The influence of a particulate substrate on filamentous bulking and phosphorus removal in activated sludge systems

1991 ◽  
Vol 25 (9) ◽  
pp. 1161 ◽  
Author(s):  
Jan Chudoba
Keyword(s):  
Activated Sludge ◽  
Phosphorus Removal ◽  
Filamentous Bulking ◽  
Activated Sludge Systems

Difficulties and developments in biological nutrient removal technology and modelling

1999 ◽  
Vol 39 (6) ◽  
pp. 1-11 ◽  
Author(s):  
George A. Ekama ◽  
Mark C. Wentzel
Keyword(s):  
Activated Sludge ◽  
Nutrient Removal ◽  
P Uptake ◽  
Biological Nutrient Removal ◽  
Filamentous Bulking ◽  
Recent Developments ◽  
Removal Technology ◽  
Hydrolysis Of ◽  
Activated Sludge Systems ◽  
P Removal

Filamentous bulking and the long sludge age required for nitrification are two important factors that limit the wastewater treatment capacity of biological nutrient removal (BNR) activated sludge systems. A growing body of observations from full-scale plants indicate support for the hypothesis that a significant stimulus for filamentous bulking in BNR systems in alternating anoxic-aerobic conditions with the presence of oxidized nitrogen at the transition from anoxic to aerobic. In the DEPHANOX system, nitrification takes place externally allowing sludge age and filamentous bulking to be reduced and increases treatment capacity. Anoxic P uptake is exploited in this system but it appears that this form of biological excess P removal (BEPR) is significantly reduced compared with aerobic P uptake in conventional BNR systems. Developments in the understanding of the BEPR processes of (i) phosphate accumulating organism (PAO) denitrification and anoxic P uptake, (ii) fermentation of influent readily biodegradable (RB)COD and (iii) anaerobic hydrolysis of slowly biodegradable (SB)COD are evaluated in relation to the IAWQ Activated Sludge Model (ASM) No.2. Recent developments in BEPR research do not yet allow a significant improvement to be made to ASM No. 2 that will increase its predictive power and reliability and therefore it remains essentially as a framework to guide further research.

Design of nutrient removal activated sludge systems

2003 ◽  
Vol 47 (11) ◽  
pp. 115-122 ◽  
Author(s):  
J. Manga ◽  
J. Ferrer ◽  
A. Seco ◽  
F. Garcia-Usach
Keyword(s):  
Mathematical Model ◽  
Activated Sludge ◽  
Nutrient Removal ◽  
Phosphorus Removal ◽  
Pilot Plant ◽  
Enhanced Biological Phosphorus Removal ◽  
Biological Phosphorus Removal ◽  
User Friendly ◽  
Biological Phosphorus ◽  
Activated Sludge Systems

A mechanistic mathematical model for nutrient and organic matter removal was used to describe the behavior of a nitrification denitrification enhanced biological phosphorus removal (NDEBPR) system. This model was implemented in a user-friendly software DESASS (design and simulation of activated sludge systems). A 484-L pilot plant was operated to verify the model results. The pilot plant was operated for three years over three different sludge ages. The validity of the model was confirmed with data from the pilot plant. Also, the utility of DESASS as a valuable tool for designing NDEBPR systems was confirmed.

A Hypothesis for the Causes and Control of Anoxic-Aerobic (AA) Filament Bulking in Nutrient Removal Activated Sludge Systems

1994 ◽  
Vol 29 (7) ◽  
pp. 203-212 ◽  
Author(s):  
T. G. Casey ◽  
M. C. Wentzel ◽  
G. A. Ekama ◽  
R. E. Loewenthal ◽  
GvR Marais
Keyword(s):  
Nitric Oxide ◽  
Literature Review ◽  
Activated Sludge ◽  
Nutrient Removal ◽  
Phosphorus Removal ◽  
Laboratory Research ◽  
Biochemical Pathways ◽  
And Control ◽  
Aerobic Zone ◽  
Activated Sludge Systems

From laboratory research and a literature review of the biochemical pathways of aerobic-facultative heterotrophic organisms, an hypothesis is proposed for the proliferation of anoxic-aerobic (AA) filamentous organisms in nitrification-denitrification (ND) and nitrification-denitrification biological excess phosphorus removal (NDBEPR) systems. In activated sludge, under anoxic conditions floc-forming organisms execute the denitrification of nitrate (NO3−) through each of the denitrification intermediates to dinitrogen (N2), in the process of which the intermediate nitric oxide (NO) is accumulated intracellularly. Intracellular NO is inhibitory to the utilization of oxygen in the subsequent aerobic zone. In contrast, the filamentous organisms execute only part of the denitrification pathway, i.e. the reduction of NO3− to NO2−; they do not accumulate NO and hence are not inhibited in the subsequent aerobic zone. Thus in anoxic-aerobic systems, floc-formers are placed at a disadvantage in the aerobic zone giving an advantage to the filaments in the competition for substrate. Experimental evidence to support this hypothesis is presented and a tentative proposal of a strategy for control of AA filament proliferation is described and tested experimentally.

The Selector Effect on Filamentous Bulking in Long Sludge Age Activated Sludge Systems

1991 ◽  
Vol 23 (4-6) ◽  
pp. 867-877 ◽  
Author(s):  
D. M. D. Gabb ◽  
D. A. Still ◽  
G. A. Ekama ◽  
D. Jenkins ◽  
G. v. R. Marais
Keyword(s):  
Activated Sludge ◽  
Phosphorus Removal ◽  
Sufficient Conditions ◽  
Extensive Investigation ◽  
Intermittent Aeration ◽  
Nitrogen And Phosphorus ◽  
Nitrogen And Phosphorus Removal ◽  
Aeration System ◽  
Microthrix Parvicella ◽  
Activated Sludge Systems

A survey of long sludge age activated sludge plants in South Africa showed that bulking was widespread in nitrogen and nitrogen and phosphorus removal plants with the dominant causative filamentous organisms being the low F/M types 0092, 0675, 0041, Microthrix parvicella, 0914 and 1851. The literature suggests that in aerobic systems proliferation of the low F/M filaments can be controlled by aerobic selector reactors. From an extensive investigation into the selector reactors, and the effect these stimulate, it was concluded that in long sludge age systems, irrespective of whether or not a selector effect is present in the sludge, (1) under completely aerobic conditions low F/M filaments do not proliferate, (2) sequential or alternating anoxic-aerobic periods like intermittent aeration are necessary, though not sufficient, conditions for the proliferation of low F/M filaments, and (3) an aerobic selector installed on an intermittent aeration system did not control low F/M filament proliferation.

The Activated Sludge Model No. 2: biological phosphorus removal

1995 ◽  
Vol 31 (2) ◽  
pp. 1-11 ◽  
Author(s):  
W. Gujer ◽  
M. Henze ◽  
T. Mino ◽  
T. Matsuo ◽  
M. C. Wentzel ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Phosphorus Removal ◽  
Biological Nutrient Removal ◽  
Final Report ◽  
Full Model ◽  
Biological Phosphorus Removal ◽  
Activated Sludge Model ◽  
Further Development ◽  
Biological Phosphorus ◽  
Activated Sludge Systems

The Activated Sludge Model No. 2 is introduced as a further development of Activated Sludge Model No. 1. Model No. 2 introduces phosphorus accumulating organisms (PAO) and allows us to simulate the behaviour of biological nutrient removal activated sludge systems. Typical wastewater composition and a set of stoichiometric and kinetic parameters are provided in order to make reasonable predictions. The model has not yet been calibrated or verified in any full-scale application. This report contains a simplified version of the full Model No. 2; the full model is published in the final report of the Task Group (Henze et al., 1994).

Sign in / Sign up

Export Citation Format

Share Document