Biostimulation and bioaugmentation for the enhanced atrazine degradation in semi-saline medium

Although microorganisms are excellent degraders of herbicide combinations in aqueous solutions, some amendments may be needed to stimulate a more rapid degradation of the herbicide in a restricted period. This paper demonstrates the use of biostimulation and bioaugmentation as robust remediation strategies for the rapid cleanup of atrazine-polluted semi-saline medium. A bacterial strain, Ochrobactrum oryzae (O. oryzae), capable of utilizing atrazine for growth was isolated from semi-e medium. Factors, such as stimulant type, concentration of atrazine, time of inoculation, and pH of medium, were analyzed to determine their effects on the atrazine removal in semi-saline medium. Maximum atrazine removal (46.6%) using O. oryzae was obtained in a semi-saline medium containing 4 g/L of sodium citrate, 1.5 mg/L of K2HPO4, and 0 mg/L of potassium nitrate at pH = 7 after 10 d of inoculation. The atrazine removal (%) varied significantly depending on the stimulant type, concentration of atrazine, inoculation time, and pH of medium. The results show biostimulation and bioaugmentation may be useful biodegradation tools for atrazine-polluted, semi-saline medium.