Process Fundamentals And Pilot Demonstration Of Wheat Straw Enhanced Bioaugmentation Of Petroleum-and Salt-contaminated Soil

This dissertation started with an overview of the recent advancement of soil remediation techniques and their practical applications. The special challenges to the bioaugmentation of petroleum- and salt-contaminated soil in oil field were highlighted and discussed. A novel bioaugmentation using baterial-fungi consortia was proposed, in which wheat straw was applied to construct coarse layer so as to facilitate both the salt leaching and the degradation of petroleum, as a result of enhanced growth of the inoculated consortia upon the addition of quality carbon source and presence of the humic acid as adsorbents for metal ions, both of which were produced from the decomposition of wheat straw.A comprehensive investigation of in-situ bioremediation was carried out at a lab-scale. It was proven in the column test that the presence of coarse layer of wheat straw effectively enhanced salt leching while prevented the salt upwards movement. The decomposition of straw provided both polyacchrides searving as quality carbon sources for the inoculated microorganisms and humic acid as adsorbent for aqueous metal ions. All these led to an enhanced growth of inoculated microorganisms and an intensified degradation of petroleum, consequently. Moreover the addition of wheat straw favored the competition of inoculated microorganisms over the native ones. A distinct reduction in the hydrophobicity was obtained during the degradation of total petroleum hydrocarbon (TPH) which thus facilitated the salt leaching simultaneously.The production of unsaturated glycolipids biosurfactant that could enhance the solubility of phenanthrene, a model compound of polycyclic aromatic hydrocarbons (PAHs), was investigated for an optimal productivity by E. cloacae. An enhanced desorption of phenanthrene from kaolinite representing the contaminated soil was obtained in the presence of biosurfactant secreted by E. cloacae. This improved the bioavailability of phenanthrene and enhanced the degradation consequently, which could be furtherly improved when glucose was added as the prior carbon source.Pilot demonstration of wheat straw enhanced bioaugmentation of petroleum- and salt-contaminated soil was carried out on an area of 7000m2 in Zhongyuan Oilfield, Henan, China. Salt leaching efficiency of test area was greatly enhanced by the coarse wheat straw layer, as compared to that obtained in the control area without coarse layer. The overall concentrations of ions, as indicated by soil electroconductivity and that for Na+ and Cl- in particular in the remediated soil, reached their respective conterparts in the regular farmland. The amount of biomass of bacteria and fungi as well as the overall biodegradation activity of the microconsortia detected in the test area were significantly higher than those obtained in the control area. The implementation of wheat straw enhanced bioaugmentation led to an overall degradation ratio of TPH of 67% and a yield of 72% in wheat grain in comparision to that obtained in the regular farmland. The pilot demonstration also set up process scheme and regulations for the further implementation of this technique at a large scale.Macroporous alginate beads with lignin (MCAL) were prepared to encapsulate P. chrysosporium responsible for the degradation of phenanthrene. It was shown that the macroporous structure enhanced the mass transfer of glucose while incorporated with the growth behavior of P. chrysosporium. These contributed to a significant improvement in the growth of P. chrysosporium. The introduction of lignin as an adsorbent for phenanthrene into alginate beads improved the availability of phenanthrene for the immobilized P. chrysosporium, and led to a greatly improved degradation of phenanthrene consequently. MCAL encapsulated microorganisms provided an effective and easy-to-use microbial model for the implementation of bioagumentation.