JP4034074B2

JP4034074B2 - Wastewater treatment equipment

Info

Publication number: JP4034074B2
Application number: JP2002004880A
Authority: JP
Inventors: 進石川
Original assignee: Maezawa Industries Inc
Current assignee: Maezawa Industries Inc
Priority date: 2002-01-11
Filing date: 2002-01-11
Publication date: 2008-01-16
Anticipated expiration: 2022-01-11
Also published as: JP2003205297A

Description

【０００１】
【発明の属する技術分野】
本発明は、排水処理装置に関し、詳しくは、嫌気性処理と好気性処理とを組み合わせた生物ろ床法による排水処理装置であって、特に、良好な処理水質を得るとともに汚泥発生量の低減も図れる排水処理装置に関する。
【０００２】
【従来の技術】
従来から、排水処理の一手段として、嫌気性処理と好気性処理とを組み合わせた生物ろ床法による嫌気好気処理が広く行われている。この嫌気好気処理は、好気性生物処理における比較的短時間で良好な処理水質が得られるという特性と、嫌気性生物処理における汚泥発生量が少ないという特性とを組み合わせたものであって、良好な処理水質が得られるとともに汚泥発生量が比較的少なく、動力費も少ないという利点を有している。
【０００３】
【発明が解決しようとする課題】
しかし、従来の嫌気好気処理を行う排水処理装置は、嫌気性生物処理を行う嫌気性ろ床では、閉塞を防止するために大きなサイズの接触材を使用する必要があり、必ずしも効果的な生物保持ができず、さらに、沈殿汚泥の効果的な引き抜きもできないという問題もあった。また、好気性生物処理を行う好気性ろ床では、一般に直径３〜５ｍｍ程度のアンスラサイト等のろ材を使用していることから、１日に１回程度の洗浄を必要とするという問題があった。さらに、脱窒処理を行うために好気性処理を行った処理水を硝化液として嫌気性処理ゾーンに循環させると、硝化液中の溶存酸素や硝酸等の結合酸素が嫌気性処理ゾーンに流入することになり、嫌気性処理ゾーンの嫌気度合いが低下して汚泥の嫌気的分解が阻害され、汚泥発生量が増加してしまう場合がある。
【０００４】
しかも、硝化液循環による窒素除去を主目的とした嫌気好気処理は１〜１２時間という比較的短時間で行われるが、汚泥発生量の削減を目的とした嫌気処理は１〜２日という比較的長時間で行われるため、従来の各１槽ずつの装置構成で窒素除去と汚泥発生量削減とを同時に満足させることは困難であり、汚泥発生量を削減するためには、汚泥の嫌気的分解を絶対嫌気状態で行う嫌気処理槽を増設するようにしていた。
【０００５】
そこで本発明は、汚泥発生量が少なく、かつ、良好な処理水質が得られるとともに、脱窒処理も問題なく行うことができ、しかも、装置全体の小型化も図れる排水処理装置を提供することを目的としている。
【０００６】
【課題を解決するための手段】
上記目的を達成するため、本発明の排水処理装置は、排水の嫌気好気処理を行う排水処理装置であって、処理槽の下部に設けた絶対嫌気状態で生物処理を行う第一ろ床部と、該第一ろ床部の上部に設けた無酸素状態で生物処理を行う第二ろ床部と、該第二ろ床部の上部に設けた好気状態で生物処理を行う第三ろ床部と、前記第一ろ床部の下方に設けた原水流入部と、処理槽の底部に設けた汚泥濃縮部及び沈殿汚泥抜取部と、前記第三ろ床部の上方に設けた処理水排出部と、前記第三ろ床部の下方に設けた散気手段と、前記第三ろ床部の上方の処理水の一部を抜き出して前記第二ろ床部の下方に流入させる硝化液循環経路とを備え、前記汚泥濃縮部には、沈殿した汚泥を前記沈殿汚泥抜取部に掻き寄せるためのピケットフェンス付の汚泥掻寄機を設けるとともに、前記第一ろ床部には、該第一ろ床部内に充填した生物担体を撹拌するスクリューリボン型の撹拌羽根を設け、前記汚泥掻寄機及び前記撹拌羽根は、処理槽上部に設置したモーターにより駆動される回転軸に取り付けられていることを特徴としている。
【０００７】
さらに、本発明の排水処理装置は、前記第三ろ床部に比重が異なる２種類の生物担体を使用し、下部の流動床と上部の固定床とを形成したことを特徴としている。
【０００８】
【発明の実施の形態】
図１は本発明の排水処理装置の一形態例を示す系統図である。この排水処理装置は、一つの処理槽１０に、底部側から順に、汚泥を濃縮沈殿させるための汚泥濃縮部１１，絶対嫌気状態で生物処理を行う第一ろ床部１２，無酸素状態で生物処理を行う第二ろ床部１３，好気状態で生物処理を行う第三ろ床部１４を適当な仕切材を介して形成したものであって、第一ろ床部１２の下方には原水流入部１５、処理槽底部には沈殿汚泥抜取部１６、第三ろ床部１４の上方には処理水排出部１７及び硝化液循環経路１８の流出部がそれぞれ設けられるとともに、第二ろ床部１３の下方には硝化液循環経路１８の流入部が設けられている。
【０００９】
さらに、前記汚泥濃縮部１１には、沈殿した汚泥を沈殿汚泥抜取部１６に掻き寄せるための汚泥掻寄手段として、ピケットフェンス付の汚泥掻寄機１９が設けられ、第一ろ床部１２には、該第一ろ床部内に充填した生物担体を撹拌する撹拌手段としてスクリューリボン型の撹拌羽根２０が設けられている。この汚泥掻寄機１９と撹拌羽根２０とは、槽上部に設置したモーター２１により駆動される回転軸２２に取り付けられ、ゆっくりとした速度、例えば毎分１〜１０回転程度の速度で、連続的あるいは間欠的、特に、３０分から２時間に１回程度、回転するように形成されている。
【００１０】
また、前記第一ろ床部１２及び第二ろ床部１３には、従来のものに比べて小さなサイズで、かつ、比重を１より僅かに大きく調整した生物担体、例えば、直径２０ｍｍ程度、長さ２０ｍｍ程度、肉厚１ｍｍ程度の中空円筒状の発泡ポリプロピレン製で、比表面積が約５００ｍ^２／ｍ^３であって、比重を約１．０５に調整した生物担体を充填している。このような生物担体を使用することにより、生物を効率よく保持でき、嫌気性処理を効果的に行うことができる状態で、生物担体を下部仕切材上に沈殿させた固定床とすることができる。
【００１１】
一方、前記第三ろ床部１４は、比重が異なる２種類の生物担体を充填し、例えば、直径１０ｍｍ程度、長さ１０ｍｍ程度、肉厚１ｍｍ程度の前記同様の中空円筒状の発泡ポリプロピレン製で、アンスラサイト等のろ材に比べてサイズが大きく、かつ、空隙率も大きく、比表面積が約８００ｍ^２／ｍ^３であって、比重を略１．０、例えば約０．９８に調整した生物担体と、比重を約０．９３に調整した生物担体とを充填し、比重が０．９８の生物担体からなる下部の流動床２３と、比重が約０．９３の生物担体からなる上部の固定床２４とを形成するようにしている。
【００１２】
固定床２４に上述のようなサイズの生物担体を使用することにより、ろ過機能を併せ持たせることができるので、第三ろ床部１４において好気的な生物処理とろ過処理とを同時に行うことができる。また、第三ろ床１４の下方には散気装置２５が設けられており、第三ろ床１４に散気空気を供給して十分な好気性状態を得るとともに、流動床２３の生物担体を流動化させている。
【００１３】
さらに、好気処理水の一部である硝化液を導入する硝化液循環経路１８を前記第二ろ床部１３の下方に設け、一般的な脱窒処理のように硝化液を原水中や嫌気処理槽に循環させるのではなく、第一ろ床部１２より上方に硝化液を循環流入させることにより、硝化液の循環流入によって第一ろ床部１２での嫌気度合いが低下し、嫌気処理効率が低下することを回避できる。同時に、第一ろ床部１２における原水の滞留時間も長くして汚泥の嫌気的分解効果を向上させることができる。
【００１４】
また、第二ろ床部１３の下方で第一ろ床部１２の上方には、第二ろ床部１３及び第三ろ床部１４の空洗用空気を供給する曝気装置２６と、洗浄排水を排出するための洗浄排水流出部２７が設けられている。第二ろ床部１３及び第三ろ床部１４に充填する生物担体として、前述のように、従来のろ材と比較してサイズが大きく、空隙率も大きな生物担体を使用することにより、目詰まりの発生が抑制されるので、生物担体の洗浄頻度を少なくできるとともに、洗浄操作も容易となり、通常は、１〜７日に１回程度の空洗及び排水を行うだけで十分なものとなる。このときの洗浄排水量は、第一ろ床部１２を含めた全体を洗浄する場合に比べて数分の一に低減することができるので、洗浄時間を短縮できるとともに、動力費の削減も図れる。
【００１５】
前記原水流入部１５には、流入原水を整流して汚泥の沈殿を促進するための整流筒２８が設けられており、原水流入部１５から流入した原水は、この整流筒２８によって処理槽底部に向けて緩やかに流入した後、上向流となって処理槽１０内を上昇する。また、処理槽底部に沈殿した汚泥を前記汚泥掻寄機１９で撹拌することにより、沈殿汚泥抜取部１６から汚泥を抜き取る際の水道の形成を防止できるとともに、汚泥の嫌気的分解で発生するメタンや炭酸ガス等のガス成分を速やかに汚泥中から排除することができる。
【００１６】
さらに、前記撹拌羽根２０によって第一ろ床部１２の生物担体を適当に撹拌することにより、第一ろ床部１２で閉塞が発生することを防止でき、第一ろ床部１２を洗浄する必要がなくなる。また、第一ろ床部１２における水理学的滞留時間を２４時間程度にして従来の嫌気性ろ床と同程度にすることにより、効果的な汚泥分解処理を行うことができる。
【００１７】
一方、第二ろ床部１３及び第三ろ床部１４を第一ろ床部１２に比べて小さくすることにより、第二ろ床部１３及び第三ろ床部１４での処理時間を１〜１２時間にして効果的な窒素除去を行えるとともに、第二ろ床部１３及び第三ろ床部１４の洗浄設備を簡易にでき、しかも、処理槽全体の小型化が図れる。
【００１８】
このような処理槽１０を有する排水処理設備において、下水等の原水は、沈砂地５１で沈砂処理及びスクリーン処理されて流量調整槽５２に流入し、ポンプ５３によりある程度の流量調整が行われて原水流入部１５から整流筒２８を通って処理槽１０の汚泥濃縮部１１に流入する。原水中の汚泥は、一部が汚泥濃縮部１１で沈殿分離され、残部が原水とともに槽内を上昇して第一ろ床部１２に流入し、第一ろ床部１２での絶対嫌気状態における嫌気性生物処理によって嫌気的に分解される。
【００１９】
第一ろ床部１２を出た原水は、硝化液循環経路１８から循環流入する硝化液と混合して第二ろ床部１３に流入し、ここでの無酸素状態における生物処理によって主として脱窒処理が行われる。脱窒処理後の原水は、第二ろ床部１３から出て散気装置２５からの散気空気と共に上部の第三ろ床部１４に流入し、この第三ろ床部１４で好気状態における生物処理によって主として硝化処理が行われるとともにろ過処理が行われる。
【００２０】
さらに、第三ろ床部１４の好気性生物処理により、第一ろ床部１２での汚泥の分解によって発生したアンモニアや硫化水素、硫化物等を酸化して悪臭や腐食性ガスの発生を抑えることもできるので、脱臭設備や防食対策の簡素化を図ることができる。
【００２１】
このようにして処理された処理水は、第三ろ床部１４の上方から処理水排出部１７を通って滅菌槽５４に流出し、最終的に固形塩素剤等により滅菌処理されてから河川等に放流される。また、第三ろ床部１４上方の処理水の一部は、ポンプ５５により硝化液循環経路１８に引き抜かれて硝化液として循環する。
【００２２】
さらに、汚泥濃縮部１１で沈殿した汚泥は、ポンプ５６によって沈殿汚泥抜取部１６から定期的に引き抜かれ、汚泥貯留槽５７に一端貯留された後、バキューム車による搬出や脱水処理が行われる。汚泥の引き抜きに際しては、汚泥掻寄機１９によって沈殿汚泥を掻き寄せることにより、汚泥を高濃度で引き抜くことが可能となる。
【００２３】
第三ろ床部１４に充填した生物担体の洗浄操作は、各ポンプ５３，５５，５６を停止し、処理水排出部１７の弁５８を閉じるとともに、散気装置２５のコンプレッサー５９を停止した状態で、曝気装置２６のブロワ６０を運転して生物担体を曝気撹拌する空洗操作と、空洗操作終了後に洗浄排水流出部２７の弁６１を開いて洗浄排水を流量調整槽５２に戻す排水操作とによって行われ、洗浄排水は流量調整槽５２で原水に混合し、処理槽１０で再び処理される。
【００２４】
このように、生物担体の洗浄操作を空洗と排水とで行い、逆洗を不要としたことにより、洗浄排水量を大幅に減少できるとともに、逆洗ポンプや洗浄用水槽等が不要となり、洗浄設備の簡素化を図れる。
【００２５】
なお、前記硝化液の一部を汚泥濃縮部１１や第一ろ床部１２に適当量流入させることにより、これらのゾーンにおけるｐＨの低下やＯＲＰの低下を防止できるとともに、ＯＰＲを−１００〜−２００ｍＶ程度に維持することによって硫化水素発生量の低減も図れる。また、流入原水にポリ鉄等の鉄系凝集剤を添加することにより、汚泥の嫌気的分解や硝化反応を阻害することなく、リン凝集によるリンの除去を行うことができる。さらに、本形態例では、好気性生物処理を行う第三ろ床部１４を下部の流動床２３と上部の固定床２４とで形成したが、第三ろ床部全体を固定床や流動床としてもよい。
【００２６】
【発明の効果】
以上説明したように、本発明の排水処理装置によれば、汚泥の発生量を少なくしながら良好な処理水質を得ることができる。また、汚泥濃縮部、第一ろ床部、第二ろ床部及び第三ろ床部を一つの処理槽にまとめているので、装置全体の小型化が図れる。
【図面の簡単な説明】
【図１】本発明の排水処理装置の一形態例を示す系統図である。
【符号の説明】
１０…処理槽、１１…汚泥濃縮部、１２…第一ろ床部、１３…第二ろ床部、１４…第三ろ床部、１５…原水流入部、１６…沈殿汚泥抜取部、１７…処理水排出部、１８…硝化液循環経路、１９…汚泥掻寄機、２０…撹拌羽根、２１…モーター、２２…回転軸、２３…流動床、２４…固定床、２５…散気装置、２６…曝気装置、２７…洗浄排水流出部、２８…整流筒、５１…沈砂地、５２…流量調整槽、５４…滅菌槽、５７…汚泥貯留槽[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wastewater treatment apparatus, and more particularly, is a wastewater treatment apparatus based on a biological filter that combines anaerobic treatment and aerobic treatment, and in particular, obtains good treated water quality and reduces sludge generation. It relates to a wastewater treatment apparatus that can be achieved.
[0002]
[Prior art]
Conventionally, anaerobic aerobic treatment using a biological filter method combining anaerobic treatment and aerobic treatment has been widely performed as a means of wastewater treatment. This anaerobic aerobic treatment is a combination of the characteristics that good treated water quality can be obtained in a relatively short time in the aerobic biological treatment and the characteristic that sludge generation in the anaerobic biological treatment is small. In addition, it has the advantages that a high quality of treated water is obtained, the amount of sludge generated is relatively small, and the power cost is low.
[0003]
[Problems to be solved by the invention]
However, a conventional wastewater treatment apparatus that performs anaerobic aerobic treatment needs to use a large-sized contact material to prevent clogging in an anaerobic filter bed that performs anaerobic biological treatment. There was also a problem that it could not be retained, and that it was impossible to effectively extract the precipitated sludge. In addition, an aerobic filter bed that performs aerobic biological treatment generally uses a filter medium such as anthracite having a diameter of about 3 to 5 mm, so that there is a problem that it requires cleaning once a day. It was. Furthermore, when the treated water that has been subjected to aerobic treatment for denitrification treatment is circulated to the anaerobic treatment zone as a nitrification solution, dissolved oxygen, nitric acid, and other bound oxygen in the nitrification solution flow into the anaerobic treatment zone. In other words, the anaerobic degree of the anaerobic treatment zone is lowered, the anaerobic decomposition of the sludge is inhibited, and the sludge generation amount may increase.
[0004]
In addition, anaerobic aerobic treatment mainly aimed at removing nitrogen by nitrifying liquid circulation is performed in a relatively short time of 1 to 12 hours, but anaerobic treatment aimed at reducing sludge generation is a comparison of 1 to 2 days. Therefore, it is difficult to satisfy both nitrogen removal and sludge generation reduction at the same time with the conventional system configuration of each tank. To reduce sludge generation, sludge is anaerobic. An anaerobic treatment tank that performs decomposition in an absolute anaerobic state was added.
[0005]
Accordingly, the present invention provides a wastewater treatment apparatus that produces a small amount of sludge and that can provide good treated water quality, can perform denitrification without problems, and can reduce the overall size of the apparatus. It is aimed.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the wastewater treatment apparatus of the present invention is a wastewater treatment apparatus that performs anaerobic and aerobic treatment of wastewater, and is a first filter bed that performs biological treatment in an absolute anaerobic state provided in the lower part of the treatment tank. A second filter bed for performing biological treatment in an oxygen-free state provided at the upper part of the first filter bed, and a third filter for performing biological treatment in an aerobic condition provided at the upper part of the second filter bed. A raw water inflow part provided below the floor part, the first filter bed part, a sludge concentration part and a precipitated sludge extraction part provided at the bottom part of the treatment tank, and a treated water provided above the third filter bed part A nitrification liquid that draws a part of the treated water above the third filter bed and flows into the lower part of the second filter bed by discharging a discharge unit, an air diffuser provided below the third filter bed and a circulation path, the sludge in the rectifying section, the precipitated sludge sludge raking machine with picket fence to scrape the settled sludge draw-off unit The first filter bed is provided with a screw ribbon type stirring blade that stirs the biological carrier filled in the first filter bed, and the sludge scraper and the stirring blade are disposed at the upper part of the treatment tank. It is characterized by being attached to a rotating shaft driven by an installed motor .
[0007]
Furthermore, waste water treatment apparatus of the present invention uses two kinds of biological carrier specific gravity different from the third filter bed unit is characterized that you formed a fixed bed of the lower portion of the fluidized bed and the top.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a system diagram showing an embodiment of the waste water treatment apparatus of the present invention. This waste water treatment apparatus is arranged in one treatment tank 10 in order from the bottom side, a sludge concentration part 11 for concentrating and precipitating sludge, a first filter bed part 12 for biological treatment in an absolute anaerobic state, and an organism in an oxygen-free state. A second filter bed 13 for performing treatment and a third filter bed 14 for performing biological treatment in an aerobic state are formed through appropriate partition materials, and raw water is disposed below the first filter bed 12. An inflow portion 15, a sedimentation sludge extraction portion 16 at the bottom of the treatment tank, and an outflow portion of the treated water discharge portion 17 and the nitrification liquid circulation path 18 are provided above the third filter bed portion 14, respectively, and a second filter bed portion Below 13, an inflow portion of the nitrification liquid circulation path 18 is provided.
[0009]
Further, the sludge concentrating section 11 is provided with a sludge scraping machine 19 with a picket fence as a sludge scraping means for scraping the settled sludge to the precipitated sludge extraction section 16. Is provided with a screw ribbon type stirring blade 20 as a stirring means for stirring the biological carrier filled in the first filter bed. The sludge scraper 19 and the stirring blade 20 are attached to a rotating shaft 22 driven by a motor 21 installed in the upper part of the tank, and continuously at a slow speed, for example, about 1 to 10 revolutions per minute. Alternatively, it is formed to rotate intermittently, particularly about once every 30 minutes to 2 hours.
[0010]
The first filter bed portion 12 and the second filter bed portion 13 have a size smaller than that of the conventional one and a specific gravity adjusted slightly larger than 1, for example, a diameter of about 20 mm, long It is made of a hollow cylindrical foamed polypropylene having a thickness of about 20 mm and a thickness of about 1 mm, and is filled with a biological carrier having a specific surface area of about 500 m ² / m ³ and a specific gravity of about 1.05. By using such a biological carrier, it is possible to obtain a fixed bed in which the biological carrier is precipitated on the lower partition material in a state where the organism can be efficiently held and an anaerobic treatment can be effectively performed. .
[0011]
On the other hand, the third filter bed portion 14 is filled with two types of biological carriers having different specific gravities, and is made of, for example, the same hollow cylindrical foamed polypropylene having a diameter of about 10 mm, a length of about 10 mm, and a wall thickness of about 1 mm. A biological carrier having a size larger than that of a filter medium such as anthracite, a large porosity, a specific surface area of about 800 m ² / m ³ , and a specific gravity adjusted to about 1.0, for example, about 0.98 And a lower fluidized bed 23 made of a biological carrier having a specific gravity of about 0.93, and an upper fixed bed made of a biological carrier having a specific gravity of about 0.93. 24 are formed.
[0012]
By using a biological carrier of the size described above for the fixed bed 24, it is possible to have a filtration function, so that the aerobic biological treatment and the filtration treatment are simultaneously performed in the third filter bed 14. Can do. In addition, an air diffuser 25 is provided below the third filter bed 14, and a diffused air is supplied to the third filter bed 14 to obtain a sufficient aerobic state. Fluidized.
[0013]
Further, a nitrification solution circulation path 18 for introducing a nitrification solution that is a part of the aerobic treatment water is provided below the second filter bed 13, and the nitrification solution is fed into the raw water or anaerobic as in general denitrification treatment By circulating the nitrification liquid above the first filter bed 12 rather than circulating it to the treatment tank, the anaerobic degree in the first filter bed 12 is reduced by the circulation inflow of the nitrification liquid, and the anaerobic treatment efficiency Can be avoided. At the same time, the residence time of the raw water in the first filter bed 12 can be lengthened to improve the sludge anaerobic decomposition effect.
[0014]
Also, an aeration device 26 for supplying air for washing the second filter bed 13 and the third filter bed 14 below the second filter bed 13 and above the first filter bed 12, and washing waste water A washing drainage outlet 27 is provided for discharging the waste water. As described above, the biological carrier filled in the second filter bed portion 13 and the third filter bed portion 14 is clogged by using a biological carrier that is larger in size and has a higher porosity than the conventional filter media. Since generation | occurrence | production of this is suppressed, the washing | cleaning frequency of a biological carrier can be decreased, and also washing | cleaning operation becomes easy, and it will become sufficient normally only to perform about 1-7 days of washing and draining. Since the amount of waste water for washing at this time can be reduced to a fraction of that in the case where the entire first filter bed 12 is washed, the washing time can be shortened and the power cost can be reduced.
[0015]
The raw water inflow section 15 is provided with a rectifying cylinder 28 for rectifying the inflow raw water and promoting the sedimentation of sludge. The raw water flowing in from the raw water inflow section 15 is fed to the bottom of the treatment tank by the rectification cylinder 28. After gently flowing in, the flow rises upward in the processing tank 10. In addition, by stirring the sludge precipitated at the bottom of the treatment tank with the sludge scraper 19, it is possible to prevent the formation of water when extracting the sludge from the precipitated sludge extractor 16, and to generate methane generated by anaerobic decomposition of the sludge. And gas components such as carbon dioxide can be quickly removed from the sludge.
[0016]
Further, by properly stirring the biological carrier in the first filter bed 12 by the stirring blade 20, it is possible to prevent the first filter bed 12 from being clogged, and the first filter bed 12 needs to be washed. Disappears. Moreover, an effective sludge decomposition treatment can be performed by setting the hydraulic residence time in the first filter bed 12 to about 24 hours and the same as that of a conventional anaerobic filter bed.
[0017]
On the other hand, by making the second filter bed part 13 and the third filter bed part 14 smaller than the first filter bed part 12, the processing time in the second filter bed part 13 and the third filter bed part 14 is reduced to 1 to 1. Effective nitrogen removal can be performed in 12 hours, the cleaning equipment for the second filter bed 13 and the third filter bed 14 can be simplified, and the entire treatment tank can be downsized.
[0018]
In the wastewater treatment facility having such a treatment tank 10, raw water such as sewage is subjected to sand settling and screen treatment in the sand settling ground 51 and flows into the flow rate adjusting tank 52, and a certain amount of flow rate adjustment is performed by the pump 53. It flows into the sludge concentration part 11 of the treatment tank 10 from the inflow part 15 through the flow straightening cylinder 28. Part of the sludge in the raw water is precipitated and separated in the sludge concentrating part 11, and the remainder rises in the tank together with the raw water and flows into the first filter bed 12, in an absolute anaerobic state in the first filter bed 12. Degraded anaerobically by anaerobic biological treatment.
[0019]
The raw water that has exited the first filter bed 12 is mixed with the nitrifying liquid circulating and flowing from the nitrating liquid circulation path 18 and flows into the second filter bed 13, where it is mainly denitrified by biological treatment in an oxygen-free state. Processing is performed. The raw water after the denitrification process exits from the second filter bed 13 and flows into the upper third filter bed 14 together with the diffused air from the diffuser 25 and is in an aerobic state at the third filter bed 14. Nitrogen treatment is mainly performed and biological treatment is performed by biological treatment.
[0020]
Furthermore, the aerobic biological treatment of the third filter bed 14 oxidizes ammonia, hydrogen sulfide, sulfide, etc. generated by the sludge decomposition in the first filter bed 12 to suppress the generation of malodor and corrosive gas. Therefore, it is possible to simplify deodorization equipment and anticorrosion measures.
[0021]
The treated water treated in this way flows out from the upper part of the third filter bed 14 through the treated water discharge part 17 to the sterilization tank 54 and is finally sterilized with a solid chlorine agent etc. To be released. Further, a part of the treated water above the third filter bed 14 is drawn out by the pump 55 to the nitrification liquid circulation path 18 and circulated as a nitrification liquid.
[0022]
Further, the sludge precipitated in the sludge concentration unit 11 is periodically extracted from the precipitated sludge extraction unit 16 by the pump 56 and once stored in the sludge storage tank 57, and then carried out by a vacuum car and dewatering treatment. When the sludge is pulled out, the sludge can be pulled out at a high concentration by scraping the precipitated sludge with the sludge scraper 19.
[0023]
In the operation of washing the biological carrier filled in the third filter bed 14, the pumps 53, 55, 56 are stopped, the valve 58 of the treated water discharge unit 17 is closed, and the compressor 59 of the air diffuser 25 is stopped. Then, an air washing operation in which the blower 60 of the aeration device 26 is operated to aerate and agitate the biological carrier, and a drainage operation in which the valve 61 of the washing drainage outlet 27 is opened after the air washing operation is finished to return the washing wastewater to the flow rate adjustment tank 52. The cleaning waste water is mixed with the raw water in the flow rate adjusting tank 52 and processed again in the processing tank 10.
[0024]
In this way, the washing operation of the biological carrier is performed by washing with air and draining, and back washing is not required, so that the amount of washing waste water can be greatly reduced, and a back washing pump, a washing water tank, etc. are no longer needed, and the washing equipment Can be simplified.
[0025]
In addition, by flowing a part of the nitrating solution into the sludge concentration unit 11 and the first filter bed unit 12 in an appropriate amount, it is possible to prevent a decrease in pH and a decrease in ORP in these zones, and an OPR of −100 to − By maintaining the pressure at about 200 mV, the amount of hydrogen sulfide generated can be reduced. Further, by adding an iron-based flocculant such as polyiron to the inflow raw water, phosphorus can be removed by agglomeration without inhibiting anaerobic decomposition and nitrification reaction of sludge. Furthermore, in this embodiment, the third filter bed 14 for performing the aerobic biological treatment is formed by the lower fluidized bed 23 and the upper fixed bed 24, but the entire third filter bed may be used as a fixed bed or a fluidized bed. Good.
[0026]
【The invention's effect】
As described above, according to the waste water treatment apparatus of the present invention, it is possible to obtain good treated water quality while reducing the amount of sludge generated. Moreover, since the sludge concentration part, the 1st filter bed part, the 2nd filter bed part, and the 3rd filter bed part are put together in one processing tank, size reduction of the whole apparatus can be achieved.
[Brief description of the drawings]
FIG. 1 is a system diagram showing an example of a wastewater treatment apparatus according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Treatment tank, 11 ... Sludge concentration part, 12 ... First filter bed part, 13 ... Second filter bed part, 14 ... Third filter bed part, 15 ... Raw water inflow part, 16 ... Precipitation sludge extraction part, 17 ... Treated water discharge unit, 18 ... nitrification liquid circulation path, 19 ... sludge scraper, 20 ... stirring blade, 21 ... motor, 22 ... rotating shaft, 23 ... fluidized bed, 24 ... fixed bed, 25 ... air diffuser, 26 ... Aeration apparatus, 27 ... Washing drainage part, 28 ... Rectifying cylinder, 51 ... Sedimentation ground, 52 ... Flow rate adjustment tank, 54 ... Sterilization tank, 57 ... Sludge storage tank

Claims

A wastewater treatment apparatus that performs anaerobic aerobic treatment of wastewater, a first filter bed that performs biological treatment in an absolute anaerobic state provided in the lower part of the treatment tank, and an oxygen-free provided in the upper part of the first filter bed A second filter bed that performs biological treatment in a state; a third filter bed that performs biological treatment in an aerobic state provided above the second filter bed; and a lower portion of the first filter bed. A raw water inflow part, a sludge concentration part and a sediment sludge extraction part provided at the bottom of the treatment tank, a treated water discharge part provided above the third filter bed, and a lower part of the third filter bed A diffusing means and a nitrification liquid circulation path for extracting a part of the treated water above the third filter bed and allowing it to flow below the second filter bed , precipitated in the sludge concentration section. A sludge scraper with a picket fence for scraping the sludge to the sedimented sludge extraction section is provided, and the first filter bed is provided with the first filter bed. The stirring blade of the screw ribbon stirring the biological carrier packed within provided, the sludge raking machine and the stirring blade is characterized by being mounted on a rotating shaft driven by installed motors in the processing tank top Wastewater treatment equipment.

The wastewater treatment apparatus according to claim 1, wherein two biological carriers having different specific gravities are used for the third filter bed to form a lower fluidized bed and an upper fixed bed.