Efficient Mn(II) removal mechanism by Serratia marcescens QZB-1 at high manganese concentration

Manganese (Mn(II)) pollution has recently increased and requires efficient remediation. In this study, Serratia marcescens QZB-1, isolated from acidic red soil, exhibited high tolerance against Mn(II) (up to 364 mM). Strain QZB-1 removed a total of 98.4% of 18 mM Mn(II), with an adsorption rate of 71.4% and oxidation rate of 28.6% after incubation for 48 h. The strain synthesized more protein (PN) to absorb Mn(II) when stimulated with Mn(II). The pH value of the cultural medium continuously increased during the Mn(II) removal process. The product crystal composition (mainly MnO2 and MnCO3), Mn-O functional group, and element-level fluctuations confirmed Mn oxidation. Overall, strain QZB-1 efficiently removed high concentration of Mn(II) mainly via adsorption and showed great potential for manganese wastewater removal

Doping silver nanoparticles into reverse osmosis membranes for antibacterial properties

Polyamide composite reverse osmosis (RO) membranes occupy an important position in water treatment. However, membrane fouling, especially biofouling, can lead to a significant decrease in membrane permeability. Therefore, reducing biological contamination is a significant and important property of an RO membrane. In this article, a hypothesis on the development of a new kind of RO membrane for antibacterial purposes was prepared by the modification of gallic acid (GA) and silver nanoparticles (AgNPs). Then, experiments were carried out to verify the hypothesis, getting a modified RO membrane with the composite of GA@AgNPs. The water flux of the GA@AgNPs RO membrane was 31.1 L·m−2·h−1, which was 46.7% higher than that of the original membrane, while the rejection rate of salt remained at 93.8–97.6%. Moreover, the GA@AgNPs RO membranes exhibited outstanding antibacterial properties with more than 99.9% antibacterial efficiency against both Escherichia coli and Staphylococcus aureus. Our work provides a new idea for solving the problem of biofouling RO membranes