Role of extracellular exopolymers in biological phosphorus removal

2006 ◽  
Vol 54 (8) ◽  
pp. 257-265 ◽  
Author(s):  
Y. Liu ◽  
S. Yu ◽  
G. Xue ◽  
F. Zhao
Keyword(s):  
Phosphorus Removal ◽  
Energy Dispersive Spectrometry ◽  
Phosphorus Content ◽  
Carbon Sources ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
Biological Phosphorus Removal ◽  
Key Factor ◽  
Biological Phosphorus

Three sequencing batch reactors (SBRs) supplied with different carbon sources were investigated. The system supplied with glucose gained the best enhanced biological phosphorus removal (EBPR), although all of them were seeded from the same sludge. With the measurement of poly-β-hydroxyalkanoate (PHA) concentration, phosphorus content in sludge and extracellular exopolymers (EPs) with scanning electron microscopy (SEM) combined with energy dispersive spectrometry (EDS), it was found that the biosorption effect of EPs played an important role in phosphorus removal and that the amount of PHA at the end of anaerobic phase was not the only key factor to determine the following phosphorus removal efficiency.

An ORP screening protocol for biological phosphorus removal in sequencing batch reactors

1995 ◽  
Vol 22 (2) ◽  
pp. 260-269 ◽  
Author(s):  
D. G. Wareham ◽  
K. J. Hall ◽  
D. S. Mavinic
Keyword(s):  
Carbon Storage ◽  
Phosphorus Removal ◽  
Reduction Potential ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
Biological Phosphorus Removal ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Screening Protocol ◽  
Biological Phosphorus

This research discusses two strategies for adding acetate to sequencing batch reactors operating as biological removal (Bio-P) systems. The control (fixed-time) reactor adds the acetate at a set time of 1 h 25 min, which is an assumed time for complete denitrification. The experimental (real-time) reactor adds the acetate when a computer detects the disappearance of nitrates, as indicated by a distinctive "breakpoint" or "kink" in the oxidation-reduction potential versus time profile. This control strategy is therefore based upon a known time for complete denitrification. The time-of-occurrence of the nitrate breakpoint is utilized in the development of a screening protocol for interpreting the behaviour (in terms of nitrate reactions) for reactors operating in biological phosphorus removal mode. The protocol involves categorizing the timing of the nitrate breakpoint into two groupings. A "failure" category corresponds to acetate being added prior to the breakpoint, because, in these cases, the acetate is used partially for denitrification and partially for Bio-P carbon storage. A "success" category corresponds to breakpoints occurring prior to the addition of acetate. In such cases, acetate is used solely for carbon storage by Bio-P organisms. Key words: oxidation-reduction potential, biological phosphorus removal, sequencing batch reactor, real-time computer control.

Bioaugmentation of sequencing batch reactors for biological phosphorus removal: comparative rRNA sequence analysis and hybridization with oligonucleotide probes

1998 ◽  
Vol 37 (4-5) ◽  
pp. 469-473 ◽  
Author(s):  
Daniel B. Oerther ◽  
James Danalewich ◽  
Ebru Dulekgurgen ◽  
Eric Leveque ◽  
David L. Freedman ◽  
...  
Keyword(s):  
Phosphorus Removal ◽  
Laboratory Scale ◽  
Batch Reactors ◽  
Oligonucleotide Probes ◽  
Sequencing Batch Reactors ◽  
Biological Phosphorus Removal ◽  
Start Up ◽  
Pure Cultures ◽  
Acinetobacter Spp ◽  
Biological Phosphorus

Four laboratory-scale sequencing batch reactors (SBRs) were operated to evaluate whether bioaugmentation with Acinetobacter spp. can be used to improve start-up and performance of enhanced biological phosphorus removal (EBPR) systems. Two of the SBRs were bioaugmented during start-up by adding pure cultures of Acinetobacter spp., the third reactor received an amendment of activated sludge from a laboratory-scale EBPR system, and the fourth reactor, receiving no amendment, served as a control. Various chemical parameters were measured to monitor the performance of the four SBRS. Oligonucleotide probes of nested phylogenetic specificity were designed to quantify the contribution of Acinetobacter to EBPR. The probes were characterized for use in quantitative membrane hybridizations and fluorescent in situ hybridizations. Data from hybridizations with samples collected from the SBRs show declining levels of Acinetobacter spp. over the experiment. All four reactors achieved significant phosphorus removal and 90% nitrification after three days of operation. The results do not show a positive correlation between levels of Acinetobacter and successful EBPR.

The effect of volatile fatty acids on enhanced biological phosphorus removal and population structure in anaerobic/aerobic sequencing batch reactors

1997 ◽  
Vol 35 (1) ◽  
pp. 153-160 ◽  
Author(s):  
Andrew Amis Randall ◽  
Larry D. Benefield ◽  
William E. Hill ◽  
Jean-Paul Nicol ◽  
Gerald K. Boman ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Phosphorus Removal ◽  
Volatile Fatty Acids ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
Enhanced Biological Phosphorus Removal ◽  
Biological Phosphorus Removal ◽  
Slow Growth Rate ◽  
Biological Phosphorus ◽  
State Nature

Three anaerobic/aerobic sequencing batch reactors (SBRs) were operated for 5 1/2 years. Volatile fatty acids (VFAs) in influent wastewater for two of the SBRs (the Glucose 1 and 2 SBRs) resulted in optimization of enhanced biological phosphorus removal (EBPR), and a bacterial population capable of increasing phosphorus (P) removals in response to increased VFA or P concentration. Another SBR not receiving VFAs (the Starch SBR) showed marginal EBPR and was incapable of either response. All three anaerobic/aerobic sequencing batch reactors (SBRs) showed bounded oscillations in P removal that did not correspond to any operational or environmental change. The oscillations were probably associated with interspecies population dynamics intensified due to the periodic, unsteady-state, nature of the SBR process. The glucose SBRs also showed an additional type of variability associated with EBPR, probably from competition between poly-P and “G” bacteria for readily available substrate (i.e. glucose, VFAs) during anaerobiosis. The predominant bacterial isolates from the glucose SBRs were Pseudomonas and Bacillus while Aeromonas was isolated most frequently from the Starch SBR. The relatively slow growth rate of Pseudomonas may have contributed to the high variability of EBPR observed. Fractal analysis indicated overall variability may have been chaotic, but was inconclusive.

Use of a new anaerobic-aerobic sequencing batch reactor system to enhance biological phosphorus removal

1997 ◽  
Vol 35 (1) ◽  
pp. 137-144 ◽  
Author(s):  
Shahnaz Danesh ◽  
Jan A. Oleszkiewicz
Keyword(s):  
Phosphorus Removal ◽  
Sequencing Batch Reactor ◽  
Batch Reactor ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
Biological Phosphorus Removal ◽  
Significant Difference ◽  
Acid Fermenter ◽  
Biological Phosphorus ◽  
Enhance Biological Phosphorus Removal

A two-stage anaerobic-aerobic sequencing batch reactor (SBR) system (PAF-SBR) was developed to enhance biological phosphorus removal in the sequencing batch reactors. The system performance was evaluated against a conventional SBR system in parallel lab-scale reactors at room temperature, using the degritted raw wastewater as the feed. The SRT for the anaerobic SBR which is named PAF (Primary Acid Fermenter) was 12 days, and for both the BNR reactors was 10 days. All reactors were run at 3 cycles per day. A significant difference (P=0.01) was observed between the performances of the two systems. The Ortho-P concentration in the effluent from the PAF-SBR was mostly below 0.5 mg/L while in the conventional SBR was generally above 1.5 mg/L. Lack of availability of carbon (mean VFA/PSol.=1.1) and long anoxic/anaerobic period were the major causes of inefficient removal of phosphorus in the conventional SBR system. The use of anaerobic stage however increased the mean VFA/PSol. to 11.3 which enhanced Bio-P removal in the PAF-SBR system. Prefermentation also improved the sludge consistency and settleability in the following SBR unit. The results indicated that by using the perfermentation step, the anoxic/anaerobic period in the BNR-SBR could be controlled and reduced to less than 50 minutes, which would reduce the total cycle time from 8 hr to 6 hr.

Nutrient removal, microbial community and sludge settlement in anaerobic/aerobic sequencing batch reactors without enhanced biological phosphorus removal

2010 ◽  
Vol 61 (10) ◽  
pp. 2433-2441
Author(s):  
Guangxue Wu ◽  
Michael Rodgers
Keyword(s):  
Microbial Community ◽  
Nutrient Removal ◽  
Phosphorus Removal ◽  
Significant Proportion ◽  
Volume Index ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
Enhanced Biological Phosphorus Removal ◽  
Biological Phosphorus Removal ◽  
Biological Phosphorus

Nutrient removal, microbial community and sludge settlement were examined in two 3-litre laboratory-scale anaerobic/aerobic sequencing batch reactors (SBRs). One SBR was operated at 10°C and the other SBR at 20°C. Different from conventional enhanced biological phosphorus removal, most of the soluble sodium acetate was removed in the aerobic phase and no organic carbon uptake or biological phosphorus release occurred in the anaerobic phase. In this type of anaerobic/aerobic SBR, the phosphorus removal and sludge settlement seemed to be unstable, and the dominant microorganism was Zoogloea sp. Although no excess biological phosphorus removal occurred, extracellular phosphorus precipitation contributed a significant proportion to total phosphorus removed. Sludge volume index decreased with increasing phosphorus contents in the biomass under all conditions. The functions of extracellular polymeric substances in sludge settlement and phosphorus removal depended on the environmental conditions applied.

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