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Liu C.,Hebei University of Science and Technology | Li L.,Hebei University of Science and Technology | Ma J.-K.,Hebei University of Science and Technology | Wu G.,Basic Research Service Center | Yang J.-L.,Hebei University of Science and Technology
Huanjing Kexue/Environmental Science | Year: 2011

The methanogenic community in anaerobic granular sludge from a full-scale UASB treating avernectin wastewater was analyzed based on mcrA gene, compared to 16S rRNA gene. The results indicated that the diversity indices of methanogenic community, including Shannon diversity index, Margalef richness index and Berger-Parker dominance index, were no difference between mcrA gene-based and 16S rRNA gene-based PCR products analysis by DGGE, although their DGGE band patterns were different, implying that the diversity analysis of methanogenic community based on mcrA genes was consistent with 16S rRNA gene. The phylogenetic analysis of dominant methanogenic populations based on these two target genes also showed resemble and Methanobacteriales and Methanosarcinales were determined to be the main orders of methanogenic populations in anaerobic granular sludge. On the other hand, the difference in phylogenetic analysis suggested simultaneously some group-specific of the two target genes. The hybridization of methanogenic community in FISH analysis based on two target genes was almost identical except a little different hybridization areas. The average relative abundance of methanogenic community was 24.25%±6.47% detected by FISH based on mcrA gene, lower than that based on 16S rRNA gene (33.42%±2.34%). Then it could be concluded that the analysis of methanogenic community based on mcrA gene and 16S rRNA gene exhibited high resemblance and mcrA gene could used to be target gene for methanogenic community, as an alternative of 16S rRNA gene. Source


Liu C.,Hebei University of Science and Technology | Yang J.L.,Hebei University of Science and Technology | Wu G.,Basic Research Service Center | Zhang S.,Hebei University of Science and Technology | And 2 more authors.
World Journal of Microbiology and Biotechnology | Year: 2010

Although the dominant members of microbial communities in wastewater bio-treatment systems were often paid attention due to their possible important roles in treatment performance, their population sizes, especially the unculturable species, were still little known. Then PCR-DGGE was used in an attempt to estimate the dominant microbial population sizes in the anaerobic granular sludge treating streptomycin wastewater, coupled with an inoculated strain (Esherichia coli) with known population sizes as an internal standard. The results indicated that the band intensities of the inoculated strain in DGGE profiles showed good correlation with population sizes. Then it was possible to estimate the dominant microbial population sizes by means of comparing their DGGE band intensities with the inoculated strain. The estimated results demonstrated that the sizes of major dominant microbial populations in the sludge sample were at the level of 107-108 CFU/g. The sizes of secondary dominant microbial populations were at the level of 105-106 CFU/g. The microbial populations with the size level lower than 103 CFU/g were undetectable by PCR-DGGE. These results provided a potential approach to evaluate dominant microbial population sizes in complex microbial communities. © 2009 Springer Science+Business Media B.V. Source


Ma J.,Hebei University of Science and Technology | Liu C.,Hebei University of Science and Technology | Zhang L.,Hebei University of Science and Technology | Zhang J.,Hebei University of Science and Technology | And 3 more authors.
Zhejiang Daxue Xuebao (Gongxue Ban)/Journal of Zhejiang University (Engineering Science) | Year: 2013

Variations of mixed liquor properties of activated sludge were investigated and their correlations were analyzed in microbubble aeration using SPG membrane microbubble generation system, including sludge size, sludge EPS mass concentration, turbidity and organic carbon in the supernatant, viscosity and surface tension of mixed liquor. Results showed that the strong shear stress caused by liquid recycling pump in the microbubble generation system led to sludge broken and subsequent sludge floc size decreasing. During the process of sludge broken, sludge EPS released, which was considered to be responsible for increased turbidity and organic carbon (especially colloidal organic carbon) mass concentration in the supernatant. The re-flocculation ability of sludge flocs also reduced significantly due to sludge EPS release. In addition, the viscosity of mixed liquor increased along with sludge EPS release, but the surface tension remained constant. The sludge size decreasing and sludge EPS release were the main reasons for variations of other mixed liquor properties, according to correlation analysis. Compared to centrifugal type pump, peristaltic type pump impacted on mixed liquor properties less due to its weaker hydraulic shear stress. The membrane fouling in the membrane filtration process was accelerated due to variations of mixed liquor properties in microbubble aeration. Source


Ma J.-K.,Hebei University of Science and Technology | Liu C.,Hebei University of Science and Technology | Wu G.,Basic Research Service Center | Yang J.-L.,Hebei University of Science and Technology | And 2 more authors.
Zhejiang Daxue Xuebao (Gongxue Ban)/Journal of Zhejiang University (Engineering Science) | Year: 2011

Probes specific for syntrophic acetogenic bacteria were designed and fluorescence in situ hybridization (FISH) was used to analyze their distribution and relative abundance in anaerobic granular sludge in a full-scale up-flow anaerobic sludge bed (UASB) reactor treating avermectin wastewater, and the activity of syntrophic acetogenic bacteria was also determined. The results indicated that the distribution forms of syntrophic acetogenic bacteria, syntrophic propionate-oxidizing bacteria and syntrophics fatty acid-β-oxidizing syntrophic bacteria were same on the surface and inner face of granular sludge samples in different formation periods. However, the average relative abundances of those syntrophic acetogenic bacteria populations were different, ranging from (10.08 ± 0.81)% to (28.06 ± 2.12)%. The maximum relative abundance of syntrophic acetogenic bacteria was obtained when granular sludge was in mature period. The relative abundances of syntrophic acetogenic bacteria on the inner face were less than those on the surface of granular sludge samples. The relative abundances of syntrophic propionate-oxidizing bacteria were larger than those of syntrophics fatty acid-β-oxidizing syntrophic bacteria. The avermectin residue in wastewater showed inhibition effect on syntrophic acetogenic bacteria. The maximum specific acetate rates of granular sludge samples ranged from 0.912 to 1.145 g/(g · d) and their variation tendency was identical with relative abundance of syntrophic acetogenic bacteria. Source


Liu C.,Hebei University of Science and Technology | Ma J.,Hebei University of Science and Technology | Zhang L.,Hebei University of Science and Technology | Zhang J.,Hebei University of Science and Technology | And 2 more authors.
Huanjing Kexue/Environmental Science | Year: 2013

Microbubble aeration is supposed to be able to provide potential advantage for aerobic biological wastewater treatment due to enhancement of oxygen mass transfer. On the other hand, microbubble and its generation methods might affect mixed liquor properties of activated sludge. Then SPG membrane microbubble generation system was used to investigate mixed liquor properties of activated sludge in microbubble aeration. The results indicated that sludge floatation happened in microbubble aeration due to attachment of microbubbles to sludge flocs, resulting in a decrease in mixed liquor suspended solid (MLSS) concentration in the bioreactor and poor sludge settleability. The strong shear stress caused by liquid recycling pump (centrifugal type) during microbubble generation led to sludge broken. As a result, sludge floc size decreased significantly and sludge EPS released. The release of sludge EPS was considered to be responsible for increased turbidity and organic carbon (especially colloidal organic carbon) concentration in the supernatant. The re-flocculation ability of sludge flocs also almost lost due to sludge EPS release. In addition, the mixed liquor viscosity increased along with sludge broken and sludge EPS release, but the surface tension of mixed liquor remained constant. Source

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