Anaerobic ammonium oxidation and denitrification are the main processes of biological nitrogen removal from sediments. Carbon sources are the key factors regulating anaerobic ammonium oxidation and denitrification. In this study, the static carbon release of lignite and its effect on nitrogen removal from pond sediment were studied. The results show that the carbon release rule of lignite at room temperature accords with the second-order kinetic equation and has the feasibility of being a denitrification carbon source.In the denitrification experiment, it was found that lignite promoted the removal of nitrite nitrogen (N
\rmO_2^ - 
-N) in the overlying water. The removal rate of N
\rmO_2^ - 
-N increased with the increase of lignite concentration. When the mass concentration of lignite was 40 g/L, the removal rate of N
\rmO_2^ - -N was up to 99.61%. At this time, the concentration of nitrate nitrogen (N
\rmO_3^ - 
-N) was also the lowest; at the same time, it was found that the optimum concentration of ammonia nitrogen (N
\rmH_4^ + 
-N) in water was 10 g/L, and the removal rate was 99.39%. Illumina high-throughput sequencing of anaerobic ammonium oxidizing bacteria in the sediment found that the proportion of Fusarium was the largest (39.6%-71.8%), and the dominant genus was Candidatus
Brocadia (13.9%-35.8%),
Desulfovibrio (17.1%-34.8%), the proportion of Candidatus
Scalindua added to the lignite group was higher than that of the unadded group; fluorescence quantitative PCR showed that with the increase of lignite mass concentration, the abundance of denitrifying bacteria in the sediment increased, while the abundance of anaerobic ammonium oxidizing bacteria was lower than that in the zero-brown coal addition group, indicating that the addition of lignite promoted the sediment denitrification. It has a certain inhibitory effect on anaerobic ammonium oxidation. Studies have shown that lignite has the conditions of denitrifying carbon source and can be used for denitrification of pond culture sediments.
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