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Volume 34 (1998)
- Issue 4 Pages 231-
- Issue 3 Pages 159-
- Issue 2 Pages 1-
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Volume 34, Issue 4
Displaying 1-6 of 6 articles from this issue
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KAZUHIRO TAKAMIZAWA, ITSUO TANAKA, MASAHIRO HATSU, AKIKO SHIROTA, NOBO ...1998 Volume 34 Issue 4 Pages 231-240
Published: December 15, 1998
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSMajor problems for hydroponics are higher operational cost and pollution due to discharge of waste nutrient solution. Besides, water culture has disadvantage for plant pathogenic distribution in the system due to shortage of buffer action in comparison with soil cultivation. To solve these problems, recycling use of nutrient solution by ultrafiltration was studied. Plants used were Lettuce (Lactuca sativa L.) and sporangia of Pythium aphanidermatum, a pathogen. Growth of lettuce was inhibited by inoculation of 2.01×104 sporangia/l or more of sporangia but they recovered viability at 22nd day after inoculation. Inoculation of 1.00×106 sporangia/l represented lethal effect on lettuce. Whether inoculation period of P. aphanidermatum to water culture was at the lst week or month, lettuce deceased. Sporangia of P. aphanidermatum were perfectly removed by untrafiltration. P. aphanidermatum produced pathogenic substance of below 20, 000 MW, which caused lettuce root rod decease. This substance seems unstable under heating condition. Experimental results suggest that ultrafiltration is effective to remove pathogenic microoganisms from nutrient solution but if pathogenic microorganisms produce some harmful substances, another/combined treatment of nutrient solution should be necessary.View full abstractDownload PDF (5825K) -
MASAHIDE ICHIKAWA, KAZUHIRO TOYOOKA, KEISUKE IWAHORI1998 Volume 34 Issue 4 Pages 241-252
Published: December 15, 1998
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSIn sewage treatment, the nitrification-denitrification process with nitrified liquor recirculation (NDPR) is mainly adopted for nitrogen removal. Bench-scale experiments on NDPR were carried out. Based on the results obtained, kinetic models of NDPR were developed and their parameters were determined. It was shown that computer simulation using these models is effective in order to investigate the optimal method of operation.View full abstractDownload PDF (986K) -
GUOJI DING, KAIQIN XU, OSAMU NISHIMURA, YUHEI INAMORI, RYUICHI SUDO1998 Volume 34 Issue 4 Pages 253-265
Published: December 15, 1998
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSAn ultrasonication method was developed to study the effect of nematodes on the chlorination of bacteria and to investigate numbers of bacteria associated with nematodes isolated from a distribution system. The organisms selected for this study were Nematoda Rhabditis sp. and Bacteria Escherichia coli C600. Thé results of experiment showed that ultrasonication of nematodes was effective for determining the numbers of bacteria in the body of the nematode and the most suitable condition of ultrasonication was 40 w for 60 sec. It was clear that resistance of associated bacteria to free chlorine was 1, 000 times higher than that of unassociated bacteria and there was a positive correlation between the survive ratio of associated bacteria and nematodes, which suggested that surviving nematodes can serve as carriers to protect bacteria lived in their body from chlorination and decreasing the survive ratio of nematodes will be effective for decreasing that of bacteria. The results of investigation on numbers of bacteria associated with nematodes isolated from an actual distribution system showed that a lot of viable bacteria were detected from surviving nematodes treated by ultrasonication, which confirmed the above experiment results and suggested that viable bacteria associated with nematodes might leak into the distribution system.View full abstractDownload PDF (3731K) -
MOTOYUKI MIZUOCHI, KAZUAKI SATO, YUHEI INAMORI, MASATOSHI MATSUMURA1998 Volume 34 Issue 4 Pages 267-277
Published: December 15, 1998
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSN2O is one of the important greenhouse gas, and it has been pointed out that its contribution to global warming will increase in the future. In the past, higher level concentration of N2O emission was reported for some sewage sludge incinerators than at other fixed emission sources including a solid waste incinerator. Therefore, we investigated the practical factors of N2O emission from the sewage sludge incineration originated from the difference of incinerator type and coagulant type used for dehydration. As a result, it was cleared that emitted amount of N2O is strongly depended on the incineration temperature and the coagulant type used for dehydration process. Amounts of N2O emitted from sewage sludge incineration in FY 1995 in Japan was estimated at 4030t on a nitrogen basis and thought to more increase to the future.View full abstractDownload PDF (1089K) -
SACHIKO ABE, RYUICHI SUDO1998 Volume 34 Issue 4 Pages 279-289
Published: December 15, 1998
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSEffects of disinfectants to periphytic algae in glass tubes (7 mm in diameter, 50 cm in length) were examined using 2 types of media; ozonated medium and chlorinated medium. The periphytic algae used in this study were collected from natural fresh waters of Zaru River and were left for their attachments for 2 months in a vessel in which glass tubes were set. Incubation experiments using these tubes and 2 types of media were carried out for 30 days.
The time course experiments showed that chlorophyl a (chl.α) concentration of glass tube wall both in control medium and ozonated medium increased on the 9th day. The average chl.α concentration of three tube wals from the 12th to the 30th day were 10.2μg/cm2 (control), 11.6μg/cm 2 (ozonated) and 7.4μg/cm2 (chlorinated) respectively. No marked increase in the concentrations of chl.α in effluent of chlorinated medium were found. The average chl.α concentration in eflluent of the control and ozonated medium were almost the same (2.1 and 1.8μg/l) in the first 13 days, and that of ozonated medium on the 17th day was about 3.5 times higher than the control. The maximum concentration of chl.α was 17.0μg/l (ozonated) on the 26th day.
Among the algal species identified (42 in total), Scenedesmus spp., Homoeothrix janthina and Chroococcus spp. dominated. Different algal communities were formed on the walls of glass tube in chlorinated medium. Numerical abundance of Chroococcus spp. was more than 50% on chlorinated glass tube walls from the 6th day. Nitzschia palea in ozonated effluent incerased in the 15th day, accounting for 74.2%in the 25th day.
The present results showed that chlorination to the medium made a negative effect on the algal flora and standing crop on the glass wall, resulting in the marked change of species composition using cluster analysis and by ozonation algal biomass and species diversity increased.View full abstractDownload PDF (1251K) -
TAKAHIRO SEKIKAWA, KEISUKE IWAHORI, NAOYUKI MIYATA, KOICHIRO YAMAKAWA1998 Volume 34 Issue 4 Pages 291-298
Published: December 15, 1998
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSIn continuous starch wastewater treatment with Aspergillus niger pellets, stability of pellets and efficiencies of starch decomposition and total organic carbon (TOC) removal were considerably affected on both pH in the reactor and hydraulic retention time (HRT) . The form of pellets was maintained without bulking or collapsing under more than 20 days'operation in case that pH and HRT were set to 3.0 and 8 hrs, respectively. In addition, microbial contamina tion was effectively controlled and high efficiency of starch decomposition (80%) was obtained.However, negligible amount of TOC was removed. Since those residual components, containing glucose mainly, were thought to be degraded readily by activated microorganisms, experimental investigation of multi-stage treatment with the fungal and activated sludge processes was carried out. Consequently, starch and TOC from the starch wastewater were removed at 80% and it was suggested that multi-stage treatment process was effective for high strength starch wastewater.View full abstractDownload PDF (710K)
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