Hydrogen-dependent control of the continuous anaerobic digestion process

Whitmore, T. N.; Lloyd, David; Jones, G.; Williams, T.Norman

doi:10.1007/bf00256675

Cited by 60 publications

(22 citation statements)

References 18 publications

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“…However, the average floc size began to decrease around day 35. Others had speculated that vigorous mixing disrupts the spatial juxtaposition of microorganisms (Conrad et al, 1985;Dolfing, 1992;Whitmore et al, 1987). Not only have we found this to be true, we also found that it can completely break syntrophic relationships, even at low mixing intensities when digesters are completely mixed.…”

Section: Continuous Mixing Disrupted Microbial Flocs Regardless Of Thsupporting

confidence: 48%

Effect of shear on performance and microbial ecology of continuously stirred anaerobic digesters treating animal manure

Hoffmann

García

Veskivar

et al. 2007

Biotech & Bioengineering

156

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We determined the effect of different mixing intensities on the performance, methanogenic population dynamics, and juxtaposition of syntrophic microbes in anaerobic digesters treating cow manure from a dairy farm. Computer automated radioactive particle tracking in conjunction with computational fluid dynamics was performed to quantify the shear levels locally. Four continuously stirred anaerobic digesters were operated at different mixing intensities of 1,500, 500, 250, and 50 revolutions per min (RPM) over a 260-day period at a temperature of 34 +/- 1 degrees C. Animal manure at a volatile solids (VS) concentration of 50 g/L was fed into the digesters daily at five different organic loading rates between 0.6 and 3.5 g VS/L day. The different mixing intensities had no effect on the biogas production rates and yields at steady-state conditions. A methane yield of 0.241 +/- 0.007 L CH(4)/g VS fed was obtained by pooling the data of all four digesters during steady-state periods. However, digester performance was affected negatively by mixing intensity during startup of the digesters, with lower biogas production rates and higher volatile fatty acids concentrations observed for the 1,500-RPM digester. Despite similar methane production yields and rates, the acetoclastic methanogenic populations were different for the high- and low-intensity mixed digesters with Methanosarcina spp. and Methanosaeta concilii as the predominant methanogens, respectively. For all four digesters, epifluorescence microscopy revealed decreasing microbial floc sizes beginning at week 4 and continuing through week 26 after which no microbial flocs remained. This decrease in size, and subsequent loss of microbial flocs did not, however, produce any long-term upsets in digester performance.

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Section: Continuous Mixing Disrupted Microbial Flocs Regardless Of Thsupporting

confidence: 48%

Effect of shear on performance and microbial ecology of continuously stirred anaerobic digesters treating animal manure

Hoffmann

García

Veskivar

et al. 2007

Biotech & Bioengineering

156

View full text Add to dashboard Cite

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“…A clear relationship between digester loading status and the dissolved hydrogen concentration (Figs. 2, 4, 8) was detected, which has not been previously established, despite the fact that the potential use of hydrogen as a control parameter for anaerobic digesters has been extensively discussed in the literature (Archer et al, 1986;Kidby and Nodwell, 1991;McCarty and Smith, 1986;Whitmore et al, 1987). However, this relationship occurred at very low H 2 levels.…”

Section: The Requirement For Hydrogen Measurement At Low Levels To Decontrasting

confidence: 38%

“…5). This can be observed in cases of severe shockloading (Whitmore et al, 1987;Strong and CordRuwisch, 1995). Our experimental findings do not confirm the expected relationship, but show a quasi-linear relation- Figure 9.…”

Section: Theoretically Expected Relationship Between H 2 Partial Presmentioning

confidence: 91%

“…Digester shockloading is known to cause a clear hydrogen signal (10-400 Pa) in the biogas or liquid phase, which can be detected with hydrogen probes (Strong and Cord-Ruwisch, 1995), mass spectrometry (Whitmore et al, 1987), polarographic exhaled hydrogen monitor (Archer et al, 1986;Fitzgerald, 1994;Mathiot et al, 1992) and trace reduction gas analysis (McCarty and Smith, 1986). However, problems have been encountered with insufficient sensitivity (Kuroda et al, 1991;Strong and Cord-Ruwisch, 1995;Whitmore et al, 1987), interference from other compounds (Kuroda et al, 1991), and mass transfer problems of gaseous hydrogen causing overconcentration of hydrogen in the liquid phase (Frigon and Guiot, 1995;Pauss and Guiot, 1993;Pauss et al, 1990).…”

Section: Introductionmentioning

confidence: 99%

“…As the increase in hydrogen concentration is the cause for the accumulation of VFAs, the use of dissolved or gaseous hydrogen concentration as a parameter for monitoring the status of anaerobic digestion and as a potential control parameter for controlling industrial anaerobic digesters has been suggested (Archer et al, 1986;Collins and Paskins, 1987;Kidby and Nedwell, 1991;McCarty and Smith, 1986;Whitmore et al, 1987). Digester shockloading is known to cause a clear hydrogen signal (10-400 Pa) in the biogas or liquid phase, which can be detected with hydrogen probes (Strong and Cord-Ruwisch, 1995), mass spectrometry (Whitmore et al, 1987), polarographic exhaled hydrogen monitor (Archer et al, 1986;Fitzgerald, 1994;Mathiot et al, 1992) and trace reduction gas analysis (McCarty and Smith, 1986).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Dissolved hydrogen concentration as an on-line control parameter for the automated operation and optimization of anaerobic digesters

Cord‐Ruwisch

Mercz

Hoh

et al. 1997

Biotechnol. Bioeng.

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Expert system for control of anaerobic digesters

Pullammanappallil

Svoronos

Chynoweth

et al. 1998

Biotechnol. Bioeng.

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Continuous anaerobic digesters are systems that present challenging control problems including the possibility that an unmeasured disturbance can change the sign of the steady‐state process gain. An expert system is developed that recognizes changes in the sign of process gain and implements appropriate control laws. The sole on‐line measured variable is the methane production rate, and the manipulated input is the dilution rate. The expert system changes the dilution rate according to one of four possible strategies: a constrained conventional set‐point control law, a constant yield control law (CYCL) that is nearly optimal for the most common cause of change in the sign of the process gain, batch operation, or constant dilution rate. The algorithm uses a t test for determining when to switch to the CYCL and returns to the conventional set‐point control law with bumpless transfer. The expert system has proved successful in several experimental tests: severe overload; mild, moderate, and severe underload; and addition of phenol in low and high levels. Phenol is an inhibitor that in high concentrations changes the sign of the process gain. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 58:13–22, 1998.

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Hydrogen-dependent control of the continuous anaerobic digestion process

Cited by 60 publications

References 18 publications

Effect of shear on performance and microbial ecology of continuously stirred anaerobic digesters treating animal manure

Effect of shear on performance and microbial ecology of continuously stirred anaerobic digesters treating animal manure

Dissolved hydrogen concentration as an on-line control parameter for the automated operation and optimization of anaerobic digesters

Expert system for control of anaerobic digesters

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