Sustainable nutrients recovery and recycling by optimizing the chemical addition sequence for struvite precipitation from raw swine slurries

Raffaele Taddeo, Kari Kolppo, Raghida Lepistö

    Research output: Contribution to journalArticleScientificpeer-review

    20 Citations (Scopus)

    Abstract

    Livestock farming contributes heavily to nitrogen (N) and phosphorus (P) flows into the environment, a major cause of eutrophication of coastal and freshwater systems. Furthermore, the growing demand for N-P fertilizers is increasing the emission of anthropogenic reactive N into the atmosphere and the depletion of the current P reserves. Therefore, it is essential to minimize the anthropogenic impact on the environment and recycle the wasted N-P for agricultural reuse. This study focused on enhancing struvite (MgNH4PO4*6H2O) precipitation from raw swine slurries in batch and laboratory-scale reactors. Different chemical addition sequences were evaluated, and the best removal efficiency (E%) was obtained when the chemicals were mixed before the precipitation process. Struvite was detected at a pH as low as 6 (E%N-P∼50%), and high E%N-P was found at pH 7–9.5 (80–95%). Furthermore, air stripping was used in place of NaOH to adjust pH, returning the same efficiency as if only alkali had been used. XRD and FE-SEM analysis of the precipitate showed that the recovered struvite was of high purity with orthorhombic crystalline structure and only trace amounts of impurities from matrix organics, co-precipitation products (CaO and amorphous calcium-phosphates), and residuals of added chemicals (MgO).

    Original languageEnglish
    Pages (from-to)52-58
    Number of pages7
    JournalJournal of Environmental Management
    Volume180
    DOIs
    Publication statusPublished - 15 Sept 2016
    Publication typeA1 Journal article-refereed

    Keywords

    • Air stripping
    • Chemical addition
    • Crystallization
    • Manure management
    • Nutrients recycling
    • Struvite

    Publication forum classification

    • Publication forum level 1

    ASJC Scopus subject areas

    • Environmental Engineering
    • Waste Management and Disposal
    • Management, Monitoring, Policy and Law

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