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Zhong C.,Beijing Normal University | Wang Y.,Beijing Normal University | Wang Y.,State Key Laboratory of Water Simulation | Lv J.,State Key Laboratory of Water Simulation | And 2 more authors.
Bioresource Technology | Year: 2013

Alternating anoxic/oxic (A/O) combined with the step-feed granular sequence batch reactor (step-feed SBR) was operated in laboratory scale to investigate nitrogen removal. The results showed that when the total inorganic nitrogen (TIN) and chemical oxygen demand (COD) levels were 55 and 320mg/L in the influent, the TIN removal efficiencies were 89.7-92.4% in the step-feed mode and 48.1-59.5% in the conventional alternating A/O single-feed mode within a 360min cycle. The pH and dissolved oxygen (DO) were used to optimize the process of denitrification and nitrification in the step-feed mode. The optimized operational condition was achieved by shortening the cycle time to 207min, resulting in a nitrogen removal rate of 0.27kgN/m3d, which was much higher than those achieved using activated sludge systems. The dominant community in the aerobic granules was coccus-like bacteria, and filamentous bacteria were hardly found. Granules were well maintained throughout the 90days of continuous step-feed operation. © 2013 Elsevier Ltd. Source

Su B.,Beijing Normal University | Cui X.,State Key Laboratory of Water Simulation | Zhu J.,Beijing Normal University
Bioresource Technology | Year: 2012

The present work investigated some important factors for optimal aerobic granulation using typical domestic sewage as a substrate in a pilot-scale alternating anaerobic/aerobic sequencing batch reactor. High sludge concentration and low sludge loading, for the first time, were used for the reactor start-up. A vast number of small particles appeared on day8. Subsequently, several measures for controlling sludge concentration and sludge loading within an appropriate range were applied to optimize the granulation process. On day 45, complete sludge granulation was achieved. After 60days of operation, the aerobic granules always kept in stable state, with an average diameter of 750μm and the SVI 30 of 20-35ml/g. The COD, TN, and TP removal ratios were 92%, 81%, and 85%, respectively. The results demonstrated that it was feasible to form aerobic granules quickly using typical domestic sewage under optimal operation strategies, which was further proved by the results from denaturing gradient gel electrophoresis fingerprint. © 2012. Source

Hao W.,Beijing Normal University | Li Y.,Beijing Normal University | Lv J.,Beijing Normal University | Chen L.,State Key Laboratory of Water Simulation | Zhu J.,Beijing Normal University
Journal of Environmental Sciences (China) | Year: 2016

As a special biofilm structure, microbial attachment is believed to play an important role in the granulation of aerobic granular activated sludge (AGAS). This experiment was to investigate the biological effect of Ca2+, Mg2+, Cu2+, Fe2+, Zn2+, and K+ which are the most common ions present in biological wastewater treatment systems, on the microbial attachment of AGAS and flocculent activated sludge (FAS), from which AGAS is always derived, in order to provide a new strategy for the rapid cultivation and stability control of AGAS. The result showed that attachment biomass of AGAS was about 300% higher than that of FAS without the addition of metal ions. Different metal ions had different effects on the process of microbial attachment. FAS and AGAS reacted differently to the metal ions as well, and in fact, AGAS was more sensitive to the metal ions. Specifically, Ca2+, Mg2+, and K+ could increase the microbial attachment ability of both AGAS and FAS under appropriate concentrations, Cu2+, Fe2+, and Zn2+ were also beneficial to the microbial attachment of FAS at low concentrations, but Cu2+, Fe2+, and Zn2+ greatly inhibited the attachment process of AGAS even at extremely low concentrations. In addition, the acylated homoserine lactone (AHL)-based quorum sensing system, the content of extracellular polymeric substances and the relative hydrophobicity of the sludges were greatly influenced by metal ions. As all these parameters had close relationships with the microbial attachment process, the microbial attachment may be affected by changes of these parameters. © 2016. Source

Wang Y.,Beijing Normal University | Zhong C.,Beijing Normal University | Huang D.,State Key Laboratory of Water Simulation | Zhu J.,Beijing Normal University
Bioresource Technology | Year: 2013

This experimental work investigated the property of membrane fouling for different sludges at high flux 20L/(m2h). The MBR with good aerobic granular sludge performed the longest operation time 61days, and TMP rose up in a steady overall rate, while only 10, 14 and 19days for bulking, flocculent and small granular sludge, respectively, which clearly demonstrated the good and complete aerobic granules greatly retarded the membrane fouling. The pore blocking resistance 76.21% was the key fouling factor for aerobic granules, but the cake resistance 61.23% or 79.02% was the main factor for flocculent or bulking sludge. The difference in EPS composition of membrane foulants between granules MBR and flocculent sludge MBR led to the different behaviour of fouling. Aerobic granules were quite stable during operation. These results suggested MBR with aerobic granules might be operated at high flux, which was very valuable for practical application. © 2013 Elsevier Ltd. Source

Lv J.,Beijing Normal University | Wang Y.,Beijing Normal University | Zhong C.,Beijing Normal University | Li Y.,Beijing Normal University | And 2 more authors.
Bioresource Technology | Year: 2014

The aerobic granulation process is involved in the attachment of microorganisms, and the quorum sensing (QS) is supposed to play an important role in microbial attachment. In this study, the attachment potential of aerobic granular activated sludge (AGAS) and flocculent activated sludge (FAS) was investigated. Results clearly showed that AGAS had stronger attachment potential than FAS. A bioassay with NTL4 proved that N-acylhomoserine lactones (AHLs) were produced in both sludge, but the AHLs content of AGAS was significantly higher than FAS. Additionally, the extracellular polymeric substances (EPS) measurements indicated that there were more proteins and polysaccharides in the hydrophobic EPS fraction of AGAS. Besides, the bacterial community structure of AGAS differed from FAS by PCR-DGGE. Some hydrophobic bacteria, such as Flavobacterium, exclusively existed in AGAS. It was speculated that the difference of attachment potential between AGAS and FAS was derived from the divergence of AHLs, EPS and microbial community. © 2013 Elsevier Ltd. Source

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