Search

The stable H2 production is the important link in the anaerobic biohythane fermentation. In order to address the key parameters for the stable H2 production in the recirculated temperature-phased anaerobic digestion (R-TPAD) system, a critical strategy was proposed to adjust the recirculation ratio (R). The adjusting strategy was examined on a lab-scale R-TPAD system. The R-TPAD system was started up and operated with R = 1. Another system without recirculation (R = 0) was also operated as the control system. By narrowing the probable range from 0

In this study, the effects of organic loading rates (OLRs) on anaerobic fermentation of food waste were comprehensively evaluated using a hollow fiber type anaerobic membrane bioreactor (HF-AnMBR). Compared to other OLRs, biogas production rate was highest at the OLR of 9.72 g-COD/L/d, the organic matter removal efficiency was also significantly higher and VFA was in lower concentration. COD conversion efficiency was as high as 92.9%, 85.3%, 82.6% and 80.4% at OLRs of 2.43, 4.86, 7.29 and 9.72 g-COD/L/d, respectively. The major membrane fouling was caused by organic pore blocking, accounting for 59.6% of the total hydraulic resistance after long-term operation. The performance of HF-AnMBR was compared with a continuously stirred tank reactor (CSTR) and a self-agitated reactor (SAR). The higher operation OLRs, COD conversion efficiency and better effluent quality achieved by the HF-AnMBR are evidences of a significant improvement in reactor performance compared to CSTR and SAR.

A 20 L hollow-fiber submerged anaerobic membrane bioreactor (SAnMBR) was used to treat real domestic wastewater at 25 °C with hydraulic retention times (HRTs) ranging from 4 to 12 h. The process performance was evaluated by organic removal efficiency, biogas production, sludge yield, and filtration behaviors during one-year's operation. For HRTs ranging between 6 and 12 h, the AnMBR showed good organic removal efficiency with chemical oxygen demand (COD) and biochemical oxygen demand (BOD) removal efficiencies of about 89% and 93%, respectively. The biogas yield was 0.26 L-gas/g-CODfed, with approximately 80% methane content, and the sludge yield was 0.07–0.11 g-VSS/g-CODrem. While at an HRT of 4 h, with the higher wastewater treatment capacity and organic loading rate (OLR), the biogas production was lower (0.17 L-gas/g-CODfed), and the sludge production was higher (0.22 g-VSS/g-CODrem). The organic removal performance (COD 84% and BOD 89%) at HRT of 4 h was acceptable due to the effective separation effect of the membrane filtration process. According to COD balance analysis, the low biogas yield and high sludge yield at HRT of 4 h were due to insufficient biodegradation under an OLR of 2.05 g-COD/L-reactor/d. Theoretical calculations based on Henry's law indicate that the ideal methane content in the biogas should be 82–85% when the operational temperature was 25 °C. To achieve a high flux and sustainable AnMBR operation, the impact of mixed liquor suspended solid (MLSS) and gas sparging velocity (GSV) on the filtration performance was analyzed. The critical flux increased with increase in the GSV from 24.2 to 174.3 m/h, but decreased with increase in the MLSS concentration from 8.2 to 20.2 g/L. Therefore, decreasing fouling rate to 0.8–1.2 kPa/d by efficiently controlling GSV and MLSS, sustainable operation could be achieved at a flux of 0.34 m/d.

In order to optimize the biogas recovery from the co-digestion of food waste (FW) and paper waste (PW), the effect of PW content on two-phase anaerobic digestion (TPAD) was investigated. The mixtures of FW and PW, with the ratios of 10:0, 8:2, 6:4 and 5:5 (total solids), were fed into TPAD to recover biomethane. After the long-term expriment, it is elucidated that the methanogenesis in TPAD was stable for PW ≤ 40%. When PW = 50%, NH4HCO3 was added to the methanogenic phase to provide nitrogen. As the indicators of the stability of the anaerobic process, the ammonia and alkalinity in the methanogenic phase were simulated for their decreasing trend. The simulation results quantified the nitrogen deficiency in the methanogenic phase for PW = 50%. Also, the comparison of alkalinity and ammonia revealed that ammonia was the major contributor to the alkalinity. Furthermore, via stoichiometric calculations, high C/N ratios were found to increase the microbial yield and exacerbated the nitrogen deficiency. In the energy estimation, adding PW showed significant increase only when PW ≥ 40%. It was concluded that 40% was the optimal PW content for bioenergy augmentation from co-digestion of FW and PW using TPAD.

A novel single-stage partial nitritation-anammox process equipped with porous functional suspended carriers was developed at 25°C in a CSTR by controlling dissolved oxygen0.3mg/L. The nitrogen removal performance was almost unchanged over a nitrogen loading rate ranging from 0.5 to 2.5kgNH

The effect of linear alkylbenzene sulfonate (LAS), a typical anionic surfactant, on the sewage treatment by a submerged anaerobic membrane bioreactor (SAnMBR) was investigated by a 243 days operation. The changes of treatment efficiency, methane recovery and sludge activity due to the presence of LAS in sewage was studied in detail. Compared with control (96.8% and 2.87 L/d), lower COD removal (95.2%) and biogas production rate (2.11 L/d) were found at a LAS dosage of 5 mg/L. Besides, LAS was removed by adsorption rather than degradation on the sludge (30–70%). Its adsorption can lead to significant loads in sewage sludge, which then decrease the methane production activity. The recovery efficiency of potential bioenergy was decreased by 20% and 26% at LAS of 2.5 mg/L and 5.0 mg/L, respectively. The results indicated that LAS had a more negative effect on the acetoclastic methanogens than acidogenic microbiota and the LAS inhibition to methanogen activity was responsible for the decrease of SAnMBR performance. Moreover, LAS caused a higher membrane fouling rate than the control experiment due to the microbial self-protection behavior in coping with the LAS in sewage. SAnMBR was hence not suitable to dispose LAS containing sewage with higher concentration.

To achieve the co-production of H2 and CH4, co-digestion of food waste (FW) and paper waste (PW) was performed on the recirculated two-phase anaerobic digestion (R-TPAD). The PW content in the feedstock increased from 0% to 20%, 40% and 50% (in total solids) with FW as the rest. The results showed that bioH2 and bioCH4 were simultaneously and stably produced in the long-term operation. With the increasing PW content, the removal efficiency of volatile solids decreased slightly from 84.9% to 78.4%; the bioH2 yields increased from 50 to 79 NL-H2/kg-VSfed while the bioCH4 yields decreased from 426 to 329 NL-CH4/kg-VSfed. With the fixed amount of FW, adding PW could significantly increase the total bioenergy yields. The relative abundance showed that the key H2-producing bacteria, Caproiciproducens and Thermoanaerobacterium, increased after PW addition. The microbial distribution suggests that the H2-producers were recirculated to the first stage after proliferating in the second stage.

Pore size is one of the most important properties in the successful operation of membrane-based bioprocesses for the treatment of municipal wastewater. The characteristics of two anaerobic membrane bioreactors (AnMBRs), one with a hollow fiber membrane of 0.4 μm pore size (AnMBR1), and the other with a membrane of 0.05 μm pore size (AnMBR2) were investigated for the treatment of real municipal wastewater at room temperature (25 °C) under varied hydraulic retention times (HRTs). Process performance was evaluated in terms of organic removal efficiency, biogas production and membrane filtration behaviours during a long-term continuous operation. Both AnMBRs showed good organic removal performance with COD and BOD removal efficiencies of around 89% and 93%, respectively. High energy recovery potential was achieved, with the biogas yield ranging between 0.20 and 0.26 L-gas/g-CODrem and a methane content of approximately 75%. The differences in the membrane filtration behaviours in the two AnMBRs included different permeate flux and total filtration resistance (Rt). In the AnMBR with a 0.4 μm pore size membrane, an average Rt of 1.08 × 10^12 m−1 was obtained even when the permeate flux was a high 0.274 m/day, while a higher average Rt of 1.51 × 10^12 m−1 was observed in the AnMBR with 0.05 μm pore size membrane even when the flux was a low 0.148 m/day. The off-line membrane cleaning strategy used for AnMBR1 indicated that the membrane restoration efficiency was 90.2%.

The conventional mesophilic digestion of waste activated sludge (WAS) is challenged by the updated wastewater treatment process. A hyper-thermophilic (70 °C)–mesophilic (35 °C) temperature-phased two-stage systems without and with recirculation were employed to upgrade the single-stage mesophilic digestion of waste activated sludge in this study. The solid reduction increased by more than 10% in the two-stage systems. Similar methane production was observed in the single-stage system and two-stage systems, with a methane yield of 0.24 L/g VS added. In the case of two-stage system without recirculation, hyper-thermophilic stage played an important role in COD solubilization, with 34.4% of the WAS solubilized in that stage, while mesophilic stage contributed more in methane production, with 36.2% of COD in the WAS produced as methane in the mesophilic stage. Firmicutes became the most dominant bacteria phylum in the mesophilic stages of two-stage systems as compared to the dominant phylum Proteobacteria in single-stage system, with the genus Methanothermobacter cardinal in the hyper-thermophilic stage. The recirculation in the two-stage system increased the microbial community diversity in the hyper-thermophilic stage, which was one factor to result in improved methane production in the hyper-thermophilic stage.

In order to upgrade the conventional mesophilic anaerobic (MD) of waste activated sludge (WAS), a thermophilic pre-fermentation and a recycle system were introduced to form continuous thermophilic–mesophilic temperature-phased anaerobic digestion (TPAD) and TPAD with recycling capability (TPAD-R). The synchronous operation, with the MD as control, indicated significant improvements in reduction of solids and the ability to produce methane in the TPAD and TPAD-R, with a similar amount of improvement in both systems. VS reduction was improved from about 40% in the MD to 50%, and the methane recovery rates were improved from 0.53 L/g VS destroyed in the MD to 0.63 L/g VS destroyed accordingly. The thermophilic stage in the TPAD and TPAD-R made a large contribution to organic matter degradation and solubilization, and the specific hydrolysis rate in thermophilic stage attained 0.2 gCOD/g VS/d. Furthermore, under experimental conditions, the thermophilic stage in the TPAD and TPAD-R also played an important role in acidogenesis and methanogenesis. The thermophilic pre-fermentation made Firmicutes and Methanosarcina become the main phylum and genus in the mesophilic stage, accounting for 44% and 54%, respectively. The recycle system improved the diversity of bacteria and archaea in the thermophilic stage of the TPAD-R. The TPAD and TPAD-R also achieved about twice the net energy of the MD.

Environmental stresses are assumed to significantly impact the content and concentration of produced extracellular polymeric substances (EPS) and therefore influence the performance of an ananmmox attached film expanded bed (AAFEB) reactor. In this study, a transient high substrate concentration of 2500 mg N L−1 (calculated as the sum of NN4+–N and NO2−–N) for 24 hours stimulated abundant EPS excretion as well as deterioration of anammox granules. The results indicated that a high EPS concentration of 89.6 ± 48.3 mg g−1 VSS resulted in 35.0 ± 0.8% decrease in the granule settling properties and 30.5 ± 0.9% reduction in the total VSS amount. The production of EPS was reasonably attributed to the impact of utilization-associated and stress-associated effects by the substrate. The results of a series of batch experiments indicated that a rapid increase of loosely-bound EPS (LB-EPS) from 41.2 to 114.6 mg g−1 VSS occurred when the substrate concentration steadily increased from 400 to 1000 mg N L−1, in contrast, the tightly-bound EPS (TB-EPS) remained stable at 32.5 ± 2.8 mg g−1 VSS. Thus, the LB-EPS was considered the key factor for the deterioration of granule stability and the substrate concentration should be controlled below 400 mg N L−1 to avoid triggering the accumulation of LB-EPS. Furthermore, the formation and disintegration mechanisms of attached film anammox granules were also elucidated in this study.

The competition between methane-producing archaea and sulfate-reducing bacteria is an important topic in anaerobic wastewater treatment. In this study, an Up-flow Anaerobic Sludge Blanket Reactor (UASB) was operated for 330 days to evaluate the treatment performance of sulfate-rich wastewater. The effects of competition change between methane production and sulfate reduction on the organic removal efficiency, methane production, and electrons allocation were investigated. Synthetic wastewater was composed of ethanol and acetate with a chemical oxygen demand (COD)/SO42− of 1.0. As a result, the COD removal efficiency achieved in long-term treatment was higher than 90%. During the initial stage, methane production was the dominant reaction. Sulfate-reducing bacteria (SRB) could only partially oxidize ethanol to acetate, and methane-producing archaea (MPA) utilized acetate for methane production. Methane production declined gradually over the long-term operation, whereas the sulfate-reducing efficiency increased. However, UASB performed well throughout the experiment because there was no significant inhibition. After the complete reduction of the sulfate, MPA converted the remaining COD into methane.

Thermophilic (55 °C)-mesophilic(35 °C) and hyper-thermophilic(70 °C)-mesophilic TPAD-R (temperature-phased anaerobic digestion with recycle) were conducted to compare and evaluate the operation performance to treat WAS (waste activated sludge) with the MD (conventional mesophilic anaerobic digestion). TPAD-R was based on the TPAD (temperature-phased anaerobic digestion), and introduced a recycle system from the end mesophilic stage to the front stage. Thermophilic-mesophilic TPAD-R produced more biogas 0.99 L/g VS (volatile solids) reduced/d than MD 0.83 L/g VS reduced/d. In thermophilic-mesophilic TPAD-R 35.7% and 18.7% of WAS was converted to methane in the thermophilic stage and in the mesophilic stage, respectively, according to a COD balance. Solids reduction was improved to a similar extent in thermophilic-mesophilic TPAD-R and hyper-thermophilic-mesophilic TPAD-R, which was 10% higher than that in MD (approximately 40% of VS reduction). Hydrolysis, acidogenesis and methanogenesis analysis indicated that thermophilic and hyper-thermophilic stage accelerated the hydrolysis rate of TPAD-R, 0.053 gCOD/gVS/d and 0.040 gCOD/gVS/d, respectively, compared to about 0.025 gCOD/gVS/d in MD. In addition, thermophilic-mesophilic TPAD-R achieved more surplus energy than hyper-thermophilic-mesophilic TPAD-R and MD.

書誌情報のみ, Bibliographic data Only

In order to upgrade the conventional mesophilic anaerobic digestion (MD) of waste activated sludge (WAS), a hyper-thermophilic (70 °C, stage I)–mesophilic (35 °C, stage II) temperature-phased anaerobic digestion system with a recycle system (TPAD-R) was constructed, with MD as a control. The accumulation of solids increased with shorter hydraulic retention time (HRT). Compared with MD, TPAD-R improved the reduction of solids by over 10%, and the removal rate of protein in TPAD-R increased by more than 20%. In stage I of TPAD-R an amount of organic matter was solubilized, in a range between 10 g L−1 and 20 g L−1, as soluble chemical oxygen demand (COD), and played an important role in enhancing hydrolysis and acidification. The specific hydrolysis and acidification rates of stage I reached their maximum values after a HRT of 10 days, 2.367 g COD per g VS per day and 1.120 g COD per g VS per day, respectively. Consequently, the methane yield in TPAD-R, primarily produced in stage II, was also improved, 29% higher than that in MD for a HRT of 10 days. Besides compensating for energy loss, TPAD-R obtained a higher net energy than MD, achieving a net energy which was 3.3 kJ g−1 VS more than that in MD for a HRT of 10 days. The TPAD-R proved to be efficient in upgrading the MD of WAS.

Long-term experiments herein were conducted to investigate the effect of cefalexin (CLX) on methane production during waste activated sludge (WAS) anaerobic digestion. CLX exhibited a considerable inhibition in methane production during the initial 25 days while the negative effect attenuated subsequently and methane production recovered depending on CLX doses used (600 and 1000 mg/L). The highest methane yield reached 450 mL at 1000 mg-CLX/L after 157 days of digestion, 63.8% higher than CLX-free one. Stimulated excretion of extracellular polymeric substances (EPS) by CLX served as microbial protecting layers, creating a suitable environment for microbes' growth and fermentation. Further examination via ultraviolet visible (UV-Vis) spectra also verified the elevated slime EPS, LB-EPS and TB-EPS indicated by UV-254 in the presence of CLX. Unlike the commonly accepted adverse effect, this study demonstrated the beneficial role of CLX in methane production, providing new insights into its true environmental impacts.

Greenhouse gas emissions from different sewage treatment plants: oxidation ditch process, double-circulated anoxic-oxic process and anoxic-oxic process were evaluated based on the survey. The methane and nitrous oxide characteristics were discussed based on the gaseous and dissolved gas profiles. As a result, it was found that methane was produced in the sewer pipes and the primary sedimentation tank. Additionally, a ventilation system would promote the gasification of dissolved methane in the first treatment units. Nitrous oxide was produced and emitted in oxic tanks with nitrite accumulation inside the sewage treatment plant. A certain amount of nitrous oxide was also discharged as dissolved gas through the effluent water. If the amount of dissolved nitrous oxide discharge is not included, 7-14% of total nitrous oxide emission would be overlooked. Based on the greenhouse gas calculation, electrical consumption and the N2O emission from incineration process were major sources in all the plants. For greenhouse gas reduction, oxidation ditch process has an advantage over the other advanced systems due to lower energy consumption, sludge production, and nitrogen removal without gas stripping.

In order to investigate the phase separation and microbial distribution in the TPAD, the conventional thermophilic-mesophilic type (TM-TPAD) and the hyperthermophilic-mesophilic type (HM-TPAD) were operated with a single-stage mesophilic anaerobic digestion (MAD) as control. HM-TPAD accomplished the volatile solids destruction 14.5% higher than MAD. Calculating conversion efficiencies distinguished the separation of acidogenic and methanogenic phases in HM-TPAD, which was not found in TM-TPAD. The differences on microbial distributions also reflected the phase separation in HM-TPAD. The protein degraders, Coprothermobacter had higher abundance in the first stage than the second stage of HM-TPAD but it had similar abundance between the two stages of TM-TPAD. Also, the archaeal communities from the two stages of HM-TPAD shared the least similarity but those from the two stages of TM-TPAD were closely similar.

The operation performance of a novel micro-granule based syntrophic system of nitritation and anammox was studied by controlling the oxygen concentration and maintaining a constant temperature of 25°C. With the oxygen concentration of around 0.11 (

The thermophilic methane fermentation of chicken manure (CM) with a total solids (TS) of approximately 10% was investigated with regard to ammonia inhibition. A gradual increase in total ammonia nitrogen to 6000 mg/L was observed in the case of raw CM fermentation. A distinct rise in VFA accumulation combined with a low methane production of 0.29 L/gVS occurred at a TAN of 4000 ∼ 5000 mg/L. Biogas production completely ceased when TAN reached 8000 mg/L after the addition of NH4HCO3. The high sensitivity of methanogenesis to TAN and free ammonia (FA) was quantitatively confirmed. The IC50 of TAN for methanogenesis, acidogenesis and hydrolysis was 5058, 5305 and 5707 mg/L at a pH value of 8.1 ± 0.2. Similar results but with a lower IC50 were obtained for FA inhibition during fermentation. The microbial community analysis revealed significant differences in hydrogenotrophic methanogens and aceticlastic methanogens before and after inhibition.

Potential reuse of dewatered sludge (DS) and municipal solid waste incineration (MSWI) bottom ash as components to develop controlled low-strength material (CLSM) was explored. The effects of DS:MSWI bottom ash:calcium sulfoaluminate (C S ¯ A) cement ratio and thermal treatment of MSWI bottom ash at 900 °C on the mechanical and microstructural properties of CLSM were intensively studied to optimize the process. Results showed DS and MSWI bottom ash could be utilized for making CLSM. The CLSM prepared with milled MSWI bottom ash gave higher unconfined compressive strength (UCS) of 2.0–6.2 MPa following 1 year of curing at 1.0:0.1:0.9 ≤ DS:MSWI bottom ash:C S ¯ A ≤ 1.0:0.8:0.2. However, the corresponding strengths for CLSM containing thermally treated MSWI bottom ash ranged from 0.7 to 4.6 MPa, decreasing 26–65%. The microstructural analysis by X-ray powder diffraction (XRD), Fourier transforms infrared spectroscopy (FT-IR), as well as scanning electron microscopy (SEM) combined with an energy dispersive X-ray spectroscopy (EDS) revealed that ettringite (C 3 A·3C S ¯ ·H 32 , or AFt) crystals were the most important strength-producing constituents which grew into and filled the CLSM matrix pores. Milled MSWI bottom ash addition favored the formation of highly crystalline AFt phases and accordingly enhanced compressive strengths of CLSM specimens. In contrast, thermal treatment at 900 °C produced new phases such as gehlenite (Ca 2 Al 2 SiO 7 ) and hydroxylapatite (Ca 5 (PO 4 ) 3 (OH)), which deteriorated the pozzolanic activity of bottom ash and caused the strengths to decrease. Leaching tests evidenced that leachable substances from CLSM samples exhibited negligible health and environmental risks. The results of this study suggested that MSWI bottom ash can be effectively recycled together with DS in developing CLSM mixtures with restricted use of C S ¯ A cement.

A continuous stirred tank reactor was used for the dark hydrogen fermentation of cellulose by mixed microflora at hyper-thermophilic temperature (70 ± 1 °C) for 240 days. A total of twenty six batch experiments were conducted to investigate the effect of temperature on the activity of cellulosic-hydrogen producing bacteria. The results show that the system reached a steady state condition after 90 days. A stable hydrogen yield of 7.07 ± 0.23 mmol H2/g cellulose was maintained for 150 days with acetate, butyrate, ethanol and propionate as main soluble byproducts. Analysis of 16S rRNA sequences showed that the cellulolytic bacteria were close to Thermoanaerobacterium genus. The cellulosic-hydrogen producing bacteria were able to utilize the cellulose or glucose within a wide range of fermentation temperatures (45–80 °C) to produce hydrogen. The activation energy for cellulose and glucose were estimated at 133.2 and 117.7 kJ/mol, respectively.

A 12L mesophilic CSTR of chicken manure fermentation was operated for 400 days to evaluate process stability, inhibition occurrence and the recovery behavior suffering TAN concentrations from 2000 mg/L to 16,000 mg/L. A biogas production of 0.35-0.4 L/gVS(in) and a COD conversion of 68% were achieved when TAN concentration was lower than 5000 mg/L. Ammonia inhibition occurred due to the addition of NH4HCO3 to the substrate. The biogas and COD conversion decreased to 0.3 L/gVS(in) and 20% at TAN 10,000 mg/L and was totally suppressed at TAN 16,000 mg/L. Carbohydrate and protein conversion decreased by 33% and 77% after inhibition. After extreme inhibition, the reactor was diluted and washed, reducing TAN and FA to 4000 mg/L and 300 mg/L respectively, and the recovered biogas production was 0.5 L/gVS(in). The extended Monod model manifested the different sensitivities of hydrolysis, acidogenesis and methanogenesis to inhibition. VFA accumulation accompanied an increase in ammonia and exerted a toxic on microorganism.

We developed a new cathode for a visible ray flat plane-emission device formed from a mixture of high crystallized single-wall carbon nanotubes (SWNTs) dispersed into an organic In2O3-SnO2 solution. A thin film cathode was fabricated by a simple coating process of the mixture onto a substrate. The turn-on field of a diode using the cathode was 1.2 V/μm and the brightness homogeneity in that plane was within 5 %. The brightness fluctuation from the lighting device could be reduced to within 1 % by employing high crystallized SWNTs. Furthermore, brightness efficiency, which is an important factor in comparing luminance devices, achieved more than 50 lm / W. This flat plane-emission device has the potential to provide a new approach to lighting in our life style and it also contributes to energy-saving through its low power consumption.

The accumulation of soluble microbial production (SMP) in an anammox attached film expanded bed (AAFEB) and its effect on the reactor performance were investigated in this study. During the long-term experiment, an extended HRT resulted in the accumulation of SMP and the change of treatment performance. When the SMP increased from 10.5±1.5mgL-1 to 31.7±6.4mgL-1 with the increase of influent TN concentration from 313mgL-1 to 2500mgL-1, the TN removal efficiency was stable. However, when the influent TN concentration was 3500mgL-1, the SMP concentration increased higher than 100mgL-1, the reactor soon became inhibited. Bath tests indicated that both the specific anammox activity (SAA) and the substrate tolerance ability decreased during the stable operation phases, whereas the specific denitrification activity (SDA) was significantly enhanced. In addition, N2O emissions in the anammox-denitrifier symbiotic system were greater than in the conventional nitrogen removal process.

A lab-scale upflow anaerobic sludge blanket (UASB) has been run for 250days to investigate the influence of influent COD/SO4(2-) ratios on the biodegradation behavior of starch wastewater and process performance. Stepwise decreasing COD/SO4(2-) ratio enhanced sulfidogenesis, complicating starch degradation routes and improving process stability. The reactor exhibited satisfactory performance at a wide COD/SO4(2-) range ⩾2, attaining stable biogas production of 1.15-1.17LL(-1)d(-1) with efficient simultaneous removal of total COD (73.5-80.3%) and sulfate (82.6±6.4%). Adding sulfate favored sulfidogenesis process and diversified microbial community, invoking hydrolysis-acidification of starch and propionate degradation and subsequent acetoclastic methanogenesis; whereas excessively enhanced sulfidogenesis (COD/SO4(2-) ratios

Long-term performance of a lab-scale UASB reactor treating starch wastewater was investigated under different hydraulic retention times (HRT). Successful start-up could be achieved after 15days' operation. The optimal HRT was 6h with organic loading rate (OLR) 4g COD/Ld at COD concentration 1000mg/L, attaining 81.1-98.7% total COD removal with methane production rate of 0.33L CH4/g CODremoved. Specific methane activity tests demonstrated that methane formation via H2-CO2 and acetate were the principal degradation pathways. Vertical characterizations revealed that main reactions including starch hydrolysis, acidification and methanogenesis occurred at the lower part of reactor ("main reaction zone"); comparatively, at the up converting acetate into methane predominated ("substrate-shortage zone"). Further reducing HRT to 3h caused volatile fatty acids accumulation, sludge floating and performance deterioration. Sludge floating was ascribed to the excess polysaccharides in extracellular polymeric substances (EPS). More efforts are required to overcome sludge floating-related issues.

An investigation was conducted on a self-agitation anaerobic baffled reactor (SA-ABR) with agitation caused solely by the release of stored gas. The compound in the reactor is mixed without the use of any mechanical equipment and electricity. The computational fluid dynamics (CFD) simulation used to provide details of the flow pattern and information about the agitation process and a solid basis for design and optimization purposes. Every self-agitation cycle could be separated into the pressure energy storage process, the exergonic process and the buffer stage. The reactor is regarded as the combination of continuous stirred tank reactor and a small plug flow reactor. The liquid level and diffusion varies widely depending on the length of the U-tube. The compound transition phenomenon in the 1st chamber mainly occurs during the energy exergonic process and buffer stage. The fluid-diffusion in the 3rd and 4th chambers mainly happens after the buffer period.

We developed and successfully fabricated a plannar light source device using a phosphor screen with single-walled carbon nanotubes (SWCNTs) as field emitters in a simple diode structure composed of the cathode containing the highly purified and crystalline SWCNTs dispersed into an organic In2O3-SnO2 precursor solution and a non-ionic surfactant. The cathode was activated by scratching process with sandpaper to obtain a large field emission current with low power consumption. The nicks by scratching were treated with Fourier analysis to determine the periodicity of the surface morphology and designed with controlling the count number of sandpapers. The anode, on the other hand, was made with phosphor deliberately optimized by coverage of ITO nanoparticles and assembled together with the cathode by the new stable assembling process resulting to stand-alone flat plane-emission panel. The device in a diode structure has a low driving voltage and good brightness homogeneity in that plane. Furthermore, field emission current fluctuation, which is an important factor in comparing luminance devices too, has a good stability in a simple diode panel. The flat plane-emission device employing the highly purified and crystalline SWCNTs has the potential to provide a new approach to lighting in our life style.