Application of calcium peroxide nano-powder in a bio-barrier for remediation of groundwater oil pollution

Groundwater pollution occurs during refining processes, transportation, storing, and distribution of oil products. Most of the oil components are insoluble in water, however, there are some components such as benzene, toluene, ethylbenzene, and xylene (known as BTEX) that are soluble in groundwater. These compounds are carcinomic and categorized as very dangerous pollutants. Permeable bio-barrier (PBB) technologies are extensively used to remove groundwater oil pollution. However, providing oxygen to improve the bioremediation efficiency in groundwater is a challenge. This research aimed to test the application of calcium peroxide nano-particles to provide more dissolved oxygen in a permeable bio-barrier.

Pseudomonas sp. BTEX-30 strain isolated from polluted groundwater around Tehran’s oil refining area was used to establish the permeable bio-barrier. Bioremediation kinetics and environmental conditions required for optimum bioremediation of bacteria were evaluated. Calcium peroxide nanoparticles have been synthesized and used for increasing the dissolved oxygen in groundwater. Bio-barrier was simulated using a glass column and Ottava sand as a porous media. The inflow rate was 0.5 ml/s with different toluene concentration for 14 days. Water samples from the inlet and outlet of the bio-barrier were taken during the test and analyzed using GC for defining the toluene concentration. Fate and transport processes in bio-barrier have been simulated by numerical models.

There were no significant differences in the toluene concentration between inlet and outlet on day one. Differences in toluene concentration between inlet and outlet started from day two. Bio-barrier showed a good response to increasing and decreasing in inlet concentration stresses after nine days. According to the results, PBB showed the best performance at 30 ppm concentration of inlet. The calculated concentration of toluene by the PBB numerical model showed a very good correlation in most stress periods.

PBB showed a very good performance for biodegradation of toluene by using calcium peroxide nanoparticles as an oxygen releasing compound.