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Zhu J.M.,Central South University | Li G.,Central South University | Jiang L.Y.,Central South University | Jiang L.Y.,National Engineering Research Center for Control and Treatment of Heavy Metal Pollution
Journal of Applied Polymer Science | Year: 2016

A series of polysiloxaneimide (PSI)/polyetherimide (PEI) composite hollow fibers were fabricated by coextrusion and phase inversion. The hydrophobic PSI outer layer was set as the selective layer which was supported by the PEI inner layer. The PSI was synthesized by polycondensation of 3,3′,4,4′-Biphenyltetracarboxylic Dianhydride (BPDA) with amino siloxane X-22-161A and a chain extender, 1,3-Bis (3-aminopropyl) -1,1,3,3-tertramethyldisiloxane (BATS). It was found that the macroscopic uniformity of PSI layer was dependent on the dope formulation, coagulant composition and dope flow rate: (1) the higher similarity degree of the solvent(s) for different layers in terms of solubility parameters, (2) the utilization of surfactant as a component in the water coagulant, and (3) higher flow rates of the outer layer dopes, led to the formation of more uniform and smoother PSI outer layer. The maximum outer layer thickness was around 2 μm. The bulk of the PEI layers were porous with finger like macrovoids. The outer surface of the inner PEI layer for some batches of the hollow fibers was confirmed to be porous. The original dual-layer hollow fibers showed poor pervaporation performance. Post treatment was applied to cure the hollow fiber, delivering composite membranes with performance dominated by the coating material of PDMS. © 2016 Wiley Periodicals, Inc. Source


Ali M.,Central South University | Ali M.,National Engineering Research Center for Control and Treatment of Heavy Metal Pollution | Chai L.-Y.,Central South University | Chai L.-Y.,National Engineering Research Center for Control and Treatment of Heavy Metal Pollution | And 14 more authors.
International Biodeterioration and Biodegradation | Year: 2016

The start-up and subsequent operation of nitritation process was carried out in an airlift reactor (ALR) over 253 days under the HRT shortening condition. The nitrogen loading rate (NLR) of the ALR was finally raised to 4.07 kg m-3d-1 by shortening the HRT from 22.7 to 2.1 h under 350 mg l-1 of influent ammonium. The improvement of removal efficiency and nitrite accumulation to 98.7% and 92.4% elevated the ammonium removal rate (ARR) and nitrite production rate (NPR) to 3.89 and 2.81 kg m-3d-1, respectively. The settling property of the nitritation biomass was improved substantially under the high hydraulic loading condition. Scanning electronic microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) were used to evaluate the physicochemical characteristics of the biomass. The attachment of chemical precipitates on biomass surface was an important reason contributing to the enhancement of nitritation performance through increasing the sludge settleability. The taxonomic complexities of microbial communities from phylum to species level were dealt with the high-throughput pyrosequencing of 16S rRNA gene sequence. It was revealed that Lactobacillus, Thermomonas, Ignavibacterium and Aquimonas were the most abundant genera in the biomass. The low abundance of Nitrospira and Candidatus Brocadia confirmed the possible occurrence of nitrite oxidation as well as anammox in the ALR. © 2016 Elsevier Ltd. Source


Ali M.,Central South University | Ali M.,National Engineering Research Center for Control and Treatment of Heavy Metal Pollution | Chai L.-Y.,Central South University | Chai L.-Y.,National Engineering Research Center for Control and Treatment of Heavy Metal Pollution | And 11 more authors.
BioMed Research International | Year: 2013

Nitrogen pollution created severe environmental problems and increasingly has become an important issue in China. Since the first discovery of ANAMMOX in the early 1990s, this related technology has become a promising as well as sustainable bioprocess for treating strong nitrogenous wastewater. Many Chinese research groups have concentrated their efforts on the ANAMMOX research including bacteria, process development, and application during the past 20 years. A series of new and outstanding outcomes including the discovery of new ANAMMOX bacterial species (Brocadia sinica), sulfate-dependent ANAMMOX bacteria (Anammoxoglobus sulfate and Bacillus benzoevorans), and the highest nitrogen removal performance (74.3-76.7 kg-N/m3/d) in lab scale granule-based UASB reactors around the world were achieved. The characteristics, structure, packing pattern and floatation mechanism of the high-rate ANAMMOX granules in ANAMMOX reactors were also carefully illustrated by native researchers. Nowadays, some pilot and full-scale ANAMMOX reactors were constructed to treat different types of ammonium-rich wastewater including monosodium glutamate wastewater, pharmaceutical wastewater, and leachate. The prime objective of the present review is to elucidate the ongoing ANAMMOX research in China from lab scale to full scale applications, comparative analysis, and evaluation of significant findings and to set a design to usher ANAMMOX research in culmination. © 2013 Mohammad Ali et al. Source


Tang C.-J.,Central South University | Tang C.-J.,National Engineering Research Center for Control and Treatment of Heavy Metal Pollution | Xiong L.,Central South University | Xiong L.,National Engineering Research Center for Control and Treatment of Heavy Metal Pollution | And 3 more authors.
Huanjing Kexue/Environmental Science | Year: 2013

The high-rate ANAMMOX granules (HAG) were cultivated in an ANAMMOX upflow anaerobic sludge blanket (UASB) reactor. The kinetic characteristics of the HAG were investigated through batch tests, using flocculent ANAMMOX sludge (FAS) as a control. The results suggested that the specific ANAMMOX activity (SAA) of the HAG reached as high as 2.63 kg · (kg · d)-1, which was 2.5 times of that of FAS. The half saturation constants for ammonium and nitrite of the HAG were 17 mg · L-1 and 19 mg · L-1, respectively, both were lower than those of the FAS. The half inhibition constants of ammonium, free ammonia and nitrite were 11 679, 505 and 735 mg · L-1, respectively, which were far higher than the corresponding values of the FAS. The better kinetic performance of the HAG contributed to the successful competition of substrates under tough conditions, which was helpful for the novel biomass supplementation process for enhancement of the ANAMMOX performance. Source


Ali M.,Central South University | Ali M.,National Engineering Research Center for Control and Treatment of Heavy Metal Pollution | Chai L.-Y.,Central South University | Chai L.-Y.,National Engineering Research Center for Control and Treatment of Heavy Metal Pollution | And 13 more authors.
Biodegradation | Year: 2016

The short-cut nitrification (SCN) performance of an airlift reactor (ALR) was investigated under increasing bicarbonate condition. The sequential increase of bicarbonate from 2.5 to 7.0 g/L accelerated the nitrite accumulation and improved the NAP to 99 %. With the increase of bicarbonate dose to 11 g/L, the ammonium removal efficiency and the ammonium removal rate (ARR) were improved to 95.1 % and 0.57 kg/m3/day, respectively. However, the elevation of bicarbonate concentration from 11.0 to 14.0 g/L gradually depreciated the nitrite accumulation percentage to 62.5 %. Then, the reactor was operated in increasing ammonium strategy to increase the nitrogen loading rate (NLR) to 1.1 kg/m3/day under 700 mg/L influent ammonium concentration. The ARR and nitrite production rate were elevated to 1.1 and 0.9 kg/m3/day, respectively. The SCN performance was improved to 1.8 kg/m3/day (NLR) by the subsequent progressive shortening of HRT to 4.8 h at ammonium concentration of 350 mg/L, which was 1.6 times higher than that of the increasing ammonium strategy. Chemical analysis with EDS, FTIR and XRD confirmed the presence of CaCO3 precipitates on biomass surface during the long-term operation under high bicarbonate conditions. The attachment of precipitates to the SCN sludge helped to improve the biomass settleability and finally enhanced the SCN performance of the ALR. © 2016 Springer Science+Business Media Dordrecht Source

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