JP5696310B1 - Sludge nutrient recovery method, algae culture method, and algae culture system - Google Patents
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Abstract
【課題】メイラード反応や単糖類の過分解反応を回避して、汚泥から単糖類を高収率で得ることができる汚泥の栄養分回収方法、藻類の培養方法、および藻類培養システムを提供する。【解決手段】多糖類を含む汚泥を、１７０℃乃至２３０℃で１０分乃至７０分間、熱水処理した後、その処理物から固体成分の一部または全部を回収し、回収した固体成分に対して、酸または酵素で加水分解することにより糖化を行う。得られた糖化後の液体を使用して、従属栄養性藻類などの藻類の培養を行う。また、熱水処理後の処理物から液体成分の一部または全部を回収し、その液体成分を使用して藻類の培養を行ってもよい。【選択図】図１The present invention provides a sludge nutrient recovery method, algae culture method, and an algae culture system capable of obtaining monosaccharides from sludge in high yield while avoiding Maillard reaction and monosaccharide overdegradation reaction. SOLUTION: Sludge containing polysaccharides is hydrothermally treated at 170 ° C. to 230 ° C. for 10 minutes to 70 minutes, and then part or all of the solid components are recovered from the treated product, and the recovered solid components are recovered. Then, saccharification is carried out by hydrolysis with acid or enzyme. The obtained saccharified liquid is used to culture algae such as heterotrophic algae. Alternatively, a part or all of the liquid component may be recovered from the processed product after the hot water treatment, and the algae may be cultured using the liquid component. [Selection] Figure 1
Description
本発明は、汚泥の栄養分回収方法、藻類の培養方法、および藻類培養システムに関する。 The present invention relates to a sludge nutrient recovery method, an algal culture method, and an algal culture system.
従来、汚泥から栄養分を分離回収し、その栄養分を使用して藻類を培養する方法として、余剰汚泥や活性汚泥、有機汚泥に含まれる微生物を、加熱処理、粉砕処理またはオゾン処理して可溶化し、その可溶化された液体成分を使用して従属栄養性藻類を培養するもの（例えば、特許文献１または２参照）や、生汚泥や余剰汚泥を消化処理し、処理後に得られる消化汚泥脱離液を電界パルスを用いて殺菌処理した後、得られた栄養塩含有液を培養液として微細藻類を培養するもの（例えば、特許文献３参照）がある。また、下水汚泥を可溶化する方法として、２００〜２５０℃の亜臨界水で汚泥を高効率に可溶化できる技術が開示されている（例えば、非特許文献１参照）。 Conventionally, as a method of separating and recovering nutrients from sludge and culturing algae using the nutrients, microorganisms contained in excess sludge, activated sludge, and organic sludge are solubilized by heat treatment, pulverization treatment, or ozone treatment. , Those that cultivate heterotrophic algae using the solubilized liquid component (see, for example, Patent Document 1 or 2), digestion treatment of raw sludge and excess sludge, and digestion sludge desorption obtained after treatment There is one that cultivates microalgae using the obtained nutrient-containing solution as a culture solution after sterilizing the solution using an electric field pulse (for example, see Patent Document 3). Moreover, as a method for solubilizing sewage sludge, a technique capable of solubilizing sludge with subcritical water at 200 to 250 ° C. with high efficiency is disclosed (for example, see Non-Patent Document 1).
なお、多糖類を分解して単糖類を得る糖化の方法として、多糖類を濃硫酸で加水分解してオリゴ糖（オリゴマー）に分解し、さらに希硫酸で加水分解して単糖類に分解する方法が利用されている（例えば、非特許文献２参照）。 As a saccharification method for degrading polysaccharides to obtain monosaccharides, polysaccharides are hydrolyzed with concentrated sulfuric acid to decompose into oligosaccharides (oligomers), and then further hydrolyzed with dilute sulfuric acid to decompose into monosaccharides. Is used (see, for example, Non-Patent Document 2).
特許文献１および２に記載の方法では、微生物を可溶化しているため、従属栄養性藻類の栄養源として重要な単糖類が得られないことが多いという課題があった。特許文献３に記載の方法では、消化処理後の消化汚泥脱離液には有機成分が乏しく、やはり単糖類がほとんど得られないという課題があった。非特許文献１に記載の方法では、亜臨界水処理によって可溶化が進むものの、条件によっては可溶化液中の単糖類の過分解反応が進行し、単糖類が分解してしまうという課題があった。また、汚泥の分解により生成したアミノ酸と単糖類とによりメイラード反応が進行するため、場合によってはその後の藻類の培養を阻害するおそれがあるという課題もあった。 In the methods described in Patent Documents 1 and 2, since microorganisms are solubilized, there is a problem that monosaccharides that are important as nutrient sources for heterotrophic algae are often not obtained. In the method described in Patent Document 3, the digested sludge detachment liquid after digestion has a problem that organic components are scarce and monosaccharides are hardly obtained. In the method described in Non-Patent Document 1, although the solubilization proceeds by the subcritical water treatment, there is a problem that depending on the conditions, the monosaccharides in the solubilized solution may undergo excessive decomposition and the monosaccharides are decomposed. It was. In addition, since the Maillard reaction proceeds with amino acids and monosaccharides generated by the decomposition of sludge, there is a problem that the culture of algae thereafter may be inhibited in some cases.
本発明は、このような課題に着目してなされたもので、メイラード反応や単糖類の過分解反応を回避して、汚泥から単糖類を高収率で得ることができる汚泥の栄養分回収方法、藻類の培養方法、および藻類培養システムを提供することを目的とする。 The present invention was made paying attention to such a problem, avoiding Maillard reaction and monosaccharide overdecomposition reaction, the sludge nutrient recovery method capable of obtaining monosaccharides in high yield from sludge, It is an object of the present invention to provide an algal culture method and an algal culture system.
上記目的を達成するために、本発明に係る汚泥の栄養分回収方法は、多糖類を含む汚泥を、２００℃より高く２３０℃以下の温度で１０分乃至３０分間、熱水処理した後、その処理物から固体成分の一部または全部を回収（例えば、分離回収）し、回収した固体成分に対して糖化を行うことを特徴とする。
In order to achieve the above-described object, the method for recovering sludge nutrients according to the present invention includes treating hydrous sludge containing polysaccharides at a temperature higher than 200 ° C. and not higher than 230 ° C. for 10 to 30 minutes, and then treating the sludge. A part or all of the solid component is recovered (for example, separated and recovered) from the product, and the recovered solid component is saccharified.
本発明に係る汚泥の栄養分回収方法では、多糖類を含む汚泥を熱水処理することにより、可溶化しやすいタンパク質等がアミノ酸になり、さらにアミノ酸からアンモニアになって、処理物の液体内に溶解する。また、汚泥中のリンもリン酸になり、液体内に溶解する。このため、熱水処理の処理物から固体成分の一部または全部を回収（分離回収）することにより、多糖類が多く含まれる固体成分を回収することができる。なお、固体成分を回収するためには、例えば、ろ過などの固液分離手段を用いてもよい。この場合、処理物から固体成分と液体成分とを分離回収することができる。また、液体成分は、アミノ酸等が含まれるため、栄養分として、例えば藻類などの培養に用いることができる。また、汚泥中に重金属等が含まれる場合には、重金属等が液体成分中に抽出されるため、固体成分からそれらを取り除くことができる。 In the sludge nutrient recovery method according to the present invention, by subjecting the sludge containing polysaccharides to hydrothermal treatment, proteins that are easily solubilized become amino acids, and further, amino acids are converted into ammonia and dissolved in the liquid of the treated product. To do. Moreover, phosphorus in sludge also becomes phosphoric acid and dissolves in the liquid. For this reason, it is possible to recover a solid component containing a large amount of polysaccharides by recovering (separating and recovering) part or all of the solid component from the processed product of the hot water treatment. In addition, in order to collect | recover a solid component, you may use solid-liquid separation means, such as filtration, for example. In this case, the solid component and the liquid component can be separated and recovered from the processed product. Moreover, since a liquid component contains an amino acid etc., it can be used for culture | cultivation of algae etc. as a nutrient, for example. Moreover, when heavy metals etc. are contained in sludge, since heavy metals etc. are extracted in a liquid component, they can be removed from a solid component.
本発明に係る汚泥の栄養分回収方法は、多糖類から単糖類への分解反応が生じないため、液体成分中に単糖類が溶解せず、メイラード反応や単糖類の過分解反応を回避することができる。また、固体成分中に多糖類をそのまま残すことができる。本発明に係る汚泥の栄養分回収方法は、特に、前記熱水処理による汚泥の可溶化率が２０乃至３５％となるよう、前記熱水処理を行うことが好ましい。なお、前記熱水処理は、１７０℃乃至２３０℃で１０分乃至７０分間としてもよい。
Nutrient recovery method of sludge according to the present invention, the decomposition reaction of the polysaccharide to the monosaccharide does not occur, monosaccharides not dissolved in the liquid component, is possible to avoid excessive decomposition reaction of the Maillard reaction and monosaccharides it can. Moreover, the polysaccharide can be left as it is in the solid component. In the sludge nutrient recovery method according to the present invention, the hot water treatment is particularly preferably performed so that the sludge solubilization rate by the hot water treatment is 20 to 35%. The hot water treatment may be performed at 170 ° C. to 230 ° C. for 10 minutes to 70 minutes.
本発明に係る汚泥の栄養分回収方法は、熱水処理の処理物から回収（分離回収）した固体成分に繊維質の多糖類が多く含まれるため、この固体成分に対して糖化を行うことにより、高収率かつ効率的に単糖類やオリゴ糖を得ることができる。このとき、アミノ酸等が含まれる液体成分と分離されているため、得られた単糖類とアミノ酸によるメイラード反応を回避することができる。得られた単糖類やオリゴ糖は、栄養源として、例えば藻類などの培養に用いることができる。 In the sludge nutrient recovery method according to the present invention, since a large amount of fibrous polysaccharide is contained in the solid component recovered (separated and recovered) from the processed product of the hot water treatment, by saccharifying the solid component, Monosaccharides and oligosaccharides can be obtained with high yield and efficiency. At this time, since it is separated from the liquid component containing amino acid or the like, Maillard reaction by the obtained monosaccharide and amino acid can be avoided. The obtained monosaccharide or oligosaccharide can be used as a nutrient source, for example, for culturing algae or the like.
本発明に係る汚泥の栄養分回収方法は、酸または酵素で加水分解することにより、前記糖化を行うことが好ましい。この場合、例えば非特許文献２に記載の方法などの既存の糖化方法を用いてもよく、容易に実用化することができる。 In the sludge nutrient recovery method according to the present invention, the saccharification is preferably performed by hydrolysis with an acid or an enzyme. In this case, for example, an existing saccharification method such as the method described in Non-Patent Document 2 may be used and can be easily put into practical use.
本発明に係る汚泥の栄養分回収方法で、汚泥は、例えば下水汚泥、余剰汚泥、活性汚泥、有機汚泥、脱水汚泥、生汚泥など、多糖類を含むものであればいかなるものであってもよい。下水の中にはトイレットペーパーなどの繊維質の多糖類（セルロース）が多く含まれているため、特に下水汚泥からなることが好ましい。 In the sludge nutrient recovery method according to the present invention, the sludge may be any as long as it contains polysaccharides, such as sewage sludge, excess sludge, activated sludge, organic sludge, dehydrated sludge, and raw sludge. Since sewage contains a large amount of fibrous polysaccharides (cellulose) such as toilet paper, it is particularly preferable to be made of sewage sludge.
本発明に係る汚泥の栄養分回収方法で、前記汚泥は下水汚泥から成り、その下水汚泥を処理する下水処理場から発生する熱を利用して、前記熱水処理を行うことが好ましい。この場合、熱水処理のための専用の熱源が不要となり、運転コストを低減することができる。下水処理場では、膨大な量の汚泥が毎日発生しており、この汚泥の多くが焼却処理され、膨大な燃焼エネルギーを発生している。燃焼エネルギーの一部は、焼却炉に流入する空気の加熱源として空気予熱器で熱回収される他に、廃熱ボイラーの熱源にもなっている。例えば、この熱の一部を取り出して、熱水処理の熱源として利用することができる。また、空気予熱器内に熱交換器を設置することにより、熱水処理の熱源を賄うこともできる。 In the sludge nutrient recovery method according to the present invention, the sludge is preferably sewage sludge, and the hydrothermal treatment is preferably performed using heat generated from a sewage treatment plant that treats the sewage sludge. In this case, a dedicated heat source for the hot water treatment becomes unnecessary, and the operation cost can be reduced. A huge amount of sludge is generated every day at a sewage treatment plant, and most of the sludge is incinerated to generate a huge amount of combustion energy. A part of the combustion energy is not only recovered by the air preheater as a heating source of the air flowing into the incinerator but also a heat source of the waste heat boiler. For example, a part of this heat can be taken out and used as a heat source for hydrothermal treatment. Moreover, the heat source of a hot-water process can also be covered by installing a heat exchanger in an air preheater.
本発明に係る藻類の培養方法は、多糖類を含む汚泥を熱水処理した後、その処理物から固体成分の一部または全部を回収し、回収した固体成分に対して糖化を行い、前記糖化後の液体を使用して、藻類の培養を行うことを特徴とする。また、本発明に係る藻類の培養方法は、本発明に係る汚泥の栄養分回収方法により得られる前記糖化後の液体を使用して、藻類の培養を行ってもよい。また、前記熱水処理は、１７０℃乃至２３０℃で１０分乃至７０分間行ってもよい。また、前記熱水処理による汚泥の可溶化率が２０乃至３５％となるよう、前記熱水処理を行ってもよい。また、酸または酵素で加水分解することにより、前記糖化を行ってもよい。また、前記汚泥は下水汚泥から成り、その下水汚泥を処理する下水処理場から発生する熱を利用して、前記熱水処理を行ってもよい。
In the method for culturing algae according to the present invention, after sludge containing polysaccharides is hydrothermally treated, a part or all of the solid component is recovered from the treated product, the recovered solid component is saccharified, and the saccharification is performed. The algae is cultured using the later liquid. In the method for culturing algae according to the present invention, the algae may be cultured using the saccharified liquid obtained by the sludge nutrient recovery method according to the present invention . The hot water treatment may be performed at 170 ° C. to 230 ° C. for 10 minutes to 70 minutes. Moreover, you may perform the said hot water treatment so that the solubilization rate of the sludge by the said hot water treatment may be 20 to 35%. Moreover, you may perform the said saccharification by hydrolyzing with an acid or an enzyme. The sludge may be sewage sludge, and the hot water treatment may be performed using heat generated from a sewage treatment plant that treats the sewage sludge.
本発明に係る藻類の培養方法では、糖化後の液体にはブドウ糖などの単糖類やオリゴ糖が多く含まれているため、栄養源として、藻類の培養に利用することができる。特に、従属栄養性藻類の培養に利用すると効果的である。 In the method for culturing algae according to the present invention, since the liquid after saccharification contains a large amount of monosaccharides and oligosaccharides such as glucose, it can be used for culturing algae as a nutrient source. In particular, it is effective when used for culturing heterotrophic algae.
本発明に係る藻類の培養方法は、前記熱水処理後の処理物から液体成分の一部または全部を回収（例えば、分離回収）し、その液体成分を使用して藻類の培養を行うことが好ましい。この場合、熱水処理後の処理物から回収（分離回収）した液体成分には、アミノ酸やアンモニアなどの窒素化合物や、リン酸などの栄養分が多く含まれているため、栄養源として、独立栄養性藻類などの藻類の培養に幅広く利用することができる。また、熱水処理後の液体成分を、糖化後の液体と混合して、藻類の培養に使用してもよい。 In the method for culturing algae according to the present invention, a part or all of a liquid component is recovered (for example, separated and recovered) from the processed product after the hot water treatment, and the algae is cultured using the liquid component. preferable. In this case, the liquid component recovered (separated and recovered) from the treated product after hot water treatment contains a large amount of nutrients such as nitrogen compounds such as amino acids and ammonia, and phosphoric acid. It can be widely used for culturing algae such as algae. Further, the liquid component after the hot water treatment may be mixed with the liquid after saccharification and used for algae culture.
本発明に係る藻類培養システムは、多糖類を含む汚泥に対して熱水処理を行う熱水処理手段と、前記熱水処理手段の処理物から固体成分の一部または全部を回収（例えば、分離回収）する固体回収手段と、前記固体回収手段で回収した固体成分に対して糖化を行う糖化手段と、前記糖化手段による糖化後の液体を使用して、藻類を培養可能に設けられた第一培養手段とを、有することを特徴とする。 The algae culture system according to the present invention includes a hydrothermal treatment means for performing hydrothermal treatment on sludge containing polysaccharides, and collects a part or all of the solid components from the processed product of the hydrothermal treatment means (for example, separation) A solid recovery means for recovering), a saccharification means for saccharifying the solid component recovered by the solid recovery means, and a first cultivated algae using the liquid after saccharification by the saccharification means And a culture means.
本発明に係る藻類培養システムは、本発明に係る汚泥の栄養分回収方法および藻類の培養方法を実施することができ、それらによる作用効果を得ることができる。すなわち、本発明に係る藻類培養システムは、多糖類を含む汚泥を熱水処理手段で熱水処理することにより、可溶化しやすいタンパク質等をアミノ酸にし、さらにアミノ酸からアンモニアにして、処理物の液体中に溶解させることができる。また、汚泥中のリンをリン酸にして、液体中に溶解させることができる。このため、固体回収手段により、固体成分の一部または全部を回収することにより、多糖類が多く含まれる固体成分を回収することができる。 The algae culture system according to the present invention can carry out the sludge nutrient recovery method and the algae culture method according to the present invention, and can obtain the operational effects thereof. That is, in the algal culture system according to the present invention, the sludge containing polysaccharides is hydrothermally treated with hydrothermal treatment means to convert solubilized proteins into amino acids, and further from amino acids to ammonia, and the liquid of the treated product. Can be dissolved in. Moreover, phosphorus in sludge can be converted into phosphoric acid and dissolved in a liquid. For this reason, the solid component rich in polysaccharide can be recovered by recovering a part or all of the solid component by the solid recovery means.
また、本発明に係る藻類培養システムは、固体回収手段で回収した固体成分に繊維質の多糖類が多く含まれるため、この固体成分に対して糖化手段で糖化を行うことにより、高収率かつ効率的に単糖類やオリゴ糖を得ることができる。このとき、アミノ酸等が含まれる液体成分と分離されているため、得られた単糖類とアミノ酸によるメイラード反応を回避することができる。得られた単糖類やオリゴ糖は、第一培養手段により、栄養源として、例えば従属栄養性藻類などの藻類の培養に用いることができる。 In addition, since the algae culture system according to the present invention contains a large amount of fibrous polysaccharide in the solid component recovered by the solid recovery means, by performing saccharification on the solid component by the saccharification means, high yield and Monosaccharides and oligosaccharides can be obtained efficiently. At this time, since it is separated from the liquid component containing amino acid or the like, Maillard reaction by the obtained monosaccharide and amino acid can be avoided. The obtained monosaccharide or oligosaccharide can be used as a nutrient source by the first culture means, for example, for culturing algae such as heterotrophic algae.
本発明に係る藻類培養システムは、前記熱水処理手段の処理物から液体成分の一部または全部を回収（例えば、分離回収）する液体回収手段と、前記液体回収手段で回収した液体成分を使用して、藻類を培養可能に設けられた第二培養手段とを、有することが好ましい。この場合、液体回収手段で回収した液体成分には、アミノ酸やアンモニアなどの窒素化合物や、リン酸などの栄養分が多く含まれているため、第二培養手段により、栄養源として、独立栄養性藻類などの藻類の培養に幅広く利用することができる。 The algae culture system according to the present invention uses a liquid recovery means for recovering (for example, separating and recovering) part or all of the liquid component from the processed product of the hot water treatment means, and the liquid component recovered by the liquid recovery means. And it is preferable to have a 2nd culture means provided so that algae can be culture | cultivated. In this case, the liquid component recovered by the liquid recovery means contains a large amount of nutrients such as nitrogen compounds such as amino acids and ammonia and phosphoric acid. It can be widely used for culturing algae such as.
本発明によれば、メイラード反応や単糖類の過分解反応を回避して、汚泥から単糖類を高収率で得ることができる汚泥の栄養分回収方法、藻類の培養方法、および藻類培養システムを提供することができる。 ADVANTAGE OF THE INVENTION According to this invention, the nutrient recovery method of the sludge which can avoid the Maillard reaction and the hyperdecomposition reaction of a monosaccharide, and can obtain a monosaccharide from sludge with a high yield, the culture method of algae, and an algal culture system can do.
以下、汚泥の熱水処理実験、固体成分の糖化実験および藻類の培養実験の実験結果に基づいて、本発明の実施の形態の汚泥の栄養分回収方法、藻類の培養方法、および藻類培養システムの構成、作用効果について説明する。図１に、本発明の実施の形態の汚泥の栄養分回収方法および藻類の培養方法のフローチャートを示す。 Hereinafter, based on experimental results of sludge hydrothermal treatment experiment, solid component saccharification experiment and algae culture experiment, sludge nutrient recovery method, algae culture method, and algae culture system configuration of the embodiment of the present invention The effect will be described. FIG. 1 shows a flowchart of a sludge nutrient recovery method and algae culture method according to an embodiment of the present invention.
［汚泥の熱水処理実験］
図１に示す、下水汚泥を熱水処理する工程に関して、以下の実験を行った。
様々な反応温度および反応時間で汚泥の熱水処理を行い、反応温度および反応時間が、分離回収された液体成分の収率（可溶化率）や液体成分中の栄養分の収率に与える影響について検討を行った。汚泥として、下水汚泥を仙台市南蒲生浄化センターで処理して生成された脱水汚泥を用いた。資料による脱水汚泥の性状については、含水率７６．７％（固形分２３．３％）、可燃分８５．７％（灰分１４．３％）、高位発熱量１９ＭＪ／ｋｇ・ＤＳである。
[Sludge hydrothermal treatment experiment]
The following experiment was conducted on the process of hydrothermal treatment of sewage sludge shown in FIG.
About sludge hydrothermal treatment at various reaction temperatures and reaction times, and the effect of reaction temperature and reaction time on the yield (solubilization rate) of separated and recovered liquid components and nutrients in liquid components Study was carried out. As the sludge, dewatered sludge produced by treating sewage sludge at the Sendai City Nansei Purification Center was used. The properties of the dewatered sludge according to the materials are a moisture content of 76.7% (solid content: 23.3%), a combustible content of 85.7% (ash content: 14.3%), and a high heating value of 19 MJ / kg · DS.
なお、以下の実験では、全有機炭素（ＴＯＣ）・全窒素（ＴＮ）分析には、(株)島津製作所社製「TOC-V CSN」および「ユニットTMN-1」を、全リン全窒素および形態別リン窒素分析には、ビーエルテック(株）社製「Auto Analyzer II」および「QuAAtro 2HR」を用いた。また、固体の元素分析には、パーキンエルマー Inc.社製「2400II」を、汚泥の灰分測定には、エスアイアイ・ナノテクノロジー(株)製「TG/DTA6200」を用いた。また、ＨＰＬＣ分析は、カラムとして昭和電工(株)社製「Shodex SH1011」を用い、カラム温度を６０℃とし、溶媒として０．０１Ｎの硫酸水溶液を用い、流量を１．０ｍｌ／ｍｉｎとして、示差屈折率（ＲＩ）検出器を用いて測定を行った。 In the following experiment, for total organic carbon (TOC) and total nitrogen (TN) analysis, “TOC-V CSN” and “Unit TMN-1” manufactured by Shimadzu Corporation were used. “Auto Analyzer II” and “QuAAtro 2HR” manufactured by LB Tech Co., Ltd. were used for the analysis of phosphorus nitrogen according to form. In addition, “2400II” manufactured by Perkin Elmer Inc. was used for elemental analysis of solids, and “TG / DTA6200” manufactured by SII Nanotechnology Co., Ltd. was used for ash content measurement of sludge. In addition, HPLC analysis uses “Shodex SH1011” manufactured by Showa Denko KK as a column, a column temperature of 60 ° C., a 0.01 N sulfuric acid aqueous solution as a solvent, a flow rate of 1.0 ml / min, and a differential. Measurements were made using a refractive index (RI) detector.
試料の脱水汚泥を、高圧蒸気滅菌器（アルプ(株)社製「IT-2346」）により滅菌し、蒸留水による洗浄および遠心分離の後、その固形分を凍結乾燥器（東京理化器械(株)社製「FDU-1200」）により凍結乾燥した。さらに、塊状となった乾燥汚泥を、市販のカッターミルおよび転動ボールミル（(株)アサヒ理化製作所社製「ボールミル回転架台AV-1型」、(株)ニッカトー社製「HDポットミルType A-3」）でワタ状に粉砕し、実験用の試料を作成した。このワタ状の脱水汚泥の元素組成は、炭素（Ｃ）４２．８％、水素（Ｈ）６．８％、窒素（Ｎ）３．５％、リン（Ｐ）０．７％である。また、灰分は、９．８ｗｔ％である。 The dehydrated sludge of the sample is sterilized with a high-pressure steam sterilizer ("IT-2346" manufactured by Alp Co., Ltd.), washed with distilled water and centrifuged, and the solid content is freeze-dried (Tokyo Rika Kikai Co., Ltd.) Lyophilized by “FDU-1200”). In addition, the dried sludge that has become agglomerated, the commercially available cutter mill and rolling ball mill ("ball mill rotating stand AV-1 type" manufactured by Asahi Rika Seisakusho Co., Ltd., "HD pot mill Type A-3 manufactured by Nikkato Co., Ltd.) )) To obtain a test sample. The elemental composition of this cotton-like dewatered sludge is 42.8% carbon (C), 6.8% hydrogen (H), 3.5% nitrogen (N), and 0.7% phosphorus (P). The ash content is 9.8 wt%.
図２に示すように、ワタ状の脱水汚泥３ｇと超純水８０ｇとを、回分式反応器（スウェージロック Co.社製「316L-HDF4-150」；体積150mL、SUS316製）１１に仕込み、回分式反応器１１の内部の空気をアルゴンガスで置換した。なお、超純水（高純度の蒸留水）は、超純水製造装置（アドバンテック東洋(株)社製「CPW-100」）で製造したものを用いた。ガス置換後、回分式反応器１１の両端をキャップおよびプラグで密閉し、高温状態となったサンドバス（エイクラフト社製「SB160T-L」）１２に投入した。 As shown in FIG. 2, 3 g of cotton-like dewatered sludge and 80 g of ultrapure water were charged into a batch reactor (“316L-HDF4-150” manufactured by Swagelok Co .; volume 150 mL, made of SUS316) 11 and batched. The air inside the reactor 11 was replaced with argon gas. The ultrapure water (high purity distilled water) used was an ultrapure water production apparatus (“CPW-100” manufactured by Advantech Toyo Co., Ltd.). After the gas replacement, both ends of the batch reactor 11 were sealed with caps and plugs, and charged into a sand bath 12 (“SB160T-L” manufactured by Aicraft Co., Ltd.) 12 in a high temperature state.
サンドバス１２は、マントルヒータ１３によって加熱され、熱電対１４により内部の温度を測定して、温度が一定になるようにマントルヒータ１３の出力が自動調整されるようになっている。回分式反応器１１の内部の温度は、サンドバス１２からの加熱により上昇を始め、数分程度の昇温過程を経て反応温度に到達するようになっている。なお、回分式反応器１１の内部の温度上昇にともない、回分式反応器１１の内部の水の飽和蒸気圧とアルゴンガスの圧力とを全圧とする、回分式反応器１１の内部圧力も上昇する。 The sand bath 12 is heated by a mantle heater 13, the internal temperature is measured by a thermocouple 14, and the output of the mantle heater 13 is automatically adjusted so that the temperature becomes constant. The temperature inside the batch reactor 11 starts to rise by heating from the sand bath 12, and reaches the reaction temperature through a temperature rising process of about several minutes. As the temperature inside the batch reactor 11 rises, the internal pressure of the batch reactor 11 increases with the saturated vapor pressure of water inside the batch reactor 11 and the pressure of argon gas as the total pressure. To do.
実験では、熱水処理の反応温度を、１２０℃、１５０℃、１８０℃、２００℃、２２５℃、２５０℃、２７５℃の７通り、反応時間（昇温過程の時間も含む）を、１５分、３０分、４５分、６０分、１５０分の５通りとした。また、加熱中に、サンドバス１２の内部の回分式反応器１１を上下に揺らして、回分式反応器１１の内部の撹拌を促した。反応時間終了後、すばやく回分式反応器１１をサンドバス１２から取り出し、水浴に投入して反応を停止させた。その後、回分式反応器１１を開けて、超純水で洗浄しながら、内容物（処理物）を回収した。回収した処理物を、ろ過操作（メルク(株)社製、0.2μm）で液体成分と固体成分（残渣）とに分離した。 In the experiment, the reaction temperature of the hot water treatment was set to seven types of 120 ° C., 150 ° C., 180 ° C., 200 ° C., 225 ° C., 250 ° C., and 275 ° C., and the reaction time (including the temperature raising process time) was 15 minutes. , 30 minutes, 45 minutes, 60 minutes, and 150 minutes. In addition, during the heating, the batch reactor 11 inside the sand bath 12 was shaken up and down to promote stirring inside the batch reactor 11. After completion of the reaction time, the batch reactor 11 was quickly taken out from the sand bath 12 and put into a water bath to stop the reaction. Thereafter, the batch reactor 11 was opened, and the contents (processed product) were collected while washing with ultrapure water. The collected treated product was separated into a liquid component and a solid component (residue) by a filtration operation (Merck Co., Ltd., 0.2 μm).
表１〜表３に、反応時間２２５℃以上のときの液体成分の収率（可溶化率）ならびに、液体成分（可溶化液）および固体成分（残渣）中の各成分の収率等を、表４に、反応時間２００℃以下のときの液体成分の収率（可溶化率）ならびに、液体成分（可溶化液）中の各成分の収率を示す。また、反応時間１５分のときの可溶化率の温度依存性を、図３に示す。なお、固形成分である残渣については、６０℃で３日間乾燥した後、乾燥重量測定、元素分析、全リン全窒素分析を行った。また、各成分の値は、熱水処理前のワタ状の脱水汚泥の元素組成を基準（１００％）としている。 In Tables 1 to 3, the yield (solubilization rate) of the liquid component when the reaction time is 225 ° C. or higher, the yield of each component in the liquid component (solubilization liquid) and the solid component (residue), etc. Table 4 shows the yield (solubilization rate) of the liquid component when the reaction time is 200 ° C. or less, and the yield of each component in the liquid component (solubilization solution). Moreover, the temperature dependence of the solubilization rate when the reaction time is 15 minutes is shown in FIG. In addition, about the residue which is a solid component, after drying at 60 degreeC for 3 days, the dry weight measurement, the elemental analysis, and the total phosphorus total nitrogen analysis were performed. Moreover, the value of each component is based on the elemental composition of cotton-like dewatered sludge before hot water treatment (100%).
なお、可溶化率Ｘは、以下の式で定義したものである。
表１および図３に示すように、反応温度２２５〜２７５℃、反応時間１５〜６０分では、脱水汚泥の可溶化率Ｘは、２７〜６７％の範囲であった。また、表４および図３に示すように、反応時間１５分のとき、反応温度１８０℃、２００℃では可溶化率が１０％強であり、充分に可溶化されていないことが確認された。 As shown in Table 1 and FIG. 3, at a reaction temperature of 225 to 275 ° C. and a reaction time of 15 to 60 minutes, the dewatered sludge solubilization rate X was in the range of 27 to 67%. Further, as shown in Table 4 and FIG. 3, when the reaction time was 15 minutes, the solubilization rate was slightly over 10% at the reaction temperature of 180 ° C. and 200 ° C., and it was confirmed that the solution was not sufficiently solubilized.
表１に示すように、反応温度２２５〜２７５℃、反応時間１５〜６０分では、可溶化液の中に約２０〜３０％の炭素が回収されていることが確認された。また、表４に示すように、反応温度２００℃以下では、可溶化液中に１５％以下の炭素しか回収されないことも確認された。表１に示すように、可溶化液の炭素量と残渣の炭素量との合計は、反応温度２２５℃では、いずれの反応時間でも９０％を超えているものの、反応温度２７５℃で反応時間３０分以上では、８０％未満となっている。このことから、反応温度２７５℃で反応時間が長くなると、二酸化炭素などのガスが発生することが示唆される。また、表１に示すように、残渣中の炭素・酸素組成の値を比較すると、反応温度２７５℃では、反応時間が長くなると炭素組成の上昇、酸素組成の低下が認められる。このことからも、炭化反応の進行が示唆される。 As shown in Table 1, it was confirmed that about 20 to 30% of carbon was recovered in the solubilized solution at a reaction temperature of 225 to 275 ° C. and a reaction time of 15 to 60 minutes. Further, as shown in Table 4, it was also confirmed that only 15% or less of carbon was recovered in the solubilized solution at a reaction temperature of 200 ° C. or lower. As shown in Table 1, the total of the carbon amount of the solubilized liquid and the carbon amount of the residue exceeds 90% at any reaction time at the reaction temperature of 225 ° C., but the reaction time is 30 at the reaction temperature of 275 ° C. For minutes or more, it is less than 80%. This suggests that when the reaction time is long at a reaction temperature of 275 ° C., a gas such as carbon dioxide is generated. Further, as shown in Table 1, when the values of the carbon / oxygen composition in the residue are compared, at the reaction temperature of 275 ° C., an increase in the carbon composition and a decrease in the oxygen composition are observed as the reaction time becomes longer. This also suggests the progress of the carbonization reaction.
表２に示すように、反応温度２２５〜２７５℃、反応時間１５〜６０分では、脱水汚泥の中に含まれる約５０〜７０％の窒素分を可溶化液中に回収できることが確認された。また、表４に示すように、反応温度２００℃のときには反応時間を３０分以上、反応温度１８０℃のときには反応時間を６０分以上にすることにより、脱水汚泥中の５０％以上の窒素分を可溶化液中に回収できることが確認された。表２に示すように、可溶化液中の窒素の形態としては、アンモニアが１０％強（可溶化液中の窒素量を基準にすれば約２０％）と比較的多く、亜硝酸や硝酸イオンはほぼ無視できる量しかないことが確認された。表２から、他の多くは、アミノ酸などの有機窒素化合物であると考えられる。 As shown in Table 2, it was confirmed that about 50 to 70% nitrogen contained in the dewatered sludge can be recovered in the solubilized liquid at a reaction temperature of 225 to 275 ° C. and a reaction time of 15 to 60 minutes. Further, as shown in Table 4, when the reaction temperature is 200 ° C., the reaction time is 30 minutes or more, and when the reaction temperature is 180 ° C., the reaction time is 60 minutes or more. It was confirmed that it could be recovered in the lysate. As shown in Table 2, as the form of nitrogen in the solubilized liquid, ammonia is a little more than 10% (about 20% based on the amount of nitrogen in the solubilized liquid), and nitrous acid and nitrate ions. Was found to be almost negligible. From Table 2, many others are considered to be organic nitrogen compounds such as amino acids.
表３に示すように、反応温度２２５〜２７５℃、反応時間１５〜６０分では、脱水汚泥中の１０％前後のリンを可溶化液中に回収でき、そのほとんどがリン酸イオンであることが確認された。また、反応温度２７５℃で顕著であるが、可溶化液中のリンは反応時間が長くなると値が低下するため、固体析出することが示唆される。 As shown in Table 3, when the reaction temperature is 225 to 275 ° C. and the reaction time is 15 to 60 minutes, about 10% of phosphorus in the dewatered sludge can be recovered in the solubilized liquid, and most of them are phosphate ions. confirmed. Moreover, although it is remarkable at the reaction temperature of 275 ° C., the value of phosphorus in the solubilized solution decreases as the reaction time increases, suggesting that solid precipitation occurs.
熱水処理後の固体成分を糖化することを考慮すると、可溶化液中への炭素の回収率をできるだけ少なくするとともに、他の窒素やリンなどの成分を可溶化液中に溶出させて、固体成分中の多糖類の割合を高めておくことが好ましい。また、作業時間を短縮するために、熱水処理時間もできるだけ短くすることが好ましい。これらを考慮すると、表１〜表４から、熱水処理による汚泥の可溶化率が２０〜３５％のとき、すなわち反応温度と反応時間がそれぞれ、［１８０℃、６０分］、［２００℃、３０分］、［２２５℃、１５分］、［２２５℃、３０分］、［２５０℃、１５分］の場合が好ましく、特に［２２５℃、１５分］の場合が最も好ましい。 Taking into account the saccharification of the solid components after hydrothermal treatment, the carbon recovery rate in the solubilized solution is reduced as much as possible, and other components such as nitrogen and phosphorus are eluted in the solubilized solution to obtain solids. It is preferable to increase the proportion of polysaccharide in the component. In order to shorten the working time, it is preferable to shorten the hot water treatment time as much as possible. Considering these, from Tables 1 to 4, when the sludge solubilization rate by hot water treatment is 20 to 35%, that is, the reaction temperature and the reaction time are [180 ° C., 60 minutes], [200 ° C., respectively]. [30 minutes], [225 ° C., 15 minutes], [225 ° C., 30 minutes], [250 ° C., 15 minutes] are preferable, and [225 ° C., 15 minutes] is particularly preferable.
なお、脱水汚泥の仕込み量を０．３５〜０．３６ｇ、超純水の量を６６ｇとしたときの、２５０℃における可溶化率を調べ、その結果を表５および図４に示す。なお、この実験は、別のサンドバス（高林理化（株）社製「ＴＫ３」）を用いて行っている。表１および表５、ならびに図４に示すように、脱水汚泥の仕込み量が少なくなると、可溶化率の値が上昇する傾向が確認された。 The solubilization rate at 250 ° C. when the amount of dehydrated sludge charged was 0.35 to 0.36 g and the amount of ultrapure water was 66 g, and the results are shown in Table 5 and FIG. This experiment was performed using another sand bath (“TK3” manufactured by Takabayashi Rika Co., Ltd.). As shown in Tables 1 and 5 and FIG. 4, it was confirmed that the value of the solubilization rate increased when the amount of dehydrated sludge charged decreased.
また、ワタ状の脱水汚泥をさらに粉砕して粉末状にし、その粉末状汚泥を熱水処理したときの可溶化率を調べ、その結果を表６および図５に示す。粉砕には、コンバージミル（真壁技研（株）社製）を使用した。表１および表６、ならびに図５に示すように、粉末状汚泥（５０％径：１２μｍ）の可溶化率は、ワタ状の汚泥の可溶化率とほぼ同様の値となっており、汚泥の形状による可溶化率の違いは比較的低い値のためほとんど認められなかった。 Further, cotton-like dewatered sludge was further pulverized into powder, and the solubilization rate when the powdered sludge was treated with hot water was examined. The results are shown in Table 6 and FIG. For pulverization, a convergence mill (manufactured by Makabe Giken Co., Ltd.) was used. As shown in Tables 1 and 6, and FIG. 5, the solubilization rate of powdered sludge (50% diameter: 12 μm) is almost the same as the solubilization rate of cotton sludge. The difference in the solubilization rate depending on the shape was hardly recognized because of the relatively low value.
［固体成分の糖化実験］
図１に示す、熱水処理後に濾過して得られた固体残渣を２段階で酸糖化する工程に関して、以下の実験を行った。
熱水処理により得られた可溶化液（液体成分）中にはタンパク質やリンなどが溶解しているため、熱水処理後の固体成分（固体残渣）は、繊維質の多糖類が主成分になっていると考えられる。そこで、この固体残渣を用いて、糖化実験を行った。用いた固体残渣は、表１に示す熱水処理実験で得られたものである。実験では、図６に示すように、固体残渣に対して、硫酸加水分解による酸糖化を行った。具体的には、非特許文献２に記載の方法を用い、まず濃硫酸により固体残渣を加水分解してオリゴ糖（オリゴマー）に分解し、さらに希硫酸により加水分解して単糖類まで分解した。酸糖化後に得られた液体中の単糖（グルコース、フルクトース）を、ＨＰＬＣで測定した。
[Saccharification experiment of solid components]
The following experiment was conducted with respect to the step of acid saccharifying the solid residue obtained by filtration after the hot water treatment shown in FIG. 1 in two stages.
Proteins and phosphorus are dissolved in the solubilized liquid (liquid component) obtained by hydrothermal treatment, so the solid component (solid residue) after hydrothermal treatment is mainly composed of fibrous polysaccharides. It is thought that it has become. Therefore, a saccharification experiment was performed using this solid residue. The solid residue used was obtained in the hydrothermal treatment experiment shown in Table 1. In the experiment, as shown in FIG. 6, acid saccharification was performed on the solid residue by sulfuric acid hydrolysis. Specifically, using the method described in Non-Patent Document 2, the solid residue was first hydrolyzed with concentrated sulfuric acid to decompose into oligosaccharides (oligomers), and further hydrolyzed with dilute sulfuric acid to decompose into monosaccharides. Monosaccharides (glucose, fructose) in the liquid obtained after acid saccharification were measured by HPLC.
単糖の測定結果から固体残渣中の単糖の残存率を求め、表７および図７に示す。ここで、熱水処理前の脱水汚泥中に含まれる多糖類を分解して得られる単糖の量を基準（１００％）とした。表７および図７に示すように、熱水処理の反応温度と反応時間がそれぞれ［２２５℃、１５分］、［２２５℃、３０分］、［２５０℃、１５分］のとき、糖化後の液体中の単糖の残存率が９０％以上となることが確認された。特に、［２２５℃、１５分］のとき、単糖の残存率が約１００％となり、脱水汚泥中の多糖類を分解して得られる単糖のほぼ全量が回収できることが確認された。 The residual rate of monosaccharides in the solid residue was determined from the measurement results of monosaccharides and is shown in Table 7 and FIG. Here, the amount of monosaccharide obtained by decomposing the polysaccharide contained in the dewatered sludge before the hot water treatment was used as a standard (100%). As shown in Table 7 and FIG. 7, when the reaction temperature and reaction time of the hydrothermal treatment were [225 ° C., 15 minutes], [225 ° C., 30 minutes], [250 ° C., 15 minutes], respectively, It was confirmed that the residual rate of monosaccharides in the liquid was 90% or more. In particular, at [225 ° C., 15 minutes], the residual rate of monosaccharides was about 100%, and it was confirmed that almost the entire amount of monosaccharides obtained by decomposing polysaccharides in dehydrated sludge can be recovered.
糖化実験の結果から、反応温度と反応時間がそれぞれ［２２５℃、１５分］、［２２５℃、３０分］、［２５０℃、１５分］の条件、特に［２２５℃、１５分］の条件で熱水処理を行うことにより、熱水処理の段階では、多糖類から単糖への分解反応がほとんど生じず、メイラード反応や単糖の過分解反応を回避することができる。また、それらの反応条件よりも高温または長い反応時間の場合には、単糖が過分解またはメイラード反応で消費されるものと考えられる。なお、熱水処理を行わず、脱水汚泥を図６に示す方法により直接糖化したときの単糖（セルロース、フルクトース）の合計重量は、脱水汚泥の４５ｗｔ％になることが確認された。 From the results of the saccharification experiment, the reaction temperature and the reaction time were [225 ° C., 15 minutes], [225 ° C., 30 minutes], [250 ° C., 15 minutes], particularly [225 ° C., 15 minutes]. By performing the hydrothermal treatment, the decomposition reaction from polysaccharide to monosaccharide hardly occurs at the hydrothermal treatment stage, and Maillard reaction and monosaccharide hyperdegradation reaction can be avoided. In addition, when the reaction temperature is higher or longer than those reaction conditions, it is considered that monosaccharides are consumed by overdegradation or Maillard reaction. It was confirmed that the total weight of monosaccharides (cellulose and fructose) when dehydrated sludge was directly saccharified by the method shown in FIG. 6 without performing hot water treatment was 45 wt% of the dehydrated sludge.
［藻類の培養実験−糖化後］
図１に示す、糖化後の液体を用いて藻類の培養を行う工程に関して、以下の実験を行った。
脱水汚泥を熱水処理した後の固体成分を糖化して得られた液体を用い、藻類を培養する実験を行った。実験には、反応温度２２５℃、反応時間１５分で熱水処理して得られた固体成分を、図６に示す方法で糖化して得られた液体を使用した。また、固体成分を、図６に示す濃硫酸で加水分解を行って得られた、主にオリゴ糖を含む液体と、その液体をさらに希硫酸で加水分解を行って得られた、主に単糖類を含む液体とを用いて、それぞれ培養を行った。また、培養する藻類として、従属栄養性藻類のオーランチオキトリウム（Aurantiochytrium）を用いた。
[Algal culture experiment-after saccharification]
The following experiment was conducted with respect to the step of culturing algae using the liquid after saccharification shown in FIG.
An experiment was conducted in which algae were cultured using a liquid obtained by saccharifying the solid component after dehydrating sludge was hydrothermally treated. In the experiment, a liquid obtained by saccharifying a solid component obtained by hydrothermal treatment at a reaction temperature of 225 ° C. and a reaction time of 15 minutes by the method shown in FIG. 6 was used. In addition, a solid component obtained by hydrolysis with concentrated sulfuric acid shown in FIG. 6 and mainly containing a oligosaccharide and a liquid obtained by further hydrolyzing the liquid with dilute sulfuric acid are mainly simple. Each was cultured using a liquid containing saccharides. Moreover, the heterotrophic algae Aurantiochytrium (Aurantiochytrium) was used as the algae to be cultured.
実験では、まず、前培養として、グルコースを２０ｇ／Ｌの濃度で含む培地を用いて、オーランチオキトリウムを７２時間培養した。次に、培養したオーランチオキトリウムをすすいだ（cell wash）後、グルコースを含まない培地（ＳＴＹ培地）を用いて２４時間培養し、再度オーランチオキトリウムをすすいだ（cell wash）。こうして培養したオーランチオキトリウムを用い、グルコースを含まない培地（ＳＴＹ培地）に糖化後の液体を添加した培地（以下、それぞれ「可溶化培地（単糖）」、「可溶化培地（オリゴ糖）」と呼ぶ）を使用して培養を行った。培養時の温度は２０℃で、７０ｒｐｍの旋回震盪を行って培養した。 In the experiment, first, as a preculture, auranthiochytrium was cultured for 72 hours using a medium containing glucose at a concentration of 20 g / L. Next, the cultured auranthiochytrium was rinsed (cell wash), then cultured for 24 hours using a medium not containing glucose (STY medium), and the auranthiochytrium was again rinsed (cell wash). Medium obtained by adding the saccharified liquid to a glucose-free medium (STY medium) using the auranthiochytrium thus cultured (hereinafter referred to as “solubilized medium (monosaccharide)” and “solubilized medium (oligosaccharide), respectively)” Was used to culture. The temperature at the time of culture was 20 ° C., and the culture was performed by rotating and shaking at 70 rpm.
実験では、培養開始から２４時間毎に、６６０ｎｍの波長の光を用いて濁度（ＯＤ６６０）を測定した。また、培養開始から４８時間後、９６時間後に、それぞれ新しい培地に交換して栄養分の補給を行った。なお、可溶化培地（単糖）および可溶化培地（オリゴ糖）は、グルコース０．６ｇ／Ｌの濃度で含んでいる。また、比較のため、グルコースを含まない培地（ＳＴＹ培地）を使用して、同様に培養を行った。実験結果を、図８に示す。 In the experiment, turbidity (OD660) was measured every 24 hours from the start of culture using light having a wavelength of 660 nm. In addition, after 48 hours and 96 hours from the start of the culture, each medium was replaced with a new medium to supply nutrients. The solubilizing medium (monosaccharide) and the solubilizing medium (oligosaccharide) contain glucose at a concentration of 0.6 g / L. For comparison, culture was similarly performed using a medium not containing glucose (STY medium). The experimental results are shown in FIG.
図８に示すように、可溶化培地（単糖）で、オーランチオキトリウムを培養可能であることが確認された。また、やや培養効率は低下するが、可溶化培地（オリゴ糖）でも、オーランチオキトリウムを培養可能であることが確認された。このことから、糖化後の液体にはブドウ糖などの単糖類やオリゴ糖が多く含まれているため、栄養源として、従属栄養性藻類などの藻類の培養に利用することができるといえる。 As shown in FIG. 8, it was confirmed that auranthiochytrium can be cultured in a solubilized medium (monosaccharide). In addition, although the culture efficiency slightly decreased, it was confirmed that auranthiochytrium can be cultured even in a solubilized medium (oligosaccharide). From this, it can be said that the liquid after saccharification contains a large amount of monosaccharides and oligosaccharides such as glucose and can be used as a nutrient source for culturing algae such as heterotrophic algae.
［藻類の培養実験−熱水処理後］
脱水汚泥を熱水処理した後の液体成分（可溶化液）を用い、藻類を培養する実験を行った。実験には、反応温度２２５℃、反応時間１５分で熱水処理を行って得られた可溶化液を用いた。また、培養する藻類として、独立栄養性藻類のユーグレナ・グラシリス（Euglena gracilis）のNIES-48株を用いた。
[Algae culture experiment-after hydrothermal treatment]
An experiment was conducted to culture algae using the liquid component (solubilized solution) after hydrothermal treatment of dehydrated sludge. In the experiment, a solubilized solution obtained by hydrothermal treatment at a reaction temperature of 225 ° C. and a reaction time of 15 minutes was used. In addition, the NIES-48 strain of Euglena gracilis, an autotrophic algae, was used as the algae to be cultured.
実験では、まず、前培養として、藻類の培養に用いられるＡＦ−６培地を用いて、ユーグレナ・グラシリスを１２０時間培養した。次に、培養したユーグレナ・グラシリスを、脱水汚泥を熱水処理した後の可溶化液（以下、「汚泥可溶化液」と呼ぶ）に接種して培養を行った。培養時の温度は２０℃、光強度は３０μmol photons m-2s-1（連続光）であり、Ｌ字型試験管を用いて静置培養を行った。なお、比較のため、ＡＦ−６培地を用いた培養も行った。また、前培養で用いたＡＦ−６培地の影響を評価するために、蒸留水のみを用いた培養も行った。 In the experiment, first, Euglena gracilis was cultured for 120 hours using AF-6 medium used for algae culture as a preculture. Next, the cultured Euglena gracilis was inoculated into a solubilization solution (hereinafter referred to as “sludge solubilization solution”) after dehydrating sludge was hydrothermally treated. The culture temperature was 20 ° C., the light intensity was 30 μmol photons m −2 s −1 (continuous light), and static culture was performed using an L-shaped test tube. For comparison, culture using AF-6 medium was also performed. Further, in order to evaluate the influence of the AF-6 medium used in the preculture, culture using only distilled water was also performed.
実験では、培養開始から２４時間毎にサンプリングを行い、７５０ｎｍの波長の光を用いて濁度（ＯＤ７５０）を測定した。なお、初期濁度ＯＤ７５０＝０．０５となるように、各培地にユーグレナ・グラシリスを接種している。また、実験は、各培地を３つずつ用意して行い、その平均値を求めている。実験結果を、図９に示す。図９では、測定値の平均をプロットし、標準偏差をエラーバーとして示している。 In the experiment, sampling was performed every 24 hours from the start of culture, and turbidity (OD750) was measured using light having a wavelength of 750 nm. Each medium was inoculated with Euglena gracilis so that the initial turbidity OD750 = 0.05. In addition, the experiment is performed by preparing three of each medium, and the average value is obtained. The experimental results are shown in FIG. In FIG. 9, the average of the measured values is plotted, and the standard deviation is shown as an error bar.
図９に示すように、汚泥可溶化液を用いて培養すると、ＡＦ−６培地により培養したものと比較して、９６時間後に濁度が２倍になることが確認された。このことから、熱水処理後の処理物から分離回収した液体成分には、アミノ酸やアンモニアなどの窒素化合物や、リン酸などの栄養分が多く含まれているため、栄養源として、独立栄養性藻類などの藻類の培養に幅広く利用することができるといえる。 As shown in FIG. 9, it was confirmed that when cultivated using a sludge solubilizing solution, the turbidity doubled after 96 hours as compared with that cultured with AF-6 medium. For this reason, the liquid components separated and recovered from the treated product after the hot water treatment contain a large amount of nutrients such as nitrogen compounds such as amino acids and ammonia, and phosphoric acid. It can be said that it can be widely used for culturing algae such as.
［熱水処理方法の変形例］
図１０に示すように、熱水処理手段として、図２に示す回分式反応器１１の代わりに、流通式亜臨界水可溶化装置を用いて熱水処理を行ってもよい。この流通式亜臨界水可溶化装置は、例えば、脱水汚泥と超純水とを撹拌して汚泥スラリーを作製し、その汚泥スラリーを高圧で供給可能に設けられた汚泥スラリー供給装置と、長い配管を有し、汚泥スラリー供給装置から高圧で供給された汚泥スラリーを高温にして、その配管の内部に通すことにより、熱水処理を行うよう設けられた反応器と、反応器から排出される処理物を冷却する冷却器と、冷却器で冷却後の処理物を固液分離するインラインフィルターとを有している。このような長い反応器を有する流通式亜臨界水可溶化装置を用いることにより、熱水処理の可溶化操作の処理量を大幅に増やすことができる。
[Modified example of hot water treatment method]
As shown in FIG. 10, hot water treatment may be performed using a flow-type subcritical water solubilizer instead of the batch reactor 11 shown in FIG. 2 as the hot water treatment means. This flow-type subcritical water solubilizer, for example, produces sludge slurry by stirring dehydrated sludge and ultrapure water, and a sludge slurry supply device provided so that the sludge slurry can be supplied at a high pressure, and a long pipe A reactor provided to perform hot water treatment by passing the sludge slurry supplied at high pressure from the sludge slurry supply device at a high temperature and passing through the inside of the piping, and a process discharged from the reactor A cooler for cooling the product, and an in-line filter for solid-liquid separation of the processed product after cooling by the cooler. By using a flow-type subcritical water solubilizer having such a long reactor, the throughput of the hydrothermal treatment solubilization operation can be greatly increased.
また、図１１に示すように、熱水処理手段として、図２に示す回分式反応器１１の代わりに、半回分式反応器を用いて熱水処理を行ってもよい。この場合、例えば、脱水汚泥を仕込む半回分式反応器と、半回分式反応器で熱水処理を行うよう、蒸留水を高圧ポンプおよび予熱炉で高温高圧にして半回分式反応器に供給する高温高圧水供給手段と、半回分式反応器から排出される熱水処理後の液体成分（可溶化液、分解物水溶液）を冷却する冷却器とを有し、高温高圧水（亜臨界水）により部分的な可溶化を行ってもよい。図１１に示す方法は、特に、汚泥のスラリー化もしくはその高圧供給が困難な場合に有効である。なお、下水処理場の廃熱ボイラーの高圧蒸気（または、その前の加圧水）が使用できる場合には、廃熱ボイラーのポンプが流体（水）の動力源となるため、図１１中の高圧ポンプや予熱炉を簡略化することができる。 Moreover, as shown in FIG. 11, you may perform a hot-water process using a semi-batch type reactor instead of the batch-type reactor 11 shown in FIG. In this case, for example, distilled water is supplied to the semi-batch reactor at a high temperature and a high pressure with a high-pressure pump and a preheating furnace so as to perform the hot water treatment with the semi-batch reactor charged with dewatered sludge and the semi-batch reactor. High-temperature high-pressure water (subcritical water) with high-temperature high-pressure water supply means and a cooler that cools the liquid components (solubilized liquid, decomposition product aqueous solution) after the hot water treatment discharged from the semi-batch reactor Alternatively, partial solubilization may be performed. The method shown in FIG. 11 is particularly effective when sludge slurrying or high-pressure supply thereof is difficult. In addition, when the high-pressure steam (or the pressurized water before that) of the waste heat boiler at the sewage treatment plant can be used, the pump of the waste heat boiler serves as a power source for fluid (water), so the high-pressure pump in FIG. And the preheating furnace can be simplified.
［糖化方法の変形例］
多糖類を分解（オリゴマー化）するポイントは、より高い反応温度とより短い反応時間との実現であり、図１２に示すように、急速昇温急速冷却式反応装置を用いて、酸を使用せずにこれを行うこともできる。すなわち、図１２（ａ）に示すように、この急速昇温急速冷却式反応装置は、例えば、熱水処理後の固体残渣（固体成分）を撹拌して固体残渣スラリーを作製し、その固体残渣スラリーを高圧で供給可能に設けられた固体残渣スラリー供給装置と、蒸留水を高圧ポンプおよび予熱炉で高温高圧にして供給する高温高圧水供給手段と、固体残渣スラリーを分解（オリゴマー化）させるよう、固体残渣スラリー供給装置から高圧で供給された固体残渣スラリーと高温高圧水供給手段から供給された高温高圧水とを混合する反応器と、蒸留水を高圧ポンプで高圧にして供給する高圧冷却水供給手段と、反応器から排出される処理物と高圧冷却水供給手段から供給される高圧冷却水とを混合し冷却する補助冷却器と、補助冷却器で冷却後の処理物を固液分離するインラインフィルターとを有している。
[Modification of saccharification method]
The point of degradation (oligomerization) of polysaccharides is the realization of a higher reaction temperature and shorter reaction time. As shown in FIG. 12, a rapid heating and rapid cooling reactor is used. You can do this without That is, as shown in FIG. 12 (a), this rapid heating and rapid cooling type reaction apparatus, for example, stirs the solid residue (solid component) after the hot water treatment to produce a solid residue slurry, and the solid residue A solid residue slurry supply device provided so that slurry can be supplied at high pressure, high temperature high pressure water supply means for supplying distilled water at high temperature and high pressure with a high pressure pump and a preheating furnace, and solid residue slurry is decomposed (oligomerized) , A reactor for mixing the solid residue slurry supplied at high pressure from the solid residue slurry supply device with the high-temperature high-pressure water supplied from the high-temperature high-pressure water supply means, and high-pressure cooling water to supply distilled water at a high pressure with a high-pressure pump The supply means, the treated product discharged from the reactor and the high-pressure cooling water supplied from the high-pressure cooling water supply means are mixed and cooled, and the treated product cooled by the auxiliary cooler is solidified. And an in-line filter to separate.
図１２（ａ）に示す急速昇温急速冷却式反応装置を使用する場合、図１２（ｂ）に示すように、原料である固体残渣スラリーを高圧で反応器に供給し、高温高圧水（熱水）と混ぜて急速昇温することにより、分解（オリゴマー化）することができる。また、数ミリ秒から数秒程度、反応器で分解を行った後、高圧冷却水で急速冷却することにより、分解反応を終了することができる。これにより、高収率でオリゴ糖を得ることができる。なお、この分解では単糖類も生成するが、得られたオリゴ糖を酵素または酸で糖化することで単糖類を高収率で得ることができる。 When using the rapid heating and rapid cooling reactor shown in FIG. 12 (a), as shown in FIG. 12 (b), the solid residue slurry as a raw material is supplied to the reactor at high pressure, and high-temperature high-pressure water (heat It can be decomposed (oligomerized) by mixing with water and rapidly raising the temperature. In addition, after performing decomposition in a reactor for several milliseconds to several seconds, the decomposition reaction can be completed by rapid cooling with high-pressure cooling water. Thereby, an oligosaccharide can be obtained with a high yield. In addition, although monosaccharide is also produced | generated by this decomposition | disassembly, a monosaccharide can be obtained with a high yield by saccharifying the obtained oligosaccharide with an enzyme or an acid.
本発明により、従属栄養性藻類の培養に必要な単糖類を、下水汚泥の熱水処理と処理後の固体成分（残渣）の糖化処理とによって得ることができる。これまで廃棄物として浄化センター等で焼却処理されてきた大量の下水汚泥を有効利用して、炭化水素等を製造する従属栄養性藻類の大量培養を実現することが可能になる。また、メイラード反応等が抑制された下水汚泥の熱水処理で生成した液体成分も、窒素・リンを含む化合物が溶解しており、独立栄養性藻類や従属栄養性藻類の培養液（培地）として利用できる。藻類の培養に限らず幅広い分野への応用が可能であり、下水汚泥を原料としたバイオマス化学工業の基盤技術として有用である。 According to the present invention, monosaccharides necessary for culturing heterotrophic algae can be obtained by hydrothermal treatment of sewage sludge and saccharification treatment of solid components (residues) after the treatment. Mass cultivation of heterotrophic algae that produce hydrocarbons and the like can be realized by effectively utilizing a large amount of sewage sludge that has been incinerated at a purification center or the like as waste. In addition, the liquid component produced by hydrothermal treatment of sewage sludge with suppressed Maillard reaction, etc. is also dissolved in compounds containing nitrogen and phosphorus, as a culture solution (medium) for autotrophic algae and heterotrophic algae Available. It can be applied to a wide range of fields, not limited to algae culture, and is useful as a basic technology for biomass chemical industry using sewage sludge as a raw material.
１１ 回分式反応器
１２ サンドバス
１３ マントルヒータ
１４ 熱電対
11 batch reactor 12 sand bath 13 mantle heater 14 thermocouple
Claims (10)
前記熱水処理手段の処理物から固体成分の一部または全部を回収する固体回収手段と、
前記固体回収手段で回収した固体成分に対して糖化を行う糖化手段と、
前記糖化手段による糖化後の液体を使用して、藻類を培養可能に設けられた第一培養手段とを、
有することを特徴とする藻類培養システム。 Hydrothermal treatment means for performing hydrothermal treatment on sludge containing polysaccharides;
Solid recovery means for recovering part or all of the solid component from the processed product of the hot water treatment means;
Saccharification means for saccharifying the solid component recovered by the solid recovery means;
Using the liquid after saccharification by the saccharification means, and a first culture means provided so that algae can be cultured,
An algae culture system comprising:
前記液体回収手段で回収した液体成分を使用して、藻類を培養可能に設けられた第二培養手段とを、
有することを特徴とする請求項９記載の藻類培養システム。
Liquid recovery means for recovering part or all of the liquid component from the processed product of the hot water treatment means;
Using the liquid component recovered by the liquid recovery means, a second culture means provided so that algae can be cultured,
The algae culture system according to claim 9, comprising:
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