Leptothrix cholodnii Response to Nutrient Limitation

Microorganisms are widely utilized for the treatment of wastewater in activated sludge systems. However, the uncontrolled growth of filamentous bacteria leads to bulking and adversely affects wastewater treatment efficiency. To clarify the nutrient requirements for filament formation, we track the growth of a filamentous bacterium, Leptothrix cholodnii SP-6 in different nutrient-limited conditions using a high aspect-ratio microfluidic chamber to follow cell-chain elongation and sheath formation. We find that limitations in Na+, K+, and Fe2+ yield no observable changes in the elongation of cell chains and sheath formation, whereas limitations of C, N, P, or vitamins lead to more pronounced changes in filament morphology; here we observe the appearance of partially empty filaments with wide intercellular gaps. We observe more dramatic differences when SP-6 cells are transferred to media lacking Mg2+ and Ca2+. Loss of Mg2+ results in cell autolysis, while removal of Ca2+ results in the catastrophic disintegration of the filaments. By simultaneously limiting both carbon and Ca2+ sources, we are able to stimulate planktonic cell generation. These findings paint a detailed picture of the ecophysiology of Leptothrix, which may lead to improved control over the unchecked growth of deleterious filamentous bacteria in water purification systems.

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

Periodica Polytechnica Chemical Engineering ◽

10.3311/ppch.10078 ◽

2017 ◽

Vol 61 (3) ◽

pp. 149 ◽

Cited By ~ 1

Author(s):

Andrea Jobbágy ◽

Bernadett Kiss ◽

Vince Bakos

Keyword(s):

Activated Sludge ◽

Continuous Flow ◽

The Other ◽

N Availability ◽

Filamentous Bacteria ◽

Severe Deficiency ◽

And Performance ◽

Experimental Stage ◽

Activated Sludge Systems ◽

P Sources

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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Determination of the effect of multi-walled carbon nanotube on the treatment efficiency and design parameters in the activated sludge systems

10.5004/dwt.2020.25755 ◽

2020 ◽

Vol 192 ◽

pp. 166-175

Author(s):

Ümmükülsüm Özel Akdemir

Keyword(s):

Carbon Nanotube ◽

Activated Sludge ◽

Design Parameters ◽

Treatment Efficiency ◽

Multi Walled Carbon Nanotube ◽

Activated Sludge Systems

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Effects of particulate and soluble substrates on microfauna populations and treatment efficiency in activated sludge systems

Water Research ◽

10.1016/j.watres.2007.04.016 ◽

2007 ◽

Vol 41 (14) ◽

pp. 3168-3176 ◽

Cited By ~ 15

Author(s):

Jaume Puigagut ◽

Humbert Salvadó ◽

Xavier Tarrats ◽

Joan García

Keyword(s):

Activated Sludge ◽

Treatment Efficiency ◽

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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Novel feast-fast technique for filamentous foam control in the activated sludge process – introducing a new foam-measurement method

Water Science & Technology ◽

10.2166/wst.2000.0364 ◽

2000 ◽

Vol 42 (3-4) ◽

pp. 95-102 ◽

Cited By ~ 4

Author(s):

H. Chua ◽

W. Lo ◽

P.H. Yu ◽

S.N. Sin ◽

Y.G. Zhao ◽

...

Keyword(s):

Activated Sludge ◽

Measurement Method ◽

Prolonged Exposure ◽

Specific Growth ◽

Foam Stability ◽

Activated Sludge Process ◽

Filamentous Bacteria ◽

Treatment Efficiency ◽

Normal Range ◽

And Control

Overgrowth of filamentous Nocardia spp. in the activated sludge microbial ecosystem was previously identified as the cause of foaming problems in Hong Kong. In this work, the specific growth rate of N. amarae was found to be significantly higher than that of non-filamentous bacteria under food-to-microorganism (F/M) ratios lower than 0.5 mgBOD/mgMLSS-day, and was used as the basis for the development of a novel Feast-Fast Operation (FFO) for the prevention and control of foaming problems. The F/M ratio in the “feasting” aeration unit was 0.8 mgBOD/mgMLSS-day while that in the “fasting” aeration unit was 0.2 mgBOD/mgMLSS-day, resulting in an overall process F/M ratio that remained within the normal range, while avoided prolonged exposure of the sludge ecosystem to an F/M ratio below 0.5 mgBOD/mgMLSS-day. The FFO suppressed filamentous overgrowth and foaming without adversely affecting the organic treatment efficiency of the modified process. A new and convenient measurement method was developed for quantifying the degree of foaming and foam stability in activated sludge.

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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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Activated sludge foaming: can phage therapy provide a control strategy?

Microbiology Australia ◽

10.1071/ma18048 ◽

2018 ◽

Vol 39 (3) ◽

pp. 162 ◽

Cited By ~ 2

Author(s):

Steve Petrovski ◽

Robert Seviour

Keyword(s):

Activated Sludge ◽

Control Strategy ◽

Phage Therapy ◽

Filamentous Bacteria ◽

Global Problem ◽

Double Stranded Dna ◽

Reliable Methods ◽

Activated Sludge Systems

Foaming in activated sludge systems is a global problem leading to environmental, cosmetic and operational problems. Proliferation of filamentous hydrophobic bacteria (including the Mycolata) are responsible for the stabilisation of foams. Currently no reliable methods exist to control these. Reducing the levels of the filamentous bacteria with bacteriophages below the threshold supporting foaming is an attractive approach to control their impact. We have isolated 88 bacteriophages that target members of the foaming Mycolata. These double stranded DNA phages have been characterised and are currently being assessed for their performance as antifoam agents.

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Treatment efficiency and sludge characteristics in conventional and suspended PVA gel beads activated sludge treating phenol containing wastewater

Global NEST Journal ◽

10.30955/gnj.002404 ◽

2018 ◽

Vol 20 (1) ◽

pp. 42-48 ◽

Cited By ~ 2

Keyword(s):

Activated Sludge ◽

Removal Rate ◽

Synthetic Wastewater ◽

Organic Load ◽

Phenol Removal ◽

Treatment Efficiency ◽

Good Efficiency ◽

Gel Beads ◽

Pva Gel ◽

Activated Sludge Systems

Protozoa play a significant role in activated sludge systems, since they graze on dispersed bacteria, supporting a healthy food web in the activated sludge artificial ecosystem. However, operational parameters and influent properties are the most important factors affecting the composition of activated sludge microfauna. The objective of this study was the assessment of the treatment efficiency and the protozoan populations in activated sludge systems with and without the addition of polyvinyl alcohol (PVA) gel beads while treating wastewater in the presence of phenol. Six activated sludge reactors - 3 of them supplied with PVA gel beads –were used for the treatment of synthetic wastewater influent containing phenol at concentrations up to 10 mg/L. During the treatment of synthetic wastewater, dominance of the sessile species was observed mainly in the reactors supplied with PVA beads. Physicochemical analyses of the effluent indicated good efficiency of reactors supplied with PVA beads in removing nutrients and organic load. Introduction of phenol in the influent at a concentration of 5 mg/L did not affect significantly the operation of the reactors and the composition and abundance of activated sludge microfauna, while a high phenol removal rate was observed. The increase of influent phenol concentration to 10 mg/L resulted to the formation of foam on the surface of the reactors and the presence of Zoogleasp, while an increase was observed in the abundance of crawling species in activated sludge and PVA supplied reactors respectively.

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