JP2002028696A - Method for treating sludge - Google Patents
Method for treating sludgeInfo
- Publication number
- JP2002028696A JP2002028696A JP2000215640A JP2000215640A JP2002028696A JP 2002028696 A JP2002028696 A JP 2002028696A JP 2000215640 A JP2000215640 A JP 2000215640A JP 2000215640 A JP2000215640 A JP 2000215640A JP 2002028696 A JP2002028696 A JP 2002028696A
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- JP
- Japan
- Prior art keywords
- sludge
- treatment
- odor
- cake
- agent
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Treatment Of Sludge (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、汚泥濃縮槽以降の
汚泥処理プロセスにおける汚泥スラリーおよび汚泥の脱
水ケーキの臭気発生を防止することができる汚泥処理方
法に関し、さらに詳しくは、下水処理場などの汚泥スラ
リーを脱水するまでの各プロセスと脱水ケーキの貯留、
保管で発生する硫化水素やメチルメルカプタン等の悪臭
物質に由来する臭気の発生を全プロセスに亘って効果的
に防止することができる汚泥処理方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sludge treatment method capable of preventing odor generation of a sludge slurry and a sludge dewatered cake in a sludge treatment process after a sludge concentration tank. Each process until sludge slurry is dewatered and storage of dewatered cake,
The present invention relates to a sludge treatment method capable of effectively preventing the generation of odor derived from malodorous substances such as hydrogen sulfide and methyl mercaptan generated during storage throughout the entire process.
【０００２】[0002]
【従来の技術】下水処理場、し尿処理場や食品・紙パル
プ工場等の有機性排水の処理に際しては、各種の汚泥が
発生し、これらの汚泥の処理プロセス（汚泥スラリー，
汚泥脱水ケーキ）が悪臭の主たる発生源となっている。
図１に下水処理場の汚泥処理プロセスの例と臭気発生箇
所を記載する。図１に示した濃縮初沈汚泥貯留槽、
汚泥混合貯留槽、汚泥供給タンク、汚泥脱水機で
は、汚泥スラリー中に存在する硫化水素を主とする悪臭
物質が揮散し、作業環境の悪化をきたしている。同時
に、揮散した硫化水素による電気関係設備の腐食、硫化
水素が生物酸化されて生ずる硫酸による機器腐食も生ず
る。脱水ケーキでは、貯留、保管中に腐敗が進み、含イ
オウ蛋白質の分解により主としてメチルメルカプタンが
発生する。2. Description of the Related Art Various types of sludge are generated in the treatment of organic wastewater from sewage treatment plants, human waste treatment plants, food and pulp mills, etc., and these sludge treatment processes (sludge slurry,
Sludge dewatered cake) is a major source of foul odors.
FIG. 1 shows an example of a sludge treatment process in a sewage treatment plant and odor generation locations. First concentrated sludge storage tank shown in FIG. 1,
In a sludge mixing storage tank, a sludge supply tank, and a sludge dewatering machine, malodorous substances mainly including hydrogen sulfide present in the sludge slurry are volatilized, thereby deteriorating the working environment. At the same time, corrosion of electrical equipment due to the volatilized hydrogen sulfide and equipment corrosion due to sulfuric acid generated by the biooxidation of hydrogen sulfide also occur. In the dehydrated cake, decay progresses during storage and storage, and methyl mercaptan is mainly generated due to decomposition of the sulfur-containing protein.
【０００３】そこでこれらの問題を解決するために提案
された従来の技術を以下に説明するが、汚泥の臭気分
解、発生防止を〜の汚泥スラリー系（以下、スラリ
ー系と記す）と脱水ケーキ系（以下、ケーキ系と記す）
に分けて説明する。Therefore, conventional techniques proposed to solve these problems will be described below. Sludge slurry systems (hereinafter referred to as "slurry systems") and dewatering cake systems are provided for preventing odor decomposition and generation of sludge. (Hereinafter referred to as cake type)
Will be described separately.
【０００４】スラリー系の臭気処理剤としては、過酸化
水素、亜塩素酸塩等の強力な酸化剤や鉄、亜鉛、銅等の
金属塩が知られており、実際に適用されている。亜塩素
酸塩は即効性に優れているが、薬剤はすぐに消費され、
〜の長い滞留時間に亘る臭気防止は不可能であっ
た。過酸化水素は反応性がやや遅い分、臭気低減の効果
に持続性があるが、それでもその効果の持続は１時間程
度に過ぎず、〜の長い滞留時間に亘る臭気防止は不
可能であった。また、これらの酸化剤はケーキ系に対し
てほとんど無効であった。一方、金属塩は、スラリー
系、ケーキ系の両者に対して効果を有するが、銅塩を除
いて効果水準が低く、満足できるものではなかった。銅
塩は添加量を増加すれば効果は優れるものの、重金属で
あるため、環境汚染の問題から一般には受け入れ難い方
法である。As a slurry-based odor treating agent, a strong oxidizing agent such as hydrogen peroxide and chlorite and a metal salt such as iron, zinc and copper are known and actually used. Chlorite is excellent for immediate action, but the drug is consumed immediately,
It was not possible to prevent odor over a long residence time. Hydrogen peroxide has a slightly slower reactivity, so the effect of reducing odor is persistent, but the effect lasts only about 1 hour, and it is impossible to prevent odor over a long residence time. . Also, these oxidants were almost ineffective for the cake system. On the other hand, the metal salt has an effect on both the slurry system and the cake system, but the effect level was low except for the copper salt and was not satisfactory. Although the copper salt is effective when the amount of addition is increased, it is a method generally unacceptable due to the problem of environmental pollution because it is a heavy metal.
【０００５】また、ケーキ系の臭気処理剤・方法として
は、各種有機系殺菌・静菌剤並びにそれらを用いた方法
が提案されているが、人体に対する安全性の問題からシ
ャンプーの配合剤としても使用されているジンクピリチ
オンがよく使われている。しかし、このジンクピリチオ
ン単独では効果が十分でないため、特開２０００−７０
９９９号公報に示されるように亜鉛塩、鉄塩等の金属塩
との併用が行われているが、ケーキ系の臭気防止期間は
最大２日程度で、汚泥の性状によっては効果が不十分で
あった。As the cake-based odor-treating agents and methods, various organic bactericidal / bacteriostatic agents and methods using them have been proposed. However, due to the problem of safety to the human body, they are also used as compounding agents for shampoos. The zinc pyrithione used is often used. However, the effect of zinc pyrithione alone is not sufficient.
As described in Japanese Patent Application Laid-Open No. 999, it is used in combination with metal salts such as zinc salt and iron salt, but the odor prevention period of the cake system is about 2 days at the maximum, and the effect is insufficient depending on the properties of sludge. there were.
【０００６】さらに、スラリー系、ケーキ系の両方の臭
気防止を図る方法としては、特開平５−２５３５９９号
公報に示されるように亜塩素酸塩と次亜塩素酸塩、およ
びさらにケーキ系の効果を高めるために静菌系消臭剤を
併用する方法が提案されている。しかし、この方法での
ケーキ系の臭気防止効果は、実用コストの静菌剤を併用
しても室内評価レベルで２〜３日に過ぎず、その効果の
持続性が十分ではなかった。また、図１のの臭気対
策はできなかった。Further, as a method for preventing odor of both the slurry type and the cake type, as disclosed in Japanese Patent Application Laid-Open No. 5-253599, the effects of chlorite and hypochlorite, and further, the effect of the cake type are disclosed. There has been proposed a method in which a bacteriostatic deodorant is used in combination in order to increase the odor. However, the odor control effect of the cake system by this method was only 2-3 days at the indoor evaluation level even when a bacteriostatic agent of practical cost was used in combination, and the effect was not sufficiently persistent. Further, the odor countermeasures shown in FIG. 1 could not be taken.
【０００７】[0007]
【発明が解決しようとする課題】前述のようにスラリー
系およびケーキ系の両方の臭気防止を全プロセスに亘っ
て効果的に防止することができる従来技術はなかった。
そこで本発明は、下水処理場等の汚泥の濃縮後から脱水
および脱水ケーキの貯留、搬出さらにケーキ搬入先に至
る汚泥処理プロセス全体に亘って臭気を防止できる汚泥
処理方法を提案することを目的とする。また、使用する
薬剤が人体、環境に対して安全であることを目標とす
る。As described above, there is no prior art which can effectively prevent the odor of both the slurry system and the cake system throughout the entire process.
Therefore, an object of the present invention is to propose a sludge treatment method capable of preventing odor over the entire sludge treatment process from the concentration of sludge in a sewage treatment plant or the like to the dehydration and storage of dewatered cakes, unloading, and further, to the cake destination. I do. The goal is to use drugs that are safe for the human body and the environment.
【０００８】[0008]
【課題を解決するための手段】本出願人は、これまでの
臭気防止剤が既に発生している臭気の分解、固定、即ち
消臭剤との観点から検討が行われていたのに対し、臭気
発生防止方法、防止剤の観点から臭気発生に直接的又は
間接的に関与する微生物活動を停止させ、且つ人体およ
び環境への影響の少ない手段とその組み合わせについて
鋭意検討し、有効な汚泥処理方法を得た。即ち本発明
は、請求項１に示すように、汚泥のｐＨを低下させて
５．５以下に調整するとともに、汚泥中に静菌剤を存在
させることにより、汚泥からの臭気の発生を防止させる
ことを特徴とする汚泥処理方法に関するものである。
尚、通常汚泥ｐＨは５〜６．５であり、そもそもｐＨ低
下剤を添加する以前からｐＨ５程度以下のものもある
が、当初からｐＨ５．５以下の汚泥に対してもさらにｐ
Ｈを低下させる場合も適用対象としている。また、請求
項２に示すように、前記静菌剤が少なくとも亜硝酸イオ
ンである方法をも提案する。また、請求項３に示すよう
に、前記静菌剤が少なくとも有機系静菌剤と、亜硝酸イ
オンである方法をも提案する。また、請求項４に示すよ
うに、少なくとも有機系二塩基酸によって汚泥を所定ｐ
Ｈに低下させる方法をも提案する。また、請求項５に示
すように、少なくとも第二鉄塩によって汚泥を所定ｐＨ
に低下させる方法をも提案する。また、請求項６に示す
ように、さらに、高分子凝集剤により凝集処理し、凝集
処理後の汚泥ｐＨを５以下に調整する方法をも提案す
る。また、請求項７に示すように、さらに、分子内に架
橋構造が導入されたカチオン系高分子凝集剤により汚泥
脱水処理する方法をも提案する。また、請求項８に示す
ように、さらに、分子内にカチオン基およびアニオン基
が導入された両性高分子凝集剤により汚泥脱水処理する
方法をも提案する。Means for Solving the Problems The applicant of the present invention has studied the decomposition and fixing of the odor already generated by the odor control agent, that is, from the viewpoint of the deodorant, Effective sludge treatment method by stopping microbial activity that directly or indirectly contributes to odor generation from the viewpoint of odor generation prevention method and inhibitor, and by studying means and combinations that have little effect on human body and environment I got That is, according to the present invention, as described in claim 1, the pH of the sludge is adjusted to 5.5 or less and the bacteriostatic agent is present in the sludge, thereby preventing the generation of odor from the sludge. The present invention relates to a sludge treatment method characterized by the above.
The pH of the sludge is usually 5 to 6.5, and there is a pH of about 5 or less even before the addition of the pH reducing agent.
The case where H is decreased is also applied. Further, a method is proposed in which the bacteriostatic agent is at least a nitrite ion. Further, the present invention also proposes a method wherein the bacteriostatic agent is at least an organic bacteriostatic agent and nitrite ions. Further, as described in claim 4, the sludge is at least predetermined pulverized with an organic dibasic acid.
A method for lowering to H is also proposed. Further, as described in claim 5, the sludge is brought to a predetermined pH with at least a ferric salt.
We also propose a way to reduce it. Further, as set forth in claim 6, a method of further performing a flocculation treatment with a polymer flocculant and adjusting the sludge pH after the flocculation treatment to 5 or less is proposed. Further, as set forth in claim 7, a method for dewatering sludge by using a cationic polymer flocculant having a crosslinked structure introduced in the molecule is further proposed. Further, as set forth in claim 8, a method of dewatering sludge by using an amphoteric polymer flocculant having a cation group and an anion group introduced into a molecule is further proposed.
【０００９】腐敗、臭気発生に係わる硫酸還元菌や一般
の微生物の至適ｐＨが概ね中性域にあることから、ｐＨ
低下によるスラリー系の臭気防止効果を、各種ｐＨ条
件、各種臭気処理剤にて検討したところ、使用したｐＨ
低下剤の種類にかかわらずｐＨ低下による臭気防止時間
の延長（持続性）が確認され、ｐＨとして５．５以下、
好ましくは４．５未満が有効であることを見いだした。
尚、ｐＨが３．５未満になると、高分子凝集剤による汚
泥の凝集、固液分離が不可能になる。したがって、凝
集、固液分離工程よりも前段においてｐＨ調整する際に
は、ｐＨは３．５以上にすることが好ましい。しかしな
がら、後述する通り、凝集、固液分離工程よりも後段で
ｐＨ調整する場合はこの限りではない。また、臭気発生
に係わる硫酸還元菌に対して静菌剤として作用する亜硝
酸塩を用いた場合、ｐＨ低下により亜硝酸塩の消費速度
が低下し、臭気防止時間が著しく延長できることを見い
だした。但し、亜硝酸塩以外の臭気処理剤、例えば過酸
化水素、亜塩素酸塩等の酸化剤、亜鉛塩等の金属塩で
は、ｐＨ低下での効果はあるものの、有用な相加又は相
乗効果は認められなかった。[0009] Since the optimum pH of sulfate-reducing bacteria and general microorganisms involved in spoilage and odor generation is generally in the neutral range,
The odor prevention effect of the slurry system due to the decrease was examined under various pH conditions and various odor treatment agents.
Regardless of the type of the reducing agent, the extension (persistence) of the odor prevention time due to the decrease in pH was confirmed.
Preferably less than 4.5 has been found to be effective.
If the pH is less than 3.5, sludge aggregation and solid-liquid separation by the polymer flocculant become impossible. Therefore, when adjusting the pH before the aggregation and solid-liquid separation steps, the pH is preferably set to 3.5 or more. However, as described later, this is not the case when the pH is adjusted at a stage subsequent to the aggregation and solid-liquid separation steps. In addition, it has been found that when nitrite acting as a bacteriostatic agent against sulfate-reducing bacteria involved in odor generation is used, the consumption rate of nitrite decreases due to a decrease in pH, and the odor prevention time can be significantly extended. However, odor treatment agents other than nitrites, for example, oxidizing agents such as hydrogen peroxide and chlorite, and metal salts such as zinc salts, although effective in lowering the pH, show useful additive or synergistic effects. I couldn't.
【００１０】前記知見に基づき、ｐＨ低下によるケーキ
系の臭気防止効果についても、各種ｐＨ条件、各種臭気
処理剤について検討したところ、ｐＨ低下剤の種類にか
かわらずｐＨ低下による臭気防止時間の延長（持続性）
が確認され、ｐＨ５．５以下、好ましくは４．５未満が
有効であることを見いだした。尚、亜硝酸塩以外の酸化
剤、亜鉛塩などを併用しても、ｐＨ低下での効果はある
ものの、有用な相加又は相乗効果は認められなかった。[0010] Based on the above findings, the effect of preventing the odor of the cake system due to the decrease in pH was examined for various pH conditions and various odor treatment agents. Persistence)
Was found, and it was found that pH 5.5 or less, preferably less than 4.5 was effective. In addition, even when an oxidizing agent other than nitrite, a zinc salt, and the like were used in combination, a useful additive or synergistic effect was not recognized, although there was an effect in lowering the pH.
【００１１】一方、人体および環境に対する影響の小さ
い静菌剤は、概して菌の活動抑制作用が小さいことが知
られている。しかし、ソルビン酸、安息香酸、パラオキ
シ安息香酸、デヒドロ酢酸、ジンクピリチオンは、人体
および環境に対する影響が小さいにもかかわらず、亜硝
酸塩の併用とｐＨ低下で著しく効果が向上することを見
いだした。即ち亜硝酸塩と上述の有機系静菌剤とを組み
合わせてケーキ系の臭気処理剤として好適に用いること
ができる。尚、亜硝酸塩は、少なくともｐＨ低下剤の添
加と同時であるか、或いはｐＨ低下剤を添加した後であ
れば、脱臭対象箇所又はその直前の位置に添加しても良
いし、汚泥スラリー中に添加しても良い。また、有機系
静菌剤は、添加場所に限定はなく、例えば送泥ポンプの
出口の送泥ラインや、脱水直前の凝集反応槽に添加する
ことができるが、脱水工程の直前に添加することが好ま
しい。即ち、この有機系静菌剤を添加後、脱水工程に流
入するまでの時間は短いほど良く、温度条件にも依存す
るが、常温で１５分以内に、さらには３分以内にするこ
とがより好ましい。On the other hand, it is known that a bacteriostatic agent having a small effect on the human body and the environment generally has a small activity of suppressing the activity of bacteria. However, sorbic acid, benzoic acid, p-hydroxybenzoic acid, dehydroacetic acid, and zinc pyrithione have been found to have significantly improved effects when combined with nitrite and lowering the pH, despite having little effect on the human body and the environment. That is, a combination of nitrite and the above-mentioned organic bacteriostatic agent can be suitably used as a cake odor treatment agent. Incidentally, the nitrite may be added at least at the same time as the addition of the pH-lowering agent, or after the addition of the pH-lowering agent, to the deodorization target site or a position immediately before the deodorization target, or in the sludge slurry. It may be added. Further, the organic bacteriostatic agent is not limited to the place where it is added, and can be added to, for example, a mud feed line at the outlet of a mud pump or an agglutination reaction tank just before dehydration, but it should be added just before the dehydration step. Is preferred. That is, the shorter the time from the addition of the organic bacteriostatic agent to the flow into the dehydration step, the better, and it depends on the temperature conditions. preferable.
【００１２】前記のようにｐＨ低下剤の種類、即ち塩
酸、硫酸等の無機酸、有機酸、或いは第二鉄塩の何れで
も、ｐＨレベルが同じであればほぼ同一の効果となる
が、強酸である無機酸を使用する場合、少しでも過剰添
加になるとｐＨが３．５未満に低下し易く、高分子凝集
剤による汚泥の凝集、固液分離が不可能になる。そのた
め、弱酸を使用することが望ましく、さらに取り扱いの
安全性から、有機酸、特にフマル酸、アジピン酸、コハ
ク酸、リンゴ酸等の有機系二塩基酸が有効であることを
見いだした。また、ｐＨは低い方が臭気防止効果の持続
時間は長くなり、臭気防止の観点からはｐＨは低い方が
好ましい。しかし、論述する通り、ｐＨが低い程、特に
ｐＨが４以下の条件では、汚泥の高分子凝集剤による凝
集効果が不良となり、汚泥の脱水処理に不都合が生じ
る。そこで、本出願人は種々の酸および高分子凝集剤を
検討したところ、酸として第二鉄塩を使用した場合には
論述する両性高分子凝集剤を使用することにより、ｐＨ
３．５程度まで汚泥の凝集、脱水処理が可能であること
を見いだした。As described above, the same pH-lowering agent, ie, an inorganic acid such as hydrochloric acid or sulfuric acid, an organic acid, or a ferric salt has almost the same effect at the same pH level. When an inorganic acid is used, the pH tends to drop to less than 3.5 if it is added in a slight excess, so that sludge aggregation and solid-liquid separation by a polymer flocculant become impossible. Therefore, it has been found that it is desirable to use a weak acid, and that organic acids, especially organic dibasic acids such as fumaric acid, adipic acid, succinic acid and malic acid are effective from the viewpoint of handling safety. In addition, the lower the pH, the longer the duration of the odor prevention effect, and the lower the pH, the more preferable from the viewpoint of odor prevention. However, as will be discussed, as the pH is lower, especially under conditions where the pH is 4 or less, the flocculation effect of the sludge by the polymer flocculant becomes poor, and the sludge is dewatered. Therefore, the present applicant examined various acids and polymer flocculants, and when a ferric salt was used as the acid, the pH was increased by using the amphoteric polymer flocculant to be discussed.
It has been found that sludge can be coagulated and dehydrated up to about 3.5.
【００１３】スラリー系の汚泥ｐＨを低下させるには、
前記ｐＨ低下剤を亜硝酸塩と同時であるか或いはその前
段であって、脱臭対象箇所又はその直前の位置に添加し
ても良いし、汚泥スラリー中に添加しても良いが、特に
ケーキ系のｐＨを大きく低下させてケーキ臭気防止期間
を効果的且つ経済的に高める方法として、脱水ケーキ又
はベルトプレス脱水の重力ろ過物に対して前記ｐＨ低下
剤、特に第二鉄塩或いは前記有機系二塩基酸粉末を添
加、混合する方法を採ることができる。本方法を採用す
ることによって、ｐＨは３．５未満にまで低下すること
が可能となる。また、スラリー系において、ｐＨ低下剤
（前添加）を添加した効果がケーキ系において持続して
いる際には特に必要ない場合もあるが、さらなる効果の
持続を目的としてｐＨ低下剤（後添加）を追加する場合
も前記と同様の方法を採れば良い。In order to lower the pH of the slurry in the slurry system,
The pH-lowering agent may be added at the same time as or before the nitrite and at the site to be deodorized or at a position immediately before the same, or may be added to the sludge slurry. As a method of effectively and economically increasing the pH by greatly lowering the cake odor prevention period, the pH lowering agent, particularly a ferric salt or the organic dibasic, is used for gravity filtration of dewatered cake or belt press dewatering. A method of adding and mixing an acid powder can be adopted. By employing this method, the pH can be reduced to less than 3.5. In the slurry system, the effect of adding the pH lowering agent (pre-addition) may not be particularly necessary when the effect is maintained in the cake system, but in order to maintain the effect further, the pH lowering agent (post-addition) is used. May be added in the same manner as described above.
【００１４】汚泥ｐＨが低下することで、通常のカチオ
ン系高分子凝集剤による凝集、固液分離効果が低下す
る。この時、分子内に架橋構造が一定以上導入されたカ
チオン系高分子凝集剤を用いることにより、良好な凝
集、固液分離、脱水性が得られることを見いだした。
尚、このような高分子凝集剤としては、現在エマルジョ
ンポリマーの形態でしか製品化されていない。また、特
にｐＨ低下剤として第二鉄塩を用いる場合には、分子内
にカチオン基およびアニオン基が導入された両性高分子
凝集剤を用いることにより、低ｐＨ域の広いｐＨ範囲で
良好な凝集、固液分離、脱水が行えることも見いだし
た。[0014] When the pH of the sludge decreases, the flocculation and solid-liquid separation effects of a usual cationic polymer flocculant decrease. At this time, it was found that good coagulation, solid-liquid separation and dehydration can be obtained by using a cationic polymer coagulant having a crosslinked structure introduced into a molecule in a certain amount or more.
Incidentally, such a polymer flocculant is currently commercialized only in the form of an emulsion polymer. In particular, when a ferric salt is used as a pH lowering agent, by using an amphoteric polymer flocculant in which a cationic group and an anionic group are introduced into a molecule, good coagulation can be achieved in a wide pH range of a low pH range. It has also been found that solid-liquid separation and dehydration can be performed.
【００１５】[0015]
【発明の実施の形態】図１は、前記のように下水処理場
の汚泥処理プロセスの一例を示すフローであるが、原水
は、最初沈殿池へ導かれ、初沈汚泥が分離される。最初
沈殿池の上澄水は、必要に応じて凝集剤を添加した後、
エアレーションタンクへ送られ、活性汚泥法により生物
的処理が行われる。エアレーションタンクの処理水は、
必要に応じて凝集剤を添加した後、最終沈殿池へ送ら
れ、汚泥が分離され、上澄水はそのまま或いは必要な処
理が施された後、放流される。分離された汚泥は、一部
が返送汚泥としてエアレーションタンクに返送され、残
余は余剰汚泥として余剰汚泥貯槽に貯留され、機械濃縮
された後、濃縮余剰汚泥貯槽に貯留される。最初沈殿池
から分離された初沈汚泥は、重力濃縮された後、濃縮
初沈汚泥貯槽に導かれる。この濃縮初沈汚泥貯槽から
初沈汚泥が、濃縮余剰汚泥貯槽から余剰汚泥がそれぞれ
汚泥混合貯留槽に送られ、混合された混合汚泥が汚
泥供給タンクへ移送され、脱水機にて脱水され、脱水
ケーキホッパーから脱水ケーキとして搬出される。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a flow chart showing an example of a sludge treatment process in a sewage treatment plant as described above. Raw water is first guided to a sedimentation basin, and primary sludge is separated. First, the supernatant water of the sedimentation basin is added after adding a flocculant if necessary.
It is sent to the aeration tank and biologically treated by the activated sludge method. The treated water of the aeration tank is
After adding a flocculant as needed, it is sent to the final sedimentation basin, the sludge is separated, and the supernatant water is discharged as it is or after necessary treatment. A part of the separated sludge is returned to the aeration tank as return sludge, and the remainder is stored in a surplus sludge storage tank as surplus sludge, and after being mechanically concentrated, is stored in a concentrated surplus sludge storage tank. The initial sludge separated from the first sedimentation basin is concentrated by gravity and then guided to a concentrated primary sludge storage tank. The primary sludge from the concentrated primary sludge storage tank and the excess sludge from the concentrated excess sludge storage tank are respectively sent to the sludge mixing storage tank, and the mixed mixed sludge is transferred to the sludge supply tank, dewatered by the dehydrator, and dewatered. It is carried out as a dehydrated cake from the cake hopper.
【００１６】〔１〕本発明はこのような下水汚泥の他、
し尿、食品、紙パルプ工場等の有機汚泥全般に適用でき
る。汚泥のｐＨは下水の混合生汚泥（初沈汚泥と余剰汚
泥の混合汚泥）では通常５．０〜６．５の範囲にあり、
その他の有機汚泥のｐＨも概ね同じ範囲にある。したが
って、前述の通り、もともとｐＨが５程度以下の汚泥も
存在するが、さらにｐＨを低下させることによって臭気
発生防止時間は更に延長させることができるため、本発
明では、このようなｐＨが低い汚泥に対してもｐＨ低下
剤を添加して更にｐＨを低下させることをも含むもので
ある。スラリー系において、十分な期間臭気を防止させ
るためには、ｐＨ調整には、即ちｐＨ低下剤としては、
亜硝酸分解作用を有するスルファミン酸を除く、どのよ
うな酸を用いても臭気防止効果には大きな差はない。ケ
ーキ系の臭気防止時間の延長には、さらに大きくｐＨを
低下し、４．０程度以下に調整すると非常に有効であ
る。しかし、このｐＨ４．０以下の条件では、ｐＨ低下
剤として第二鉄塩を用いてｐＨを下げた場合を除き、ど
のような高分子凝集剤を用いても汚泥を機械脱水可能な
レベルまで凝集させることができない。ｐＨ低下剤とし
て第二鉄塩を用いた場合はｐＨ３．５程度までなら、分
子内にカチオン基およびアニオン基を導入した両性高分
子凝集剤で凝集可能である。[1] The present invention provides, in addition to such sewage sludge,
Applicable to all kinds of organic sludge such as night soil, food, pulp and paper mills. The pH of sludge is usually in the range of 5.0 to 6.5 for mixed raw sludge (mixed sludge of primary settled sludge and excess sludge) in sewage,
The pH of other organic sludges is also in substantially the same range. Therefore, as described above, there is originally sludge having a pH of about 5 or less, but the odor generation prevention time can be further extended by further lowering the pH. This also includes adding a pH reducing agent to further lower the pH. In a slurry system, in order to prevent odor for a sufficient period, pH adjustment, that is, as a pH lowering agent,
There is no significant difference in the odor control effect using any acid except for sulfamic acid having a nitrous acid decomposing action. To extend the odor prevention time of the cake system, it is very effective to further lower the pH and adjust it to about 4.0 or less. However, under the condition of pH 4.0 or less, sludge is flocculated to a level at which mechanical sludge can be dewatered using any polymer flocculant, except when the pH is lowered using a ferric salt as a pH lowering agent. I can't let it. When a ferric salt is used as the pH lowering agent, if the pH is up to about 3.5, it can be flocculated with an amphoteric polymer flocculant having a cationic group and an anionic group introduced into the molecule.
【００１７】〔２〕ケーキ系の臭気発生時間延長が特に
要求される場合には、脱水ケーキ、或いは汚泥の凝集、
ろ過後の濃縮物に更にｐＨ低下剤を添加して混合するこ
とにより、汚泥の凝集、固液分離に影響を与えることな
くケーキのｐＨを大きく低下でき、臭気発生防止時間を
延長できる。例えばこのｐＨ低下剤の添加は、ベルトプ
レス脱水機の重力脱水部が好ましい。また、前述のよう
に脱水ケーキに第二鉄塩或いは酸を添加することも可能
であるが、この場合には混合装置が必要となる。[2] When it is particularly required to extend the odor generation time of the cake system, dewatered cake or coagulation of sludge,
By further adding and mixing a pH-lowering agent to the filtered concentrate, the pH of the cake can be significantly reduced without affecting sludge aggregation and solid-liquid separation, and the odor generation prevention time can be extended. For example, the addition of the pH lowering agent is preferably performed in a gravity dewatering section of a belt press dehydrator. As described above, it is possible to add a ferric salt or an acid to the dewatered cake, but in this case, a mixing device is required.
【００１８】〔３〕前述のｐＨ低下剤にて汚泥スラリー
のｐＨを低下させた場合、一般的に高分子凝集剤として
使用されるカチオンポリマーでは凝集不良を生ずる。こ
れは、カチオン基の反応相手である汚泥のアニオン（カ
ルボキシル基）がｐＨ低下に応じて非解離となるためと
考えられる。このような条件下では、分子内に架橋構造
が一定以上導入されたカチオン系高分子凝集剤（エマル
ジョンポリマー）が特異的に有効である。このような架
橋構造が導入された高分子凝集剤の物性は、次の通りで
ある。エマルジョンポリマーを１０モルＮａＣｌ中にポ
リマー成分として０．５％に溶解し、これを１３０００
ｒｐｍで１時間超遠心分離を行う。この上部液を採取し
て２１５ｎｍで紫外線吸光度（Ａ）を測定する。超遠心
処理をしない溶液の吸光度をＢとしてΔＵＶを次式で求
める。 ΔＵＶ＝（Ｂ−Ａ）／Ｂ ΔＵＶが０．３以上のポリマーが本発明の架橋構造を一
定以上有するエマルジョンポリマーである。因みに通常
（分子内に架橋構造を有しない）のカチオン系高分子凝
集剤であるエマルジョンポリマー及び粉末ポリマーのΔ
ＵＶは０．１未満である。また、特にｐＨ低下剤として
第二鉄塩を用いた場合は、分子内にカチオン基およびア
ニオン基が導入された両性高分子凝集剤（ポリマー）が
良好な凝集性を示し、両性ポリマー中のアニオン比率を
高めることでｐＨ４程度以下でも凝集、脱水が可能であ
る。尚、このような高分子凝集剤は、有機系静菌剤と同
じ位置に添加しても良いし、別途凝集反応槽を設け、そ
こに添加しても良い。[3] When the pH of the sludge slurry is lowered by the above-mentioned pH lowering agent, poor coagulation occurs in a cationic polymer generally used as a high molecular coagulant. This is presumably because the anion (carboxyl group) of the sludge, which is the reaction partner of the cationic group, becomes non-dissociated as the pH decreases. Under such conditions, a cationic polymer flocculant (emulsion polymer) having a crosslinked structure introduced into a molecule in a certain amount or more is specifically effective. The physical properties of the polymer flocculant into which such a crosslinked structure has been introduced are as follows. The emulsion polymer was dissolved in 10 mol NaCl as a polymer component in 0.5%, and this was dissolved in 13000.
Ultracentrifuge for 1 hour at rpm. The upper solution is collected and the ultraviolet absorbance (A) is measured at 215 nm. The ΔUV is determined by the following equation, where B is the absorbance of the solution without ultracentrifugation. ΔUV = (BA) / B A polymer having a ΔUV of 0.3 or more is an emulsion polymer having a crosslinked structure of the present invention in a certain amount or more. Incidentally, Δ of emulsion polymer and powder polymer, which are normal (having no crosslinked structure in the molecule) cationic polymer flocculant, is used.
UV is less than 0.1. In particular, when a ferric salt is used as a pH-lowering agent, an amphoteric polymer flocculant (polymer) having a cation group and an anion group introduced therein exhibits good aggregating properties, and an anion contained in the amphoteric polymer. By increasing the ratio, aggregation and dehydration are possible even at a pH of about 4 or less. In addition, such a polymer flocculant may be added to the same position as the organic bacteriostatic agent, or may be added to a separate flocculation reaction tank.
【００１９】〔４〕スラリー系、およびケーキ系の臭気
防止に使用される亜硝酸塩の種類には特に制限がなく、
例えばアルカリ金属塩、アルカリ土類類金属塩等を使用
することができる。この亜硝酸塩は、好ましくは脱臭対
象箇所又はその直前の位置に添加され、図示例では、重
力濃縮槽、濃縮初沈汚泥貯槽、汚泥混合貯留槽等が
好適である。[4] There are no particular restrictions on the type of nitrite used to prevent the odor of slurry and cake.
For example, alkali metal salts, alkaline earth metal salts and the like can be used. This nitrite is preferably added to the deodorization target location or a location immediately before it. In the illustrated example, a gravity concentration tank, a concentrated concentrated sludge storage tank, a sludge mixed storage tank, and the like are suitable.
【００２０】〔５〕ｐＨ低下剤として使用する第二鉄塩
の種類についても特に制限がなく、通常塩化第二鉄、硫
酸第二鉄、ポリ硫酸第二鉄を使用できるが、腐食性の低
い硫酸塩を使用することが好ましい。[5] There is no particular limitation on the type of ferric salt used as a pH-lowering agent. Normally, ferric chloride, ferric sulfate, and ferric polysulfate can be used. It is preferred to use sulfates.
【００２１】〔６〕ｐＨ低下剤として使用する有機系二
塩基酸は粉末、水溶液の何れの添加形態でも良いが、脱
水ケーキ或いは凝集・ろ過物に添加する場合は粉末とす
る。また、特に脱水ケーキに酸が移行し易い溶解度の小
さいフマル酸、アジピン酸が好ましい。[6] The organic dibasic acid used as a pH-lowering agent may be in the form of any of a powder and an aqueous solution. In addition, fumaric acid and adipic acid, which have low solubility and easily transfer an acid to the dehydrated cake, are particularly preferable.
【００２２】〔７〕亜硝酸塩と組み合わしてなる有機系
静菌剤は、ケーキ固形分に効率良く移行し、ろ液側への
流出を最小にすることがケーキ系の臭気抑制時間延長に
は極めて重要である。そこでこのケーキ系静菌剤は脱水
工程の直前に添加すること、およびジンクピリチオン、
ソルビン酸、安息香酸、デヒドロ酢酸等の有機系静菌剤
はアルカリ塩等の溶液ではなく、不溶性金属塩のスラリ
ー、粉末形態、粉末スラリーで添加することが効率的で
ある。この有機系静菌剤は、前述のように添加場所に限
定はないが、図示例では汚泥供給タンクから脱水機
に添加すれば良く、常温で１５分以内に脱水されるよう
に添加することが好ましい。[7] The organic bacteriostatic agent combined with nitrite efficiently transfers to the cake solids, and minimizing the outflow to the filtrate side is necessary for extending the odor control time of the cake system. Very important. Therefore, this cake bacteriostatic agent should be added immediately before the dehydration step, and zinc pyrithione,
Organic bacteriostatic agents such as sorbic acid, benzoic acid, and dehydroacetic acid are efficiently added in the form of a slurry, powder form, or powder slurry of an insoluble metal salt, not a solution of an alkali salt or the like. The location of the organic bacteriostatic agent is not limited as described above, but in the illustrated example, the organic bacteriostatic agent may be added from the sludge supply tank to the dehydrator, and may be added so as to be dehydrated within 15 minutes at room temperature. preferable.
【００２３】[0023]
【実施例】以下に、実施例を挙げて本発明を詳しく説明
するが、本発明はこれらの実施例に何等限定されるもの
ではない。EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.
【００２４】１．試験方法 （１）汚泥 汚泥はＡ下水処理場の初沈重力濃縮汚泥と余剰延伸濃縮
汚泥を別個に採取し、この全固形物濃度（ＴＳ）を測定
後、それぞれの濃度を厚木市市水で２．５０％に調整し
た後、初沈汚泥６０％、余剰汚泥４０％に混合し、供試
試料とした。このような処理を行う理由は、臭気の発生
や、臭気処理剤の効果が各汚泥の混合比率や濃度によっ
て大きく異なるため、試験日時が異なる試験結果を直接
比較できるよう汚泥条件をできるだけ同一化するためで
ある。1. Test method (1) Sludge Sludge was collected separately from the initial sedimentation gravity concentrated sludge and the excess stretched concentrated sludge at the A sewage treatment plant, and after measuring the total solids concentration (TS), each concentration was measured using Atsugi City Water. After adjusting to 2.50%, the mixture was mixed with 60% of initial settled sludge and 40% of surplus sludge to obtain a test sample. The reason for performing such treatment is that the generation of odor and the effect of the odor treatment agent vary greatly depending on the mixing ratio and concentration of each sludge, so that the sludge conditions are made as identical as possible so that test results with different test dates and times can be directly compared. That's why.
【００２５】（２）スラリー系臭気防止試験 ２．５％調整汚泥１０００ｍｌを１Ｌビーカーに採り、
ｐＨ低下剤を添加混合後、直ちに所定量の亜硝酸ナトリ
ウムを添加混合した。試料は２５℃の恒温室に保管し、
１〜２４時間の硫化水素（Ｈ2Ｓ）、メチルメルカプタ
ン（ＭＭ）の濃度推移を測定した。硫化水素、メチルメ
ルカプタンの濃度は、汚泥５０ｍｌを空隙容積（汚泥５
０ｍｌを除く）６００ｃｃの容器に採り、１分間激しく
振盪して悪臭ガス成分を揮散させた後、ガステック社製
検知管にて測定した。この測定値（ｐｐｍ）から次式に
したがって、汚泥中に含まれる硫化水素およびメチルメ
ルカプタンの濃度を計算した。Ｈ2Ｓ汚泥中濃度(mg/l)
＝測定ガス濃度(ppm)×1.16(*1)×0.01832(*2)＝Ａ(pp
m)ＭＭ汚泥中濃度(mg/l)＝測定ガス濃度(ppm)×1.82(*
3)×0.023(*4)＝Ｂ(ppm) ＊１）無処理汚泥で悪臭ガス測定後、空気を置換して再
度振盪、ガス測定を硫化水素の測定数値が０ｐｐｍにな
るまで繰り返し行う。その全測定値合算値を１回目測定
値で割った商が１．１６である。この係数により１回目
の測定値から、気液平衡等で揮散しなかった硫化水素分
を含めたトータルを推算する。 ＊２）硫化水素１ミリモル（３４ｍｇ）が２２．４Ｌ中
に存在すると１０００ｐｐｍになるため、汚泥中の硫化
水素濃度（Ａ-2 mg/l）は次式となる。 Ａ-2＝34/22400×600×Ａ/1000×1000/50＝0.0182(mg/
l) ＊３）前記＊１）と同様の操作でメチルメルカプタンの
１回目測定値から全メチルメルカプタンを推算する係数
を求めて、係数１．８２を得た。 ＊４）メチルメルカプタン１ミリモルは４８ｍｇである
ため、前記＊２）と同様に、汚泥中のメチルメルカプタ
ン濃度（Ｂ-2 mg/l）は次式となる。 Ｂ-2＝48/22400×600×Ｂ/1000×1000/50＝0.0230(mg/
l) また、臭気物質測定とともに汚泥中の亜硝酸塩残留濃度
の測定を行った。(2) Slurry-based odor prevention test: 1,000 ml of 2.5% adjusted sludge was placed in a 1 L beaker,
Immediately after the addition and mixing of the pH lowering agent, a predetermined amount of sodium nitrite was added and mixed. Samples are stored in a 25 ° C constant temperature room,
Hydrogen sulfide from 1 to 24 hours (H 2 S), to determine the concentration transition of methyl mercaptan (MM). The concentration of hydrogen sulfide and methyl mercaptan was determined by setting 50 ml of sludge to void volume (sludge 5
(Excluding 0 ml) was taken in a 600 cc container, shaken vigorously for 1 minute to volatilize odorous gas components, and then measured with a gas tube detector tube. From the measured values (ppm), the concentrations of hydrogen sulfide and methyl mercaptan contained in the sludge were calculated according to the following equation. H 2 S sludge concentration (mg / l)
= Measurement gas concentration (ppm) x 1.16 (* 1) x 0.01832 (* 2) = A (pp
m) MM sludge concentration (mg / l) = measured gas concentration (ppm) x 1.82 (*
3) × 0.023 (* 4) = B (ppm) * 1) After measuring odorous gas with untreated sludge, replace air and shake again, and repeat gas measurement until the measured value of hydrogen sulfide becomes 0 ppm. The quotient obtained by dividing the sum of all the measured values by the first measured value is 1.16. From this coefficient, the total including the hydrogen sulfide not volatilized due to gas-liquid equilibrium or the like is estimated from the first measurement value. * 2) If 1 mmol (34 mg) of hydrogen sulfide is present in 22.4 L, the concentration will be 1000 ppm. Therefore, the concentration of hydrogen sulfide (A-2 mg / l) in sludge is as follows. A-2 = 34/22 400 × 600 × A / 1000 × 1000/50 = 0.0182 (mg /
l) * 3) A coefficient for estimating the total methyl mercaptan from the first measurement value of methyl mercaptan was obtained by the same operation as in * 1) to obtain a coefficient of 1.82. * 4) Since 1 mmol of methyl mercaptan is 48 mg, the concentration of methyl mercaptan in sludge (B-2 mg / l) is expressed by the following equation, as in the above * 2). B-2 = 48/22 400 × 600 × B / 1000 × 1000/50 = 0.0230 (mg /
l) In addition to measurement of odorous substances, residual nitrite concentration in sludge was measured.
【００２６】（３）ケーキ系臭気防止試験 ２．５％調整汚泥２００ｍｌを３００ｍｌビーカーに採
取し、ｐＨ低下処理と亜硝酸塩添加を行った後、１時間
室温で保管する。その後、有機系静菌剤を添加し、直ち
に高分子凝集剤で凝集、重力ろ過を行い、ベルトプレス
脱水を想定した圧搾試験装置で重力ろ過物の全量を、
０．０５ＭＰａの圧力で１２０秒間、圧搾脱水を行い、
脱水ケーキを得る。脱水ケーキ全量を、開封したテトラ
パックに入れ、開封口をヒートシールする。ケーキ量１
ｇに対して、空気２５ｃｃをシリンジで注入し（ケーキ
は約２０ｇ、空気は５００ｃｃになる）、これを３０℃
の恒温室に保管し、２４時間ごとに硫化水素、メチルメ
ルカプタンの測定を行った。(3) Cake-based odor prevention test 200 ml of 2.5% adjusted sludge is collected in a 300 ml beaker, subjected to pH lowering treatment and nitrite addition, and stored for 1 hour at room temperature. Thereafter, an organic bacteriostatic agent was added, and immediately agglomerated with a polymer coagulant, gravity filtration was performed, and the entire amount of the gravity filtered material was crushed by a compression test apparatus assuming belt press dehydration,
Press dewatering for 120 seconds at a pressure of 0.05 MPa,
Get a dehydrated cake. The whole amount of the dehydrated cake is placed in the opened tetra pack, and the opening is heat-sealed. Cake quantity 1
Inject 25 cc of air into the syringe (about 20 g for cake and 500 cc for air) with respect to g.
And measured for hydrogen sulfide and methyl mercaptan every 24 hours.
【００２７】実施例１；ｐＨ低下によるスラリー系の臭
気防止持続時間の測定試験 前記試験方法（２）に沿ってスラリー系における臭気物
質（硫化水素およびメチルメルカプタン）の濃度の測
定、並びに亜硝酸塩残留濃度の測定を行った。硫化水素
（Ｈ2Ｓ）濃度の測定結果を表１に、メチルメルカプタ
ン（ＭＭ）濃度の測定結果を表２、また亜硝酸塩残留濃
度の測定結果を表３に示した。尚、以下の条件の比較例
も同様に試験し、その測定結果を併記した。 比較例１−０：ブランク 比較例１−１：ｐＨ低下処理無しで静菌剤（亜硝酸塩）
適用 比較例１−２：ｐＨ５．５以上の低下処理して静菌剤
（亜硝酸塩）適用 比較例１−３：ｐＨ低下処理して亜硝酸塩以外の臭気処
理剤（亜塩素酸塩）適用 比較例１−４：ｐＨ低下処理無しで亜硝酸塩以外の臭気
処理剤（過酸化水素）適用 比較例１−５：ｐＨ低下処理して亜硝酸塩以外の臭気処
理剤（過酸化水素）適用Example 1 Measurement Test of Odor Prevention Duration of Slurry System Due to pH Drop Measurement of the concentration of odorous substances (hydrogen sulfide and methyl mercaptan) in the slurry system and residual nitrite according to the above-mentioned test method (2). The concentration was measured. Table 1 shows the measurement results of the hydrogen sulfide (H 2 S) concentration, Table 2 shows the measurement results of the methyl mercaptan (MM) concentration, and Table 3 shows the measurement results of the residual nitrite concentration. In addition, the comparative example of the following conditions was also tested similarly, and the measurement result was also described. Comparative Example 1-0: Blank Comparative Example 1-1: Bacteriostatic agent (nitrite) without pH lowering treatment
Application Comparative Example 1-2: Applying a bacteriostatic agent (nitrite) by lowering the pH to 5.5 or more Comparative Example 1-3: Applying an odor treating agent (chlorite) other than nitrite by applying a lowering pH Example 1-4: Odor treatment agent other than nitrite (hydrogen peroxide) applied without pH lowering treatment Comparative Example 1-5: Odor treatment agent other than nitrite (hydrogen peroxide) applied with pH lowering treatment
【００２８】[0028]
【表１】 [Table 1]
【表２】 [Table 2]
【表３】 [Table 3]
【００２９】表１〜３より明らかなように、ｐＨ低下剤
の種類にかかわらずｐＨ５．５以下に調整するとともに
静菌剤である亜硝酸塩を用いることにより、スラリー系
における硫化水素やメチルメルカプタンの濃度を１〜２
４時間もの長時間に亘って低く抑えることが確認され
た。As is clear from Tables 1 to 3, the pH is adjusted to 5.5 or less regardless of the type of the pH reducing agent, and the use of nitrite, which is a bacteriostatic agent, makes it possible to use hydrogen sulfide and methyl mercaptan in the slurry system. Concentration 1-2
It was confirmed that it was kept low for as long as 4 hours.
【００３０】実施例２；ｐＨ低下時の各種高分子凝集剤
による脱水試験 分子内に架橋構造が導入されたカチオン系高分子凝集剤
（架橋カチオンと略記する）および分子内にカチオン基
およびアニオン基が導入された両性高分子凝集剤（両性
と略記する）を用いた場合の通常のカチオン系高分子凝
集剤（通常カチオンと略記する）との凝集、脱水性を評
価するため、フロック径、ろ液量、ろ過速度を測定し
た。測定結果を表４に示した。尚、以下の条件の比較例
も同様に試験し、その結果を併記した。 比較例２−０：ブランク 比較例２−１：強酸（硫酸）にてｐＨ低下処理して通常
高分子凝集剤適用 比較例２−２：ポリ硫酸鉄にてｐＨ低下処理して通常高
分子凝集剤適用 比較例２−３：フマル酸にてｐＨ低下処理して通常高分
子凝集剤適用Example 2: Dehydration test with various polymer flocculants when the pH is lowered Cationic polymer flocculant having a cross-linked structure introduced in the molecule (abbreviated as cross-linked cation) and cationic and anionic groups in the molecule In order to evaluate the agglomeration and dehydration properties of a general cationic polymer flocculant (usually abbreviated as cation) when using an amphoteric polymer flocculant (abbreviated as amphoteric) into which is introduced, a floc diameter, a filter The liquid volume and the filtration rate were measured. Table 4 shows the measurement results. In addition, the comparative example under the following conditions was similarly tested, and the result was also described. Comparative Example 2-0: blank Comparative Example 2-1: pH-lowering treatment with strong acid (sulfuric acid) and application of normal polymer flocculant Comparative Example 2-2: pH-lowering treatment with iron polysulfate and normal polymer aggregation Comparative Example 2-3: Applying a normal polymer flocculant by performing pH reduction treatment with fumaric acid
【００３１】[0031]
【表４】 [Table 4]
【００３２】表４より明らかなように、ｐＨ低下させた
条件では通常の高分子凝集剤ではフロック径も小さく、
ろ過速度も遅く、汚泥を機械脱水可能なレベルまで凝集
させることができなかった。しかし、このｐＨ低下させ
た条件でも、特定の高分子凝集剤（架橋カチオンや両
性）を用いることにより、従来と同様の凝集、脱水性が
得られることが確認された。As is evident from Table 4, under the condition where the pH was lowered, the floc diameter was small with the ordinary polymer flocculant.
The filtration rate was also slow, and the sludge could not be flocculated to a level that allowed mechanical dewatering. However, it was confirmed that the same coagulation and dehydration properties as before can be obtained by using a specific polymer coagulant (cross-linking cation or amphoteric) even under the condition where the pH is lowered.
【００３３】実施例３；ｐＨ低下によるケーキ系の臭気
防止持続時間の測定試験 前記試験方法（３）に沿ってケーキ系における臭気物質
（硫化水素およびメチルメルカプタン）の濃度の測定を
行った。硫化水素（Ｈ2Ｓ）濃度の測定結果を表５に、
メチルメルカプタン（ＭＭ）濃度の測定結果を表６に示
した。尚、以下の条件の比較例も同様に試験し、その測
定結果を併記した。 比較例３−０：ブランク 比較例３−１：ｐＨ低下処理無しで亜硝酸塩のみ適用 比較例３−２：ｐＨ低下処理無しで亜硝酸塩と有機系静
菌剤（ZPt）とを適用 比較例３−３：ｐＨ低下処理して有機系静菌剤（ZPt）
のみ適用 比較例３−４：ｐＨ低下処理無しで亜硝酸塩と有機系静
菌剤（ソルビン酸）とを適用 比較例３−５：ｐＨ低下処理して有機系静菌剤（ソルビ
ン酸）のみ適用 比較例３−６：ｐＨ低下処理無しで亜硝酸塩と有機系静
菌剤（安息香酸）とを適用 尚、ZPtはジンクピリチオンの略記である。Example 3 Measurement Test of Odor Prevention Duration of Cake System Due to Decrease in pH The concentration of odorous substances (hydrogen sulfide and methyl mercaptan) in the cake system was measured according to the test method (3). Table 5 shows the measurement results of the concentration of hydrogen sulfide (H 2 S).
Table 6 shows the measurement results of the methyl mercaptan (MM) concentration. In addition, the comparative example of the following conditions was also tested similarly, and the measurement result was also described. Comparative Example 3-0: Blank Comparative Example 3-1: Nitrite Only Applied Without pH Lowering Treatment Comparative Example 3-2: Nitrite and Organic Bacteriostatic Agent (ZPt) Applied Without pH Lowering Treatment Comparative Example 3 -3: pH lowering treatment and organic bacteriostatic agent (ZPt)
Comparative example 3-4: Nitrite and organic bacteriostatic agent (sorbic acid) are applied without pH lowering treatment Comparative example 3-5: pH lowering treatment and only organic bacteriostatic agent (sorbic acid) applied Comparative Example 3-6: Application of nitrite and an organic bacteriostatic agent (benzoic acid) without pH lowering treatment ZPt is an abbreviation for zinc pyrithione.
【００３４】[0034]
【表５】 [Table 5]
【表６】 [Table 6]
【００３５】表５，６より明らかなように、ｐＨ低下剤
の種類にかかわらずｐＨ５．５以下に調整するとともに
亜硝酸塩と有機系静菌剤を組み合わせて用いることによ
り、ケーキ系における硫化水素やメチルメルカプタンの
濃度を１〜４日間もの長期間に亘って低く抑えることが
できることが確認された。As is clear from Tables 5 and 6, the pH is adjusted to 5.5 or less irrespective of the type of the pH-lowering agent, and by using a combination of nitrite and an organic bacteriostatic agent, hydrogen sulfide or the like in the cake system is reduced. It was confirmed that the concentration of methyl mercaptan could be kept low for as long as 1-4 days.
【００３６】実施例４；ｐＨ低下剤後添加によるケーキ
系の臭気防止持続時間の測定試験 凝集ろ過物へ、ｐＨ低下剤を後添加（追加）した場合の
ケーキ系における臭気物質（硫化水素およびメチルメル
カプタン）の濃度の測定を前記実施例３よりもさらに長
い時間で行った。硫化水素（Ｈ2Ｓ）濃度の測定結果を
表７に、メチルメルカプタン（ＭＭ）濃度の測定結果を
表８に示した。尚、以下の条件の比較例も同様に試験
し、その測定結果を併記した。 比較例４−０：ブランク 比較例４−１：先添加および後添加ｐＨ低下剤無し以外
は同様Example 4 Measurement Test of Odor Prevention Duration of Cake System by Post-Addition of pH-Lowering Agent Odorants (hydrogen sulfide and methyl) in the cake system when a pH-lowering agent was post-added (added) to the aggregated filtrate (Mercaptan) was measured for a longer time than in Example 3. Table 7 shows the measurement results of the hydrogen sulfide (H 2 S) concentration, and Table 8 shows the measurement results of the methyl mercaptan (MM) concentration. In addition, the comparative example of the following conditions was also tested similarly, and the measurement result was also described. Comparative Example 4-0: Blank Comparative Example 4-1: Same as above except that no pre-addition and post-addition pH lowering agent was used
【００３７】[0037]
【表７】 [Table 7]
【表８】 [Table 8]
【００３８】表７，８より明らかなように、ｐＨ低下剤
を後添加しない場合（実施例４−１１〜１３）では５〜
６日程度で臭気発生が認められたが、ｐＨ低下剤をケー
キや重力ろ過物に後添加（追加）することにより、更な
る効果の持続延長が得られることが確認された。As is clear from Tables 7 and 8, when the pH-lowering agent was not added later (Examples 4-11 to 13), 5 to 5 was used.
Odor generation was observed in about 6 days, but it was confirmed that further extension of the effect could be obtained by post-adding (adding) the pH-lowering agent to the cake or gravity filtrate.
【００３９】[0039]
【発明の効果】以上説明したように本発明の汚泥処理方
法は、汚泥ｐＨを低下させて３．５〜５．５に調整する
とともに、汚泥中に静菌剤を存在させることにより、硫
化水素やメチルメルカプタン等の臭気の発生を全プロセ
スに亘って効果的に防止することができる。さらに、こ
の条件でも他の処理、例えば汚泥の凝集、脱水処理に関
して何等支障なく実施することができる高分子凝集剤を
も提案するので、汚泥処理全体のシステムに何等支障を
生ずることがない。また、本発明は、スラリー系、ケー
キ系の何れかに限定されるものではなく、しかも特にケ
ーキ系の静菌剤として使用する薬剤は、人体、環境に対
して安全であって、特殊な設備等を増設する必要もない
ので実用的価値が高いものである。As described above, according to the sludge treatment method of the present invention, the pH of the sludge is adjusted to 3.5 to 5.5 by lowering the pH and the presence of a bacteriostatic agent in the sludge enables hydrogen sulfide to be produced. Odor such as methyl mercaptan and the like can be effectively prevented over the entire process. Further, even under these conditions, a polymer flocculant that can be carried out without any trouble in other treatments, for example, sludge flocculation and dehydration treatment, is proposed, so that there is no trouble in the whole sludge treatment system. Further, the present invention is not limited to any of the slurry system and the cake system, and in particular, the agent used as a cake system bacteriostatic agent is safe for the human body and the environment, and requires special equipment. It is of high practical value because there is no need to add additional components.
【図１】下水処理場の汚泥処理プロセスの例と臭気発生
箇所を示すフロー（流れ系統図）である。FIG. 1 is a flow (flow system diagram) showing an example of a sludge treatment process in a sewage treatment plant and an odor generation location.
Claims (8)
整するとともに、汚泥中に静菌剤を存在させることによ
り、汚泥からの臭気の発生を防止させることを特徴とす
る汚泥処理方法。1. A method for treating sludge, wherein the pH of sludge is lowered to 5.5 or less and a bacteriostatic agent is present in the sludge to prevent the generation of odor from the sludge. .
ことを特徴とする請求項１に記載の汚泥処理方法。2. The method for treating sludge according to claim 1, wherein the bacteriostatic agent is at least a nitrite ion.
硝酸イオンであることを特徴とする請求項１に記載の汚
泥処理方法。3. The method for treating sludge according to claim 1, wherein the bacteriostatic agent is at least an organic bacteriostatic agent and nitrite ions.
を所定ｐＨに低下させることを特徴とする請求項１〜３
の何れか一項に記載の汚泥処理方法。4. The sludge is reduced to a predetermined pH by at least an organic dibasic acid.
The sludge treatment method according to any one of the above.
ｐＨに低下させることを特徴とする請求項１〜３の何れ
か一項に記載の汚泥処理方法。5. The sludge treatment method according to claim 1, wherein the sludge is reduced to a predetermined pH with at least a ferric salt.
し、凝集処理後の汚泥のｐＨを５以下に調整することを
特徴とする請求項１〜５の何れか一項に記載の汚泥処理
方法。6. The sludge treatment method according to claim 1, wherein the sludge after the flocculation treatment is further adjusted by coagulation treatment with a polymer coagulant to 5 or less. .
カチオン系高分子凝集剤により汚泥脱水処理することを
特徴とする請求項１〜６の何れか一項に記載の汚泥処理
方法。7. The sludge treatment method according to claim 1, further comprising performing a sludge dehydration treatment with a cationic polymer flocculant having a crosslinked structure introduced in the molecule.
オン基が導入された両性高分子凝集剤により汚泥脱水処
理することを特徴とする請求項１〜６の何れか一項に記
載の汚泥処理方法。8. The sludge treatment method according to claim 1, further comprising performing a sludge dehydration treatment with an amphoteric polymer flocculant having a cation group and an anion group introduced into the molecule. .
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|---|---|---|---|
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|---|---|---|---|
| JP2000215640A JP3700550B2 (en) | 2000-07-17 | 2000-07-17 | Sludge treatment method |
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| FR2849020A1 (en) * | 2002-12-23 | 2004-06-25 | Otv Sa | Treatment procedure for fermentable sludge or effluent consists of reducing pH level, adding nitrite salt, agitating, filtering and neutralizing |
| JP2004230292A (en) * | 2003-01-30 | 2004-08-19 | Ebara Corp | Method and device for preventing generation of odor |
| JP2005000764A (en) * | 2003-06-10 | 2005-01-06 | Ebara Engineering Service Co Ltd | Sludge slurry dehydration method and equipment |
| JP2010227937A (en) * | 2010-06-15 | 2010-10-14 | Kurita Water Ind Ltd | Odor prevention method |
| JP2012157862A (en) * | 2012-04-04 | 2012-08-23 | Swing Corp | Method for preventing odor generation of dehydrated cake |
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| WO2004058651A3 (en) * | 2002-12-23 | 2004-08-19 | Otv Sa | Fermentable effluent- and/or sludge-purification method and installation for implementing one such method |
| FR2849020A1 (en) * | 2002-12-23 | 2004-06-25 | Otv Sa | Treatment procedure for fermentable sludge or effluent consists of reducing pH level, adding nitrite salt, agitating, filtering and neutralizing |
| JP2004230292A (en) * | 2003-01-30 | 2004-08-19 | Ebara Corp | Method and device for preventing generation of odor |
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