Abstract

Chemical or organic compounds released during the waste composting could be harmful to the environment. The purpose of this work is to investigate the stability indices of organic matter after the lixiviation runs on composting platforms. The results showed that the organic matter became resistant to biodegradation after 2 months of wastes composting, that the nitrates content decreased, while the phosphorus one increased. The organic load predominantly hydrophilic substances (HPI*) decreased significantly (p <0.05) during composting polymerizing into humic acids (AH characteristics of the leachate, such as a pH <8, a (BOD₅/COD) ratio >0.1 and a (AH*+HPO*) content <50% pointed to the class of an intermediate leachate. However, the values of COD*) and hydrophobic substances (HPO*). The increase in (AH*+HPO*) fractions is correlated with Specific UV Absorbance (SUVA) value which rose from 4 to 25 L.gC^-1.cm^-1. Some <4000 mgO₂.L^-1, of SUVA >20 L.gC^-1.cm^-1 and an HPI* concentration <30% suggested a stabilized leachate. Thus, during the 4 months, the resultant compost although mature was not stable. The leachate characterization has permitted to understand both its quality and the state of the waste where it originates from, making it possible to prevent any chemicals leakage into the environment.

Key words: Waste, composting, organic matter, hydrophobic fractionation.