Kamal Khodaei; Hamid Reza Nassery; Hadi Tabani; Zahra Kazemizadeh
Abstract
Introduction: 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 ...
Read More
Introduction: 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. Material and methods: 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. Results and discussion: 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. Conclusion: PBB showed a very good performance for biodegradation of toluene by using calcium peroxide nanoparticles as an oxygen releasing compound.
Sara Saidi; Hamid Reza Nasei; Yaser Nik Peyman
Abstract
Introduction: Environmental pollution, especially the increasing trend of water resources pollution caused by oil spills, is one of the main concerns of advanced human societies. Considering the dangerous nature of oil contamination for the environment as well as the development of various diseases such ...
Read More
Introduction: Environmental pollution, especially the increasing trend of water resources pollution caused by oil spills, is one of the main concerns of advanced human societies. Considering the dangerous nature of oil contamination for the environment as well as the development of various diseases such as pulmonary and skin diseases and cancer, it is very important to purify the environment. Material and methods: In the study area, Shahr-e-Ray industrial zone, south of Tehran, petroleum activities have led to aquifer pollution, so that in some parts the thickness of light non-aqueous phase liquid (LNAPL) on the surface of the groundwater reaches more than 20 meters. Since the LNAPL acts as a source of exceeding pollution in the groundwater, in both saturated and unsaturated areas, it is necessary to purify the aquifer, which contains LNAPL fluid. In this regard, awareness of hydrodynamic parameters of the aquifer such as transmissivity and hydraulic conductivity is of great importance and even determinative of the type of recovery methods. Results and discussion: Because of the hydrogeological conditions of Rey industrial zone, LNAPL thickness and also time limitations, the Baildown test was used to determine hydrodynamic parameters of the aquifer, including transmissivity and hydraulic conductivity. This method involves removing the entire LNAPL from the casing and filter pack by moving part of the volume to create head differences. Afterwards, the fluid level is measured during removal. Conclusion: Regarding the results of the Baildown test, the range of LNAPL transmissivities in the aquifer varied between 0.085 to 11.506 m2/day and the range of hydraulic conductivities varied 0.01 to 1.62 m/day. According to the Baildown test result, the highest transmissivity of LNAPL in 10 wells was observed in the eastern and northeastern regions of the study area.
