Date of Award
Master of Science (MS)
Environmental Engineering and Science
David L Freedman
Environment pollution is a global problem that has been created through decades of industrial development. Remediation activities are needed to mitigate the resulting health and environmental impacts. Nowadays there are still numerous sites that require clean-up of complex mixtures of contaminants that exhibit an even greater challenge to scientists and engineers. Area P, located in the Camaçari industrial site, is the subject of this research. The environmental impacts created by this area is a consequence of petrochemical industries located within the zone.The main objectives of this research were to evaluate the interactions among chemicals of concern in Area P during aerobic and anaerobic biodegradation, and to develop strategies for remediation, including biodegradation, chemical reduction, and chemical oxidation. Batch and flow through column experiments were performed to evaluate inhibition caused by mixtures of the contaminants and how best to sequence treatment processes to achieve high rates of degradation. Based on the results, the main outcomes were: • In a batch test with a 4-NT anaerobic enrichment culture, complete inhibition was observed on the rate of 4-NT biodegradation when all the compounds were present at their highest concentration. No degradation was achieved. • In a batch test with a 2,6-DNT anaerobic enrichment culture, no inhibitory effects were observed on the rate of the anaerobic biodegradation of 2,6-DNT when all the compounds were present at their highest concentration. • In a batch test with the CB and 1,2-DCB aerobic enrichment cultures, groundwater from Area P was inhibitory. Once treated by a sequence of ISCR and ISCO at a stoichiometric dose, the rate of biodegradation increased, suggesting that chemical treatment removed the inhibitors. At a dose that was 10 times the stoichiometric level, the rate of biodegradation was inhibited. Getting the dosing correct for in situ application will therefore be an important consideration. • In flow through column experiments, a treatment sequence consisting of aerobic bioaugmentation, ISCR/anaerobic bioaugmentation, and ISCO/aerobic bioaugmentation was the most effective for removing 4-NT, 2,4-DNT, 2,6-DNT, CB and 1,2-DCB. Repeated additions of oxidant achieved removal of the aminotoluenes daughter products. 1,4-Dioxane and 1,2-DCA were persistent under these conditions. • In flow through column experiments, a treatment sequence consisting of chemical oxidation/aerobic biodegradation or aerobic biodegradation alone were effective only for removal of CB and 1,2-DCB. All other compounds persisted. • Using pseudo first order kinetic constants determined from operation of the columns, the estimated time to decrease the parent compounds to regulatory standards is only a matter of several weeks. However, that is under the optimal conditions created. In situ clean-up times are certain to be longer, but the prospect for reaching the clean-up goals is reasonable as long as the various treatment sequences can be implemented.
Jimenez Garcia, Jimena Paola, "Evaluation of Strategies for Treatment of Complex Waste Mixtures at an Industrial Site in South America" (2021). All Theses. 3624.