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Volume 39 (2003)
- Issue 4 Pages 157-
- Issue 3 Pages 99-
- Issue 2 Pages 49-
- Issue 1 Pages 1-
Volume 39, Issue 2
Displaying 1-6 of 6 articles from this issue
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HIROSHI NISHIMURA, YUHEI INAMORI, KAI-QIN XU, OSAMU NISHIMURA, RYUICHI ...2003 Volume 39 Issue 2 Pages 49-57
Published: June 15, 2003
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSThe present study is aimed at clearly understanding the relationship among the arrangement of the gravel, the flow rate, and the porosity of the contact media, and the purification capability, which should be effective for a multi-natural type river restoration. Experimental studies were carried out by filling a linear circulation water passage (rated at a grade of 1/830, 30m long, 24cm wide, and 9cm deep, with a Stone type contact media or a net type contact media, whereby the biofilm attachment capability, the filling conditions and the flow rate were varied.
The organic material removal capability differed depending upon the roughness coefficient of the flow passage; the greater the contact provided for the contact media, the higher the purification capability on contact with the biofilm; but it was found that the purification velocity would not improve, even when the amount of attached biofilm per unit contact media was increased to an extremely high level. This means that as the biofilm thickness increases, the porosity decreases so as to cause the decrease of the flow rate through the filled layer. In order to improve nitrification capability, it is necessary to establish the critical flow rate through the filled layer at above 5cm⋅s-1. On the other hand, for the nutrient removal (denitrification), it is important to have a greater amount of biofilm and to keep an anaerobic condition inside the biofilm. Therefore, it is important to make the proper combination of the rapids and pools in the biofilm processes in the rivers and streams.View full abstractDownload PDF (2883K) -
AKIKO KOHAMA, KEIJIRO ENARI, SATOSHI TAMAOKI, MASATOMO NAKAYAMA2003 Volume 39 Issue 2 Pages 59-66
Published: June 15, 2003
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSA recent development to control of eutrophication is the ecological engineering, which involves using plants for water purification. Specifically, aquatic plant, Zizania latifolia, is profitable for nutrient absorption and nutrient elimination from an enclosed system, serving as food for migrating swans. In this study, an experiment in a water culture inhibiting the nitrification and denitrification was conducted to evaluate the ability of nitrogen and phosphorus absorption by Zizania latifolia from May to December in 2001 (32 weeks) . The results were as follows: The wet weight, the amount of water absorption, the amounts of Total Inorganic Nitrogen (TIN) and phosphorus (PO4-P) absorption by Zizania latifolia increased along with growth of Zizania latifolia. The maximum wet weight was taken in October (636g) and the amount of the whole experimental period of water absorption was 74.5kg. The maximum amount of TIN and PO4-P absorption of Zizania latifolia were taken in September, which values were 629mg⋅4weeks-1 and 133mg⋅4weeks-1, respectively. The amounts of the whole experimental period of TIN and PO4-P absorption were 3, 150mg and 631mg, respectively. Finally, the results showed that 5.4mg of TIN and 1.1mg of PO4-P were required for Zizania latifolia to grow 1g of wet weight.View full abstractDownload PDF (990K) -
SHUN'ICHI HONDA, KEISUKE IWAHORI2003 Volume 39 Issue 2 Pages 67-74
Published: June 15, 2003
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSSewage sludge contains plenty of cellulose that is recognized as a biomass resource. All of cellulose containing in sludge are however treated and disposed with sludge without recovering as a resource. This study noted a resourcefu11ness of cellulose contained in sludge, produced the adsorbents by the mixture and the burning of cellulose recovered from sludge and thermosetting resin, and evaluated the abilities of deodorization as an adsorbent. The weights of samples were drastically reduced during the temperatures from 300 to 600°C because of the characteristics of cellulose and phenol resin. The sample burned at 400°C in nitrogen atmosphere was the highest methylene blue and iodine adsorption capacities, and these values were more than the recommendation values of Japan Water Works Association. Moreover the deodorization test suggested that the sample burned at 400°C in nitmgen atmosphere was the highest to adsorb hydrogen sulfide. These results showed that the production of new adsorbent was able to be produced by cellulose recovered from primary sludge and phenol resin and suggested to utilize as a recovery resource.View full abstractDownload PDF (2737K) -
FUMIKO TANAKA, CHUANPING FENG, NORIO SUGIURA, TAKAAKI MAEKAWA2003 Volume 39 Issue 2 Pages 75-84
Published: June 15, 2003
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSThe efficiency of two different types of onsite leachates and simulated leachates, the latter containing endocrine disruptor bisphenol A and refractory humic acid as organic constituents with NaCl and NH4Cl electrolytes, was examined by an electrochemical treatment method. The mechanisms for the removal of organic substances and ammonium ions are discussed based on the analyses of total organic carbon (TOC), nitrogen compounds, and evolved gas. The results suggested that, for the removal of ammonium ions, indirect oxidation by active chlorines is an important process during electrochemical treatment. The degradation of organic substances with chloride-containing leachate is a two-step mechanism consisting of (1) indirect oxidation of active chlorines and (2) cathodic reduction as a result of methane formation, which was proved to be an important process. This two-step mechanism in the electrochemical treatment method was found to be more effective than chlorination or ozonation treatment. For leachate containing a low concentration of chloride ions, direct oxidation by an anodic surface was also important for the degradation of the organic substances during electrochemical treatment. In particular, assimilable organic substances are preferentially degraded by direct oxidation over ammonium ions. In addition, some reactive compounds, such as bisphenol A and p-nitrosodimethylaniline (RNO), might be converted by the oxidizability of chloramines.View full abstractDownload PDF (1368K) -
NAKAO NOMURA, AKIO MINAMI, TOSHIO YAMATOGI, KAZUYUKI OUCHI, TOSHIAKI O ...2003 Volume 39 Issue 2 Pages 85-91
Published: June 15, 2003
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSA density current generator was designed for sediment treatment of Lake Kasumigaura. A fresh water shellfish, Ishigai, introduced as a bio-indicator for sediment quality monitoring, showed high survival and growth rate around 400m away the from density current generator. Simulation of water circulation was conducted using MEC (Marine Environmental Committee) model and results showed that although the flow rate was very slow, water discharged from the density current generator could reach up to several kilometers within 6 hours.View full abstractDownload PDF (2719K) -
NAOSHI FUJIMOTO, NORIO HAYASHI, TAKAHIRO OUCHIYAMA, MOTOYUKI MIZUOCHI, ...2003 Volume 39 Issue 2 Pages 93-97
Published: June 15, 2003
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSProtozoa and metazoan were isolated from biofilms in Thailand to study the effects of temperature on their growth. The study revealed that the protozoa and metazoan that were isolated in Thailand could not grow at low temperatures of 15°C or less. The growth of protozoa and metazoan isolated from biofilms in Thailand tends to be more susceptible to temperature than that of ones isolated in Japan.View full abstractDownload PDF (544K)
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