Stripping of volatile organic compounds with CO2 Focus on toluene and trichloroethylene

Abstract

Nowadays our urban landscape expands at an ever increasing rate. Brownfields are created mostly in urban areas. These brownfields may be highly polluted. Due to expensive remediation methods, alternative methods need to be developed. Ecogrout is a method where the soil will be approved by in situ strengthening and simultaneously remediation of the groundwater is achieved. With the Ecogrout reaction CO2 is obtained, which can be used to strip dissolved contaminants. The stripping potential for trichloroethylene (TCE) and toluene with CO2 from the Ecogrout process was evaluated by performing batch experiments. Within the batches a layer of gravel was present. The contaminants were dissolved in NaHCO3 stock solutions. These NaHCO3 stock solutions were mixed thoroughly with CaCl2 to obtain the Ecogrout reaction. Different experiments were performed during this research. These experiments include pressure experiments, vapor pressure experiments and batch experiments. The development of setup and methods used for these research experiments was an important part of this master research. Resulting from the batch experiments stripping of TCE in the first 30 minutes increased proportionally with the CO2 production. The equilibrium concentrations of gaseous contaminants for both concentrations CaCl2 and NaHCO3 used differed due to different ionic strengths. Also the results of TCE differed from the results obtained for toluene. Different interpretations were given to discuss the difference in results obtained from the experiments. Nevertheless due to the release of CO2, the gaseous contaminant concentrations increased with reference to the volatilization rates. Concluding from this positive result it is recommended to perform more research. More research can be done by for example column and field experiments to obtain more advanced systems.