Bioremediation of benzene from groundwater by calcium peroxide (CaO2) nanoparticles encapsulated in sodium alginate

This study was conducted through batch and column experiments for remediation of benzene from groundwater (50 mg/L) by encapsulated calcium peroxide (CaO2) nanoparticles and FeSO4. The results showed complete benzene removal by CaO2 capsules within 60 days, whereas, addition of FeSO4 capsules to the batch tests removed 100% of pollution after 70 days. Furthermore, the initial temperature and pH of the groundwater showed significant impacts on the remediation process. Results indicated that benzene was removed more efficiently by addition of FeSO4 and CaO2 capsules in modified Fenton (MF) reaction at lower pH (3). However, raising the pH resulted in better stimulation of microbial population due to more oxygen generation from CaO2 capsules. In addition, results revealed that CaO2 capsules are able to perform effectively for pollution bioremediation at 30 °C and at lower temperatures MF reaction is performed ideally. In column experiments, MF reaction showed higher capability for benzene remediation from the effluent (100% removal after 4 days) and CaO2 capsules were successfully exploited for comprehensive treatment of the groundwater after 30 days. Results indicated that MF reaction was more potent than only CaO2 capsules for benzene removal from groundwater. Present investigation provides a considerable insight into application of CaO2 nanoparticles as reactive barriers.