Occurrence, characteristics, and microbial community of microplastics in anaerobic sludge of wastewater treatment plants.

Wastewater treatment plants (WWTPs) usually contain microplastics (MPs) due to daily influents of domestic and municipal wastewater. Thus, the WWTPs act as a point source of MPs distribution in the environment due to their incapability to remove MPs completely. In this study, MPs occurrence and distribution in anaerobic sludge from WWTPs in different regions (Kaifeng "KHP", Jinan "JSP", and Lanzhou "LGP") were studied. Followed by MPs identification by microscopy and Fourier transform infrared (FTIR) spectrum. The microbial communities associated with anaerobic sludge and MPs were also explored. The results showed that MPs concentrations were 16.5, 38.5, and 17.2 particles/g of total solids (TS) and transparent MPs accounted for 49.1%, 58.5%, and 48.3% in KHP, JSP, and LGP samples, respectively. Fibers represented the most common shape of MPs in KHP (49.1%), JSP (56.0%), and LGP (69.0%). The FTIR spectroscopy indicated the predominance of polyethylene polymer in 1-5 mm MPs. The Proteobacteria, Chloroflexi, Actinobacteria, Bacteroidetes, and Planctomycetes were the abundant phyla in all anaerobic sludge. The bacterial genera in KHP and LGP were similar, in which Caldilinea (>23%), Terrimonas (>10%), and Ferruginibacter (>7%) formed the core bacterial genera. While Rhodococcus (15.3%) and Rhodoplanes (10.9%) were dominating in JSP. The archaeal genera Methanosaeta (>69%) and Methanobrevibacter (>10%) were abundant in KHP and LGP sludge. While Methanomethylovorans accounted for 90% of JSP. Acetyltransferase and hydratase were the major bacterial enzymes, while reductase was the key archaeal enzyme in all anaerobic sludge. This study provided the baseline for MPs distribution, characterization, and MPs associated microbes in WWTPs.

Stable Trimetallic NiFeCu Catalysts with High Carbon Resistance for Dry Reforming of Methane.

Copper has been incorporated into Ni-Fe alloys to form a series of ternary NiFeCu alloy catalysts with molar ratio of Cu/Fe varying from 0 to 1.5, which were tested in dry reforming of methane (DRM) at 923 K and atmospheric pressure with a CH4 /CO2 ratio of 1. XRD, TPR-H2 and FE-TEM measurements confirm the formation of Ni-Fe-Cu alloys with particle size of 5.0-5.7 nm. The Ni3 Fe1 Cu1 -Mgx Aly Oz (2.6 wt% Cu) shows the highest carbon resistance with only 5.0 % carbon by thermogravimetric analysis. Importantly, XPS analyses complemented with XAFS demonstrate that doping an appropriate quantity of Cu to form stable trimetallic alloy enhances the interaction between Ni and Fe, thus inhibiting Fe segregation and reducing carbon deposition. However, doping excessive Cu (3.9 wt%) weakens the Ni-Fe bond, preventing Fe from providing labile oxygen to Ni sites, which is unfavorable for carbon elimination.

Enhancing bacterial transport with saponins in saturated porous media for the bioaugmentation of groundwater: visual investigation and surface interactions.

The success of bioaugmentation processes for the remediation of groundwater contamination relies on effective transport of the injected microorganisms in a subsurface environment. Biosurfactants potentially affect bacterial attachment and transport behavior in porous media. Although saponins as biosurfactants are abundant in nature, their influence on bacterial transport in groundwater systems remains unknown. In this research, tank visual-transport experiments, breakthrough curve monitoring, and surface property measurement were performed to evaluate the effects of saponins on the transport of Pseudomonas migulae AN-1 cells, which were used as a model bacterium in saturated sand. Results show that the 0.1% saponins could effectively facilitated the AN-1 secondary transport and the addition of saponins decreased the hydrophobicity of AN-1 and sand. The role of the promotion of saponins was more dominant than that of the inhibition of ions on AN-1 transport in a saturated porous medium when ions and saponins coexisted. The interactions between AN-1 and sand grains with saponins and ions were explained in accordance with the Derjaguin-Landau-Verwey-Overbeek theory.