Does a change in reactor loading rate affect activated sludge bioflocculation?

Dierdonck, Jan Van; Broeck, Rob Van den; Vervoort, E.; D’haeninck, P.; Springael, Dirk; Impe, Jan Van; Smets, Ilse

doi:10.1016/j.procbio.2012.08.017

Cited by 26 publications

(10 citation statements)

References 38 publications

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“…The formation of larger flocs at the relatively high P/C ratio may be attributed to increased hydrophobicity and cohesion between aggregates . Our findings were in agreement with literature findings . Composition of EPS obviously affected the physicochemical properties of activated sludge flocs.…”

Section: Resultsmentioning

confidence: 99%

Production of protein‐ and carbohydrate‐EPS in activated sludge reactors operated at different carbon to nitrogen ratios

Geyik¹,

Çeçen²

2014

J of Chemical Tech & Biotech

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BACKGROUND This study aimed to clarify how a variation in the carbon to nitrogen (C/N) ratio in influent wastewater affects the production and composition of extracellular polymeric substances (EPS) in activated sludge. In the literature such a comparative analysis is rarely presented, most studies on EPS focus on simultaneous organic carbon removal and nitrification whereas little attention is paid to the case of low organic load or separate‐stage nitrification. RESULTS Among the very loosely bound, loosely bound and tightly bound EPS fractions, tightly bound EPS prevailed in semi‐continuously fed batch activated sludge reactors that were fed at a C/N ratio of 10, 5 and 0, respectively. The C/N ratio had no clear effect on total EPS production, however it changed the proportion of proteins and carbohydrates. In each sludge proteins constituted the dominant part of EPS, but the EPS of the nitrifying sludge (C/N = 0), had a definitely higher protein content. As evidenced by HPSEC fingerprints, in all EPS fractions most proteins had MWs ≤16 kDa. Depending on the C/N ratio in a reactor, high MW proteins in EPS shifted from tightly bound fractions to others. CONCLUSION The study is among the few that highlight how the protein and carbohydrate content in EPS changes at different C/N ratios. Since wastewater composition in a treatment system affects the chemical composition of EPS, each sludge might have different responses to uptake of xenobiotics such as metals. Further, this difference in composition might affect sludge settling, dewatering and membrane fouling. © 2014 Society of Chemical Industry

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Section: Resultsmentioning

confidence: 99%

Production of protein‐ and carbohydrate‐EPS in activated sludge reactors operated at different carbon to nitrogen ratios

Geyik¹,

Çeçen²

2014

J of Chemical Tech & Biotech

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“…Recently, a study was performed in AS systems showing the great potential of image analysis procedure to relate to settling properties as the morphological parameters of AS respond rather fast to changing process conditions, especially during filamentous bulking [163]. Image analysis parameters have been also found of great potential to study the stability of the sludge prior to an impact of different operational conditions in a lab-scale reactor after the period of acclimatization [164], and to determine the bioflocculation mechanism of aggregated biomass combined with EPS analysis [165]. The growing interest in membrane bioreactors (MBRs) as valuable alternative for conventional AS systems, conducted to relevant research in the bioflocculation of the sludge using automated image analysis.…”

Section: Image Analysis In Bright-field and Phase-contrast Microscopymentioning

confidence: 99%

Activated sludge characterization through microscopy: A review on quantitative image analysis and chemometric techniques

Mesquita

Amaral

Ferreira

2013

Analytica Chimica Acta

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In wastewater treatment processes, and particularly in activated sludge systems, efficiency is quite dependent on the operating conditions, and a number of problems may arise due to sludge structure and proliferation of specific microorganisms. In fact, bacterial communities and protozoa identification by microscopy inspection is already routinely employed in a considerable number of cases. Furthermore, quantitative image analysis techniques have been increasingly used throughout the years for the assessment of aggregates and filamentous bacteria properties. These procedures are able to provide an ever growing amount of data for wastewater treatment processes in which chemometric techniques can be a valuable tool. However, the determination of microbial communities' properties remains a current challenge in spite of the great diversity of microscopy techniques applied. In this review, activated sludge characterization is discussed highlighting the aggregates structure and filamentous bacteria determination by image analysis on bright-field, phase-contrast, and fluorescence microscopy. An in-depth analysis is performed to summarize the many new findings that have been obtained, and future developments for these biological processes are further discussed.

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“…These are the average values of the concentration before and after the start of the changing influent conditions, as indicated by the red line. In addition, eEPS PN/PS is often used as an indicator for bioflocculation (Liao et al, 2001;Van Dierdonck et al, 2012b). Although values for eEPS PN/PS are not extremely high, for all reactors an increase could be observed when the changes in influent conditions were applied (see Table 3).…”

Section: Tablementioning

confidence: 98%

“…SMP are extracted and analysed according to Van Dierdonck et al (2012a) and Van Dierdonck et al (2012b), respectively.…”

Section: Extracellular Polymeric Substances Eps Can Be Divided In Twmentioning

confidence: 99%

“…The major drawback of the aforementioned measurements is that they are unable to directly assess the activated sludge bioflocculation condition. Monitoring flocs and floc size or in the case of deflocculation, floc break-up into smaller flocs and the subsequent release of microcolonies and primary particles, offers a more direct view on the (dynamics of the) bioflocculation process (Jarvis et al, 2005, Van Dierdonck et al, 2012b. This can be achieved by microscopic image analysis which has already proven its merits, e.g., in the filamentous bulking context (Arelli et al, 2009;da Motta et al, 2001;Jenné et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

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The effect of alternating influent carbon source composition on activated sludge bioflocculation

Dierdonck

Broeck

Vervoort

et al. 2013

Journal of Biotechnology

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which has been archived on the university repository Lirias (https://lirias.kuleuven.be/) of the Katholieke Universiteit Leuven.The content is identical to the content of the published paper, but without the final typesetting by the publisher.When referring to this work, please cite the full bibliographic info:Van Dierdonck, J., Van den Broeck, R., Vervoort, E., Van Impe, J., Smets, I. (2013). Effect of alternating influent carbon source composition on activated sludge bioflocculation. Journal of Biotechnology, 167 (3),[225][226][227][228][229][230][231][232][233][234] The journal and the original published paper can be found at: http://www.journals.elsevier.com/journal-of-biotechnology http://dx.doi.org/10.1016/j.jbiotec.2013.07.012 The corresponding author can be contacted for additional info.Conditions for open access are available at: http://www.sherpa.ac.uk/romeo/ Postprint version of paper published in Journal of Biotechnology 2013, vol. 167, issue 3, p. 225--234. The content is identical to the published paper, but without the final typesetting by the publisher. AbstractThe impact of alternating influent carbon sources, i.e., glucose and starch, on activated sludge bioflocculation was investigated. To this end, four lab-scale reactors were operated during a long-term experiment. During this period the influent carbon source ratio (glucose/starch) was alternated every 7 or 35 days (i.e., a fast and slow switching frequency). Bioflocculation was monitored throughout the entire experiment using an extensive set of parameters, including macroscopic and microscopic activated sludge characteristics. Sludge hydrophobicity remained high (> 80%) throughout the experiment indicating good bioflocculation. However, sludge settleability decreased for all four reactors after a 60 day adaptation period to the applied alternation in influent carbon source. During this adaptation period, floc size decreased due to the release of microcolonies. The subsequent period was characterized by a decrease in settleability, coinciding with a release of primary particles and an increase in floc size. The observed phenomena could be linked with the protein concentration near the floc surface. This fraction mainly consists of hydrolytic enzymes necessary for the degradation of starch and is responsible for a progressive deterioration of the EPS matrix. The results of this specific study indicate to be independent of the influent carbon source ratio or switching frequency.

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Does a change in reactor loading rate affect activated sludge bioflocculation?

Cited by 26 publications

References 38 publications

Production of protein‐ and carbohydrate‐EPS in activated sludge reactors operated at different carbon to nitrogen ratios

Production of protein‐ and carbohydrate‐EPS in activated sludge reactors operated at different carbon to nitrogen ratios

Activated sludge characterization through microscopy: A review on quantitative image analysis and chemometric techniques

The effect of alternating influent carbon source composition on activated sludge bioflocculation

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