Solids retention time in heterotrophic and nitrifying biofilms in a biofilm airlift suspension reactor

Benthum, W. A. J. van; Loosdrecht, Mark C.M. van; Tijhuis, L.; Heijnen, J. J.

doi:10.2166/wst.1995.0262

Cited by 10 publications

(9 citation statements)

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“…water. Studies on a rotating annular reactor or an airlift suspension reactor also showed lower adsorption efficiencies of biofilms in the diurnal time frame (13,43,44). Reactors in these studies worked in a continuous mode, which entails lower and more constant particle concentrations than the batch mode.…”

Section: Discussionmentioning

confidence: 89%

“…These filters comprise mature biofilms with highly dynamic microbial populations, for which particulate material constitutes an important carbon resource (22,28). Consequently, the interception of particles by the biofilm is essential for the performance of bioreactors (44). Since particles tend to accumulate hazardous pollutants at their surface, their removal from wastewater is all the more important (26).…”

mentioning

confidence: 99%

“…In contrast, other reactor types are operated in a continuous mode, in which wastewater permanently passes through the system. Particle retention is a fundamental factor in these technologies, since it determines biofilm function (35,44). To achieve a better assessment of reactor types, particle retention should be specifically examined for each application.…”

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confidence: 99%

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Interception of Small Particles by Flocculent Structures, Sessile Ciliates, and the Basic Layer of a Wastewater Biofilm

Eisenmann¹,

Letsiou²,

Feuchtinger³

et al. 2001

Appl Environ Microbiol

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We investigated attachment processes of hydrophobic and hydrophilic particles (diameter ‫؍‬ 1 m) to mature biofilms grown on clay marbles in a sequencing batch biofilm reactor. During a treatment cycle with filtered wastewater containing different fluorescent beads, the progression of particle density in various biofilm compartments (carrier biofilm, basic biofilm layer, biofilm flocs, and sessile ciliates) was determined by flow cytometry, confocal laser scanning microscopy and automated image analysis. Particles were almost completely removed from wastewater by typical processes of particle retention: up to 58% of particles attached to clay marbles, up to 15% were associated with suspended flocs, and up to 10% were ingested by sessile ciliates. Ingestion of particles by ciliates was exceptionally high immediately after wastewater addition (1,200 particles grazer ؊1 h ؊1 ) and continued until approximately 14% of the water had been cleared by ciliate filter feeding. Most probably, ciliate bioturbation increases particle sorption to the basic biofilm. Backwashing of the reactor detached pieces of biofilm and thus released approximately 50% of the particles into rinsing water. Clay marbles in the upper part of the reactor were more efficiently abraded than in the lower part. No indications for selective attachment of the applied hydrophobic and hydrophilic beads were found. As a consequence of interception patterns, organisms at elevated biofilm structures are probably major profiteers of wastewater particles; among them, ciliates may be of major importance because of their highly active digestive food vacuoles.

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Section: Discussionmentioning

confidence: 89%

mentioning

confidence: 99%

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Interception of Small Particles by Flocculent Structures, Sessile Ciliates, and the Basic Layer of a Wastewater Biofilm

Eisenmann¹,

Letsiou²,

Feuchtinger³

et al. 2001

Appl Environ Microbiol

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“…Generally, the biofilms, obtained within 7 d of cultivation in the present study had the structure that is known to develop under the substrate regime that used in the experiments (Costerton et al, 1995;Yang et al, 2000). Features of this structure include nonuniform thickness, patchyness, and presence of pores up to 100 Jim in diameter allowing penetration of particles into the biofilm and water flow below its surface (Costerton et al, 1995;van Benthum et al, 1995). Both heterotrophically grown and nitrifying biofilms showed this type of structure, which should allow the penetration of SRB into deeper regions of the biofilms, in the vicinity of anoxic zones.…”

Section: Discussionmentioning

confidence: 96%

Colonization of aerobic biofilms by sulfate‐reducing bacteria

Power

Meer

Harms³

et al. 2001

Biofouling

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The ability of the SRB Desulfovibrio desulfuricans to colonize aerobic heterotrophic or nitrifying biofilms on stainless steel surfaces was investigated by fluorescence in situ hybridization (FISH) in combination with confocal laser scanning microscopy (CLSM), the polymerase chain reaction (PCR) directed to the dissimilatory sulfite reductase and by oxygen microelectrodes. Biofilms of heterotrophic bacteria and of nitrifying bacteria pregrown on steel coupons in laboratory devices were not invaded by cells of D. desulfuricans within 1 week, even though large pores as possible entry paths and anoxic zones and sulfate in the medium as prerequisites for activity of D. desulfuricans existed in the biofilms. On the contrary, coinoculation of D. desulfuricans and aerobic heterotrophic bacteria from water of a cooling water system led to immediate establishment of a small but detectable population of D. desulfuricans distributed over the whole biofilm depth. The fact that individual SRB attached efficiently and irreversibly to steel suggests that in coinoculation experiments, establishment of SRB in the biofilm possibly occurred from the biofilm base, which is the zone that became anoxic first. Based on these findings it is suggested that the idea of protecting surfaces from SRB-induced corrosion by pregrowing and maintaining specific bacterial biofilms should be further pursued.

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“…The biomass density in granules was set to 80000 gCOD/m 3 . [26] This represents a concentration in the granules of 60000 gVSS/m 3 for a conversion factor of 0.75 gVSS/gCOD. [27] Porosity was assumed constant (80%) throughout the granule.…”

Section: Granular Sludgementioning

confidence: 99%

Analysing the effects of the aeration pattern and residual ammonium concentration in a partial nitritation-anammox process

Corbala-Robles

Picioreanu

Loosdrecht

et al. 2015

Environmental Technology

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A mathematical model was used to evaluate the effect of the aeration pattern and ammonium concentration in a partial nitritation-anammox sequencing batch reactor with granular and flocculent sludge. In the tested conditions, model results indicate that most of the aerobic ammonium oxidation potential would occur in the bulk liquid, with 70% of the ammonium-oxidizing bacteria (AOB) biomass in suspension rather than in granules. The simulated granular sludge consisted predominantly of anammox bacteria with AOB present in the outer layer of the granule (50 μm AOB layer, accounting for 3% of the granule weight). Simulation results indicated that when granules do not contain any AOB, the amount of granular biomass required to achieve the same level of nitrogen removal would strongly increase (in the simulated conditions, by a factor of three) due to anammox inhibition by oxygen. This underlines the importance of a small fraction of AOB present in the granular anammox sludge. The aeration pattern had an important impact on the nitrogen removal: a better performance was suggested for continuous aeration (90% N-removal) than for intermittent aeration (68-84% N-removal). Anammox inhibition during the periods of high oxygen concentration was identified as the main reason for the lower nitrogen removal in the intermittently aerated system. With increasing oxygen concentration, a higher residual (effluent) ammonium concentration was needed to assure nitrite-oxidizing bacteria repression in the system. This study contributes to further understand the complexity of a reactor with both granular and flocculent sludge and the impact of operation conditions on reactor performance.

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Solids retention time in heterotrophic and nitrifying biofilms in a biofilm airlift suspension reactor

Cited by 10 publications

References 0 publications

Interception of Small Particles by Flocculent Structures, Sessile Ciliates, and the Basic Layer of a Wastewater Biofilm

Interception of Small Particles by Flocculent Structures, Sessile Ciliates, and the Basic Layer of a Wastewater Biofilm

Colonization of aerobic biofilms by sulfate‐reducing bacteria

Analysing the effects of the aeration pattern and residual ammonium concentration in a partial nitritation-anammox process

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