JP2020054984A - Treatment method and treatment apparatus for organic wasterwater or sludge - Google Patents
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- ILLRQJVNDWDWBA-UHFFFAOYSA-K dimagnesium;phosphate Chemical compound [Mg+2].[Mg+2].[O-]P([O-])([O-])=O ILLRQJVNDWDWBA-UHFFFAOYSA-K 0.000 claims 1
- 238000011084 recovery Methods 0.000 abstract description 39
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- 238000004062 sedimentation Methods 0.000 description 11
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 10
- 239000007787 solid Substances 0.000 description 10
- 208000005156 Dehydration Diseases 0.000 description 9
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- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 description 6
- 239000000701 coagulant Substances 0.000 description 6
- 238000012545 processing Methods 0.000 description 6
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 5
- 238000000354 decomposition reaction Methods 0.000 description 5
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- 239000003002 pH adjusting agent Substances 0.000 description 5
- 229940085991 phosphate ion Drugs 0.000 description 5
- 239000000758 substrate Substances 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 239000011575 calcium Substances 0.000 description 4
- 238000007796 conventional method Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
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- 239000001506 calcium phosphate Substances 0.000 description 3
- 229910000389 calcium phosphate Inorganic materials 0.000 description 3
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- QORWJWZARLRLPR-UHFFFAOYSA-H tricalcium bis(phosphate) Chemical compound [Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O QORWJWZARLRLPR-UHFFFAOYSA-H 0.000 description 3
- 238000004065 wastewater treatment Methods 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 2
- 230000002378 acidificating effect Effects 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- JTJMJGYZQZDUJJ-UHFFFAOYSA-N phencyclidine Chemical class C1CCCCN1C1(C=2C=CC=CC=2)CCCCC1 JTJMJGYZQZDUJJ-UHFFFAOYSA-N 0.000 description 2
- 230000009257 reactivity Effects 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 1
- 229910017958 MgNH Inorganic materials 0.000 description 1
- 241000207961 Sesamum Species 0.000 description 1
- 235000003434 Sesamum indicum Nutrition 0.000 description 1
- 238000010306 acid treatment Methods 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000003463 adsorbent Substances 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 159000000007 calcium salts Chemical class 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-N carbonic acid Chemical compound OC(O)=O BVKZGUZCCUSVTD-UHFFFAOYSA-N 0.000 description 1
- 230000008859 change Effects 0.000 description 1
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- 239000003337 fertilizer Substances 0.000 description 1
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- 238000010438 heat treatment Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
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- 230000000813 microbial effect Effects 0.000 description 1
- 238000009448 modified atmosphere packaging Methods 0.000 description 1
- 235000019837 monoammonium phosphate Nutrition 0.000 description 1
- 238000011369 optimal treatment Methods 0.000 description 1
- 239000010815 organic waste Substances 0.000 description 1
- -1 phosphorus compound Chemical class 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
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Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E50/00—Technologies for the production of fuel of non-fossil origin
- Y02E50/30—Fuel from waste, e.g. synthetic alcohol or diesel
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- Removal Of Specific Substances (AREA)
- Purification Treatments By Anaerobic Or Anaerobic And Aerobic Bacteria Or Animals (AREA)
- Treatment Of Sludge (AREA)
Abstract
Description
本発明は、有機性廃水または汚泥の処理方法及び処理装置に関し、特に、有機性廃水または汚泥中の有機物を嫌気性微生物の働きによって嫌気性処理する設備を含む有機物処理システムにおいて、有機物中のリン成分をリン酸マグネシウムアンモニウム（以下、「ＭＡＰ」と称す）等のリン化合物として回収することが可能な有機性廃水または汚泥の処理方法及び処理装置に関する。 The present invention relates to a method and an apparatus for treating organic wastewater or sludge, and more particularly, to an organic matter treatment system including a facility for anaerobic treatment of organic matter in organic wastewater or sludge by the action of anaerobic microorganisms. The present invention relates to a method and an apparatus for treating organic wastewater or sludge capable of recovering a component as a phosphorus compound such as magnesium ammonium phosphate (hereinafter referred to as “MAP”).
有機性廃水または汚泥から窒素成分及びリン成分を分離する方法として、有機性廃水または汚泥にマグネシウムイオンなどを添加して、廃水中に含まれるリン、アンモニア及びマグネシウムイオンを反応させてＭＡＰの結晶を成長させ、ＭＡＰ粒子として分離回収する方法（「ＭＡＰ処理法」と称する）が知られている。 As a method of separating nitrogen component and phosphorus component from organic wastewater or sludge, magnesium ions and the like are added to organic wastewater or sludge, and phosphorus, ammonia and magnesium ions contained in the wastewater are reacted to form MAP crystals. A method of growing and separating and recovering as MAP particles (referred to as “MAP treatment method”) is known.
このようなＭＡＰ処理法は、薬剤使用量、機械動力、熱エネルギーも比較的少なく安価な晶析法であり、リン成分の回収を安定的に行うことが出来る上、回収されるＭＡＰは優れた肥料としての付加価値があるため、資源の有効利用の点からも優れたリン及び窒素の回収兼除去技術である。 Such a MAP treatment method is an inexpensive crystallization method in which the amount of drug used, mechanical power, and heat energy are relatively small and the phosphorus component can be stably recovered, and the MAP recovered is excellent. Since it has added value as a fertilizer, it is an excellent phosphorus and nitrogen recovery and removal technology from the viewpoint of effective use of resources.
ＭＡＰ処理法に関しては、例えば特許文献１において有機性廃水を嫌気性処理する嫌気性消化工程において汚泥中に発生するＭＡＰ粒子を液体サイクロンなどによって分離し、該ＭＡＰ粒子を含むＭＡＰ分離濃縮液を得た後、該ＭＡＰ分離濃縮液にマグネシウムイオンを新たに添加し、溶解しているリン成分との反応によって、該ＭＡＰ濃縮液に存在するＭＡＰ粒子の表面に新たなＭＡＰを積層させてＭＡＰ粒子として回収し、ＭＡＰ粒子回収後のＭＡＰ脱離汚泥は脱水して脱水ケーキとして排出させる方法が提案されている。 Regarding the MAP treatment method, for example, in Patent Document 1, MAP particles generated in sludge in an anaerobic digestion step of anaerobically treating organic wastewater are separated by a liquid cyclone or the like to obtain a MAP separation concentrated solution containing the MAP particles. After that, magnesium ions are newly added to the MAP separation concentrated solution, and a new MAP is laminated on the surface of the MAP particles existing in the MAP concentrated solution by a reaction with a dissolved phosphorus component to form MAP particles. A method has been proposed in which the MAP desorbed sludge after the collection and MAP particle recovery is dehydrated and discharged as a dewatered cake.
また、特許文献２では有機性廃水または汚泥を嫌気性処理する嫌気性消化工程において、該嫌気性処理の前段に有機性汚泥を濃縮汚泥と濃縮脱離液に固液分離する工程、該濃縮汚泥のみを嫌気性処理する工程、該嫌気性処理汚泥からＭＡＰ粒子を分離する工程、及び該嫌気性処理汚泥を濃縮・脱水処理する工程をそれぞれ有する処理方式において、該嫌気性処理前段濃縮脱離水、該嫌気性処理汚泥から分離した該ＭＡＰ粒子、該嫌気性処理後濃縮・脱水分離水、及びマグネシウム源を混合することでＭＡＰ生成しＭＡＰを分離回収する方法が提案されている。 Further, in Patent Document 2, in an anaerobic digestion step of anaerobically treating organic wastewater or sludge, a step of solid-liquid separation of organic sludge into a concentrated sludge and a concentrated desorbed liquid prior to the anaerobic treatment, Only the anaerobic treatment sludge, a step of separating MAP particles from the anaerobic treatment sludge, and a treatment system having a step of concentrating and dewatering the anaerobic treatment sludge, wherein the anaerobic treatment pre-stage concentration desorption water, A method has been proposed in which MAP is generated by mixing the MAP particles separated from the anaerobic treated sludge, the concentrated / dewatered separated water after the anaerobic treatment, and a magnesium source, and the MAP is separated and recovered.
また、特許文献３では有機性汚泥を固液分離して４−１２ｗｔ％の濃縮汚泥と濃縮分離液に分離し、該濃縮汚泥を嫌気性消化し、該嫌気性消化汚泥と先の濃縮分離水を混合後、脱水処理を行う方法が提案されている。 In Patent Document 3, an organic sludge is separated into a solid and a liquid to separate 4-12 wt% of a concentrated sludge and a concentrated separated liquid, the concentrated sludge is anaerobically digested, and the anaerobic digested sludge and the above concentrated separated water are separated. And then performing a dehydration treatment after mixing.
しかしながら、特許文献１〜３のいずれも回収対象となる有機物の嫌気性処理とリン回収をともに効率良く行うための処理に関してはまだ検討の余地がある。 However, in any of Patent Documents 1 to 3, there is still room for study on the treatment for efficiently performing both the anaerobic treatment of the organic matter to be collected and the phosphorus collection.
本発明者らはこれまで様々な有機性廃水または汚泥を対象として有機物中の溶解性リン成分をＭＡＰ粒子として回収する研究を行ってきたところ、回収対象となる有機物の嫌気性処理とリン回収がともに効率良く行われるプロセスを設計するための基本的な情報となる知見として、以下の（１）〜（５）に示す事項を見出した。なお、これらの知見はいずれも様々なパイロット試験等で定量的に確認された事項である。 The present inventors have been conducting research on recovering soluble phosphorus components in organic matter as MAP particles for various organic wastewaters or sludges, and the anaerobic treatment of the organic matter to be recovered and phosphorus recovery have been carried out. The following items (1) to (5) were found as knowledge serving as basic information for designing a process in which both processes are performed efficiently. These findings are all quantitatively confirmed by various pilot tests and the like.
（１）下水処理場等で発生する嫌気性消化汚泥中のリンの形態は、水処理系でリン固定用に使用される無機凝集剤の種類と添加率により変化するが、該汚泥中リンの約５〜８割がＰＯ4−Ｐ、またはＭＡＰの形態で存在することからこれらのリンを汚泥から回収することにより汚泥中のリンは減少し汚泥固形物排出量が１０％以上削減できる場合があること。 (1) The form of phosphorus in anaerobic digested sludge generated in a sewage treatment plant or the like varies depending on the type and addition rate of an inorganic coagulant used for fixing phosphorus in a water treatment system. Since about 50 to 80% is present in the form of PO 4 -P or MAP, by recovering these phosphorus from the sludge, the phosphorus in the sludge can be reduced, and the sludge solids discharge amount can be reduced by 10% or more. There is.
（２）メタン発酵等の嫌気性処理に投入される有機物はある程度までは高濃度化する方が、メタン発酵槽容量が小さくなり滞留日数も１０−１５日程度と比較的短くでき、ガス発電などに利用可能な余剰メタンガス生成量が投入有機物ＶＳあたりで比較的多くなりメタン発酵効率が良いこと。 (2) The concentration of organic matter to be introduced into anaerobic treatment such as methane fermentation is increased to some extent, the capacity of methane fermentation tank becomes smaller and the number of staying days can be relatively short, about 10-15 days. The amount of surplus methane gas that can be used for methane fermentation is relatively large per input organic matter VS, and the methane fermentation efficiency is good.
（３）固形物濃度がＴＳ：１０〜５０ｇ／Ｌ程度の高濃度有機性汚泥中においても一定以上の種晶ＭＡＰ粒子が存在する環境下では嫌気性処理投入溶解性リン成分の８割以上を粒子径１０μｍ以上の比較的大きなＭＡＰ粒子として形成することができること。 (3) Even in a high-concentration organic sludge having a solid concentration of TS: about 10 to 50 g / L, in an environment where a certain number of seed crystal MAP particles are present, 80% or more of the anaerobic treatment input soluble phosphorus component is used. That it can be formed as relatively large MAP particles having a particle diameter of 10 μm or more.
（４）ＭＡＰ粒子径が１０μｍ以上のＭＡＰ粒子は液体サイクロン等を使用することで汚泥濃度１０ｇ／Ｌ以上の汚泥中から９０％以上の回収率で分離回収することが可能であること。 (4) MAP particles having a MAP particle diameter of 10 μm or more can be separated and recovered at a recovery rate of 90% or more from sludge having a sludge concentration of 10 g / L or more by using a liquid cyclone or the like.
（５）高濃度消化汚泥と消化槽投入前汚泥の濃縮分離水の混合液は脱水性が比較的良好であること。 (5) The mixed solution of the high-concentration digested sludge and the concentrated separated water of the sludge before being put into the digestion tank has relatively good dewaterability.
上記知見に基づいて嫌気性処理とリン回収をより効率化するプロセスを模索する中で、本発明者らが更に鋭意検討したところある課題が浮かび上がった。高濃度消化処理を行う場合、嫌気性消化プロセスに投入する有機物の前処理としての濃縮処理が行われるが、分離された濃縮分離水中に溶解性リン、溶解性Ｍｇが比較的多い場合がある。そのため、嫌気性消化汚泥からのリン回収のみでは、これら嫌気性処理前分離水中の溶解性成分を回収すること、及びそれらを効率良く比較的粒子径の大きいＭＡＰ粒子に晶析させて回収することが困難になる場合がある。 In search of a process for improving the efficiency of the anaerobic treatment and the phosphorus recovery based on the above findings, the present inventors have made further studies and found a certain problem. When performing the high-concentration digestion treatment, a concentration treatment is performed as a pre-treatment of the organic matter to be input to the anaerobic digestion process. However, the separated concentrated separated water may have relatively large amounts of soluble phosphorus and soluble Mg. Therefore, by only recovering phosphorus from anaerobic digestion sludge, it is necessary to recover these soluble components in the separated water before anaerobic treatment, and to efficiently crystallize them into MAP particles having a relatively large particle size and recover them. May be difficult.
汚泥の嫌気性消化処理を行わない、又は行う前の水処理プロセスにおけるリン回収方法としては、嫌気好気法の活用によりリン酸を多く含む分離水等を作成しＣａ塩を添加してリン酸カルシウム：Ｃａ3（ＰＯ4）2として回収する方法や、吸着材によりリン酸を吸着し、リン脱着工程を経て最終的には同様にリン酸カルシウムとして回収する方法等が知られている。 As a method for recovering phosphorus in a water treatment process in which an anaerobic digestion treatment of sludge is not performed, or before performing the treatment, a separated water or the like containing a large amount of phosphoric acid is prepared by utilizing an anaerobic aerobic method, and a calcium salt is added by adding a Ca salt: There are known a method of recovering Ca 3 (PO 4 ) 2 , a method of adsorbing phosphoric acid by an adsorbent, and finally recovering calcium phosphate through a phosphorus desorption step.
しかしながら、嫌気性消化処理前の液体と嫌気性消化処理後汚泥の混合液からのリン回収方式はほとんど報告されていない。その理由は、嫌気性消化を行わない条件下では、反応性も高く、比重も３．１４ｇ／ｃｍ3と比較的沈降分離しやすいリン酸カルシウム等のＣａ系沈澱物として分離回収するのが一般的であるが、嫌気性消化を行った後では消化汚泥中に炭酸イオンが多く存在することからＣａを添加するとリン酸カルシウムよりも先に炭酸カルシウムが生成し易く効率が悪くなるためである。 However, there has been almost no report on a method of recovering phosphorus from a liquid mixture of a liquid before the anaerobic digestion treatment and a sludge after the anaerobic digestion treatment. The reason is that under the condition that anaerobic digestion is not performed, it is common to separate and collect as a Ca-based precipitate such as calcium phosphate which has a high reactivity and a specific gravity of 3.14 g / cm 3 which is relatively easy to precipitate and separate. However, after performing anaerobic digestion, there are many carbonate ions in the digested sludge, so that when Ca is added, calcium carbonate is apt to be generated before calcium phosphate, resulting in poor efficiency.
嫌気性消化処理を行う場合、嫌気性消化槽に投入される汚泥中の溶解性リン、及び溶解性Ｍｇは消化槽に投入された直後に、約１０００ｍｇ／Ｌ程度のＮＨ4−Ｎと接触し、さらにｐＨも急激にアルカリ性領域まで上昇するため、瞬時に微細なＭＡＰ粒子が生成される。消化槽内でのＭＡＰ生成反応の反応性が各基質成分の溶解度積で決まることは自明ではあるものの、消化槽に投入された直後の槽内の流動条件における汚泥中のＭＡＰ溶解度積の変化速度、微細ＭＡＰ結晶核の新規生成量、及び既存種ＭＡＰ粒子への付着晶析量等に関しては現時点では依然として不明な部分が多く、これまでどの程度の溶解性リンや溶解性Ｍｇの供給量が消化槽内でどの程度の粒子径のＭＡＰ粒子を形成することになるかという研究はほとんど報告されていない。 When performing the anaerobic digestion treatment, the soluble phosphorus and the soluble Mg in the sludge fed into the anaerobic digestion tank come into contact with about 1000 mg / L of NH 4 -N immediately after being fed into the digestion tank. Further, since the pH rapidly rises to the alkaline region, fine MAP particles are instantaneously generated. Although it is obvious that the reactivity of the MAP generation reaction in the digestion tank is determined by the solubility product of each substrate component, the rate of change of the MAP solubility product in the sludge under the flow conditions in the tank immediately after being introduced into the digestion tank At present, there is still a lot of uncertainty about the amount of new MAP crystal nuclei generated and the amount of crystallization adhering to existing MAP particles, and the supply of soluble phosphorus and soluble Mg Few studies have been reported on how much MAP particles will form in the tank.
その理由としては、汚泥から直接ＭＡＰ粒子を回収しようとする取り組みが現時点でまだ少ない事、消化槽内で生成されるＭＡＰ粒子の粒子径分布が後段でＭＡＰ分離回収する液体サイクロン等のＭＡＰ分離性を左右する重要因子となっていくということがまだ広く認識されていない事、そもそも有機性汚泥中に存在する無機性微粒子の種類や形状や物性に関する報告が非常に少ない事等が挙げられる。 The reasons are as follows: At present, there are few efforts to directly recover MAP particles from sludge, and the particle size distribution of MAP particles generated in the digestion tank has a MAP separation property such as liquid cyclone that separates and recovers MAP at a later stage. It has not been widely recognized that it will be an important factor influencing the organic matter, and there are very few reports on the type, shape and physical properties of inorganic fine particles present in organic sludge in the first place.
この点に関し、例えば、特許文献１の方式では、嫌気性処理前の汚泥から直接ＭＡＰ粒子を回収しようとする手法については記載も示唆もされていない。一方、特許文献２の方式では、嫌気性処理する前の汚泥を濃縮分離した濃縮分離水をＭＡＰ造粒反応装置へ供給することは一応記載されているが、特許文献２に記載される発明にも、嫌気性処理前の汚泥から直接ＭＡＰ粒子を回収しようとする手法については記載も示唆もされていない。 In this regard, for example, in the method of Patent Document 1, there is no description or suggestion of a method of directly collecting MAP particles from sludge before anaerobic treatment. On the other hand, in the method of Patent Document 2, it is described temporarily that concentrated water separated and concentrated from sludge before anaerobic treatment is supplied to a MAP granulation reaction apparatus. However, there is no description or suggestion of a method for directly recovering MAP particles from sludge before anaerobic treatment.
さらに、特許文献２では、ＭＡＰ造粒反応装置へ供給される晶析対象液は有機性汚泥固形分をほとんど含まない固液分離後のろ液が主体であり、晶析処理水を水処理系である最初沈殿池へ返送している図３の記載からしても、晶析処理水は濁度が低いことは明らかであり、ＭＡＰ造粒反応装置へ嫌気性消化処理前の汚泥を積極的に供給するという記載は見当たらない。 Further, in Patent Document 2, the crystallization target liquid supplied to the MAP granulation reaction apparatus is mainly a filtrate after solid-liquid separation containing almost no organic sludge solids, and the crystallization water is treated with a water treatment system. It is clear from the description in FIG. 3 that the crystallization water is returned to the first sedimentation basin, which has low turbidity, and the sludge before the anaerobic digestion treatment is positively sent to the MAP granulation reactor. There is no description to supply to.
また、特許文献２では消化汚泥中に残留するリン酸イオンからのＭＡＰ回収方法として消化汚泥の脱水処理後の脱水ろ液をＭＡＰ反応槽に供給する方式を採用しているが、この方法では脱水処理時に使用される凝集剤や脱水機洗浄排水により汚泥が希釈されるためＭＡＰ反応槽に供給される時点でのろ液中リン酸イオン濃度、及びＭｇイオン濃度が２／３程度に希釈されることが多く、ＭＡＰ反応が溶解度積による化学反応であることからリン回収率としては消化汚泥を直接ＭＡＰ反応槽に供給してリン回収する方法と比較して大幅に低下する場合がある。 Patent Document 2 discloses a method of supplying a dehydrated filtrate after dehydration treatment of digested sludge to a MAP reaction tank as a method of recovering MAP from phosphate ions remaining in digested sludge. Since the sludge is diluted by the coagulant used in the treatment and the dewatering water from the dehydrator, the phosphate ion concentration and the Mg ion concentration in the filtrate at the time when the sludge is supplied to the MAP reaction tank are diluted to about 2/3. In many cases, since the MAP reaction is a chemical reaction based on the solubility product, the phosphorus recovery rate may be significantly reduced as compared with the method of recovering phosphorus by directly supplying digested sludge to the MAP reaction tank.
また、特許文献３の方式は、汚泥濃度４〜１２ｗｔ％の汚泥を用いた高効率な高濃度嫌気性消化の例が開示されているだけで、有機物の嫌気性処理とリン回収率の向上をより効率的に両立させる手法については記載も示唆もされていない。 In addition, the method of Patent Document 3 discloses only an example of high-efficiency, high-concentration anaerobic digestion using sludge having a sludge concentration of 4 to 12 wt%, and improves the anaerobic treatment of organic substances and the improvement of phosphorus recovery rate. There is no description or suggestion of a method to achieve more efficient compatibility.
上記課題を鑑み、本発明は、回収対象となる有機物の嫌気性処理とリン回収とをともに効率良く行うことが可能な有機性廃水または汚泥の処理方法及び処理装置を提供する。 In view of the above problems, the present invention provides a method and apparatus for treating organic wastewater or sludge, which can efficiently perform both anaerobic treatment of an organic substance to be collected and phosphorus recovery.
本願発明者らは上記課題を解決すべく嫌気性処理工程で生成されるＭＡＰ粒子の粒子径を左右する因子に関して、基質濃度、ＶＳ濃度、各種共存イオン、温度、ｐＨ、ＯＲＰ、粘性、種晶表面積、流動条件、基質供給方式、有機物分解速度等に関して様々な実験を通じて鋭意研究した結果、嫌気性処理工程へ供給される直前の汚泥中の「リン酸イオン」、及び「Ｍｇイオン」の総量が生成ＭＡＰ粒子径に影響を及ぼしていることを見出した。 In order to solve the above-mentioned problems, the inventors of the present application have determined the factors affecting the particle size of MAP particles generated in the anaerobic treatment step, such as substrate concentration, VS concentration, various coexisting ions, temperature, pH, ORP, viscosity, and seed crystal. As a result of diligent research through various experiments on surface area, flow conditions, substrate supply method, organic matter decomposition rate, etc., the total amount of “phosphate ions” and “Mg ions” in sludge immediately before being supplied to the anaerobic treatment process It has been found that it has an influence on the produced MAP particle size.
言い換えれば、供給汚泥中のリン酸イオンとＭｇイオンが嫌気性処理工程内の定常時のリン酸イオン濃度とＭｇイオン濃度と比較してそれぞれ大きく、その差が大きいほど微細ＭＡＰを形成し易いということであり、この差は定常時の嫌気性処理工程のリン酸とＭｇの濃度を基準とした比較となるため、必ずしも投入汚泥中のリン酸イオン濃度やＭｇイオン濃度の値だけで決まるものでは無いというものである。本発明者らはこのΔＰＯ4−Ｐ（投入汚泥リン酸−嫌気性処理工程リン酸）とΔＳ−Ｍｇ（投入汚泥Ｍｇイオン−嫌気性処理工程Ｍｇイオン）、及び［ΔＰＯ4−Ｐ／投入汚泥Ｔ−Ｐ］、［ΔＳ−Ｍｇ／投入汚泥Ｔ−Ｍｇ］等を指標とすることによってより最適な処理プロセスを選択でき、目標リン回収率を達成できることを見出した。 In other words, the phosphate ions and the Mg ions in the supplied sludge are larger than the phosphate ion concentration and the Mg ion concentration in the steady state in the anaerobic treatment process, respectively, and the larger the difference, the easier the fine MAP is formed. That is, since this difference is a comparison based on the concentrations of phosphoric acid and Mg in the anaerobic treatment step in a steady state, it is not necessarily determined only by the values of the phosphate ion concentration and the Mg ion concentration in the input sludge. It is not. The present inventors have found that ΔPO 4 -P (input sludge phosphoric acid-anaerobic treatment step phosphoric acid), ΔS-Mg (input sludge Mg ion-anaerobic treatment step Mg ion), and [ΔPO 4 -P / input sludge It has been found that a more optimal treatment process can be selected by using [TP], [ΔS-Mg / input sludge T-Mg] and the like as indexes, and a target phosphorus recovery rate can be achieved.
ここで仮に消化槽への投入汚泥のＰＯ4−Ｐ濃度、Ｓ−Ｍｇ濃度をそれぞれ［ＰＯ4−Ｐ−ｉｎ］、［Ｓ−Ｍｇ−ｉｎ］とし、消化槽内定常時完全混合状態の汚泥のＰＯ4−Ｐ濃度、Ｓ−Ｍｇ濃度をそれぞれ［ＰＯ4−Ｐ−ｏｕｔ］、［Ｓ−Ｍｇ−ｏｕｔ］とし、さらに該投入汚泥のＴ−Ｐ濃度、Ｔ−Ｍｇ濃度をそれぞれ［Ｔ−Ｐ−ｉｎ］、［Ｔ−Ｍｇ−ｉｎ］とした場合の以下の（１）、（２）式で示される数値をそれぞれＬ値（Ｐ）とＬ値（Ｍｇ）とすると、消化汚泥中の微細ＭＡＰ率（＝微細ＭＡＰ−Ｐ／Ｔ−Ｐ）に関して図１、図２に示すような相関関係がある。
Ｌ値（Ｐ）＝（［ＰＯ4−Ｐ−ｉｎ］−［ＰＯ4−Ｐ−ｏｕｔ］）／［Ｔ−Ｐ−ｉｎ］ …（１）
Ｌ値（Ｍｇ）＝（［Ｓ−Ｍｇ−ｉｎ］−［Ｓ−Ｍｇ−ｏｕｔ］）／［Ｔ−Ｍｇ−ｉｎ］ …（２）
Here, the PO 4 -P concentration and the S-Mg concentration of the sludge fed into the digestion tank are assumed to be [PO 4 -P-in] and [S-Mg-in], respectively. The PO 4 -P concentration and the S-Mg concentration are respectively [PO 4 -P-out] and [S-Mg-out], and the TP concentration and the T-Mg concentration of the input sludge are respectively [TP-P]. -In] and [T-Mg-in], the values represented by the following equations (1) and (2) are defined as L value (P) and L value (Mg), respectively. The MAP ratio (= fine MAP-P / TP) has a correlation as shown in FIGS.
L value (P) = ([PO 4 -P-in] - [PO 4 -P-out]) / [T-P-in] ... (1)
L value (Mg) = ([S-Mg-in]-[S-Mg-out]) / [T-Mg-in] (2)
より具体的には、有機性廃水または汚泥を効率的に嫌気性処理およびリン回収する方法として、嫌気性処理工程に供給する汚泥に対して嫌気性処理工程に供給する前に、供給汚泥中の溶解性リン、及び溶解性Ｍｇの量を大幅に軽減するための所定の処置を施し、溶解性リン及び溶解性Ｍｇの嫌気性処理工程への供給量を大幅に軽減した状態で、嫌気性処理を行う。そして、嫌気性処理汚泥及び嫌気性処理工程に直接供給しなかった溶解性リン及び溶解性Ｍｇを含む液をともにＭＡＰ晶析リアクターに供給し、液体サイクロン等のＭＡＰ分離装置を使用してＭＡＰ晶析リアクター内のＭＡＰ濃度を所定濃度に維持するようにＭＡＰ分離装置とＭＡＰ晶析リアクターとの間で循環ラインを形成し、必要に応じて該リアクター内にＭｇ源を供給することで有機性廃水または汚泥に含まれる溶解性リンを軽減しＭＡＰ回収量を最大化する方式が好ましい手法の一つであることを見出した。 More specifically, as a method for efficiently performing anaerobic treatment and phosphorus recovery of organic wastewater or sludge, sludge supplied to the anaerobic treatment step is supplied to the anaerobic treatment step before being supplied to the anaerobic treatment step. The anaerobic treatment was performed in a state where the prescribed treatment for significantly reducing the amount of soluble phosphorus and soluble Mg was performed, and the supply amount of soluble phosphorus and soluble Mg to the anaerobic treatment step was significantly reduced. I do. Then, both the anaerobic treated sludge and the liquid containing soluble phosphorus and soluble Mg not directly supplied to the anaerobic treatment step are supplied to the MAP crystallization reactor, and the MAP crystallization is performed using a MAP separation device such as a liquid cyclone. A circulation line is formed between the MAP separation device and the MAP crystallization reactor so as to maintain the MAP concentration in the crystallization reactor at a predetermined concentration, and an Mg source is supplied into the reactor as needed to supply organic wastewater. Alternatively, it has been found that a method of reducing the amount of soluble phosphorus contained in sludge and maximizing the amount of MAP recovered is one of preferred methods.
以上の知見を基礎として完成した本発明の実施の形態に係る有機性廃水又は汚泥の処理方法は、一側面において、有機性廃水または汚泥に対して嫌気性処理を行う工程と、有機性廃水または汚泥中のリン成分をリン酸マグネシウムアンモニウム粒子の形態で回収する工程を含む有機性廃水または汚泥の処理方法であって、有機性廃水または汚泥を嫌気性処理した後の嫌気性処理液体と、嫌気性処理する前段の有機性廃水または汚泥に含まれる溶解性リンまたは溶解性マグネシウムとを、リン酸マグネシウムアンモニウム粒子が存在する液体内で混合し、混合液のｐＨを調整することによりリン酸マグネシウムアンモニウム粒子を晶析させ、該リン酸マグネシウムアンモニウム粒子を分離濃縮した後のＭＡＰ濃縮液またはＭＡＰ脱離汚泥を汚泥処理系に戻すことを特徴とする有機性廃水または汚泥の処理方法である。 The method for treating organic wastewater or sludge according to the embodiment of the present invention completed based on the above findings is, in one aspect, a step of performing anaerobic treatment on organic wastewater or sludge, An organic effluent or sludge treatment method comprising a step of recovering a phosphorus component in sludge in the form of magnesium ammonium phosphate particles, wherein the anaerobic treatment liquid after the anaerobic treatment of the organic waste water or sludge, The soluble phosphorus or soluble magnesium contained in the organic wastewater or sludge of the preceding stage of the sexual treatment is mixed in the liquid in which the magnesium ammonium phosphate particles are present, and the pH of the mixed solution is adjusted to adjust the magnesium ammonium phosphate. The MAP concentrate or the MAP desorbed sludge after crystallizing the particles and separating and concentrating the magnesium ammonium phosphate particles is sludge. A treatment method of organic wastewater or sludge and returning to science.
本発明の実施の形態に係る有機性廃水または汚泥の処理方法は一実施態様において、嫌気性処理を行う前段の有機性廃水または汚泥を固液分離して濃縮汚泥と濃縮分離水とに分離し、濃縮汚泥を嫌気性処理工程に導入し、濃縮分離水と嫌気性処理後の嫌気性処理液体とを共にＭＡＰ晶析リアクターに導入することを含む。 In one embodiment, the method for treating organic wastewater or sludge according to the embodiment of the present invention is to separate the organic wastewater or sludge at the stage prior to performing anaerobic treatment into solid-liquid separation to separate into concentrated sludge and concentrated separated water. And introducing the concentrated sludge to the anaerobic treatment step, and introducing both the concentrated separated water and the anaerobic treated liquid after the anaerobic treatment to the MAP crystallization reactor.
本発明の実施の形態に係る有機性廃水または汚泥の処理方法は別の一実施態様において、嫌気性処理を行う前段の有機性廃水または汚泥と、嫌気性処理後の嫌気性処理液体の少なくとも一部とを共にＭＡＰ晶析リアクターに導入し、該ＭＡＰ晶析リアクター内で晶析したリン酸マグネシウムアンモニウム粒子を分離濃縮した後のＭＡＰ脱離汚泥の少なくとも一部を嫌気性処理に循環返送することを含む。 In another embodiment, the method for treating organic wastewater or sludge according to the embodiment of the present invention includes at least one of organic wastewater or sludge before the anaerobic treatment and anaerobic treatment liquid after the anaerobic treatment. The MAP desorption sludge after separation and concentration of the magnesium ammonium phosphate particles crystallized in the MAP crystallization reactor. including.
本発明の実施の形態に係る有機性廃水または汚泥の処理方法は別の一実施態様において、嫌気性処理後の嫌気性処理液体をＭＡＰ濃縮液とＭＡＰ脱離汚泥とに分離し、ＭＡＰ濃縮液をＭＡＰ晶析リアクターに導入し、ＭＡＰ脱離汚泥をＭＡＰ晶析リアクターの処理系外へ排出することを含む。 In another embodiment of the method for treating organic wastewater or sludge according to the embodiment of the present invention, the anaerobic treatment liquid after the anaerobic treatment is separated into a MAP concentrate and a MAP desorbed sludge, and the MAP concentrate Into the MAP crystallization reactor, and discharging the MAP desorbed sludge out of the treatment system of the MAP crystallization reactor.
本発明の実施の形態に係る有機性廃水または汚泥の処理方法は別の一実施態様において、有機性廃水または汚泥を嫌気性処理した後の嫌気性処理液体と、嫌気性処理する前段の有機性廃水または汚泥に含まれる溶解性リンまたは溶解性マグネシウムを導入するＭＡＰ晶析リアクター内または該ＭＡＰ晶析リアクターの前段において物理的脱炭酸処理を施す。 In another embodiment, the method for treating organic wastewater or sludge according to the embodiment of the present invention is an anaerobic treatment liquid after the anaerobic treatment of the organic wastewater or sludge, and the organic matter before the anaerobic treatment. A physical decarboxylation treatment is performed in a MAP crystallization reactor for introducing soluble phosphorus or soluble magnesium contained in wastewater or sludge or in a preceding stage of the MAP crystallization reactor.
本発明の実施の形態に係る有機性廃水または汚泥の処理方法は別の一実施態様において、嫌気性処理する前段の有機性廃水または汚泥に含まれる溶解性リンまたは溶解性マグネシウムを、粒子径１０μｍ以上のリン酸マグネシウムアンモニウム粒子が５ｇ／Ｌ以上存在する液体内で混合する。 In another embodiment, the method for treating organic wastewater or sludge according to the embodiment of the present invention is to dissolve soluble phosphorus or soluble magnesium contained in organic wastewater or sludge prior to anaerobic treatment with a particle diameter of 10 μm. The above magnesium ammonium phosphate particles are mixed in a liquid containing 5 g / L or more.
本発明の実施の形態に係る有機性廃水または汚泥の処理方法は別の一実施態様において、混合液のｐＨが６．８以上となるようにｐＨを調整する。 In another embodiment of the method for treating organic wastewater or sludge according to the embodiment of the present invention, the pH is adjusted such that the pH of the mixed solution is 6.8 or higher.
本発明の実施の形態に係る有機性廃水または汚泥の処理装置は一側面において、有機性廃水または汚泥を濃縮汚泥と濃縮分離水とに分離する濃縮装置と、濃縮汚泥に対して嫌気性処理を行い、嫌気性処理液体を得る嫌気性処理装置と、濃縮分離水と嫌気性処理液体とを導入し、リン酸マグネシウムアンモニウム粒子が存在する液体内で混合液のｐＨを調整してリン酸マグネシウムアンモニウム粒子を晶析させるＭＡＰ晶析リアクターと、ＭＡＰ晶析リアクターで得られたＭＡＰ晶析処理水からリン酸マグネシウムアンモニウム粒子を分離濃縮し、ＭＡＰ濃縮液及びＭＡＰ脱離汚泥を得るＭＡＰ分離装置と、ＭＡＰ濃縮液をＭＡＰ晶析リアクターへ返送する配管ラインとを備えることを特徴とする有機性廃水または汚泥の処理装置である。 In one aspect, an organic wastewater or sludge treatment apparatus according to an embodiment of the present invention includes a concentration apparatus that separates organic wastewater or sludge into concentrated sludge and concentrated separated water, and an anaerobic treatment for concentrated sludge. An anaerobic treatment apparatus for obtaining an anaerobic treatment liquid, a concentrated separation water and an anaerobic treatment liquid are introduced, and the pH of the mixed solution is adjusted in the liquid in which the magnesium ammonium phosphate particles are present, and the magnesium ammonium phosphate is adjusted. A MAP crystallization reactor for crystallizing particles, and a MAP separation device for separating and concentrating magnesium ammonium phosphate particles from MAP crystallization-treated water obtained in the MAP crystallization reactor to obtain a MAP concentrated solution and MAP desorbed sludge, A piping line for returning the MAP concentrate to the MAP crystallization reactor.
本発明は更に別の一側面において、有機性廃水または汚泥に対して嫌気性処理を行う嫌気性処理装置と、嫌気性処理を行う前段の有機性廃水または汚泥と、嫌気性処理後の嫌気性処理液体の少なくとも一部とを共に導入し、リン酸マグネシウムアンモニウム粒子が存在する液体内で混合液のｐＨを調整してリン酸マグネシウムアンモニウム粒子を晶析させるＭＡＰ晶析リアクターと、ＭＡＰ晶析リアクターで得られたＭＡＰ晶析処理水からリン酸マグネシウムアンモニウム粒子を分離濃縮し、ＭＡＰ濃縮液及びＭＡＰ脱離汚泥を得るＭＡＰ分離装置と、ＭＡＰ脱離汚泥を嫌気性処理装置へ返送する配管ラインとを備えることを特徴とする有機性廃水または汚泥の処理装置である。 In still another aspect of the present invention, an anaerobic treatment apparatus for performing anaerobic treatment on organic wastewater or sludge, an organic effluent or sludge at the preceding stage of performing anaerobic treatment, and anaerobic treatment after anaerobic treatment A MAP crystallization reactor that introduces at least a part of the processing liquid together and adjusts the pH of the mixed solution in the liquid in which the magnesium ammonium phosphate particles are present to crystallize the magnesium ammonium phosphate particles; and a MAP crystallization reactor. A MAP separation device for separating and concentrating magnesium ammonium phosphate particles from the MAP crystallization-treated water obtained in step 1 to obtain a MAP concentrated solution and MAP desorbed sludge, and a piping line for returning the MAP desorbed sludge to the anaerobic treatment device. An organic wastewater or sludge treatment apparatus comprising:
本発明によれば、回収対象となる有機物の嫌気性処理とリン回収とをともに効率良く行うことが可能な有機性廃水または汚泥の処理方法及び処理装置が提供できる。 Advantageous Effects of Invention According to the present invention, it is possible to provide a method and an apparatus for treating organic wastewater or sludge that can efficiently perform both anaerobic treatment of an organic substance to be collected and phosphorus recovery.
以下、図面を参照しながら本発明の実施の形態を説明する。以下に示す実施の形態は、この発明の技術的思想を具体化するための装置や方法を例示するものであってこの発明の技術的思想は構成部品の構造、配置等を下記のものに特定するものではない。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments described below exemplify an apparatus and a method for embodying the technical idea of the present invention. The technical idea of the present invention specifies the structure, arrangement, and the like of the components as follows. It does not do.
本明細書では、水処理系として標準活性汚泥処理を採用し、汚泥処理系として嫌気性消化処理と脱水処理をそれぞれ採用する一般的な下水処理場を一例として説明する。しかしながら、当業者であれば、有機性廃液または有機物を処理する施設として嫌気的処理を組み込む食品系廃水処理、し尿系廃水処理、生ごみや有機廃材系廃水処理等のあらゆる処理プロセスに適応または応用が可能であり、例示する下水処理に限定されるものではないことは勿論である。 In the present specification, an example of a general sewage treatment plant that employs standard activated sludge treatment as a water treatment system and employs anaerobic digestion treatment and dehydration treatment as sludge treatment systems, respectively, will be described. However, those skilled in the art can adapt or apply to any treatment process such as food wastewater treatment, human wastewater treatment, garbage and organic wastewater treatment, which incorporates anaerobic treatment as a facility for treating organic wastewater or organic matter. It is needless to say that the present invention is not limited to the exemplified sewage treatment.
また、本明細書における「微細ＭＡＰ」とは、液体サイクロン等の分離装置によって汚泥から分離することが困難な粒径１０μｍ以下の微粒子状のＭＡＰを意味し、「粗ＭＡＰ」とは、液体サイクロン等の分離装置によって汚泥から分離可能な粒径１０μｍ以下の微粒子状のＭＡＰを意味する。「全ＭＡＰ」とは、上記微細ＭＡＰと粗ＭＡＰとを合わせたものを意味し、「種晶ＭＡＰ」とは、粒径は粗ＭＡＰサイズを有し、ＭＡＰ晶析反応を促進させるために予め槽内に一定量充填し流動させておくＭＡＰ粒子を意味する。種晶ＭＡＰが十分存在すると、ＭＡＰ反応は種晶ＭＡＰ表面上で種晶ＭＡＰをコーティングする形で晶析するので、反応したＰＯ4−ＰやＳ−Ｍｇの成分は粗ＭＡＰの粒径サイズのＭＡＰとなり、液体サイクロン等の分離装置で分離回収が可能となる。 The term “fine MAP” as used herein means a particulate MAP having a particle diameter of 10 μm or less which is difficult to separate from sludge by a separation device such as a liquid cyclone. Etc. means fine particulate MAP having a particle size of 10 μm or less that can be separated from sludge by a separation device such as “Total MAP” means a combination of the fine MAP and the coarse MAP, and “seed crystal MAP” means that the particle size has a coarse MAP size, and is used in advance to promote the MAP crystallization reaction. It means MAP particles that are filled in a certain amount in a tank and are allowed to flow. When the seed MAP is sufficiently present, the MAP reaction is crystallized on the surface of the seed MAP so as to coat the seed MAP, so that the reacted PO 4 -P or S-Mg component has a particle size of the coarse MAP. It becomes MAP and can be separated and collected by a separation device such as a hydrocyclone.
下水処理場に流入する有機成分は、水処理系において最初沈澱池で沈降分離した有機酸を多く含む初沈汚泥と最終沈澱池で沈降分離した活性汚泥性微生物を多く含む余剰汚泥の二種類の汚泥に取り込まれ、これらを混合した混合生汚泥として汚泥処理系へ送られる。この混合生汚泥は汚泥処理系において嫌気性消化処理等により有機物の分解、可燃性ガス回収、脱水処理により減量化、場合によっては乾燥処理、焼却処理により更に減量化を行った後に脱水ケーキ、または焼却灰の形態で場外に搬出されるのが一般的である。これら汚泥減量化工程において分離される分離水は一般的には返流水として水処理系の最初沈澱池等に返送される。 There are two types of organic components flowing into the sewage treatment plant: primary sludge, which contains a lot of organic acids that settled and separated in the sedimentation basin, and excess sludge, which contains lots of activated sludge microorganisms that settled and separated in the final sedimentation basin. The sludge is taken into the sludge and sent to a sludge treatment system as a mixed raw sludge. This mixed raw sludge is decomposed by decomposing organic matter by anaerobic digestion treatment in a sludge treatment system, reducing the amount of flammable gas, dehydration treatment, and in some cases, further reducing the amount by drying treatment and incineration treatment, and then performing dehydration cake, or It is generally carried out of the site in the form of incinerated ash. The separated water separated in the sludge reduction step is generally returned to the first settling basin of the water treatment system as return water.
嫌気性消化処理に供給される混合生汚泥の溶解成分中には、初沈汚泥由来の有機酸とトレードする形で活性汚泥系微生物が放出したリン酸イオンとマグネシウムイオン、及び初沈汚泥由来のマグネシウムイオンが多く存在する。有機酸はできるだけ嫌気性消化処理に導入してメタン等の可燃ガスとして回収することが望ましいが、リン酸イオンやマグネシウムイオンは嫌気性消化処理に導入されると有機物分解副産物である炭酸イオン（解離すると水酸イオン）とアンモニアイオンによりＭＡＰとして晶析し易くなり消化槽内や後段設備のスケールリスク要因となる。 Among the dissolved components of the mixed raw sludge supplied to the anaerobic digestion treatment, phosphate ions and magnesium ions released by activated sludge microorganisms in a form that trades with organic acids derived from primary sludge, and those derived from primary sludge There are many magnesium ions. It is desirable that organic acids be introduced into the anaerobic digestion treatment as much as possible and recovered as combustible gas such as methane. However, phosphate ions and magnesium ions are introduced into the anaerobic digestion treatment, and carbonate ions, which are by-products of organic matter decomposition (dissociation) Then, it becomes easy to crystallize as MAP by the hydroxyl ion) and the ammonia ion, which becomes a scale risk factor in the digestion tank and the subsequent equipment.
一般的な下水汚泥の消化槽内の消化汚泥はｐＨが７．０−７．５程度の弱アルカリ性で、汚泥中にはＮＨ4−Ｎが６００−１２００ｍｇ／Ｌ程度、ＰＯ4−Ｐが５０−３００ｍｇ／Ｌ程度、Ｍｇイオンが１．０−３０ｍｇ／Ｌ程度存在する場合が多い。ＭｇＮＨ4・ＰＯ4ＯＨ・５Ｈ2Ｏの構造式を持つリン酸マグネシウムアンモニウム（ＭＡＰ）分子は、消化槽内で生成し、Ｍｇ律速でＭＡＰ生成が抑えられている場合が多く、消化槽内の消化汚泥中に存在するＭＡＰ量はＭＡＰ−Ｐ換算で２００−４５０ｍｇ／Ｌ程度存在する場合が多い。 Digested sludge in a general sewage sludge digestion tank is weakly alkaline with a pH of about 7.0 to 7.5, and NH 4 —N contains about 600 to 1200 mg / L and PO 4 —P contains 50 in the sludge. In many cases, about -300 mg / L and Mg ions exist in about 1.0-30 mg / L. Magnesium ammonium phosphate (MAP) molecules having the structural formula of MgNH 4 · PO 4 OH · 5H 2 O are generated in the digestion tank, and the MAP generation is often controlled by the Mg-limiting rate. The amount of MAP present in digested sludge is often about 200-450 mg / L in MAP-P conversion.
また、このＭＡＰ粒子は粒子径が０．１μｍ以下〜１ｍｍ以上まで幅広く存在し、液体サイクロン等を使用して消化汚泥１１から直接、ＭＡＰ粒子（比重：１．７）を回収するために必要な粗ＭＡＰ粒子サイズのＭＡＰ粒子存在比率は１０〜３５％程度である。 Further, the MAP particles have a wide range of particle diameters from 0.1 μm or less to 1 mm or more, and are necessary for directly collecting MAP particles (specific gravity: 1.7) from digested sludge 11 using a liquid cyclone or the like. The MAP particle existence ratio of the coarse MAP particle size is about 10 to 35%.
本発明者らの研究により、消化槽内のこのようなＭＡＰ溶解成分のバランスの中に一般的な混合生汚泥が投入されると、混合生汚泥中のＰＯ4−ＰやＭｇイオンが消化槽内のｐＨ、ＮＨ4−ＮとのバランスでＭＡＰ生成が急速に進行し、消化槽内の混合生汚泥投入部において微細な新規のＭＡＰ粒子が大量に生成されることが分かってきた。微細ＭＡＰ粒子を生成する要因としては、ＰＯ4 3-、Ｍｇ+、ＮＨ4+、ＯＨ-等の基質成分以外に、種晶ＭＡＰ量、種晶粒子径、流動条件等が関係するが、既存の消化槽内の環境ではこの投入汚泥由来のＰＯ4−ＰやＭｇイオンが起因となる消化槽内での微細ＭＡＰ生成を抑制することが困難であることが分かってきた。 According to the study of the present inventors, when a general mixed raw sludge is put into the balance of such MAP dissolved components in the digester, PO 4 -P and Mg ions in the mixed raw sludge are converted into the digester. It has been found that MAP generation progresses rapidly due to the balance between pH and NH 4 -N in the inside, and a large amount of new fine MAP particles are generated in the mixed raw sludge input section in the digestion tank. Factors that generate fine MAP particles are related to the seed crystal MAP amount, seed crystal particle diameter, flow conditions, etc., in addition to substrate components such as PO 4 3- , Mg + , NH 4+ , and OH −. It has been found that it is difficult to suppress the production of fine MAP in the digester caused by PO 4 -P and Mg ions derived from the input sludge in the environment in the digester.
既存の消化槽の環境で生成した微細ＭＡＰは後段のＭＡＰ晶析リアクターに直接導入しても短時間で微細ＭＡＰ粒子全量を粗ＭＡＰレベルに肥大化させることが困難であるため、最終的に消化槽内で生成した微細ＭＡＰの多くは最終的に回収できない場合が多い。そこで、発明者らは消化槽内での微細ＭＡＰ生成にとって最も寄与率の高い、消化槽投入液中の「ＰＯ4−ＰとＭｇイオン」を消化槽に投入する前に粗ＭＡＰとして回収する方法を実証検討していく中で以下の知見を得た。 Even if the fine MAP generated in the existing digester environment is directly introduced into the subsequent MAP crystallization reactor, it is difficult to increase the total amount of the fine MAP particles to the coarse MAP level in a short period of time. Many of the fine MAPs generated in the tank cannot be finally recovered in many cases. Then, the inventors recover the “PO 4 -P and Mg ions” in the digestion tank input liquid, which is the most contributing factor to the generation of fine MAP in the digestion tank, as a crude MAP before putting it into the digestion tank. During the empirical study, the following findings were obtained.
すなわち、この消化槽に供給されるリン酸イオンとＭｇイオンの各濃度と消化槽内定常時のリン酸イオンとＭｇイオンの各濃度との落差が大きく、それらの値が投入汚泥のＴ−Ｐ、Ｔ−Ｍｇに対して比率が大きいほど、該消化槽内で生成されるＭＡＰ粒子の粒径が小さくなり、最終的にはリン回収率が低下することが判明した。 That is, there is a large drop between each concentration of phosphate ion and Mg ion supplied to this digester and each concentration of phosphate ion and Mg ion at the time of steady state in the digester. It was found that the larger the ratio with respect to T-Mg, the smaller the particle size of the MAP particles generated in the digestion tank, and finally the lower the phosphorus recovery rate.
具体的な態様としては、以下に示す第１の実施の形態及び第２の実施の形態の二つの方式が利用可能であり、汚泥性状等の諸条件に応じていずれかを選択することが有効である。 As a specific mode, the following two systems of the first embodiment and the second embodiment can be used, and it is effective to select one of them according to various conditions such as sludge properties. It is.
（第１の実施の形態：濃縮分離水−消化汚泥混合リン回収方式）
第１の実施の形態に係る有機性廃水または汚泥の処理装置は、図３に示すように、流入水１を処理する最初沈澱池２１、曝気槽２２、最終沈澱池２３を含む水処理系２の処理設備と、最初沈澱池２１で得られる初沈汚泥５及び最終沈澱池２３で得られる余剰汚泥７を混合して混合生汚泥８とし、混合生汚泥８を処理する汚泥処理系３の処理設備とを備える。
(First Embodiment: Concentrated Separation Water-Digested Sludge Mixed Phosphorus Recovery System)
As shown in FIG. 3, an organic wastewater or sludge treatment apparatus according to the first embodiment includes a water treatment system 2 including an initial sedimentation basin 21, an aeration tank 22, and a final sedimentation basin 23 for treating inflow water 1. And the sludge treatment system 3 for treating the mixed raw sludge 8 by mixing the initial sludge 5 initially obtained in the sedimentation basin 21 and the excess sludge 7 obtained in the final sedimentation basin 23 to obtain mixed raw sludge 8. Equipment.
最初沈澱池２１では、流入水１から有機酸を多く含む初沈汚泥５と流出水４とに分離される。流出水４は曝気槽２２において活性汚泥微生物と共に好気処理が行われ、活性汚泥を含む活性汚泥混合液６が得られる。活性汚泥混合液は、最終沈澱池２３において固液分離されて余剰汚泥７と処理水が得られる。 In the first settling basin 21, the influent 1 is separated into an initial sediment 5 containing much organic acid and an effluent 4. The effluent 4 is subjected to aerobic treatment together with the activated sludge microorganisms in the aeration tank 22 to obtain the activated sludge mixed liquid 6 containing the activated sludge. The activated sludge mixture is subjected to solid-liquid separation in the final sedimentation basin 23 to obtain excess sludge 7 and treated water.
最終沈澱池２３で沈降分離した活性汚泥性微生物を多く含む余剰汚泥７と初沈汚泥５は、混合槽３１において混合され、混合生汚泥８が得られる。混合槽３１で得られた混合生汚泥８は、濃縮装置３２に供給され、濃縮装置３２において凝集剤などが添加されることにより、後段の消化槽３３による嫌気性処理に適した汚泥濃度に濃縮処理されて濃縮汚泥９と濃縮分離水１０とに分離される。 The excess sludge 7 containing a large amount of activated sludge microorganisms settled and separated in the final sedimentation basin 23 and the initial sludge 5 are mixed in the mixing tank 31 to obtain a mixed raw sludge 8. The mixed raw sludge 8 obtained in the mixing tank 31 is supplied to a concentrating device 32, and a coagulant or the like is added in the concentrating device 32, thereby concentrating the mixed sludge 8 to a sludge concentration suitable for anaerobic treatment in a digestion tank 33 in the subsequent stage. The treated sludge is separated into concentrated sludge 9 and concentrated separated water 10.
濃縮装置３２において濃縮汚泥は典型的には汚泥（ＴＳ）濃度２ｗｔ％以上、より典型的には４〜１２ｗｔ％、更に典型的には７〜１０ｗｔ％程度に濃縮される。濃縮装置３２で混合生汚泥８を濃縮して高濃度化することにより、後段の消化槽３３に投入される汚泥の体積を小さくすることができるため消化槽３３を小型化することができる。濃縮分離水１０の一部は最初沈澱池２１へ返送することができる。濃縮分離水１０の他の一部は配管ラインを介してＭＡＰ晶析リアクター３４へ供給される。また、濃縮分離水１０のリン酸、Ｍｇ、有機酸などの成分量によっては全量を最初沈澱池２１に返送しても良いし、全量をＭＡＰ晶析リアクター３４に供給しても良い。 In the concentration device 32, the concentrated sludge is typically concentrated to a sludge (TS) concentration of 2 wt% or more, more typically 4 to 12 wt%, and still more typically about 7 to 10 wt%. By concentrating the mixed raw sludge 8 by the concentrating device 32 to increase the concentration, the volume of the sludge fed into the digestion tank 33 at the subsequent stage can be reduced, so that the digestion tank 33 can be downsized. Part of the concentrated separated water 10 can be returned to the settling basin 21 at first. Another part of the concentrated separation water 10 is supplied to the MAP crystallization reactor 34 via a piping line. Further, depending on the amount of components such as phosphoric acid, Mg, and organic acid in the concentrated separation water 10, the entire amount may be returned to the precipitation tank 21 first, or the entire amount may be supplied to the MAP crystallization reactor 34.
濃縮汚泥９は消化槽３３に投入され、消化槽３３において濃縮汚泥９に対する嫌気性処理が行われて嫌気性消化液体（消化汚泥１１）が得られる。本明細書において「嫌気性処理」とは、主に絶対嫌気性微生物によるメタン発酵もしくはメタン発酵を主体とする処理を意味する。消化汚泥１１の一部又は全部は消化槽３３内から引き抜かれ、ＭＡＰ晶析リアクター３４へ導入される。 The concentrated sludge 9 is introduced into the digestion tank 33, and the anaerobic treatment of the concentrated sludge 9 is performed in the digestion tank 33 to obtain an anaerobic digestion liquid (digestion sludge 11). In the present specification, “anaerobic treatment” means methane fermentation by an anaerobic microorganism or a treatment mainly comprising methane fermentation. Part or all of the digested sludge 11 is withdrawn from the digestion tank 33 and introduced into the MAP crystallization reactor.
ＭＡＰ晶析リアクター３４は、粒子径１０μｍ以上のリン酸マグネシウムアンモニウム粒子が少なくとも５ｇ／Ｌ存在する液体内で混合液のｐＨが６．８以上となるようにｐＨを調整してリン酸マグネシウムアンモニウム粒子を晶析させる装置である。 The MAP crystallization reactor 34 adjusts the pH of the mixed solution to be 6.8 or more in a liquid containing at least 5 g / L of magnesium ammonium phosphate particles having a particle diameter of 10 μm or more, and adjusts the pH of the magnesium ammonium phosphate particles by This is an apparatus for crystallizing.
図示を省略するが、ＭＡＰ晶析リアクター３４は、晶析対象液のｐＨを調整するためのｐＨ調整機構、リアクター内のＭＡＰ粒子の濃度を調節するための粒子濃度調節機構、必要に応じてＭｇイオンを供給するためのＭｇ供給機構を備えている。ＭＡＰ晶析リアクター３４には、濃縮装置３２で得られた濃縮分離水１０と消化汚泥１１との混合液が導入され、ＭＡＰ晶析リアクター３４内においてはＭＡＰ粒子の晶析反応が進行する。ＭＡＰ晶析リアクター３４で処理されたＭＡＰ晶析処理水１２は、ＭＡＰ晶析リアクター３４の外部へ排出され、ＭＡＰ分離装置３５へ導入される。 Although not shown, the MAP crystallization reactor 34 includes a pH adjusting mechanism for adjusting the pH of the liquid to be crystallized, a particle concentration adjusting mechanism for adjusting the concentration of the MAP particles in the reactor, and Mg as needed. An Mg supply mechanism for supplying ions is provided. A mixed solution of the concentrated separated water 10 and the digested sludge 11 obtained by the concentrating device 32 is introduced into the MAP crystallization reactor 34, and the MAP particle crystallization reaction proceeds in the MAP crystallization reactor 34. The MAP crystallization treated water 12 treated in the MAP crystallization reactor 34 is discharged outside the MAP crystallization reactor 34 and introduced into the MAP separation device 35.
ＭＡＰ分離装置３５は、ＭＡＰ晶析リアクター３４で得られたＭＡＰ晶析処理水１２からリン酸マグネシウムアンモニウム粒子を分離、回収するための装置であり、例えば、液体サイクロン等が好適に用いられる。 The MAP separation device 35 is a device for separating and recovering magnesium ammonium phosphate particles from the MAP crystallization treated water 12 obtained in the MAP crystallization reactor 34. For example, a liquid cyclone or the like is suitably used.
ＭＡＰ分離装置３５においては、粗ＭＡＰ粒子が分離濃縮されたＭＡＰ濃縮液１４と粗ＭＡＰ粒子が取り除かれたＭＡＰ脱離汚泥１３とが得られる。粗ＭＡＰ粒子が分離濃縮されたＭＡＰ濃縮液１４は、汚泥処理系３の設備の一つであるＭＡＰ晶析リアクター３４とＭＡＰ分離装置３５との間に設けられた配管ラインを介してＭＡＰ晶析リアクター３４内へ循環返送されるとともに、一部が回収ＭＡＰとして系外に排出され、洗浄、乾燥後種々の用途に利用される。 In the MAP separation device 35, a MAP concentrate 14 in which coarse MAP particles are separated and concentrated and a MAP desorbed sludge 13 in which coarse MAP particles are removed are obtained. The MAP concentrate 14 in which the coarse MAP particles are separated and concentrated is subjected to MAP crystallization via a piping line provided between a MAP crystallization reactor 34, which is one of the facilities of the sludge treatment system 3, and a MAP separation device 35. It is circulated back into the reactor 34, and a part is discharged out of the system as a recovered MAP, and is used for various uses after washing and drying.
このように、配管ラインを通じてＭＡＰ分離装置３５で得られた粗ＭＡＰ粒子が分離濃縮ＭＡＰ濃縮液１４を返送することにより、ＭＡＰ晶析リアクター３４内のＭＡＰ濃度を所定濃度に安定的に維持することができるため、ＭＡＰ晶析リアクター３４内のＭＡＰの晶析反応を安定的に進行させることができる。ＭＡＰ分離装置３５で得られたＭＡＰ脱離汚泥１３は、脱水装置３６に導入され、脱水装置３６において脱水処理が行われ、脱水ケーキが得られる。 In this manner, the MAP concentration in the MAP crystallization reactor 34 is stably maintained at a predetermined concentration by returning the separated and concentrated MAP concentrate 14 by the coarse MAP particles obtained by the MAP separation device 35 through the pipe line. Therefore, the MAP crystallization reaction in the MAP crystallization reactor 34 can proceed stably. The MAP desorbed sludge 13 obtained by the MAP separation device 35 is introduced into a dewatering device 36, and is subjected to a dewatering treatment in the dewatering device 36 to obtain a dewatered cake.
上述の図３に示す処理装置を用いて、第１の実施の形態に係る有機性廃水または汚泥の処理方法を実施することができる。すなわち、第１の実施の形態に係る処理方法は、有機性廃水または汚泥に対して嫌気性処理を行う工程と、有機性廃水または汚泥中のリン成分をリン酸マグネシウムアンモニウム粒子の形態で回収する工程を含む処理方法である。 The method for treating organic wastewater or sludge according to the first embodiment can be performed using the treatment apparatus shown in FIG. 3 described above. That is, the treatment method according to the first embodiment includes a step of performing anaerobic treatment on organic wastewater or sludge, and recovering a phosphorus component in the organic wastewater or sludge in the form of magnesium ammonium phosphate particles. This is a processing method including steps.
本方法は、有機性廃水または汚泥を含む混合生汚泥８を消化槽３３において嫌気性処理した後の嫌気性処理液体（消化汚泥１１）と、嫌気性処理する前段の混合生汚泥８に含まれる溶解性リンまたは溶解性マグネシウムを、好適には粒子径１０μｍ以上のリン酸マグネシウムアンモニウム粒子が５ｇ／Ｌ以上存在する液体を収容したＭＡＰ晶析リアクター３４内で混合し、混合液のｐＨが好適には６．８以上となるように、更に好ましくはｐＨ７．１〜７．８にｐＨを調整することによりリン酸マグネシウムアンモニウム粒子を晶析させ、晶析したリン酸マグネシウムアンモニウム粒子をＭＡＰ分離装置３５において分離濃縮した後のＭＡＰ濃縮液１４をＭＡＰ晶析リアクター３４に戻し、ＭＡＰ脱離汚泥１３を脱水装置３６に送ることを含む。ＭＡＰ濃縮液１４の一部からはＭＡＰが回収される。 In this method, the mixed raw sludge 8 containing the organic wastewater or the sludge is contained in the anaerobic treatment liquid (digestion sludge 11) after the anaerobic treatment in the digestion tank 33 and the mixed raw sludge 8 before the anaerobic treatment. The soluble phosphorus or soluble magnesium is mixed in a MAP crystallization reactor 34 containing a liquid containing preferably 5 g / L or more of magnesium ammonium phosphate particles having a particle diameter of 10 μm or more, and the pH of the mixed solution is preferably adjusted. Is adjusted to pH 6.8 or more, more preferably, to pH 7.1 to 7.8 to crystallize the magnesium ammonium phosphate particles. The MAP concentrated solution 14 after the separation and concentration is returned to the MAP crystallization reactor 34 and the MAP desorbed sludge 13 is sent to a dehydration device 36. . MAP is recovered from a part of the MAP concentrate 14.
嫌気性処理を行う前段の有機性廃水または汚泥、即ち混合生汚泥８は、濃縮装置３２において固液分離して濃縮汚泥９と濃縮分離水１０とに分離する工程を含むことが好ましい。濃縮汚泥９は嫌気性処理工程に導入し、濃縮分離水１０と嫌気性処理後の嫌気性処理液体である消化汚泥１１は共に、ＭＡＰ晶析リアクター３４に導入することが好ましい。これにより、嫌気性処理工程に供給される汚泥中の溶解性リンおよび溶解性マグネシウムの量を嫌気性処理工程にその汚泥が供給される前に予め低減させることができるため、嫌気性処理工程において生成されるその後の晶析反応に寄与しにくい微細なＭＡＰの生成を抑え、汚泥中の溶解性リンを回収ＭＡＰとしてより回収しやすい形態に制御することができる。 It is preferable to include a step of separating the organic wastewater or sludge, that is, the mixed raw sludge 8 in the former stage of the anaerobic treatment, into solid-liquid separation in the concentrator 32 and separating it into the concentrated sludge 9 and the concentrated separated water 10. It is preferable that the concentrated sludge 9 is introduced into the anaerobic treatment step, and the concentrated separation water 10 and the digested sludge 11 which is the anaerobic treatment liquid after the anaerobic treatment are both introduced into the MAP crystallization reactor 34. Thereby, the amount of soluble phosphorus and soluble magnesium in the sludge supplied to the anaerobic treatment step can be reduced in advance before the sludge is supplied to the anaerobic treatment step. The generation of fine MAP that is less likely to contribute to the subsequent crystallization reaction that is generated can be suppressed, and the soluble phosphorus in the sludge can be controlled to a form that can be more easily recovered as recovered MAP.
このように、第１の実施の形態に係る有機性廃水または汚泥の処理装置及び処理方法によれば、嫌気性処理の対象となる溶解性有機物が比較的少ない混合生汚泥８を処理する場合であっても、濃縮装置３２において混合生汚泥８を消化槽３３における嫌気性処理に適切な汚泥濃度に濃縮することができるため、小型の消化槽３３においてより多くの有用性ガスを効率的に発生させることができる。 As described above, according to the organic wastewater or sludge treatment apparatus and the treatment method according to the first embodiment, the mixed raw sludge 8 having a relatively small amount of soluble organic matter to be subjected to anaerobic treatment is treated. Even so, the mixed raw sludge 8 can be concentrated in the concentration apparatus 32 to a sludge concentration suitable for anaerobic treatment in the digestion tank 33, so that more useful gas is efficiently generated in the small digestion tank 33. Can be done.
さらに、濃縮装置３２で得られる濃縮分離水と消化槽３３から排出される消化汚泥１１とをＭＡＰ晶析リアクター３４へ導入し、晶析反応を進行させることで、従来は水処理系２へと供給されていた溶解性リン及び溶解性マグネシウムを汚泥処理系におけるＭＡＰの晶析反応に利用することが可能となり、ＭＡＰ分離装置３５で回収されるリンの回収率をより向上させることが可能となる。 Furthermore, the concentrated separation water obtained by the concentrating device 32 and the digested sludge 11 discharged from the digestion tank 33 are introduced into the MAP crystallization reactor 34, and the crystallization reaction is allowed to proceed. The supplied soluble phosphorus and soluble magnesium can be used for the MAP crystallization reaction in the sludge treatment system, and the recovery rate of phosphorus recovered by the MAP separation device 35 can be further improved. .
さらに、ＭＡＰ分離装置３５から排出されるＭＡＰ濃縮液１４を必要に応じてＭＡＰ晶析リアクター３４へ循環返送させることにより、ＭＡＰ晶析リアクター３４内のＭＡＰ濃度を粗ＭＡＰ粒子の晶析に好適な所定濃度に維持することができ、さらに必要に応じてＭＡＰ晶析リアクター３４内にＭｇ源を供給することで、ＭＡＰ晶析リアクター３４内における晶析反応をより安定的に進行させることができるため、安定したリン回収率が得られるようになる。Ｍｇ源の供給量は具体的にはＭＡＰ晶析リアクター３４内に供給されるＰＯ4−Ｐとのモル比としての「Ｍｇ／Ｐ比」ベースで０．５〜１．３の範囲内になるようにＭｇ源を供給することが微細ＭＡＰ生成防止、コスト軽減、及び後段のスケール防止の観点からも望ましい。 Further, the MAP concentrate 14 discharged from the MAP separation device 35 is circulated and returned to the MAP crystallization reactor 34 as necessary, so that the MAP concentration in the MAP crystallization reactor 34 is suitable for crystallization of coarse MAP particles. Since the concentration can be maintained at a predetermined concentration, and the Mg source is supplied into the MAP crystallization reactor 34 as necessary, the crystallization reaction in the MAP crystallization reactor 34 can proceed more stably. As a result, a stable phosphorus recovery rate can be obtained. Specifically, the supply amount of the Mg source is in the range of 0.5 to 1.3 based on the “Mg / P ratio” as a molar ratio with the PO 4 -P supplied into the MAP crystallization reactor 34. Supplying the Mg source as described above is also desirable from the viewpoints of preventing the generation of fine MAP, reducing costs, and preventing scale at the subsequent stage.
さらに、第１の実施の形態によれば、混合生汚泥８に含まれる溶解性リンまたは溶解性マグネシウムを最大限に利用して、ＭＡＰ晶析リアクター３４内でより多くのＭＡＰ粒子を晶析させることができる。そのため、図６及び図７に示すような従来法では存在していたＭＡＰ粒子の多くが、本実施形態の脱水ケーキ中には除去されているため、脱水ケーキとしての固形物の排出量を小さくすることができる。その結果、ケーキ処分コストも大幅に軽減できる。 Further, according to the first embodiment, more MAP particles are crystallized in the MAP crystallization reactor 34 by making maximum use of the soluble phosphorus or the soluble magnesium contained in the mixed raw sludge 8. be able to. Therefore, since most of the MAP particles existing in the conventional method as shown in FIGS. 6 and 7 are removed in the dewatered cake of the present embodiment, the discharge amount of solids as the dewatered cake is reduced. can do. As a result, the cake disposal cost can be significantly reduced.
また、脱水処理により分離された脱水分離水は従来法よりもＰＯ4−ＰとＭｇイオンが大幅に軽減していることから、脱水分離水を返流水として水処理系２に戻しても水処理系２でのリン負荷増加率は従来法と比較して小さくすることができる。 Further, since PO 4 -P and Mg ions are greatly reduced in the dewatered separated water separated by the dewatering treatment as compared with the conventional method, even if the dewatered separated water is returned to the water treatment system 2 as return water, the water treatment is performed. The phosphorus load increase rate in the system 2 can be reduced as compared with the conventional method.
第１の実施の形態に係る有機性廃水または汚泥の処理装置及び処理方法は、混合生汚泥８中の溶解性有機物が比較的少ない場合に特に好適に適応できる。その際、混合生汚泥８を濃縮分離する際に、濃縮汚泥９になるべく有機物が多く濃縮され、且つ溶解性リンと溶解性マグネシウムの濃度をできるだけ少なくなるように、初沈汚泥５と余剰汚泥７を混合する前後における撹拌条件や曝気条件を適正に調整することも有効である。 The apparatus and method for treating organic wastewater or sludge according to the first embodiment can be particularly suitably applied when the amount of soluble organic matter in the mixed raw sludge 8 is relatively small. At that time, when the mixed raw sludge 8 is concentrated and separated, the primary sludge 5 and the excess sludge 7 are concentrated so that the organic matter is concentrated as much as possible into the concentrated sludge 9 and the concentrations of the soluble phosphorus and the soluble magnesium are reduced as much as possible. It is also effective to appropriately adjust the stirring conditions and the aeration conditions before and after mixing.
以下に限定されるものではないが、例えば、ＭＡＰ晶析リアクター３４に導入する消化汚泥１１の１日当たりの供給量を１Ｑとした場合、濃縮分離水１０を０．５〜２．０Ｑとすることが好ましく、一実施態様では、消化汚泥１１の１日当たりの供給量を０．３Ｑとした場合に濃縮分離水１０を０．７Ｑとすることで、より効率的な処理を行うことができる。 Although not limited to the following, for example, when the daily supply amount of the digested sludge 11 to be introduced into the MAP crystallization reactor 34 is 1Q, the concentrated separation water 10 is set to 0.5 to 2.0Q. In one embodiment, when the daily supply amount of the digested sludge 11 is 0.3 Q, the concentrated separated water 10 is set to 0.7 Q, so that more efficient treatment can be performed.
（第２の実施の形態：混合生汚泥の嫌気性処理前リン回収方式）
第２の実施の形態に係る有機性廃水または汚泥の処理装置は、図４に示すように、混合生汚泥８を消化槽３３へ供給する前に、ＭＡＰ晶析リアクター３４へ供給する点が、第１の実施の形態に係る有機性廃水または汚泥の処理装置と異なる。
(Second embodiment: phosphorus recovery method before anaerobic treatment of mixed raw sludge)
As shown in FIG. 4, the organic wastewater or sludge treatment apparatus according to the second embodiment supplies mixed raw sludge 8 to a MAP crystallization reactor 34 before supplying the mixed raw sludge 8 to a digestion tank 33. It is different from the organic wastewater or sludge treatment apparatus according to the first embodiment.
即ち、第２の実施の形態に係る有機性廃水または汚泥の処理装置は、嫌気性処理を行う消化槽３３と、嫌気性処理を行う前段の混合生汚泥８と消化槽３３で得られる消化汚泥１１の少なくとも一部とを共に導入し、リン酸マグネシウムアンモニウム粒子を晶析させるＭＡＰ晶析リアクター３４と、ＭＡＰ晶析リアクター３４で得られたＭＡＰ晶析処理水１７からリン酸マグネシウムアンモニウム粒子を濃縮分離するＭＡＰ分離装置３５と、ＭＡＰ分離装置３５においてリン酸マグネシウムアンモニウム粒子を分離濃縮した後のＭＡＰ濃縮液１４をＭＡＰ晶析リアクター３４に循環させるかまたは一部系外に排出して回収し、ＭＡＰ脱離汚泥１６を汚泥処理系３の消化槽３３へと返送する配管ラインとを備える。 That is, the organic wastewater or sludge treatment apparatus according to the second embodiment includes a digestion tank 33 for performing anaerobic treatment, and a mixed raw sludge 8 and a digested sludge obtained in the digestion tank 33 in the preceding stage for performing anaerobic treatment. 11 are introduced together to crystallize magnesium ammonium phosphate particles, and magnesium ammonium phosphate particles are concentrated from MAP crystallization treated water 17 obtained in MAP crystallization reactor 34. A MAP separation device 35 to be separated, and a MAP concentrated solution 14 obtained by separating and concentrating magnesium ammonium phosphate particles in the MAP separation device 35 is circulated to the MAP crystallization reactor 34 or partially discharged out of the system and collected, A piping line for returning the MAP desorbed sludge 16 to the digestion tank 33 of the sludge treatment system 3 is provided.
ＭＡＰ晶析リアクター３４で回収すべき混合生汚泥８中のターゲットの成分はリン酸イオンとＭｇイオンであることから、なるべく混合生汚泥８の全量を対象とすることが望ましく、少なくとも混合生汚泥８の５０％以上を、ＭＡＰ晶析リアクター３４に導入することが好ましい。但し、混合生汚泥８中には髪の毛、トイレットペーパー残査、ゴマ等の植物種子系残査等、比較的粒径の大きい固形物がある程度含まれる場合があり、これらは後段のＭＡＰ分離装置での目詰まりの原因となる場合もある。よって、沈降分離装置または分離スクリーン等を用いてそれら比較的粒径の大きい固形物を主体とした汚泥の一部を消化槽３３に直接投入しても良いし、ＭＡＰ脱離汚泥１６と混合して消化槽３３へ供給させても良く、それにより消化槽３３における有機物の分解効率及びメタンガス等の有用性ガスの生成効率を向上させることができ効果的である。 Since the components of the target in the mixed raw sludge 8 to be recovered in the MAP crystallization reactor 34 are phosphate ions and Mg ions, it is desirable to target the entire amount of the mixed raw sludge 8 as much as possible. Is preferably introduced into the MAP crystallization reactor. However, the mixed raw sludge 8 may contain a relatively large amount of solids such as hair, toilet paper residue, plant seed residue such as sesame, etc. to some extent. It may cause clogging. Therefore, a part of the sludge mainly composed of solids having a relatively large particle diameter may be directly introduced into the digestion tank 33 by using a sedimentation separation device or a separation screen, or may be mixed with the MAP desorbed sludge 16. The gas may be supplied to the digestion tank 33 to effectively improve the decomposition efficiency of organic substances in the digestion tank 33 and the generation efficiency of useful gas such as methane gas.
なお、分離スクリーン等を使用する場合の開口径またはスクリーン幅は０．２５ｍｍ〜５ｍｍ程度が望ましい。ただし、この沈澱分離装置または分離スクリーン等を使用する場合は凝集剤を使用しない物理的な分離方法で行う方が良く、前述の第１の実施の形態において凝集剤を使用する濃縮方法を採用した場合よりも、比較的薬品コストの軽減効果が望める。 In addition, when using a separation screen etc., the opening diameter or screen width is desirably about 0.25 mm to 5 mm. However, when using this sedimentation / separation apparatus or separation screen, it is better to carry out a physical separation method without using a flocculant. In the first embodiment, the concentration method using a flocculant is employed. As compared with the case, the effect of reducing the chemical cost can be relatively expected.
消化槽３３で処理された消化汚泥１１は、液体サイクロン等のＭＡＰ分離装置３７へ供給されてＭＡＰ粒子が分離濃縮され、ＭＡＰ濃縮液１５とＭＡＰ脱離汚泥１３とに分離される。ＭＡＰ濃縮液１５は混合槽３１からの混合生汚泥８とともにＭＡＰ晶析リアクター３４へ導入される。ＭＡＰ脱離汚泥１３は配管ラインを介して脱水装置３６へ導入され、脱水装置３６において脱水処理が行われて脱水ケーキが生成される。 The digested sludge 11 treated in the digestion tank 33 is supplied to a MAP separator 37 such as a liquid cyclone, where MAP particles are separated and concentrated, and separated into a MAP concentrate 15 and MAP desorbed sludge 13. The MAP concentrate 15 is introduced into the MAP crystallization reactor 34 together with the mixed raw sludge 8 from the mixing tank 31. The MAP desorbed sludge 13 is introduced into a dewatering device 36 via a piping line, and is subjected to a dewatering process in the dewatering device 36 to generate a dewatered cake.
ＭＡＰ晶析リアクター３４内では、粒子径１０μｍ以上のリン酸マグネシウムアンモニウム粒子が少なくとも５ｇ／Ｌ以上存在する液体内で混合液のｐＨが６．８以上となるようにｐＨが調整されてＭＡＰ粒子の晶析反応が進行する。ＭＡＰ晶析リアクター３４で処理されたＭＡＰ晶析処理水１７は、液体サイクロン等のＭＡＰ分離装置３５へ導入され、サイクロン分離によってＭＡＰ粒子が分離される。ＭＡＰ粒子回収後に得られるＭＡＰ濃縮液１４はＭＡＰ晶析リアクター３４へ循環返送され、一部が回収される。 In the MAP crystallization reactor 34, the pH is adjusted so that the pH of the mixture becomes 6.8 or more in a liquid in which at least 5 g / L or more of magnesium ammonium phosphate particles having a particle diameter of 10 μm or more are present. The crystallization reaction proceeds. The MAP crystallization water 17 treated in the MAP crystallization reactor 34 is introduced into a MAP separation device 35 such as a liquid cyclone, and MAP particles are separated by cyclone separation. The MAP concentrate 14 obtained after the collection of the MAP particles is circulated back to the MAP crystallization reactor 34, and a part thereof is recovered.
ＭＡＰ脱離汚泥１６は、配管ラインを介して消化槽３３への投入汚泥として利用される。なお、図示していないが、ＭＡＰ濃縮液１４の一部を種晶ＭＡＰとして必要に応じて消化槽３３へ供給する配管ラインが設けられていても構わない。 The MAP desorbed sludge 16 is used as sludge fed into the digestion tank 33 via a piping line. Although not shown, a piping line for supplying a part of the MAP concentrate 14 as a seed crystal MAP to the digestion tank 33 as necessary may be provided.
上述の図４に示す処理装置を用いて、第２の実施の形態に係る有機性廃水または汚泥の処理方法を実施することができる。すなわち、第２の実施の形態に係る処理方法は、混合生汚泥８と、消化槽３３から得られる消化汚泥１１の少なくとも一部とを共に、ＭＡＰ晶析リアクター３４に導入し、ＭＡＰ晶析リアクター３４内で晶析したＭＡＰ粒子を分離濃縮した後のＭＡＰ濃縮液１４またはＭＡＰ脱離汚泥１６の少なくとも一部を消化槽３３における嫌気性処理に循環返送することを含む。 The method for treating organic wastewater or sludge according to the second embodiment can be implemented using the treatment apparatus shown in FIG. 4 described above. That is, in the treatment method according to the second embodiment, the mixed raw sludge 8 and at least a part of the digested sludge 11 obtained from the digestion tank 33 are both introduced into the MAP crystallization reactor 34, and the MAP crystallization reactor This includes circulating and returning at least a part of the MAP concentrate 14 or the MAP desorbed sludge 16 after separating and concentrating the MAP particles crystallized in 34 to the anaerobic treatment in the digestion tank 33.
第２の実施の形態に係る有機性廃水または汚泥の処理方法は、更に、消化汚泥１１をＭＡＰ分離装置３７においてＭＡＰ濃縮液１５とＭＡＰ脱離汚泥１３とに分離し、ＭＡＰ濃縮液１５をＭＡＰ晶析リアクター３４に導入し、ＭＡＰ脱離汚泥１３をＭＡＰ晶析リアクター３４の処理系外である脱水装置３６へと排出することを含むことができる。また、消化汚泥１１に存在する粗ＭＡＰ量が十分に少ない場合、例えば１００ｍｇ−Ｐ／Ｌ以下程度で、且つ処理施設サイドの要望等がある場合はＭＡＰ分離装置３７を省略して、消化汚泥１１の所定量をＭＡＰ晶析リアクター３４に導入し、かつ別の所定量を脱水装置３６へと送る装置で代用することも可能である。 In the method for treating organic wastewater or sludge according to the second embodiment, the digested sludge 11 is further separated into a MAP concentrate 15 and a MAP desorbed sludge 13 in a MAP separation device 37, and the MAP concentrate 15 is separated from MAP. The method may include introducing the MAP desorbed sludge 13 into the crystallization reactor 34 and discharging the MAP desorbed sludge 13 to a dehydration device 36 outside the treatment system of the MAP crystallization reactor 34. If the amount of crude MAP existing in the digested sludge 11 is sufficiently small, for example, about 100 mg-P / L or less, and if there is a request from the treatment facility side, the MAP separation device 37 is omitted and the digested sludge 11 is omitted. May be introduced into the MAP crystallization reactor 34, and another predetermined amount may be sent to the dehydration device 36.
また、消化汚泥１１に存在するＰＯ4−Ｐが必要以上に大きい場合、例えば５０ｍｇ−Ｐ／Ｌ以上程度で、且つ処理施設サイドの要望等がある場合は、ＭＡＰ晶析リアクター３４とは別のもう一つのＭＡＰ晶析リアクター（図示せず）を設けて、脱水装置３６へ送る汚泥からＰＯ4−Ｐを除去しＭＡＰとして回収することも有効である場合がある。 Further, when PO 4 -P present in the digested sludge 11 is larger than necessary, for example, about 50 mg-P / L or more, and when there is a request from the treatment facility side, another MAP crystallization reactor 34 is used. It may be effective to provide another MAP crystallization reactor (not shown) to remove PO 4 -P from the sludge sent to the dehydrating device 36 and collect it as MAP.
嫌気性処理の本来の目的である「有機物の分解率最大化及びそれに付随して発生するＣＨ4等の有用性ガス回収量最大化」という観点と、有機物からのリン回収効率化を両立するためには、嫌気性処理工程に導入する物質中にはできるだけ有機物を残し、溶解性リン及び溶解性Ｍｇは除去することが望ましい。 To achieve both the viewpoint of the original purpose of the anaerobic treatment "decomposition rate maximization of organic matter and usefulness gas recovery maximization of CH 4 or the like generated in association with it," the phosphorus recovery efficiency from organic matter In this case, it is desirable to leave as much organic matter as possible in the substance to be introduced into the anaerobic treatment step and to remove soluble phosphorus and soluble Mg.
第２の実施の形態に係る有機性廃水または汚泥の処理装置及び処理方法によれば、混合生汚泥８を嫌気性処理する前に直接、ＭＡＰ晶析リアクター３４に供給し、ＭＡＰ晶析リアクター３４内で混合生汚泥８中の溶解性リン及び溶解性マグネシウムをＭＡＰ粒子に晶析化して分離し、ＭＡＰ粒子を分離した後のＭＡＰ脱離汚泥１３を消化槽３３へ供給することにより、嫌気性処理をより効率的に行えるとともに、リンの回収率を同時に向上させることが可能となる。 According to the apparatus and method for treating organic wastewater or sludge according to the second embodiment, the mixed raw sludge 8 is directly supplied to the MAP crystallization reactor 34 before the anaerobic treatment, and the MAP crystallization reactor 34 is supplied. In the inside, the soluble phosphorus and the soluble magnesium in the mixed raw sludge 8 are crystallized into MAP particles and separated, and the MAP desorbed sludge 13 after the separation of the MAP particles is supplied to the digestion tank 33 to be anaerobic. The treatment can be performed more efficiently, and the recovery rate of phosphorus can be improved at the same time.
ＭＡＰ晶析リアクター３４で晶析反応をより安定的に進行させるためにはｐＨを６．８以上、更には７．１〜７．８のアルカリ領域とすることが望ましい。一方で、一般的な下水の混合生汚泥８は、ｐＨが４．５〜６．５程度の弱酸性であるため、図４に示す処理装置のように、混合生汚泥８をＭＡＰ晶析リアクター３４へ導入することによって、ＭＡＰ晶析リアクター３４へ供給すべきｐＨ調整剤の添加量が多くなる場合がある。 In order to make the crystallization reaction proceed more stably in the MAP crystallization reactor 34, the pH is desirably 6.8 or more, and more desirably an alkaline range of 7.1 to 7.8. On the other hand, since the mixed raw sludge 8 of general sewage is weakly acidic with a pH of about 4.5 to 6.5, the mixed raw sludge 8 is converted into a MAP crystallization reactor as shown in the treatment apparatus shown in FIG. By introducing the pH adjuster into the MAP crystallization reactor, the amount of the pH adjuster to be supplied to the MAP crystallization reactor may increase.
第２の実施の形態に係る処理装置においては、消化汚泥１１の少なくとも一部をアルカリ剤、ＮＨ4、ＰＯ4−Ｐ、及びＭＡＰ種晶の供給剤として利用するために、混合生汚泥８の供給と同時に消化汚泥１１をＭＡＰ晶析リアクター３４に導入し消化汚泥１１の供給量を適宜調整することによって、ＭＡＰ晶析リアクター３４へ供給すべき薬剤の添加量を低減させることができる。汚泥性状により異なるため以下は例示であるが、例えば、混合生汚泥８を一日当たり１Ｑ程度添加する場合、ＭＡＰ濃縮液１５の一日当たりの供給量を０．５〜３Ｑとすることで、ＭＡＰ濃縮液１５の一日当たりの供給量を２Ｑとする場合、混合生汚泥８を１Ｑ程度添加することで、ＭＡＰ晶析リアクター３４へ供給する薬剤の供給量を少なくしながらより多くのＭＡＰを回収することができる。 In the treatment apparatus according to the second embodiment, the mixed raw sludge 8 is used in order to use at least a part of the digested sludge 11 as an alkali agent, NH 4 , PO 4 -P, and a MAP seed crystal feed. By simultaneously introducing the digested sludge 11 into the MAP crystallization reactor 34 and adjusting the supply amount of the digested sludge 11 as needed, the amount of the chemical to be supplied to the MAP crystallization reactor 34 can be reduced. The following is an example, since it differs depending on the sludge properties. For example, when the mixed raw sludge 8 is added at about 1 Q per day, the MAP condensate 15 is supplied at a daily supply rate of 0.5 to 3 Q, thereby increasing the MAP concentration. When the daily supply amount of the liquid 15 is 2Q, by adding about 1Q of the mixed raw sludge 8, it is possible to collect more MAP while reducing the supply amount of the chemical supplied to the MAP crystallization reactor 34. Can be.
混合生汚泥８と消化汚泥１１のＭＡＰ晶析リアクター３４への供給量の比率はそれぞれの汚泥性状によって異なるが、ＭＡＰ晶析リアクター３４内のＭＡＰ晶析環境としてｐＨ：６．７〜７．６、Ｍｇイオン濃度：０．１〜６０ｍｇ／Ｌ、粗ＭＡＰ粒子濃度：７〜７０ｇ／Ｌの範囲となるように、混合生汚泥８と消化汚泥１１の２種類の汚泥ブレンド比、Ｍｇ系薬剤添加量、該リアクター内曝気量、ＭＡＰ引き抜き量等を調整することが望ましい。 The ratio of the supply amount of the mixed raw sludge 8 and the digested sludge 11 to the MAP crystallization reactor 34 varies depending on the properties of each sludge, but the MAP crystallization environment in the MAP crystallization reactor 34 has a pH of 6.7 to 7.6. , Mg ion concentration: 0.1 to 60 mg / L, Crude MAP particle concentration: 7 to 70 g / L, blend ratio of two types of mixed sludge 8 and digested sludge 11, and addition of Mg-based chemicals It is desirable to adjust the amount, the aeration amount in the reactor, the MAP withdrawal amount, and the like.
また、ＭＡＰ晶析リアクター３４に導入する混合生汚泥８と消化汚泥１１は、ＭＡＰ晶析リアクター３４内に導入する前段で一部先に混合しておいても良い場合がある。消化汚泥１１中の一部微細ＭＡＰは弱酸性の混合生汚泥と先に接触することで溶解させることができ、これによりＭＡＰ晶析リアクター３４へのＰＯ4−Ｐ及びＳ−Ｍｇ負荷量を増大させ、リン回収率を向上することができる。 In some cases, the mixed raw sludge 8 and the digested sludge 11 introduced into the MAP crystallization reactor 34 may be partially mixed before being introduced into the MAP crystallization reactor 34. Partially fine MAP in digested sludge 11 can be dissolved by first contacting with weakly acidic mixed raw sludge, thereby increasing the load of PO 4 -P and S-Mg on MAP crystallization reactor 34. And the phosphorus recovery rate can be improved.
消化汚泥１１のＭＡＰ晶析リアクター３４への供給に際しては、一旦ＭＡＰ分離装置３７で消化汚泥１１からＭＡＰを回収して、ＭＡＰ濃縮液１５とＭＡＰ脱離汚泥１３とに分離し、ＭＡＰ濃縮液１５の方をＭＡＰ晶析リアクター３４に導入し、ＭＡＰ脱離汚泥１３の方を系外に排出し脱水処理等を行う方法がリン回収率及び脱水ケーキの排出量低減の観点からはより効率的で好ましい。 When supplying the digested sludge 11 to the MAP crystallization reactor 34, the MAP is once collected from the digested sludge 11 by the MAP separator 37, separated into the MAP concentrate 15 and the MAP desorbed sludge 13, and the MAP concentrate 15 Is introduced into the MAP crystallization reactor 34, and the MAP desorbed sludge 13 is discharged out of the system to perform dehydration treatment, etc., from the viewpoint of reducing the phosphorus recovery rate and the amount of dewatered cake discharged. preferable.
ＭＡＰ晶析リアクター３４を経由して嫌気性処理工程に導入されたＭＡＰ脱離汚泥１６は、消化槽３３内の嫌気性微生物により有機物が分解され、同時に分解代謝物としてＰＯ4−Ｐ、Ｓ−Ｍｇ、ＮＨ4−Ｎが増加し、嫌気性処理工程内でＭＡＰ粒子が生成される。しかし、嫌気性処理工程内のこれらＭＡＰ基質成分濃度は、特にＰＯ4−Ｐ、Ｓ−Ｍｇの汚泥流入部等での急激な濃度変動が少ないことから消化槽３３内におけるＭＡＰ晶析反応は比較的低濃度でゆっくりと進行し、比較的大きなＭＡＰ粒子を形成することが分かっている。すなわち、従来法では嫌気性処理工程で大量に発生していた微細ＭＡＰの生成が、本願発明では抑制されているために、リン回収率としては飛躍的に向上する。 The MAP desorbed sludge 16 introduced into the anaerobic treatment step via the MAP crystallization reactor 34 is decomposed into organic substances by anaerobic microorganisms in the digestion tank 33, and simultaneously PO 4 -P and S- Mg and NH 4 —N increase, and MAP particles are generated in the anaerobic treatment step. However, the concentration of these MAP substrate components in the anaerobic treatment process is relatively small, especially at the sludge inflow portion of PO 4 -P and S-Mg. It has been found that it proceeds slowly at very low concentrations and forms relatively large MAP particles. That is, the generation of fine MAP, which was generated in a large amount in the anaerobic treatment step in the conventional method, is suppressed in the present invention, so that the phosphorus recovery rate is dramatically improved.
（変形例）
混合生汚泥８を嫌気性処理した後の消化汚泥１１と、濃縮分離水１０または濃縮してない状態の混合生汚泥８とを共にＭＡＰ晶析リアクター３４へ供給する前に混合し、消化汚泥１１と濃縮分離水１０または濃縮してない状態の混合生汚泥８に対して物理的脱炭酸処理を行うことが好ましい場合がある。このため、図５に示すように、消化槽３３とＭＡＰ晶析リアクター３４との間、あるいはＭＡＰ晶析リアクター３４内に物理的脱炭酸処理装置３８が設けられていてもよい。
(Modification)
The digested sludge 11 after the mixed raw sludge 8 is subjected to the anaerobic treatment and the concentrated separated water 10 or the mixed raw sludge 8 in a non-concentrated state are mixed together before being supplied to the MAP crystallization reactor 34, and the digested sludge 11 is mixed. It may be preferable to physically decarbonate the concentrated separated water 10 or the mixed raw sludge 8 in a non-concentrated state. For this reason, as shown in FIG. 5, a physical decarboxylation device 38 may be provided between the digestion tank 33 and the MAP crystallization reactor 34 or in the MAP crystallization reactor 34.
物理的脱炭酸処理装置３８としては、曝気装置や機械撹拌装置等を用いることができる。図５に示す処理装置によれば、物理的脱炭酸処理装置３８において消化汚泥１１と濃縮分離水１０または濃縮してない状態の混合生汚泥８とに対して物理的脱炭酸処理を行うことによって、ｐＨが上昇するためｐＨ調整剤の使用量を軽減できるとともに、脱炭酸により上昇したｐＨ環境下においてＭＡＰ晶析がより進行した後の後段のプロセスにおいてスケールリスクが軽減できる。加えてＭＡＰ晶析リアクター３４におけるＭＡＰ粒子の回収率を高めることができるとともに、脱水ケーキの生成量を少なくすることができる。 As the physical decarboxylation device 38, an aeration device, a mechanical stirring device, or the like can be used. According to the treatment apparatus shown in FIG. 5, the physical decarboxylation treatment unit 38 performs the physical decarboxylation treatment on the digested sludge 11 and the concentrated separated water 10 or the mixed raw sludge 8 in a non-concentrated state. As the pH rises, the amount of the pH adjuster used can be reduced, and the scale risk can be reduced in the subsequent process after MAP crystallization has further progressed in the pH environment increased by decarboxylation. In addition, the recovery rate of the MAP particles in the MAP crystallization reactor 34 can be increased, and the amount of the dehydrated cake can be reduced.
図示を省略しているが、物理的脱炭酸処理装置３８は、図４のＭＡＰ分離装置３７の後段且つＭＡＰ晶析リアクター３４の前段に配置し、ＭＡＰ濃縮液１５と混合生汚泥８とを脱炭酸処理するようにすることも勿論可能である。 Although not shown, the physical decarboxylation device 38 is disposed downstream of the MAP separation device 37 in FIG. 4 and upstream of the MAP crystallization reactor 34 to remove the MAP concentrate 15 and the mixed raw sludge 8. Of course, it is also possible to perform carbonic acid treatment.
下水処理場等の処理施設において嫌気性処理工程に導入される有機性汚泥は、水処理系２における運転方式の違い等により汚泥性状が大きく異なり、それにより汚泥中に存在する有機酸、溶解性リン、溶解性Ｍｇの量は様々である。 The organic sludge introduced into the anaerobic treatment process in a treatment facility such as a sewage treatment plant has a greatly different sludge property due to a difference in an operation method in the water treatment system 2 and the like. The amounts of phosphorus and soluble Mg vary.
一概には言えない場合もあるが、例えば下水処理場において嫌気性消化槽に導入される汚泥が、初沈汚泥比率が活性汚泥由来余剰汚泥比率よりも大きい場合、その汚泥は有機酸含有率が比較的高く、逆に活性汚泥由来余剰汚泥の比率が大きい場合は溶解性リン、溶解性マグネシウムが比較的高い。汚泥が前者の場合、嫌気性処理投入汚泥を濃縮分離して濃縮分離水を嫌気性処理に導入しないプロセスでは濃縮分離水の有機酸からのＣＨ4ガス回収が見込めないためにガス回収としては不利になる。汚泥が後者の場合は、嫌気性処理投入汚泥を濃縮分離して濃縮分離水を嫌気性処理に導入しないプロセスでもＣＨ4ガス回収としてはほとんど影響が無く、逆に高濃度メタン発酵が可能となりメタン発酵槽のコンパクト化が可能となり有効である。このように、嫌気性工程に導入する汚泥性状によって、第１の実施の形態、第２の実施の形態及び変形例のいずれかの方式を選択することが好ましい。 Although it cannot be said unconditionally, for example, when the sludge introduced into the anaerobic digestion tank at a sewage treatment plant has a higher initial sludge ratio than the activated sludge-derived excess sludge ratio, the sludge has an organic acid content ratio. When the ratio of the excess sludge derived from the activated sludge is relatively high, the soluble phosphorus and the soluble magnesium are relatively high. If the sludge is the former, disadvantageous as gas collected for that are not expected to be CH 4 gas recovery from an organic acid concentration and separation water concentrated separated water anaerobic treatment turned sludge concentration and separation to a process that does not introduce the anaerobic treatment become. In the case of the latter sludge, even in a process in which the anaerobic treated input sludge is concentrated and separated and the concentrated separated water is not introduced into the anaerobic treatment, there is almost no effect on the recovery of CH 4 gas, and conversely, high-concentration methane fermentation becomes possible. The fermenter can be made more compact and effective. As described above, it is preferable to select any one of the first embodiment, the second embodiment, and the modification depending on the property of the sludge introduced into the anaerobic step.
以下に本発明の実施例を比較例と共に示すが、これらの実施例は本発明及びその利点をよりよく理解するために提供するものであり、発明が限定されることを意図するものではない。 Hereinafter, Examples of the present invention are shown together with Comparative Examples, but these Examples are provided for better understanding of the present invention and its advantages, and are not intended to limit the invention.
下水処理場の水処理系で発生した初沈汚泥、余剰汚泥を用いて、複数の運転条件に切り替えられるパイロットプラントを使用してリン回収を行った。混合生汚泥の嫌気性消化設備としては全て３５℃中温消化を採用し、消化槽水理学的滞留日数は２５日とし、ＭＡＰ分離装置は全て液体サイクロンを使用し、各流量バランスに応じて液体サイクロンのアンダーとオーバーの口径は適宜調節した。液体サイクロン投入液に粒径１０ｍｍ以上の夾雑物が存在する場合は篩で除去し該除去物をサイクロンオーバー液に混合した。 Phosphorus recovery was performed using the initial settling sludge and excess sludge generated in the water treatment system of the sewage treatment plant using a pilot plant that can be switched to multiple operating conditions. As the anaerobic digestion equipment for mixed raw sludge, all medium-temperature digestion at 35 ° C is adopted, the hydraulic retention time of digestion tank is 25 days, and the MAP separation device uses all liquid cyclones, and liquid cyclones are used according to each flow balance. The under and over diameters were adjusted as appropriate. When impurities having a particle diameter of 10 mm or more were present in the liquid added to the cyclone, the liquid was removed with a sieve, and the removed matter was mixed with the cyclone over liquid.
実施例１は、図３に示す構成のパイロットプラントに基づいて運転した場合を示し、実施例１のみ他の比較例１等の消化槽の１／３の容量の消化槽を採用し、消化槽への投入汚泥は混合生汚泥に対して対固形物当たり凝集剤を０．２％添加して汚泥濃度を３倍にした状態で消化槽に投入する方式とした。実施例２は、図４に示す構成のパイロットプラントに基づいて運転した場合を示し、流量バランスとしては種々の条件より１３ＭＡＰ脱離汚泥：１５ＭＡＰ濃縮液：８混合生汚泥＝２：３：２となるように設定した。実施例３は、図４に示す構成のパイロットプラントが備えるＭＡＰ晶析リアクターにエアリフト循環型曝気装置を付加して脱炭酸処理を行った場合を示す。 Example 1 shows a case in which the operation was performed based on the pilot plant having the configuration shown in FIG. 3. Only Example 1 employed a digestion tank having a capacity of ３ of the digestion tank of the other comparative example 1 and the like. The sludge to be fed into the digestion tank was prepared by adding 0.2% of a flocculant per solid matter to the mixed raw sludge to triple the sludge concentration. Example 2 shows a case in which the operation was performed based on the pilot plant having the configuration shown in FIG. 4. The flow rate balance was 13 MAP desorbed sludge: 15 MAP concentrated liquid: 8 mixed raw sludge = 2: 3: 2 from various conditions. It was set to become. Example 3 shows a case where a decarboxylation treatment was performed by adding an air lift circulation type aeration apparatus to a MAP crystallization reactor provided in a pilot plant having the configuration shown in FIG.
比較例１は、図７に示す構成のパイロットプラントに基づいて運転した場合を示し、比較例２は図７に示す構成のパイロットプラントにおいて混合生汚泥の初沈汚泥と余剰汚泥の混合比を変更して運転した場合を示す。 Comparative Example 1 shows the case where the operation was performed based on the pilot plant having the configuration shown in FIG. 7, and Comparative Example 2 changed the mixing ratio between the initial settled sludge and the excess sludge of the mixed raw sludge in the pilot plant having the configuration shown in FIG. 7. This shows the case where the vehicle is driven.
運転条件の詳細を表１に示し、比較例１のリン回収率、回収リン当たりの使用薬剤コスト、プラント動力、プラント設置面積、余剰メタンガス回収量、排出固形量（脱水ケーキ重量）をそれぞれ１００とした場合の各実施例及び各比較例の比較結果を表２に示す。なお、リン回収当たりの使用薬剤コストはＭＡＰを晶析させるためのＭｇ源、ｐＨ調整剤、及び混合生汚泥を濃縮する場合にはその際に使用する凝集剤を含めたコストとした。 The details of the operating conditions are shown in Table 1, and the phosphorus recovery rate, the chemical cost per recovered phosphorus, the plant power, the plant installation area, the surplus methane gas recovery amount, and the discharged solids amount (weight of the dehydrated cake) of Comparative Example 1 are 100, respectively. Table 2 shows the comparison results of each of the examples and the comparative examples in the case of performing the above. In addition, the chemical | medical agent cost per phosphorus collection was made into the cost including the Mg source for crystallizing MAP, pH adjuster, and the coagulant used at the time of concentrating mixed sludge.
実施例１〜３のいずれも、混合生汚泥に対して嫌気性処理を行い、その後脱水処理を行った比較例１に比べて、リン回収率を高くすることができた。また、実施例１〜３のいずれも、比較例１に比べて回収したリン当たりの使用薬剤コストを低減することができた。また、排出固形物量に関しても、比較例１では排出ケーキ中に固形物として含まれていたＭＡＰ粒子を実施例１〜３では分離回収していることから大幅に削減することが可能で処分コスト軽減効果があった。 In all of Examples 1 to 3, the phosphorus recovery rate could be increased as compared with Comparative Example 1 in which the mixed raw sludge was subjected to anaerobic treatment and then dewatered. Further, all of Examples 1 to 3 were able to reduce the cost of chemicals used per phosphorus recovered compared to Comparative Example 1. Further, regarding the amount of solids discharged, the MAP particles contained in the discharged cake in Comparative Example 1 were separated and recovered in Examples 1 to 3 because the MAP particles were contained in the discharged cake. There was an effect.
さらに、実施例１では、混合生汚泥を濃縮処理した濃縮汚泥を用いて嫌気性処理を行ったため、消化槽の大きさを小さくすることができ、これによりプラント設置面積も小さくすることができた。特に消化槽が１／３となることから、該消化槽の加温処理のためのボイラー使用分の回収ＣＨ4が大幅に削減することから、発電に使用できる余剰ＣＨ4が１００→１０５に増加した。リン回収に関しては、想定どおりに消化槽内での微細ＭＡＰ率が８０％→５５％大幅に低下し、その分粗ＭＡＰ化率が上昇したことからリン回収率が増加した。消化槽に投入する混合生汚泥を３倍に濃縮するために使用した凝集剤コスト分が比較例１よりも余分にかかったが、リン回収量が１．３倍に増加したことで回収リンあたりの薬品コストとしては比較例１よりも小さくなった。 Furthermore, in Example 1, since the anaerobic treatment was performed using the concentrated sludge obtained by concentrating the mixed raw sludge, the size of the digestion tank could be reduced, thereby reducing the plant installation area. . Particularly increased from the digester becomes 1/3, since the said digestion tank heating process boilers using partial recovery CH 4 of for the is greatly reduced, the excess CH 4 is 100 → 105 that can be used for power generation did. Regarding the phosphorus recovery, the fine MAP ratio in the digestion tank was greatly reduced from 80% to 55% as expected, and the crude MAP conversion ratio was increased accordingly, so that the phosphorus recovery ratio was increased. The coagulant used for concentrating the mixed raw sludge to be fed into the digestion tank three times was more expensive than that of Comparative Example 1, but the amount of phosphorus recovered increased by 1.3 times. The chemical cost was lower than that of Comparative Example 1.
比較例２、実施例２、３は混合生汚泥の初沈汚泥と余剰汚泥の比率が８：２であり、初沈汚泥由来の有機物が多いことから、実施例１の方式を採用してしまうと混合生汚泥の濃縮処理において分離する濃縮分離水中の有機酸等の有機物からＣＨ4ガスを回収できなくなる。そのため混合生汚泥の濃縮処理は行わず、通常サイズの消化槽を用いたが、活性汚泥処理等での微生物分解処理を受けていない初沈汚泥由来の有機物が多いことから消化槽での余剰ガス回収量はやや増加した。また、理由は定かではないが、ＭＡＰ晶析においては余剰汚泥由来のリンの方が、初沈汚泥由来のリンよりもやや粗ＭＡＰ化しやすい傾向がある事から比較例１と２はプラントとしては同一のものであるが、リン回収率は比較例２の方がやや小さかった。 In Comparative Example 2, Examples 2 and 3, the ratio of the primary sludge of the mixed raw sludge to the excess sludge is 8: 2, and the amount of the organic matter derived from the primary sludge is large, so the method of Example 1 is employed. CH 4 gas cannot be recovered from organic substances such as organic acids in the concentrated separation water separated in the concentration treatment of the mixed raw sludge. For this reason, the concentrated raw sludge was not concentrated, and a normal-sized digester was used.However, since there was a large amount of organic matter derived from primary sludge that had not been subjected to microbial decomposition treatment such as activated sludge treatment, excess gas in the digester was used. Recovery volumes increased slightly. Although the reason is not clear, in Comparative Example 1 and 2 as a plant, phosphorus in excess sludge tends to be slightly coarser in MAP than in phosphorus in primary sludge in MAP crystallization. Although the same, the phosphorus recovery rate was slightly smaller in Comparative Example 2.
実施例２では、消化槽に投入される混合生汚泥から溶解性リン及び溶解性Ｍｇを大幅に軽減した後で投入していることから、消化槽内での微細ＭＡＰ生成率は８０％→４５％まで低下し、その分粗ＭＡＰとして後段で回収できたことからリン回収率は大幅に上昇した。また、回収リンあたり使用薬剤コストとしては、実施例１で使用した混合生汚泥の濃縮処理用凝集剤の使用が無かったことから実施例１と比較しても大幅に薬剤コストが軽減した。 In Example 2, since the soluble phosphorus and the soluble Mg were significantly reduced from the mixed raw sludge charged into the digester and then added, the fine MAP generation rate in the digester was 80% → 45. %, And as a result, crude MAP could be recovered in the subsequent stage, and the phosphorus recovery rate significantly increased. In addition, the cost of chemicals used per recovered phosphorus was significantly reduced as compared with Example 1 because no coagulant for concentration treatment of mixed raw sludge used in Example 1 was used.
実施例３では曝気による脱炭酸効果でｐＨ調整剤の使用量が軽減でき、リン回収率、薬品コストともに実施例２よりも改善した。実施例２，３のプラント動力、及びプラント設置面積に関しては、比較例２よりも装置点数が増えた分やや増加したものの、その差は大きくなかった。 In Example 3, the amount of the pH adjuster used could be reduced by the decarboxylation effect by aeration, and both the phosphorus recovery rate and the chemical cost were improved as compared with Example 2. Regarding the plant power and the plant installation area of Examples 2 and 3, although the number of devices was slightly increased as compared with Comparative Example 2, the differences were not large.
混合生汚泥又は濃縮分離液をＭＡＰ晶析リアクターへ供給していない比較例１、２では、ＭＡＰ晶析リアクターにおける薬剤の添加量が多くなるとともに、消化槽において回収されるＭＡＰ粒子の生成に寄与しない微細なＭＡＰ粒子が消化槽内で生成されてしまったため、リン回収率及び回収リン当たりの薬剤コストが実施例１〜３に比べて低下した。 In Comparative Examples 1 and 2, in which the mixed raw sludge or the concentrated separated liquid was not supplied to the MAP crystallization reactor, the amount of the drug added in the MAP crystallization reactor was increased, and the MAP crystallization reactor contributed to the generation of MAP particles recovered in the digestion tank. Since fine MAP particles were not generated in the digestion tank, the phosphorus recovery rate and the drug cost per recovered phosphorus were lower than those in Examples 1 to 3.
１…流入水
２…水処理系
３…汚泥処理系
４…流出水
５…初沈汚泥
６…活性汚泥混合液
７…余剰汚泥
８…混合生汚泥
９…濃縮汚泥
１０…濃縮分離水
１１…消化汚泥
１２…ＭＡＰ晶析処理水
１３…ＭＡＰ脱離汚泥
１４…ＭＡＰ濃縮液
１５…ＭＡＰ濃縮液
１６…ＭＡＰ脱離汚泥
１７…ＭＡＰ晶析処理水
２１…最初沈澱池
２２…曝気槽
２３…最終沈澱池
３１…混合槽
３２…濃縮装置
３３…消化槽
３４…ＭＡＰ晶析リアクター
３５…ＭＡＰ分離装置
３６…脱水装置
３７…ＭＡＰ分離装置
３８…物理的脱炭酸処理装置
DESCRIPTION OF SYMBOLS 1 ... Inflow water 2 ... Water treatment system 3 ... Sludge treatment system 4 ... Outflow water 5 ... Primary sludge 6 ... Activated sludge mixed liquid 7 ... Excess sludge 8 ... Mixed raw sludge 9 ... Condensed sludge 10 ... Concentrated separation water 11 ... Digestion Sludge 12: MAP crystallization treated water 13: MAP desorbed sludge 14: MAP concentrated solution 15: MAP concentrated solution 16: MAP desorbed sludge 17: MAP crystallization treated water 21 ... First settling basin 22 ... Aeration tank 23 ... Final settled Pond 31 Mixing tank 32 Concentrator 33 Digestion tank 34 MAP crystallization reactor 35 MAP separator 36 Dehydrator 37 MAP separator 38 Physical decarboxylation unit
Claims (9)
前記有機性廃水または汚泥を前記嫌気性処理した後の嫌気性処理液体と、前記嫌気性処理する前段の前記有機性廃水または汚泥に含まれる溶解性リンまたは溶解性マグネシウムとを、リン酸マグネシウムアンモニウム粒子が存在する液体内で混合し、前記混合液のｐＨを調整することによりリン酸マグネシウムアンモニウム粒子を晶析させ、該リン酸マグネシウムアンモニウム粒子を分離濃縮した後のＭＡＰ濃縮液またはＭＡＰ脱離汚泥を汚泥処理系に戻すことを特徴とする有機性廃水または汚泥の処理方法。 An organic wastewater or sludge treatment method comprising a step of performing anaerobic treatment on organic wastewater or sludge, and a step of recovering a phosphorus component in the organic wastewater or sludge in the form of magnesium ammonium phosphate particles. hand,
An anaerobic treatment liquid after the organic wastewater or sludge is subjected to the anaerobic treatment, and soluble phosphorus or soluble magnesium contained in the organic wastewater or sludge before the anaerobic treatment, magnesium magnesium phosphate MAP concentrate or MAP desorbed sludge after mixing in a liquid in which particles are present, crystallizing magnesium ammonium phosphate particles by adjusting the pH of the mixed solution, and separating and concentrating the magnesium ammonium phosphate particles. A method for treating organic wastewater or sludge, comprising returning the wastewater to a sludge treatment system.
前記濃縮汚泥に対して嫌気性処理を行い、嫌気性処理液体を得る嫌気性処理装置と、
前記濃縮分離水と前記嫌気性処理液体とを導入し、リン酸マグネシウムアンモニウム粒子が存在する液体内で前記混合液のｐＨを調整して前記リン酸マグネシウムアンモニウム粒子を晶析させるＭＡＰ晶析リアクターと、
前記ＭＡＰ晶析リアクターで得られたＭＡＰ晶析処理水から前記リン酸マグネシウムアンモニウム粒子を分離濃縮し、ＭＡＰ濃縮液及びＭＡＰ脱離汚泥を得るＭＡＰ分離装置と、
前記ＭＡＰ濃縮液を前記ＭＡＰ晶析リアクターへ返送する配管ラインと
を備えることを特徴とする有機性廃水または汚泥の処理装置。 A concentration device for separating organic wastewater or sludge into concentrated sludge and concentrated separated water,
An anaerobic treatment apparatus for performing an anaerobic treatment on the concentrated sludge to obtain an anaerobic treatment liquid,
A MAP crystallization reactor that introduces the concentrated separated water and the anaerobic treatment liquid, adjusts the pH of the mixed solution in a liquid in which magnesium ammonium phosphate particles are present, and crystallizes the magnesium ammonium phosphate particles; ,
A MAP separation device that separates and concentrates the magnesium ammonium phosphate particles from the MAP crystallization treated water obtained in the MAP crystallization reactor, and obtains a MAP concentrated solution and MAP desorbed sludge;
And a piping line for returning the MAP concentrate to the MAP crystallization reactor.
前記嫌気性処理を行う前段の前記有機性廃水または汚泥と、前記嫌気性処理後の嫌気性処理液体の少なくとも一部とを共に導入し、リン酸マグネシウムアンモニウム粒子が存在する液体内で前記混合液のｐＨを調整して前記リン酸マグネシウムアンモニウム粒子を晶析させるＭＡＰ晶析リアクターと、
前記ＭＡＰ晶析リアクターで得られたＭＡＰ晶析処理水から前記リン酸マグネシウムアンモニウム粒子を分離濃縮し、ＭＡＰ濃縮液及びＭＡＰ脱離汚泥を得るＭＡＰ分離装置と、
前記ＭＡＰ脱離汚泥を前記嫌気性処理装置へ返送する配管ラインと
を備えることを特徴とする有機性廃水または汚泥の処理装置。 An anaerobic treatment device that performs anaerobic treatment on organic wastewater or sludge;
The organic wastewater or sludge at the previous stage of performing the anaerobic treatment and at least a part of the anaerobic treatment liquid after the anaerobic treatment are introduced together, and the mixed liquid is mixed in a liquid in which magnesium ammonium phosphate particles are present. A MAP crystallization reactor that adjusts the pH of the magnesium ammonium phosphate particles to crystallize,
A MAP separation device that separates and concentrates the magnesium ammonium phosphate particles from the MAP crystallization treated water obtained in the MAP crystallization reactor, and obtains a MAP concentrated solution and MAP desorbed sludge;
A pipe line for returning the MAP desorbed sludge to the anaerobic treatment apparatus. An organic wastewater or sludge treatment apparatus.
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| JP2004000941A (en) * | 2002-04-18 | 2004-01-08 | Ebara Corp | Treatment method for organic wastewater or sludge and treatment apparatus therefor |
| JP2004008957A (en) * | 2002-06-07 | 2004-01-15 | Ebara Corp | Phosphorus and nitrogen recovery method and apparatus therefor |
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