山口県宇部市から情報発信、Infomation from Ube City, Japan



Anaerobic wastewater treatment (AnWT) – Principle, processes and applications
村上定瞭(水浄化フォーラム), Sadaaki Murakami (Water & Solutions Forum)


 2.1 特徴
 2.2 有機物の嫌気分解
 2.3 反応条件
 2.4 生化学と物質収支
 3.1 従来技術
 3.2 微生物保持と高速化技術

Table of contents

1. Introduction
2. Basics of anaerobic wastewater treatment
 2.1 Characteristics
 2.2 Anaerobic decomposition of organic substances
 2.3 Reaction conditions
 2.4 Biochemistry and mass balance
3. Anaerobic wastewater treatment technology
 3.1 Conventional technology
 3.2 Microorganism retention and high rate technology
4. Application fields

  History of Anaerobic Treatment Technology
  COD in Japan


 1900年代後半に、担体の表面/内側に微生物を保持する方法[担体固定法:anaerobic filters (AF)、rotating bed (RB) anaerobic reactor、expanded bed (EB) anaerobic reactor、fluidized bed (FB) anaerobic reactorなど]および微生物群が自己的に凝集・集塊する沈降性に優れた粒状の形成物を利用する方法[(グラニュール法:upflow anaerobic sludge blanket (UASB) reactor、expanded granular sludge bed (EGSB) anaerobic reactor、anaerobic reactor with internal circulation(IC)など)]が次々と開発され、反応槽内に微生物を高濃度に固定・保持することが可能となるとともに、装置構造や運転操作法も工夫・改善がなされ、様々な生活・産業排水へ適用されることとなった [Chernicharo, 2007; Lier, 2008]。また、(亜)熱帯地域の国々では下水などの処理施設として、経済的な嫌気性処理技術が活用され、地域の衛生・環境の改善に貢献している [Mara, 2003]。

1. Introduction

 Anaerobic wastewater treatment (AnWT) technology has been used for over 100 decades to stabilize sewage sludge, night soil and highly concentrated organic industrial wastewater. The advantages of the anaerobic treatment method over the aerobic treatment are that (1) it is energy-saving because it does not require aeration, (2) it can be expected to recover useful substances such as methane, nitrogen and phosphorus, and (3) the amount of sludge generated is small. However, the quality of the treated water does not meet the discharge criteria for public water bodies, and additional treatment is required.
 By the way, anaerobic microorganisms have a slow growth rate and require a long sludge retention time in the reaction tank. In addition, these microorganisms are inferior in coagulation/sedimentation property, and it is difficult to control the hydraulic retention time and the sludge retention time independently. If the sludge retention time can be controlled regardless of the hydraulic retention time, it is possible to maintain a high concentration of microorganisms in the reaction tank and increase the volume load of organic matter (compact) to shorten the treatment time (speed).
 In the latter half of the 1900s, a method of retaining microorganisms on the surface/inside of the carrier [carrier fixing method: anaerobic filters (AF), rotating bed (RB) anaerobic reactor, expanded bed (EB) anaerobic reactor, fluidized bed (FB) anaerobic reactor, etc.] and a method of using a granular product with excellent sedimentation properties in which microbial groups self-aggregate/agglomerate [granule method: expanded anaerobic sludge blanket (UASB) reactor, expanded granular sludge bed (EGSB) anaerobic reactor) , anaerobic reactor with internal circulation (IC), etc.] were developed one after another, and it became possible to fix and retain microorganisms in a high concentration in the reaction tank, and the device structure and operation method were devised and improved. It has been applied to various domestic and industrial wastewaters [Chernicharo, 2007; Lier, 2008]. In addition, economical anaerobic treatment technology is utilized as a treatment facility for sewage, especially in countries in the (sub)tropical region, and contributes to the improvement of local hygiene and environment [Mara, 2003].


2.1 嫌気性生物処理の特徴


2.Basics of Anaerobic Biological Treatment

2.1 Characteristics of anaerobic biological treatment

 The features of anaerobic biotreatment are summarized as follows in comparison with aerobic biotreatment.



(1) Advantages

 ① The microbial cell synthesis rate is low, and the amount of excess sludge generated is about 1/3 to 1/10 that of aerobic bacteria.
 ② Oxygen supply is not required and power consumption can be reduced to 1/3 to 1/2 compared to aerobic treatment.
 ③ Generated methane gas can be used as energy.
 ④ The pathogenic bacteria and parasite eggs die (except for single treatment by the high-rate AnWT method).



(2) Disadvantages

 ① Anaerobic bacteria have a slow growth rate and require a long sludge retention time.
 ② Methane generation is sensitive to environmental factors such as temperature
(20°C or less) and pH.
 ③ Good quality water cannot be obtained and the latter stage of treatment is required for discharge to public water areas.
 ④ Efficient treatment is difficult for wastewater with low organic matter concentration.

aerobic vs anaerobic COD balance
図1 好気・嫌気における物質変換 [Chernicharo, 2007]
Fig.1 Material conversion in aerobic and anaerobic [Chernicharo, 2007].

2.2 有機物の嫌気分解


2.2 Anaerobic decomposition of organic matter

 Anaerobic digestion is composed of sequential and parallel complex reaction processes in which facultative anaerobes (surviving under aerobic and anaerobic conditions: anoxic) and obligate anaerobes (surviving only under anaerobic conditions:
anaerobic) coexist and participate. It converts the organic substances in wastewater and waste to inorganic substances such as methane and carbon dioxide. This degradation pathway is roughly divided into three processes: (1) hydrolysis and solubilization of polymeric organic substances, (2) reduction of molecular weight and acid production (fermentation), and (3) methane production.



(1) Hydrolysis and solubilization

 Polymeric substances (mostly solid/suspended proteins/carbohydrates/lipids) become soluble amino acids/sugars/higher fatty acids by the hydrolysis reaction of extracellular secretory enzymes of microorganisms, and pass through cell walls/cell membranes. Then, it is converted into a substance that can be absorbed into cells.



(2) Lower molecular weight and acid production (fermentation)

 Amino acids, saccharides, and higher fatty acids taken into the cells of microorganisms are metabolically decomposed and converted into acetic acid, hydrogen, carbon dioxide, ammonia, and hydrogen sulfide through lower fatty acids and alcohols.



(3) Production of methane from acetic acid, hydrogen and carbon dioxide

 Methane gas is produced from acetic acid and from hydrogen and carbon dioxide. Generally, the hydrolysis reaction of (1) is slow in the anaerobic decomposition of organic substances, and this process is the rate-determining step in wastewater containing solid/suspended substances and lipids.
 In addition, since the acid production rate is higher than the methane production rate, when a readily degradable organic substance is rapidly and massively added, the organic acid accumulates due to the promotion of acid production. It is important to maintain the organic load so that it is balanced. Furthermore, since methanogens (obligate anaerobes) are easily affected by environmental conditions and inhibitors, it is important to pay attention to the control of the gas generation process in order to facilitate methane fermentation.

図2 有機性高分子物質の嫌気分解 [Gujer & Zehnder, 1983]
Fig.2 Anaerobic decomposition of organic polymer [Gujer & Zehnder, 1983].

2.3 反応条件



2.3 Reaction conditions

(1) Temperature

 In the anaerobic treatment, the temperature of the reaction tank is a very important operating factor. There are two optimum temperature conditions for anaerobic bacteria: mesophilic bacterium of 30 to 35°C and thermophilic bacterium of 50 to 60°C. Thermophilic bacteria are 25 to 50% faster than mesophilic bacteria. At temperatures below about 20°C, the methane fermentation rate decreases rapidly.



(2) pH

 The optimum pH is 5-6 for acid-producing bacteria and 6.8-7.2 for methanogenic bacteria. Methanogens are extremely pH-dependent, and their activities rapidly decrease at pH 6 and below and pH 8 and above.



(3) Nutrients

 Since anaerobic bacteria have a lower growth yield than aerobic bacteria, the required amount of nutrient salts is also small, but if they are insufficient, they are added. The COD:N:P ratio is 350:7:1 for high load operation (0.8kg to 1.2kgCOD/kgVSS/d) and 1000:7:1 for low load operation (0.5kgCOD/kgVSS/d or less). The proper N/P ratio is about 7, and the C/N ratio is at least 25.



(4) Inhibitor

 The main inhibitors for methanogens are ammonia and lower organic acids. In both cases, the free state (non-ionized nonionic body) inhibits the reaction to do.
 Lower fatty acids are products of anaerobic treatment, such as acetic acid, propionic acid, and butyric acid. Accumulation of 2,000 mg/L or more as acetic acid inhibits fermentation. It is necessary to keep the organic acid concentration/alkalinity at 0.3 to 0.4 or less as an operation index, and if it is 0.8 or more, a functional disorder will occur.
 Ammonia is likely to be liberated at high pH or high temperature, and is therefore susceptible to ammonia inhibition in these environments. Under normal operating conditions, the NH3-N concentration is 3,500 mg/L or more for mesophilic bacteria and 2,000 mg/L or more for thermophilic bacteria, which inhibits methanogenesis.



(5) Sulfur and nitrogen oxides

 Nitric acid (NO3-), nitrous acid (NO2-), sulfuric acid (SO42-), sulfurous acid (SO32-) and other inorganic oxide salts are present in large amounts, they act as electron acceptors for organic substances and nitrogen- and/or sulfur-reducing bacteria grow up, resulting in that the bacteria oxidize organic matters to produce ammonia (NH3) ano/or hydrogen sulfide (H2S) ,and that the amount of methane gas generated is reduced and also the COD removal rate also decreases.
 Hydrogen sulfide becomes an inhibitory substance for methane bacteria and causes a bad odor and corrosion of equipment materials.

2.4 生物化学と物質収支



2.4 Biochemistry and material balance

(1) Biochemistry and COD

 Because oxygen demand (CODCr) measured by potassium dichromate can decompose organic matter almost completely, CODCr (abbreviated as COD on this page) is used as an index of organic matter in anaerobic biological reactions. The COD of the organic matter CnHaOb can be calculated from the following reaction formula, assuming that it is completely chemically oxidized.

CnHaOb + (1/4)(4n+1-2b)O2→nCO2 + (a/2)H2O

 1molの有機物 CnHaObは、(1/4)(4n+1-2b)O2molesまたは8(4n+a-2b)gのO2に対応する。したがって、有機物の理論的CODTは、次式で示される。
 1 mol of organic matter CnHaOb corresponds to (1/4)(4n+1-2b)O2moles or 8(4n+a-2b)g of O2. Therefore, the theoretical CODT of organic substances is given by the following equation.

CODT = 8(4n+a-2b)/(12n+a+16b)[gCOD/gCnHaOb]

 同様にして、タンパク質など、窒素を含む有機 CnHaObNdについては、つぎのようになる。
 Similarly, for organic CnHaObNd containing nitrogen, such as proteins, it is described as follows.

CnHaObNd + (n+a/4-b/2-3d/4)O2 → nCO2 + (a/2-3d/2)H2O + dNH3
CODT = 8(4n+a-2b-3d)/(12n+a+16b+14d)[gCOD/gCnHaObNd]



(2) Biochemistry and biogas generation

 When the organic matter CnHaObNd, which is completely biodegradable by anaerobic organisms, shall be converted to CH4, CO2 and NH3 and the sludge generation is not considered, the theoretical generation amounts of total biogas VT and methane gas VCH4 can be estimated from the following reaction equation.

CnHaObNd + (n-a/4-b/2+3d/4)H2O →
(n/2+a/8-b/4-3d/8)CH4 + (n/2-a/8+b/4+3d/8)CO2+dNH3
VT ={(n/2+a/8-b/4-3d/8) + (n/2-a/8+b/4+3d/8)}RT/p[L/gCnHaObNd]
VCH4 = (n/2+a/8-b/4-3d/8)/(12n+a+16b+14d)RT/p[L/gCnHaObNd]

 ここで、R = 気体定数[0.08206atm・L/mole/K、T = 絶対温度[K (= 273+t)、t=反応槽内の操作温度℃]、p = 大気圧[atm]。
 Where R = gas constant [0.08206atm・L/mole/K, T = absolute temperature [K (= 273+t), t = operating temperature in reactor ℃], p = atmospheric pressure [atm].
 As specific biogas generation amounts, Table 1 shows examples of measured values ​​for each substrate, and Table 2 shows measured values ​​for each solid waste.

表1 基質1g当りのガス発生量 [片岡, 2010]
Table 1 Amount of gas generated per 1g of substrate [Kataoka, 2010].
gas per 1g_substrate

表2 固形性有機廃棄物のメタン発酵でのガス発生量[国土交通省、2003]
Table 2 Amount of gas generated during methane fermentation of solid organic waste [Ministry of Land, Infrastructure, Transport and Tourism, 2003].
gas from wastes




(3) Mass balance by COC

1) COC balance in the decomposition process

 An outline of the COD balance that flows into the anaerobic biodegradation process is as follows.
 ① The pollutant CODinf in the inflow water is divided into degradable components CODbd and non-degradable components CODrec. ② CODbd is taken up by the microbial body, which is converted into two fractions: CODcel is a cell synthetic component of the microorganism and CODint is metabolite component released to the outside of the cell (mainly lower fatty acids). ③ A part of CODint becomes methane production CODCH4. ④ CODcel and CODCH 4 are the component CODrem those are removed from the inflow water, and CODint that is not converted to methane within the HRT becomes CODun, which is a component released to the outside of the system together with CODrec.

図3 嫌気性分解プロセスにおけるCOD収支 [Chernicharo, 2007]
Fig.3 COD balance in anaerobic decomposition process [Chernicharo, 2007].


 一般的に生活・産業に伴う排水中の汚濁物質には固形成分が多く含まれており、加えて生物分解の過程で微生物の細胞合成が行われる。流入水中CODinfは、水質分析において一般的に3つのタイプに分類される [Chernicharo, 2007]。
 ① ろ過性COD(CODfilt)は、排水を孔径(1.5μm*)のろ紙を通過したろ液中のCOD成分である。または、遠心分離(5,000rpmで5分間)したときの上澄み液中のCOD成分である。CODfilには、溶解成分CODsolとコロイド状成分CODcolを含み、後者はろ紙では分離できない。
 ② 粒子状COD(CODpart)は粒子状(懸濁状)有機物質のCODでろ紙上に残留する成分で、流入CODinfからCODfilを除いた成分に対応する。
 *)日本での浮遊物質(懸濁物質)SS [昭和46年環境庁告示第59号付表9]は、網目2mmのふるいを通過した試料を孔径1μmのガラス繊維ろ紙でろ過したときに、ろ紙上に補足される物質で、水洗後、105~110℃で2時間加熱乾燥し、デシケーター中で放冷後、質量を測定する。また、CODSS(またはCODpart)測定におけるろ紙の孔径は、実験者・研究者によって異なるので、孔径を明記することに留意する。

2) COD component of inflow water

 In general, pollutants in wastewater associated with daily life and industry contain a large amount of solid components, and in addition, microbial cell synthesis is performed during the process of biodegradation. CODinf in the influent is generally classified into three types in water quality analysis [Chernicharo, 2007].
 ① Filterable COD (CODfilt) is a COD component in the filtrate obtained by passing wastewater through a filter paper having a pore size (1.5 μm*). Alternatively, it is the COD component in the supernatant after centrifugation (5,000 rpm for 5 minutes). CODfil contains dissolved component CODsol and colloidal component CODcol, which cannot be separated by filter paper.
 ② Particulate COD (CODpart) is a COD of a particulate (suspended) organic substance that remains on the filter paper and corresponds to the component obtained by removing CODfil from the inflow CODinf.
 *) Suspended solids (suspended solids) in Japan [Showa 46, Environment Agency Notification No. 59, Appendix 9] is a filter paper when a sample that has passed through a 2 mm mesh sieve is filtered through glass fiber filter paper with a pore size of 1 μm. After washing with water using the above-supplemented substance, heat-dry at 105-110°C for 2 hours, allow to cool in a desiccator, and measure the mass. Also, note that the pore size of filter paper in CODSS (or CODpart) measurement differs depending on the experimenter/researcher, so be careful to specify the pore size.


 排水処理の適正な運転・管理において、反応系の物質収支を測定することは極めて重要である [Lier & et al., 2008]。嫌気性生物処理では、前述したように管理指標としてCODが用いられる。図4に示すように、流入水CODinfについて、次の関係式が成立する。

3) COD balance of inflow and outflow

 It is extremely important to measure the mass balance of the reaction system in the proper operation and management of wastewater treatment [Lier & et al., 2008]. In the treatment of anaerobic organisms, COD is used as a management index as described above. As shown in Fig.4, the following relational expression holds for the inflow CODinf.

CODinf = CODeff + CODgas + CODsludge

 CODsludge corresponds to excess sludge drawn out of the reaction system. The effluent CODeff contains COD components such as dissolved CH4 and H2S in addition to the persistent substances, reaction intermediates and effluent sludge described in 1). When a large amount of electron acceptors such as SO42- and NO3 is contained, the inflowing organic COD is converted into inorganic COD, and the amount of generated gas is reduced. Further, when the concentration of inflowing organic matter is low, the proportion of dissolved CH4 and CO2 is high, and the proportion of the generated gas amount is reduced.

図4 嫌気性反応槽におけるCOD収支
Fig.4 COD balance in anaerobic reactor.


 有機物の嫌気性分解とメタンガス発生には、多様な微生物が競争・共生的に関わっている。この複雑な生態系と分解機構を明らかにするため、分子生物学的手法が用いられている [原田・他, 2004]。
 分子マーカーとして遺伝子が利用され、16S rRNA遺伝子 [Olsen & et al., 1986] は様々な分野で広く用いられている。また、DGGE(denaturing gradient gel electrophoresis)法 [Muyzer & et al., 1993]、T-RELF(terminal-restriction length polymorphisms)法 [Liu & et al., 1997]、FISH(fluorescence in situ hybridization)法 [Delong & et al., 1989; Amann & et al., 1990] などの技術も開発され、微生物の新しい知見が得られるようになった。
 遺伝子解析に加え、DNAプローブを用いたin situ hybridization法による検出や定量も進められてきた。特に、グラニュール汚泥は球状の生物膜という特異な構造を有しており、薄片断片化し、FISH法と共集点レーザー走査顕微鏡を用いることで、特定の微生物群の空間分布の把握が可能となった [Sekiguchi, 1999]。
 微生物検査[大楠,2012]には、①顕微鏡検査(電子顕微鏡を含む)、②培養検査、③抗原検査、④薬剤感受性試験に加えて、⑤遺伝子検査や⑥質量分析検査などがある。特に、質量分析検査は遺伝子ではなく、例えば、MALDI-TOF MS(Matrix Assisted Laser Desorption/Ionization – Time of Flight Mass Spectrometry)、資料中のタンパク質成分をイオン化(2002年ノーベル賞を受賞した田中耕一博士が発明)して、その質量の違いにより分析するものである。これらの検査は自動化・機器化(キットを含む)されるとともに、データベースも刻々と蓄積されている。

(4) Analysis of microbial community

 Various microorganisms are competing and symbiotically involved in the anaerobic decomposition of organic substances and the generation of methane gas. Molecular biology techniques have been used to clarify this complex ecosystem and degradation mechanism [Harada et al., 2004].
 Genes are used as molecular markers, and the 16S rRNA gene [Olsen & et al., 1986] is widely used in various fields. In addition, techniques such as the methods, DGGE (denaturing gradient gel electrophoresis) method [Muyzer & et al., 1993], T-RELF (terminal-restriction length polymorphisms) method [Liu & et al., 1997], and FISH (fluorescence in situ hybridization) [Delong & et al., 1989; Amann & et al., 1990], have also been developed, and new knowledge of microorganisms has been obtained.
 Methane fermentation consists of a wide variety of microorganisms that span both archaea (bacteria) and bacterial (bacteria) domains, and genetic analyses have revealed that there are a large number of highly homologous to known microorganisms, those that have not been artificially cultivated so far, or difficult-to-cultivate microorganisms (Kamagata, 2007).
 In addition to gene analysis, detection and quantification by the in situ hybridization method using a DNA probe have been advanced. In particular, granule sludge has a peculiar structure of spherical biofilm, and it is possible to grasp the spatial distribution of a specific microbial group by fragmenting thin pieces and using the FISH method and the co-focusing laser scanning microscope [Sekiguchi, 1999].
 Microbial tests [Okusu, 2012] include ① microscopy (including electron microscopy), ② culture testing, ③ antigen testing, ④ drug susceptibility testing, as well as ⑤ genetic testing and ⑥ mass spectrometry testing. In particular, mass spectrometry is not a gene, but for example, MALDI-TOF MS (Matrix Assisted Laser Desorption/Ionization – Time of Flight Mass Spectrometry), ionization of protein components in materials (invented by Dr. Koichi Tanaka who won the 2002 Nobel Prize), and analyze by the difference in the mass. These tests are automated and instrumented (including kits), and a database is being accumulated every moment.
 In the future, we can expect further progress in research and technology development and design, operation, and management in the wastewater treatment field by accumulating various knowledge related to microorganisms that purify pollutants by utilizing research and technology in other fields.


3.1 従来技術

(1)嫌気性池(anaerobic pond)

 安定化池法[Mara、2003]は、その主な除去対象により、①嫌気性菌により有機物を除去する嫌気性池(anaerobic pond)、②藻類の光合成による酸素発生と水表面からの空気中の酸素補給による好気性微生物と底面・底泥中の嫌気性菌による有機物除去する通性池(facultative pond)、および③病原菌を除去する熟成池(mauration pond)の3つに大別される。上記池の単独または組合わせ、あるいは、他法との組合わせによって排水処理が実施されている。同じタイプの安定化池であっても、地域や利用目的によって、設計・運転・管理条件が大きく異なるので留意する必要がある。

3. Anaerobic biological treatment technology

3.1 Conventional technology

(1) Anaerobic pond

 Stabilization pond method [Mara, 2003] mainly consists of ① an anaerobic pond that removes organic matter by anaerobic bacteria, ② oxygen generation by photosynthesis of algae and air from the water surface. There are three major categories: facultative ponds that remove aerobic microorganisms due to supplemental oxygen and anaerobic bacteria in the bottom/bottom mud, and ③ mauration ponds that remove pathogens. Wastewater treatment is carried out by the above ponds alone or in combination, or in combination with other methods. It is necessary to keep in mind that even the same type of stabilization pond has large differences in design, operation, and management conditions depending on the area and purpose of use.
 Usually, it is often used as the first stage of the combination of the above ponds ① to ③. Anaerobic ponds are deep, large (generally at least 2-3 m, 2-5 m) large reservoirs intended for anaerobic microbial degradation and sedimentation. The number of retention days varies greatly depending on the type of wastewater source, the concentration of organic substances and temperature, the presence or absence of post-treatment, and the reuse of treated water. In the primary treatment of domestic wastewater, the operation period is 1 to 10 days. Since wastewater including human waste often contains pathogenic bacteria, it is necessary to operate for a long period of time or disinfect by aging ponds, etc., so care must be taken in irrigation use and discharge to public water areas. It is necessary to remove the sludge that has settled and accumulated, and even if the removed sludge is sprayed on farmland, there is no odor problem. With proper design and proper inflow of sewage, sludge extraction is not very frequent (every few years), but if too much sludge accumulates, normal purification cannot be achieved.
 For the pond, it is necessary to take measures such as impermeable water to prevent groundwater pollution, embankment to prevent inflow of drift water around the pond, and installation of safety fences to prevent accidents. There are problems such as foul odors and generation of insects, so it is necessary to be careful when setting the location.

(2)嫌気消化(anaerobic digesters)

 腐敗槽(spectic tank)は構造が簡単で電力が不要であり、各家庭や下水システムのない小さな集落からの生活排水の一次処理法として、今日においても、世界各地(特に電力供給のない、または、少ない地域)で広く利用されている。

(2) Anaerobic digesters

 Anaerobic digestion of sewage sludge and night urine can be divided into three components: desorbed liquid, digested sludge, and digested gas. The digestion tanks found in the early stages (a septic tank, a travis tank, and an Imhoff tank: Fig. 5a-c) are single tanks that combine digestion and precipitation, but after that, heating and stirring (by digestion gas and mechanical agitation), 2-tank system, returning separated digested sludge, etc., to improve the efficiency of treatment.
 Spectral tanks have a simple structure and do not require electricity, and as a primary treatment method for domestic wastewater from individual households and small settlements without sewage systems, they are still used today in many parts of the world (especially when there is no electricity supply or in a small ruaral area).

septic tank
図5a 腐敗槽
Fig.5a Septic tank.

travis tank
図5b トラビス槽
Fig.5b Travis tank.

imhoff tank
図5c イムホフ槽
Fig.5c Imhoff tank.
1)標準消化槽(conventional digester)


1) Standard digester

 Fill the sealed tank with seed sludge such as digested sludge, and while heating to 30-37℃, add sewage sludge and night urine anti-continuously and treat with HRT for 20-30 days. It takes 60 to 70 days to digest at room temperature.
 Generally, the digestion tanks are arranged in two stages in series, and the first tank is agitated by blowing in the digestion gas, and 0.4 to 0.5 m3 of digestion gas is generated per 1 kg of organic matter input. The second tank completes the digestion and performs solid-liquid separation, and the gas generation amount is about 1/20 of the first tank. The organic matter load in sludge digestion is 1.5 kg-VS/m3/ at 30℃. With high temperature digestion (50-60°C), the digestion days can be shortened to 10-15 days.

2)高率消化槽(high-rate anaerobic digester)


2) High-rate anaerobic digester

 For high-rate digestion, HRT can be shortened to about 6 to 8.7 days by continuously stirring the mixture in the digester tank by digestion gas stirring or mechanical stirring, and the organic load can be increased to 3 to 5 kg-VSS/m3/d. To be continuous agitation, which has a great effect on, ensures (a) uniform temperature inside the tank, (b) sufficient mixing of input substrate and digested sludge, (c) prevention of scum, and (e) prevention of localized high concentration area due to short-circuit flow.

3)嫌気性接触法(anaerobic contact process)


3) Anaerobic contact process

 This is a method in which the digested sludge recovered by sedimentation of the digested effluent is mixed with the influent and returned to the digestion tank, and the activated sludge method is applied to anaerobic treatment.
 This makes it possible to maintain a high bacterial cell concentration in the digestion tank and shorten HRT. On the other hand, it is necessary to consider that methanogens do not form flocs and digested sludge has poor sedimentation properties, making sludge separation difficult and easy to flow out of the system. This method is suitable for high-concentration organic wastewater that has a high load in aerobic treatment.

con digestion
図6a 標準消化槽
Fig.6a Standard digester.
high-rate digestion
図6b 高率消化槽
Fig.6b High rate digestion tank.
contact digestion
図6c 嫌気性接触法
Fig.6c Anaerobic contact method.

3.2 微生物保持と高速化技術


3.2 Microorganism retention and rate-up technology

 As a method of controlling the sludge retention time regardless of the hydraulic retention time, maintaining a high concentration of microorganisms in the reaction tank and increasing the volume load of organic substances to shorten the treatment time, that is sludge immobilization in the reactor which can be roughly divided into the use of carrier or granule formation.

(1)担体固定法(attached bacterial processes)


(1) Attached bacterial processes

 In the treatment of anaerobic organisms, it is necessary to maintain a high concentration of methanogens having a low specific growth rate in the reaction tank in order to ensure stable treatment performance and high load treatment. Therefore, a high-load type anaerobic treatment method called a microorganism immobilization method has been put to practical use mainly in the industrial wastewater field.

1)固定床(fixed bed anaeroic reactor)


1) fixed bed anaeroic reactor

 The inside of the sealed reaction tank is filled with a carrier such as plastic or crushed stone, and a biofilm of anaerobic bacteria is attached to and proliferated on the surface of the carrier, and the treatment is performed by contacting with waste water.
 There are various methods depending on shape and size of the carrier, and flow direction of the water (upward or downward) through the filler. On the other hand, there is a problem that the actual volume of the reaction tank is decreased by filling the carrier, and the reaction tank is clogged or foamed due to crystallization of suspended matter in the input drainage or crystallization of inorganic substances on the carrier surface.

2)流動床(expanded/fluidised bed reactor)


2) Fluidized bed (expanded/fluidised bed reactor)

 A granular adhering carrier such as sand, anthracite, and lightweight aggregate having a particle size of 0.2 to 1.0 mm is suspended in a fluidized state, and anaerobic bacteria adhere to and grow on the surface of the carrier. In the fluidized bed, there is no problem of clogging, the contact efficiency with waste water is high, and the substrate can be decomposed to a low concentration. On the other hand, scale-up is relatively difficult, and there are problems such as power cost for carrier flow, separation of biofilm due to friction between particles, and carrier outflow. Further, it is difficult to maintain the flow condition for uniformly suspending the carrier in the reaction tank.

anaerobic filter
図7a 嫌気性固定床法
Fig.7a Anaerobic fixed bed method.
fluidised bed
図7b 嫌気性流動床法
Fig.7b Anaerobic fluidized bed method.


1)UASB(Upflow Anaerobic Sludge Bed)

 凝集・集塊機能を有する粒径0.5~2.0mm程度の沈降性の優れたグラニュール(粒状)を形成した嫌気性菌汚泥を反応槽に保持する方法である。高負荷処理が可能で汚泥層の閉塞も起こらないことから、中・高濃度排水処理法とし普及している。排水は底部から投入され、汚泥層を上昇する過程でグラニュールと接触して有機物が分解される。これを上向流嫌気性汚泥床(UASB:Up-flow Anaerobic Sludge Blanket)法という。
 UASB反応層の構造は、反応層底部に原水供給装置、上部に気液固分離装置(GLSS:Gass-Liguid-Solid Separator)を設置している。排水を反応層底部から均一に流入させる。一般的には、流入水の上昇速度は最大5m/h、容積負荷最大15kg/m3/dで運転される。

(2) Granule method

1) UASB (Upflow Anaerobic Sludge Bed)

 This is a method of holding anaerobic bacterial sludge in the reaction tank, which has granules (granulate) having a particle size of 0.5 to 2.0 mm and having a coagulation/agglomeration function and having excellent sedimentation properties. It is widely used as a medium/high-concentration wastewater treatment method because it enables high-load treatment and does not cause clogging of the sludge layer. Wastewater is introduced from the bottom, and in the process of rising in the sludge layer, it contacts the granules to decompose organic matter. This is called the Up-flow Anaerobic Sludge Blanket (UASB) method.
 As for the structure of the UASB reaction layer, a raw water supply device is installed at the bottom of the reaction layer and a gas-liquid solid separation device (GLSS: Gass-Liguid-Solid Separator) is installed at the top. The waste water is allowed to flow evenly from the bottom of the reaction layer. Generally, the rising speed of the inflow water is 5 m/h at maximum and the volume load is 15 kg/m3/d at maximum.

2)EGSB(Expanded Granular Sludge Bed

 UASB法の高負荷改良型として、膨張汚泥床(EGSB:Expanded Granular Sludge Bed)法がある。流入水を高い上昇速度(5~10m/h)で運転しグラニュール床を膨張させ、流入水とグラニュールの接触効率を改善し、処理効率を増加している。

2) EGSB (Expanded Granular Sludge Bed

 There is an expanded sludge bed (EGSB) method as a high load improvement type of the UASB method. The inflow water is operated at a high rising speed (5 to 10 m/h) to expand the granule bed, improving the contact efficiency between the inflow water and the granule and increasing the treatment efficiency.
 Even with the normal UASB method, high load processing capacity (30-40kgCOD/m3/d) more than 2-3 times is possible. In the EGSB method, the ratio of the height/cross-sectional area of ​​the reaction tank is set large. There is also a system in which a part of the outflow water is returned to the inflow water and circulated in the reaction tank, and a system in which GLSS is installed in multiple stages for stable solid-liquid separation.

3)IC(Internal Circulation Reactor)

 以上のような方法により、UASBよりも高負荷・高速(35~50kgCOD/m3/h、HRT < 2.5h)に有機物の嫌気性分解が可能となる。IC反応槽は、懸濁物質を含む高濃度の有機性産業排水へ普及している。

3) IC (Internal Circulation Reactor)

 The IC reaction tank is composed of two vertically connected reaction sections having a UASB structure connected vertically.
 Most of the organic matter in the reduced water introduced from the bottom of the reaction tank is converted into biogas in the lower reaction section. This biogas is collected in a separator. This separator and the gas-liquid separator of the upper reactor are connected by a pipe (a rising pipe), and the mixed liquid also rises due to the gas lift effect. At the bottom of the gas-liquid separator, a descending pipe is connected to the lower reactor so that the gas is discharged out of the system and the mixed liquid is returned to the lower reactor. In this way, the mixed solution is naturally circulated inside the reaction tank.
 The treatment liquid in the lower reaction section is introduced into the upper reaction section, the remaining decomposable organic substances are gasified, and the treatment solution is discharged out of the system. The rising speed of the mixed solution in this reaction section is set to 2 to 10 m/h.
 By the above method, anaerobic decomposition of organic substances can be performed at higher load and speed (35 to 50 kg COD/m3/h, HRT < 2.5h) than UASB. IC reactors are popular for high-concentration organic industrial wastewater containing suspended solids.

UASB reactor
図8a UASB法
Fig.8a UASB method.
EGSB reactor_1
図8b EGSB法
Fig.8b EGSB method.
EGSB reactor_2
図8c 多段式EGSB法
Fig.8c Multi-stage EGSB method.
図8d IC法
Fig.8d IC method.

 一方、Metanosarcina属のメタン生成菌の汚泥の粒径は概ね0.5mm以下と小さく流出しやすくなり、処理水質も悪化することから、このタイプのグラニュール汚泥の異常繁殖は望ましくない。傾向として、高酢酸濃度下でMetanosarcina属メタン生成菌が優先となることが多い(詳しくは、文献[例えば、Lier, 2008, pp.408-409や片岡,2010など]を参照)。

4) Characteristics and operation of granule sludge

 In the UASB method, it is of utmost importance to maintain granule sludge in the tank and continuously grow it. Therefore, it is necessary to create an environment in which the methanogens can grow preferentially in the UASB treatment tank, and in particular, the methanogens of the genus Metanosaeta that form the skeleton of granule sludge and grow with bromine acetate as the only substrate. Proliferation is essential. Normal granule sludge has a structure in which filamentous or rod-shaped Methanogens of the genus Metanosaeta are intertwined.
 On the other hand, the sludge size of Methanogens of the genus Metanosarcina is as small as 0.5 mm or less, which facilitates the outflow and deteriorates the quality of treated water. Therefore, abnormal growth of this type of granule sludge is not desirable. As a tendency, Metanosarcina sp. methanogens have a high priority under high acetic acid concentration (for details, see the literature [eg, Lier, 2008, pp.408-409 and Kataoka, 2010]).
 It is necessary to pay attention to the behavior of suspended particles in raw water in the production and retention of granule sludge. If the SS component adheres to the granulated sludge or remains/accumulates in the reaction tank, the treatment performance will decrease. Also, when granulated sludge is formed so as to include SS components, if this is organic SS, this SS component gradually solubilizes and decomposes over time to form voids, where gas accumulates. It causes the floating of granule sludge. It is necessary to take measures to remove SS in raw water before the UASB.
 In order to create an environment in which methanogenic bacteria can preferentially grow in the UASB reaction tank, install an acid generation tank in front of the UASB reaction tank to prevent the substrate of acid generation bacteria from flowing directly into the UASB reaction tank. Thus, there is also a method of limiting the growth amount of acid-producing bacteria. In addition, by circulating UASB-treated water to the acid production tank, continuous seeding of acid-producing bacteria is performed, pH drop in the acid-producing tank is prevented, and inhibition of methanogenic bacteria by lower fatty acids is mitigated. be able to.

写真1a 室内でのUASB実験の様子
Photo 1a Indoor UASB experiment.
写真1b 屋外でのUASB実証実験の様子
Photo 1b Outdoor UASB demonstration test.
写真1 都市下水の混合汚泥を亜臨界水で加水分解・低分子化した可溶化液からのUASBによるエネルギー回収
Photo 1 UASB energy recovery from solubilized liquid obtained by hydrolyzing and reducing the molecular weight of mixed sludge from municipal sewage with subcritical water.
写真2a グラニュール全景; ×40
Photo 2a Overall view of granules; ×40.
写真2b グラニュール表面; ×5,000
Photo 2b Granule surface; ×5,000.
写真2c グラニュール断面; ×5,000
Photo 2c Granule cross section; ×5,000.
写真2 上記UASB実験(写真1)で用いた代表的なグラニュール(2-5mm)の電子顕微鏡写真
Photo 2 Electron micrograph of a typical granule (2-5mm) used in the above UASB experiment (Photo 1).



4. Application fields

 Anaerobic digestion is widely used for the treatment of solid organic waste such as agricultural waste, animal manure, sewage sludge, and municipal waste. In addition, the anaerobic digestion method is used for wastewater treatment from agricultural and livestock industries, food and beverage factories (Table 3) in both developed and developing countries. As for domestic wastewater, the use of anaerobic treatment technology, especially UASB type reactors, is steadily increasing in tropical and subtropical regions.
 Specific examples of wastewater treatment in various fields of life and industry are introduced in detail on another page.

表3 嫌気性処理の主な産業排水への応用
Table 3 Application of anaerobic treatment to main industrial wastewater.
anaerobic appl_food


 嫌気性処理は、19世紀末から20世紀初頭にヨーロッパで始まり、1950年代には加温や機械式撹拌などの処理方式が開発され、国内でも下水汚泥やし尿処理での汚泥減量化・安定化を目的とした嫌気性消化法が普及した。1980年代になると微生物固定化方式による高負荷型嫌気性処理法が産業排水処理分野を中心に普及した。そして現在、低酸素社会に向けた未利用資源の活用技術として、廃棄物系バイオマス向け嫌気性処理法が大きく脚光を浴びている。[片岡, 2010]

History of anaerobic treatment technology

 Anaerobic biological treatment is a biological treatment method that decomposes organic matter into methane gas and carbon dioxide by the metabolic action of anaerobic bacteria that grow in an anaerobic environment without oxygen.
 Anaerobic treatment began in Europe from the end of the 19th century to the beginning of the 20th century, and treatment methods such as heating and mechanical stirring were developed in the 1950s to reduce and stabilize sludge in sewage sludge and human waste treatment in Japan. The targeted anaerobic digestion method became popular. In the 1980s, the high-load anaerobic treatment method using the microorganism immobilization method became popular mainly in the industrial wastewater treatment field. At present, an anaerobic treatment method for waste biomass is in the spotlight as a utilization technology of unused resources for a low oxygen society. [Kataoka, 2010]



 1862年フランスの細菌学者Louis Pasteurは、乳酸発酵・アルコール発酵の研究から、酸素存在下で生活する生物を好気性(aerobic)生物、無酸素状態で生活できる生物を嫌気性(anaerobic)生物と呼び、識別するようになった。
 嫌気性処理法は、1875年フランスのLouis MourasのAutomatic Scavenger(自動清浄機)が始まりとされる。Louis Mourasは、し尿の固形分が汚水溜めの中で液化・溶解することを見つけ、汚水溜めを密封して、液化分を放流する管を取り付けた。1895年イギリスのDonald Cameronは、嫌気性菌の働きを利用したSeptic Tank(腐敗槽)を開発した。これは、トラップ付きの流入口と出口を備え、両方が下水の水面下に挿入されていることにより、水面上に形成されるスカム槽の破壊を防ぐ浅い槽で、濃縮汚泥は汚泥溜めに受け入れた。
 1903年イギリスのWilliam Travisが開発したTravis Tankがハンプトン市に建設され、1906年ドイツのKarl Imhoffが開発したImhoff Tankがエムッシャーで稼働した。これらは二階槽と称され、単層で下水と汚泥を沈降分離して汚泥消化(嫌気性消化)をする。これらの嫌気性処理は、家庭下水法として普及し始めたが、1913年ArdernとLockettが開発した活性汚泥法の台頭によって家庭下水での適用は次第に少なくなり、下水汚泥の減量化・安定化を目的とした嫌気性消化法として展開されていった。

(1) Start of anaerobic treatment

1) Europe

 In Europe in the 14th to 17th centuries, many residents were concentrated in the narrow land surrounded by the city walls, sludge treatment was left unclean, and epidemics were frequently attacked. In 1842 in England, the Public Health Law and the River Pollution Control Law were enacted, and the modern public health system, sewage disposal, and environmental improvement such as water and sewerage began.
 1862, French bacteriologist Louis Pasteur called and came to identify anaerobic organisms living in the presence of oxygen as aerobic organisms and anaerobic organisms living in the presence of oxygen from the study of lactic acid fermentation and alcoholic fermentation.
 The anaerobic treatment method is said to be started in 1875 by Louis Mouras’s Automatic Scavenger in France. Louis Mouras found that the solids of human waste liquefied and dissolved in the sump, sealed the sump, and installed a tube to drain the liquefaction. 1895, Donald Cameron of the United Kingdom developed the Septic Tank that utilizes the action of anaerobic bacteria. This is a shallow tank with an inlet and an outlet with traps, both of which are inserted below the surface of the sewage to prevent destruction of the scum tank formed on the surface of the water.
 It was Travis Tank developed by William Travis in England in 1903 was built in Hampton City, and Imhoff Tank developed by Karl Imhoff in Germany in 1906 started operation in Emscher. These are called the second-floor tanks, and sewage and sludge are settled and separated in a single layer for sludge digestion (anaerobic digestion). These anaerobic treatments have started to spread as a domestic sewage method, but with the rise of Activated Sludge method developed by Ardern and Lockett in 1913, these applications in domestic sewage gradually decreased, and these are developed as an anaerobic digestion method for the purpose of reducing and stabilizing sewage sludge.


 さて本論に戻ると、明治初期のコレラなど伝染病流行で、長與専齋(ながよせんさい、1875年内務省衛生局初代局長)は衛生工事を推進し、公衆衛生思想が普及し始めた。そして、中島鋭治(東京大学教授、東京市技師長)が1901年8月~1802年欧米各都市の上下水道や土木事業を調査し、前述したSeptic Tank(腐敗槽)の技術が日本に伝わった。

2) Japan

 In Japan, there is a custom of pursuing cleanliness due to the influence of Buddhism, and waste treatment is also a harvesting type, and as a fertilizer for farmers, personal hygiene was superior to other countries.
 By the way, as an aside, when the editor of this site was young(Showa 20s), in the home twon, there was a urine stabilizing tank beside each farmland, which was aged and used as a fertilizer. In addition, food waste was composted in one corner of the barn and used as fertilizer for farmland and paddy field. The household wastewater flowed into a sedimentation tank (retention days: about 2 to 3 days), and the solid content was removed, and the supernatant liquid was discharged into a stream flowing beside our house. Small fish (such as crucian carp, (rose) locust, goli, and cormorant loach), kawanina, and clams inhabited the stream. I remember that in the summer, many fireflies danced in the stream and flew not only into the garden but also into the house. After those days, with the spread of chemical fertilizers and the improvement of living standards (changes in the properties of miscellaneous wastewater), the water quality of streams and rivers deteriorated, and such a landscape gradually disappeared from many places in japan.
 Now, returning to this article, due to the epidemics such as cholera in the early Meiji era, Nagayo Sensai (1875, the first director of the Ministry of Home Affairs, Ministry of Internal Affairs) promoted hygiene work, and public health thought began to spread. Then, Eiji Nakajima (Professor at the University of Tokyo, Chief Engineer of Tokyo City) investigated the water supply and sewerage and civil engineering projects in the cities of Europe and America from August 1901 to 1802, and the technology of the Septic Tank described above was introduced to Japan.
 In October 1930, Atsaburo Ikeda, Kiyoshi Sugito (later Mayor of Nagoya), and others started sewage treatment by the activated sludge process at the Atsuta Sewage Treatment Plant in Nagoya, and then in March 1932, Nagoya Practical operation of anaerobic sludge digestion started at the city’s Tenhaku sludge treatment plant. The domestic anaerobic treatment technology that started in this way is being developed in fields such as sewage sludge treatment, human waste treatment, and industrial wastewater treatment.




(2) Development of anaerobic digestion technology

1) Progress in anaerobic digestion technology

 By anaerobically digesting sewage sludge and human waste, it can be separated into three components: desorbed liquid, digested sludge, and digested gas. And energy recovery can be achieved.
 Experiments revealed that 15-20% of sludge can be decomposed by anaerobic digestion at the Sunray Treatment Plant in Birmingham in 1908. It became clear that even the possibility of using biogas for power generation was recognized. By the early 1930s, Fair and Moor showed that there were two optimum temperature regions, medium temperature digestion (28-33°C) and high temperature digestion (55-60°C). Now, the anaerobic digestion method of today is reached (Fig.6a-6c).
 In Japan, in particular, the anaerobic digestion of human waste treatment rapidly spread after 1956, and many facilities were constructed as the mainstream until around 1975, accounting for 65% of the total number of facilities and 70% of the treatment capacity. As for human waste treatment, in 1975, the rise of anaerobic digestion facilities rapidly decreased due to the rise of biological denitrification.


 嫌気性生物処理では、安定な処理性能の確保と高負荷処理のため、比増殖速度の小さいメタン生成菌を反応槽内に高濃度に保持する必要がある。そのため、3.2 微生物保持と高速化技術に記載している微生物固定化方式と呼ばれる高負荷型嫌気性処理法が産業排水分野を中心に実用化されている。

2) Immobilization and speedup of anaerobic bacteria

 In the treatment of anaerobic organisms, it is necessary to maintain a high concentration of methanogens having a low specific growth rate in the reaction tank in order to ensure stable treatment performance and high load treatment. Therefore, the high-load anaerobic treatment method called the microorganism immobilization method described in 3.2 Microorganism retention and rate-up technology has been put to practical use mainly in the industrial wastewater field.



COD in Japan

 Oxidizing agents used in Japanese environmental standards, etc. are considered to be alternative indicators of BOD, which takes a long time to measure. The manganate method (CODMn) is adopted.
 On the other hand, as an estimate of the total amount of organic matter, there is CODCr by potassium dichromate, which is a strong oxidant (in the past, it was called potassium dichromate).
 The adoption of CODMn in Japan has the background that non-biodegradable organic substances are not causative agents of the environmental problem of “oxygen consumption” and are therefore not subject to environmental regulations including environmental standards. In addition, it was difficult to adopt the measurement method using hexavalent chromium (potassium dichromate is one of them) in the presence of hexavalent chromium pollution as a typical environmental problem and pollution problem. The reason is.
 As described above, CODMn has various interpretations and evaluations, but especially between CODMn and long-term BOD (for example, BOD20), there is a considerable difference in the measured value depending on the substance in the water and the substance composition. Sometimes, there are times when questions are raised about its alternative index nature.


 1) 大楠 清文, 2012: 臨床微生物検査の今後の展望-三大技術革新と患者診療への貢献-, Animus, No.73, pp.14-21.
 2) 片岡 直明, 2010: 嫌気性生物処理技術の特徴と発展の流れ,エバラ時報 No.229, pp.27-38.
 3) 鎌形 洋一, 2007: 難培養微生物とは何か?, Journal of Environmental Biotechnology, Vol.7, No.2, pp.69-73.
 4) 国土交通省, 2003: バイオソリッド利活用基本計画策定マニュアル(案)平成15年8月.
 5) 原田 秀樹・大橋 晶良・井町 寛之, 2004: 超高速メタン発酵バイオリアクターの開発と汚泥菌叢の分子微生物生態解析、環境バイオテクノロジー学会誌, Vol.4, No.1, pp.19-27.
 6) Amann, R.I, B.J. Binder, R.J. Olson, S.W. Chisholm, R. Devereux, and D.A. Stahl, 1990: Combination of 16S rRNA-targeted oligonucleotide probes with flow cytometry for analyzing mixed microbial populations, Appl. Environ. Microbiol., Vol.56, pp.1919-1925.
 7) Chernicharo, C.A. de L., 2007: Biological Wastewater Treatment Series Vol.4 Anaerobic Reactors, 188 pages, IWA Publishing.
 8) Delong, E.F., K.Y. Wu, B.B. Prezelin, and R.V.M. Jovine, 1989: Phylogenetic strains: Ribosomal RNA-based probes for identification of single cells, Science, Vol.243, pp.1360-1363.
 9) Gujer, W., and Zehnder, 1983: Conversion processes in anaerobic digestion, Wat.Sci.Techn.,Vol.15,No.8/9, pp.127-167.
 10) Lier, J.B.van, N. Mahmoud, and G. Zeeman, 2008: Biological Wastewater Treatment: Principles Modelling and Design, Chap.16, Anaerobic Wastewater Treatment, pp.402-442, IWA Publishing.
 11) Liu, W.T., T.L. Marsh, H. Cheng, and L.J. Forney, 1997: Characterization of microbial diversity by determining by terminal restriction length polymorphisms of genes encoding 16S rRNA, Appl. Environ. Microbiol., Vol.63, pp.4516-4522.
 12) Mara, D., 2003: Domestic Wastewater Treatment in Developing Countries, 310 pages, Earthscan.
 13) Muyzer, G., E.C. de Waal, and A.G. Uitterlinden, 1993: Profiling of complex microbial populations by denatured gradient gel electrophoresis analysis of polymerase chain reaction-amplified genes coding for 16S rRNA, Appl. Environ. Microbiol., Vol.59, pp.695-700.
 14) Olsen, G.J., S.J. Giovannoni, and N.R. Pace, 1986: Microbiology ecology and evolution: a ribosomal RNA approach, Ann. Rev. Microbiol, Vol.40, pp.337-365.
 15) Sekiguchi, Y., Y. Kamagata, K. Nakamura, A. Ohashi, and H. Harada, 1999: Fluorescence in situ hybridization using 16S rRNA-targeted oligonucleotides reveals localization of methanogens and selected uncultured bacteria in mesophilic and thermophilic sludge granules, App. Environ. Microbiol., Vol.65, pp.1280-1288.


 1) Kiyofumi Oogi, 2012: Future prospects of clinical microbiological testing-Three major technological innovations and contribution to patient care, Animus, No.73, pp.14-21 (in Japanese).
 2) Naoaki Kataoka, 2010: Characteristics and development flow of anaerobic biological treatment technology, Ebara Bulletin No.229, pp.27-38 (in Japanese).
 3) Yamaichi Kamagata, 2007: What are refractory microorganisms? , Journal of Environmental Biotechnology, Vol.7, No.2, pp.69-73 (in Japanese).
 4) Ministry of Land, Infrastructure, Transport and Tourism, 2003: Biosolid Utilization Basic Plan Formulation Manual (Draft) August 2003 (in Japanese).
 5) Hideki Harada, Ohashi Akiyoshi, Imachi Hiroyuki, 2004: Development of ultrafast methane fermentation bioreactor, molecular microbial ecology analysis of sludge flora, Journal of Environmental Biotechnology, Vol.4, No.1, pp.19-27 (in Japanese).
(The following is the same as the left column.)


Published: May 6, 2017
Updated: May 14, 2017
Updated: July 11, 2020 (English version added)
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