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Absorption of nitrogen from a liquid by pine bark

Content Partner: Lincoln University. This study investigated the potential of Pinus radiata (pine) bark to absorb organic and ammoniacal-nitrogen, from an aqueous solution and from a dairy slurry, in the laboratory and in a field treatment of dairy slurry. Preliminary experiments indicated that the...

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Bibliographic Details
Main Author: Musgrave, Simon J
Format: Dissertation
Language:English
Online Access:Request full text
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Summary:Content Partner: Lincoln University. This study investigated the potential of Pinus radiata (pine) bark to absorb organic and ammoniacal-nitrogen, from an aqueous solution and from a dairy slurry, in the laboratory and in a field treatment of dairy slurry. Preliminary experiments indicated that the initial nitrogen concentration of the solution had a significant effect on the rate of nitrogen absorption. The range of physical and chemical characteristics in pine bark and dairy slurry was found to give some variation in the quantity of nitrogen absorbed over time. Some unexplained results were attributed to differences in pine bark characteristics between samples, and to undefined analytical errors which may have included microbial activity in stored samples. Phenyl mercuric acetate was found to have no significant effect on the analysis of ammoniacal nitrogen using the Flow Injection Analyser, and was hence used for the inhibition of microbial activity in subsequent samples during storage. Empirical models were developed for predicting the amount of ammoniacal and organic nitrogen absorbed, from an aqueous solution of ammonium sulphate and from a dairy slurry, by pine bark over time as a function of pH and initial nitrogen concentration in the laboratory and in the field. The proportion of ammoniacal nitrogen absorbed over 24 hours, at pH 6 to 8, ranged from 35% from an initial concentration of 50 ppm-N, to 15% from an initial concentration of 200 ppm-N. After three weeks, approximately 75% of the ammoniacal-nitrogen was absorbed from a solution of 100 ppm-N ammonium sulphate at pH 6. About 50% of the total nitrogen in a dairy slurry was absorbed by pine bark over two weeks. The model developed for predicting the absorption of ammoniacal-nitrogen was tested and found not appropriate for describing the absorption of total nitrogen from a dairy slurry. A new empirical model was developed for the dairy slurry. Initial pH of the solution was shown to have an effect on the mechanism of nitrogen absorption. At pH 6 there was no difference in the absorption of nitrogen by sterilised and non-sterilised bark, whereas at pH 8 there was a significant reduction in absorption of nitrogen by sterilised bark. This suggested that the absorption of nitrogen at pH 6 was largely chemical, whereas at pH 8 there was significant microbially mediated absorption. Infra-red spectroscopy was used to deduce some possible functional groups involved in the absorption of various forms