Maryam Yavari-Bafghi - Extremophiles Laboratory, Department of Microbiology, School of Biology, College of Science, University of Tehran, Tehran, Iran
Mahmoud Shavandi - Microbiology and Biotechnology Group, Environment and Biotechnology Research Division, Research Institute of Petroleum Industry, Tehran, Iran
Seyed Mohammad Mehdi Dastgheib - Microbiology and Biotechnology Group, Environment and Biotechnology Research Division, Research Institute of Petroleum Industry, Tehran, Iran
Mohammad Ali Amoozegar - Extremophiles Laboratory, Department of Microbiology, School of Biology, College of Science, University of Tehran, Tehran, Iran

Background and Aim : Groundwater is one of the most important water resources that is widely used in washing and irrigation processes for about ۴۰ % of the world's agricultural products. Pollution of groundwater with various contaminants such as phenols is a crucial environmental concern and threatens the health of human society. This study evaluated the effects of calcium peroxide and small bioreactor chambers on phenol removal from groundwater.Methods : Design the experiments and analysis of results were performed by a statistical package Design-Expert version ۱۱ and analysis of variance (ANOVA), respectively. Powdered and encapsulated synthesized-calcium peroxide (CaO۲) nanoparticles were applied to investigate the effect of biostimulation in groundwater contaminated by phenol. Bioaugmentation was also performed by using innovative Small Bioreactor Chambers (SBCs) containing a phenol-degrading consortium which was successfully isolated from a water well located in Iran.Results : Designed experiments revealed that the highest growth rate and phenol degradation of the ph۱۰۰-consortium were observed at ۱۵ °C and pH ۷.۵ in the presence of ۵۰۰ mg·L-۱ of powdered CaO۲ and ۱۰۰ mg·L-۱ of phenol as a sole source of carbon. According to the next-generation sequencing (NGS) analysis of the consortium, Proteobacteria and Bacteroidetes with ۷۵.۳% and ۱۶.۲% relative abundance were the dominant phyla in the ph۱۰۰-consortium, respectively. At the class level, the predominant taxa were Gammaproteobacteria, followed by Bacteroidia, Alphaproteobacteria and Actinobacteria. Batch experiments results indicated that the addition of ۵۰۰ mg·L-۱ of encapsulated CaO۲ was the optimum concentration for phenol (۱۰۰ mg·L-۱) bioremediation in ۶۰ days with the negligible negative impacts on the microbial population. In addition, the highest biodegradation percentage were achieved during incubation of SBCs in a medium supplemented with ۵۰۰ mg·L-۱ CaO۲ powder in ۲۵th days of experiment.Conclusion : These results provide evidence for a successful application of calcium peroxide nanoparticles and SBCs containing the selected microbial cultures in water treatment processes.

Bioremediation, Bioaugmentation, Biostimulation, Groundwater, Phenol