Airlift two-phase partitioning bioreactor for dichloromethane removal: Silicone rubber stimulated biodegradation and its auto-circulation

Biofiltration of toluene and ethyl acetate mixture by a fungal-bacterial biofilter: Performance and community structure analysis

The inhibitory effect of hydrophilic volatile organic compounds (VOCs) on hydrophobic VOCs removal was found to be efficiently reduced by the fungal-bacterial biofilters (F&B-BFs) developed in the present study. Overall, the toluene and ethyl acetate mixture removal efficiencies (REs) and elimination capacities (ECs) of F&B-BFs were superior to those of bacterial biofilters (B-BFs). The REs for toluene and ethyl acetate were 32.5 ± 0.8 % and 74.6 ± 1.0 %, respectively, for F&B-BFs, in comparison to 8.0 ± 0.3 % and 60 ± 1.3 % for B-BFs. The ECs for toluene and ethyl acetate were 13.0 g m-3 h-1 and 149.2 g m-3 h-1, respectively, for the F&B-BF, compared to 3.2 g m-3 h-1 and 119.6 g m-3 h-1 for the B-BFs. This was achieved at a constant empty bed residence time (EBRT) of 45 s. F&B-BFs exhibited a superior mineralization efficiencies (MEs) compared to B-BFs for a VOC mixture of toluene and ethyl acetate (≈36.1 % vs ~ 29.6 %). This is attributed to the direct capture of VOCs by the presence of fungi, increased the contact time between VOCs and VOCs-degrading bacteria, and even distribution of VOCs-degrading bacteria in the F&B-BFs. Moreover, compared with B-BFs, the coupling effect of genus Pseudomonas degradation, and unclassified_f_Herpotrichiellaceae and unclassified_p_Ascomycota adsorption of F&B-BF resulted in a reduction in the impact of the presence of hydrophilic VOCs on the removal of hydrophobic VOCs, thereby enhancing the biofiltration performance of mixtures of hydrophilic and hydrophobic VOCs.

Enhancement of gaseous chlorobenzene biodegradation and power generation in a microbial fuel cell by bifunctional Acinetobacter sp. HY-99C

The efficient biodegradation of volatile chlorinated hydrocarbons using microbial fuel cells (MFCs) offers a feasible approach for purifying waste gas and alleviating energy crises. However, power generation is limited by poor pollutant biodegradation and slow electron transfer. The bifunctional bacterium Acinetobacter sp. HY-99C was screened and used to improve the performance of a conventional MFC. The inoculation of strain HY-99C into the conventional MFC promoted the formation of a compact biofilm with high metabolic activity and an enriched bifunctional genus (Acinetobacter), which resulted in the accelerated decomposition of chlorinated aromatic compounds into biodegradable organic acids. This led to efficient chlorobenzene removal and power generation from the MFC, with a chlorobenzene elimination capacity of 70.8 g m-3 h-1 and power density of 89.6 mW m-2, which are improved over those of previously reported MFCs. This study provides novel insights into enhancing pollutant removal and power generation in MFCs.

From rosin to novel bio-based silicone rubber: a review

Rosin is a characteristic natural renewable resource. In view of the unique hydrogenated phenanthrene ring skeleton structure of rosin, it can be designed and synthesized to modify silicone rubber for improving its mechanical properties, thermal stability, and other properties. In this paper, the research progress of silicone rubber modified by rosin and its derivatives is reviewed, including internal or surface modification of room temperature or high temperature vulcanized silicone rubber. The different chemical modifications and polymerization pathways to obtain bio-based silicone rubber (e.g. rosin-based silicone cross-linking agent, filler compound rosin-based silicone cross-linking agent, rosin-based polymer, and rosin quaternary ammonium salt bifunctional antibacterial coating) are discussed and its research prospect is reviewed. Overall, the present review article will provide a quantitative experimental basis for rosin to produce bio-renewable multifunctional silicone rubber to increase our level of understanding of the behavior of this important class of silicone rubber and other similar bio-based polymers.

Metal-organic framework derived bio-anode enhances chlorobenzene removal and electricity generation: Special Ru4+/Ru3+-bridged intracellular electron transfer

Efficient removal of chlorinated organic contaminants using the microbial fuel cell (MFC) provides a promising strategy to alleviate water pollution and energy crisis. However, bio-degradation is challenged by poor biofilm formation and sluggish intracellular electron transfer, causing unsatisfactory electricity generation. To address those problems, a metal-organic framework derivative, Ru-porous TiO2 (Ru-PT) bio-anode has been artfully designed herein for chlorobenzene removal. The Ru-PT bio-anode not only formed a compact anodic biofilm due to the large specific surface area of PT, but more importantly, it introduced special pseudocapacitance-enhanced intracellular electron transfer by slowly implanting Ru4+/Ru3+ redox pair into bacteria. Such a Ru4+/Ru3+ implantation was then found to directionally induce the enrichment of a dual-functional genus (degrader & exoelectrogen), Pseudomonas, thereby enhancing the conversion of bio-refractory chlorophenols towards biodegradable carboxylic acids. These features allowed our MFC to have a resilient chlorobenzene removal and accompanied satisfactory electricity generation, with power density, coulombic efficiency, and turnover frequency reaching 662 mW m-2, 8.7%, and 386,622 s-1, which outcompeted those of other MFCs reported. Further, benefiting from the reversible pseudocapacitance, the Ru-PT bio-anode intriguingly functioned as an internal capacitor for electricity storage. This work provided important insights into cost-effective bio-anode development and offered an avenue for engineering MFC.

Efficient biodechlorination at the Fe3O4-based silicone powder modified chlorobenzene-affinity anode

The treatment of chlorinated volatile organic compounds faces challenges of secondary pollution and less-efficiency due to the substitution of chlorine. Microbial fuel cells (MFCs) provide a promising opportunity for its abatement. In this study, a novel Fe3O4 nanoparticles and silicone-based powder (SP) were integrated and immobilized on carbon felt (CF+Fe3O4@SP), which was further used as anode in the chlorobenzene (CB) powered MFC. Owing to the cooperation between SP and Fe3O4, the anode exhibited excellent performance for both biodechlorination and power generation. The results indicated that the CF+Fe3O4@SP anode loaded MFC achieved 98.5% removal of 200 mg/L CB within 28 h, and the maximum power density was 675.9 mW/m3, which was a 45.6% increase compared to that of the bare CF anode. Microbial community analysis indicated that the genera Comamonadaceae, Pandoraea, Obscuribacteraceae, and Truepera were dominated, especially, the Comamonadaceae and Obscuribacteraceae showed outstanding affinity for Fe3O4 and SP, respectively. Moreover, the proportion of live bacteria, secretion of extracellular polymer substances, and protein content in the extracellular polymer substances were significantly increased by modifying Fe3O4@SP onto the carbon-based anode. Thus, this study provides new insights into the development of MFCs for refractory and hydrophobic volatile organic compounds removal.