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Volume 41 (2005)
- Issue 4 Pages 159-
- Issue 3 Pages 113-
- Issue 2 Pages 51-
- Issue 1 Pages 1-
Volume 41, Issue 2
Displaying 1-6 of 6 articles from this issue
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ORIGINALS
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HIROYUKI TAKASUNA, YASUO OZAKI, KAORU ABE2005 Volume 41 Issue 2 Pages 51-59
Published: 2005
Released on J-STAGE: July 07, 2006
JOURNAL FREE ACCESSZeolite has been often used for water purification by plant and bed filter materials. Kanumatsuchi, a kind of volcanic ash soil, has the ability of adsorption of phosphorus. But the feature of the water purification system with plants and Kanumatsuchi as bed filter materials is still unknown. In this study, an experiment of water purification using two series of ditches filled with Kanumatsuchi has been carried out. Forage crops (Sorghum; Sorghum vulgare and Sesbania; Sesbania cannabina) were planted in one ditch, and flowers and herbs (Garden Petunia ; Petunia × hybrida, French Marigold; Tagetes patula, Basil; Ocimum basilicum and etc.) were planted in another ditch. Nitrogen and Phosphorus average loading rate to the ditches during experiment (6 months) was 0.99-1.06 and 0.22-0.24 g · m-2 · d-1. The average nitrogen removal rate of the forage crop ditch and the flowers & herbs ditch was 0.52 and 0.14 g · m-2 · d-1. The phosphorus average removal rate of the forage crop ditch and the flowers & herbs ditch was 0.22 and 0.24 g · m-2 · d-1. But the phosphorus concentration of effluent from the flowers & herbs ditch increased near the end of the experiment.
The biomass production of forage crops was larger than that of flowers & herbs. Analysis of nitrogen and phosphorus concentration of plants shows that forage crops uptake larger nitrogen and phosphorus than flowers and herbs. Results of the experiment suggest that a combined effect of the uptake by plants and the adsorption by Kanumatsuchi leads high phosphorus removal in this system. And we can conclude that the increasing of phosphorus absorption by plants results in sustaining of the absorption ability of Kanumatsuchi.View full abstractDownload PDF (1355K) -
XIAN-NING LI, TAKAO INAISHI, HIROYUKI NAKAZATO, MUNEHIRO NOMURA, OSAMU ...2005 Volume 41 Issue 2 Pages 61-71
Published: 2005
Released on J-STAGE: July 07, 2006
JOURNAL FREE ACCESSIn this study, the effect of water surface loading and harvesting on purification function by hydroponic biofilter method was studied, and the pollution control efficiency with respect to water quality and ecosystem by this method was also studied using mesocosm experiment.
In plants growing channels, the average T-N removal rate was obtained as 0.98 g · m-2 · d-1 and that of T-P was 0.10 g · m-2 · d-1 except in the winter. It was found that the maximum removal rate of T-N was obtained when the water surface loading was set at 5 m3 · m-2 · d-1, and those of T-P and Chl.a were obtained while loading set at 4 m3 · m-2 · d-1. Thus, it is necessary to set the optimal water surface loading according to the purpose because the removal ratio is observed lower at high loading than at low loading. Furthermore, it turns out that harvest has no influence on outflow by performing suitable harvest. The concentrations of T-N and T-P in mesocosm 1 of plants growing system were found lower than in mesocosm 2 of the control system. The concentrations of Chl.a were found 41.1 μ g · l-1 in mesocosm 1 and 77.4 μ g · l-1 in mesocosm 2 at the 25th day, and the densities of Microcystis sp. were 1.1 × 103 N · ml-1 in mesocosm 1 and 29 × 103 N · ml-1 in mesocosm 2 at the 10th day. This system is thought to be very important to maintain the ecosystem because the nutrient can be removed and algae density be controlled, furthermore Microcystis sp. be removed as control the species of algae.View full abstractDownload PDF (1691K) -
KOTARO AOYAMA, NAOYUKI MIYATA, KEISUKE IWAHORI2005 Volume 41 Issue 2 Pages 73-81
Published: 2005
Released on J-STAGE: July 07, 2006
JOURNAL FREE ACCESSLandfill leachates contain many kinds of hazardous chemicals, the toxicity of which is evaluated using various bioassays. Alkaline single cell gel electrophoresis (comet assay), a mutagenicity test, enables sensitive detection of DNA damage in eukaryotic cells induced by genotoxic agents. We previously evaluated DNA damage and repair by a comet assay using unicellular green alga Euglena gracilis and demonstrated the usefulness of normalized tail moment as a DNA damage evaluation index. Therefore, we performed an evaluation of DNA damage induced by landfill leachates by the comet assay using E. gracilis and compared the results to the umu test. In the comet assay, sample A and B displayed DNA damage in 40-fold and 10-fold concentration, respectively. Because highly concentrated CODMn (Chemical Oxygen Demand) and T-N (Total Nitrogen) were detected in the samples, the chemicals that caused the DNA damage may be the not-readily biodegradable or biorefractory organics and nitrogen compounds. The DNA damage in sample A was closely related to the indirect mutagens. In sample B, it was influenced by the direct mutagens. These results showed that landfill leachates contain various mutagens difficult to predict from chemical analysis. Moreover, the umu test detected no mutagenicity in any samples. Since the comet assay was more sensitive than the umu test, comet assay is the method of choice for detecting mutagenicity in landfill leachates.View full abstractDownload PDF (2898K) -
HIROSHI OGAWA, HIDEYUKI KITAMURA, NAOYUKI MIYATA, KEISUKE IWAHORI2005 Volume 41 Issue 2 Pages 83-92
Published: 2005
Released on J-STAGE: July 07, 2006
JOURNAL FREE ACCESSExperimental investigations on the biodegradation of endocrine disrupting chemicals (EDC) in the aerobic and anaerobic sludges were carried out. EDC concentrations were adjusted to the same levels of the influent derived from the actual sewage treatment plants or the domestic wastewater treatment facilities (Gappei-shori Johkasous). After 90% of 17 β-estradiol (E2) was adsorbed by the activated sludges, it declined to the value under the detection limit at 72 hours. Higher the MLSS concentration of sludges were, more adsorption of bisphenol A (BPA) and nonylphenol (NP) were obtained, and their removal efficiencies varied in the range of 72-99% and 59-90%, respectively. Biodegradation rates of E2, BPA and NP conformed to the first-order reaction model. However, the biodegradation of E2, BPA and NP was not caused by the anaerobic sludges. It was confirmed that mono-(2-ethylhexyl) phthalate, mono-butyl phthalate and phthalic acid were formed as the intermediates in the aerobic biodegradation of di-(2-ethylhexyl) phthalate and di-n-butyl phthalate.View full abstractDownload PDF (1892K) -
HARUKO KUNIEDA, XIAN-NING LI, KAZUHIRO YAMADA, NOBUO CHIBA, MUNEHIRO N ...2005 Volume 41 Issue 2 Pages 93-101
Published: 2005
Released on J-STAGE: July 07, 2006
JOURNAL FREE ACCESSThe objective of this study is to evaluate the constructed reed bed treatment system to remove nutrients from secondary effluent. The packed media, the removal characteristics and the optimum water surface loading were discussed.
The results indicated that the growing of the reeds was better and the nutrients removal rates were higher in constructed reed bed treatment systems packed with sand or gravel than in the system packed with net material. The maximum removal rates of DTN and DTP in the system packed with sand were 5.5 g · m-2 · day-1 and 0.5 g · m-2 · day-1 respectively when the water surface loading rate was set at a maximum of 0.38 m3 · m-2 · day-1, and those in the system packed with gravel were 6.6 g · m-2 · day-1 and 1.1 g · m-2 · day-1 respectively when the water surface loading rate was set at 0.60 m3 · m-2 · day-1. It is clear that the low nutrients concentration of effluent can be obtained in the system packed with sand and the volume of treated effluent can be ensured in the system packed with gravel, revealing importance to choose the packed media according to treatment objectives.View full abstractDownload PDF (1308K) -
PHAM KHAC LIEU, RITSUKO HATOZAKI, HAYATO HOMAN, KENJI FURUKAWA2005 Volume 41 Issue 2 Pages 103-112
Published: 2005
Released on J-STAGE: July 07, 2006
JOURNAL FREE ACCESSIn the process named SNAP (Single-stage Nitrogen removal using Anammox and Partial Nitritation), influent ammonium was removed as nitrogen gas by the combination of two autotrophic steps, partial nitritation and anammox, in one unit process. The reactors were packed with acryl-resin fiber biomass carriers and gently aerated. The synthetic influent, simulating secondary-treated landfill leachate, contained ammonium concentrations of 240 mg-N/l and 500 mg-N/l for reactors named SN-2 and SN-3, respectively. Data from 300 days of SNAP operation using reactor SN-2 showed ammonium conversions of 47.7∼88.1% with nitrogen removal rates of 0.31∼0.45 kg-N/m3/d under various operational conditions. The best performance with loading rate of 0.6 kg-N/m3/d was obtained at 35°C, pH 7.8, and aeration rate of 0.10 vvm (volume per volume per minute), with 88.1% ammonium conversion and 78.5% nitrogen removal. The results of about 100 days of operation for reactor SN-3 confirmed the treatment capability of SNAP process, with about 80% nitrogen removal with loading rates up to 1.0 kg-N/m3/d. Some important characteristics of the SNAP process are discussed.View full abstractDownload PDF (3940K)
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