Single aerobic denitrifying bacterial strains have been studied extensively; considerably less attention has been paid to mix-cultured aerobic denitrifying bacteria (Mix-CADB). Herein, three novel Mix-CADB consortia were isolated from sediment using ultrasonic processor pretreatment. The nitrate and total organic carbon (TOC) removal efficiencies of the Mix-CADB were greater than 99% and 97% under aerobic conditions, respectively. Moreover, the optimal conditions for aerobic denitrification of the Mix-CADB were evaluated by a response surface methodology model. The nirS gene sequences indicated that the dominant phyla were Firmicutes and Proteobacteria. The relative abundance of mixed taxa changed over the culture time. Network analysis demonstrated that the total nitrogen (TN) and TOC removal performance were driven by the co-occurrence and interaction of Bacillus subtilis, Pseudomonas stutzeri, Rhodococcus sp., etc. Mix-CADB inoculation can remove 86% TN and 93% COD of real wastewater. The identified Mix-CADB isolated by ultrasonic pretreatment can be used for nitrogenous wastewater treatment.