scholarly journals Volatile fatty acids build-up and its effect on E. coli inactivation during excreta stabilisation in single-stage and two-stage systems

2018 ◽  
Vol 8 (2) ◽  
pp. 257-267 ◽  
Author(s):  
Joy Riungu ◽  
Mariska Ronteltap ◽  
Jules B. van Lier
Keyword(s):  
Fatty Acids ◽  
Decay Rate ◽  
Volatile Fatty Acids ◽  
Flow Reactor ◽  
Plug Flow ◽  
Single Stage ◽  
Pathogen Inactivation ◽  
Two Stage ◽  
E Coli ◽  
Reactor Length

Abstract Digestion and co-digestion of faecal matter collected from urine diverting dehydrating toilet faeces (UDDT-F) and mixed organic market waste (OMW) was studied in single stage pilot scale mesophilic plug-flow anaerobic reactors at UDDT-F:OMW ratios 4:1 and 1:0. Escherichia coli inactivation and volatile fatty acids (VFA) build-up was monitored at sampling points located along the reactor profile. When applying UDDT-F:OMW ratio of 4:1 at 12% total solids (TS), E. coli inactivation achieved was 2.3 log times higher than that achieved in UDDT-F:OMW ratio of 1:0. In subsequent trials, a two-stage reactor was researched, applying a UDDT-F:OMW ratio of 4:1 and 10 or 12% TS slurry concentrations. Highest VFA concentrations of 16.3 ± 1.3 g/L were obtained at a pH of 4.9 in the hydrolysis/acidogenesis reactor, applying a UDDT-F:OMW ratio of 4:1 and 12% TS, corresponding to a non-dissociated (ND)-VFA concentration of 6.9 ± 2.0 g/L. The corresponding decay rate reached a value of 1.6 per day. In the subsequent methanogenic plug-flow reactor, a decay rate of 1.1 per day was attained within the first third part of the reactor length, which declined to 0.6 per day within the last third part of the reactor length. Results show that a two-stage system is an efficient way to enhance pathogen inactivation during anaerobic digestion.

Volatile fatty acids production by mesophilic fermentation of mechanically-sorted urban organic wastes in a plug-flow reactor

1995 ◽  
Vol 51 (1) ◽  
pp. 89-96 ◽  
Author(s):  
C. Sans ◽  
J. Mata-Alvarez ◽  
F. Cecchi ◽  
P. Pavan ◽  
A. Bassetti
Keyword(s):  
Fatty Acids ◽  
Volatile Fatty Acids ◽  
Flow Reactor ◽  
Plug Flow ◽  
Organic Wastes ◽  
Plug Flow Reactor

A Mathematical Model of Volatile Fatty Acids (VFA) Production in a Plug-Flow Reactor Treating the Organic Fraction of Municipal Solid Waste (MSW)

1993 ◽  
Vol 27 (2) ◽  
pp. 201-208 ◽  
Author(s):  
E. D. Negri ◽  
J. Mata-Alvarez ◽  
C. Sans ◽  
F. Cecchi
Keyword(s):  
Mathematical Model ◽  
Fatty Acids ◽  
Municipal Solid Waste ◽  
Volatile Fatty Acids ◽  
Flow Reactor ◽  
Plug Flow ◽  
Biomass Concentration ◽  
Organic Fraction ◽  
Initial Biomass Concentration ◽  
Suspended Biomass

A mathematical model of a plug-flow reactor with a fluid recycle has been elaborated to simulate the VFA production process treating the organic fraction of the municipal solid waste. An alternative hydrolytic reaction model (homogeneous - heterogeneous) is proposed. The effect of a possible methanization step is also considered. The effect of process parameters (solid retention time (SRT), pH, recycle ratio) on the reactor performance is analyzed for parameters based on fruit and vegetable waste. The sensitivity of the model to proposed parameters (suspended biomass and initial biomass concentration) is also evaluated. It is found that the reactor production is very sensitive to the system pH. At low SRT, the production of volatile fatty acids (VFA) is proportional to this parameter. As the SRT increases methanization can reduce the VFA production. The effect of the recycle is negligible for the system and operating conditions studied. The effect of suspended biomass and initial biomass concentration was found to be also negligible. For the system analyzed, the pH is a critical parameter and a plug-flow arrangement (without recycle) seems to be the more reasonable election.

Single-Stage and Two-Stage Anaerobic Digestion of Food Waste: Effect of the Organic Loading Rate on the Methane Production and Volatile Fatty Acids

2021 ◽  
Vol 232 (3) ◽  
Author(s):  
Brayan Alexis Parra-Orobio ◽  
Mariano Nicolas Cruz-Bournazou ◽  
Patricia Torres-Lozada
Keyword(s):  
Fatty Acids ◽  
Anaerobic Digestion ◽  
Food Waste ◽  
Methane Production ◽  
Volatile Fatty Acids ◽  
Loading Rate ◽  
Single Stage ◽  
Organic Loading Rate ◽  
Organic Loading ◽  
Two Stage

scholarly journals Effect of Biowaste Sludge Maturation on the Diversity of Thermophilic Bacteria and Archaea in an Anaerobic Reactor

2009 ◽  
Vol 75 (8) ◽  
pp. 2566-2572 ◽  
Author(s):  
M. Goberna ◽  
H. Insam ◽  
I. H. Franke-Whittle
Keyword(s):  
Fatty Acids ◽  
Volatile Fatty Acids ◽  
Flow Reactor ◽  
Thermophilic Bacteria ◽  
Plug Flow ◽  
Phylogenetic Groups ◽  
Anaerobic Reactor ◽  
Prokaryotic Diversity ◽  
Major Shift ◽  
Stable Community

ABSTRACT Prokaryotic diversity was investigated near the inlet and outlet of a plug-flow reactor. After analyzing 800 clones, 50 bacterial and 3 archaeal phylogenetic groups were defined. Clostridia (>92%) dominated among bacteria and Methanoculleus (>90%) among archaea. Significant changes in pH and volatile fatty acids did not invoke a major shift in the phylogenetic groups. We suggest that the environmental filter imposed by the saline conditions (20 g liter−1) selected a stable community of halotolerant and halophilic prokaryotes.

Increasing 2 -Bio- (H2 and CH4) production from food waste by combining two-stage anaerobic digestion and electrodialysis for continuous volatile fatty acids removal

2021 ◽  
Vol 129 ◽  
pp. 20-25
Author(s):  
Gamal K. Hassan ◽  
Rhys Jon Jones ◽  
Jaime Massanet-Nicolau ◽  
Richard Dinsdale ◽  
M.M. Abo-Aly ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Anaerobic Digestion ◽  
Food Waste ◽  
Volatile Fatty Acids ◽  
Two Stage ◽  
Ch4 Production

Analysis of Equilibrium Shifting by Inter-Stage Reactant Feeding in a Series of Isothermal Reactors

2014 ◽  
Vol 12 (1) ◽  
pp. 163-179
Author(s):  
Florent Allain ◽  
Jean-François Portha ◽  
Laurent Falk
Keyword(s):  
Flow Reactor ◽  
Homogeneous Model ◽  
Plug Flow ◽  
Volumetric Flow Rate ◽  
Continuous Reactor ◽  
Two Stage ◽  
Heterogeneous Model ◽  
Number Systems ◽  
Reversible Reactions ◽  
The Impact

Abstract This paper focuses on the impact of reactant staging on conversion for one single reversible reaction in a two-stage, isothermal, continuous reactor. The analytical expression of global conversion has been derived for a series of two continuously stirred-tank reactors. Improvements in the overall conversion and yield by staging can be obtained for low Damköhler number systems leading to low conversions, when the volumetric flow rate of the staged reactant has a higher value than that of the other one. The example of triolein transesterification involving three reversible reactions in a two-stage plug flow reactor is also studied as a concrete example of a consecutive/parallel reversible reactions system. Results are obtained by using a pseudo-homogeneous model and are compared with those obtained with a heterogeneous model from a previous study.

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