Analysis of phosphorus removal and anaerobic selector performance in a full-scale activated sludge process in Singapore

2006 ◽  
Vol 54 (8) ◽  
pp. 237-246 ◽  
Author(s):  
Y.S. Cao ◽  
C.M. Ang ◽  
K.S. Raajeevan ◽  
A.K. Kiran ◽  
K.C. Lai ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Phosphorus Removal ◽  
Volatile Fatty Acids ◽  
P Uptake ◽  
Full Scale ◽  
Volume Index ◽  
Activated Sludge Process ◽  
Biological Phosphorus Removal ◽  
P Release ◽  
Sludge Settleability

This paper analyses the performance of the anaerobic selector (A/O process) in a full-scale activated sludge process receiving mostly industrial sewage discharge (>60%) in Singapore. In addition to the sludge settleability, enhanced biological phosphorus removal (EBPR) was studied. The sludge volume index (SVI) reduced from 200 to 80 ml g−1 and foaming was suppressed significantly, indicating the effectiveness of the anaerobic selector in improving sludge settleability. The phosphorus removal efficiency was 66%, and 7.5 mg HAc-COD was consumed per mg PO3−4-P removed. In the anaerobic compartment, 31% of the SCOD and 73% of the acetic acid in the settled sewage were removed with PO3−4-P release of 14.1 mg PO3−4-P l −1. The linear correlation between PO3−4-P release in the anaerobic compartment and PO3−4-P uptake in the aerobic compartment indicates that there is about 0.8 mg PO3−4-P release in the anaerobic compartment per mg PO3−4-P uptake in the aerobic compartment. The fates of volatile fatty acids (VFAs) and its short chain acids (SCAs) in the process were studied and discussed.

Enhanced biological phosphorus removal in the retrofitting from an anoxic selector to an anaerobic selector in a full-scale activated sludge process in Singapore

2009 ◽  
Vol 59 (5) ◽  
pp. 857-865 ◽  
Author(s):  
Y. Cao ◽  
C. M. Ang ◽  
K. C. Chua ◽  
F. W. Woo ◽  
H. Chi ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Phosphorus Removal ◽  
Oxygen Demand ◽  
P Uptake ◽  
Full Scale ◽  
Activated Sludge Process ◽  
Enhanced Biological Phosphorus Removal ◽  
Biological Phosphorus Removal ◽  
Biological Phosphorus ◽  
Final Effluent

This paper presents the investigation results of retrofitting an anoxic selector to an anaerobic selector through stepwise reduction of air supply in a full-scale activated sludge process with a focus on enhanced biological phosphorus removal (EBPR). The process experienced gradual shift from a Ludzack-Ettinger (LE) to an anaerobic-anoxic-oxic (A2O) process and subsequently, an anaerobic-oxic (A/O) process. The major findings are: (i) the average influent-based PO43−-P release in the anaerobic selector compartment was 16.3 mg P l−1 and that in the secondary clarifier was 1.7 mg P l−1. 75% of the SCOD and 93% of the acetic acid in the primary effluent were taken up in the anaerobic selector compartment, respectively; (ii) PO43−-P uptake contributed by both aerobic and denitrifying phosphorus accumulating organisms (DPAOs) occurred mainly in the first and second aerobic lanes together with simultaneous nitrification and denitrification (SND) while there was not much contribution from the last aerobic lane; (iii) The average PO43−-P concentration of the final effluent was 2.4 mg P l−1 corresponding to a removal efficiency of 85%; (iv) the SVI was satisfactory after retrofitting; and (v) the increase of NH4+-N in the final effluent from the commencement to the completion of the retrofitting resulted in an approximate 40–50% reduction in oxygen demand and a significant aeration energy saving was achieved.

Excess biological phosphorus removal in the activated sludge process using primary sludge fermentation

1986 ◽  
Vol 13 (3) ◽  
pp. 345-351 ◽  
Author(s):  
B. Rabinowitz ◽  
W. K. Oldham
Keyword(s):  
Fatty Acids ◽  
Activated Sludge ◽  
Phosphorus Removal ◽  
Volatile Fatty Acids ◽  
Phosphorus Release ◽  
Activated Sludge Process ◽  
Removal Mechanism ◽  
Biological Phosphorus Removal ◽  
Primary Sludge ◽  
Biological Phosphorus

This paper examines the role of short-chain volatile fatty acids in the excess biological phosphorus removal mechanism of the activated sludge process. The effectiveness of various substrate additions in inducing phosphorus removal was investigated through a series of laboratory and pilot-scale experiments. Phosphorus release and substrate uptake both take place in the anaerobic zone of the process and there appears to be an exchange phenomenon that occurs between the two molecules. The system phosphorus removal of the process is improved by the addition of sodium acetate to the anaerobic zone. It is important that the zone receives no incoming nitrate, as the added substrate will be oxidized in the denitrification reaction, rendering it unavailable for the phosphorus removal mechanism. Acetate and propionate, the two substrates that are most effective in inducing anaerobic phosphorus release, can be generated on-site at a treatment plant by primary sludge fermentation in concentrations sufficient to significantly enhance the phosphorus removal characteristics of the process. Key words: biological phosphorus removal, short-chain volatile fatty acids, phosphorus release, substrate utilization, primary sludge fermentation.

Full Scale Investigations on Enhanced Biological Phosphorus Removal – P-Release in the Anaerobic Reactor

1994 ◽  
Vol 29 (7) ◽  
pp. 153-156 ◽  
Author(s):  
D. Wedi ◽  
P. A. Wilderer
Keyword(s):  
Phosphorus Removal ◽  
Full Scale ◽  
Process Conditions ◽  
Enhanced Biological Phosphorus Removal ◽  
Biological Phosphorus Removal ◽  
Anaerobic Reactor ◽  
P Release ◽  
Acinetobacter Sp ◽  
Biological Phosphorus ◽  
P Removal

Most of the fundamental processes responsible for enhanced biological phosphorus removal (EBPR) were obtained through laboratory tests under defined conditions with pure or enriched cultures. Acinetobacter sp. was identified as the most important group of bacteria responsible for bio-P removal. Full scale data showed, however, that laboratory results do not match full scale results well enough. There is a lack of data on the effects of sub-optimal process conditions such as inadequate availability of volatile fatty acids (VFA), high nitrate recycle, storm water inflow or low temperatures. In this paper the results of full scale experiments on P-release are presented and compared with theoretical values. Measurements at a full scale Phoredox-system showed a surprisingly low P-release in the anaerobic reactor. Only 4 to 10% of the phosphorus in the activated sludge was released in the bulk liquid. With laboratory batch-tests, a maximum of 20% of the P in the sludge could be released. It is assumed that under the prevailing process conditions either the fraction of Acinetobacter sp. was very small, or bacteria other than Acinetobacter sp. were responsible for the P-removal, or most of the phosphorus was bound chemically but mediated by biological processes.

Combined denitrification and excess biological phosphorus removal in discontinuous operated biofilm systems

2002 ◽  
Vol 46 (4-5) ◽  
pp. 193-200 ◽  
Author(s):  
D. Brandt ◽  
C. Sieker ◽  
W. Hegemann
Keyword(s):  
Phosphorus Removal ◽  
P Uptake ◽  
Organic Substrate ◽  
Treated Wastewater ◽  
Biological Phosphorus Removal ◽  
P Release ◽  
Different Types ◽  
Immobilized Biomass ◽  
Biological Phosphorus ◽  
P Removal

The sorption-denitrification-P-removal (S-DN-P) process combines biological excess P-removal (BEPR) and denitrification using immobilized biomass. The accumulation of denitrifying polyP organisms is achieved by sequencing anaerobic/anoxic conditions. The immobilized biomass is in alternating contact with primary treated wastewater (anaerobic sorption-phase) and nitrified wastewater (denitrification phase). In the sorption phase, P-release takes place and readily biodegradable organic substrate, e.g. volatile fatty acid, is taken up and stored by polyP accumulating organisms (PAO). In addition to this, other organic matter is physically/chemically adsorbed in the biofilm structures. In the denitrification phase, the biomass denitrifies the stored and adsorbed organic substrate and, at the same time, P-uptake and polyP formation occurs. This paper presents results of investigations at laboratory and half-technical scale. At laboratory scale different types of carriers were tested regarding their suitability for the S-DN-P-process. In half-technical scale a biofilter and a moving bed reactor (MBR) were tested. In the biofilter a stable removal of nitrate and phosphate was achieved. However, it was not possible to achieve similar results in the MBR process. Especially the release and uptake of phosphate showed no clear tendency although the uptake of acetate was good. Reasons for this could be the accumulation of glycogen accumulating organisms which impair the metabolism of PAO.

Effect of continuous addition of an organic substrate to the anoxic phase on biological phosphorus removal

1998 ◽  
Vol 38 (1) ◽  
pp. 97-105 ◽  
Author(s):  
J. Meinhold ◽  
H. Pedersen ◽  
E. Arnold ◽  
S. Isaacs ◽  
M. Henze
Keyword(s):  
Phosphorus Removal ◽  
Phosphate Uptake ◽  
P Uptake ◽  
Organic Substrate ◽  
Organic Substrates ◽  
Biological Phosphorus Removal ◽  
P Release ◽  
Influence Of Substrate ◽  
Biological Phosphorus ◽  
P Removal

The continuous introduction of a biological phosphorus removal (BPR) promoting organic substrate to the denitrifying reactor of a BPR process is examined through a series of batch experiments using acetate as model organic substrate. Several observations are made regarding the influence of substrate availability on PHA storage/utilization and phosphate uptake/release. Under anoxic conditions PHB is utilized and phosphate is taken up, indicating that at least a fraction of the PAO can denitrify. The rates of anoxic P-uptake, PHB utilization and denitrification are found to increase with increasing initial PHB level. At low acetate addition rates the P-uptake and PHB utilization rates are reduced compared to when no acetate is available. At higher acetate addition rates a net P-release occurs and PHB is accumulated. For certain intermediate acetate addition rates the PHB level can increase while a net P-release occurs. Whether the introduction of BPR promoting organic substrates to the denitrifying reactor is detrimental to overall P-removal appears to be dependent on the interaction between aerobic P-uptake, which is a function of PHB level, and the aerobic residence time.

Full-Scale Cyclic Activated Sludge System Phosphorus Removal

1992 ◽  
Vol 26 (9-11) ◽  
pp. 2253-2256 ◽  
Author(s):  
M. C. Goronszy
Keyword(s):  
Activated Sludge ◽  
Phosphorus Removal ◽  
Full Scale ◽  
Biological Phosphorus Removal ◽  
Fill Ratio ◽  
Variable Volume ◽  
Activated Sludge System ◽  
Sludge Bulking ◽  
Volume Mode ◽  
Biological Phosphorus

The performance of three full-scale cyclic activated sludge facilities, operated for biological phosphorus removal is demonstrated. The facilities are operated without formal mixed anoxic or anaerobic sequences in a variable volume mode. The system is independent of fill-ratio operation for filamentous sludge bulking control.

Background to Biological Phosphorus Removal

1983 ◽  
Vol 15 (3-4) ◽  
pp. 1-13 ◽  
Author(s):  
James L Barnard
Keyword(s):  
Activated Sludge ◽  
Phosphorus Removal ◽  
Plug Flow ◽  
Full Scale ◽  
Biological Phosphorus Removal ◽  
Anaerobic Conditions ◽  
Paper Briefly ◽  
Nitrogen And Phosphorus ◽  
Nitrogen And Phosphorus Removal ◽  
Biological Phosphorus

This paper briefly summarizes the early work on phosphorus removal in activated sludge plants in the U.S.A. and observed that such removals only occurred in low SRT plants of the plug flow type and in the Phostrip plants, neither designed for full nitrification. The discovery of simultaneous nitrogen and phosphorus removal, as well as full-scale experiments are discussed. The Phoredox process was proposed utilizing internal recycling for the removal of nitrates and an anaerobic first stage in which the incoming feed is used to obtain the necessary anaerobic conditions, essential as a conditioning step for the uptake of phosphorus. Proposed mechanisms are discussed.

Applicability of experience from laboratory reactors with biological phosphorus removal in full-scale plants

2006 ◽  
Vol 54 (1) ◽  
pp. 267-275 ◽  
Author(s):  
E. Tykesson ◽  
L.L. Blackall ◽  
Y. Kong ◽  
P.H. Nielsen ◽  
J. la Cour Jansen
Keyword(s):  
Phosphorus Removal ◽  
Wastewater Treatment Plants ◽  
In Situ Hybridisation ◽  
Full Scale ◽  
Fluorescence In Situ Hybridisation ◽  
Biological Phosphorus Removal ◽  
Batch Tests ◽  
P Release ◽  
Biological Phosphorus

Enhanced biological phosphorus removal (EBPR) has been used at many wastewater treatment plants all over the world for many years. In this study a full-scale sludge with good EBPR was tested with P-release batch tests and combined FISH/MAR (fluorescence in situ hybridisation and microautoradiography). Proposed models of PAOs and GAOs (polyphosphate- and glycogen-accumulating organisms) and microbial methods suggested from studies of laboratory reactors were found to be applicable also on sludge from full-scale plants. Dependency of pH and the uptake of both acetate and propionate were studied and used for calculations for verifying the models and results from microbial methods. All rates found from the batch tests with acetate were higher than in the batch tests with propionate, which was explained by the finding that only those parts of the bacterial community that were able to take up acetate anaerobically were able to take up propionate anaerobically.

Experience from 10 years of full-scale operation with enhanced biological phosphorus removal at Öresundsverket

2005 ◽  
Vol 52 (12) ◽  
pp. 151-159 ◽  
Author(s):  
E. Tykesson ◽  
L.-E. Jönsson ◽  
J. la Cour Jansen
Keyword(s):  
Phosphorus Removal ◽  
Volatile Fatty Acids ◽  
Stable Process ◽  
Full Scale ◽  
Phosphorus Concentration ◽  
Enhanced Biological Phosphorus Removal ◽  
Biological Phosphorus Removal ◽  
Sludge Hydrolysis ◽  
Low Levels ◽  
Biological Phosphorus

Ten years of full-scale experience with enhanced biological phosphorus removal (EBPR) has been evaluated. During the start-up period lack of carbon source was the main operational problem and a higher level of volatile fatty acids was secured by introducing a primary sludge hydrolysis. Acidic thermal sludge hydrolysis was used as the sludge treatment method at the plant during about three years. One effluent stream, rich in carbon and precipitant, was brought back to the process leading to an improvement of the phosphorus removal both by an improved biological process and chemical precipitation. A quite stable process of EBPR was developed with low levels of effluent phosphorus concentration. Stringent effluent discharge limits during short evaluation periods necessitated a continued work for improvement of the short-term stability. During periods with lack of carbon, such as industrial holiday or rainy periods, both simultaneous precipitation and reduced aeration have been successfully tested as strategies for securing low levels of effluent phosphorus.

Improved Biological Phosphorus Removal Resulting from the Enrichment of Reactor Feed with Fermentation Products

1992 ◽  
Vol 26 (5-6) ◽  
pp. 943-953 ◽  
Author(s):  
L. H. Lötter ◽  
A. R. Pitman
Keyword(s):  
South Africa ◽  
Fatty Acids ◽  
Activated Sludge ◽  
Phosphorus Removal ◽  
Volatile Fatty Acids ◽  
Phosphate Removal ◽  
Biodegradable Materials ◽  
Biological Phosphorus Removal ◽  
Fermentation Products ◽  
Biological Phosphorus

Research in South Africa has highlighted the dependence of biological phosphate removal mechanisms on the presence of certain minimum concentrations of some readily biodegradable materials including interalia volatile fatty acids. Successful generation of these compounds has been achieved at recently commissioned facilities at three of Johannesburg' activated sludge plants. Elutriation of the volatile fatty acids from the sludge was achieved by recycling sludge to the influent sewage stream. Significant improvements in phosphate removal were observed, thus reducing the demand for chemical dosing to achieve the phosphate standard. In this paper the effect of altering the feed sewage characteristics on biological phosphorus removal is discussed.

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