Treatment of contaminated Flowback water in shale gas development

Flowback water from shale gas well drilling has a high TDS (total dissolved solids) content, ranging from 5000 ppm to 261,000 ppm, along with a TSS (total suspended solids) content of 300–3000 mg/L. Recently, the rapid expansion of shale gas production in Marcellus Formation has raised serious environmental concerns about the large amount of flowback water in this area. In this project a process based on ceramic membrane filtration and ion-exchange is optimised for the treatment of the flowback water from Marcellus Formation. Mixed bed ion-exchange will then be employed to reduce the high TDS concentration of flowback water. Finally, a preliminary cost estimation of the proposed treatment process will be conducted. The studied process contains a combination of two MF (microfiltration) membranes. After treatment, all TSS and >99% of TDS should be successfully removed from the flowback water to meet the criteria for surface discharge. The cost estimation of the treatment is expected to be around 18.4 $/m

Characterization of the inessential endomorphisms in the category of Abelian groups

An endomorphism f of an Abelian group A is said to be inessential (in the category of Abelian groups) if it can be extended to an endomorphism of any Abelian group which contains A as a subgroup. In this paper we show that f is as above if and only if (f − v idA)(A) is contained in the maximal divisible subgroup of A for some v ∈ Z

Cloning, Expression, Primary Structure, and Insertion Mutagenesis of the Pyruvate Formate-Lyase Enzyme of Aeromonas Hydrophila.

The pyruvate formate-lyase enzyme (Pfl), a key enzyme in alcoholic fermentation, catalyzes the anaerobic conversion of pyruvate into acetyl-CoA and formate in prokaryotes. The pyruvate formate-lyase gene (pfl) of the facultative anaerobe Aeromonas hydrophila was cloned and sequenced. Subsequently, the Pfl was characterized based on the deduced amino acid sequence and evaluated in vivo following insertion mutagenesis. Finally, the pathogenesis of a defined mutant was compared to wild type A. hydrophila in channel catfish. The pfl of A. hydrophila was identified from two recombinant pBluescript SK(-) clones excised from a $\lambda$ ZAP II phage library. Both clones carried the same 9.15 Kbp insert, oriented in opposite directions, and expressed two polypeptide of 85 & 82 KDa sizes regardless of isopropyl-B-D-thiogalactoside induction. Dideoxy sequencing of a 4.8 Kbp subclone expressing the two immunoreactive polypeptides identified a 2280 base open reading frame (ORF), with 70% sequence homology to the E. coli pfl. The ORF encodes an 85.5 KDa protein containing 760 amino acid residues with 85.5% homology to the E. coli Pfl peptide sequence. The Aeromonas Pfl secondary structure consists of 46% $\alpha$-helices and 39% $\beta$-sheets. Catalytically important adjacent cysteine residues in E. coli Pfl at positions 419-420 were also located at the same positions in the A. hydrophila Pfl. A free radical identified at glycine-735 residue in the cloned enzyme was also in the same position as in E. coli Pfl. A candidate trypsin cleavage site, located between arginine residues at 624-625 positions in A. hydrophila Pfl, was confirmed by the presence of a 68 KDa trypsin resistant fragment. Insertion mutagenesis of the pfl with a kanamycin resistant marker (kan) resulted in isolating an obligate aerobic A. hydrophila pfl mutant strain, which was characterized phenotypically by anaerobic growth on pyruvate and antibiotic resistance profile. Polymerase chain reaction experiments confirmed the insertion of the kan marker into the mutant chromosome and the occurrence of a double-crossover homologous recombination event. No significant difference was noticed in the LD\sb{50} in channel catfish injected with either the parent or the mutant strain, indicating that the Pfl may not play an important role in the pathogenesis of acute A. hydrophila infections