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Y. Mishima
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LONG-TERM CHANGE OF WATER QUALITY IN THE RESERVOIR OF THE ISAHAYA BAY RECLAMATION PROJECT Y. Mitsugi; N. Vongthanasunthorn; Y. Mishima; K. Koga; H. Araki; P. Ittisukananth
Lowland Technology International Vol 15 No 1, June (2013)
Publisher : International Association of Lowland Technology

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In 1997, the Isahaya Reservoir was constructed at the innermost part of Isahaya Bay, Japan to prevent natural disasters and to develop water resources for large-scale farm lands. The main purposes of this study were to analyze the mechanisms underlying the water quality changes observed and to collect significant information for water quality management at the reservoir. Observed water quality parameters on chlorophyll-a, suspended solids, total nitrogen, dissolved inorganic nitrogen, total phosporus, dissolved inorganic phosphorus and chloride ion were analyzed by using a water quality model. It was found taht the results obtained from the developed water quality model agreed with the observed data. After calibrating the observed data, a simple sensitivity analysis was conducted to demonstrate the mechanisms of the water quality changes. The major water quality problems were suspended solids that had been resuspended by strong wind and eutrophication due to the enrichment of nutrients. The major mechanisms of water quality changes in the Isahaya reservoir were a coagulation and flocculation by brackish water and the transformation process of phosphorus. The coagulation affected the settling velocity of suspended solids and dissolved phosphorus. It was also revealed that the resolution process of dissolved phosphorus from suspended solids was controlled by the salinity.
PHOSPHORUS RECOVERY FROM WASTEWATER BY HYDROTALCITE AND ZEOLITE Y. Mishima; H. Araki
Lowland Technology International Vol 12 No 2, Dec (2010)
Publisher : International Association of Lowland Technology

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A system using hydrotalcite and zeolite is developed for the recovery of phosphorus from wastewater having low phospate concetrations. As HT and Ze is independently used, redundant ion species are produced in a desorbing solution. As HT and Ze are used in combination, however, the opposite redundant ion species can be used to desorb PO43- and NH4+, respectively. Simply alkaline NaCl solution is used to desorb/regenerate HT/Ze. Moreover, desorbed substances can be recovered as magnesium ammonium phosphate (MAP) by the addition of Mg. In this paper, the desorption of PO43- and NH4+ from HT and Ze into a single desorbing solution and phosphorus recovery from the desorbing solutions as MAP are experimentally investigated. It is verified that the single desorbing solution can simultaneously desorb HT and Ze. Whereas 95% of phosphate was recovered from the desorbing soluition in which PO43- and NH4+ were accumulated, most of the recovered phosphorus was not MAP but Mg3(PO4)2 (MP). However, when the initial concentrations of PO43- and NH4+ in the desorbing solution increased, MAP was procuded rather easily and more than 90% of P was recovered. Further investigation into application for the practical plant is necessary.
Evaluation on applicability of a new hybrid adsorbent to waste pollution control in Lowland by complex leachate from waste landfill site S. Juengjarernnirathorn; M. Ohno; Y. Mishima; H. Suhara; H. Araki
Lowland Technology International Vol 17 No 4, March (2016)
Publisher : International Association of Lowland Technology

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There is growing social concern about water environment issue including eutrophication, water pollution in the water bodies, and hazardous contaminants in lowland groundwater. Following extensive research into wastewater characteristics, the understanding of the potential effects of wastewater on health and the environment has become more comprehensive. Soil and water in lowland areas are especially easily contaminated by heavy metals, toxicant chemicals from waste disposal landfill sites and factories, and natural disasters. These events have prompted the search for suitable solutions. Several treatment methods have been developed to deal with health and environmental concerns associated with the findings of recent research. In this paper, a new adsorbent is characterized and the adsorption of harmful substances dissolved in leachate has been studied. Nano size Layered Double Hydrotalcite (NLDH) and Zeolite (Ze) have been combined to synthesize a more powerful adsorbent, which successfully adsorb both anion and cation at the same time; cations and anions were simultaneously recovered at the same time over 3 hours, under an initial pH of 6 at 20°C using 0.5 gram and 1 gram per liter of the hybrid adsorbent (HB). Other adsorbents were used to validate the efficiency of a new hybrid adsorbent (HB).
Identification of Urban Sprawl – A Case Study of Vijayawada City, Andhra Pradesh, India P. Kesava Rao; Y. Mishima; S. Srinivasulu; N. Bhaskara Rao
Lowland Technology International Vol 18 No 1, June (2016)
Publisher : International Association of Lowland Technology

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At this moment, India is among the countries of low level of urbanization. As a result, most urban settlements are characterized by shortfalls in stock housing and water supply, urban encroachments in fringe area, inadequate sewerage, traffic congestion, pollution, poverty and social unrest making urban governance a difficult task to maintain healthy urban environment. High rate of urban population growth is a cause of concern among India’s urban and town planners for efficient urban planning. Therefore, there is an urgent need to adopt modern technology of Remote Sensing and Geographic Information Systems to collect, to analyze, to model and to link the overall planning process to make planning process more effective and meaningful. Vijayawada is the second largest city in the state of Andhra Pradesh and in the close vicinity of newly constructing Capital, Amaravati of the newly formed state, located on banks of river Krishna is taken as a case study for observation of sprawl using a change detection method. It is found that Shannon’s entropy analysis method effective qualitative measure to identify the sprawl of Vijayawada city.
Co-Authors H. Araki H. Suhara K. Koga M. Ohno N. Bhaskara Rao N. Vongthanasunthorn P. Ittisukananth P. Kesava Rao S. Juengjarernnirathorn S. Srinivasulu Y. Mitsugi