Combined ozone-activated sludge treatment of landfill leachate.

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