Leachate composition and environmental risks from waste wood dumps.

High concentrations of phenols can be found in leachate and stormwater of woodprocessing, storage and disposal sites. Although timber is a natural product, mishandlingof wood waste may harm the environment.As a common practice, wood residues were dumped in landfills in Estonia. As a nationalstrategy, it has been decided to close all of the dumping sites. In many cases, woodresidues have been used for capping of municipal dump sites. It has been suspected, thatenvironmentally hazardous phenolic compounds may be leaching out from such landfills.Pathways for generation of natural phenolic compounds, as well as the ecologic impact ofthem have not been studied in Estonia.In this paper, leachate composition from dumpsites of waste wood is studied and thehazards of phenols to the environment are discussed. In the wood waste, phenol can befound mainly in tannins, resin and lignin. Phenols in tannins are water-soluble, butphenols in resins are more soluble in organic solvents, such as ether, what is producedduring decomposition of lignin. Chipping and storage of wood in the water-richenvironment speeds up the leaching of phenols.The leachate from wood waste dumps is quickly purified by natural processes in the soil.It is assumed that in most cases the natural phenols do not migrate far from the dump siteor storage area. The problem may arise in case where such waste is stored near to thewater body or the leach-water is repeatedly re-circulated into the deposit of waste wood.