JP2010264424A

JP2010264424A - Organic wastewater treatment facility and method for operating the same

Info

Publication number: JP2010264424A
Application number: JP2009120122A
Authority: JP
Inventors: Tetsuo Narita; 哲雄成田; Ken Sato; 建佐藤; Tsuneaki Kobayashi; 恒明小林; Teruo Hongo; 輝雄本郷; Tetsuo Yamashita; 哲生山下; Akira Akashi; 昭赤司
Original assignee: KOBELCO ECO MAINTENANCE CO Ltd; KOBELCO ECO-MAINTENANCE CO Ltd; Kobelco Eco Solutions Co Ltd
Current assignee: KOBELCO ECO MAINTENANCE CO Ltd; KOBELCO ECO-MAINTENANCE CO Ltd; Shinko Pantec Co Ltd
Priority date: 2009-05-18
Filing date: 2009-05-18
Publication date: 2010-11-25
Anticipated expiration: 2029-05-18
Also published as: JP5119200B2

Abstract

<P>PROBLEM TO BE SOLVED: To quickly and easily reduce the load on a wastewater treatment facility when the organic substance concentration increases in a short time in raw water flowing into the wastewater treatment facility. <P>SOLUTION: The organic wastewater treatment facility includes a former stage solid-liquid separation device for separating solids from the raw water, a biological treatment tank for decomposing with activated sludge an organic substance in the water separated in the former stage solid-liquid separation device, and a latter stage solid-liquid separation device for separating the biologically treated liquid obtained in the biological treatment tank into sludge and treated liquid. When the organic substance concentration is over a prescribed value in the raw water, part of the excess sludge obtained in the latter stage solid-liquid separation device is mixed with the raw water before the inlet port of the former stage solid-liquid separation device. The soluble organic substance in the raw water is adsorbed and/or biologically decomposed by the mixed excess sludge. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

本発明は、原水中の溶解性有機物濃度が増加した場合にも、放流水の有機物濃度の増加を抑制しうる有機性廃水処理施設、及びそのような有機性廃水処理施設の運転方法に関する。 The present invention relates to an organic wastewater treatment facility capable of suppressing an increase in the organic matter concentration of effluent water even when the concentration of soluble organic matter in raw water increases, and an operating method of such an organic wastewater treatment facility.

下水等の一般的な廃水処理方法では、まず処理すべき原水を最初沈殿槽（最初沈殿池）に流入させ、固形物を沈殿分離させる。固形物は最初沈殿槽の底部に沈殿した後に槽外に排出され、上澄水は水面付近から流出され、生物処理槽へと供給される。次に、生物処理槽では、嫌気性及び／又は好気性微生物を用いて、生物処理槽内の処理水中の有機物等が分解される。生物処理槽の生物処理液は、最終沈殿槽（最終沈殿池）へと供給され、活性汚泥を沈殿分離する。そして、最終沈殿槽の水面付近から上澄水が取り出され、処理水として処理施設外へと放流される。 In a general wastewater treatment method such as sewage, first, raw water to be treated is allowed to flow into an initial sedimentation tank (initial sedimentation basin), and solid matter is precipitated and separated. The solid is first settled at the bottom of the settling tank and then discharged out of the tank, and the supernatant water is discharged from the vicinity of the water surface and supplied to the biological treatment tank. Next, in the biological treatment tank, anaerobic and / or aerobic microorganisms are used to decompose organic substances in the treated water in the biological treatment tank. The biological treatment liquid in the biological treatment tank is supplied to a final sedimentation tank (final sedimentation tank) to precipitate and separate activated sludge. And supernatant water is taken out from the water surface vicinity of a final sedimentation tank, and is discharged | emitted out of a treatment facility as treated water.

このような廃水処理方法では、負荷の変動に対する対策も必要となるが、例えば、特許文献１には、廃水の流入量増加に対して緩衝槽を設けることにより対処することが開示されている。また、特許文献２には、降雨等によって下水流量が急激に増加した場合、嫌気処理用の前段生物処理槽と好気処理用の後段生物処理槽との間で最終沈殿槽の上澄水を流通させ、上澄水の残部を、前段生物処理槽を経ることなく後段生物処理槽に流入させる方法が開示されている。 In such a wastewater treatment method, countermeasures against load fluctuations are also necessary. For example, Patent Document 1 discloses that a buffer tank is provided to cope with an increase in the amount of wastewater inflow. Further, in Patent Document 2, when the sewage flow rate suddenly increases due to rain or the like, the supernatant water of the final sedimentation tank is circulated between the front biological treatment tank for anaerobic treatment and the rear biological treatment tank for aerobic treatment. A method is disclosed in which the remaining supernatant is allowed to flow into the subsequent biological treatment tank without passing through the previous biological treatment tank.

最終沈殿槽で発生する余剰汚泥は、産業廃棄物の約半数を占めるといわれており、その減容化対策が研究されている。例えば、特許文献３には、廃水原水に微生物の電子受容体調整水を混入し、溶存酸素量が実質的に1mg/L以下の条件で曝気し、汚泥を沈殿分離処理した後、さらに溶存酸素量が実質的に1mg/L以下の条件で曝気すると共に上澄み水を電子受容体調整水として廃水原水に返送する処理方法を行うための処理装置が提案されている。 Surplus sludge generated in the final sedimentation tank is said to account for about half of industrial waste, and measures to reduce its volume have been studied. For example, in Patent Document 3, microbial electron acceptor adjustment water is mixed in raw wastewater, and the amount of dissolved oxygen is aerated under a condition of substantially 1 mg / L or less. A treatment apparatus has been proposed for carrying out a treatment method in which the amount of aeration is substantially 1 mg / L or less and the supernatant water is returned to the wastewater raw water as electron acceptor adjustment water.

また、有機性廃水の生物処理施設において、負荷変動に対処するために前段生物処理槽及び後段生物処理槽という２つの生物処理槽によって有機物を分解し、前段生物処理槽にて処理された後の混合水を水質測定槽に導き、溶存酸素センサの計測値を利用して後段生物処理槽の処理能力の後段生物処理槽に流入する混合水の負荷量に対する過不足度を判断し、前段生物処理槽の曝気量を制御する方法が、特許文献４に開示されている。 Moreover, in a biological treatment facility for organic wastewater, organic matter is decomposed by two biological treatment tanks, a first-stage biological treatment tank and a second-stage biological treatment tank, in order to cope with load fluctuations, and after being processed in the first-stage biological treatment tank. Lead the mixed water to the water quality measurement tank, and use the measured value of the dissolved oxygen sensor to determine the excess or deficiency of the mixed water flowing into the latter biological treatment tank with the treatment capacity of the latter biological treatment tank. A method for controlling the amount of aeration in the tank is disclosed in Patent Document 4.

特開平５−１９２６８８号公報JP-A-5-192688 特開２００５−２６２１４０号公報JP 2005-262140 A 特許第３６６７２５４号公報Japanese Patent No. 3667254 特開２００８−１６１８５５号公報JP 2008-161855 A

原水中の有機物濃度が上昇すれば、好気性生物処理槽における曝気量を増やしたり、活性汚泥による有機物の生物処理を活性化させるように温度、pH等を調整することにより、処理水中の有機物濃度の上昇を抑制することは可能である。しかし、原水の発生源によっては、原水中の溶解性有機物濃度が一時的に急上昇することがある。 If the organic matter concentration in the raw water increases, the aeration rate in the aerobic biological treatment tank is increased, or the organic matter concentration in the treated water is adjusted by adjusting the temperature, pH, etc. to activate the biological treatment of organic matter with activated sludge. It is possible to suppress the rise of However, depending on the source of the raw water, the concentration of soluble organic substances in the raw water may rise rapidly.

このような場合、特許文献１〜３に開示されている方法では、原水中の溶解性有機物濃度が急増した場合に、廃水処理施設の放流水の有機物濃度が上昇することを抑制することは困難である。また、特許文献４に開示されている方法でも、前段生物処理槽の曝気量を増やしても生物処理能力を急に上昇させることは不可能であるため、原水中の溶解性有機物濃度が急増した場合には、やはり放流水の有機物濃度が高くなり、水質が悪化せざるを得ない。 In such a case, in the methods disclosed in Patent Documents 1 to 3, it is difficult to suppress an increase in the organic matter concentration of the discharged water of the wastewater treatment facility when the concentration of the soluble organic matter in the raw water increases rapidly. It is. In addition, even in the method disclosed in Patent Document 4, it is impossible to increase the biological treatment capacity suddenly even if the aeration amount of the previous biological treatment tank is increased, so the concentration of soluble organic matter in the raw water has increased rapidly. In some cases, the organic matter concentration in the discharged water becomes high, and the water quality is inevitably deteriorated.

本発明は、原水中の溶解性有機物濃度が急増した場合に、容易かつ迅速に対応しうる有機性廃水処理施設及びそうした有機性廃水処理施設の運転方法の提供を目的とする。 An object of the present invention is to provide an organic wastewater treatment facility that can easily and quickly cope with a rapidly increasing concentration of dissolved organic matter in raw water, and an operation method of such an organic wastewater treatment facility.

本発明者は、活性汚泥には溶解性有機物を吸着する能力があることから活性汚泥の余剰分である余剰汚泥を原水に混合し固形分を分離すれば、生物処理槽の負荷を軽減できることを見出し、本発明を完成させるに至った。 The present inventor has the ability to adsorb soluble organic matter in the activated sludge, so that it is possible to reduce the load on the biological treatment tank by mixing the excess sludge, which is the surplus of activated sludge, with the raw water and separating the solid content. The headline and the present invention have been completed.

具体的に、本発明は、
原水中の固形物を分離する前段固液分離装置と、
前段固液分離装置で得られた分離水中の有機物を活性汚泥によって分解する生物処理槽と、
生物処理槽で得られた生物処理液を汚泥と処理水とに分離する後段固液分離装置と、
を備える有機性廃水処理施設において、
原水の有機物濃度が所定濃度を超えた場合には、後段固液分離装置にて得られた余剰汚泥の一部を前段固液分離装置の流入部より前で原水と混合することを特徴とする、有機性廃水処理施設の運転方法に関する。 Specifically, the present invention
A first-stage solid-liquid separation device for separating solids in raw water;
A biological treatment tank for decomposing organic matter in the separated water obtained by the former solid-liquid separator with activated sludge;
A subsequent solid-liquid separation device for separating the biological treatment liquid obtained in the biological treatment tank into sludge and treated water;
In an organic wastewater treatment facility comprising
When the organic matter concentration of the raw water exceeds a predetermined concentration, a part of the excess sludge obtained in the latter-stage solid-liquid separator is mixed with the raw water before the inflow portion of the former-stage solid-liquid separator. The present invention relates to a method for operating an organic wastewater treatment facility.

また、本発明は、
原水中の固形物を分離する前段固液分離装置と、
前段固液分離装置で得られた分離水中の有機物を活性汚泥によって分解する生物処理槽と、
生物処理槽で得られた生物処理液を汚泥と処理水とに分離する後段固液分離装置と、
を備える有機性廃水処理施設であって、
後段固液分離装置にて得られた余剰汚泥の一部を原水に混合するための余剰汚泥供給経路を設け、
通常時には余剰汚泥供給経路を閉じ、
原水の有機物濃度が所定濃度を超えた場合には余剰汚泥供給経路を開き、余剰汚泥の一部を原水と混合することを特徴とする、有機性廃水処理施設に関する。 The present invention also provides:
A first-stage solid-liquid separation device for separating solids in raw water;
A biological treatment tank for decomposing organic matter in the separated water obtained by the former solid-liquid separator with activated sludge;
A subsequent solid-liquid separation device for separating the biological treatment liquid obtained in the biological treatment tank into sludge and treated water;
An organic wastewater treatment facility comprising:
Provide a surplus sludge supply path for mixing a part of the surplus sludge obtained in the latter solid-liquid separator with the raw water,
Normally, the surplus sludge supply route is closed,
The present invention relates to an organic wastewater treatment facility characterized in that when the organic matter concentration of raw water exceeds a predetermined concentration, the surplus sludge supply path is opened and a part of the surplus sludge is mixed with raw water.

後段固液分離装置では、生物処理槽中の汚泥を分離し、余剰分は余剰汚泥として抜き取られることによって除去される。この余剰汚泥には、溶解性有機物を吸着及び／又は分解する好気性微生物が含まれている。 In the latter-stage solid-liquid separator, the sludge in the biological treatment tank is separated, and the excess is removed by being extracted as excess sludge. This surplus sludge contains aerobic microorganisms that adsorb and / or decompose soluble organic matter.

本発明では、通常時（すなわち、原水の有機物濃度が有機性廃水処理施設の設計濃度以下である場合）には、後段固液分離装置から抜き取った余剰汚泥を廃棄し、所定濃度を超えた（原水の有機物濃度が有機性廃水処理施設の設計濃度を超えた）場合には、固液分離装置から抜き取った余剰汚泥の一部を原水と混合し、余剰汚泥によって過剰な溶解性有機物を吸着除去する。 In the present invention, during normal times (that is, when the organic matter concentration of the raw water is equal to or lower than the design concentration of the organic wastewater treatment facility), excess sludge extracted from the subsequent solid-liquid separation device is discarded and exceeds a predetermined concentration ( If the organic matter concentration in the raw water exceeds the design concentration of the organic wastewater treatment facility), a part of the excess sludge extracted from the solid-liquid separator is mixed with the raw water, and the excess sludge is adsorbed and removed by the excess sludge. To do.

また、余剰汚泥は溶解性有機物濃度が低いため、溶解性有機物質濃度が高い原水に対しては、高い処理能力を発揮しうる。このため、本発明では、原水に混合された余剰汚泥によって、原水中の溶解性有機物を効率よく吸着及び／又は分解することが可能である。 Moreover, since the excess sludge has a low soluble organic substance concentration, it can exhibit a high treatment capacity for raw water having a high soluble organic substance concentration. For this reason, in this invention, it is possible to adsorb | suck and / or decompose | disassemble efficiently the soluble organic substance in raw | natural water with the excess sludge mixed with raw | natural water.

原水に混合された余剰汚泥は、原水中の溶解性有機物を吸着及び／又は分解した後、前段固液分離装置にて固形分と分離水とに分離する。この分離した固形分は、原水に含まれる有機性固形物等と共に、適宜前段固液分離装置から抜き取られて廃棄されるため、余剰汚泥に吸着した溶解性有機物が後段の好気的生物処理槽へと流入することはない。このため、生物処理槽への有機物負荷の上昇を抑制できるので、処理水質の悪化を抑制でき、好気性生物処理の場合には、曝気量の増加（それに伴う曝気電力量の増加）も抑制できる。 The excess sludge mixed with the raw water is adsorbed and / or decomposed with the soluble organic matter in the raw water, and then separated into solids and separated water by the former solid-liquid separator. The separated solids are extracted from the former solid-liquid separation device and discarded together with the organic solids contained in the raw water, so that the dissolved organic matter adsorbed on the excess sludge is the latter aerobic biological treatment tank. Will not flow into. For this reason, since the increase in the organic substance load to the biological treatment tank can be suppressed, deterioration of the treated water quality can be suppressed, and in the case of aerobic biological treatment, an increase in the aeration amount (an increase in the aeration electric energy associated therewith) can also be suppressed. .

前記余剰汚泥供給経路の出口側は、前段固液分離装置の原水供給経路に接続し、原水と余剰汚泥を混合して前段固液分離装置内に供給すれば、原水の流れる力を利用しうるために、攪拌機などの特別な装置なしで充分に余剰汚泥を撹拌することが可能である。 The outlet side of the surplus sludge supply path is connected to the raw water supply path of the former solid-liquid separator, and if raw water and surplus sludge are mixed and supplied into the former solid-liquid separator, the flow force of the raw water can be used. Therefore, it is possible to sufficiently stir excess sludge without a special device such as a stirrer.

前記前段固液分離装置に流入させる原水に添加する余剰汚泥濃度は、0.03 kg-SS/m³以上0.2kg-SS/m³以下となるように調整することが好ましい。 Excess sludge concentration to be added to the raw water to flow into the front solid-liquid separator is preferably adjusted to be 0.03 kg-SS / m ³ or more 0.2kg-SS / m ³ or less.

本発明の有機性廃水処理施設及びその運転方法によれば、原水中の有機物濃度が急増した場合であっても、生物処理槽の負荷を、容易かつ迅速に軽減することが可能である。 According to the organic wastewater treatment facility and the method of operating the same of the present invention, it is possible to easily and quickly reduce the load on the biological treatment tank even when the concentration of organic matter in the raw water increases rapidly.

本発明の有機性廃水処理施設の一例における通常時の処理フローを示す図である。It is a figure which shows the processing flow at the normal time in an example of the organic wastewater treatment facility of this invention. 本発明の有機性廃水処理施設の一例における負荷増大時の処理フローを示す図である。It is a figure which shows the processing flow at the time of load increase in an example of the organic wastewater treatment facility of this invention. 実施の形態２の有機性廃水処理施設の構成を説明する図である。It is a figure explaining the structure of the organic waste water treatment facility of Embodiment 2. FIG. 撹拌時間及び余剰汚泥混合率を変化させた場合における、上澄水のTOC測定結果を表すグラフである。It is a graph showing the TOC measurement result of supernatant water when changing the stirring time and the excess sludge mixing ratio. 撹拌時間及び余剰汚泥混合率を変化させた場合における、上澄水のS-TOC測定結果を表すグラフである。It is a graph showing the S-TOC measurement result of supernatant water in the case of changing stirring time and excess sludge mixing rate. 撹拌時間１分における、上澄水のTOC測定結果を表すグラフである。It is a graph showing the TOC measurement result of supernatant water in stirring time 1 minute. 撹拌時間１分における、上澄水のS-TOC測定結果を表すグラフである。It is a graph showing the S-TOC measurement result of supernatant water in stirring time 1 minute. 余剰汚泥によるTOC除去量を表すグラフである。It is a graph showing the amount of TOC removal by excess sludge. 余剰汚泥によるTOC除去率を表すグラフである。It is a graph showing the TOC removal rate by excess sludge. 余剰汚泥によるS-TOC除去量を表すグラフである。It is a graph showing the amount of S-TOC removal by excess sludge. 余剰汚泥によるS-TOC除去率を表すグラフである。It is a graph showing the S-TOC removal rate by excess sludge. 余剰汚泥単位重量あたりのTOC除去量を表すグラフである。It is a graph showing the amount of TOC removal per unit weight of excess sludge. 余剰汚泥単位重量あたりのTOC除去率を表すグラフである。It is a graph showing the TOC removal rate per unit weight of excess sludge.

以下、本発明の実施の形態について、適宜図面を参酌しながら説明する。なお、本発明は、以下の記載に限定されない。 Hereinafter, embodiments of the present invention will be described with reference to the drawings as appropriate. The present invention is not limited to the following description.

＜実施の形態１＞
（通常時）
まず、前段固液分離装置として最初沈殿槽、好気性生物処理槽、後段固液分離装置として最終沈殿槽を各１基備える有機性廃水処理施設としての下水処理場における処理フローを、図１に基づいて説明する。原水（有機性廃水）は経路１から原水槽２に一旦貯水された後、経路３を経て最初沈殿槽４へと供給される。最初沈殿槽４では、懸濁物質等が沈殿除去される。 <Embodiment 1>
(Normal time)
First, FIG. 1 shows a treatment flow in a sewage treatment plant as an organic wastewater treatment facility equipped with a first settling tank, an aerobic biological treatment tank as a first-stage solid-liquid separation apparatus, and a final settling tank as one latter-stage solid-liquid separation apparatus. This will be explained based on. The raw water (organic waste water) is temporarily stored in the raw water tank 2 from the path 1 and then supplied to the first sedimentation tank 4 via the path 3. In the first settling tank 4, suspended substances and the like are removed by precipitation.

最初沈殿槽４の上澄水は、経路５を経て好気性生物処理槽６へと供給される。好気的生物処理槽６では、ブロア７によって廃水中に空気が吹き込まれ、活性汚泥によって廃水中の有機物が好気的に生物分解される。一定時間処理を行った後、好気性生物処理槽６中の生物処理液は、経路８を経て最終沈殿槽９へと供給される。 First, the supernatant water of the sedimentation tank 4 is supplied to the aerobic biological treatment tank 6 via the path 5. In the aerobic biological treatment tank 6, air is blown into the wastewater by the blower 7, and the organic matter in the wastewater is aerobically biodegraded by the activated sludge. After the treatment for a certain time, the biological treatment liquid in the aerobic biological treatment tank 6 is supplied to the final sedimentation tank 9 via the path 8.

最終沈殿槽９へは、好気性生物処理槽６の活性汚泥が流入するため、最終沈殿槽９の底部には活性汚泥が徐々に沈殿する。最終沈殿槽９の上澄水は、処理水として経路１０を経て放流される。最終沈殿槽９の底部に沈殿した汚泥は、一部は返送汚泥として汚泥返送経路１２によって、好気性生物処理槽６に返送される。この返送によって、好気的生物処理槽６内の活性汚泥量を一定範囲に維持することが可能である。 Since the activated sludge from the aerobic biological treatment tank 6 flows into the final sedimentation tank 9, the activated sludge gradually settles at the bottom of the final sedimentation tank 9. The supernatant water of the final sedimentation tank 9 is discharged via the path 10 as treated water. Part of the sludge that has settled at the bottom of the final sedimentation tank 9 is returned to the aerobic biological treatment tank 6 through the sludge return path 12 as return sludge. By this return, the amount of activated sludge in the aerobic biological treatment tank 6 can be maintained within a certain range.

また、最終沈殿槽９の底部に沈殿した汚泥の余剰分は、余剰汚泥として適宜、経路１１から抜き取られ、廃棄される。 Moreover, the excess of the sludge settled at the bottom of the final sedimentation tank 9 is appropriately extracted from the path 11 as excess sludge and discarded.

経路１１には、余剰汚泥供給経路１３も接続しており、経路１１との接続部の反対側（余剰汚泥出口側）は、経路３へと接続している。汚泥返送経路１２には、バルブ１４が設けられているが、通常時にはバルブ１４は閉じており、経路１１から取り出された余剰汚泥の一部は、原水へは供給されない。 The surplus sludge supply path 13 is also connected to the path 11, and the side opposite to the connection portion with the path 11 (the surplus sludge outlet side) is connected to the path 3. Although the valve 14 is provided in the sludge return path 12, the valve 14 is normally closed, and a part of the excess sludge taken out from the path 11 is not supplied to the raw water.

（負荷上昇時）
次に、原水の溶解性有機物濃度が、有機性廃水処理施設の処理能力を超える程度に上昇した場合の余剰汚泥の原水への供給について、図２に基づいて説明する。なおここでは、通常時との相違点である余剰汚泥供給経路１３による余剰汚泥の原水への供給に関する部分を説明する。 (When load increases)
Next, the supply of surplus sludge to the raw water when the concentration of soluble organic matter in the raw water rises to a level exceeding the treatment capacity of the organic wastewater treatment facility will be described with reference to FIG. In addition, the part regarding the supply to the raw | natural water of the excess sludge by the excess sludge supply path | route 13 which is a difference with the normal time is demonstrated here.

原水の有機物濃度が上昇すると、好気性生物処理槽６の処理能力が不足し、充分に有機物を生物分解できない。このため、最終沈殿槽９へと溶解性有機物濃度の高い生物処理液が流入し、結果として経路１０から放流される処理水の溶解性有機物濃度も基準値よりも高くなり、処理水質が悪化することになる。曝気装置１８の曝気量を増やせば、好気性生物処理槽６の処理能力をある程度向上させることもできるが、急激に有機物濃度が上昇した場合、好気性微生物を用いた生物分解であるため、処理能力を急に向上させることは困難である。 When the organic matter concentration in the raw water increases, the treatment capacity of the aerobic biological treatment tank 6 is insufficient, and the organic matter cannot be sufficiently biodegraded. For this reason, the biological treatment liquid having a high concentration of dissolved organic matter flows into the final sedimentation tank 9, and as a result, the concentration of soluble organic matter in the treated water discharged from the path 10 also becomes higher than the reference value, and the quality of the treated water is deteriorated. It will be. If the aeration amount of the aeration apparatus 18 is increased, the treatment capacity of the aerobic biological treatment tank 6 can be improved to some extent. However, when the organic substance concentration is rapidly increased, the treatment is performed due to biodegradation using aerobic microorganisms. It is difficult to improve ability suddenly.

そこで、本発明では、有機物濃度が所定値を超えればバルブ１４を開き、経路１１から抜き出された余剰汚泥の一部を、余剰汚泥供給経路１３及び経路３を経て、最初沈殿槽４へと返送する。原水の有機物濃度は、図２においては、原水槽２に設置した有機物濃度計１６によって測定している。有機物濃度計１６の信号は、経路１７によってバルブ１４に伝えられ、バルブ１４の開閉が調整される。 Therefore, in the present invention, if the organic substance concentration exceeds a predetermined value, the valve 14 is opened, and a part of the excess sludge extracted from the path 11 is passed through the excess sludge supply path 13 and the path 3 to the initial settling tank 4. Return it. The organic matter concentration of the raw water is measured by an organic matter concentration meter 16 installed in the raw water tank 2 in FIG. The signal of the organic substance concentration meter 16 is transmitted to the valve 14 through the path 17 and the opening / closing of the valve 14 is adjusted.

なお、原水の溶解性有機物濃度は、有機物濃度計によってリアルタイムで測定することが好ましいが、JIS K0102（工場排水試験法）に規定されているCOD（化学的酸素要求量）を定時的に測定し、その測定結果に応じてバルブ１４の開閉を調整することも可能である。また、溶解性有機物濃度と電気伝導度の相関性をあらかじめ把握しておき、電気伝導度を測定することにより有機物濃度を算出してもよい。 The dissolved organic matter concentration of raw water is preferably measured in real time with an organic matter concentration meter, but the COD (chemical oxygen demand) specified in JIS K0102 (Factory Wastewater Test Method) is regularly measured. It is also possible to adjust the opening / closing of the valve 14 according to the measurement result. Further, the correlation between the soluble organic substance concentration and the electric conductivity may be grasped in advance, and the organic substance concentration may be calculated by measuring the electric conductivity.

余剰汚泥供給経路１３と経路３とが接続されているため、原水の流れの持つ力で経路３から最初沈殿槽４へ原水と余剰汚泥が混合された状態で供給される。このため、最初沈殿槽４では、撹拌装置がなくとも原水と余剰汚泥を撹拌することができる。なお、原水と余剰汚泥を混合してから最初沈殿槽４へと供給するまでの時間は、30秒以上とすることが好ましい。 Since the excess sludge supply path 13 and the path 3 are connected, the raw water and the excess sludge are supplied in a mixed state from the path 3 to the first settling tank 4 by the force of the raw water flow. For this reason, in the first settling tank 4, raw water and excess sludge can be stirred without a stirring device. In addition, it is preferable that the time from mixing raw water and excess sludge to supplying it to the first settling tank 4 is 30 seconds or more.

原水の流れの持つ力で原水と余剰汚泥を最良の混合状態に混合するためには30秒程度が必要とされるが、それに満たない場合でも最初沈殿槽４へ供給後に混合が進行するため、有機物の除去効果は発揮される。 About 30 seconds are required to mix the raw water and surplus sludge to the best mixing state with the power of the raw water flow, but even if it is less than that, mixing proceeds after the feed to the first settling tank 4, The organic substance removal effect is exhibited.

原水と混合された余剰汚泥は、最初沈殿槽４へ流入する間に原水中の溶解性有機物を吸着し、最初沈殿槽４に流入した後は最初沈殿槽４の底部へと沈殿する。このとき、余剰汚泥は、最初沈殿槽４内で有機物を生物分解する能力を有するため、有機物を吸着除去する以外に、曝気処理がない状態であっても、原水中の溶存酸素を利用して、有機物を生物分解することが期待しうる。 The surplus sludge mixed with the raw water adsorbs the soluble organic matter in the raw water while first flowing into the settling tank 4, and settles to the bottom of the first settling tank 4 after flowing into the first settling tank 4. At this time, surplus sludge has the ability to biodegrade organic matter in the sedimentation tank 4 at the beginning, so that dissolved oxygen in raw water is used even in the absence of aeration treatment other than adsorption and removal of organic matter. Biodegradation of organic matter can be expected.

このとき、最初沈殿槽４の底部に沈殿した余剰汚泥は、有機物を吸着したまま汚泥排出経路１５から抜き取られるため、原水と混合された余剰汚泥と、余剰汚泥が吸着した溶解性有機物とは、後段の好気性生物処理槽６へは流入することがない。 At this time, the excess sludge that has first settled at the bottom of the settling tank 4 is extracted from the sludge discharge path 15 while adsorbing the organic matter. It does not flow into the aerobic biological treatment tank 6 at the subsequent stage.

最初沈殿槽４内で原水中の有機物が吸着及び／又は生物分解されることにより、経路５を経て好気的生物処理槽６へと供給される上澄水の有機物濃度が減少し、原水の溶解性有機物濃度が急増した場合であっても、好気的生物処理槽６の負荷急増を抑制することが可能である。 First, the organic matter in the raw water is adsorbed and / or biodegraded in the sedimentation tank 4, so that the organic matter concentration in the supernatant water supplied to the aerobic biological treatment tank 6 via the path 5 is reduced and the raw water is dissolved. Even when the concentration of the organic organic substance is rapidly increased, it is possible to suppress the rapid increase in the load of the aerobic biological treatment tank 6.

余剰汚泥供給経路１３による余剰汚泥の供給は、原水の有機物濃度が有機性廃水処理施設の設計処理濃度よりも10％超えた場合に行うことが好ましい。このとき、前段固液分離装置に流入させる原水に添加する余剰汚泥量は、原水1m³あたり余剰汚泥0.03〜0.2kg-SSである。すなわち、添加後の原水中の余剰汚泥濃度が好ましくは0.03 kg-SS/m³以上0.2kg-SS/m³以下となるように調整する。 The supply of excess sludge through the excess sludge supply path 13 is preferably performed when the organic matter concentration of raw water exceeds 10% of the design treatment concentration of the organic wastewater treatment facility. At this time, the amount of excess sludge added to the raw water flowing into the preceding solid-liquid separator is 0.03 to 0.2 kg-SS of excess sludge per 1 m ^{3 of} raw water. That is, excess sludge concentration in the raw water after the addition is preferably adjusted to be 0.03 kg-SS / m ³ or more 0.2kg-SS / m ³ or less.

原水の溶解性有機物濃度が減少し、通常濃度に戻れば、原水槽２に設置した有機物濃度計１６の信号によってバルブ１４が閉じられ、汚泥返送経路１３による余剰汚泥の返送を中止する。こうして、通常時の運転に戻る。 When the concentration of the dissolved organic matter in the raw water decreases and returns to the normal concentration, the valve 14 is closed by a signal from the organic matter concentration meter 16 installed in the raw water tank 2 and the return of excess sludge through the sludge return path 13 is stopped. Thus, the normal operation is resumed.

なお、最初沈殿槽４は、膜分離装置に代えてもよく、最終沈殿槽９も膜分離装置に代えてもよい。 The first settling tank 4 may be replaced with a membrane separator, and the final settling tank 9 may be replaced with a membrane separator.

＜実施の形態２＞
実施の形態１では、好気性生物処理槽と最終沈殿槽（後段固液分離装置）とが独立した構造であったが、図３に示すように、好気性生物処理槽と固液分離装置とが一体化した構造であってもよい。図３の例では、経路５を経て供給される沈殿槽２２の上澄液は、膜分離活性汚泥処理装置２１内で活性汚泥法によって有機物が生物分解された後、浸漬膜分離装置１９によってろ過され、その透過水が処理水として経路２０から排水される。 <Embodiment 2>
In the first embodiment, the aerobic biological treatment tank and the final sedimentation tank (the latter solid-liquid separation device) are independent structures, but as shown in FIG. 3, the aerobic biological treatment tank, the solid-liquid separation device, May be an integrated structure. In the example of FIG. 3, the supernatant of the sedimentation tank 22 supplied via the path 5 is filtered by the submerged membrane separation device 19 after the organic matter is biodegraded by the activated sludge method in the membrane separation activated sludge treatment device 21. Then, the permeated water is drained from the path 20 as treated water.

浸漬膜分離装置１９によるろ過により、処理液の汚泥濃度は徐々に上昇するが、膜分離活性汚泥処理装置２１内の余剰汚泥は、適宜汚泥経路１１から抜き取られるため、汚泥濃度を一定範囲内に調整することが可能である。なお、図３の有機性廃水処理施設では、汚泥返送経路は不要である。 Although the sludge concentration of the treatment liquid gradually increases by filtration by the submerged membrane separation device 19, the excess sludge in the membrane separation activated sludge treatment device 21 is appropriately extracted from the sludge passage 11, so that the sludge concentration is within a certain range. It is possible to adjust. Note that the sludge return route is not required in the organic wastewater treatment facility of FIG.

汚泥経路１１から抜き取られた余剰汚泥の一部は、原水の溶解性有機物濃度が上昇した場合には、実施の形態１と同様に、余剰汚泥供給経路１３及び経路３を経て、原水へ混合される。 A portion of the excess sludge extracted from the sludge path 11 is mixed into the raw water via the excess sludge supply path 13 and the path 3 as in the first embodiment when the concentration of soluble organic matter in the raw water increases. The

なお、膜分離活性汚泥処理装置２１の浸漬膜分離装置１９としては、精密膜分離装置、限外ろ過膜分離装置等、公知の膜分離装置を利用することが可能である。また、沈殿槽２２は、膜分離装置に代えてもよい。 In addition, as the submerged membrane separation device 19 of the membrane separation activated sludge treatment device 21, a known membrane separation device such as a precision membrane separation device or an ultrafiltration membrane separation device can be used. Moreover, you may replace the precipitation tank 22 with a membrane separator.

本発明の有機性廃水処理施設の運転方法は、余剰汚泥供給経路を設けるという簡単な改造によって、既存の有機性廃水処理施設においても実施可能である。 The operation method of the organic wastewater treatment facility of the present invention can also be implemented in an existing organic wastewater treatment facility by a simple modification of providing an excess sludge supply path.

なお、上記実施の形態１及び実施の形態２では、生物処理は好気性生物処理槽単独で行う場合について説明したが、嫌気性生物処理槽と好気性生物処理槽とを組み合わせてもよい。 In the first embodiment and the second embodiment, the case where the biological treatment is performed in the aerobic biological treatment tank alone has been described. However, the anaerobic biological treatment tank and the aerobic biological treatment tank may be combined.

（余剰汚泥による負荷軽減実験）
有機性廃水処理施設において、原水の溶解性有機物濃度上昇時に余剰汚泥を原水へ混合することを想定し、ビーカーに原水及び最終沈殿槽の余剰汚泥を投入し、攪拌翼によって一定時間撹拌した。60分間静置した後、上澄水を採取した。そして、原水及び上澄水の懸濁物質濃度（SS）、全有機性炭素濃度（TOC）及び溶解性全有機性炭素濃度（S-TOC）を測定した。原水及び余剰汚泥のSS、TOC及びS-TOCを、表１に示す。 (Load reduction experiment using excess sludge)
In an organic wastewater treatment facility, it was assumed that surplus sludge was mixed with raw water when the concentration of dissolved organic matter in the raw water increased, and the raw water and surplus sludge from the final sedimentation tank were charged into a beaker and stirred for a certain time with a stirring blade. After standing for 60 minutes, the supernatant water was collected. Then, the suspended solids concentration (SS), total organic carbon concentration (TOC), and soluble total organic carbon concentration (S-TOC) were measured. Table 1 shows SS, TOC and S-TOC of raw water and excess sludge.

また、原水に対する余剰汚泥（最終沈殿槽より引き抜いた汚泥）の混合割合は、表２に示すとおり0〜20容量％とした。原水と余剰汚泥の撹拌時間は、1〜20分とした。 Moreover, as shown in Table 2, the mixing ratio of excess sludge (raw sludge extracted from the final sedimentation tank) to the raw water was set to 0 to 20% by volume. The stirring time of the raw water and excess sludge was 1 to 20 minutes.

まず、原水と余剰汚泥の撹拌時間を1〜20分とし、余剰汚泥混合率を1〜20容量%とした場合における、ろ液のTOC濃度とS-TOC濃度の測定結果を、それぞれ図４及び図５に示す。余剰汚泥混合率が高いほど、ろ液のTOC濃度及びS-TOC濃度が低くなることが確認されたが、撹拌時間による影響はほとんど認められなかった。なお、同様の実験を撹拌時間30秒として行ったが、ろ液のTOC濃度及びS-TOC濃度は撹拌時間1分とほぼ同じであった。 First, the measurement results of the TOC concentration and S-TOC concentration of the filtrate when the stirring time of raw water and excess sludge is 1 to 20 minutes and the excess sludge mixing ratio is 1 to 20% by volume are shown in FIG. As shown in FIG. It was confirmed that the higher the excess sludge mixing ratio, the lower the TOC concentration and S-TOC concentration of the filtrate, but almost no influence was found due to the stirring time. The same experiment was conducted with a stirring time of 30 seconds, but the TOC concentration and S-TOC concentration of the filtrate were almost the same as the stirring time of 1 minute.

次に、原水中の余剰汚泥濃度を0.03〜0.8kg-SS/m³と変化させ、撹拌時間を1分とした場合における、ろ液のTOC濃度とS-TOC濃度の測定結果を、それぞれ図６及び図７に示す。余剰汚泥濃度が高くなるほど、ろ液のTOC及びS-TOCは低下した。なお、撹拌時間が30秒〜20分の範囲では、ろ液のTOC及びS-TOCはあまり変化しなかった。 Next, the measurement results of the TOC concentration and S-TOC concentration of the filtrate when the excess sludge concentration in the raw water is changed from 0.03 to 0.8 kg-SS / m ³ and the stirring time is 1 minute are shown in the figure. 6 and FIG. The higher the excess sludge concentration, the lower the TOC and S-TOC of the filtrate. In addition, when the stirring time was in the range of 30 seconds to 20 minutes, the TOC and S-TOC of the filtrate did not change much.

次に、原水中の余剰汚泥濃度を0.03〜0.8kg-SS/m³と変化させ、撹拌時間を1分とした場合における、TOC除去量及びTOC除去率を、それぞれ図８及び図９に示す。また、S-TOC除去量及びS-TOC除去率を、それぞれ図１０及び図１１に示す。TOCとS-TOCの濃度変化の挙動は類似しており、有機物が固形性であるか溶解性であるかに関しては、顕著な差は認められなかった。余剰汚泥濃度が高くなるにつれて、TOC等の除去量及び除去率は高くなった。 Next, the TOC removal amount and the TOC removal rate when the excess sludge concentration in the raw water is changed from 0.03 to 0.8 kg-SS / m ³ and the stirring time is 1 minute are shown in FIGS. 8 and 9, respectively. . The S-TOC removal amount and the S-TOC removal rate are shown in FIGS. 10 and 11, respectively. The behavior of TOC and S-TOC concentration changes was similar, and no significant difference was observed regarding whether the organic matter was solid or soluble. As the excess sludge concentration increased, the removal amount and removal rate of TOC and the like increased.

次に、原水中の余剰汚泥濃度を0.03〜0.8kg-SS/m³と変化させ、撹拌時間を1分とした場合における、余剰汚泥単位重量あたりのTOC除去量及びS-TOC除去量を、それぞれ図１２及び図１３に示す。余剰汚泥濃度が高くなるほど、余剰汚泥単位重量あたりのTOC及びS-TOCの除去効率が急激に低下した。 Next, when the excess sludge concentration in the raw water is changed from 0.03 to 0.8 kg-SS / m ³ and the stirring time is 1 minute, the TOC removal amount and S-TOC removal amount per unit weight of excess sludge They are shown in FIGS. 12 and 13, respectively. As the excess sludge concentration increased, the removal efficiency of TOC and S-TOC per unit weight of excess sludge decreased rapidly.

このため、最初沈殿槽内の余剰汚泥濃度が0.03kg-SS/m³以上0.8kg-SS/m³以下となるように、原水と余剰汚泥とを混合し、TOC及びS-TOC除去率を15％程度として運転することが実用的であると考察された。 Therefore, as excess sludge concentration in the first settling tank is 0.03kg-SS / m ³ or more 0.8kg-SS / m ³ or less, mixing the raw water and excess sludge, the TOC and S-TOC removal rate It was considered practical to drive at around 15%.

本発明の有機性廃水処理施設及びその運転方法は、原水の有機物濃度が変動しやすい有機性廃水処理施設及びその運転方法として、廃水処理分野において有用である。 The organic wastewater treatment facility and the operation method thereof according to the present invention are useful in the wastewater treatment field as an organic wastewater treatment facility and an operation method thereof in which the organic matter concentration of raw water is likely to vary.

１，３，５，８，１０，２０：経路
２：原水槽
４：最初沈殿槽（前段固液分離装置）
６：好気性生物処理槽
７：ブロア
９：最終沈殿槽（後段固液分離装置）
１１，１５：汚泥経路
１２：余剰汚泥供給経路
１３：汚泥返送経路
１４：バルブ
１６：有機物濃度計
１７：経路（電気経路）
１８：曝気装置（散気装置）
１９：浸漬膜分離装置
２１：膜分離活性汚泥処理装置（好気的生物処理槽＋固液分離装置）
２２：沈殿槽 1,3,5,8,10,20: Path 2: Raw water tank 4: First sedimentation tank (front solid-liquid separation device)
6: Aerobic biological treatment tank 7: Blower 9: Final sedimentation tank (second-stage solid-liquid separator)
11, 15: Sludge route 12: Surplus sludge supply route 13: Sludge return route 14: Valve 16: Organic substance concentration meter 17: Route (electric route)
18: Aeration device (aeration device)
19: Submerged membrane separation device 21: Membrane separation activated sludge treatment device (aerobic biological treatment tank + solid-liquid separation device)
22: Settling tank

Claims

原水中の固形物を分離する前段固液分離装置と、
前段固液分離装置で得られた分離水中の有機物を活性汚泥によって分解する生物処理槽と、
生物処理槽で得られた生物処理液を汚泥と処理水とに分離する後段固液分離装置と、
を備える有機性廃水処理施設において、
原水の有機物濃度が所定濃度を超えた場合には、後段固液分離装置にて得られた余剰汚泥の一部を前段固液分離装置の流入部より前で原水と混合することを特徴とする、有機性廃水処理施設の運転方法。 A first-stage solid-liquid separation device for separating solids in raw water;
A biological treatment tank for decomposing organic matter in the separated water obtained by the former solid-liquid separator with activated sludge;
A subsequent solid-liquid separation device for separating the biological treatment liquid obtained in the biological treatment tank into sludge and treated water;
In an organic wastewater treatment facility comprising
When the organic matter concentration of the raw water exceeds a predetermined concentration, a part of the excess sludge obtained in the latter-stage solid-liquid separator is mixed with the raw water before the inflow portion of the former-stage solid-liquid separator. , Operation method of organic wastewater treatment facility.

前記前段固液分離装置に流入させる原水に添加する余剰汚泥濃度を0.03 kg-SS/m³以上0.2kg-SS/m³以下となるように調整する、請求項１に記載の有機性廃水処理施設の運転方法。 Adjusting the excess sludge concentration to be added to the raw water to flow into the front solid-liquid separation device such that 0.03 kg-SS / m ³ or more 0.2kg-SS / m ³ or less, an organic waste water treatment according to claim 1 How to operate the facility.

原水中の固形物を分離する前段固液分離装置と、
前段固液分離装置で得られた分離水中の有機物を活性汚泥によって分解する生物処理槽と、
生物処理槽で得られた生物処理液を汚泥と処理水とに分離する後段固液分離装置と、
を備える有機性廃水処理施設であって、
後段固液分離装置にて得られた余剰汚泥の一部を原水に混合するための余剰汚泥供給経路を設け、
通常時には余剰汚泥供給経路を閉じ、
原水の有機物濃度が所定濃度を超えた場合には余剰汚泥供給経路を開き、余剰汚泥の一部を原水と混合することを特徴とする、有機性廃水処理施設。 A first-stage solid-liquid separation device for separating solids in raw water;
A biological treatment tank for decomposing organic matter in the separated water obtained by the former solid-liquid separator with activated sludge;
A subsequent solid-liquid separation device for separating the biological treatment liquid obtained in the biological treatment tank into sludge and treated water;
An organic wastewater treatment facility comprising:
Provide a surplus sludge supply path for mixing a part of the surplus sludge obtained in the latter solid-liquid separator with the raw water,
Normally, the surplus sludge supply route is closed,
An organic wastewater treatment facility characterized in that when the organic matter concentration of raw water exceeds a predetermined concentration, the surplus sludge supply path is opened and a part of the surplus sludge is mixed with raw water.

前記余剰汚泥供給経路の出口側が前段固液分離装置の原水供給経路に接続されている、請求項３に記載の有機性廃水処理施設。 The organic wastewater treatment facility according to claim 3, wherein an outlet side of the surplus sludge supply path is connected to a raw water supply path of a preceding solid-liquid separator.

前記前段固液分離装置に流入させる原水に添加する余剰汚泥濃度を0.03 kg-SS/m³以上0.2kg-SS/m³以下となるように調整する、請求項３又は４に記載の有機性廃水処理施設。
Adjusting the excess sludge concentration to be added to the raw water to flow into the front solid-liquid separation device such that 0.03 kg-SS / m ³ or more 0.2 kg-SS / m ³ or less, organic according to claim 3 or 4 Wastewater treatment facility.