The Effect of Incomplete Denitrification on Anoxic-Aerobic (Low F/M) Filament Bulking in Nutrient Removal Activated Sludge Systems

Musvoto, E. V.; Casey, Tom; Ekama, George A.; Wentzel, M. C.; Marais, G. V. R.

doi:10.2166/wst.1994.0354

Cited by 11 publications

(4 citation statements)

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“…Casey et at. (] 992 and ]994) and Musvoto et at. (1994) have demonstrated that when denitrification in the anoxic reactor preceding the aerobic reactor is incomplete (that is, NO] and N0 2 -leak from the anoxic to aerobic reactors), then the anoxic-aerobic (AA, previously called low-F/M) filaments (for example, M. Parvicella, 0092, 0041, 0675) proliferate to cause bulking with diluted sludge volume indices (DSVls) in excess of 200 mUg; if denitrification is complete, then good sludge settleabilities are obtained with DSVls less than 100 mL/g.…”

Section: Filamentousmentioning

confidence: 98%

“…In Figure 2 it can be seen that the biodegradable COD comprises two fractions, the RBCOD and the slowly biodegradable COD (SBCOD). Experiments and experience have indicated that for South African wastewaters, the magnitude of BEPR is strongly linked to the influent RBCOD concentration and that thc SBCOD contributes negligibly to the growth of the poly-P organisms and, hence, to the BEPR (Nicholls et at., 1984;Pitman, 1991;and Wentzel et ai., 1994). With regard to the RBCOD, this also has two fractions, SCFAs (also called volatile fatty acids) and the non-SCFAs termed fermentable RBCOD (F-RBCOD).…”

Section: Autotrophs (Nitrifiers)mentioning

confidence: 99%

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Principles in the design of single‐sludge activated‐sludge systems for biological removal of carbon, nitrogen, and phosphorus

Wentzel¹,

Ekama²

1997

Water Environment Research

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The function of the single-sludge activated-sludge system has expanded from chemical oxygen demand (COD) removal to include, progressively, nitrification, denitrification, and phosphorus removal, all biological. With such complexity, design procedures based on fundamental behavioral patterns are required. The fundamental principles of a steady-state model for biological excess phosphorus removal (BEPR) that is based on the current understanding of the mechanisms of BEPR are described. The model can be used for design and to predict the expected system response under constant flow and load conditions. With the aid of the model, the influence of various parameters on the magnitude of phosphorus removal and the interactions between BEPR and nitrification and denitrification are examined. Principle variables that influence phosphorus removal are an influent wastewater characteristic-readily biodegradable chemical oxygen demand concentrationand process design parameters-anaerobic mass fraction and its subdivision and sludge age. Also, the model indicates that, in agreement with observations, preventing recycling of nitrate to the anaerobic reactor is one of the main considerations in design. Water Environ. Res., 69, 1222Res., 69, ( 1997. KEYWORDS:design, activated sludge, nitrogen, phosphorus, biological excess phosphorus removal, models.To comply with more stringent effluent legislation, the functions of the activated-sludge system have expanded to progressively include the biologica] removal of carbon (C), nitrogen (N), and phosphorus (P). Not only have these expansions increased the complexity of the system configuration and its operation, but concomitantly the number of biologica] processes influencing the effluent quality and the number of compounds involved in these processes have increased. With such complexities designs based on experience or semiempirical methods no longer will provide optimal performance, and design procedures based on more fundamental behavioral patterns are required. To meet this requirement, over the past two decades the research group at the University of Cape Town, South Africa, has developed steady-state design models based on a simplified conceptualization of the behavior of the activated-sludge system. These models have progressively included aerobic COO removal and nitrification (Oold et ai., 1980, andEkama, 1976), anoxic denitrification (Oold et at., ]991; van Haande] et at. , 198 I; and WRC, 1984), and anaerobic-anoxic-aerobic biological excess phosphorus removal (Wentzel et ai., 1990 and.The models enable system design and operational parameters to be readily identified, provide guidance in selecting values for these parameters, and quantify the expected behavior of the system.[n this paper, the steady-state design model of Wentzel et at. (1990) for bio]ogical excess phosphorus removal (BEPR) wi II be used (with the values for model constants given by Wentzel et at.) to evaluate the influence of various system parameters and wastewater characteristics on the system respons...

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Section: Filamentousmentioning

confidence: 98%

Section: Autotrophs (Nitrifiers)mentioning

confidence: 99%

Principles in the design of single‐sludge activated‐sludge systems for biological removal of carbon, nitrogen, and phosphorus

Wentzel¹,

Ekama²

1997

Water Environment Research

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“…Another possible reason for poor settleablity in the sole methanol addition run can be associated with the degree of denitrification. Casey et al (1992Casey et al ( , 1994 and Musvoto et al (1994) have shown that good sludge settleability was observed with complete denitrification, while filaments proliferate causing sludge bulking with high SVI when denitrification is incomplete. However, more tests related to hydrophicity and filamentous organisms are needed to support the present results clearly.…”

Section: Svimentioning

confidence: 99%

Effect of sequentially combining methanol and acetic acid on the performance of biological nitrogen and phosphorus removal

Cho

Molof²

2004

Journal of Environmental Management

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“…Magnesium hydroxide as a new type of water treatment agent has many advantages, such as harmless, easy to pumping and with high adsorption ability. Research shows that: magnesium hydroxide or magnesium salt could remove heavy metals, nitrogen and phosphorus effectively [4][5][6][7]. Comparing to magnesium hydroxide, nano magnesium hydroxide have higher practical value [8][9].…”

Section: Introductionmentioning

confidence: 99%

Preparation of Modified Expanded Graphite and its Adsorption Characteristics for Pb (II) and Cr (VI)

Zhao

et al. 2011

AMR

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The Effect of Incomplete Denitrification on Anoxic-Aerobic (Low F/M) Filament Bulking in Nutrient Removal Activated Sludge Systems

Cited by 11 publications

References 0 publications

Principles in the design of single‐sludge activated‐sludge systems for biological removal of carbon, nitrogen, and phosphorus

Principles in the design of single‐sludge activated‐sludge systems for biological removal of carbon, nitrogen, and phosphorus

Effect of sequentially combining methanol and acetic acid on the performance of biological nitrogen and phosphorus removal

Preparation of Modified Expanded Graphite and its Adsorption Characteristics for Pb (II) and Cr (VI)

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