Yu Qin

Chongqing University, Ch’ung-ch’ing-shih, Chongqing Shi, China

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Publications (7)0.75 Total impact

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    ABSTRACT: To study the influence of dissolved oxygen (DO) on bacterial population in a one-step autotrophic nitrogen removal process and to improve the system operation. Ammonia oxidizing bacteria (AOB), nitrite oxidizing bacteria (NOB) and anaerobic ammonium oxidizing bacteria (ANAMMOX) were amplified directly from the one-step completely autotrophic nitrogen removal reactor by using the specific PCR primers. The purified PCR products were cloned into T-vector and identified as the target fragments of AOB, NOB and ANAMMOX by sequencing. Recombined plasmid was used as standard molecule sample in Real-time PCR for quantification. High DO was beneficial to AOB and NOB. The population of both AOB and NOB were higher in activated sludge than biofilm samples. High DO had the directly influence on ANAMMOX population whereas low DO had the inhibitory effect of ANAMMOX activity if the system was lack of NO3- and NO2-. DO of 2.0 (aeration)/0.4(non-aeration) mg/L was the best operation concentration. Meanwhile, ANAMMOX population reached the peak in this condition and AOB, NOB as well as ANAMMOX composes of a steady co-metabolisms system.
    ACTA MICROBIOLOGICA SINICA 07/2009; 49(6):773-9.
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    ABSTRACT: To analyze the effect of DO and aeration/non-aeration ratio on the microbial community structure, active sludge and biofilm samples were taken from the SBBR one-step completely autotrophic nitrogen removal reactor under different DO concentrations and aeration/non-aeration ratios. By PCR-DGGE and bands statistical analyses, results show that through one and a half year of operation, the microbial community structures in this system has changed a lot compared with the inoculum. The bacterial richness values of biofilm are higher than active sludge in 2 h:2 h aeration/non-aeration ratio, no matter when moderate, high and low DO concentration. When this system is operated under the most efficient condition: DO = 2.0 (aeration) mg/L, 0.4 (non-aeration) mg/L, the bacterial richness values are the highest. There are about 14 and 10 bands in the biofilm and active sludge samples respectively. The diversities of bacterium and their co-metabolisms are the key factors of maintaining a high operate efficiency. In addition, the aeration/non-aeration ratio also has the influence on the microbial community structure. Under long aeration/non-aeration ratio of 3 h:5 h, microbial community structure of biofiln is similar with active sludge. The comparability is 100%. The activities of aerobic and anaerobic bacterium have lost much that makes low efficiency of this system although they could survive both in active sludge and biofim.
    Huan jing ke xue= Huanjing kexue / [bian ji, Zhongguo ke xue yuan huan jing ke xue wei yuan hui "Huan jing ke xue" bian ji wei yuan hui.] 03/2009; 30(2):493-8.
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    ABSTRACT: Different synthetic wastewaters were used in the batch tests to analyze the intermediate products and the nitrogen balance, and to study the mechanism of ammonium removal in the completely autotrophic nitrogen removal in one reactor process with the sludge cultured in the SBBR completely autotrophic nitrogen removal system. The results showed that 62% of ammonium was converted to such nitrogen compounds as NO2-, NO3-, NH2 OH, N2H4, NO, NO2, N2O and N2 without addition of organic carbon, and N2 took up 90.07%. The ammonium in the completely autotrophic nitrogen removal in one reactor system was removed in many ways. 4.5% of ammonium was removed in the physical-chemical way. 3.73% of ammonium was converted by the conventional nitrification-denitrification process. The quantity of ammonium removed by the completely autotrophic nitrogen removal in one reactor process was 53.77%, which is the largest, and the completely autotrophic nitrogen removal in one reactor process could be realized in two different metabolic pathways. But the effluent ammonium in the anoxic reactor, where enough NO2 present were present, was equal to the blank system, and no ammonium was converted to such nitrogen compounds as NO2- and N2 by Nitrosomonas eutropha using NO2 as electron acceptor, which maybe caused by lack of the function bacteria.
    Huan jing ke xue= Huanjing kexue / [bian ji, Zhongguo ke xue yuan huan jing ke xue wei yuan hui "Huan jing ke xue" bian ji wei yuan hui.] 02/2009; 30(1):102-7.
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    ABSTRACT: In this study, three sequential batch biofilm reactors (SBBRs) were operated for 155 days to evaluate the performance of completely autotrophic nitrogen removal over nitrite (CANON) process under different aeration modes and dissolved oxygen (DO). Synthetic wastewater with 160-mg NH4 +-N/L was fed into the reactors. In the continuously-aerated reactor, the efficiency of the ammonium nitrogen conversion and total nitrogen (TN) removal reached 80% and 70%, respectively, with DO between 0.8–1.0 mg/L. Whereas in the intermittently-aerated reactor, at the aeration/non-aeration ratio of 1.0, ammonium was always under the detection limit and 86% of TN was removed with DO between 2.0–2.5 mg/L during the aeration time. Results show that CANON could be achieved in both continuous and intermittent aeration pattern. However, to achieve the same nitrogen removal efficiency, the DO needed in the intermittently-aerated sequential batch biofilm reactor (SBBR) during the aeration period was higher than that in the continuously-aerated SBBR. In addition, the DO in the CANON system should be adjusted to the aeration mode, and low DO was not a prerequisite to CANON process.
    Frontiers of Environmental Science & Engineering in China 11/2008; 2(4):439-445. · 0.75 Impact Factor
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    ABSTRACT: To study the characteristics of the Nitroso-bacteria in one-step completely autotrophic nitrogen removal process. We took samples from activated sludge of the one-step completely autotrophic nitrogen removal reactor. Through four times of enrichments and isolations, one Nitroso-bacteria named N1 was obtained. We identified this strain by microscope and 16S rDNA analysis and studied the effect of pH, temperature as well as ammonium concentration on the metabolism of N1. Of the N1 nucleotides, 97%, 96% and 96% were identical with the conserved fragment of Nitrosomonas sp. NL7 (AY958677), Nitrosomonas AS1 (EF016119) and Nitrosomonas sp. Is32 (AJ621027) respectively. The optimal temperature and pH of N1 were 8.0 and 30 degrees C and sufficient dissolved oxygen was demanded. In addition, no restraint effect was turned up in the ammonium concentration of 80-800 mg/L. N1 was identified as Nitrosomonas sp. Compared with the relative references, this strain was ammonium-tolerant.
    ACTA MICROBIOLOGICA SINICA 09/2008; 48(8):1088-94.
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    ABSTRACT: To improve the performance of single SBBR completely autotrophic nitrogen removal system and study the influence of aeration/non-aeration ratio on it, four reactors were applied in the experiment. The results showed that both continuous and intermittent aeration system could implement completely autotrophic nitrogen removal. On the conditions of ammonium concentration round 160 mg/L, temperature 30 degrees C +/- 2 degrees C, pH value 7.8-8.2, HRT 2 days and DO 0.8-1.0 mg/L, ammonium and total nitrogen removal efficiency reached 80% and 70% respectively in the continuous aeration system, and in the system of DO 2.0-2.5 (aeration) mg x L(-1)/ 0.2-0.4 (non-aeration) mg x L(-1), aeration/non-aeration ratio 2 h:2 h, ammonium and total nitrogen removal efficiency reached above 90% and 80% respectively. DO should be adjusted in accordance with aerobic/anaerobic ratio, and may be related to the biomass and its distribution between activated sludge and biofilm. The mechanism of nitrogen removal was also discussed.
    Huan jing ke xue= Huanjing kexue / [bian ji, Zhongguo ke xue yuan huan jing ke xue wei yuan hui "Huan jing ke xue" bian ji wei yuan hui.] 10/2007; 28(9):1975-80.
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    ABSTRACT: The start-up experiment on nitrification of mid-low NH4+ -N concentration wastewater was carried out in four SBR biofilm reactors for the establishment of completely autotrophic nitrogen removal process by the control of DO and HRT and different medias. The results show that on the conditions of temperature 30 degrees C +/-2 degrees C, ammonia concentration 60-120 mg/L, DO 0.8 - 1.0 mg/L and hydraulic retention time 24 h, the inoculating general active aerobic sludge and anaerobic sludge was nitrified stably after 130 days, and the YJZH media was more suitable for microorganism coherence.
    Huan jing ke xue= Huanjing kexue / [bian ji, Zhongguo ke xue yuan huan jing ke xue wei yuan hui "Huan jing ke xue" bian ji wei yuan hui.] 05/2006; 27(4):686-90.