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Volume 38 (2002)
- Issue 4 Pages 175-
- Issue 3 Pages 117-
- Issue 2 Pages 57-
- Issue 1 Pages 1-
Volume 38, Issue 1
Displaying 1-6 of 6 articles from this issue
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KAZUYO YUMIHARA, TORU SHIGEMATSU, KEISUKE HAMADA, SHIGERU MORIMURA, KE ...2002 Volume 38 Issue 1 Pages 1-9
Published: March 15, 2002
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSThe biodegradability of eight aromatic compounds; benzyl alcohol, phenol, toluene, terephthalic acid, aniline, benzensulfonic acid, 2, 4, 6-trichlorophenol and m-nitrophenol; was evaluated under methanogenic conditions. Benzyl alcohol and phenol were termed as readily biodegradable aromatic compounds based on the net gas production. Toluene, terephthalic acid, aniline, an benzenesulfonic acid were termed as persistent compounds. 2, 4, 6-trichlorophenol and m-nitrophenol were caused a toxicity response of the methanogenesis. All compounds, which were suggested to be toxicity compounds by the biodegradability test, showed toxicity to aceticlastic methanogens. The anaerobic continuous treatments of synthetic wastewaters with aniline or terephthalic acid as the carbon sources were carried out. Glucose or acetic acid, used as co-substrates, showed stimulatory effect on the degradation of aniline or terephthalic acid. The degradation efficiency of aniline and terephthalic acid were more than 80% and 90%, respectively, in the treatments of synthetic wastewaters with acetic acid and aniline or terephthalic acid at the mole ratio (acetic acid / aniline or terephthalic acid) over 10.0 at a TOC loading rate of 0.5g/l⋅d.View full abstractDownload PDF (1118K) -
LEU THO BACH, ZAFAR IQBAL BHATTI, KENJI FURUKAWA2002 Volume 38 Issue 1 Pages 11-20
Published: March 15, 2002
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSHigh strength sugary wastewater was continuously treated in a 12.5l UASB reactor operated at 37°C for 440 days. This included 350 days of loading rate study during which volumetric loading rate (VLR) was increased from 0.3 to 24 g-TOC/l·d and 90 days of investigation at a stable loading rate of 8 g-TOC/l·d. The UASB reactor achieved 80-98% TOC reduction at VLRs up to 16 g-TOC/l·d. Mass balance calculations revealed that 46% and 49% of TOC removed was converted to CO2 and CH4, respectively while the rest was converted to biomass with an average observed sludge yield of 0.094 g-VSS/g-TOC. The C: N: P ratio in the wastewater, pH, volatile fatty acid (VFA) concentration of the effluent and hydraulic retention time (HRT) were all correlated with the removal efficiency of the reactor. For achievement of effective TOC removal efficiencies, these parameters must be maintained at C: N: P=350: 10: 2; pH, 6.8-7.2; VFAs, less than 1000mg/l; and HRT, greater than 12 hr. The microbial structure of the granules was elucidated and microorganisms resembling the Methanobacterium and Methanobrevibacter genera were found to be dominant in the granular sludge cultivated during the period of loading rate increases. However, Methanothrix-like methanogens were found to be dominant in granular sludge cultivatedduring the period with a stable loading rate of 8 g-TOC/l·d. And loading rate is a majoroperational parameter in a UASB reactor for selection of granular sludge with better characteristics such as granule size, settling velocity, MLSS and VSS concentration.View full abstractDownload PDF (3208K) -
TAKAYUKI NISHIO, TARO YOSHIKURA, ISAO FUKUNAGA2002 Volume 38 Issue 1 Pages 21-28
Published: March 15, 2002
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSNitrification by autotrophic bacteria is sensitive to low temperature and nitrification efficiency decreases in winter, however, the activity can be maintained when phosphate, which is eliminated through a coagulation-sedimentation process in potable water treatment plants, is amended prior to sand and GAC filtration. We examined seasonal changes in the population of nitrifying bacteria during the water treatment process and the effect of phosphate amendment in the laboratory. The population densities of nitrifying bacteria in the biofilm attached to sand and GAC observed in winter were of the same order as those in other seasons. The potential nitrifying activity in winter was about 0.5-to 1.8-fold that in summer when examined at 30°C. Filter sand seemed to be more sensitive to low temperatures than GAC as seasonal deviations in nitrifying activities were larger in sand. The immediate effect of phosphate addition was confirmed using a sand column and the population of ammonia-oxidizing bacteria did not increase significantly after 3 weeks of incubation. Phosphate addition enhanced ammonia-elimination rate more than nitrification products accumulation rate. When nitrifying activity was inhibited by the addition of allylthiourea, the respiration in phosphate-amended culture was more active than in culture without phosphate. Thus a possibility remained that addition of phosphate might have enhanced ammonification by heterotrophic bacteria in the biofilm resulting in an increase in nitrifying activity.View full abstractDownload PDF (934K) -
YASUHIRO YAMAMOTO, MITSURU INOUE, OSAMU NISHIMURA, YUHEI INAMORI, MASA ...2002 Volume 38 Issue 1 Pages 29-38
Published: March 15, 2002
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSAn advanced technique of dripping the thick iron solution was developed and applied to on-site domestic wastewater treatment systems. The thick iron solution was obtained by heating and melting FeCl3⋅6H2O crystals.
By using the new technique, the T-P concentration of the treated water decreased to less than 1mg·l-1 when the thick iron solution was added at an Fe/P molar ratio of 1.75. The addition of thick iron solution did not affect the removal of BOD, COD, SS and T-N.The T-P concentration of the treated water increased when coagulated sludge containing ferric phosphate was in contact with the anaerobic sludge in the tank for along time. This problem could be solved by improving the process to prevent such contact. It was also shown that the addition of thick iron solution increased the volume of sludge by about 30%.View full abstractDownload PDF (1249K) -
NAOSHI FUJIMOTO, MASATOSHI SOMA, MAIKO YOSHIDA, MASAHARU SUZUKI, RIKIY ...2002 Volume 38 Issue 1 Pages 39-45
Published: March 15, 2002
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSThe production of microcystin by a nutrient-starved Microcystis viridis culture with a nutrient gradient was examined. The specific production rate of microcystin increased with increasing nitrate and phosphate concentrations. The specific production rates of nitrate-starved cultures after nitrate supply were higher than those of phosphate-starved cultures after phosphate supply showing that nitrogen is a more important nutrient for microcystin production than phosphorus. The time course of microcystin production by nitrate-starved M.viridis after nitrate supply was evaluated at 2h intervals. The microcystin-RR content increased to more than 2-fold within 24 hrs. An increase in dry weight was not observed within 24 hrs, showing microcystin was produced prior to cell growth for nitrogen-starved M. viridis. The specific production rate of microcystin-RR seemed to increase with increasing nitrate cell quota, which suggested that the nitrogen cell quota might regulate the rate of production of microcystin in lakes and reservoirs.View full abstractDownload PDF (782K) -
YASUHIRO YAMAMOTO, YUJI MIURA, MITSURU INOUE, NAOSHI FUJIMOTO, YUHEI I ...2002 Volume 38 Issue 1 Pages 47-55
Published: March 15, 2002
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSA simultaneous removal of nitrogen and phosphorus technology in small-scale domestic wastewater treatment was developed. Physicochemical phosphorus removal systems such as the coagulation method, electrolysis of iron method and electrolysis of aluminum method were combined with anaerobic filter bed-biological filtration process and removal efficiencies of organic matter, nitrogen and phosphorus as well as sludge generation were investigate.
It was demonstrated that these systems improved the organic matter and phosphorus removal efficiencies. Moreover, the denitrification rate improved, which could contribute to stabilizing the nitrogen removal efficiency in this process, as well as reducing the volume of the anaerobic filter bed tank. The water quality of the effluent was less than BOD10mg⋅l-1, T-N10mg⋅l1 and T-P1 mg⋅l1. To achieve this efficiency with the coagulation method, it was necessary to closely manage the generated sludge. With the electrolysis of iron method, a high phosphorus removal efficiency was achieved under the general maintenance and management of generated sludge. With the electrolysis of aluminum method, although an extremely high removal efficiency was achieved, it was necessary to investigate the conditions for controlling the elution of aluminum ion to stabilize the phosphorus removal efficiency. These findings clarified that by incorporating the physicochemical phosphorus removal system with anaerobic filter bed-biological filtration process, the simultaneous nitrogen and phosphorus removal system could be established.View full abstractDownload PDF (1125K)
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