Biological treatment is widely preferred by many landfill owners to remove
the bulk of the pollutants in leachate. Specific problems due to toxicity a
nd nutrient deficiencies are however frequently reported. This study invest
igates the possibility of pre-treating leachate to decrease its toxicity an
d increase its biodegradability, using ozonation. Lab-scale and pilot testi
ng has shown that nitrification toxicity was minimised by ozone pre-treatme
nt. A decrease of the COD/BOD-ratio from 16 to 6 was achieved, making the p
re-treated leachate co-treatable in municipal sewage treatment. The operati
onal cost for the pretreatment was estimated at 1.34 Euro/kg COD.