Illumination enhances methane production from thermophilic anaerobic digestion.

Incandescent lamp illumination enhanced methane production from a thermophilic anaerobic digestion reactor (55 degrees C) supplied with glucose. After 10 days of operation, the volume of methane produced from light reactors was approximately 2.5 times higher than that from dark reactors. A comparison of the carbon balance between light and dark conditions showed that methane produced from hydrogen and carbon dioxide in the light reactors was higher than that from the dark reactors. When hydrogen or acetate was fed into the reactors, methane production with added hydrogen was faster and higher under light conditions than under dark conditions. The use of blue light-emitting diodes also enhanced methane production over that under dark conditions. The 16S rRNA gene copy numbers for Methanothermobacter spp. in the light reactor and in the dark reactor were at the same level. The copy number for Methanosarcina spp. in the light reactors was approximately double than that in the dark reactors. These results suggest that blue light enhances the methanogenic activity of hydrogenotrophic methanogens.

Phylogenetic description of immobilized methanogenic community using real-time PCR in a fixed-bed anaerobic digester.

After immobilization of anaerobes on polyurethane foam in a thermophilic, fixed-bed, anaerobic digester supplied with acetate, the results of real-time PCR analysis indicated that the major immobilized methanogenic archaea were Methanosarcina spp., and that the major free-living methanogenic archaea were Methanosarcina and Methanobacterium spp. 16S rRNA gene densities of Methanosarcina spp. and Methanobacterium spp. immobilized on the polyurethane foam were 7.6x10(9) and 2.6x10(8) copies/cm3, respectively. Immobilized methanogenic archaea could be concentrated 1000 times relative to those in the original anaerobically digested sludge from a completely mixed thermophilic digester supplied with cattle waste. On the other hand, immobilized bacteria could be concentrated only 10 times. The cell densities of the immobilized methanogenic archaea and bacteria were higher than those of the free-living methanogenic archaea and bacteria in the reactor. The results of clone analysis indicate that the major methanogenic archaea of the original thermophilic sludge are members of the order Methanomicrobiales, and that the major methanogenic archaea immobilized on the polyurethane foam are Methanosarcina spp., and those of the liquid phase are Methanobacterium spp. The results of the real time PCR analysis approximately agree with those of the clone analysis. These results indicate that real-time PCR analysis is useful for quantitatively describing methanogenic communities.

Removal of 3-chlorobenzoate using an upflow anaerobic sludge blanket reactor under light conditions.

The possibility of 3-chlorobenzoate removal from water using an upflow anaerobic sludge blanket (UASB) reactor without the addition of any extra dechlorinating culture under light conditions has been studied on a laboratory scale. Benzoate removal was observed in the first three months of operation under light conditions, but the 3-chlorobenzoate removal was not observed. After three months of operation under light conditions, the 3-chlorobenzoate concentration in the UASB reactor effluent gradually decreased to less than 1 mg x h(-1). The 3-chlorobenzoate concentration in the effluent did not increase under dark conditions. The DOC concentration in the effluent decreased according to the removal of the 3-chlorobenzoate by the UASB granules. These results indicated that granules in the UASB reactor provided the 3-chlorobenzoate removability after 80-100 d of adaptation to the 3-chlorobenzoate, and that the UASB reactor is useful for 3-chlorobenzoate removal.

Characterization of lighted upflow anaerobic sludge blanket (LUASB) method under sulfate-rich conditions.

Growth of phototrophic bacteria was induced from granules in a lighted upflow anaerobic sludge blanket (LUASB) reactor supplied with an organic-acid-based medium containing 141.7 mg S.l(-1) of SO4(2-) under light conditions (100 microE.m(-2).s(-1)). We investigated the population dynamics of phototrophic bacteria in the LUASB reactor and the performance of the LUASB reactor for wastewater treatment and poly-beta-hydroxybutyrate (PHB) production under anaerobic light and sulfate-rich conditions. In vivo absorption spectra and a colony count suggested that populations of Rhodopseudomonas palustris and Blastochloris sulfoviridis in the LUASB reactor supplied with a medium containing 574.4 mg S.l(-1) of SO4(2-) under light conditions were lower than those supplied with a medium containing 1.0 or 141.7 mg S.l(-1) of SO4(2-) under parallel conditions. Removal efficiencies of ammonium and phosphate in the LUASB reactor supplied with the medium containing 141.7 mg S.l(-1) of SO4(2-) under light conditions were higher than those under parallel conditions but without illumination. The difference in the results of runs under light or dark conditions suggested that the ammonium and phosphate ion removal efficiencies were improved by increasing the amount of phototrophic bacterial biomass in the LUASB reactor under sulfate-rich conditions. The average PHB production rates of the bacterial cells recovered from the effluent of the LUASB reactor supplied with a medium containing 141.7, 283.5 or 574.4 mg S.l(-1) of SO4(2-) were 1.0-2.9 mg.l(-1)-reactor.d(-1) and the average PHB content based on the dry bacterial biomass was 1.4-3.6%.

Microalgal cultivation in a solution recovered from the low-temperature catalytic gasification of the microalga.

Microalgal cultivation in a solution recovered from the low-temperature catalytic gasification of the microalga itself was studied. The growth of Chlorella vulgaris in 75-300-fold diluted recovered solution containing phosphate, magnesium ions and micro-elements was comparable to that in the standard culture medium. It was suggested that C. vulgaris could use ammonium in the recovered solution as its nitrogen source and at the same time could provide a source of biomass which was recycled via gasification.

Isolation and characterization of phototrophic bacteria growing in lighted upflow anaerobic sludge blanket reactor.

Two strains of phototrophic bacteria were isolated from the effluent of a lighted upflow anaerobic sludge blanket (LUASB) reactor. Their 16S rRNA gene sequences and phenotypic characteristics suggested that two isolates were Rhodopseudomonas palustris and Blastochloris sulfoviridis strains.

Organic acid consumption of phototrophic bacteria in a lighted upflow anaerobic sludge blanket reactor.

It was previously suggested that a population of phototrophic bacteria, Rhodopseudomonas palustris strain RN1 and Blastochloris sulfoviridis strain GN1 could be induced from granules in a lighted upflow anaerobic sludge blanket (LUASB) reactor. The present study showed that both strains RN1 and GN1 could use acetate, propionate, butyrate, and lactate as electron donors under anaerobic light conditions. The composition of organic acids in the effluent from the LUASB reactor was studied to investigate competitive consumption between acetogenic bacteria, methanogens, and phototrophic bacteria in the reactor. When acetate, propionate and lactate were supplied to the reactor, a small amount of acetate and propionate was observed in the effluent under light conditions. The concentrations of acetate and propionate increased under dark conditions compared with those under light conditions using organic acid and peptone media as the influent. When starch was supplied to the reactor, the concentrations of formate, acetate, propionate, butyrate, and lactate in the effluent were less than 0.5 mg C.l(-1) during operation under light and dark conditions. The concentrations of ammonium and phosphate in the effluent under dark conditions were higher than those under light conditions. These results suggested that phototrophic bacteria in the LUASB reactor consumed acetate and propionate as well as ammonium and phosphate in competition with methanogens and acetogenic bacteria.

Lighted upflow anaerobic sludge blanket.

The upflow anaerobic sludge blanket (UASB) method has been developed as an efficient anaerobic wastewater treatment process; however, the performance of this process in the removal nitrogenous compounds and phosphate is not high. Here, we present the water treatment performance of a lighted upflow anaerobic sludge blanket (LUASB) reactor and propose a novel LUASB concept. A population of phototrophic bacteria was induced from UASB granules under light conditions (100 microE x m(-2) x s(-1)). The ammonium and phosphate ion removal efficiencies of the LUASB reactor were higher than those of a UASB reactor. The difference in the results from runs under light and dark conditions suggests that the efficiencies of ammonium and phosphate ion removal were improved by an increase in the phototrophic bacteria in the LUASB reactor. The UASB granule can decompose a variety of organic substances; therefore, the LUASB method could also be effective for producing phototrophic bacterial biomass and polyhydroxyalkanoates (PHAs) from various wastewaters.

Treatment of liquid fraction separated from liquidized food waste in an upflow anaerobic sludge blanket reactor.

Thermochemical liquidization as a pretreatment for anaerobic digestion of food waste was studied using a laboratory-scale upflow anaerobic sludge blanket (UASB) reactor for a period of 82 d. Model food waste (approximately 90 wt% moisture content) was thermochemically liquidized at 175 degrees C for 1 h. The liquidized food waste was separated into a solid phase (6-10 wt%) and a liquid phase (85-89 wt%). The diluted liquid phase was continuously treated by anaerobic digestion using a UASB reactor at 35 degrees C. The volumetric loading rate was increased stepwise to 6.4-7.2 g total organic carbon (TOC)/l-reactor/d. Methane production was found to be approximately 0.35-0.61 l/g-TOC removed. The range of TOC removal efficiencies was 67-69% at an influent TOC concentration of 10.1-11.1 g/l and a volumetric loading rate of 4.8-5.3 g-TOC/l-reactor/d. This treatment process using an UASB reactor could be suitable for resource recovery from food waste.

Wastewater treatment and poly-beta-hydroxybutyrate production using lighted upflow anaerobic sludge blanket method.

We investigated the performance of a lighted upflow anaerobic sludge blanket (LUASB) reactor for wastewater treatment and poly-beta-hydroxybutyrate (PHB) production. Phototrophic bacteria were induced from UASB (upflow anaerobic sludge blanket) granules under light conditions (100 microE.m(-2).s(-1)). The ammonium and phosphate ion removal efficiencies of the LUASB reactor were higher than those of the UASB reactor. The difference in the results from runs under light and dark conditions suggested that the ammonium and phosphate ion removal efficiencies were improved by increasing the amount of phototrophic bacteria in the LUASB reactor. The average production rate of PHB from the biomass in the effluent from the LUASB reactor was 6.6-14.0 mg.l(-1)-reactor.d(-1) using acetate-based media and the average PHB content based on the dry bacterial biomass was 15.1-25.3%. The PHB concentration increased by reincubation of the effluent from the LUASB reactor with sodium acetate under light conditions. The UASB granular sludge can decompose a variety of organic substances and in addition the LUASB method can remove ammonium and phosphate ions. The LUASB method thus appears to be appropriate for wastewater treatment and production of phototrophic bacteria and PHB from various wastewaters.

Effects of glucose addition and light on current outputs in photosynthetic electrochemical cells using Synechocystis sp. PCC6714.

The effects of glucose addition and light on the current outputs in electrochemical cells using a cyanobacterium Synechocystis sp. PCC6714 were investigated under photo- and chemoheterotrophical conditions. The addition of glucose to the anode solutions of the electrochemical cells resulted in a rapid increase in the current outputs under both light and dark conditions. Although the coulombic outputs were almost the same between under light and dark conditions, the rate of glucose consumption was faster under illumination than in the dark. The total sugar content in the cells of strain PCC6714 increased with the addition of glucose and the total sugar accumulated remained intact during the discharge under illumination, while it decreased gradually in the dark. When the light was switched off after the addition of glucose, the current output markedly increased. The coulombic outputs obtained after darkening were 10 to 80 times larger than that obtained by the addition of glucose under the continuous light or dark conditions. Synechocystis sp. completely incorporated 0.14 mM and 0.42 mM glucose for 1 h and 3 h, respectively, under illumination. There was no difference in the coulombic outputs between 1 h and 12 h illumination times in the electrochemical cells with 0.14 mM glucose. When the light was switched off after 1 h illumination in the electrochemical cells with 0.42 mM glucose, the coulombic output obtained from the electrochemical cell was lower than that in the electrochemical cell with 12 h illumination. This indicates that the current output was produced with higher efficiency with glucose incorporated under illumination than that in the case of glucose incorporated after darkening. The highest coulombic yield of 54% in this experiment was obtained by darkening in the electrochemical cell with 0.14 mM glucose.

Spinnability of Starch Pastes.

We have developed apparatus to assess spinnability that uses an impedance to prevent of electrolysis. The spinning distance and the stress confirmed by measurement of dial gauge. A total of 10 starch pastes was prepared from corn, sago, katakuri, sweet potato, kuzu, edible canna, cassava, Indian lotus root, bracken, and potato, at 2% and 4% concentrations. The spinning distance of each starch paste showed a dependence on the concentration and the tensile velocity. The strain at the point of maximum stress increased in all samples with increases in the tensile velocity. The spinning energy increased with increase in the tensile velocity, with a particularly large dependence on the tensile velocity of potato. Cluster analysis was done using the spinning property values of 4% starch pastes as the parameters, which showed a division at a distance of 20, yielding four clusters, with each cluster showing a distinctive spinning pattern.