Facile biodegradation of N, N-dimethylformamide, N, N-dimethylacetamide and N-methyl-2-pyrrolidone by source-derived Bacillus strain APS1 for water reclamation and reuse

Abstract

Large volume of hazardous aprotic polar solvents such as N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc) and N-methyl-2-pyrrolidone (NMP) are released to the environment through wastewater stream, generated from industries which include polymer membrane industries. Biodegradation of these solvents by bacterial strains is a convenient process but inherent toxicity of these solvents at high concentrations often limits the efficiency of the process. Current work reports a facile biodegradation of DMF, DMAc and NMP at high concentrations employing free cells of Bacillus cereus APS1 strain, isolated from DMF rich wastewater. The newly isolated strain is capable of degrading these solvents utilizing them as sole carbon and nitrogen source. The free cells of APS1 are highly tolerant to DMF concentration as high as 35000 mg/L. Biodegradation of solvents is monitored by refractive index, HPLC and 1H NMR spectroscopy. Effect of pH of the wastewater, cell growth and concentration of the solvents is evaluated. Almost complete biodegradation of DMF(30000 mg/L) present in wastewater occurs within 48 h, while 192 h is required at DMF concentration of 35000 mg/L. Time required for complete biodegradation of DMAc and NMP at concentration of 10000 mg/L is 72 h and 96 h respectively. In batch mode, the biodegradation efficacy of APS1 remains steady for multiple cycles. Ultrafiltration membranes prepared using reclaimed water and fresh water as nonsolvents show similar morphology and performance. This work shows that a strain isolated from DMF wastewater is advantageous for the biodegradation of DMF or similar kind of amide containing solvents.