Improved methane elimination by methane-oxidizing bacteria immobilized on modified oil shale semicoke

Synthesis of semicoke-based geopolymers as delivery vehicles for slow release of herbicides

A novel carrier of semicoke-based geopolymer was prepared and applied for site-specific targeted release and recycling of herbicides.

Electrospun nanofibers enhance trehalose synthesis by regulating gene expression for Micrococcus luteus fermentation

In this study, mesoporous polyacrylonitrile (PAN)/thermoplastic polyurethane (TPU) blended nanofibers were prepared to immobilize Micrococcus luteus for enhancing the conversion of trehalose. The images of SEM showed the cells were adsorbed on the surface and pores due to the unique pore structure. The results of contact angle, Zeta potential and water holding ratio exhibited the good hydrophilicity and stability of PAN/TPU-P2. Besides, it was indicated that the biomass and immobilization efficiency were increased to 0.633 g/L and 0.153 g/g, respectively. It was the most noteworthy that the trehalose yield could reach 23.46 g/L, which was 71.62 % higher than that of the control in the multi-batch fermentation. Moreover, the reactive oxygen species (ROS) level was decreased to 12.8 % while the enzyme concentration was increased to 11.176 mg/mL. Meanwhile, it was also found that PAN/TPU-P2 immobilization substantially increased the expression of target gene MtreY by 3.500 times. In other words, the mechanism by which immobilized cells increased trehalose yield was that PAN/TPU-P regulated gene expression of MtreY. Therefore, this research provided theoretical foundation for the metabolic regulation of sufficient trehalose production by immobilized cells.

Methane-fueled microbial fuel cells with the formate-acclimating electroactive culture

Methane gas is widespread in natural environments and anaerobic wastewater treatment sites, bringing the risk of the greenhouse effect and energy loss if left unmanaged. A methane-fueled microbial fuel cell (MFC) can convert methane to electricity under mild condition, but faced difficulties in startup. In this study, the new startup strategy and operation performance for methane-fueled MFCs were investigated. After the pre-cultivation of formate-acclimating electroactive culture, the methane-fueled MFC was successfully started up in a short time of 53 d. Increasing concentrations of molybdenum and tungsten in medium facilitated both methane consumption and electricity generation. Under the optimal condition (batch duration of 11 h, 30 °C, pH 7 buffered by phosphate buffer solution), the methane-fueled MFC achieved the maximum power density of 166 mW/m³, a coulomb production of 6.58 ± 0.07C/batch, a CE of 27.4 ± 0.4% and a methane consumption of 31.2 ± 0.3 μmol/batch. This work explored a suitable inoculum (formate-acclimating electroactive culture) for methane-fueled MFCs.

Remediation with Semicoke-Preparation, Characterization, and Adsorption Application

Development of low-cost contaminant sorbents from industrial waste is now an essential aspect of the circular economy since their disposal continues to threaten ecological integrity. Semicoke (SC), a by-product generated in large quantities and described as solid waste from gasification of low-rank coal (LRC), is gaining popularity in line with its reuse capacity in the energy industry but is less explored as a contaminant adsorbent despite its physical and elemental carbon properties. This paper summarizes recent information on SC, sources and production, adsorption mechanism of polluting contaminants, and summarizes regeneration methods capable of yielding sustainability for the material reuse.

Methane Elimination Using Biofiltration Packed With Fly Ash Ceramsite as Support Material

Methane is a greenhouse gas and significantly contributes to global warming. Methane biofiltration with immobilized methane-oxidizing bacteria (MOB) is an efficient and eco-friendly approach for methane elimination. To achieve high methane elimination capacity (EC), it is necessary to use an exceptional support material to immobilize MOB. The MOB consortium was inoculated in biofilters to continuusly eliminate 1% (v/v) of methane. Results showed that the immobilized MOB cells outperformed than the suspended MOB cells. The biofilter packed with fly ash ceramsite (FAC) held the highest average methane EC of 4.628 g h^–1 m^–3, which was 33.4% higher than that of the biofilter with the suspended MOB cells. The qPCR revealed that FAC surface presented the highest pmoA gene abundance, which inferred that FAC surface immobilized the most MOB biomass. The XPS and contact angle measurement indicated that the desirable surface elemental composition and stronger surface hydrophilicity of FAC might favor MOB immobilization and accordingly improve methane elimination.