【０００１】
【発明の属する技術分野】
本発明は、生活系排水、工場系廃水、農業系排水、道路系排水などの各種の排水中に含まれる汚染物質を吸着およびろ過する浮揚性に優れた汚染物質除去材及びそれを用いた汚染物質除去方法に関する。
【０００２】
【従来の技術】
従来から、排水などの被処理水中の汚染物質を吸着してろ過するろ材として砂、活性炭、スポンジ、アンスラサイト（無煙炭）、発泡スチロール粒子などが知られており、イオンによる吸着・交換作用を利用するゼオライト（沸石）やイオン交換膜なども知られている。また最近では、汚染物質の生物膜による分解無機化を利用する微生物の支持体として、セラミック、発泡プラスチック、繊維集合体などの多孔体が使われるようになった。
【０００３】
発泡プラスチックからなるろ材としては、被処理水に対する浮揚性に優れた独立気泡性発泡体を用いたものと、被処理水中に対する浮揚性のあまり良くない連続気泡性発泡体を用いたものとが知られている。
【０００４】
独立気泡性発泡体からなるろ材として、原料樹脂材に発泡剤を添加して低圧で混練しつつ独立発泡させて内部に独立気泡を有する発泡体を形成する過程と、該過程で得られた発泡体を大きさ及び形状の不揃いな多数の粉砕粒子に粉砕する過程とを経て製作したものが提案されている（例えば、特許文献１参照。）。但し、この特許文献１には、界面活性剤による粉砕粒子表面への親水イオン基の導入については開示されていない。また、同様の技術として、原料樹脂材に炭酸カルシウムなどの親水性粉体と発泡剤とを加えて独立発泡させ、その発泡体を粉砕してなる粉砕粒子をろ材として用いることで、親水性化による早期からの処理能力の向上と、外面部の浸水による浮揚力の抑制により生ずる浮遊流動性を向上させた技術も提案されている（例えば、特許文献２参照。）。
【０００５】
一方、連続気泡性発泡体からなるろ材として、樹脂中に脂肪族グリセリンエステルなどの非イオン界面活性剤を、樹脂１００重量部につき１〜１５重量部混入させて親水性としたろ材が提案されている（例えば、特許文献３参照。）。この特許文献３には、ろ材の用途として、生物ろ過方式浄化槽に充填する微生物繁殖用担体としての用途が記載されており、担体の形状に関する記載はないが、おそらく細片に切断したものを水没させて使用するものと考えられる。同様の技術で、連続気泡性発泡体の樹脂中にアニオン系界面活性剤および非イオン界面活性剤を、樹脂１００重量部につき０．１〜５重量部塗布または含浸させた微生物繁殖用担持体を用いることで、微生物繁殖用担持体を早期に被処理水に水没させて微生物の処理能力の向上を図ることを目的とした技術（例えば、特許文献４参照）が提案されている。この特許文献４に記載の技術は、発泡体と界面活性剤とを用いる点で本願に類似するが、製造方法、形状、連泡率、浮揚性、使用目的において異なる。
【０００６】
従来からあるろ材の内、比重が水より重いろ材は抑止メッシュ上にろ材を配置させ水処理を下降水流で実施する場合が多く、懸濁態物質（ＳＳ成分）などが凝集沈殿する場合にはろ材の上に堆積して目詰まりする方向にある。これを上向水流で処理する場合には、ろ材が抑止メッシュ上を浮動しないようにするために、上向水流の速度が著しく低く制限される。このため被処理水中に上下間隔をあけて抑止メッシュを設け、両抑止メッシュ間にろ材を挿入する方法を用いることがあるが、ろ材の充填量やろ材の圧縮変形でろ材の充填密度が変化し、ろ過効果が変化する課題を抱える。この点、浮揚性のあるろ材は、ろ材の上側にのみ抑止メッシュを置いて、浮き上がろうとするろ材を抑止メッシュで受け止めるだけでも、抑止メッシュの下側において自身の浮力により適度に圧縮されたろ材の層を形成できる。従って、ろ材の浮力とろ材の層厚を決定することにより、早い上向水流であっても安定したろ過効果を生じさせることができる。また、懸濁態物質ＳＳなどの凝集沈殿物は下方に沈下し、ろ材の目詰まりの原因になりにくい。さらに、浮揚性のあるろ材は水処理が下降水流であっても浮力がこの流れに勝れば、ろ材が浮動せず吸着ろ過は安定して行われる。
【０００７】
浮揚性およびろ過性に優れるろ材は発泡プラスチックの細片や粒子が好適であるが、形状と共に発泡のセル構造も重要である。連続気泡性発泡体からなる細片や粒子は吸水すると沈降し易くなり浮揚力が落ち上向水流での水処理には向かない。また、発泡スチロールの発泡球状粒子は１００％に近い独立気泡を持つ粒子であるため浮力が大きすぎることと、充填粒子間の隙間が大きくろ過性能が劣る。
この点、独立気泡性発泡体を粉砕してなる粉砕粒子は、中心部の破壊されていない独立気泡と外面部の破壊された気泡とで構成され、適度な浮力を持つ一方で、水中の汚染物質との接触面積を広く持つことができる優れた吸着ろ材と言える。
【０００８】
【特許文献１】
特許第２７２６３７６号公報
【特許文献２】
特開平８−１４１５８８号公報
【特許文献３】
特開２００１−３４２２７７号公報
【特許文献４】
特開２００２−１９９８７９号公報
【０００９】
【発明が解決しようとする課題】
ところで、特許文献１、２に記載のような独立気泡性発泡体を粉砕してなる粉砕粒子を用いた場合でも、次のような課題がある。
即ち、一般にプラスチックは撥水性で水と馴染まない。発泡させてもその性質は変わらず、水中に没しても気泡を巻き込み水中の汚染物質の吸着やろ過の効率の低下を招く。これに鑑み、特許文献２は炭酸カルシウムなどの親水性粉体を発泡体の樹脂中に混練して親水性化して改良を加えている。しかし、無機充填材はそれ自身の比重が重く、多量に添加すると浮力を低減化させることと独立気泡の破壊が起こり、これも浮力低下の原因となる。
【００１０】
また、生活系排水、工場系廃水、農業系排水、道路系排水などの各種の排水中には様々な形態の汚染物質が含まれている。一般的には、ＢＯＤ、ＣＯＤで表される有機物質、有機態窒素や有機態リンなどの懸濁態物質や無機態窒素、無機態リンなどのイオン性低分子、フミン質などの水溶性難分解物質などが挙げられるが、食品工場、化学品製造業の排水であればその製品固有の汚染物質が含まれるであろうし、道路系排水であれば自動車からのガソリン、排ガス成分、タイヤ磨耗塵、アスファルト磨耗塵、大気中にあった塵芥の沈殿物などが含まれるであろう。このように排水中には多種多様の汚染物質が含まれることを前提として排水処理方法を検討しなければならない。しかし、特許文献１，２に記載の独立気泡性発泡体の粉砕粒子は、比較的高分子の懸濁態物質であれば吸着したりろ過するであろうし、凝集して沈殿させることも可能であるが、イオン性物質や水溶性高分子のフミン質は捕捉できない欠点がある。
【００１１】
本発明の目的は、浮揚性に優れる独立気泡性ポリオレフィン系発泡体の粉砕粒子であって、親水性かつ、排水中のイオン性物質を吸着する能力を持った汚染物質除去材を提供することである。
【００１２】
【課題を解決するための手段】
本発明者らは鋭意検討の結果、界面活性剤を樹脂中に練込んだ独立気泡性ポリオレフィン系発泡体の粉砕粒子が、上記課題を解決することを見出し本発明の完成に至った。
【００１３】
本発明に係る汚染物質除去材は、被処理水中に含まれる汚染物質を吸着およびろ過する汚染物質除去材であって、界面活性剤が独立気泡性ポリオレフィン系発泡体の樹脂中に練込まれており、該発泡体の粉砕粒子からなるものである。
【００１４】
ここで、前記界面活性剤としては、カチオン系界面活性剤、アニオン系界面活性剤、両性界面活性剤および非イオン界面活性剤の４種類の界面活性剤のいずれか１種または２種以上の界面活性剤を利用できる。界面活性剤の練込み重量部数の適性値は、独立気泡性ポリオレフィン系発泡体の発泡前の樹脂１００重量部に対して、０．０１〜１０重量部に設定することが好適である。また、独立気泡性ポリオレフィン系発泡体の独立気泡の直径も、汚染物質除去材の吸着およびろ過性能に密着に関与し、その値を１０〜５００μｍに制限することが好ましい。
【００１５】
前記独立気泡性ポリオレフィン系発泡体の粉砕粒子としては、ビーズ法型内発泡成形法の原料ビーズおよび発泡成形品のいずれか１種または２種の粉砕粒子を採用できる。粉砕粒子のサイズとしては、短径が１ｍｍ〜３０ｍｍになるように粉砕したものを好適に利用できる。
【００１６】
更に、排水中のイオン性物質の種類に応じて、吸着およびろ過の能力を幅広く調整できることから、前記粉砕粒子として、カチオン系界面活性剤、アニオン系界面活性剤、両性界面活性剤および非イオン界面活性剤の４種類の界面活性剤のうち異種の界面活性剤が樹脂中に練り込まれた複数種類の粉砕粒子を混合したものを好適に利用できる。
【００１７】
本発明に係る汚染物質除去方法は、被処理水の流通経路の途中部に、流通経路を横断するように請求項１〜７のいずれか１項記載の汚染物質除去材を一定厚さの層状に配置し、汚染物質除去材層を通過するように被処理水を供給することで、被処理水中に含まれる汚染物質を吸着およびろ過するものである。
【００１８】
ここで、排水中のイオン性物質の種類に応じて、吸着およびろ過の能力を幅広く調整できるメリットがあることから、前記汚染物質除去材層を流通経路の途中部に複数配置し、汚染物質除去材層毎にそれを構成する粉砕粒子として、カチオン系界面活性剤、アニオン系界面活性剤、両性界面活性剤および非イオン界面活性剤の４種類の界面活性剤のうち異種の界面活性剤が樹脂中に練込まれた粉砕粒子を用い、被処理水中に含まれる汚染物質を段階的に吸着およびろ過することが好ましい。
【００１９】
【発明の実施の形態】
本発明の汚染物質除去材は、界面活性剤が樹脂中に練込まれた独立気泡性ポリオレフィン系発泡体の粉砕粒子からなる。
本発明の独立気泡性ポリオレフィン系発泡体に使用されるポリオレフィン系樹脂は、オレフィン単量体単位を５０％以上、さらには７０％以上で１００％以下含有し、オレフィン単量体と共重合可能な単量体単位を５０％以下、さらには３０％以下で０％以上含有する樹脂である。オレフィン単量体の具体例としては、エチレン、プロピレン、ブテン、ペンテン、ヘキセン、へプテン、オクテンなどの炭素数２〜８のαオレフィン単量体やノルボルネン系モノマーなどの環状オレフィンなどがあげられる。これらは単独で用いてもよく、２種以上を併用してもよい。また、オレフィン単量体と共重合可能な単量体の具体例としては、酢酸ビニルなどのビニルアルコール、メチルメタクリレート、エチルアクリレート、ヘキシルアクリレートなどのアルキル基の炭素数が１〜６の（メタ）アクリル酸アルキルエステル、ビニルアルコール、メタクリル酸、塩化ビニルなどがあげられる。これらは単独で用いてもよく、２種以上を併用してもよい。
【００２０】
さらに前記ポリオレフィン系樹脂の具体例として、例えばエチレン−プロピレンランダム共重合体、エチレン−プロピレン−ブテンランダム３元共重合体、ポリエチレン−ポリプロピレンブロック共重合体、ホモポリプロピレンなどのポリプロピレン系樹脂；低密度ポリエチレン、中密度ポリエチレン、高密度ポリエチレン、直鎖低密度ポリエチレン、エチレン−酢酸ビニル共重合体、エチレン−メチルメタクリレート共重合体などのポレエチレン樹脂；ポリブテン、ポリペンテンなどがあげられる。これらのポリマーは単独で用いてもよく、２種以上を併用してもよい。また、該ポリオレフィン系樹脂は、無架橋で用いてもよいが、パーオキサイドや放射線などにより架橋させて用いてもよい。
【００２１】
また本発明に用いる界面活性剤は、特に限定はないが、好ましくはカチオン系界面活性剤、アニオン系界面活性剤、両性界面活性剤、非イオン界面活性剤が挙げられ、これらの１種以上を用いることが出来る。上記界面活性剤はいずれも親水基を有するため、浸水時の気泡の巻き込みが少なく、排水処理の効率が向上する。また、カチオン系界面活性剤、アニオン系界面活性剤、両性界面活性剤などのイオン系界面活性剤は、排水中の汚染物質のイオン性物質を吸着ろ過する性能が備わるため優れた汚染物質除去材となる。１種および２種以上の界面活性剤が樹脂中に練込まれた独立気泡性ポリオレフィン系発泡体の粉砕粒子からなる汚染物質除去材は被処理水としての排水中のイオン物質などの汚染物質の中身にあわせて、その種類を使い分けることでその吸着ろ過効果を高めることが可能となる。
【００２２】
本発明に供せられる代表的な界面活性剤について説明すると、カチオン系界面活性剤としては、アルキルスルホン酸塩、アルキルベンゼンスルホン酸塩、アルキル硫酸エステル塩、アルキルエトキシ硫酸エステル塩、アルキルリン酸エステル塩などを例示でき、アニオン系界面活性剤としては、アルキルトリメチルアンモニウム塩、アシロイルアミドプロピルトリメチルアンモニウムメトサルフェート、アルキルベンジルジメチルアンモニウム塩、アシル塩化コリンなどを例示でき、両性界面活性剤としては、アルキルベタイン型、イミダゾリン型、アラニン型などを例示でき、非イオン界面活性剤としては、脂肪酸アルキロールアミド、ジ−（２−ヒドロキシエチル）アルキルアミン、ポリオキシエチレンアルキルアミン、脂肪酸グリセリンエステル、ポリオキシエチレングリコール脂肪酸エステル、ソルビタン脂肪酸エステル、ポリオキシソルビタン脂肪酸エステル、ポリオキシエチレンアルキルフェニルエーテル、ポリオキシエチレンアルキルエーテルなどを例示できる。
【００２３】
さらに本発明は、カチオン系界面活性剤、アニオン系界面活性剤、両性界面活性剤および非イオン界面活性剤の４種類の界面活性剤のうち異種の界面活性剤が練込まれた複数種類の粉砕粒子を混合して使用することを提案し、被処理水としての排水中のイオン物質などの汚染物質の物性に合わせて、その界面活性剤のイオンの種類を選定し、組み合わせや配合割合を事前に決めて使用することにより吸着ろ過効果を高めることが可能となる。
【００２４】
界面活性剤の練込み重量部数は、独立気泡性ポリオレフィン系発泡体発泡前の樹脂１００重量部に対して、０．０１〜１０重量部であることが好ましい。さらに好ましくは、０．０５〜５重量部である。少ない場合にはイオン性物質の吸着ろ過効果および持続性が劣る場合があり、多過ぎると粉砕粒子の近傍で必要以上の泡立ちが生じる恐れがある。
【００２５】
また、本発明においては、独立気泡性ポリオレフィン系発泡体を粉砕した粉砕粒子を使用するが、これは、適度な浮揚性を持たせるためである。つまり、独立気泡性ポリオレフィン系発泡体を粉砕すると、粉砕した小片の中心部は独立気泡を維持した状態となるが、外面部においては気泡が破壊（開口）した状態となり、外面部の気泡に被被処理水が浸入して、被処理水との接触面積を増大できるとともに、浮揚力を調整できることになる。粉砕粒子としては、例えば板状の発泡体を粉砕機や破砕機で粉砕してなる、不揃いな小片状のものを好適に採用できるが、中心部に独立気泡が残存し、外面部の独立気泡が破壊されていれば、一定サイズの小片にカットしたものを採用することも可能である。
【００２６】
ポリオレフィン樹脂が耐久性のある樹脂である以外に、好ましい理由として、ポリオレフィン樹脂は結晶性ポリマーであってガラス転移温度が低く室温でもそのセグメント内でミクロブラウン運動が行われ、界面活性剤の表面移行が起こり、仮に表面に付いた界面活性剤が洗い落とされても内部から補給されるため吸着ろ過効果が長く持続するからで、この点ポリスチレンなどの非結晶性ポリマーはガラス転移温度が室温より高いものが多くこの性質がないからである。
【００２７】
本発明の中心部に独立気泡を有し、外面部に破壊された気泡を有する界面活性剤入りの粉砕粒子からなる汚染物質除去材は、押出機にポリオレフィン系樹脂および界面活性剤を投入して、これを分解型発泡剤または揮発性発泡剤で押出発泡させる方法やポリオレフィン系樹脂および界面活性剤に熱分解型発泡剤の他、必要に応じて架橋剤、発泡助剤などを添加し、熱分解型発泡剤が熱分解しない温度でロールやミキサーなどで溶融混練し、金型中で所定形状に成形後、熱分解型発泡剤が発泡可能な温度で発泡させるバッチタイプの発泡方法で製造される発泡体の粉砕によっても製造可能となるが、ポリオレフィン系樹脂の発泡体の独立気泡率が１００％に近く、かつ球状の気泡が得られることにおいては、ビーズ法型内発泡成形法の原料ビーズまたは発泡成形品からの粉砕粒子であることが好ましい。
【００２８】
前記ポリオレフィン系発泡体の原料ビーズとは、例えば、界面活性剤とオレフィン系樹脂とを押出機のスクリュウで加熱混練しながら糸状に押出し、これをカットしてペレットを得、次に、このペレットを密閉耐圧容器内で水系媒体に分散剤により分散させ、揮発性発泡剤を加え、ペレットの軟化温度以上の発泡温度にまで加熱し、前記密閉耐圧容器の内圧よりも低圧の雰囲気下に放出して得られる予備発泡粒子のことである。この予備発泡粒子を粉砕機や破砕機で粉砕しても良いが、ビーズ法型内発泡成形した成形品を粉砕機や破砕機で粉砕することにより、本発明の汚染物質除去材を得ることができる。
【００２９】
前記ビーズ法型内発泡成形法とは、代表されるのはビーズ法発泡ポリスチレンにおける発泡成形方法である。この方法は、揮発性発泡材を溶存する球形の微小ポリスチレンビーズを予備発泡機で蒸気過熱し所望の発泡倍率（密度）の予備発泡粒子を得る。次に、発泡成形機に設置された開閉可能な金型を閉じ、該金型の空間部に該予備発泡粒子を充填し、金型周囲に設置された蒸気室から金型表面に無数に配置された小孔から蒸気を金型内に投入し、発泡させて充填粒子間の空隙部を埋め粒子どうしを溶融固着させ、冷却後金型を開として、所望の形状の発泡成形体を得る方法である。ビーズ法発泡ポリオレフィン系樹脂においても基本的には全く同様な方法で製造されるが、異なる点はポリオレフィン系樹脂には溶剤型発泡剤を溶存する力が無く、発泡後の予備発泡粒子の２次発泡余力が弱いので、金型に充填する前の予備発泡粒子に無機ガスを加圧封入したり、予備発泡粒子を加圧収縮させて金型に充填するなどの工程を必要とする。
【００３０】
独立気泡性ポリオレフィン系発泡体の独立気泡の直径は１０〜５００μｍであることが好ましい。独立気泡の直径が小さくなればなるほど粉砕粒子の周囲の破壊された気泡の比表面積が向上して処理する水中の汚染物質との接触の機会が増えるが、小さ過ぎるとＳＳ分を捕捉できなくなる場合がある。独立気泡の直径が大きくなると比表面積が減少して処理する水中の汚染物質との接触の機会が減る場合がある。
【００３１】
独立気泡の直径の測定方法は、発泡体をカッターナイフで約３×３ｃｍ２以上のカット面となるようカットし、カット面の無数の独立気泡をインクやマジックインクで着色し、スケールの付いたルーペ（拡大倍率４０または８０）でのぞき、そのスケール（例えば２０ｍｍ）に対する直線上の独立気泡の数を数えて、独立気泡１ケ当たりの平均気泡径を求める方法で行った。
【００３２】
独立気泡性ポリオレフィン系発泡体の粉砕粒子の大きさは、短径で１ｍｍ〜３０ｍｍが好ましく、より好ましくは２〜５ｍｍである。小さ過ぎると中心部の独立気泡まで破壊されて浮揚性が低下する場合あり、逆に大き過ぎると浮力が大き過ぎることと比表面積が減って処理する水中の汚染物質との接触の機会を減ずる場合がある。このようなサイズの粉砕粒子は、網目サイズの異なる２種類の篩を用いて選別することができ、網目３０ｍｍ〜５ｍｍの篩を通過し、網目１ｍｍ〜２ｍｍの篩を通過しない粉砕粒子を要求サイズの粉砕粒子として用いることになる。
【００３３】
次に、汚染物質除去材を用いた排水処理設備の一例について簡単に説明する。
図１に示すように、被処理水１としての排水が流通する処理槽１０が設けられ、処理槽１０の下部には被処理水１の入口管１１が接続され、処理槽１０の上部には汚染物質を除去した処理水２の出口管１２が接続されている。処理水２の液面３よりも下側において処理槽１０の上部内には処理槽１０内における被処理水１の流通経路を横断するように抑止メッシュ１３が設けられ、汚染物質除去材１４はその浮力により抑止メッシュ１３の下側に層状に浮かんで配置されている。尚、符号１５は、処理槽１０の下部内に沈殿した汚染物質４を処理槽１０の下端から排出するたの排出管であり、符号１６は、排出管１５を開閉するためのバルブである。
【００３４】
そして、被処理水１中の汚染物質を除去する際には、入口管１１から処理槽１０の下部内へ被処理水１を供給することで、被処理水１が汚染物質除去材１４を通って上側へ移動し、汚染物質除去材１４を通過する過程で被処理水１中に含まれる汚染物質が除去され、処理水２として出口管１２から排出されることになる。
【００３５】
また、処理対象の異なる複数種類の汚染物質除去材を用いる場合には、例えば、図２に示すように、処理槽１０内に被処理水１の流通経路を横断する上下１対の抑止メッシュ１３Ａ，１３Ｂを間隔をあけて配置し、それぞれの抑止メッシュ１３Ａ，１３Ｂの下側に種類の異なる汚染物質除去材１４Ａ，１４Ｂを層状に配置するこも可能である。具体的には、汚染物質除去材層毎にそれを構成する粉砕粒子として、カチオン系界面活性剤、アニオン系界面活性剤、両性界面活性剤および非イオン界面活性剤の４種類の界面活性剤のうち異種の界面活性剤が樹脂中に練込まれた粉砕粒子を用い、被処理水１中に含まれる汚染物質を段階的に吸着およびろ過することになる。このように構成すると、被処理水１中のイオン物質などの汚染物質の物性に適合するように、その界面活性剤のイオンの種類を選定し、汚染物質除去層の組み合わせや厚みを事前に設定して使用することにより吸着ろ過効果を高めることが可能となる。また、また、汚染物質の物性により適合するように、種類の異なる汚染物質除去材層を３層以上設けることも可能である。
【００３６】
【実施例】
以下に、本発明による汚染物質除去材の製造および排水処理の実施態様について実施例にて詳しく説明するが、本発明はこれら実施例のみに限定されるものではない。
（実施例１）エチレン含有量が３％のエチレン−プロピレンランダムコポリマーのラージペレット１００重量部にカチオン系界面活性剤のアシロイルアミドプロピルトリメチルアンモニュームサルフェート１．０重量部および発泡造核剤などの添加剤とをマスターバッチし、押出機内で溶融混練させ糸状に押し出し、ペレタライザーにて直径約０．７ｍｍで長さ約１０ｍｍのスモールペレットを作製した。該スモールペレットを耐圧容器中に水、分散剤と共に仕込み撹拌ペラで撹拌し、耐圧容器のジャケットに蒸気を投入して昇温した。昇温途中で揮発性発泡剤のブタンを投入し、耐圧容器内の温度が１５０℃、圧力が１．６６７ＭＰａ（１７ｋｇ／ｃｍ２）で安定するまでブタンを追加した。次ぎに、耐圧容器に連結する配管の仕切り板にある口径６ｍｍの円孔を開放して大気中に放出して発泡させた。この間耐圧容器内の圧力が一定となるようブタンを追加し続けた。得られた予備発泡粒子は直径約３ｍｍのほぼ球体であり、発泡倍率５倍（密度＝０．１８ｇ／ｃｍ３）で約９８％の独立気泡率を有していた。該予備発泡粒子を加圧タンク内に仕込み、空気加圧して発泡粒子ないの無数独立気泡内に加圧空気を含浸させた。独立気泡内の空気圧は１５２０ｈＰａ（１．５ａｔｍ）であった。次ぎに、加圧空気が含浸された予備発泡粒子を発泡成形機に搭載された開閉可能な金型を閉じた状態として、該金型内に充填器により充填し、金型に附帯する蒸気チャンバー室から金型面にある無数の細孔を通して蒸気を投入し約１４０℃で加熱発泡させ、冷却後金型から取り出して、板状体の発泡成形品を得た。その平均気泡径は測定の結果約１８０μｍであった。次ぎに、複数の刃物をセットした破砕ローターと被破砕物を破砕ローターに押しつける供給プレスシャーを持つ破砕機に該板状体の発泡成形品を投入して粉砕し、網目５ｍｍのスクリーンを通過させ、さらに網目２ｍｍのスクリーンで篩い、短径２〜５ｍｍ、平均約３ｍｍの本発明の１例となる、樹脂中にカチオン系界面活性剤が練り込まれた、中心部に独立気泡を有し、外周部に破壊された気泡を有する、浮揚性に優れる独立気泡性ポリオレフィン系発泡体の粉砕粒子である汚染物質除去材を得た。
【００３７】
（実施例２）実施例１と同一の方法で、エチレン分３％のポリプロピレンランダムコポリマー１００重量部に対して、アニオン系界面活性剤のアルキルリン酸エステル塩１．０重量部を練り込んだ、独立気泡性ポリオレフィン系発泡体の粉砕粒子である汚染物質除去材を得た。
【００３８】
（実施例３）実施例１と同一の方法で、エチレン分３％のポリプロピレンランダムコポリマー１００重量部に対して、非イオン界面活性剤のジ−（２−ヒドロキシエチル）アルキルアミン１．０重量部を練り込んだ、独立気泡性ポリオレフィン系発泡体の粉砕粒子である汚染物質除去材を得た。
【００３９】
（実施例４）実施例１と同一の方法で、エチレン分３％のポリプロピレンランダムコポリマー１００重量部に対して、カチオン系界面活性剤のアシロイルアミドプロピルトリメチルアンモニュームサルフェート０．５重量部およびアニオン系界面活性剤のアルキルリン酸エステル塩０．５重量部を練り込んだ、独立気泡性ポリオレフィン系発泡体の粉砕粒子である汚染物質除去材を得た。
【００４０】
（実施例５）実施例１で得たカチオン系界面活性剤が練り込まれた粉砕粒子５０％と実施例２のアニオン系界面活性剤の入った粉砕粒子５０％とを混合した汚染物質除去材を得た。
【００４１】
（実施例６）実施例１で得たカチオン系界面活性剤が練り込まれた粉砕粒子からなる汚染物質除去材と、実施例２のアニオン系界面活性剤の入った粉砕粒子からなる汚染物質除去材を用いた。
【００４２】
（実施例７）また、基本的には実施例１と同一の方法であるが、予備発泡条件の温度・圧力や発泡成形の温度など樹脂の耐熱性に合わせて低めに設定し、空気含浸を省略して、直鎖低密度ポリエチレン１００重量部に対して、アニオン系界面活性剤のアルキルリン酸エステル塩０．５重量部を練り込んだ、発泡倍率１０倍で気泡径２５０μｍの独立気泡性ポリオレフィン系発泡体の粉砕粒子である汚染物質除去材を得た。
【００４３】
（実施例８）同じく、直鎖低密度ポリエチレン１００重量部に対して、非イオン界面活性剤のジ−（２−ヒドロキシエチル）アルキルアミン０．５重量部を練り込んだ、独立気泡性ポリオレフィン系発泡体の粉砕粒子である汚染物質除去材を得た。
【００４４】
（比較例１）実施例１と同一の方法で、エチレン分３％のポリプロピレンランダムコポリマーに界面活性剤を加えず、独立気泡性ポリオレフィン系発泡体の粉砕粒子である汚染物質除去材を得た。
【００４５】
（評価試験）
実施例１〜５、７、８、比較例１に関しては、図１に示す排水処理設備を用い、抑止メッシュ１３の下側に汚染物質除去材を厚さが３０ｃｍになるように層状に形成して、汚染物質除去材による汚染物質の吸着およびろ過性能試験を行った。また、実施例６に関しては、図２に示す排水処理設備を用い、下側の抑止メッシュ１３Ｂの下側にカチオン系界面活性剤が練り込まれた粉砕粒子からなる汚染物質除去材を厚さが１５ｃｍとなるように層状に形成し、上側の抑止メッシュ１３Ａの下側にアニオン系界面活性剤が練り込まれた粉砕粒子からなる汚染物質除去材を厚さが１５ｃｍとなるように層状に形成して、両汚染物質除去材による汚染物質の吸着およびろ過性能試験を行った。
【００４６】
その結果、実施例１〜８の何れにおいても、比較例１と比べ、ＢＯＤ、ＣＯＤで表される有機物質、有機態窒素や有機態リンなどの懸濁態物質や無機態窒素、無機態リンなどのイオン性低分子、フミン質などの水溶性難分解物質などが効率良く除去されることが確認された。また、道路系排水である自動車からのガソリン、排ガス成分、タイヤ磨耗塵、アスファルト磨耗塵、大気中にあった塵芥の沈殿物なども効果的に除去されることが判明した。
【００４７】
【発明の効果】
本発明に係る汚染物質除去材は、次のような効果を奏する。
独立気泡性ポリオレフィン系発泡体の粉砕粒子を用い、粉砕粒子の中心部は独立気泡が残存しした状態となるが、外面部は気泡が破壊（開口）した状態となって、水が浸入し得る構造となっているので、サイズの調整により粉砕粒子の浮力を容易に調整できること、粉砕粒子に適度な浮力を持たせることで、早い上向水流であっても安定したろ過効果を得ることができること、水と粉砕粒子との接触面積を大きく設定して汚染物質除去性能を向上できること、などの効果が得られる。
【００４８】
また、粉砕粒子を構成する樹脂中に界面活性剤が練り込まれているので、界面活性剤の選択如何により、粉砕粒子の表面に存在する各種イオンを正イオンから負イオンまで調整できる。このため、被処理水としての排水中のイオン性物質を吸着およびろ過する能力を幅広く調整することができ、しかも樹脂内部に存在する界面活性剤が時間を掛けて表面に移行するため効果が持続し、浮揚性のろ材の特長を生かした新たな汚染物質除去材を提供できる。
【００４９】
ここで、前記界面活性剤として、カチオン系界面活性剤、アニオン系界面活性剤、両性界面活性剤および非イオン界面活性剤の４種類の界面活性剤のいずれか１種または２種以上の界面活性剤を用いると、被処理水としての排水中のイオン物質などの汚染物質の物性に合わせて、その界面活性剤のイオンの種類を選定し、界面活性剤の組み合わせや配合割合を事前に決めて使用することにより吸着ろ過効果を高めることが可能となる。
【００５０】
界面活性剤の練込み重量部数を独立気泡性ポリオレフィン系発泡体の発泡前の樹脂１００重量部に対して、０．０１〜１０重量部に設定すると、イオン性物質の吸着ろ過効果および持続性を十分に確保でき、しかも粉砕粒子の近傍で必要以上の泡立ちが生じることを防止できる。
【００５１】
独立気泡性ポリオレフィン系発泡体の独立気泡の直径を１０〜５００μｍに設定すると、被処理水と粉砕粒子との接触面積を増大しつつ、ＳＳ分の捕捉性能を十分に確保することが可能となる。
【００５２】
粉砕粒子の短径を１ｍｍ〜３０ｍｍに設定すると、粉砕粒子の浮力を適度に設定でき、しかも被処理水と粉砕粒子との接触面積を十分に確保できる。
【００５３】
粉砕粒子として、カチオン系界面活性剤、アニオン系界面活性剤、両性界面活性剤および非イオン界面活性剤の４種類の界面活性剤のうち異種の界面活性剤が樹脂中に練り込まれた複数種類の粉砕粒子を混合したものを用いると、排水中のイオン性物質の種類に応じて、吸着およびろ過の能力を幅広く調整できる。
【００５４】
本発明に係る汚染物質除去方法によれば、請求項１〜７のいずれか１項記載の汚染物質除去材を用いているので、請求項１〜７のいずれか１項と同様の効果が得られる。
【００５５】
ここで、前記汚染物質除去材層を流通経路の途中部に複数配置し、汚染物質除去材層毎にそれを構成する粉砕粒子として、カチオン系界面活性剤、アニオン系界面活性剤、両性界面活性剤および非イオン界面活性剤の４種類の界面活性剤のうち異種の界面活性剤が樹脂中に練込まれた粉砕粒子を用い、被処理水中に含まれる汚染物質を段階的に吸着およびろ過すると、排水中のイオン性物質の種類に応じて汚染物質除去材を選定して、汚染物質の吸着およびろ過の能力を幅広く調整できる。
【図面の簡単な説明】
【図１】排水処理設備の説明図
【図２】他の構成の排水処理設備の説明図
【符号の説明】
１ 被処理水 ２ 処理水
３ 液面
１０ 処理槽 １１ 入口管
１２ 出口管 １３ 抑止メッシュ
１４ 汚染物質除去材 １５ 排出管
１６ バルブ
１３Ａ 抑止メッシュ １３Ｂ 抑止メッシュ
１４Ａ 汚染物質除去材 １４Ｂ 汚染物質除去材[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pollutant-removing material having excellent buoyancy for adsorbing and filtering pollutants contained in various wastewaters such as domestic wastewater, factory wastewater, agricultural wastewater, and road wastewater, and pollution using the same. It relates to a material removal method.
[0002]
[Prior art]
Conventionally, sand, activated carbon, sponge, anthracite (anthracite), polystyrene foam particles, etc. are known as filter media for adsorbing and filtering pollutants in treated water such as wastewater, and use the adsorption / exchange action by ions. Zeolite (zeolite) and ion exchange membranes are also known. Recently, porous materials such as ceramics, foamed plastics, and fiber aggregates have come to be used as a support for microorganisms that take advantage of biodegradation of contaminants.
[0003]
Filter media made of foamed plastic are known to use closed-cell foams with excellent buoyancy in the water to be treated and those using open-cell foams with poor buoyancy in the water to be treated. It has been.
[0004]
The process of forming a foam having closed cells inside by adding a foaming agent to the raw resin material and kneading at low pressure to form a foam having closed cells inside as a filter medium comprising a closed cell foam, and the foam obtained in the process A product manufactured through a process of pulverizing a body into a large number of pulverized particles having irregular sizes and shapes has been proposed (for example, see Patent Document 1). However, this Patent Document 1 does not disclose the introduction of hydrophilic ion groups onto the pulverized particle surface by a surfactant. In addition, as a similar technology, hydrophilic materials are made hydrophilic by adding a hydrophilic powder such as calcium carbonate and a foaming agent to the raw material resin material and independently foaming, and using the pulverized particles obtained by pulverizing the foam as a filter medium. There has also been proposed a technique for improving the floating fluidity caused by the improvement of the processing capability from the early stage and the suppression of the levitation force due to the flooding of the outer surface (see, for example, Patent Document 2).
[0005]
On the other hand, as a filter medium composed of an open-cell foam, a filter medium made hydrophilic by mixing 1 to 15 parts by weight of nonionic surfactant such as aliphatic glycerin ester in 100 parts by weight of resin has been proposed. (For example, refer to Patent Document 3). This Patent Document 3 describes the use of a filter medium as a microorganism propagation carrier filled in a biological filtration septic tank, and there is no description regarding the shape of the carrier, but what is probably cut into small pieces is submerged. It is considered to be used. Using the same technique, a microorganism propagation carrier having 0.1 to 5 parts by weight of an anionic surfactant and a nonionic surfactant applied or impregnated per 100 parts by weight of resin in an open-cell foamed resin. A technique (for example, refer to Patent Document 4) aimed at improving the treatment ability of microorganisms by submerging the microorganism propagation carrier in treated water at an early stage by using it has been proposed. The technique described in Patent Document 4 is similar to the present application in that a foam and a surfactant are used, but differs in production method, shape, open cell ratio, floatability, and purpose of use.
[0006]
Of the conventional filter media, filter media with a specific gravity heavier than water are often placed on a restraining mesh and water treatment is carried out in a descending water flow. When suspended substances (SS components) coagulate and settle, It is in the direction of clogging by depositing on the filter medium. In the case of treating this with an upward water flow, the speed of the upward water flow is limited to be extremely low in order to prevent the filter medium from floating on the restraining mesh. For this reason, a method may be used in which a suppression mesh is provided in the water to be treated with a spacing between the top and bottom, and a filter medium is inserted between the two suppression meshes. However, the packing density of the filter medium and the packing density of the filter medium change due to the compression deformation of the filter medium. There is a problem that the filtration effect changes. In this respect, the buoyant filter medium was moderately compressed by its own buoyancy on the lower side of the deterrence mesh even if the deterrence mesh was placed only on the upper side of the filter medium and the filter medium to be lifted was received with the deterrence mesh. A layer of filter media can be formed. Therefore, by determining the buoyancy of the filter medium and the layer thickness of the filter medium, a stable filtering effect can be produced even with an early upward water flow. In addition, the aggregated precipitate such as the suspended matter SS sinks downward and is unlikely to cause clogging of the filter medium. Further, even if the buoyancy of the buoyant filter medium is a descending water flow, if the buoyancy surpasses this flow, the filter medium does not float and adsorption filtration is performed stably.
[0007]
The filter medium excellent in buoyancy and filterability is preferably a foamed plastic strip or particle, but the foamed cell structure is also important as well as the shape. Strips and particles made of open-celled foam are liable to settle when water is absorbed, and the buoyancy is reduced, making them unsuitable for water treatment in upward water flow. Moreover, since the foamed spherical particles of the expanded polystyrene are particles having closed cells close to 100%, the buoyancy is too large, and the gap between the filled particles is large and the filtration performance is inferior.
In this respect, the pulverized particles obtained by pulverizing the closed cell foam are composed of closed cells that are not destroyed in the center and broken cells in the outer surface, and have moderate buoyancy, while being contaminated in water. It can be said that it is an excellent adsorptive filter medium that can have a wide contact area with a substance.
[0008]
[Patent Document 1]
Japanese Patent No. 2726376
[Patent Document 2]
JP-A-8-141588
[Patent Document 3]
JP 2001-342277 A
[Patent Document 4]
JP 2002-199879 A
[0009]
[Problems to be solved by the invention]
By the way, even when using pulverized particles obtained by pulverizing closed-cell foams as described in Patent Documents 1 and 2, there are the following problems.
That is, plastics are generally water repellent and are not compatible with water. Even if it is made to foam, its properties do not change, and even if it is submerged in water, bubbles are involved and adsorption of contaminants in the water and the efficiency of filtration are reduced. In view of this, in Patent Document 2, hydrophilic powders such as calcium carbonate are kneaded in a foam resin to make them hydrophilic, and improvements are made. However, the inorganic filler itself has a high specific gravity, and when added in a large amount, the buoyancy is reduced and the closed cells are destroyed, which also causes a decrease in buoyancy.
[0010]
In addition, various types of pollutants are contained in various wastewaters such as domestic wastewater, factory wastewater, agricultural wastewater, and road wastewater. In general, organic substances represented by BOD and COD, suspended substances such as organic nitrogen and organic phosphorus, ionic low molecules such as inorganic nitrogen and inorganic phosphorus, and water-soluble difficulty such as humic substances For example, if it is wastewater from a food factory or chemical manufacturing industry, it will contain pollutants specific to that product. If it is road-related wastewater, it will contain gasoline from automobiles, exhaust gas components, tire wear dust, etc. , Asphalt wear dust, dust deposits that were in the atmosphere. In this way, wastewater treatment methods must be examined on the assumption that wastewater contains a wide variety of pollutants. However, the closed-cell foamed pulverized particles described in Patent Documents 1 and 2 will be adsorbed or filtered if they are relatively high-molecular suspended substances, and can be agglomerated and precipitated. However, there is a disadvantage that ionic substances and humic substances of water-soluble polymers cannot be captured.
[0011]
An object of the present invention is to provide a pollutant removing material which is a pulverized particle of a closed cell polyolefin-based foam having excellent buoyancy and has a hydrophilic property and adsorbs an ionic substance in waste water. is there.
[0012]
[Means for Solving the Problems]
As a result of intensive studies, the present inventors have found that pulverized particles of a closed-cell polyolefin-based foam obtained by kneading a surfactant in a resin can solve the above problems, and have completed the present invention.
[0013]
The pollutant removing material according to the present invention is a pollutant removing material that adsorbs and filters the pollutants contained in the water to be treated, and the surfactant is kneaded into the resin of the closed-cell polyolefin foam. And made of pulverized particles of the foam.
[0014]
Here, as the surfactant, any one or two or more of four types of surfactants such as a cationic surfactant, an anionic surfactant, an amphoteric surfactant and a nonionic surfactant are used. Activators can be used. The appropriate value for the number of parts by weight of the surfactant to be kneaded is preferably set to 0.01 to 10 parts by weight with respect to 100 parts by weight of the resin before foaming of the closed cell polyolefin-based foam. Further, the diameter of the closed cell of the closed cell polyolefin-based foam is also involved in the adhesion and filtration performance of the contaminant removing material, and the value is preferably limited to 10 to 500 μm.
[0015]
As the pulverized particles of the closed-cell polyolefin foam, any one or two pulverized particles of the raw material beads and the foam-molded product of the in-mold foam molding method can be adopted. As the size of the pulverized particles, those pulverized so that the minor axis is 1 mm to 30 mm can be suitably used.
[0016]
Furthermore, the ability of adsorption and filtration can be widely adjusted according to the type of ionic substance in the waste water, so that the pulverized particles include cationic surfactants, anionic surfactants, amphoteric surfactants and nonionic interfaces. Of the four types of surfactants, a mixture of a plurality of types of pulverized particles in which different types of surfactants are kneaded in a resin can be suitably used.
[0017]
The pollutant removal method according to the present invention is a method of forming a pollutant removal material according to any one of claims 1 to 7 in a layered manner with a certain thickness so as to cross the distribution path in the middle of the distribution path of the water to be treated. The water to be treated is disposed so as to pass through the pollutant removing material layer, thereby adsorbing and filtering the pollutants contained in the water to be treated.
[0018]
Here, depending on the type of ionic substance in the wastewater, there is a merit that the ability of adsorption and filtration can be widely adjusted. Therefore, a plurality of the pollutant removal material layers are arranged in the middle of the distribution path to remove the pollutant. As the pulverized particles constituting each material layer, different types of surfactants among four types of surfactants, cationic surfactants, anionic surfactants, amphoteric surfactants and nonionic surfactants, are resins. It is preferable to use the pulverized particles kneaded therein to adsorb and filter the contaminants contained in the water to be treated in stages.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
The contaminant removing material of the present invention is made of pulverized particles of a closed-cell polyolefin foam in which a surfactant is kneaded in a resin.
The polyolefin resin used in the closed cell polyolefin foam of the present invention contains 50% or more, more preferably 70% or more and 100% or less of an olefin monomer unit, and is copolymerizable with the olefin monomer. It is a resin containing monomer units of 50% or less, further 30% or less and 0% or more. Specific examples of the olefin monomer include α-olefin monomers having 2 to 8 carbon atoms such as ethylene, propylene, butene, pentene, hexene, heptene and octene, and cyclic olefins such as norbornene monomers. These may be used alone or in combination of two or more. Specific examples of the monomer copolymerizable with the olefin monomer include (alcohol) having 1 to 6 carbon atoms in an alkyl group such as vinyl alcohol such as vinyl acetate, methyl methacrylate, ethyl acrylate, hexyl acrylate, and the like. Examples include alkyl acrylates, vinyl alcohol, methacrylic acid, and vinyl chloride. These may be used alone or in combination of two or more.
[0020]
Further, specific examples of the polyolefin resin include polypropylene resins such as ethylene-propylene random copolymer, ethylene-propylene-butene random terpolymer, polyethylene-polypropylene block copolymer, homopolypropylene; low density polyethylene And polyethylene resins such as medium density polyethylene, high density polyethylene, linear low density polyethylene, ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer; polybutene, polypentene and the like. These polymers may be used independently and may use 2 or more types together. The polyolefin-based resin may be used without cross-linking, but may be used after cross-linking with peroxide or radiation.
[0021]
The surfactant used in the present invention is not particularly limited, but preferably includes a cationic surfactant, an anionic surfactant, an amphoteric surfactant, and a nonionic surfactant. Can be used. Since all of the above surfactants have a hydrophilic group, there is little entrainment of bubbles during water immersion, and the efficiency of wastewater treatment is improved. In addition, ionic surfactants such as cationic surfactants, anionic surfactants, and amphoteric surfactants are excellent contaminant removal materials because they have the ability to adsorb and filter ionic substances from pollutants in wastewater. It becomes. Contaminant removing material consisting of pulverized particles of closed-cell polyolefin foam in which one or more surfactants are kneaded in the resin is used to remove contaminants such as ionic substances in wastewater as water to be treated. Depending on the contents, it is possible to enhance the adsorption filtration effect by using different types.
[0022]
A typical surfactant used in the present invention will be described. Examples of the cationic surfactant include alkyl sulfonate, alkyl benzene sulfonate, alkyl sulfate ester salt, alkyl ethoxy sulfate ester salt, and alkyl phosphate ester salt. Examples of the anionic surfactant include alkyltrimethylammonium salt, acyloylamidopropyltrimethylammonium methosulfate, alkylbenzyldimethylammonium salt, and acylcholine chloride. Examples of the amphoteric surfactant include alkylbetaine. Type, imidazoline type, alanine type and the like. Nonionic surfactants include fatty acid alkylolamide, di- (2-hydroxyethyl) alkylamine, polyoxyethylene alkylamine, fatty acid glycerin. Esters, polyoxyethylene glycol fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene alkyl phenyl ethers, the like can be exemplified polyoxyethylene alkyl ethers.
[0023]
Furthermore, the present invention provides a plurality of types of pulverization in which different types of surfactants are kneaded among the four types of surfactants of cationic surfactants, anionic surfactants, amphoteric surfactants and nonionic surfactants. We propose to mix and use the particles, select the type of surfactant ions according to the physical properties of the ionic substances and other contaminants in the wastewater as the water to be treated, and determine the combination and blending ratio in advance. It is possible to enhance the adsorption filtration effect by deciding to use.
[0024]
The number of parts by weight of the surfactant is preferably 0.01 to 10 parts by weight with respect to 100 parts by weight of the resin before foaming the closed cell polyolefin-based foam. More preferably, it is 0.05-5 weight part. If the amount is too small, the adsorptive filtration effect and sustainability of the ionic substance may be inferior. If the amount is too large, bubbles may be generated more than necessary near the pulverized particles.
[0025]
In the present invention, pulverized particles obtained by pulverizing closed-cell polyolefin-based foams are used for the purpose of providing appropriate buoyancy. In other words, when the closed cell polyolefin-based foam is pulverized, the center part of the pulverized small piece is in a state of maintaining closed cells, but in the outer surface part, the bubbles are broken (opened), and the bubbles on the outer surface part are covered. As the water to be treated enters, the contact area with the water to be treated can be increased and the levitation force can be adjusted. As the pulverized particles, for example, irregularly shaped small pieces obtained by pulverizing a plate-like foam with a pulverizer or a crusher can be preferably used, but closed cells remain in the center and the outer surface is independent. If the bubbles are broken, it is possible to adopt a cut piece of a certain size.
[0026]
In addition to being a durable resin, the preferred reason is that the polyolefin resin is a crystalline polymer that has a low glass transition temperature and microbrown motion within the segment even at room temperature, resulting in surface migration of the surfactant. This occurs because even if the surfactant on the surface is washed away, it is replenished from the inside, so the adsorption filtration effect lasts long. This point has a glass transition temperature higher than room temperature for amorphous polymers such as polystyrene. This is because there are many things that do not have this property.
[0027]
Contaminant removing material consisting of surfactant-containing pulverized particles having closed cells at the center of the present invention and bubbles broken at the outer surface is charged with polyolefin resin and surfactant in an extruder. , A method of extrusion foaming with a decomposable foaming agent or a volatile foaming agent, and adding a crosslinking agent, a foaming aid, etc. as necessary in addition to the thermal decomposable foaming agent to the polyolefin resin and surfactant, Manufactured by a batch type foaming method in which the decomposable foaming agent is melt-kneaded with a roll or mixer at a temperature that does not thermally decompose, and after molding into a predetermined shape in a mold, the pyrolyzable foaming agent is foamed at a temperature that allows foaming. Can be produced by pulverizing the foam, but the closed cell ratio of the polyolefin resin foam is close to 100% and spherical cells are obtained. Or it is preferably ground particles of a foamed molded article.
[0028]
The raw material beads of the polyolefin foam are, for example, a surfactant and an olefin resin that are extruded into a thread while being kneaded with a screw of an extruder, and cut to obtain a pellet. Disperse in a water-based medium with a dispersant in a sealed pressure vessel, add a volatile foaming agent, heat to a foaming temperature equal to or higher than the softening temperature of the pellet, and release into an atmosphere at a pressure lower than the internal pressure of the sealed pressure vessel. It is a pre-expanded particle obtained. The pre-expanded particles may be pulverized by a pulverizer or a crusher. However, the pollutant removing material of the present invention can be obtained by pulverizing a molded product obtained by foam molding in a bead method using a pulverizer or a crusher. it can.
[0029]
The bead method in-mold foam molding method is typically a foam molding method in bead method foamed polystyrene. In this method, spherical fine polystyrene beads in which a volatile foam material is dissolved are steam-heated with a pre-foaming machine to obtain pre-foamed particles having a desired expansion ratio (density). Next, the mold that can be opened and closed installed in the foam molding machine is closed, the space of the mold is filled with the pre-expanded particles, and a myriad of arrangements are made on the mold surface from the steam chamber installed around the mold A method of obtaining a foamed molded article having a desired shape by injecting steam into the mold from the formed small holes, foaming, filling the voids between the filled particles, melting and fixing the particles, and opening the mold after cooling It is. The beaded foamed polyolefin resin is basically manufactured in the same manner, except that the polyolefin resin does not have the power to dissolve the solvent-type foaming agent, and the secondary foamed pre-expanded particles after foaming. Since the foaming surplus power is weak, it is necessary to perform a process such as pressurizing and encapsulating the inorganic gas in the pre-expanded particles before filling the mold, or filling the mold by press-shrinking the pre-expanded particles.
[0030]
The closed cell diameter of the closed cell polyolefin-based foam is preferably 10 to 500 μm. The smaller the diameter of the closed cell, the higher the specific surface area of the broken bubbles around the pulverized particles and the more chance of contact with the water contaminants to be treated. There is. When the diameter of the closed cell is increased, the specific surface area is decreased, and the chance of contact with contaminants in water to be treated may be decreased.
[0031]
The method for measuring the diameter of closed cells is to measure the foam with a cutter knife about 3 x 3 cm. 2 Cut to the above cut surface, and countless number of closed cells on the cut surface are colored with ink or magic ink. Look through a magnifying glass with a scale (magnification 40 or 80), and straight on the scale (for example, 20 mm) The number of closed cells was counted and the average bubble diameter per closed cell was obtained.
[0032]
The size of the pulverized particles of the closed cell polyolefin-based foam is preferably 1 mm to 30 mm, more preferably 2 to 5 mm, with a short diameter. If it is too small, it may break down to the closed cells in the center and reduce buoyancy. Conversely, if it is too large, the buoyancy will be too large and the specific surface area will be reduced, reducing the chance of contact with the contaminants in the water to be treated. There is. The pulverized particles having such a size can be selected using two types of sieves having different mesh sizes. The pulverized particles that pass through a sieve having a mesh size of 30 mm to 5 mm and do not pass through a sieve having a mesh size of 1 mm to 2 mm are required. It will be used as pulverized particles.
[0033]
Next, an example of a wastewater treatment facility using a contaminant removing material will be briefly described.
As shown in FIG. 1, a treatment tank 10 through which drainage as treated water 1 flows is provided, an inlet pipe 11 for treated water 1 is connected to the lower part of the treated tank 10, and an upper part of the treated tank 10 is An outlet pipe 12 for the treated water 2 from which contaminants have been removed is connected. A deterrence mesh 13 is provided in the upper part of the treatment tank 10 below the liquid level 3 of the treated water 2 so as to cross the flow path of the treated water 1 in the treatment tank 10, and the contaminant removing material 14 is Due to the buoyancy, it is arranged in a layered manner under the restraining mesh 13. Reference numeral 15 denotes a discharge pipe for discharging the pollutant 4 precipitated in the lower part of the processing tank 10 from the lower end of the processing tank 10, and reference numeral 16 denotes a valve for opening and closing the discharge pipe 15.
[0034]
When removing contaminants in the treated water 1, the treated water 1 passes through the contaminant removing material 14 by supplying the treated water 1 from the inlet pipe 11 into the lower portion of the treatment tank 10. In the process of moving upward and passing through the contaminant removal material 14, the contaminant contained in the treated water 1 is removed and discharged from the outlet pipe 12 as treated water 2.
[0035]
Moreover, when using several types of contaminant removal material from which a process target differs, for example, as shown in FIG. 2, a pair of upper and lower restraining meshes 13A crossing the flow path of the treated water 1 in the treatment tank 10 is used. , 13B may be arranged at intervals, and different types of contaminant removing materials 14A, 14B may be arranged in layers below the respective deterrence meshes 13A, 13B. Specifically, as the pulverized particles constituting each pollutant removing material layer, four types of surfactants such as a cationic surfactant, an anionic surfactant, an amphoteric surfactant and a nonionic surfactant are used. Of these, pulverized particles in which different types of surfactants are kneaded in the resin are used to gradually adsorb and filter contaminants contained in the water 1 to be treated. When configured in this way, the type of surfactant ions is selected so that the physical properties of the contaminants such as ionic substances in the water to be treated 1 are matched, and the combination and thickness of the contaminant removal layer are set in advance. It is possible to enhance the adsorption filtration effect. It is also possible to provide three or more layers of different types of pollutant removal materials so as to suit the physical properties of the pollutants.
[0036]
【Example】
In the following, embodiments of production of a pollutant removing material and wastewater treatment according to the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.
Example 1 100 parts by weight of large pellets of ethylene-propylene random copolymer having an ethylene content of 3%, 1.0 part by weight of a cationic surfactant, acyloylamidopropyltrimethylammonium sulfate, and a foam nucleating agent The additive was masterbatched, melted and kneaded in an extruder, extruded into a yarn shape, and small pellets having a diameter of about 0.7 mm and a length of about 10 mm were produced with a pelletizer. The small pellets were charged into a pressure vessel together with water and a dispersing agent and stirred with a stirring blade. Steam was added to the jacket of the pressure vessel and the temperature was raised. The volatile foaming agent butane was introduced in the middle of the temperature elevation, the temperature in the pressure vessel was 150 ° C., and the pressure was 1.667 MPa (17 kg / cm 2 ) Added butane until stable. Next, a 6 mm diameter circular hole in the partition plate of the pipe connected to the pressure vessel was opened and released into the atmosphere for foaming. During this time, butane was continuously added so that the pressure in the pressure vessel became constant. The obtained pre-expanded particles are almost spherical with a diameter of about 3 mm, and the expansion ratio is 5 times (density = 0.18 g / cm). 3 ) Had a closed cell ratio of about 98%. The pre-expanded particles were charged into a pressurized tank and air-pressurized to impregnate pressurized air into countless closed cells without expanded particles. The air pressure in the closed cells was 1520 hPa (1.5 atm). Next, pre-expanded particles impregnated with pressurized air are closed in a mold that can be opened and closed mounted on a foam molding machine, and the mold is filled with a filler, and a steam chamber attached to the mold is attached. Steam was introduced from the chamber through innumerable pores on the mold surface and heated and foamed at about 140 ° C. After cooling, the product was taken out from the mold to obtain a foamed product of a plate-like body. As a result of measurement, the average bubble diameter was about 180 μm. Next, the foamed molded product of the plate-like body is put into a crushing machine having a crushing rotor having a plurality of blades set and a supply press shear that presses the crushing object against the crushing rotor and pulverized, and passed through a screen having a mesh size of 5 mm. In addition, it is sieved with a screen with a mesh size of 2 mm, and becomes an example of the present invention having a minor axis of 2 to 5 mm and an average of about 3 mm, and has a closed cell in the center, in which a cationic surfactant is kneaded into the resin, A pollutant removing material which is a pulverized particle of a closed cell polyolefin-based foam having excellent buoyancy and having broken bubbles on the outer periphery was obtained.
[0037]
(Example 2) In the same manner as in Example 1, 1.0 part by weight of an alkyl phosphate ester salt of an anionic surfactant was kneaded into 100 parts by weight of a polypropylene random copolymer having an ethylene content of 3%. A contaminant removing material, which is a pulverized particle of a closed-cell polyolefin-based foam, was obtained.
[0038]
(Example 3) In the same manner as in Example 1, 1.0 part by weight of a nonionic surfactant di- (2-hydroxyethyl) alkylamine with respect to 100 parts by weight of a polypropylene random copolymer having an ethylene content of 3% Thus, a pollutant removing material which is a pulverized particle of a closed-cell polyolefin foam was obtained.
[0039]
(Example 4) In the same manner as in Example 1, 0.5 parts by weight of the cationic surfactant acyloylamidopropyltrimethylammonium sulfate and an anion were added to 100 parts by weight of a polypropylene random copolymer having an ethylene content of 3%. A contaminant removing material, which is a pulverized particle of a closed-cell polyolefin foam, kneaded with 0.5 part by weight of an alkyl phosphate ester salt of a surfactant.
[0040]
(Example 5) A pollutant removing material obtained by mixing 50% of the pulverized particles kneaded with the cationic surfactant obtained in Example 1 and 50% of the pulverized particles containing the anionic surfactant of Example 2. Got.
[0041]
(Example 6) Pollutant removal material consisting of pulverized particles kneaded with the cationic surfactant obtained in Example 1 and contaminant removal consisting of pulverized particles containing the anionic surfactant of Example 2 The material was used.
[0042]
(Embodiment 7) Basically, it is the same method as in Embodiment 1, but it is set to a low value in accordance with the heat resistance of the resin, such as the temperature and pressure of pre-foaming conditions and the temperature of foam molding, and air impregnation is performed. Omitted, 100 parts by weight of linear low density polyethylene, kneaded 0.5 parts by weight of anionic surfactant alkyl phosphate ester salt, closed cell polyolefin having a foaming ratio of 10 times and a cell diameter of 250 μm A pollutant-removing material, which is a pulverized particle of the system foam, was obtained.
[0043]
(Example 8) Similarly, a closed-cell polyolefin system in which 0.5 parts by weight of a nonionic surfactant di- (2-hydroxyethyl) alkylamine was kneaded with 100 parts by weight of a linear low-density polyethylene. A pollutant-removing material which is a pulverized particle of the foam was obtained.
[0044]
(Comparative Example 1) In the same manner as in Example 1, a surfactant removing agent was not added to a polypropylene random copolymer having an ethylene content of 3%, and a pollutant removing material that was a pulverized particle of a closed-cell polyolefin foam was obtained.
[0045]
(Evaluation test)
For Examples 1 to 5, 7, 8, and Comparative Example 1, the wastewater treatment facility shown in FIG. 1 was used, and a pollutant removing material was formed in a layer so that the thickness was 30 cm below the suppression mesh 13. Then, the contaminant adsorption with the contaminant removal material and the filtration performance test were conducted. For Example 6, the waste water treatment facility shown in FIG. 2 was used, and the thickness of the pollutant removing material made of pulverized particles in which a cationic surfactant was kneaded under the lower deterrent mesh 13B was reduced. Formed in layers so as to be 15 cm, and formed in layers so that a contaminant removing material made of pulverized particles in which an anionic surfactant is kneaded under the upper deterrent mesh 13A is 15 cm in thickness. Then, the adsorption of contaminants and the filtration performance test with both contaminant removal materials were conducted.
[0046]
As a result, in any of Examples 1 to 8, compared to Comparative Example 1, organic substances represented by BOD and COD, suspended substances such as organic nitrogen and organic phosphorus, inorganic nitrogen, and inorganic phosphorus It has been confirmed that ionic low molecules such as humic substances and water-soluble persistent substances such as humic substances are efficiently removed. In addition, it has been found that gasoline, exhaust gas components, tire wear dust, asphalt wear dust, and dust deposits in the atmosphere that are road drainage are also effectively removed.
[0047]
【The invention's effect】
The contaminant removal material according to the present invention has the following effects.
Using pulverized particles of closed-cell polyolefin foam, the central part of the pulverized particles is in a state where closed cells remain, but the outer surface part is in a state where the bubbles are broken (opened), and water can enter. Since it has a structure, the buoyancy of the pulverized particles can be easily adjusted by adjusting the size, and by providing an appropriate buoyancy to the pulverized particles, a stable filtration effect can be obtained even with a fast upward water flow In addition, it is possible to improve the contaminant removal performance by setting a large contact area between water and the pulverized particles.
[0048]
Moreover, since the surfactant is kneaded in the resin constituting the pulverized particles, various ions present on the surface of the pulverized particles can be adjusted from positive ions to negative ions depending on the selection of the surfactant. For this reason, the ability to adsorb and filter ionic substances in the wastewater as the treated water can be adjusted widely, and the surface active agent within the resin moves to the surface over time, so the effect is sustained. In addition, it is possible to provide a new contaminant removing material that takes advantage of the characteristics of buoyant filter media.
[0049]
Here, as the surfactant, any one or two or more kinds of surfactants of four kinds of surfactants, a cationic surfactant, an anionic surfactant, an amphoteric surfactant and a nonionic surfactant are used. When the agent is used, the type of surfactant ion is selected according to the physical properties of the pollutant such as ionic substances in the wastewater as the water to be treated, and the combination and blending ratio of the surfactant are determined in advance. By using it, it becomes possible to enhance the adsorption filtration effect.
[0050]
If the number of parts by weight of the surfactant is set to 0.01 to 10 parts by weight with respect to 100 parts by weight of the resin before foaming of the closed cell polyolefin foam, the adsorption filtration effect and sustainability of the ionic substance can be increased. Sufficient foaming can be ensured and more than necessary foaming can be prevented in the vicinity of the pulverized particles.
[0051]
When the diameter of the closed cell of the closed cell polyolefin-based foam is set to 10 to 500 μm, it is possible to sufficiently secure the capture performance for SS while increasing the contact area between the water to be treated and the pulverized particles. .
[0052]
When the minor axis of the pulverized particles is set to 1 mm to 30 mm, the buoyancy of the pulverized particles can be appropriately set, and the contact area between the water to be treated and the pulverized particles can be sufficiently secured.
[0053]
Plural types of pulverized particles in which different types of surfactants are kneaded into the resin among four types of surfactants, cationic surfactants, anionic surfactants, amphoteric surfactants and nonionic surfactants If a mixture of pulverized particles is used, the adsorption and filtration capabilities can be widely adjusted according to the type of ionic substance in the waste water.
[0054]
According to the pollutant removing method of the present invention, since the pollutant removing material according to any one of claims 1 to 7 is used, the same effect as any one of claims 1 to 7 is obtained. It is done.
[0055]
Here, a plurality of the pollutant removing material layers are arranged in the middle of the distribution channel, and as the pulverized particles constituting each pollutant removing material layer, a cationic surfactant, an anionic surfactant, an amphoteric surfactant When pulverized particles in which different types of surfactants are kneaded into the resin among the four types of surfactants, the nonionic surfactant and the nonionic surfactant, the contaminants contained in the water to be treated are adsorbed and filtered in stages. By selecting the pollutant removal material according to the type of ionic substances in the wastewater, the ability to adsorb and filter pollutants can be adjusted widely.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of wastewater treatment equipment
FIG. 2 is an explanatory diagram of a wastewater treatment facility having another configuration.
[Explanation of symbols]
1 treated water 2 treated water
3 Liquid level
10 treatment tank 11 inlet pipe
12 outlet pipe 13 restraining mesh
14 Pollutant removal material 15 Discharge pipe
16 Valve
13A inhibition mesh 13B inhibition mesh
14A Pollutant removal material 14B Pollutant removal material
