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Journal of Environmental Quality Abstract - Waste Management

Ammonia Stripping of Biologically Treated Liquid Manure


This article in JEQ

  1. Vol. 41 No. 1, p. 273-280
    Received: Aug 8, 2011

    * Corresponding author(s): anni.alitalo@mtt.fi
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  1. Anni Alitalo *a,
  2. Aleksis Kyröb and
  3. Erkki Aurac
  1. a MTT Agrifood Research Finland, Plant Production Research, Soil and Plant Nutrition, 31600 Jokioinen, Finland
    b Dep. of Agricultural Sciences, Univ. of Helsinki, Finland
    c Biotaito, Killintie 14, 31300 Tammela, Finland. Assigned to Associate Editor Sean McGinn


A prerequisite for efficient ammonia removal in air stripping is that the pH of the liquid to be stripped is sufficiently high. Swine manure pH is usually around 7. At pH 7 (at 20°C), only 0.4% of ammonium is in ammonia form, and it is necessary to raise the pH of swine slurry to achieve efficient ammonia removal. Because manure has a very high buffering capacity, large amounts of chemicals are needed to change the slurry pH. The present study showed that efficient air stripping of manure can be achieved with a small amount of chemicals and without strong bases like NaOH. Slurry was subjected to aerobic biological treatment to raise pH before stripping. This facilitated 8 to 32% ammonia removal without chemical treatment. The slurry was further subjected to repeated cycles of stripping with MgO and Ca(OH)2 additions after the first and second strippings, respectively, to raise slurry pH in between the stripping cycles. After three consecutive stripping cycles, 59 to 86% of the original ammonium had been removed. It was shown that the reduction in buffer capacity of the slurry was due to ammonia and carbonate removal during the stripping cycles.

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