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Volume 53 (2017)
- Issue 4 Pages 95-
- Issue 3 Pages 81-
- Issue 2 Pages 33-
- Issue 1 Pages 1-
Volume 53, Issue 1
Displaying 1-3 of 3 articles from this issue
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ORIGINALS
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NAOKI TAKAHASHI, ATSUSHI SASAKI, YURIE SHIRAKAWA, MUNEHIRO NOMURA, OSA ...Article type: ORIGINALS
2017 Volume 53 Issue 1 Pages 1-10
Published: 2017
Released on J-STAGE: March 10, 2018
JOURNAL FREE ACCESSIn this research the factors affecting on the removal of coliform group by certified structure type small-scale Johkasou were analyzed. Before chlorination process, the relevance ratios of effluent standard of the number of coliform group in BOD removal type Johkasou and Nitrogen removal type Johkasou were 70.0％ and 88.3％, respectively. The number of coliform group was decreased with the decrease of BOD and SS. Furthermore, the number of coliform group was decreased with the increase of nitrification ratio. After chlorination process, the relevance ratios of effluent standard of the coliform group in BOD removal type Johkasou and Nitrogen removal type Johkasou were 85.0％ and 100.0％, respectively. It was also revealed that some small-scale Johkasou, in which the residual chlorine was detected but free chlorine was not detected, could not achieve the effluent standard of coliform group. This is because that combined chlorine was generated by ammonia remained in treated water and the effect of chlorination was reduced to remove coliform group. From these results, it was concluded that certified structure type small-scale Johkasou, especially Nitrogen removal type Johkasou can removal coliform group effectively and contribute to keep hygienic safety.View full abstractDownload PDF (1699K) -
PHAM THANH HIEN, TOYAMA TADASHI, MORI KAZUHIROArticle type: ORIGINALS
2017 Volume 53 Issue 1 Pages 11-21
Published: 2017
Released on J-STAGE: March 10, 2018
JOURNAL FREE ACCESSThis study investigated the capacity of fill-and-drain constructed wetlands (CWs) for removal of a common antibiotic, tetracycline (TC), and tetracycline resistance genes (tet genes) from municipal wastewater. TC (230 μg/L) containing wastewater was treated in the CWs planted or non-planted with common reed (Phragmites australis). TC was removed significantly in the planted (95.4 % removal) and non-planted (87.2% removal) CWs with a treatment time of 1 day. Both CWs, with longer treatment times, completely removed TC from the wastewater. Adsorption of TC to soil materials might be the major mechanism of removal by the CWs over the short-term. Biodegradation of TC by native microorganisms present in wastewater also contributed in TC removal in CWs. In addition, the planted CWs showed higher TC removal efficiency than did the non-planted ones. The presence of five tet genes (tetC, tetM, tetO, tetQ, and tetW) was monitored in the planted CWs. The influent wastewater had 1.7 × 102-2 × 104 copies/mL of these genes. All the tet genes were completely removed from wastewater by the planted CWs with 1 day treatment. In 28 days sequencing batch experiments using planted and non-planted CWs treating TC containing wastewater (250 μg/L) with treatment time of 2 days, the planted CWs completely and repeatedly removed TC from the wastewater. TC removal by non-planted CWs was 98.9-99.8%, and low concentration of TC persisted in the effluents. The presence of plants provided the effective TC removal in the CWs for a long-term. The planted CWs also maintained about 3 log reduction of tet genes from wastewater during the sequencing batch experiments. These results suggest the potential of planted CWs for use in the removal TC and tet genes from municipal wastewater.View full abstractDownload PDF (1387K)
MATERIALS
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SEIKO FURUTA, SATOSHI ICHISE, DAIYA BAMBA, NAOYUKI KISHIMOTOArticle type: MATERIALS
2017 Volume 53 Issue 1 Pages 23-32
Published: 2017
Released on J-STAGE: March 10, 2018
JOURNAL FREE ACCESSConstructed lakeshores occupy 73％ of the shoreline in the southern basin of Lake Biwa and 38％ in the northern basin. To elucidate the effect of lakeshore construction on the sediment of coastal zone, sediments were sampled from coastal zones near constructed shorelines and near natural shorelines, and were characterized by their particle size distribution, chemical components, and depth distributions of dissolved oxygen （DO） and microalgae cells. A micro profiling system with a micro DO sensor was used for determining DO concentration in the sediment every 0.5－1.0-mm layer. The microalgae cells were counted under an epifluorescence microscope every 1-mm sediment layer. As a result, the sediments near constructed lakeshores were anaerobic with a thin aerobic layer at the sediment surface and contained fine clay silt more than 50％ in volume, whereas the percentages of fine clay silt in the sediments near natural lakeshores were not more than 1.3％. Furthermore, much higher cyanobacteria was detected in the sediments near constructed lakeshores than near natural lakeshores. Thus, it was suggested that the lakeshore construction made the sediments in the coastal zone more anaerobic and contributed to the predomination of cyanobacteria. However, further researches will be required for the better understanding of the effect of lakeshore construction in detail.View full abstractDownload PDF (2641K)
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