Evaluation of the Performance of Structured Mixed Packing and Inert Packing Materials in Toluene Biotrickle-filtration

Duanfang Sun,Jianjun Li,Taicheng An,Meiying Xu,Guoping Sun,Jun Guo 한국생물공학회 2011 Biotechnology and Bioprocess Engineering Vol.16 No.5

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.

Bacterial Community Diversity and Functional Gene Abundance of Structured Mixed Packing and Inert Packing Materials Based Biotrickling Filters

Duanfang Sun,Jianjun Li,Taicheng An,Meiying Xu,Guoping Sun,Jun Guo 한국생물공학회 2012 Biotechnology and Bioprocess Engineering Vol.17 No.3

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 ureaformaldehyde 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 toluenedegrading 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. 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 ureaformaldehyde 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 toluenedegrading 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.

Toluene Removal Efficiency, Process Robustness, and Bacterial Diversity of a Biotrickling Filter Inoculated with Burkholderia sp. Strain T3

Duanfang Sun,Jianjun Li,MEI-YING XU,Taicheng An,GUO-PING SUN,JUN GUO 한국생물공학회 2013 Biotechnology and Bioprocess Engineering Vol.18 No.1

Microorganisms determine the overall biofilter performance under specific operating conditions. The toluene removal and process robustness of a laboratoryscale,ceramisite-based biotrickling filter inoculated with Burkholderia sp. strain T3 (BTFb) were compared with those of another biotrickling filter inoculated with activated sludge (BTFa) for 3 months under various operating conditions. Denaturing gradient gel electrophoresis was applied to visualise the bacterial community of the BTFa and BTFb. Real-time polymerase chain reaction was performed to determine the genes coding for toluenedegrading enzymes. Burkholderia sp. strain T3, which possesses the major toluene-degrading genes in BTFb, was traced in the BTFb bacterial community. The strain was found to stabilize the relative quantity steadily at higher than 60% during toluene biofiltration. Thus, BTFb performed more efficiently than BTFa as evidenced by achieving 98.86% toluene removal efficiency (RE) on 3 day, critical elimination capacity (EC) of 234.23 ± 10.54 g/m3/h, and rapid restoration of the initial RE and EC levels within 3 day of reoperation, even after 1 month of shutdown. The efficiency of BTFb is also evident by the stabilised RE and EC levels within a wide temperature range and a gradually decreasing system pH. Maintaining the pressure drop levels below 150 Pa during prolonged operation also contributed to the efficiency of BTFb. Thus, based on the study results,we propose that Burkholderia sp. strain T3 is a highly efficient and applicable inoculum for toluene biofiltration.

Treatment of Volatile Organic Compounds from a Typical Waste Printed Circuit Board Dismantling Workshop by a Pilot-scale Biotrickling Filter

Dongqi Liao,Jianjun Li,Duanfang Sun,Meiying Xu,Taicheng An,Guo-Ping Sun 한국생물공학회 2015 Biotechnology and Bioprocess Engineering Vol.20 No.4

A pilot-scale biotrickling filter (BTF) was designed to treat volatile organic compounds (VOCs) emitted from a typical waste printed circuit board (WPCB) pyrolysis workshop. Measured by gas chromatography-mass spectrometry (GC-MS), the main components of VOCs and their concentrations were benzene, toluene, chlorobenzene, ethyl-benzene, xylene, styrene, benzaldehyde, and trimethyl-benzene. The removal efficiencies of the BTF for these compounds ranged from 81.1 to 97.8% after 90 days of operation. The maximum elimination capacity of 25.94 g/m3 h was obtained with the inlet loading of 30.72 g/m3 fixed the fixed empty-bed residence time (EBRT) of 9.80 sec. Hazard ratio index based on threshold limit value for time weighted average (TLV-TWA) and VOCs concentrations indicated that the cancer risk of VOCs was significantly reduced after the BTF treatment. The microbial community analysis revealed initial inoculum and some emerging bacteria played crucial roles in the improvement of BTF performance with the biodegradation of this kind of VOCs by the polymerase chain reactiondenaturing gradient gel electrophoresis (PCR-DGGE) technique and pyrosequencing analyses indicated that proteobacteria phylum was the dominant in the BTF. All above results indicated that VOCs with multicomponent and fluctuant concentrations from a typical waste printed circuit board pyrolysis workshop were removed efficiently and in an environmentally friendly way by the biofiltration method.