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The synthesis of DDR-type zeolite membranes faces the problem of cracks that occur on the zeolite membrane due to differences in the thermal expansion coefficient between zeolite and the porous substrate during the detemplating process. In this study, Al-containing ZSM-58 zeolite membranes with DDR topology were prepared by rapid thermal processing (RTP), with the aim of developing a reproducible method for preparing DDR zeolite membrane without cracks. Moreover, we verified the influence of RTP before performing conventional thermal calcination (CTC) on ZSM-58 membranes with various silica-to-aluminum (Si/Al) molar ratios. Using the developed method, an Al-containing ZSM-58 membrane without cracks was obtained, along with complete template removal by RTP, and it had higher CO2/CH4 selectivity. An all-silica ZSM-58 membrane without cracks was obtained by only using the ozone detemplating method. ZSM-58 crystals and membranes with various Si/Al molar ratios were analyzed by using Fourier-transform infrared (FTIR) spectroscopy to confirm the effects of RTP treatment. Al-containing ZSM-58 zeolites had higher silanol concentrations than all-silica zeolites, confirming many silanol condensations by RTP. The condensation of silanol forms results in the formation of siloxane bonds and stronger resistance to thermal stress, therefore, RTP caused crack suppression in Al-containing ZSM-58 membranes. The results demonstrate that Al-containing ZSM-58 zeolite membranes with high CO2 permeance and CO2/CH4 selectivity and minimal cracking can be produced by using RTP.

First, we attempted to synthesize a DD3R zeolite membrane by using precursor solutions containing small amounts of a structure-directing agent and potassium fluoride (KF), with the aim of obtaining a membrane with high permeance toward CO2. The most dilute precursor solution (1-adamantylamine:KF:SiO2:H2O = 0.026:0.026:1:52) produced a thin and dense zeolite membrane that showed a high CO2 permeance of 12 × 10−8 mol m−2 s−1 Pa−1 and a high PCO2/PCH4 of 270 at a pressure drop of 1.0 MPa. We then studied the synthesis of DD3R membranes with various alkali metal halides (KCl, KBr, NaF, NaCl, or NaBr) as the mineralizing agent (MA). Regardless of the alkali metal halide selected, the addition of a small amount of MA permitted the preparation of DD3R membranes with a high separation selectivity of 190–380 at a pressure drop of 1.0 MPa. Addition of excessive amounts of MA caused gelling of the solution and a decrease in the separation selectivity. The presence of a few alkali metal cations promotes the growth of zeolite crystals on the support and permits the synthesis of dense DD3R zeolite membranes.

Utilising CO2 from biogas as a carbon source can introduce energy production systems incorporating microalgae cultivation into wastewater treatment plants (WWTPs). In this study, the effects of utilising membrane-separated CO2 (MSC; CO2 content: 983 ± 11 dm3 m−3)—obtained from biogas using a newly developed separation system—on indigenous microalgae cultivation with treated effluents was investigated. Assuming model cultivation systems, energy balance analysis was conducted to evaluate the feasibility of MSC utilisation and its superiority over flue gas CO2 (FC) from power plants (PPs). Scenarios 1 and 2 used generated biogas of 11.6 and 116 dm3 s−1, and produced MSC (carbon based) were 0.802 and 8.02 g s−1, respectively. Experiments comparing MSC (suspended solids (SS): 166 ± 23 mg dm−3; higher heating value (HHV): 21.1 ± 0.46 kJ g−1) with commercial CO2 (SS: 176 ± 16 mg dm−3; HHV: 21.2 ± 0.90 kJ g−1) revealed no negative effects on microalgae activity, biomass production, or energy content. Energy revenue of the MSC utilisation system was 27.0 MJ per 1 kg injected MSC, which is greater than the energy costs (18.2 and 17.1 MJ kg−1 in scenarios 1 and 2, respectively). MSC utilisation is energetically feasible, and energetically superior to FC utilisation when the PP-to-WWTP distance is over 0.6 and 1.9 km in scenarios 1 and 2, respectively.

We prepared all-silica ZSM-58 zeolite membranes on α-alumina tubular supports and optimized their synthesis conditions. High-purity ZSM-58 zeolite membranes were prepared using a concentrated precursor solution (methyltropinium iodide/SiO2 and NaOH/SiO2 molar ratios > 0.05) with a H2O/SiO2 molar ratio of 52 at 413 K for 24 h. A ZSM-58/DOH mixed layer or a pure DOH layer was generated with ZSM-58 when the synthesis temperature exceeded 413 K and the synthesis time was longer than 24 h. The membranes prepared with a H2O/SiO2 molar ratio higher than 52 were not covered ZSM-58 zeolite and/or generated DOH zeolite. Further, we investigated the separation performance of the ZSM-58 zeolite membrane for CO2/CH4 and CO2/N2 gas mixtures as a function of feed pressure. At a pressure drop of 0.2 MPa, the membrane exhibited a CO2 permeance and CO2/CH4 mixture selectivity of 17 × 10−8 mol s−1 m−2 Pa−1 and 290, respectively, for a CO2/CH4 system, and a CO2 permeance and CO2/N2 selectivity of 29 × 10−8 mol m−2 s−1 Pa−1 and 44, respectively, for a CO2/N2 system. The mixture selectivity was lower than the single gas selectivity in CO2/CH4 separation due to competitive adsorption since CH4 mainly passes through non-zeolite pores. In contrast, the mixture selectivity was higher than the single gas selectivity in CO2/N2 separation because N2 permeation was inhibited by CO2 adsorption in the zeolite pores since N2 mainly passes through the zeolite pores. Thus, high-purity ZSM-58 zeolite membranes with high CO2 separation performances were obtained by the optimized synthesis conditions.

高いCO2/CH4分離性能を有するDDR型ゼオライト膜を用いたバイオガスの膜分離プロセスの開発を行うとともに，DDR型ゼオライト膜を用いた下水処理施設から発生するバイオガスの分離・精製と膜の耐久性を評価した．まず，簡素な1段分離プロセスに必要な膜性能を数理モデルにより把握し，実験によってDDR型ゼオライト膜を用いる際の最適な処理流量を決定した．次いで，実バイオガス分離・精製を行うために下水処理施設内にパイロットプラントを設置し，精製実験を行った．結果，目標とする回収CH4濃度90%，排出CO2濃度97%で精製可能であった．また，約40時間以上通気しても膜性能は変化しなかった．そのため，本研究で開発した膜分離プロセスは十分にバイオガスの分離・精製に適用することが可能であることがわかった．さらに，バイオガスの前処理を一切行なわず1600時間供給することにより，バイオガス中の不純物が膜分離性能に与える影響の検討を行った結果，長時間の通気によりバイオガス中に不純物として含まれる高級炭化水素，シロキサンなどの高沸点化合物により膜性能が低下すると考えられた．

To reduce the pollution load caused by Combined Sewer Overflow (CSO), which significantly affects the properties of water for public use in the event of rain, effective measures are adopted after the outflow behavior and pollution load are carefully studied. In this research, an area of about 127 ha around the confluence zone located in Nagaoka City, Niigata was targeted, the outflow rate, the water quality of CSO and the amount of rainfall were continuously monitored for 1200 days. The observation was started in June 2004 at two points where chamber has been equipped. As a next step, a simulation model with high reproducibility was designed on the basis of the data obtained by continuous observation using MOUSE. Since the water quality was predicted using the model in the case when it could not be measured, the pollution load of CSO was accurately estimated. It was found that the pollution loads of SS and of BOD for eight months (from April to November) were 50×103 kg and 28×103 kg, respectively. In addition, we found that the pollution load basic units of SS and BOD were 59×103 kg km-2 year-1 and 33×103 kg km-2 year-1, respectively.

リン鉱石は枯渇が懸念される資源である一方，下水汚泥焼却灰はリン鉱石と同程度リンを含有し，リン鉱石と代替できる可能性を有する。そこで本研究は，溶融処理を用いたスラグ肥料の作成可能な下水汚泥焼却灰組成範囲と，肥料としての安全性・肥効性の明確化を目的とした。灰組成による影響検討のためモデル灰からスラグ肥料を作製した結果，灰組成中にリン酸17wt%以上，酸化マグネシウム15wt%以上，アルカリ分40wt%以上となる範囲内にすることで品質基準を満たすことを確認した。また実焼却灰でもこの組成範囲に調整することでリン肥料が作製可能なことを確認した。重金属類に対する安全性の検討を行った結果，含有量試験より鉛やクロムなどは肥料取締法基準値を満たすことを確認した。またスラグ肥料を施肥して栽培した作物を分析した結果，植物中の鉛，カドミウム，クロムは食品衛生法の許容上限量を下回り，実土壌への適用が可能であることが示唆された。

膜分離活性汚泥法では高いランニングコストを削減することが課題となっている．高いランニングコストをもたらしている主原因は，膜面付着物を剥離させるために強い曝気が必要なことである．これまでに本研究グループでは膜分離反応槽内に担体を投入することで膜透過性能の向上効果があることを見出しており，担体投入により曝気量が縮減できると考えられた． 本研究では，曝気線速度0.4m/minで担体の無添加系と添加系，曝気線速度0.2m/minで担体を添加系の3条件で，実下水の長期間の連続処理実験を行った．その結果，担体を添加することで，従来より低い曝気線速度でも安定した窒素除去性能および膜透過性能が得られ，薬品洗浄回数も大幅に削減できた．

Using hydrothermal synthesis, a highly hydrophobic DDR-type zeolite membrane was prepared on the outer surface of a porous α-alumina tube. The results of this study show that it is useful for CO2/CH4 separation. Single-gas permeation for CO2, CH4, H2, He, N2, and O2, and CO2/CH4 binary gas permeation, were measured, respectively, at pressures up to 5 and 2 MPa. The respective single-gas permeances of CO2 and CH4 at 298 K at a feed pressure of 0.2 MPa and a permeate pressure of 0.1 MPa were 4.2 × 10-7 and 1.2 × 10-9 mol m-2 s-1 Pa-1; the ideal selectivity for CO2/CH4 was 340. The permeances were in the following order: CO2 > H2 > He > O2 > N2 > CH4. Single-gas permeance was dependent on the relative molecular size of the DDR pore diameter. However, CO2 permeance dominated the adsorption affinity to the pore wall of DDR zeolite. In mixed-gas permeation experiments using the sweep method, the DDR-type zeolite membrane showed high selectivity for CO2/CH4 mixtures of 200 and high CO2 permeance of 3.0 × 10-7 m...

We measured the mutagen formation potential (MFP) of 42 river water samples from 37 rivers throughout Japan using the Ames mutagenicity assay, to investigate the nationwide level of mutagen precursors contained in river water. The MFP of river water was highest when Salmonella typhimurium strain TA100 was used without metabolic activation. The MFPs ranged from 210 to 20,200 net rev. · l-1 and the median was 2,520 net rev. · l-1, which shows that the values varied greatly between samples. About 60% of the samples showed MFPs in the range from 1,500 to 3,500 net rev. · l-1. Dissolved organic carbon (DOC), E260, NH4-N, NO2-N, NO3-N and T-N concentrations were also measured. A strong positive relationship was observed between logarithmically-transformed DOC and MFP. However, the MFP/DOC ratio varied widely from 110 to 2,160 net rev. · mg-1. We also investigated the relationship between MFP and river basin characteristics such as population density. The results suggest that mutagen precursors are strongly influenced by human activities. In addition, rivers were classified using a cluster analysis of water qualities (MFP, DOC, E260, NH4-N and NO2-N+NO3-N).

Clathrasil Deca-dodecasil 3R (DD3R) zeolite was synthesized in this study. Then, adsorption properties of carbon dioxide and methane were examined on the all-silica DD3R zeolite. Pure component adsorption isotherms are reported at temperatures of 273–348 K and pressures as high as 3 MPa. The isotherms follow a typical Type-I shape according to the Brunauer classification. They are well described using Langmuir and multi-site Langmuir models. Isosteric heats of adsorption and Henry’s Law constants of all adsorbates were determined. High selectivity of adsorption for carbon dioxide over methane suggests that the all-silica DD3R is an effective adsorbent or zeolite membrane material that can separate carbon dioxide and methane gaseous mixtures.

Highly porous activated carbon is used in the removal of volatile organic compounds (VOCs) and the purification of room air. Since the activated carbon must be capable of removing VOCs at low concentrations through adsorption, studies on the adsorption equilibrium of trace-level concentrations of VOCs are essential. To determine the adsorption isotherm, a headspace gas chromatography (HSGC) method was used, with analysis carried out using gas chromatography or gas chromatography-mass spectroscopy. The reliability of this method was confirmed by comparison of the adsorption isotherms of methanol measured by the HSGC method with those measured by the volumetric method. Isotherms for three different types of activated carbon and eight types of VOCs were determined over a wide range of concentrations. Furthermore, the results of the HSGC method for two systems of binary adsorption equilibria (dichloromethane+trichloroethylene) and (benzene+toluene), were found to be correlated with those of the ideal adsorbed solution theory.

本研究では，非理想吸着相溶液（Non-ideal Adsorbed Solution: NAS）理論を用いて，活性炭BPLに対する揮発性有機化合物類（VOCs）の二成分吸着平衡の相関を検討した．まず，ヘッドスペースガスクロマトグラフィー（HSGC）法を用いて，293，323，353 Kにおけるメタノール，アセトン，ベンゼン，ヘキサンの吸着等温線および293 Kにおけるトルエンの吸着等温線を相対圧2×10−7–1×10−2の範囲で測定した．また，トルエン／ベンゼン，ベンゼン／アセトン，ヘキサン／アセトンの二成分吸着平衡をHSGC法と流通法を用いて測定した．そして，二成分吸着について理想吸着相溶液（Ideal Adsorbed Solution: IAS）理論による解析を行った結果，極性が類似しているベンゼン／トルエンでは推算が可能であったが，極性の異なるVOCを組み合わせた二成分系（ベンゼン／アセトン系，ヘキサン–アセトン系）においては予測が困難であった．一方，NASではIASに比べて高精度での相関が可能であった．さらに，NASは共沸点を示す疎水性のY型ゼオライトに対するトルエン／1-プロパノール系においても二成分吸着平衡の相関が可能であった．

In this study, we report a new effective sludge-digestion gas (biogas) adsorption storage technology. The experimental data of the pure and binary adsorption equilibrium of methane and carbon dioxide, which are the main components of the biogas, on five types of activated carbons at a temperature range of 273–333 K and pressures up to 6 MPa, were measured. Pure isotherms were fitted with the Toth and extended Toth models. Binary equilibrium was predicted using the Ideal Adsorbed Solution Theory (IAST) based on the extended Toth model with the experimental data being predicted as well. The differential enthalpy of the pure and binary adsorption was calculated, and storage densities of the binary gases, methane and carbon dioxide, considering the increased activated carbon temperature, were estimated using the adiabat and isobar of mixed gases in the biogas composition.

High-pressure excess adsorption equilibria of methane and carbon dioxide on five microporous activated carbons were measured. Adsorption isotherms were obtained at temperatures ranging from (273 to 333) K and at pressures ranging from (0.5 to 6000) kPa using a static volumetric apparatus. The experimental data were analyzed using the Toth model and the Dubinin−Astakhov model. The isosteric enthalpies of adsorption and the limiting heat of adsorption for both adsorbates on all activated carbons were calculated using the Clausius−Clapeyron equations and the van't Hoff equations, respectively.

都市ごみ焼却灰溶融スラグの有効利用の促進を図るため, 灰組成の違いによるスラグ強度とPb溶出特性の把握を行い, スラグ化に適した灰組成範囲の明確化とpb溶出機構の解明を行った。溶融スラグは, 灰組成を試薬により調整したモデル焼却灰を用い, 1, 400℃で2時間溶融して冷却速度4℃/minの徐冷方法で作成した。スラグを骨材として再利用する際の骨材試験としてすりへり試験を行った結果, 塩基度 (CaO/SiO2) 1.25～1.75の範囲においてGehleniteの結晶が析出し, すりへり減量値が低く, スラグ強度が高くなった。また, 酸性 (pH4) 下の溶出試験では, 塩基度1.0～1.25の範囲にある共晶組成においてPbの溶出率が他の灰組成の2～3倍程度高くなった。さらに, 環告46号法を行った結果, 塩基度1.0～2.0の範囲にある多くの組成において溶出基準を満たすことがわかった。したがって, スラグ化に適した灰組成はスラグの材料強度とPb溶出試験の結果から塩基度1.5～1.75の範囲であると考えられた。さらに, Pbの溶出量は, 同一灰組成ならば, pHを一定とした条件下ではスラグ中のPb含有量に比例することを明らかとした。

一般廃棄物のガス化溶融処理では, 熱分解工程から燃焼・溶融工程までを最適に行うために, 投入する廃棄物をどの程度まで熱分解させるかが重要になってくる。本研究では, 実験試料に模擬ごみを仮定したRDF (廃棄物固形燃料) を用い, 一般廃棄物のガス化溶融処理における熱分解工程の処理条件の違いが, 熱分解残渣, タール, 熱分解ガスの生成に対し, どの程度影響を及ぼすのかを明らかにするとともに, 各熱分解条件で生成した熱分解残渣の熱重量分析および着火温度を測定することで, 燃焼・溶融工程での着火のしやすさを評価した。そして, 燃焼・溶融工程を通して適した熱分解条件を明らかにするために, 各熱分解条件での (1) 熱分解残渣の低位発熱量, (2) 熱分解ガスの低位発熱量, (3) 熱分解残渣の生成割合, (4) 熱分解残渣の燃料比を基に評価を行った。その結果, 熱分解温度450～500℃, 熱分解時間60分程度の条件が適することが明らかになった。