Composition of extracellular polymeric substances in the activated sludge floc matrix

The precise role of extracellular polymeric substances (EPS) in relation to the formation and physicochemical properties of microbial floc in wastewater treatment systems is not well known. Studies were undertaken to provide more comprehensive descriptions of EPS and properties of microbial floc. Acidic polysaccharides and DNA were relatively labile components of the EPS when biomass was stored at 4°C or at −20°C, and significant losses of these components were observed within 24 hours. The composition and properties of activated sludge were found to vary between different full-scale treatment systems reflecting the importance of wastewater composition and operation conditions on microbial communities and the response to environmental conditions. The COD:N:P ratio was found to influence hydrophobicity, surface charge and the EPS composition of microbial flocs in well-controlled bench-scale sequencing batch reactors. Phosphorus depleted and P-limited conditions resulted in a decrease in surface charge but increases in acidic polysaccharides which corresponded to a strong carboxyl stretch at 1740 cm−1 when the biomass was analysed by FTIR-spectroscopy. Electron dense particles, identified by energy-dispersive spectroscopy as containing iron, phosphorus and sulfur, were observed in the fibrils of the floc matrix by transmission electron microscopy.

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Effect of temperatures and alternating anoxic/oxic sequencing batch reactor (SBR) operating modes on extracellular polymeric substances in activated sludge

Water Science & Technology ◽

10.2166/wst.2020.336 ◽

2020 ◽

Author(s):

Hongwei Sun ◽

Chenjian Cai ◽

Jixue Chen ◽

Chunyu Liu ◽

Guangjie Wang ◽

...

Keyword(s):

Activated Sludge ◽

Extracellular Polymeric Substances ◽

Sequencing Batch Reactor ◽

Batch Reactor ◽

Batch Reactors ◽

Sequencing Batch Reactors ◽

Operating Modes ◽

Nitrification Process ◽

Main Component ◽

Denitrification Process

Abstract In order to investigate the effect of temperatures and operating modes on extracellular polymeric substances (EPS) contents, three sequencing batch reactors (SBRs) were operated at temperatures of 15, 25, and 35 °C (R15 °C, R25 °C, and R35 °C, respectively), with two SBRs operated under alternating anoxic/oxic conditions (RA/O and RO/A, respectively). Results showed that higher contents of tightly bound EPS (TB-EPS) and total EPS appeared in R15 °C, while loosely bound EPS (LB-EPS) dominated in R35 °C. In all three kinds of EPS (LB-EPS, TB-EPS and total EPS) assessed, protein was the main component in R15 °C and R25 °C, while polysaccharides dominated in R35 °C. Moreover, compared with RO/A, RA/O was favorable for the production of the three kinds of EPS. Furthermore, three kinds of EPS and their components were augmented during the nitrification process, while they declined during the denitrification process under all conditions except for R35 °C.

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Physicochemical and Biological Effects on Activated Sludge Performance and Activity Recovery of Damaged Sludge by Exposure to CeO2 Nanoparticles in Sequencing Batch Reactors

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph16204029 ◽

2019 ◽

Vol 16 (20) ◽

pp. 4029 ◽

Cited By ~ 2

Author(s):

Qian Feng ◽

Yaqing Sun ◽

Yang Wu ◽

Zhaoxia Xue ◽

Jingyang Luo ◽

...

Keyword(s):

Activated Sludge ◽

Extracellular Polymeric Substances ◽

High Throughput Sequencing ◽

Biological Effects ◽

Recovery Period ◽

Ceo2 Nanoparticles ◽

Batch Reactors ◽

Sequencing Batch Reactors ◽

Key Enzymes ◽

Activity Recovery

Recently, the growing release of CeO2 nanoparticles (CeO2 NPs) into sewage systems has attracted great concern. Several studies have extensively explored CeO2 NPs’ potential adverse impacts on wastewater treatment plants; however, the impaired activated sludge recovery potentials have seldom been addressed to date. To explore the physicochemical and biological effects on the activated sludge performance and activity recovery of damaged sludge by exposure to CeO2 NPs in sequencing batch reactors (SBRs), four reactors and multiple indicators including water quality, key enzymes, microbial metabolites, the microbial community structure and toxicity were used. Results showed that 10-week exposure to higher CeO2 NP concentration (1, 10 mg/L) resulted in a sharp decrease in nitrogen and phosphorus removal efficiencies, which were consistent with the tendencies of key enzymes. Meanwhile, CeO2 NPs at concentrations of 0.1, 1, and 10 mg/L decreased the secretion of tightly bound extracellular polymeric substances to 0.13%, 3.14%, and 28.60%, respectively, compared to the control. In addition, two-week recovery period assays revealed that the functional bacteria Proteobacteria, Nitrospirae and Planctomycetes recovered slightly at the phyla level, as analyzed through high-throughput sequencing, which was consistent with the small amount of improvement of the effluent performance of the system. This reflected the small possibility of the activity recovery of damaged sludge.

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The Influence of Temperature on Bioflocculation and Settling of Activated Sludge and their Flocculation Mechanisms Involved

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.518-523.1817 ◽

2012 ◽

Vol 518-523 ◽

pp. 1817-1824 ◽

Cited By ~ 2

Author(s):

Jing Shui Huang ◽

Yue Wen ◽

A Sheng Cao ◽

Hai Song Li ◽

Qi Zhou

Keyword(s):

Activated Sludge ◽

Interaction Energy ◽

Extracellular Polymeric Substances ◽

Synthetic Wastewater ◽

Attractive Potential ◽

Batch Reactors ◽

Sequencing Batch Reactors ◽

Actual Performance ◽

Influence Of Temperature On ◽

Effects Of Temperature

Effects of temperature (conventional (25°С) vs. mesophilic (35°С) vs. thermophilic (55°С)) on activated sludge properties (production and composition of EPS and interaction potential) and their roles in bioflocculation and settling were studied using well-controlled sequencing batch reactors fed with a synthetic wastewater comprised of glucose and inorganic nutrients. The results show that thermophilic sludge had a poorer bioflocculation ability and settleability than that of conventional and mesophilic sludge. Analysis of extracellular polymeric substances (EPS) indicates that thermophilic sludge had a higher level of loosely bound EPS (LB-EPS) content than that of conventional and mesophilic sludge. The LB-EPS content of thermophilic sludge was ten times more than TB-EPS content of it, which coincided with higher supernatant turbidity. Therefore, the worse bioflocculation and settling ability of thermophilic sludge could be explained from the perspective of LB-EPS. Calculating the interaction energy of three kinds of sludge, the interaction barrier of thermophilic sludge disappeared which meant the attractive potential was dominant in the system. Thus, it should have led to a better flocculation, which did not agree with the actual performance. It indicates that the worse bioflocculation and settling ability of thermophilic sludge could be explained from the perspective of interaction energy.

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Influent with Particulate Substrate, Clean, Innocuous and Sustainable Solution for Bulking Control and Mitigation in Activated Sludge Process

Water ◽

10.3390/w13070984 ◽

2021 ◽

Vol 13 (7) ◽

pp. 984

Author(s):

Pedro Cisterna-Osorio ◽

Claudia Calabran-Caceres ◽

Giannina Tiznado-Bustamante ◽

Nataly Bastias-Toro

Keyword(s):

Activated Sludge ◽

Suspended Solids ◽

Nutrient Deficiency ◽

Microscopic Analysis ◽

Volume Index ◽

Favorable Effect ◽

Batch Reactors ◽

Sequencing Batch Reactors ◽

Active Sludge ◽

Chemical Reagents

This research studies the incidence of the type of substrate, soluble or particulate, in the emergence, development, and inhibition of bulking in activated sludge systems. It was evaluated using the sludge volume index (SVI), mixing liquor-suspended solids (MLSS), microscopic analysis of biomass, and effluent suspended solids (ESS). In the first experiment, four sequencing batch reactors (SBRs) were fed with soluble substrate at a fixed mass, while the mass of the particulate substrate varied, as those (saccharose mass/flour mass) ratios were 3:1, 3:2, 3:3 and 3:4., with a deficit ranging from 20 to 30% compared to the ratio recommended. The four SBRs have similar MLSS, IVL, and ESS. From day 30, with a deficit from 80 to 90%, the influents have ratios 1/1 and 1/2 until 48 days. The SBRs present IVL between 600 and 730 mL/g and ESS from 370 to 440 mg/L; unlike influents with ratios 1/3 and 1/4, they present IVL between 170 and 185 mL/g, and ESS from 260 to 270 mg/L. The favorable effect of particulate matter is categorical. In the second set of experiments, two SBRs were studied: SBR 1 fed with saccharose, and SBR 2 with flour; there is a lack of nutrients causing bulking in SBRs. Once the nutrient deficiency condition is changed in day 11 to excess, after 22 days, the SVI was 190 mL/g, ESS was 360 mg/L, and MLSS was 2000 mg/L for influents with saccharose; the influent with flour, with an SVI of 80 mL/g, ESS of 100 mg/L, and MLSS of 4000 mg/L, shows faster and more consistent recovery with the particulate substrate. Therefore, the proposal is to add particulate substrate-like flour to active sludge plants facing bulking. It is a clean, innocuous and sustainable alternative to processes that use chemical reagents.

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Wastewater fermentation and nutrient removal in sequencing batch reactors

Water Science & Technology ◽

10.2166/wst.1998.0061 ◽

1998 ◽

Vol 38 (1) ◽

pp. 255-264 ◽

Cited By ~ 4

Author(s):

Germán Cuevas-Rodríguez ◽

Óscar González-Barceló ◽

Simón González-Martínez

Keyword(s):

Activated Sludge ◽

Volatile Fatty Acids ◽

Organic Load ◽

Batch Reactors ◽

Sequencing Batch Reactors ◽

Organic Loading ◽

Nitrogen And Phosphorus ◽

Loading Rates ◽

Average Value ◽

Experimental Runs

This research project was conducted to analyze the performance of a SBR reactor when being fed with anaerobically fermented wastewater. Important was to determine the capacity of the system to remove nitrogen and phosphorus. Two SBR reactors, each one with a volume of 980 liters, were used: one used as fermenter and the other as activated sludge SBR. Using 8-hour cycles, the reactors were operated and studied during 269 days. The fermenter produced an effluent with an average value of 223±24 mg/l of volatile fatty acids. The activated sludge SBR was tested under 3 organic loading rates of 0.13, 0.25, and 0.35 kgCODtotal/kgTSS·d. For the three tested organic loading rates, PO4-P concentrations under 1.1 mg/l and COD between 37 and 38 mg/l were consistently achieved. Exceptionally high NH4-N influent values were measured during the time of the experimentation with the organic load of 0.25 kgCODtotal/kgTSS·d, not reaching in this case full nitrification. Denitrification was observed during the fill phase in every cycle. SVI values between 40 and 70 were determined during the experimental runs.

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Study of factors affecting simultaneous nitrification and denitrification (SND)

Water Science & Technology ◽

10.2166/wst.1999.0262 ◽

1999 ◽

Vol 39 (6) ◽

pp. 61-68 ◽

Cited By ~ 118

Author(s):

Klangduen Pochana ◽

Jürg Keller

Keyword(s):

Carbon Source ◽

Activated Sludge ◽

Physical Phenomenon ◽

Treatment Plant ◽

Batch Reactors ◽

Sequencing Batch Reactors ◽

Factors Affecting ◽

Floc Size ◽

Sludge Flocs ◽

Activated Sludge Systems

Experiments have been performed to gain an understanding of the conditions and processes governing the occurrence of SND in activated sludge systems. Sequencing batch reactors (SBRs) have been operated under controlled conditions using the wastewater from the first anaerobic pond in an abattoir wastewater treatment plant. Under specific circumstances, up to 95% of total nitrogen removal through SND has been found in the system. Carbon source and oxygen concentrations were found to be important process parameters. The addition of acetate as an external carbon source resulted in a significant increase of SND activity in the system. Stepwise change of DO concentration has also been observed in this study. Experiments to determine the effect of the floc size on SND have been performed in order to test the hypothesis that SND is a physical phenomenon, governed by the diffusion of oxygen into the activated sludge flocs. Initial results support this hypothesis but further experimental confirmation is still required.

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Contribution of prokaryotes and eukaryotes to CO2 emissions in the wastewater treatment process

PeerJ ◽

10.7717/peerj.9325 ◽

2020 ◽

Vol 8 ◽

pp. e9325

Author(s):

Katarzyna Jaromin-Gleń ◽

Roman Babko ◽

Tatiana Kuzmina ◽

Yaroslav Danko ◽

Grzegorz Łagód ◽

...

Keyword(s):

Wastewater Treatment ◽

Activated Sludge ◽

Greenhouse Effect ◽

Wastewater Treatment Plants ◽

Ghg Emissions ◽

Batch Reactors ◽

Sequencing Batch Reactors ◽

Wastewater Treatment Process ◽

Eukaryotic Organisms ◽

Quantitative Contribution

Reduction of the greenhouse effect is primarily associated with the reduction of greenhouse gas (GHG) emissions. Carbon dioxide (CO2) is one of the gases that increases the greenhouse effect - it is responsible for about half of the greenhouse effect. Significant sources of CO2 are wastewater treatment plants (WWTPs) and waste management, with about 3% contribution to global emissions. CO2 is produced mainly in the aerobic stage of wastewater purification and is a consequence of activated sludge activity. Although the roles of activated sludge components in the purification process have been studied quite well, their quantitative contribution to CO2 emissions is still unknown. The emission of CO2 caused by prokaryotes and eukaryotes over the course of a year (taking into account subsequent seasons) in model sequencing batch reactors (SBR) is presented in this study. In this work, for the first time, we aimed to quantify this contribution of eukaryotic organisms to total CO2 emissions during the WWTP process. It is of the order of several or more ppm. The contribution of CO2 produced by different components of activated sludge in WWTPs can improve estimation of the emissions of GHGs in this area of human activity.

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Isolation, Separation and Identification of the Extracellular Polymeric Substance (EPS) Protein Fraction from the Activated Sludge Floc

10.32920/ryerson.14653773.v1 ◽

2021 ◽

Author(s):

Elena Brei

Keyword(s):

Mass Spectrum ◽

Activated Sludge ◽

Extracellular Polymeric Substances ◽

Current Knowledge ◽

Noncovalent Interactions ◽

Detection Methods ◽

Structure Stability ◽

Major Protein ◽

Substantial Portion ◽

Microbial Flocs

The purpose of this study was to expand the current knowledge of the composition of extracellular polymeric substances (EPS), principally EPS proteins, and their influence on structure, stability and surface chemistry of microbial flocs in activated sludge. It was proposed that a substantial portion of EPS proteins contains glycoproteins or proteins that are strongly bound noncovalently to carbohydrates. Various buffer additives, purification and precipitation methods were employed for protein purification and several glycoprotein detection methods were utilized for glycoprotein detection in the EPS. The proteins were separated with success, with a substantial portion suggesting either a possible glycosylation or strong noncovalent interactions with carbohydrate moiety. An enzyme, oligoendopeptidase F from M3B family was tentatively identified as a major protein present. These results suggest that proteins in the activated sludge EPS may exist in a very intricate arrangement. Furthermore, the EPS peptides may get degraded by naturally present enzymes in the EPS after the protein is digested prior to mass spectrum (MS), making the identification challenging.

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Seasonal Dynamics of the Activated Sludge Microbiome in Sequencing Batch Reactors, Assessed Using 16S rRNA Transcript Amplicon Sequencing

Applied and Environmental Microbiology ◽

10.1128/aem.00597-20 ◽

2020 ◽

Vol 86 (19) ◽

Author(s):

Juliet Johnston ◽

Sebastian Behrens

Keyword(s):

Wastewater Treatment ◽

Microbial Community ◽

16S Rrna ◽

Activated Sludge ◽

Seasonal Dynamics ◽

Activity Patterns ◽

Amplicon Sequencing ◽

Batch Reactors ◽

Sequencing Batch Reactors ◽

Copy Numbers

ABSTRACT Activated sludge is comprised of diverse microorganisms which remediate wastewater. Previous research has characterized activated sludge using 16S rRNA gene amplicon sequencing, which can help to address questions on the relative abundance of microorganisms. In this study, we used 16S rRNA transcript sequencing in order to characterize “active” populations (via protein synthesis potential) and gain a deeper understanding of microbial activity patterns within activated sludge. Seasonal abundances of individual populations in activated sludge change over time, yet a persistent group of core microorganisms remains throughout the year which are traditionally classified on presence or absence without monitoring of their activity or growth. The goal of this study was to further our understanding of how the activated sludge microbiome changes between seasons with respect to population abundance, activity, and growth. Triplicate sequencing batch reactors were sampled at 10-min intervals throughout reaction cycles during all four seasons. We quantified the gene and transcript copy numbers of 16S rRNA amplicons using real-time PCR and sequenced the products to reveal community abundance and activity changes. We identified 108 operational taxonomic units (OTUs) with stable abundance, activity, and growth throughout the year. Nonproliferating OTUs were commonly human health related, while OTUs that showed seasonal abundance changes have previously been identified as being associated with floc formation and bulking. We observed significant differences in 16S rRNA transcript copy numbers, particularly at lower temperatures in winter and spring. The study provides an analysis of the seasonal dynamics of microbial activity variations in activated sludge based on quantifying and sequencing 16S rRNA transcripts. IMPORTANCE Sequencing batch reactors are a common design for wastewater treatment plants, particularly in smaller municipalities, due to their low footprint and ease of operations. However, like for most treatment plants in temperate/continental climates, the microbial community involved in water treatment is highly seasonal and its biological processes can be sensitive to cold temperatures. The seasonality of these microbial communities has been explored primarily in conventional treatment plants and not in sequencing batch reactors. Furthermore, most studies often only address which organisms are present. However, the activated sludge microbial community is very diverse, and it is often hard to discern which organisms are active and which organisms are simply present. In this study, we applied additional sequencing techniques to also address the issues of which organisms are active and which organisms are growing. By addressing these issues, we gained new insights into seasonal microbial populations dynamics and activity patterns affecting wastewater treatment.

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