Filtration ability of hollow fiber membrane for production of magnesium ammonium phosphate crystals by reaction crystallization

H. Watamura, H. Marukawa, Izumi Hirasawa

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    Relationship between magnesium ammonium phosphate (MAP) crystal properties and the filtration ability of hollow fiber membrane (HFM) were investigated. Phosphorus recovery process by crystallization has a problem that it produces a large amount of fine crystals. So improvement of the crystallization process by combining with filtration was discussed. MAP crystals were obtained by batch reaction crystallization and the filtration characteristics were investigated. The filtration was evaluated by the specific filtration resistance (αc) on HFM. Filtered slurry was prepared with each suspension density and crystal size distribution. The solution was filtered at constant pressure of 0. 02 MPa and the filtration time on each filtrated volume was recorded. As a result, αc decreases exponentially with suspension density increasing from 0. 25 g/L to 0. 5 g/L and αc decreases moderately with suspension density increasing from 0. 5 g/L to 1. 5 g/L. αc of large crystals decreases exponentially at less suspension density than αc of small crystals does. Also, αc increases as the ratio of the fractured crystals increases.

    Original languageEnglish
    Pages (from-to)55-59
    Number of pages5
    JournalFrontiers of Chemical Science and Engineering
    Issue number1
    Publication statusPublished - 2013 Mar



    • crystallization
    • MAP
    • membrane separation

    ASJC Scopus subject areas

    • Chemical Engineering(all)

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