Experiences and new developments in biological pretreatment and physical post-treatment of landfill leachate

The leachate treatment plant of the landfill in Mechernich including biological pretreatment, reverse osmosis and evaporation and drying of the concentrate has been in operation since the beginning of 1994. Originally the plant was designed for a capacity of 130 m³/d. In the future, an average leachate amount of ca. 280 m³/d and even considerably higher montly peaks must be assumed. The necessary enlargement of the biological pretreatment will be realized by a second biological contactor plant. Corresponding to the operation of the existing plant a large amount of the ammonium can be eliminated under aerobic conditions by deammonification so no enlargement of the denitrification stage is needed. by simply replacing the reverse osmosis membranes by nanofiltration membranes, an operational capacity of ca. 280 m³/d may easily be achieved at the existing physical post-treatment stage. With the aid of this enlargement conception, the relatively high operational costs at present will be reduced considerably.