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Yao W.-T.,Guangdong University of Technology | Sun S.-Y.,Guangdong University of Technology | Zheng L.,Guangdong University of Technology | Li C.-H.,Guangzhou Lijiao Sewage Treatment Plant | And 3 more authors.
Huanjing Kexue/Environmental Science | Year: 2011

In order to investigate the mechanisms of ultrasonic promotion for sludge anaerobic/aerobic digestibility, the index of EPS(polysaccharide, protein, DNA and total content)and dissolved substances were measured by using biochemistrical methods. The optimal conditions of ultrasonic treatment were decided from the uniform design. The uniform design results showed that at the optimal ultrasonic conditions of 15 min ultrasonic time, 0.1 W/mL density and 12 h ultrasonic interval time, the performances of anaerobic/aerobic digestion were greatly improved, the removal rate of VSS reached 42.45% after 10d digestion. The results of sludge anaerobic/aerobic digestion promoted by ultrasonic treatment showed that the variational trend of EPS index in sludge increased firstly and then fell off during 10 d digestion, the maximum of protein, DNA and total content were appeared in the 2 d, while the maximum of polysaccharides was came out in the 4 d. The total content of EPS in ultrasonic sludge was more than the control sludge during 0-6 d digestion, and then less than control in 6-10 d because of a large amount of EPS and cellular substances had been released out. The variational trend of dissolved substances in the supernatant was similar with that in sludge, the dissolved substances concentrations were highly increased after ultrasonic treatment. The maximum of total concentrations in ultrasonic sludge was 34.61 mg·L-1 higher than the beginning, it was about 3.5 multiple of the increased concentrations of control's maximum, indicated that ultrasonic treatment could release EPS and cellular substances into the supernatant. The greatly release of soluble organics enhanced the consumed proportion of organics, resulted in the removal rate of VSS in ultrasonic sludge was markedly improved. The infrared spectrum analysis of EPS showed that polysaccharide, protein and DNA were the major components of EPS in anaerobic/aerobic sludge, ultrasonic treatment wouldn't change the organic structure of them.


Ye Y.-D.,Guangdong University of Technology | Sun S.-Y.,Guangdong University of Technology | Zheng L.,Guangdong University of Technology | Liu B.-J.,Guangzhou Lijiao Sewage Treatment Plant | And 3 more authors.
Huanjing Kexue/Environmental Science | Year: 2012

In order to evaluate the function of sludge aerobic/anoxic digestibility by ultrasonic pretreatment. The SS, VSS and hydrolytic enzyme activities(amylase, glucosidase, protease, phosphatase) were measured before and after ultrasonic pretreatment(28 kHz, 0.15 kW·L-1, 10 min). The results showed that the performances of aerobic/anoxic were greatly improved after ultrasonic pretreatment, the removal efficiency of VSS went to 44.3%, 7.8% better than of traditional aerobic/anoxic digestion. The variational trend of sludge hydrolytic enzyme activities increased firstly and then fell off during 13d digestion, the maximum of amylase activity and glucosidase activity in ultrasonic sludge, appeared in the 5 d, amylase activity was 0.104 μmol·g-1 and glucosidase activity was 0.637 μmol·g-1. The maximum of intracellular protease activity and extracellular proteases activity in ultrasonic sludge, appeared in the 7 d, intracellular protease activity was 23.68 μmol·g-1, higher than extracellular proteases activity, and it was playing a leading role in sludge digestion. The acid phosphatase activity of ultrasonic sludge was higher than the control sludge, and the alkaline phosphatase was sensitive to environment. So the alkaline phosphatase activity reduced when the internal properties of sludge was changed.


Ye Y.-D.,Guangdong University of Technology | Sun S.-Y.,Guangdong University of Technology | Zheng L.,Guangdong University of Technology | Liu B.-J.,Guangzhou Lijiao Sewage Treatment Plant | And 3 more authors.
Huanjing Kexue/Environmental Science | Year: 2012

The microbial community structure of sludge aerobic/anoxic digestion after ultrasonic pretreatment was studied by PCR amplification and DGGE based on 16S rDNA. The genomic DNA of sludge at different stages was extracted with SDS cell lysate method. After purification of DNA, the 16S rDNA genes(V3 region) were amplified by using the universal primers(F357GC and R518). The results of agarose gel(1.5%)electrophoresis showed that the PCR products were about 190 bp in length. The amplified DNA fragments were separated by paralleled DGGE with the denaturant(urea and acrylamide) from 30% to 60%. The sequences were used for homology analysis and phylogenetic trees were constructed. The DGGE profiles showed that the change of microbial diversity was in correspondence to different periods. Compared with 0 d, the diversities of microorganisms were 61.2%, 48.2%, 46.4%, 42.6% and 41.7%, respectively after 5 d, 10 d, 15 d, 20 d, 25 d. Shannon density index of bacteria experienced a process from a gradual reduction to stable state. This suggested that ultrasonic pretreatment had a significant impact on bacterial community structures. Cluster analysis of DGGE by UPGMA(unweighted air group method, arithmetic mean) divided all lanes into three clusters, which corresponded to different periods during the whole experiment. The sequences indicated that Firmicute, Genuscitrobacter, Bacilli, α-Proteobacteria, β-Proteobacteria were the predominant microbial populations in the process of sludge aerobic/anoxic digestion after ultrasonic pretreatment.


Yao W.,Guangdong University of Technology | Sun S.,Guangdong University of Technology | Zheng L.,Guangdong University of Technology | Yin G.,Guangdong University of Technology | And 4 more authors.
Huanjing Kexue Xuebao/Acta Scientiae Circumstantiae | Year: 2011

In order to investigate the sludge anaerobic/aerobic digestion mechanism by ultrasonic sludge treatment, the index proportion of EPS and dissolved substances (polysaccharides, protein and DNA), enzyme activities (protease activity and dehydorgenase activity) were measured in the anaerobic/aerobic digestion by the optimal ultrasonic treatment (28 kHz ultrasonic frequency, 0.1 W·mL-1 ultrasonic density, 15 min ultrasonic time and 12 h ultrasonic interval time). It showed that the performances of anaerobic/aerobic digestion were greatly improved by ultrasonic treatment, with the removal rate of VSS reaching 40.14% after digestion for 10 days, 20% more than that of the controlled, and at the same time great amount of soluble organics was released. The index proportions of EPS and dissolved substances in the ultrasonic sludge and the control were almost the same, indicating that ultrasonic could promote oxygen/aerobic sludge digestion but would not change the index proportion of EPS and their dissolved substances. The variation trend of enzyme activities increased at the beginning and then dropped off after 10 days' digestion, with the maximum value appearing on the fourth day. The protease activity of ultrasonic sludge was more than that of the controlled during 0~5 d digestion, due to the markedly improved protease activity and the high-speed biological reaction. Organic matter degradation ratio was also improved greatly, leading to the improved VSS removal rate in ultrasonic sludge. While the variation of dehydrogenase activity in ultrasonic sludge was almost the same compared with the controlled, it was therefore unable to represent ultrasonic promotion by sludge anaerobic/aerobic digestibility. The variation trend of sludge bacteria density also increased at the beginning and then dropped off after 10 days' digestion, but it is controversial for the measurement of bacteria density. Further study is needed.

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