Leachate composition and environmental risks from waste wood dumps.

Abstract

High concentrations of phenols can be found in leachate and stormwater of wood
processing, storage and disposal sites. Although timber is a natural product, mishandling
of wood waste may harm the environment.
As a common practice, wood residues were dumped in landfills in Estonia. As a national
strategy, it has been decided to close all of the dumping sites. In many cases, wood
residues have been used for capping of municipal dump sites. It has been suspected, that
environmentally hazardous phenolic compounds may be leaching out from such landfills.
Pathways for generation of natural phenolic compounds, as well as the ecologic impact of
them have not been studied in Estonia.
In this paper, leachate composition from dumpsites of waste wood is studied and the
hazards of phenols to the environment are discussed. In the wood waste, phenol can be
found mainly in tannins, resin and lignin. Phenols in tannins are water-soluble, but
phenols in resins are more soluble in organic solvents, such as ether, what is produced
during decomposition of lignin. Chipping and storage of wood in the water-rich
environment 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 site
or storage area. The problem may arise in case where such waste is stored near to the
water body or the leach-water is repeatedly re-circulated into the deposit of waste wood.