード電極とされた際に、必要以上に電極を溶出させず電極の長寿命化を図ることもできる。
【０１４１】
一方、制御部９１０は、リン濃度が当該リン濃度についての所定値よりも低く、窒素濃度が当該窒素濃度についての所定値よりも高い場合には、電解槽１００において窒素除去を重点的に行なえるように、電極９０３〜９０５の中でカソード電極とされる電極がより多くなるように、直流電源９００を制御する。これらの電極をカソード電極として、より多くの窒素酸化物を還元させるためである。
【０１４２】
なお、電極９０３〜９０５のいずれかがアノード電極とされた際には、他のカソード電極とされた電極と図２６に示すように対向させることが好ましい。なお、図２６では、電極９０３，９０５がアノード電極とされ、電極９０４がカソード電極とされた場合の好ましい配置を示している。
【０１４３】
今回開示された各実施の形態はすべての点で例示であって制限的なものではないと考えられるべきである。本発明の範囲は上記した説明ではなく特許請求の範囲によって示され、特許請求の範囲と均等の意味および範囲内でのすべての変更が含まれることが意図される。なお、各実施の形態は、単独でも、また、可能な限り組合せても、適用することができる。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態である水処理装置を含む水処理システムの処理工程を模式的に示す図である。
【図２】図１の処理工程を具体化した家庭用合併浄化槽の模式的な縦断面図である。
【図３】図１の窒素除去用の電解槽の構造を模式的に示す図である。
【図４】図３の固液分離装置の一例を示す図である。
【図５】図３の電極対の斜視図である。
【図６】図３の電極および電極支持部の構造を示す図である。
【図７】図６の電極および電極支持部が、電解槽上に取付けられるために組合わされた状態を側方から見た図である。
【図８】図３の電極支持部の斜視図である。
【図９】図３の電極の、電極支持部への取付態様を説明するための図である。
【図１０】図３の電極および電極支持部がケースに収納される状態を示す図である。
【図１１】図３の電解槽内の電解反応を模式的に示す図である。
【図１２】図３の電解槽内で、複数の電極対が備えられる状態を示す図である。
【図１３】図１のリン除去用の電解槽内の電極対の構成を説明するための図である。
【図１４】図１のリン除去用の電解槽内の電極対の構成を説明するための図である。
【図１５】図１３の電極対の、部分的な、一部破断された、分解斜視図である。
【図１６】図１３の電極対の、部分的な、一部破断された、分解斜視図である。
【図１７】図１に示した被処理水に対する処理の流れの変形例を示す図である。
【図１８】本発明の第２の実施の形態である水処理装置を含む水処理システムを構成する装置の模式的な縦断面図である。
【図１９】図１８の水処理システムにおける被処理水に対する処理の流れ、および、その変形例を示す図である。
【図２０】本発明の第３の実施の形態である水処理装置を模式的に示す図である。
【図２１】本発明の第４の実施の形態である水処理装置を模式的に示す図である。
【図２２】本発明の第５の実施の形態である水処理装置を模式的に示す図である。
【図２３】本発明の第６の実施の形態である水処理装置を模式的に示す図である。
【図２４】本発明の第７の実施の形態である水処理装置の、電解槽における電極の配置を示す図である。
【図２５】図２４の電極の制御に関する制御ブロック図である。
【図２６】図２４に示した電極の配列の変形例を示す図である。
【符号の説明】
１　タンク、５　第一嫌気ろ床槽、１０　第二嫌気ろ床槽、１４　接触ばっ気槽、１９，１９０　沈殿槽、５１，５２，１０１　電極対、５９，１００　電解槽、１０３，１０４　電極、１０５　直流電源、１２０　制御回路、６００　凝集槽。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a water treatment apparatus, and more particularly to a water treatment apparatus for treating wastewater or the like using a compound generated by electrolysis.
[0002]
[Prior art]
BACKGROUND ART Conventionally, a technique has been disclosed in which water to be treated such as wastewater is passed through an electrolytic cell, and the water to be treated is treated using a compound generated by electrolysis (Patent Documents 1 to 5). In these conventional techniques, nitrogen compounds such as nitrate nitrogen contained in water to be treated are oxidized or reduced by electrolysis, and hypohalous acid or halogen acid generated by electrolysis is generated by reduction of nitrate nitrogen or the like. By reacting with the ammonia or the like, and removing it from the water to be treated as nitrogen gas.
[0003]
In addition, Patent Documents 3 to 5 further describe a technique of adding an iron compound or forming an anode with iron or aluminum to coagulate and remove phosphorus and colloidal impurities in the water to be treated. ing.
[0004]
[Patent Document 1]
JP-A-8-155463
[0005]
[Patent Document 2]
JP-A-10-000473
[0006]
[Patent Document 3]
JP 2000-117259 A
[0007]
[Patent Document 4]
JP 2000-334465 A
[0008]
[Patent Document 5]
JP 2001-252667 A
[0009]
[Problems to be solved by the invention]
Heretofore, there has always been a demand for such a water treatment apparatus to have an improved treatment capacity for removing nitrogen compounds and phosphorus compounds.
[0010]
The present invention has been conceived in view of the above-described circumstances, and an object of the present invention is to improve the treatment capacity of water to be treated in a water treatment apparatus.
[0011]
[Means for Solving the Problems]
A water treatment apparatus according to an aspect of the present invention is configured to introduce water to be treated, an electrolytic cell including an electrode pair, and to introduce water to be treated treated in the electrolytic cell, and to perform coagulation for adding a flocculant. An agent addition tank and a sedimentation tank for introducing the water to be treated treated in the coagulant addition tank and sedimenting aggregates in the water to be treated are provided.
[0012]
According to one aspect of the present invention, after subjecting the water to be treated to a treatment such as nitrogen removal in an electrolytic cell, a flocculant addition tank can coagulate a phosphorus compound or the like, and the coagulated material is Can be settled in a settling tank. That is, aggregation and precipitation for removing phosphorus can be performed on the water to be treated in a tank different from the electrolytic tank.
[0013]
This makes it possible to reliably remove the phosphorus compounds and the like in the water to be treated and to suppress the accumulation of sludge and the like that may hinder the electrolytic reaction in the electrolytic cell. The water treatment capacity can be improved.
[0014]
In the water treatment apparatus of the present invention, the electrolytic cell includes a first electrolytic cell including the soluble electrode, an anode electrode including an insoluble metal electrode, and a copper alloy, iron, an iron alloy, or an insoluble metal electrode. And a second electrolytic cell having a cathode electrode.
[0015]
Thus, metal ions can be eluted from the electrode in the first electrolytic tank and reacted with the phosphorus compound in the water to be treated, and nitrogen oxides can be converted to ammonia in the second electrolytic tank.
[0016]
Further, in the water treatment apparatus of the present invention, it is preferable that the soluble electrode is iron, an iron alloy, aluminum, or an aluminum alloy.
[0017]
A water treatment apparatus according to another aspect of the present invention includes a first electrode formed of an insoluble metal electrode into which water to be treated is introduced, and an electrode provided with a polarity opposite to that of the first electrode. An electrolyzer comprising a second electrode made of a conductor containing a Group VIII metal, and a polarity inversion section for inverting the polarity applied to the first electrode and the second electrode.
[0018]
According to another aspect of the present invention, the second electrode reduces nitrogen oxides in the water to be treated when used as a cathode electrode, and elutes iron or aluminum ions when used as an anode electrode. It becomes a coagulant for the phosphorus compound in the water to be treated.
[0019]
This allows the water treatment apparatus to remove nitrogen and nitrogen oxides in the water to be treated, thereby improving the treatment capacity.
[0020]
A water treatment apparatus according to still another aspect of the present invention includes an anode electrode made of an insoluble metal electrode, and a copper alloy, iron, an iron alloy, or a cathode electrode made of an insoluble metal electrode, for treating water to be treated. It is characterized by including an electrolytic cell to be introduced.
[0021]
According to the present invention, nitrogen oxide is converted to ammonia by reducing it at the cathode electrode, and halogen acid or hypohalous acid can be generated from the halogen compound in the water to be treated at the anode electrode.
[0022]
Thereby, the water treatment apparatus can efficiently convert nitrogen oxides into gaseous nitrogen by reacting ammonia with halogen acid or hypohalous acid. That is, the processing capacity of the water treatment device is improved.
[0023]
A water treatment apparatus according to another aspect of the present invention includes an electrolytic cell including a plurality of electrodes which are made of an alloy including iron, and which is provided with polarities independently of each other, and a polarity control which controls polarities provided to the plurality of electrodes. And a part.
[0024]
According to another aspect of the present invention, iron ions constituting the coagulant of the phosphorus compound are eluted in the water to be treated when the anode electrode is used, and in the water to be treated when the cathode electrode is used. An iron electrode capable of reducing nitrogen oxides to ammonia can be selectively used as an anode electrode or a cathode electrode depending on the case.
[0025]
Thereby, in the water treatment apparatus, since the ratio between the ability of removing phosphorus and the ability of removing nitrogen of the water to be treated can be selectively exhibited, a high treatment capacity can be exhibited even if the content of the water to be treated changes. .
[0026]
Further, the water treatment apparatus of the present invention further includes a detection unit capable of detecting the amount of the phosphorus compound and the amount of the nitrogen oxide in the electrode tank, the polarity control unit, according to the detection output of the detection unit, It is preferable to control the polarity applied to each of the plurality of electrodes and the value of the current flowing through the plurality of electrodes.
[0027]
Further, it is preferable that the water treatment apparatus of the present invention further includes a water amount control unit for keeping the amount of water in the electrolytic cell constant.
[0028]
In the water treatment apparatus of the present invention, it is preferable that the electrolytic cell is of a hopper type, and has a drain valve at a bottom thereof.
[0029]
In the water treatment apparatus of the present invention, it is preferable that the electrolytic cell has a mechanism for discharging gas generated in the electrolytic cell to the outside.
[0030]
In addition, the water treatment apparatus of the present invention preferably further includes a separation unit installed in a flow path of the water to be treated in the electrolytic cell, for separating liquid and solid contained in the water to be treated. .
[0031]
In addition, the water treatment apparatus of the present invention preferably further includes a chlorine compound supply unit that supplies a chlorine compound into the electrolytic cell.
[0032]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same components are denoted by the same reference numerals, unless otherwise specified, and have the same names and functions. Therefore, detailed description thereof will not be repeated.
[0033]
Hereinafter, embodiments of the present invention will be described with reference to the drawings. The water treatment system shown below is mainly applied to large-scale wastewater treatment facilities that treat domestic wastewater and industrial wastewater. It can also be applied. Further, according to the water treatment apparatus described below, in particular, nitrogen compounds contained in domestic wastewater, wastewater of a plating factory, and the like can be removed from the water to be treated by electrolytic treatment.
[0034]
[First Embodiment]
FIG. 1 is a diagram schematically showing processing steps of a water treatment system including a water treatment apparatus according to a first embodiment of the present invention, and FIG. It is a typical longitudinal section of a merger septic tank.
[0035]
Referring to FIG. 1 and FIG. 2, the water treatment system according to the present embodiment mainly includes a tank 1 and an electrolytic cell 100. The tank 1 is buried underground. The inside of the tank 1 includes a first anaerobic filter bed tank 5, a second anaerobic filter bed tank 10 and a contact aeration by a first partition wall 2, a second partition wall 3, a third partition wall 4, and a fourth partition wall 20. It is divided into a tank 14, a sedimentation tank 19 and a disinfection tank 21. The upper part of the tank 1 is covered with a plurality of manholes 28. Further, members inside the tank 1 are connected to members (the third blower 30 and the like) outside the tank 1. In FIG. 2, members outside the tank 1 such as the third blower 30 are described above the tank 1 for convenience, but these members are not necessarily installed above the tank 1. is not.
[0036]
The first anaerobic filter tank 5 is provided with an inflow port 6 into which household wastewater, which is water to be treated, flows, and a first anaerobic filter bed 7 is provided therein. That is, since the household wastewater flows into the first anaerobic filter tank 5, it is also a contaminant removal tank in the present embodiment. In the present embodiment, the first anaerobic filter tank 5 constitutes an inflow tank. In the first anaerobic filter bed tank 5, hardly decomposable miscellaneous substances in household wastewater are precipitated and separated, and organic matter in household wastewater is anaerobically decomposed by anaerobic microorganisms attached to the first anaerobic filter bed 7. You. Further, nitric nitrogen is reduced to nitrogen gas.
[0037]
Further, the first anaerobic filter tank 5 is provided with a first advection pipe 8. In addition, a first water supply port 9 is formed in an upper part of the first partition wall 2. One end of the first advection tube 8 is arranged in the first anaerobic filter bed tank 5, and the other end is arranged in the second anaerobic filter bed tank 10. The treated water anaerobically decomposed in the first anaerobic filter tank 5 is supplied to the retreating second anaerobic filter tank 10 via the first advection pipe 8.
[0038]
The second anaerobic filter tank 10 is provided with a second anaerobic filter bed 11. Suspended substances are captured by the second anaerobic filter bed 11, organic substances are anaerobically decomposed by anaerobic microorganisms, and nitric nitrogen is reduced to nitrogen gas.
[0039]
The second anaerobic filter tank 10 is provided with a second advection pipe 12. A jet device 32 is attached to the upper part of the second advection pipe 12. The ejection device 32 is connected to the third blower 30. In addition, the jetting device 32 connects the second anaerobic filter tank 10 and the contact aeration tank 14 via the second water supply port 13 penetrating the upper part of the second partition wall 3.
[0040]
The jetting device 32 blows air from the jet port 31 into the second advection pipe 12 by sending air from the third blower 30. Thereby, the supply of the treated water from the second anaerobic filter tank 10 to the contact aeration tank 14 in the second advection pipe 12 is promoted.
[0041]
The contact aeration tank 14 includes a contact member 15. The contact material 15 is provided to promote the culture of aerobic microorganisms. A first air diffuser 16 is provided near the bottom of the contact aeration tank 14.
[0042]
The upper end of the first air diffuser 16 is connected to the first blower 17. A plurality of holes are formed on the lower surface side of the first air diffuser 16. Then, when air is sent from the first blower 17, the air is released as bubbles from the holes. In addition, since the hole is formed on the lower surface side of the first air diffuser 16, the sludge is less likely to enter the inside than when the hole is formed on the upper surface or the side surface.
[0043]
By releasing air bubbles from the first air diffuser 16, the contact aeration tank 14 is maintained in an aerobic state. As a result, in the contact aeration tank 14, the treated water is aerobically decomposed by the aerobic microorganisms, is also nitrified, and ammonia nitrogen is decomposed into nitrate nitrogen. The aerobic microorganisms in the contact aeration tank 14 include nitrifying bacteria. In general, nitrifying bacteria refer to ammonia oxidizing bacteria and nitrifying bacteria.
[0044]
The contact material 15 has attached thereto a biofilm that has grown and gradually increased. Then, when air bubbles are released from the first air diffuser 16, the biofilm adhering to the contact material 15 is separated.
[0045]
A pump 33 is provided below the contact aeration tank 14. Further, a sludge return path 34 is connected above the pump 33, and a sludge return path 35 is connected to the upper end of the sludge return path 34 so as to extend to the left in the figure. Thereby, the sludge generated in the contact aeration tank 14 is sent to the first anaerobic filter tank 5.
[0046]
A disinfection tank 21 is provided above the sedimentation tank 19. The disinfection tank 21 is configured such that the supernatant of the settling tank 19 flows into the disinfection tank 21. Further, the disinfection tank 21 is provided with a sterilizing device 22. The sterilizer 22 is provided with a chlorine-based chemical or the like. The treated water that has flowed into the disinfecting tank 19 is disinfected by the chemical and sent to the electrolytic tank 100 via the drain 23. The configuration of the electrolytic cell 100 will be described later.
[0047]
Further, the settling tank 19 is provided with a third advection pipe 38 and a pump 39.
The treated water in the contact aeration tank 14 flows into the settling tank 19 via the third advection pipe 38. This flow is promoted by the pump 39.
[0048]
The settling tank 19 and the first anaerobic filter tank 5 are connected by a first return pipe 24.
The first return pipe 24 includes a second air diffuser 25 therein. The second air diffuser 25 is connected to the second blower 26. The second air diffuser 25 has an ejection hole for ejecting air as appropriate. Then, the second air diffuser 25 blows out the air supplied from the second blower 26 from the outlet, and discharges the treated water in the sedimentation tank 19 through the first return pipe 24 through the first anaerobic filter bed. Feed into tank 5.
[0049]
In addition, an electrolytic cell 59 is provided above the first anaerobic filter tank 5. The water to be treated is introduced into the electrolytic tank 59 from the first return pipe 24. Further, inside the electrolytic cell 59, electrode pairs 51 and 52 are provided. The electrode pairs 51 and 52 are each connected to a power supply 57.
[0050]
In the electrolysis tank 59, metal ions such as iron ions and aluminum ions are eluted by an electrolysis reaction (abbreviated as electrolysis) in the electrode pairs 51 and 52. As a result, in the electrolytic tank 59, the eluted metal ions react with the phosphorus compound in the treated water, and a metal salt that is hardly soluble in water is generated and aggregated. When iron ions are eluted as metal ions, the elution of metal ions is represented by the formula (1a).
[0051]
Fe → Fe³⁺+ 3e⁻… (1a)
In addition, an example of a reaction formula for generating a metal salt that is hardly soluble in water is represented by formula (1b).
[0052]
Fe³⁺+ PO₄ ^3-→ FePO₄… (1b)
In addition, as the tolerable metal salt to be generated, mainly “FePO₄”,“ Fe (OH)₃"," FeOOH "," Fe₂O₃”And“ Fe₃O₄The compound of "" can be mentioned. That is, when the iron ions are supplied to the water to be treated, the above-described five types of compounds mainly aggregate.
[0053]
A magnetic processing unit 60 is provided downstream of the electrolytic cell 59. The water to be treated in the electrolytic cell 59 flows into the magnetic processing unit 60.
[0054]
In the magnetic processing unit 60, the water to be treated comes into contact with the magnet. Note that Fe₂O₃And Fe₃O₄Is attracted to the magnet. That is, the aggregate generated by supplying iron ions to the water to be treated is Fe₂O₃And Fe₃O₄To be attracted to the magnet. Thereby, Fe₂O₃And Fe₃O₄Co-aggregated with FePO₄Is also attracted to the magnet and separated from the water to be treated.
[0055]
After being treated by the magnetic treatment unit 60, the water to be treated is sent again to the first anaerobic filter tank 5.
[0056]
That is, in the water treatment system of the present embodiment, as shown in FIG. 1, the water to be treated is treated in the first and second anaerobic filter tanks 5 and 14 and then sent to the contact aeration tank 14. , And further sent to the sedimentation tank 19. The water to be treated in the sedimentation tank 19 is returned to the first anaerobic filter tank 5 via the electrolytic tank 59 together with the sludge to be settled. The water to be treated flows together with the sludge settling from the settling tank 19 to the contact aeration tank 14, and also from the contact aeration tank 14 to the second anaerobic filter bed tank 10 together with the sludge separated from the contact agent 15. Water to be treated flows in. The supernatant of the water to be treated in the sedimentation tank 19 flows into the disinfection tank 21. Then, the water to be treated in the disinfecting tank 21 is sent to the electrolytic tank 100 through the drain port 23. As described above, the electrolytic cell 59 is an electrolytic cell for removing a phosphorus component in the water to be treated. The electrolytic cell 100 is an electrolytic cell for removing nitrogen oxides such as nitrate ions in the water to be treated, as described later.
[0057]
Next, the configuration of the electrolytic cell 100 will be described with further reference to FIG. FIG. 3 is a diagram schematically showing the structure of the electrolytic cell 100. FIG. 3 also shows members around the electrolytic cell 100.
[0058]
Water to be treated is introduced into the electrolytic cell 100 from the tank 1 via the inlet 110, and water to be treated is separated from the solid-liquid separator 130 via the inlet 111. The electrodes 103 and 104 are immersed in the water to be treated in the electrolytic cell 100. The water to be treated is discharged from the electrolytic cell 100 through a discharge port 113. The amount of treated water introduced from the inlets 110 and 111 and the amount of treated water discharged from the outlet 113 can be controlled by controlling the opening and closing of the valves 110A, 111A and 113A, respectively. Further, an exhaust port 112 for discharging gas generated inside is formed in the electrolytic cell 100, and the opening and closing of the exhaust port 112 is controlled by opening and closing a valve 112A.
[0059]
A pump 131 is provided between the solid-liquid separator 130 and the inlet 111. The water to be treated in the tank 1 is introduced into the solid-liquid separation device 130 from the introduction port 116. In the water to be treated, a solid component and a liquid component are separated by the solid-liquid separation device 130, and the liquid component is sent to the electrolytic cell 100 via the inlet 111.
[0060]
In the electrolytic cell 100, when the electrodes 103 and 104 are supplied with power from the DC power supply 105, the electrode 103 is used as an anode and the electrode 104 is used as a cathode to perform electrolysis of the water to be treated. The electrode 103 is made of, for example, a platinum-iridium alloy. In addition, as the electrode 103, a noble metal or a material coated with a noble metal, a material containing a noble metal, a material coated with a material containing a noble metal, a carbon electrode, or an electrode made of stainless steel can be used. Among them, an insoluble metal electrode is preferable. Here, examples of the material containing a noble metal include oxides of platinum, iridium oxide, and materials obtained by mixing a noble metal in ceramics and firing (silicon oxide, titanium oxide, and the like).
[0061]
The electrode 104 is made of an alloy containing an amphoteric metal such as a copper-aluminum alloy, or an alloy containing a metal that is oxidized and reacts with an anion such as a hydroxide ion to produce a water-insoluble compound that acts as a coagulant. Or a metal that is oxidized like iron or aluminum and reacts with phosphate ions to produce a compound insoluble in water, or an alloy containing such a metal. In addition, since nitrate ions are reduced on the electrode 104 as described later, the electrode 104 may be formed of an insoluble metal electrode.
[0062]
Further, a water level sensor 122 and a pH sensor 123 are provided in the electrolytic cell 100. Further, a chemical supply device 106 for supplying sodium chloride and hypochlorous acid is provided in the electrolytic cell 100. From the drug supply device 106, a drug is appropriately administered into the electrolytic cell 100 via a tube 106A. A stirrer 107 is provided in the electrolytic cell 100, and the stirrer 107 rotates and stirs the water to be treated in the electrolytic cell 100 when appropriately powered from outside the electrolytic cell 100. When the water to be treated is being processed in the electrolytic cell 100, the stirrer 107 is appropriately rotated.
[0063]
Further, a control circuit 120 is provided which receives the detection outputs of the water level sensor 122 and the pH sensor 123 and controls the operations of the valves 110A, 111A, 112A, 113A and the DC power supply 105. The control circuit 120 controls the opening and closing of the valves 110A, 111A, 113A based on the detection output of the water level sensor 122, for example, so that the amount of water in the electrolytic cell 100 becomes constant. Further, the control circuit 120 opens the valve 112A at regular time intervals and discharges the gas generated in the electrolytic cell 100 to the outside of the electrolytic cell 100.
[0064]
Here, the main electrolytic reaction on the electrodes 103 and 104 and the accompanying reaction will be described with reference to the following equations (2) to (11).
[0065]
(Equation 1)

[0066]
In the water to be treated in the electrolytic cell 100, the equilibrium of the above equations (2) and (3) is established by the addition of sodium chloride. In the vicinity of the electrode 103, as shown in the above formulas (4) to (6), oxygen gas is generated by electrolysis of water, chlorine ions are converted to chlorine gas, and part of the chlorine gas is hydrated. It becomes hypochlorous acid. In the vicinity of the electrode 104, hydrogen gas is generated by the electrolysis of water as shown in the above equations (7) and (8), and sodium ions react with hydroxide ions to generate sodium hydroxide. You. As a result, the water to be treated becomes alkaline near the electrode 104.
[0067]
Then, nitrate ions in the water to be treated introduced into the electrolytic cell 100 are reduced to ammonia via nitrite ions on the surface of the electrode 104 (see equations (9) to (11)). When the electrode 104 contains an amphoteric metal such as aluminum or zinc, electrons generated when the amphoteric metal is strongly alkaline and eluted from the electrode 104 are also used for reducing nitrate ions in the formula (11). it is conceivable that. In some cases, nitrate ions are reduced on the electrode 104 and directly become nitrogen gas.
[0068]
The ammonia generated as described above combines with the hypochlorous acid generated as described above to generate chloramines as represented by the following formulas (12) to (14). Further, the generated chloramines are converted into nitrogen gas or nitrous oxide as shown in formulas (15) and (16).
[0069]
(Equation 2)

[0070]
Further, as described above, the aluminum eluted from the electrode 104 (see the following equation (17)) reacts with hydroxide ions in the water to be treated as aluminum ions to form aluminum hydroxide, as shown in the equation (18). Or, as shown in formula (19), reacts with sodium ions as aluminate to form sodium aluminate.
Then, a colloid in water (SS (Suspended Solids) component in water) having a particle size of 1 to 0.01 × 10^-6m) are neutralized, an attractive force acts between particles, and eventually flocs and sediments.
[0071]
(Equation 3)

[0072]
Further, the aluminum ion eluted from the electrode 104 reacts with the phosphate ion in the water to be treated, becomes aluminum insoluble in water, and precipitates as shown in the following equation (20). Thereby, the phosphoric acid component in the water to be treated can be removed by the aluminum ions. In the present embodiment, since a metal capable of removing a phosphoric acid component and an SS component typified by aluminum is eluted at the cathode, such a metal is closer to the electrode than when the metal is eluted at the anode. Passivation can be avoided.
[0073]
(Equation 4)

[0074]
In this embodiment, when the electrode 104 is formed of an alloy containing copper as a main component and a metal having a higher ionization tendency than copper, such as a Devarda alloy, reduction of nitrate ions is particularly promoted. You. If the purpose is only to remove nitrogen oxides and / or phosphoric acid in the water to be treated, the electrode 104 is dissolved in an amphoteric metal such as aluminum, and the components in the electrode 104 are eluted. A metal that reacts with anions in the tank 100 and acts as a coagulant to form a water-insoluble compound, or a metal that is oxidized and reacts with phosphate ions to form a water-insoluble compound. It may be composed of a single metal.
[0075]
FIG. 4 shows an example of the solid-liquid separation device 130.
The solid-liquid separation device 130 is provided with a separation membrane 130A near the bottom thereof. The separation membrane 130A completely partitions the inside of the solid-liquid separation device 130 up and down.
[0076]
Above the solid-liquid separator 130, an outlet 115 for sending the water to be treated to the electrolytic cell 100 is provided. The discharge port 115 is connected to a pump 131.
[0077]
In the solid-liquid separation device 130, the guided solid component in the water to be treated cannot pass through the separation membrane 130A. Thereby, the water to be treated from which the solid components have been removed is sent from the solid-liquid separation device 130 to the electrolytic cell 100.
[0078]
The bottom of the solid-liquid separator 130 is of a hopper type, and the opening and closing of the valve 130C is appropriately controlled by the control circuit 120, so that solid components such as precipitates are discharged from the outlet 130B of the bottom.
[0079]
Next, the structure of the electrode pair 101 constituted by the electrodes 103 and 104 will be described in more detail. FIG. 5 is a perspective view of the electrode pair.
[0080]
Referring to FIG. 5, electrodes 103 and 104 forming an electrode pair are attached to electrode support portions 101A and 101B. The electrode supporting portions 101A and 101B support the electrodes 103 and 104, respectively, and are combined with each other, as described later.
A wiring 101X that connects the electrodes 103 and 104 to the control circuit 120 extends from above the electrode support portions 101A and 101B.
[0081]
FIG. 6 shows the structure of the electrodes 103 and 104 and the electrode support portions 101A and 101B. FIG. 7 is a side view showing a state in which the electrodes 103 and 104 and the electrode support portions 101A and 101B are combined to be mounted on the electrolytic cell 100, as viewed from the side.
[0082]
The electrodes 103 and 104 are attached to the electrode support portions 101A and 101B, respectively. The electrode supporting portions 101A and 101B are located above the electrodes 103 and 104, and are appropriately supported so as not to be immersed in the treated water in the electrolytic cell 100.
[0083]
Referring to FIGS. 6 and 7, electrodes 103 and 104 have their upper portions screwed to electrode support portions 101A and 101B, respectively. A spacer 101C is attached to the electrode support 101A on a surface that should face the electrode support 101B.
Then, as shown in FIG. 7, the electrode support portion 101A and the electrode support portion 101B are combined and fixed to face each other via a spacer 101C. The distance between the electrode 103 and the electrode 104 is adjusted by appropriately adjusting the width of the spacer 101C.
[0084]
Here, the configuration of the electrode support portions 101A and 101B will be described. FIG. 8 is a perspective view of the electrode support 101A. The electrode support 101A includes a wiring for connecting the DC power supply 105 and the electrode 103. One end of the wiring is a connector 1010, and the other end is a connector 1011. The electrode 103 is electrically connected to the connector 1010 by being screwed to the electrode support 101A. The connector 1011 is electrically connected to the DC power supply 105. As a result, the electrode 103 is electrically connected to the DC power supply 105 by being screwed to the electrode support 101A. In addition, the electrode support portion 101B also has two connectors and includes wiring, similarly to the electrode support portion 101A. The electrode 104 is electrically connected to the DC power supply 105 by being screwed to the electrode support 101B.
[0085]
Since the electrodes 103 and 104 and the electrode supporting portions 101A and 101B are configured as described above, the wiring connecting the electrodes 103 and 104 and the power supply 38 can be prevented from lying in the treated water. Some connectors can be prevented from being immersed in the treated water and corroded.
[0086]
FIG. 9 is a view for explaining a mode of attaching the electrodes 103 to the electrode support portions 101A and 101B.
[0087]
A cutout 101E into which the upper part of the electrode 103 can be fitted is formed in the electrode support 101A. A similar notch is also formed in the electrode support 102A. Each of the electrodes 103 and 104 has its upper part fitted into the cutout and is screwed. Thereby, the positions of the electrodes 103 and 104 in the electrolytic cell 100 are more reliably fixed, and the position where the electrode reaction occurs in the electrolytic cell 100 is stabilized.
[0088]
When the electrode supporting portions 101A and 101B and the electrodes 103 and 104 are transported as a unit, it is preferable that the electrode supporting portions 101A and 101B be housed in a case and transported as shown in FIG. More specifically, the unitized electrode support portions 101A and 101B and the electrodes 103 and 104 are combined with the case 1020 such that the electrodes 103 and 104 fit inside the case 1020. At the time of combination, the electrode support portions 101A and 101B are screwed to the case 1020 by screws 102A and 102B.
[0089]
FIG. 11 schematically shows an electrolytic reaction in the electrolytic cell 100.
The electrodes 103 and 104 are energized by a DC power supply 105. When current is supplied to one of the electrodes 103 and 104 as a cathode electrode and the other to an anode electrode, on the anode side, halogen ions (chloride ions in FIG. 11) existing in the water to be treated are oxidized and halogen gas (chloride ion) is discharged. (If chlorine ions are oxidized), the gas reacts with water in the water to be treated to produce hypochlorous acid. On the other hand, on the cathode side, nitrogen components in the water to be treated (such as organic nitrogen compounds in the water to be treated) are converted into nitrate ions, and nitrate ions are further converted into ammonium ions. Then, by reacting the hypochlorous acid and the ammonium ion thus electrochemically generated, the nitrogen component is converted into nitrogen gas via chloramines. In the present embodiment, potentials of opposite polarities are applied to the electrodes 103 and 104, but the polarities are exchangeable. Therefore, when one of the electrodes 103 and 104 is formed of a material containing iron, the electrode containing iron can be used as a cathode electrode at one time and as an electrode for reducing nitrate ions, and at another time. Can be used as an electrode on the anode side to elute iron ions.
[0090]
Further, FIGS. 3 and 11 show a state in which only one electrode pair 101 including the electrodes 103 and 104 is set in the electrolytic cell 100, but the present invention is not limited to this. A plurality of electrode pairs 101 may be set as shown in FIG.
[0091]
Next, the configuration of the electrode pair 51 in the electrolytic cell 59 will be described with reference to FIGS. FIG. 13 is a perspective view of the electrode pair 51. FIG. 14 is a perspective view when the electrode pair 51 is partially broken. The electrode pair 52 has the same configuration as the electrode pair 51.
[0092]
The electrode pair 51 includes two metal plates of the electrodes 511 and 512. The metal plate is made of, for example, iron or aluminum.
[0093]
The electrode pair 51 includes a support 510. A handle 510a is attached to an upper portion of the support 510. A cover 513 is attached to the left side surface of the support 510. More specifically, six screw holes are formed in the cover 513, and each screw hole is screwed with a predetermined screw, so that the cover 513 is attached to the left side surface of the support 510. The electrode 511 is attached to the cover 513 by nuts 511a and 511b. The above-mentioned screw holes include screw holes 513a, 513b (see FIG. 15), 513c, 513d, and 513e. The predetermined screws include the screws 517a, 517b, 517c, and 517d shown in FIG.
[0094]
A guide 519d is attached to the upper rear of the support 510, and the wiring 519 protrudes from the guide 519d toward the upper side of the support 510. The guide 519d has a cylindrical shape, and the wiring 519 is passed through the inside of the guide 519d. A connector 519c for connecting to the power supply 57 is connected to one end of the wiring 519. The portion of the wiring 519 from the portion (below) the guide 519d to the other end is built in a combination of the support 510 and the cover 513. Note that the wiring 519 includes a plurality of wirings (including a wiring 519a described later). The other end of the wiring 519 is in a state where a terminal such as a terminal 518 (see FIG. 15) described later is attached to each of the plurality of included wirings.
[0095]
Here, FIGS. 15 and 16 show exploded perspective views of the electrode pair 51, partially and partially broken. Note that, in FIG. 16, the wiring 519, the connector 519c, the wiring 519a, and the terminal 518 are omitted for convenience.
[0096]
15 and 16, between the cover 513 and the support 510, electrode fixing jigs 515 and 516 made of iron, stainless steel, or the like are provided. The electrode fixing jigs 515 and 516 are conductors and are preferably made of a material that is hardly corroded.
[0097]
The electrode fixing jig 515 is a plate on which protrusions 515a and 515b are formed. The protrusions 515a and 515b are configured to be able to penetrate holes formed in the cover 513. The electrode 511 is attached so as to be electrically connected to the protrusions 515a and 515b by nuts 511a and 511b.
[0098]
A terminal 518 is provided slightly behind the center of the support 510 and between the electrode fixing jig 515 and the electrode fixing jig 516. The terminal 518 forms an end of the wiring 519a. The wiring 519a is one of a plurality of wirings included in the wiring 519.
[0099]
The terminal 518 is arranged at a position where it comes into contact with the projection 515a when the electrode fixing jig 515 is attached to the cover 513 and the cover 513 is attached to the support 510. Thus, the electrode 511 is electrically connected to the terminal 518 via the protrusion 515a.
[0100]
Note that the electrode fixing jig 516 is also formed with a projection similar to the projections 515a and 515b. The protrusion protrudes on the left side surface of the support 510. Further, a terminal different from the terminal 518 is provided slightly forward of the center of the support 510 and between the electrode fixing jig 515 and the electrode fixing jig 516. The other terminal here constitutes an end of a wiring different from the wiring 519a among a plurality of wirings included in the wiring 519. The other terminal is electrically connected to a projection formed on the electrode fixing jig 516, and the projection is connected to the electrode 512. Thus, the another terminal and the electrode 512 are electrically connected.
[0101]
Although not shown, an insulator is provided between the electrode fixing jig 515 and the electrode fixing jig 516 and between the terminal and the terminal 518. Thus, a short circuit between the electrode 511 and the electrode 512 inside the combination of the support 510 and the cover 513 can be reliably avoided.
[0102]
The electrode fixing jig 515 is screwed to the cover 513 by screws 514a to 514c. The electrode fixing jig 516 is screwed to the support 510 by screws 514d to 514f.
[0103]
A packing 510b is provided between the support body 510 and the cover 513 and outside the place where the cover 513 is screwed. Further, a packing 510c is provided between the support 510 and the electrode fixing jig 516 and outside the place where the electrode fixing jig 516 is screwed. Further, a packing similar to the packing 510c is provided between the cover 513 and the electrode fixing jig 515 and outside the place where the electrode fixing jig 515 is screwed.
[0104]
Thus, when the support 510 and the cover 513 are combined, the support 510 and the cover 513 can incorporate the terminal 518 and the above-mentioned another terminal so that water does not enter inside.
[0105]
In the tank 1 shown in FIG. 2, the electrolytic cell 59 is provided in the contact back tank 14. The electrolytic cell 59 may be provided in another tank in the tank 1, such as the first anaerobic leaky tank 5, the second anaerobic leaky tank 10, or the sedimentation tank 19. Further, the electrolytic cell 59 may be provided outside the tank 1 so as to be adjacent to the inlet 6 and the drain 23.
[0106]
In the electrolytic cell 59 of the present embodiment, the electrode pairs 51 and 52 are surrounded by a case 54. In the electrolytic cell 59, the case 54 may have a bottom and a valve having a valve at the bottom. Here, the valve is provided to discharge the insoluble precipitate generated inside the tank outside the tank. By installing the electrode pairs 51 and 52 in such a tank, it is possible to prevent the electrolytic reaction in the electrode pairs 51 and 52 from being hindered by sludge in other tanks (such as the first anaerobic leaky tank 5). it can.
[0107]
In addition, the circulation flow rate of the tank 1 is 3Q. Note that Q is the amount of water flowing into the tank 1. That is, in the tank 1, the amount of water three times the amount of water flowing in is circulated.
[0108]
The electrolytic reaction in the electrode pairs 51 and 52 is performed so that the concentration of the eluted iron ions or aluminum ions is 1 to 3 times the molar concentration of phosphorus in the treated water. The above-mentioned electrolytic reaction is controlled so that the concentration of iron ions or aluminum ions is preferably about 1 to 2 times, more preferably about 1.5 times, the molar concentration of phosphorus in the treated water. You. For this reason, in the electrolytic reaction, the current density at the electrode is 0.1 mA / cm.²Or more, often 0.3 mA / cm²It is controlled to be about.
[0109]
By controlling the current density in the electrode as described above, it is considered that generation of an oxide film and organic deposits on the electrode surface can be prevented, and these can be removed. This is because it is considered that iron hydroxide and organic deposits which are considered to be generated at the anode side electrode can be removed by hydrogen gas generated at the cathode side or backing by the third diffuser 53. Therefore, when the current density in the above electrolytic reaction is too low, the amount of hydrogen gas generated on the cathode side is low, and it is considered that the deposits on the anode side cannot be sufficiently removed. The backing amount of the third air diffuser 53 in the electrolytic cell 59 is set to about 15 L / min.
[0110]
For example, when the amount of domestic wastewater flowing into the tank 1 per day is 1200 L and the circulation flow rate in each tank in the tank 1 is 6000 L, the current flowing through the electrodes 511 and 512 and the electrodes forming the electrode pair 52 Is controlled to about 650 mA.
The current density at each electrode can be controlled by changing the immersion area of each electrode. The distance between the electrode 511 and the electrode 512 is set to about 25 mm, and the voltage between the electrodes is constantly monitored. Further, it is preferable that the polarity of each electrode is reversed every predetermined time (for example, every 24 hours).
[0111]
One of the electrodes 511 and 512 is formed of an insoluble metal electrode. The other is made of a conductor containing a metal of Group VIII of the periodic table, preferably iron.
[0112]
Further, in the present embodiment, as can be understood from FIGS. 1 and 2, the electrolytic cell 100 is installed at the subsequent stage of the tank 1, that is, so that the water to be treated after the secondary treatment is introduced. I was FIGS. 17B and 17C show a modified example of the flow of processing when the electrolytic cell 100 is used as an apparatus for tertiary treatment of the water to be treated. FIG. 17A shows a part of the processing flow of FIGS. 17B and 17C.
[0113]
With reference to FIGS. 17A and 17B, in this example, first, in the process 200, the water to be treated is subjected to an anaerobic treatment and an aerobic treatment.
[0114]
The processing in step 200 is the processing in the step shown in FIG. Specifically, the water to be treated that has been treated in the anaerobic filter tank 201 is sent to the contact aeration tank 202. A part of the water to be treated after the treatment in the contact aeration tank 202 is returned to the anaerobic filter tank 201 together with the separated sludge, and a part is sent to the sedimentation tank 203. A part of the water to be treated in the sedimentation tank 203 is returned to the contact aeration tank 202 together with the sedimentation sludge, but a part is sent to the next step.
[0115]
Then, referring to FIG. 17B, the water to be treated after the treatment in step 200 is sent to contact aeration tank 210. The treated water in the contact aeration tank 210 is sent to the settling tank 211. The separated sludge from the contact aeration tank 210 is sent to a separately provided sedimentation tank, sludge concentration storage tank, sludge concentration equipment, and the like. A part of the water to be treated in the sedimentation tank 211 is sent to the anaerobic filter tank 201 (see FIG. 17 (A)) together with the sedimentation sludge, and a part is sent to the sand filtration raw water tank 212, It is sent to the filtration device 213.
[0116]
The washing wastewater generated in the sand filtration device 213 is sent to the electrolytic tank 214 for removing phosphorus, and then returned to the anaerobic filter bed tank 201 (see FIG. 17A). The water to be treated after filtration by the sand filtration device 213 is sent to a sand filtration treatment water tank 215, is disinfected in a disinfection tank 216, is treated by 100 for nitrogen removal, and is discharged outside the facility.
[0117]
Next, a modification of FIG. 17B will be described with reference to FIGS. 17A and 17C.
[0118]
Also in this example, first, in the process 200, the water to be treated is subjected to anaerobic treatment and aerobic treatment. Then, the water to be treated after the treatment in the process 200 is circulated through the intermediate flow rate adjusting tank 220, the coagulation tank 221, the coagulation sedimentation tank 222, and the electrolytic tank 223 for removing phosphorus. The water to be treated in the electrolytic tank 223 for removing phosphorus is sent to the anaerobic filter tank 201 in the step 200. The supernatant in the coagulation sedimentation tank 222 is sent to the disinfection tank 224, processed in the electrolytic cell 100 for removing nitrogen, and then discharged outside the facility.
[0119]
Further, in the present embodiment described above, the electrolytic treatment may be performed in the electrolytic cell 100 such that the water to be treated is replaced every predetermined time. In the electrolytic cell 100, the nitrate ion concentration and / or the phosphate ion concentration of the water to be treated in the electrolytic cell 100 are detected, and when these concentrations fall below a predetermined value, the control circuit 120 activates the valve. The electrolytic treatment may be performed by appropriately opening and closing 110A, 111A, and 113A and replacing the water to be treated in electrolytic cell 100.
[0120]
[Second embodiment]
FIG. 18 is a schematic longitudinal sectional view of an apparatus constituting a water treatment system including a water treatment apparatus according to the second embodiment of the present invention.
[0121]
The electrolytic cell 100 may be installed outside the tank 1 as shown in FIG. 2, or may be installed inside the tank 1 as shown in FIG.
[0122]
When the electrolytic cell 100 is installed in the tank 1, the value of the current flowing between the electrodes 103 and 104 is controlled by controlling the halogen ion concentration and the hypohalous acid ion concentration in the electrolytic cell 100 or It needs to be done based on the pH value.
[0123]
In the first embodiment, as described using Equations (3) and (6), halogen ions and hypohalous acid ions are generated in the electrolytic cell 100. It is considered that these ions have a bad influence on the microorganisms in the tank 1 when the concentration is high.
[0124]
For this reason, in the present embodiment, the electrode 103 is controlled so that the halogen ion concentration and the hypohalite ion concentration in the electrolytic cell 100 do not exceed a predetermined concentration or the pH does not fall below a predetermined value. , 104 are controlled.
[0125]
When the electrolytic cell 100 is installed in the tank 1 as shown in FIG. 18, the processing steps shown in FIG. 1 will be changed to those shown in FIG. When the electrolytic cell 100 is installed in the tank 1 in the steps shown in FIGS. 17B and 17C, the respective steps are changed to the steps shown in FIGS. 19B and 19C. Will be.
[0126]
[Third Embodiment]
The water treatment apparatus according to the present embodiment is configured such that, when the electrolytic cell 100 is attached to the outside of the tank 1 or the like, the water is discharged from the electrolytic cell 100 to the outside via a newly provided sedimentation tank 190. is there.
[0127]
In the present embodiment, as shown in FIG. 20, water to be treated is introduced into electrolytic cell 100 from introduction port 110. In the electrolytic cell 100, the electrodes 103 and 104 are immersed in the water to be treated. The water to be treated in the electrolytic cell 100 is introduced into the sedimentation tank 190 from the side outlet 114. An outlet 117 is formed at the bottom of the electrolytic cell 100. The discharge port 117 is opened and closed by a valve 117A. In the electrolytic cell 100 of the present embodiment, sediments and the like can be discharged from the discharge port 117 to the outside. The opening and closing of the valve 117A is performed every time power is supplied to the electrodes 103 and 104 for a certain period of time by an appropriately provided control unit such as the control circuit 120.
[0128]
The precipitation tank 190 is provided with a separation membrane 190A. Most of the water to be treated introduced into the sedimentation tank 190 passes through the separation membrane 190A and is discharged to the outside. At the bottom of the sedimentation tank 190, an outlet 190C for discharging the sediment generated in the sedimentation tank 190 is formed, and the outlet 190C is opened and closed by a valve 190B. The operation of the valve 190B is also controlled by a control unit (not shown) such as the control circuit 120.
[0129]
[Fourth Embodiment]
As shown in FIG. 21, the water treatment apparatus of the present embodiment is provided with a coagulation tank 600 between the electrolytic tank 100 and the precipitation tank 190 of the third embodiment.
[0130]
Referring to FIG. 21, in the present embodiment, in electrolytic cell 100, a film 108 for preventing SS components, precipitates, and the like from approaching electrode 103 and the like, and bubbles are generated in electrolytic cell 100. A back pipe 109 for performing agitation and the like, and a pump 109P for sending air to the back pipe 109 are provided. In the coagulation tank 600, a coagulant tank 601 containing a coagulant to be introduced into the coagulation tank 600, a pump 602 for sending the coagulant in the coagulation tank 601 into the coagulation tank 600, and discharge from the coagulation tank 600. A membrane 603 for separating solid components in the water to be treated, a back pipe 604 for performing agitation or the like by generating bubbles in the flocculation tank 600, and a pump 604P for sending air to the back pipe 604 are provided. Have been.
[0131]
The water to be treated introduced into the electrolytic cell 100 is sent to the coagulation tank 600 after being subjected to the electrolytic treatment. In the coagulation tank 600, by adding the coagulant from the coagulant tank 601, the phosphoric acid component can be coagulated and removed from the water to be treated as a phosphorus compound. Examples of the coagulant include iron compounds such as polyiron sulfate, aluminum compounds such as polyaluminum chloride, and biodegradable polymers such as polyglutamic acid. Then, the supernatant liquid in the flocculation tank 600 is sent to the precipitation tank 190, and discharged from the precipitation tank 190 to the outside.
[0132]
[Fifth Embodiment]
As shown in FIG. 22, the water treatment apparatus according to the present embodiment is provided with an electrolytic tank 59 for removing phosphorus instead of the coagulation tank 600 according to the fourth embodiment. In the present embodiment, the water to be treated introduced into electrolytic cell 100 is sent to electrolytic cell 59, then sent to sedimentation tank 190, and discharged to the outside. In the present embodiment, a flocculant is added from the flocculant tank 601 to the electrolytic tank 59 for removing phosphorus.
[0133]
[Sixth Embodiment]
As shown in FIG. 23, the water treatment apparatus according to the present embodiment further includes an electrolytic tank 59 for removing phosphorus between the electrolytic tank 100 and the coagulation tank 600 according to the fourth embodiment. . Since the coagulation bath 600 is provided, the coagulant is not added to the electrolytic bath 59 of the present embodiment as in the electrolytic bath 59 of the fifth embodiment.
[0134]
In the water treatment apparatus of the present embodiment, the water to be treated introduced into the electrolytic cell 100 is sent to the electrolytic cell 59, sent to the coagulation tank 600, sent to the sedimentation tank 190, and discharged to the outside. Is done.
[0135]
[Seventh Embodiment]
The water treatment apparatus of the present embodiment is characterized by the electrodes set in electrolytic cell 100 and the control mode thereof. In the electrolytic cell 100 of the present embodiment, as shown in FIG. 24, a plurality of plate-shaped electrodes 902 to 905 are provided around a columnar electrode 901.
[0136]
FIG. 25 shows only a part related to control of the electrodes 901 to 905 in the control block diagram of the water treatment apparatus.
[0137]
Electrodes 901 to 905 are supplied with power from DC power supply 900. The operation of DC power supply 900 is controlled by control unit 910. The electrode 901 is constituted by an insoluble metal electrode. The electrodes 902 to 905 are made of an alloy containing iron.
[0138]
The electrode 901 is an anode electrode. The electrode 902 is a cathode electrode. The electrodes 903 to 905 may be anode electrodes or cathode electrodes.
[0139]
The control unit 910 can refer to the detection outputs of the phosphorus concentration sensor 920 for detecting the phosphorus concentration in the electrolytic cell 100 and the nitrogen concentration sensor 930 for detecting the nitrogen concentration in the electrolytic cell 100. Then, when the phosphorus concentration is higher than the predetermined value for the phosphorus concentration and the nitrogen concentration is lower than the predetermined value for the nitrogen concentration, control unit 910 can focus on the phosphorus removal in electrolytic cell 100. As described above, the DC power supply 900 is controlled so that the number of the electrodes 903 to 905, which are the anode electrodes, is increased. This is because these electrodes are used as anode electrodes to elute more iron ions.
[0140]
Further, control unit 910 controls the current value flowing through electrodes 901 to 905 according to the phosphorus concentration and / or the nitrogen concentration in electrolytic cell 100. Thereby, the ability of removing phosphorus and / or removing nitrogen by electrolysis can be adjusted according to the concentration of phosphorus and / or the concentration of nitrogen. In addition, when the electrodes 901 to 905 are used as anode electrodes, the electrodes are eluted more than necessary. Without doing so, the life of the electrode can be extended.
[0141]
On the other hand, when the phosphorus concentration is lower than the predetermined value for the phosphorus concentration and the nitrogen concentration is higher than the predetermined value for the nitrogen concentration, control unit 910 can focus on nitrogen removal in electrolytic cell 100. As described above, the DC power supply 900 is controlled so that the number of the electrodes 903 to 905 serving as the cathode is increased. This is because these electrodes are used as cathode electrodes to reduce more nitrogen oxides.
[0142]
When any one of the electrodes 903 to 905 is used as an anode electrode, it is preferable to face another electrode serving as a cathode electrode as shown in FIG. FIG. 26 shows a preferred arrangement in the case where the electrodes 903 and 905 are anode electrodes and the electrode 904 is a cathode electrode.
[0143]
The embodiments disclosed this time should be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims. The embodiments can be applied independently or in combination as much as possible.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing processing steps of a water treatment system including a water treatment device according to a first embodiment of the present invention.
FIG. 2 is a schematic longitudinal sectional view of a household combined septic tank embodying the processing step of FIG. 1;
FIG. 3 is a view schematically showing a structure of an electrolytic cell for removing nitrogen in FIG. 1;
4 is a diagram showing an example of the solid-liquid separation device of FIG.
FIG. 5 is a perspective view of the electrode pair of FIG. 3;
FIG. 6 is a diagram showing a structure of an electrode and an electrode support of FIG. 3;
FIG. 7 is a side view of a state in which the electrode and the electrode support of FIG. 6 are combined to be mounted on an electrolytic cell.
FIG. 8 is a perspective view of the electrode support of FIG. 3;
FIG. 9 is a diagram for explaining a mode of attaching the electrode of FIG. 3 to an electrode support.
FIG. 10 is a diagram showing a state in which the electrode and the electrode support of FIG. 3 are housed in a case.
FIG. 11 is a diagram schematically showing an electrolytic reaction in the electrolytic cell of FIG.
12 is a diagram showing a state in which a plurality of electrode pairs are provided in the electrolytic cell of FIG.
FIG. 13 is a view for explaining a configuration of an electrode pair in the electrolytic cell for removing phosphorus in FIG. 1;
14 is a view for explaining a configuration of an electrode pair in the electrolytic cell for removing phosphorus in FIG. 1;
FIG. 15 is an exploded perspective view, partially broken away, of the electrode pair of FIG. 13;
FIG. 16 is an exploded perspective view, partially broken away, of the electrode pair of FIG. 13;
FIG. 17 is a diagram showing a modification of the flow of the treatment for the water to be treated shown in FIG. 1;
FIG. 18 is a schematic longitudinal sectional view of an apparatus constituting a water treatment system including a water treatment apparatus according to a second embodiment of the present invention.
FIG. 19 is a diagram showing a flow of processing on water to be treated in the water treatment system of FIG. 18, and a modification thereof.
FIG. 20 is a view schematically showing a water treatment apparatus according to a third embodiment of the present invention.
FIG. 21 is a view schematically showing a water treatment apparatus according to a fourth embodiment of the present invention.
FIG. 22 is a view schematically showing a water treatment apparatus according to a fifth embodiment of the present invention.
FIG. 23 is a view schematically showing a water treatment apparatus according to a sixth embodiment of the present invention.
FIG. 24 is a view showing an arrangement of electrodes in an electrolytic cell of a water treatment apparatus according to a seventh embodiment of the present invention.
FIG. 25 is a control block diagram relating to control of the electrodes in FIG. 24;
26 is a diagram showing a modification of the arrangement of the electrodes shown in FIG. 24.
[Explanation of symbols]
1 tank, 5 first anaerobic filter bed tank, 10 second anaerobic filter bed tank, 14 ば contact aeration tank, 19,190 sedimentation tank, 51, 52, 101 electrode pair, 59, 100 electrolytic cell, 103, 104 electrode, 105 DC power supply, 120 control circuit, 600 coagulation tank.

Claims (12)

An electrolytic cell provided with water to be treated and having an electrode pair,
The water to be treated treated in the electrolytic cell is introduced, and a coagulant addition tank for adding a coagulant,
A water treatment apparatus, comprising: a sedimentation tank for introducing the water to be treated treated in the coagulant addition tank, and for sedimenting aggregates in the water to be treated. The electrolytic cell includes a first electrolytic cell including the soluble electrode, and a second electrolytic cell including an anode electrode formed of an insoluble metal electrode and a cathode electrode formed of a copper alloy, iron, iron alloy, or an insoluble metal electrode. The water treatment apparatus according to claim 1, comprising: The water treatment device according to claim 1, wherein the soluble electrode is iron, an iron alloy, aluminum, or an aluminum alloy. A first electrode made of an insoluble metal electrode into which water to be treated is introduced, and a second electrode made of a conductor containing a metal of Group VIII of the periodic table, the electrode being given an opposite polarity to the first electrode. An electrolytic cell comprising:
A water treatment apparatus, comprising: a polarity inverting unit that inverts the polarity applied to the first electrode and the second electrode. A water treatment apparatus comprising: an anode electrode made of an insoluble metal electrode; and a cathode electrode made of a copper alloy, iron, iron alloy, or an insoluble metal electrode, and includes an electrolytic cell into which water to be treated is introduced. An electrolytic cell including a plurality of electrodes which are made of an alloy including iron and which are independently given a polarity,
A water treatment apparatus, comprising: a polarity control unit that controls the polarity applied to the plurality of electrodes. The electrode control apparatus further includes a detection unit capable of detecting the amount of the phosphorus compound and the amount of the nitrogen oxide in the electrode tank, wherein the polarity control unit determines the polarity and the polarity applied to each of the plurality of electrodes according to a detection output of the detection unit. The water treatment device according to claim 6, wherein a current value flowing through the plurality of electrodes is controlled. The water treatment apparatus according to any one of claims 1 to 7, further comprising a water amount control unit for keeping the amount of water in the electrolytic cell constant. The water treatment apparatus according to any one of claims 1 to 8, wherein the electrolytic cell is a hopper type and includes a drain valve at a bottom thereof. The water treatment apparatus according to any one of claims 1 to 9, wherein the electrolytic cell includes a mechanism for discharging gas generated in the electrolytic cell to the outside. The method according to claim 1, further comprising a separation unit provided in a flow path of the water to be treated in the electrolytic cell, for separating liquid and solid contained in the water to be treated. Water treatment equipment. The water treatment apparatus according to claim 1, further comprising a chlorine compound supply unit that supplies a chlorine compound into the electrolytic cell.

Images