【発明の詳細な説明】
【０００１】
【発明の属する技術分野】本発明は、下水等の固液分離
設備として適用する濃縮凝集装置に関するものである。
【０００２】
【従来の技術】一般に水処理分野の汚泥濃縮は、下水等
の固液分離濃縮技術として広く使用されており、その濃
縮方法としては重力濃縮や機械濃縮（遠心、浮上等）が
あり、いずれの場合も濃縮性能は、濃縮液濃度が高く、
分離液が清澄であるなど、その主な目的は、後段汚泥処
理の効率化と水処理への返流水負荷の低減にある。しか
るに近年は、生活環境の変化や分流式下水道の普及に伴
い汚泥濃縮性が悪化しているため、その汚泥濃縮方法と
して機械濃縮機を採用するケースが増加している。
【０００３】
【発明が解決しようとする課題】従来の汚泥濃縮方法に
おいて、重力濃縮の場合、消費動力は小さいが、その反
面、濃縮槽の汚泥滞留時間が１０時間程度と長く且つ広
い敷地を必要とし、濃縮液および分離液濃度は原汚泥の
性状に大きく依存する。ここでの、一般的に濃縮槽への
投入汚泥濃度は、０．５〜１％程度であり、濃縮液の濃
度は２〜３％程度、分離液濃度は１０００〜５０００ｍ
ｇ／Ｌ程度（ＳＳ回収率６０〜７０％程度）となる。こ
のように、重力濃縮槽ではランニングコストは小さいが
濃縮性能の悪化時に、高濃度の分離液が水処理系統へ返
流水として戻り、水処理の負荷に大きな影響を及ぼすと
いう課題があった。一方、機械濃縮の場合、一般的に濃
縮液の濃度は４％以上、ＳＳ回収率は９０％以上となる
が、その反面、設備費および消費動力が大きくなるとい
う課題があった。このように従来の重力濃縮および機械
濃縮ではそれぞれ一長一短があることから、低コストで
濃縮性能が向上する濃縮装置の開発が望まれている。
【０００４】本発明は上記のような事情に鑑みてなされ
たもので、濃縮分離液の清澄度が高く、水処理系統への
返流水負荷を大幅削減可能で、且つランニングコストの
低減を図ることができる濃縮凝集装置を提供することを
目的とする。
【０００５】
【課題を解決するための手段】本発明に係る濃縮凝集装
置は、流入水を導入する流入槽と、この流入槽からの流
出水を濃縮する濃縮槽と、この濃縮槽から濃縮分離液を
導入する凝集分離槽と、この凝集分離槽から前記流入槽
に汚泥を返送する汚泥返送管とを備えたものである。
【０００６】
【発明の実施の形態】以下、この発明の実施の一形態を
説明する。
実施の形態１．図１はこの発明の実施の形態１による濃
縮凝集装置を示すフロー図である。図において、１は原
水導入管、２はその原水導入管１から流入水を導入する
流入槽、３は流入槽２からの流出水を導入しその流出水
に含まれた懸濁物質（汚泥）などを濃縮する濃縮槽であ
り、この濃縮槽３としては一般的な重力濃縮装置が適用
される。４は前記濃縮槽３から濃縮分離液を導入して固
液分離する凝集分離槽、５はその凝集分離槽４内に添加
物を供給する添加物供給手段であり、添加物供給手段と
しては、定量フィダー供給やスラリー供給あるいはドラ
イ供給が挙げられるが、凝集分離槽４内に添加物を速や
かに供給できるものであれば、如何なるものでもよい。
その添加物としては、砂または砂に近似する比重２〜８
の範囲である有機系や無機系の物質、またはそれらの混
合物、例えば微粒砂や酸化ジルコニウムやガーネットな
どが挙げられる。６は前記凝集分離槽４に無機凝集剤お
よび高分子凝集剤を併用するか、各々単独で供給する薬
品供給手段、７は前記凝集分離槽４から凝集汚泥を前段
の流入槽２内に返送する汚泥返送管、８は凝集分離槽４
の分離液を系外に排出する処理水排出管である。汚泥返
送には、砂が含まれることもあるので、耐摩耗性がある
サンドポンプや、耐摩耗性水中ポンプなどが好ましい。
凝集分離に微粒砂を用いた場合は、サイクロンなどで砂
分を分離した汚泥を返送する。なお、汚泥返送管７は返
送路など汚泥を流入槽２に戻すことができればよい。な
お耐摩耗性であればなおよい。また、流入槽２に代わり
にパイプで導入したり、スタティックミキサー、ライン
ミキサーを使用したり、濃縮槽３に付帯するように設け
られた槽でもよい。さらには、濃縮槽３の流入口付近に
返送汚泥を返送しても代用できる。
【０００７】次に動作について説明する。原水導入管１
から流入槽２に流入した流入水は、後段の凝集分離槽４
から前記流入槽２に返送された凝集汚泥と混合され、そ
の流出水が濃縮槽３に移流し、この濃縮槽３では、流入
槽２からの流出水中の凝集汚泥や流入水中の固形分等が
重力濃縮されて分離される。ここで、濃縮槽３に移流し
た流入槽２からの流出水中には凝集分離槽４から返送さ
れた凝集汚泥に含まれる沈降促進材となる凝集剤や砂等
の不溶性物質が含まれていることにより、前記濃縮槽３
では汚泥の重力濃縮が促進される。これにより、濃縮汚
泥のＴＳ濃度と濃縮分離液の清澄度などが改善される。
【０００８】次いで、凝集分離槽４内には、添加物供給
手段５から砂等の不溶性物質である添加物が供給される
と共に、薬品供給手段６から凝集剤が供給されること
で、凝集分離槽４内に移流した濃縮分離液に含まれる汚
泥が凝集沈殿され、その凝集汚泥は汚泥返送管７を介し
て前段の流入槽２に返送される一方、分離液は処理水排
出管８から系外に排出される。
【０００９】以上説明した一連のプロセスにより、濃縮
液濃度は通常の重力濃縮の場合と比較して１０〜２０％
増加し、重力濃縮と凝集分離とによる総合的なＳＳ除去
率は９５％以上となり、ＳＳに含まれるリンが除去され
るだけでなく、濃縮分離液の清澄度が向上する。このた
め、水処理系への返流水負荷が大幅削減される。
【００１０】実施例１．上記実施の形態１による構成と
した本発明の濃縮凝集装置と、重力沈降を行う濃縮槽に
直接凝集剤を添加した従来（薬注重力濃縮）の場合とを
下水で実施して比較した結果を表１に示す。
【００１１】
【表１】
【００１２】なお、実施条件として、本発明の凝集分離
槽４に添加する添加物としては微粒砂を用いた。また、
原液汚泥ＳＳ５，０００ｍｇ／Ｌ、Ｔ−Ｐ８０ｍｇ／
Ｌ、処理量３，８００ｍ３／日とした。さらに、本発明
の凝集分離槽４における砂濃度は６，０００ｍｇ／Ｌ、
従来例の重力濃縮槽単独の濃縮液ＴＳ濃度は１．７％程
度である。なお、ＳＳは浮遊物質（懸濁物質）を、Ｔ−
Ｐは全リンを、ＴＳは蒸発残留物（全固形物量）を示
す。
【００１３】本発明による濃縮凝集装置での処理では、
前段の重力濃縮槽３での濃縮液ＴＳ濃度が２％、後段の
凝集分離槽４での凝集分離処理水のＳＳ濃度が４０ｍｇ
／Ｌとなり、総合的なＳＳ除去率は９９％以上となっ
た。また、Ｔ−Ｐの除去率もＳＳ除去率と同様に９９％
以上となって頗る良好であった。なお、この時の薬品使
用量は無機凝集剤２９０Ｌ／日で、これは全固形物量に
対して８％になるように高分子凝集剤２．９ｍ３／日
で、これは全固形物量に対して０．１３％になるように
した。これに対し、単独の重力濃縮槽に凝集剤を直接添
加した従来のプロセスでは、本発明と同じ薬品使用量
（無機凝集剤２９０Ｌ／日，高分子凝集剤２．９ｍ３／
日）で濃縮液ＴＳ濃度は２．１％、ＳＳ除去率は７６％
であり、更に薬品使用量を増加させたところ、濃縮液Ｔ
Ｓ濃度は２．８％、ＳＳ除去率は９９％となった。
【００１４】ここで、従来の重力濃縮槽において、上述
のように薬品使用量を増加させることにより、本発明の
場合とほぼ同様のＳＳ除去率を得ることができるが、こ
の場合、表１の薬品コストの欄で明らかな通り、１９，
７００円／日から５３，９２０円／日へ２倍以上のコス
ト高となる。これに対する本発明では、容積２，０００
ｍ３の濃縮槽３に対して後段の凝集分離槽４は容積１０
ｍ３と非常に小型であることから、少ない薬品コストで
非常高いＳＳ除去率およびＴ−Ｐ除去率が得られた。こ
の事由は、濃縮槽３から凝集分離槽４に移流させた濃縮
分離液のみに薬品添加を行うことで効率化を図ったこと
と、凝集分離槽４での添加物使用による凝集沈殿の高速
化を図ったことにある。本発明の実施例では、添加物を
使用して凝集分離槽を小型にしたが、凝集分離槽を１０
倍の容積にすれば同等の薬品コストで、同等の水質が得
られる。したがって、本発明の濃縮凝集装置によれば、
低コストで濃縮分離液の清澄化が可能となり、水処理系
への返流水負荷を大幅に削減可能となる。
【００１５】なお、上記実施の形態１において、濃縮槽
３は重力濃縮に限らず他の遠心濃縮や加圧浮上濃縮であ
っても良く、また、対象廃水は、屎尿や産業廃水など濃
縮を必要とするものであれば、処理対象の被処理液（流
入水）となるものである。
【００１６】
【発明の効果】以上のように本発明によれば、設備費や
消費動力が大きな濃縮機械を必要とせず、近年の生活環
境の変化や分流式下水道の普及に伴う汚泥濃縮性能の悪
化傾向にあっても、消費動力が小さく低コストで濃縮性
能を向上させることができるという効果がある。即ち、
凝集分離槽での凝集汚泥を前段の流入槽に返送して流入
水（被処理液）と混合させることにより、次段濃縮槽で
の濃縮性能が向上し、その濃縮槽から後段の凝集分離槽
に移流した濃縮分離液のみに添加物を添加することによ
り、凝集分離槽での凝集分離処理を非常に短時間（５分
程度）に効率よく行うことができ、このような濃縮槽と
凝集分離槽とによる総合的なＳＳ除去率は、上記実験例
で明らかな通り９５％以上となって、濃縮分離液の清澄
度が非常に高くなるという効果がある。また、薬品使用
量について、従来の重力濃縮槽に直接凝集剤を添加した
場合に比べ、同じＳＳ除去率を得るのに本発明では５０
％以上少なくて済むので、薬品コストを低減できるとい
う効果がある。あるいは、凝集分離槽に添加物を使用し
ないで、凝集分離槽の容積を１０倍とすれば、同様の薬
品量で、同様の水質が得られるという効果がある。さら
に、本発明では、濃縮槽から凝集分離槽に移流させた濃
縮分離液のみに薬品添加を行うので、濃縮槽後段の凝集
分離槽は前段の濃縮槽に比べて容積が非常に小さなもの
でよく、その小容積の凝集分離槽によれば非常に高いＳ
Ｓ除去率を得ることができ、また、小容積の凝集分離槽
に対する薬品添加量は、上述のように従来の重力濃縮槽
に直接凝集剤を添加した場合に比べ、同じＳＳ除去率を
得るのに５０％以上少なくて済むので、薬品コストを低
減できるという効果がある。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a condensing and aggregating apparatus applied as a solid-liquid separation equipment for sewage or the like. 2. Description of the Related Art In general, sludge concentration in the field of water treatment is widely used as a solid-liquid separation and concentration technique for sewage and the like, and its concentration methods include gravity concentration and mechanical concentration (centrifugation, flotation, etc.). , In any case, the concentration performance is high,
The main purpose, such as the clarity of the separated liquid, is to improve the efficiency of the second-stage sludge treatment and to reduce the load on the water returned to the water treatment. However, in recent years, sludge concentrating properties have been degraded due to changes in living environment and the spread of sewerage sewerage systems. Therefore, cases in which a mechanical concentrator is used as a sludge concentrating method are increasing. [0003] In the conventional sludge concentration method, in the case of gravity concentration, the power consumption is small, but on the other hand, the sludge residence time of the concentration tank is as long as about 10 hours and a large site is required. The concentration of the concentrated liquid and the separated liquid greatly depends on the properties of the raw sludge. Here, generally, the concentration of sludge put into the concentration tank is about 0.5 to 1%, the concentration of the concentrated liquid is about 2 to 3%, and the concentration of the separated liquid is 1000 to 5000 m.
g / L (SS recovery rate of about 60 to 70%). As described above, in the gravity concentration tank, the running cost is small, but when the concentration performance is deteriorated, a high-concentration separated solution returns as return water to the water treatment system, and thus has a problem that the load of the water treatment is greatly affected. On the other hand, in the case of mechanical concentration, the concentration of the concentrate is generally 4% or more and the SS recovery rate is 90% or more, but on the other hand, there is a problem that equipment costs and power consumption increase. As described above, the conventional gravity concentration and the mechanical concentration each have advantages and disadvantages. Therefore, it is desired to develop a concentration device that improves the concentration performance at low cost. SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has an object to improve the clarity of a concentrated separation liquid, greatly reduce the load of returning water to a water treatment system, and reduce running costs. It is an object of the present invention to provide a concentrating and aggregating apparatus capable of performing the following. [0005] A concentrating and coagulating apparatus according to the present invention comprises an inflow tank for introducing inflow water, a concentration tank for concentrating effluent from the inflow tank, and a concentration and separation from the concentration tank. It has a coagulation / separation tank for introducing a liquid, and a sludge return pipe for returning sludge from the coagulation / separation tank to the inflow tank. An embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a flow chart showing a concentration and aggregation device according to Embodiment 1 of the present invention. In the figure, 1 is a raw water introduction pipe, 2 is an inflow tank for introducing inflow water from the raw water introduction pipe 1, 3 is an outflow water from the inflow tank 2, and 3 is a suspended substance (sludge) contained in the outflow water. This is a concentration tank for concentrating water and the like, and a general gravity concentrator is applied as the concentration tank 3. Reference numeral 4 denotes an aggregating / separating tank for introducing a concentrated / separated liquid from the concentrating tank 3 to perform solid-liquid separation, and 5 denotes an additive supplying means for supplying an additive into the aggregating / separating tank 4. A fixed-quantity feeder supply, a slurry supply, or a dry supply may be mentioned, but any material may be used as long as the additive can be quickly supplied into the flocculation / separation tank 4.
As the additive, sand or specific gravity 2 to 8 similar to sand is used.
And organic or inorganic substances, or mixtures thereof, such as fine sand, zirconium oxide and garnet. 6 is a chemical supply means for supplying an inorganic flocculant and a polymer flocculant to the flocculation / separation tank 4 together or supplying each alone, and 7 is for returning the flocculated sludge from the flocculation / separation tank 4 into the upstream inflow tank 2. Sludge return pipe, 8 is coagulation separation tank 4
This is a treated water discharge pipe for discharging the separated liquid from the system. Since sand may be contained in the sludge return, a sand pump having wear resistance, a wear-resistant submersible pump, or the like is preferable.
When fine-grained sand is used for coagulation and separation, the sludge from which sand has been separated by a cyclone is returned. The sludge return pipe 7 only needs to return sludge to the inflow tank 2 such as a return path. It is even better if the wear resistance is high. Further, instead of the inflow tank 2, a pipe may be introduced, a static mixer or a line mixer may be used, or a tank provided so as to accompany the concentration tank 3 may be used. Furthermore, returning sludge to the vicinity of the inlet of the concentration tank 3 can be used instead. Next, the operation will be described. Raw water introduction pipe 1
The influent flowing into the inflow tank 2 from the
Is mixed with the coagulated sludge returned to the inflow tank 2, and the effluent is transferred to the concentration tank 3. It is separated by gravity concentration. Here, the effluent from the inflow tank 2 transferred to the concentration tank 3 contains an insoluble substance such as a flocculant or sand serving as a sedimentation promoting material contained in the coagulated sludge returned from the coagulation separation tank 4. The concentration tank 3
Then, the gravity concentration of sludge is promoted. Thereby, the TS concentration of the concentrated sludge, the clarity of the concentrated separated liquid, and the like are improved. Next, an additive, which is an insoluble substance such as sand, is supplied from the additive supply means 5 into the coagulation / separation tank 4, and a coagulant is supplied from the chemical supply means 6. The sludge contained in the concentrated separated liquid transferred to the tank 4 is coagulated and settled, and the coagulated sludge is returned to the former inflow tank 2 through the sludge return pipe 7, while the separated liquid is discharged from the treated water discharge pipe 8 through the treated water discharge pipe 8. It is discharged outside. According to the series of processes described above, the concentration of the concentrated solution is 10 to 20% as compared with the case of ordinary gravity concentration.
As a result, the total SS removal rate by gravity concentration and coagulation separation becomes 95% or more, not only phosphorus contained in SS is removed, but also the clarity of the concentrated separation liquid is improved. For this reason, the return water load to the water treatment system is greatly reduced. Embodiment 1 FIG. The results obtained by comparing the concentration / aggregation apparatus of the present invention having the configuration according to the first embodiment with a conventional case (chemical injection gravity concentration) in which a coagulant is directly added to a concentration tank for gravity sedimentation by performing with sewage are shown below. It is shown in Table 1. [Table 1] As an operating condition, fine sand was used as an additive to be added to the coagulation / separation tank 4 of the present invention. Also,
Undiluted sludge SS 5,000mg / L, T-P80mg / L
L, and the treatment amount was 3,800 m 3 / day. Furthermore, the sand concentration in the coagulation separation tank 4 of the present invention is 6,000 mg / L,
The concentration of the concentrated solution TS in the conventional gravity concentration tank alone is about 1.7%. In addition, SS is the suspended substance (suspension substance), T-
P indicates total phosphorus, and TS indicates evaporation residue (total solid content). [0013] In the treatment in the concentrating and aggregating apparatus according to the present invention,
The concentration TS of the concentrated solution in the gravity concentration tank 3 in the first stage is 2%, and the SS concentration of the coagulation separation treatment water in the coagulation separation tank 4 in the subsequent stage is 40 mg.
/ L, and the overall SS removal rate was 99% or more. In addition, the removal rate of TP was 99% similarly to the removal rate of SS.
As mentioned above, it was very good. The amount of the chemical used at this time was 290 L / day of the inorganic flocculant, which was 2.9 m 3 / day of the polymer flocculant so as to be 8% based on the total solid content, which was based on the total solid content. To 0.13%. On the other hand, in the conventional process in which the coagulant is directly added to a single gravity concentrating tank, the same amount of chemicals as used in the present invention (290 L / day of inorganic coagulant, 2.9 m 3 of polymer coagulant / day)
Concentrate TS concentration is 2.1% and SS removal rate is 76%
When the amount of chemicals used was further increased, the concentrated solution T
The S concentration was 2.8%, and the SS removal rate was 99%. Here, in the conventional gravity concentration tank, by increasing the amount of chemicals as described above, it is possible to obtain an SS removal rate substantially similar to that of the present invention. As is evident in the column of chemical cost, 19,
The cost is more than double from 700 yen / day to 53,920 yen / day. In the present invention, the volume 2,000
flocculation separation tank 4 in the subsequent stage with respect to the concentration tank 3 m 3 is the volume 10
because it is very compact and m 3, very high SS removal rate and T-P removal rate less chemicals cost is obtained. The reason for this is that the chemicals are added only to the concentrated separation liquid transferred from the concentration tank 3 to the coagulation / separation tank 4 to increase the efficiency, and that the use of additives in the coagulation / separation tank 4 speeds up the coagulation and precipitation. It is to have planned. In the embodiment of the present invention, the coagulation / separation tank is reduced in size by using the additive.
If the volume is doubled, the same water quality can be obtained at the same chemical cost. Therefore, according to the concentration and aggregation device of the present invention,
It is possible to clarify the concentrated separated solution at low cost, and it is possible to greatly reduce the load of the return water to the water treatment system. In the first embodiment, the concentration tank 3 is not limited to gravity concentration but may be another centrifugal concentration or pressure flotation concentration. The target wastewater requires concentration such as human waste or industrial wastewater. Is the liquid to be treated (inflow water). As described above, according to the present invention, there is no need for a thickening machine which requires large equipment cost and power consumption, and the sludge thickening performance accompanying the recent changes in the living environment and the spread of the diverted sewer system is not required. Even if it is in a deteriorating tendency, there is an effect that the power consumption is small and the concentration performance can be improved at low cost. That is,
By returning the coagulated sludge in the coagulation separation tank to the inflow tank at the previous stage and mixing it with the inflow water (liquid to be treated), the enrichment performance in the next-stage concentration tank is improved, and the coagulation separation tank at the subsequent stage By adding an additive only to the concentrated separation liquid that has been transferred to the separation tank, the aggregation separation treatment in the aggregation separation tank can be efficiently performed in a very short time (about 5 minutes). The total SS removal rate by the tank is 95% or more as is clear in the above experimental example, and there is an effect that the clarity of the concentrated separated liquid is extremely high. As for the amount of chemicals used, the present invention achieves the same SS removal rate as 50% as compared with the case where a coagulant is directly added to a conventional gravity concentration tank.
% Or less, which has the effect of reducing chemical costs. Alternatively, if the volume of the coagulation / separation tank is increased to 10 times without using an additive in the coagulation / separation tank, the same water quality can be obtained with the same amount of chemicals. Furthermore, in the present invention, since chemicals are added only to the concentrated separation liquid transferred from the concentration tank to the coagulation separation tank, the coagulation separation tank in the latter stage of the concentration tank may have a very small volume as compared with the former concentration tank. According to the small volume coagulation / separation tank, very high S
The S removal rate can be obtained, and the amount of chemicals added to the small-volume coagulation / separation tank can be the same SS removal rate as compared to the case where the coagulant is directly added to the conventional gravity concentration tank as described above. 50% or less, and there is an effect that the chemical cost can be reduced.
【図面の簡単な説明】
【図１】この発明の実施の形態１による濃縮凝集装置を
概略的に示すフロー図である。
【符号の説明】
１ 原水導入管
２ 流入槽
３ 濃縮槽
４ 凝集分離槽
５ 添加物供給手段
６ 薬品供給手段
７ 汚泥返送管
８ 処理水排出管BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow chart schematically showing a concentration-aggregation apparatus according to Embodiment 1 of the present invention. [Description of Signs] 1 Raw water introduction pipe 2 Inflow tank 3 Concentration tank 4 Coagulation separation tank 5 Additive supply means 6 Chemical supply means 7 Sludge return pipe 8 Treated water discharge pipe
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フロントページの続き
(72)発明者 石谷 純一
東京都港区芝浦三丁目６番18号 株式会社
西原環境衛生研究所内
(72)発明者 間瀬 博子
東京都港区芝浦三丁目６番18号 株式会社
西原環境衛生研究所内
Ｆターム(参考） 4D015 BA25 BA28 BB05 BB08 EA32
4D059 AA05 AA06 BE31 BE47 BE49
BE55 BE56 BE60 BE64 CB09
DA51 DA70
────────────────────────────────────────────────── ───
Continuation of front page
(72) Inventor Junichi Ishitani
3-6-18 Shibaura, Minato-ku, Tokyo Co., Ltd.
Nishihara Environmental Health Research Institute
(72) Inventor Hiroko Mase
3-6-18 Shibaura, Minato-ku, Tokyo Co., Ltd.
Nishihara Environmental Health Research Institute
F term (reference) 4D015 BA25 BA28 BB05 BB08 EA32
4D059 AA05 AA06 BE31 BE47 BE49
BE55 BE56 BE60 BE64 CB09
DA51 DA70