Journal of Water and Environment Technology
Online ISSN : 1348-2165
ISSN-L : 1348-2165
Volume 12 , Issue 3
Showing 1-10 articles out of 10 articles from the selected issue
Original Papers
  • Masaki SAGEHASHI, Michihiro AKIBA
    Type: Original Paper
    2014 Volume 12 Issue 3 Pages 211-220
    Published: 2014
    Released: June 10, 2014
    JOURNALS FREE ACCESS
    To obtain basic information about the emergency water supply for elderly people, the amount of water use and preparedness for the cutoff of water supply at elderly facilities in Tokyo were investigated. Questionnaires about water use in October 2012 and preparedness for the cutoff of the water supply were sent to 1,251 of these facilities located in Tokyo, and 214 answers were obtained. Based on the data from facilities not involving outpatient users, the daily water use per person admitted was calculated. Median values were 411 [L/day/person-admitted], and 431 [L/day/person-admitted] for the Designated Facility Covered by Public Aid Providing Long-Term Care to the Elderly (n = 13), and the Welfare Facilities for the Elderly (i.e., Nursing Home, Low-Cost Home, and Fee-Based Home for the Elderlies) (n = 22), respectively. Note that these values include the water used by workers and visitors at the facilities. Meanwhile, the preparedness was summarized based on all of the valid answers. As a result, the ratio of water receiving tank possession and the stock drinking water were high. However, there are still room for improvement of the introductions of the emergency water supply agreement and the emergency drill considering the cutoff of the water supply.
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  • He YANG, Hiroyasu SATOH, Takashi MINO
    Type: Original Paper
    2014 Volume 12 Issue 3 Pages 221-230
    Published: 2014
    Released: June 10, 2014
    JOURNALS FREE ACCESS
    Viruses hosted by microorganisms in activated sludge are of particular interest for researchers because they may affect the performance of wastewater treatment. In this study, the authors investigated at which condition of wastewater treatment viruses, especially double stranded DNA (dsDNA) viruses, were released from activated sludge to the supernatant. To determine the concentrations of viruses, supernatant samples were filtered through membrane filter, viral capsid was digested by treatment with proteinase K, and the dsDNA concentration was determined. The authors confirmed that most of dsDNA in the filtered supernatant cannot be digested by DNase I, and thus treatment with DNase I was omitted. The behavior of dsDNA viruses was monitored in twelve selected cycles from three laboratory-scale sequencing batch activated sludge reactors with sequencing anaerobic and aerobic conditions. The concentrations of dsDNA viruses increased at different timings of treatment: during anaerobic phase, aerobic phase, and settling phase. The rate of increase was varied, sometimes rapid while other times gradual. Decrease of dsDNA concentration was also observed. The behavior of dsDNA viruses in activated sludge during wastewater treatment was found to be very diverse and complex.
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  • Charles K. CHERUIYOT, Victor S. MUHANDIKI
    Type: Original Paper
    2014 Volume 12 Issue 3 Pages 231-244
    Published: 2014
    Released: June 10, 2014
    JOURNALS FREE ACCESS
    Lake Victoria in East Africa is the second largest freshwater lake in the world by surface area. Pollution of the lake is an increasing concern because it compromises the ecosystem integrity of the lake. Past studies estimated the runoff load using borrowed nutrient export coefficients from other regions. Borrowed export coefficients were not necessarily modified to match the attributes of the local area. This study estimated the nutrient export coefficients for three land uses using river runoff data measured at river mouths of watersheds on the Kenyan side of Lake Victoria. Measured nutrients at river mouths were distributed back to the watersheds using a model equation. Factors that influence the export of nutrients were also assessed and incorporated in the model. Land use areas and rainfall-runoff coefficient values were used as main variables to explain runoff load. Two sets of data were used, one to set up the model and the other to validate the model. The range of export coefficients were estimated at 95% confidence interval. Land use and rainfall-runoff coefficient factors are adequate to estimate the export coefficients. Agricultural activities are the dominant land use and cover 87% of the catchment and are the major source of runoff load.
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  • Yugo TAKABE, Kohei YAMASE, Kohsuke WATANABE, Yasunari KUSUDA, Tadao MI ...
    Type: Original Paper
    2014 Volume 12 Issue 3 Pages 245-257
    Published: 2014
    Released: June 10, 2014
    JOURNALS FREE ACCESS
    Effects of a crush process on methane conversion efficiency in thermophilic anaerobic digestion with coffee grounds were evaluated. The crush process was performed with a blender (10,000 rpm). In batch experiments, solubilization rates for crushed coffee grounds (representative particle size: 320 μm) were greater than 8.10% at 55°C for 24 h, and the rate for uncrushed grounds (> 1,000 μm) was 5.00% under the same conditions. In a batch experiment, methane conversion efficiency for crushed grounds (45.4%) was higher than that for uncrushed grounds (27.7%) in the thermophilic anaerobic digestion process (120 h). The contribution of acetic acid to the conversion efficiency was suggested. Continuous experiments (solubilization and thermophilic anaerobic digestion) were conducted with loading rates of 5 and 6.5 kg COD/m3/day. The experiments also showed average efficiencies for the crushed samples (41.1% and 39.3%, 5 and 6.5 kg COD/m3/day, respectively) were higher than uncrushed samples (33.4% and 32.4%). Moreover, the crushing process improved the total solid decomposition. Based on these results, it was found that anaerobic digestion using a crush process is effective, especially for coffee grounds with a representative particle size of 320 μm.
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  • Ginno Lizano ANDRES, Nobuyuki YANO, Yuuki SHIYOUKEI, Yoshinobu YOSHIHA ...
    Type: Original Paper
    2014 Volume 12 Issue 3 Pages 259-274
    Published: 2014
    Released: June 10, 2014
    JOURNALS FREE ACCESS
    Capacitive deionization technique having higher efficiency and lower operation cost in comparison with the reverse osmosis technique for regeneration of rinse water used for dechlorination of incineration ashes is investigated. Activated charcoal-based electrodes were developed and characterized for their capacity to remove the chlorine ions dissolved in rinse water for incineration ashes. The mass ratio of rinse water to incineration ashes was also investigated to realize the most efficient removal of chloride from rinse water and minimize the regeneration load of the rinse water. The electrochemical properties of the developed electrode were characterized using a three-electrode cyclic voltammetry system, which showed that chemically modified carbon electrodes demonstrated an increase in capacitance. An asymmetrical distribution of capacities of both electrodes was found to be ideal wherein no electrochemical reactions took place at the electrode surface. The electrode capacities were defined based on the difference between the rest potential of the electrodes and the oxidation-reduction potential of the solution. Furthermore, the ion removal capacity of the electrode was evaluated using NaCl solution with a conductivity of 11 mS/cm. The electrode with a thickness ratio of 2.5:1 (anode:cathode) exhibited high ion removal capacity up to 0.034 mol/m2.
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  • Dai SIMAZAKI, Satoshi HIRAMATSU, Jun FUJIWARA, Michihiro AKIBA, Shoich ...
    Type: Original Paper
    2014 Volume 12 Issue 3 Pages 275-283
    Published: 2014
    Released: June 10, 2014
    JOURNALS FREE ACCESS
    Monitoring priority of a wide variety of pharmaceuticals was determined in regard to the probability of occurrence in water sources and drinking water in Japan. One hundred and twenty six pharmaceuticals currently in Japanese market, i.e. prescription drugs, over-the-counter (OTC) drugs, veterinary drugs and antibiotics for aquaculture were chosen by literature review and database search. Six evaluation criteria were selected for the determination of monitoring priority of the pharmaceuticals based on occurrence in water sources and drinking water, as well as possible impacts on human health, i.e. annual production, human urinary excretion, octanol-water partition coefficient (log Kow), biodegradation, removal capability by conventional water treatments, and minimum daily therapeutic dose (or acceptable daily intake (ADI) if available). Methodology of the prioritization adopted in this study were found to be appropriate because all of the six pharmaceuticals (i.e., amantadine, carbamazepine, epinastine, ibuprofen, iopamidol and oseltamivir acid) detected in finished drinking water in Japan appeared among the top 25 on the monitoring priority list. Further field investigations on the high-priority pharmaceuticals should be considered to elucidate the overall picture of residual pharmaceuticals in water environment and drinking water, and their potential implications for human health.
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  • Taichi NAGAI, Osamu MIKI, Chikako OKUMURA
    Type: Original Paper
    2014 Volume 12 Issue 3 Pages 285-294
    Published: 2014
    Released: June 10, 2014
    JOURNALS FREE ACCESS
    Sargassaceae species are important macroalgae for maintaining marine environments. Furthermore, biofuel based on Sargassaceae species has become studied recently. However, Sargassaceae species have declined rapidly in coastal areas around Japan, which are called "isoyake", a term meaning barren areas. The development of effective measures to restore these "isoyake" and the construction of Sargassaceae beds are strongly needed. A lack of iron in coastal areas limits the growth of macroalgae, and may cause "isoyake". However, the effects of the iron concentration on the growth of macroalgae, such as species of Sargassaceae, are poorly studied. In this research, the effects of chelated iron on the growth of Sargassaceae species during the germling and immature stages were examined. The addition of Fe-EDTA promoted the growth of four Sargassaceae species during the germling stages. During the germling stage of Sargassum ringgoldianum, the maximum specific growth rate and the saturation constant were estimated to be 0.17 day-1 and 4.3 μg/L, respectively. Additionally, the periodic addition of Fe-EDTA promoted the stable growth of Sargassum horneri during the immature stage.
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  • Takehide HAMA, Daichi IWASAKI, Tomohisa NAGAI, Fuminori IGARASHI, Yasu ...
    Type: Original Paper
    2014 Volume 12 Issue 3 Pages 295-305
    Published: 2014
    Released: June 10, 2014
    JOURNALS FREE ACCESS
    Nutrient effluent load from paddy fields has a large impact on water quality in the downstream areas. The sediment in drainage canals can act as nutrient source by releasing nutrients to the overlying drainage water. In this study, we evaluated the effect of bioturbation caused by tubificid worms, which live commonly in paddy fields, on nutrient release from the sediment in drainage canals. We investigated a low-lying paddy field district adjacent to Lake Biwa. We also sampled drainage water and the sediment in the study site and conducted incubation experiment of the sediment for four weeks. In the sediment incubation experiment, we added different densities of tubificid worms to the sediment. The effect of tubificid worms on nitrogen release was much larger than that on phosphorus. Nitrogen was mainly released as ammonium nitrogen by the excretion of tubificid worms.
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  • Hironori KAWAMURA, Senichi EBISE
    Type: Original Paper
    2014 Volume 12 Issue 3 Pages 307-320
    Published: 2014
    Released: June 10, 2014
    JOURNALS FREE ACCESS
    Yodo River is an important source of tap water for 12 million people in Kinki area. The statistical characteristics in pesticide concentrations for R. Yodo and three major tributaries were made clear by high-frequency observations. The relationships between total pesticide loads during observation periods and the areas of river watershed and its paddy field became almost linear on a log-log graph. The mass balances of pesticide loads between the three major tributaries and R. Yodo during the downstream reach were calculated during the observation period. As the sums of total pesticide loads of the three major tributaries accorded to those of R. Yodo at Yodo River New Bridge during observation period in 2011, the decreases of pesticide loads by degradation during the downstream reach were considered to be very small. The frequency of routine observation was evaluated in order to precisely estimate the total runoff pesticide loads mainly during an irrigation period. The estimated total loads for three pesticides detected widely in long term during the monthly observation distributed widely in the range of 10 - 472% of those by every three days of observations. The weights of the three pesticides in DI value (detecting index value) were calculated as 27 - 88% of all pesticide species in the big rivers during the irrigation period.
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  • Kumiko OGUMA, Jatuwat SANGSANONT, Hiroyuki KATAYAMA
    Type: Original Paper
    2014 Volume 12 Issue 3 Pages 321-331
    Published: 2014
    Released: June 10, 2014
    JOURNALS FREE ACCESS
    Chlorination and UV disinfection of untreated wastewater were compared, assuming that the activated sludge process is not functioning after disasters. Untreated wastewater samples were collected from a wastewater treatment plant that was severely damaged by the Great East Japan Earthquake in 2011, and the samples were subjected to chlorination or UV disinfection with or without preceding coagulation. Disinfection efficiency was evaluated based on the inactivation profiles of indigenous microorganisms: total coliforms, Escherichia coli, and somatic phages. Chlorination without coagulation was not effective for either microorganism regardless of the chlorine injection rate (5 mg/L or 10 mg/L) and contact time (up to 30 min), but the inactivation efficiency was improved when coagulation preceded chlorination. Meanwhile, UV disinfection was effective even without coagulation, and the UV inactivation rate constant was not significantly different between samples with and without coagulation for either microorganism (ANOVA, p > 0.10) under the experimental conditions adopted in this study. In conclusion, the direct chlorination of untreated wastewater, as conducted after the Great East Japan Earthquake, is not very effective and we recommend coagulation before chlorination if secondary wastewater treatment is unavailable after a disaster. Alternatively, UV irradiation would be an option for disinfecting untreated wastewater after disasters.
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