Conditions Favoring Proliferation of Glycogen Accumulating Organisms for Excess Biological Carbon Removal in Treating Nutrient Deficient Wastewater

Impact of marginal availability and severe deficiency of nitrogen on the growth of glycogen accumulating organisms (GAOs) and performance of anaerobic/aerobic activated sludge systems treating nutrient deficient wastewater was investigated at marginal availability and severe deficiency of phosphorus. Two continuous-flow lab-scale systems were operated simultaneously fed by model winery wastewater, one with marginal availability and the other one at severe deficiency of nitrogen. In the second experimental stage, marginal availability of P was converted into severe deficiency by interrupting external dosing.Common practice of dosing N- and P-sources to marginal availability caused enhanced proliferation of filamentous bacteria leading to poor biomass settling and instable operation. At marginal N-availability accumulation of GAOs started when conditions became deficient for phosphorus. In severe lack of nitrogen GAOs overgrew filaments, and outcompeted phosphorous accumulating organisms (PAOs) initially present in the seed. Stable and good performance could be maintained even after withdrawal of phosphorous dosing.

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Occurrence and significance of filamentous bacteria in pulp and paper activated sludge systems

Water Science & Technology ◽

10.2166/wst.2004.0159 ◽

2004 ◽

Vol 50 (3) ◽

pp. 39-48 ◽

Cited By ~ 4

Author(s):

J. Bergeron ◽

C. Pelletier

Keyword(s):

Activated Sludge ◽

Pulp And Paper ◽

Batch Reactors ◽

Nutrient Deficiencies ◽

Filamentous Bacteria ◽

Growth Type ◽

Conventional Activated Sludge ◽

Mode Of Operation ◽

Activated Sludge Systems ◽

P Sources

A microbial survey of 27 activated sludge (AS) systems included 16 conventional activated sludge (CAS) systems, five sequential batch reactors (SBR) and six oxygen-activated sludge (OAS) systems, all treating pulp and paper effluents. The most prevalent filaments observed were Thiothrix (26%) and Type 021N (22%). The designs of the activated sludge systems seemed to have an effect on the filament types. We found Thiothrix to be the most common filament associated with bulking. For CAS systems, a completely mixed mode of operation promoted Thiothrix and Type 021N growth. Type 021N was favoured in CAS systems with food to microorganism (F/M) ratios higher than 0.2, and with dissolved oxygen (DO) residuals higher than 2 ppm, while Thiothrix generally proliferated at lower F/M ratio and DO residuals. Nutrient deficiencies as well as nutrient dosage variations were suspected in most of the systems having Thiothrix and Type 021N as the most prevalent filaments. Thiothrix appeared to prefer polyphosphate and/or ammonia rather than urea/phosphoric acid as N and P sources. Systems with aerobic selectors showed the lowest filament counts, while systems with no selectors showed the highest filament counts.

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Validation of a new image analysis procedure for quantifying filamentous bacteria in activated sludge

Water Science & Technology ◽

10.2166/wst.2014.296 ◽

2014 ◽

Vol 70 (6) ◽

pp. 955-963 ◽

Cited By ~ 4

Author(s):

Ewa Liwarska-Bizukojc ◽

Marcin Bizukojc ◽

Olga Andrzejczak

Keyword(s):

Image Processing ◽

Image Analysis ◽

Activated Sludge ◽

Analysis Procedure ◽

Automated Image Analysis ◽

Filamentous Bacteria ◽

Image Processing And Analysis ◽

Manual Counting ◽

Analysis Application ◽

Activated Sludge Systems

Quantification of filamentous bacteria in activated sludge systems can be made by manual counting under a microscope or by the application of various automated image analysis procedures. The latter has been significantly developed in the last two decades. In this work a new method based upon automated image analysis techniques was elaborated and presented. It consisted of three stages: (a) Neisser staining, (b) grabbing of microscopic images, and (c) digital image processing and analysis. This automated image analysis procedure possessed the features of novelty. It simultaneously delivered data about aggregates and filaments in an individual calculation routine, which is seldom met in the procedures described in the literature so far. What is more important, the macroprogram performing image processing and calculation of morphological parameters was written in the same software which was used for grabbing of images. Previously published procedures required using two different types of software, one for image grabbing and another one for image processing and analysis. Application of this new procedure for the quantification of filamentous bacteria in the full-scale as well as laboratory activated sludge systems proved that it was simple, fast and delivered reliable results.

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The effect of low sludge age on wastewater fractionation (SS, SI)

Water Science & Technology ◽

10.2166/wst.2003.0606 ◽

2003 ◽

Vol 47 (11) ◽

pp. 203-209 ◽

Cited By ~ 25

Author(s):

S. Haider ◽

K. Svardal ◽

P.A. Vanrolleghem ◽

H. Kroiss

Keyword(s):

Activated Sludge ◽

Maximum Growth ◽

Maximum Growth Rate ◽

The Other ◽

Second Stage ◽

Lower Maximum ◽

The Difference ◽

Selection Of ◽

Activated Sludge Systems ◽

Raw Wastewater

In lab-scale experiments at the 2-stage activated sludge pilot plant of Vienna's central WWTP it is shown that the wastewater soluble COD concentration, which is inert to a sludge with SRT < 1 d (SIA) is about double compared to the SI concentration in sludge with SRT > 10 d (SIB). Unexpectedly the ratio of SIA/SIB is independent of the sludge age between SRTs of 0.4 and 1.0 days. The difference between the two SI fractions is soluble COD that is readily biodegradable by the sludge with SRT > 10 d. However, it is degraded at a lower maximum growth rate. These results comply with earlier results gained with different methods and at different WWTPs. It is hypothesised that very low sludge ages result in a selection of fast growing bacteria, which can utilise only part of the SS in the raw wastewater. The other part of SS therefore remains in the wastewater and can thus be utilised for enhanced denitrification in the second stage. It is still unknown beyond which sludge age the soluble inert COD SIA starts to decrease, finally reaching the value SIB for low loaded systems (SRT > 5 days). From this point on SI and SS are assumed only to depend on the wastewater composition and not on the sludge age. The assumption of the Activated Sludge Model No.1 that the biodegradable fractions can be modelled as a single substrate and by a single removal kinetic (one Monod term) appears not to be applicable for low sludge ages. Some suggestions for mathematical modelling, design and operation of 2-stage activated sludge systems are given.

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Investigation of triclosan fate and toxicity in continuous-flow activated sludge systems

Chemosphere ◽

10.1016/j.chemosphere.2007.01.047 ◽

2007 ◽

Vol 68 (2) ◽

pp. 375-381 ◽

Cited By ~ 63

Author(s):

Athanasios S. Stasinakis ◽

Anastasios V. Petalas ◽

Daniel Mamais ◽

Nikolaos S. Thomaidis ◽

Georgia Gatidou ◽

...

Keyword(s):

Activated Sludge ◽

Continuous Flow ◽

Activated Sludge Systems

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Modelling seasonal dynamics of Microthrix parvicella

Water Science & Technology ◽

10.2166/wst.2006.387 ◽

2006 ◽

Vol 54 (1) ◽

pp. 189-198 ◽

Cited By ~ 6

Author(s):

T. Hug ◽

W. Gujer ◽

H. Siegrist

Keyword(s):

Activated Sludge ◽

Wastewater Treatment Plants ◽

Future Research ◽

Model Structure ◽

Filamentous Bacteria ◽

Selection Mechanism ◽

Research Activities ◽

Microthrix Parvicella ◽

Selection Mechanisms ◽

Activated Sludge Systems

The filamentous bacteria “Microthrix parvicella” can cause serious bulking and scumming in wastewater treatment plants (WWTPs) all over the world. Decades of research have identified Microthrixas a specialized lipid consumer but could not clarify the processes that allow this organism to successfully compete in activated sludge systems. In this study we developed a model, based on ASM3, that describes the pronounced seasonal variations of Microthrix abundance observed in a full-scale WWTP. We hypothesize that low temperatures reduce the solubility of lipids and inhibit their uptake by non-specialized bacteria. The presented model structure and parameters successfully fit the measured data; however they do not necessarily reflect the only and true selection mechanism for Microthrix. This model is not yet to be used for prediction; it is rather a valuable research tool to coordinate the discussion and plan future research activities in order to identify the relevant selection mechanisms favoring Microthrix in activated sludge systems.

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Effect of Using Anaerobic Selectors on the Performance of Continuous Flow Activated Sludge Systems

AL-Rafdain Engineering Journal (AREJ) ◽

10.33899/rengj.2013.82367 ◽

2013 ◽

Vol 21 (6) ◽

pp. 88-99

Author(s):

Dr. Kossay K. Al-Ahmady ◽

Hanan Haqe Ismaeel

Keyword(s):

Activated Sludge ◽

Continuous Flow ◽

Activated Sludge Systems

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Microscopic versus macroscopic biomass models in activated sludge systems

Water Science & Technology ◽

10.2166/wst.2002.0089 ◽

2002 ◽

Vol 45 (6) ◽

pp. 1-11 ◽

Cited By ~ 13

Author(s):

W. Gujer

Keyword(s):

Activated Sludge ◽

Kinetic Parameters ◽

Model Prediction ◽

Continuous Flow ◽

Average Cell ◽

Macroscopic Models ◽

Cell Composition ◽

Microscopic Models ◽

Flow Systems ◽

Activated Sludge Systems

Today's models of activated sludge systems are based on average composition of biomass (macroscopic models). With the introduction of cell internal storage compounds (structured biomass) in ASM2 and ASM3 cell composition influences the kinetic behavior of activated sludge. Since the kinetics of most processes is not linear, adding up the behavior of individual cells (microscopic models) does not result in the same model prediction as obtained when predictions are made with average cell composition. Based on first simple computations with microscopic models which consider up to 100,000 individual bacteria, differences in model prediction are identified. It becomes clear that kinetic parameters for lumped, macroscopic models are system specific: whereas biomass from SBR systems yields kinetic parameters suited for application in microscopic models – biomass from continuous flow systems can only be used for the calibration of macroscopic models. Application of SBR models to continuous flow systems requires the use of microscopic models.

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