JP2004066105A - Deodorizing method of dehydrated sludge cake - Google Patents
Deodorizing method of dehydrated sludge cake Download PDFInfo
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- JP2004066105A JP2004066105A JP2002228726A JP2002228726A JP2004066105A JP 2004066105 A JP2004066105 A JP 2004066105A JP 2002228726 A JP2002228726 A JP 2002228726A JP 2002228726 A JP2002228726 A JP 2002228726A JP 2004066105 A JP2004066105 A JP 2004066105A
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- 239000010802 sludge Substances 0.000 title claims abstract description 108
- 230000001877 deodorizing effect Effects 0.000 title claims abstract description 32
- 238000000034 method Methods 0.000 title claims abstract description 23
- 239000002781 deodorant agent Substances 0.000 claims abstract description 57
- IOVCWXUNBOPUCH-UHFFFAOYSA-M Nitrite anion Chemical compound [O-]N=O IOVCWXUNBOPUCH-UHFFFAOYSA-M 0.000 claims abstract description 19
- 229960002026 pyrithione Drugs 0.000 claims abstract description 8
- XNRNJIIJLOFJEK-UHFFFAOYSA-N sodium;1-oxidopyridine-2-thione Chemical compound [Na+].[O-]N1C=CC=CC1=S XNRNJIIJLOFJEK-UHFFFAOYSA-N 0.000 claims abstract description 8
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 claims abstract description 4
- 229910052700 potassium Inorganic materials 0.000 claims abstract description 4
- 239000011591 potassium Substances 0.000 claims abstract description 4
- FGVVTMRZYROCTH-UHFFFAOYSA-N pyridine-2-thiol N-oxide Chemical class [O-][N+]1=CC=CC=C1S FGVVTMRZYROCTH-UHFFFAOYSA-N 0.000 claims abstract 6
- 239000007864 aqueous solution Substances 0.000 claims description 20
- 239000003795 chemical substances by application Substances 0.000 claims description 7
- 239000007788 liquid Substances 0.000 abstract description 9
- YBBJKCMMCRQZMA-UHFFFAOYSA-N pyrithione Chemical class ON1C=CC=CC1=S YBBJKCMMCRQZMA-UHFFFAOYSA-N 0.000 description 19
- 239000004480 active ingredient Substances 0.000 description 18
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 14
- LSDPWZHWYPCBBB-UHFFFAOYSA-N Methanethiol Chemical compound SC LSDPWZHWYPCBBB-UHFFFAOYSA-N 0.000 description 12
- LPXPTNMVRIOKMN-UHFFFAOYSA-M sodium nitrite Chemical compound [Na+].[O-]N=O LPXPTNMVRIOKMN-UHFFFAOYSA-M 0.000 description 12
- 239000011550 stock solution Substances 0.000 description 12
- 239000000126 substance Substances 0.000 description 12
- 238000002347 injection Methods 0.000 description 10
- 239000007924 injection Substances 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 7
- 238000004062 sedimentation Methods 0.000 description 7
- 235000010288 sodium nitrite Nutrition 0.000 description 6
- 238000011156 evaluation Methods 0.000 description 5
- 230000010349 pulsation Effects 0.000 description 5
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 4
- 238000005273 aeration Methods 0.000 description 4
- 239000000701 coagulant Substances 0.000 description 4
- 150000003839 salts Chemical group 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- 238000011282 treatment Methods 0.000 description 4
- -1 alkali metal salts Chemical class 0.000 description 3
- 238000010790 dilution Methods 0.000 description 3
- 239000012895 dilution Substances 0.000 description 3
- 229910000037 hydrogen sulfide Inorganic materials 0.000 description 3
- DPBJAVGHACCNRL-UHFFFAOYSA-N 2-(dimethylamino)ethyl prop-2-enoate Chemical compound CN(C)CCOC(=O)C=C DPBJAVGHACCNRL-UHFFFAOYSA-N 0.000 description 2
- AZFNGPAYDKGCRB-XCPIVNJJSA-M [(1s,2s)-2-amino-1,2-diphenylethyl]-(4-methylphenyl)sulfonylazanide;chlororuthenium(1+);1-methyl-4-propan-2-ylbenzene Chemical compound [Ru+]Cl.CC(C)C1=CC=C(C)C=C1.C1=CC(C)=CC=C1S(=O)(=O)[N-][C@@H](C=1C=CC=CC=1)[C@@H](N)C1=CC=CC=C1 AZFNGPAYDKGCRB-XCPIVNJJSA-M 0.000 description 2
- 238000007865 diluting Methods 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 235000010289 potassium nitrite Nutrition 0.000 description 2
- 239000004304 potassium nitrite Substances 0.000 description 2
- 239000010865 sewage Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- JKNCOURZONDCGV-UHFFFAOYSA-N 2-(dimethylamino)ethyl 2-methylprop-2-enoate Chemical compound CN(C)CCOC(=O)C(C)=C JKNCOURZONDCGV-UHFFFAOYSA-N 0.000 description 1
- HRPVXLWXLXDGHG-UHFFFAOYSA-N Acrylamide Chemical compound NC(=O)C=C HRPVXLWXLXDGHG-UHFFFAOYSA-N 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- CAMXVZOXBADHNJ-UHFFFAOYSA-N ammonium nitrite Chemical compound [NH4+].[O-]N=O CAMXVZOXBADHNJ-UHFFFAOYSA-N 0.000 description 1
- GJTDJAPHKDIQIQ-UHFFFAOYSA-L barium(2+);dinitrite Chemical compound [Ba+2].[O-]N=O.[O-]N=O GJTDJAPHKDIQIQ-UHFFFAOYSA-L 0.000 description 1
- AJAFRMGZWFDZAS-UHFFFAOYSA-M cesium;nitrite Chemical compound [Cs+].[O-]N=O AJAFRMGZWFDZAS-UHFFFAOYSA-M 0.000 description 1
- 238000004581 coalescence Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 229940079593 drug Drugs 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 239000010800 human waste Substances 0.000 description 1
- 239000010842 industrial wastewater Substances 0.000 description 1
- AAJBNRZDTJPMTJ-UHFFFAOYSA-L magnesium;dinitrite Chemical compound [Mg+2].[O-]N=O.[O-]N=O AAJBNRZDTJPMTJ-UHFFFAOYSA-L 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000011328 necessary treatment Methods 0.000 description 1
- ZVHHIDVFSYXCEW-UHFFFAOYSA-L nickel(ii) nitrite Chemical compound [Ni+2].[O-]N=O.[O-]N=O ZVHHIDVFSYXCEW-UHFFFAOYSA-L 0.000 description 1
- 150000002826 nitrites Chemical class 0.000 description 1
- 231100000989 no adverse effect Toxicity 0.000 description 1
- 230000009965 odorless effect Effects 0.000 description 1
- 230000002688 persistence Effects 0.000 description 1
- RAFRTSDUWORDLA-UHFFFAOYSA-N phenyl 3-chloropropanoate Chemical compound ClCCC(=O)OC1=CC=CC=C1 RAFRTSDUWORDLA-UHFFFAOYSA-N 0.000 description 1
- 238000011112 process operation Methods 0.000 description 1
- 230000003134 recirculating effect Effects 0.000 description 1
- 229940010109 rubidium nitrite Drugs 0.000 description 1
- VPMVPQJJBGXJAI-UHFFFAOYSA-M rubidium(1+);nitrite Chemical compound [Rb+].[O-]N=O VPMVPQJJBGXJAI-UHFFFAOYSA-M 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- HOWFTCIROIVKLW-UHFFFAOYSA-L strontium;dinitrite Chemical compound [Sr+2].[O-]N=O.[O-]N=O HOWFTCIROIVKLW-UHFFFAOYSA-L 0.000 description 1
- 150000003464 sulfur compounds Chemical class 0.000 description 1
- 229910052716 thallium Inorganic materials 0.000 description 1
- BKVIYDNLLOSFOA-UHFFFAOYSA-N thallium Chemical compound [Tl] BKVIYDNLLOSFOA-UHFFFAOYSA-N 0.000 description 1
- 238000004065 wastewater treatment Methods 0.000 description 1
Images
Abstract
Description
【０００１】
【発明の属する技術分野】
本発明は、汚泥脱水ケーキの脱臭方法に関し、とりわけ脱臭剤を往復動ポンプを介して汚泥に供給する汚泥脱水ケーキの脱臭方法に関する。
【０００２】
【従来の技術】
汚泥脱水ケーキの脱臭方法として、脱水されて脱水ケーキとなる前の汚泥に脱臭剤を供給する方法がある。従来、実機プラントでは、脱臭剤として水性液剤が用いられていた。水性液剤としては、ポンプの負荷が増大しないようにするために、また、大型の貯蔵タンクを必要としないようにするために、比較的高濃度（たとえば、有効成分濃度が４０重量％程度）の水性液剤が使用されていた。そして、脱臭剤の供給には、水性液剤を定量的に供給することができるプランジャーポンプなどの往復動ポンプが用いられていた。
【０００３】
しかし、往復動ポンプは、経時的にみた場合に供給量が変動する現象（脈動現象）を伴うので、とくに往復動ポンプを用いて脱臭剤を供給する場合には、たとえば、配管内で流動している汚泥に、脱臭剤を、連続的に一定割合で供給しつづけることが困難であり、その結果、脱臭剤が汚泥中に均一に分散しにくいといった問題があった。
【０００４】
たとえば、実験室で小規模な回分式で行なう脱臭剤の評価で得られる結果と比較して、往復動ポンプを用いた実機プラントで行なう評価では、充分な脱臭効果を得るために、脱臭剤の使用量を多くする必要があった。すなわち、実験室で小規模な回分式で行なう評価と比較して、往復動ポンプを用いた実機プラントで行なう評価では、脱臭剤の効率がわるく、脱臭効果の持続性がわるかった。これは、実験室で行なう小規模な回分式の評価では、脱臭剤を汚泥に供給したのちに充分に攪拌、混合することによって、脱臭剤を汚泥中に均一に分散させうるのに対して、実機プラントでは、脱臭剤を汚泥中に均一に分散させにくいことに起因するものと考えられる。そのため、実機プラントにおいて、実験室と同等の効率を得ることが求められていた。
【０００５】
【発明が解決しようとする課題】
本発明は、実機プラントにおいても、汚泥脱水ケーキの脱臭を、効率よく、長期間にわたって、行なうことができる方法を提供することを目的とする。
【０００６】
【課題を解決するための手段】
本発明は、亜硝酸塩の濃度が０．３８〜１９重量％であり、水溶性のピリチオン塩の濃度が０．０２〜１重量％である水性液剤からなる脱臭剤を、汚泥に供給することを特徴とする汚泥脱水ケーキの脱臭方法にかかわる。本発明は、亜硝酸塩および水溶性のピリチオン塩の濃度が低い水性液剤を使用することにより、有効成分を汚泥の全体にわたって均一に分散させやすくしたものである。
【０００７】
本発明は、脱臭剤を、往復動ポンプを介して、汚泥に供給する場合に好適である。本発明は、脱臭剤を、配管内の汚泥に供給する場合にとくに好適である。
【０００８】
本発明においては、汚泥１リットルあたりの脱臭剤の供給量を０．６〜９ｃｃとすることが好ましい。本発明において用いる水溶性のピリチオン塩としては、ナトリウムピリチオンまたはカリウムピリチオンが好ましい。本発明においては、脱臭剤を汚泥に供給する往復動ポンプを、汚泥を移送するポンプに連動させることが好ましい。
【０００９】
【発明の実施の形態】
本発明は、脱臭剤を汚泥に供給することにより、汚泥脱水ケーキから悪臭成分（たとえば、硫化水素、メチルメルカプタンなどのイオウ化合物）が発生することを抑制する汚泥脱水ケーキの脱臭方法にかかわる。本発明は、各種の汚泥、たとえば、下水処理場、し尿処理場、食品工場、紙パルプ工場などの有機性産業排水の処理工程などにおいて発生する各種の汚泥に、とくに制限なく、適用することができる。本発明によれば、汚泥脱水ケーキから悪臭成分が発生することを、効率よく、脱臭剤（有効成分）の使用量が少なくても、長期間にわたって、抑制することができる。
【００１０】
図１は、下水処理場で発生する汚泥に脱臭剤を供給して脱水ケーキの脱臭を行なう本発明の脱臭方法の一態様の工程を示すフロー図である。図１に示される工程では、原水１を、最初沈殿池２へ導入し、初沈生汚泥３を分離する。最初沈殿池２の上層水４ａに、必要に応じて凝集剤を添加したのち、曝気槽５へ移送し、活性汚泥法により生物的処理を行なう。曝気槽５の処理水６に、必要に応じて凝集剤を添加したのち、最終沈殿池７へ移送し、汚泥８を分離する。分離された汚泥８の一部を、返送汚泥９として曝気槽５に返送し、残余を余剰汚泥１０として処理する。
【００１１】
最終沈殿池７の上層水４ｂを、そのままで、または、必要な処理を施したのち、放流する。初沈生汚泥３および余剰汚泥１０を、濃縮汚泥槽１１へ移送する。濃縮汚泥槽１１において濃縮された汚泥（濃縮汚泥）１２を、汚泥供給ポンプ１３を介して、汚泥混和槽１４へ移送する。汚泥混和槽１４に貯留された汚泥を、脱水機１５により脱水し、脱水ケーキ１６として搬出する。濃縮汚泥槽１１の上層水４ｃおよび脱水機１５からの濾液１７を、原水１に返送する。
【００１２】
本発明においては、脱水機１５により脱水されて脱水ケーキ１６になる前の汚泥に、脱臭剤を供給する。図１に示される工程においては、濃縮汚泥槽１１から、汚泥供給ポンプ１３を介し、配管を通して汚泥混和槽１４に移送されている途中の濃縮汚泥１２に、薬品タンク１８から薬注ポンプ（往復動ポンプ）１９を介して脱臭剤を供給する。濃縮汚泥槽１１から汚泥混和槽１４に移送されている途中の濃縮汚泥１２は、通常９０〜９９．５重量％、多くの場合９５〜９９重量％の水を含有する。
【００１３】
脱臭剤を供給され、移送されている途中の濃縮汚泥１２に、さらに凝集剤２０を供給し、汚泥混和槽１４に移送し、フロックを形成させたのち、脱水機１５に移送し、脱水して脱水ケーキ１６とする。脱水ケーキ１６は、通常６５〜９０重量％、多くの場合７０〜８５重量％の水を含有する。凝集剤としては、たとえば、ジメチルアミノエチルアクリレート４級塩の重合体、ジメチルアミノエチルメタクリレート４級塩の重合体、これらの４級塩とアクリルアミドとの共重合体、ポリアミジンなどを用いることができる。凝集剤は、たとえば、汚泥の固形分に対して０．００５〜０．０４重量％、とりわけ０．００８〜０．０２重量％添加することができる。
【００１４】
たとえば、脱臭剤を供給する往復動ポンプ（薬注ポンプ１９）を、汚泥を移送するポンプ（汚泥供給ポンプ１３）に連動させることにより、汚泥（濃縮汚泥１２）が移送されると同時に、移送中の汚泥（濃縮汚泥１２）に、脱臭剤が供給されるようにすることができ、工程の運用管理上有利である。すなわち、連動させないと、薬注ポンプと汚泥供給ポンプのスイッチを同時に、オン、オフしなければならないので、作業が煩雑となる。また、連動させることにより、緊急停止時にもスイッチ１個で即応できる。
【００１５】
本発明においては、脱臭剤として、亜硝酸塩と水溶性のピリチオン塩とを含有する水性液剤を用いる。亜硝酸塩としては、たとえば、亜硝酸アンモニウム、亜硝酸ナトリウム、亜硝酸カリウム、亜硝酸ルビジウム、亜硝酸セシウム、亜硝酸カルシウム、亜硝酸ストロンチウム、亜硝酸マグネシウム、亜硝酸バリウム、亜硝酸ニッケル、亜硝酸タリウムなどをあげることができる。これらの亜硝酸塩は、１種を単独で用いることができ、または、２種以上を組み合わせて用いることもできる。これらのなかで、亜硝酸ナトリウムおよび亜硝酸カリウムは、脱水ケーキの二次使用を行なう場合にも利用先での悪影響がないので、とくに好適に用いることができる。
【００１６】
水溶性のピリチオン塩としては、たとえば、ナトリウムピリチオンまたはカリウムピリチオンなどのピリチオンのアルカリ金属塩をあげることができる。水不溶性のピリチオン塩では、脱臭剤タンクや脱臭剤配管内で、水性液剤から沈降分離し、タンクや配管を閉塞させる場合がある。
【００１７】
本発明において脱臭剤として用いられる水性液剤中の亜硝酸塩の濃度は０．３８〜１９重量％、好ましくは０．７６〜１２．７重量％、より好ましくは１．３〜７．６重量％であり、水溶性のピリチオン塩の濃度は０．０２〜１重量％、好ましくは０．０４〜０．６７重量％、より好ましくは０．０６〜０．４重量％である。亜硝酸塩の濃度が低すぎると、大型の薬品タンクや薬注ポンプを使用することが必要になり、設備価格の高騰を招き、経済的でなく、高すぎると、注入量が少なくなり、汚泥中の脱臭剤が均一分散できず、脱臭効果の低下を招く。水溶性のピリチオン塩の濃度が低すぎると、大型の薬品タンクや薬注ポンプを使用することが必要になり、経済的でなく、高すぎると、脱臭剤が均一分散できず、脱臭効果が低下する。
【００１８】
水性液剤中の亜硝酸塩と水溶性のピリチオン塩との合計の濃度は、たとえば、０．４〜２０重量％、好ましくは０．８〜１３．４重量％、より好ましくは１．４〜８重量％であることができる。亜硝酸塩と水溶性のピリチオン塩との合計の濃度が低すぎると、大型の薬品タンクや薬注ポンプを使用することが必要になり、経済的でなく、高すぎると、注入量が少なく、均一分散できず、脱臭効果が低下する。
【００１９】
水性液剤中の亜硝酸塩と水溶性のピリチオン塩との重量比は、たとえば、水溶性のピリチオン塩１重量部に対して、亜硝酸塩を０．３８〜９５０重量部、好ましくは２〜８０重量部、より好ましくは１０〜５０重量部とすることができる。水溶性のピリチオン塩に対する亜硝酸塩の重量比が少なすぎると、脱臭効果が低い場合があり、逆にピリチオン塩の重量比が少なすぎると、脱臭効果の持続性が低い場合がある。
【００２０】
亜硝酸塩および水溶性のピリチオン塩を含有する水性液剤は、たとえば、高濃度の原液を調製しておき、高濃度の原液を使用時に水で希釈して低濃度の水性液剤とすることにより、調製することができる。たとえば、亜硝酸塩と水溶性のピリチオン塩との合計の濃度が３０〜５０重量％の原液を調製しておき、使用時に水で２〜１００倍、とりわけ５〜３０倍に希釈して使用することが好ましい。
【００２１】
本発明は、脱臭剤を、往復動ポンプを介して、汚泥に供給する場合に、とくに好適である。往復動ポンプは、たとえば、プランジャー型定量ポンプがあり、ピストンまたはプランジャーなどの往復運動により、シリンダー内容積を変化させ、シリンダー内容積の拡大時にシリンダー内に液を吸い込み、縮小時にシリンダー内の液を吐出して圧送する形式のポンプである。他に、ダイヤフラム型定量ポンプなどがある。
【００２２】
とくに単動の往復動ポンプの場合、作動原理から、吐出流量が間欠的になり、脈動現象をともなう。脈動現象により、脱臭剤の吐出流量が間欠的になると、汚泥に対する脱臭剤の供給が間欠的になり、結果として、汚泥に対する脱臭剤中の有効成分の分散が不均一になりやすい。しかし、本発明においては、脱臭剤として、有効成分（亜硝酸塩、水溶性のピリチオン塩）の濃度が低い水性液剤を用いるので、汚泥に対する脱臭剤の供給が間欠的になっても、不均一の程度が緩和され、有効成分の拡散が不均一になりにくい。
【００２３】
脱臭剤は、たとえば、配管内の汚泥、タンク内の汚泥に供給することができる。本発明は、配管内の汚泥に脱臭剤を供給する場合に、とくに好適である。タンク内の汚泥に供給する場合には、有効成分の分散を均一にするために、たとえば、攪拌機で攪拌して有効成分を均一にするという手段を採用することもできる。しかし、配管内の汚泥を攪拌機で攪拌することは、装置の構造上、一般に困難である。したがって、攪拌機で攪拌しなくても、脱臭剤の有効成分を均一に分散させることができる本発明は、脱臭剤を配管内の汚泥に供給する場合に、とくに好適である。
【００２４】
脱臭剤（水性液剤）の供給量は、たとえば、汚泥１リットルあたり、０．６〜９ｃｃとすることができる。
【００２５】
【実施例】
実施例１〜３および比較例１
図１に示す工程にしたがって、汚泥脱水ケーキ１６の脱臭を行なった。濃縮汚泥（含水量９８重量％）１２を、１分間あたり１５０リットルの速度で、汚泥供給ポンプ１３を介して、移送し、そこへ脱臭剤原液を表１に示す水希釈倍率で希釈した脱臭剤（実施例１〜３）または脱臭剤原液（比較例１）を、薬注ポンプ１９を介して、注入した。
【００２６】
脱臭剤原液としては、亜硝酸ナトリウム濃度が３８重量％であり、ナトリウムピリチオン濃度が２重量％である水性液剤を用いた。薬注ポンプ１９としては、往復動ポンプであるプランジャー型定量ポンプ（原液および５倍稀釈時は、株式会社イワキ製ＬＧ−Ｆ２０２ＳＨ−０４ＦＥＳを、１０倍および３０倍稀釈時は、株式会社イワキ製ＬＧ−Ｆ４０２ＳＨ−０４ＦＥＳ）を用いた。ＬＧ−Ｆ２０２ＳＨ−０４ＦＥＳの吐出量３２６ｍＬ／分、最高吐出圧力４．０ＭＰａ、プランジャー径２０ｍｍ、ストローク数１１６ｓｐｍ、モータ出力０．４ｋＷであった。また、ＬＧ−Ｆ４０２ＳＨ−０４ＦＥＳは、吐出量１３５０ｍｌ／分、最高吐出圧１．０ＭＰａ、プランジャー径４０ｍｍ、ストローク数１１６ｓｐｍ、モータ出力０．４ｋＷであった。
【００２７】
脱臭剤または脱臭剤原液の注入量は、濃縮汚泥１２（体積）に対する水希釈前の脱臭剤原液としての注入量（体積）が３００ｐｐｍとなるようにした。したがって、実施例１〜３および比較例１において、一定量の汚泥に対する脱臭剤の有効成分（亜硝酸ナトリウム、ナトリウムピリチオン）の供給量は、同じである。
【００２８】
脱臭剤（実施例１〜３）または脱臭剤原液（比較例１）を注入した濃縮汚泥１２に、濃縮汚泥の固形分１ｋｇあたり、０．２ｇの凝集剤（ジメチルアミノエチルアクリレート４級塩の重合体：第一工業製薬（株）製のハイセットＣ２００Ｈ）２０を注入し、汚泥混和槽１４でフロックを作成したのち、脱水機１５で脱水して脱水ケーキ（含水量：８０重量％）１６を得た。脱水機１５の出口で、脱水ケーキ１６をサンプリングし、その５０ｇを５リットルのテトラバックに入れ、密封後、無臭空気を２リットル入れ、測定用サンプルとして２５℃の恒温槽に保存した。保存開始２４時間後、４８時間後および７２時間後に、テトラバック内で発生した悪臭成分（硫化水素（Ｈ２Ｓ）、メチルメルカプタン（ＭＭ））を検知管（（株）ガステック製）で測定した。結果を表１に示す。
【００２９】
【表１】
表１に示した結果より、汚泥に有効成分（亜硝酸ナトリウム、ナトリウムピリチオン）の濃度が高い水性液剤（脱臭剤原液）を注入した比較例１では、４８時間後にメチルメルカプタンが検出され、７２時間後にメチルメルカプタンおよび硫化水素が検出された。このことは、汚泥に有効成分の濃度が高い水性液剤を注入する従来技術では、脱水ケーキから悪臭成分が発生することを長期間にわたって抑制することができないことを示す。
【００３１】
これに対して、汚泥に有効成分（亜硝酸ナトリウム、ナトリウムピリチオン）の濃度が低い水性液剤（脱臭剤）を注入した実施例１〜３では、７２時間後にも悪臭成分（メチルメルカプタン、硫化水素）が検出されなかった。このことは、汚泥に有効成分の濃度が低い水性液剤（脱臭剤）を注入する本発明によれば、脱水ケーキから悪臭成分が発生することを長期間にわたって抑制することができることを意味し、本発明が、脱水ケーキを長期間貯蔵しなければならない場合にとくに有用であることを示す。
【００３２】
実施例１〜３において、比較例１よりも、脱水ケーキからの悪臭成分の発生を長期間にわたって抑制することができるのは、以下の理由によるものと考えられる。すなわち、比較例１では、有効成分の濃度が高い水性液剤（脱臭剤原液）を汚泥に注入するので、水性液剤としての注入量（体積）がちいさく、汚泥に対してｐｐｍオーダー（３００ｐｐｍ）であり、脈動による影響がおおきく、有効成分を汚泥の全体にわたって均一に分散させることが困難である。これに対して、各実施例では、有効成分の濃度が低い水性液剤（脱臭剤）を汚泥に注入するので、有効成分の供給量が同じ条件では、水性液剤としての注入量（体積）がおおきく、汚泥に対して％オーダー（０．１５％、０．３％、０．９％）であり、脈動による影響が相対的にちいさく、有効成分を汚泥の全体にわたって均一に分散させやすい。
【００３３】
【発明の効果】
本発明によれば、従来の高濃度の脱臭剤を汚泥に供給する脱臭方法と比較して、脱臭剤の有効成分（亜硝酸塩、水溶性のピリチオン塩）の添加量が同一でも、より長期間にわたって、脱臭効果を維持することができ、悪臭成分の発生を抑制することができる。
【図面の簡単な説明】
【図１】本発明の脱臭方法の一態様の工程を示すフロー図である。
【符号の説明】
２ 最初沈殿池
５ 曝気槽
７ 最終沈殿池
１１ 濃縮汚泥槽
１３ 汚泥供給ポンプ
１４ 汚泥混和槽
１５ 脱水機
１８ 薬品タンク
１９ 薬注ポンプ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for deodorizing sludge dewatered cake, and more particularly to a method for deodorizing sludge dewatered cake in which a deodorant is supplied to sludge via a reciprocating pump.
[0002]
[Prior art]
As a method of deodorizing a sludge dewatered cake, there is a method of supplying a deodorant to sludge before being dewatered to become a dewatered cake. Conventionally, in an actual plant, an aqueous solution has been used as a deodorant. As the aqueous liquid, a relatively high concentration (for example, the concentration of the active ingredient is about 40% by weight) is used so as not to increase the load on the pump and not to require a large storage tank. Aqueous solutions were used. In addition, a reciprocating pump such as a plunger pump capable of quantitatively supplying the aqueous solution has been used for supplying the deodorant.
[0003]
However, a reciprocating pump involves a phenomenon that the supply amount fluctuates (pulsation phenomenon) when viewed over time. In particular, when a reciprocating pump is used to supply a deodorant, for example, the recirculating pump flows in a pipe. It is difficult to continuously supply the deodorant to the sludge at a constant rate, and as a result, there is a problem that the deodorant is difficult to uniformly disperse in the sludge.
[0004]
For example, in comparison with the results obtained in the evaluation of a deodorizer performed in a small batch in a laboratory, in the evaluation performed in an actual plant using a reciprocating pump, in order to obtain a sufficient deodorizing effect, It was necessary to use more. That is, in the evaluation performed in the actual plant using the reciprocating pump, the efficiency of the deodorant was poor, and the sustainability of the deodorizing effect was poor compared to the evaluation performed in a laboratory using a small batch type. This is because, in a small batch type evaluation performed in a laboratory, the deodorant can be uniformly dispersed in the sludge by sufficiently stirring and mixing after supplying the deodorant to the sludge. This is considered to be due to the fact that it is difficult to disperse the deodorant uniformly in the sludge in the actual plant. Therefore, in an actual plant, it has been required to obtain the same efficiency as that of a laboratory.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to provide a method capable of efficiently deodorizing a sludge dewatered cake over a long period of time even in an actual plant.
[0006]
[Means for Solving the Problems]
The present invention provides a method for supplying a sludge with a deodorant comprising an aqueous solution having a concentration of nitrite of 0.38 to 19% by weight and a concentration of a water-soluble pyrithione salt of 0.02 to 1% by weight. It is related to the characteristic method of deodorizing sludge dewatered cake. The present invention makes it easier to uniformly disperse the active ingredient throughout the sludge by using an aqueous solution having a low concentration of nitrite and a water-soluble pyrithione salt.
[0007]
The present invention is suitable for supplying a deodorant to sludge via a reciprocating pump. The present invention is particularly suitable for supplying a deodorant to sludge in piping.
[0008]
In the present invention, the supply amount of the deodorant per liter of sludge is preferably 0.6 to 9 cc. As the water-soluble pyrithione salt used in the present invention, sodium pyrithione or potassium pyrithione is preferable. In the present invention, it is preferable that the reciprocating pump that supplies the deodorant to the sludge is linked to the pump that transfers the sludge.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention relates to a method for deodorizing a sludge dewatered cake, which suppresses generation of malodorous components (for example, sulfur compounds such as hydrogen sulfide and methyl mercaptan) from a sludge dewatered cake by supplying a deodorant to the sludge. The present invention can be applied to various kinds of sludge without particular limitation, for example, various kinds of sludge generated in an organic industrial wastewater treatment process of a sewage treatment plant, a human waste treatment plant, a food factory, a pulp and paper factory, and the like. it can. ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of a malodorous component from a sludge dewatering cake can be suppressed efficiently over a long period of time, even if the usage-amount of a deodorant (active ingredient) is small.
[0010]
FIG. 1 is a flow chart showing the steps of one embodiment of the deodorizing method of the present invention in which a deodorizing agent is supplied to sludge generated in a sewage treatment plant to deodorize a dewatered cake. In the step shown in FIG. 1, raw water 1 is first introduced into a sedimentation basin 2, and primary sludge 3 is separated. First, a coagulant is added to the
[0011]
The
[0012]
In the present invention, a deodorant is supplied to the sludge before it is dewatered by the dehydrator 15 to become the dewatered cake 16. In the process shown in FIG. 1, a chemical injection pump (reciprocating motion) from a concentrated sludge tank 11 to a concentrated sludge 12 being transferred to a sludge mixing tank 14 through a pipe via a sludge supply pump 13 to a sludge mixing tank 14. A deodorant is supplied via a pump 19. The concentrated sludge 12 being transferred from the concentrated sludge tank 11 to the sludge mixing tank 14 usually contains 90 to 99.5% by weight, and often 95 to 99% by weight of water.
[0013]
The coagulant 20 is further supplied to the concentrated sludge 12 which has been supplied with the deodorant and is being transferred, and is transferred to the sludge mixing tank 14 to form flocs. The dehydrated cake 16 is used. The dewatered cake 16 usually contains 65-90% by weight, often 70-85% by weight of water. As the coagulant, for example, a polymer of a quaternary salt of dimethylaminoethyl acrylate, a polymer of a quaternary salt of dimethylaminoethyl methacrylate, a copolymer of these quaternary salts with acrylamide, polyamidine and the like can be used. The flocculant can be added, for example, in an amount of 0.005 to 0.04% by weight, particularly 0.008 to 0.02% by weight, based on the solid content of the sludge.
[0014]
For example, by linking a reciprocating pump (drug pump 19) for supplying a deodorant with a pump (sludge supply pump 13) for transferring sludge, the sludge (concentrated sludge 12) is transferred at the same time as the sludge is transferred. The sludge (concentrated sludge 12) can be supplied with a deodorant, which is advantageous in process operation management. That is, if not linked, the switches of the chemical injection pump and the sludge supply pump must be turned on and off at the same time, which complicates the operation. In addition, by linking, even in the case of an emergency stop, one switch can be used immediately.
[0015]
In the present invention, an aqueous solution containing nitrite and a water-soluble pyrithione salt is used as a deodorant. Examples of the nitrite include ammonium nitrite, sodium nitrite, potassium nitrite, rubidium nitrite, cesium nitrite, calcium nitrite, strontium nitrite, magnesium nitrite, barium nitrite, nickel nitrite, and thallium nitrite. I can give it. One of these nitrites can be used alone, or two or more can be used in combination. Among them, sodium nitrite and potassium nitrite can be particularly preferably used because there is no adverse effect at the place of use even when the dehydrated cake is used secondarily.
[0016]
Examples of the water-soluble pyrithione salt include alkali metal salts of pyrithione such as sodium pyrithione and potassium pyrithione. In the case of a water-insoluble pyrithione salt, sedimentation and separation from an aqueous solution may occur in a deodorant tank or a deodorant pipe, and the tank or the pipe may be blocked.
[0017]
The concentration of nitrite in the aqueous solution used as a deodorant in the present invention is 0.38 to 19% by weight, preferably 0.76 to 12.7% by weight, more preferably 1.3 to 7.6% by weight. Yes, the concentration of the water-soluble pyrithione salt is 0.02 to 1% by weight, preferably 0.04 to 0.67% by weight, more preferably 0.06 to 0.4% by weight. If the concentration of nitrite is too low, it is necessary to use a large chemical tank or chemical injection pump, which leads to a rise in equipment prices, and it is not economical. Cannot be uniformly dispersed, resulting in a decrease in the deodorizing effect. If the concentration of the water-soluble pyrithione salt is too low, it is necessary to use a large chemical tank or a chemical injection pump, and it is not economical. If it is too high, the deodorant cannot be uniformly dispersed and the deodorizing effect is reduced. I do.
[0018]
The total concentration of the nitrite and the water-soluble pyrithione salt in the aqueous solution is, for example, 0.4 to 20% by weight, preferably 0.8 to 13.4% by weight, more preferably 1.4 to 8% by weight. %. If the total concentration of nitrite and water-soluble pyrithione salt is too low, it is necessary to use a large chemical tank or a chemical pump, and it is not economical. It cannot be dispersed and the deodorizing effect is reduced.
[0019]
The weight ratio of the nitrite to the water-soluble pyrithione salt in the aqueous solution is, for example, 0.38 to 950 parts by weight, preferably 2 to 80 parts by weight of the nitrite with respect to 1 part by weight of the water-soluble pyrithione salt. , More preferably 10 to 50 parts by weight. If the weight ratio of the nitrite to the water-soluble pyrithione salt is too small, the deodorizing effect may be low, and if the weight ratio of the pyrithione salt is too small, the persistence of the deodorizing effect may be low.
[0020]
An aqueous solution containing nitrite and a water-soluble pyrithione salt is prepared, for example, by preparing a high-concentration stock solution and diluting the high-concentration stock solution with water at the time of use to obtain a low-concentration aqueous solution. can do. For example, a stock solution having a total concentration of nitrite and a water-soluble pyrithione salt of 30 to 50% by weight is prepared, and diluted with water 2 to 100 times, particularly 5 to 30 times when used. Is preferred.
[0021]
The present invention is particularly suitable for supplying a deodorant to sludge via a reciprocating pump. Reciprocating pumps include, for example, a plunger type metering pump, in which the volume inside the cylinder is changed by reciprocating motion of a piston or a plunger, the liquid is sucked into the cylinder when the volume inside the cylinder is expanded, and the pressure inside the cylinder is reduced when the volume is reduced. This is a pump that discharges liquid and sends it under pressure. Another example is a diaphragm type metering pump.
[0022]
In particular, in the case of a single-acting reciprocating pump, the discharge flow rate becomes intermittent due to the operation principle, which is accompanied by a pulsation phenomenon. When the discharge flow rate of the deodorant becomes intermittent due to the pulsation phenomenon, the supply of the deodorant to the sludge becomes intermittent, and as a result, the dispersion of the effective component in the deodorant to the sludge tends to become uneven. However, in the present invention, since the aqueous solution having a low concentration of the active ingredient (nitrite, water-soluble pyrithione salt) is used as the deodorant, even if the supply of the deodorant to the sludge is intermittent, the unevenness is not uniform. The degree is reduced, and the diffusion of the active ingredient is less likely to be uneven.
[0023]
The deodorant can be supplied to, for example, sludge in piping and sludge in a tank. The present invention is particularly suitable for supplying a deodorant to sludge in piping. When supplying to the sludge in the tank, in order to make the dispersion of the active ingredient uniform, for example, means for stirring the active ingredient to make the active ingredient uniform may be employed. However, it is generally difficult to stir the sludge in the pipe with a stirrer due to the structure of the apparatus. Therefore, the present invention, in which the effective components of the deodorant can be uniformly dispersed without stirring with a stirrer, is particularly suitable when the deodorant is supplied to the sludge in the piping.
[0024]
The supply amount of the deodorant (aqueous liquid) can be, for example, 0.6 to 9 cc per liter of sludge.
[0025]
【Example】
Examples 1 to 3 and Comparative Example 1
According to the process shown in FIG. 1, the sludge dewatering cake 16 was deodorized. Condensed sludge (water content: 98% by weight) 12 is transferred at a rate of 150 liters per minute via a sludge feed pump 13, and the deodorant stock solution is diluted with the water dilution ratio shown in Table 1 there. (Examples 1 to 3) or a deodorant stock solution (Comparative Example 1) was injected via the chemical injection pump 19.
[0026]
As the deodorant stock solution, an aqueous solution having a sodium nitrite concentration of 38% by weight and a sodium pyrithione concentration of 2% by weight was used. As the chemical injection pump 19, a plunger type metering pump which is a reciprocating pump (LG-F202SH-04FES manufactured by Iwaki Co., Ltd. at the time of diluting the stock solution and 5-fold, and manufactured by Iwaki Co., Ltd. at the time of 10-fold and 30-fold dilution) LG-F402SH-04FES). The discharge rate of LG-F202SH-04FES was 326 mL / min, the maximum discharge pressure was 4.0 MPa, the plunger diameter was 20 mm, the number of strokes was 116 spm, and the motor output was 0.4 kW. The LG-F402SH-04FES had a discharge rate of 1350 ml / min, a maximum discharge pressure of 1.0 MPa, a plunger diameter of 40 mm, a stroke number of 116 spm, and a motor output of 0.4 kW.
[0027]
The injection amount (volume) of the deodorant or the stock solution of the deodorant was 300 ppm with respect to the concentrated sludge 12 (volume) as the stock solution of the deodorant before dilution with water. Therefore, in Examples 1 to 3 and Comparative Example 1, the supply amounts of the effective components (sodium nitrite, sodium pyrithione) of the deodorant to a fixed amount of sludge are the same.
[0028]
0.2 g of a flocculant (dimethylaminoethyl acrylate quaternary salt weight) per 1 kg of the solid content of the concentrated sludge was added to the concentrated sludge 12 into which the deodorant (Examples 1 to 3) or the stock solution of the deodorant (Comparative Example 1) was injected. Coalescence: High Set C200H (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 20 was injected, flocs were formed in a sludge mixing tank 14, and then dewatered by a dehydrator 15 to obtain a dewatered cake (water content: 80% by weight) 16. Obtained. At the outlet of the dehydrator 15, the dehydrated cake 16 was sampled, 50 g of the sample was placed in a 5-liter tetrabag, sealed, and then 2 liters of odorless air was charged. The sample was stored in a thermostat at 25 ° C. as a measurement sample. At 24 hours, 48 hours, and 72 hours after the start of storage, malodorous components (hydrogen sulfide (H2S), methyl mercaptan (MM)) generated in the Tetra Vac were measured using a detector tube (manufactured by Gastech Co., Ltd.). Table 1 shows the results.
[0029]
[Table 1]
From the results shown in Table 1, in Comparative Example 1 in which an aqueous solution (stock solution of deodorant) having a high concentration of active ingredients (sodium nitrite, sodium pyrithione) was injected into sludge, methyl mercaptan was detected after 48 hours, and 72 hours. Later, methyl mercaptan and hydrogen sulfide were detected. This indicates that the generation of malodorous components from the dewatered cake cannot be suppressed for a long period of time by the conventional technique of injecting an aqueous solution having a high active ingredient concentration into sludge.
[0031]
On the other hand, in Examples 1 to 3 in which the aqueous solution (deodorant) having a low concentration of the active ingredient (sodium nitrite, sodium pyrithione) was injected into the sludge, the malodorous components (methyl mercaptan, hydrogen sulfide) were obtained even after 72 hours. Was not detected. This means that according to the present invention in which an aqueous solution (deodorant) having a low concentration of the active ingredient is injected into the sludge, generation of malodorous components from the dewatered cake can be suppressed for a long period of time. The invention shows that the invention is particularly useful when the dewatered cake has to be stored for a long time.
[0032]
In Examples 1 to 3, the reason why the generation of malodorous components from the dehydrated cake can be suppressed over a longer period than in Comparative Example 1 is considered to be as follows. That is, in Comparative Example 1, since the aqueous liquid (deodorant stock solution) having a high concentration of the active ingredient is injected into the sludge, the injection amount (volume) as the aqueous liquid is small, which is on the order of ppm (300 ppm) with respect to the sludge. The effect of pulsation is large, and it is difficult to disperse the active ingredient uniformly throughout the sludge. In contrast, in each embodiment, since the aqueous liquid (deodorant) having a low concentration of the active ingredient is injected into the sludge, the injection amount (volume) of the aqueous liquid is large under the same supply amount of the active ingredient. % Of the sludge (0.15%, 0.3%, 0.9%), the influence of the pulsation is relatively small, and the active ingredient is easily dispersed uniformly throughout the sludge.
[0033]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, compared with the conventional deodorizing method which supplies a high-concentration deodorizing agent to sludge, even if the addition amount of the active ingredient (nitrite, water-soluble pyrithione salt) of a deodorizing agent is the same, a longer term In this manner, the deodorizing effect can be maintained, and the generation of malodorous components can be suppressed.
[Brief description of the drawings]
FIG. 1 is a flowchart showing the steps of one embodiment of the deodorizing method of the present invention.
[Explanation of symbols]
2 First sedimentation tank 5 Aeration tank 7 Final sedimentation tank 11 Condensed sludge tank 13 Sludge supply pump 14 Sludge mixing tank 15 Dehydrator 18 Chemical tank 19 Chemical injection pump
Claims (7)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2002228726A JP3635078B2 (en) | 2002-08-06 | 2002-08-06 | Deodorization method of sludge dewatering cake |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2002228726A JP3635078B2 (en) | 2002-08-06 | 2002-08-06 | Deodorization method of sludge dewatering cake |
Publications (2)
| Publication Number | Publication Date |
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| JP3635078B2 JP3635078B2 (en) | 2005-03-30 |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005169266A (en) * | 2003-12-11 | 2005-06-30 | Kurita Water Ind Ltd | Offensive smell inhibitor of sludge slurry or sludge dehydrated cake |
| JP2006075703A (en) * | 2004-09-08 | 2006-03-23 | Asahi Kasei Chemicals Corp | Deodorant and deodorizing method |
| WO2009006262A1 (en) | 2007-06-28 | 2009-01-08 | Buckman Laboratories International, Inc. | Use of cyclodextrins for odor control in papermaking sludges, and deodorized sludge and products |
| JP2013086007A (en) * | 2011-10-17 | 2013-05-13 | Nippon Steel & Sumikin Eco-Tech Corp | Deodorization method for sludge slurry, deodorization method for dehydrated cake and deodorant |
| JP2014233693A (en) * | 2013-06-04 | 2014-12-15 | 水ｉｎｇ株式会社 | Deodorizing method and device of dehydrated cake |
-
2002
- 2002-08-06 JP JP2002228726A patent/JP3635078B2/en not_active Expired - Lifetime
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005169266A (en) * | 2003-12-11 | 2005-06-30 | Kurita Water Ind Ltd | Offensive smell inhibitor of sludge slurry or sludge dehydrated cake |
| JP2006075703A (en) * | 2004-09-08 | 2006-03-23 | Asahi Kasei Chemicals Corp | Deodorant and deodorizing method |
| WO2009006262A1 (en) | 2007-06-28 | 2009-01-08 | Buckman Laboratories International, Inc. | Use of cyclodextrins for odor control in papermaking sludges, and deodorized sludge and products |
| US8147651B2 (en) | 2007-06-28 | 2012-04-03 | Buckman Laboratories International, Inc. | Use of cyclodextrins for odor control in papermaking sludges, and deodorized sludge and products |
| JP2013086007A (en) * | 2011-10-17 | 2013-05-13 | Nippon Steel & Sumikin Eco-Tech Corp | Deodorization method for sludge slurry, deodorization method for dehydrated cake and deodorant |
| JP2014233693A (en) * | 2013-06-04 | 2014-12-15 | 水ｉｎｇ株式会社 | Deodorizing method and device of dehydrated cake |
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| Publication number | Publication date |
|---|---|
| JP3635078B2 (en) | 2005-03-30 |
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