Comparison of carbon storage under aerobic and anoxic conditions

Majone, Mauro; Massanisso, P.; Ramadori, R.

doi:10.2166/wst.1998.0793

Cited by 31 publications

(31 citation statements)

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“…The analysis of the data indicates that, when acetate and ammonia are in excess, the corresponding uptake rates follow zero order kinetics, which is in accordance to several published studies (Beccari et al, 1998;Beun et al, 2000Beun et al, , 2002Dircks et al, 1999Dircks et al, , 2001Krishna and van Loosdrecht, 1999;Majone et al, 1998;Serafim et al, 2004;Third et al, 2003;van Aalst-van Leeuwen et al, 1997). A considerable deviation is however observed for high intracellular PHB contents, suggesting a possible inhibition effect of PHB on acetate uptake as shown later in this work.…”

Section: Resultssupporting

confidence: 92%

Mathematical modelling of a mixed culture cultivation process for the production of polyhydroxybutyrate

Dias

Serafim

Lemos

et al. 2005

Biotechnol. Bioeng.

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Mixed cultures submitted to acetate "feast" and "famine" cycles are able to store intracellularly high quantities of polyhydroxybutyrate (PHB). It was demonstrated in a previous study that the intracellular PHB content can be increased up to 78.5% (g HB/gVSS) of cell dry weight in a sequencing batch reactor (SBR) with optimised operating conditions. The specific PHB formation rate was also shown to be higher for mixed cultures than for pure cultures. Such high intracellular PHB contents and specific productivity open new perspectives for the industrial production of polyhydroxyalkanoates (PHA) using mixed cultures instead of pure cultures. The main goal in this work was to develop a mathematical model of mixed cultures envisaging the optimisation of PHB production. A relatively simple two-compartments cell model was developed based on experimental observations and other models proposed in the literature. A convenient experimental planing allowed to identify the kinetic parameters and yield coefficients. Experiments were performed with and without ammonia limitation enabling the analysis of PHB formation independently of the cell growth process. The experimental true yields partially confirm the theoretical values proposed in the literature. The final model exhibited high accuracy in describing the process state of most experiments performed, thus opening good perspectives for future model-based optimisation studies.

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Section: Resultssupporting

confidence: 92%

Mathematical modelling of a mixed culture cultivation process for the production of polyhydroxybutyrate

Dias

Serafim

Lemos

et al. 2005

Biotechnol. Bioeng.

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“…In many bacteria, PHB is used as both a growth substrate and a source of reducing power under conditions of carbon starvation (3,4,9,11,13,31,33), enabling PHB-rich cells to replicate in the absence of an exogenous carbon source. In M. parvus OBBP, however, stored PHB did not enable replication in the absence of exogenous carbon when all other nutrients were present.…”

Section: Discussionmentioning

confidence: 99%

“…When PHB was present without exogenous nitrogen or carbon, the concentration of cells did not increase. Activated sludge enrichments also replicated using stored PHB as a carbon source when no external carbon was present during cyclic pulse feeding of carbon (3,4,9,12,13,31). In the absence of both carbon and nitrogen, PHB degraded more slowly than when nitrogen was present (36).…”

mentioning

confidence: 99%

Poly-3-Hydroxybutyrate Metabolism in the Type II Methanotroph Methylocystis parvus OBBP

Pieja

Sundström

Criddle

2011

Appl Environ Microbiol

116

102

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Differences in carbon assimilation pathways and reducing power requirements among organisms are likely to affect the role of the storage polymer poly-3-hydroxybutyrate (PHB). Previous researchers have demonstrated that PHB functions as a sole growth substrate in aerobic cultures enriched on acetate during periods of carbon deficiency, but it is uncertain how C 1 metabolism affects the role of PHB. In the present study, the type II methanotroph Methylocystis parvus OBBP did not replicate using stored PHB in the absence of methane, even when all other nutrients were provided in excess. When PHB-rich cultures of M. parvus OBBP were deprived of carbon and nitrogen for 48 h, they did not utilize significant amounts of stored PHB, and neither cell concentrations nor concentrations of total suspended solids changed significantly. When methane and nitrogen both were present, PHB and methane were consumed simultaneously. Cells with PHB had significantly higher specific growth rates than cells lacking PHB. The addition of formate (a source of reducing power) to PHB-rich cells delayed PHB consumption, but the addition of glyoxylate (a source of C 2 units) did not. This and results from other researchers suggest that methanotrophic PHB metabolism is linked to the supply of reducing power as opposed to the supply of C 2 units for synthesis.Poly-3-hydroxybutyrate (PHB) is a biologically produced, biodegradable polyester with properties similar to those of polypropylene and mechanical properties that can be tailored for different applications by changing the copolymer content of the polymer (1, 5, 27). Many bacteria accumulate PHB as a carbon storage polymer under conditions of unbalanced growth (i.e., nutrient deficiency and/or carbon excess) (1, 27). Although considerable efforts are currently being devoted to commercializing microbial PHB production, commercialization thus far has been limited because of the relatively high production cost of PHB compared to that of traditional petrochemical-based plastics, such as polyethylene and polypropylene (28). A major fraction of the production cost (30%) (7) is due to feedstocks, which are typically sugars such as glucose and sucrose (27).Methane is both an inexpensive feedstock for PHB production and a potent greenhouse gas; its use as a substrate for PHB production is therefore an effective means of carbon sequestration and an attractive alternative to sugar-based feedstocks. Methanotrophs have been shown to produce PHB (2, 18, 37, 41-44), and Wendlandt et al. (42) have reported PHB levels of up to 30 g liter Ϫ1 in a culture dominated by Methylocystis sp. GB 25 and maintained under nonaseptic conditions. While PHB production is well characterized in a variety of bacteria, comparatively few studies have investigated why bacteria accumulate PHB or the process of PHB consumption (16,20,33,36,41). In nonmethanotrophs, PHB consumption is linked to both short-term replication and long-term survival under carbon starvation. Handrick et al. (16) concluded that Ralstonia eutropha replicat...

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“…As autotrophic nitrifi cation is slow, SND requires slowly biodegradable organic substrates, such as internal storage polymers. The internal carbon source is degraded much slower than a soluble substrate and can be used as an electron donor for denitrifi cation if no external substrate is available [10,13,3]. The ability of heterotrophs to rapidly remove the soluble substrate and store it as a slowly degradable polymer represents a convenient opportunity to preserve reducing power for SND.…”

Section: Resultsmentioning

confidence: 99%

Simultaneous Nitrification and Denitrification in an SBR with a Modified Cycle During Reject Water Treatment

Bernat¹

2013

Archives of Environmental Protection

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Keywords: Anaerobic sludge digester supernatant, SBR, simultaneous nitrifi cation and denitrifi cation (SND).Abstract: In this study, the dependence between volumetric exchange rate (n) in an SBR (Sequencing Batch Reactor) with a modifi ed cycle and simultaneous nitrifi cation and denitrifi cation (SND) effi ciency during the treatment of anaerobic sludge digester supernatant was determined. In the SBR cycle alternating three aeration phases (with limited dissolved oxygen (DO) concentration up to 0.7 mg O 2 /L) and two mixing phases were applied. The lengths of each aeration and mixing phases were 4 and 5.5 h, respectively. Independently of n, a total removal of ammonium was achieved. However, at n = 0.1 d -1 and n = 0.3 d -1 nitrates were the main product of nitrifi cation, while at n = 0.5 d -1, both nitrates and nitrites occurred in the effl uent. Under these operational conditions, despite low COD/N (ca. 4) ratio in the infl uent, denitrifi cation in activated sludge was observed. A higher denitrifi cation effi ciency at n = 0.5 d -1 (51.3%) than at n = 0.1 d -1 (7.8%) indicated that n was a crucial factor infl uencing SND via nitrite and nitrate in the SBR with a low oxygen concentration in aeration phases.

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Comparison of carbon storage under aerobic and anoxic conditions

Cited by 31 publications

References 0 publications

Mathematical modelling of a mixed culture cultivation process for the production of polyhydroxybutyrate

Mathematical modelling of a mixed culture cultivation process for the production of polyhydroxybutyrate

Poly-3-Hydroxybutyrate Metabolism in the Type II Methanotroph Methylocystis parvus OBBP

Simultaneous Nitrification and Denitrification in an SBR with a Modified Cycle During Reject Water Treatment

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