Effects of azo dye on simultaneous biological removal of azo dye and nutrients in wastewater.

The potential disrupting effects of Azo dye on wastewater nutrients removal deserved more analysis. In this study, 15 days exposure experiments were conducted with alizarin yellow R (AYR) as a model dye to determine whether the dye caused adverse effects on biological removal of both the dye and nutrients in acclimated anaerobic-aerobic-anoxic sequencing batch reactors. The results showed that the AYR removal efficiency was, respectively, 85.7% and 66.8% at AYR concentrations of 50 and 200 mg l-1, while higher AYR inlet (400 mg l-1) might inactivate sludge. Lower removal of AYR at 200 mg l-1 of AYR was due to the insufficient support of electron donors in the anaerobic process. However, the decolorized by-products p-phenylenediamine and 5-aminosalicylic were completely decomposed in the following aerobic stage at both 50 and 200 mg l-1 of AYR concentrations. Compared with the absence of AYR, the presence of 200 mg l-1 of AYR decreased the total nitrogen removal efficiency from 82.4 to 41.1%, and chemical oxygen demand (COD) removal efficiency initially decreased to 68.1% and then returned to around 83.4% in the long-term exposure time. It was also found that the inhibition of AYR, nitrogen and COD removal induced by a higher concentration of AYR was due to the increased intracellular reactive oxygen species production, which caused the rise of oxidation-reduction potential value and decreased ammonia monooxygenase and nitrite oxidoreductase activities.

Enhanced bio-hydrogen production from protein wastewater by altering protein structure and amino acids acidification type.

Enhanced bio-hydrogen production from protein wastewater by altering protein structure and amino acids acidification type via pH control was investigated. The hydrogen production reached 205.2 mL/g-protein when protein wastewater was pretreated at pH 12 and then fermented at pH 10. The mechanism studies showed that pH 12 pretreatment significantly enhanced protein bio-hydrolysis during the subsequent fermentation stage as it caused the unfolding of protein, damaged the protein hydrogen bonding networks, and destroyed the disulfide bridges, which increased the susceptibility of protein to protease. Moreover, pH 10 fermentation produced more acetic but less propionic acid during the anaerobic fermentation of amino acids, which was consistent with the theory of fermentation type affecting hydrogen production. Further analyses of the critical enzymes, genes, and microorganisms indicated that the activity and abundance of hydrogen producing bacteria in the pH 10 fermentation reactor were greater than those in the control.

Complete mitochondrial genome of the double-striped cockroach Blattella bisignata (Insecta: Blattaria: Blaberoidea).

In this work, we sequenced the complete mitochondrial genome of Blaberoidea species, Blattella bisignata. The circle genome (16,470 bp) consists of 13 protein-coding, 22 tRNA, and 2 rRNA genes, and an A+T-rich region. The A+T-rich region, which contains five long repeat sequences, is located between the small rRNA and tRNA(Ile) and is 1705 bp in length.

Complete mitochondrial genomes of two cockroaches, Blattella germanica and Periplaneta americana, and the phylogenetic position of termites.

The mitochondrial genomes are one of the most information-rich markers in phylogenetics. The relationships within superorder Dictyoptera have been debated in the literature. However, the closely related termites (Isoptera) are retained as unranked taxon within the order Blattaria (cockroaches). In this work, we sequenced the complete mitogenomes of two cockroaches, reconstructed the molecular phylogeny and attempted to infer the phylogenetic position of termites in Blattaria more reliably. The complete mtDNA nucleotide sequences of the peridomestic American cockroach (Periplaneta americana L.) and the domestic German cockroach (Blattella germanica L.) are 15,025 and 15,584 bp in size, respectively. The genome shares the gene order and orientation with previously known Blattaria mitogenomes. Most tRNAs could be folded into the typical cloverleaf secondary structure, but the tRNA-Ser (AGN) of P. americana appears to be missing the dihydrouridine arm. Using nucleotide and amino acid sequences as phylogenetic markers, we proposed that termites should be treated as a superfamily (Termitoidea) of cockroaches. We suggested that Polyphagoidea was the sister group of Termitoidea in Blattaria and supported that the suborder Caelifera is more closely related to the Phasmatodea than to the suborder Ensifera of Orthoptera.

Bis(1,3-diethyl-benzimidazolium) tetra-bromidomercurate(II).

In the title compound, (C(11)H(15)N(2))(2)[HgBr(4)], the tetra-coordinated Hg(II) center of the complex anion adopts a distorted tetra-hedral geometry [Hg-Br = 2.5755 (8)-2.623 (11) Šand Br-Hg-Br = 103.78 (19)-116.4 (3)°]. One of the Br atoms is disordered over two sites [site-occupancy factors = 0.51 (6) and 0.49 (6)]. The N-C-N angles in the cations are 110.7 (6) and 111.4 (7)°. In the crystal packing, a supra-molecular chain is formed via both weak inter-molecular C-H⋯Br hydrogen bonds and π-π aromatic ring stacking inter-actions [centroid-centroid separation = 3.803 (1) Å].