JP2004209424A - Sludge treatment agent and sludge treatment method using the same - Google Patents
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Abstract
Description
【０００１】
【発明の属する技術分野】
本発明は、各種の下水やヘドロなどの汚泥処理技術に関する。
【０００２】
【従来の技術】
下水汚泥や湖沼、海域のヘドロなどの汚泥処理は、被処理水に汚泥処理剤を加え、汚泥を凝集させ、減容化した後、適宜、生物的処理、化学的処理を行って無害化し、乾燥または焼却して行なわれている。汚泥処理剤としては、塩化アルミニウム、硫酸バン土（硫酸アルミニウム）、ポリ塩化アルミニウム（ＰＡＣ）などのアルミニウム系処理剤、塩化鉄、硫酸鉄、水酸化鉄などの鉄系処理剤、あるいは水溶性高分子化合物などが使用されている。
しかし、アルミニウム系処理剤は、脱臭効果が低く、処理汚泥から悪臭が生じ、最終処分方法が制限される。鉄系処理剤は、悪臭の要因となる硫化水素を固定化する作用を有するが、塩化鉄、硫酸鉄などの水溶性のものは、酸性を有するので生物への影響が懸念され、処理水を環境へ排出するにあたっては中和の処理が必要である。また、溶出した鉄イオンによる被処理水の着色が問題となる。水酸化鉄は、一般に水溶性の鉄塩を汚泥を含む水に加え、中和して水酸化鉄を生成させながら汚泥を凝集させる方法において間接的に用いられる。この方法では多量の中和剤を必要とする。水酸化鉄を直接添加する方法は、凝集効果が不十分である。水溶性高分子化合物は、前記の無機系汚泥処理剤より凝集効果は優れているが、非常に高価である。
【０００３】
【発明が解決しようとする課題】
本発明は、脱臭及び凝集効果に優れ、しかも経済的な汚泥処理剤およびそれを用いた汚泥の処理方法を提供することを課題とする。
【０００４】
【課題を解決するための手段】
本発明者らは鋭意研究を重ねた結果、水酸化鉄と硫酸カルシウムとを含む汚泥処理剤により、前記の課題を解決できることを見出し、本発明を完成した。
【０００５】
すなわち、請求項１に係わる本発明は、水酸化鉄と硫酸カルシウムとを含むことを特徴とする汚泥処理剤である。
【０００６】
請求項２に係わる本発明は、水酸化鉄をＦｅ２Ｏ３として１０〜６０重量％の範囲で、硫酸カルシウムをＣａＳＯ４として２０〜５０重量％の範囲で含むことを特徴とする請求項１記載の汚泥処理剤である。
【０００７】
請求項３に係わる本発明は、更にケイ素の化合物、アルミニウムの化合物から選ばれる少なくとも１種を含むことを特徴とする請求項１記載の汚泥処理剤である。
【０００８】
請求項４に係わる本発明は、更に水を含むことを特徴とする請求項１記載の汚泥処理剤である。
【０００９】
請求項５に係わる本発明は、固形分が３０〜６０重量％の範囲にあることを特徴とする請求項４記載の汚泥処理剤である。
【００１０】
請求項６に係わる本発明は、鉄成分を含む廃酸をカルシウム成分を含むアルカリで中和した中和生成物であることを特徴とする請求項１記載の汚泥処理剤である。
【００１１】
請求項７に係わる本発明は、廃酸が酸化チタンの製造工程から副生されることを特徴とする請求項６記載の汚泥処理剤である。
【００１２】
請求項８に係わる本発明は、水酸化鉄と硫酸カルシウムとを含む汚泥処理剤を汚泥を含む水または汚泥に混合し汚泥を凝集させることを特徴とする汚泥処理方法である。
【００１３】
請求項９に係わる本発明は、汚泥を含む水が下水の汚泥濃縮水であることを特徴とする請求項８記載の汚泥処理方法である。
【００１４】
請求項１０に係わる本発明は、汚泥が浚渫汚泥であることを特徴とする請求項８記載の汚泥処理方法である。
【００１５】
【発明実施の形態】
本発明の汚泥処理剤は、水酸化鉄と硫酸カルシウムとを含む。これら二成分の相乗効果により、それぞれの成分単独では得られない優れた汚泥の凝集・減容化作用を有し、その後の脱水、無害化、乾燥、焼却等の処理工程が容易である。さらに、水酸化鉄が悪臭の主要因である硫化水素を吸着・固定化するので、汚泥を脱臭することができる。このため、生活排水、産業排水などの下水や、湖沼、海域のヘドロなど広範囲の汚泥処理に適用される。また、処理汚泥には硫酸カルシウムが含まれるので、回収して、例えば、コンポスト、セメント原料、土壌改良剤などの石膏含有資材として、有効利用することもできる。
【００１６】
処理剤に用いる硫酸カルシウムとしては、硫酸カルシウム二水塩（二水石膏）、硫酸カルシウム半水塩（半水石膏）、無水硫酸カルシウム（無水石膏）、及びそれらの混合物を用いることができる。
水酸化鉄には、鉄の水酸化物、鉄の含水酸化物が含まれ、鉄の酸化数は適宜選択できる。例えば、水酸化第二鉄を用いると、汚泥中で三価鉄が還元され、酸素供給剤として作用するので、汚泥を好気処理する場合に好ましい。また、処理汚泥を湖沼、海域に埋め戻す際に残存する三価鉄の作用により底部の貧酸素防止にもなる。
水酸化鉄の好ましい含有量は、Ｆｅ２Ｏ３として１０〜６０重量％の範囲であり、硫酸カルシウムの好ましい含有量は、ＣａＳＯ４として２０〜５０重量％の範囲であり、より好ましい範囲はそれぞれ１５〜５０重量％、２０〜４０重量％である。
処理剤には水酸化鉄、硫酸カルシウム以外に、本発明の効果を阻害しない範囲で、他の成分、例えば、処理剤の製造に係わる副生物などが含まれていても良い。また、ケイ素の化合物やアルミニウムの化合物には、水中の有機化合物、可溶性塩類（ＳＳ）、窒素を除去する作用や、化学的酸素要求量（ＣＯＤ）を低減させる作用が知られているので、これらから選ばれる少なくとも１種が含まれていても良い。
【００１７】
処理剤の形態としては、種々の形態を取ることができ、処理方法に応じて適宜選択することができる。例えば、粉末状、顆粒状、成形体などにすると、下水などの汚泥を含む水への投入が容易となる。一方、本発明の処理剤に水を含ませ、湿潤状態で用いると、浚渫した湖沼や海域のヘドロとの混合が容易になり、好ましい。このような湿潤状態の処理剤は、固形分が３０〜６０重量％の範囲にあるのが好ましく、４０〜６０重量％の範囲にあるのが更に好ましい。固形分が６０重量％を超えると所望の効果が得られず、３０重量％より少ないと流動状態になり作業性が著しく低下するばかりでなく、有効成分の含有量が少なく経済的でない。
【００１８】
本発明の処理剤としては、水酸化鉄と硫酸カルシウムとを混合したものの他、鉄成分を含む各種廃酸の中和工程で副生される水酸化鉄を含む石膏なども用いることができ、本発明の処理剤を低コストで提供できる。後者としては、例えば、硫酸法酸化チタンの製造工程で発生する鉄成分を含む廃硫酸や、鉄の酸洗浄廃液を、石灰等のカルシウム成分を含むアルカリで中和した中和生成物（スラッジ）などが挙げられる。このような廃酸から本発明の処理剤を調製する具体的な方法を、以下に記載する。
【００１９】
第一の方法は、鉄成分を含む硫酸、例えば、硫酸法酸化チタンの製造工程で発生する廃硫酸に、カルシウム成分を含むアルカリを加えてｐＨが７〜９の範囲で中和する。廃硫酸中の硫酸塩はカルシウム成分と反応して硫酸カルシウムとして沈殿し、同時に鉄成分も水酸化鉄として沈殿する。中和する際に、液中に空気を吹き込むか、酸化剤を加えるなどして酸化し、酸化数を調整することもでき、例えば、前記の水酸化第二鉄を含む処理剤は、このように中和しながら酸化することで得られる。これらを固液分離すると、本発明の処理剤が得られる。
【００２０】
第二の方法は、先ず第１の工程として、鉄成分を含む硫酸、例えば、硫酸法酸化チタンの製造工程で発生する廃硫酸に、カルシウム成分を含むアルカリを加えて、ｐＨが４〜６の範囲で中和する。廃硫酸中の硫酸塩の一部が優先的にカルシウム成分と反応し、鉄成分をほとんど含まない硫酸カルシウムとして沈殿するので、これを濃縮または濾過等の固液分離により除去する。引き続き、第２の工程で固液分離後の上澄液または濾液に、更にカルシウム成分を含むアルカリを加え、第一の方法と同様にしてｐＨが７〜９の範囲で中和するか、または、中和しながら酸化する。上澄液または濾液中の未反応の硫酸塩と鉄成分が、それぞれアルカリ成分と反応して、水酸化鉄及び硫酸カルシウムとして沈殿するので、これらを固液分離する。第二の方法では、水酸化鉄の濃度の高い処理剤が得られ、副生する鉄成分を含まない硫酸カルシウムは、石膏資材として石膏ボード等に利用できる。
【００２１】
第三の方法は、第二の方法で本発明の処理剤を固液分離した後の上澄液または濾液に、硫酸法酸化チタンの蒸解工程で発生する未反応の鉱石などを含む廃硫酸、塩素法酸化チタンの塩素化工程で発生する四塩化チタンなどの塩化物を含む塩酸性廃酸などを混合し、これにカルシウム成分を含むアルカリを加え、第一の方法と同様にしてｐＨが７〜９の範囲で中和するか、または、中和しながら酸化する。混合廃酸中の硫酸塩成分と鉄成分が、それぞれアルカリ成分と反応して、水酸化鉄及び硫酸カルシウムとして沈殿するので、これらを固液分離することで本発明の処理剤が得られる。
【００２２】
用いるカルシウム成分を含むアルカリとしては、例えば、第一の方法、第二の方法の第２の工程、第三の方法では、水酸化カルシウムのような強アルカリを、第二の方法の第１の工程では炭酸カルシウムのような弱アルカリを用いると、ｐＨ調整を行わなくても良いので好ましい。得られた処理剤は、必要に応じて乾燥し、粉末状、顆粒状、成形体などに適宜成形することができる。あるいは、乾燥せず、固形分が前記の３０〜６０重量％の範囲になるまで脱水すると、湿潤状態の処理剤を得ることができる。
【００２３】
以上の方法で得られた処理剤には、水酸化鉄及び硫酸カルシウムが前記の範囲で、すなわち、Ｆｅ２Ｏ３として１０〜６０重量％、ＣａＳＯ４として２０〜５０重量％の範囲で含まれている。その他の成分を若干含んでいても良く、酸化チタン製造工程の廃硫酸を用いた場合では、チタンの化合物がＴｉＯ２として１〜３０重量％、ケイ素の化合物がＳｉＯ２として０．５〜１０重量％、アルミニウムの化合物がＡｌ２Ｏ３として１〜５重量％の範囲で含まれている。
【００２４】
本発明の汚泥処理方法は、まず、水酸化鉄と硫酸カルシウムとを含む汚泥処理剤を、下水などの汚泥を含む水に混合するか、または、汚泥に直接混合し、汚泥を凝集させる。汚泥処理を行う前に、通常、汚泥を含む水は濃縮され、このような汚泥濃縮水の汚泥含有量は２０００〜３００００ｍｇ／リットルの範囲である。この範囲の濃度の汚泥濃縮水には、汚泥濃縮水に対し、０．１〜１０重量％、好ましくは１．０〜５重量％の範囲で、前記汚泥処理剤を加えるのが好ましい。また、湖沼、海域などのヘドロを浚渫した浚渫汚泥は、通常、含水率が５０〜９０重量％の範囲にあり、この範囲の含水率の浚渫汚泥には、浚渫汚泥に対し、１０〜１００重量％の範囲で前記泥処理剤を加えるのが好ましい。前記汚泥処理剤が水を含んで湿潤状態にあれば、汚泥との混合が容易になり、更に好ましい。この処理により、汚泥が凝集し、ろ過、脱水が容易となるばかりでなく、処理物が減容化されるので、その後の無害化、乾燥、焼却などの工程における作業性が改善される。汚泥を除去した処理水は、河川、湖沼、海域などの環境中へ放出する。あるいは、必要に応じて、下水処理場等において無毒化などの高度処理を行った後、処理水として循環使用されるか、または環境中へ放出される。固液分離した処理汚泥には硫酸カルシウムが含まれるので、石膏含有資材として、コンポスト、セメント原料、土壌改良剤などに再利用できる。浚渫汚泥の処理汚泥は、乾干潟造成材料として用いるか、あるいは圧密処理、焼却などの固化処理後、再度湖沼または海域に埋め戻すこともできる。
【００２５】
【実施例】
以下に実施例を挙げて本発明を説明するが、これらは本発明を限定するものではない。
【００２６】
実施例１、２
実施例１として、前記の第２の方法を適用して本発明の汚泥処理剤（試料Ａ）を得た。また、実施例２として、前記の第３の方法を適用して本発明の汚泥処理剤（試料Ｂ）を得た。それぞれの化学的組成を、表１に記載する。
【００２７】
【表１】
実施例３、４、比較例１
下水処理場で発生した汚泥濃縮水（平均濃度（ＭＬＳＳ）１２５００ｍｇ／リットル）に、実施例１、２で得られた汚泥処理剤（試料Ａ、Ｂ）を溶解した。それぞれを、実施例３、４とする。また、汚泥処理剤を用いなかったものを、比較例１とする。
【００２９】
評価１
実施例３、４において、汚泥処理剤（試料Ａ、Ｂ）を汚泥濃縮水に対し０．１重量％になるように添加し、攪拌した。攪拌後、１０分経過してから、それぞれの比容積（ＳＶ）を測定し、臭気を官能試験により評価した。比較例１においても、攪拌後、１０分経過してから、同様に比容積、臭気を測定した。結果を表２に示す。本発明の汚泥処理剤は凝集効果が大きく、脱臭効果を有することが判る。ＳＶは、攪拌後の汚泥濃縮水１００ミリリットルをメスシリンダーに採取し、所定の時間が経過した後、凝集した汚泥の体積を測定して、汚泥の体積（ミリリットル）／汚泥濃縮水１００ミリリットル（％）として算出した。
【００３０】
評価２
処理汚泥をろ紙（５Ａ）を用いてろ過し、ろ液のｐＨ、化学的酸素要求量（ＣＯＤ）、窒素含有量を測定した。結果を表２に示す。本発明の汚泥処理剤は中性でありｐＨには顕著な変化は認められず、またＣＯＤを低減させる効果や、窒素の除去効果も認められる。
【００３１】
【表２】
評価３
実施例３について、汚泥濃縮水に添加する汚泥処理剤（試料Ａ）の量を変更し、試料Ａを添加、攪拌し２０分経過した後の比容積を、評価１と同様にして測定した。また、比較例１についても、攪拌し２０分経過した後で、比容積を測定した。結果を表３に示す。本発明の汚泥処理剤の添加量が増加するに従い、低い比容積を示し、汚泥濃縮水に対し、汚泥処理剤１重量％を添加すると、比容積は比較例に対して半分に達することが示された。処理汚泥を、ろ紙（５Ａ）を用いてろ過し、固液分離した処理汚泥の含水率を測定したところ、表３のように含水率は添加量の増加とともに減少することが判る。
【００３３】
【表３】
実施例５、比較例２
伊勢湾で採取した浚渫汚泥に、実施例１で得られた汚泥処理剤（試料Ａ）を混合した。これを、実施例５とする。また、汚泥処理剤を用いなかったものを、比較例２とする。
【００３５】
評価４
実施例５において、浚渫汚泥（含水率５０％）１０ｇに水５００ミリリットルを加えて１０，０００ｍｇ・ｄｒｙ／リットルのスラリーとし、試料Ａの添加量を変えてこのスラリーに添加、攪拌した後、１０分及び２０分経過してから、それぞれの上澄み液のＳＳ（懸濁物質量、ミリグラム／リットル）を測定した。比較例２においても、攪拌後、１０分及び２０分経過してから、ＳＳを測定した。結果を表４に示す。本発明の汚泥処理剤は、浚渫汚泥に対しても、凝集効果が大きいことが判る。
【００３６】
【表４】
評価５
実施例５において、前記浚渫汚泥（含水率５０重量％）に対し、５０重量％になるように汚泥処理剤を加え攪拌後、密閉可能な容器に入れ、密閉状態で１日、室温において放置した。この密閉容器中の硫化水素濃度を、検知管法により測定した。また、比較例２についても、同様にして硫化水素の濃度を測定した。その結果を、表５に示す。本発明の汚泥処理剤により、汚泥中の硫化水素を固定化できることが判る。更に、汚泥中の酸化還元電位（ＯＲＰ）を測定したところ、本発明の汚泥処理剤を用いると、電位がプラス側に推移する、すなわち、好気性が強くなることが判る。
【００３８】
【表５】
実施例６
実施例６として処理剤の生体影響を確認するため、ビーカーＡに処理剤１００ｇに水１０００ミリリットル、対照としてビーカーＢに水１０００ミリリットルのみを入れ、これに河川で採取したシジミを入れ室温で放置した。７日間、シジミは生存し、７日目に環境の悪化にともないビーカーＡおよびＢ（対照）のシジミはいづれも死滅した。生存期間に差は認められず、生体への悪影響は無いと考えられる。
【００４０】
【発明の効果】
本発明の汚泥処理剤は、水酸化鉄と硫酸カルシウムとを含むことを特徴とする。この汚泥処理剤は中性であり、中和剤を必要としない点で他の鉄塩系処理剤とは大きく異なっている。この処理剤を用いることにより、汚泥の凝集性が向上し、含水率も低下するので、その後の固液分離、無害化、乾燥、焼却などの工程が容易になる。さらに、水酸化鉄の作用により、下水あるいは汚泥中の硫化水素を吸収、固定化するため、悪臭の除去も可能である。また、本発明には、硫酸法酸化チタンの製造工程から生じる廃硫酸などの鉄成分を含む廃酸を、カルシウム成分を含むアルカリで中和した中和生成物を用いることができ、安価な汚泥処理剤を提供できるので、汚泥処理のコストが低減される。処理後の汚泥は、硫酸カルシウムを含むことにより、コンポスト、セメント原料、土壌改良などの石膏含有資材として活用できる。
【図面の簡単な説明】
【図１】図１は本発明の処理フローの概要を示したものである。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a technology for treating sludge such as various types of sewage and sludge.
[0002]
[Prior art]
For sludge treatment of sewage sludge, lakes and marshes, sludge in sea areas, a sludge treatment agent is added to the water to be treated, and the sludge is agglomerated and reduced in volume. Dried or incinerated. Examples of the sludge treatment agent include aluminum-based treatment agents such as aluminum chloride, bansulfate (aluminum sulfate), and polyaluminum chloride (PAC); iron-based treatment agents such as iron chloride, iron sulfate, and iron hydroxide; Molecular compounds and the like are used.
However, the aluminum-based treating agent has a low deodorizing effect, generates odor from the treated sludge, and limits the final disposal method. Iron-based treatment agents have the effect of immobilizing hydrogen sulfide, which causes odors.However, water-soluble substances such as iron chloride and iron sulfate have acidity, which may affect biological organisms. When discharging to the environment, neutralization treatment is required. Further, coloring of the water to be treated by the eluted iron ions becomes a problem. The iron hydroxide is generally used indirectly in a method in which a water-soluble iron salt is added to water containing sludge and neutralized to form iron hydroxide and agglomerate the sludge. This method requires a large amount of neutralizing agent. The method of directly adding iron hydroxide has an insufficient coagulation effect. The water-soluble polymer compound has a better coagulation effect than the above-mentioned inorganic sludge treating agent, but is very expensive.
[0003]
[Problems to be solved by the invention]
An object of the present invention is to provide an economical sludge treating agent which is excellent in deodorizing and coagulating effects, and a method for treating sludge using the same.
[0004]
[Means for Solving the Problems]
As a result of intensive studies, the present inventors have found that the above-mentioned problems can be solved by a sludge treating agent containing iron hydroxide and calcium sulfate, and have completed the present invention.
[0005]
That is, the present invention according to claim 1 is a sludge treating agent containing iron hydroxide and calcium sulfate.
[0006]
The present invention according to claim 2 is characterized in that iron hydroxide is contained in the range of 10 to 60% by weight as Fe 2 O 3 and calcium sulfate is contained in the range of 20 to 50% by weight as CaSO 4. It is a sludge treating agent described.
[0007]
The present invention according to claim 3 is the sludge treating agent according to claim 1, further comprising at least one compound selected from a compound of silicon and a compound of aluminum.
[0008]
The present invention according to claim 4 is the sludge treating agent according to claim 1, further comprising water.
[0009]
The present invention according to claim 5 is the sludge treating agent according to claim 4, wherein the solid content is in the range of 30 to 60% by weight.
[0010]
The present invention according to claim 6 is the sludge treatment agent according to claim 1, wherein the sludge treatment agent is a neutralized product obtained by neutralizing waste acid containing an iron component with an alkali containing a calcium component.
[0011]
The present invention according to claim 7 is the sludge treating agent according to claim 6, wherein the waste acid is by-produced from the production process of titanium oxide.
[0012]
The present invention according to claim 8 is a sludge treatment method characterized by mixing a sludge treatment agent containing iron hydroxide and calcium sulfate with water or sludge containing sludge to aggregate sludge.
[0013]
The present invention according to claim 9 is the sludge treatment method according to claim 8, wherein the water containing sludge is sewage sludge concentrated water.
[0014]
The present invention according to claim 10 is the sludge treatment method according to claim 8, wherein the sludge is dredged sludge.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
The sludge treating agent of the present invention contains iron hydroxide and calcium sulfate. Due to the synergistic effect of these two components, each component has an excellent sludge flocculation and volume reduction action that cannot be obtained by each component alone, and subsequent processing steps such as dehydration, detoxification, drying, and incineration are easy. Further, since iron hydroxide adsorbs and fixes hydrogen sulfide, which is a main cause of offensive odor, sludge can be deodorized. For this reason, it is applied to a wide range of sludge treatment such as sewage such as domestic wastewater and industrial wastewater, and sludge in lakes and marshes and sea areas. Further, since the treated sludge contains calcium sulfate, it can be recovered and effectively used as a gypsum-containing material such as compost, a cement raw material, and a soil conditioner.
[0016]
As the calcium sulfate used for the treating agent, calcium sulfate dihydrate (gypsum dihydrate), calcium sulfate hemihydrate (gypsum hemihydrate), anhydrous calcium sulfate (anhydrite), and a mixture thereof can be used.
Iron hydroxide includes iron hydroxide and iron hydrate, and the oxidation number of iron can be appropriately selected. For example, when ferric hydroxide is used, trivalent iron is reduced in the sludge and acts as an oxygen supply agent, and thus is preferable when the sludge is subjected to aerobic treatment. In addition, when the treated sludge is backfilled in lakes and seas, the residual ferric iron prevents the bottom from being anoxic.
The preferred content of iron hydroxide is in the range of 10 to 60% by weight as Fe 2 O 3 , the preferred content of calcium sulfate is in the range of 20 to 50% by weight as CaSO 4 , and the more preferred ranges are respectively 15 to 50% by weight and 20 to 40% by weight.
In addition to iron hydroxide and calcium sulfate, the treating agent may contain other components, such as by-products involved in the production of the treating agent, as long as the effects of the present invention are not impaired. In addition, silicon compounds and aluminum compounds are known to have an action of removing organic compounds, soluble salts (SS) and nitrogen in water, and an action of reducing chemical oxygen demand (COD). At least one selected from the group consisting of:
[0017]
The form of the treatment agent can take various forms and can be appropriately selected according to the treatment method. For example, when it is made into a powder, a granule, a molded body, or the like, it can be easily introduced into water containing sludge such as sewage. On the other hand, when the treatment agent of the present invention contains water and is used in a wet state, it is easy to mix with dredged lakes and marshes and sludge in sea areas, which is preferable. Such a wet processing agent preferably has a solid content in the range of 30 to 60% by weight, more preferably 40 to 60% by weight. If the solid content exceeds 60% by weight, the desired effect cannot be obtained. If the solid content is less than 30% by weight, the composition becomes fluid and the workability is remarkably reduced, and the content of the active ingredient is small, which is not economical.
[0018]
As the treating agent of the present invention, in addition to a mixture of iron hydroxide and calcium sulfate, gypsum containing iron hydroxide by-produced in the neutralization step of various waste acids containing an iron component can also be used, The treatment agent of the present invention can be provided at low cost. As the latter, for example, a neutralized product (sludge) obtained by neutralizing waste sulfuric acid containing an iron component generated in the process of producing titanium oxide by a sulfuric acid method or an acid washing waste solution of iron with an alkali containing a calcium component such as lime. And the like. A specific method for preparing the treatment agent of the present invention from such waste acid will be described below.
[0019]
In the first method, an alkali containing a calcium component is added to sulfuric acid containing an iron component, for example, waste sulfuric acid generated in a process for producing titanium oxide by a sulfuric acid method, to neutralize the solution in a pH range of 7 to 9. The sulfate in the waste sulfuric acid reacts with the calcium component and precipitates as calcium sulfate, and at the same time, the iron component also precipitates as iron hydroxide. At the time of neutralization, air is blown into the liquid or oxidized by adding an oxidizing agent and the like, and the oxidation number can be adjusted.For example, the treating agent containing ferric hydroxide may be used as described above. It is obtained by oxidizing while neutralizing to. When these are separated into solid and liquid, the treating agent of the present invention is obtained.
[0020]
In the second method, first, as a first step, an alkali containing a calcium component is added to sulfuric acid containing an iron component, for example, waste sulfuric acid generated in a production process of a sulfuric acid method titanium oxide, and a pH of 4 to 6 is added. Neutralize in range. Part of the sulfate in the waste sulfuric acid reacts preferentially with the calcium component and precipitates as calcium sulfate containing almost no iron component, and is removed by solid-liquid separation such as concentration or filtration. Subsequently, an alkali containing a calcium component is further added to the supernatant or the filtrate after the solid-liquid separation in the second step, and the pH is neutralized in the range of 7 to 9 as in the first method, or Oxidizes while neutralizing. Unreacted sulfate and iron components in the supernatant or the filtrate react with the alkali components, respectively, and precipitate as iron hydroxide and calcium sulfate. In the second method, a treating agent having a high concentration of iron hydroxide is obtained, and calcium sulfate containing no by-produced iron component can be used as a gypsum material for gypsum boards and the like.
[0021]
The third method is that the supernatant or filtrate after the solid-liquid separation of the treating agent of the present invention in the second method, waste sulfuric acid containing unreacted ore and the like generated in the step of digesting titanium oxide in a sulfuric acid method, A chlorine-containing waste acid such as titanium tetrachloride generated in the chlorination process of titanium oxide is mixed with a hydrochloric acid waste acid, and an alkali containing a calcium component is added thereto. Neutralize in the range of ~ 9 or oxidize while neutralizing. Since the sulfate component and the iron component in the mixed waste acid respectively react with the alkali component and precipitate as iron hydroxide and calcium sulfate, the treating agent of the present invention can be obtained by solid-liquid separation of these components.
[0022]
Examples of the alkali containing a calcium component to be used include, in the first method, the second step of the second method, and the third method, a strong alkali such as calcium hydroxide in the first method of the second method. In the step, it is preferable to use a weak alkali such as calcium carbonate, since it is not necessary to adjust the pH. The obtained treating agent can be dried if necessary, and can be appropriately formed into a powder, a granule, a molded body, or the like. Alternatively, when the solid content is not dehydrated but is dehydrated until the solid content falls within the range of 30 to 60% by weight, a wet treatment agent can be obtained.
[0023]
The treating agent obtained by the above method contains iron hydroxide and calcium sulfate in the above range, that is, 10 to 60% by weight as Fe 2 O 3 and 20 to 50% by weight as CaSO 4. ing. May include other components slightly, from 0.5 to 10 weight in the case of using the waste sulfuric acid in the titanium oxide production process, 1-30 wt% compound of titanium as TiO 2, the compound of silicon as SiO 2 %, And a compound of aluminum in the range of 1 to 5% by weight as Al 2 O 3 .
[0024]
In the sludge treatment method of the present invention, first, a sludge treating agent containing iron hydroxide and calcium sulfate is mixed with water containing sludge such as sewage, or directly mixed with sludge to aggregate sludge. Before performing the sludge treatment, the water containing the sludge is usually concentrated, and the sludge content of such a sludge concentrate is in the range of 2000 to 30,000 mg / liter. It is preferable to add the sludge treating agent to the sludge concentrate having a concentration in this range in the range of 0.1 to 10% by weight, preferably 1.0 to 5% by weight, based on the sludge concentrate. In addition, dredged sludge obtained by dredging sludge in lakes, marshes, sea areas, and the like usually has a water content in the range of 50 to 90% by weight. % Of the mud treatment agent is preferably added. It is more preferable that the sludge treating agent is in a wet state containing water, because it can be easily mixed with sludge. This treatment not only makes the sludge aggregate and facilitates filtration and dehydration, but also reduces the volume of the treated material, thereby improving workability in the subsequent steps such as detoxification, drying, and incineration. The treated water from which the sludge has been removed is released into the environment such as rivers, lakes and marshes. Alternatively, if necessary, after advanced treatment such as detoxification in a sewage treatment plant or the like, the wastewater is circulated for use as treated water or discharged into the environment. Since the solid-liquid separated treated sludge contains calcium sulfate, it can be reused as a gypsum-containing material for compost, cement raw materials, soil conditioners, and the like. The treated sludge of dredged sludge can be used as a dry tidal flat forming material, or can be backfilled in lakes or marshes again after solidification treatment such as consolidation treatment or incineration.
[0025]
【Example】
Hereinafter, the present invention will be described with reference to examples, but these do not limit the present invention.
[0026]
Examples 1 and 2
As Example 1, the sludge treatment agent (sample A) of the present invention was obtained by applying the above-mentioned second method. Further, as Example 2, the sludge treating agent of the present invention (sample B) was obtained by applying the third method. Each chemical composition is described in Table 1.
[0027]
[Table 1]
Examples 3 and 4, Comparative Example 1
The sludge treating agents (samples A and B) obtained in Examples 1 and 2 were dissolved in sludge concentrated water (average concentration (MLSS) 12,500 mg / liter) generated in a sewage treatment plant. These are Examples 3 and 4, respectively. In addition, the case where no sludge treating agent was used is referred to as Comparative Example 1.
[0029]
Evaluation 1
In Examples 3 and 4, the sludge treating agents (samples A and B) were added so as to be 0.1% by weight with respect to the sludge concentrated water, followed by stirring. Ten minutes after the stirring, the respective specific volumes (SV) were measured, and the odor was evaluated by a sensory test. Also in Comparative Example 1, the specific volume and the odor were measured in the same manner 10 minutes after the stirring. Table 2 shows the results. It turns out that the sludge treating agent of the present invention has a large coagulation effect and a deodorizing effect. The SV collects 100 ml of the sludge concentrated water after stirring in a measuring cylinder, and after a predetermined time has elapsed, measures the volume of the aggregated sludge, and calculates the volume of the sludge (milliliter) / 100 ml of the sludge concentrated water (% ).
[0030]
Evaluation 2
The treated sludge was filtered using a filter paper (5A), and the pH, the chemical oxygen demand (COD), and the nitrogen content of the filtrate were measured. Table 2 shows the results. The sludge treating agent of the present invention is neutral and has no noticeable change in pH, and also has an effect of reducing COD and an effect of removing nitrogen.
[0031]
[Table 2]
Evaluation 3
In Example 3, the amount of the sludge treating agent (sample A) added to the sludge concentrated water was changed, and the specific volume after 20 minutes of adding and stirring sample A was measured in the same manner as in Evaluation 1. Also, for Comparative Example 1, the specific volume was measured after stirring for 20 minutes. Table 3 shows the results. As the addition amount of the sludge treatment agent of the present invention increases, the specific volume decreases, and when 1% by weight of the sludge treatment agent is added to the sludge concentrated water, the specific volume reaches half that of the comparative example. Was done. The treated sludge was filtered using a filter paper (5A), and the water content of the treated sludge subjected to solid-liquid separation was measured. As shown in Table 3, it was found that the water content decreased as the amount of addition increased.
[0033]
[Table 3]
Example 5, Comparative Example 2
The sludge treating agent (sample A) obtained in Example 1 was mixed with the dredged sludge collected in Ise Bay. This is Example 5. Further, Comparative Example 2 in which no sludge treatment agent was used was used.
[0035]
Evaluation 4
In Example 5, 500 ml of water was added to 10 g of the dredged sludge (water content: 50%) to obtain a slurry of 10,000 mg · dry / liter. After 20 minutes, the SS (suspended substance, milligram / liter) of each supernatant was measured. In Comparative Example 2, SS was measured 10 minutes and 20 minutes after the stirring. Table 4 shows the results. It can be seen that the sludge treating agent of the present invention has a large coagulation effect even on dredged sludge.
[0036]
[Table 4]
Evaluation 5
In Example 5, a sludge treating agent was added to the dredged sludge (water content: 50% by weight) so as to be 50% by weight, stirred, put in a sealable container, and left at room temperature in a closed state for one day. . The concentration of hydrogen sulfide in this sealed container was measured by a detector tube method. Also in Comparative Example 2, the concentration of hydrogen sulfide was measured in the same manner. Table 5 shows the results. It is found that the sludge treating agent of the present invention can fix hydrogen sulfide in sludge. Furthermore, when the oxidation-reduction potential (ORP) in the sludge was measured, it was found that when the sludge treating agent of the present invention was used, the potential shifted to the plus side, that is, the aerobicity became strong.
[0038]
[Table 5]
Example 6
In Example 6, 1000 ml of water was added to 100 g of the treating agent in a beaker A, and only 1000 ml of water was added to a beaker B as a control in order to confirm the biological effects of the treating agent. . For seven days, the clams survived, and on day 7, both clams of beakers A and B (control) died due to the deterioration of the environment. There is no difference in the survival time, and it is considered that there is no adverse effect on the living body.
[0040]
【The invention's effect】
The sludge treatment agent of the present invention is characterized by containing iron hydroxide and calcium sulfate. This sludge treatment agent is neutral, and differs greatly from other iron salt treatment agents in that it does not require a neutralizing agent. The use of this treating agent improves the cohesiveness of the sludge and lowers the water content, so that the subsequent steps such as solid-liquid separation, detoxification, drying, and incineration are facilitated. Further, by the action of iron hydroxide, hydrogen sulfide in sewage or sludge is absorbed and immobilized, so that an odor can be removed. Further, in the present invention, it is possible to use a neutralized product obtained by neutralizing a waste acid containing an iron component such as waste sulfuric acid generated from a manufacturing process of a titanium oxide by a sulfuric acid method with an alkali containing a calcium component, thereby obtaining inexpensive sludge. Since a treatment agent can be provided, the cost of sludge treatment is reduced. The sludge after treatment can be used as a gypsum-containing material such as compost, cement raw material, and soil improvement by containing calcium sulfate.
[Brief description of the drawings]
FIG. 1 shows an outline of a processing flow of the present invention.
Claims (10)
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006102660A (en) * | 2004-10-06 | 2006-04-20 | Mizusawa Ind Chem Ltd | Method for producing deodorant composite composition |
| WO2010073680A1 (en) * | 2008-12-25 | 2010-07-01 | 新日本製鐵株式会社 | Method of inhibiting dissolved-state sulfide from dissolving away from bottom sediment of water area |
| JP5852276B1 (en) * | 2015-03-04 | 2016-02-03 | 有限会社谷田建設 | Method for producing soil amendment |
| WO2016113946A1 (en) * | 2015-01-13 | 2016-07-21 | 住友金属鉱山株式会社 | Chromium-containing water treatment method |
| WO2020138264A1 (en) * | 2018-12-28 | 2020-07-02 | ライオン株式会社 | Interdental brush |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS54149256A (en) * | 1978-05-15 | 1979-11-22 | Fuji Satsushi Kogyo Kk | Dehydrating solidifying agent of sewage sludge and dehydrating solidifying method |
| JPS5698280A (en) * | 1979-12-29 | 1981-08-07 | Chiyoda Chem Eng & Constr Co Ltd | Method for deodorizing and enhancing strength of hydrous soft soil having bad smell |
| JPH01271000A (en) * | 1988-04-21 | 1989-10-30 | Fujisash Co | Process for modifying accumulated sludge |
| JP2001179006A (en) * | 1999-12-22 | 2001-07-03 | Neos Co Ltd | Regeneration treatment agent for paint-containing thinner |
| JP2002205077A (en) * | 2001-01-05 | 2002-07-23 | Ebara Corp | Method and apparatus for treating organic sewage |
| JP2002363559A (en) * | 2001-06-12 | 2002-12-18 | Odessa Technos Co Ltd | Improving method of neutral soil for control of hydrogen sulfide and improved material of neutral soil for control of hydrogen sulfide |
-
2003
- 2003-01-07 JP JP2003001172A patent/JP3950927B2/en not_active Expired - Lifetime
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS54149256A (en) * | 1978-05-15 | 1979-11-22 | Fuji Satsushi Kogyo Kk | Dehydrating solidifying agent of sewage sludge and dehydrating solidifying method |
| JPS5698280A (en) * | 1979-12-29 | 1981-08-07 | Chiyoda Chem Eng & Constr Co Ltd | Method for deodorizing and enhancing strength of hydrous soft soil having bad smell |
| JPH01271000A (en) * | 1988-04-21 | 1989-10-30 | Fujisash Co | Process for modifying accumulated sludge |
| JP2001179006A (en) * | 1999-12-22 | 2001-07-03 | Neos Co Ltd | Regeneration treatment agent for paint-containing thinner |
| JP2002205077A (en) * | 2001-01-05 | 2002-07-23 | Ebara Corp | Method and apparatus for treating organic sewage |
| JP2002363559A (en) * | 2001-06-12 | 2002-12-18 | Odessa Technos Co Ltd | Improving method of neutral soil for control of hydrogen sulfide and improved material of neutral soil for control of hydrogen sulfide |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006102660A (en) * | 2004-10-06 | 2006-04-20 | Mizusawa Ind Chem Ltd | Method for producing deodorant composite composition |
| WO2010073680A1 (en) * | 2008-12-25 | 2010-07-01 | 新日本製鐵株式会社 | Method of inhibiting dissolved-state sulfide from dissolving away from bottom sediment of water area |
| JP4938136B2 (en) * | 2008-12-25 | 2012-05-23 | 新日本製鐵株式会社 | Method for inhibiting dissolution of dissolved sulfide from sediments in water |
| WO2016113946A1 (en) * | 2015-01-13 | 2016-07-21 | 住友金属鉱山株式会社 | Chromium-containing water treatment method |
| JP2016129867A (en) * | 2015-01-13 | 2016-07-21 | 住友金属鉱山株式会社 | Method for treating chromium-containing water |
| CN107001083A (en) * | 2015-01-13 | 2017-08-01 | 住友金属矿山株式会社 | The processing method of the water containing chromium |
| US10442715B2 (en) | 2015-01-13 | 2019-10-15 | Sumitomo Metal Mining Co., Ltd. | Chromium-containing water treatment method |
| JP5852276B1 (en) * | 2015-03-04 | 2016-02-03 | 有限会社谷田建設 | Method for producing soil amendment |
| WO2020138264A1 (en) * | 2018-12-28 | 2020-07-02 | ライオン株式会社 | Interdental brush |
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