1996 Fiscal Year Final Research Report Summary
Study on phosphate and Ammonium Removal using Magnesium Ammonium Phosphate Crystallization
| Project/Area Number |
07650929
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
反応・分離工学
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| Research Institution | Waseda University |
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Principal Investigator |
HIRASAWA Izumi Waseda Univ., School of Sci.Eng.Prof., 理工学部, 教授 (10228778)
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| Project Period (FY) |
1995 – 1996
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| Keywords | Environmental Crystall / Wastewater Treatment / Magnesium Ammonium Phosphate / Ind.Cry. / Design / プロセス開発 |
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| Research Abstract |
Development of Ammonium and Phosphate ions removal process has been needed for removing them from wastewater exhausted in the process of sludge treatment, considering the concept of sludge treatment base in the metropolitan urban cite. In this research, basic investigation was done on the relation between crystallization characteristics and removability. Batch experiments were done to verify the crystallization characteristics of MAP (characteristics of water quality and operational conditions to crystallize MAP selectively), and selective crystallization conditions (temperature, pH,Mg/P molar ratio and NH4/P molar ratio) was obtained. Based on the results above, batch reactive crystallization experiments were performed, to investigate relation between the process of Magnesium and Phosphate removal and crystallization of MAP,and to clarify operational pH and Mg/P molar ratio for obtaining optimum removal efficiency and consider MAP crystallization based on nucleation and crystal growth phenomena, by measuring the dynamic change of crystal size and its shape through SEM.And also Alcohol addition method was investigated, to make clear the effect of alcohol on the solid-liquid equilibrium. Addition of alcohol lowered the solubility product.
Process of MAP crystallization was considered to consist of reaction of ions, diffusion and surface integration stpes, and it was recognized that integration step determined the rate, when desirable product size was needed. Consequently design method on the material balance and crystallization rate was proposed, considering relation between crystallization rate and design method of the crystallizer.
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