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Qiao S.,Dalian University of Technology | Bi Z.,Dalian University of Technology | Zhou J.,Dalian University of Technology | Cheng Y.,Dalian Municipal Development and Reform Commission | Zhang J.,Harbin Institute of Technology
Bioresource Technology | Year: 2013

In this study, we explored the effects of Fe(II) on the activity of anammox biomass both in short and long terms. With the influent Fe(II) at 0.09 and 0.12. mM, continuous experiments demonstrated that the nitrogen removal rates increased 32.2% and 29.9% compared to that with normal Fe(II) level (0.03. mM). Influent Fe(II) variation could affect the total Fe, heme c levels and hydrazine dehydrogenase activity. At the Fe(II) concentration of 0.09. mM, the total Fe, heme c levels inside anammox cell and hydrazine dehydrogenase activity could increase about 2.0, 2.1 and 2.35 folds as much as that with normal Fe(II) level. However, when the Fe(II) elevated to 0.18. mM, it would cause a mal-effect on anammox bacteria and further deteriorate nitrogen removal performance. It was indicated that the appropriate increase of Fe(II) was beneficial for more heme c synthesis, enhancement of hydrazine dehydrogenase activity, the growth of anammox bacteria. © 2013 Elsevier Ltd. Source


Qiao S.,Dalian University of Technology | Tian T.,Dalian University of Technology | Duan X.,Dalian University of Technology | Zhou J.,Dalian University of Technology | Cheng Y.,Dalian Municipal Development and Reform Commission
Chemical Engineering Journal | Year: 2013

In this study, we developed an effective strategy to achieve single-stage autotrophic nitrogen removal by co-immobilizing partial nitrifying and anaerobic ammonia oxidation (anammox) biomass. Batch experiments were carried out to determine the optimum dissolved oxygen concentration of 1.5. mg/L, and the optimum biomass ratio of partial nitrifying biomass versus anammox biomass of 1:2. In continuous experiment, the total nitrogen removal rate reached 1.69. g. N/L/d (nitrogen loading rate up to 2.2. g. N/L/d). At the stable running stage, the TN average removal efficiency reached 77%. Scanning electron microscopy observations showed microorganisms greatly increased after 80. days cultivating. FISH analysis indicated that most anammox cells agglomerated in groups and ammonia oxidizing bacteria formed a thick layer around anammox cells. © 2013 Elsevier B.V. Source


Bi Z.,Dalian University of Technology | Qiao S.,Dalian University of Technology | Zhou J.,Dalian University of Technology | Tang X.,Dalian University of Technology | Cheng Y.,Dalian Municipal Development and Reform Commission
Chemical Engineering Journal | Year: 2014

This study investigated the inhibitory effects of Cd, Ag, Hg and Pb on Anammox biomass by batch experiments. Inhibition effects and recovery performance were monitored in sequence over 24h and 72h experimental runs. The IC50 (the 50% inhibitory concentration of nitrogen removal rate) values were calculated as follows: 11.16±0.42mg/L for Cd; 11.52±0.49mg/L for Ag; 60.35±2.47mg/L for Hg. Pb caused only 7.19% decrease on nitrogen removal rate (NRR) even at a dose of 40mg/L. Hence, the order of the inhibitory effect was determined as Cd>Ag>Hg>Pb. Furthermore, the crude enzyme (hydrazine dehydrogenase) activity and heme c concentration were also depressed under heavy metals exposure. Among four metals, Cd and Hg could exert sustained toxicity on Anammox biomass, but mal-effects of Ag and Pb could resume to a large extent after removing these two metals within 96h. © 2014 Elsevier B.V. Source


Qiao S.,Dalian University of Technology | Bi Z.,Dalian University of Technology | Zhou J.,Dalian University of Technology | Cheng Y.,Dalian Municipal Development and Reform Commission | And 2 more authors.
Bioresource Technology | Year: 2012

This study examined long-term effect of MnO2 powder (average diameter of 4-7μm) on nitrogen removal in anammox process. Two lab-scale up-flow anammox reactors were operated for 380days, one with and one without MnO2 powder addition. During the period when only substrate concentrations varied, the maximum nitrogen removal rate in the reactor with MnO2 addition reached 920.9g-N/m3/d. This value was 2-folds higher than that (464.6g-N/m3/d) of the reactor without MnO2 addition. The crude enzyme activities of the anammox biomass from the two reactors was measured as 0.531±0.019 and 0.298±0.007μmol cytochrome c reduced/mg protein/min, respectively. Transmission electron microscopy observation demonstrated more undefined particles existing inside anammox bacterial cell in the reactor with MnO2 powder addition. Furthermore, filament-like structures inside anammoxosome were observed, which formed a net-like structure with particles as the connecting nodes. The experiment results demonstrated that MnO2 improved nitrogen removal performance of anammox process. © 2012 Elsevier Ltd. Source


Qiao S.,Dalian University of Technology | Duan X.,Dalian University of Technology | Zhou J.,Dalian University of Technology | Cheng Y.,Dalian Municipal Development and Reform Commission | Bhatti Z.,Environment Canada
World Journal of Microbiology and Biotechnology | Year: 2014

In this study, we developed a novel technique for preparing polyvinyl alcohol (PVA) hydrogel as an immobilizing matrix by the addition of sodium bicarbonate. This resulted in an increase in the specific surface area of PVA_sodium bicarbonate (PVA_SB) hydrogel beads to 65.23 m2 g-1 hydrogel beads, which was approximately 85 and 14 % higher than those of normal PVA and PVA_sodium alginate (PVA_SA) hydrogel beads, respectively. The D e value of PVA_SB hydrogel beads was calculated as 7.49 × 10-4 cm2 s-1, which was similar to the D e of PVA_SA hydrogel beads but nearly 38 % higher than that of the normal PVA hydrogel beads. After immobilization with nitrifying biomass, the oxygen uptake rate and the ammonium oxidation rate of nitrifying biomass entrapped in PVA_SB hydrogel beads were determined to be 19.53 mg O2 g MLVSS-1 h-1 and 10.59 mg N g MLVSS-1 h-1, which were 49 and 43 % higher than those of normal PVA hydrogel beads, respectively. Scanning electron microscopy observation of the PVA_SB hydrogel beads demonstrated relatively higher specific surface area and revealed loose microstructure that was considered to provide large spaces for microbial growth. This kind of structure was also considered beneficial for reducing mass transfer resistance and increasing pollutant uptake. © 2014 Springer Science+Business Media Dordrecht. Source

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