JP3752603B2

JP3752603B2 - Biofilm treatment method for wastewater

Info

Publication number: JP3752603B2
Application number: JP26201294A
Authority: JP
Inventors: 榮一田代
Original assignee: 榮一田代
Priority date: 1993-09-30
Filing date: 1994-09-30
Publication date: 2006-03-08
Anticipated expiration: 2021-03-08
Also published as: JPH07251187A

Description

【０００１】
【産業上の利用分野】
本発明は、厨房排水や食品加工工場等の含油排水や含澱粉排水、或いは合併槽排水、下水その他高濃度の油分やＳＳの混入が避けられない排水を、油分やＳＳ除去工程を経ずにそのまま接触濾材槽に導入して処理する、生物処理法の改良に関する。
【０００２】
【従来の技術】
生物膜処理法とは排水の生物処理法の一種であり、槽や塔内に収納した接触濾材表面に生物膜を形成させ、この生物膜で排水中の有機物を処理するものである。生物膜処理法には、接触曝気、回転接触曝気、嫌気性浸漬濾床、撒水濾床など幾つかの方法があるがこの中で現在最も広く用いられているのは、接触曝気法である。これは、曝気槽内にプラスチック製の板や紐その他の接触材を固定し或いは浮遊させ、下方から曝気することによって接触材表面に生物膜を形成させるものである。そして、この生物膜が効率良く排水中の有機物を処理するので、ＢＯＤ容積負荷が活性汚泥法の５倍前後もあり極めて効率のよい排水処理方法である。しかし、元々はＢＯＤが低く水量の多い場合に有利な処理法であり、３次処理に使用されていた。そして、ここ数年らい、ＢＯＤ容積負荷が高い点に着目して１次処理や２次処理にも使用されるようになった。また、回転接触曝気法や嫌気性浸漬濾床、撒水濾床なども、ＢＯＤ容積負荷が高い処理方法である。
【０００３】
ところが、接触曝気法は排水中に油分が多く含まれていると、接触濾材やその上に付着している生物膜に油分が付着してその活動を妨げ、甚だしい場合には水や空気の通路を閉塞してしまって、処理不能に陥る難点がある。ＳＳ分が多い場合も、同様に接触濾材や生物膜の表面に付着し、ついには水や空気の通路を閉塞してしまって、処理不能に陥いらせる。これは、元来ＳＳや油分に弱い接触曝気法の欠点に気が付かなかったことによる。尚この問題は、接触曝気法に限らず浸漬濾床法（接触曝気法において曝気をせずに嫌気状態で処理する方法）や、接触濾材の上から水を撒水する撒水濾床法、円盤や円盤状網を水中に半埋没状態で回転させる回転接触曝気法など、接触濾材を用いる排水処理の場合に、常に付きまとう問題である。
【０００４】
そこで、接触濾材による生物膜処理に先立って、排水中の油分含有量を低下させることが行なわれるようになった。その程度は、接触曝気法の場合はノルマルヘキサン抽出物として１０ppm 程度、余程良好に運転管理しても２０ppm が上限とされる。他の処理法の場合も大同小異である。そして、この油分の除去は、現在では殆どが加圧浮上によって行われている。小規模排水の場合にはグリストラップも用いられるが、加圧浮上処理の場合は、同時にＳＳ分も除去できる利点がある。
【０００５】
【発明が解決しようとする課題】
しかし、この加圧浮上処理は多量の凝集剤を必要とするし、動力費もかかるうえに曝気された空気が悪臭を発散させるし、分離した油分が腐敗して悪臭を放つとかその処理に手間がかかるなど極めて問題のあるものである。尚、接触曝気法の場合は、それ自体が微生物の活発な活動を助けるために大量の酸素を必要として動力を消費するし、発生する汚泥も活性汚泥法に比べて多く、その処理も大きな負担になる。
【０００６】
更に加圧浮上の最大の難点は、油分（ＳＳも）を十分に除去出来ないことである。従来から、長時間曝気したり大量の凝集剤を投入してできるだけ低下させるようにしているが、１０ppm はおろか３０ppm 以下にすることすら至難の技である。従って、接触濾材が油分やＳＳに覆われたり、通路が閉塞したりして処理不能に陥ることが多いが、そのような場合には接触濾材を除去してしまうしか方法がない。この場合、接触濾材を再度設置できればよいが多くの場合不可能であり、接触濾材のないままに排水の処理が行われ、処理が不十分なまま排出される結果となる。
【０００７】
【発明が解決しようとする課題】
以上のような現状に鑑み、本発明者は鋭意研究の結果本発明方法を完成させたものであり、その特徴とするところは、排水中から油分及びＳＳの除去を行わずに或いは余り行わずに、サポニン含有剤を添加した状態で排水を接触濾材槽に導入し、そのまま生物膜処理を行う点にある。
【０００８】
ここで、排水とは、生活排水、工業排水等を含む被処理水すべてを言うが、特に油分を多く含む排水を主たる対象とする。例えば、外食産業や食品加工工場等の排水であり、家庭からの雑排水も多くの油分を含む。また油分とは、ノルマルヘキサン抽出物（ノルヘキ成分）のことを言う。ノルヘキ成分の処理水での水質基準は数ppm といわれているが、食品加工工場や外食産業からの排水中には６００〜７００ppm も含まれていることがある。また、油分は比較的少ないがＳＳが多く含まれる排水たとえば製麺工場など澱粉を多く含む排水、油分もＳＳも共に多く含まれる排水も本発明の好適な処理対象となる。
【０００９】
次に、接触曝気法とは、曝気槽の中に鉱物、プラスチック、木材その他の板状や紐状、粒状などの接触濾材を設置し、或いは浮遊させ、下方或いは側方からエアレーションして処理する方法を言う。浮遊性のものとしては、プラスチック空容器、コルク、発砲スチロール、活性炭、バーミキュライト、パルプ屑、籾殻、おが屑等が用いられるが、これらが曝気で攪拌されるので流動濾床法とも言われる。また、これらを充填した槽に、上方から排水を散布するのが撒水濾床法である。尚、接触曝気法と同様な構造において曝気をしないものを嫌気性浸漬濾床法と言う。接触回転曝気法とは、円盤状の板や網、或いはプラスチック空容器等を収納した容器等を、被処理水中に半浸漬状態にして回転させるもので、好気、嫌気の両状態で処理するものを言う。これらはいずれも本発明に適用できるものである。これらの処理によって、次第に接触濾材の表面に微生物のコロニーができ、有機物質を効率良く処理するようになる。
【００１０】
ここにサポニンとは、植物体に含有される配糖体の一種で、セッケンのように著しくアワ立つコロイド水溶液を作るものの総称であり、多くの植物から見出されている。本発明では用いるサポニンの種類は問わないが、コストや安定供給の点から、植物体中の含有量が多く且つその植物が大量に存在し安定して入手できるものが好ましい。この観点から、キラヤサポニンやユッカ、なぎいかだ、大豆、砂糖大根等から得られるサポニンが好ましい。この内特に、南米のチリー、ボリビア、ペルー等に自生するシャボンの木（学名：Quilaia saponaria Mol.バラ科）から抽出したキラヤサポニンが好適である。これは、化１の構造を有するキラヤ酸をアグリコン（配糖体の非糖質部分）とするトリテルペン系の配糖体であり化２で表わされもので、構造及び分析技術が解明されている数少ないサポニンであるし、比較的サポニン含有濃度の高い抽出液が得られることによる。
【化１】

【化２】

【００１１】
サポニン含有剤は、植物体から抽出した抽出液（溶媒を含む）をそのまま用いてもよく、それを精製したもの自体でもよい。抽出の方法は通常の方法でよく、エタノール等の低級アルコール等で抽出できる。更に、精製物や抽出液を粉状、顆粒状、又は錠剤に加工したものも用いられる。
【００１２】
ところで、本発明者はサポニンが汚水の生物学的処理工程に有効であることを見出したが、これはサポニンが配糖体であるため微生物の栄養分となり、酸素含有量が多いこととあいまって微生物の繁殖を助ける結果、処理効率が向上するものと推察されている。そこで、本発明者は本発明においても接触曝気槽にサポニン含有剤を供給してその状況を数ケ月にわって観察したところ、接触曝気槽中の生物層に変化がみられ、５００ppm 以上の油分を充分に処理するようになった。但し、油分の分解物質が残るのか処理水中のＢＯＤやＣＯＤは幾分の上昇を見た。他の処理法の場合も、同様に良好な結果が得られた。
【００１３】
サポニン含有剤の添加量は、排水中の油分の濃度によって異なるが、通常は、排水に対して精製物換算で0.01〜1.0 ppm 、特に0.１２〜0.4 ppm （含有量４％液として、３〜１０ppm ）程度である。添加は、液状サポニン含有剤の場合定量ポンプで常時滴下する等の方法を採るとよい。錠剤や顆粒剤等の固型剤の場合は、適量を適宜間隔をおいて投入するとよい。また、サポニン含有剤の添加箇所は、当初は接触濾材槽に直接投入するが、安定状態（２〜３ケ月）になれば、調整槽に投入する方が良好な結果が得られる。
【００１４】
尚、本発明は排水の生物学的処理工程において、２次処理にでも３次処理にでも使用できるものである。場合によっては、１次処理にも使用できる。
【００１５】
【実施例】
（実施例１）
次に、本発明を図面に示す一実施例に基づいて詳細に説明する。図１は、或る食品加工工場の排水処理施設のフローチャート（接触曝気法を採用）である。排水量は２５０トン／日で、従来から処理水の水質は安定していて問題はなかった。しかし、油分が多い（５００ppm ）ため、加圧浮上処理により油分を除去し、曝気槽へ送り込む排水中の油分は１０ppm を目標に調整していた。しかし、現実には６０ppm 以下には下がらず、接触曝気槽の処理能力が低下していった。尚、発生する浮上フロスを余剰汚泥として脱水処分しているが、脱水ケーキの発生量が約0.５トン／日となり、処分費が高くついていた。しかも、加圧浮上用の凝集剤や脱水用凝集剤の費用、加圧浮上に要する電気代等を勘案するとかなりのランニングコストになっていた。
【００１６】
そこで、キラヤサポニン含有剤を１日１回処理水量に対して３ppm （サポニン含有量４％液の場合）添加した。この添加は、図１の曝気槽に行った。投入から１〜２ケ月間は、当初微生物が増加し、次第に曝気槽の生物層が変化して、原生動物（良好な処理槽に多く見られる）の現出が観察されるようになった。しかし、処理に要する費用は以前とかわらず、ただサポニン含有剤の費用が上積みされた程度であった。３ケ月目からは、曝気槽において形成されるフロックが大きくなり、良好時に発生する原生動物や微生物が多く観察されるようになった。それとともに、投入する排水中の油分の濃度を上げたため（５０〜３００ppm ）、加圧浮上に要する薬剤や脱水用薬剤及び脱水ケーキ処分費が次第に低下してきて、サポニン含有剤の費用を加えても当初より低コストになってきた。
【００１７】
３ケ月後から加圧浮上装置の使用を停止し、図２に示すように排水を調整槽から直接曝気槽に投入するようにした。そして、均一な添加をするために、サポニン含有剤をこの調整槽に投入するようにした。その結果、油分の回収に要する手間や費用が大幅に軽減されるとともに、悪臭も減って作業環境が向上した。また浮上フロスがなくなり、余剰汚泥として搬出していた量が減少したうえ、脱水し易くなるので脱水用凝集剤の使用量も大幅に減少した。そのため、余剰汚泥の処理費、脱水用薬品の大幅な費用の削減ができた。勿論、処理水の水質も安定している。しかも、微生物が活発に活動するので本来はＤＯ（溶存酸素）が不足気味になるはずであるが、サポニン含有剤には溶存酸素増加効果があるので、かえって送気量を減少させることができ、その点においてもコストの低下が図られた。
【００１８】
このような結果が生じたのは、油分がサポニン含有剤によって乳化され、バクテリアによって分解されやすい状態になったこと、またバクテリアの活性化が図れてこの乳化された油分及びＳＳ分（デンプン質等）が効率良く分解されたことによると思われる。
【００１９】
但し、油分が大量に消化されるので、その残分としてのＢＯＤやＣＯＤは、下記に示すように幾分増加した。しかし、その量は排水基準の範囲内に収まっている。
投入前（平均） mg／ｌ
ＢＯＤＣＯＤＳＳノルヘキ成分
原水 1,０００２６５４０３５００ppm
加圧浮上後７２４２３０３６０６０
処理水 3.７５１２ 9.３１０
投入後（平均） mg／ｌ
ＢＯＤＣＯＤＳＳノルヘキ成分
処理水 4.7 ５１4.１ 6.８２〜３ppm
【００２０】
（実施例２）
あるサービスエリアで、７０ｍ³ ／日の厨房排水を加圧浮上した後に嫌気性浸漬濾床槽で処理していたところ、油分の除去が不十分なため接触濾材が油分で目詰まり起こし、ついには濾材が持ち上がって全く処理槽の体をなさない状態になっていた。この厨房排水は、平均でＢＯＤが５５０ppm 、油分が１００〜１５０ppm であり、処理水はＢＯＤが１００、油分が５０程度であった。
【００２１】
この状態で、接触濾材を交換して加圧浮上装置を外し、サポニン含有剤を３〜５ppm 投入し続けて２ケ月程度経過したところ、処理水はＢＯＤが１５ppm 、油分（ノノルマルヘキサン抽出物）が５ppm 程度と安定した処理が行なえるようになった。
【００２２】
【発明の効果】
以上、詳細に説明した本発明には、次のような大きな利点がある。
1) 接触曝気法など接触濾材槽を使用する排水処理方法の大きなネックであった油分やＳＳの除去が不要になり、これに費やしていた手間や費用が削減され、排水処理費は、サポニン含有剤の使用前に比べてほぼ半減した。
2) 活性汚泥も絶対量が減少（約３／１）し、併せて凝集剤の使用量も１／３になり、汚泥処理費が減少した。
3) 悪臭に曝され、取り扱いにくい油分の塊の処理が不要になるので、作業環境が大幅に改善される。
【図面の簡単な説明】
【図１】従来の接触曝気法を基にしたサポニン含有剤の使用開始当初の本発明による排水処理のフローチャートの一例を示す。
【図２】安定期における本発明の接触曝気法による排水処理のフローチャートの一例を示す。[0001]
[Industrial application fields]
The present invention provides oil-containing wastewater such as kitchen wastewater and food processing plants, starch-containing wastewater, combined tank wastewater, sewage and other wastewater that cannot be mixed with high-concentration oil or SS without oil and SS removal process. The present invention relates to an improvement of a biological treatment method in which it is directly introduced into a contact filter medium tank and processed.
[0002]
[Prior art]
The biofilm treatment method is a kind of wastewater biotreatment method, in which a biofilm is formed on the surface of a contact filter medium housed in a tank or a tower, and organic matter in the wastewater is treated with this biofilm. There are several biofilm treatment methods, such as contact aeration, rotary contact aeration, anaerobic submerged filter bed, and submerged filter bed. Among them, the contact aeration method is most widely used at present. In this method, a plastic plate, string or other contact material is fixed or floated in the aeration tank, and a biofilm is formed on the surface of the contact material by aeration from below. And since this biofilm efficiently treats organic matter in the wastewater, the BOD volumetric load is about five times that of the activated sludge method, which is an extremely efficient wastewater treatment method. However, it was originally an advantageous treatment method when the BOD was low and the amount of water was large, and was used for the tertiary treatment. In recent years, it has come to be used for primary processing and secondary processing, paying attention to the high BOD volumetric load. In addition, a rotating contact aeration method, an anaerobic submerged filter bed, a submerged filter bed, etc. are also processing methods with a high BOD volume load.
[0003]
However, in the contact aeration method, if a lot of oil is contained in the waste water, the oil adheres to the contact filter medium and the biofilm adhering to it, hindering its activity. There is a difficulty that it is blocked, and can not be processed. Even when there is a lot of SS, it adheres to the surface of the contact filter medium or biofilm, and eventually blocks the passage of water or air, making it impossible to process. This is because the defect of the contact aeration method that is inherently weak against SS and oil is not noticed. In addition, this problem is not limited to the contact aeration method, but is a submerged filter bed method (a method of treating in an anaerobic state without aeration in the contact aeration method), a submerged filter bed method in which water is submerged from the contact filter medium, This is always a problem with wastewater treatment using contact filter media, such as a rotating contact aeration method in which a disk-shaped net is rotated in a semi-buried state.
[0004]
Therefore, prior to the biofilm treatment with the contact filter medium, the oil content in the waste water has been reduced. In the case of the contact aeration method, the upper limit is about 10 ppm as a normal hexane extract, and 20 ppm is the upper limit even if the operation is managed so well. The other processing methods are also the same. And most of the removal of this oil is carried out by pressure levitation at present. In the case of small-scale drainage, grease traps are also used, but in the case of pressurized levitation treatment, there is an advantage that SS can be removed at the same time.
[0005]
[Problems to be solved by the invention]
However, this pressurized flotation process requires a large amount of flocculant, power costs, and the aerated air emits a bad odor, and the separated oil rots and gives off a bad odor. Is extremely problematic. In the case of the contact aeration method, a large amount of oxygen is required to support the active activity of microorganisms, and power is consumed. The amount of generated sludge is larger than that of the activated sludge method, and the treatment is also a heavy burden. become.
[0006]
Furthermore, the biggest difficulty in levitation is that oil (SS) cannot be removed sufficiently. Conventionally, aeration is performed for a long time or a large amount of aggregating agent is added to reduce the amount as much as possible. However, it is extremely difficult to reduce 10 ppm to 30 ppm or less. Therefore, the contact filter medium is often covered with oil or SS, or the passage is blocked, so that the treatment cannot be performed. In such a case, there is only a method of removing the contact filter medium. In this case, it is sufficient if the contact filter medium can be installed again, but in many cases it is impossible. As a result, wastewater is treated without the contact filter medium, and the process is discharged with insufficient treatment.
[0007]
[Problems to be solved by the invention]
In view of the present situation as described above, the present inventor has completed the method of the present invention as a result of earnest research, and the feature thereof is that the oil and SS are not removed from the wastewater or not so much. In addition, the waste water is introduced into the contact filter medium tank with the saponin-containing agent added, and the biofilm treatment is performed as it is.
[0008]
Here, the drainage refers to all treated water including domestic wastewater, industrial wastewater, and the like, but mainly drainage containing a large amount of oil. For example, wastewater from the restaurant industry, food processing factories, etc., and miscellaneous wastewater from homes also contains a lot of oil. The oil component means a normal hexane extract (normal hex component). Although the water quality standard for treated water of norhexi components is said to be several ppm, 600 to 700 ppm may be contained in wastewater from food processing plants and the food service industry. In addition, wastewater containing a relatively small amount of oil but containing a large amount of SS, such as a wastewater containing a large amount of starch such as a noodle factory, and a wastewater containing a large amount of both oil and SS are also suitable treatment targets of the present invention.
[0009]
Next, the contact aeration method is a process in which a contact filter medium such as mineral, plastic, wood or other plate, string or granular is placed in an aeration tank or floated and aerated from below or from the side. Say the way. As a floating thing, a plastic empty container, cork, foamed polystyrene, activated carbon, vermiculite, pulp waste, rice husk, sawdust, etc. are used. Since these are stirred by aeration, it is also called fluidized bed method. Moreover, it is a submerged filter bed method to spray waste water from the upper part to the tank filled with these. In addition, what does not aerate in the structure similar to a contact aeration method is called an anaerobic immersion filter bed method. The contact rotation aeration method is a method in which a disk-like plate or net, or a container containing an empty plastic container is rotated in a semi-immersed state in water to be treated, and is processed in both aerobic and anaerobic conditions. Say things. Any of these can be applied to the present invention. By these treatments, microbial colonies are gradually formed on the surface of the contact filter medium, and organic substances are efficiently treated.
[0010]
Here, saponin is a kind of glycoside contained in a plant body, and is a collective term for making a colloidal aqueous solution that is remarkably abundant like soap, and has been found in many plants. In the present invention, the type of saponin to be used is not limited. From the viewpoint of cost and stable supply, a saponin having a high content in the plant body and a large amount of the plant that can be stably obtained is preferable. From this point of view, saponins obtained from Kiraya saponin, yucca, nagi raft, soybean, sugar radish and the like are preferable. Of these, Quillaja saponin extracted from a soap tree (scientific name: Quilaia saponaria Mol. Rosaceae) that naturally grows in South America such as Chilly, Bolivia, and Peru is preferred. This is a triterpene-based glycoside having aglycone having the structure of Chemical Formula 1 as an aglycon (non-carbohydrate part of the glycoside), and is represented by Chemical Formula 2. This is due to the fact that an extract with a relatively high saponin concentration is obtained.
[Chemical 1]

[Chemical 2]

[0011]
As the saponin-containing agent, an extract (including a solvent) extracted from a plant body may be used as it is, or a purified product itself may be used. The extraction method may be a normal method, and can be extracted with a lower alcohol such as ethanol. Further, a refined product or an extract obtained by processing into a powder, granule, or tablet can also be used.
[0012]
By the way, the present inventor has found that saponin is effective in biological treatment processes of sewage, but this is a microorganism, because saponin is a glycoside and has a high oxygen content. It is speculated that the processing efficiency will improve as a result of helping breeding. Therefore, in the present invention, the present inventor also supplied a saponin-containing agent to the contact aeration tank and observed the situation for several months. As a result, a change was observed in the biological layer in the contact aeration tank, and an oil content of 500 ppm or more was observed. Has been fully processed. However, BOD and COD in the treated water saw some increase whether the oil decomposition substances remain. In the case of other treatment methods, good results were obtained as well.
[0013]
The amount of saponin-containing agent varies depending on the concentration of oil in the wastewater, but is usually 0.01 to 1.0 ppm, especially 0.12 to 0.4 ppm in terms of purified product (3% as a 4% solution). -10 ppm). In the case of a liquid saponin-containing agent, the addition may be carried out by a method such as constantly dropping with a metering pump. In the case of a solid preparation such as a tablet or granule, an appropriate amount may be added at an appropriate interval. Moreover, although the addition site | part of a saponin containing agent is initially injected | thrown-in directly to a contact filter medium tank, if it will be in a stable state (2 to 3 months), a better result will be obtained if it introduce | transduces into a adjustment tank.
[0014]
The present invention can be used for secondary treatment and tertiary treatment in the biological treatment process of waste water. In some cases, it can also be used for primary processing.
[0015]
【Example】
(Example 1)
Next, the present invention will be described in detail based on an embodiment shown in the drawings. FIG. 1 is a flowchart of a wastewater treatment facility of a certain food processing factory (adopting contact aeration method). The amount of discharged water was 250 tons / day, and the quality of treated water has been stable and has not been a problem. However, since there was a lot of oil (500 ppm), the oil was removed by pressurized flotation and the oil content in the wastewater sent to the aeration tank was adjusted to 10 ppm. However, in reality, it did not drop below 60 ppm, and the treatment capacity of the contact aeration tank decreased. Although the generated floating floss was dehydrated as surplus sludge, the amount of dehydrated cake generated was about 0.5 tons / day, and the disposal cost was high. Moreover, considering the cost of the flocculant for pressure floating and the flocculant for dehydration, the electricity cost required for pressure floating, etc., the running cost has become considerable.
[0016]
Therefore, 3 ppm (in the case of 4% saponin content liquid) of Kirayasaponin containing agent was added once a day with respect to the amount of treated water. This addition was performed in the aeration tank of FIG. During the period of 1 to 2 months from the introduction, the microorganisms initially increased, the biological layer of the aeration tank gradually changed, and the appearance of protozoa (which is often found in good treatment tanks) was observed. However, the cost required for the treatment was the same as before, but only the cost of the saponin-containing agent was added. From the third month onward, flocs formed in the aeration tank became larger, and many protozoa and microorganisms generated in good condition were observed. At the same time, since the concentration of oil in the wastewater to be added was increased (50 to 300 ppm), the chemicals required for pressurized levitation, the chemicals for dehydration, and the disposal costs for dehydrated cakes gradually declined. It has become cheaper than the beginning.
[0017]
After 3 months, the use of the pressure levitation device was stopped, and the waste water was directly fed from the adjustment tank to the aeration tank as shown in FIG. And in order to add uniformly, the saponin containing agent was thrown into this adjustment tank. As a result, the labor and cost required for oil recovery have been greatly reduced, and the working environment has been improved by reducing bad odors. In addition, the amount of the flocculant for dehydration was greatly reduced because there was no floating floss and the amount transported as surplus sludge decreased and it became easier to dehydrate. As a result, it was possible to reduce surplus sludge treatment costs and dehydration chemicals significantly. Of course, the quality of the treated water is also stable. Moreover, since microorganisms are active, originally DO (dissolved oxygen) should be deficient, but since the saponin-containing agent has an effect of increasing dissolved oxygen, the amount of air can be reduced. In that respect, the cost was reduced.
[0018]
Such a result occurred because the oil was emulsified by the saponin-containing agent and became easily degraded by bacteria, and the bacteria were activated and the emulsified oil and SS content (starch etc.) ) Is considered to be efficiently decomposed.
[0019]
However, since a large amount of oil was digested, BOD and COD as the residue increased somewhat as shown below. However, the amount is within the drainage standard.
Before input (average) mg / l
BOD COD SS Norhexa ingredients raw water 1,000 265 403 500ppm
After rising to pressure 724 230 360 60
Treatment water 3.75 12 9.3 10
After input (average) mg / l
BOD COD SS Norhexi component treatment water 4.7 5 14.1 6.8 2-3 ppm
[0020]
(Example 2)
In a certain service area, 70m ³ / day of kitchen wastewater was pressurized and floated and then treated in an anaerobic immersion filter bed tank. However, because the oil was not removed sufficiently, the contact filter medium was clogged with oil, and finally The filter medium was lifted up and did not form the body of the treatment tank at all. This kitchen wastewater had an average BOD of 550 ppm and an oil content of 100 to 150 ppm, and the treated water had a BOD of 100 and an oil content of about 50.
[0021]
In this state, the contact filter medium was replaced, the pressure flotation device was removed, and 3 to 5 ppm of the saponin-containing agent was continuously added. After about 2 months, the treated water had a BOD of 15 ppm and the oil content (non-normal hexane extract) However, it became possible to perform stable treatment at around 5ppm.
[0022]
【The invention's effect】
As described above, the present invention described in detail has the following great advantages.
1) The removal of oil and SS, which was a major bottleneck in wastewater treatment methods using contact filter media tanks such as contact aeration, is no longer necessary, reducing labor and costs spent on this, and wastewater treatment costs include saponin The amount was almost halved compared to before using the agent.
2) The absolute amount of activated sludge decreased (about 3/1), and the amount of flocculant used was also reduced to 1/3, reducing sludge treatment costs.
3) The working environment is greatly improved because it is no longer necessary to dispose of lump of oil that is exposed to bad odor and is difficult to handle.
[Brief description of the drawings]
FIG. 1 shows an example of a flowchart of wastewater treatment according to the present invention at the beginning of use of a saponin-containing agent based on a conventional contact aeration method.
FIG. 2 shows an example of a flowchart of waste water treatment by the contact aeration method of the present invention in a stable period .

Claims

Biofilm with increased microbial and protozoa adapted to decompose oil adhering to the filter medium by introducing the drainage together with the saponin-containing agent into the contact filter medium tank with little or no removal of oil and SS from the drainage A biofilm treatment method for wastewater, characterized by decomposing oil and SS in the wastewater by contacting the wastewater.

Using the beginning of the saponin-containing agent to remove oil and SS from waste water, gradually together lowering the degree of removal of oil and SS, saponin-containing agent is to add to the contact filter medium tank, according to claim 1, wherein Wastewater biofilm treatment method.

After the saponin-containing agent has been used for 2 to 3 months and the quality of the treated water has been stabilized, the oil and SS are removed from the wastewater without any or little removal and introduced into the contact filter medium tank. The biofilm treatment method for wastewater according to claim 1, wherein the containing agent is added to the contact filter medium tank or the upstream adjustment tank.

The wastewater biofilm treatment method according to claim 1, claim 2, or claim 3, wherein the wastewater having an oil (normal hexane extract) concentration of 700 ppm or less is treated.

The addition amount of the saponin-containing agent, depending on the oil content in the waste water, (as the content of 4% solution, 0. 25~25ppm) 0. 01~ 1. 0ppm purified solid basis with respect to drainage is, according The biofilm treatment method for waste water according to claim 1, claim 2, claim 3, or claim 4.

The amount of the saponin-containing agent added is 0.12 to 0.4 ppm (3 to 10 ppm as a 4% content liquid) in terms of purified product with respect to the wastewater, depending on the oil concentration in the wastewater. The biofilm treatment method for waste water according to claim 2, claim 3 or claim 4.

The contact filter medium tank is a contact aeration tank, a rotary contact aeration tank, an anaerobic submerged filter bed tank, or a submerged filter bed tank. Claim 1, Claim 2, Claim 3, Claim 4, Claim 5 or Claim The biofilm treatment method for waste water according to 6 .

The contact filter medium tank is used as a secondary treatment or a tertiary treatment of wastewater, wherein the wastewater according to claim 1, claim 2, claim 3, claim 4, claim 5, claim 6 or claim 7 is used. Biofilm treatment method.