Acetonitrile biodegradation and total nitrogen removal in a single-stage airlift bioreactor using bacterial endophytes

This study focused on the biodegradation of acetonitrile (ACN) and subsequent nitrification using a mesophilic microbial consortium isolated from Phragmites australis and Zantedeschia aethiopica plants which were in a nitrile-contaminated habitat. The organisms were identified using 16S rDNA sequencing and were determined to be Bacillus sp., Pseudomonas sp., and Enterobacter sp. organisms. These organisms were used as a consortium in the biodegradation of ACN. The physicochemical conditions including temperature, pH, and ACN concentration were optimized using response surface methodology (RSM). Based on this method, an optimal biodegradation efficiency of 99% was achieved at an optimized temperature of 34.99 °C, pH of 7:03, and an ACN concentration of up to 127.23 mg/L. These optimized parameters were used in the continuous operation over a period of 122 days with increased ACN concentrations of 150–500 mg/L where the biodegradation efficiency exceeded 99% which were accompanied by the production of acetic acid, acetamide, and nitrogenous compounds. Acetic acid and acetamide were completely utilized while total nitrogen (TN) was 1.2 mg/L on the last day of the study.