Journal of Japan Society on Water Environment
Online ISSN : 1881-3690
Print ISSN : 0916-8958
ISSN-L : 0916-8958
Volume 37, Issue 5
Displaying 1-5 of 5 articles from this issue
Original Paper
  • Yaozong JIANG, Tomotaka YANAGITA, Tomoyo MITANI
    Article type: Original Paper
    2014 Volume 37 Issue 5 Pages 169-176
    Published: 2014
    Released on J-STAGE: September 10, 2014
    JOURNAL FREE ACCESS
    The effects of various anions on the removal of arsenite by a newly developed iron hydroxide synthesized from ferrous sulfate, sodium hypochlorite, and sodium hydroxide were examined. The adsorption isotherm of arsenite was of the Freundlich type, that of phosphorus was of the Langmuir type, and that of fluoride was of the Henry type. The maximum amounts of anion adsorbed after 24 hours of contact were 0.50 mmol As•g-1 for arsenite, 0.45 mmol PO4-P•g-1 for phosphorus, and 0.85 mmol F•g-1 for fluoride. Judging from the distribution coefficient of coexisting individual anions and various coexisting anions, arsenite adsorption was inhibited by PO43-; however, only a slight inhibition was observed in the presence of HCO3- and F-. No inhibition was observed in the presence of NO3-, NO2-, Cl-, or SO42-. The amount of arsenite adsorbed by the newly developed iron hydroxide in the column filtration experiments was reduced to 66% in the presence of PO43-. Only small reductions was observed in the presence of F-.
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  • Takuya OKUBO, Yuichi SATO, Yoshihiro AZUMA
    Article type: Original Paper
    2014 Volume 37 Issue 5 Pages 177-187
    Published: 2014
    Released on J-STAGE: September 10, 2014
    JOURNAL FREE ACCESS
    We investigated the inflow and outflow of nitrogen and phosphorus in two paddy field areas (0.84 ha and 1.0 ha) where irrigation water has relatively high concentrations of nitrogen (app. 2-5 mg•L-1) and phosphorus (app. 0.2-0.7 mg•L-1) in Moriyama City in Shiga Prefecture, Japan. The results are as follows: 1) The net loads of nitrogen of the two paddies were -56 and 11 g•ha-1•d-1. One paddy showed nitrogen removal during the irrigation period. 2) the net loads of phosphorus were 90 and 104 g•ha-1•d-1. These values were higher than those reported by other researchers in other researches performed in Shiga Prefecture. The high load of phosphorus may be due to the accumulation of bioavailable phosphorus in paddy soil. 3) The net loads of dissolved organic carbon were 213 and 326 g•ha-1•d-1. These values were the same as previously reported values. 4) From the results of this study, we found that the reuse of wastewater with high nutrient concentrations is effective for the removal of nitrogen, but not for the removal of phosphorus or organic carbon. The removal of phosphorus may be suppressed by the accumulation of phosphorus in paddy soil. The removal of organic carbon is difficult because of the production of organic carbon by phytoplankton in surface water of paddies.
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  • Mari ASAMI, Koji KOSAKA, Dai SIMAZAKI, Kanako TAKEI
    Article type: Original Paper
    2014 Volume 37 Issue 5 Pages 189-195
    Published: 2014
    Released on J-STAGE: September 10, 2014
    JOURNAL FREE ACCESS
    Chlorate and perchlorate are oxidized substances of chloride, and they exist in the form of anions in water and toxic contaminants that should be controlled, especially in drinking water. To control and minimize the formation of perchlorate in the water purification process, the formation of chlorate and perchlorate in chlorine generation process was studied in electrolysis of salt water. Six electrodes with different properties (main components: A: RuO2-TiO2; B: RuO2-IrO2-TiO2; C: IrO2-SnO2; D: IrO2-Pt; E: Pt; and F: PbO2) were tested. Electric voltage differed among electrodes and the generation of chlorate and perchlorate depended on their electric voltage. When electric current is constant, those electrodes of higher terminal voltage generally showed lower production of chlorine and higher generation of chlorate and perchlorate. It is noted the electrodes, E: Pt and F: PbO2 are prominent in the generation of chlorate and perchlorate. Therefore, the generation of chlorate and perchlorate should be controlled with the consideration of electrode material, the especially in on-site generation of hypochlorite, industrial electrolysis, water purification devices, and hypochlorite generation devices that involve electrolysis.
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  • Ryoya WATANABE, Toshiki SUGO, Shinichiro WAKAHARA, Yu-You LI
    Article type: Original Paper
    2014 Volume 37 Issue 5 Pages 197-204
    Published: 2014
    Released on J-STAGE: September 10, 2014
    JOURNAL FREE ACCESS
    Anaerobic membrane bioreactors (AnMBRs) in which anaerobic digestion and membrane separation are combined have recently been attracting attention, because they can recover methane and reduce sludge production in wastewater treatment. In this study, a laboratory-scale AnMBR for treating synthetic sewage was continuously operated with lowered the temperature gradually from 25 to 15°C to investigate the effect of temperature on the treatment performance, mass balance, and membrane performance. At hydraulic retention time (HRT) of 12 hours, the chemical organic demand (COD) concentration of the effluent and COD removal at 25, 20, and 15°C were 18, 17, and 40 mg•L-1 and 96, 96, and 92% respectively. Concerning the mass balance, no difference in the conversion ratios of methane including dissolved methane was seen, but the recovery ratio of methane gas at 15°C was about 10% lower than those at 25 and 20°C. Regarding the membrane performance, the rate of trans-membrane pressure was increased by lowering the temperature, and the reason increasing the membrane pressure was thought to be the blocking of pores by organic matter from microbial metabolic products. The AnMBR was expected to successfully produce clean water, recover energy efficiently, and reduce the amount of sludge produced compared with traditional sewage treatment.
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Note
  • Takayuki NAKAMURA
    Article type: Note
    2014 Volume 37 Issue 5 Pages 205-210
    Published: 2014
    Released on J-STAGE: September 10, 2014
    JOURNAL FREE ACCESS
    The nitrogen load in the basin of Shinano River was calculated by a pollutant load method using administrative data from 1970 to 2005 and compared with the concentrations of total nitrogen in the river. Livestock, farmland and forest primarily generated nitrogen load in the upper basin, whereas livestock, farmland and sewage were the main nitrogen sources in the middle basin. Industrial waste occupied half the total amount of nitrogen load in the lower basin. The total amount of nitrogen load generated in the basin decreased by 20% from 1985 to 2005, and it was 35,000 tonN•yr-1 in 2005. The decrease in nitrogen load from livestock and farmland, and the construction of sewage systems with improved treatment efficiency caused a decrease in the nitrogen load in the basin. This decrease in the nitrogen load was reflected in the decrease in total nitrogen concentration in the middle and lower basins of the river from 1990 onward. In order to further improve water quality, new measures may be required for industrial waste treatment in the middle and lower basins of the river.
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