Study of denitrification and reductive dechlorination processes applied to groundwater bioremediation

Tesis doctoral de Montserrat Calderer Perich

This thesis is based on the study of bioremediation processes as reliable technologies to remove contaminants from groundwater. specifically, it is aimed to study denitrification and reductive dechlorination as bioremediation technologies to remove nitrates and chlorinated aliphatic hydrocarbons (cahs), respectively, from polluted groundwater. In addition, it is aimed to apply advanced technologies which allow improving on the knowledge of these processes. the aquifer associated to the stream argentona, located in argentona, catalunya (spain), was selected as study site to investigate the denitrification process. In the first part, microcosm experiments containing groundwater and subsoil from the aquifer were performed. From these first studies it was observed the low capacity of the aquifer to eliminate nitrates under natural conditions, but, at the same time, it was noted the feasibility of applying a bioremediation process such as the addition of organic matter. In addition, the influence of different factors such as the presence of oxygen and the type of electron donor on the denitrification process was studied. afterwards, a mathematical model was developed to explain the microbiological processes that occur when stimulating the aquifer material with an organic carbon source. The model could successfully explain the consumption of oxygen, nitrates and organic matter by the indigenous facultative heterotrophic microbial population from aquifer. Some parameters of the model were calibrated from experimental data and the quality of these parameters was investigated. The developed model constitutes a first approach in order to have reliable models for in situ denitrification. in order to advance in the study of the denitrification process in natural conditions, dynamic experiments were carried out simulating the groundwater flow through the aquifer. The efficiency of injecting organic matter under these conditions was demonstrated. At the same time, hydrodynamic effects of the process were observed, indicating the importance to design properly bioremediation technologies before its application in field-scale. Furthermore, an integrated model coupling the biochemical reactions and the transport processes inside the column was developed and applied to describe denitrification under dynamic conditions. finally, molecular microbiological techniques were applied to investigate microbial changes due to the application of enhanced denitrification. On the one hand, real-time polymerase chain reaction (real-time pcr) assays revealed the growth of microbial population, specially of denitrifying bacteria in aquifer material stimulated with an organic carbon source. On the other hand, th denaturing gradient gel electrophoresis (dgge) method allowed to investigate changes in the indigenous microbial community due to the amendment with organic matter. in order to advance in the knowledge of bioremediation processes in groundwater, reductive dechlorination of cahs in groundwater was studied. In this case, experiments at laboratory scale were applied, aimed to study the possible application of a permeable reactive barrier (prb) to eliminate a cah-contaminated plume, containing basically cis-1,2-dichloroethene and vinyl chloride, which flows to the river zenne near brussels, belgium. the study included batch experiments in order to investigate the degradation potential in aquifer and sediments of the river zenne, as well as column experiments which simulated the groundwater flow through the sediments of the river or the aquifer material. The results demonstrated the high degradation potential of the sediments, which in the long term could be enhanced to act as a natural biobarrier of the system in order to prevent groundwater contaminants from arriving at the surface water of the river zenne.

 

Datos académicos de la tesis doctoral «Study of denitrification and reductive dechlorination processes applied to groundwater bioremediation«

  • Título de la tesis:  Study of denitrification and reductive dechlorination processes applied to groundwater bioremediation
  • Autor:  Montserrat Calderer Perich
  • Universidad:  Politécnica de catalunya
  • Fecha de lectura de la tesis:  23/06/2010

 

Dirección y tribunal

  • Director de la tesis
    • Joan De Pablo Ribas
  • Tribunal
    • Presidente del tribunal: José Luis Cortina pallas
    • winnie Dejonghe (vocal)
    • (vocal)
    • (vocal)

 

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