Identification of a highly efficient aerobic denitrier and denitrification optimization using response surface method

Abstract:

[Objective] The eutrophication of water body is one of pressing water environmental problems in China today. It is mainly caused by over-discharge of wastewater with high nitrogen. Aerobic denitrification bacteria are promising on simultaneous nitrification and denitrification process, presenting high advantages than conventional denitrification process. A high efficient aerobic denitrification strain was isolated and its nitrogen removal efficiency was optimized. [Methods] The aerobic denitrification strain was obtained in a SBR reactor, and response surface method was used to improve key factors influencing denitrification and total nitrogen removal efficiency. [Results] High efficiency aerobic denitrification strain of Pseudomonas T13 was selected from a SBR reactor. Based on response surface method, the highest nitrate removal rate was 95%, total nitrogen removal rate of 90% within 18 h, which were obtained by optimizing key factors of ratio of carbon and nitrogen, dissolved oxygen, pH, and temperature. The suitable temperature ranged from 25 °C to 30 °C. The optimal pH is neutral and the suitable COD/NO3?-N was over 4:1. The DO was around 2.5 mg/L. Pseudomonas T13 can use nitrate and nitrite as electron acceptor for nitrate respiration with 90% removal rate. [Conclusion] An aerobic strain with high efficient denitrification was identified as Pseudomonas T13 from a long-term running SBR reactor. Over 30% nitrate reductase were detected out of all denitrification enzyme genes from the strain. It is presenting a great potential on nitrate removal (>90%) to strengthen nitrogen removal process in wastewater treatment.