JP4380290B2

JP4380290B2 - Nitrogen-containing organic wastewater treatment method and apparatus

Info

Publication number: JP4380290B2
Application number: JP2003358279A
Authority: JP
Inventors: 茂樹嘉義; 俊幸栗林; 佐智雄友納; 保彦石井
Original assignee: Kurita Water Industries Ltd
Current assignee: Kurita Water Industries Ltd
Priority date: 2003-10-17
Filing date: 2003-10-17
Publication date: 2009-12-09
Anticipated expiration: 2023-10-17
Also published as: JP2005118719A

Description

本発明は、含窒素有機性排水の処理方法および装置に関し、特にし尿等の含窒素有機性排水を好気的に処理し、有機物を除去するとともに硝化脱窒を行う処理方法および装置に関するものである。 The present invention relates to a method and apparatus for treating nitrogen-containing organic wastewater, and more particularly to a treatment method and apparatus for aerobically treating nitrogen-containing organic wastewater such as human waste to remove organic substances and perform nitrification denitrification. is there.

し尿等の含窒素有機性排水の処理方法および装置として、１次脱窒槽で含窒素有機性排水を硝化液と混合して生物脱窒するとともに有機物を分解し、１次硝化槽で硝化して硝化液の一部を１次脱窒槽に返送するとともに、残部を２次脱窒槽に導入して脱窒し、再曝気槽で再曝気した後、沈殿槽で沈殿分離し、汚泥の一部を第１脱窒槽に返送する方法および装置は良く知られている（例えば特許文献１）。また上記処理方法および装置において、沈澱槽の替わりに、曝気状態で膜分離する膜分離装置を設置し、汚泥と処理水の分離に膜分離を適用する方法も良く知られている（例えば特許文献２）。 As a treatment method and apparatus for nitrogen-containing organic wastewater such as human waste, nitrogen-containing organic wastewater is mixed with nitrification liquid in a primary denitrification tank to biologically denitrify, decompose organic matter, and nitrify in a primary nitrification tank. A part of the nitrification liquid is returned to the primary denitrification tank, and the remainder is introduced into the secondary denitrification tank for denitrification, re-aerated in the re-aeration tank, and then separated by precipitation in the settling tank, and a part of the sludge is removed. A method and an apparatus for returning to the first denitrification tank are well known (for example, Patent Document 1). Further, in the above processing method and apparatus, a method of installing a membrane separation device for membrane separation in an aerated state instead of a precipitation tank and applying membrane separation for separation of sludge and treated water is well known (for example, Patent Documents). 2).

図２はこれらを適用した従来の含窒素有機性排水の処理方法および装置を示すフロー図である。処理装置１０を構成する１次脱窒槽１は複数段の第１脱窒槽１ａ、第２脱窒槽１ｂ、第３脱窒槽１ｃ、第４脱窒槽１ｄからなり、１次硝化槽２は複数段の第１硝化槽２ａ、第２硝化槽２ｂ、第３硝化槽２ｃ、第４硝化槽２ｄからなり、これらは交互に配置され、続いて２次脱窒槽３、再曝気槽４、膜分離槽５、ポンプピット６が配置され、全体が１次脱窒槽１ａ側からポンプピット６側へ液が流れるようにシリーズに連絡している。 FIG. 2 is a flowchart showing a conventional nitrogen-containing organic wastewater treatment method and apparatus to which these are applied. The primary denitrification tank 1 constituting the processing apparatus 10 includes a plurality of stages of a first denitrification tank 1a, a second denitrification tank 1b, a third denitrification tank 1c, and a fourth denitrification tank 1d, and the primary nitrification tank 2 has a plurality of stages. The first nitrification tank 2a, the second nitrification tank 2b, the third nitrification tank 2c, and the fourth nitrification tank 2d are arranged alternately, followed by the secondary denitrification tank 3, the re-aeration tank 4, and the membrane separation tank 5. The pump pit 6 is arranged, and the whole communicates with the series so that the liquid flows from the primary denitrification tank 1a side to the pump pit 6 side.

原水路１１は分岐路１１ａ、１１ｂ、１１ｃ、１１ｄに分岐して、それぞれ第１脱窒槽１ａ、第２脱窒槽１ｂ、第３脱窒槽１ｃ、第４脱窒槽１ｄに連絡している。給気路１２は分岐路１２ａ、１２ｂ、１２ｃ、１２ｄ、１２ｅに分岐して、それぞれ第１硝化槽２ａ、第２硝化槽２ｂ、第３硝化槽２ｃ、第４硝化槽２ｄおよび再曝気槽４の下部に設けられた散気装置７ａ、７ｂ、７ｃ、７ｄ、７ｅに連絡している。２次脱窒槽３には、原水路１１は連絡せず、基質供給路１３が連絡している。 The raw water channel 11 branches into branch channels 11a, 11b, 11c, and 11d, and communicates with the first denitrification tank 1a, the second denitrification tank 1b, the third denitrification tank 1c, and the fourth denitrification tank 1d, respectively. The air supply path 12 is branched into branch paths 12a, 12b, 12c, 12d, and 12e, and the first nitrification tank 2a, the second nitrification tank 2b, the third nitrification tank 2c, the fourth nitrification tank 2d, and the re-aeration tank 4 respectively. The air diffusers 7a, 7b, 7c, 7d, and 7e provided at the lower part of the air diffuser are communicated. The secondary denitrification tank 3 does not communicate with the raw water channel 11 but communicates with the substrate supply channel 13.

膜分離槽５には膜モジュール８が配置され、その下部に設けられた散気装置７ｆに給気路１４が連絡している。膜モジュール８は分離膜８ａにより濃縮液室８ｂと透過液室８ｃとが区画され、濃縮液室８ｂが膜分離槽５と連通し、透過液室８ｃにはポンプＰ１を有する処理水路１５が連絡している。１次硝化槽２の最終段の第４硝化槽２ｄからポンプＰ２を有する硝化液循環路１６が１次脱窒槽１の第１脱窒槽１ａに連絡している。ポンプピット６からポンプＰ３を有する第１の返送路１７が１次脱窒槽１の第１脱窒槽１ａに連絡し、ポンプピット６からポンプＰ４を有する余剰汚泥路１８が系外に連絡している。 A membrane module 8 is disposed in the membrane separation tank 5, and an air supply path 14 communicates with an air diffuser 7f provided below the membrane module 8. In the membrane module 8, the concentrated liquid chamber 8b and the permeated liquid chamber 8c are partitioned by the separation membrane 8a, the concentrated liquid chamber 8b communicates with the membrane separation tank 5, and the permeated liquid chamber 8c communicates with the treatment water channel 15 having the pump P1. is doing. A nitrification liquid circulation path 16 having a pump P2 communicates with the first denitrification tank 1a of the primary denitrification tank 1 from the fourth nitrification tank 2d at the final stage of the primary nitrification tank 2. The first return passage 17 having the pump P3 from the pump pit 6 communicates with the first denitrification tank 1a of the primary denitrification tank 1, and the surplus sludge passage 18 having the pump P4 communicates from the pump pit 6 outside the system. .

上記の処理装置１０においては、原水（含窒素有機性排水）を原水路１１から分岐路１１ａ、１１ｂ、１１ｃ、１１ｄに分配して、それぞれ第１脱窒槽１ａ、第２脱窒槽１ｂ、第３脱窒槽１ｃ、第４脱窒槽１ｄに供給し、空気を給気路１２から分岐路１２ａ、１２ｂ、１２ｃ、１２ｄ、１２ｅに分配して、それぞれ第１硝化槽２ａ、第２硝化槽２ｂ、第３硝化槽２ｃ、第４硝化槽２ｄおよび再曝気槽４の下部に設けられた散気装置７ａ、７ｂ、７ｃ、７ｄ、７ｅに供給して曝気する。そして１次硝化槽２の最終段の第４硝化槽２ｄから硝化液を、ポンプＰ２により硝化液循環路１６から１次脱窒槽１の第１脱窒槽１ａに循環し、ポンプピット６の濃縮液を返送汚泥として、ポンプＰ３により第１の返送路１７から１次脱窒槽１の第１脱窒槽１ａに返送して処理を行う。 In the treatment apparatus 10, raw water (nitrogen-containing organic waste water) is distributed from the raw water channel 11 to the branch channels 11 a, 11 b, 11 c, and 11 d, and the first denitrification tank 1 a, second denitrification tank 1 b, and third respectively. The denitrification tank 1c and the fourth denitrification tank 1d are supplied, and the air is distributed from the air supply path 12 to the branch paths 12a, 12b, 12c, 12d, and 12e, and the first nitrification tank 2a, the second nitrification tank 2b, Aeration is performed by supplying to the aeration devices 7a, 7b, 7c, 7d, and 7e provided at the lower part of the third nitrification tank 2c, the fourth nitrification tank 2d, and the re-aeration tank 4. Then, the nitrification liquid is circulated from the fourth nitrification tank 2d at the final stage of the primary nitrification tank 2 from the nitrification liquid circulation path 16 to the first denitrification tank 1a of the primary denitrification tank 1 by the pump P2, and is concentrated in the pump pit 6. Is returned to the first denitrification tank 1a of the primary denitrification tank 1 from the first return path 17 by the pump P3 and processed.

第１脱窒槽１ａでは、含窒素有機性排水を循環硝化液および返送汚泥と混合して嫌気状態に保つことにより、脱窒菌の作用によって硝酸または亜硝酸性窒素を窒素ガスに還元して生物脱窒し、同時に原水中の有機物を基質として分解し、１次脱窒が行われる。第１脱窒槽１ａの脱窒液は第１硝化槽２ａに入り、曝気により残留有機物を分解するとともに、硝化菌の作用によって原水中のアンモニア性窒素を硝酸または亜硝酸性窒素に硝化する。第１硝化槽２ａの硝化液は第２脱窒槽１ｂに入って同様に脱窒され、その後順次第２硝化槽２ｂ、第３脱窒槽１ｃ、第３硝化槽２ｃ、第４脱窒槽１ｄおよび第４硝化槽２ｄに入って、硝化または脱窒を受ける。 In the first denitrification tank 1a, nitrogen-containing organic wastewater is mixed with the circulating nitrification liquid and the return sludge and kept in an anaerobic state to reduce nitric acid or nitrite nitrogen to nitrogen gas by the action of denitrifying bacteria, and biological desorption. Nitrogen is performed, and at the same time, organic matter in the raw water is decomposed as a substrate, and primary denitrification is performed. The denitrification liquid in the first denitrification tank 1a enters the first nitrification tank 2a, decomposes residual organic substances by aeration, and nitrifies ammoniacal nitrogen in the raw water into nitric acid or nitrite nitrogen by the action of nitrifying bacteria. The nitrification liquid in the first nitrification tank 2a enters the second denitrification tank 1b and is similarly denitrified, and then sequentially the second nitrification tank 2b, the third denitrification tank 1c, the third nitrification tank 2c, the fourth denitrification tank 1d and the first 4 Enters nitrification tank 2d and undergoes nitrification or denitrification.

このようにして１次脱窒槽１の複数段の第１脱窒槽１ａ、第２脱窒槽１ｂ、第３脱窒槽１ｃ、第４脱窒槽１ｄにおいて１次脱窒が行われ、１次硝化槽２の複数段の第１硝化槽２ａ、第２硝化槽２ｂ、第３硝化槽２ｃ、第４硝化槽２ｄにおいて１次硝化が行われる。第４硝化槽２ｄの１次硝化液は大部分が循環硝化液として第１脱窒槽１ａに循環するが、一部は２次脱窒槽３に入り、ここで含窒素有機性排水を混合することなく、基質供給路１３から供給されるメタノール等の実質的に窒素を含まない基質と混合して生物脱窒することにより、残留する硝酸または亜硝酸性窒素が除去され、２次脱窒が行われる。２次脱窒槽３の２次脱窒液は再曝気槽４に入り、ここで再曝気することにより、残留する有機物を分解する。 Thus, primary denitrification is performed in the first denitrification tank 1a, the second denitrification tank 1b, the third denitrification tank 1c, and the fourth denitrification tank 1d of the plurality of stages of the primary denitrification tank 1, and the primary nitrification tank 2 Primary nitrification is performed in the first nitrification tank 2a, the second nitrification tank 2b, the third nitrification tank 2c, and the fourth nitrification tank 2d. Most of the primary nitrification liquid in the fourth nitrification tank 2d circulates as a circulation nitrification liquid to the first denitrification tank 1a, but a part enters the secondary denitrification tank 3 where nitrogen-containing organic waste water is mixed. The remaining nitric acid or nitrite nitrogen is removed by mixing with a substrate substantially free of nitrogen such as methanol supplied from the substrate supply path 13 to perform secondary denitrification. Is called. The secondary denitrification liquid in the secondary denitrification tank 3 enters the re-aeration tank 4, where the remaining organic matter is decomposed by re-aeration.

このようにして１次脱窒、１次硝化、２次脱窒、再曝気を交互に繰り返すことにより、原水（含窒素有機性排水）に含まれる有機物およびアンモニア性窒素は除去される。従来例えば特許文献１では、再曝気槽４の再曝気液は沈殿槽で沈殿分離し、分離汚泥の一部を第１脱窒槽１ａに返送していたが、分離汚泥の濃度を高めるために、例えば特許文献２では沈澱槽の替わりに、曝気状態で膜分離する膜分離装置を設置し、汚泥と処理水の分離に膜分離を適用するようになり、図２はこのような処理装置を示している。 Thus, by repeating primary denitrification, primary nitrification, secondary denitrification, and re-aeration alternately, organic substances and ammoniacal nitrogen contained in raw water (nitrogen-containing organic waste water) are removed. Conventionally, in Patent Document 1, for example, the re-aeration liquid in the re-aeration tank 4 is precipitated and separated in the precipitation tank, and a part of the separated sludge is returned to the first denitrification tank 1a, but in order to increase the concentration of the separated sludge, For example, in Patent Document 2, instead of a precipitation tank, a membrane separation device that separates membranes in an aerated state is installed, and membrane separation is applied to separation of sludge and treated water. FIG. 2 shows such a treatment device. ing.

すなわち図２において、再曝気槽４の再曝気液は膜分離槽５に導入され、給気路１４から散気装置７ｆに空気を供給して、２次脱窒液の再曝気液を曝気した状態で、膜モジュール８により膜分離を行う。膜モジュール８では、汚泥を含む再曝気液は分離膜８ａにより膜分離され、分離膜８ａを透過した透過液は透過液室８ｃから、処理水としてポンプＰ１により処理水路１５を通して取り出される。濃縮液室８ｂの濃縮液は散気装置７ｆによる曝気により分離膜８ａへの付着が防止されて膜分離槽５内に分散する。膜分離槽５の濃縮液はポンプピット６に入り、その一部は返送汚泥としてからポンプＰ３により、第１の返送路１７を通して１次脱窒槽１の第１脱窒槽１ａに返送され、他の一部は余剰汚泥としてポンプＰ４により余剰汚泥路１８を通して系外に排出される。 That is, in FIG. 2, the re-aeration liquid in the re-aeration tank 4 is introduced into the membrane separation tank 5, and air is supplied from the air supply path 14 to the air diffuser 7f to aerate the re-aeration liquid of the secondary denitrification liquid. In the state, membrane separation is performed by the membrane module 8. In the membrane module 8, the re-aerated liquid containing sludge is membrane-separated by the separation membrane 8a, and the permeate that has permeated through the separation membrane 8a is taken out from the permeate chamber 8c through the treatment water channel 15 as treatment water by the pump P1. The concentrated liquid in the concentrated liquid chamber 8b is dispersed in the membrane separation tank 5 while being prevented from adhering to the separation membrane 8a by aeration by the air diffuser 7f. The concentrated liquid in the membrane separation tank 5 enters the pump pit 6, and a part of the concentrated liquid is returned to the first denitrification tank 1 a of the primary denitrification tank 1 through the first return path 17 by the pump P 3 and returned to the other. A part is discharged out of the system through the excess sludge passage 18 by the pump P4 as excess sludge.

上記のような処理において、２次脱窒槽３でほぼ完全に窒素除去されていても、処理水（分離膜８ａの透過液）中に窒素が検出される場合がある。例えば固液分離槽として沈澱槽を用いる場合には、固液分離条件の選択により処理水（分離液）のＴ−Ｎを低くすることができるが、膜分離槽５を用いる場合には、処理水のＴ−Ｎを低くすることが困難であり、処理水のＴ−Ｎを安定して例えば１０ｍｇ／Ｌ以下に維持するのは困難である。その原因を調べたところ、膜分離槽５で曝気を行うことにより、汚泥中の有機窒素化合物の分解または代謝等により窒素成分が濃縮液中に溶出し、これがＮＯ_X−Ｎに硝化されて処理水に混入するものと推定された。 In the treatment as described above, even if nitrogen is almost completely removed in the secondary denitrification tank 3, nitrogen may be detected in the treated water (permeated liquid of the separation membrane 8a). For example, when a precipitation tank is used as the solid-liquid separation tank, the TN of the treated water (separated liquid) can be lowered by selecting the solid-liquid separation conditions, but when the membrane separation tank 5 is used, It is difficult to lower the TN of water, and it is difficult to stably maintain the TN of treated water at, for example, 10 mg / L or less. When the cause was investigated, by aeration in the membrane separation tank 5, the nitrogen component was eluted in the concentrate by decomposition or metabolism of organic nitrogen compounds in the sludge, and this was nitrified to NO _x -N and treated. Presumed to be mixed in water.

上記の処理水のＴ−Ｎの上昇を防止するために、硝化槽の酸素供給量を増加させることにより、少しでも分解を進めることはできるが、酸素供給量を増すと発泡等の障害があり、十分な効果を得ることができない。また返送汚泥量を増加させることにより、膜分離槽のＭＬＳＳを低下させたり、汚泥の膜分離槽での滞留時間を短くして、ＮＯ_X−Ｎの発生を少なくすることもできるが、膜分離槽から余剰汚泥を引き抜いて脱水する際、汚泥濃度が低くなることは脱水効果を悪化させることになる。 In order to prevent the increase in the TN of the treated water, the decomposition can be advanced as much as possible by increasing the amount of oxygen supplied to the nitrification tank. However, if the amount of oxygen supplied is increased, there are obstacles such as foaming. Can't get enough effect. In addition, by increasing the amount of returned sludge, the MLSS of the membrane separation tank can be reduced, or the residence time of the sludge in the membrane separation tank can be shortened to reduce the generation of NO _x -N. When the excess sludge is extracted from the tank and dehydrated, the decrease in the sludge concentration deteriorates the dehydration effect.

特許文献１では、無希釈のし尿を１次脱窒および硝化した後、水で希釈して２次脱窒を行うので、２次脱窒および再曝気に必要な汚泥濃度とするために、沈澱槽の分離汚泥の一部を２次脱窒槽に返送しているが、ここでは沈殿分離であるため、汚泥中の有機窒素化合物の分解または代謝等により処理水のＴ−Ｎが増加するかどうかは不明であり、分離汚泥の一部を２次脱窒槽に返送することによって処理水のＴ−Ｎが低くなるかどうかも明らかにされていない。
特公平１−１６５５９号公報特開平１１−２８４６８号公報 In Patent Document 1, since non-diluted human waste is subjected to primary denitrification and nitrification, and then diluted with water to perform secondary denitrification, in order to obtain a sludge concentration necessary for secondary denitrification and re-aeration, precipitation is performed. Part of the separated sludge in the tank is returned to the secondary denitrification tank, but here it is precipitation separation, so whether TN of treated water increases due to decomposition or metabolism of organic nitrogen compounds in the sludge It is unclear, and it has not been clarified whether TN of treated water is lowered by returning a part of the separated sludge to the secondary denitrification tank.
Japanese Patent Publication No. 1-16559 JP-A-11-28468

本発明の課題は、汚泥と処理水の分離に曝気状態での膜分離を適用する硝化脱窒処理において、硝化槽での発泡や脱水効果の悪化などを招くことなく、簡単な構成と操作で処理水中の窒素濃度を低くして、良好な処理水を得ることができる含窒素有機性排水の処理方法および装置を提供することである。 The subject of the present invention is a simple configuration and operation without causing foaming in the nitrification tank or deterioration of the dehydration effect in nitrification denitrification treatment in which membrane separation in an aerated state is applied to separation of sludge and treated water. It is intended to provide a method and apparatus for treating nitrogen-containing organic waste water that can reduce the nitrogen concentration in treated water and obtain good treated water.

本発明は次の含窒素有機性排水の処理方法および装置である。
（１）含窒素有機性排水を硝化液と混合して生物脱窒するとともに有機物を分解する１次脱窒工程と、
１次脱窒液を生物硝化する１次硝化工程と、
１次硝化液を実質的に窒素を含まない基質と混合して生物脱窒する２次脱窒工程と、
２次脱窒液を再曝気する再曝気工程と、
再曝気液を曝気状態で膜分離する膜分離工程と、
膜分離工程の濃縮液の一部を１次脱窒工程に返送する第１の返送工程と、
膜分離工程の濃縮液の他の一部を２次脱窒工程に返送する第２の返送工程と
を含み、
１次脱窒工程および１次硝化工程はそれぞれ交互に複数段階を行うステップ脱窒、硝化工程である含窒素有機性排水の処理方法（ただし、２次脱窒工程において、窒素有機性排水を混合する方法を除く。）。
（２）含窒素有機性排水を硝化液と混合して生物脱窒するとともに有機物を分解する１次脱窒槽と、
１次脱窒液を生物硝化する１次硝化槽と、
１次硝化液を実質的に窒素を含まない基質と混合して生物脱窒する２次脱窒槽と、
２次脱窒液を再曝気する再曝気槽と、
再曝気液を曝気状態で膜分離する膜分離槽と、
膜分離槽の濃縮液の一部を１次脱窒槽に返送する第１の返送路と、
膜分離槽の濃縮液の他の一部を２次脱窒槽に返送する第２の返送路と
を含み、
１次脱窒槽および１次硝化槽はそれぞれ交互に複数段階を行うステップ脱窒槽および硝化槽である含窒素有機性排水の処理装置（ただし、２次脱窒槽において、窒素有機性排水を混合する装置を除く。）。 The present invention is the following nitrogen-containing organic wastewater treatment method and apparatus.
(1) A primary denitrification step in which nitrogen-containing organic wastewater is mixed with nitrification liquid to biologically denitrify and decompose organic matter;
A primary nitrification step of bionitrating the primary denitrification solution;
A secondary denitrification step in which the primary nitrification solution is mixed with a substrate substantially free of nitrogen to biodenitrify;
A re-aeration process for re-aeration of the secondary denitrification liquid;
A membrane separation step of separating the re-aerated liquid in an aerated state;
A first return step for returning a part of the concentrate of the membrane separation step to the primary denitrification step;
A second returning step of returning the other part of the concentrate of the membrane separation process in the secondary denitrification step seen including,
The primary denitrification process and the primary nitrification process are performed in multiple steps alternately. Nitrogen-containing organic wastewater treatment method, which is a nitrification process (However, in the secondary denitrification process, nitrogen organic wastewater is mixed. Except how to do that.)
(2) A primary denitrification tank that mixes nitrogen-containing organic wastewater with nitrification liquid to biologically denitrify and decompose organic matter;
A primary nitrification tank for bionitrating the primary denitrification liquid;
A secondary denitrification tank for biological denitrification by mixing the primary nitrification solution with a substrate substantially free of nitrogen,
A re-aeration tank for re-aeration of the secondary denitrification liquid;
A membrane separation tank for separating a re-aerated liquid in an aerated state;
A first return path for returning a part of the concentrate in the membrane separation tank to the primary denitrification tank;
A second return path for returning a portion of the other of the concentrate of the membrane separation tank to the secondary denitrification seen including,
The primary denitrification tank and the primary nitrification tank are a step denitrification tank and a nitrification tank, each of which comprises a plurality of stages. A treatment apparatus for nitrogen-containing organic wastewater (however, a device for mixing nitrogen organic wastewater in the secondary denitrification tank) except for.).

本発明の処理対象となる含窒素有機性排水は、窒素および有機物を含む排水であり、他の元素および無機物を含んでいてもよい。窒素としてはアンモニア性窒素、硝酸または亜硝酸性窒素、有機性窒素などがあるが、通常の含窒素有機性排水はアンモニア性窒素および有機性窒素を含むものが多い。このような含窒素有機性排水には、下水、産業排水、食品排水、し尿などがあげられる。 The nitrogen-containing organic waste water to be treated in the present invention is waste water containing nitrogen and organic matter, and may contain other elements and inorganic matter. Nitrogen includes ammonia nitrogen, nitric acid or nitrite nitrogen, organic nitrogen, etc., and most nitrogen-containing organic wastewater contains ammonia nitrogen and organic nitrogen. Such nitrogen-containing organic wastewater includes sewage, industrial wastewater, food wastewater, human waste and the like.

本発明の含窒素有機性排水の処理方法では、１次脱窒工程において含窒素有機性排水を硝化液と混合して生物脱窒するとともに有機物を分解し、１次硝化工程において１次脱窒液を生物硝化し、２次脱窒工程において含窒素有機性排水を混合することなく、１次硝化液を実質的に窒素を含まない基質と混合して生物脱窒し、膜分離工程において２次脱窒液を曝気状態で膜分離し、第１の返送工程において膜分離工程の濃縮液の一部を１次脱窒工程に返送し、第２の返送工程において膜分離工程の濃縮液の他の一部を２次脱窒工程に返送して、含窒素有機性排水を処理する。曝気により発泡が起る場合は、予め被処理水を希釈して処理を行い、途中では希釈を行なわずに処理するのが好ましい。 In the method for treating nitrogen-containing organic waste water according to the present invention, the nitrogen-containing organic waste water is mixed with a nitrification liquid in the primary denitrification step to biologically denitrify and decompose organic matter, and in the primary nitrification step, the primary denitrification step is performed. The liquid is biologically nitrified without mixing nitrogen-containing organic wastewater in the secondary denitrification process, and the primary nitrification liquid is mixed with a substrate that does not substantially contain nitrogen for biological denitrification. The secondary denitrification liquid is subjected to membrane separation in the aerated state, a part of the concentrated liquid in the membrane separation process is returned to the primary denitrification process in the first return process, and the concentrated liquid in the membrane separation process is returned in the second return process. The other part is returned to the secondary denitrification process to treat nitrogen-containing organic wastewater. In the case where foaming occurs due to aeration, it is preferable to dilute the water to be treated in advance and perform the treatment without diluting in the middle.

１次脱窒工程および１次硝化工程はそれぞれの工程を交互に複数段階行うステップ脱窒およびステップ硝化工程を採用することにより、効率よく窒素および有機物を含む排水を処理できるので好ましい。この場合、原水（含窒素有機性排水）を各段階の１次脱窒工程に分注して脱窒を行い、脱窒液は次段の１次硝化工程に送って硝化し、硝化液は次段の１次脱窒工程に送り、最終階の硝化液は第１段の１次脱窒工程に循環するように構成するのが好ましい。２次脱窒工程と膜分離工程間に再曝気工程を設け、２次脱窒液を再曝気する。膜分離工程では、再曝気液を曝気状態に維持して膜分離する。膜分離工程の濃縮液は、第１の返送工程において一部を１次脱窒工程に返送し、第２の返送工程において他の一部を２次脱窒工程に返送するが、さらに他の一部を余剰汚泥として系外に排出することができる。 By employing a plurality of steps performed steps denitrification and step nitrification step alternating primary denitrification step and the primary nitrification step Waso respectively process, it is possible to process the waste water containing efficiently nitrogen and organic preferred. In this case, raw water (nitrogen-containing organic wastewater) is dispensed into the primary denitrification process at each stage to perform denitrification, and the denitrification liquid is sent to the primary nitrification process at the next stage for nitrification. It is preferable that the nitrification liquid on the final floor is sent to the primary denitrification process at the next stage and circulated to the primary denitrification process at the first stage. A re-aeration process is provided between the secondary denitrification process and the membrane separation process to re-aerate the secondary denitrification liquid. In the membrane separation step, the re-aerated liquid is maintained in the aerated state to perform membrane separation . The concentrated liquid in the membrane separation process is partially returned to the primary denitrification process in the first return process, and the other part is returned to the secondary denitrification process in the second return process. Part of it can be discharged out of the system as excess sludge.

上記の含窒素有機性排水の処理方法に用いるための処理装置は、含窒素有機性排水を硝化液と混合して生物脱窒するとともに有機物を分解する１次脱窒槽と、１次脱窒液を生物硝化する１次硝化槽と、１次硝化液を実質的に窒素を含まない基質と混合して生物脱窒する２次脱窒槽と、２次脱窒液を再曝気する再曝気槽と、再曝気液を曝気状態で膜分離する膜分離槽と、膜分離槽の濃縮液の一部を１次脱窒槽に返送する第１の返送路と、膜分離槽の濃縮液の他の一部を２次脱窒槽に返送する第２の返送路とを含む装置が用いられる。 A treatment apparatus for use in the above-described method for treating nitrogen-containing organic wastewater comprises a primary denitrification tank that mixes nitrogen-containing organic wastewater with a nitrification liquid for biological denitrification and decomposes organic matter, and primary denitrification liquid. A primary nitrification tank for biological nitrification, a secondary denitrification tank for biological denitrification by mixing the primary nitrification liquid with a substrate substantially free of nitrogen, and a re-aeration tank for re-aeration of the secondary denitrification liquid A membrane separation tank for membrane separation of the re-aerated liquid in an aerated state, a first return path for returning a part of the concentrated liquid in the membrane separation tank to the primary denitrification tank, and another concentrated liquid in the membrane separation tank And a second return path for returning the part to the secondary denitrification tank.

上記の処理装置において、１次脱窒槽および１次硝化槽はそれぞれ交互に複数段階を行うステップ脱窒槽および硝化槽の組み合わせとされる。この場合、原水（含窒素有機性排水）を各段階の１次脱窒槽に分注して脱窒を行い、脱窒液は次段の１次硝化槽に送って硝化し、硝化液は次段の１次脱窒槽に送り、最終階の硝化液は第１段の１次脱窒槽に循環するように構成するのが好ましい。また２次脱窒槽と膜分離槽間に、２次脱窒液を再曝気する再曝気槽が設けられる。膜分離槽の濃縮液（返送汚泥）を複数槽からなる１次脱窒槽に返送する場合、第１の返送路を先頭の１次脱窒槽に連絡するのが好ましい。 In the above processing apparatus, a primary denitrification tank and the primary nitrification reactor is a combination of the respective steps denitrification tank and nitrification tank to perform multiple steps alternately. In this case, raw water (nitrogen-containing organic waste water) is dispensed into the primary denitrification tank at each stage for denitrification, and the denitrification liquid is sent to the primary nitrification tank at the next stage for nitrification. It is preferable that the nitrification liquid on the final floor is sent to the primary denitrification tank of the stage and is circulated to the primary denitrification tank of the first stage. Also between the secondary denitrification tank and the membrane separation tank, re-aeration tank is provided to re-aeration secondary denitrified liquid. When returning the concentrated liquid (return sludge) of the membrane separation tank to a primary denitrification tank comprising a plurality of tanks, it is preferable to connect the first return path to the first primary denitrification tank.

膜分離槽に用いる分離膜は、通常固液分離に用いられるＭＦ膜、ＵＦ膜等の透過膜が用いられ、分離膜の形態は平膜、チューブラー膜、中空糸膜などがある。このような分離膜は、分離膜により濃縮液室と透過液室とが区画された膜モジュールとして用いるのが好ましい。このような膜モジュールは、設置条件により加圧型、浸漬型のものなどが用いられる。膜分離槽の濃縮液は、膜分離槽から１次脱窒槽および／または２次脱窒槽に返送してもよいが、ポンプピットを設けてポンプピットから返送してもよい。返送手段は専用ポンプ等を用いてもよいし、返送汚泥路または余剰汚泥路から分岐してもよい。余剰汚泥路は膜分離槽またはポンプピットから余剰汚泥を引き抜き、汚泥処理へ送るように設けられる。 As the separation membrane used in the membrane separation tank, a permeable membrane such as an MF membrane or a UF membrane usually used for solid-liquid separation is used. Examples of the separation membrane include a flat membrane, a tubular membrane, and a hollow fiber membrane. Such a separation membrane is preferably used as a membrane module in which the concentrate chamber and the permeate chamber are partitioned by the separation membrane. As such a membrane module, a pressure type, immersion type or the like is used depending on installation conditions. The concentrated liquid in the membrane separation tank may be returned from the membrane separation tank to the primary denitrification tank and / or the secondary denitrification tank. Alternatively, a pump pit may be provided and returned from the pump pit. The return means may use a dedicated pump or the like, or may branch from the return sludge path or the excess sludge path. The surplus sludge path is provided so as to draw surplus sludge from the membrane separation tank or pump pit and send it to the sludge treatment.

本発明の含窒素有機性排水の処理方法では、１次脱窒、１次硝化、２次脱窒、再曝気は従来の硝化脱窒方法と同様に行われる。硝化脱窒方法は標準脱窒素法、高負荷処理方法、浄化槽対応型等の方法が採用できる。再曝気液を曝気状態で膜分離することも、膜分離を採用する従来の硝化脱窒方法と同様であるが、膜分離工程の濃縮液を２次脱窒工程に循環して脱窒することにより、処理水の窒素濃度を低下させることができる。膜分離槽で膜分離することにより濃縮液のＭＬＳＳは高くなるので、濃縮液の一部を返送汚泥として１次脱窒工程へ返送し、残部を余剰汚泥として脱水処理している。 In the nitrogen-containing organic wastewater treatment method of the present invention, primary denitrification, primary nitrification, secondary denitrification, and re-aeration are performed in the same manner as in the conventional nitrification denitrification method. As a nitrification denitrification method, a standard denitrification method, a high load treatment method, a septic tank compatible method, or the like can be adopted . Membrane separation of the re- aerated liquid in the aerated state is the same as the conventional nitrification denitrification method that employs membrane separation, but denitrification is performed by circulating the concentrated liquid from the membrane separation process to the secondary denitrification process. Thus, the nitrogen concentration of the treated water can be reduced. Since the MLSS of the concentrate is increased by performing membrane separation in the membrane separation tank, a part of the concentrate is returned to the primary denitrification step as return sludge, and the remainder is dehydrated as excess sludge.

脱水処理を効率よく行うためには、膜分離工程の濃縮液を高濃度に維持して膜分離を行うのが好ましい。このような高濃度の濃縮液を単に膜分離槽に入れて膜分離すると、嫌気状態になって有機物が溶出して処理水質が悪化し、また汚泥が膜面に付着して膜分離効率が下がるのを防止するために、曝気状態で膜分離することが行われている。一般的には曝気により好気状態に維持すると、有機物が分解され、処理水質が良くなると考えられている。 In order to efficiently perform the dehydration treatment, it is preferable to perform the membrane separation while maintaining the concentrated liquid in the membrane separation step at a high concentration. If such a concentrated solution is simply put in a membrane separation tank and separated into membranes, it becomes anaerobic and organic substances are eluted, the quality of treated water deteriorates, and sludge adheres to the membrane surface and membrane separation efficiency decreases. In order to prevent this, membrane separation is performed in an aerated state. In general, it is considered that maintaining an aerobic state by aeration will decompose organic substances and improve the quality of treated water.

ところが汚泥濃度が高い状態、例えばＭＬＳＳとして１０,０００〜２０,０００ｍｇ／Ｌの状態で濃縮液の曝気を継続すると、汚泥中に含まれる有機窒素化合物の分解または代謝等により窒素成分が濃縮液中に溶出し、これが硝酸または亜硝酸性窒素に硝化されるものと推定され、２次脱窒工程でほぼ完全に窒素除去されていても、濃縮液中に窒素が検出され、この窒素成分が処理水（分離膜の透過液）に混入し、処理水質を悪化させる場合がある。 However, if the aeration of the concentrated liquid is continued in a state where the sludge concentration is high, for example, 10,000 to 20,000 mg / L as MLSS, nitrogen components are contained in the concentrated liquid due to decomposition or metabolism of organic nitrogen compounds contained in the sludge. It is estimated that it will be nitrified to nitric acid or nitrite nitrogen, and even if nitrogen is almost completely removed in the secondary denitrification process, nitrogen is detected in the concentrate and this nitrogen component is treated. It may be mixed with water (permeated liquid of the separation membrane) to deteriorate the quality of treated water.

都合のよいことに濃縮液中の窒素は曝気により硝酸または亜硝酸性窒素になっているので、濃縮液の一部を２次脱窒工程に循環することにより脱窒することができ、窒素濃度の低い再曝気液を膜分離工程に循環して、濃縮液中の窒素濃度を低くすることができる。これにより脱水処理を効率よく行うために、膜分離工程の濃縮液を高濃度に維持して膜分離を行っても、濃縮液中の窒素濃度を低く維持して、処理水の窒素濃度を低くすることができる。 Conveniently, the nitrogen in the concentrate is converted to nitric acid or nitrite nitrogen by aeration, so that a part of the concentrate can be denitrified by circulating it in the secondary denitrification process, and the nitrogen concentration of not lower reaerated liquid circulated to the membrane separation process, it is possible to reduce the nitrogen concentration in the concentrate. Thus, in order to efficiently perform the dehydration treatment, even if the membrane separation is carried out while maintaining the concentrated liquid in the membrane separation step at a high concentration, the nitrogen concentration in the concentrated liquid is kept low and the nitrogen concentration in the treated water is lowered. can do.

このため硝化槽の酸素供給量を増加させたり、膜分離槽のＭＬＳＳを低下させたりする必要はなく、硝化槽での発泡や脱水効果の悪化などを招くことはない。２次脱窒工程への濃縮液の返送率は、膜分離槽の濃縮液の窒素濃度により変化させることができる。この場合、濃縮液（処理水）の窒素濃度を例えば３〜７ｍｇ／Ｌを維持するように濃縮液の返送率を選ぶと、上記窒素濃度の処理水を得ることができる。濃縮液の脱窒に必要なメタノール等の実質的に窒素を含まない基質は、２次脱窒工程へ供給される基質の量を増加することにより対応することができる。濃縮液の返送を行う２次脱窒工程あるいはその前後の工程において水による希釈を行う必要はない。 For this reason, it is not necessary to increase the oxygen supply amount of the nitrification tank or to lower the MLSS of the membrane separation tank, and neither the foaming in the nitrification tank nor the dehydration effect is deteriorated. The return rate of the concentrate to the secondary denitrification step can be changed depending on the nitrogen concentration of the concentrate in the membrane separation tank. In this case, if the return rate of the concentrate is selected so that the nitrogen concentration of the concentrate (treated water) is maintained at, for example, 3 to 7 mg / L, the treated water having the nitrogen concentration can be obtained. Substrate substantially free of nitrogen, such as methanol, required for denitrification of the concentrate can be accommodated by increasing the amount of substrate supplied to the secondary denitrification step. There is no need to dilute with water in the secondary denitrification step in which the concentrate is returned or in the steps before and after.

本発明によれば、１次脱窒工程および１次硝化工程として、それぞれ交互に複数段階を行うステップ脱窒、硝化工程を採用し、１次脱窒工程で含窒素有機性排水を硝化液と混合して生物脱窒するとともに有機物を分解し、１次硝化工程で１次脱窒液を生物硝化し、２次脱窒工程で１次硝化液を含窒素有機性排水と混合することなく、実質的に窒素を含まない基質と混合して生物脱窒し、再曝気工程で２次脱窒液を再曝気し、膜分離工程で再曝気液を曝気状態で膜分離し、第１の返送工程において膜分離工程の濃縮液の一部を１次脱窒工程に返送し、第２の返送工程において膜分離工程の濃縮液の他の一部を２次脱窒工程に返送して脱窒するようにしたので、汚泥と処理水の分離に曝気状態での膜分離を適用する硝化脱窒処理においても、硝化槽での発泡や脱水効果の悪化などを招くことなく、簡単な構成と操作で処理水中の窒素濃度を低くして、良好な処理水を得ることができる。 According to the present invention, as the primary denitrification process and the primary nitrification process, step denitrification and nitrification processes that alternately perform a plurality of stages are adopted, and the nitrogen-containing organic waste water is used as the nitrification liquid in the primary denitrification process. Without mixing and biological denitrification, organic matter is decomposed, the primary denitrification liquid is bionitrated in the primary nitrification process, and the primary nitrification liquid is not mixed with nitrogen-containing organic wastewater in the secondary denitrification process. Biological denitrification by mixing with a substrate substantially free of nitrogen, re-aeration of the secondary denitrification liquid in the re-aeration process , membrane separation of the re-aeration liquid in the aerated state in the membrane separation process, and first return In the process, a part of the concentrated liquid in the membrane separation process is returned to the primary denitrification process, and in the second return process, another part of the concentrated liquid in the membrane separation process is returned to the secondary denitrification process. Therefore, even in nitrification denitrification treatment that applies membrane separation in the aerated state for separation of sludge and treated water, Without causing such foaming or the dewatering effect deterioration of a bath, by lowering the nitrogen concentration in the treated water with a simple structure and operation, it is possible to obtain satisfactory treated water.

以下、本発明の実施形態を図面により説明する。図１は本発明の実施形態による含窒素有機性排水の処理方法および装置を示すフロー図である。図１の処理装置１０は図２の処理装置１０とほぼ同様に構成されているので、同一または相当部分に同一符号を付して説明を省略する。図１の処理装置１０が図２の処理装置１０と相違するところは、ポンプＰ５を有する第２の返送路２１が膜分離槽５の下部から２次脱窒槽３に連絡しているところである。 Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a flowchart showing a method and apparatus for treating nitrogen-containing organic wastewater according to an embodiment of the present invention. Since the processing apparatus 10 in FIG. 1 is configured in substantially the same manner as the processing apparatus 10 in FIG. 2, the same or corresponding parts are denoted by the same reference numerals and description thereof is omitted. The processing apparatus 10 in FIG. 1 differs from the processing apparatus 10 in FIG. 2 in that a second return path 21 having a pump P5 communicates with the secondary denitrification tank 3 from the lower part of the membrane separation tank 5.

図１の処理装置１０による含窒素有機性排水の処理方法は、図２の処理装置１０による含窒素有機性排水の処理方法とほぼ同様に行われる。すなわち１次脱窒槽１における１次脱窒、１次硝化槽２における１次硝化、２次脱窒槽３における２次脱窒、再曝気槽４における再曝気、膜分離槽５における膜分離、硝化液循環路１６からの硝化液の循環、第１の返送路１７からの一部の濃縮液の返送、余剰汚泥路１８からの余剰汚泥の排出などは図２とほぼ同様に行われる。 The processing method of nitrogen-containing organic waste water by the processing apparatus 10 of FIG. 1 is performed in substantially the same manner as the processing method of nitrogen-containing organic waste water by the processing apparatus 10 of FIG. That is, primary denitrification in the primary denitrification tank 1, primary nitrification in the primary nitrification tank 2, secondary denitrification in the secondary denitrification tank 3, re-aeration in the re-aeration tank 4, membrane separation in the membrane separation tank 5, and nitrification The circulation of the nitrification liquid from the liquid circulation path 16, the return of a part of the concentrated liquid from the first return path 17, the discharge of the excess sludge from the excess sludge path 18, and the like are performed in substantially the same manner as in FIG.

図１の処理装置１０による含窒素有機性排水の処理方法では、膜分離槽５内の膜分離工程の濃縮液の他の一部を第２の返送路２１から、２次脱窒槽３における２次脱窒工程に返送して脱窒することにより、処理水の窒素濃度を低下させることができる。膜分離工程は膜分離槽５内の濃縮液を高濃度に維持して膜分離を行うが、このような高濃度の濃縮液を曝気状態で膜分離すると、前述のように汚泥中に含まれる有機窒素化合物の分解または代謝等により窒素成分が濃縮液中に溶出し、これが硝酸または亜硝酸性窒素に硝化されるものと推定され、濃縮液中の窒素濃度が高くなる。 In the processing method of nitrogen-containing organic wastewater by the processing apparatus 10 of FIG. 1, another part of the concentrated liquid in the membrane separation process in the membrane separation tank 5 is transferred from the second return path 21 to 2 in the secondary denitrification tank 3. By returning to the next denitrification step and performing denitrification, the nitrogen concentration of the treated water can be lowered. In the membrane separation process, the concentrated solution in the membrane separation tank 5 is maintained at a high concentration to perform membrane separation. When such a concentrated solution is separated into a membrane in an aerated state, it is contained in sludge as described above. It is presumed that the nitrogen component is eluted into the concentrate by decomposition or metabolism of the organic nitrogen compound, and this is presumed to be nitrified into nitric acid or nitrite nitrogen, and the nitrogen concentration in the concentrate increases.

濃縮液中の窒素は曝気により硝酸または亜硝酸性窒素になっているので、濃縮液の一部を２次脱窒槽３に返送すると、１次脱窒槽１の第４硝化槽２ｄから流入する１次硝化液とともに生物脱窒により脱窒することができる。ここで必要なメタノール等の実質的に窒素を含まない基質は、基質供給路１３から供給される基質の量を増加することにより対応することができる。このように返送する濃縮液を脱窒することにより、窒素濃度の低い脱窒液を再曝気槽４で再曝気し、窒素濃度の低い再曝気液を膜分離槽５に循環して、濃縮液中の窒素濃度を低く維持することができる。このため膜分離槽５の濃縮液のＭＬＳＳを高濃度に維持して膜分離を行っても、濃縮液中の窒素濃度を低く維持して、処理水の窒素濃度を低くすることができる。 Since nitrogen in the concentrate is converted to nitric acid or nitrite nitrogen by aeration, when a part of the concentrate is returned to the secondary denitrification tank 3, it flows from the fourth nitrification tank 2d of the primary denitrification tank 1 It can be denitrified by biological denitrification along with the next nitrification solution. The substrate substantially free of nitrogen such as methanol required here can be dealt with by increasing the amount of substrate supplied from the substrate supply path 13. By denitrifying the concentrated liquid to be returned in this way, the denitrified liquid having a low nitrogen concentration is re-aerated in the re-aeration tank 4, and the re-aerated liquid having a low nitrogen concentration is circulated to the membrane separation tank 5. The nitrogen concentration inside can be kept low. For this reason, even if MLSS of the concentrate of the membrane separation tank 5 is maintained at a high concentration and membrane separation is performed, the nitrogen concentration in the concentrate can be kept low and the nitrogen concentration of the treated water can be lowered.

上記の処理では、１次硝化槽２、再曝気槽４、膜分離槽５などにおける酸素供給量を増加させる必要はないので、発泡障害、その他の悪影響を硝化脱窒処理に及ぼすことがない。また膜分離槽５のＭＬＳＳを低下させる必要はないので、脱水効果の悪化などを招くこともない。このため簡単な構成と操作により処理水中の窒素濃度を低くして、良好な処理水を得ることができる。 In the above-described treatment, it is not necessary to increase the oxygen supply amount in the primary nitrification tank 2, the re-aeration tank 4, the membrane separation tank 5, and the like, so that foaming failure and other adverse effects are not exerted on the nitrification denitrification treatment. Moreover, since it is not necessary to lower MLSS of the membrane separation tank 5, the dehydration effect is not deteriorated. For this reason, the nitrogen concentration in the treated water can be lowered by a simple configuration and operation, and good treated water can be obtained.

図１において、膜分離槽５と再曝気槽４で異なる条件で曝気を行うために、膜分離槽５とは別に再曝気槽４を設けて曝気を行う。またポンプピット６も省略することができるが、濃縮液の返送による膜分離槽５の液面の変動を防止するためにはポンプピット６を設けて濃縮液の返送を行うのが好ましい。この場合、ポンプピット６から濃縮液の一部を２次脱窒槽３に循環することができ、第１の返送路１７から分岐路（図示省略）を通して濃縮液の一部を２次脱窒槽３に循環してもよい。 In Figure 1, in order to perform aeration at different conditions re aeration tank 4 and the membrane separation tank 5, it intends rows aeration re aeration tank 4 is provided separately from the membrane separation tank 5. Although the pump pit 6 can be omitted, it is preferable to provide the pump pit 6 to return the concentrated liquid in order to prevent fluctuations in the liquid level of the membrane separation tank 5 due to the return of the concentrated liquid. In this case, a part of the concentrated liquid can be circulated from the pump pit 6 to the secondary denitrification tank 3, and a part of the concentrated liquid is passed from the first return path 17 through the branch path (not shown). It may be circulated.

比較例１：
図２の処理装置１０において、含窒素有機性排水として、生し尿を希釈水により１．３倍希釈した希釈し尿（ＢＯＤ５１００ｍｇ／Ｌ、ＮＨ₄−Ｎ：５３０ｍｇ／Ｌ、ＮＯ_X−Ｎ：０ｍｇ／Ｌ、Ｔ−Ｎ：１０００ｍｇ／Ｌ）を原水とし、原水量１００ＫＬ／Ｄで供給して生物硝化脱窒素処理を行い、膜モジュール８として平膜型浸漬モジュールを用いて、膜分離処理を行い、膜分離槽５の濃縮液を２次脱窒槽３に返送しないで処理を行った。１次硝化液の循環量は３６０ｍ³／日、第１脱窒槽への返送汚泥量は２７０ｍ³／日であった。 Comparative Example 1:
In the treatment apparatus 10 of FIG. 2, diluted urine obtained by diluting raw urine 1.3 times with diluted water (BOD 5100 mg / L, NH ₄ -N: 530 mg / L, NO _x -N: 0 mg / as nitrogen-containing organic waste water). L, TN: 1000 mg / L) is used as raw water, the raw water is supplied at 100 KL / D to perform biological nitrification denitrification, and membrane membrane 8 is subjected to membrane separation using a flat membrane immersion module. The treatment was performed without returning the concentrated liquid in the membrane separation tank 5 to the secondary denitrification tank 3. The circulation rate of the primary nitrification liquid was 360 m ³ / day, and the amount of sludge returned to the first denitrification tank was 270 m ³ / day.

実施例１：
図１の処理装置１０において、比較例１と同様に生物硝化脱窒素処理および膜分離処理を行い、１次硝化液の循環量は３６０ｍ³／日、第１脱窒槽への濃縮液の返送量は９７ｍ³／日とし、膜分離槽５の濃縮液の２次脱窒槽３への濃縮液の返送量は４８０ｍ³／Ｄとした。 Example 1:
1, the biological nitrification denitrification process and the membrane separation process are performed in the same manner as in Comparative Example 1, and the circulation rate of the primary nitrification liquid is 360 m ³ / day, and the return amount of the concentrated liquid to the first denitrification tank Was 97 m ³ / day, and the amount of the concentrated liquid returned to the secondary denitrification tank ³ was 480 m ³ / D.

比較例１および実施例１の各工程の水質を表１に示す。表１の結果から、膜分離槽５の濃縮液の一部を２次脱窒槽３に返送して処理を行うことにより、全窒素濃度の低い高水質の処理水が得られることが分かる。

Table 1 shows the water quality of each step of Comparative Example 1 and Example 1. From the results shown in Table 1, it can be seen that high-quality treated water having a low total nitrogen concentration can be obtained by returning a part of the concentrated liquid in the membrane separation tank 5 to the secondary denitrification tank 3 for treatment.

し尿等の含窒素有機性排水を好気的に処理し、有機物を除去するとともに硝化脱窒を行う処理方法および装置に利用される。 Nitrogen-containing organic wastewater such as human waste is aerobically treated to remove organic substances and to be used in a treatment method and apparatus for performing nitrification denitrification.

本発明の実施形態による含窒素有機性排水の処理方法および装置を示すフロー図である。It is a flowchart which shows the processing method and apparatus of the nitrogen-containing organic waste_water | drain by embodiment of this invention. 従来の含窒素有機性排水の処理方法および装置を示すフロー図である。It is a flowchart which shows the processing method and apparatus of the conventional nitrogen-containing organic waste_water | drain.

符号の説明Explanation of symbols

１１次脱窒槽
１ａ第１脱窒槽
１ｂ第２脱窒槽
１ｃ第３脱窒槽
１ｄ第４脱窒槽
２１次硝化槽
２ａ第１硝化槽
２ｂ第２硝化槽
２ｃ第３硝化槽
２ｄ第４硝化槽
３２次脱窒槽
４再曝気槽
５膜分離槽
６ポンプピット
７ａ、７ｂ・・・散気装置
８膜モジュール
８ａ分離膜
８ｂ濃縮液室
８ｃ透過液室
１０処理装置
１１原水路
１１ａ、１１ｂ、１１ｃ、１１ｄ分岐路
１２、１４給気路
１２ａ、１２ｂ、１２ｃ、１２ｄ、１２ｅ分岐路
１３基質供給路
１５処理水路
１６硝化液循環路
１７第１の返送路
１８余剰汚泥路
２１第２の返送路
Ｐ１、Ｐ２・・・ポンプ DESCRIPTION OF SYMBOLS 1 Primary denitrification tank 1a 1st denitrification tank 1b 2nd denitrification tank 1c 3rd denitrification tank 1d 4th denitrification tank 2 Primary nitrification tank 2a 1st nitrification tank 2b 2nd nitrification tank 2c 3rd nitrification tank 2d 4th nitrification tank 3 Secondary denitrification tank 4 Re-aeration tank 5 Membrane separation tank 6 Pump pit 7a, 7b ... Aeration device 8 Membrane module 8a Separation membrane 8b Concentrated liquid chamber 8c Permeate chamber 10 Treatment device 11 Raw water channels 11a, 11b, 11c 11d Branch path 12, 14 Air supply path 12a, 12b, 12c, 12d, 12e Branch path 13 Substrate supply path 15 Treatment water path 16 Nitrification liquid circulation path 17 First return path 18 Surplus sludge path 21 Second return path P1 , P2 ... Pump

Claims

含窒素有機性排水を硝化液と混合して生物脱窒するとともに有機物を分解する１次脱窒工程と、
１次脱窒液を生物硝化する１次硝化工程と、
１次硝化液を実質的に窒素を含まない基質と混合して生物脱窒する２次脱窒工程と、
２次脱窒液を再曝気する再曝気工程と、
再曝気液を曝気状態で膜分離する膜分離工程と、
膜分離工程の濃縮液の一部を１次脱窒工程に返送する第１の返送工程と、
膜分離工程の濃縮液の他の一部を２次脱窒工程に返送する第２の返送工程と
を含み、
１次脱窒工程および１次硝化工程はそれぞれ交互に複数段階を行うステップ脱窒、硝化工程である含窒素有機性排水の処理方法（ただし、２次脱窒工程において、窒素有機性排水を混合する方法を除く。）。 A primary denitrification step in which nitrogen-containing organic wastewater is mixed with a nitrification solution to biologically denitrify and decompose organic matter;
A primary nitrification step of bionitrating the primary denitrification solution;
A secondary denitrification step in which the primary nitrification solution is mixed with a substrate substantially free of nitrogen to biodenitrify;
A re-aeration process for re-aeration of the secondary denitrification liquid;
A membrane separation step of separating the re-aerated liquid in an aerated state;
A first return step for returning a part of the concentrate of the membrane separation step to the primary denitrification step;
A second returning step of returning the other part of the concentrate of the membrane separation process in the secondary denitrification step seen including,
The primary denitrification process and the primary nitrification process are performed in multiple steps alternately. Nitrogen-containing organic wastewater treatment method, which is a nitrification process (However, in the secondary denitrification process, nitrogen organic wastewater is mixed. Except how to do that.)

含窒素有機性排水を硝化液と混合して生物脱窒するとともに有機物を分解する１次脱窒槽と、
１次脱窒液を生物硝化する１次硝化槽と、
１次硝化液を実質的に窒素を含まない基質と混合して生物脱窒する２次脱窒槽と、
２次脱窒液を再曝気する再曝気槽と、
再曝気液を曝気状態で膜分離する膜分離槽と、
膜分離槽の濃縮液の一部を１次脱窒槽に返送する第１の返送路と、
膜分離槽の濃縮液の他の一部を２次脱窒槽に返送する第２の返送路と
を含み、
１次脱窒槽および１次硝化槽はそれぞれ交互に複数段階を行うステップ脱窒槽および硝化槽である窒素有機性排水の処理装置（ただし、２次脱窒槽において、窒素有機性排水を混合する装置を除く。）。 A primary denitrification tank that mixes nitrogen-containing organic wastewater with a nitrification solution for biological denitrification and decomposes organic matter;
A primary nitrification tank for bionitrating the primary denitrification liquid;
A secondary denitrification tank for biological denitrification by mixing the primary nitrification solution with a substrate substantially free of nitrogen,
A re-aeration tank for re-aeration of the secondary denitrification liquid;
A membrane separation tank for separating a re-aerated liquid in an aerated state;
A first return path for returning a part of the concentrate in the membrane separation tank to the primary denitrification tank;
A second return path for returning a portion of the other of the concentrate of the membrane separation tank to the secondary denitrification seen including,
The primary denitrification tank and the primary nitrification tank are stepped denitrification tanks and nitrification tanks that are alternately operated in multiple stages. A nitrogen organic wastewater treatment device (however, in the secondary denitrification tank, a device that mixes nitrogen organic wastewater is used. except.).