Influence of Temperature on Inoculation and Startup of a Groundwater-Denitrifying Submerged Filter

Abstract

The effect of temperature on biofilm formation and nitrate removal capacity of a submerged filter inoculated with activated sludge for the denitrification of polluted groundwater was studied. Temperatures studied were 5, 10, 20, and 30°C. Results showed that colonization of the system after recirculation of the inoculum takes place independently of temperature, but temperatures below 5 or 10°C slowed down biofilm formation. After inoculation, the acclimation phase of the biofilm required more time at low temperatures. In steady-state conditions, nitrogen removal capacity was conditioned by temperature: although nitrogen removal capacity was not significantly affected at 10–30°C in steady-state conditions, at 5°C the nitrogen removal rate was approximately 70% of that observed at 20°C. Nitrite accumulation was also related to temperature.