JP6917299B2 - Dehydration method of organic sludge, processing equipment used for dehydration of organic sludge, organic coagulant - Google Patents
Dehydration method of organic sludge, processing equipment used for dehydration of organic sludge, organic coagulant Download PDFInfo
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- Separation Of Suspended Particles By Flocculating Agents (AREA)
- Centrifugal Separators (AREA)
- Treatment Of Sludge (AREA)
Description
本発明は、有機性汚泥の脱水方法及びその装置、有機凝結剤に関する。 The present invention relates to a method for dehydrating organic sludge, an apparatus thereof, and an organic coagulant.
近年、廃棄物量の削減や廃棄物の再利用などが求められている。有機性汚泥は通常脱水後に廃棄物として処理されるが、脱水が不十分であると、発生量やその後の工程に影響を及ぼす。そのため、効率的および効果的な有機性汚泥の脱水方法の開発が望まれている。 In recent years, there has been a demand for reduction of the amount of waste and reuse of waste. Organic sludge is usually treated as waste after dewatering, but insufficient dewatering affects the amount generated and subsequent processes. Therefore, it is desired to develop an efficient and effective method for dehydrating organic sludge.
有機性汚泥の脱水方法として、高分子凝集剤により汚泥を凝集させた後、機械的脱水を行う方法（「１液法」と称される）や、高分子凝集剤により汚泥を凝集させた後、重力濃縮で脱水した汚泥に高分子凝集剤を添加し、機械的脱水を行う方法（「高分子凝集剤２液添加法」と称される）、無機凝集剤または有機凝結剤など脱水助剤を汚泥に添加した後、高分子凝集剤で凝集させ、機械的脱水を行う方法（「無機凝集剤または有機凝結剤・前添加法」と称される）などが一般的に行われてきた。 As a method for dehydrating organic sludge, a method of coagulating sludge with a polymer flocculant and then mechanically dehydrating it (referred to as a "one-component method") or a method of coagulating sludge with a polymer flocculant is performed. , A method of mechanically dehydrating by adding a polymer flocculant to sludge dehydrated by gravity concentration (referred to as "polymer coagulant two-component addition method"), a dehydration aid such as an inorganic flocculant or an organic coagulant. Is generally added to sludge and then agglomerated with a polymer flocculant to perform mechanical dehydration (referred to as "inorganic flocculant or organic coagulant / pre-addition method").
遠心脱水機による汚泥の脱水方法として、脱水機内へ汚泥と高分子凝集剤を供給して汚泥粒子を凝集させ、遠心脱水をする過程で無機凝結剤を添加し、遠心脱水および固液分離を行う方法（「機内２液調質法」と称される）が知られている。 As a method of dehydrating sludge by a centrifugal dehydrator, sludge and a polymer flocculant are supplied into the dehydrator to aggregate sludge particles, and an inorganic coagulant is added in the process of centrifugal dehydration to perform centrifugal dehydration and solid-liquid separation. A method (referred to as "in-flight two-component tempering method") is known.
また、近年、有機性汚泥の別の脱水方法として、高分子凝集剤により汚泥を凝集させた後、凝集汚泥を重力濃縮し、無機凝結剤や有機凝結剤など脱水助剤を汚泥に添加した後、機械的脱水を行う方法（「無機凝集剤または有機凝結剤・後添加法」と称される。）が提案されている。 Further, in recent years, as another dewatering method for organic sludge, after coagulating sludge with a polymer coagulant, the coagulated sludge is gravity-concentrated, and a dehydration aid such as an inorganic coagulant or an organic coagulant is added to the sludge. , A method of performing mechanical dehydration (referred to as "inorganic coagulant or organic coagulant / post-addition method") has been proposed.
一方、有機性汚泥の脱水工程において、特に無機凝集剤などを添加する場合、汚泥や脱水ろ液中の溶解性カルシウム濃度や硫酸イオン濃度が高くなるため、脱水機や周辺の配管などに石膏スケールが生成される。石膏スケールの付着は強固であるため、除去や洗浄には多くの労力を要する。 On the other hand, in the process of dehydrating organic sludge, especially when an inorganic flocculant is added, the concentration of soluble calcium and the concentration of sulfate ions in the sludge and the dehydration filtrate become high, so gypsum scale is applied to the dehydrator and surrounding piping. Is generated. Since the gypsum scale adheres strongly, it requires a lot of labor to remove and clean.
特許文献１には、カチオン性高分子凝集剤Ｉを添加・撹拌する工程と、凝集汚泥を重力により固液分離する工程と、脱水ケーキに高分子凝集剤Ｉよりカチオン強度の強い高分子凝集剤ＩＩを添加・撹拌する工程と、機械脱水する工程とを有する有機性汚泥の脱水方法が開示されている。 Patent Document 1 describes a step of adding and stirring a cationic polymer flocculant I, a step of solid-liquid separating agglomerated sludge by gravity, and a polymer flocculant having a stronger cation strength than the polymer flocculant I in a dehydrated cake. A dewatering method for organic sludge having a step of adding / stirring II and a step of mechanically dewatering is disclosed.
また、カチオン性高分子凝集剤ＩＩのカチオン強度は３．５または５．０ｍｅｑ／ｇ以上が好ましいとの記載があり、その実施例ではポリアミン系の高分子凝集剤を使用している。 Further, there is a description that the cationic strength of the cationic polymer flocculant II is preferably 3.5 or 5.0 meq / g or more, and in the example, a polyamine-based polymer flocculant is used.
特許文献２には、汚泥の脱水方法として、汚泥と高分子量のカチオン系高分子凝集剤とを第１の処理槽内で緩速にて攪拌混合して汚泥を粗大フロック状に凝集させ、この粗大フロック状汚泥を重力脱水機に送って濃縮し、得られた濃縮汚泥と高カチオン度高分子凝集剤とを第２の処理槽内で十分攪拌混合することにより汚泥をさらに凝集させ、その後、この凝集汚泥を機械脱水機に供給して脱水する方法が記載されている。 In Patent Document 2, as a method for dehydrating sludge, sludge and a high-molecular-weight cationic polymer flocculant are stirred and mixed at a slow speed in a first treatment tank to aggregate the sludge into coarse flocs. Coarse flock-like sludge is sent to a gravity dehydrator to concentrate, and the obtained concentrated sludge and a high cationic polymer flocculant are sufficiently stirred and mixed in a second treatment tank to further agglomerate the sludge, and then the sludge is further aggregated. A method of supplying this coagulated sludge to a mechanical dehydrator to dehydrate it is described.
特許文献３には、汚泥脱水方法及び装置について、汚泥に第１の凝集剤を添加して凝集を行い１次凝集フロックを生成させる１次凝集工程と、１次凝集フロックを脱水して１次脱水ケーキを得る１次脱水工程と、１次脱水ケーキにディスパーションまたはエマルション状態の高分子凝集剤からなる第２の凝集剤を添加して凝集を行い２次凝集フロックを生成させる２次凝集工程と、２次凝集フロックを脱水する２次脱水工程とを含む方法及び装置が記載されている。 Patent Document 3 describes a sludge dewatering method and an apparatus for a primary coagulation step in which a first coagulant is added to sludge to coagulate and generate a primary coagulation floc, and a primary coagulation floc is dehydrated to produce a primary coagulation floc. A primary dehydration step of obtaining a dehydrated cake, and a secondary flocculation step of adding a second flocculant composed of a dispersion or emulsion polymer flocculant to the primary dehydrated cake to coagulate and generate a secondary coagulation floc. And a method and apparatus including a secondary dehydration step of dehydrating the secondary aggregated floc.
特許文献４には、有機性汚泥の脱水方法について、有機性汚泥にカチオン系有機高分子凝集剤を添加して混合及びフロック形成した後、重力濃縮した凝集汚泥に鉄塩を添加し、その後、加圧脱水する方法が記載されている。 Patent Document 4 describes a method for dehydrating organic sludge by adding a cationic organic polymer flocculant to organic sludge to mix and form flocs, and then adding an iron salt to the gravity-concentrated coagulated sludge. A method of pressure dehydration is described.
特許文献５には、有機性汚泥の脱水方法及び装置について、有機性汚泥に高分子凝集剤を添加し、凝集汚泥を形成する凝集工程と、凝集汚泥を加圧することにより凝集汚泥を圧搾して脱水する凝集汚泥加圧脱水工程と、凝集汚泥加圧脱水工程で形成された脱水ケーキに無機凝集剤を添加する無機凝集剤添加工程と、無機凝集剤が添加された脱水ケーキを機械脱水する機械脱水工程により行う方法及び凝集汚泥加圧脱水工程で用いる汚泥圧搾機について記載されている。 Patent Document 5 describes a method and apparatus for dehydrating organic sludge by adding a polymer flocculant to organic sludge to form agglomerated sludge and pressurizing the coagulated sludge to squeeze the coagulated sludge. A machine for mechanically dehydrating a dewatered cake to which an inorganic coagulant has been added, and a step of adding an inorganic coagulant to the dewatered cake formed in the coagulated sludge pressure dehydration step for dehydration, and a dewatering cake to which the inorganic coagulant has been added. The method performed by the dewatering step and the sludge squeezing machine used in the coagulated sludge pressurized dewatering step are described.
非特許文献１では、有機性汚泥の脱水方法と脱水後の汚泥性状について、し尿施設の濃縮汚泥に造粒槽でポリマを添加する工程と、凝集汚泥のベルトプレス脱水機による第一脱水工程と、脱水汚泥にポリマ（有機凝結剤、キトサンなど）を添加する工程と、ポリマ添加汚泥のスクリュープレス脱水機（スチーム熱を加えた脱水）による第二脱水工程とを有す汚泥脱水方法、及び脱水ケーキの汚泥含水率が６５ｗｔ％以下になるといった脱水後の汚泥性状が記載されている。 In Non-Patent Document 1, the method of dehydrating organic sludge and the properties of sludge after dehydration are described in a step of adding a polymer to the concentrated sludge of a urine facility in a granulation tank and a first dehydration step of agglomerated sludge using a belt press dehydrator. , A sludge dewatering method having a step of adding a polymer (organic coagulant, chitosan, etc.) to the dewatered sludge and a second dewatering step of the sludge added sludge by a screw press dewatering machine (dewatering by applying steam heat), and dewatering. The sludge properties after dehydration, such as the sludge moisture content of the cake being 65 wt% or less, are described.
しかし、特許文献１は含水率低減効果のみを目的としており、スケール発生の防止については何ら考慮、対策は講じられていない。また、有機凝結剤についても明記されておらず、粘度、分子量、希釈液とする工程および希釈倍率についての諸条件は記載していない。 However, Patent Document 1 aims only at the effect of reducing the water content, and no consideration is given to the prevention of scale generation and no measures are taken. In addition, the organic coagulant is not specified, and various conditions regarding viscosity, molecular weight, step of making a diluted solution, and dilution ratio are not described.
特許文献２では、脱水機等の腐食による装置の短命化防止を目的としており、含水率低減効果と石膏スケール生成抑制効果を目的とするものではない。 Patent Document 2 aims to prevent a device from shortening its life due to corrosion of a dehydrator or the like, and does not aim to reduce the water content and suppress the formation of gypsum scale.
特許文献３では、脱水ケーキの低含水率化と高いＳＳ回収率を目的としており、石膏スケール抑制効果を目的とするものではない。 Patent Document 3 aims at lowering the water content of the dehydrated cake and high SS recovery rate, and does not aim at the effect of suppressing gypsum scale.
特許文献４では、無機系の凝集剤（鉄塩）を凝集汚泥に添加について記載しているに過ぎず、濃縮後の汚泥に有機凝結剤を添加することについては開示されていない。 Patent Document 4 merely describes the addition of an inorganic coagulant (iron salt) to the coagulated sludge, and does not disclose the addition of an organic coagulant to the concentrated sludge.
特許文献５では、無機系の凝集剤を使用することで、石膏スケール生成の可能性がある。 In Patent Document 5, there is a possibility of producing gypsum scale by using an inorganic flocculant.
非特許文献１では、脱水ケーキの低含水率化を目的としており、石膏スケール生成抑制効果は考慮されていない。また、機械脱水はスクリュープレス脱水機（一部スチール熱を利用）とベルトプレス脱水機でのみ検討を行っており、他の機械脱水方法及び装置や遠心脱水方法及び装置については考慮されていない。 Non-Patent Document 1 aims to reduce the water content of the dehydrated cake, and does not consider the effect of suppressing the formation of gypsum scale. In addition, mechanical dehydration is being studied only with a screw press dehydrator (partially using steel heat) and a belt press dehydrator, and other mechanical dehydration methods and devices and centrifugal dehydration methods and devices are not considered.
このように、従来技術では、有機性汚泥に高分子凝集剤や脱水助剤を添加することで、汚泥含水率低減効果、脱水機などの腐食防止効果、高いＳＳ回収率を目的としている。しかし、特に無機凝集剤を添加する脱水方法では、汚泥中の溶解性カルシウム濃度や硫酸イオン濃度が高くなるため、脱水機内や周辺の配管などに、石膏スケールの生成される問題点があった。石膏スケールが生成された場合、除去や洗浄が必要となる。従来の方法では上記のように、スケール生成の抑制を単独、または脱水ケーキ含水率低減効果とスケール生成の抑制を同時に達成できる有機性汚泥の脱水方法は報告されていなかった。 As described above, in the prior art, by adding a polymer flocculant or a dehydration aid to organic sludge, it is aimed at the effect of reducing the water content of sludge, the effect of preventing corrosion of dehydrators and the like, and the high SS recovery rate. However, especially in the dehydration method in which an inorganic flocculant is added, the concentration of soluble calcium and the concentration of sulfate ions in sludge are high, so that there is a problem that gypsum scale is generated in the dehydrator and in the surrounding piping. If gypsum scale is produced, it needs to be removed and cleaned. As described above, no method for dehydrating organic sludge has been reported in the conventional method, which can achieve the suppression of scale formation alone or the effect of reducing the water content of the dehydrated cake and the suppression of scale formation at the same time.
本発明では、脱水ケーキの含水率低減効果と石膏スケール生成抑制効果の両方を達成することを目的としている。 An object of the present invention is to achieve both the effect of reducing the water content of the dehydrated cake and the effect of suppressing the formation of gypsum scale.
また、本発明では、本脱水方法に最適な有機凝結剤の物性、使用方法や、本脱水方法に使用可能な有機凝結剤についても検討している。
従って、本発明の目的は、汚泥含水率低減と廃棄物量削減を図りつつ、上記の問題点を克服可能な脱水方法及び装置、有機凝結剤を提供することにある。
Further, in the present invention, the physical characteristics and usage method of the organic coagulant most suitable for the present dehydration method, and the organic coagulant that can be used for the present dehydration method are also studied.
Therefore, an object of the present invention is to provide a dehydration method, an apparatus, and an organic coagulant capable of overcoming the above problems while reducing the sludge water content and the amount of waste.
上記課題を解決するために、本発明は以下の構成とすることができる。 In order to solve the above problems, the present invention can have the following configuration.
（１）本発明は汚泥性状を有する有機性汚泥の脱水方法に関し、この有機性汚泥に高分子凝集剤を添加した後、有機性汚泥に有機凝結剤を添加する工程を有する。この有機凝結剤としては、少なくともカルシウムから選択される金属類の濃度が２００ｍｇ/Ｌ以下、硫酸イオン濃度が２００ｍｇ／Ｌ以下であって、かつ、ｐＨ４におけるカチオン度が５ｍｅｑ/ｇ以上のものを用いる。有機凝結剤を添加した後の有機性汚泥は機械的に脱水して脱水ケーキを得る。 (1) The present invention relates to a method for dehydrating organic sludge having sludge properties, and includes a step of adding a polymer flocculant to the organic sludge and then adding an organic coagulant to the organic sludge. As this organic coagulant, those having a concentration of at least metals selected from calcium of 200 mg / L or less, a sulfate ion concentration of 200 mg / L or less, and a cation degree at pH 4 of 5 meq / g or more are used. .. The organic sludge after adding the organic coagulant is mechanically dehydrated to obtain a dehydrated cake.
（２）有機性汚泥、高分子凝集剤及び有機凝結剤を同一の遠心脱水機に注入し、機械的に脱水することも可能である。 (2) It is also possible to inject organic sludge, a polymer flocculant and an organic coagulant into the same centrifugal dehydrator and mechanically dehydrate them.
（３）高分子凝集剤を添加する前の有機性汚泥を基準とし、この有機性汚泥のＴＳに対して０．１質量％〜３．０質量％の前記有機凝結剤を添加することが好ましい。 (3) Based on the organic sludge before the addition of the polymer flocculant, it is preferable to add 0.1% by mass to 3.0% by mass of the organic coagulant to the TS of the organic sludge. ..
（４）２５℃における原液の粘度が５０ｍＰａ・ｓ以上の液状の有機凝結剤を使用することが好ましい。 (4) It is preferable to use a liquid organic coagulant having a viscosity of the stock solution at 25 ° C. of 50 mPa · s or more.
（５）有機凝結剤は無希釈で使用してもよいし、希釈倍率６０倍以下に希釈した溶液として添加することもできる。 (5) The organic coagulant may be used undiluted, or may be added as a solution diluted at a dilution ratio of 60 times or less.
（６）本発明は有機性汚泥の脱水に用いられる有機凝結剤も提供するものであって、この有機凝結剤は少なくともカルシウムから選択される金属類の濃度が２００ｍｇ/Ｌ以下、硫酸イオン濃度が２００ｍｇ／Ｌ以下であって、かつ、ｐＨ４におけるカチオン度が５ｍｅｑ/ｇ以上、２５℃における原液の粘度が５０ｍＰａ・ｓ以上である。 (6) The present invention also provides an organic coagulant used for dehydrating organic sludge, and this organic coagulant has at least a concentration of metals selected from calcium of 200 mg / L or less and a sulfate ion concentration of 200 mg / L or less. It is 200 mg / L or less, the cation degree at pH 4 is 5 meq / g or more, and the viscosity of the stock solution at 25 ° C. is 50 mPa · s or more.
（７）本発明は、更に、有機性汚泥の処理装置にも関し、この処理装置は有機性汚泥に高分子凝集剤を添加する凝集剤供給手段と、高分子凝集剤により凝集した前記有機性汚泥を濃縮し、濃縮汚泥を得る濃縮手段と、濃縮汚泥に、少なくともカルシウムから選択される金属類の濃度が２００ｍｇ/Ｌ以下、硫酸イオン濃度が２００ｍｇ／Ｌ以下であって、かつ、ｐＨ４におけるカチオン度が５ｍｅｑ/ｇ以上の有機凝結剤を添加する凝結剤供給手段と、有機凝結剤を添加後の濃縮汚泥が供給され、機械脱水により脱水ケーキを得る脱水手段とを有する。濃縮汚泥に、有機凝結剤を添加することにより、機械脱水で発生する石膏スケールの生成を低減することが可能となる。 (7) The present invention further relates to an organic sludge treatment apparatus, which comprises an agent supply means for adding a polymer flocculant to organic sludge and the organic sludge aggregated by the polymer flocculant. Concentration means for concentrating sludge to obtain concentrated sludge, and in the concentrated sludge, the concentration of metals selected from at least calcium is 200 mg / L or less, the sulfate ion concentration is 200 mg / L or less, and the cation at pH 4 It has a coagulant supply means for adding an organic coagulant having a degree of 5 meq / g or more, and a dehydration means for supplying concentrated sludge after adding the organic coagulant to obtain a dehydrated cake by mechanical dehydration. By adding an organic coagulant to the concentrated sludge, it is possible to reduce the formation of gypsum scale generated by mechanical dehydration.
（８）本発明に係る他の処理装置は、遠心脱水機を具備する脱水手段と、汚泥性状を有する有機性汚泥を前記脱水手段へ供給する汚泥供給手段と、高分子凝集剤を脱水手段へ供給する凝集剤供給手段と、高分子凝集剤が添加された有機性汚泥に、有機凝結剤を添加する凝結剤供給手段とを有する。この有機凝結剤は、少なくともカルシウムから選択される金属類の濃度が２００ｍｇ/Ｌ以下、硫酸イオン濃度が２００ｍｇ／Ｌ以下であって、かつ、ｐＨ４におけるカチオン度が５ｍｅｑ/ｇ以上である。脱水手段は、有機性汚泥を高分子凝集剤で凝集すると共に濃縮し、更に有機凝結剤を浸透させて脱水する。 (8) The other processing apparatus according to the present invention includes a dehydration means provided with a centrifugal dehydrator, a sludge supply means for supplying organic sludge having sludge properties to the dehydration means, and a polymer flocculant to the dehydration means. It has a coagulant supply means for supplying and a coagulant supply means for adding an organic coagulant to the organic sludge to which the polymer coagulant is added. This organic coagulant has a concentration of metals selected from at least calcium of 200 mg / L or less, a sulfate ion concentration of 200 mg / L or less, and a cation degree at pH 4 of 5 meq / g or more. In the dehydration means, the organic sludge is agglomerated and concentrated with a polymer flocculant, and further permeated with an organic coagulant to dehydrate.
本発明によれば、汚泥含水率の低減と廃棄物量の削減を図りつつ、石膏スケール生成の防止といった特有の効果を得ることが可能である。 According to the present invention, it is possible to obtain a peculiar effect such as prevention of gypsum scale formation while reducing the sludge water content and the amount of waste.
以下、本発明を具体的に説明するが、本発明は特定の具体例に限定されるものではない。 Hereinafter, the present invention will be specifically described, but the present invention is not limited to a specific specific example.
図１は、本発明の概略を説明するための図面であり、本発明は、有機性汚泥の高分子凝集剤を添加する工程と、有機凝結剤を添加する工程とを有し、高分子凝集剤及び有機凝結剤が添加された汚泥は脱水され、脱水汚泥（脱水ケーキ）が排出される。以下に詳細に説明する。 FIG. 1 is a drawing for explaining the outline of the present invention. The present invention has a step of adding a polymer flocculant of organic sludge and a step of adding an organic coagulant, and the present invention has a step of adding a polymer flocculant. The sludge to which the agent and the organic coagulant are added is dehydrated, and the dehydrated sludge (dehydrated cake) is discharged. This will be described in detail below.
[有機性汚泥]
有機性汚泥は、下水処理、し尿処理、各種産業廃水処理などにおいて発生する有機性汚泥である。例えば、最初沈澱池汚泥、余剰汚泥、嫌気性消化汚泥、好気性消化汚泥、浄化槽汚泥、生し尿を含むし尿系汚泥などを挙げることができる。これら汚泥は１種のみを単独で処理してもよいし、２種以上の汚泥を混合して処理してもよい。これら有機性汚泥は無機物を含んでも良い。
[Organic sludge]
Organic sludge is organic sludge generated in sewage treatment, urine treatment, various industrial wastewater treatments, and the like. For example, first settling pond sludge, surplus sludge, anaerobic digestion sludge, aerobic digestion sludge, septic tank sludge, human waste including raw urine, and the like can be mentioned. Only one type of sludge may be treated alone, or two or more types of sludge may be mixed and treated. These organic sludges may contain inorganic substances.
有機性汚泥は、溶解性カルシウム濃度範囲が１０ｍｇ／Ｌ〜２００ｍｇ／Ｌのものが好ましく、より好ましくは１０ｍｇ／Ｌ〜１５０ｍｇ／Ｌ、さらに好ましくは１０ｍｇ／Ｌ〜１００ｍｇ／Ｌ、特に好ましくは２０〜８０ｍｇ／Ｌである。有機性汚泥の硫酸イオン濃度範囲は好ましくは０．１ｍｇ／Ｌ〜２００ｍｇ／Ｌであり、より好ましくは０．１ｍｇ／Ｌ〜１５０ｍｇ／Ｌ、特に好ましくは０．５〜１２０ｍｇ／Ｌである。 The organic sludge preferably has a soluble calcium concentration range of 10 mg / L to 200 mg / L, more preferably 10 mg / L to 150 mg / L, still more preferably 10 mg / L to 100 mg / L, and particularly preferably 20 to 20 to L. It is 80 mg / L. The sulfate ion concentration range of the organic sludge is preferably 0.1 mg / L to 200 mg / L, more preferably 0.1 mg / L to 150 mg / L, and particularly preferably 0.5 to 120 mg / L.
有機性汚泥の溶解性カルシウム濃度と硫酸イオン濃度の少なくとも一方が上記好適範囲内であれば、汚泥中の溶解性カルシウムに由来する石膏スケールの生成が効果的に抑制される。 When at least one of the soluble calcium concentration and the sulfate ion concentration of the organic sludge is within the above-mentioned preferable range, the formation of gypsum scale derived from the soluble calcium in the sludge is effectively suppressed.
有機性汚泥は、通常、ｐＨ６〜８、カルシウム濃度が１００ｍｇ/Ｌ〜４００ｍｇ/Ｌ、例えば１００ｍｇ/Ｌ〜３５０ｍｇ/Ｌという特徴を有している。溶解性カルシウム濃度と硫酸イオン濃度の少なくとも一方が上記好適濃度範囲を超える高濃度汚泥を処理する場合、水と、低濃度汚泥と、低濃度排水から選択される１種以上の希釈媒体を添加してもよい。「低濃度」とは、カルシウム濃度と硫酸イオン濃度の少なくとも一方が上記好適濃度の上限値よりも低い意味である。例えば、低濃度汚泥と高濃度汚泥の混合汚泥を有機性汚泥として処理することもできる。 Organic sludge is usually characterized by a pH of 6 to 8 and a calcium concentration of 100 mg / L to 400 mg / L, for example 100 mg / L to 350 mg / L. When treating high-concentration sludge in which at least one of the soluble calcium concentration and the sulfate ion concentration exceeds the above-mentioned preferable concentration range, water, low-concentration sludge, and one or more dilution media selected from low-concentration wastewater are added. You may. "Low concentration" means that at least one of the calcium concentration and the sulfate ion concentration is lower than the upper limit of the above-mentioned suitable concentration. For example, a mixed sludge of low-concentration sludge and high-concentration sludge can be treated as organic sludge.
溶解性カルシウム濃度と硫酸イオン濃度は、水溶性の塩として存在し、汚泥中に溶解してイオン化（Ｃａ２＋、ＳＯ４ ２−）して存在する濃度のことであって、溶解性カルシウム濃度と硫酸イオン濃度は、それぞれ実施例で後述するＩＣＰ発光分光分析法、イオンクロマトグラフ法により測定可能である。 Soluble calcium concentration and sulfate ion concentration are present as water-soluble salts, ionized and dissolved in the sludge (Ca 2+, SO 4 2-) the method comprising the concentration present in the solubility of calcium concentration and The sulfate ion concentration can be measured by the ICP emission spectroscopic analysis method and the ion chromatograph method, which will be described later in Examples, respectively.
[有機凝結剤]
有機凝結剤とは、広義では高分子凝集剤に分類されるが、高分子凝集剤と分類される薬剤と比較すると、低分子であり、高カチオン度を有する。具体的には、有機凝結剤の分子量は数百万以下であり、より具体的には分子量が１５０万以下であり、好ましくは分子量１００万以下、より好ましくは分子量５０万以下、特に好ましくは分子量１０万以下である。分子量の下限は例えば１０００以上であり、好ましくは５０００以上、より好ましくは１万以上であり、更に好ましくは２万以上、特に好ましくは３万以上である。
[Organic coagulant]
The organic coagulant is broadly classified as a polymer flocculant, but is a small molecule and has a high degree of cation as compared with a drug classified as a polymer flocculant. Specifically, the molecular weight of the organic coagulant is several million or less, more specifically, the molecular weight is 1.5 million or less, preferably 1 million or less, more preferably 500,000 or less, and particularly preferably the molecular weight. It is 100,000 or less. The lower limit of the molecular weight is, for example, 1000 or more, preferably 5000 or more, more preferably 10,000 or more, still more preferably 20,000 or more, and particularly preferably 30,000 or more.
ここでの分子量は、固有粘度（０．２Ｎ−ＮａＣｌ水溶液中２５℃での測定値、単位はｄｌ／ｇ）から換算して求められるもので、ポリアクリルアミド系高分子の粘度式：［η］＝３．０２×１０-4×（Ｍｗ）0.68［ポリマー凝集剤、（株）東京都下水道サービス刊、１１３頁］から（Ｍｗ）を便宜上求めることができる。 The molecular weight here is obtained by converting from the intrinsic viscosity (measured value at 25 ° C. in 0.2N-NaCl aqueous solution, unit is dl / g), and the viscosity formula of the polyacrylamide polymer: [η]. = 3.02 × 10 -4 × (Mw) 0.68 (Mw) can be obtained for convenience from [Polymer coagulant, published by Tokyo Metropolitan Sewerage Service Co., Ltd., p. 113].
また、有機凝結剤としては、粉体、液体のいずれも存在するが、いずれの場合も水溶液としたときの粘度が高分子凝集剤と比較して低く、有機凝結剤は通常液体である。これは、高分子凝集剤、ポリマ、低分子系カチオン凝集剤、有機凝結剤、有機凝集剤などと称されることがあるが、本明細書では、有機凝結剤とする。本発明に係る有機凝結剤は、有機性汚泥の脱水方法に用いられ、カチオン性であり、好ましくは室温（２７℃）で液状の物質である。 Further, as the organic coagulant, both powder and liquid exist, but in both cases, the viscosity when made into an aqueous solution is lower than that of the polymer flocculant, and the organic coagulant is usually a liquid. This may be referred to as a polymer flocculant, a polymer, a small molecule cationic flocculant, an organic coagulant, an organic coagulant, etc., but in the present specification, it is referred to as an organic coagulant. The organic coagulant according to the present invention is used in a method for dehydrating organic sludge, is cationic, and is preferably a liquid substance at room temperature (27 ° C.).
本脱水方法で使用する有機凝結剤としては、例えばポリアミン系、ジシアンジアミド系、ポリジシアンジアミド系、ポリジアリルジメチルアンモニウムクロライド系（「ポリＤＡＤＭＡＣ系」とも称する）、アミノ縮合系、メラミン酸コロイド系などから１種以上を選択して用いることができる。 Examples of the organic coagulant used in this dehydration method include polyamine type, dicyandiamide type, polydicyandiamide type, polydiallyldimethylammonium chloride type (also referred to as "polyDADMAC type"), amino condensation type, and melamine colloid type. More than a species can be selected and used.
より具体的には、ポリアルキルポリアミン、ポリエチレンイミン、ジアリルジメチルアンモニウムクロリド、エチレンジアミンエピクロルヒドリン重縮合物、メチロールメラミン酸コロイド、ジシアンジアミド・塩化アンモニウム・ホルムアルデヒド重縮合物、ポリエチレン・ポリアミン・ジメチルアミン・エピクロルヒドリン重縮合物、ジアルキルアミン・エピクロルヒドリン重縮合物（特にジメチルアミン・エピクロルヒドリン重縮合物）、ポリアリルアミン塩酸塩、ポリジアリルメチルアミン塩酸塩、ジアリルジメチルアンモニウムクロライドと二酸化イオウの共重合体、ジアリルジメチルアンモニウムクロライドとアクリルアミドの共重合体、ジアリルアミン塩酸塩と二酸化イオウとの共重合体などから１種以上を用いることができる。 More specifically, polyalkylpolyamine, polyethyleneimine, diallyldimethylammonium chloride, ethylenediamine epichlorohydrin polycondensate, methylolmelamic acid colloid, dicyandiamide / ammonium chloride / formaldehyde polycondensate, polyethylene / polyamine / dimethylamine / epichlorohydrin polycondensate. , Dialkylamine / epichlorohydrin polycondensate (especially dimethylamine / epichlorohydrin polycondensate), polyallylamine hydrochloride, polydiallylmethylamine hydrochloride, copolymer of diallyldimethylammonium chloride and sulfur dioxide, diallyldimethylammonium chloride and acrylamide One or more kinds can be used from a copolymer, a copolymer of diallylamine hydrochloride and sulfur dioxide, and the like.
しかし、本発明の有機凝結剤の濃度（混合物の場合は、混合物全体の濃度）は、金属類が２００ｍｇ/Ｌ以下、硫酸イオンが２００ｍｇ/Ｌ以下である必要があり、より好ましくは金属類濃度が１００ｍｇ/Ｌ以下、硫酸イオン濃度が１００ｍｇ/Ｌ以下である。従って、二酸化イオウの共重合体など、イオウ原子や金属類を含む有機凝結剤は使用しないか、使用する場合はその量を抑えるべきである。上記有機凝結剤の中でも、イオウ原子や金属類の含有量が極めて低く（コンタミネーションレベルでは存在するおそれはある）、汚泥脱水性が高いという点で、ポリアミン系、ポリＤＡＤＭＡＣ系、ポリジシアンジアミド系の有機凝結剤が好ましく、ポリアミン系の有機凝結剤が最も好ましい。 However, the concentration of the organic coagulant of the present invention (in the case of a mixture, the concentration of the entire mixture) needs to be 200 mg / L or less for metals and 200 mg / L or less for sulfate ions, and more preferably the concentration of metals. Is 100 mg / L or less, and the sulfate ion concentration is 100 mg / L or less. Therefore, organic coagulants containing sulfur atoms and metals, such as copolymers of sulfur dioxide, should not be used, or if used, their amounts should be suppressed. Among the above organic coagulants, polyamine-based, polyDADMAC-based, and polydicyandiamide-based ones have extremely low content of sulfur atoms and metals (may exist at the contamination level) and high sludge dehydration property. Organic coagulants are preferred, and polyamine-based organic coagulants are most preferred.
ここで、金属類とは少なくともＣａから選択される物質であり、すなわち、Ｃａ濃度が金属類の濃度が上記好適範囲（例：２００ｍｇ/Ｌ以下）の有機凝結剤であれば使用することができるが、好ましくは、Ｍｇなども含むアルカリ土類金属全体の濃度が上記好適範囲、より好ましくは、Ｃａなどのアルカリ土類金属に加え、Ｆｅ等の遷移金属、Ａｌ等の卑金属から構成される金属類の合計濃度が２００ｍｇ/Ｌ以下の有機凝結剤を用いる。 Here, the metals are substances selected from at least Ca, that is, any organic coagulant having a Ca concentration in the above preferable range (eg, 200 mg / L or less) can be used. However, preferably, the concentration of the entire alkaline earth metal including Mg and the like is in the above preferable range, and more preferably, a metal composed of a transition metal such as Fe and a base metal such as Al in addition to the alkaline earth metal such as Ca. Use an organic coagulant having a total concentration of 200 mg / L or less.
有機凝結剤の性状としては、高カチオン度（原液中の有機凝結剤成分換算値）であり、詳しくはｐＨ４における有機凝結剤の原液中の成分としてのカチオン度が５ｍｅｑ/ｇ以上が好ましく、より好ましくは７ｍｅｑ/ｇ以上、更に好ましくは１０ｍｅｑ/ｇ以上である。有機凝結剤の原液の粘度（回転粘度計、２５℃で測定）が５０ｍＰａ・ｓ以上が好ましく、１５０ｍＰａ・ｓ以上であればより好ましく、上限は特に限定されないが４０００ｍＰａ・ｓ以下が好ましい。 The properties of the organic coagulant are high cationism (converted value of the organic coagulant component in the undiluted solution), and more specifically, the cationity as a component in the undiluted solution of the organic coagulant at pH 4 is preferably 5 meq / g or more. It is preferably 7 meq / g or more, and more preferably 10 meq / g or more. The viscosity of the undiluted solution of the organic coagulant (rotational viscometer, measured at 25 ° C.) is preferably 50 mPa · s or more, more preferably 150 mPa · s or more, and the upper limit is not particularly limited, but 4000 mPa · s or less is preferable.
なお、ｐＨ４におけるカチオン度は以下の手順で測定することができる。高分子凝集剤または有機凝結剤を純水に溶解し、５００ｍｇ／Ｌの高分子凝集剤水溶液（成分換算）または有機凝結剤水溶液（原液中の成分換算）を調製した。次に９０ｍＬの純水と１０ｍＬの高分子凝集剤水溶液または有機凝結剤水溶液を混合し、０．１規定の塩酸水溶液でｐＨ４に調整した。これにトルイジンブルーを加え、１／４００規定のポリビニル硫酸カリウムで滴定した。滴定では、青色から赤紫色に変色して１５秒以上保持する時点を終点とした。カチオン度（コロイド当量値）は以下の式から計算した。
カチオン度（ｍｅｑ/ｇ）＝滴定量（ｍＬ）／２
The degree of cation at pH 4 can be measured by the following procedure. The polymer coagulant or the organic coagulant was dissolved in pure water to prepare a 500 mg / L polymer coagulant aqueous solution (component conversion) or an organic coagulant aqueous solution (component conversion in the stock solution). Next, 90 mL of pure water was mixed with 10 mL of a polymer coagulant aqueous solution or an organic coagulant aqueous solution, and the pH was adjusted to 4 with a 0.1N hydrochloric acid aqueous solution. Toluidine blue was added thereto, and the mixture was titrated with 1/400 standard potassium polyvinyl sulfate. In the titration, the end point was the time when the color changed from blue to magenta and held for 15 seconds or longer. The degree of cation (colloid equivalent value) was calculated from the following formula.
Cationicity (meq / g) = titration (mL) / 2
有機凝結剤は、無希釈の原液での使用も可能である。ここで「原液」とは、例えば「有機凝結剤」として流通可能な液状製品（例：水溶液）のことであって、有機凝結剤成分（有機凝結剤として説明した上記化合物）に加え、水などの溶媒や任意の添加剤を含む場合もあり、具体的には有機凝結剤成分の含有量が１０質量％以上、好ましくは２０質量％以上、より好ましくは３０質量％以上であり、その含有量上限は例えば９０質量％、好ましくは７０質量％以下、より好ましくは５０質量％以下である。このような原液で使用した場合の脱水効果は高いが、粘度を低下させて脱水ケーキ内に含浸及び分散させやすくすると共に、希釈することにより容量を増やして均一分散させやすくする観点から、希釈液（水）で希釈後に、脱水ケーキに添加することが好ましい。ただし、希釈倍率が６０倍を超えると、希釈液中の水分量が増えるため、脱水ケーキの水分量を増加させてしまう。 The organic coagulant can also be used in an undiluted stock solution. Here, the "undiluted solution" is, for example, a liquid product (eg, an aqueous solution) that can be distributed as an "organic coagulant", and in addition to an organic coagulant component (the above compound described as an organic coagulant), water or the like. The content of the organic coagulant component is 10% by mass or more, preferably 20% by mass or more, more preferably 30% by mass or more, and the content thereof. The upper limit is, for example, 90% by mass, preferably 70% by mass or less, and more preferably 50% by mass or less. Although the dehydration effect is high when used in such a stock solution, it is a diluted solution from the viewpoint of lowering the viscosity to facilitate impregnation and dispersion in the dehydrated cake, and increasing the volume by diluting to facilitate uniform dispersion. It is preferable to add it to the dehydrated cake after diluting it with (water). However, if the dilution ratio exceeds 60 times, the amount of water in the diluted solution increases, which increases the amount of water in the dehydrated cake.
上記観点から、有機凝結剤の原液の希釈倍率は２〜６０倍（質量比）が好ましい。より好ましい希釈倍率は５〜５０倍である。希釈液（溶媒）には、水を主成分（５０質量％以上）とし、好ましくは水を９０質量％以上、より好ましくは９５質量％以上、特に好ましくは９９質量％水を含み、特に実質的に水からなるものを用いる。具体的には、純水、水道水、工業用水、地下水、各種廃水処理の処理水、海水などが使用できるが、経済的な観点からは、工業用水、地下水、各種廃水処理の処理水が好ましい。 From the above viewpoint, the dilution ratio of the stock solution of the organic coagulant is preferably 2 to 60 times (mass ratio). A more preferable dilution ratio is 5 to 50 times. The diluent (solvent) contains water as a main component (50% by mass or more), preferably 90% by mass or more, more preferably 95% by mass or more, and particularly preferably 99% by mass or more of water, particularly substantially. Use a solvent consisting of water. Specifically, pure water, tap water, industrial water, groundwater, treated water for various wastewater treatments, seawater, etc. can be used, but from an economic point of view, industrial water, groundwater, and treated water for various wastewater treatments are preferable. ..
このように、希釈液は特に限定されないが、希釈液の金属類濃度や硫酸イオン濃度が高いと、結果的に有機凝結剤溶液の金属類濃度、硫酸イオン濃度が高くなってしまうので、希釈液の金属類イオン濃度と硫酸イオン濃度はそれぞれ２００ｍｇ/Ｌ以下が好ましく、より好ましくは１００ｍｇ/Ｌ以下であり、最も好ましくは５０ｍｇ／Ｌ以下である。従って、これら濃度の観点から、好ましくは希釈液には硬水を使用せず、いわゆる軟水（硬度１００ｍｇ/Ｌ以下）に相当する水道水、純水などを使用する。金属類と硫酸イオンの少なくとも一方の濃度が高い地下水などを用いる場合は、上記軟水などと混合して希釈液とすることもできる。 As described above, the diluent is not particularly limited, but if the metal concentration and the sulfate ion concentration of the diluent are high, the metal concentration and the sulfate ion concentration of the organic coagulant solution will be high as a result. The metal ion concentration and the sulfate ion concentration of the above are preferably 200 mg / L or less, more preferably 100 mg / L or less, and most preferably 50 mg / L or less. Therefore, from the viewpoint of these concentrations, it is preferable not to use hard water as the diluent, but to use tap water, pure water or the like corresponding to so-called soft water (hardness 100 mg / L or less). When groundwater or the like having a high concentration of at least one of metals and sulfate ions is used, it can be mixed with the above-mentioned soft water or the like to prepare a diluted solution.
有機凝結剤を希釈する場合も希釈しない場合も、有機凝結剤（液状の場合は原液、紛体の場合は固形分）の添加量を、有機性汚泥のＴＳに対して０．１質量％以上（有機凝結剤の質量％は、有機凝結剤の原液換算）にすることで、脱水効果を高めることができる。他方、有機性汚泥のＴＳに対する添加量が３．０質量％を超えても、有機凝結剤の無駄である。よって、かかる観点から、有機凝結剤の添加量は、有機性汚泥のＴＳに対して０．１〜３．０質量％で添加するのが好ましく、中でも０．５質量％以上或いは２．５質量％以下、その中でも０．６質量％以上或いは２．０質量％以下の割合で添加するのがより一層好ましい。 Regardless of whether the organic coagulant is diluted or not, the amount of the organic coagulant (stock solution in the case of liquid, solid content in the case of powder) is 0.1% by mass or more (0.1% by mass or more) with respect to the TS of the organic sludge. The dehydration effect can be enhanced by setting the mass% of the organic coagulant to the stock solution equivalent of the organic coagulant). On the other hand, even if the amount of organic sludge added to TS exceeds 3.0% by mass, the organic coagulant is wasted. Therefore, from this point of view, the amount of the organic coagulant added is preferably 0.1 to 3.0% by mass with respect to the TS of the organic sludge, particularly 0.5% by mass or more or 2.5% by mass. % Or less, more preferably 0.6% by mass or more or 2.0% by mass or less.
[高分子凝集剤]
高分子凝集剤としてはカチオン性基を含有する物であれば特に限定されず、カチオン性高分子凝集剤、両性高分子凝集剤の一方又は両方を用いることができる。カチオン性基を含有する高分子凝集剤、特にカチオン性高分子凝集剤と共に、アニオン性高分子凝集剤とノニオン性高分子凝集剤の一方又は両方を併用することも可能である。
[Polymer flocculant]
The polymer flocculant is not particularly limited as long as it contains a cationic group, and one or both of the cationic polymer flocculant and the amphoteric polymer flocculant can be used. It is also possible to use one or both of the anionic polymer flocculant and the nonionic polymer flocculant together with the polymer flocculant containing a cationic group, particularly the cationic polymer flocculant.
いずれの場合も、本発明には、カチオン度が有機凝結剤よりも低い高分子凝集剤を用いることが好ましい。高分子凝集剤のカチオン度は、有機凝結剤と同様の方法で測定することが可能である。高分子凝集剤を２種以上使用する場合は、各高分子凝集剤のカチオン度と質量比とから算出した値を、高分子凝集剤全体のカチオン度と推定することもできる。 In either case, it is preferable to use a polymer flocculant having a cation content lower than that of the organic coagulant in the present invention. The cationicity of the polymer flocculant can be measured in the same manner as the organic coagulant. When two or more kinds of polymer flocculants are used, the value calculated from the cation degree and the mass ratio of each polymer flocculant can be estimated as the cation degree of the entire polymer flocculant.
カチオン性高分子凝集剤としては、例えばアクリレート系高分子凝集剤（「ＤＡＡ系高分子凝集剤」とも称する）、メタクリレート系高分子凝集剤（「ＤＡＭ系高分子凝集剤」とも称する）、アミド基、ニトリル基、アミン塩酸基、ホルムアルデヒド基などを含むポリビニルアミジン（「アミジン系高分子凝集剤」とも称する）、ポリアクリルアミドのマンニッヒ変性物などが挙げることができる。 Examples of the cationic polymer flocculant include an acrylate-based polymer flocculant (also referred to as "DAA-based polymer flocculant"), a methacrylate-based polymer flocculant (also referred to as "DAM-based polymer flocculant"), and an amide group. , Polyvinylamidine containing a nitrile group, an amine hydrochloric acid group, a formaldehyde group, etc. (also referred to as an "amidine-based polymer flocculant"), a Mannig modified product of polyacrylamide, and the like can be mentioned.
両性高分子凝集剤は、一般に、（メタ）アクリル酸エステル系などのカチオン性モノマーと、アクリル酸等のアニオン性モノマーとの共重合体であって、アクリルアミドなどのノニオン性モノマーを更に共重合させる場合もある。具体的には、ジメチルアミノエチルアクリレート４級アンモニウム塩とアクリルアミドとアクリル酸との共重合物、ジメチルアミノエチルメタクリレート４級アンモニウム塩とアクリルアミドとアクリル酸との共重合物、ジメチルアミノエチルアクリレート４級アンモニウム塩とジメチルアミノエチルメタクリレート4級アンモニウム塩とアクリルアミドとアクリル酸との共重合物などを挙げることができる。 The amphoteric polymer flocculant is generally a copolymer of a cationic monomer such as (meth) acrylic acid ester and an anionic monomer such as acrylic acid, and further copolymerizes a nonionic monomer such as acrylamide. In some cases. Specifically, a copolymer of dimethylaminoethyl acrylate quaternary ammonium salt, acrylamide and acrylic acid, a copolymer of dimethylaminoethyl methacrylate quaternary ammonium salt and acrylamide and acrylic acid, and dimethylaminoethyl acrylate quaternary ammonium. Examples thereof include a salt, a quaternary ammonium salt of dimethylaminoethyl methacrylate, and a copolymer of acrylamide and acrylic acid.
高分子凝集剤の分子量は特に限定されないが、少なくとも有機凝結剤よりは高分子量のものを用いることが好ましい。例えば、分子量は数百万以上、具体的には２００万以上、好ましくは２５０万を超え、より好ましくは３００万以上、特に好ましくは５００万以上である。この分子量も、有機凝結剤と同様、固有粘度から換算して求めることができる。 The molecular weight of the polymer flocculant is not particularly limited, but it is preferable to use at least a polymer coagulant having a higher molecular weight than the organic coagulant. For example, the molecular weight is several million or more, specifically 2 million or more, preferably more than 2.5 million, more preferably 3 million or more, and particularly preferably 5 million or more. Similar to the organic coagulant, this molecular weight can also be obtained by converting from the intrinsic viscosity.
高分子凝集剤はそのまま用いてもよいが、有機性汚泥への分散性を高めるためには、溶媒に分散又は溶解した高分子凝集剤の溶液を用いることが好ましい。この溶媒は、上記有機凝結剤の希釈液と同様の溶媒、例えば、純水、水道水、工業用水、地下水、各種廃水処理の処理水、海水などをあげることができるが、高分子凝集剤の効果を最大限発揮させる観点からは純水が望ましい。一方、経済性の観点からは水道水、工業用水、地下水、各種廃水処理の処理水が望ましい。 The polymer flocculant may be used as it is, but in order to enhance the dispersibility in organic sludge, it is preferable to use a solution of the polymer flocculant dispersed or dissolved in a solvent. The solvent may be the same solvent as the diluted solution of the organic coagulant, for example, pure water, tap water, industrial water, groundwater, treated water for various wastewater treatments, seawater, etc. Pure water is desirable from the viewpoint of maximizing the effect. On the other hand, from the viewpoint of economy, tap water, industrial water, groundwater, and treated water for various wastewater treatments are desirable.
高分子凝集剤は、有機性汚泥のＴＳに対して０．３質量％以上（高分子凝集剤の質量％は、高分子凝集剤の成分換算）添加すれば、脱水効果を高めることができる一方、３．５質量％を超えて添加しても高分子凝集剤の無駄である。よって、かかる観点から高分子凝集剤の添加量（溶媒除く）は、有機性汚泥のＴＳに対して０．３〜３．５質量％で添加することが望ましく、中でも０．４質量％以上あるいは３．０質量％以下の割合で添加するのが一層好ましい。なお、ＴＳ（Ｔｏｔａｌ ｓｏｌｉｄ）は残留蒸発物のことであり、有機性汚泥を１０５℃〜１１０℃で蒸発乾固した後に残留した物質の質量を、蒸発乾固前の汚泥質量で除して１００を乗じた値である（単位は％）。ＴＳの測定には、本発明により処理する前の有機性汚泥を用いる。 The dehydration effect can be enhanced by adding 0.3% by mass or more of the polymer flocculant to the TS of the organic sludge (mass% of the polymer flocculant is converted into a component of the polymer flocculant). , Even if it is added in excess of 3.5% by mass, the polymer flocculant is wasted. Therefore, from this point of view, it is desirable that the amount of the polymer flocculant added (excluding the solvent) is 0.3 to 3.5% by mass with respect to the TS of the organic sludge, particularly 0.4% by mass or more or It is more preferable to add in a proportion of 3.0% by mass or less. TS (Total solid) is a residual evaporative substance, and the mass of the substance remaining after evaporating and drying organic sludge at 105 ° C to 110 ° C is divided by the mass of sludge before evaporating and drying to 100. It is the value multiplied by (unit is%). For the measurement of TS, organic sludge before treatment according to the present invention is used.
次に、第１例、第２例の脱水方法を、それに用いる処理装置と共に説明するが、本発明はこれに限定されるものではない。 Next, the dehydration methods of the first example and the second example will be described together with the processing apparatus used therein, but the present invention is not limited thereto.
[第１例の脱水方法]
図２の符号１ａは第１例の脱水方法で用いる処理装置の一例を示しており、この処理装置１ａは少なくとも高分子凝集剤を供給する凝集剤供給手段５ａと、有機凝結剤を供給する凝結剤供給手段７ａと、汚泥を脱水する脱水手段９ａとを有している。この処理装置１ａに送られた有機性汚泥は、先ず、凝集剤供給手段５ａの高分子凝集剤を用いた凝集工程に付される。
[First example dehydration method]
Reference numeral 1a in FIG. 2 indicates an example of a processing device used in the dehydration method of the first example, in which the processing device 1a includes at least a coagulant supply means 5a for supplying a polymer flocculant and a coagulation device for supplying an organic coagulant. It has an agent supply means 7a and a dehydration means 9a for dehydrating sludge. The organic sludge sent to the treatment apparatus 1a is first subjected to a coagulation step using the polymer coagulant of the coagulant supply means 5a.
- 凝集工程
凝集剤供給手段５ａは特に限定されないが、好ましくは混和槽１５を有しており、この混和槽１５に上記溶媒に分散又は溶解した混和状態の高分子凝集剤溶液を収容しておく。凝集剤供給手段５ａは、有機性汚泥を処理する凝集槽１１又はその前段に接続され、有機性汚泥には高分子凝集剤又はその溶液が添加される。
--Coagulation step The coagulant supply means 5a is not particularly limited, but preferably has a mixing tank 15, and the mixing tank 15 contains a polymer coagulant solution in a mixed state dispersed or dissolved in the above solvent. .. The coagulant supply means 5a is connected to the coagulation tank 11 for treating the organic sludge or its predecessor, and the polymer coagulant or a solution thereof is added to the organic sludge.
凝集剤供給手段５ａには流量調整手段などの制御手段を設置してもよく、予め有機性汚泥のＴＳを測定するか、有機性汚泥の情報（汚泥の出所、過去のＴＳ測定値等）からＴＳを予測しておき、このＴＳと、有機性汚泥の供給量に基づき、制御手段で高分子凝集剤の添加量を制御してもよい。 A control means such as a flow rate adjusting means may be installed in the coagulant supply means 5a, and the TS of the organic sludge may be measured in advance, or from the information of the organic sludge (sludge source, past TS measurement value, etc.). The TS may be predicted, and the amount of the polymer flocculant added may be controlled by the control means based on the TS and the supply amount of the organic sludge.
凝集槽１１に有機性汚泥を供給し、凝集剤供給手段５ａから供給した高分子凝集剤と、この有機性汚泥とを、凝集槽１１の撹拌手段で撹拌混合すると、有機性汚泥は高分子凝集剤により凝集して凝集フロックが形成される。すなわち、この処理装置１ａでは、凝集槽１１と混和槽１５とで凝集工程用の装置の一部又は全部が構成される。なお、有機性汚泥を凝集可能であれば、この凝集工程に用いる装置の構成、装置の形態、装置の数、装置の寸法、または、凝集に使用する水槽の数、水槽の構成、水槽の形態、装置の寸法、さらには凝集方法及び技術に関しては限定されない。 When organic sludge is supplied to the coagulation tank 11 and the polymer coagulant supplied from the coagulant supply means 5a and the organic sludge are stirred and mixed by the stirring means of the coagulation tank 11, the organic sludge is polymer agglomerated. The agent aggregates to form aggregated flocs. That is, in this processing device 1a, a part or all of the device for the coagulation step is configured by the coagulation tank 11 and the mixing tank 15. If organic sludge can be agglomerated, the configuration of the device, the form of the device, the number of devices, the dimensions of the device, or the number of water tanks used for coagulation, the structure of the water tank, the form of the water tank. There are no restrictions on the dimensions of the device, as well as the aggregation method and technique.
いずれの装置を用いた場合も、高分子凝集剤を用いた凝集処理により、最終的に得られる脱水ケーキの含水率を効果的に低減できると共に、後段の有機凝結剤の使用量を適正に調整することができる。 Regardless of which device is used, the water content of the finally obtained dehydrated cake can be effectively reduced by the coagulation treatment using the polymer coagulant, and the amount of the organic coagulant used in the subsequent stage can be adjusted appropriately. can do.
この処理装置１ａでは、好ましくは凝集槽１１の後段に濃縮手段６を設置し、凝集工程で得た凝集汚泥を濃縮して過剰な水分を除去する。次に、この濃縮工程について説明する。 In this processing apparatus 1a, preferably, the concentrating means 6 is installed after the coagulation tank 11, and the coagulated sludge obtained in the coagulation step is concentrated to remove excess water. Next, this concentration step will be described.
- 濃縮工程
濃縮手段６は、凝集汚泥を濃縮可能な装置であれば特に限定はされず、汚泥の濃縮脱水に用いられる装置、例えば、重力式濃縮機、機械式濃縮機の少なくとも一方を用いることが可能であり、具体的には、重力（沈降など）、重力ろ過、減圧ろ過、その他のろ過装置、ドラム型濃縮（脱水）装置、ベルトプレス式濃縮（脱水）装置、多重円盤型濃縮（脱水）装置、遠心脱水機などから１種以上を選択して用いることができる。
--Concentration step The concentrating means 6 is not particularly limited as long as it is an apparatus capable of concentrating coagulated sludge, and an apparatus used for concentrating and dehydrating sludge, for example, at least one of a gravity type concentrator and a mechanical concentrator is used. Specifically, gravity (settling, etc.), gravity filtration, vacuum filtration, other filtration equipment, drum type concentration (dehydration) equipment, belt press type concentration (dehydration) equipment, multiple disk type concentration (dehydration) ) One or more types can be selected and used from an apparatus, a centrifugal dehydrator, and the like.
いずれの装置を用いた場合も、凝集汚泥は固液分離により濃縮され、濃縮によりＴＳ濃度が高くなった濃縮汚泥が濃縮手段６から次工程へ送られる。このとき、凝集汚泥に含まれていた溶解性カルシウムや硫酸イオンの一部は、固液分離により生じたろ液と共に濃縮手段６から排出される。 Regardless of which device is used, the aggregated sludge is concentrated by solid-liquid separation, and the concentrated sludge whose TS concentration is increased by the concentration is sent from the concentration means 6 to the next step. At this time, some of the soluble calcium and sulfate ions contained in the aggregated sludge are discharged from the concentrating means 6 together with the filtrate generated by the solid-liquid separation.
濃縮工程での濃縮の程度は特に限定されないが、次工程へ送られる濃縮汚泥のＴＳが５０ｇ/Ｌ〜１５０ｇ/Ｌになるように、濃縮条件及び濃縮時間を設定して、汚泥を濃縮するのが好ましい。より好ましくは、濃縮汚泥のＴＳを６０ｇ/Ｌ〜１４０ｇ/Ｌにし、より好ましくはＴＳが７０ｇ/Ｌ〜１３０ｇ/Ｌにし、更に好ましくはＴＳが８０ｇ/Ｌ〜１２０ｇ/Ｌまで濃縮を行う。上記有機性汚泥の場合と同様、「ＴＳ」は残留蒸発物のことであって、凝集汚泥を１０５℃〜１１０℃で蒸発乾固した後に残留する物質の質量と、蒸発乾固する前の凝集汚泥の質量とから算出することができる。 The degree of concentration in the concentration step is not particularly limited, but the sludge is concentrated by setting the concentration conditions and the concentration time so that the TS of the concentrated sludge sent to the next step is 50 g / L to 150 g / L. Is preferable. More preferably, the TS of the concentrated sludge is 60 g / L to 140 g / L, more preferably the TS is 70 g / L to 130 g / L, and further preferably the TS is concentrated to 80 g / L to 120 g / L. As in the case of the above organic sludge, "TS" is a residual evaporative substance, and the mass of the substance remaining after evaporating and drying the aggregated sludge at 105 ° C. to 110 ° C. and the agglomeration before evaporating and drying. It can be calculated from the mass of sludge.
また、含水率に着目すると、次工程へ送られる濃縮汚泥の含水率は、８５質量％を超えることが好ましく、より好ましくは８７質量%以上であり、含水率の好適上限は９５質量％であり、より好ましくは９３質量％以下であり、更により好ましくは９２質量%以下である。 Focusing on the water content, the water content of the concentrated sludge sent to the next step is preferably more than 85% by mass, more preferably 87% by mass or more, and the preferable upper limit of the water content is 95% by mass. , More preferably 93% by mass or less, and even more preferably 92% by mass or less.
濃縮汚泥のＴＳが低く、含水率が高すぎると、次工程で有機凝結剤を分散させ易くなるものの、脱水ろ液側に流出する有機凝結剤が増加し、有機凝結剤を有効利用できなくなり、有機凝結剤の添加量が増加する。他方、濃縮汚泥のＴＳが高く、含水率が低すぎると、濃縮汚泥は固体に近くなり、濃縮汚泥内部に有機凝結剤を分散されることができず、有機凝結剤の効果が十分発揮できなくなるため、やはり有機凝結剤の添加量が増加する。このため、ＴＳと含水率の少なくとも一方が上記好適範囲になるように、濃縮工程の条件を設定する。次に、有機凝結剤を添加する工程について説明する。 If the TS of the concentrated sludge is low and the water content is too high, the organic coagulant can be easily dispersed in the next step, but the amount of the organic coagulant flowing out to the dehydration filtrate side increases, and the organic coagulant cannot be effectively used. The amount of organic coagulant added increases. On the other hand, if the TS of the concentrated sludge is high and the water content is too low, the concentrated sludge becomes close to a solid, and the organic coagulant cannot be dispersed inside the concentrated sludge, so that the effect of the organic coagulant cannot be fully exerted. Therefore, the amount of the organic coagulant added also increases. Therefore, the conditions of the concentration step are set so that at least one of the TS and the water content is within the above-mentioned preferable range. Next, the step of adding the organic coagulant will be described.
- 有機凝結剤の添加工程
凝結剤供給手段７ａは特に限定されないが、例えば、有機凝結剤の貯留槽１７を有しており、貯留槽１７には有機凝結剤の原液又は希釈溶液が貯留されている。使用する有機凝結剤の性状や使用形態は上記の通りである。
—— Step of adding the organic coagulant The coagulant supply means 7a is not particularly limited, but for example, it has a storage tank 17 for the organic coagulant, and the stock solution or the diluted solution of the organic coagulant is stored in the storage tank 17. There is. The properties and usage patterns of the organic coagulant used are as described above.
本工程では、上記凝集工程及び濃縮工程を経た濃縮汚泥に、上記のような有機凝結剤を添加することにより、脱水効率をさらに高めることができる。 In this step, the dehydration efficiency can be further improved by adding the above-mentioned organic coagulant to the concentrated sludge that has undergone the above-mentioned aggregation step and concentration step.
凝集剤供給手段５ａと同様、凝結剤供給手段７ａにも流量調整手段などの制御手段を設置してもよく、未処理（高分子凝集剤の添加前）の有機性汚泥のＴＳを測定するか、有機性汚泥の情報（汚泥の出所、過去のＴＳ測定値等）からそのＴＳを予測しておき、このＴＳと、有機性汚泥の供給量に基づき、制御手段で有機凝結剤の添加量（原液又は固形分として）を上記好適範囲（ＴＳに対し０．１質量％以上）に制御してもよい。 Similar to the coagulant supply means 5a, a control means such as a flow rate adjusting means may be installed in the coagulant supply means 7a to measure the TS of untreated (before the addition of the polymer coagulant) organic sludge. , Predict the TS from the information of organic sludge (source of sludge, past TS measurement value, etc.), and based on this TS and the supply amount of organic sludge, the amount of organic coagulant added by the control means ( The undiluted solution or solid content) may be controlled within the above-mentioned preferable range (0.1% by mass or more with respect to TS).
有機凝結剤と共に無機性の凝集剤又は凝結剤（無機凝集剤）を使用することも可能である。しかし、一般的な無機凝集剤はアルミニウム系、鉄系のいずれも酸性を示すので、無機凝集剤を濃縮汚泥に添加すると、有機性汚泥中では難溶性塩などの態様で存在するカルシウムが溶出し、溶解性カルシウム濃度が上昇してしまう。しかも、無機凝集剤には、硫酸鉄（Ｉ）、（ＩＩ）、ポリ硫酸第二鉄、硫酸アルミニウムなど硫酸イオンを含有するものがあり、この硫酸イオンと溶解性カルシウムが反応することで、硫酸カルシウム（以下、石膏スケール）が析出してしまう。 It is also possible to use an inorganic coagulant or a coagulant (inorganic coagulant) together with the organic coagulant. However, since both aluminum-based and iron-based general inorganic flocculants are acidic, when the inorganic flocculant is added to the concentrated sludge, calcium existing in the form of a sparingly soluble salt or the like is eluted in the organic sludge. , Soluble calcium concentration will increase. Moreover, some inorganic flocculants contain sulfate ions such as iron (I), (II), polyferric sulfate, and aluminum sulfate, and the reaction between these sulfate ions and soluble calcium causes sulfate. Calcium (hereinafter referred to as gypsum scale) is precipitated.
従って、無機凝集剤を添加する場合は、その添加量を抑える必要があり、例えば無機凝集剤の使用量を質量比で有機凝結剤の１/１０以下、好ましくは１/１００未満とし、最も好ましくは無機凝集剤を使用しない。 Therefore, when an inorganic coagulant is added, it is necessary to suppress the amount of the inorganic coagulant added. For example, the amount of the inorganic coagulant used is 1/10 or less, preferably less than 1/100 of the organic coagulant in terms of mass ratio, which is most preferable. Does not use inorganic flocculants.
有機凝結剤を添加後、濃縮汚泥を脱水手段９ａへ送り、下記機械脱水工程に付す。 After adding the organic coagulant, the concentrated sludge is sent to the dewatering means 9a and subjected to the following mechanical dewatering step.
＜機械脱水工程＞
脱水手段９ａは特に限定されず、汚泥脱水に通常用いられる装置を広く用いることが可能であるが、特にスケール発生により脱水効率が低下しやすい装置、具体的には、脱水ろ液排出用の配管や、ろ過機構（パンチングメタル、ウェッジワイヤースクリーン、多重円盤等）を具備する装置が特に適している。
<Mechanical dehydration process>
The dehydration means 9a is not particularly limited, and an apparatus usually used for sludge dehydration can be widely used, but an apparatus in which the dehydration efficiency tends to decrease due to scale generation, specifically, a pipe for discharging a dehydration filtrate And devices equipped with a filtration mechanism (punching metal, wedge wire screen, multiple discs, etc.) are particularly suitable.
例えば、スクリュープレス脱水機、遠心脱水機、多重円盤型脱水機、多重板型スクリュープレス脱水機、回転加圧脱水機、楕円板型脱水機、真空脱水機、ベルトプレス脱水機などから１種以上を選択し、脱水手段９ａとして用いることができる。 For example, one or more types from screw press dehydrator, centrifugal dehydrator, multiple disk type dehydrator, multiple plate type screw press dehydrator, rotary pressure dehydrator, elliptical plate type dehydrator, vacuum dehydrator, belt press dehydrator, etc. Can be selected and used as the dehydration means 9a.
いずれの脱水手段９ａを用いた場合も、有機凝結剤が添加された濃縮汚泥を機械脱水し、ろ液と脱水ケーキに固液分離することができる。このような脱水方法によれば、脱水ケーキの含水率を８０質量％以下、好ましくは７５質量％以下まで低減することができる。 When any of the dewatering means 9a is used, the concentrated sludge to which the organic coagulant is added can be mechanically dewatered and solid-liquid separated into a filtrate and a dewatered cake. According to such a dehydration method, the water content of the dehydrated cake can be reduced to 80% by mass or less, preferably 75% by mass or less.
上述したように、有機凝結剤は硫酸イオンや金属類の含有量が極めて低く、無機凝集剤を使用した時と比較して脱水ろ液のｐＨ変動が少ないため、汚泥中のカルシウムが溶出し難い。また、有機凝結剤の使用により、脱水ろ液中の硫酸イオンの増加も殆ど生じない。 As described above, the organic coagulant has an extremely low content of sulfate ions and metals, and the pH fluctuation of the dehydration filtrate is smaller than that when the inorganic flocculant is used, so that calcium in sludge is difficult to elute. .. In addition, the use of the organic coagulant causes almost no increase in sulfate ions in the dehydrated filtrate.
具体的には、有機凝結剤を添加しなかった場合と比較して、有機凝結剤添加時の脱水ろ液中の溶解性カルシウム濃度の増加量は、４０ｍｇ／Ｌ以下、好ましくは３０ｍｇ／Ｌ以下、さらに好ましくは２０ｍｇ／Ｌ以下、硫酸イオン濃度の増加量は３ｍｇ／Ｌ以下、好ましくは１．５ｍｇ／Ｌ以下、さらにこのましくは０．５ｍｇ／Ｌ以下、かつ、有機凝結剤添加時の脱水ろ液のｐＨを６〜８にすることが可能である。その結果、ろ液中のカルシウムイオン[Ｃａ２+]と硫酸イオン[ＳＯ４ ２−]のイオン積が小さくなり、石膏スケール（ＣａＳＯ４）の生成を抑制することができるので、脱水手段９ａに付着する石膏スケールの低減できる。 Specifically, the amount of increase in the soluble calcium concentration in the dehydrated filtrate when the organic coagulant is added is 40 mg / L or less, preferably 30 mg / L or less, as compared with the case where the organic coagulant is not added. More preferably 20 mg / L or less, the amount of increase in sulfate ion concentration is 3 mg / L or less, preferably 1.5 mg / L or less, more preferably 0.5 mg / L or less, and when an organic coagulant is added. The pH of the dehydrated filtrate can be 6-8. As a result, the ion product of calcium ion [Ca 2+ ] and sulfate ion [SO 4 2- ] in the filtrate becomes small, and the formation of gypsum scale (CaSO 4 ) can be suppressed. Adhering gypsum scale can be reduced.
このように、汚泥含水率低減と廃棄物量削減を図りつつ、金属類や硫酸イオンを含有しない有機凝結剤を後添加することで、石膏スケール生成の防止効果、汚泥焼却時の鉄クリンカ生成防止効果、脱水ケーキの堆肥化に有効、などの効果を得ることが可能である。 In this way, while reducing the sludge moisture content and the amount of waste, by adding an organic coagulant that does not contain metals or sulfate ions afterwards, the effect of preventing the formation of gypsum scale and the effect of preventing the formation of iron clinker during sludge incineration. , Effective for composting dehydrated cake, etc. can be obtained.
以上は、有機凝結剤を高分子凝集剤とは異なる装置に添加する場合について説明したが、本発明はこれに限定されない。 The above has described the case where the organic coagulant is added to an apparatus different from the polymer flocculant, but the present invention is not limited to this.
[第２例の脱水方法]
図３の符号１ｂは第２例の脱水方法で用いる処理装置の一例を示しており、この処理装置１ｂは、凝集剤供給手段５ｂと凝結剤供給手段７ｂに加え、汚泥供給手段４を有し、更に、脱水手段９ｂが遠心力を発生する機構（遠心脱水機）を具備する。次に、この処理装置１ｂに汚泥を供給する工程について説明する。
[Second example of dehydration method]
Reference numeral 1b in FIG. 3 indicates an example of a treatment device used in the dehydration method of the second example, and the treatment device 1b has a sludge supply means 4 in addition to the coagulant supply means 5b and the coagulant supply means 7b. Further, the dehydrating means 9b is provided with a mechanism (centrifugal dehydrator) for generating centrifugal force. Next, a step of supplying sludge to the processing apparatus 1b will be described.
- 汚泥供給工程
汚泥供給手段４は特に限定されないが、有機性汚泥を脱水手段９ｂに供給する供給配管２１を有する。脱水手段９ｂは、例えば、筒状のケーシング４８と、ケーシング４８に挿通された中空の外胴ボウル４５（回転ボウル）と、外胴ボウル４５に挿通された内胴スクリュー４７とを有しており、有機性汚泥の供給配管２１は一端が内胴スクリュー４７に挿通され、ポンプ等による圧送により、内胴スクリュー４７に有機性汚泥が供給される。
--Sludge supply step The sludge supply means 4 is not particularly limited, but has a supply pipe 21 for supplying organic sludge to the dehydration means 9b. The dehydration means 9b has, for example, a tubular casing 48, a hollow outer body bowl 45 (rotary bowl) inserted through the casing 48, and an inner body screw 47 inserted through the outer body bowl 45. One end of the organic sludge supply pipe 21 is inserted into the inner body screw 47, and the organic sludge is supplied to the inner body screw 47 by pumping with a pump or the like.
- 凝集工程及び凝集汚泥濃縮工程
第１例の処理装置１ａと同様、凝集剤供給手段５ｂは混和槽１５を有しており、混和槽１５の一端に供給配管２２が接続され、この供給配管２２の他端は、有機性汚泥の供給配管２１と同じ内胴スクリュー４７に挿通されている。
--Coagulation step and coagulation sludge concentration step Similar to the treatment device 1a of the first example, the coagulant supply means 5b has a mixing tank 15, and a supply pipe 22 is connected to one end of the mixing tank 15, and the supply pipe 22 is connected. The other end of the is inserted into the same inner body screw 47 as the organic sludge supply pipe 21.
ここでは、有機性汚泥の供給配管２１は、先端が内胴スクリュー４７内部へ突き出るように、高分子凝集剤の供給配管２２に挿通され、その突き出た先端部分から有機性汚泥が供給される。従って、高分子凝集剤（溶液）はポンプなどにより混和槽１５から圧送されると、有機性汚泥を取り囲むように、有機性汚泥の後方から内胴スクリュー４７内部に注入される。 Here, the organic sludge supply pipe 21 is inserted into the polymer flocculant supply pipe 22 so that the tip protrudes into the inner body screw 47, and the organic sludge is supplied from the protruding tip portion. Therefore, when the polymer flocculant (solution) is pumped from the mixing tank 15 by a pump or the like, it is injected into the inner body screw 47 from the rear of the organic sludge so as to surround the organic sludge.
内胴スクリュー４７の壁には外胴ボウル４５の内部空間（プール）と連通する１以上の供給口４９ａ、４９ｂが設けられ、少なくとも１つの供給口４９ａが有機性汚泥と高分子凝集剤の供給場所に近接している。 The wall of the inner body screw 47 is provided with one or more supply ports 49a and 49b communicating with the internal space (pool) of the outer body bowl 45, and at least one supply port 49a supplies organic sludge and a polymer flocculant. Close to the place.
内胴スクリュー４７と外胴ボウル４５は、内胴スクリュー４７に供給配管２１、２２、２３が挿通された状態を維持したまま、回転軸を中心に同一方向に異なる速度で回転するよう構成されており、この回転により、有機性汚泥は高分子凝集剤と接触しながら、供給口４９ａを通って外胴ボウル４５へ移送され、内胴スクリュー４７の外面に設置したスクリュー羽根４６により外胴ボウル４５内部を排出口４４へ向かって移送される。 The inner body screw 47 and the outer body bowl 45 are configured to rotate at different speeds in the same direction around the rotation axis while maintaining the state in which the supply pipes 21, 22, and 23 are inserted through the inner body screw 47. By this rotation, the organic sludge is transferred to the outer body bowl 45 through the supply port 49a while being in contact with the polymer flocculant, and is transferred to the outer body bowl 45 by the screw blades 46 installed on the outer surface of the inner body screw 47. The inside is transferred toward the discharge port 44.
このとき、有機性汚泥は、内胴スクリュー４７と外胴ボウル４５との間の回転差により生じる遠心力を受ける。すなわち、有機性汚泥は、移送による高分子凝集剤との接触（混和）で凝集が進行し、回転による遠心力で濃縮が進行して濃縮汚泥となる。 At this time, the organic sludge receives the centrifugal force generated by the rotational difference between the inner body screw 47 and the outer body bowl 45. That is, the organic sludge is aggregated by contact (mixing) with the polymer flocculant by transfer, and is concentrated by the centrifugal force due to rotation to become concentrated sludge.
- 有機凝結剤添加工程
第１例の処理装置１ａと同様、凝結剤供給手段７ｂも貯留槽１７を有しており、この貯留槽１７の一端に供給配管２３が接続され、この供給配管２３の他端は脱水手段９ｂ、例えば、他の供給配管２１、２２と同じ内胴スクリュー４７に挿通されており、貯留槽１７に収容した有機凝結剤又はその希釈液は、ポンプなどで圧送され、内胴スクリュー４７に供給される。
--Organic coagulant addition step Similar to the processing device 1a of the first example, the coagulant supply means 7b also has a storage tank 17, and a supply pipe 23 is connected to one end of the storage tank 17, and the supply pipe 23 of the storage tank 23 is connected. The other end is inserted into the dehydrating means 9b, for example, the same inner body screw 47 as the other supply pipes 21 and 22, and the organic coagulant or its diluent contained in the storage tank 17 is pumped by a pump or the like and inside. It is supplied to the body screw 47.
この供給配管２３と、他の供給配管２１、２２との位置関係は特に限定されないが、ここでは、高分子凝集剤の供給配管２２は、先端が内胴スクリュー４７内部へ突き出るように、有機凝結剤の供給配管２３に挿通され、有機性汚泥の供給配管２１は、高分子凝集剤の供給配管２２よりも更に内胴スクリュー４７内部へ突き出されている。 The positional relationship between the supply pipe 23 and the other supply pipes 21 and 22 is not particularly limited, but here, the polymer flocculant supply pipe 22 is organically condensed so that the tip protrudes into the inner body screw 47. It is inserted through the agent supply pipe 23, and the organic sludge supply pipe 21 protrudes further into the inner body screw 47 than the polymer flocculant supply pipe 22.
従って、有機凝結剤は、高分子凝集剤よりも有機性汚泥の供給場所から離間した位置で脱水手段９ｂに供給されることになる。 Therefore, the organic coagulant is supplied to the dewatering means 9b at a position farther from the supply location of the organic sludge than the polymer flocculant.
供給口４９ａ、４９ｂを複数設置する場合、１以上の供給口４９ｂを他の排出口４９ａよりも排出口４４に近い側に設け、排出口４４に近い側の供給口４９ｂに有機凝結剤の供給場所が近接するように供給配管２３を設置してもよい。この場合、有機凝結剤は外胴ボウル４５に直接供給され、排出口４４へ向かって移送される途中の有機性汚泥に添加されることになる。 When a plurality of supply ports 49a and 49b are installed, one or more supply ports 49b are provided closer to the discharge port 44 than the other discharge ports 49a, and the organic coagulant is supplied to the supply port 49b on the side closer to the discharge port 44. The supply pipe 23 may be installed so that the locations are close to each other. In this case, the organic coagulant is directly supplied to the outer body bowl 45 and added to the organic sludge being transferred toward the discharge port 44.
この有機性汚泥は有機凝結剤が添加される前に高分子凝集剤と接触して、凝集と濃縮が進行しているので、処理前よりもＴＳ濃度が高く（含水率が低く）、適度に流動性が低下した濃縮状態にある。この状態の有機性汚泥（濃縮汚泥）に有機凝結剤が添加され、スクリュー羽根４６で移送されることで、有機凝結剤が脱水ろ液側に過剰に流出することなく、有機性汚泥に浸透し、分散される。 This organic sludge comes into contact with the polymer flocculant before the organic coagulant is added, and coagulation and concentration proceed. Therefore, the TS concentration is higher (water content is lower) than before the treatment, and the sludge is moderately concentrated. It is in a concentrated state with reduced fluidity. An organic coagulant is added to the organic sludge (concentrated sludge) in this state and transferred by the screw blade 46, so that the organic coagulant permeates the organic sludge without excessively flowing out to the dehydration filtrate side. , Distributed.
- 脱水工程
有機凝結剤が分散した有機性汚泥は、遠心力により外胴ボウル４５で更に脱水され、スクリュー羽根４６により移送されて排出口４４から脱水ケーキとして排出される。他方、遠心脱水により固液分離したろ液は、脱水ケーキ排出側との水位差により、脱水ケーキとは別の排出口から排出される。
—— Dehydration step The organic sludge in which the organic coagulant is dispersed is further dehydrated in the outer body bowl 45 by centrifugal force, transferred by the screw blades 46, and discharged as a dehydrated cake from the discharge port 44. On the other hand, the filtrate separated into solid and liquid by centrifugal dehydration is discharged from a discharge port different from the dehydrated cake due to the difference in water level from the dehydrated cake discharge side.
第２例の脱水方法は、凝集工程、凝集汚泥濃縮工程、有機凝結剤添加工程、遠心脱水工程を遠心脱水機内で行うため、凝集工程や凝集汚泥濃縮工程において、別の反応槽や装置が不必要となる。 In the dehydration method of the second example, since the coagulation step, the coagulation sludge concentration step, the organic coagulant addition step, and the centrifugal dehydration step are performed in the centrifugal dehydrator, another reaction tank or apparatus is not required in the coagulation step and the coagulation sludge concentration step. You will need it.
以上は、供給配管２１、２２、２３を脱水手段９ｂの同じ部材（内胴スクリュー４７）に供給する場合について説明したが、有機凝結剤よりも高分子凝集剤が有機性汚泥に先に添加されるのであれば、供給配管２１、２２、２３の構造や設置場所は特に限定されない。 The case where the supply pipes 21, 22 and 23 are supplied to the same member (inner body screw 47) of the dehydration means 9b has been described above, but the polymer flocculant is added to the organic sludge before the organic coagulant. If so, the structure and installation location of the supply pipes 21, 22, and 23 are not particularly limited.
例えば、高分子凝集剤の供給配管２２を有機性汚泥の供給配管２１に接続し、予め、高分子凝集剤が添加された有機性汚泥を脱水手段９ｂに添加してもよい。また第１例と同様、各供給手段５ｂ、７ｂに調整手段を設置し、有機性汚泥の性状（ＴＳなど）に合わせて、高分子凝集剤と有機凝結剤の少なくとも一方の添加量を制御してもよい。 For example, the polymer coagulant supply pipe 22 may be connected to the organic sludge supply pipe 21, and the organic sludge to which the polymer coagulant has been added in advance may be added to the dehydration means 9b. Further, as in the first example, adjusting means is installed in each of the supply means 5b and 7b to control the addition amount of at least one of the polymer flocculant and the organic coagulant according to the properties of the organic sludge (TS, etc.). You may.
第１例の場合と同様、第２例の脱水方法で排出した脱水ケーキは廃棄してもよいし、堆肥などに再利用することも可能であるが、汚泥焼却などの廃棄処理時には鉄クリンカの生成が防止され、再利用時には堆肥として有効な成分（リン）を保持するなどの効果が得られる。 As in the case of the first example, the dehydrated cake discharged by the dehydration method of the second example may be discarded or reused for compost, etc. The formation is prevented, and when reused, effects such as retaining an effective component (phosphorus) as compost can be obtained.
以下、本発明を下記実施例及び比較例に基づいてさらに記述する。本試験では、凝集汚泥を濃縮し濃縮汚泥とした後で、濃縮汚泥に有機凝結剤を添加し、脱水することで、石膏スケール生成の抑制効果と、含水率低減効果を得られるかを検討した。 Hereinafter, the present invention will be further described based on the following Examples and Comparative Examples. In this test, it was examined whether the effect of suppressing the formation of gypsum scale and the effect of reducing the water content can be obtained by concentrating the coagulated sludge into concentrated sludge and then adding an organic coagulant to the concentrated sludge and dehydrating it. ..
＜試験方法＞
試験には、１種類のし尿処理場由来の混合汚泥（余剰汚泥＋凝沈汚泥）（汚泥Ａ）、２種類のし尿処理場由来の混合汚泥（生し尿＋浄化槽汚泥）（汚泥Ｂ、Ｃ）の計３種類を使用した。汚泥Ａに用いた凝沈汚泥は、水処理設備の廃水に、無機凝集剤、高分子凝集剤を添加、撹拌し、凝集フロックを形成後に沈殿させ、重力濃縮により得たものである。
<Test method>
In the test, mixed sludge derived from one type of human waste treatment plant (surplus sludge + coagulated sludge) (sludge A), mixed sludge derived from two types of human waste treatment plant (raw urine + septic tank sludge) (sludge B, C) A total of 3 types were used. The coagulated sludge used for sludge A was obtained by adding an inorganic flocculant and a polymer flocculant to wastewater of a water treatment facility, stirring the mixture, forming aggregated flocs and then precipitating the sludge, and then concentrating the sludge by gravity.
汚泥Ａ、汚泥Ｂ、汚泥ＣのＴＳはそれぞれ１１．４ｇ/Ｌ、７．９８ｇ/Ｌ、６．５６ｇ/Ｌであり、ｐＨはそれぞれ６．９、７．３、６．８、カルシウム濃度はそれぞれ３０５ｍｇ/Ｌ、１２６ｍｇ/Ｌ、１７３ｍｇ/Ｌ、溶解性カルシウム濃度はそれぞれ７１．７ｍｇ/Ｌ、２７．７ｍｇ/Ｌ、５３．３ｍｇ/Ｌ、硫酸イオン濃度はそれぞれ１０１ｍｇ/Ｌ、０．６ｍｇ/Ｌ、２．０ｍｇ/Ｌであった。 The TS of sludge A, sludge B, and sludge C are 11.4 g / L, 7.98 g / L, and 6.56 g / L, respectively, and the pH is 6.9, 7.3, 6.8, and the calcium concentration is 6.9, 7.3, 6.8, respectively. 305 mg / L, 126 mg / L, 173 mg / L, respectively, soluble calcium concentration was 71.7 mg / L, 27.7 mg / L, 53.3 mg / L, respectively, and sulfate ion concentration was 101 mg / L, 0.6 mg / L, respectively. It was L, 2.0 mg / L.
ＴＳとは、蒸発残留物のことであり、汚泥を１０５℃〜１１０℃で蒸発乾固したときに残留する物質の濃度である。測定方法は、下水試験法（日本下水道協会発行、下水試験方法）に準拠した。 TS is an evaporation residue, and is a concentration of a substance remaining when sludge is evaporated to dryness at 105 ° C to 110 ° C. The measurement method was based on the sewage test method (published by the Japan Sewerage Association, sewage test method).
溶解性カルシウム濃度と硫酸イオン濃度の測定は、まず、下水試験法のガラス繊維ろ紙法（ＪＩＳ Ｋ ０１０２ １４．１）に準じ、前処理を実施した。詳しくは、原液試料を孔径1μmのガラス繊維ろ紙で吸引ろ過したろ液を測定用試料とした。 The soluble calcium concentration and the sulfate ion concentration were first pretreated according to the glass fiber filter paper method (JIS K 0102 14.1) of the sewage test method. Specifically, the undiluted solution sample was suction-filtered with a glass fiber filter paper having a pore size of 1 μm, and the filtrate was used as the measurement sample.
溶解性カルシウムの測定は、前処理で調製した測定用試料を、下水試験法のＩＣＰ発光分光分析法に準じ、測定した。詳しくは、（１＋１）硝酸（３５％硝酸）を添加したものを、５〜１０分、９７℃以上に加温し、冷却した試料をＩＣＰ発光分光分析装置により測定した。硫酸イオン（ＳＯ４ ２−）の測定は、前処理で調製した測定用試料を、下水試験法のイオンクロマトグラフ法に準じ、測定した。 For the measurement of soluble calcium, the measurement sample prepared in the pretreatment was measured according to the ICP emission spectroscopic analysis method of the sewage test method. Specifically, a sample to which (1 + 1) nitric acid (35% nitric acid) was added was heated to 97 ° C. or higher for 5 to 10 minutes, and the cooled sample was measured by an ICP emission spectrophotometer. Measurement of Sulfate ion (SO 4 2-) is a measurement sample prepared in the previous process, according to ion chromatography sewage test method was measured.
なお、カルシウム濃度とは、難溶性塩の形態も含めた全カルシウム濃度のことである。このカルシウム濃度は、まず、汚泥適量を純水に溶解し汚泥水溶液とした。この汚泥水溶液を溶解性カルシウム濃度の測定と同様に、下水試験法のＩＣＰ発光分光分析法に準じ、測定した。 The calcium concentration is the total calcium concentration including the form of the poorly soluble salt. For this calcium concentration, first, an appropriate amount of sludge was dissolved in pure water to prepare an aqueous sludge solution. This sludge aqueous solution was measured according to the ICP emission spectroscopic analysis method of the sewage test method in the same manner as the measurement of the soluble calcium concentration.
高分子凝集剤としては、汚泥Ａには両性高分子凝集剤Ａ（ポリメタクリル酸エステル・アクリル酸共重合物とポリアクリル酸エステル・アクリル酸共重合物との混合物、分子量３００万、ｐＨ４におけるカチオン度約１．５ ｍｅｑ／ｇ、汚泥Ｂにはカチオン性高分子凝集剤Ｂ（ポリアクリル酸エステル系、分子量８００万、ｐＨ４におけるカチオン度約３．３）、汚泥Ｃにはカチオン性高分子凝集剤Ｃ（ポリアクリル酸エステル系、分子量７００万、ｐＨ４におけるカチオン度約４．０）を使用した。高分子凝集剤使用時は、粉末状のものを純水に溶解し、溶解濃度２ｇ/Ｌの高分子凝集剤水溶液として用いた。 As the polymer flocculant, sludge A contains an amphoteric polymer flocculant A (a mixture of a polymethacrylic acid ester / acrylic acid copolymer and a polyacrylic acid ester / acrylic acid copolymer, a molecular weight of 3 million, and a cation at pH 4. Degree of about 1.5 meq / g, cationic polymer flocculant B for sludge B (polyacrylic acid ester type, molecular weight 8 million, cationic degree at pH 4 about 3.3), cationic polymer flocculant for sludge C Agent C (polyacrylic acid ester type, molecular weight 7 million, cationic degree at pH 4 of about 4.0) was used. When using a polymer flocculant, a powdery substance was dissolved in pure water and the dissolution concentration was 2 g / L. Was used as an aqueous solution of a polymer flocculant.
有機凝結剤としては、有機凝結剤ａ（ポリアミン系、分子量２５万、ｐＨ４における有機凝結剤の原液中の成分としてのカチオン度約６ｍｅｑ/ｇ）、有機凝結剤ｂ（ポリアミン系、分子量３万、ｐＨ４における有機凝結剤の原液中の成分としてのカチオン度約１０ｍｅｑ/ｇ）、有機凝結剤ｃ（ポリＤＡＤＭＡＣ系、分子量３万、ｐＨ４における有機凝結剤の原液中の成分としてのカチオン度約６．４ｍｅｑ/ｇ）、有機凝結剤ｄ（ポリジシアンジアミド系、分子量１．５万、ｐＨ４における有機凝結剤の原液中の成分としてのカチオン度約５．９ｍｅｑ/ｇ）の計４種類を使用した。有機凝結剤使用時は、液状のもの（原液）を純水で希釈し、原液の溶解濃度２０ｇ/Ｌの有機凝結剤希釈液として用いた。 Examples of the organic coagulant include organic coagulant a (polyamine type, molecular weight 250,000, cation degree as a component in the stock solution of the organic coagulant at pH 4 of about 6 meq / g), organic coagulant b (polyamine type, molecular weight 30,000,). 2. Cationicity as a component in the stock solution of the organic coagulant at pH 4 (polyDADMAC system, molecular weight 30,000, cationic degree as a component in the stock solution of the organic coagulant at pH 4). 4 meq / g) and organic coagulant d (polydisyandiamide type, molecular weight 15,000, cation degree as a component in the stock solution of the organic coagulant at pH 4 of about 5.9 meq / g), a total of four types were used. When the organic coagulant was used, the liquid (stock solution) was diluted with pure water and used as the organic coagulant diluent having a dissolution concentration of 20 g / L in the stock solution.
また、後述する比較例に用いた無機凝集剤は、濃度１６０ｇ-Ｆｅ/Ｌのポリ硫酸第２鉄（以下、無機凝集剤）溶液（原液）であり、この原液を無機凝集剤として使用した。 The inorganic flocculant used in the comparative example described later was a ferric polysulfate (hereinafter, inorganic flocculant) solution (stock solution) having a concentration of 160 g-Fe / L, and this stock solution was used as the inorganic flocculant.
＜試験手順＞
試験手順は、以下の通りである。
（汚泥の凝集及び汚泥の一次脱水・濃縮）
<Test procedure>
The test procedure is as follows.
(Agglutination of sludge and primary dehydration / concentration of sludge)
- 汚泥Ａを用いた濃縮汚泥Ａ
汚泥Ａを用いた試験では、ビーカーに入れた有機性汚泥５００ｍＬに対し、高分子凝集剤の対ＴＳ濃度が２．８質量％になるよう高分子凝集剤Ａの水溶液を添加し、スパチュラで汚泥が凝集するまで撹拌し、凝集汚泥Ａを形成させた。凝集汚泥Ａをふるい上で固液分離し、汚泥を濃縮することで、濃縮汚泥Ａとした。
--Concentrated sludge A using sludge A
In the test using sludge A, an aqueous solution of the polymer flocculant A was added to 500 mL of the organic sludge placed in the beaker so that the TS concentration of the polymer flocculant was 2.8% by mass, and the sludge was used with a spatula. The mixture was stirred until it aggregated to form aggregated sludge A. The coagulated sludge A was solid-liquid separated on a sieve and the sludge was concentrated to obtain concentrated sludge A.
- 汚泥Ｂを用いた濃縮汚泥Ｂ
汚泥Ｂを用いた試験では、ビーカーに入れた有機性汚泥５００ｍＬに対し、高分子凝集剤の対ＴＳ濃度が１．３質量％になるよう高分子凝集剤Ｂ水溶液を添加し、スパチュラで汚泥が凝集するまで撹拌し、凝集汚泥Ｂを形成させた。凝集汚泥Ｂをふるい上で固液分離し、汚泥を濃縮することで、濃縮汚泥Ｂとした。
--Concentrated sludge B using sludge B
In the test using sludge B, an aqueous solution of the polymer flocculant B was added so that the concentration of the polymer flocculant with respect to TS was 1.3% by mass with respect to 500 mL of the organic sludge placed in the beaker, and the sludge was generated with a spatula. The mixture was stirred until it agglomerated to form agglomerated sludge B. The coagulated sludge B was solid-liquid separated on a sieve, and the sludge was concentrated to obtain concentrated sludge B.
- 汚泥Ｃを用いた濃縮汚泥Ｃ
汚泥Ｃの試験では、ビーカーに入れた有機性汚泥５００ｍＬに対し、高分子凝集剤の対ＴＳ濃度が１．５質量％になるよう高分子凝集剤Ｃ水溶液を添加し、スパチュラで汚泥が凝集するまで撹拌し、凝集汚泥を形成させた。凝集汚泥をふるい上で固液分離し、汚泥を濃縮することで、濃縮汚泥Ｃとした。
--Concentrated sludge C using sludge C
In the sludge C test, an aqueous solution of the polymer flocculant C was added to 500 mL of the organic sludge placed in the beaker so that the concentration of the polymer flocculant with respect to TS was 1.5% by mass, and the sludge aggregated with a spatula. The mixture was stirred until agglomerated sludge was formed. The coagulated sludge was separated into solid and liquid on a sieve, and the sludge was concentrated to obtain concentrated sludge C.
（脱水試験）
[濃縮汚泥Ａ]
実施例１-１、１-２、１-３、１-４では、濃縮汚泥Ａにそれぞれ、０．６４質量％（対ＴＳ）（有機凝結剤の原液換算による）の注入量で、有機凝結剤ａ、ｂ、ｃ、ｄをそれぞれ添加し、試験用ベルトプレス脱水機を用いて脱水し、脱水ケーキＡ１-１、Ａ１-２、Ａ１-３、Ａ１-４の含水率を測定した。
(Dehydration test)
[Concentrated sludge A]
In Examples 1-1, 1-2, 1-3, and 1-4, organic coagulation was performed in the concentrated sludge A at an injection amount of 0.64% by mass (vs. TS) (based on the stock solution equivalent of the organic coagulant). Agents a, b, c, and d were added, respectively, and dehydrated using a test belt press dehydrator, and the water content of the dehydrated cakes A1-1, A1-2, A1-3, and A1-4 was measured.
さらに、実施例１-５、１-６では、濃縮汚泥Ａに対する有機凝結剤ｂの添加量をそれぞれ１．２８質量％、１．９２質量％（対ＴＳ）（有機凝結剤の原液換算による）に変更した以外は、上記実施例１−２と同じ方法で脱水し、脱水ケーキＡ１-５、Ａ１-６の含水率を測定した。また、実施例１-５における、脱水ろ液Ａ１-５の水質分析を実施した。 Further, in Examples 1-5 and 1-6, the amount of the organic coagulant b added to the concentrated sludge A was 1.28% by mass and 1.92% by mass (vs. TS) (based on the stock solution equivalent of the organic coagulant). The dehydration was carried out in the same manner as in Example 1-2 above, except that the content was changed to, and the water content of the dehydrated cakes A1-5 and A1-6 was measured. In addition, the water quality analysis of the dehydrated filtrate A1-5 in Examples 1-5 was carried out.
比較試験として、各濃縮汚泥に無機凝集剤を添加した試験を、以下の試験手順で実施した。比較例１では、この濃縮汚泥Ａに無機凝集剤と有機凝結剤のいずれも添加せず、試験用ベルトプレス脱水機を用いて脱水し、脱水ケーキａ１の含水率を測定し、脱水ろ液ａ１の水質分析を実施した。 As a comparative test, a test in which an inorganic flocculant was added to each concentrated sludge was carried out according to the following test procedure. In Comparative Example 1, neither the inorganic flocculant nor the organic coagulant was added to the concentrated sludge A, and the sludge was dehydrated using a test belt press dehydrator, the water content of the dehydrated cake a1 was measured, and the dehydrated filtrate a1 was measured. Water quality analysis was carried out.
比較例２-１、２-２、２-３では、濃縮汚泥Ａにそれぞれ、１．０質量％、２．０質量％、３．０質量％（対ＴＳ）（無機凝集剤の原液中のＦｅ換算による）の無機凝集剤を添加し、試験用ベルトプレス脱水機を用いて脱水し、脱水ケーキａ２-１、ａ２-２、ａ２-３の含水率を測定し、脱水ろ液ａ２-２の水質分析を実施した。 In Comparative Examples 2-1, 2-2, and 2-3, 1.0% by mass, 2.0% by mass, and 3.0% by mass (vs. TS) (against TS) (in the undiluted solution of the inorganic flocculant) were added to the concentrated sludge A, respectively. Add an inorganic flocculant (according to Fe conversion), dehydrate using a test belt press dehydrator, measure the water content of the dehydrated cakes a2-1, a2-2, and a2-3, and dehydrate filtrate a2-2. Water quality analysis was carried out.
[濃縮汚泥Ｂ]
実施例２-１、２-２、２-３、２-４では、濃縮汚泥Ｂにそれぞれ、０．６４質量％（対ＴＳ）（有機凝結剤の原液換算による）の注入量で、有機凝結剤ａ、ｂ、ｃ、ｄをそれぞれ添加し、試験用ベルトプレス脱水機を用いて脱水し、脱水ケーキＢ２-１、Ｂ２-２、Ｂ２-３、Ｂ２-４の含水率を測定した。
[Concentrated sludge B]
In Examples 2-1 and 2-2, 2-3, and 2-4, the concentrated sludge B was organically condensed with an injection amount of 0.64% by mass (to TS) (based on the stock solution equivalent of the organic coagulant). Agents a, b, c, and d were added, respectively, and dehydrated using a test belt press dehydrator, and the water content of the dehydrated cakes B2-1, B2-2, B2-3, and B2-4 was measured.
さらに、実施例２-５、２-６では、濃縮汚泥Ｂにそれぞれ１．２８質量%、１．９２質量%（対ＴＳ）（有機凝結剤の原液換算による）の有機凝結剤ｂをそれぞれ添加し、試験用ベルトプレス脱水機を用いて脱水し、脱水ケーキＢ２−５、Ｂ２−６の含水率を測定した。また、実施例２−５における、脱水ろ液Ｂ２−５の水質分析を実施した。 Further, in Examples 2-5 and 2-6, 1.28% by mass and 1.92% by mass (vs. TS) of the organic coagulant b (based on the stock solution equivalent of the organic coagulant) were added to the concentrated sludge B, respectively. Then, dehydration was performed using a test belt press dehydrator, and the water content of the dehydrated cakes B2-5 and B2-6 was measured. Moreover, the water quality analysis of the dehydration filtrate B2-5 in Example 2-5 was carried out.
比較例３では、無機凝集剤と有機凝結剤のいずれも添加していない濃縮汚泥Ｂを試験用ベルトプレス脱水機を用いて脱水し、脱水ケーキｂ１の含水率を測定し、脱水ろ液ｂ１の水質分析を実施した。 In Comparative Example 3, concentrated sludge B to which neither an inorganic flocculant nor an organic coagulant was added was dehydrated using a test belt press dehydrator, the water content of the dehydrated cake b1 was measured, and the dehydrated filtrate b1 was measured. A water quality analysis was carried out.
比較例４−１、４−２、４−３では、濃縮汚泥Ｂにそれぞれ、１．０質量％、２．０質量％、３．０質量％（対ＴＳ）（無機凝集剤の原液中のＦｅ換算による）の無機凝集剤を添加し、試験用ベルトプレス脱水機を用いて脱水し、脱水ケーキｂ４−１、ｂ４−２、ｂ４−３の含水率を測定し、脱水ろ液ｂ４−２の水質分析を実施した。 In Comparative Examples 4-1, 4-2, and 4-3, 1.0% by mass, 2.0% by mass, and 3.0% by mass (vs. TS) (in the undiluted solution of the inorganic flocculant) were added to the concentrated sludge B, respectively. Add an inorganic flocculant (according to Fe conversion), dehydrate using a test belt press dehydrator, measure the water content of the dehydrated cakes b4-1, b4-2, and b4-3, and measure the dehydration filtrate b4-2. Water quality analysis was carried out.
[濃縮汚泥Ｃ]
実施例３−１、３−２、３−３、３−４では、濃縮汚泥Ｃにそれぞれ、０．６４質量％（対ＴＳ）（有機凝結剤の原液換算による）の注入量で、有機凝結剤ａ、ｂ、ｃ、ｄをそれぞれ添加し、試験用ベルトプレス脱水機を用いて脱水し、脱水ケーキＣ３−１、Ｃ３−２、Ｃ３−３、Ｃ３−４の含水率を測定した。
[Concentrated sludge C]
In Examples 3-1, 3-2, 3-3, and 3-4, organic coagulation was performed in the concentrated sludge C at an injection amount of 0.64% by mass (to TS) (based on the stock solution equivalent of the organic coagulant). Agents a, b, c, and d were added, respectively, and dehydrated using a test belt press dehydrator, and the water content of the dehydrated cakes C3-1, C3-2, C3-3, and C3-4 was measured.
さらに、実施例３−５、３−６では、濃縮汚泥Ｃにそれぞれ１．２８質量％、１．９２質量％（対ＴＳ）（有機凝結剤の原液換算による）の有機凝結剤ｂをそれぞれ添加し、試験用ベルトプレス脱水機を用いて脱水し、脱水ケーキＣ３−５、Ｃ３−６の含水率を測定した。また、実施例３−５における、脱水ろ液Ｃ３−５の水質分析を実施した。 Further, in Examples 3-5 and 3-6, 1.28% by mass and 1.92% by mass (vs. TS) of the organic coagulant b (based on the stock solution equivalent of the organic coagulant) were added to the concentrated sludge C, respectively. Then, dehydration was performed using a test belt press dehydrator, and the water content of the dehydrated cakes C3-5 and C3-6 was measured. Moreover, the water quality analysis of the dehydration filtrate C3-5 in Example 3-5 was carried out.
比較例５では、無機凝集剤、有機凝結剤のいずれも添加していない濃縮汚泥Ｃを試験用ベルトプレス脱水機を用いて脱水し、脱水ケーキｃ１の含水率を測定し、脱水ろ液ｃ１の水質分析を実施した。 In Comparative Example 5, concentrated sludge C to which neither an inorganic flocculant nor an organic coagulant was added was dehydrated using a test belt press dehydrator, the water content of the dehydrated cake c1 was measured, and the dehydrated filtrate c1 was measured. A water quality analysis was carried out.
比較例６−１、６−２、６−３では、濃縮汚泥Ｃにそれぞれ、１．０質量％、２．０質量％、３．０質量％（対ＴＳ）（無機凝集剤の原液中のＦｅ換算による）の無機凝集剤を添加し、試験用ベルトプレス脱水機を用いて脱水し、脱水ケーキｃ６−１、ｃ６−２、ｃ６−３の含水率を測定し、脱水ろ液ｃ６−２の水質分析を実施した。 In Comparative Examples 6-1, 6-2, and 6-3, 1.0% by mass, 2.0% by mass, and 3.0% by mass (vs. TS) (in the undiluted solution of the inorganic flocculant) were added to the concentrated sludge C, respectively. Add an inorganic flocculant (according to Fe conversion), dehydrate using a test belt press dehydrator, measure the water content of the dehydrated cakes c6-1, c6-2, c6-3, and dehydrate filtrate c6-2. Water quality analysis was carried out.
＜試験結果＞
[脱水ケーキ含水率低減効果の検討]
（実施例１〜３）
実施例１〜３の試験結果を表１−１〜１−３に示す。
<Test results>
[Examination of water content reduction effect of dehydrated cake]
(Examples 1 to 3)
The test results of Examples 1 to 3 are shown in Tables 1-1 to 1-3.
注入率０．６４質量％の条件で有機凝結剤ａ〜ｄを比較したところ、有機凝結剤ｂは汚泥Ａ、Ｂに対して脱水効果が最も高く、汚泥Ｃに対しても、最も含水率の低い実施例３−１との差が０．４質量％と僅差であった。従って、ポリアミン系、高カチオン度の有機凝結剤を使用することで、高い脱水効果が得られることが確認された。 When the organic coagulants a to d were compared under the condition of an injection rate of 0.64% by mass, the organic coagulant b had the highest dehydration effect on sludges A and B, and also had the highest water content on sludge C. The difference from the low Example 3-1 was as small as 0.4% by mass. Therefore, it was confirmed that a high dehydration effect can be obtained by using a polyamine-based organic coagulant having a high degree of cation.
（比較例１、２及び実施例１−２、１−５、１−６）
比較例１〜６、及び実施例１−２、１−５、１−６、実施例２−２、２−５、２−６、実施例３−２、３−５、３−６の試験結果を表２−１〜２−３に示す。実施例との比較のため、下記表中には実施例１−２、１−５、１−６の結果も併せて記載した。
(Comparative Examples 1 and 2 and Examples 1-2, 1-5, 1-6)
Tests of Comparative Examples 1-6, Examples 1-2, 1-5, 1-6, Examples 2-2, 2-5, 2-6, Examples 3-2, 3-5, 3-6 The results are shown in Tables 2-1 to 2-3. For comparison with Examples, the results of Examples 1-2, 1-5, and 1-6 are also shown in the table below.
上記表から明らかように、有機凝結剤と無機凝集剤のいずれも添加しない比較例１、３、５は、同じ汚泥Ａ、Ｂ、Ｃに有機凝結剤又は無機凝集剤を添加した場合と比較して、脱水ケーキの含水率が最も高く、脱水効果が低いことが確認された。 As is clear from the above table, Comparative Examples 1, 3 and 5 in which neither the organic coagulant nor the inorganic coagulant was added were compared with the case where the organic coagulant or the inorganic coagulant was added to the same sludges A, B and C. It was confirmed that the dehydrated cake had the highest water content and the lowest dehydration effect.
比較例１、３、５と比較すると、有機凝結剤又は無機凝集剤を使用した場合は、含水率が２．８〜３．２質量％程度低減しており、有機凝結剤と無機凝集剤とを比較すると、濃縮汚泥Ａ、Ｂに対しては、有機凝結剤の含水率低減効果は無機凝集剤と同等か、若干劣る程度（０．３〜０．８質量％）であり、本発明の有機凝結剤を高分子凝集剤の後に添加することで、脱水ケーキ含水率を低減させる効果が得られることが確認された。 Compared with Comparative Examples 1, 3 and 5, when the organic coagulant or the inorganic coagulant was used, the water content was reduced by about 2.8 to 3.2% by mass, and the organic coagulant and the inorganic coagulant were used. The water content reducing effect of the organic coagulant is equal to or slightly inferior to that of the inorganic coagulant (0.3 to 0.8% by mass) with respect to the concentrated sludges A and B. It was confirmed that the effect of reducing the water content of the dehydrated cake can be obtained by adding the organic coagulant after the polymer flocculant.
＜石膏スケール生成抑制効果の検討＞
下記表３の分析項目について、脱水ろ液の水質分析結果を行った。
<Examination of gypsum scale generation inhibitory effect>
The water quality analysis results of the dehydrated filtrate were performed for the analysis items in Table 3 below.
分析項目のうち、ｐＨ、Ｍ−アルカリ度、ＳＳ、ＰＯ４−Ｐの測定方法は下水試験法に準拠した。また、電気伝導率、の測定方法はＪＩＳ Ｋ ０１０２に準拠した。 Among analysis items, pH, M- alkalinity, SS, method of measuring PO 4 -P is compliant with the sewage test method. The method for measuring the electrical conductivity was based on JIS K 0102.
具体的には、ｐＨはガラス電極法により、採取した脱水ろ液に対して実施した。Ｍ−アルカリ度はアルカリ度[ｐＨ４．８]（総アルカリ度又はＭ−アルカリ度）の測定方法により測定した。ＳＳは脱水ろ液を孔径１μｍガラス繊維ろ紙で吸引ろ過し、ろ過後のろ紙を１０５℃で２時間加熱し、放冷した後の重量秤量結果より、算出した。ＰＯ４−Ｐは前記吸引ろ過後の脱水ろ液に対し、モリブデン青(アスコルビン酸還元)吸光光度法により測定した。電気伝導率は分析装置ＭＥＴＴＬＥＲ ＴＯＬＥＤＯ ＭＣ２２６（ＭＥＴＴＬＥＲ ＴＯＬＥＤＯ社、スイス）により、測定した。 Specifically, the pH was measured for the dehydrated filtrate collected by the glass electrode method. The M-alkalinity was measured by a method for measuring alkalinity [pH 4.8] (total alkalinity or M-alkalinity). SS was calculated from the results of weight weighing after suction-filtering the dehydrated filtrate with a glass fiber filter paper having a pore size of 1 μm, heating the filtered filter paper at 105 ° C. for 2 hours, and allowing it to cool. PO 4- P was measured by the molybdenum blue (ascorbic acid reduction) absorptiometry with respect to the dehydrated filtrate after suction filtration. The electrical conductivity was measured by an analyzer METTTLER TOREDO MC226 (METTTLER TOREDO, Switzerland).
Ｓ−Ｃａ（溶解性カルシウム濃度）とＳＯ４ ２−（硫酸イオン濃度）は、測定用試料として脱水ろ液を用いた以外は、汚泥Ａ〜Ｃに関する測定方法と同じ条件でそれぞれ測定した。各分析項目の測定温度は１８℃である。 S-Ca (soluble calcium concentration) and SO 4 2-(sulfate ion concentration), except that the measurement sample using a dehydration filtrate were measured under the same conditions as the measurement method of sludge A through C. The measurement temperature of each analysis item is 18 ° C.
各分析項目の測定結果を表３−１に示す。 The measurement results of each analysis item are shown in Table 3-1.
石膏の溶液中での平衡および溶解度積は以下の式で表される。
ＣａＳＯ４ ⇔ Ｃａ２＋ ＋ ＳＯ４ ２−
Ｋｓｐ ＝ ［Ｃａ２＋］［ＳＯ４ ２−］
The equilibrium and solubility product of gypsum in solution is expressed by the following formula.
CaSO 4 ⇔ Ca 2+ + SO 4 2-
K sp = [Ca 2+ ] [SO 4 2- ]
従って、Ｃａ２＋とＳＯ４ ２−のイオン積が飽和溶解度積Ｋｓｐより高い値であれば、石膏スケールが固形物として析出しやすいことになる。 Therefore, if the ion product of Ca 2+ and SO 4 2- is higher than the saturated solubility product K sp , the gypsum scale is likely to precipitate as a solid substance.
比較例１、３、５（高分子凝集剤のみ使用時）と実施例１−５、２−５、３−５（有機凝結剤使用時）を比較すると、上記含水率低減効果には差があるものの、表３の脱水ろ液の分析項目結果に顕著な差は確認されなかった。具体的には、いずれも溶解性カルシウム濃度の増加量は５．１〜１７．８ｍｇ／Ｌ、硫酸イオン濃度の増加量は０〜２．１ｍｇ／Ｌであった。 Comparing Comparative Examples 1, 3 and 5 (when using only the polymer flocculant) and Examples 1-5, 2-5 and 3-5 (when using the organic coagulant), there is a difference in the water content reduction effect. However, no significant difference was confirmed in the analysis item results of the dehydrated filtrate in Table 3. Specifically, the amount of increase in the soluble calcium concentration was 5.1 to 17.8 mg / L, and the amount of increase in the sulfate ion concentration was 0 to 2.1 mg / L.
しかし、無機凝集剤を使用した比較例２−２、４−２、６−２の脱水ろ液については、ｐＨの低下、Ｍ−アルカリ度の低下がみられ、特にＳ−ＣａとＳＯ４ ２−の大幅な増加（Ｓ−Ｃａ：５〜１０倍、ＳＯ４ ２−：２６〜８５７倍）が確認された。 However, the dehydration filtrate of Comparative Example 2-2,4-2,6-2 using inorganic coagulant, lowering of pH, decrease of M- alkalinity is observed, in particular S-Ca and SO 4 2 - a substantial increase in (S-Ca: 5~10 times, SO 4 2-: 26~857-fold) was observed.
また、有機凝結剤を使用した実施例のｐＨは７．５〜７．９であり、高分子凝集剤のみを使用した場合と比較してｐＨ変化量が０．１〜０．４にすぎなかったのに対し、無機凝集剤を使用した比較例のｐＨは４．１〜５．１であり、高分子凝集剤のみを使用した場合と比較してｐＨ変化量が２．３〜３．２もあった。 Further, the pH of the examples using the organic coagulant was 7.5 to 7.9, and the amount of pH change was only 0.1 to 0.4 as compared with the case where only the polymer flocculant was used. On the other hand, the pH of the comparative example using the inorganic flocculant was 4.1 to 5.1, and the amount of pH change was 2.3 to 3.2 as compared with the case where only the polymer flocculant was used. There was also.
有機凝結剤を使用した実施例では、上記測定値Ｓ−Ｃａ、ＳＯ４ ２−から算出されるイオン積ｂはいずれのろ液においても飽和溶解度積ａより低い値であり、理論的に石膏スケールは析出しないと考えられる。 In the embodiment using the organic coagulating agent, ion product b calculated the measured value S-Ca, the SO 4 2-is lower than the saturation solubility product a in any of the filtrate, theoretically gypsum scale Is not considered to precipitate.
他方、無機凝集剤を使用した比較例では、イオン積ｂがいずれも飽和溶解度積ａよりも高く、石膏スケールが析出すると考えられる。 On the other hand, in the comparative example using the inorganic flocculant, it is considered that the ion product b is higher than the saturated solubility product a and the gypsum scale is precipitated.
以上の結果より、有機凝結剤を使用した場合には、石膏スケール生成成分を低減でき、石膏スケール生成抑制効果を発揮することが確認された。また、無機凝集剤は鉄やアルミニウムなどの金属類を含むのに対し、有機凝結剤は金属類の濃度が極めて低いため、脱水ケーキを焼却した時にフェライトやアルミネートなどのクリンカの生成が抑制される上、リン酸が難溶性塩（ＦｅＰＯ４、ＡｌＰＯ４）となって除去されることもないので、脱水ケーキを堆肥として好適に再利用することもできる。 From the above results, it was confirmed that when an organic coagulant was used, the gypsum scale-forming component could be reduced and the gypsum scale-forming inhibitory effect was exhibited. In addition, the inorganic flocculant contains metals such as iron and aluminum, whereas the organic coagulant has an extremely low concentration of metals, so that the formation of clinker such as ferrite and aluminate is suppressed when the dehydrated cake is incinerated. In addition, since phosphoric acid is not removed as poorly soluble salts (FePO 4 , AlPO 4 ), the dehydrated cake can be suitably reused as compost.
１ａ、１ｂ：処理装置
４：汚泥供給手段
５ａ、５ｂ：凝集剤供給手段
６：濃縮手段
７ａ、７ｂ：凝結剤供給手段
９ａ、９ｂ：脱水手段
１１：凝集槽
１５：混和槽
１７：貯留槽
２１、２２、２３：供給配管
４４：排出口
４５：外胴ボウル（回転ボウル）
４６：スクリュー羽根
４７：内胴スクリュー
４８：ケーシング
４９ａ、４９ｂ：供給口
1a, 1b: Treatment device 4: Sludge supply means 5a, 5b: Coagulant supply means 6: Concentration means 7a, 7b: Coagulant supply means 9a, 9b: Dehydration means 11: Coagulation tank 15: Mixing tank 17: Storage tank 21 , 22, 23: Supply pipe 44: Discharge port 45: Outer body bowl (rotary bowl)
46: Screw blade 47: Inner body screw 48: Casing 49a, 49b: Supply port
Claims (6)
前記有機性汚泥に、ポリアミン系、ポリジアリルジメチルアンモニウムクロライド系、ポリジシアンジアミド系のいずれかの有機凝結剤成分を１０質量％以上の濃度で含む液体であると共に、少なくともカルシウムから選択される金属類の濃度が２００ｍｇ/Ｌ以下、硫酸イオン濃度が２００ｍｇ／Ｌ以下であって、かつ、ｐＨ４におけるカチオン度が５ｍｅｑ/ｇ以上の有機凝結剤を添加し、
前記高分子凝集剤及び前記有機凝結剤が添加された前記有機性汚泥を機械的に脱水して脱水ケーキを得ることを特徴とする有機性汚泥の脱水方法。 A cationic polymer flocculant or an amphoteric polymer flocculant is added to organic sludge having sludge properties with a soluble calcium concentration of 10 mg / L to 200 mg / L and a sulfate ion concentration of 0.1 mg / L to 200 mg / L. ,
The organic sludge is a liquid containing a polyamine-based, polydiallyldimethylammonium chloride-based, or polydicyandiamide-based organic coagulant component at a concentration of 10% by mass or more, and at least a metal selected from calcium. An organic coagulant having a concentration of 200 mg / L or less, a sulfate ion concentration of 200 mg / L or less, and a cation degree at pH 4 of 5 meq / g or more was added.
A method for dehydrating organic sludge, which comprises mechanically dehydrating the organic sludge to which the polymer flocculant and the organic coagulant are added to obtain a dehydrated cake.
ポリアミン系、ポリジアリルジメチルアンモニウムクロライド系、ポリジシアンジアミド系のいずれかの有機凝結剤成分を１０質量％以上の濃度で含む液体であると共に、少なくともカルシウムから選択される金属類の濃度が２００ｍｇ/Ｌ以下、硫酸イオン濃度が２００ｍｇ/Ｌ以下であって、かつ、ｐＨ４におけるカチオン度が５ｍｅｑ/ｇ以上 、２５℃における原液の粘度が５０ｍＰａ・ｓ以上である有機凝結剤。 An organic coagulant used for dehydrating organic sludge having a soluble calcium concentration of 10 mg / L to 200 mg / L and a sulfate ion concentration of 0.1 mg / L to 200 mg / L.
It is a liquid containing any of polyamine-based, polydiallyldimethylammonium chloride-based, and polydicyandiamide-based organic coagulant components at a concentration of 10% by mass or more, and at least the concentration of metals selected from calcium is 200 mg / L or less. An organic coagulant having a sulfate ion concentration of 200 mg / L or less, a cation degree at pH 4 of 5 meq / g or more, and a stock solution viscosity of 50 mPa · s or more at 25 ° C.
前記高分子凝集剤により凝集した前記有機性汚泥を濃縮し、濃縮汚泥を得る濃縮手段と、
前記濃縮汚泥に、ポリアミン系、ポリジアリルジメチルアンモニウムクロライド系、ポリジシアンジアミド系のいずれかの有機凝結剤成分を１０質量％以上の濃度で含む液体であると共に、少なくともカルシウムから選択される金属類の濃度が２００ｍｇ/Ｌ以下、硫酸イオン濃度が２００ｍｇ／Ｌ以下であって、かつ、ｐＨ４におけるカチオン度 が５ｍｅｑ/ｇ以上の有機凝結剤を添加する凝結剤供給手段と、
前記有機凝結剤を添加後の前記濃縮汚泥が供給され、機械脱水により脱水ケーキを得る脱水手段と、を有し、
前記濃縮汚泥に、前記有機凝結剤を添加することにより、前記機械脱水で発生する石膏スケールの生成を低減することを特徴とする有機性汚泥の処理装置。 Coagulant supply means for adding a cationic polymer flocculant or an amphoteric polymer flocculant to organic sludge having a soluble calcium concentration of 10 mg / L to 200 mg / L and a sulfate ion concentration of 0.1 mg / L to 200 mg / L. When,
Concentration means for concentrating the organic sludge aggregated by the polymer flocculant to obtain concentrated sludge,
The concentrated sludge is a liquid containing any one of polyamine-based, polydiallyldimethylammonium chloride-based, and polydicyandiamide-based organic coagulant components at a concentration of 10% by mass or more, and at least the concentration of metals selected from calcium. Is 200 mg / L or less, the sulfate ion concentration is 200 mg / L or less, and the coagulant supply means for adding an organic coagulant having a cationic degree at pH 4 of 5 meq / g or more.
The concentrated sludge after adding the organic coagulant is supplied, and has a dewatering means for obtaining a dewatered cake by mechanical dewatering.
A device for treating organic sludge, which comprises reducing the formation of gypsum scale generated by the mechanical dehydration by adding the organic coagulant to the concentrated sludge.
溶解性カルシウム濃度が１０ｍｇ／Ｌ〜２００ｍｇ／Ｌ、硫酸イオン濃度が０．１ｍｇ／Ｌ〜２００ｍｇ／Ｌの汚泥性状を有する有機性汚泥を前記脱水手段へ供給する汚泥供給手段と、
カチオン性高分子凝集剤あるいは両性高分子凝集剤を前記脱水手段へ供給する凝集剤供給手段と、
前記高分子凝集剤が添加された前記有機性汚泥に、ポリアミン系、ポリジアリルジメチルアンモニウムクロライド系、ポリジシアンジアミド系のいずれかの有機凝結剤成分を１０質量％以上の濃度で含む液体であると共に、少なくともカルシウムから選択される金属類の濃度が２００ｍｇ/Ｌ以下、硫酸イオン濃度が２００ｍｇ／Ｌ以下であって、 かつ、ｐＨ４におけるカチオン度が５ｍｅｑ/ｇ以上の有機凝結剤を供給する凝結剤供給手段と、を有し、
前記脱水手段は、前記有機性汚泥を前記高分子凝集剤で凝集すると共に濃縮し、更に前記有機凝結剤を浸透させて脱水することを特徴とする有機性汚泥の処理装置。 Dehydrating means equipped with a centrifugal dehydrator and
A sludge supply means for supplying organic sludge having sludge properties having a soluble calcium concentration of 10 mg / L to 200 mg / L and a sulfate ion concentration of 0.1 mg / L to 200 mg / L to the dehydration means.
A flocculant supply means for supplying a cationic polymer flocculant or an amphoteric polymer flocculant to the dehydration means, and a coagulant supply means.
The organic sludge to which the polymer flocculant is added is a liquid containing any one of polyamine-based, polydiallyldimethylammonium chloride-based, and polydicyandiamide-based organic coagulant components at a concentration of 10% by mass or more, and is a liquid. Coagulant supplying means for supplying an organic coagulant having a concentration of at least metals selected from calcium of 200 mg / L or less, a sulfate ion concentration of 200 mg / L or less, and a cationic degree of 5 meq / g or more at pH 4. And have
The dehydration means is an organic sludge treatment apparatus, which comprises agglomerating and concentrating the organic sludge with the polymer flocculant, and further permeating the organic coagulant to dehydrate the organic sludge.
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