Measure Cod, Improve Processes

The leachate from a landfill in North Rhine-Westphalia, Germany, used to be transported by road tanker to the nearest sewage treatment plant. Since 1998 a biological treatment plant has been in operation, which has now handled more than 650,000 m3 of leachate, at a maximum rate of 350 m3/day. Four activated carbon filters, each filled with 20 m3, handle the residual COD load. The wastewater is fed into them in a sequence that depends on how long the activated carbon has been in use. A freshly regenerated filter discharges treated wastewater with a COD concentration of about 50 mg/l; this is well below the limit value of 400 mg/l and is therefore a major cost factor. This can be avoided with the help of the COD cuvette test.