Study On The Enhanced Aerobic Bioremediation For TBBPA-Cu Co-contamination By Sludge-Based Microbial Agent

Tetrabromobisphenol A(TBBPA) is one of the most widely used brominated flame retardants around the world, and it is also a potential endocrine disruptor. Due to the bioaccumulation, persistence and biological toxicity, it is necessary to investigate the biodegradation of TBBPA. Previous researches showed that the anaerobic microbial degradation of TBBPA was incomplete along with the potential accumulation of the more poisonous intermediate product, named bisphenol A. Although continuous anaerobic-aerobic biological technology could biodegrade TBBPA completely, it increased the complication of treatment process. Therefore, one step process for aerobic transformation of TBBPA was applied in this thesis. In addition, due to the hydrophobicity of TBBPA, soil and sediment would be the final sink in the environment. At the same time, the site polluted by TBBPA was frequently accompanied with heavy metals. However, little information was available on the bioremediation of the combined pollution (i.e., TBBPA and heavy metal). We aimed to examine the effect of sludge-based microbial agent on the bioremediation of TBBPA-Cu co-contamination.Thermo-alkaline method was adopted to treat active sludge in order to acquire the sludge-lysate to culture Pseudomonas sp. fz with the high degradation efficiency of TBBPA, and aim to obtain the sludge-based microbial agent in this reseach. Under the conditions of 150 rpm and 35℃, the sludge-based bacterial agent removed 85.0% and 82.1% of TBBPA(10 mg/L) after 96h in the presence and absence of Cu(II)(5 mg/L), respectively. In addition, lower concentration of Cu(II)(<5 mg/L) could efficiently accelerate the transfomiation of TBBPA. Furthermore, the sludge-based bacterial agent could reduce the inhibitory action of the Pseudomonas sp. fz biodegradation by excessive Cu(II)(5-25 mg/L).Through analysis the metabolism in the sludge-based mirobial agent, it suggested that organic matter of sludge-lysate could be acted as the cometabolic substrate in the degradation of TBBPA. The 3D detection of fluorescence spectrophotometer informed that the humic acid from sludge-lysate had two sites coupled with heavy metal complexation. There were 77.5% and 47.8% functional groups involved in Cu(II) complexation, respectively. In particular, carboxyl, hydroxyl and carbonyl groups played the important roles in the complex reaction on the basis of Fourier Transform Infrared Spectroscopy (FTIR) analysis. Additionally, the microbial physiological characteristics were showed distinctly in the different mediums. The hydrophobicity of cell surface had been improved and the dehydrogenase activity of strain fz had been raised in the presence of sludge-lysate. The damage of microbial cell membrane from the toxic effects of TBBPA and Cu(II) were reduced in the presence of sludge-lysate.Finally, the research of sludge-based bioagent applied to the bioremediation of TBBPA-Cu co-contaminated soil was investigated through biological aerobic composting process. Under the 40%-50% of moisture capacity in the soil, the sludge-based bioagent was capable of remediating contaminated soil by degrading 76.1% of TBBPA (30 mg/kg) and improving the dehydrogenase activity 11-folds over the contamined soil in 15 days experimental period. Moreover, the bioremediation of TBBPA (30 mg/kg)-Cu (800 mg/kg) co-contamined soil was exhibited with high efficiency by degrading 75.6% of TBBPA and converting the ionic Cu to the organic bound Cu along with the seed germination index was increased 25% after 15 days.