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Sun D.,South China University of Technology | Sun D.,Guangdong Institute of Microbiology | Sun D.,Guangdong Provincial Key Laboratory of Applied Microbiology | Sun D.,Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application | And 15 more authors.
Biotechnology and Bioprocess Engineering | Year: 2011

Packing materials play a key role in waste gas treatment. Organic and inert packing materials have their disadvantages, which may be minimized by mixed packing. In this study, various operating conditions were applied to evaluate the performance of structured mixed packing and inert packing materials in toluene biotricklefiltration. Four biotrickle filters were packed with structured mixed packing materials, namely, ceramic pall rings, ceramic rashig rings, and lava rock. Their toluene removal capacity was studied for 217 day using a laboratory-scale reaction under various operating conditions. The key elimination capacity (removal efficiency > 95%) ranking of the biotrickle filters was as follows: Structured mixed packing (306.20 ± 7.90 g/m 3/h) > pall ring (156.71 ± 7.84 g/m 3/h) > rashig ring (153.31 ± 6.14 g/m 3/h) > lava rock (150.32 ± 9.19 g/m 3/h). The structured mixed packing and inert packing resulted in excellent toluene-degrading biofilter performance under long-term operation. The structured mixed packing provided a more rapid startup rate and better process robustness than the inert packing did. The biotrickle filter with mixed packing materials had a high elimination capacity which makes it suitable for various real-life applications, whereas the capability of the inert packing material was more suitable for treating a steady low toluene load. © The Korean Society for Biotechnology and Bioengineering and Springer 2011. Source


Chen X.-J.,CAS South China Sea Institute of Oceanology | Chen X.-J.,Guangdong Institute of Microbiology | Chen X.-J.,Guangdong Provincial Key Laboratory of Applied Microbiology | Chen X.-J.,University of Chinese Academy of Sciences | And 4 more authors.
Huanjing Kexue/Environmental Science | Year: 2010

The effects of soluble and insoluble Fe(III) on anaerobic azoreduction by Shewanella decolorationis S12 were examined in a series of experiments. Results showed that the effects of iron on anaerobic azoreduction depended on the solubility and concentration of the compounds. Azoreduction was inhibited by insoluble Fe(III) and 0.05-2 mmol/L Fe2O3 all decelerated the azoreduction activity of 0.2 mmol/L amaranth, but the increase in the concentrations of Fe2O3 did not cause an increasing inhibition. Soluble Fe(III) of which concentration less than 0.4 mmol/L enhanced azoreduction activity of 0.2 mmol/L amaranth but there was no linear relationship between the concentration of soluble Fe(III) and azoreduction activity. Soluble Fe(III) of which concentration more than 1 mmol/L inhibited azoreduction activity of 0.2 mmol/L amaranth and an increasing concentration resulted in an increased inhibition. The inhibition was strengthened under the conditions of limited electron donor. On the other hand, soluble Fe(III) and Fe(II) could relieve the inhibition of azoreduction by dicumarol which blocked quinone cycle. It suggests that in addition to quinone cycle, there is a Fe(III)↔Fe(II) cycle shuttling electrons in cytoplasmic and periplasmic environment. That is the reason why low concentration of soluble Fe(III) or Fe (II) can enhance azoreduction of S.decolorationis S12. It also indicates that insoluble Fe(III) and high concentration of soluble Fe(III) do compete with azo dye for electrons once it acts as electron acceptor. Thus, when iron and azo dye coexisted, iron could serve as an electron transfer agent or electron competitive inhibitor for anaerobic azoreduction under different conditions. High efficiency of azoreduction can be achieved through controlling the solubility and concentration of irons. Source


Chen X.,Guangdong Institute of Microbiology | Chen X.,Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application | Chen X.,Guangdong Provincial Key Laboratory of Applied Microbiology | Sun G.,Guangdong Institute of Microbiology | And 5 more authors.
Journal of Applied Microbiology | Year: 2011

Aim: To investigate the role of soluble and insoluble iron in azoreduction by resting cells of Shewanella decolorationis S12.Methods and Results: A series of analytical experiments were carried out. Results showed that insoluble Fe 2O 3 all delayed the reduction of amaranth but did not inhibit it. Adsorption to Fe 2O 3 particles by the bacterial cell surface could be the reason leading to the delay in azoreduction. For the soluble iron, an important finding was that azoreduction activities were inhibited by soluble iron in high concentration because of its higher redox potential, and the inhibition was strengthened when the electron donor supply was insufficient. However, activities of azoreduction could be enhanced by low concentration of soluble iron. This stimulating effect was because of the electron transfer but not the cell growth.Conclusions: The effects of iron on azoreduction by the resting cells depended on the solubility and concentration of the iron compounds, which was different from what was observed by the growing cells in the previous studies.Significance and Impact of the Study: This study has both theoretical significance in the microbial physiology and practical significance in the bioremediation of azo dyes-contaminated environment. © 2010 The Authors. Journal of Applied Microbiology © 2010 The Society for Applied Microbiology. Source


Sun D.,South China University of Technology | Sun D.,Guangdong Institute of Microbiology | Sun D.,State Key Laboratory of Applied Microbiology | Sun D.,Guangdong Open Laboratory of Microbial Culture Collection and Application | And 21 more authors.
Biotechnology and Bioprocess Engineering | Year: 2012

Packing is the most important factor in biofilter design. A structured mixed packing (SMP) material, combined with various organic and inorganic materials (mineral matter is 80.18 ± 0.48%, w : w), was constructed by urea-formaldehyde resin in order to minimize the disadvantages of these materials when used as stand-alone components. The performance of the toluene biotrickling filter (BTF) packed with SMP was compared with the other BTFs packed with a ceramic raschig ring, ceramic pall ring, and lava rock, respectively, for 217 day under various operating conditions. Real-time PCR and DGGE techniques were applied to reveal the gene coding for the toluene-degrading enzymes and the bacterial community structure in the BTFs. The toluene-degradation gene copies exponentially increased, and bacterial diversity significantly decreased with the improving elimination capacities of the BTFs. The overload and shutdown operations resulted in insignificant fluctuations in the toluene-degradation gene copies at equal levels as well as a slight variation in the bacterial community structures in the BTFs. Various putative toluene-degrading bacteria were found using sequencing bands from the DGGE gels; some bacteria, such as Burkholderia spp., were further confirmed by real-time PCR; other bacteria, such as Alcaligenes spp., might not have been reported. The packing properties of SMP material supported more toluene-degradation gene copies in the biofilm, and higher toluene-degrading bacterial diversity of the BTF, than did inert packing. Thus, the BTF with SMP demonstrated excellent performance, suggesting the suitability of SMP for real applications, whereas the capabilities of inert packing materials are more suited to the treatment of steady low VOC loads. © 2012 The Korean Society for Biotechnology and Bioengineering and Springer. Source

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