JP2004105099A

JP2004105099A - Microorganism carrier

Info

Publication number: JP2004105099A
Application number: JP2002272632A
Authority: JP
Inventors: Kenji Wakikawa; 脇川　賢二
Original assignee: Inoue MTP KK; Inoac Corp
Current assignee: Inoac Corp
Priority date: 2002-09-19
Filing date: 2002-09-19
Publication date: 2004-04-08

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microorganism carrier having high immobilization efficiency of microorganisms, and suitably usable in a septic tank or the like. <P>SOLUTION: The microorganism carrier 10 is constituted by forming a cut product of an open cell foamed product formed by foaming a resin composition containing carbon fibers added thereto and regulated so that the surfaces are composed of the cut surfaces 11. The open cell foamed product is preferably the one of a crosslinked polyolefin-based resin. The polyolefin-based resin preferably contains ≥75 pts. wt. ethylene-vinyl acetate copolymer based on 100 pts. wt. resin. The carbon fiber added to the resin composition preferably has 0.1-5.0 mm fiber length and the content thereof is preferably 0.5-5 pts. wt. based on 100 pts. wt. resin. Preferably, the open cells are formed by breaking foams by compression. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
この発明は、浄化槽等に用いられる微生物担体に関する。
【０００２】
【従来の技術】
従来、浄化槽などにおける水処理には、好気性バクテリア等の微生物による働きで溶存有機物を酸化分解させる方法が利用されている。前記微生物による水処理において、多孔質体である連続気泡発泡体は、比表面積が大きく、微生物による生物膜を大量に作ることが可能なため、微生物担体として用いた場合に、水処理の効率が上がり、浄化槽の大きさを小さくできることが知られている（特許文献１、特許文献２、特許文献３参照。）。また、発泡体以外では炭素繊維が微生物の付着効率の高いことが知られており、炭素繊維編織物を水質浄化に用いることが検討されている（例えば、非特許文献１参照。）。
【０００３】
【特許文献１】
特開昭６３−２０９７８８号公報
【特許文献２】
特開平７−２５１１４７号公報
【特許文献３】
特開２００１−９６２８９号公報
【非特許文献１】
佐藤　誠、外５名、“炭素繊維編織品の形態が微生物固着に与える影響”、［ｏｎｌｉｎｅ］、［平成１４年９月４日検索］、インターネット＜ＵＲＬ：ｈｔｔｐ：／／ｗｗｗ．ｔｔｒｌ．ｐｒｅｆ．ｇｕｎｍａ．ｊｐ／ｙｏｕｓｈｉ／ｈ１１／０１ｔａｎｓｏ．ｈｔｍ＞
【０００４】
【発明が解決しようとする課題】
しかし、前記発泡体からなる微生物担体にあっては、微生物の付着性に対してさらなる向上が求められている。また、前記炭素繊維を浄化槽の微生物担体として用いようとすると、炭素繊維自体が細かい繊維であるため、炭素繊維がばっ気槽から次工程の沈殿槽に流出したり、処理水に混ざったりし易く、微生物担体としての用をなさなくなる。
【０００５】
この発明は前記の点に鑑みなされたものであり、微生物の付着効率が高く、浄化槽等での使用に好適な微生物担体の提供を目的とする。
【０００６】
【課題を解決するための手段】
この発明は、炭素繊維の添加された樹脂組成物から発泡形成された連続気泡発泡体の切り出し品からなって、表面が切断面で構成されていることを特徴とする微生物担体に係る。
【０００７】
前記樹脂組成物の樹脂はポリオレフィン系樹脂、また、前記連続気泡発泡体はポリオレフィン系樹脂架橋連続気泡発泡体が好ましい。さらに、前記ポリオレフィン系樹脂は、樹脂１００重量部中にエチレン酢酸ビニル共重合体を７５重量％以上含むものが好ましい。
【０００８】
また、前記樹脂組成物に添加された炭素繊維は、繊維長０．１〜５．０ｍｍのものが好ましく、さらには添加量が樹脂１００重量部に対して０．５〜５重量部であるのが好ましい。
【０００９】
また、前記連続気泡発泡体は、発泡倍率が１０〜４０倍であるのが好ましく、さらには、圧縮による破泡で連続気泡とされたものが好ましい。
【００１０】
【発明の実施の形態】
以下この発明を詳細に説明する。図１はこの発明の一実施例に係る微生物担体１０の斜視図である。
【００１１】
前記微生物担体１０は、浄化槽等における好気性バクテリア等による水処理に際し、好気性バクテリア等の微生物に対する付着用担体として使用されるものである。前記微生物担体１０は、炭素繊維の添加された樹脂組成物から発泡形成された連続気泡発泡体の切り出し品からなって、表面が切断面１１で構成されている。前記微生物担体１０の形状及びサイズは適宜とされるが、例として一辺が５〜５０ｍｍの立方体を挙げる。
【００１２】
樹脂組成物の樹脂としては、ポリウレタン、ゴム、ポリオレフィン系樹脂等を使用することができるが、それらの中でも、耐水性及び非汚染性の面からポリオレフィン系樹脂が好ましく、また、前記連続気泡発泡体はポリオレフィン系樹脂架橋連続気泡発泡体が好ましい。
【００１３】
前記ポリオレフィン系樹脂には、エチレン酢酸ビニル共重合体（ＥＶＡ）、低密度ポリエチレン（ＬＤＰＥ）、高密度ポリエチレン（ＨＤＰＥ）、エチレン−プロピレン共重合体、エチレン−ブテン共重合体、エチレンとメチル、エチル、プロピル若しくはブチルの各アクリル酸エステルとの共重合体、又はこれらの塩素化物、あるいはそれらの混合物、さらにはそれらとアイソタクチックポリプロピレン若しくはアタクチックポリプロピレンの混合物等を挙げることができる。
【００１４】
さらに前記ポリオレフィン系樹脂の中でも、エチレン酢酸ビニル共重合体をポリオレフィン系樹脂の全量１００重量部中７５重量部以上（最大１００重量部）含むものが好ましい。エチレン酢酸ビニル共重合体の発泡体は、低密度ポリエチレン（ＬＤＰＥ）等からなる発泡体と比べて反発弾性率（ＪＩＳ　Ｋ　６４００準拠）が高いため、前記微生物担体１０を流動礁で長期に使用した場合にも摩耗による寸法減少が少なく、微生物の担持表面積の減少を生じにくいので、長期に渡って微生物による処理を効率良く行わせることができる。また、前記エチレン酢酸ビニル共重合体の含量が７５重量部未満の場合、前記微生物担体１０の反発弾性率が低くなり、前記微生物担体１０を流動礁として長期使用した際、前記摩耗による担持表面積の減少が大きくなる。さらにまた、エチレン酢酸ビニル共重合体は、フィラーを充填して加工するときの加工性に優れ、多量に添加できる特色がある。
【００１５】
さらにまた、前記ポリオレフィン系樹脂は、ポリオレフィン系樹脂の全量１００重量％中、酢酸ビニル含量が１２〜３０重量％のものが好ましい。前記酢酸ビニル含量が１２重量％未満の場合、前記微生物担体１０は反発弾性率が低くなり、前記流動礁としての長期使用の際に摩耗程度が大きくなる。それに対し、３０重量％を超えると、ゴム成分たるビニル成分が多量に含まれることになって、所望の発泡倍率の発泡体が得られず、前記微生物担体１０のコストが増大する。
【００１６】
前記樹脂をポリオレフィン系樹脂とする場合、前記樹脂組成物には、前記ポリオレフィン系樹脂の他に、通常、ポリオレフィン系樹脂架橋発泡体の製造に使用される架橋剤、発泡剤、及び適宜の助剤が含まれる。
【００１７】
前記架橋剤としては、ジクミルパーオキサイド、２，５−ジメチル−２，５−ビス−ターシャリーブチルパーオキシヘキサン、１，３−ビス−ターシャリーパーオキシ−イソプロピルベンゼンなどの有機過酸化物等を挙げることができる。前記架橋剤の配合量は、通常、ポリオレフィン系樹脂１００重量部に対し０．５０〜１．３重量部である。
【００１８】
前記発泡剤としては、加熱により分解してガスを発生するものが用いられ、特に制限されるものではない。例えばアゾジカルボンアミド、２，２’−アゾビスイソブチロニトリル、ジアゾアミノベンゼン、ベンゼンスルホニルヒドラジド、ベンゼン−１，３−スルホニルヒドラジド、ジフェニルオキシド−４，４’−ジスルフォニルヒドラジド、４，４’−オキシビスベンゼンスルフォニルヒドラジド、パラトルエンスルフォニルヒドラジド、Ｎ，Ｎ’−ジニトロソペンタメチレンテトラミン、Ｎ，Ｎ’−ジニトロソ−Ｎ，Ｎ’−ジメチルフタルアミド、テレフタルアジド、ｐ−ｔ−ブチルベンズアジド、重炭酸ナトリウム、重炭酸アンモニウム等の一種又は二種以上が用いられる。特にアゾジカルボンアミド、４，４’−オキシビスベンゼンスルホニルヒドラジドが好適である。添加量としては、通常、ポリオレフィン系樹脂１００重量部に対して２〜３０重量部とされる。
【００１９】
また、適宜の助剤としては、発泡助剤、充填剤等がある。前記発泡助剤には、酸化亜鉛、酸化鉛等の金属酸化物、低級又は高級脂肪酸あるいはそれらの金属塩、尿素及びその誘導体等が挙げられる。
【００２０】
前記炭素繊維は、繊維長０．１〜５．０ｍｍのものが好ましい。０．１ｍｍよりも短いと、前記樹脂組成物の混合時に前記炭素繊維が飛散し易くなり、前記樹脂組成物内に充分混合分散し難くなる。それに対して５ｍｍよりも長いと、前記炭素繊維の嵩比重が非常に小さくなって、前記樹脂組成物の混合時に混合装置の槽から樹脂組成物が溢（あふ）れてしまい、良好な発泡体が得られなくなる。さらに、前記樹脂組成物の混合時における剪断力で前記炭素繊維が短く切断されてしまうため、前記炭素繊維の繊維長を５ｍｍより長くしても、意味が無くなってしまう。しかも、前記炭素繊維の短いものと長いものとを、前記炭素繊維の添加量を同一にして比べた場合、繊維長の短いものの方が、前記炭素繊維の数が多くなって前記微生物との接触点が多くなり、微生物の担持効果が高くなる。
【００２１】
また、前記炭素繊維の添加量は、前記樹脂組成物の樹脂１００重量部に対して０．５〜５重量部が好ましい。０．５重量部未満では、前記炭素繊維を添加した効果を得難くなる。それに対して、前記炭素繊維の添加量が５重量部を超えると、発泡体製造時に発泡体の膨張を前記炭素繊維が妨げ、発泡体に割れ等の不具合が発生し易くなる。前記炭素繊維のより好ましい添加量は１〜３重量部である。なお、前記炭素繊維には、通常の炭素繊維に処理を施して多孔質にした活性炭素繊維がある。この活性炭素繊維は、アンモニア等を吸着する機能があり、しかも多孔質であるため前記微生物の担持が良好となるので、この発明における炭素繊維として好ましいものである。
【００２２】
前記連続気泡発泡体の発泡倍率は、１０〜４０倍、より好ましくは１５〜３０倍である。発泡倍率が１０倍未満の場合、発泡体内部の空隙比率が小さくなるため、微生物との接触性が小さくなり、微生物担体として十分な機能を発揮できなくなる。それに対して発泡倍率が大になると、単位面積当たりの炭素繊維数が減少し、前記発泡倍率が４０倍を超えると、前記炭素繊維を添加した効果が充分に得られなくなる。
【００２３】
また、前記微生物担体１０は、前記炭素繊維の添加された樹脂組成物から発泡形成された連続気泡発泡体の切り出し品からなり、その表面が切断面１１で構成されているので、前記切断面１１で前記炭素繊維が露出し、微生物と効果的に接触することができる。さらに、前記連続気泡発泡体の連続気泡化は、発泡体を圧縮（クラッシングとも称される）して破泡させるものが好ましい。その圧縮によって、前記炭素繊維の一部が樹脂の骨格から露出し、前記微生物と炭素繊維との接触がより良好になる。勿論、前記連続気泡化は圧縮に限られるものではなく、公知の溶解処理によるものでもよい。
【００２４】
前記微生物担体１０の製造は、前記炭素繊維の添加された樹脂組成物を用い、公知の発泡方法にしたがい発泡させ、得られた発泡体を刃物等の切断具で所要寸法に切断して微生物担体１０を切り出すことにより行うことができる。その際、前記樹脂組成物の樹脂がポリオレフィン系樹脂の場合、ポリオレフィン系樹脂架橋発泡体に関する公知の二段発泡方法にしたがい発泡を行い、得られたポリオレフィン系樹脂架橋発泡体を圧縮又は溶解処理により、気泡を破泡させて連通化し、樹脂骨格に前記炭素繊維が結合したポリオレフィン系架橋連続気泡発泡体を得る。その後、前記ポリオレフィン系架橋連続気泡発泡体を、所要寸法に切り出して前記微生物担体１０を得る。
【００２５】
【実施例】
ポリオレフィン系樹脂としてエチレン酢酸ビニル共重合体（エバテートＨ２０２０、住友化学工業株式会社製）１００重量部（酢酸ビニル含量１５重量％）、発泡剤としてアゾジカルボンアミド１５重量部、架橋剤としてジクミルパーオキサイド０．６重量部、発泡助剤として尿素系助剤（セルペースト１０１、永和化成工業株式会社製）０．６重量部からなる樹脂組成物と、炭素繊維（径０．０１ｍｍ、コノコカーボンファイバース製）２重量部とからなる材料９００ｇを、１Ｌニーダーに入れ、混練り後１０インチロールで更に混練りし、発泡性コンパウンドを得た。この発泡性コンパウンドを、２０×２３０×２３０ｍｍの密閉金型に入れ、１３０℃で４０分間加熱し、脱型して、２２×２３５×２３５ｍｍの一次架橋体を得た。この一次架橋体を、１６０℃に温調された５０×５００×５００ｍｍの非密閉金型に入れ、１００分間加熱し、発泡倍率２０倍のポリオレフィン系樹脂架橋発泡体を得た。このようにして得られたポリオレフィン系樹脂架橋発泡体を、等速２本ロールで１／５の厚みに圧縮する作業を５往復行い、気泡を破泡させてポリオレフィン系樹脂架橋連続気泡発泡体を得た。その後、前記ポリオレフィン系樹脂架橋連続気泡発泡体から、一辺１０ｍｍの立方体形状をした微生物担体を切り出した。表１は、前記炭素繊維の繊維長を０．０５〜５．５ｍｍの間で変化させた場合における前記混練り作業時の状態を示す。
【００２６】
【表１】

【００２７】
この表１に示すように、炭素繊維の繊維長が０．０５ｍｍの比較例１の場合、前記混練り作業時に炭素繊維が飛散し、炭素繊維を樹脂組成物に充分かつ正確な量混合することができなかった。また、炭素繊維の繊維長が５．５ｍｍの比較例２の場合、混練り時に槽から発泡性コンパウンドが溢れてしまい、その後発泡体を製造することができなかった。それに対し、炭素繊維の繊維長が０．１〜５．０ｍｍの実施例１〜４においては、混練り作業時に不具合を生じず、発泡まで良好に行えた。
【００２８】
また、前記炭素繊維の繊維長を０．２５ｍｍにし、前記炭素繊維の添加量を０．５〜５．５重量部で変化させ、他は前記と同様にして実施例５〜８と比較例３の微生物担体を製造した。このようにして得られた微生物担体の表面をマイクロスコープ（キーエンス株式会社製、ＶＨ−７０００）で眺め、１ｍｍ^２中の炭素繊維数を数え、１００倍して１ｃｍ^２中の本数とした。表２にはこの場合の発泡状態と、炭素繊維数を示す。この表２に示すように、実施例５〜８における炭素繊維添加量０．５〜５．０重量部の範囲では良好に発泡できたのに対し、比較例３における炭素繊維添加量５．５重量部では発泡体に割れが発生した。
【００２９】
【表２】

【００３０】
さらに、前記炭素繊維を含まないことのみが前記各実施例と相違する比較例４の微生物担体を前記と同様にして製造し、この比較例４と前記実施例１〜８の微生物担体に対して、微生物の付着性を調べた。その方法は、前記比較例４と前記実施例１〜８の微生物担体を既存の浄化槽に投入し、２週間後に取り出してそれぞれ中央部で切断し、その切断面における活性汚泥の付着具合を目視で観察して行った。その結果、前記実施例１〜８の微生物担体については、中心部まで活性汚泥が付着していたのに対し、比較例４の微生物担体は表面から３ｍｍの範囲だけに活性汚泥が付着していた。前記活性汚泥は、細菌類や菌類を主な構成生物とするものであることが知られており、このことから、前記炭素繊維を含む実施例１〜８の微生物担体は、炭素繊維を含まない比較例４の微生物担体よりも微生物の付着性が向上しているのがわかる。
【００３１】
【発明の効果】
以上図示し説明したように、この発明の微生物担体は、炭素繊維の添加された樹脂組成物から発泡形成された連続気泡発泡体の切り出し品からなり、表面が切断面で構成されているため、炭素繊維がばっ気槽から次工程の沈殿槽に流出したり、処理水に混ざったりし難いのみならず、切断面における炭素繊維の露出によって微生物付着率の向上効果を充分に発揮することができる。
【図面の簡単な説明】
【図１】この発明の一実施例に係る微生物担体の斜視図である。
【符号の説明】
１０　微生物担体
１１　切断面[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a microorganism carrier used for a septic tank or the like.
[0002]
[Prior art]
BACKGROUND ART Conventionally, for water treatment in a septic tank or the like, a method of oxidatively decomposing dissolved organic substances by the action of microorganisms such as aerobic bacteria has been used. In the water treatment by the microorganism, the open-cell foam that is a porous body has a large specific surface area and can produce a large amount of a biofilm by the microorganism. It is known that the size of the septic tank can be reduced by going up (see Patent Literature 1, Patent Literature 2, and Patent Literature 3). In addition, it is known that carbon fibers other than foams have high adhesion efficiency of microorganisms, and the use of carbon fiber woven fabric for water purification has been studied (for example, see Non-Patent Document 1).
[0003]
[Patent Document 1]
JP-A-63-209788 [Patent Document 2]
JP-A-7-251147 [Patent Document 3]
JP 2001-96289 A [Non-Patent Document 1]
Makoto Sato, et al., "Influence of carbon fiber woven fabric form on microbial adhesion", [online], [Search on September 4, 2002], Internet <URL: http: // www. ttrl. pref. gunma. jp / youshi / h11 / 01tanso. htm>
[0004]
[Problems to be solved by the invention]
However, the microbial carrier comprising the foam is required to further improve the adhesion of the microorganism. Further, when trying to use the carbon fiber as a microbial carrier for a septic tank, the carbon fiber itself is a fine fiber, so that the carbon fiber easily flows out from the aeration tank to the sedimentation tank in the next step, or is easily mixed with the treated water. It is no longer useful as a microbial carrier.
[0005]
The present invention has been made in view of the above points, and an object of the present invention is to provide a microorganism carrier which has high adhesion efficiency of microorganisms and is suitable for use in a septic tank or the like.
[0006]
[Means for Solving the Problems]
The present invention relates to a microorganism carrier comprising a cut-out product of an open-cell foam formed by foaming from a resin composition to which carbon fibers have been added, wherein the surface is constituted by a cut surface.
[0007]
The resin of the resin composition is preferably a polyolefin resin, and the open cell foam is preferably a polyolefin resin crosslinked open cell foam. Further, the polyolefin-based resin preferably contains at least 75% by weight of an ethylene-vinyl acetate copolymer in 100 parts by weight of the resin.
[0008]
The carbon fiber added to the resin composition preferably has a fiber length of 0.1 to 5.0 mm, and more preferably 0.5 to 5 parts by weight based on 100 parts by weight of the resin. Is preferred.
[0009]
Further, the open-cell foam preferably has an expansion ratio of 10 to 40 times, and more preferably, is formed into open cells by foam breaking by compression.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail. FIG. 1 is a perspective view of a microorganism carrier 10 according to one embodiment of the present invention.
[0011]
The microorganism carrier 10 is used as a carrier for attachment to microorganisms such as aerobic bacteria in water treatment with aerobic bacteria or the like in a septic tank or the like. The microorganism carrier 10 is a cut product of an open-cell foam formed by foaming from a resin composition to which carbon fibers have been added, and has a cut surface 11 on the surface. The shape and size of the microorganism carrier 10 are appropriately determined, and an example is a cube having a side of 5 to 50 mm.
[0012]
As the resin of the resin composition, polyurethane, rubber, polyolefin-based resins and the like can be used. Among them, polyolefin-based resins are preferable from the viewpoint of water resistance and non-staining properties, and the open-cell foam is preferably used. Is preferably a polyolefin resin crosslinked open cell foam.
[0013]
The polyolefin-based resin includes ethylene vinyl acetate copolymer (EVA), low density polyethylene (LDPE), high density polyethylene (HDPE), ethylene-propylene copolymer, ethylene-butene copolymer, ethylene and methyl, ethyl And propyl or butyl acrylates, or chlorinated products thereof, or mixtures thereof, and furthermore, mixtures thereof with isotactic polypropylene or atactic polypropylene.
[0014]
Further, among the above-mentioned polyolefin resins, those containing 75 parts by weight or more (maximum 100 parts by weight) of the ethylene vinyl acetate copolymer in 100 parts by weight of the total amount of the polyolefin resin are preferable. Since the foam of the ethylene-vinyl acetate copolymer has a higher rebound resilience (based on JIS K 6400) than a foam made of low density polyethylene (LDPE) or the like, the microorganism carrier 10 was used for a long time in a fluid reef. Also in this case, the dimensional reduction due to abrasion is small, and the reduction of the surface area for carrying microorganisms is unlikely to occur, so that the treatment with microorganisms can be performed efficiently over a long period of time. Further, when the content of the ethylene-vinyl acetate copolymer is less than 75 parts by weight, the resilience of the microorganism carrier 10 becomes low, and when the microorganism carrier 10 is used as a fluid reef for a long time, the surface area supported by the abrasion is reduced. The decrease is greater. Furthermore, the ethylene-vinyl acetate copolymer is excellent in processability at the time of processing by filling a filler, and has a feature that it can be added in a large amount.
[0015]
Further, the polyolefin-based resin preferably has a vinyl acetate content of 12 to 30% by weight based on 100% by weight of the total amount of the polyolefin-based resin. When the vinyl acetate content is less than 12% by weight, the microbial carrier 10 has a low rebound resilience and a high degree of wear during long-term use as the fluid reef. On the other hand, if it exceeds 30% by weight, a large amount of a vinyl component as a rubber component is contained, so that a foam having a desired expansion ratio cannot be obtained, and the cost of the microorganism carrier 10 increases.
[0016]
When the resin is a polyolefin-based resin, in addition to the polyolefin-based resin, the resin composition generally includes a crosslinking agent, a foaming agent, and an appropriate auxiliary agent used for producing a polyolefin-based resin crosslinked foam. Is included.
[0017]
Examples of the crosslinking agent include organic peroxides such as dicumyl peroxide, 2,5-dimethyl-2,5-bis-tert-butylperoxyhexane, and 1,3-bis-tert-peroxy-isopropylbenzene. Can be mentioned. The compounding amount of the crosslinking agent is usually 0.50 to 1.3 parts by weight based on 100 parts by weight of the polyolefin resin.
[0018]
As the foaming agent, one that decomposes upon heating to generate gas is used, and is not particularly limited. For example, azodicarbonamide, 2,2′-azobisisobutyronitrile, diazoaminobenzene, benzenesulfonylhydrazide, benzene-1,3-sulfonylhydrazide, diphenyloxide-4,4′-disulfonylhydrazide, 4,4 ′ -Oxybisbenzenesulfonylhydrazide, paratoluenesulfonylhydrazide, N, N'-dinitrosopentamethylenetetramine, N, N'-dinitroso-N, N'-dimethylphthalamide, terephthalazide, pt-butylbenzazide, One or more of sodium bicarbonate and ammonium bicarbonate are used. Particularly, azodicarbonamide and 4,4′-oxybisbenzenesulfonyl hydrazide are preferred. The addition amount is usually 2 to 30 parts by weight based on 100 parts by weight of the polyolefin resin.
[0019]
In addition, examples of the appropriate auxiliary include a foaming auxiliary and a filler. Examples of the foaming aid include metal oxides such as zinc oxide and lead oxide, lower and higher fatty acids or metal salts thereof, urea and derivatives thereof.
[0020]
The carbon fiber preferably has a fiber length of 0.1 to 5.0 mm. When the length is shorter than 0.1 mm, the carbon fibers are liable to be scattered when the resin composition is mixed, and it is difficult to sufficiently mix and disperse the carbon fibers in the resin composition. On the other hand, if it is longer than 5 mm, the bulk specific gravity of the carbon fiber becomes very small, and the resin composition overflows from the tank of the mixing device when mixing the resin composition, and a good foam is obtained. Can not be obtained. Furthermore, since the carbon fiber is cut short by the shearing force at the time of mixing the resin composition, it becomes meaningless even if the fiber length of the carbon fiber is longer than 5 mm. Moreover, when comparing the carbon fiber having a short length with the carbon fiber having the same addition amount of the carbon fiber, the carbon fiber having a shorter fiber length has a larger number of the carbon fibers and is in contact with the microorganism. The number of points increases, and the effect of supporting microorganisms increases.
[0021]
Further, the addition amount of the carbon fiber is preferably 0.5 to 5 parts by weight based on 100 parts by weight of the resin of the resin composition. If it is less than 0.5 part by weight, it is difficult to obtain the effect of adding the carbon fiber. On the other hand, if the addition amount of the carbon fiber exceeds 5 parts by weight, the expansion of the foam is prevented by the carbon fiber at the time of producing the foam, and the foam tends to cause a problem such as cracking. A more preferable addition amount of the carbon fiber is 1 to 3 parts by weight. The carbon fibers include activated carbon fibers obtained by treating ordinary carbon fibers to make them porous. The activated carbon fiber has a function of adsorbing ammonia and the like, and is porous, so that the microorganism can be favorably carried. Therefore, the activated carbon fiber is preferable as the carbon fiber in the present invention.
[0022]
The expansion ratio of the open-cell foam is 10 to 40 times, and more preferably 15 to 30 times. When the expansion ratio is less than 10 times, the void ratio inside the foam becomes small, so that the contact property with the microorganisms becomes small and the sufficient function as a microorganism carrier cannot be exhibited. On the other hand, when the expansion ratio becomes large, the number of carbon fibers per unit area decreases, and when the expansion ratio exceeds 40 times, the effect of adding the carbon fibers cannot be sufficiently obtained.
[0023]
Further, the microbial carrier 10 is made of a cut product of an open-cell foam foamed and formed from the resin composition to which the carbon fiber is added, and the surface thereof is constituted by the cut surface 11. Thus, the carbon fibers are exposed and can be effectively contacted with microorganisms. Further, for the open-cell formation of the open-cell foam, it is preferable that the foam is compressed (also called crushing) to break the foam. Due to the compression, a part of the carbon fiber is exposed from the resin skeleton, and the contact between the microorganism and the carbon fiber becomes better. Needless to say, the open-cell formation is not limited to compression, but may be a known dissolution treatment.
[0024]
The microbial carrier 10 is manufactured by using the resin composition to which the carbon fiber is added, foaming the foamed material according to a known foaming method, and cutting the obtained foam into required dimensions with a cutting tool such as a blade. This can be done by cutting out 10. At this time, when the resin of the resin composition is a polyolefin resin, foaming is performed according to a known two-stage foaming method for a polyolefin resin crosslinked foam, and the obtained polyolefin resin crosslinked foam is compressed or dissolved. The polyolefin-based cross-linked open-cell foam in which the carbon fibers are bonded to the resin skeleton is obtained by breaking bubbles to make the cells open. Thereafter, the polyolefin-based crosslinked open-cell foam is cut into required dimensions to obtain the microorganism carrier 10.
[0025]
【Example】
100 parts by weight of ethylene vinyl acetate copolymer (Evatate H2020, manufactured by Sumitomo Chemical Co., Ltd.) (polyvinyl acetate content: 15% by weight) as a polyolefin resin, 15 parts by weight of azodicarbonamide as a foaming agent, and dicumyl peroxide as a crosslinking agent A resin composition comprising 0.6 parts by weight and 0.6 parts by weight of a urea-based auxiliary (Cell Paste 101, manufactured by Eiwa Chemical Industry Co., Ltd.) as a foaming auxiliary; (2 parts by weight) was placed in a 1 L kneader, kneaded, and further kneaded with a 10-inch roll to obtain a foamable compound. This foamable compound was placed in a closed mold of 20 × 230 × 230 mm, heated at 130 ° C. for 40 minutes, and demolded to obtain a primary crosslinked body of 22 × 235 × 235 mm. This primary crosslinked product was placed in a 50 × 500 × 500 mm unsealed mold controlled at 160 ° C., and heated for 100 minutes to obtain a polyolefin resin crosslinked foam having an expansion ratio of 20 times. The polyolefin resin crosslinked foam obtained in this manner is compressed to a thickness of 1/5 with two rolls at a constant speed of 5 reciprocations to break up bubbles to form a polyolefin resin crosslinked open cell foam. Obtained. Thereafter, a cubic microbial carrier having a side length of 10 mm was cut out from the polyolefin-based resin crosslinked open-cell foam. Table 1 shows the state at the time of the kneading operation when the fiber length of the carbon fiber was changed between 0.05 and 5.5 mm.
[0026]
[Table 1]

[0027]
As shown in Table 1, in the case of Comparative Example 1 in which the fiber length of the carbon fiber was 0.05 mm, the carbon fiber was scattered during the kneading operation, and the carbon fiber was sufficiently and accurately mixed with the resin composition. Could not. In the case of Comparative Example 2 in which the carbon fiber had a fiber length of 5.5 mm, the foaming compound overflowed from the tank during kneading, and a foam could not be manufactured thereafter. On the other hand, in Examples 1 to 4 in which the fiber length of the carbon fiber was 0.1 to 5.0 mm, no trouble occurred during the kneading operation, and the foaming was successfully performed.
[0028]
In addition, the fiber length of the carbon fiber was set to 0.25 mm, and the amount of the carbon fiber added was changed from 0.5 to 5.5 parts by weight. Was produced. The surface of the microbial carrier thus obtained was viewed with a microscope (VH-7000, manufactured by KEYENCE CORPORATION), and the number of carbon fibers in 1 mm ² was counted and multiplied by 100 to obtain the number in 1 cm ² . Table 2 shows the foamed state and the number of carbon fibers in this case. As shown in Table 2, while foaming was satisfactorily performed in the range of 0.5 to 5.0 parts by weight of carbon fiber added in Examples 5 to 8, the amount of carbon fiber added in Comparative Example 3 was 5.5. The cracks occurred in the foam at the weight part.
[0029]
[Table 2]

[0030]
Furthermore, a microbial carrier of Comparative Example 4 which is different from each of the Examples only in that it does not contain the carbon fiber was produced in the same manner as described above, and this Comparative Example 4 and the microbial carriers of Examples 1 to 8 were produced. The microbial adhesion was examined. In the method, the microorganism carriers of Comparative Example 4 and Examples 1 to 8 were put into an existing septic tank, taken out two weeks later, cut at the center, and the state of adhesion of activated sludge on the cut surface was visually observed. Observed. As a result, with respect to the microbial carriers of Examples 1 to 8, activated sludge adhered to the center, whereas the microbial carrier of Comparative Example 4 had activated sludge adhered only within a range of 3 mm from the surface. . The activated sludge is known to be mainly composed of bacteria and fungi, and from this, the microorganism carriers of Examples 1 to 8 including the carbon fiber do not include the carbon fiber. It can be seen that the adherence of microorganisms is higher than that of the microorganism carrier of Comparative Example 4.
[0031]
【The invention's effect】
As shown and described above, the microbial carrier of the present invention is a cut-out product of an open-cell foam formed by foaming from a resin composition to which carbon fibers are added, and the surface is constituted by a cut surface, Not only is it difficult for the carbon fiber to flow out of the aeration tank into the sedimentation tank of the next step, or mixed with the treated water, but also the effect of improving the microbial adhesion rate can be sufficiently exerted by exposing the carbon fiber on the cut surface. .
[Brief description of the drawings]
FIG. 1 is a perspective view of a microorganism carrier according to one embodiment of the present invention.
[Explanation of symbols]
10 Microbial carrier 11 Cut surface

Claims

A microbial carrier comprising a cut product of an open-cell foam formed by foaming from a resin composition to which carbon fibers have been added, wherein the surface is constituted by a cut surface.

The microorganism carrier according to claim 1, wherein the resin of the resin composition is a polyolefin-based resin, and the open-cell foam is a polyolefin-based resin cross-linked open-cell foam.

The microorganism carrier according to claim 2, wherein the polyolefin-based resin contains 75 parts by weight or more of an ethylene-vinyl acetate copolymer in 100 parts by weight of the resin.

The microorganism carrier according to any one of claims 1 to 3, wherein the carbon fiber added to the resin composition has a fiber length of 0.1 to 5.0 mm.

The microorganism carrier according to any one of claims 1 to 4, wherein the amount of the carbon fiber added is 0.5 to 5 parts by weight based on 100 parts by weight of the resin of the resin composition.

The microorganism carrier according to any one of claims 1 to 5, wherein the expansion ratio of the open-cell foam is 10 to 40 times.

The microorganism carrier according to any one of claims 1 to 6, wherein the open-cell foam is made into open cells by foam breakage by compression.