| Benzene, toluene, ethylene and xylenes (BTEX, in brief), as important aromatic compounds, exist in oil and petroleum products and were widely used as solvents in industry. BTEX were improved to be carcinogenic, teratogenetic and mutagenic to endanger human-beings'health by contaminating underground water with leakage and delivery. To study the migration and removal of BTEX-contaminated groundwater is of theoretical and application importance. In this study, the transport and transformation formulation was established for BTEX in soil and groundwater system. Then the immobilized biological barrier has been presented for describing the remediation of BTEX-contaminated groundwater, which was included the domestic influence and community analysis of mixed culture, preparation of immobilized bio-beads and in situ removal process of BTEX.The detailed works of this thesis are as follows:The results of batch experiment indicated that linear equilibrium adsorption equation can well describe the adsorption behavior of BTEX in clayed soil. A soil column experiment was performed to calculate the dispersive coefficient and retardation factor of the test medium. As for Rd, the retardation factors were followed by benzene, toluene, ethyl benzene and xylenes, which meant the aquifer medium had hardly the abilities to retard and attenuate benzene and could partly retard toluene,ethyl benzene and xylenes.Based on the enrichment and purposed acclimation of the aerobic microbes, degradation performance of BTEX was studied and optimal temperature was 30℃, pH value was 7.5 and inoculums was 2.61 mg/L. The one-order kinetics constants of substrates'degradation were followed as: benzene < toluene < ethyl benzene < xylenes. As for BTEX mixture, the dynamics parameters were apparently decreased because of competitive effect. Through Monod kinetics simulation, the maximum-specific-growth rates of mixed culture were separately 0.3395, 0.5199, 0.6298 and 0.2701 h-1, while the half-saturation concentrations were 160.6, 124.6, 168.3 and 227.8 mg/L.Different domestic conditions have been taken to study the changes of microbial community structure. The results of PCR-DGGE showed that different domestic indeed influenced the mixture's DNA diversity and biodegradation. The microbes, acclimated by BTEX mixture, had the key metabolism enzyme as catechol-1, 2-dioxygenese, which indicated the microbes could firstly biodegrade BTEX into catechol with alkyl, then degrade into cis,cis-muconic acid with alkyl by ortho-cleavage, at last transform into carbon dioxide and water in tricarboxylic acid cycle.Bench experiments of degradation were carried out to assess the performance of two kinds of new-typed immobilized bio-beads, which were produced with sodium alginate (SA), polyvinyl alcohol (PVA) and activated carbon fiber (ACF). As a result, SA-MB was considered better in the microstructure, degradation and reusability, and ACF was a well-performing encapsulation carrier, which could enhance biodegradation of BTEX by changing the microstructure and stabilities of MB.Permeability of SA-MB as medium of biobarrier was measured as1.32×10-10 m2, which was proved to be suitable for permeable reactive system. Furthermore, the removal of BTEX was studied in the biobarrier which was simulated by laboratory column. It showed that the presented biobarrier with immobilized biobeads could do well in remedying BTEX-contaminated groundwater and provide dependable basis for in situ remediation practice.
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