This study developed Fe3O4@cellulose nanocomposites by co-precipitation synthesis for bacteria capture and isolation. By surface modification with cellulose, the Fe3O4@cellulose nanocomposites have 20 nm average particle size and 3.3–24.9 emu/g saturation magnetization. Living bacteria could be captured by the Fe3O4@cellulose nanocomposites and harvested by magnetic field, with high efficiency (95.1%) and stability (>99.99%). By metabolizing cellulose and destroying the Fe3O4@cellulose@bacteria complex, cellulose-decomposing microorganisms lost the magnetism. They were therefore able to be isolated from the inert microbial community and the separation efficiency achieved over 99.2%. This research opened a door to cultivate the uncultivable cellulose-decomposing microorganisms in situ and further characterize their ecological functions in natural environment
2 May 2017 in Archives of Environmental Contamination and Toxicology
Antibiotic residues and antibiotic resistance genes (ARGs) pose a great threat to public health and food security via the horizontal transfer in the food production chain. Oxidative degradation of amoxicillin (AMO) in aqueous solution by thermally activated persulfate (TAP) was investigated. The AMO degradation followed a pseudo-first-order kinetic model at all tested conditions. The pseudo-first-order rate constants of AMO degradation well-fitted the Arrhenius equation when the reaction temperature ranged from 35°C to 60°C, with the apparent activate energy of 126.9 kJ·mol−1. High reaction temperature, high initial persulfate concentration, low pH, high Cl− concentration, and humic acid (HA) concentration increased the AMO degradation efficiency. The EPR test demonstrated that both ·OH and SO4·− were generated in the TAP system, and the radical scavenging test identified that the predominant reactive radical species were SO4·− in aqueous solution without adjusting the solution pH. In groundwater and drinking water, AMO degradation suggested that TAP could be a reliable technology for water remediation contaminated by AMO in practice.
In recent years, the effect of formaldehyde on microorganisms and body had become a global public health issue. The multistage combination of anaerobic and aerobic process was adopted to treat paraformaldehyde wastewater. Microbial community structure in different reaction stages was analyzed through high-throughput sequencing. Results showed that multistage A-O activated sludge process positively influenced polyformaldehyde wastewater. The removal rates of formaldehyde were basically stable at more than 99% and those of COD were about 89%. Analysis of the microbial diversity index indicated that the microbial diversity of the reactor was high, and the treatment effect was good. Moreover, microbial community had certain similarity in the same system. Microbial communities in different units also showed typical representative characteristics affected by working conditions and influent concentrations. Proteobacteria, Firmicutes, and Bacteroidetes were the dominant fungal genera in the phylum level of community composition. As to family and genus levels, Peptostreptococcaceae was distributed at various stages and the dominant in this system. This bacterium also played an important role in organic matter removal, particularly decomposition of the acidified middle metabolites. In addition, Rhodobacteraceae and Rhodocyclaceae were the formaldehyde-degrading bacteria found in the reactor.
Using reclaimed water as a resource for landscape water replenishment may alleviate the major problems of water resource shortages and water environment pollution. However, the safety of the reclaimed water and the risk of eutrophication caused by the reclaimed water replenishment are unclear to the public and to the research community. This study aimed to reveal the differences between natural water and reclaimed water and to discuss the rationality of reclaimed water replenishment from the perspective of microorganisms. The microbial community structures in natural water, reclaimed water and natural biofilms were analyzed, and the community succession was clarified along the ecological niches, water resources, fluidity and time using 16S rRNA gene amplicon sequencing. Primary biofilms without the original community were added to study the formation of microbial community structures under reclaimed water acclimation. The results showed that the difference caused by ecological niches was more than those caused by the fluidity of water and different water resources. No significant difference caused by the addition of reclaimed water was found in the microbial diversity and community structure. Based on the results of microbial analysis, reclaimed water replenishment is a feasible solution that can be used for supplying river water.