APPLICATION OF AIR SPARGING AND BIOAUGMENTATION FOR NITROBENZENE AND ANILINE REMEDIATION IN SHALLOW GROUNDWATER: A LABORATORY-SCALE STUDY

Nitrobenzene (NB) and aniline (AN). widely used as chemical industrial materials, are commonly found as organic pollutants in groundwater. Among all the remediation technologies for organic chemical-contaminated groundwater, air sparging and bioaugmentation are two kinds of frequently used and cost-effective methods. In this study, air sparging and bioaugmentation were combined to remediate NB and AN contaminated shallow groundwater (laboratory scale) to overcome their own shortcomings. The results showed that sole air sparging removed NB and AN effectively, but only 90% of them. After a NB and AN degrading bacterial consortium was augmented, 99.0% of NB and AN were removed, which indicates that the combination of air sparging with bioaugmentation may remediate NB and AN to a much lower concentration (e.g., regulatory level). Groundwater analysis showed that NB and AN removal occurred mainly in upstream and midstream of the simulation system. In this system, air sparging provided adequate dissolved oxygen for injected bacteria and about 2 similar to 3 mg/L of dissolved oxygen was consumed in the biodegradation. PCR-DGGE analysis showed that injected degrading bacteria migrated with the depletion of NB and AN, and its intensity was affected by the concentrations of NB and AN. Overall, combining air sparging with bioaugmentation together increased the removal efficiency of NB and AN, and it is a cost-effective technology for the remediation of groundwater contaminated with NB and AN.