The Effect Of Organic Matter On The Denitrification Characteristics Of Anammox Oxidation (ANAMMOX) Reaction

Anaerobic ammonium oxidation?ANAMMOX? was a lithoautotrophic biological conversion process that anaerobic ammonium oxidation bacteria?AAOB? could use NO2--N as electron acceptor to oxidize NH₄⁺-N to N2 under anaerobic conditions. The characteristics of anaerobic ammonium oxidation in the presence of organic compounds were studied by batch experiments.Batch experiments were conducted to investigate organic matter?OM? on anaerobic ammonia oxidation?ANAMMOX?. Firstly, the effects of organic matter?OMs? concentration on ANAMMOX reation were explored through the starch addition experiment. Results showed that the inhibitory threshold concentration of starch?NH₄⁺-N removal efficiency was lower than 80%? was about 640 mg/L. The removal of NH₄⁺-N and NO2--N, NH₄⁺-N and COD were synchronous in reactors. ?NO2--N/?NH₄⁺-N increased and ?NO3--N/?NH₄⁺-N decreased with the increasing of starch concentration and the change of ?NO2--N/?NH₄⁺-N was slower than ?NO3--N/?NH₄⁺-N. The metabolic way of AAOB might have changed after the addition of OM which would reduce the theoretical ?NO2--N/?NH₄⁺-N value. The reaction of ANAMMOX, denitrification and anaerobic fermentation were simultaneously occurred in reaction reactor, which made ? p H and ? ORP decreased when starch concentration was higher than 320 mg/L. PH and NH₄⁺-N concentration had good correlation, and the p H-NH₄⁺-N fitting lines were approached to the same with different concentrations OMs or COD.Secondly, the performance of ANAMMOX in presence of COD was evaluated under the condition of various OMs. The threshold inhibition concentration of sodium succinate, sodium potassium tartrate, peptone, lactose on ANAMMOX reaction was 192.5 mg/L?210 mg/L?225 mg/L?325 mg/L respectively, which represented the consequence of inhibition too. With OMs concentration lower than 80 mg/L, the ANAMMOX reaction wasn't inhibited, but the promotion of total nitrogen consumption was detected due to the NO3--N removal. The removed NH₄⁺-N fell, NO2--N enhanced and produced NO3--N decreased in effluent with OMs concentration higher than 160 mg/L, which resulted in the change of stoichiometric ratio. At the same OMs addition concentration, the sequence of the R1 and R2 were all sodium succinate, sodium potassium tartrate, peptone, lactose. The activity of ANAMMOX fell due to the decrease of the specific ANAMMOX activity?SAA? and increase of the specific denitrification activity?SDA?. The specific ANAMMOX activity was higher than that in the control group when lactose, peptone, sodium potassium tartrate concentration were lower than 80 mg/L, which meant the promotion of ANAMMOX reaction. The activity of ANAMMOX fell due to the decrease of the specific ANAMMOX activity and increase of the specific denitrification activity. From the perspective of thermodynamics, it was notable that denitrification and ANAMMOX reactions were simultaneously occurred in reactors and the occurrence of denitrification was prior to the ANAMMOX reaction.