The microbiology of phosphorus removal in activated sludge processes-the current state of play

Seviour, Robert J.; McIlroy, Simon Jon

doi:10.1007/s12275-008-0051-0

Cited by 45 publications

(40 citation statements)

References 57 publications

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“…None in samples taken at the end of the aerobic stage stained positively for polyP in our study. Both variants occurred together in most of the EBPR plant samples examined, suggesting that they share an ecophysiology well suited to the alternative anaerobic:aerobic feast: famine conditions deliberately established in these processes (41,46), although they were also seen in non-EBPR biomass samples (Table 2). Which features might be competitively advantageous to such populations would include an ability for anaerobic substrate assimilation for the synthesis of storage material such as poly ␤-hydroxyalkanoates.…”

Section: Discussionmentioning

confidence: 99%

Filamentous Bacterium Eikelboom Type 0092 in Activated Sludge Plants in Australia Is a Member of the Phylum Chloroflexi

Speirs

Nittami

McIlroy

et al. 2009

Appl Environ Microbiol

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Molecular data show that the filamentous bacterium Eikelboom type 0092, frequently seen in Australian activated sludge plants, is a member of the phylum Chloroflexi. Fluorescence in situ hybridization (FISH) probes designed against cloned 16S rRNA sequences from a full-scale enhanced biological phosphate removalactivated sludge plant community, where this was a dominant filament morphotype, suggest that it can exist as two variants, differing in their trichome diameter. When applied to samples from several treatment plants in eastern Australia, each FISH probe targeted only the type 0092 filament morphotype against which it was designed. The patterns of FISH signals generated with both were consistent with the ribosomes not being evenly distributed but arranged as intracellular aggregates. The FISH survey data showed that these two variants appeared together in most but not all of the plants examined. None stained positively for intracellular presence of either poly-␤-hydroxyalkanoates or polyphosphate.Most activated sludge plants suffer from the operational disorders of bulking and foaming, both of which are caused by excessive growth of certain filamentous bacteria. Several different filament morphotypes have been described from systems treating domestic and industrial wastes (17, 18) but, in the absence of pure cultures, many of these have never been characterized sufficiently to resolve their taxonomy or provide them with valid names. Hence, they are often still referred to as numerical types persisting from the study of Eikelboom (18). Success has been achieved with some cultured and uncultured filaments in elucidating their phylogeny from 16S rRNA sequence analyses (6, 9, 10, 31, 50) and providing them with valid names (37, 49). Furthermore, with such sequence information, rRNA targeted oligonucleotide probes have been designed for their in situ identification and, together with microautoradiography (MAR) and other techniques (29,40), their ecophysiology may be elucidated (25,27,28). Type 0092, originally described by Eikelboom (18), appears prominently in many filament surveys carried out on plants around the world, where microscopy was used to identify them (35, 48). These morphotypes have been associated especially with long sludge age (Ͼ15-day) operational conditions (22) and thus frequently appear in enhanced biological phosphate removal (EBPR) systems (see, for example, reference 11), where the biomass is recycled repeatedly through anaerobic: aerobic zones. Consequently, this filament morphotype was classified as an "all-zone" grower by Wanner and Grau (52), able in their view to grow under aerobic, anoxic, and anaerobic conditions. However, its physiology from pure culture studies was described as being strictly aerobic (13, 21). These isolates were never deposited in recognized culture collections, and so confirmation of their identity is difficult. Similarly, the precise identification of the type 0092 filaments claimed to have been cultured by Ramothokang et al. (43) is unclear.Type 0092 has ver...

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Section: Discussionmentioning

confidence: 99%

Filamentous Bacterium Eikelboom Type 0092 in Activated Sludge Plants in Australia Is a Member of the Phylum Chloroflexi

Speirs

Nittami

McIlroy

et al. 2009

Appl Environ Microbiol

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“…In the following oxic treatment phase, the same bacteria exhibit a 'luxury uptake' of phosphate along with accumulation of polyphosphate. This concept is generally accepted, although the identification and cultivation of the relevant polyphosphate-accumulating organisms has proven to be problematic (Seviour and McIlroy, 2008). Moreover, Comeau et al (1986) report that sulfide addition stimulated phosphate release, but this result was not included into the concept of polyphosphate usage and, to our knowledge, has not further been investigated.…”

Section: Introductionmentioning

confidence: 96%

Sulfide induces phosphate release from polyphosphate in cultures of a marine Beggiatoa strain

2010

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Sulfur bacteria such as Beggiatoa or Thiomargarita have a particularly high capacity for storage because of their large size. In addition to sulfur and nitrate, these bacteria also store phosphorus in the form of polyphosphate. Thiomargarita namibiensis has been shown to release phosphate from internally stored polyphosphate in pulses creating steep peaks of phosphate in the sediment and thereby inducing the precipitation of phosphorus-rich minerals. Large sulfur bacteria populate sediments at the sites of recent phosphorite formation and are found as fossils in ancient phosphorite deposits. Therefore, it can be assumed that this physiology contributes to the removal of bioavailable phosphorus from the marine system and thus is important for the global phosphorus cycle. We investigated under defined laboratory conditions which parameters stimulate the decomposition of polyphosphate and the release of phosphate in a marine Beggiatoa strain. Initially, we tested phosphate release in response to anoxia and high concentrations of acetate, because acetate is described as the relevant stimulus for phosphate release in activated sludge. To our surprise, the Beggiatoa strain did not release phosphate in response to this treatment. Instead, we could clearly show that increasing sulfide concentrations and anoxia resulted in a decomposition of polyphosphate. This physiological reaction is a yet unknown mode of bacterial polyphosphate usage and provides a new explanation for high phosphate concentrations in sulfidic marine sediments.

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“…Phosphorus removal is achieved by the Betaproteobacteria species tentatively named "Candidatus Accumulibacter phosphatis" and generally referred to as polyphosphate (poly-P)-accumulating organisms (PAOs) or Accumulibacter (11,49,64). When exposed to anaerobic-aerobic/anoxic cycles, PAOs have the metabolic capacity to take up phosphate beyond their anabolic requirements and store it intracellularly as poly-P.…”

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Dynamics of Microbial Community Structure of and Enhanced Biological Phosphorus Removal by Aerobic Granules Cultivated on Propionate or Acetate

Gonzalez-Gil

Holliger

2011

Appl Environ Microbiol

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Aerobic granules are dense microbial aggregates with the potential to replace floccular sludge for the treatment of wastewaters. In bubble-column sequencing batch reactors, distinct microbial populations dominated propionate-and acetate-cultivated aerobic granules after 50 days of reactor operation when only carbon removal was detected. Propionate granules were dominated by Zoogloea (40%), Acidovorax, and Thiothrix, whereas acetate granules were mainly dominated by Thiothrix (60%). Thereafter, an exponential increase in enhanced biological phosphorus removal (EBPR) activity was observed in the propionate granules, but a linear and erratic increase was detected in the acetate ones. Besides Accumulibacter and Competibacter, other bacterial populations found in both granules were associated with Chloroflexus and Acidovorax. The EBPR activity in the propionate granules was high and stable, whereas EBPR in the acetate granules was erratic throughout the study and suffered from a deterioration period that could be readily reversed by inducing hydrolysis of polyphosphate in presumably saturated Accumulibacter cells. Using a new ppk1 gene-based dual terminalrestriction fragment length polymorphism (T-RFLP) approach revealed that Accumulibacter diversity was highest in the floccular sludge inoculum but that when granules were formed, propionate readily favored the dominance of Accumulibacter type IIA. In contrast, acetate granules exhibited transient shifts between type I and type II before the granules were dominated by Accumulibacter type IIA. However, ppk1 gene sequences from acetate granules clustered separately from those of propionate granules. Our data indicate that the mere presence of Accumulibacter is not enough to have consistently high EBPR but that the type of Accumulibacter determines the robustness of the phosphate removal process.In sequencing batch reactors operated under high shear stress and short setting times, microorganisms involved in wastewater treatment can form structures called aerobic granules (1). Aerobic granules are compact quasispherical aggregates formed by self-immobilized mixed microbial communities embedded in a matrix of extracellular biopolymeric substances (35). These microbial aggregates can accommodate a biomass concentration five times higher than that of activated sludge flocs (13) and settle 10 times faster (42, 60). These characteristics translate into small-footprint treatment plants, and therefore the use of aerobic granular sludge-based systems has recently been proposed as a promising alternative technology to conventional activated sludge treatment systems, with annual maintenance costs and land requirements that would be reduced by 17% and

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The microbiology of phosphorus removal in activated sludge processes-the current state of play

Cited by 45 publications

References 57 publications

Filamentous Bacterium Eikelboom Type 0092 in Activated Sludge Plants in Australia Is a Member of the Phylum Chloroflexi

Filamentous Bacterium Eikelboom Type 0092 in Activated Sludge Plants in Australia Is a Member of the Phylum Chloroflexi

Sulfide induces phosphate release from polyphosphate in cultures of a marine Beggiatoa strain

Dynamics of Microbial Community Structure of and Enhanced Biological Phosphorus Removal by Aerobic Granules Cultivated on Propionate or Acetate

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