Microbial and operational response of an anaerobic fixed bed digester to oleic acid overloads

Cavaleiro, A. J.; Alves, M. M.; Мота, М.

doi:10.1016/s0032-9592(01)00219-9

Cited by 18 publications

(18 citation statements)

References 19 publications

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“…Adaptation of acetotrophic methanogens in continuously operated systems has previously been observed Cavaleiro et al, 2001). Cavaleiro et al (2001) found that a hydraulic shock (reduction of HRT) of oleate to an anaerobic filter induced an increase in the tolerance.…”

Section: Adaptation Of Microorganisms To Oleatementioning

confidence: 91%

“…However, continuous experiments with fixed-bed reactors have showed that pre-exposure of acetotrophic methanogens to lipids benefits the development of resistance to oleate . Cavaleiro et al (2001) found that a hydraulic shock (reduction of HRT) induced an increase in the resistance of acetotrophic methanogens towards oleate; whereas an organic shock of oleate (increase in substrate concentration) resulted in a lower resistance towards oleate.…”

Section: Introductionmentioning

confidence: 97%

“…Finally, acetate and H 2 are converted to CH 4 , CO 2 , and H 2 O by methanogens (Schink, 1988). During the anaerobic degradation of lipids, the oxidation of LCFA is known to be the rate-limiting step (Rinzema et al, 1994) and it is well documented that LCFA inhibit the anaerobic microbial activity at even low concentrations Angelidaki and Ahring, 1992;Cavaleiro et al, 2001;Hanaki et al, 1981;Hwu et al, 1996;Koster and Cramer, 1987;Lalman and Bagley, 2000, 2001Rinzema et al, 1989Rinzema et al, , 1994Shin et al, 2003). In fact, LCFA inhibits both acetotrophic and hydrogenotrophic methanogens as well as syntrophic acetogens.…”

Section: Introductionmentioning

confidence: 99%

“…For many years, the mechanism of inhibition by LCFA has been ascribed to mechanisms of cell wall damage and bactericidal effects (Rinzema et al, 1994) but recent research suggest that the inhibition is due to transport limitation such as product diffusion limitation, for example, biogas release (Pereira et al, 2003(Pereira et al, , 2005. Due to inhibition of acetogenic bacteria and methanogens, process inhibition in anaerobic digesters caused by LCFA will lead to both a decrease in methane production and an increase in VFA concentration (Cavaleiro et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

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Responses of the biogas process to pulses of oleate in reactors treating mixtures of cattle and pig manure

Nielsen

Ahring

2006

Biotech & Bioengineering

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The effect of oleate on the anaerobic digestion process was investigated. Two thermophilic continuously stirred tank reactors (CSTR) were fed with mixtures of cattle and pig manure with different total solid (TS) and volatile solid (VS) content. The reactors were subjected to increasing pulses of oleate. Following pulses of 0.5 and 1.0 g oleate/L, the most distinct increase in volatile fatty acid (VFA) concentrations were observed in the reactor with the lowest TS/VS content. This suggests a higher adsorption of oleate on the surfaces of biofibers in the reactor with the highest TS/VS and a less pronounced inhibition of the anaerobic digestion process. On the other hand, addition of 2.0 g oleate/L severely inhibited the process in both reactors, and a significant increase in all VFA concentrations combined with an immediate drop in methane production was noticed. However, 20 days after the reactors had been exposed to oleate both reactors showed a lower VFA concentration along with a higher methane production than before the pulses. This indicates that oleate had a stimulating effect on the overall process. The improved acetogenic and methanogenic activity in the reactors was confirmed in batch activity tests. In addition to this, toxicity tests revealed that the oleate pulses induced an increase in the tolerance level of acetotrophic methanogens towards oleate. When evaluating the usability of different process parameters (i.e., VFA and methane production) as indicators of process recovery, following the inhibition by oleate, propionate was found to be most suitable.

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Section: Adaptation Of Microorganisms To Oleatementioning

confidence: 91%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Responses of the biogas process to pulses of oleate in reactors treating mixtures of cattle and pig manure

Nielsen

Ahring

2006

Biotech & Bioengineering

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“…LCFA overloading has been shown to lead to volatile fatty acid (VFA) and LCFA accumulation that may significantly reduce methane production due to imbalances between acid consuming and methane producing microorganisms Angelidaki and Ahring 1992;Eiroa et al 2012;Rinzema et al 1994). Overloading of LCFA can cause concentrations of total volatile acids to be above 2000 mg COD/L or more and/or acetate concentrations above 500 mg COD/ L (Cavaleiro et al 2001;Cavaleiro et al 2009;Eiroa et al 2012). As the total calculated amounts of COD (<55 mg COD/L) and acetate (<15 mg COD/L) produced in this study for microcosms containing biodiesel are much less, they should not be inhibitory.…”

Section: Effects Of the Presence Of Biodiesel In The Anaerobic Degradmentioning

confidence: 99%

Influence of the Anaerobic Biodegradation of Different Types of Biodiesel on the Natural Attenuation of Benzene

Borges¹,

Dias²,

Danko³

2014

Water Air Soil Pollut

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In the present research work, different types of biodiesel were produced by a homogeneous alkali transesterification reaction using soybean oil, pork lard, and castor bean oil as raw materials, to evaluate how their different compositions may affect the biodegradability, namely, in the presence of benzene. Biodiesel was characterized according to the European standard EN 14214. The anaerobic biodegradation of the different types of biodiesel was examined as well as its influence on the biodegradation of benzene. Analyses were performed to determine the volume of methane (directly related to the anaerobic biodegradation of bio-diesel), the concentration of benzene over time, and the production of organic acids. The results showed methane production resulting from the anaerobic degradation of all biodiesel types. The differences between the degradation behavior of each fuel were negligible, contrary to what was expected; however, the amount of methane produced was low due to nutrient limitations. This fact was confirmed by the organic acid analysis as well as by the addition of new media. Anaerobic benzene biodegradation was found to be negatively impacted by the presence of all biodiesel types on average; therefore, the results of this study may impact management of sites that contain biodiesel and fuel hydrocarbon contamination.

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Mineralization of LCFA associated with anaerobic sludge: Kinetics, enhancement of methanogenic activity, and effect of VFA

Pereira

Sousa²,

Мота³

et al. 2004

Biotech & Bioengineering

171

100

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Long-chain fatty acids (LCFA) associated with anaerobic sludge by mechanisms of precipitation, adsorption, or entrapment can be biodegraded to methane. The mineralization kinetics of biomass-associated LCFA were established according to an inhibition model based on Haldane's enzymatic inhibition kinetics. A value around 1,000 mg COD-LCFAÁg VSS À1 was obtained for the optimal specific LCFA content that allowed the maximal mineralization rate. For sludge with specific LCFA contents of 2,838 F 63 and 4,571 F 257 mg COD-LCFAÁg VSS À1 , the specific methanogenic activities in the presence of acetate, butyrate, and H 2 /CO 2 were significantly enhanced after the mineralization of the biomass-associated LCFA. For sludge with a specific LCFA content near the optimal value defined by the kinetic model, the effect of adding VFA to the medium was studied during the mineralization of the biomass-associated LCFA. Different patterns were obtained for each individual substrate. Acetate and butyrate were preferentially consumed by the consortium, but in the case of propionate no evidence of a sequential consumption pattern could be withdrawn. It was concluded that LCFA do not exert a bactericidal neither a permanent toxic effect toward the anaerobic consortia. A discussion is addressed to the relative roles of a reversible inhibitory effect and a transport limitation effect imposed by the LCFA surrounding the cells. B

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Microbial and operational response of an anaerobic fixed bed digester to oleic acid overloads

Cited by 18 publications

References 19 publications

Responses of the biogas process to pulses of oleate in reactors treating mixtures of cattle and pig manure

Responses of the biogas process to pulses of oleate in reactors treating mixtures of cattle and pig manure

Influence of the Anaerobic Biodegradation of Different Types of Biodiesel on the Natural Attenuation of Benzene

Mineralization of LCFA associated with anaerobic sludge: Kinetics, enhancement of methanogenic activity, and effect of VFA

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