Process control factors influencing <i>Nocardia</i> populations in activated sludge

The Madison Metropolitan Sewerage District (The District) in Madison, Wisconsin has been experiencing seasonal foaming in their anaerobic biosolids digesters, which has occurred from mid‐November to late June for the past few years. The exact cause(s) of foaming is unknown. Previous research findings are unclear as to whether applications of advanced anaerobic digestion processes reduce the foaming potential of digesters. The object of this study was to investigate how configurations of thermophilic and acid phase‐thermophilic anaerobic digestion would affect foaming at the bench‐scale level compared to single stage mesophilic digestion for The District. Bench‐scale anaerobic digesters were fed with a 4 to 4.5% by dry weight of solids content blend of waste activated sludge (WAS) and primary sludge from The District. Foaming potential was monitored using Alka‐Seltzer and aeration foaming tests. The bench‐scale acid phase‐thermophilic digester had a higher foaming potential than the bench‐scale mesophilic digester. These results indicate that higher temperatures increase the foaming potential of the bench‐scale anaerobic digesters. The bench‐scale acid phase‐thermophilic digesters had a greater percent (approximately 5 to 10%) volatile solids destruction and a greater percent (approximately 5 to 10%) total solids destruction when compared to the bench‐scale mesophilic digester. Overall, for the full‐scale foaming experienced by The District, it appears that adding an acid phase or switching to thermophilic digestion would not alleviate The District's foaming issues.

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“…They also reported that if the MCRT was less than 5 days unstable foam was observed using the aeration foaming potential test. Cha et al (1992) …”

Section: Reduction In Sludge Agementioning

confidence: 99%

Foaming Phenomenon in Bench‐Scale Anaerobic Digesters

Siebels

Long

2013

Water Environment Research

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“…2). At the same temperature (ϳ24°C) as the one used in this study, Cha et al (10) previously suggested that a 1.6-day MCRT or SRT could wash out nocardioform foaming. However, such a reduction during the winter slow-growth period for heterotrophic bacteria could cause a marked negative effect on floc size, because extracellular polymer formation by bacteria occurs 30 to 40 h after their maximum growth (49), and also settling at the CWRP, as reported previously (42).…”

Section: Discussionmentioning

confidence: 94%

“…3a); however, many reports on nocardioforms in mixed liquors and surface foams of aeration tanks at full-scale plants have associated growth with summer months (14,55). A previous study of bench-scale activated sludge also found higher nocardioform filament counts at warmer temperatures when the MCRT was constant (10). The foaming episode in our study did occur as the temperature increased (late winter), which was agreement with previous studies from the Midwest, where filamentous bacterial growth and foaming occurred during late spring or summer, when temperatures increased 4°C to 6°C (14,48).…”

Section: Discussionmentioning

confidence: 96%

“…A number of operational and physicochemical parameters, such as extended mean cell residence times (MCRTs), high concentrations of long-chain hydrocarbons, certain pH ranges, and temperatures, were found to be factors that promoted foaming events (9,10,43,51). However, no common operational parameters, design criteria, and sewage compositions were found to be predictive of foaming events in full-scale Australian wastewater treatment plants (9).…”

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confidence: 99%

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Interaction of Operational and Physicochemical Factors Leading to Gordonia amarae-Like Foaming in an Incompletely Nitrifying Activated Sludge Plant

Asvapathanagul

Huang

Gedalanga

et al. 2012

Appl Environ Microbiol

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eThe overgrowth of Gordonia amarae-like bacteria in the mixed liquor of an incompletely nitrifying water reclamation plant was inversely correlated with temperature (r ‫؍‬ ؊0.78; P < 0.005) and positively correlated with the solids retention time (SRT) obtained a week prior to sampling (r ‫؍‬ 0.67; P < 0.005). Drops followed by spikes in the food-to-mass ratio (0.18 to 0.52) and biochemical oxygen demand concentrations in primary effluent (94 to 298 mg liter ؊1 ) occurred at the initiation of G. amarae-like bacterial growth. The total bacterial concentration did not increase as concentrations of G. amarae-like cells increased, but total bacterial cell concentrations fluctuated in a manner similar to that of G. amarae-like bacteria in the pseudo-steady state. The ammonium ion removal rate (percent) was inversely related to G. amarae-like cell concentrations during accelerated growth and washout phases. The dissolved oxygen concentration decreased as the G. amarae-like cell concentration decreased. The concentrations of G. amarae-like cells peaked (2.47 ؋ 10 9 cells liter ؊1 ) approximately 1.5 months prior to foaming. Foaming occurred during the late pseudo-steady-state phase, when temperature declines reversed. These findings suggested that temperature changes triggered operational and physicochemical changes favorable to the growth of G. amarae-like bacteria. Fine-scale quantitative PCR (qPCR) monitoring at weekly intervals allowed a better understanding of the factors affecting this organism and indicated that frequent sampling was required to obtain statistical significance with factors changing as the concentrations of this organism increased. Furthermore, the early identification of G. amarae-like cells when they are confined to mixed liquor (10 7 cells liter ؊1 ) allows management strategies to prevent foaming.

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“…For initial growth experiments the medium was either LB [27], or mineral salts medium [5] containing 0.5% (w/v) sodium acetate trihydrate. Single colonies of the untransformed and vgb-bearing G. amarae were inoculated into 5 ml of medium and grown overnight at 30°C and 200 rpm.…”

Section: Growth Measurementsmentioning

confidence: 99%

Expression of Vitreoscilla hemoglobin in Gordonia amarae enhances biosurfactant production

Doğan

Pagilla

Webster

et al. 2006

J IND MICROBIOL BIOTECHNOL

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The gene (vgb) encoding Vitreoscilla (bacterial) hemoglobin (VHb) was electroporated into Gordonia amarae, where it was stably maintained, and expressed at about 4 nmol VHb g À1 of cells. The maximum cell mass (OD 600 ) of vgb-bearing G. amarae was greater than that of untransformed G. amarae for a variety of media and aeration conditions (2.8-fold under normal aeration and 3.4-fold under limited aeration in rich medium, and 3.5-fold under normal aeration and 3.2-fold under limited aeration in mineral salts medium). The maximum level of trehalose lipid from cultures grown in rich medium plus hexadecane was also increased for the recombinant strain, by 4.0-fold in broth and 1.8-fold in cells under normal aeration and 2.1-fold in broth and 1.4-fold in cells under limited aeration. Maximum overall biosurfactant production was also increased in the engineered strain, by 1.4-fold and 2.4-fold for limited and normal aeration, respectively. The engineered strain may be an improved source for producing purified biosurfactant or an aid to microorganisms bioremediating sparingly soluble contaminants in situ.

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Process control factors influencing Nocardia populations in activated sludge

Cited by 51 publications

References 3 publications

Foaming Phenomenon in Bench‐Scale Anaerobic Digesters

Foaming Phenomenon in Bench‐Scale Anaerobic Digesters

Interaction of Operational and Physicochemical Factors Leading to Gordonia amarae-Like Foaming in an Incompletely Nitrifying Activated Sludge Plant

Expression of Vitreoscilla hemoglobin in Gordonia amarae enhances biosurfactant production

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