Selective Wettability Membrane for Continuous Oil−Water Separation and In Situ Visible Light-Driven Photocatalytic Purification of Water

Membrane-based technologies are attractive for remediating oily wastewater because they are relatively energy-efficient and are applicable to a wide range of industrial effluents. For complete treatment of oily wastewater, removing dissolved contaminants from the water phase is typically followed by adsorption onto an adsorbent, which complicates the process. Here, an in-air superhydrophilic and underwater superoleophobic membrane-based continuous separation of surfactant-stabilized oil-in-water emulsions and in situ decontamination of water by visible-light-driven photocatalytic degradation of dissolved organic contaminants is reported. The membrane is fabricated by utilizing a thermally sensitized stainless steel mesh coated with visible light absorbing iron-doped titania nanoparticles. Post annealing of the membrane can enhance the adhesion of nanoparticles to the membrane surface by formation of a bridge between them. An apparatus that enables continuous separation of surfactant-stabilized oil-in-water emulsion and in situ photocatalytic degradation of dissolved organic matter in the water-rich permeate upon irradiation of visible light on the membrane surface with greater than 99% photocatalytic degradation is developed. The membrane demonstrates the recovery of its intrinsic water-rich permeate flux upon continuous irradiation of light after being contaminated with oil. Finally, continuous oil−water separation and in situ water decontamination is demonstrated by photocatalytically degrading model toxins in water-rich permeate

Cefotaxime Resistant Bacteria Isolated from a Wastewater Treatment Plant

The most common type of antibiotics prescribed in the U.S. and worldwide for clinical infections are beta lactams. It is estimated that 28 million pounds of antibiotics a year are consumed in the U.S. with approximate equal usage between agriculture and medicine. Some percentage of an antibiotic dose given to a patient leaves the body unaltered, is disseminated, and can persist in the environment, putting selection pressure on populations of bacteria for antibiotic resistance. Bacteria that are able to survive exposure to an antibiotic will be able to reproduce, passing resistance to future generations. Also, bacteria that have resistance genes located on transferable plasmids can pass this resistance to other bacteria via horizontal gene transfer. This transfer of resistance genes might pose a significant threat to the medical community if non-resistant human pathogens acquire resistance from other bacteria and then limit the options of treating a patient\u27s infection. Some bacteria have evolved a way to combat beta-Iactam antibiotics by producing beta-Iactamase enzymes that render the antibiotics useless. These extended spectrum beta-Iactamases (ESBLs) confer resistance to bacteria able to produce them. Most of the study of beta-Iactamase production has focused on clinical infections. Limited study has been done with beta-Iactamase producing bacteria isolated from human sewage. / To study the production of extended spectrum beta-lactamases (ESBLs) in bacteria from human sewage, I screened wastewater influent from the Hays, Ellis County, KS wastewater treatment plant on Mueller-Hinton Agar embedded with 50 microgram/milliliter cefotaxime. Cefotaxime was used due to its broad spectrum of activity against bacteria and also because it is a relatively “new class of cephalosporin. I also screened the bacteria on MacConkey Agar, which is differential for lactose fermentation and selective for gram negative bacteria. Because gram positive bacteria are not thought to produce ESBLs, I limited this study to gram negative bacteria. I performed double disc diffusion assays and E-tests to look for the presence of extended spectrum beta lactamases (ESBLs). An isolate of Escherichia coli serotype 0157:117 was found to produce an ESBL, which conferred resistance to cefotaxime. In addition to resistance assays I viewed and photographed two of my isolates under a Scanning Electron Microscope (SEM). / The clinical implications of the overuse of all antibiotics had become apparent with the spread of multiple resistant Staphylococcus aureus (MRSA), and Escherichia coli O 157:H7. As newer classes of ESBLs evolve, the resistance problem only increases. Pathogenic species of bacteria have been able to pick up and transfer resistance genes, limiting therapeutic options for patients with infections. Adding to this problem is that non-pathogenic species of bacteria can act as resistance gene reservoirs , harboring plasmids that can be exchanged with previously non-resistance species of bacteria. Without the prudent use of antibiotics, resistance will become an increasingly complex medical problem worldwide

Selective Wettability Membrane for Continuous Oil−Water Separation and In Situ Visible Light‐Driven Photocatalytic Purification of Water

Membrane-based technologies are attractive for remediating oily wastewater because they are relatively energy-efficient and are applicable to a wide range of industrial effluents. For complete treatment of oily wastewater, removing dissolved contaminants from the water phase is typically followed by adsorption onto an adsorbent, which complicates the process. Here, an in-air superhydrophilic and underwater superoleophobic membrane-based continuous separation of surfactant-stabilized oil-in-water emulsions and in situ decontamination of water by visible-light-driven photocatalytic degradation of dissolved organic contaminants is reported. The membrane is fabricated by utilizing a thermally sensitized stainless steel mesh coated with visible light absorbing iron-doped titania nanoparticles. Post annealing of the membrane can enhance the adhesion of nanoparticles to the membrane surface by formation of a bridge between them. An apparatus that enables continuous separation of surfactant-stabilized oil-in-water emulsion and in situ photocatalytic degradation of dissolved organic matter in the water-rich permeate upon irradiation of visible light on the membrane surface with greater than 99% photocatalytic degradation is developed. The membrane demonstrates the recovery of its intrinsic water-rich permeate flux upon continuous irradiation of light after being contaminated with oil. Finally, continuous oil−water separation and in situ water decontamination is demonstrated by photocatalytically degrading model toxins in water-rich permeate