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Volume 40 (2004)
- Issue 4 Pages 125-
- Issue 3 Pages 77-
- Issue 2 Pages 37-
- Issue 1 Pages 1-
Volume 40, Issue 2
Displaying 1-5 of 5 articles from this issue
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HIROKI MIYANISHI, AKIHIRO KIMURA, SINSUKE KASAHARA, MUNETAKA ISHIKAWA2004 Volume 40 Issue 2 Pages 37-44
Published: June 15, 2004
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSIn this study, the effects of bioactive reagent (saponin) on the anaerobic digestion were investigated. In order to clarify the effectiveness of saponin, continuous experiments with the presence of saponin were conducted at mesophilic temperature (38°C) on the mixed substrate of night soil and garbage. The amounts of added saponin were 0, 20, 50ppm. The obtained results are as follows.
1) The rates of hydrolytic, acidogenenic and methanogenenic were increased by the saponin addition. The increments of the rates were 1.3, 1.4 and 1.2 times, respectively. These result shows that the addition of saponin is effective for upgrading of anaerobic digestion. The acidogenesis rate was especially increased.
2) The increment of acidogenenic rate was 1.2 times higher than that of methanogenesis by the saponin addition. This caused the accumulation of volatile fatty acid. It indicates that methanogenesis is rate-limiting step in the over all process of anaerobic digestion.
3) Compared with the results of 20ppm and 50ppm of saponin addition, there was little difference between all process of anaerobic digestion. It seems that the addition of 20ppm of saponin is enough for the rate increase of the reaction at the condition of this study.View full abstractDownload PDF (952K) -
HU JIN, MAKIKO MORITA, YASUNORI KAWAGOSHI, SHIGERU MARUYAMA, TEIZI URA ...2004 Volume 40 Issue 2 Pages 45-52
Published: June 15, 2004
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSAvailabilities of biodegradable plastics as a carbon source for biological denitrification process were studied. Four kinds of biodegradable plastics (poly-β-hydroxybutyrate, CELLGREEN, LACTY BIONOLLE) were used for batch denitrification experiments with activated sludge and continuous denitrification experiment using soil column. The denitrification activities and weight-losses before and after experiments were compared. The highest denitrification activity was obtained in the experiment with PHB (bacteria produced plastic) as a carbon source, and 90.2% of initially added 10g of PHB pellets was degraded. CELLGREEN (natural compound) was also utilized in denitrification process, and 32.6% of initially added 10g of CELLGREEN pellets was degraded. On the other hand, the weight-loss was not observed in LACTY and BIONOLLE (both are chemical synthesis palstic), which indicated that these types of biodegradable plastic were not easily degraded by activated sludge and soil microorganisms. The decomposition of surface of PHB plastic pellet in soil column was slower than that in activated sludge, which suggested the advantage of PHB for long-term bioremediation in nitrate-polluted soil and ground water. After the continuous denirtrification experiment, the total number of bacteria and the number of PHB-utilizing denitrifier was counted to be 3.4×109cells⋅wet-g-1 and 8.5×106cells⋅wet-g-1 respectively.View full abstractDownload PDF (4128K) -
MIYOKO WAKI, KAZUYOSHI SUZUKI, TAKASHI OSADA, YASUO TANAKA2004 Volume 40 Issue 2 Pages 53-61
Published: June 15, 2004
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSMethane is utilizable as a carbon source for nitrogen removal from wastewater that lacks organic carbon sources. In this study, we confirmed that methane-dependent denitrification by biomass from the biogas scrubber of a swine wastewater treatment plant occurs in the presence of CH4 and O2, but not in the presence of CH4 alone. We further found that the CH4/O2 ratio in supplied gas needs to be more than 1.0 for high nitrate removal activity using methane. In this condition, methane oxidation activity was maximized, and DO concentration decreased to less than 0.3 mg/l. It was supposed that the O2 consumption rate owing to methane oxidation was higher than the O2 transfer rate from the gas phase to the liquid phase, and consequently DO concentration declined to a low level suitable for denitrification. Moreover, when the CH4/O2 ratio exceeded 1.0, high nitrate removal activity occurred under incubation with high O2 partial pressure. Heightening the O2 supply rate while maintaining a CH4/O2 ratio greater than 1.0 would improve the NO3- removal activity. Sustaining a biomass with high concentration and controlling DO concentration would be required to avoid excess O2 supply relative to the O2 consumption rate by microorganisms.View full abstractDownload PDF (1094K) -
KEISUKE IWAHORI, NAOYUKI MIYATA, YASUHIRO YAMAMOTO, DAIJIRO SONE, KOTA ...2004 Volume 40 Issue 2 Pages 63-70
Published: June 15, 2004
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSThe comet assay has been widely used in genetic toxicology, environmental biomonitoring and clinical investigations. However, many indices are typically used to evaluate degree of DNA damage in comet assay and various bioassays have also been employed for the mutagenicity test of environmental waters. In this study, the DNA damage evaluation characteristics of each index were examined and the numerical data obtained were normalized on the basis of untreated controls to compare with data obtained under different experiment conditions. For confirmation of detection characteristics and sensitivity, comet assay were compared with Ames test, umu test and Rec assay. Among the comet assay indices, tail moment most effectively represented the sensitivities of individual cells and dose-dependent DNA damage was detected. By normalization of tail moment, comparison of experimental results in different conditions was simplified. The comet assay did not have the capacity to detect DNA cross-linking agent. The comparison of data revealed that mutagenicity detection sensitivity for comet assay is greater than Ames test and Rec assay and as high as that of umu test.View full abstractDownload PDF (1015K) -
Young-O Kim, Hai-Uk Nam, Tae-Joo Park, Tae-Ho Lee2004 Volume 40 Issue 2 Pages 71-76
Published: June 15, 2004
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSThe effect of media types on organics and nitrogen removal and microbial populations in a fixed biofilm an anaerobic-, anoxic-, and aerobic reactor system (AAO process) were studied at two different HRTs. The reactors in the AAO process were packed with two different types of media: a net cross-linked type SARAN media and the other granular type Synthetic Activated Ceramic (SAC) media. The process was applied to treat a wastewater taken from an influent line of ‘Janglim’ wastewater treatment plant in Korea. At two different HRT of 8.0 hr and 5.2 hr, the AAO process with SARAN media showed 80.2% and 79.8% of COD removal and 70.2% and 72.3% of ammonia nitrogen removal, while the process with SAC media showed 79.8% and 78.1% of COD removal and 90.5% and 85.4% of ammonia nitrogen removal. The microbial population in biofilm formed on SAC media (1.78 ×1012 cells/cm2) was two orders of magnitude greater in cell number than that of SARAN media (7.80 × 1010 cell/cm2) . The population ratios of heterotrophs and autotrophs in biofilm on the SARAN media were 0.87-0.88 and 0.12-0.13, respectively, but the ratios on the SAC media were 0.64-0.76 for heterotrophs and 0.24-0.36 for autotrophs. Consequently, the AAO process with SAC media could contain higher biomass concentration and autotrophs/heterotrophs fraction than the process with the SARAN media. The results showed that biological nutrient removal efficiency in a fixed biofilm reactor is deeply influenced by not only operation conditions but also media characteristics and microbial populations in biofilms on the media.View full abstractDownload PDF (810K)
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