KÄVEREDUKTION GENOM NITRIFIKATION I BIOLOGISKA BÄDDAR OCH EFTERDENITRIFIKATION – FÖRSÖK VID BJUVS AVLOPPSRENINGSVERK / Nitrification in Trickling Filters followed by Denitrification – Pilot Tests the Municipal Wastewaier Treatment
Trickling filters are normally considered to be difficult to use in systems designed for nitrogen removal. If the load of organic substances is low or can be reduced to a sufficiently low level, a trickling filter can however be used for nitrification and denitrification can be obtained in a succeeding denitrification process. This might be the most economical system when a treatment plant including trickling filters is rebuilt for nitrogen removal, especially if excisting volumes are efficiently used. The municipal wastewater treatment plant in Bjuv has two stonepacked trickling filters. The use of precipitation makes the load of BOD low. A more than one year study shows that the nitrification effiency normally is high enough to leave an effluent ammonium concentration of 10 mg N/l or less. Results from a simultaneously performed pilot study show that the nitrate produced in the trickling filters can be reduced to a low concemration using a reasonable dosage of external carbon. The concentration of nitrogen as ammonium and nitrate after the trickling filters aiid the pilot denitrification plant could be kept at a level of about 10 mg N/l. Thus, with an efficient removal of suspended solids, this system will result effluent concentration of nitrogen in the range of 10-15 mg N/l.