Impact of salinity coupling FNA on N2O reduction during denitrification via nitrite

In order to study the influencing factors during the conversion process of Nitrous oxide (N2O), batch tests were conducted with the sludge treating landfill leachate for a long time. In this study, the inhibitory effect of free nitrous acid (FNA) concentration on N2O reduction and accumulation at different salinity were investigated. The results show that: there are some differences of the minimum inhibition concentration of FNA on N2O reduction under different salinity, which gradually reduce as the increasing of salinity; the accumulation of N2O increases with the increase of salinity, implying that N2O production is bound up with the salinity; the accumulation of N2O at 10, 20, 30, 35 and 40 g/L salt account for 19.1%, 33.2%, 39.0%, 53.5% and 56% of influent total nitrogen, respectively; the acclimatization of sludge can increase the ability to resist FNA inhibition, weaken the inhibition of FNA on N2O reduction and thus reduce N2O emission.