Dual function filtration and catalytic breakdown of organic pollutants in wastewater using ozonation with titania and alumina membranes

Water recycling via treatment from industrial and/or municipal waste sources is one of the key strategies for resolving water shortages worldwide. Polymer membranes are effective at improving the water quality essential for recycling, but depend on regular cleaning and replacement. Pure ceramic membranes can reduce the cleaning need and last significantly longer in the same applications while possessing the possibility of operating in more aggressive environments not suitable for polymers. In the current work, filtration using a tubular ceramic membrane (�-Al2O3 or TiO2) was combined with ozonation to remove organic compounds present in a secondary effluent to enhance key quality features of the water (colour and total organic carbon, TOC) for its potential reuse. ‘Bare’ commercial �-Al2O3 filters (pore size ∼0.58 �m) were tested as a microfiltration membrane and compared with the more advanced catalytically active TiO2 layer that was formed by the sol–gel method. The presence of anatase with a 4 nm pore size at the membrane surface was confirmed by X-ray diffraction (XRD) and N2 adsorption. Filtration of the effluent over a 2 h period led to a reduction in flux to 45% and 60% of the initial values for the �-alumina and TiO2 membrane, respectively. However, a brief dose (2 min) of ozone at the start of the run resulted in reductions to only 70% of the initial flux for both membranes. It is likely that the oxide’s functional property facilitated the formation of hydroxyl (OH•) or other radicals on the membrane surface from ozone decomposition which targeted the breakdown of organic foulants thus inhibiting their deposition. Interestingly, the porous structure therefore acted in a synergistic, dual function mode to physically separate the particulates while also catalytically breaking down organic matter. The system also greatly improved the efficiency of membrane filtration for the reduction of colour, A254 (organics absorption at the wavelength of 254 nm) and TOC. The best performance came from combined ozonation (2 min ozonation time with an estimated applied ozone dose of 8 mg L−1) with the TiO2 membrane, which was able to reduce colour by 88%, A254 by 75% and TOC by 43%. It is clearly evident that a synergistic effect occurs with the process combination of ozonation and ceramic membrane filtration demonstrating the practical benefit of combining ceramic membrane filtration with conventional water ozonation

Poverty in the Social World of the Wise

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68560/2/10.1177_030908928701203704.pd

Silicic conduits as supersized tuffisites:Clastogenic influences on shifting eruption styles at Cordón Caulle volcano (Chile)

Understanding the processes that drive explosive-effusive transitions during large silicic eruptions is crucial to hazard mitigation. Conduit models usually treat magma ascent and degassing as a gradual, unidirectional progression from bubble nucleation through magmatic fragmentation. However, there is growing evidence for the importance of bi-directional clastogenic processes that sinter fragmented materials into coherent clastogenic magmas. Bombs that were ejected immediately before the first emergence of lava in the 2011–2012 eruption at Cordón Caulle volcano (Chile) are texturally heterogeneous composite assemblages of welded pyroclastic material. Although diverse in density and appearance, SEM and X-ray tomographic analysis show them all to have been formed by multi-generational viscous sintering of fine ash. Sintering created discrete clasts ranging from obsidian to pumice and formed a pervasive clast-supporting matrix that assembled these clasts into a conduit-sealing plug. An evaluation of sintering timescales reveals texturally disparate bomb components to represent only minutes of difference in residence time within the conduit. Permeability modelling indicates that the plug was an effective conduit seal, with outgassing potential—even from high-porosity regions—being limited by the inability of gas to flow across tendrils of densely sintered inter-clast matrix. Contrary to traditional perspectives, declining expressions of explosivity at the surface need not be preceded or accompanied by a decline in fragmentation efficiency. Instead, they result from tips in balance between the opposing processes of fragmentation and sintering that occur in countless cycles within volcanic conduits. These processes may be particularly enhanced at silicic fissure volcanoes, which have laterally extensive subsurface plumbing systems that require complex magma ascent pathways. The textures investigated here reveal the processes occurring within silicic fissures to be phenomenologically identical to those that have been inferred to occur in tuffisite veins: silicic conduits are essentially supersized examples of edifice-penetrating tuffisites

The PHENIX Experiment at RHIC

The physics emphases of the PHENIX collaboration and the design and current status of the PHENIX detector are discussed. The plan of the collaboration for making the most effective use of the available luminosity in the first years of RHIC operation is also presented.Comment: 5 pages, 1 figure. Further details of the PHENIX physics program available at http://www.rhic.bnl.gov/phenix

Correction to: Silicic conduits as supersized tuffisites: Clastogenic influences on shifting eruption styles at Cordón Caulle volcano (Chile) (Bulletin of Volcanology, (2021), 83, 2, (11), 10.1007/s00445-020-01432-1)

The original version of this article unfortunately contained a mistake. The presentation of Table 1 was incorrect. The corrected table is given below. © 2021, International Association of Volcanology & Chemistry of the Earth's Interior