Despite the many benefits of denitrifying phosphorus removal process, the significant generation of nitrous oxide (N
2O), a potent greenhouse gas, remains a problem for this innovative and promising process. To better understand and more effectively control N
2O generation in denitrifying phosphorus removal process, batch experiments were carried out to investigate the main causes of N
2O generation, based on which the control measures were subsequently proposed. The results showed that N
2O generation accounted for 0.41 % of the total nitrogen removal in denitrifying phosphorus removal process, whereas, in contrast, almost no N
2O was generated in conventional denitrification process. It was further demonstrated that the weak competition of N
2O reductase for electrons and the high nitrite accumulation were the two main causes for N
2O generation, evidenced by N
2O production and reduction rates under different conditions. Accordingly, the reduction of N
2O generation was successfully achieved via two control measures: (1) the use of continuous nitrate addition reducing N
2O generation by around 91.4 % and (2) the use of propionate as the carbon source reducing N
2O generation by around 69.8 %.
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