Catalytic Ozonation of Recalcitrant Organic Chemicals in Water Using Vanadium Oxides Loaded ZSM-5 Zeolites

The discharge of wastewater having recalcitrant chemical compositions can have significant and adverse environmental effects. The present study investigates the application of a catalytic ozonation treatment for the removal of recalcitrant organic chemicals (ROCs) from the water. Novel catalytic materials using vanadium (V) oxides deposited onto the surface of NaZSM-5 zeolites (V/ZSM) were found to be highly efficient for this purpose. The highly-dispersed V oxides (V4+ and V5+) and Si-OH-Al framework structures were determined to promote the surface reaction and generation of hydroxyl radicals. The constructed V1/ZSM450 (0.7 wt% of V loading and 450°C of calcination) exhibited the highest activity among the developed catalyst compositions. The V1/ZSM450-COP increased the mineralization rate of nitrobenzene and benzoic acid by 50 and 41% in comparison to single ozonation. This study demonstrates the enhanced potential of V/ZSM catalysts used with catalytic ozonation process (COP) for the treatment of chemical wastewaters

Hydrolysis and acidification of activated sludge from a petroleum refinery

Abstract The cost-effective treatment of activated sludge that is generated by refining petroleum is a challenging industrial problem. In this study, semi-continuous stirred tank reactors (CSTRs) containing petroleum refinery excess activated sludge (PREAS) were used to comparatively investigate hydrolysis and acidification rates, after the addition of heneicosane (C21H44) (R1) and 1-phenylnaphthalene (C16H12) (R2) to different and individual reactors. Operation of the reactors using a sludge retention time (SRT) of 6 days and a pH of 5.0, resulted in the maintenance of stable biological activity as determined by soluble chemical oxygen demand (SCOD), volatile fatty acids (VFAs) production and oil removal efficiency. The optimum conditions for hydrogen production include a SRT of 8 days, at pH 6.5. Under these conditions, hydrogen production rates in the control containing only PREAS were 1567 mL/L (R0), compared with 1365 mL/L in R1 and 1454 mL/L-PREAS in R2. Coprothermobacter, Fervidobacterium, Caldisericum and Tepidiphilus were the dominant bacterial genera that have the potential to degrade petroleum compounds and generate VFAs. This study has shown that high concentrations of heneicosane and 1-phenylnaphthalene did not inhibit the hydrolytic acidification of PREAS

Comparison of Efficiencies and Mechanisms of Catalytic Ozonation of Recalcitrant Petroleum Refinery Wastewater by Ce, Mg, and Ce-Mg Oxides Loaded Al2O3

The use of catalytic ozonation processes (COPs) for the advanced treatment of recalcitrant petroleum refinery wastewater (RPRW) is rapidly expanding. In this study, magnesium (Mg), cerium (Ce), and Mg-Ce oxide-loaded alumina (Al2O3) were developed as cost efficient catalysts for ozonation treatment of RPRW, having performance metrics that meet new discharge standards. Interactions between the metal oxides and the Al2O3 support influence the catalytic properties, as well as the efficiency and mechanism. Mg-Ce/Al2O3 (Mg-Ce/Al2O3-COP) reduced the chemical oxygen demand by 4.7%, 4.1%, 6.0%, and 17.5% relative to Mg/Al2O3-COP, Ce/Al2O3-COP, Al2O3-COP, and single ozonation, respectively. The loaded composite metal oxides significantly increased the hydroxyl radical-mediated oxidation. Surface hydroxyl groups (–OHs) are the dominant catalytic active sites on Al2O3. These active surface –OHs along with the deposited metal oxides (Mg2+ and/or Ce4+) increased the catalytic activity. The Mg-Ce/Al2O3 catalyst can be economically produced, has high efficiency, and is stable under acidic and alkaline conditions

Efficient ozonation of reverse osmosis concentrates from petroleum refinery wastewater using composite metal oxide-loaded alumina

Abstract Novel Mn–Fe–Mg- and Mn–Fe–Ce-loaded alumina (Mn–Fe–Mg/Al2O3 and Mn–Fe–Ce/Al2O3) were developed to catalytically ozonate reverse osmosis concentrates generated from petroleum refinery wastewaters (PRW-ROC). Highly dispersed 100–300-nm deposits of composite multivalent metal oxides of Mn (Mn2+, Mn3+, and Mn4+), Fe (Fe2+ and Fe3+) and Mg (Mg2+), or Ce (Ce4+) were achieved on Al2O3 supports. The developed Mn–Fe–Mg/Al2O3 and Mn–Fe–Ce/Al2O3 exhibited higher catalytic activity during the ozonation of PRW-ROC than Mn–Fe/Al2O3, Mn/Al2O3, Fe/Al2O3, and Al2O3. Chemical oxygen demand removal by Mn–Fe–Mg/Al2O3- or Mn–Fe–Ce/Al2O3-catalyzed ozonation increased by 23.9% and 23.2%, respectively, in comparison with single ozonation. Mn–Fe–Mg/Al2O3 and Mn–Fe–Ce/Al2O3 notably promoted ·OH generation and ·OH-mediated oxidation. This study demonstrated the potential use of composite metal oxide-loaded Al2O3 in advanced treatment of bio-recalcitrant wastewaters

The first complete mitochondrial genome sequence of the korean endemic catfish Silurus microdorsalis (Actinopteri, Siluriformes, Siluridae)

The Silurus microdorsalis is known as Korean endemic slender catfish. Despite its value as a biological resource, there is no complete mitochondrial genome sequence. The complete mitochondrial genome consisted of 16,524 bp including 22 transfer RNA (tRNAs), 2 ribosomal RNA (rRNAs), 13 protein-coding genes (PCGs), and A + T rich region. The overall base composition of S. microdorsalis was A + T: 56.1%, C + G: 43.9%, apparently with slight AT bias. Phylogenetic relationship showed that S. microdorsalis was closely related to Silurus glanis