Nitrogen Removal of Water and Sediment in Grass Carp Aquaculture Ponds by Mixed Nitrifying and Denitrifying Bacteria and Its Effects on Bacterial Community

Nitrification and denitrification are important for nitrogen (N) cycling in fish ponds culture, but the effects of nitrifying denitrifying bacteria concentrations on pond water sediments remain largely unknown. Here, we used 0, 0.15, 0.30, 0.60 mg/L different mixed to repair substrate through an enclosure experiment lasting 15 days. The results showed that purification effect was most obvious from day 4 7. optimal relative concentration bacteria; NH4+-N (ammonia nitrogen) decreased by 75.83%, NO2−-N (nitrite) 93.09%, NO3−-N (nitrate) 38.02%, TN (total 45.16% this group water. In one cycle, C/N (carbon/nitrogen) ratio both body bottom sediment significantly increased, increased more than sediment. Water 76.00%, 51.96% group. Amplicon sequencing change bacterium diversity consistent with quality index. Dominant had a relatively high percentage, significant differences dominant percentage across bacterial addition groups, while not without among groups. species were, respectively, Nitrosomonas, Nitrosovibrio, Nitrosospira, Aeromonas, were Thauera, Azoarcus, Magnetospirillum, Azospira, Idiomarina. correlation analyses aerobic nitrification facultative anaerobic sediments. Research shows exogenous can effectively reduce load At 0.6 mg/L, obviously, which best purification.