Short-term effect of ammonia concentration and salinity on activity of ammonia oxidizing bacteria

摘要

A continuously aerated SHARON (single reactor high activity ammonia removal over nitrite)nsystem has been operated to achieve partial nitritation. Two sets of batch experiments werencarried out to study the effect of ammonia concentration and salinity on the activity of ammoniaoxidizingnbacteria (AOB). Activity of AOB raised as free ammonia concentration was increasednreaching its maximum value at 4.5mgNH3-N l21. The half saturation constant for free ammonianwas determined (KNH3n?0.32mgNH3-N l21). Activity decreased at TAN (total ammonium–nitrogen)nconcentration over 2,000mgNH4-N l21. No free ammonia inhibition was detected. The effect ofnsalinity was studied by adding different concentrations of different salts to the biomass. Nonsignificant differences were observed between the experiments carried out with a salt containingnor not containing NH4. These results support that AOB are inhibited by salinity, not by freenammonia. A mathematical expression to represent this inhibition is proposed. To comparensubstrate affinity and salinity inhibitory effect on different AOB populations, similar experimentsnwere carried out with biomass from a biological nutrient removal pilot plant. The AOB activitynreached its maximum value at 0.008mgNH3-N l21 and decreased at TAN concentration overn400mgNH4-N l21. These differences can be explained by the different AOB predominating species:nNitrosomonas europaea and N. eutropha in the SHARON biomass and Nitrosomonas oligotrophanin the pilot plant.