JP3890461B2

JP3890461B2 - SS removal treatment method for yard drainage

Info

Publication number: JP3890461B2
Application number: JP26261799A
Authority: JP
Inventors: 和久福永; 達也加藤; 敏近藤
Original assignee: Nippon Steel Corp; Nippon Steel Engineering Co Ltd
Current assignee: Nippon Steel Corp; Nippon Steel Engineering Co Ltd
Priority date: 1999-09-16
Filing date: 1999-09-16
Publication date: 2007-03-07
Anticipated expiration: 2019-09-16
Also published as: JP2001079562A

Description

【０００１】
【発明の属する技術分野】
本発明は、粉粒体（塊を含み、以下「粉粒体」という。）を貯蔵した野外ヤードで、散水や雨水などにより生じるＳＳを含む排水の処理方法に関するものである。
【０００２】
【従来の技術】
例えば、製鉄業での排水としては、大別して
（１）工場の生産活動に伴って冷却、洗浄時に発生する冷却排水、洗浄排水などの工場排水
（２）降雨に伴って発生する雨水排水
がある。
【０００３】
従来は、主として（１）の工場排水に対して公害防止対策を講じていたが、最近、公害に対する認識の高まりから雨天時の対策も講じている。ローカル条件によって程度の差はあるが、降雨に伴って公害上の問題を発生する場所と公害対象（物質）としては、
１．原料、副原料、石炭ヤード・・ＳＳ（浮遊性物質）、色度、ＰＨ
２．スクラップヤード・・・・・・ＳＳ、色度、油
３．バラスヤード・・・・・・・・ＳＳ、ＰＨ
などがある。
【０００４】
従来、これらの野外ヤードの排水処理プロセスの内、ＳＳを除去する排水処理プロセスとしては、図６に示すように、例えば鉄鉱石１の貯蔵ヤード２からの多量のＳＳを含むヤード排水３をＵ字溝４を経てポンプピット５に集め、ポンプピット５からポンプＰａで調整槽６に集めて水量調整してから、凝集剤７や処理剤８を添加した撹拌器９付きの凝集反応槽１０経由で沈殿池１１に導き、凝集反応槽１０で凝集させたＳＳを沈殿させて除去し、水槽１２経由で無害化した上澄水３ｃを水槽１２経由で河川や海に放流する排水処理プロセスが知られている。この従来の排水処理プロセスでは、晴天時、雨天時を兼ねるようになっており、最大降雨量を想定した容量を処理できるように大規模の凝集反応槽１０と沈殿池１１が配置されているため設備コスト負担が大きい。
【０００５】
近年、ヤード２からの粉塵の飛散を防止する観点から、晴天時の散水が増えており、少水量ながらＳＳを含む排水３が絶えることはなく、排水処理は毎日行われている。
この排水処理においては、雨天時の排水量に対応する大容量の凝集反応槽１０に凝集剤７を添加して排水４中のＳＳを凝集し、大きなＳＳフロックを生成して沈殿池１１で沈殿させ、上澄水３ｃを放流するものであり、凝集反応槽１０において添加される凝集剤７の量が少ないと、ＳＳフロックが微細になり、沈殿池１１からの流量を絞ってもＳＳフロックが流出して水質規制に触れる懸念があることから、凝集剤７の添加量はＳＳ濃度の変化が激しい晴天時をベースに決めていることが多い。
【０００６】
しかし、晴天時でもＳＳ濃度が大きく異なる。特に溝に溜まったＳＳが一気にはきだされるため、ＳＳ濃度は排水初期に高く、次第に安定化する傾向がある。また、雨天時には、排水量が晴天時の２〜１０倍まで増加することがあり、降雨量が多くなるほど排水３中のＳＳ濃度が低くなる。
【０００７】
このように、排水中のＳＳ濃度が大きく変化するにもかかわらず、従来、凝集剤７の添加量をＳＳ濃度の高い晴天時をベースとして設定しており、比較的高価な凝集剤７の消費量が多く、排水処理コスト負担が大きいという問題もある。
【０００８】
【発明が解決しようとする課題】
本発明は、ヤードの排水中のＳＳを除去する排水処理方法において、設備コスト負担を軽減するとともに、凝集剤のコスト負担を大幅に節減して、排水処理コスト負担を大幅に軽減できる排水処理方法を提供するものである。
【０００９】
【課題を解決するための手段】
本発明は、下記（１）〜（７）の発明から構成されるものである。
（１）．濾過もしくは凝集濾過による少水量高濃度ＳＳ排水処理プロセスと凝集沈殿による雨天時の多水量低濃度ＳＳ排水処理プロセスを切り替えて用いる、ＳＳを含むヤード排水の処理方法であって、晴天時の散水による少水量で高濃度のＳＳを含むヤード排水を前記少水量高濃度ＳＳ排水処理プロセスで処理し、基準降雨量を超えたときの多水量で低濃度のＳＳを含むヤード排水を前記多水量低濃度ＳＳ排水処理プロセスで処理することを特徴とするヤード排水のＳＳ除去処理方法。
（２）．濾過もしくは凝集濾過による少水量高濃度ＳＳ排水処理プロセスと凝集沈殿による多水量ＳＳ排水処理プロセスを併用する、ＳＳを含むヤード排水の処理方法であって、晴天時の少水量で高濃度のＳＳ排水を少水量高濃度ＳＳ排水処理プロセスで処理し、雨天時には、多水量で低濃度のＳＳ排水を多水量低濃度ＳＳ排水処理プロセスにオーバーフロー（またはバイパス）させて導入し、少水量高濃度ＳＳ排水処理プロセスと多水量低濃度ＳＳ排水処理プロセスを併用して処理することを特徴とするヤード排水のＳＳ除去処理方法。
（３）．（１）または（２）において、少水量高濃度ＳＳ排水処理プロセスと多水量低濃度ＳＳ排水処理プロセスの切り替えの時期を、降雨量情報で判定することを特徴とするヤード排水のＳＳ除去処理方法。
（４）．（１）または（２）において、少水量高濃度ＳＳ排水処理プロセスと多水量低濃度ＳＳ排水処理プロセスの切り替えの時期を、これらの排水処理プロセスの前段の原水槽または調整槽の水位レベルで判定することを特徴とするヤード排水のＳＳ除去処理方法。
（５）．濾過もしくは凝集濾過による少水量高濃度ＳＳ排水処理プロセスと凝集沈殿による多水量低濃度ＳＳ排水処理プロセスを併用する、ＳＳを含むヤード排水の処理方法であって、多水量ＳＳ排水処理プロセスの前段に晴天時の少水量高濃度ＳＳ排水プロセスを直列配置し、少水量で高濃度のＳＳを含む排水と、多水量で低濃度のＳＳを含む排水を、まず少水量高濃度ＳＳ排水処理プロセスで処理し、ついで多水量低濃度ＳＳ排水処理プロセスで処理することを特徴とするヤード排水のＳＳ除去処理方法。
（６）．濾過もしくは凝集濾過による少水量高濃度ＳＳ排水処理プロセスと凝集沈殿による多水量低濃度ＳＳ排水処理プロセスを併用する、ＳＳを含むヤード排水の処理方法であって、晴天時の少水量高濃度ＳＳ排水プロセスの前段に多水量低濃度ＳＳ排水処理プロセスを直列配置し、少水量で高濃度のＳＳを含む排水と、多水量で低濃度のＳＳを含む排水を、まず多水量低濃度ＳＳ排水処理プロセスでで処理し、ついで少水量高濃度ＳＳ排水処理プロセスで処理することを特徴とするヤード排水のＳＳ除去処理方法。
（７）．（１）〜（６）のいずれかにおいて、少水量高濃度ＳＳ排水処理プロセスの濾過機の逆洗水を、多水量低濃度ＳＳ排水処理プロセスに導入して処理することを特徴とするヤード排水のＳＳ除去処理方法。
【００１０】
【発明の実施の形態】
本発明は、主として粉粒体を貯蔵する野外ヤードからの排水のＳＳ除去処理方法であり、凝集濾過による少水量高濃度ＳＳ排水処理プロセスと、凝集沈殿による多水量低濃度ＳＳ排水処理プロセスを用いて処理するものであり、基本的には、少水量でＳＳ濃度の高い晴天時（ここでは、降雨のない時、降雨量が少なくて粉粒体が乾燥状態で飛散する状態にある時を意味し、以下「晴天時」という。）の排水処理には、少水量高濃度ＳＳ排水処理プロセスを用い、多水量でＳＳ濃度の低い雨天時の排水には、多水量低濃度ＳＳ排水処理プロセスを用いるものである。
【００１１】
本発明では、少水量高濃度ＳＳ排水処理プロセスには、凝集濾過プロセスを用いるので、晴天時のＳＳ濃度が高い時には５００ｍｇ／リットル以上の比較的高濃度の排水に対して、そのＳＳ濃度に見合う凝集剤が多少不足していても、濾材間に捕捉されているＳＳフロックにＳＳが容易に吸着・捕捉され、ＳＳの除去が確実に行われるので、凝集剤の使用量を従来より５０％程度少なくすることができる。
【００１２】
本発明で用いる凝集濾過プロセスの濾過機としては、天然砂や浮上濾材を濾材として用いる周知の各種濾過機を用いることができるが、濾過機能を安定確保する上で、濾材を気体や液体で逆洗する構造を有するものが有利である。
【００１３】
また、多水量でＳＳ濃度の低い雨天時の排水は、多量でＳＳ濃度は３００ｍｇ／リットルと比較的低いので、凝集剤の使用量は、少水量高濃度ＳＳ排水処理プロセスより少なくてもよいので、少水量高濃度ＳＳ排水処理プロセスと区別して凝集剤の使用量を設定するものであり、従来より５０％程度少なくすることができる。
【００１４】
本発明で用いる凝集剤としては、有機物の高分子凝集剤が多く、他にポリ塩化アルミニウム（ＰＡＣ）などの無機凝集剤、陽イオン性または陰イオン性の界面活性剤などを用いることができる。濾材としては、天然砂が一般的であるが、この限りではない。
【００１５】
ここで、少水量で高濃度のＳＳを含む排水に対して、濾過もしくは凝集濾過プロセスに代えて凝集沈殿プロセスを適用した場合には、生成するＳＳフロックは、結合力の小さい微細なもので軽いため、沈殿池から容易に流出してしまい、ＳＳの除去を確実に行なうことは難しいことから、高濃度のＳＳを除去するためには、大量の凝集剤が必要であり、処理コスト負担が大きくなるので好ましくない。
【００１６】
また、本発明では、多水量低濃度ＳＳ排水処理プロセスには、凝集沈殿プロセスを用いるので、対象流量に応じた容量の沈殿池が必要ではあるが、土木構造物でスケールメリットがあり、容量増加の割合で設備費が増加しないメリットがあり、大型化も容易である。
また、ＳＳを沈殿池で凝集沈殿させるが、ＳＳ濃度は低いので、上記したように、凝集剤の使用量を従来より少なくてもＳＳを容易に凝集沈殿させて除去することができる。
本発明で凝集沈殿に用いる沈殿池としては、横流式沈殿池や円形沈殿池などの周知の各種の沈殿池を用いることができる。
【００１７】
本発明では、基本的には、ヤードからの排水量（晴天時の散水量、雨天時の降雨量）に応じて、少水量高濃度ＳＳ排水処理プロセスと多水量低濃度ＳＳ排水処理プロセスを切り替え使用するものであるが、少水量高濃度ＳＳ排水処理プロセスと多水量低濃度ＳＳ排水処理プロセスを直列に配置して併用して処理を分担し、相互にバックアップできるようにすることも考慮している。
【００１８】
また、凝集濾過による少水量高濃度ＳＳ排水処理プロセスにおいては、濾過機を逆洗するようになっているが、この逆洗後のＳＳを含む逆洗水は、多水量低濃度ＳＳ排水処理プロセスに導入して、多水量低濃度ＳＳ排水とともに処理することが設備コスト負担、処理コスト負担を軽減する上で有効である。
【００１９】
本発明では、凝集濾過による少水量高濃度ＳＳ排水処理プロセスと、凝集沈殿による多水量低濃度ＳＳ排水処理プロセスの切り替えは、ヤードからの排水量（ｔ／ｈｒ）が切り替え条件を満たしたとき（散水の排水量レベルか、基準降雨量を超えた排水量レベルかの判定基準に該当時・・・予め判定基準を設定する）、手動または自動的に行うものであるが、この排水量を判定する手段としては、
（１）．目視で判定する。
（２）．晴天時の散水量でヤードからの排水量を推定する。
（３）．降雨情報（当該地域の降雨予報または当該地域の降雨量実績）でヤードからの排水量を推定する。
（４）．排水処理プロセスの前段の原水槽や調整槽の水位を検知してヤードからの排水量を推定する。
（２）〜（４）では、排水量推定システムと切替システムを連動させることにより少水量高濃度ＳＳ排水処理プロセスと凝集沈殿による多水量低濃度ＳＳ排水処理プロセスを自動切替することも可能である。
【００２０】
本発明では、ＳＳを多量に含むヤード排水を処理対象としているが、例えば、色度、ＰＨ、油、ＣＯＤ（化学的酸素要求量）も併せて処理対象とする場合もあり、この場合には、凝集反応槽に、凝集剤の他にＮａＯＨなどの反応処理剤の添加を含む追加的プロセスがあるが、この場合にも本発明の適用に問題はない。
【００２１】
【実施例】
以下に本発明を、設備配置例とともに説明する。
（実施例１）
図１は、本発明を実施する鉄鉱石貯蔵ヤードの排水処理設備の配置例を示すものである。図１は晴天時の少水量で高濃度ＳＳを含む排水を処理している場合を示し、図２は、雨天時の多水量で低濃度ＳＳを含む排水を処理している場合を示している。
【００２２】
図１、図２において、１はヤード２に貯蔵された鉄鉱石、３は散水によって発生したＳＳを含むヤード排水で、Ｕ字溝４を経て原水槽５に集め、ポンプＰａにより調整槽６を経て、凝集剤７や処理剤８を添加して撹拌機９ａで撹拌処理する反応槽１０ａと給水Ｗして撹拌機９ｂで撹拌処理してＳＳフロックを生長させる凝集槽１０ｂからなる凝集反応槽１０に導入する。凝集反応槽１０で反応・凝集処理され生長したＳＳフロックを含む排水を、本発明の排水処理プロセスに導入して処理する。
【００２３】
この実施例では、反応・凝集処理後の排水処理プロセスは、凝集反応槽１０からの生長したＳＳフロックを含む排水を濾過する濾材及びエアーを用いた、逆洗構造を備えた濾過機１３と、この濾過機を逆洗水で逆洗して濾過機能を維持する逆洗装置１４ａ（供給側）、１４ｂ（排出側）からなる少水量高濃度ＳＳ排水処理プロセスＡと、凝集反応槽１０と連絡管１５ａにより接続され、凝集反応槽１０からの生長したＳＳフロックを含む排水を沈殿処理してＳＳフロックを沈殿除去する沈殿池１１ａからなる多水量低濃度ＳＳ排水処理プロセスＢとを並列的に配置している。
【００２４】
少水量高濃度ＳＳ排水処理プロセスＡは、基本的には、晴天時の少水量で高濃度ＳＳを含む排水を処理するためのものであり、多水量低濃度ＳＳ排水処理プロセスＢは、降雨量が基準降雨量を超えた場合の多水量で低濃度ＳＳを含む排水を処理するものであるが、ここでは、
（１）晴天時の少水量高濃度ＳＳ排水処理プロセスＡ単独（晴天時）
（２）雨天時の多水量低濃度ＳＳ排水処理プロセスＢ単独（雨天時）
（３）晴天時の少水量高濃度ＳＳ排水処理プロセスＡと雨天時の多水量低濃度ＳＳ排水処理プロセスＢを併用（雨天時）
の３通りの排水処理プロセスに手動切替えまたは自動切替え可能にしている。
【００２５】
以下に（１）〜（３）の排水処理について説明する。
［（１）による晴天時の少水量高濃度ＳＳ排水処理プロセスＡによる排水処理］
図１に示すように、散水によって発生したＳＳを含むヤード排水３は、Ｕ字溝４を経て原水槽５に集め、ポンプＰａにより調整槽６に導入し、ポンプＰｂにより凝集剤７や処理剤８を添加して撹拌機９ａで撹拌処理する反応槽１０ａと給水Ｗして撹拌機９ｂで撹拌処理してＳＳフロックを生長させる凝集槽１０ｂからなる凝集反応槽１０に導入して処理する。
ここでは、処理する排水はＳＳ濃度が高い排水であるため、ＳＳフロックの生長をより確実にするために、凝集剤７の添加量を多くする。
反応凝集処理され生長したＳＳフロックを含む排水３を、切替弁Ｖａを開にし、ポンプＰ1 により、晴天時の少水量高濃度ＳＳ排水処理プロセスＡの濾過機１３に導入して濾過し、濾過した排水３を水槽１２経由で放流する。
【００２６】
濾過機１３には、濾過の都度、懸濁物量が抑留され、この懸濁物量が一定のレベルまで増えると、濾過抵抗が大きくなって濾過機能が低下し、懸濁物量が漏出して濾過水質が悪化するので、濾過機１３を、適時、逆洗装置１４ａからの逆洗水及びエアーで逆洗して、濾過機能の低下を防止する。
洗浄後の懸濁物を含む逆洗水は、ここでは沈殿池１１ａに導入して沈殿処理するようにしているが、沈殿池１１ａ外に排出するようにしてもよい。
【００２７】
この（１）の排水処理プロセスは、凝集効率が良好で凝集剤の使用量が少なくてすむ濾過凝集を用いており、凝集剤７の使用量を、沈殿凝集のみの場合に比較して大幅に節減することができるもので、晴天時の少水量高濃度ＳＳ排水の処理に適している。
【００２８】
［（２）による雨天時の多水量低濃度ＳＳ排水処理プロセスＢによる排水処理］
図２に示すように、降雨によって発生したＳＳを含むヤード排水３を、Ｕ字溝４を経て原水槽５に集め、ポンプＰａにより調整槽６に導入し、ポンプＰｂにより凝集剤７や処理剤８を添加して撹拌機９ａで撹拌処理する反応槽１０ａと給水Ｗして撹拌機９ｂで撹拌処理しＳＳフロックを生長させる凝集槽１０ｂとからなる凝集反応槽１０に導入して処理する。
ここでは、処理する排水はＳＳ濃度が低い排水であるため、ＳＳフロックの生長のための凝集剤７の添加量を少なく変更する。
【００２９】
雨天時には、降雨により原水槽５、調整槽６、反応凝集槽１０の水位レベルが高くなるので、例えば原水槽５の水位計１６ａで水位レベルを検知し、この水位が一定レベル以上になった場合には、切替弁Ｖａを閉とし晴天時の少水量高濃度ＳＳ排水処理プロセスＡを閉とするとともに、切替弁Ｖｂを開にして、多水量低濃度ＳＳ排水処理プロセスＢを開とし、反応凝集槽１０からの生長したＳＳフロックを含むＳＳ排水を、連絡管１５経由で沈殿池１１ａに導入する。
【００３０】
降雨が止んで排水量が減少し、晴天時の排水量レベルになった場合には、切り替弁Ｖａを開にして晴天時の少水量高濃度ＳＳ排水処理プロセスＡを開にする。
反応凝集槽１０への凝集剤７の添加量は、ただちに増加させる必要はなく、晴天になって、鉄鉱石が乾燥状態になって散水が必要な状態になってから増加させるようにすればよい。
【００３１】
この（２）の排水処理プロセスにおいては、沈殿池１１ａを用いた凝集沈殿処理を行うが、ＳＳ濃度の低い雨天時のヤード排水の処理を、ＳＳ濃度の高い晴天時のヤード排水の処理と区別して行うので、凝集剤の使用量を少なくしても凝集剤の使用量を節減することができ、ＳＳ濃度の高い晴天時のヤード排水の処理とＳＳ濃度の低い雨天時のヤード排水の処理を、同様にして行う従来の場合に比較して、凝集剤の使用量を節減することができる。
【００３２】
［（３）による晴天時の少水量高濃度ＳＳ排水処理プロセスＡと雨天時の多水量低濃度ＳＳ排水処理プロセスＢを併用する排水処理］
この排水処理は、図１に示すように、散水によって発生したＳＳを含むヤード排水３を晴天時の少水量高濃度ＳＳ排水処理プロセスＡで処理中に、降雨があった場合に、この排水処理プロセスＡの切替弁Ｖａを開の状態にしたまま、図２に示すように、雨天時の多水量低濃度ＳＳ排水処理プロセスＢの切替弁Ｖｂを開にして、この排水処理プロセスＢを開の状態にして、排水処理プロセスＡと排水処理プロセスＢとを併用して処理するものである。
【００３３】
この例では、排水処理プロセスＡから排水処理プロセスＢへ切り替える場合、切替弁Ｖｂを設けて開動作するようにしているが、切替弁Ｖｂは不可欠ではなく、図３に示すように、水位レベルが上昇した時に反応凝集槽１０の生長したＳＳフロックを含むＳＳ排水を、オーバーフロー管１７経由でオーバーフローさせて沈殿池１１ａに導入するようにしてもよい。
【００３４】
ここでは、降雨があってヤード排水が増加し、反応凝集槽１０で処理され生長したＳＳフロックを含む排水の反応凝集槽１０での水位が上昇した時に、この排水をオーバーフロー管１７から自然にオーバーフローさせて、このオーバーフロー分を雨天時の多水量低濃度ＳＳ排水処理プロセスＢに導入して沈殿池１１ａで凝集沈殿処理するようにしたものである。この降雨によるたヤード排水３は、ただちにＳＳ濃度が低い排水になるため、ＳＳフロックの生長のための凝集剤７の添加量を少なく変更する。
【００３５】
この（３）の排水処理プロセスにおいては、凝集効率が良好で凝集剤の使用量が少なくてすむ凝集濾過と、凝集沈殿を併用しており、凝集剤の使用量を、凝集沈殿のみの場合に比較して大幅に節減することができる。
【００３６】
（実施例２）
図４は、この実施例２の排水処理設備の配置例を示す。
この実施例２では、凝集反応槽１０に晴天時の少水量高濃度ＳＳ排水処理プロセスＡ（以下「排水処理プロセスＡ」という。）を接続し、その後段に雨天時の多水量低濃度ＳＳ排水処理プロセスＢ（以下「排水処理プロセスＢ」という。）を直列的に接続して、凝集反応槽１０からの生長したＳＳフロックを含む排水を、まず排水処理プロセスＡで処理し、ついで排水処理プロセスＢで沈殿処理するようにしたものである。
【００３７】
この実施例２では、晴天時の少水量で高濃度ＳＳを含む排水も雨天時の多水量で低濃度ＳＳを含む排水も、排水処理プロセスＡと、その後段に接続した雨天時の排水処理プロセスＢで同様にして処理するものである。
この実施例２では、晴天時の少水量で高濃度ＳＳを含む排水を処理する際に、排水処理プロセスＡの凝集濾過プロセスの逆洗のインターバルが長くなった場合に、ＳＳ捕捉限界を超えて濾過機１３からＳＳフロックが流出した場合、後段の排水処理プロセスＢの沈殿処理で確実に除去することもできる。
【００３８】
（実施例３）
図５は、この実施例３の排水処理設備の配置例を示す。
この実施例３では、凝集反応槽１０に雨天時の排水処理プロセスＢの沈殿池１１ｂを接続し、その後段に排水処理プロセスＡを直列に接続して、その後段に雨天時の排水処理プロセスＢの沈殿池１１ａを直列的に接続して、凝集反応槽１０からの生長したＳＳフロックを含む排水を、まず排水処理プロセスＢの沈殿池１１ｂで凝集沈殿処理し、ついで排水処理プロセスＡで処理してから沈殿池１１ａで沈殿処理するようにしたものである。
【００３９】
この実施例３では、晴天時の少水量で高濃度ＳＳを含む排水も雨天時の多水量で低濃度ＳＳを含む排水も、排水処理プロセスＢと、その後段に接続した排水処理プロセスＡで同様にして処理するものである。
この実施例では、晴天時の少水量で高濃度ＳＳを含む排水を処理する際に、まず排水処理プロセスＢで凝集沈殿処理して、粗ＳＳを除去してから後段の排水処理プロセスＡに導入し、凝集濾過して除去するようにしており、排水処理プロセスＡでの負荷を軽減することができる。
また、排水処理プロセスＢによる凝集沈殿処理を先行させるため、晴天時にも反応凝集槽１０での凝集剤の使用量を少なくすることができ、凝集剤７の使用量を大幅に節減することができる。
【００４０】
【実験例】
実施例１（図１、図２）のような設備配置例を用いて、鉄鉱石ヤードの晴天時の散水による排水と雨天時の降雨による排水のＳＳ除去処理を行った。実験条件と実験結果の評価について以下に説明する。
【００４１】
［実験条件］
鉄鉱石ヤード
ヤード面積：３００，０００ｍ³
排水のＳＳ濃度
晴天時の散水排水：５００ｍｇ／リットル
雨天時の降雨排水：２００ｍｇ／リットル
排水処理量
晴天時の散水排水：３ｍ³
雨天時の降雨排水：２０ｍ³
凝集剤：ＰＡＣ、高分子凝集剤
濾過機
処理能力：３ｍ³／分
沈殿池（水平横流式）
容量：１，０００ｍ³
［評価］
従来との比較
凝集剤の使用量：従来の５０％以下に節減
ＳＳ濃度：１０ｍｇ／リットル、従来は２０ｍｇ／リットル
【００４２】
以上のように、本発明のヤード排水のＳＳ除去処理方法においては、前記図５に示したような、従来の凝集沈殿方式のヤード排水のＳＳ除去処理方法に比較して、凝集剤の使用量を大幅に節減することができ、処理コストを大幅に節減することができる。また、凝集濾過プロセスを用ることにより設備コストを増加させないで、処理能力を向上することもできる。
なお、実施例２、実施例３の設備配置例による場合には、さらに、これらの効果を確かなものにすることができる。
【００４３】
【発明の効果】
本発明では、濾過もしくは凝集濾過による少水量高濃度ＳＳ排水処理プロセスと、凝集沈殿による多水量低濃度ＳＳ排水処理プロセスを併用し、切り替えまたは直列配置して処理するものであり、凝集剤のコスト負担を大幅に節減するとともに、全体の設備コスト負担も軽減でき、排水処理コスト負担を大幅に軽減することができる。
【図面の簡単な説明】
【図１】本発明のヤード排水処理方法を実施する、晴天時の排水処理プロセスと雨天時の排水処理プロセスを切り替え可能な排水処理設備例を示す側断面説明図で晴天時の排水処理状態を示す。
【図２】本発明のヤード排水処理方法を実施する、晴天時の排水処理プロセスと雨天時の排水処理プロセスを切り替え可能な排水処理設備例を示す側断面説明図で雨天時の排水処理状態を示す。
【図３】本発明のヤード排水処理方法を実施する晴天時の排水処理プロセスと雨天時の排水処理プロセスを切り替え可能な他の排水処理設備例を示す側断面説明図。
【図４】本発明のヤード排水処理方法を実施する晴天時の排水処理プロセスと雨天時の排水処理プロセスを直列配置する排水処理設備例を示す側断面説明図。
【図５】本発明のヤード排水処理方法を実施する晴天時の排水処理プロセスと雨天時の排水処理プロセスを直列配置する多の排水処理設備例を示す側断面説明図。
【図６】従来のヤード排水処理方法を実施する排水処理設備例を示す側断面説明図。
【符号の説明】
１鉄鉱石（粉粒体）
２ヤード
３ＳＳ排水
４Ｕ字溝
５原水溝
６調整槽
７凝集剤
８処理剤
９、９ａ、９ｂ撹拌器
１０反応凝集槽
１０ａ反応槽
１０ｂ凝集槽
１１、１１ａ、１１ｂ沈殿池
１２水槽
１３濾過機
１４ａ、１４ｂ逆洗装置
１５連絡管
１６水位計
１７オーバーフロー管
Ｐａ、Ｐｂ、Ｐ₁ ポンプ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for treating wastewater containing SS generated by watering, rainwater, etc., in an outdoor yard storing powder particles (including a lump, hereinafter referred to as “powder particles”).
[0002]
[Prior art]
For example, wastewater in the steel industry can be broadly divided into (1) cooling effluent generated at the time of factory production activities, cooling effluent generated during washing, washing effluent and other factory effluent, and (2) rainwater effluent generated due to rainfall. .
[0003]
Conventionally, pollution prevention measures have been taken mainly for the factory wastewater of (1), but recently, measures against rainy weather have also been taken due to the growing awareness of pollution. Depending on the local conditions, the degree of pollution and the pollution target (substance) that causes pollution problems due to rainfall,
1. Raw material, auxiliary raw material, coal yard ... SS (floating material), chromaticity, PH
2. Scrap Yard ... SS, chromaticity, oil Ballast Yard SS, PH
and so on.
[0004]
Conventionally, among these wastewater treatment processes in the outdoor yard, as a wastewater treatment process for removing SS, as shown in FIG. 6, for example, a yard drainage 3 containing a large amount of SS from the storage yard 2 of iron ore 1 is used. Collected in the pump pit 5 through the groove 4 and collected in the adjustment tank 6 from the pump pit 5 by the pump Pa and adjusted in the amount of water, and then passed through the agglomeration reaction tank 10 with the stirrer 9 to which the flocculant 7 and the processing agent 8 were added. The wastewater treatment process is known in which the SS agglomerated in the agglomeration reaction tank 10 is precipitated and removed, and the detoxified supernatant water 3c is discharged via the water tank 12 to the river or the sea via the water tank 12. ing. In this conventional wastewater treatment process, it is used in both fine weather and rainy weather, and the large-scale agglomeration reaction tank 10 and sedimentation basin 11 are arranged so that the capacity assuming the maximum rainfall can be treated. The equipment cost burden is large.
[0005]
In recent years, from the viewpoint of preventing dust from scattering from the yard 2, the amount of water sprayed in fine weather has increased, and although the amount of water is small, the wastewater 3 containing SS does not cease, and wastewater treatment is performed every day.
In this wastewater treatment, the flocculant 7 is added to the large-capacity agglomeration reaction tank 10 corresponding to the amount of wastewater in the rain to aggregate the SS in the wastewater 4, and a large SS floc is generated and precipitated in the sedimentation tank 11. The supernatant water 3c is discharged, and if the amount of the flocculant 7 added in the flocculation reaction tank 10 is small, the SS floc becomes fine, and even if the flow rate from the sedimentation tank 11 is reduced, the SS floc flows out. Therefore, the amount of the flocculant 7 added is often determined based on a clear day when the SS concentration changes drastically.
[0006]
However, the SS concentration varies greatly even in fine weather. In particular, since SS accumulated in the groove is expelled at once, the SS concentration is high at the beginning of drainage and tends to be gradually stabilized. Moreover, when it rains, the amount of drainage may increase 2 to 10 times that when it is fine, and the SS concentration in the drainage 3 decreases as the amount of rainfall increases.
[0007]
As described above, the amount of the flocculant 7 is conventionally set based on a clear day when the SS concentration is high, even though the SS concentration in the wastewater is greatly changed, and the consumption of the relatively expensive flocculant 7 is consumed. There is also a problem that the amount is large and the wastewater treatment cost burden is large.
[0008]
[Problems to be solved by the invention]
The present invention relates to a wastewater treatment method for removing SS in wastewater from a yard. The wastewater treatment method can significantly reduce the cost burden of the flocculant and greatly reduce the wastewater treatment cost burden while reducing the equipment cost burden. Is to provide.
[0009]
[Means for Solving the Problems]
The present invention includes the following inventions (1) to (7).
(1). A method for treating yard wastewater containing SS, switching between a low-water high-concentration SS wastewater treatment process by filtration or coagulation filtration and a high-water-low concentration SS wastewater treatment process during rainy weather due to coagulation sedimentation. Yard wastewater containing high-concentration SS with a small amount of water is treated by the small-water-high concentration SS wastewater treatment process, and yard wastewater containing a large amount of water and low-concentration SS when the standard rainfall is exceeded. A process for removing SS from yard wastewater, characterized by being treated by an SS wastewater treatment process.
(2). This is a method for treating yard wastewater containing SS, which uses both a low-water high-concentration SS wastewater treatment process by filtration or coagulation filtration and a large-water SS wastewater treatment process by coagulation sedimentation. Is treated with a low-water-high-concentration SS wastewater treatment process, and in rainy weather, high-volume, low-concentration SS wastewater is introduced into the high-water-low-concentration SS wastewater treatment process by overflowing (or bypassed), and low-water-high concentration SS wastewater is introduced. A method for SS removal treatment of yard wastewater, characterized in that treatment is carried out in combination with a treatment process and a large amount of low-concentration SS wastewater treatment process.
(3). In (1) or (2), the yard drainage SS removal method characterized by determining the timing of switching between the small water high concentration SS wastewater treatment process and the high water low concentration SS wastewater treatment process based on rainfall information .
(4). In (1) or (2), the timing of switching between the low-water-high concentration SS wastewater treatment process and the high-water-low concentration SS wastewater treatment process is determined based on the water level of the raw water tank or the adjustment tank before the wastewater treatment process. A method for removing SS from yard drainage.
(5). A method for treating yard wastewater containing SS, which uses both a low-water-high concentration SS wastewater treatment process by filtration or coagulation filtration and a high-water-low concentration SS wastewater treatment process by coagulation sedimentation, which is preceded by a high water content SS wastewater treatment process. Low-water high-concentration SS drainage process in fine weather is arranged in series, and low-water high-concentration SS wastewater and high-water low-concentration SS wastewater are first treated by the low-water high-concentration SS wastewater treatment process. Then, the SS removal treatment method for the yard wastewater, characterized in that the treatment is performed by a high water content low concentration SS wastewater treatment process.
(6). This is a method for treating yard wastewater containing SS, which uses both low-water and high-concentration SS wastewater treatment process by filtration or coagulation filtration and multi-water and low-concentration SS wastewater treatment process by coagulation sedimentation. A large amount of low concentration SS wastewater treatment process is arranged in series before the process, and wastewater containing small amount of water and high concentration SS and wastewater containing large amount of water and low concentration SS are first treated with high water amount and low concentration SS wastewater treatment process. A method for removing SS from yard wastewater, characterized in that the wastewater is treated with a low-water, high-concentration SS wastewater treatment process.
(7). In any one of (1) to (6), the backwash water of the filter of the low water amount high concentration SS waste water treatment process is introduced into the high water amount low concentration SS waste water treatment process and treated. SS removal processing method.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is an SS removal treatment method for waste water from an outdoor yard that mainly stores granular materials, and uses a low water amount high concentration SS waste water treatment process by coagulation filtration and a high water amount low concentration SS waste water treatment process by coagulation sedimentation. Basically, when the weather is fine with a small amount of water and high SS concentration (in this case, when there is no rainfall, it means that the amount of rainfall is small and the granular material is scattered in a dry state) (Hereinafter referred to as “when the weather is fine”), a low-water high-concentration SS wastewater treatment process is used for wastewater treatment, and a high-water-low-concentration SS wastewater treatment process is used for wastewater during rainy weather with a large amount of water and low SS concentration. It is what is used.
[0011]
In the present invention, a coagulation filtration process is used for the low-water-high-concentration SS wastewater treatment process. Therefore, when the SS concentration in fine weather is high, the SS concentration is commensurate with a relatively high-concentration wastewater of 500 mg / liter or more. Even if there is a shortage of flocculant, SS is easily adsorbed and captured by the SS flocs trapped between the filter media, and the removal of SS is performed reliably. Can be reduced.
[0012]
As the filter of the coagulation filtration process used in the present invention, various known filters using natural sand or floating filter medium can be used. However, in order to secure a stable filtration function, the filter medium is reversed with gas or liquid. What has the structure to wash is advantageous.
[0013]
In addition, drainage in rainy weather with a large amount of water and a low SS concentration is large and the SS concentration is relatively low at 300 mg / liter. Therefore, the amount of flocculant used may be less than that of a low water amount high concentration SS wastewater treatment process. The amount of flocculant used is set in distinction from the low-water-volume high-concentration SS wastewater treatment process and can be reduced by about 50%.
[0014]
As the flocculant used in the present invention, there are many organic polymer flocculants. In addition, inorganic flocculants such as polyaluminum chloride (PAC), cationic or anionic surfactants, and the like can be used. Natural sand is generally used as the filter medium, but is not limited thereto.
[0015]
Here, when a coagulation sedimentation process is applied instead of filtration or coagulation filtration process to waste water containing a small amount of water and high concentration SS, the SS flocs produced are fine and light with a small binding force. Therefore, since it easily flows out of the sedimentation basin and it is difficult to reliably remove SS, a large amount of flocculant is necessary to remove high concentration SS, and the processing cost burden is large. This is not preferable.
[0016]
Moreover, in the present invention, a coagulation sedimentation process is used for the high water content low concentration SS wastewater treatment process, so a sedimentation basin with a capacity corresponding to the target flow rate is necessary. Therefore, there is a merit that the equipment cost does not increase at a rate of, and an increase in size is easy.
Further, SS is coagulated and precipitated in a sedimentation basin, but since the SS concentration is low, as described above, SS can be easily coagulated and removed even if the amount of the coagulant used is less than the conventional amount.
As the sedimentation basin used for the coagulation sedimentation in the present invention, various known sedimentation basins such as a cross-flow sedimentation basin and a circular sedimentation basin can be used.
[0017]
In the present invention, basically, a low water high-concentration SS wastewater treatment process and a high water low-concentration SS wastewater treatment process are switched according to the amount of wastewater from the yard (water spraying in fine weather, rainfall in rainy weather). However, it is also considered that low-water high-concentration SS wastewater treatment process and high-water low-concentration SS wastewater treatment process are arranged in series and used together to share the treatment and back up each other. .
[0018]
Moreover, in the small water amount high concentration SS wastewater treatment process by the coagulation filtration, the filter is backwashed, but the backwash water including the SS after the backwash is a high water amount low concentration SS wastewater treatment process. It is effective to reduce the facility cost burden and the treatment cost burden by introducing it into the wastewater and treating it with a large amount of low-concentration SS wastewater.
[0019]
In the present invention, switching between a low-water high-concentration SS wastewater treatment process by coagulation filtration and a high-water-low concentration SS wastewater treatment process by coagulation sedimentation is performed when the amount of drainage from the yard (t / hr) satisfies the switching condition (watering) If it falls under the criteria of whether the level of drainage of water or the level of drainage that exceeds the standard rainfall, set the criteria in advance), or manually or automatically. ,
(1). Judge visually.
(2). Estimate the amount of water discharged from the yard by the amount of water sprayed in fine weather
(3). The amount of drainage from the yard is estimated based on the rainfall information (rain forecast for the area or actual rainfall amount for the area).
(4). The amount of water discharged from the yard is estimated by detecting the water level in the raw water tank and the adjustment tank in the previous stage of the waste water treatment process.
In (2) to (4), it is also possible to automatically switch between a low water amount high concentration SS waste water treatment process and a high water amount low concentration SS waste water treatment process by coagulation sedimentation by linking the waste water amount estimation system and the switching system.
[0020]
In the present invention, the yard drainage containing a large amount of SS is targeted for processing. For example, chromaticity, PH, oil, and COD (chemical oxygen demand) may also be treated. In this case, In the agglomeration reaction tank, there is an additional process including addition of a reaction treatment agent such as NaOH in addition to the aggregating agent. However, there is no problem in applying the present invention in this case.
[0021]
【Example】
Hereinafter, the present invention will be described together with an example of equipment arrangement.
Example 1
FIG. 1 shows an arrangement example of wastewater treatment equipment of an iron ore storage yard for carrying out the present invention. FIG. 1 shows a case where wastewater containing a high concentration SS is treated with a small amount of water in fine weather, and FIG. 2 shows a case where wastewater containing a low concentration SS is treated with a large amount of water in rainy weather. .
[0022]
1 and 2, 1 is iron ore stored in the yard 2, 3 is a yard drainage containing SS generated by sprinkling, collected in the raw water tank 5 through the U-shaped groove 4, and adjusted tank 6 by the pump Pa After that, the agglomeration reaction tank 10 including the reaction tank 10a for adding the flocculant 7 and the processing agent 8 and stirring the mixture with the stirrer 9a and the agitation tank 10b for supplying the water W and stirring with the stirrer 9b to grow the SS floc. To introduce. Wastewater containing SS flocs that has been reacted and agglomerated in the agglomeration reaction tank 10 and grown is introduced into the wastewater treatment process of the present invention for treatment.
[0023]
In this embodiment, the waste water treatment process after the reaction / coagulation treatment includes a filter 13 having a backwash structure using a filter medium and air for filtering the waste water containing the grown SS floc from the coagulation reaction tank 10, and This filter is backwashed with backwashing water to maintain the filtration function and communicates with the coagulation reaction tank 10 and the small water high concentration SS wastewater treatment process A comprising the backwashing devices 14a (supply side) and 14b (discharge side). Connected in parallel with a low water concentration SS wastewater treatment process B consisting of a sedimentation basin 11a, which is connected by a pipe 15a and precipitates the wastewater containing the grown SS floc from the agglomeration reaction tank 10 and precipitates and removes the SS floc. is doing.
[0024]
The low water high concentration SS wastewater treatment process A is basically for treating wastewater containing high concentration SS with a small amount of water in fine weather, and the high water content low concentration SS wastewater treatment process B is the amount of rainfall. Is to treat wastewater containing low concentration SS with a large amount of water when the standard rainfall exceeds the standard rainfall,
(1) Small water high-concentration SS wastewater treatment process A in clear weather alone (in clear weather)
(2) Heavy water and low concentration SS wastewater treatment process B in rainy weather (rainy weather)
(3) Combined use of low-water high-concentration SS wastewater treatment process A during fine weather and high-water low-concentration SS wastewater treatment process B during rainy weather (weather)
The three types of wastewater treatment processes can be switched manually or automatically.
[0025]
The waste water treatment (1) to (3) will be described below.
[Wastewater treatment by small-water high-concentration SS wastewater treatment process A in fine weather according to (1)]
As shown in FIG. 1, the yard drainage 3 containing SS generated by watering is collected in the raw water tank 5 through the U-shaped groove 4, introduced into the adjustment tank 6 by the pump Pa, and the flocculant 7 and the treatment agent by the pump Pb. 8 is added to the reaction tank 10a which is stirred by the stirrer 9a and the water supply W is stirred and processed by the stirrer 9b to be introduced into the agglomeration reaction tank 10 which is a coagulation tank 10b which grows SS floc.
Here, since the wastewater to be treated is wastewater having a high SS concentration, the amount of the flocculant 7 added is increased in order to ensure the growth of SS floc.
The waste water 3 containing SS floc produced by the reaction coagulation treatment is opened by switching the valve Va, and is introduced into the filter 13 of the low-water quantity high-concentration SS waste water treatment process A in fine weather by the pump P1, and filtered and filtered. The drainage 3 is discharged through the water tank 12.
[0026]
In the filter 13, the amount of suspended matter is restrained at every filtration, and when the amount of suspended matter increases to a certain level, the filtration resistance increases, the filtration function decreases, the amount of suspended matter leaks, and the filtered water quality Therefore, the filter 13 is backwashed with backwashing water and air from the backwashing device 14a at an appropriate time to prevent a reduction in filtration function.
Here, the backwash water containing the washed suspension is introduced into the sedimentation basin 11a and subjected to sedimentation treatment, but may be discharged out of the sedimentation basin 11a.
[0027]
The wastewater treatment process of (1) uses filtration flocculation which has a good flocculation efficiency and requires a small amount of flocculating agent, and the amount of flocculating agent 7 used is significantly larger than that of precipitation flocculation alone. It can be saved, and is suitable for the treatment of low-volume, high-concentration SS drainage in fine weather.
[0028]
[Drainage treatment by high-volume, low-concentration SS wastewater treatment process B during rainy weather by (2)]
As shown in FIG. 2, the yard drainage 3 containing SS generated by rainfall is collected in the raw water tank 5 through the U-shaped groove 4, introduced into the adjustment tank 6 by the pump Pa, and the flocculant 7 and the treatment agent by the pump Pb. 8 is added to the agglomeration reaction tank 10 comprising a reaction tank 10a for agitation treatment with the agitator 9a and water supply W and agitation tank 10b for agitation treatment with the agitator 9b to grow SS floc.
Here, since the wastewater to be treated is a wastewater having a low SS concentration, the amount of the flocculant 7 added for the growth of SS flocs is changed to be small.
[0029]
When it rains, the water level of the raw water tank 5, the adjustment tank 6, and the reaction flocculation tank 10 becomes high due to rain. For example, when the water level is detected by the water level meter 16a of the raw water tank 5, the water level becomes a certain level or higher. In this case, the switching valve Va is closed to close the small water high concentration SS wastewater treatment process A in clear weather, the switching valve Vb is opened to open the high water low concentration SS wastewater treatment process B, and reaction agglomeration is performed. SS drainage containing the grown SS floc from the tank 10 is introduced into the settling basin 11a via the connecting pipe 15.
[0030]
When the rainfall stops and the amount of drainage decreases and reaches the level of drainage during fine weather, the changeover valve Va is opened to open the small water high concentration SS wastewater treatment process A during fine weather.
The amount of the flocculant 7 added to the reaction flocculation tank 10 does not need to be increased immediately, but may be increased after it becomes clear and the iron ore becomes dry and requires watering. .
[0031]
In the wastewater treatment process of (2), coagulation sedimentation treatment using the sedimentation basin 11a is performed. The treatment of yard wastewater during rainy weather with a low SS concentration is different from the treatment of yard wastewater during sunny weather with a high SS concentration. Since it is performed separately, the amount of flocculant used can be reduced even if the amount of flocculant used is reduced, and the treatment of yard drainage during clear weather with high SS concentration and yard drainage during rainy weather with low SS concentration. The amount of the flocculant used can be reduced as compared with the conventional case performed in the same manner.
[0032]
[Wastewater treatment using low-water high-concentration SS wastewater treatment process A in clear weather and high-water-low concentration SS wastewater treatment process B in rainy weather by (3)]
As shown in FIG. 1, this wastewater treatment is performed when rain occurs during treatment of the yard wastewater 3 containing SS generated by sprinkling in a low-water high-concentration SS wastewater treatment process A in fine weather. With the switching valve Va of the process A open, as shown in FIG. 2, the switching valve Vb of the high water content low concentration SS wastewater treatment process B in the rainy weather is opened and the wastewater treatment process B is opened. In this state, waste water treatment process A and waste water treatment process B are used in combination.
[0033]
In this example, when switching from the wastewater treatment process A to the wastewater treatment process B, the switching valve Vb is provided and the opening operation is performed. However, the switching valve Vb is not indispensable, and as shown in FIG. When it rises, the SS drainage containing the SS flocs grown in the reaction coagulation tank 10 may be overflowed via the overflow pipe 17 and introduced into the sedimentation tank 11a.
[0034]
Here, when there is rainfall and the yard drainage increases and the water level in the reaction coagulation tank 10 of the wastewater containing SS floc treated and grown in the reaction coagulation tank 10 rises, this drainage naturally overflows from the overflow pipe 17. Thus, this overflow is introduced into a high water content low concentration SS wastewater treatment process B during rainy weather, and is subjected to a coagulation sedimentation treatment in the sedimentation basin 11a. Since the yard drainage 3 due to the rain immediately becomes a drainage with a low SS concentration, the addition amount of the flocculant 7 for the growth of SS flocs is changed to be small.
[0035]
In the wastewater treatment process (3), coagulation filtration with good coagulation efficiency and a small amount of coagulant is used in combination with coagulation precipitation, and the coagulant is used only when coagulation precipitation is used. Compared with this, it can save a lot.
[0036]
(Example 2)
FIG. 4 shows an arrangement example of the waste water treatment facility of the second embodiment.
In Example 2, a small water high concentration SS wastewater treatment process A (hereinafter referred to as “wastewater treatment process A”) in fine weather is connected to the agglomeration reaction tank 10, and a high water content low concentration SS wastewater in rainy weather is connected to the subsequent stage. The waste water containing SS floc that has grown from the agglomeration reaction tank 10 is first treated by waste water treatment process A by connecting treatment processes B (hereinafter referred to as “waste water treatment process B”) in series, and then the waste water treatment process. The precipitate is treated with B.
[0037]
In the second embodiment, wastewater treatment process A and wastewater treatment process at the time of rainy weather connected to the subsequent stage are both wastewater containing a high concentration SS with a small amount of water during fine weather and wastewater containing a high concentration SS and a low concentration SS during rainy weather. The same processing is performed at B.
In this Example 2, when treating the wastewater containing high concentration SS with a small amount of water in fine weather, when the backwash interval of the coagulation filtration process of the wastewater treatment process A becomes longer, the SS capture limit is exceeded. When the SS floc flows out from the filter 13, it can be reliably removed by the precipitation treatment in the subsequent waste water treatment process B.
[0038]
(Example 3)
FIG. 5 shows an arrangement example of the waste water treatment facility of the third embodiment.
In this Example 3, a sedimentation basin 11b of a wastewater treatment process B during rainy weather is connected to the agglomeration reaction tank 10, a wastewater treatment process A is connected in series to the subsequent stage, and a wastewater treatment process B during rainy weather to the subsequent stage. The sedimentation basin 11a is connected in series, and the wastewater containing the grown SS flocs from the agglomeration reaction tank 10 is first subjected to the coagulation sedimentation treatment in the sedimentation basin 11b of the wastewater treatment process B, and then treated in the wastewater treatment process A. Then, precipitation is performed in the settling tank 11a.
[0039]
In Example 3, waste water containing a high concentration SS with a small amount of water during fine weather and waste water containing a high concentration SS and a low concentration SS during rainy weather are the same in the waste water treatment process B and the waste water treatment process A connected to the subsequent stage. To process.
In this embodiment, when treating wastewater containing high-concentration SS with a small amount of water in fine weather, first, coagulation sedimentation treatment is performed in wastewater treatment process B, and after removing coarse SS, it is introduced into the subsequent wastewater treatment process A. Then, it is removed by coagulation filtration, and the load on the wastewater treatment process A can be reduced.
Moreover, since the coagulation sedimentation process by the waste water treatment process B is preceded, the use amount of the coagulant in the reaction coagulation tank 10 can be reduced even in fine weather, and the use amount of the coagulant 7 can be greatly reduced. .
[0040]
[Experimental example]
Using an example of equipment arrangement as in Example 1 (FIGS. 1 and 2), SS removal processing was performed for drainage due to sprinkling when the iron ore yard is fine and for drainage due to rain during rainy weather. The evaluation of experimental conditions and experimental results will be described below.
[0041]
[Experimental conditions]
Iron ore yard yard area: 300,000m ³
SS concentration of drainage Sprinkling drainage in fine weather: 500 mg / liter Rainfall drainage in rainy weather: 200 mg / liter Wastewater treatment amount Sprinkling drainage in fine weather: 3 m ³
Rain drainage in rainy weather: 20m ³
Flocculant: PAC, polymer flocculant filter processing capacity: 3 m ³ / min sedimentation basin (horizontal cross-flow type)
Capacity: 1,000m ³
[Evaluation]
Comparison with conventional use amount of flocculant: 50% or less of conventional SS concentration: 10 mg / liter, conventional 20 mg / liter
As described above, in the yard drainage SS removal processing method of the present invention, the amount of the flocculant used as compared with the conventional flocculation sedimentation type yard drainage SS removal treatment method as shown in FIG. Can be saved significantly, and the processing cost can be greatly reduced. Further, by using the coagulation filtration process, the processing capacity can be improved without increasing the equipment cost.
In addition, in the case of the equipment arrangement examples of the second and third embodiments, these effects can be further ensured.
[0043]
【The invention's effect】
In the present invention, the low water high concentration SS wastewater treatment process by filtration or coagulation filtration and the high water low concentration SS wastewater treatment process by coagulation sedimentation are used in combination, and are processed by switching or arranging them in series. In addition to greatly reducing the burden, the overall equipment cost burden can be reduced, and the wastewater treatment cost burden can be significantly reduced.
[Brief description of the drawings]
FIG. 1 is a side sectional explanatory view showing an example of a wastewater treatment facility capable of switching between a wastewater treatment process in fine weather and a wastewater treatment process in rainy weather, which carries out the yard wastewater treatment method of the present invention. Show.
FIG. 2 is an explanatory side sectional view showing an example of a wastewater treatment facility capable of switching between a wastewater treatment process in fine weather and a wastewater treatment process in rainy weather, which implements the yard wastewater treatment method of the present invention. Show.
FIG. 3 is an explanatory side sectional view showing another example of wastewater treatment equipment capable of switching between a wastewater treatment process in fine weather and a wastewater treatment process in rainy weather that implements the yard wastewater treatment method of the present invention.
FIG. 4 is an explanatory side sectional view showing an example of wastewater treatment equipment in which a wastewater treatment process in fine weather and a wastewater treatment process in rainy weather that implement the yard wastewater treatment method of the present invention are arranged in series.
FIG. 5 is an explanatory side cross-sectional view showing an example of multiple wastewater treatment facilities in which a wastewater treatment process in fine weather and a wastewater treatment process in rainy weather that implement the yard wastewater treatment method of the present invention are arranged in series.
FIG. 6 is an explanatory side sectional view showing an example of waste water treatment equipment for carrying out a conventional yard waste water treatment method.
[Explanation of symbols]
1 Iron ore (powder)
2 yards 3 SS drainage 4 U-shaped groove 5 Raw water groove 6 Adjustment tank 7 Coagulant 8 Treatment agent 9, 9a, 9b Stirrer 10 Reaction coagulation tank 10a Reaction tank 10b Coagulation tank 11, 11a, 11b Settling tank 12 Water tank 13 Filter 14a, 14b Backwash device 15 Connecting pipe 16 Water level gauge 17 Overflow pipe Pa, Pb, P ₁ pump

Claims

A method for treating yard wastewater containing SS, switching between a low-water high-concentration SS wastewater treatment process by filtration or coagulation filtration and a high-water-low concentration SS wastewater treatment process during rainy weather due to coagulation sedimentation. Yard wastewater containing high-concentration SS with a small amount of water is treated by the small-water-high concentration SS wastewater treatment process, and yard wastewater containing a large amount of water and low-concentration SS when the standard rainfall is exceeded. A method for removing SS from a yard wastewater, characterized in that the treatment is performed by an SS wastewater treatment process.

This is a method for treating yard wastewater containing SS, which uses both a low-water high-concentration SS wastewater treatment process by filtration or coagulation filtration and a large-water SS wastewater treatment process by coagulation sedimentation. Is treated by a low water high concentration SS wastewater treatment process, and in the rainy weather, a large amount of low concentration SS wastewater is introduced into the high water low concentration SS wastewater treatment process by overflowing (or bypassed), and a low water high concentration SS wastewater is introduced. A method for SS removal treatment of yard wastewater, characterized in that treatment is carried out in combination with a treatment process and a large amount of low-concentration SS wastewater treatment process.

The yard drainage SS removal process according to claim 1 or 2, wherein the timing of switching between the low-water-high-concentration SS wastewater treatment process and the high-water-low concentration SS wastewater treatment process is determined by rainfall information. Method.

2. The timing of switching between a low-water-high concentration SS wastewater treatment process and a high-water-low-concentration SS wastewater treatment process is determined based on the water level of the raw water tank or the adjustment tank before the wastewater treatment process. Or the SS removal processing method of the yard drainage of Claim 2.

A method for treating yard wastewater containing SS, which uses both a low-water-high concentration SS wastewater treatment process by filtration or coagulation filtration and a high-water-low concentration SS wastewater treatment process by coagulation sedimentation, which is preceded by a high water content SS wastewater treatment process. Low-water high-concentration SS drainage process in fine weather is arranged in series, and low-water high-concentration SS wastewater and high-water low-concentration SS wastewater are first treated by the low-water high-concentration SS wastewater treatment process. Then, the SS removal treatment method for the yard wastewater, characterized in that the treatment is performed by a high water content low concentration SS wastewater treatment process.

This is a method for treating yard wastewater containing SS, which uses both low-water and high-concentration SS wastewater treatment process by filtration or coagulation filtration and multi-water and low-concentration SS wastewater treatment process by coagulation sedimentation. A large amount of low concentration SS wastewater treatment process is arranged in series before the process, and wastewater containing small amount of water and high concentration SS and wastewater containing large amount of water and low concentration SS are first treated with high water amount and low concentration SS wastewater treatment process. A method for removing SS from yard wastewater, characterized in that the wastewater is treated with a low-water, high-concentration SS wastewater treatment process.

The yard according to any one of claims 1 to 6, wherein the backwash water of the filter of the low water amount high concentration SS waste water treatment process is introduced into the high water amount low concentration SS waste water treatment process for treatment. SS removal treatment method for wastewater.