Interaction of Different Groups of Micro-Organisms in Biological Phosphate Removal

Observations under continuous flow conditions in a bench-scale activated sludge unit and in full-scale nutrient removal activated sludge plants indicated that, despite relatively high numbers of Aoinetobaoter oalooaoetious, no enhanced biological phosphate removal was achieved. Total bacteriological analyses of the mixed liquor of these plants indicated that in all cases Aeromonas spp. were present in low numbers, particularly Aeromonas punotata. This bacterium is described as being able to produce acetate as one of its major fermentation end products. Phosphate uptake batch experiments using pure cultures showed that Aeromonas punotata enhances the phosphate uptake capability of Aoinetobaoter calooaoetious by converting carbohydrates present in the sewage to a substrate required for phosphate removal. It was shown that the anaerobic zone in a phosphate removing activated sludge plant is a fermentation reactor, where suitable substrates are generated rather than stress conditions imposed on the bacteria, a condition which was previously believed to be essential for enhanced phosphate uptake.

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Verification of anoxic phosphate uptake as the main biochemical mechanism of the “dephanox” process

Water Science & Technology ◽

10.2166/wst.1997.0365 ◽

1997 ◽

Vol 35 (10) ◽

pp. 87-94 ◽

Cited By ~ 7

Author(s):

R. Sorm ◽

J. Wanner ◽

R. Saltarelli ◽

G. Bortone ◽

A. Tilche

Keyword(s):

Activated Sludge ◽

Nutrient Removal ◽

Uptake Rate ◽

Phosphate Uptake ◽

Biochemical Mechanism ◽

Batch Experiments ◽

Batch Tests ◽

Genetic Probes ◽

Activated Sludge Systems ◽

Removal System

The phenomenon of anoxic phosphate uptake with simultaneous denitrification was studied. For this purpose kinetic batch tests have been carried out by using the activated sludge samples from three modifications of nutrient removal activated sludge systems: two based on an anaerobic-anoxic-oxic (A2/O) system and a third on an anaerobic-oxic (A/O) system. The results showed significant differences in anoxic phosphate uptake rate between activated sludge which was alternatively exposed to anoxic conditions and activated sludge from the A/O arrangement. These differences were also accompanied by different denitrification rates. Simultaneously with batch experiments the microscopic observation of activated sludge samples was carried out. Neisser and Gram stained samples showed clear differences in shape, size and distribution of polyphosphate accumulating bacteria between A2/O and A/O Processes. Moreover, experiments performed using genetic probes confirmed the differences in microbiological composition of activated sludge samples from different nutrient removal system arrangements.

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Effect of Supplemental Carbon Source on Phosphate Removal in an Alternating Activated Sludge Process

Water Science & Technology ◽

10.2166/wst.1993.0690 ◽

1993 ◽

Vol 28 (11-12) ◽

pp. 499-512 ◽

Cited By ~ 1

Author(s):

S. H. Isaacs ◽

M. Henze ◽

H. Søeberg ◽

M. Kümmel

Keyword(s):

Carbon Source ◽

Activated Sludge ◽

Nutrient Removal ◽

Pilot Plant ◽

Phosphate Uptake ◽

Phosphate Removal ◽

Activated Sludge Process ◽

Significant Release

Pilot plant studies indicate that the addition of COD in the form of acetate to an alternating nutrient removal activated sludge process as a means to improve denitrification rates is not detrimental to biological phosphate removal. This is in spite of the fact that the added acetate can cause a significant release of phosphate during the anoxic phases in the aeration tanks. The added COD also appears to result in increased rates of aerobic phosphate uptake, thus improving the phosphate removal ability of the process. These observations are presented and discussed in the paper.

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Examination of the Activated Sludge Model No. 2 with an alternating process

Water Science & Technology ◽

10.2166/wst.1995.0073 ◽

1995 ◽

Vol 31 (2) ◽

pp. 55-66 ◽

Cited By ~ 6

Author(s):

S. Isaacs ◽

J. A. Hansen ◽

K. Schmidt ◽

M. Henze

Keyword(s):

Activated Sludge ◽

Nutrient Removal ◽

Pilot Plant ◽

Pilot Scale ◽

Phosphate Removal ◽

Data Series ◽

Batch Experiments ◽

Phosphate Release ◽

Activated Sludge Model ◽

The Third

Three series of data obtained in a pilot-scale alternating-type activated sludge nutrient removal process are examined in light of the recently introduced Activated Sludge Model No. 2 (ASM2). The first data series was collected while adding acetate to the inlet to improve phosphate removal. ASM2 can explain why phosphate levels first rise before an improvement occurs based on a slow build-up of internally stored polyhydroxyalkanoates (PHA). The second and third data series represent batch experiments performed in the pilot plant, and show the effect of nitrate on phosphate release. ASM2 could describe the second data series well after including one additional reaction to account for denitrification by phosphate accumulating organisms. The third data series examines the effect of the rate of acetate addition, and shows that this affects the rate of anoxic phosphate release more strongly than it does the denitrification rate.

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Hypothesis for the Role of Nutrient Starvation in Biofilm Detachment

Applied and Environmental Microbiology ◽

10.1128/aem.70.12.7418-7425.2004 ◽

2004 ◽

Vol 70 (12) ◽

pp. 7418-7425 ◽

Cited By ~ 170

Author(s):

Stephen M. Hunt ◽

Erin M. Werner ◽

Baochuan Huang ◽

Martin A. Hamilton ◽

Philip S. Stewart

Keyword(s):

Continuous Flow ◽

Large Cell ◽

Nutrient Starvation ◽

Flow Conditions ◽

Cell Clusters ◽

Theoretical Approaches ◽

Biofilm Detachment ◽

Pure Cultures ◽

Potential Trigger

ABSTRACT A combination of experimental and theoretical approaches was used to investigate the role of nutrient starvation as a potential trigger for biofilm detachment. Experimental observations of detachment in a variety of biofilm systems were made with pure cultures of Pseudomonas aeruginosa. These observations indicated that biofilms grown under continuous-flow conditions detached after flow was stopped, that hollow cell clusters were sometimes observed in biofilms grown in flow cells, and that lysed cells were apparent in the internal strata of colony biofilms. When biofilms were nutrient starved under continuous-flow conditions, detachment still occurred, suggesting that starvation and not the accumulation of a metabolic product was responsible for triggering detachment in this particular system. A cellular automata computer model of biofilm dynamics was used to explore the starvation-dependent detachment mechanism. The model predicted biofilm structures and dynamics that were qualitatively similar to those observed experimentally. The predicted features included centrally located voids appearing in sufficiently large cell clusters, gradients in growth rate within these clusters, and the release of most of the biofilm with simulated stopped-flow conditions. The model was also able to predict biofilm sloughing resulting solely from this detachment mechanism. These results support the conjecture that nutrient starvation is an environmental cue for the release of microbes from a biofilm.

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Phosphate removal using aerobic bacterial consortium and pure cultures isolated from activated sludge

Process Safety and Environmental Protection ◽

10.1016/j.psep.2015.03.011 ◽

2015 ◽

Vol 95 ◽

pp. 237-246 ◽

Cited By ~ 21

Author(s):

Leyla Benammar ◽

Taha Menasria ◽

Ammar Ayachi ◽

Messaoud Benounis

Keyword(s):

Activated Sludge ◽

Bacterial Consortium ◽

Phosphate Removal ◽

Pure Cultures

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Amount and nature of soluble refractory organics produced by activated sludge micro-organisms in sequencing batch and continuous flow reactors

Water Science & Technology ◽

10.1016/s0273-1223(96)00875-x ◽

1997 ◽

Vol 35 (1) ◽

Cited By ~ 11

Keyword(s):

Activated Sludge ◽

Continuous Flow ◽

Flow Reactors ◽

Continuous Flow Reactors ◽

Micro Organisms ◽

Refractory Organics

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Phosphate uptake under anoxic conditions and fixed-film nitrification in nutrient removal activated sludge system

Water Research ◽

10.1016/0043-1354(95)00331-2 ◽

1996 ◽

Vol 30 (7) ◽

pp. 1573-1584 ◽

Cited By ~ 41

Author(s):

R. S̆orm ◽

G. Bortone ◽

R. Saltarelli ◽

P. Jeníc̆ek ◽

J. Wanner ◽

...

Keyword(s):

Activated Sludge ◽

Nutrient Removal ◽

Phosphate Uptake ◽

Anoxic Conditions ◽

Activated Sludge System ◽

Fixed Film

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The effect of chemical bulking control on biological nutrient removal in a full scale activated sludge plant

Water Science & Technology ◽

10.2166/wst.1996.0441 ◽

1996 ◽

Vol 34 (3-4) ◽

pp. 275-282 ◽

Cited By ~ 5

Author(s):

G. B. Saayman ◽

C. F. Schutte ◽

J. van Leeuwen

Keyword(s):

Hydrogen Peroxide ◽

Activated Sludge ◽

Nutrient Removal ◽

Pilot Scale ◽

Full Scale ◽

City Council ◽

Phosphate Removal ◽

Biological Nutrient Removal ◽

Removal Processes ◽

The City

The use of chemicals for sludge bulking control has a direct effect on the biological nutrient removal processes in activated sludge systems designed for this purpose. Chlorine has been used on full scale but information on the use of ozone and hydrogen peroxide is limited to pilot scale tests. The objective of this study was to investigate the effects of chlorine, ozone and hydrogen peroxide on nutrient removal processes when used on a continuous basis for bulking control in a full scale biological nutrient removal activated sludge plant. The full scale studies were conducted over a period of 39 months at the Daspoort sewage works of the City Council of Pretoria. The results indicate that at low dosages the oxidants have limited effects on the nutrient removal processes but at higher levels chlorine had a detrimental effect resulting in the phosphate limit of 1 mg P.1−1 being exceeded. It is concluded that chlorine is the most effective of the three oxidants for bulking control, but that it should be used with caution in order not to upset the biological phosphate removal processes. Ozone at low levels had a small but consistent positive effect on bulking control as well as on nutrient removal. The effects of hydrogen peroxide were very small except at high dosages.

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Comparison of Biocenoses from Continuous and Sequencing Batch Reactors

Water Science & Technology ◽

10.2166/wst.1992.0126 ◽

1992 ◽

Vol 25 (6) ◽

pp. 239-249 ◽

Cited By ~ 14

Author(s):

J. Wanner

Keyword(s):

Activated Sludge ◽

Nutrient Removal ◽

Continuous Flow ◽

Sequencing Batch Reactor ◽

Flow System ◽

Batch Reactor ◽

Continuous Reactor ◽

Batch Reactors ◽

Sequencing Batch Reactors ◽

Filamentous Microorganisms

Sequencing batch reactors (SBR) are often used for research on nutrient removal systems. A model anaerobic-oxic SBR was compared with a compartmentalized continuous-flow system. The levels of COD, phosphorus, and nitrogen removal in both systems were comparable but the biocenoses differed significantly. The SVI values of activated sludge from the continuous reactor ranged between 100 and 200 ml/g although no significant occurrence of filamentous microorganisms was observed. The sequencing batch reactor produced activated sludge with the SVIs below 100 ml/g and with high settling velocities. Filamentous microorganisms were frequently observed in the biocenosis of the SBR. The differences in settling properties and filamentous growth in both reactors are discussed and explained.

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