State indicators for monitoring the anaerobic digestion process

Boe, Kanokwan; Batstone, Damien J.; Steyer, Jean-Phillippe; Angelidaki, Irini

doi:10.1016/j.watres.2010.07.043

Cited by 234 publications

(134 citation statements)

References 27 publications

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“…Among the total VFAs, acetate was still the dominant component, although propionate was also accumulated, which is consistent with previous reports that propionate is easy to accumulate when the biogas reactor is disturbed [22,23].…”

Section: Reactor Performancesupporting

confidence: 91%

New Steady-State Microbial Community Compositions and Process Performances in Biogas Reactors Induced by Temperature Disturbances

Luo¹,

Francisci²,

Kougias³

et al. 2015

Biological Treatment of Solid Waste

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Background: The microbial community in a biogas reactor greatly influences the process performance. However, only the effects of deterministic factors (such as temperature and hydraulic retention time (HRT)) on the microbial community and performance have been investigated in biogas reactors. Little is known about the manner in which stochastic factors (for example, stochastic birth, death, colonization, and extinction) and disturbance affect the stable-state microbial community and reactor performances. Results: In the present study, three replicate biogas reactors treating cattle manure were run to examine the role of stochastic factors and disturbance in shaping microbial communities. In the triplicate biogas reactors with the same inoculum and operational conditions, similar process performances and microbial community profiles were observed under steady-state conditions. This indicated that stochastic factors had a minor role in shaping the profile of the microbial community composition and activity in biogas reactors. On the contrary, temperature disturbance was found to play an important role in the microbial community composition as well as process performance for biogas reactors. Although three different temperature disturbances were applied to each biogas reactor, the increased methane yields (around 10% higher) and decreased volatile fatty acids (VFAs) concentrations at steady state were found in all three reactors after the temperature disturbances. After the temperature disturbance, the biogas reactors were brought back to the original operational conditions; however, new steady-state microbial community profiles were observed in all the biogas reactors.Conclusions: The present study demonstrated that temperature disturbance, but not stochastic factors, played an important role in shaping the profile of the microbial community composition and activity in biogas reactors. New steady-state microbial community profiles and reactor performances were observed in all the biogas reactors after the temperature disturbance.

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Section: Reactor Performancesupporting

confidence: 91%

New Steady-State Microbial Community Compositions and Process Performances in Biogas Reactors Induced by Temperature Disturbances

Luo¹,

Francisci²,

Kougias³

et al. 2015

Biological Treatment of Solid Waste

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“…When the pH of the digester dropped below 6.7, the feeding was stopped for a day and these periods are indicated by vertical arrows equation [31] that gives higher methane content for the lipidic substrates than for the carbohydrates and proteins. In the literature, drop in the methane concentration in the biogas was reported in case of organic overload of anaerobic digesters [8,31,32]. In our experiments, the increased OLR had limited influence on the methane concentration.…”

Section: Discussionmentioning

confidence: 40%

“…However, the training data set to calculate the distance from the steady-state process must be carefully managed [11,30]. True performance of a gas sensor array for biogas process monitoring could only be estimated by extending the present work to conditions prevailing in real agricultural situations while comparing results with VFA monitoring in the liquid phase, the latter being a well accepted method for identifying organic overload state the anaerobic process [8,[37][38][39][40]. For future experiments, an automated e-nose system that acquires automatically the biogas sample and gives real-time monitoring on hourly basis of the bioreactor status should be evaluated, allowing process control and possibly some interventions on the bioreactors.…”

Section: Future Workmentioning

confidence: 99%

“…Individual volatile fatty acids (VFA) are considered, in the domain of anaerobic digestion, as the most relevant state variables for process monitoring, but their online analysis in anaerobic reactors is not obvious and only few systems such as NIR [4][5][6][7] or online gas chromatography [8][9][10] have been tested for their estimation in the anaerobic sludge. For agricultural AD plants, robustness and simplicity must necessarily be part of the process analyzer design [11].…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of an electronic nose for the early detection of organic overload of anaerobic digesters

Adam

Lemaigre²,

Romain

et al. 2012

Bioprocess Biosyst Eng

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This study aimed at analysing the utilization of an electronic nose (e-nose) to serve as a specific monitoring tool for anaerobic digestion process, especially for detecting organic overload. An array of non specific metal oxide semiconductor gas sensors were used to detect process faults due to organic overload events in twelve 1.8-L anaerobic semi-continuous reactors. Three different load strategies were followed: (1) a cautious organic load (1.3 gVS L -1 day -1 ); (2) an increasing load strategy (1.3-5.3 gVS L -1 day -1 ) and (3) a cautious organic load with load pulses of up to 12 gVS L -1 day -1 . A first monitoring campaign was conducted with three different substrates: sucrose, maize oil and a mix of sucrose/oil during 60 days. The second campaign was run with dry sugar beet pulp for 45 days. Hotelling's T 2 value and upper control limit to a reference set of digesters fed with a cautious OLR (1.3 gVS L -1 day -1 ) was used as indirect state variable of the reactors. Overload situations were identified by the e-nose apparatus with Hotelling's T 2 values at least four times higher in magnitude than the upper control limit of 23.7. These results confirmed that the e-nose technology appeared promising for online detection of process imbalances in the domain of anaerobic digestion.

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“…For this reason, a continuous monitoring of the plant and of digestion itself is necessary to avoid the instability of the system. Nowadays, a wide number of indicators are used to monitor the correct anaerobic digestion, as VFAs evaluation (Boe et al 2007(Boe et al , 2010, pH, redox potential, biogas production rate, biogas composition, FOS/ TAC ratio, COD and/or VS reduction are also used. FOS is an acronym that stands for Fl€ uchtige Organische S€ auren, i.e.…”

Section: Introductionmentioning

confidence: 99%

Evaluating an e-nose ability to detect biogas plant efficiency: a case study

Costa

Tangorra

Zaninelli

et al. 2016

Italian Journal of Animal Science

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The demand for online monitoring and control of biogas process is increasing, since better monitoring and control system can improve process plants stability and economy. A number of parameters in both the liquid and the gas phase have been suggested as process indicators (pH, alkalinity, VFA and H 2, redox potential, biogas production rate, biogas composition, FOS/TAC ratio, COD and/or VS reduction). The present study proposes the use of complex sensors as a possible solution to engineer a consistent control system. Tests were performed to analyze the biogas coming from a biogas plant in which conditions of pre-overloading and overloading were artificially inducted. The different inducted functioning conditions were recognised using a FOS/TAC tester, or the ratio volatile organic acids/alkaline buffer capacity. The FOS/TAC ratio has long been recognized extending as far as the imminent inversion of the digester biology to be detected at an early stage. Data coming from the e-nose were sorted and classified according to FOS/TAC ratio as a reference method. Not all the sensors of the e-nose were reactive to manure digestates, but four of them, sensitive to aromatic compounds, ammonia alkanes and methane, resulted crucial in the samples identification. Results confirmed that the e-nose can discriminate different digestion conditions, demonstrating the possibility to reduce the number of sensors in this innovative tool for biogas control systems. However, this instrument cannot be considered a complete alternative to traditional analysis systems, as, for example, the FOS/TAC titration, but a supporting tool for a quick analysis of the system. ARTICLE HISTORY

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State indicators for monitoring the anaerobic digestion process

Cited by 234 publications

References 27 publications

New Steady-State Microbial Community Compositions and Process Performances in Biogas Reactors Induced by Temperature Disturbances

New Steady-State Microbial Community Compositions and Process Performances in Biogas Reactors Induced by Temperature Disturbances

Evaluation of an electronic nose for the early detection of organic overload of anaerobic digesters

Evaluating an e-nose ability to detect biogas plant efficiency: a case study

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