Quantification of functional bacteria in one-step completely nitrogen removal process influenced by dissolved oxygen

Abstract:

Abstract: [Objective] To study the influence of dissolved oxygen (DO) on bacterial population in a one-step autotrophic nitrogen removal process and to improve the system operation. [Methods] Ammonia oxidizing bacteria (AOB), nitrite oxidizing bacteria (NOB) and anaerobic ammonium oxidizing bacteria (ANAMMOX) were amplified directly from the one-step completely autotrophic nitrogen removal reactor by using the specific PCR primers. The purified PCR products were cloned into T-vector and identified as the target fragments of AOB, NOB and ANAMMOX by sequencing. Recombined plasmid was used as standard molecule sample in Real-time PCR for quantification. [Results] High DO was beneficial to AOB and NOB. The population of both AOB and NOB were higher in activated sludge than biofilm samples. High DO had the directly influence on ANAMMOX population whereas low DO had the inhibitory effect of ANAMMOX activity if the system was lack of NO3- and NO2-. [Conclusion] DO of 2.0 (aeration)/ 0.4(non-aeration) mg/L was the best operation concentration. Meanwhile, ANAMMOX population reached the peak in this condition and AOB ，NOB as well as ANAMMOX composes of a steady co-metabolisms system.