Expanded granular sludge bed bioreactor in wastewater treatment

The expanded granular sludge bed bioreactor appears today as a cheap, robust and more popular technology because it operates using a fluidized bed, which allows increasing in organic load and in cell retention times, generating higher treatment efficiencies (up to 95 %) and renewable energy (i.e., biogas, biomethane, and biohydrogen). Nevertheless, the efficiency of this bioreactor mainly depends on the operating conditions. Thus, the content presented in this review paper focuses on the analysis of the operating conditions and performance of expanded granular sludge bed bioreactor for treating different types of industrial, agro-industrial and domestic wastewaters (e.g., agro-food, beverage, alcohol distillery, tannery, slaughterhouse, chemical, pharmaceutical, municipal sewage, among others). Because of this reason, this study aimed to analyze the operating conditions and type of substrate, which has been used in these bioreactors to improve future research to wastewater treatment and renewable energy production. According to the review, it is concluded that the EGSB bioreactor is a novel sustainable alternative to treat different types of wastewaters and consequently change the paradigm of wastewater management from "treatment and disposal" to "beneficial use" as well as "profitable effort"

Electrochemical and XAS investigation of oxygen reduction reaction on Pt-TiO2-C catalysts

Pt-TiO2-C composites with different titanium oxide loading were synthesized by photo-deposition and chemical vapor deposition methods. The changes in their electronic properties improve the electrochemical activity toward the oxygen reduction reaction (ORR) compared to the Pt-C catalyst synthesized at the same conditions. The platinum samples were physically characterized by means of Transmission Electron Microscopy (TEM), Small Angle X-ray Scattering (SAXS), X-ray Absorption Spectroscopy (XAS) and X-ray Photo-electron Spectroscopy (XPS). Their electrochemical activity was also investigated by cyclic and linear voltammetry techniques. TEM analysis shows homogeneously dispersed platinum nanoparticles with an average particle size of 2 nm in all the synthesized samples. Form factor (morphology model) and particle size were determined by SAXS, the data adjusted to spherical Pt nanoparticles in both synthesis methods. XAS studies at the Pt L-3-edge shows a close interaction of Pt with the support material, i.e. C or TiO2. XPS analysis reveals surface modifications that induce electronic changes on Pt-TiO2-C. Significant differences in the ORR electrochemical activity were correlated to the TiO2 loading and the synthesis procedure. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved