| 摘要 |
Methods for extracting molecules of fulvic acid from a humus material such as oxidized lignite are disclosed. The humus material is mixed with water to solubilize at least some of the fulvic acid molecules. A first filtration apparatus (which may be an ultrafiltration apparatus) may be used to separate at least some of the solubilized fulvic acid molecules from the humin and at least some of the humic acid molecules. A second filtration apparatus (which may be an ultrafiltration apparatus or a nanfiltration apparatus) may be used to then separate the fulvic acid molecules from most of the water and any remaining impurities. A digestion step may also be carried out where microorganisms are brought into contact with the mixture in the presence of oxygen in order to oxidize any unoxidized organic compounds in the humus material. Iron and aluminum may be precipitated and removed by the addition of a phosphate to improve the purity of the end-product.
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