Dynamic denitrification of 3,600 m3/h sewage effluent by moving bed biofiltration

STP “De Groote Lucht” in the Netherlands had to be upgraded in order to meet the tightened criterion for total nitrogen (10 mg/l N as yearly average). ASTRASAND moving bed biofiltration, has been introduced for post-denitrification. Pilot plant tests were executed in 1996 and it was found that in order to achieve good filter performance with the specific process conditions, an adequate process control system was required. This filter control ensured removal efficiencies of >95% with influent concentrations up to 30 mg/l NO₃−N and strongly fluctuating influent flows. The full scale denitrification installation with a capacity of 3,600 m₃/h, the first full scale installation of this type used for biological denitrification in Europe, was built in 1998 and started up in 1999. Since the start up, the filter performance is good and the nitrate removal efficiencies are higher than required.