Study On Removal Of Oil Contaminants From Soil By Bioventing (BV)

Bioventing is an in-situ technology used in removal of organic compounds in contaminated soil. It has been applied since the end of 1970's, and now there are many cases of applying BV in spot successfully. In this paper, study and experiment of the removal of benzene, toluene, xylene and trichloroethlene (TCE) of oil-contaminated in soil commonly have been finished.Microorganisms culture,acclimation, screening and breakaway were studied. High quality germs with high ratio of degradation were obtained through batch experiments. Optimal conditions for the growth of microorganisms were obtained through study of effects of pH, temperature and concentration of contamination on microorganisms. The results of the experiments of single contaminant (toluene), multicomponent contaminants (toluene, benzene, xylene) and cometabolic contaminant TCE in bioventing show that microorganisms may degrade the contaminants and the portion of removal by degradation can be 10-38%. It is shown bioventing is a superiority method of soil remediation to other methods.The results of experiments of removal of toluene in aqueous and in NAPL show that the contaminant of degradation by microorganisms in aqueous is easier than in NAPL. Parameters of soil characteristics, microorganisms degradation kinetics characteristics and adsorption isotherms of contaminants were determined. One-dimensional mass transfer model was established on the transportation and transference of the contaminants in soil. The results of experiments of removal of toluene in aqueous and in NAPL show that the experiment data accord with the model well. It was demonstrated that the proposed model can describe the removal of toluene in aqueous and NAPL in bioventing and have significance in bioventing at field pickup.