JP4289454B2 - Methane fermentation process and methane fermentation system - Google Patents
Methane fermentation process and methane fermentation system Download PDFInfo
- Publication number
- JP4289454B2 JP4289454B2 JP2003329281A JP2003329281A JP4289454B2 JP 4289454 B2 JP4289454 B2 JP 4289454B2 JP 2003329281 A JP2003329281 A JP 2003329281A JP 2003329281 A JP2003329281 A JP 2003329281A JP 4289454 B2 JP4289454 B2 JP 4289454B2
- Authority
- JP
- Japan
- Prior art keywords
- tank
- methane fermentation
- electrodeposition
- electrodialysis
- treatment
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Images
Classifications
-
- 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
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A40/00—Adaptation technologies in agriculture, forestry, livestock or agroalimentary production
- Y02A40/10—Adaptation technologies in agriculture, forestry, livestock or agroalimentary production in agriculture
- Y02A40/20—Fertilizers of biological origin, e.g. guano or fertilizers made from animal corpses
-
- 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
-
- 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
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/40—Bio-organic fraction processing; Production of fertilisers from the organic fraction of waste or refuse
Landscapes
- Processing Of Solid Wastes (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
- Treatment Of Sludge (AREA)
- Water Treatment By Electricity Or Magnetism (AREA)
- Fertilizers (AREA)
Description
本発明は、メタン発酵プロセスおよびメタン発酵システムに関し、詳細には、有機性廃棄物をメタン発酵処理して得られる発酵液から、重金属等を効率良く除去するためのメタン発酵プロセスおよびメタン発酵システムに関する。 The present invention relates to a methane fermentation process and a methane fermentation system, and more particularly, to a methane fermentation process and a methane fermentation system for efficiently removing heavy metals and the like from a fermentation liquid obtained by subjecting organic waste to methane fermentation. .
食品廃棄物、家畜糞尿、下水汚泥等の有機性廃棄物については、メタン発酵処理を施し、堆肥化して農地還元することが行われている。しかし、メタン発酵液中には、重金属類や食塩などの塩類が含まれていることがあり、有機性廃棄物のリサイクルにおいて妨げとなる場合がある。特に溶解度が小さい重金属類については、土壌中に蓄積する可能性が捨てきれず、土壌汚染の原因となることが懸念されている。 Organic waste such as food waste, livestock manure, and sewage sludge is subjected to methane fermentation treatment, composted, and returned to farmland. However, the methane fermentation broth may contain salts such as heavy metals and salt, which may hinder recycling of organic waste. In particular, for heavy metals with low solubility, the possibility of accumulating in the soil cannot be discarded, and there is concern that it may cause soil contamination.
食品廃棄物中に比較的多量に含まれる食塩については、メタン発酵処理後に堆肥化して農地還元した場合、雨水による溶出、地下への浸透により土壌中の濃度が漸次減少していくため、塩害を生じさせにくいと考えられているが、地域性や気象条件によっては、明らかに農地還元に適さない濃度の塩類を含む場合もある。 For salt contained in food waste in a relatively large amount, when it is composted after methane fermentation treatment and reduced to farmland, the concentration in the soil gradually decreases due to elution by rainwater and penetration into the underground, causing salt damage. Although it is thought that it is difficult to produce, depending on the regional characteristics and weather conditions, it may contain salts with concentrations that are clearly unsuitable for agricultural land reduction.
以上のような状況に鑑み、塩類を含有する有機性廃棄物を脱塩処理した後、メタン発酵処理する有機性廃棄物の処理方法が提案されている(例えば、特許文献1)。 In view of the above situation, a method for treating organic waste in which methane fermentation treatment is performed after desalting the organic waste containing salts has been proposed (for example, Patent Document 1).
特許文献1に記載の方法は、メタン発酵前の流動性が低い有機性廃物を脱塩処理する方法であるが、発酵前の有機性廃棄物は粘性が大きく、塩類(イオン類)や重金属類が移動し難い状態で存在するため除去効率が低く、特に重金属類の除去効果はほとんど期待できない。また、粘性の大きな有機性廃棄物を処理するために高圧ポンプが必要となり、消費電力も大きくなるため経済的でない。有機性廃棄物を微細化して水を加え、希釈すれば粘性を下げられるが、メタン発酵処理の際の水分が多くなりすぎると装置サイズを大型化せざるを得ないため、実用的な方法ではない。 The method described in Patent Document 1 is a method of desalinating organic waste having low fluidity before methane fermentation, but organic waste before fermentation has a large viscosity, and salts (ions) and heavy metals Is present in a state where it is difficult to move, the removal efficiency is low, and in particular, the removal effect of heavy metals can hardly be expected. In addition, a high-pressure pump is required to process organic waste with a high viscosity, and power consumption is increased, which is not economical. If the organic waste is refined and water is added and diluted, the viscosity can be reduced, but if the water during the methane fermentation process becomes too much, the equipment size must be increased. Absent.
本発明は、有機性廃棄物をメタン発酵処理して堆肥等として再利用する際に、メタン発酵液から効率良く塩類や重金属類を除去する方法を提供することにある。 An object of the present invention is to provide a method for efficiently removing salts and heavy metals from a methane fermentation liquid when organic waste is subjected to methane fermentation treatment and reused as compost or the like.
上記課題を解決するため、本発明の第1の態様は、有機性廃棄物をメタン発酵処理し、発酵液を電気透析処理および/または電析処理することを特徴とする、メタン発酵プロセスである。電気透析処理によって、メタン発酵液中に含まれる有機性廃棄物由来の塩類と重金属類の一部を効率よく除去することができる。同様に、電析処理によって、重金属類を効率良く除去することができる。従って、電気透析または電析処理後のメタン発酵液は、塩分や重金属類の含有量が低く、堆肥化して土壌に施用する場合でも塩害や重金属類が蓄積するという問題が生じない。さらに、電気透析や電析は、メタン発酵後の液について行われるため、処理効率が良いとともに、消費エネルギーも少なく経済的なプロセスとなる。 In order to solve the above-mentioned problems, a first aspect of the present invention is a methane fermentation process characterized in that organic waste is subjected to methane fermentation treatment, and the fermentation solution is subjected to electrodialysis treatment and / or electrodeposition treatment. . By electrodialysis, a part of the organic waste-derived salts and heavy metals contained in the methane fermentation liquid can be efficiently removed. Similarly, heavy metals can be efficiently removed by electrodeposition. Therefore, the methane fermentation broth after electrodialysis or electrodeposition has a low content of salt and heavy metals, and even when composted and applied to soil, there is no problem of accumulation of salt damage and heavy metals. Furthermore, since electrodialysis and electrodeposition are performed on the liquid after methane fermentation, it is an economical process with good treatment efficiency and low energy consumption.
本発明の第2の態様は、第1の態様において、発酵液の酸化還元状態および/または水素イオン濃度を調整した後、電気透析処理または電析処理を行うことを特徴とする、メタン発酵プロセスである。メタン発酵液の酸化還元状態や水素イオン濃度を調整することにより、メタン発酵液中に含まれる重金属類をイオン化させ、溶解状態にすることができる。従って、電気透析や電析による除去効率を大幅に向上させることができる。 According to a second aspect of the present invention, in the first aspect, a methane fermentation process characterized by performing an electrodialysis treatment or an electrodeposition treatment after adjusting the oxidation-reduction state and / or hydrogen ion concentration of the fermentation broth. It is. By adjusting the oxidation-reduction state and hydrogen ion concentration of the methane fermentation broth, heavy metals contained in the methane fermentation broth can be ionized to be in a dissolved state. Therefore, the removal efficiency by electrodialysis or electrodeposition can be greatly improved.
本発明の第3の態様は、第1または第2の態様において、電析処理によって発酵液中から除去した重金属類を、電析槽への印加電圧の極性を反転させて溶出させ、回収することを特徴とする、メタン発酵プロセスである。これにより、メタン発酵液から析出分離した重金属類を容易に回収できる。 According to a third aspect of the present invention, in the first or second aspect, the heavy metals removed from the fermentation liquor by the electrodeposition treatment are eluted by reversing the polarity of the voltage applied to the electrodeposition tank and recovered. This is a methane fermentation process. Thereby, heavy metals precipitated and separated from the methane fermentation liquid can be easily recovered.
本発明の第4の態様は、水処理施設において、該施設から発生する汚泥をメタン発酵処理し、発酵液を電気透析処理するとともに、電気透析処理における濃縮液側に前記水処理施設からの水を供給することを特徴とするメタン発酵プロセスである。電気透析処理では、濃縮液として多量の水を必要とし、その処理も必要になるが、本発明の第4の態様では水処理施設と連携させ、濃縮液として水処理施設の水を用いることによって、水の供給手段と処理手段が確保されるので、効率的なプロセスとなる。 According to a fourth aspect of the present invention, in a water treatment facility, sludge generated from the facility is subjected to methane fermentation treatment, the fermentation solution is electrodialyzed, and water from the water treatment facility is placed on the concentrate side in the electrodialysis treatment. It is a methane fermentation process characterized by supplying. In electrodialysis treatment, a large amount of water is required as a concentrate, and the treatment is also necessary. In the fourth aspect of the present invention, the water of the water treatment facility is used as the concentrate by cooperating with the water treatment facility. Since the water supply means and the treatment means are secured, the process is efficient.
本発明の第5の態様は、有機性廃棄物をメタン発酵処理するメタン発酵槽と、発酵液を電気透析処理する電気透析装置および/または発酵液を電析処理する電析装置を備えたことを特徴とする、メタン発酵システムである。このメタン発酵システムは、前記第1の態様のプロセスの実施に適したものである。 The fifth aspect of the present invention includes a methane fermentation tank for subjecting organic waste to methane fermentation, an electrodialysis apparatus for electrodialyzing the fermentation liquid, and / or an electrodeposition apparatus for electrodepositioning the fermentation liquid. This is a methane fermentation system. This methane fermentation system is suitable for carrying out the process of the first aspect.
本発明の第6の態様は、第5の態様において、前記電気透析装置または電析装置の前段に、検出器として酸化還元電位計、硫化物イオン検出器、またはpH電極を設けたことを特徴とする、メタン発酵システムである。このメタン発酵システムは、前記第2の態様のプロセスの実施に適したものである。 According to a sixth aspect of the present invention, in the fifth aspect, an oxidation-reduction potentiometer, a sulfide ion detector, or a pH electrode is provided as a detector before the electrodialysis apparatus or the electrodeposition apparatus. It is a methane fermentation system. This methane fermentation system is suitable for carrying out the process of the second aspect.
電気透析処理によって、メタン発酵液中に含まれる有機性廃棄物由来の塩類と重金属類の一部を効率よく除去することができる。同様に、電析処理によって、同様に重金属類を効率良く除去することができる。従って、電気透析または電析処理後のメタン発酵液は、塩分や重金属類の含有量が低く、堆肥化して土壌に施用する場合でも塩害や重金属類が蓄積するという問題が生じない。さらに、電気透析や電析は、メタン発酵後の液について行われるため、処理効率が良いとともに、消費エネルギーも少なく経済的なプロセスとなる。 By electrodialysis, a part of the organic waste-derived salts and heavy metals contained in the methane fermentation liquid can be efficiently removed. Similarly, heavy metals can be efficiently removed by the electrodeposition process. Therefore, the methane fermentation broth after electrodialysis or electrodeposition has a low content of salt and heavy metals, and even when composted and applied to soil, there is no problem of accumulation of salt damage and heavy metals. Furthermore, since electrodialysis and electrodeposition are performed on the liquid after methane fermentation, it is an economical process with good treatment efficiency and low energy consumption.
<有機性廃棄物>
本発明において有機性廃棄物とは、例えば、畜産廃棄物や緑農廃棄物、排水処理汚泥などが挙げられる。ここで畜産廃棄物としては、家畜の糞尿や、屠体および/またはその加工品が挙げられ、より具体的には牛、羊、山羊、ニワトリ等の家畜の屠体、そこから分離された骨、肉、脂肪、内蔵、血液、脳、眼球、皮、蹄、角などのほか、例えば肉骨粉、肉粉、骨粉、血粉などに代表される、家畜屠体の骨、肉等を破砕した破砕物や、血液などを乾燥した乾燥物も含まれる。また緑農廃棄物には、家庭の生ごみのほか、産業廃棄物生ごみとして、農水産業廃棄物、食品加工廃棄物等が含まれる。
<Organic waste>
In the present invention, organic waste includes, for example, livestock waste, green farm waste, wastewater treatment sludge, and the like. Examples of livestock waste include livestock manure, carcass and / or processed products thereof. More specifically, livestock carcasses such as cattle, sheep, goats and chickens, and bones separated therefrom. In addition to meat, fat, internal organs, blood, brain, eyeballs, skin, hoofs, horns, etc., crushed material of bones, meat, etc. of livestock carcasses represented by meat and bone meal, meat meal, bone meal, blood meal In addition, a dried product obtained by drying blood or the like is also included. In addition to household garbage, green agricultural waste includes agricultural and industrial waste, food processing waste, etc. as industrial waste.
<重金属類、塩類>
本発明において除去の対象となる重金属類としては、例えば、家畜糞尿中に含まれる亜鉛や、下水汚泥中に含まれるカドミウム、鉛、銅、クロムなどが挙げられる。また、塩類としては、例えば、食品廃棄物中に含まれる塩化ナトリウムなどが挙げられる。
<Heavy metals and salts>
Examples of heavy metals to be removed in the present invention include zinc contained in livestock manure, cadmium, lead, copper, chromium, etc. contained in sewage sludge. Examples of the salts include sodium chloride contained in food waste.
<発酵工程>
本発明プロセスにおいては、メタン発酵に先立ち、原料となる有機性廃棄物の状態により、必要に応じて前処理として破砕・分別工程を実施することができる。破砕・分別工程は、例えば、以下に示すような分別破砕、あるいは全量破砕により行うことができる。
分別破砕の場合は、破砕分別機を用い、有機性廃棄物の中で容易に破砕可能な部位を液と共にスラリーとして回収する。一方、破砕しにくい部位は塊状物として別途収集する。スラリーの含水率は、70〜90重量%、塊状物の含水率は40〜60重量%程度である。破砕分別機は、有機性の固形物をせん断力、引っ張り力によって破砕するもので、カッター部分は2軸式または3軸式のものが利用できる。牛などの動物屠体を原料とする場合は、3軸式で破砕処理する方が破砕物の細かさや均一性の観点から好ましい。
<Fermentation process>
In the process of the present invention, prior to methane fermentation, depending on the state of organic waste as a raw material, a crushing / sorting step can be performed as a pretreatment as necessary. The crushing / sorting step can be performed by, for example, fractionating crushing as shown below, or crushing the entire amount.
In the case of fractional crushing, a crushing / separating machine is used to collect a portion that can be easily crushed in organic waste as a slurry together with a liquid. On the other hand, parts that are difficult to crush are collected separately as a lump. The water content of the slurry is 70 to 90% by weight, and the water content of the lump is about 40 to 60% by weight. The crushing / separating machine crushes organic solids by a shearing force and a pulling force, and a two-axis type or a three-axis type cutter can be used. When animal carcasses such as cattle are used as raw materials, it is preferable to crush the triaxial type from the viewpoint of the fineness and uniformity of the crushed material.
選別除去すべき混入プラスチック類、シート類などは、メッシュによる選別、風選(風力による選別)などで除去することができる。 The mixed plastics and sheets to be sorted and removed can be removed by mesh sorting, wind sorting (wind sorting), or the like.
また、全量粉砕の場合は、例えばディスポーザー等の破砕機を使用して全対象物を破砕する。含水率は、一例として60〜70重量%であるが、有機性廃棄物の種類に応じて広い範囲をとる。 In the case of pulverizing the entire amount, for example, the entire object is crushed using a crusher such as a disposer. The water content is 60 to 70% by weight as an example, but takes a wide range depending on the type of organic waste.
メタン発酵は、いわゆる中温型、高温型、またスラリー(湿式)型、ドライ(乾式)型のいずれのタイプでも適用可能である。 Methane fermentation can be applied to any of a so-called medium temperature type, a high temperature type, a slurry (wet) type, and a dry (dry) type.
発酵槽は、絶対嫌気性のメタン発酵菌による活動を維持するために、二槽方式をとる発酵プロセスの場合も、後段においては空気を完全に遮断したタンクにより構成される。発酵槽は固形物濃度(通常3〜40重量%の範囲)と発酵温度(通常、中温発酵では37℃、高温発酵では55℃)によって、形状や運転条件が異なってくる。例えば、洗浄廃水が混合したりして高含水率になった原料(固形物濃度10重量%まで)の場合は湿式型の完全混合方式の発酵槽、低含水率の原料(固形物濃度30〜40重量%)の場合は、いわゆる乾式型のプラグフロー式(押出し式)の発酵槽を用いることが好ましい。 The fermenter is composed of a tank in which air is completely shut off in the latter stage even in the case of a fermentation process using a two-tank system in order to maintain the activity due to the anaerobic methane fermentation bacteria. The shape and operating conditions of the fermenter vary depending on the solid concentration (usually in the range of 3 to 40% by weight) and the fermentation temperature (usually 37 ° C for medium temperature fermentation and 55 ° C for high temperature fermentation). For example, in the case of a raw material having a high water content (up to a solid concentration of 10% by weight) mixed with washing waste water, a wet type complete mixing method fermenter, a raw material having a low water content (solids concentration of 30 to 30%) 40 wt%), it is preferable to use a so-called dry type plug flow type (extrusion type) fermenter.
発酵槽には、生成するバイオガスを回収するための回収手段のほか、必要に応じて保温のための加熱手段を設けておくことが好ましい。また、バイオガスの回収手段には、必要に応じて脱硫装置を設けることもできる。これらは既知の構成のものを利用できる。 In addition to the recovery means for recovering the biogas to be produced, it is preferable that the fermenter is provided with a heating means for keeping warm if necessary. In addition, the biogas recovery means may be provided with a desulfurization apparatus as required. Those having a known configuration can be used.
高含水率の原料(固形物濃度を10重量%程度まで)の場合は、完全混合方式の発酵槽を用い、高温メタン発酵菌(至適温度55℃)では、滞留時間(Retention Time)を10〜15日間程度、中温メタン発酵菌(至適温度37℃)では、滞留時間を20〜30日間程度とすることが可能である。 In the case of a raw material with a high water content (solids concentration up to about 10% by weight), a complete mixing type fermenter is used, and in a high-temperature methane-fermenting bacterium (optimum temperature 55 ° C.), the retention time (Retention Time) is 10 About 15 to 15 days, with medium temperature methane fermentation bacteria (optimum temperature 37 ° C.), the residence time can be about 20 to 30 days.
低含水率の原料(固形物濃度30〜40重量%)の場合は、被処理物の固形分濃度を30〜40重量%にして押出し式の発酵槽を使用できる程度の固さに調整する。滞留時間については、高含水率の場合と同様に設定することができる。また、C/N比の調整のために、必要に応じて若干の有機成分を導入することもできる。 In the case of a raw material having a low water content (solids concentration of 30 to 40% by weight), the solid content concentration of the object to be treated is adjusted to 30 to 40% by weight to adjust the hardness to such an extent that an extrusion type fermenter can be used. About residence time, it can set similarly to the case of high moisture content. Further, for the adjustment of the C / N ratio, some organic components can be introduced as necessary.
高含水率型のメタン発酵後の発酵残渣は、例えば水分含有率95重量%、固形分5重量%程度を含む液体であり、嫌気性微生物の菌体およびその代謝産物に由来する各種のアミノ酸や有機酸などを多量に含んでいる。 The fermentation residue after methane fermentation of high water content type is, for example, a liquid containing a moisture content of 95% by weight and a solid content of about 5% by weight, and various amino acids derived from anaerobic microorganisms and their metabolites Contains a large amount of organic acids.
メタン発酵後に必要に応じて発酵残渣の固液分離工程を設けることができる。固液分離は、例えばデカンター、凝集沈殿槽、遠心脱水機、スクリュープレス、膜分離器など、スラリー濃度を高めることが可能な装置を利用可能であり、発酵残渣の性状に応じて選択される。 A solid-liquid separation step of the fermentation residue can be provided as necessary after methane fermentation. For the solid-liquid separation, an apparatus capable of increasing the slurry concentration, such as a decanter, a coagulation sedimentation tank, a centrifugal dehydrator, a screw press, and a membrane separator, can be used, and is selected according to the properties of the fermentation residue.
以上のメタン発酵において、発酵により生成するバイオガスは、有機性廃棄物の種類により異なるが、通例メタンを60重量%程度、二酸化炭素を40重量%程度含んでいるため、例えばガスエンジン、温水ボイラー、蒸気ボイラー、ガスタービン、燃料電池等の燃料として利用できる。これらの中でも、特に、ガスエンジン、ガスタービン、燃料電池などによるコージェネレーションシステムを採用することにより、バイオガスを燃料として熱と電力を回収することができる。 In the above methane fermentation, the biogas produced by fermentation varies depending on the type of organic waste, but typically contains about 60% by weight of methane and about 40% by weight of carbon dioxide. It can be used as fuel for steam boilers, gas turbines, fuel cells and the like. Among these, in particular, by employing a cogeneration system such as a gas engine, a gas turbine, or a fuel cell, heat and electric power can be recovered using biogas as fuel.
バイオガスを燃料として回収された熱は、例えば蒸気の形態で供給され、メタン発酵槽の加温や発酵液の濃縮などの熱源として利用できる。 The heat recovered using biogas as fuel is supplied in the form of steam, for example, and can be used as a heat source for heating the methane fermentation tank or concentrating the fermentation broth.
また、発酵槽や濃縮装置においては、真空ポンプなどの減圧装置、攪拌装置などの動力として電力を消費するが、このときの電力の全てをコージェネレーションによる電力で賄うことが可能であり、余剰の電力は他の用途に転用できる。 In addition, in fermenters and concentrators, power is consumed as power for decompression devices such as vacuum pumps, stirring devices, etc., but it is possible to cover all of the power at this time with power generated by cogeneration. Electricity can be diverted to other uses.
<電気透析処理および電析処理>
電気透析処理および電析処理(電着処理または電解処理とも呼ばれる)は、常法に従い実施することができる。電気透析装置や電析装置としては、特に制限はなく、既知の構成のものを好適に使用することができる。
<Electrodialysis treatment and electrodeposition treatment>
Electrodialysis treatment and electrodeposition treatment (also referred to as electrodeposition treatment or electrolytic treatment) can be carried out according to conventional methods. There is no restriction | limiting in particular as an electrodialysis apparatus or an electrodeposition apparatus, The thing of a known structure can be used conveniently.
本発明においては、電気透析または電析に先立ち、発酵液の酸化還元状態および/または水素イオン濃度を調整しておくことが好ましい。電気透析法、電析槽(電析・溶出槽)において効率良く重金属類を除去するためには、重金属類が溶解(イオン化)していることが重要である。例えば、ヒ素や鉄は還元性雰囲気で、また、クロムや水銀は酸化性雰囲気で溶出し易くなり、また、鉛やカドニウムは低いpH値(例えば、約pH6以下)で著しく溶解性が向上する。亜鉛は、低いpH(例えば、約pH6以下)あるいは高pH(例えば、約pH8以上)にて溶解性が大きくなる。 In the present invention, prior to electrodialysis or electrodeposition, it is preferable to adjust the oxidation-reduction state and / or hydrogen ion concentration of the fermentation broth. In order to efficiently remove heavy metals in the electrodialysis method and electrodeposition tank (electrodeposition / elution tank), it is important that the heavy metals are dissolved (ionized). For example, arsenic and iron are easily eluted in a reducing atmosphere, chromium and mercury are easily eluted in an oxidizing atmosphere, and lead and cadmium are significantly improved in solubility at a low pH value (for example, about pH 6 or less). Zinc is highly soluble at low pH (eg, about pH 6 or lower) or high pH (eg, about pH 8 or higher).
従って、発酵液の酸化還元状態やpHを調整することにより、発酵液中の重金属類の溶解を促進することができる。高い溶解性を発現する最適値は、対象とする重金属、発酵液の共存成分、許容できるコストなどによって大きく異なる。また、特に後述する調整槽から検出器に至る間の発酵液流通時間は、実用上十分な平衡に達するまでの時間とすることが好ましく、通常数10秒以上をとることができる。 Therefore, by adjusting the oxidation-reduction state and pH of the fermentation broth, dissolution of heavy metals in the fermentation broth can be promoted. The optimum value that expresses high solubility varies greatly depending on the heavy metal of interest, the coexisting components of the fermentation broth, the acceptable cost, and the like. Moreover, it is preferable to make especially the fermentation liquid distribution | circulation time from the adjustment tank mentioned later to a detector into the time until it reaches | attains practically sufficient equilibrium, and can take several tens of seconds normally.
酸化還元状態の調整では、まず調整槽において嫌気・好気度を調整し、次に検出器を用いて発酵液の酸化還元状態を検出する。その後、発酵液を電気透析槽及び/または電析槽(電析・溶出槽)に送液する。つまり処理手順の一例としては、調整槽→検出器→電気透析槽・電析槽という順序となる。ここで、検出器としては、酸化還元電極(検出電極として、例えば白金、金等の貴金属極、炭素極、銀−塩化銀電極等の参照極、温度検出極からなる検出器)あるいは硫化物イオンを検出するイオン電極(ハロゲン化銀などの固体電解質系電極等と参照極、温度検出極からなる検出器)などを使用することができる。これらの検出器は、調整槽に設けてもよいが、調整槽から電気透析槽または電析槽に至る経路(配管)上に配備することが好ましい。 In the adjustment of the redox state, the anaerobic / aerobic degree is first adjusted in the adjustment tank, and then the redox state of the fermentation broth is detected using a detector. Thereafter, the fermentation broth is fed to an electrodialysis tank and / or an electrodeposition tank (electrodeposition / elution tank). That is, as an example of the processing procedure, the order is the adjustment tank → detector → electrodialysis tank / electrodeposition tank. Here, as a detector, a redox electrode (a detector comprising a noble metal electrode such as platinum or gold, a carbon electrode, a reference electrode such as a silver-silver chloride electrode, or a temperature detection electrode as a detection electrode) or sulfide ion An ion electrode (a detector comprising a solid electrolyte electrode such as silver halide, a reference electrode, and a temperature detection electrode) can be used. These detectors may be provided in the adjustment tank, but are preferably provided on a path (pipe) from the adjustment tank to the electrodialysis tank or the electrodeposition tank.
調整槽においては、以下に示す操作を行うことにより嫌気・好気度を調整することができる。好気化する場合は、例えばスタティックミキサー等を内蔵した発酵液配管の上流側に空気を注入することにより調整できる。嫌気化する場合は、例えば、発酵液配管の一部をジャケット式熱交換器とし、ジャケット部分に温水もしくは蒸気を通じて、発酵液温度を一時的に50℃程度まで昇温する。これによって、発酵液中の有機物の分解が促進され、酸素が消費される。 In the adjustment tank, the anaerobic / aerobic level can be adjusted by performing the following operations. In the case of aerobic, it can be adjusted, for example, by injecting air into the upstream side of the fermentation liquor pipe incorporating a static mixer or the like. In the case of anaerobic, for example, a part of the fermentation liquor pipe is used as a jacket type heat exchanger, and the temperature of the fermentation liquor is temporarily raised to about 50 ° C. through warm water or steam through the jacket part. This accelerates the decomposition of organic matter in the fermentation broth and consumes oxygen.
以上と同様に、pHの制御も、例えばpH電極、酸・アルカリ注入装置、ミキサーなどを組み合わせて実施することができる。pH調整の為に注入する酸やアルカリとしては、例えば、塩酸、硫酸などの酸や水酸化ナトリウム、水酸化カルシウムなどのアルカリが挙げられる。なお、必要に応じて、電気透析・電析(電析)処理後にpHを再調整(例えば、元のpHに戻す)する操作を行うことができる。 Similarly to the above, the pH can be controlled by combining, for example, a pH electrode, an acid / alkali injection device, a mixer, and the like. Examples of the acid and alkali to be injected for pH adjustment include acids such as hydrochloric acid and sulfuric acid, and alkalis such as sodium hydroxide and calcium hydroxide. In addition, as needed, operation which readjusts pH (for example, returns to original pH) after an electrodialysis and electrodeposition (electrodeposition) process can be performed.
電析処理によって発酵液中から除去した重金属は、電析槽への印加電圧の極性を反転させることによって、回収液中に溶出させることができる。溶出させた重金属類は、キレート剤などを添加することによって不溶化させ、吸着材に吸着するなどの方法で回収できる。 The heavy metal removed from the fermentation broth by the electrodeposition treatment can be eluted in the recovered liquid by reversing the polarity of the voltage applied to the electrodeposition tank. The eluted heavy metals can be recovered by a method such as insolubilization by adding a chelating agent or the like and adsorption to an adsorbent.
以下、図面に基づき本発明のメタン発酵プロセスの好ましい実施の形態を説明する。
第1実施形態:
図1に従い、家畜糞尿などの有機性廃棄物をメタン発酵し、亜鉛などの重金属を電気透析処理および/または電析処理により除去するプロセスである。
まず、豚などの家畜の糞尿は一旦受槽に貯留された後、前処理槽に導入され、ここで破砕・ペースト化、前発酵などが行われる。前処理が済んだ豚糞尿は、消化タンクに導入される。
Hereinafter, preferred embodiments of the methane fermentation process of the present invention will be described with reference to the drawings.
First embodiment:
According to FIG. 1, organic waste such as livestock manure is subjected to methane fermentation, and heavy metals such as zinc are removed by electrodialysis and / or electrodeposition.
First, livestock manure such as pigs is once stored in a receiving tank and then introduced into a pretreatment tank where crushing / pasting, pre-fermentation, and the like are performed. The pre-treated swine manure is introduced into the digestion tank.
消化タンクにおいて所定の発酵期間が経過し、嫌気消化が終了した時点で、メタン発酵液を抜出し、濃縮槽に導く。濃縮槽では、重力沈降によって上澄みを分取し、沈澱物を調整槽に移す。 When a predetermined fermentation period elapses in the digestion tank and the anaerobic digestion is completed, the methane fermentation solution is extracted and guided to the concentration tank. In the concentration tank, the supernatant is collected by gravity sedimentation, and the precipitate is transferred to the adjustment tank.
調整槽では、エアレーションなどによる発酵液の酸化還元状態やpHの調整を行う。この操作によって、メタン発酵液中に含まれる重金属類をイオン化させ、電気透析や電析の効率を高めることができる。例えば、エアレーションでは、メタン発酵液に空気を導入して好気性条件とし、硫化物および/もしくは硫化物イオンを酸化する。エアレーションは、硫化物イオンの量を検出器を用いてモニタリングしながら実施することが好ましい。 In the adjustment tank, the redox state and pH of the fermentation broth are adjusted by aeration or the like. By this operation, heavy metals contained in the methane fermentation liquid can be ionized, and the efficiency of electrodialysis and electrodeposition can be increased. For example, in aeration, air is introduced into a methane fermentation broth to achieve aerobic conditions, and sulfides and / or sulfide ions are oxidized. The aeration is preferably performed while monitoring the amount of sulfide ions using a detector.
調整槽での処理が済んだメタン発酵液は、その酸化還元電位、硫化物濃度、pHなどを検出器により計測して所定の範囲にあることを確認した後、電気透析槽および電析槽に順次導入する。これにより、メタン発酵液の脱塩と重金属類の除去が行われる。糞尿中の亜鉛などの金属は主にアンモニアと錯イオンを作って溶存状態にあり、電気透析または電析によって除去される。なお、豚などの家畜糞尿や蛋白質中心の食品廃棄物等のメタン発酵処理では発酵液中にアンモニアが比較的多く生成するので、亜鉛はアンモニア錯体として溶存しやすくなる。電析によって電析槽に析出した重金属類は、電析槽への印加電圧の極性を反転させることにより溶出させ、重金属回収槽に回収する。 The methane fermentation broth treated in the adjustment tank is measured by its detector for its oxidation-reduction potential, sulfide concentration, pH, etc. Introduce sequentially. Thereby, desalination of methane fermentation liquid and removal of heavy metals are performed. Metals such as zinc in manure are in a dissolved state mainly by forming complex ions with ammonia, and are removed by electrodialysis or electrodeposition. In the methane fermentation treatment of livestock manure such as pigs and protein-centered food waste, a relatively large amount of ammonia is produced in the fermentation broth, so that zinc is easily dissolved as an ammonia complex. Heavy metals deposited in the electrodeposition tank by electrodeposition are eluted by reversing the polarity of the voltage applied to the electrodeposition tank and recovered in the heavy metal recovery tank.
電気透析槽および/または電析槽を通過したメタン発酵液は、堆肥化設備に導入され、堆肥化される。このようにして得られる堆肥は、塩分が少なく、重金属類も除去されているため、農地還元しても塩害や重金属類による汚染を引き起こす心配がないものである。 The methane fermentation liquid that has passed through the electrodialysis tank and / or the electrodeposition tank is introduced into a composting facility and composted. Since the compost obtained in this way has a low salt content and heavy metals have been removed, there is no fear of causing salt damage or contamination with heavy metals even when reduced to farmland.
第2実施形態:
図2に示すように、生ごみや下水汚泥などの有機性廃棄物をメタン発酵処理して堆肥化するとともに、重金属類のヒ素などは電気透析法により、水銀や鉛などは電析法によって除去するプロセスである。
Second embodiment:
As shown in Fig. 2, organic waste such as garbage and sewage sludge is composted by methane fermentation. Heavy metals such as arsenic are removed by electrodialysis, and mercury and lead are removed by electrodeposition. Process.
まず、生ごみなどの有機性廃棄物は受槽から前処理槽に導入され、ここで破砕・ペースト化、前発酵などが行われる。前処理が済んだ生ごみペーストは、消化タンクに導入される。一方、水処理汚泥は直接消化タンクに導入され、生ごみペーストと混合され、メタン発酵が行われる。 First, organic waste such as garbage is introduced into the pretreatment tank from the receiving tank, where crushing, pasting, pre-fermentation, and the like are performed. The pre-treated garbage paste is introduced into the digestion tank. On the other hand, water treatment sludge is directly introduced into the digestion tank, mixed with garbage paste, and methane fermentation is performed.
所定の発酵期間が経過し、嫌気消化が終了した時点で、メタン発酵液を抜出し、濃縮槽に導く。濃縮槽では、重力沈降によって上澄みを分取し、沈澱物を調整槽に移す。 When the predetermined fermentation period has elapsed and the anaerobic digestion has been completed, the methane fermentation solution is extracted and guided to the concentration tank. In the concentration tank, the supernatant is collected by gravity sedimentation, and the precipitate is transferred to the adjustment tank.
次に、調整槽では、発酵液の酸化還元状態やpHの調整を行う。この操作によって、メタン発酵液中に含まれる重金属類をイオン化させ、電気透析や電析の効率を高めることができる。例えば、発酵液に含まれる重金属類としてヒ素等が想定される場合は、ヒ素が溶出しやすい酸化還元状態(例えばpH6以下、酸化還元電位−50mV以下)に調整する。ヒ素の場合は発酵液を若干の嫌気状態におく方が溶出させやすくなり、電気透析によって除去し易くなる。しかし、完全な嫌気状態では、硫化物として懸濁物となっている場合が多く、電気透析では除去し難い。なお、荷電したヒ素コロイドは、電析によって除去が可能である。 Next, in the adjustment tank, the redox state and pH of the fermentation broth are adjusted. By this operation, heavy metals contained in the methane fermentation liquid can be ionized, and the efficiency of electrodialysis and electrodeposition can be increased. For example, when arsenic or the like is assumed as a heavy metal contained in the fermentation broth, it is adjusted to an oxidation-reduction state (for example, pH 6 or less, oxidation-reduction potential −50 mV or less) in which arsenic is easily eluted. In the case of arsenic, it is easier to elute the fermentation broth in a slightly anaerobic state and it is easier to remove by electrodialysis. However, in a complete anaerobic state, it is often a suspension as a sulfide and is difficult to remove by electrodialysis. The charged arsenic colloid can be removed by electrodeposition.
また、電気透析または電析の前にpH調整が必要なときは、調整槽でエアレーションを行う場合と同様に、定量ポンプを用いて酸もしくはアルカリを注入することが好ましい。 Moreover, when pH adjustment is required before electrodialysis or electrodeposition, it is preferable to inject | pour an acid or an alkali using a metering pump similarly to the case where aeration is performed in an adjustment tank.
調整槽での処理が済んだメタン発酵液は、検出器によって酸化還元電位、硫化物濃度、pHなどを計測して所定の範囲にあることを確認した後、電気透析槽および電析槽に順次導入する。これにより、メタン発酵液の脱塩と重金属類の除去が行われる。電析によって電析槽に析出した重金属類は、電析槽への印加電圧の極性を反転させることにより溶出させ、重金属回収槽に回収する。本実施形態では、電気透析の濃縮液側に、水処理施設からの水を供給することができる。これにより、効率良くプロセスを運転することができる。 The methane fermentation broth after the treatment in the adjustment tank is measured by a detector to measure the oxidation-reduction potential, sulfide concentration, pH, etc. Introduce. Thereby, desalination of methane fermentation liquid and removal of heavy metals are performed. Heavy metals deposited in the electrodeposition tank by electrodeposition are eluted by reversing the polarity of the voltage applied to the electrodeposition tank and recovered in the heavy metal recovery tank. In this embodiment, water from the water treatment facility can be supplied to the concentrate side of electrodialysis. Thereby, the process can be operated efficiently.
電気透析槽および電析槽を通過したメタン発酵液は、堆肥化設備に導入され、堆肥化される。このようにして得られる堆肥は、塩分が少なく、重金属類も除去されているため、農地還元しても塩害や重金属類による汚染を引き起こす心配がないものである。 The methane fermentation liquid that has passed through the electrodialysis tank and the electrodeposition tank is introduced into a composting facility and composted. Since the compost obtained in this way has a low salt content and heavy metals have been removed, there is no fear of causing salt damage or contamination with heavy metals even when reduced to farmland.
図2のように、本発明のメタン発酵システムと水処理設備とを連携させることにより、電気透析により得られる濃縮水を、水処理設備の水によって稀釈することができるので処理が非常に容易になる。また、電気透析に使用する陽極室液や陰極室液、電析に使用する対極水についても水処理設備から導入できるので効率的なシステムとなる。 As shown in FIG. 2, since the methane fermentation system of the present invention and the water treatment facility are linked, the concentrated water obtained by electrodialysis can be diluted with the water of the water treatment facility, so that the treatment is very easy. Become. In addition, since the anode chamber solution and cathode chamber solution used for electrodialysis and the counter electrode water used for electrodeposition can be introduced from the water treatment facility, an efficient system is obtained.
次に、実施例を挙げ、本発明を更に詳細に説明するが、本発明はこれらによって制約されるものではない。なお、実施例、比較例では、電気透析槽および電析槽として以下の構成のものを使用した。 EXAMPLES Next, although an Example is given and this invention is demonstrated further in detail, this invention is not restrict | limited by these. In Examples and Comparative Examples, electrodialysis tanks and electrodeposition tanks having the following configurations were used.
<電気透析槽>
試料流通部が幅10mm、長さ100mm、各室の厚さ1mmの小型流通セルを電気透析槽とした。この電気透析槽は、押え板/電極板/スペーサー(濃縮室)/隔膜/スペーサー(希釈室)/隔膜/スペーサー(濃縮室)/電極板/押え板、により構成されている。
<Electrodialysis tank>
A small flow cell having a sample flow portion of 10 mm in width, 100 mm in length, and a thickness of 1 mm in each chamber was used as an electrodialysis tank. This electrodialysis tank is composed of presser plate / electrode plate / spacer (concentration chamber) / diaphragm / spacer (dilution chamber) / diaphragm / spacer (concentration chamber) / electrode plate / presser plate.
<電析槽>
電極板と隔膜で2mmの厚さの透過室を作った電析槽を使用した。この電析槽は、押え板/電極板(作用極、亜鉛電析極)/スペーサー(2mm厚)/スペーサー(2mm厚)/電極板(対極)/押え板、により構成されている。
<Electrodeposition tank>
An electrodeposition tank in which a permeation chamber having a thickness of 2 mm was made of an electrode plate and a diaphragm was used. This electrodeposition tank is composed of press plate / electrode plate (working electrode, zinc electrodeposition electrode) / spacer (2 mm thickness) / spacer (2 mm thickness) / electrode plate (counter electrode) / press plate.
比較例1
微細化した生ゴミ試料(生ごみペースト)を直接電気透析処理した後、メタン発酵処理を行った。
電気透析槽の希釈室に生ごみペーストを、濃縮室に発酵液をそれぞれ流通させて、20mAの電流を流した。この電気透析槽に生ごみペーストを流通させることにより、乾物ベースで生ごみ中に3.8重量%含まれていた食塩(NaCl)が1.5重量%に低下した[通電量に対する食塩除去量の割合(電流効率)は79%であった]。塩類の除去効率は良好であったが、電気透析槽への高圧輸送のため、本実験のポンプ所要出口圧は0.3kPaに達した。しかも電気透析槽への圧送のため、実験途中において電気透析槽から発酵液の漏出が生じた(これに対し、後述する本発明の実施例では、ポンプ所要圧力は通常0.1kPa以下である)。
Comparative Example 1
A micro sample of garbage (garbage paste) was directly electrodialyzed and then subjected to methane fermentation.
Garbage paste was passed through the dilution chamber of the electrodialysis tank and the fermentation broth was passed through the concentration chamber, respectively, and a current of 20 mA was passed. By circulating the garbage paste through this electrodialysis tank, the salt (NaCl) contained in the garbage on a dry matter basis was reduced to 1.5% by weight. Ratio (current efficiency) was 79%]. Although the salt removal efficiency was good, the required outlet pressure of the pump in this experiment reached 0.3 kPa because of high-pressure transport to the electrodialysis tank. Moreover, due to the pressure feeding to the electrodialysis tank, leakage of the fermentation broth occurred from the electrodialysis tank during the experiment (in contrast to this, in the examples of the present invention described later, the required pump pressure is usually 0.1 kPa or less). .
実施例1
図3に従い生ごみの処理を実施した。脱塩前の分別・微細化した生ごみを、消化タンクでメタン発酵処理し、この発酵液を濃縮槽で上澄みを分離し、調整槽で発酵液の酸化還元状態やpHの調整を行った後、電気透析槽を用いた脱塩実験を実施した。その結果、20mAの通電で乾物ベースの食塩含有量は3.0重量%から1.2重量%に減少した。このときの電流効率は62%と計算された。この透析処理を行っても肥料成分としての全窒素量、カリウム量の変化量(減少量)は10重量%以下であった。
Example 1
Garbage treatment was carried out according to FIG. After separating and refining raw garbage before desalting, methane fermentation treatment in the digestion tank, separating the supernatant in the concentration tank, and adjusting the redox state and pH of the fermentation liquid in the adjustment tank A desalting experiment using an electrodialysis tank was performed. As a result, the salt content of the dry matter base decreased from 3.0% by weight to 1.2% by weight with a current of 20 mA. The current efficiency at this time was calculated to be 62%. Even when this dialysis treatment was performed, the amount of change (decrease) in the amount of total nitrogen and potassium as fertilizer components was 10% by weight or less.
すなわち、過剰に共存した食塩成分(ナトリウムイオン、塩化物イオン)は優先的に電気透析によって除去され、より濃度の小さかったカリウムイオン等はほとんど除去されていなかった。この結果から、肥料として熟成させても、その有効性は維持できることが判った。 That is, salt components (sodium ions and chloride ions) coexisting excessively were preferentially removed by electrodialysis, and potassium ions having a lower concentration were hardly removed. From this result, it was found that the effectiveness can be maintained even when aging as a fertilizer.
実施例2および比較例2
図4に従い、豚糞尿の処理を実施した。まず、豚糞尿を一旦受槽に貯留した後、前処理槽に導入し、ここで破砕・ペースト化、前発酵などを実施した。前処理が済んだ豚糞尿は、消化タンクに導入し、メタン発酵させた。この発酵液を濃縮槽に導き、上澄みを分離した後、調整槽で5分間曝気処理し、さらに電気透析槽に導入して亜鉛の除去を検討した。電気透析槽で20mAの通電を行ったところ、発酵液中の亜鉛含有量は乾物ベースで0.02重量%から0.01重量%まで減少した(実施例2−1)。
Example 2 and Comparative Example 2
According to FIG. 4, pig manure was processed. First, swine manure was once stored in a receiving tank and then introduced into a pretreatment tank, where crushing / pasting, pre-fermentation, and the like were performed. The swine manure that had been pretreated was introduced into the digestion tank and fermented with methane. After this fermentation broth was introduced into a concentration tank and the supernatant was separated, it was subjected to aeration treatment for 5 minutes in an adjustment tank, and further introduced into an electrodialysis tank to examine the removal of zinc. When energization of 20 mA was performed in the electrodialysis tank, the zinc content in the fermentation broth decreased from 0.02 wt% to 0.01 wt% on a dry matter basis (Example 2-1).
一方、メタン発酵液に酸化還元電極を挿入し、その指示値が正の値を示すまで約8分間、曝気処理した場合についても並行して検討を行った(実施例2−2)。この液を同じく20mAの通電を行い電気透析槽で処理したところ、亜鉛含有量は、乾物ベースで0.005重量%まで減少した。 On the other hand, the case where an oxidation reduction electrode was inserted into the methane fermentation broth and aeration treatment was performed for about 8 minutes until the indicated value showed a positive value was also examined in parallel (Example 2-2). When this solution was similarly energized with 20 mA and treated in an electrodialysis tank, the zinc content was reduced to 0.005% by weight on a dry matter basis.
また、比較例2として、曝気処理を全くせずに電気透析処理を行った場合、亜鉛を除去することはできなかった。これは嫌気状態で硫化物イオンが生成し、亜鉛と結合して、そのイオン化を妨げたものと考えられた。 Further, as Comparative Example 2, when the electrodialysis treatment was performed without performing the aeration treatment at all, zinc could not be removed. This was thought to be because sulfide ions were generated in anaerobic conditions and bound to zinc, preventing its ionization.
実施例3
図5に従い、下水処理汚泥の処理を実施した。下水処理場の汚泥を消化タンクに導入し、メタン発酵処理した。この消化汚泥を濃縮槽で上澄み分離し、嫌気状態のまま電気透析槽に導入して脱金属処理した。電気透析槽では、20mAの通電を行ったところ、消化汚泥中の全ヒ素濃度が108ppmから5ppmに低減できた。
Example 3
According to FIG. 5, the sewage treatment sludge was treated. Sludge from the sewage treatment plant was introduced into the digestion tank and subjected to methane fermentation. The digested sludge was separated into the supernatant in a concentration tank and introduced into an electrodialysis tank in an anaerobic state for demetalization treatment. In the electrodialysis tank, when 20 mA was energized, the total arsenic concentration in the digested sludge could be reduced from 108 ppm to 5 ppm.
なお、電気透析処理前に消化汚泥を約1時間空気中に放置したものは、全ヒ素濃度が70ppmまでしか低減できなかった。約1時間空気中に放置した消化汚泥は、酸化還元電極電位が−50mV以上から−5mV程度まで正側に移行していた。このためヒ素の溶解性が低下したものと考えられた。 When the digested sludge was left in the air for about 1 hour before electrodialysis, the total arsenic concentration could only be reduced to 70 ppm. Digested sludge left in the air for about 1 hour had a redox electrode potential shifted to the positive side from −50 mV or more to about −5 mV. For this reason, it was considered that the solubility of arsenic was lowered.
実施例4
図6に従い、生ごみのメタン発酵処理および電析処理を実施した。実施例1と同様に前処理しメタン発酵させた発酵液について、濃縮槽で上澄み分離し、調整槽で酸化還元状態および/またはpHの調整を実施した後、電析槽に流通させた。
Example 4
According to FIG. 6, methane fermentation treatment and electrodeposition treatment of garbage were performed. The fermented liquor pretreated and fermented in methane in the same manner as in Example 1 was separated in the supernatant in the concentration tank, adjusted in the redox state and / or pH in the adjustment tank, and then passed through the electrodeposition tank.
電析槽の作用極側、対極側ともにメタン発酵液(スラリー)を流通させ20mAの通電を行った。電析によって電析槽出口側の亜鉛濃度は乾物ベースで0.002重量%以下となった。次に、電析槽に印加している直流電圧を逆にしたところ、一時的に、0.05%を超える亜鉛が溶出するのを観察した。これにより、電析・溶出処理によって、農地還元をする上で問題になるメタン発酵後の重金属類を処理、回収できることが明らかになった。 A methane fermentation broth (slurry) was circulated on both the working electrode side and the counter electrode side of the electrodeposition tank, and a current of 20 mA was applied. As a result of electrodeposition, the zinc concentration at the outlet of the electrodeposition tank was 0.002% by weight or less on a dry matter basis. Next, when the DC voltage applied to the electrodeposition tank was reversed, it was observed that zinc exceeding 0.05% was eluted temporarily. As a result, it has been clarified that heavy metals after methane fermentation can be treated and recovered by electrodeposition / elution treatment, which is a problem in reducing agricultural land.
以上、本発明を種々の実施形態に関して述べたが、本発明は上記実施形態に制約されるものではなく、特許請求の範囲に記載された発明の範囲内で、他の実施形態についても適用可能である。 The present invention has been described above with reference to various embodiments. However, the present invention is not limited to the above embodiments, and can be applied to other embodiments within the scope of the invention described in the claims. It is.
本発明のメタン発酵プロセスおよびメタン発酵システムは、有機性廃棄物をメタン発酵処理し、肥料化等を図る上で利用可能である。 The methane fermentation process and the methane fermentation system of the present invention can be used for methane fermentation treatment of organic waste to make fertilizer and the like.
Claims (1)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2003329281A JP4289454B2 (en) | 2003-09-22 | 2003-09-22 | Methane fermentation process and methane fermentation system |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2003329281A JP4289454B2 (en) | 2003-09-22 | 2003-09-22 | Methane fermentation process and methane fermentation system |
Publications (2)
Publication Number | Publication Date |
---|---|
JP2005087979A JP2005087979A (en) | 2005-04-07 |
JP4289454B2 true JP4289454B2 (en) | 2009-07-01 |
Family
ID=34458563
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP2003329281A Expired - Fee Related JP4289454B2 (en) | 2003-09-22 | 2003-09-22 | Methane fermentation process and methane fermentation system |
Country Status (1)
Country | Link |
---|---|
JP (1) | JP4289454B2 (en) |
Families Citing this family (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR100687095B1 (en) * | 2005-06-14 | 2007-02-26 | 한국전력기술 주식회사 | Electrodialysis reversal and electrochemical wastewater treatment process of compound containing nitrogen |
JP2007038185A (en) * | 2005-08-05 | 2007-02-15 | Kimigafuchigakuen Sojo Univ | Night soil treatment method |
JP4966523B2 (en) * | 2005-08-08 | 2012-07-04 | 株式会社タクマ | Biomass processing system |
JP4890825B2 (en) * | 2005-09-22 | 2012-03-07 | 三井造船環境エンジニアリング株式会社 | Method for recovering valuable materials from fermentation broth |
JP4654210B2 (en) * | 2007-03-14 | 2011-03-16 | 三井造船株式会社 | Method for recovering valuable materials from fermentation broth |
JP5872148B2 (en) * | 2010-03-31 | 2016-03-01 | 一般財団法人電力中央研究所 | Biological treatment method and method for producing microorganism group-supporting carrier |
JP2014087748A (en) * | 2012-10-30 | 2014-05-15 | Mitsui Eng & Shipbuild Co Ltd | Inter-liquid ion transfer method and inter-liquid ion transfer device |
CN113694732A (en) * | 2021-09-15 | 2021-11-26 | 上海理工大学 | System for efficiently recovering volatile fatty acid from mixed fermentation liquor in real time |
CN117259383B (en) * | 2023-10-30 | 2024-05-17 | 河南理工大学 | Organic solid waste treatment process |
-
2003
- 2003-09-22 JP JP2003329281A patent/JP4289454B2/en not_active Expired - Fee Related
Also Published As
Publication number | Publication date |
---|---|
JP2005087979A (en) | 2005-04-07 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP5127200B2 (en) | Wastewater treatment equipment containing ammonia nitrogen | |
Geng et al. | Thermal/alkaline pretreatment of waste activated sludge combined with a microbial fuel cell operated at alkaline pH for efficient energy recovery | |
JP4875864B2 (en) | Biomass processing system | |
US7892310B2 (en) | Biowaste treatment | |
JP4289454B2 (en) | Methane fermentation process and methane fermentation system | |
JP2000015231A (en) | Method for methane fermentation of organic waste | |
JP3554689B2 (en) | Waste disposal method | |
JP4817967B2 (en) | Organic waste processing method and organic waste processing apparatus | |
JP2005013909A (en) | Method of treating fermented product derived from organic waste and method of producing fodder | |
Zeng et al. | Recycling of acetate and ammonium from digestate for single cell protein production by a hybrid electrochemical-membrane fermentation process | |
Moset et al. | Anaerobic digestion of sulfate-acidified cattle slurry: One-stage vs. two-stage | |
JP2006314920A (en) | Method for recovering energy from biomass | |
JP5230243B2 (en) | Method and system for methane fermentation treatment of organic waste | |
JP2007044572A (en) | Method and system for treating organic waste | |
JP3512342B2 (en) | Cleaning method for separation membrane | |
JP2006218422A (en) | Process for treating organic waste and apparatus for the same | |
JP4488794B2 (en) | Method and system for treating fermentation residual liquid and other anaerobic organic compound-containing liquid | |
JP2005144361A (en) | Organic waste treating method | |
JP4182355B2 (en) | Organic waste processing method and organic waste processing apparatus | |
JP2005087977A (en) | Organic waste treatment method and organic waste treatment system | |
JP3727178B2 (en) | Methane fermentation method | |
CN103435240A (en) | Fermentation and re-dewatering method of dewatered sludge | |
JP2004298688A (en) | Method for treating organic waste, biogas system and method for producing methane fermentation residual liquid concentrate | |
JP5301788B2 (en) | Co-fermentation method | |
JP2005193122A (en) | Anaerobic hydrogen fermentation treatment system |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20060531 |
|
A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20080723 |
|
A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20080806 |
|
A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20081006 |
|
TRDD | Decision of grant or rejection written | ||
A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20090318 |
|
A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 |
|
A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20090324 |
|
R150 | Certificate of patent or registration of utility model |
Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120410 Year of fee payment: 3 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120410 Year of fee payment: 3 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130410 Year of fee payment: 4 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130410 Year of fee payment: 4 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20140410 Year of fee payment: 5 |
|
R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
S111 | Request for change of ownership or part of ownership |
Free format text: JAPANESE INTERMEDIATE CODE: R313117 |
|
R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
S533 | Written request for registration of change of name |
Free format text: JAPANESE INTERMEDIATE CODE: R313533 |
|
R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
LAPS | Cancellation because of no payment of annual fees |