| Chlorobenzene is a typical volatile organic compound（VOC）with stable structure,large biological toxicity and low water solubility.The traditional biological treatment technology is not ideal for chlorobenzene abatement.The two-phase partitioning bioreaction system utilizes non-aqueous media to enhance the mass transfer of hydrophobic VOCs and increase the removal efficiency of contaminants.However,the liquid non-aqueous phase（NAP）has disadvantages such as being easily emulsified and difficult to recycle.Some researchers revealed that replacing the liquid non-aqueous phase with a solid non-aqueous phase solve the above problems effectively.Herein,with high efficient chlorobenzene-degrading bacteria as a model microorganism,chlorobenzene as target pollutant,two-phase partitioning bioreactor system constructed by solid non-aqueous phase is used to study the enhanced chlorobenzene-biodegrading process of solid non-aqueous phase.In this work,it is expected to achieve efficient biological purification of chlorobenzene and lay the foundation for the treatment of CB-contaminated exhaust by two-phase partitioning system.In this paper,a two-phase partitioning biosystem is constructed by using silicone masterbatch and silicone powder as the solid non-aqueous phase（NAP）.Their respective intensification of chlorobenzene removal in the two systems is investigated and compared.The study revealed that compared with the silicone masterbatch,the absorption rate of the chlorobenzene was faster than the silicone powder.The absorption equilibrium could be reached within 40 minutes,and the desorption balance could be reached within 30 minutes.When the dosage of solid NAP is 0.5 g each bottle,the ratio of chlorobenzene removal efficiency in the experimental group with silicone powder is 94.7%within 37 h,and the degradation rate is about 20%higher than the experiment group with silicone masterbatch.Fitting the experimental data with the Haldane model,the maximum specific degradation rateγmaxax of strain LW26 were 2.58 h-11 and 2.66 h-1,respectively in the two-phase partitioning system with silicone masterbatch and silicone powder.A superparamagnetic Fe3O4 nanoparticle is prepared by chemical co-precipitation method and the Fe3O4 is modified to obtain a magnetic silicone powder（Fe3O4@SiO2@PDMS）.The saturation magnetization of the magnetic silicone powder is 64.25 emu·g-1,and the saturation magnetization of Fe3O4 is 69.32 emu·g-1.The coating decrease the saturation magnetization,but it doesn’t affect the magnetic silicone powder to be separated from the two-phase partitioning biosystem by external magnetic field.Compared to the silicone masterbatch,the magnetic silicone powder has a faster rate of absorption/desorption of chlorobenzene,and the absorption/desorption equilibrium can be reached in 25 minutes.Magnetic silicone powder is of abiotoxicity nondegradation and stability.When 0.5 g/bottle of magnetic silicone powder is added to the system,strain LW26 could degrade 99.9%of chlorobenzene in 25 h with the concentration of 5.5 mg.It’s found that when the concentration of chlorobenzene is 33mg/bottle,the activity of the ETS in the two-phase distribution system was 264.93mg·g-1·h-1,while ETS activity can hardly be detected in the single-phase system.It reveals that when the substrate concentration is too high,magnetic silicone powder can absorb chlorobenzene so that the concentration of the aqueous phase is decreased to less inhibitory concentrations,microorganisms in the aqueous phase is maintained high bioactivity.The total amount of extracellular polymer produced by the bacteria in the two-phase distribution system is of 35.60±8.42 mg·g-1,which was 1.12 times of the single-phase system.It further shows that the presence of magnetic silicone powder does reduce the toxic effect of chlorobenzene on microorganisms,making strain LW26highly effective in degrading chlorobenzene off-gas.The experimental data fitted with the Haldane model,the maximum specific degradation rateγmaxax of strain LW26 was2.73 h-1,in the two-phase distribution system with magnetic silicone powder.The magnetic silicone powder can be recovered by an external magnetic field,and the recovered can maintain the removal effeciency of chlorobenzene above 99.4%.So,magnetic silicone powder not only enhances the performance of biodegradable chlorobenzene exhaust gas,but it can also be reused with good condition. |
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