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Qian, Jin et al (2018), A novel integrated thiosulfate-driven denitritation (TDD) and anaerobic ammonia oxidation (anammox) process for biological nitrogen removal, Biochemical Engineering Journal, vol. 139, 68 - 73
A novel integrated thiosulfate-driven denitritation (TDD) and anaerobic ammonia oxidation (anammox) process for biological nitrogen removalQian, Jin, Zhang, Mingkuan, Pei, Xiangjun, Zhang, Zhen, Niu, Juntao, Liu, Yu (2018), Biochemical Engineering Journal, vol. 139, 68 - 73
An integrated system by combining the thiosulfate-driven denitritation (TDD) and anaerobic ammonia oxidation (anammox) was established for high-rate biological nitrogen removal (BNR) and less N2O generation under 35 °C. The anammox contribute to 27% nitrogen removal in the system. The anammox activity was enhanced by four times as temperature increased from 20 to 35 °C. The less N2O emission at 35 °C compared with that at 20 °C is attributed to the involvement of anammox (characterized as no N2O generation) function rather than higher N2O reducing rate under the thermophilic condition. The produced NO3?in anammox can be readily reduced by thiosulfate. The results of this study could enlighten us how to induce a high nitrogen degradation activity with lower sludge yield, in the meanwhile to minimize the greenhouse gas emission and the nitrogenous residues in the BNR process.
Qiao, Jian et al (2018), Experimental and computational studies of oxygen transport in a Taylor-Couette bioreactor, Chemical Engineering Journal, vol. 334, 1954 - 1964
Experimental and computational studies of oxygen transport in a Taylor-Couette bioreactorQiao, Jian, Yan, Wei Cheng, Teoh, Jia Heng, Tong, Yen Wah, Wang, Chi Hwa (2018), Chemical Engineering Journal, vol. 334, 1954 - 1964
With research and development for almost one century, the Taylor-Couette device is now applied in many practical applications such as reaction, filtration, extraction and bioreactor. We intend to use the Taylor-Couette bioreactor to culture cells that are seeded in a biodegradable porous scaffold. Oxygen concentration is always the most significant constraint in a bioreactor and can limit the cell proliferation rate. It is therefore important to know the mass transfer phenomenon and oxygen transport pattern inside the system. In this study, the equilibrium oxygen concentrations at different Reynolds numbers and operation conditions were measured and the mass transfer coefficients were also calculated. CFD simulation was carried out to compare with the experimental results. Both experimental and simulation results showed that the equilibrium oxygen concentration and mass transfer coefficient increased with Reynolds number. To further improve the mass transfer efficiency, air bubble was introduced to the bottom of the rotating inner cylinder and the vortex center. It was shown that the mass transfer coefficient of oxygen could be significantly increased with the trapped bubble.
Qin, H. et al (2018), Vertical distribution and community composition of anammox bacteria in sediments of a eutrophic shallow lake, Journal of Applied Microbiology, vol. 125, 121 - 132
Vertical distribution and community composition of anammox bacteria in sediments of a eutrophic shallow lakeQin, H., Han, C., Jin, Z., Wu, L., Deng, H., Zhu, G., Zhong, W. (2018), Journal of Applied Microbiology, vol. 125, 121 - 132
AimsThe aim of this study was to explore the vertical distribution traits of anaerobic ammonium-oxidizing (anammox) bacterial relative abundance and community composition along the oxic/anoxic sediment profiles in a shallow lake. Methods and ResultsThe Illumina Miseq-based sequencing and quantitative polymerase chain reactions were utilized to analyse relative abundance of anammox hydrazine synthase (hzsB) gene in comparison with bacterial 16S rRNA genes, anammox bacterial relative abundance (the number of anammox sequences divided by total number of sequences), community composition and diversity in sediments. The relative abundance of hzsB gene at the low-nitrogen (LN) site in the lake sediments showed that the vertical distribution of anammox bacteria increased to a peak, then decreased with increasing depth. Moreover, the relative abundance of hzsB gene at the high-nitrogen site was significantly lower than that at the LN site. Additionally, the community composition results showed that Candidatus Brocadia sp. was the dominant genus. In addition, the anammox bacterial diversity was also site specific. Redundancy analysis showed that the total N and the NH4+-N content might be the most important factors affecting anammox bacterial community composition in the studied sites. ConclusionsThe results revealed the specific vertical variance of anammox bacterial distribution and community composition in oxic/anoxic sediments of a eutrophic shallow lake. Significance and Impact of the StudyThis is the first study to demonstrate that anammox bacteria displayed the particular distribution in freshwater sediments, which implied a strong response to the anthropogenic eutrophication.
Qu, K. et al (2008), Hydrogen sulfide: Neurochemistry and neurobiology, Neurochemistry International, vol. 52, 155 - 165
Hydrogen sulfide: Neurochemistry and neurobiologyQu, K., Lee, S. W., Bian, J. S., Low, C. M., Wong, P. T.H. (2008), Neurochemistry International, vol. 52, 155 - 165
Current evidence suggests that hydrogen sulfide (H2S) plays an important role in brain functions, probably acting as a neuromodulator as well as an intracellular messenger. In the mammalian CNS, H2S is formed from the amino acid cysteine by the action of cystathionine ?-synthase (CBS) with serine (Ser) as the by-product. As CBS is a calcium and calmodulin dependent enzyme, the biosynthesis of H2S should be acutely controlled by the intracellular concentration of calcium. In addition, it is also regulated by S-adenosylmethionine which acts as an allosteric activator of CBS. H2S, as a sulfhydryl compound, has similar reducing properties as glutathione. In neurons, H2S stimulates the production of cAMP probably by direct activation of adenylyl cyclase and thus activate cAMP-dependent processes. In astrocytes, H2S increases intracellular calcium to an extent capable of inducing and propagating a "calcium wave", which is a form of calcium signaling among these cells. Possible physiological functions of H2S include potentiating long-term potentials through activation of the NMDA receptors, regulating the redox status, maintaining the excitatory/inhibitory balance in neurotransmission, and inhibiting oxidative damage through scavenging free radicals and reactive species. H2S is also involved in CNS pathologies such as stroke and Alzheimer's disease. In stroke, H2S appears to act as a mediator of ischemic injuries and thus inhibition of its production has been suggested to be a potential treatment approach in stroke therapy. © 2007 Elsevier Ltd. All rights reserved.
Quintana, Cintia Organo et al (2011), Burrow ventilation and associated porewater irrigation by the polychaete Marenzelleria viridis, Journal of Experimental Marine Biology and Ecology, vol. 397, 179 - 187
Burrow ventilation and associated porewater irrigation by the polychaete Marenzelleria viridisQuintana, Cintia Organo, Hansen, Tanja, Delefosse, Matthieu, Banta, Gary, Kristensen, Erik (2011), Journal of Experimental Marine Biology and Ecology, vol. 397, 179 - 187
Burrow ventilation of benthic infauna generates water currents that irrigate the interstices of the sediments surrounding the burrow walls. Such activities have associated effects on biogeochemical processes affecting ultimately important ecosystem processes. In this study, the ventilation and irrigation behavior of Marenzelleria viridis, an invasive polychaete species in Europe, was analyzed using different approaches. M. viridis showed to perform two types of ventilation: (1) muscular pumping of water out of the burrow and (2) cilia pumping of water into the burrow. Flowmeter measurements presented muscular pumping in time averaged rates of 0.15mlmin-1. Oxygen needle electrodes positioned above the burrow openings revealed that muscular undulation of the worm body pumps anoxic water out of the burrow. On the other hand, microscope observations of the animal showed that ventilation of oxygen-rich water in the burrow occurs by ciliary action. The volume of water irrigated by M. viridis appears to vary linearly within the first 24h incubation, with rates ranging from 0.003 to 0.01mlmin-1. From those rates we could estimate that the time averaged rate of cilia ventilation should be about 0.16mlmin-1. Since the cilia pumping into the burrow occurs in periods of 24±12min and at 50-70% of the measured time, considerable amounts of water from deeper sediments may percolate upwards to the sediment surface. This water is rich in reduced compounds and nutrients and may have important associated ecological implications in the ecosystem (e.g. affecting redox conditions, organic matter degradation, benthic recruitment and primary production). © 2010 Elsevier B.V.