The Application of Microbial Technology in Harbor Engineering: The Impact of Extracellular Polymeric Substances on the Sedimentation and Properties of Fluid Mud

2017 ◽  
pp. 847-857
Author(s):  
Xiaohua Chen ◽  
Qixiu Pang ◽  
Mengnan Li ◽  
Baojiang Sun ◽  
Ruibo Zhang ◽  
...  
Keyword(s):  
Extracellular Polymeric Substances ◽  
Fluid Mud ◽  
The Impact

Community structure of micro- and macroflocs in pin-point sludge and the influence of sludge age and potassium addition on microfloc formation

2002 ◽  
Vol 46 (1-2) ◽  
pp. 405-412 ◽  
Author(s):  
E. Müller ◽  
K. Kriebitzsch ◽  
P.A. Wilderer ◽  
S. Wuertz
Keyword(s):  
Community Structure ◽  
Microbial Communities ◽  
Extracellular Polymeric Substances ◽  
Point Of View ◽  
Sludge Formation ◽  
Industrial Plants ◽  
Noticeable Improvement ◽  
Lower Protein ◽  
Utilization Patterns ◽  
The Impact

Settling problems caused by pin-point sludge constitute a serious problem in biological wastewater treatment, particularly in many industrial plants. Until now, most studies focused on the relationship between pin-point sludge formation and either shearing forces or the impact of toxicants. This study deals with the community structure in both the micro- and macrofloc fraction which was analyzed by fluorescent in situ hybridization (FISH) and BIOLOG substrate utilization patterns. It was shown that each fraction consisted of different microbial communities with unique metabolic profiles suggesting that pin-point sludge formation is not due to dispersal of intact flocs but to microcolonies growing separately. Alternatively, macroflocs may have an architecture leading to segregation of microbial communities after floc dispersal. Further it could be shown that the formation of microflocs was influenced by sludge age. The best sludge sedimentation was obtained for a sludge age of 5 and 10 days. Additional analysis of extracellular polymeric substances (EPS) suggested that the lower protein to carbohydrate ratio of 10-day-old sludge led to better flocculation compared to 20-day-old sludge containing similar total amounts of EPS. From a practical point of view, addition of potassium (0.1 g/l) effected a noticeable improvement of sludge settleability.

Effect of phosphorus limitation on microbial floc structure and gene expression in activated sludge

2006 ◽  
Vol 54 (1) ◽  
pp. 247-255 ◽  
Author(s):  
J.R. Liu ◽  
C.T. Liu ◽  
E.A. Edwards ◽  
S.N. Liss
Keyword(s):  
Gene Expression ◽  
Activated Sludge ◽  
Extracellular Polymeric Substances ◽  
Morphological Changes ◽  
Cell Structure ◽  
Operating Conditions ◽  
P Limitation ◽  
Floc Structure ◽  
The Impact ◽  
Log Ratio

The effect of limiting phosphorus (P) in activated sludge was investigated in laboratory-scale sequencing batch reactors (SBRs). Correlative microscopy revealed that P-limitation (COD:N:P=100:5:0.05) leads to morphological changes in floc structure and the composition of extracellular polymeric substances (EPS). This was found to be accompanied by expression of quorum-sensing in an acyl homoserine lactone bioassay. Differential gene expression in relation to P-limitation was examined in a global profile using the Affymetrix™ Escherichia coli antisense genomic microarray. Three separate experiments were conducted where the impact of P-limitation was examined under batch conditions and in SBRs at stable operating conditions and within 3–7 days following a down-shift in P. Significant changes in open reading frames (ORF) and intergenic regions based on the E. coli microarray were observed. Several genes associated with cell structure, including slt, wbbH, fimH, amB, rfaJ and slp were found to be expressed. Quorum regulated genes were also found to be expressed including psiF which is known to be induced by P-starvation (92% confidence level; 1.45 log ratio).

scholarly journals Spatio-temporal modeling of the crowding conditions and metabolic variability in microbial communities

2021 ◽  
Vol 17 (7) ◽  
pp. e1009140
Author(s):  
Liliana Angeles-Martinez ◽  
Vassily Hatzimanikatis
Keyword(s):  
Microbial Communities ◽  
Extracellular Polymeric Substances ◽  
Resource Competition ◽  
Local Environment ◽  
Microbial Interactions ◽  
Relative Fitness ◽  
Flux Analysis ◽  
Scaled Particle Theory ◽  
Spatio Temporal ◽  
The Impact

The metabolic capabilities of the species and the local environment shape the microbial interactions in a community either through the exchange of metabolic products or the competition for the resources. Cells are often arranged in close proximity to each other, creating a crowded environment that unevenly reduce the diffusion of nutrients. Herein, we investigated how the crowding conditions and metabolic variability among cells shape the dynamics of microbial communities. For this, we developed CROMICS, a spatio-temporal framework that combines techniques such as individual-based modeling, scaled particle theory, and thermodynamic flux analysis to explicitly incorporate the cell metabolism and the impact of the presence of macromolecular components on the nutrients diffusion. This framework was used to study two archetypical microbial communities (i) Escherichia coli and Salmonella enterica that cooperate with each other by exchanging metabolites, and (ii) two E. coli with different production level of extracellular polymeric substances (EPS) that compete for the same nutrients. In the mutualistic community, our results demonstrate that crowding enhanced the fitness of cooperative mutants by reducing the leakage of metabolites from the region where they are produced, avoiding the resource competition with non-cooperative cells. Moreover, we also show that E. coli EPS-secreting mutants won the competition against the non-secreting cells by creating less dense structures (i.e. increasing the spacing among the cells) that allow mutants to expand and reach regions closer to the nutrient supply point. A modest enhancement of the relative fitness of EPS-secreting cells over the non-secreting ones were found when the crowding effect was taken into account in the simulations. The emergence of cell-cell interactions and the intracellular conflicts arising from the trade-off between growth and the secretion of metabolites or EPS could provide a local competitive advantage to one species, either by supplying more cross-feeding metabolites or by creating a less dense neighborhood.

scholarly journals Aquatic polymers can drive pathogen transmission in coastal ecosystems

2014 ◽  
Vol 281 (1795) ◽  
pp. 20141287 ◽  
Author(s):  
Karen Shapiro ◽  
Colin Krusor ◽  
Fernanda F. M. Mazzillo ◽  
Patricia A. Conrad ◽  
John L. Largier ◽  
...  
Keyword(s):  
Extracellular Polymeric Substances ◽  
Critical Role ◽  
Pathogen Transmission ◽  
Coastal Habitat ◽  
Marine Fauna ◽  
Aggregation Processes ◽  
Zoonotic Parasite ◽  
Marine Aggregates ◽  
The Matrix ◽  
The Impact

Gelatinous polymers including extracellular polymeric substances (EPSs) are fundamental to biophysical processes in aquatic habitats, including mediating aggregation processes and functioning as the matrix of biofilms. Yet insight into the impact of these sticky molecules on the environmental transmission of pathogens in the ocean is limited. We used the zoonotic parasite Toxoplasma gondii as a model to evaluate polymer-mediated mechanisms that promote transmission of terrestrially derived pathogens to marine fauna and humans. We show that transparent exopolymer particles, a particulate form of EPS, enhance T. gondii association with marine aggregates, material consumed by organisms otherwise unable to access micrometre-sized particles. Adhesion to EPS biofilms on macroalgae also captures T. gondii from the water, enabling uptake of pathogens by invertebrates that feed on kelp surfaces. We demonstrate the acquisition, concentration and retention of T. gondii by kelp-grazing snails, which can transmit T. gondii to threatened California sea otters. Results highlight novel mechanisms whereby aquatic polymers facilitate incorporation of pathogens into food webs via association with particle aggregates and biofilms. Identifying the critical role of invisible polymers in transmission of pathogens in the ocean represents a fundamental advance in understanding and mitigating the health impacts of coastal habitat pollution with contaminated runoff.

The impact of reduced phosphorus levels on microbial floc properties during biological treatment of pulp and paper wastewaters

2007 ◽  
Vol 55 (6) ◽  
pp. 73-79 ◽  
Author(s):  
J.R. Liu ◽  
S.N. Liss
Keyword(s):  
Extracellular Polymeric Substances ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
Reactor Performance ◽  
Inorganic P ◽  
P Limitation ◽  
Floc Structure ◽  
The Impact ◽  
Sludge Settleability ◽  
Phosphorus Levels

The effect of limiting P in activated sludge was investigated in laboratory scale sequencing batch reactors (SBRs) fed effluent from a container board mill. Floc characterization included measurement of hydrophobicity, surface charge, and analysis of extracellular polymeric substances (EPS). Reactor performance was assessed by monitoring COD and inorganic P removal, MLSS, and sludge settleability (SVI and batch settling flux) over a period of eight months. Control reactors (BOD:N:P of 100:5:1) were compared to reactors run under P-limited conditions (100:5:0.3; 100:5:0.1). Reactor performance at lower temperatures (14 °C; control = 26 °C) was also studied to assess the impact of P-limitation. Changes in floc structure and the composition of EPS occurred within 1 to 3 days following a reduction in P levels. There was an insignificant increase in SVI; however, gravitational settling velocity and batch settling flux values for low P floc were consistently higher than for floc generated under control conditions. Lower temperatures (14 °C) resulted in a deterioration in floc settling properties at a BOD:N:P of 100:5:1. This impact on settling was significantly reduced at a BOD:P of 100:0.1. Reducing P concentrations in the wastewater treatment system has the potential to improve sludge settleability and reduce final P discharges.

Surface adhesion of phototrophic biofilms

2020 ◽  
Author(s):  
Judith Stiefelmaier ◽  
Dorina Strieth ◽  
Susanne Schaefer ◽  
Daniel Kronenberger ◽  
Björn Wrabl ◽  
...  
Keyword(s):  
Extracellular Polymeric Substances ◽  
Cfd Simulation ◽  
Oxygenic Photosynthesis ◽  
Adhesion Forces ◽  
Surface Adhesion ◽  
German Research Foundation ◽  
Terrestrial Cyanobacteria ◽  
Phototrophic Biofilms ◽  
Flow Through ◽  
The Impact

<p>Cyanobacteria belong to the oldest known microorganisms and are capable of oxygenic photosynthesis. Depending on their habitat aquatic and terrestrial cyanobacteria are distinguished. Terrestrial cyanobacteria grow embedded in a matrix of extracellular polymeric substances (EPS) as phototrophic biofilms. Those EPS serve as nutrient storage, protection from desiccation and play an important role in surface adhesion. For cultivation of phototrophic biofilms different biofilm reactors have been developed in the last years. One interesting parameter when cultivating biofilms is the surface material and structure, since it can influence the surface adhesion and thus biofilm formation. Therefore, different materials as cultivation surfaces were investigated as well as the strain specific behavior of different cyanobacteria and the impact on EPS formation. In this work the adhesion of the terrestrial cyanobacteria <em>Coleofasciculus chthonoplastes</em> and <em>Trichocoleus sociatus</em> to different materials was investigated. For characterization of materials measurements concerning surface roughness were conducted using atomic force microscopy. Biofilms were cultivated in an aerosol and the development of surface adhesion in connection with biofilm age was analyzed using two different methods. In the first set-up biofilms were placed in a specially designed flow-through chamber and overflown with medium at increasing flow speed. The detachment of the biofilm was documented with optical coherence tomography (OCT). Additionally, the experiments were supplemented with CFD-simulation for quantification of shear forces. The second method analyzed adhesion forces using rotational rheometry. Hereby, differences between cyanobacteria strains and surface materials could be observed as well as an increasing adhesion with increasing cultivation time. The developed flow-through chamber, which could as well be utilized with a camera instead of OCT, offers a simple low-priced possibility for investigation of surface adhesion.</p> <p>This project is financially supported by the German Research Foundation (DFG; Project number: UL 170/16-1; MU 2985/3-1 and SFB 926) and the Landesförderung Rheinland-Pfalz (Project: iProcess).</p>

Strong selection pressures impact the capacity of flocculating activated sludge bacteria to granulate

2013 ◽  
Vol 67 (8) ◽  
pp. 1678-1687 ◽  
Author(s):  
G. A. C. Ehlers ◽  
S. J. Turner
Keyword(s):  
Particle Size ◽  
Activated Sludge ◽  
Extracellular Polymeric Substances ◽  
High Rate ◽  
Volume Index ◽  
Size Analysis ◽  
Liquid Separation ◽  
Granule Formation ◽  
Selection Pressures ◽  
The Impact

The capacity of activated sludge (AS) microbial populations to form dense granules offers the potential to establish efficiently settleable biomass. This has the potential to circumvent problems around ineffective solids–liquid separation and sensitivity to variable chemical oxygen demand (COD) loads. Although a number of studies have evaluated aerobic laboratory granulation reactors as high-rate treatment systems, the biological processes involved in aerobic granulation are not fully understood. Concomitantly, the impact of operation parameters such as organic loading rates is also important for granulation. The ability of a flocculating AS community to granulate under different selection pressures was evaluated in a laboratory sequencing batch reactor by determining levels of extracellular polymeric substances (EPS) and particle size fractions that developed under feast (4.74 g COD L−1) and famine (0.42 g COD L−1) nutrient regimes. The efficiency of solid–liquid separation was also measured. Aggregation indices showed levels >94% and a sludge volume index factor of up to 0.94, which strongly suggested granule formation; however, microscopy evaluation showed a mixture of flocs and granules. Particle size analysis revealed binomial distribution patterns of particles in the reactor which shifted to smaller tightly bound particles (<200 μm) although large particles (>600 μm) were also measured during famine conditions. This coincided with increases in EPS levels although EPS quantities were low and it is postulated that this could have impacted granule formation: the EPS in the bacterial aggregates were consumed since the AS community was starved.

scholarly journals Understanding the Impact of Extracellular Polymeric Substances on Lead Release in Drinking Water Systems

ACS Omega ◽  
2018 ◽  
Vol 3 (11) ◽  
pp. 14824-14832 ◽  
Author(s):  
Yaohuan Gao ◽  
Benjamin F. Trueman ◽  
Amina K. Stoddart ◽  
Graham A. Gagnon
Keyword(s):  
Drinking Water ◽  
Extracellular Polymeric Substances ◽  
Water Systems ◽  
Lead Release ◽  
The Impact ◽  
Drinking Water Systems
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