Effect of temperature and salinity on the wastewater treatment performance of aerobic submerged fixed bed biofilm reactors

The influence of temperature (5-35 degrees C) and salinity (up to 20g/lNaCl) on the wastewater purification process in completely mixed and aerated submerged fixed bed biofilm reactors (SFBBRS) was studied. C- and N-conversion in SFBBRs designed according to the DWA (German Association for Water , Wastewater and Waste) rules for carbon removal was investigated for several months on synthetic wastewater. The DOC degradation rate was even at, according to the DWA, high DOC/BOD loading rates not much affected by temperatures between 5-35 degrees C and salt contents up to 20 g/L NaCl. At these high DOC loadings an appreciable ammonium conversion could also be observed. The ammonium conversion proved to be sensitive to temperature and salinity. At 5 degrees C the ammonium removal rate decreased by a factor of five compared to 25-35 degrees C. Under many operation conditions investigated more than 50% of the converted ammonium was transformed into gaseous nitrogen. The addition of 20 g/L NaCl caused a strong inhibition of the ammonium removal rate over the whole temperature range investigated.