Liquid fertilizer products from anaerobic digestion of food waste: Mass, nutrient and energy balance of four digestate liquid treatment systems

Elina Tampio, Sanna Marttinen, Jukka Rintala

    Research output: Contribution to journalArticleScientificpeer-review

    79 Citations (Scopus)

    Abstract

    This study compared four different digestate liquid treatment systems of a theoretical anaerobic digestion plant in order to facilitate the utilization of municipal food waste nutrients in agriculture. The mass, nutrient and energy balances of a theoretical plant digesting 60 kt/y of food waste were used to evaluate the feasibility of the treatments to concentrate nutrients into liquid fertilizer products. The studied technologies for digestate liquid treatment were ammonia stripping, ammonia stripping combined with reverse osmosis (RO), evaporation combined with RO, and stripping combined with both evaporation and RO. As a result, processing of digestate into concentrated fertilizer products consumed less than 10% of the produced energy from food wastes and was also sufficient for the heat-demanding digestate liquid treatments, evaporation and stripping. The digestate liquid treatment systems were considered as nitrogen and potassium concentration methods which were able to concentrate up to 67% of the feedstock nitrogen into transportable fertilizer products with low mass. Of the studied digestate systems evaporation combined with RO was evaluated as the most efficient nutrient recovery technology for the production of transportable fertilizer products due to the high concentration of nutrients and nutrient availability as well as low product mass and energy consumption. Overall, the selection of the treatment technology is dependent on the location of the anaerobic digestion plant relative to the agricultural land and the type of fertilizer products needed.

    Original languageEnglish
    Pages (from-to)22–32
    Number of pages11
    JournalJournal of Cleaner Production
    Volume125
    DOIs
    Publication statusPublished - Jul 2016
    Publication typeA1 Journal article-refereed

    Keywords

    • Anaerobic digestion
    • Digestate liquid treatment
    • Evaporation
    • Food waste
    • Reverse osmosis
    • Stripping

    Publication forum classification

    • Publication forum level 2

    ASJC Scopus subject areas

    • Industrial and Manufacturing Engineering
    • Renewable Energy, Sustainability and the Environment
    • Environmental Science(all)
    • Strategy and Management

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