3. Results
3.1. Humic-like substance characterization
The general properties of humic-like substances are
shown in Table 1. The HLS end-product is a black liquid
presenting a high organic carbon content (9.36 g C l1).
The product is constituted by humic acids (56.4%) and a
high level of fulvic acid (43.6%) confirmed by a high
E465/E665 ratio characteristic of low molecular weight content
(Chen et al., 1977) (Table 1). As demonstrated by
Richard (2002), HLS properties and behaviour are similar
to natural humic substance properties extracted from soil
or compost. Elemental analysis and infrared spectroscopy
indicate similarities in the composition and structure of
humic molecules. Gel filtration data and spectrophotometric
analysis confirmed the presence of high and low molecular
weight particles (Richard, 2002).