Method for measuring the dead volume of an anaerobic reactor

Abstract

The invention relates to a method for measuring the dead volume of an anaerobic reactor used to convert an input comprising organic material into biogas, which consists in: - modelling (1) the residence time of the materials in the reactor as a function of: > the maximum degradation potential of the inputs, > the actual degradation of the inputs in the reactor, > a parameter characteristic of the degradation kinetics of the inputs in the predetermined type of reactor, taking into account its operating conditions, - measuring (2): > the maximum degradation potential of the inputs, > an indicator of degradation of the inputs within the reactor, > a parameter characteristic of the degradation kinetics of the inputs in the predetermined type of reactor and of its operating conditions, - calculating (3) an estimated residence time for the materials in the reactor based on the model and the measurements, - calculating (4) the dead volume based on the estimated residence time and on the predetermined type of reactor. The method makes it possible to monitor changes in the dead volume of a reactor.

Description

Method for measuring the dead volume of an anaerobic reactor

[0001] The invention relates to the field of biogas recovery, by anaerobic digestion, of organic carbon present in municipal or industrial sludge, organic waste or a mixture thereof. More particularly, the invention relates to a method for measuring the dead volume of a reactor and a method for monitoring a reactor.

[0002] A method for treating organic substrates is already known, for example from document FR3044324. These substrates may be sludge from the treatment of domestic or industrial wastewater. The sludge is subjected to a biological treatment of anaerobic digestion, which reduces its volume and produces biogas. The biological degradation process takes place inside a closed, airtight reactor, also called an anaerobic reactor or anaerobic digester, through which the sludge circulates for a given residence time, undergoing a series of biological transformations. To function properly, an anaerobic reactor is temperature-controlled and its contents are stirred.

[0003] Despite all the precautions taken for proper sludge transformation, solids accumulate in the reactor. This is called silting. These sands occupy a so-called dead volume in the tank, which is no longer available for the sludge transformation reaction. In the long run, this dead volume ends up having a significant impact on the reactor's productivity. The drop in biogas production due to silting alone can be very significant in the long term, sometimes up to 20%.

[0004] It is known to measure the amount of dead volume, to decide whether it is useful to stop the reactor to evacuate the accumulated sand. This operation is obviously costly, not only in itself, but also in terms of loss of production. It is therefore advisable to decide on it only after carefully verifying its usefulness.

[0005] Among the known verification techniques, the most reliable to date and also the most widespread is lithium tracing. This conventional method, which is used in various fields in which a fluid flow must be studied, consists of injecting precise doses of lithium at different times, then measuring the lithium concentration at the reactor outlet at different times over a relatively long measurement period. Since lithium is inert with respect to the decomposition of sludge, it is not affected by the chemical reactions that occur in the reactor. Its concentration at the reactor outlet therefore depends solely on the speed at which it passes through the said reactor or, strictly equivalently since its progression in the reactor is not known but only its entry and exit times, on its residence time in the reactor. A residence time distribution curve is thus established.The model described by Levenspiel (cf. Levenspiel, "ChemicalReactionEngineering", John Wiley and Sons, New York, 1962, pp. 242-308) is applied to quantitatively partition the reactor contents into fully mixed active volume, proportion of inactive mixture, and proportion of inputs that bypass these two components to bypass the reactor outlet. From the residence time distribution curve, the dead volume can be deduced and, if necessary, its magnitude confirmed to justify a reactor shutdown.

[0006] One difficulty with lithium tracking is its very high cost, making many mining sites reluctant to implement it.

[0007] Furthermore, the timing of the tracing method is often unfavorable: because lithium tracing is expensive, it is only applied when a problem is proven on the site. In general, the presence of an excessively high dead volume is strongly suspected due to a significant and persistent drop in production. Tracing then only serves to confirm the silting hypothesis, but a significant drop in production has already been experienced. It is therefore too late to limit losses. The tracing method did not have the benefit of detecting excessive silting. It only served to confirm it. Conversely, sites that want to avoid measuring too late follow a predefined schedule. They then run the risk of carrying out lithium tracing too early, and therefore also in a useless manner. Lithium tracing cannot therefore be considered a method for monitoring silting.

[0008] Another difficulty with lithium tracing is the potential pollution resulting from its implementation. Although the quantities injected are small and set by current standards, the lithium used is difficult to recover from the reactor outlet. It will eventually be released, fortunately in small quantities, into the environment, where its high stability will cause it to persist for a long time.

[0009] There is therefore a need for a method for monitoring the dead volume of a reactor that is simple, fast, inexpensive and non-polluting. The lithium tracing solution is certainly technically available as a measurement method, but the practical conditions of its implementation make it unavailable as a preventive monitoring method.

[0010] The level of silting is also readable posteriorly on the production curves of a reactor observed over several years. However, production monitoring is not a reliable method for tracking silting either. With monthly production reports, the trend is easily masked by the overriding influence of other variation factors, starting with the composition of inputs, which is not absolutely stable. In addition, the accuracy of the measurements is often not sufficient to detect the impact of silting in the short term. Finally, the phenomenon is not linear. Silting progresses more quickly at times, depending on various factors.

[0011] The invention therefore aims to provide a real practical solution to the need for preventive monitoring of silting in an anaerobic reactor.

[0012] The subject of the invention is a method for measuring the dead volume of an anaerobic reactor of a predetermined type, used to transform inputs comprising organic matter into biogas and digestate, characterized in that it comprises the following steps:

[0013] - model the residence time of the materials in the reactor as a function of at least the following parameters:

[0014] > maximum potential for degradation of inputs,

[0015] > degradation of inputs effective in the reactor,

[0016] > characteristic parameter of the kinetics of degradation of inputs in the predetermined type of reactor, taking into account its operating conditions,

[0017] - measure the following values:

[0018] > maximum potential for degradation of inputs,

[0019] > indicator of degradation of inputs within the reactor,

[0020] > characteristic parameter of the kinetics of degradation of inputs in the predetermined type of reactor and its operating conditions,

[0021] - calculate the estimated residence time of the materials in the reactor from the model and measurements, and the nominal residence time of the materials in the reactor taking into account the predetermined reactor type,

[0022] - calculate the dead volume from the nominal residence time, the estimated residence time and the predetermined reactor type;

[0023] process in which, as a characteristic parameter of the kinetics of degradation of the inputs in the predetermined type of reactor, taking into account its operating conditions, the hydrolysis rate is used.

[0024] For the purposes of the invention, the hydrolysis rate can be obtained by any suitable measurement method, such as a biological method or infrared measurement, or any model making it possible to describe the hydrolysis kinetics during methanization.

[0025] As an example, we can use the formula available in the calculation according to the ISO 19388 standard, namely: k hyd = 0.045∙1.072 T-10 .

[0026] The invention is not limited to the example of first-order kinetics as described in ISO 19388, but any model suitable for describing hydrolysis kinetics may be applied, in particular with reference to the publication V.A.Vavilin, B. Fernandez, J.Palatsi, X.Flotats, Hydrolysis kinetics in anaerobic degradation of particulate organic material: An overview, Waste Management, Volume 28, Issue 6, 2008, Pages 939-951.

[0027] In particular, the Contois model described in the previous publication, equation (13), makes it possible to obtain an even more precise hydrolysis rate, being in particular a function of the concentration of microbial biomass, but imposes a more complex numerical resolution.

[0028] The order of the steps of the method according to the invention is not limiting, since an intermediate result necessary for a given step has been obtained by prior execution of a step for obtaining this intermediate result.

[0029] This process can be implemented regularly and preventively. It then allows for the identification of deviations before they become critical, all without cost or pollution being a barrier to its application.

[0030] In this application, the composition of the inputs is considered to be reasonably stable because the inputs do not vary overnight and the measurements of the maximum degradation potential of the inputs and the degradation kinetics of the inputs can correspond to the indicator of degradation of the inputs which is preferably measured on site. Stability is understood to be over a few weeks. In practice, this condition is almost always satisfied.

[0031] The maximum input degradation potential is the maximum capacity of the reactor to degrade inputs in the absence of oxygen. This parameter, or measurement, corresponds to the maximum theoretical quantity of organic matter that the reactor can process by the biological processes activated within it.

[0032] An advantage of the above process is first of all that it constitutes a rapid, inexpensive and non-polluting tool allowing preventive monitoring of the reactor.

[0033] In addition, the method provides additional information, such as the maximum degradation potential of inputs, which is useful for monitoring and optimizing biological treatments.

[0034] Depending on other optional features of the process, taken alone or in combination:

[0035] – The reactor type can be defined by:

[0036] - its flow type (piston flow or infinitely mixed),

[0037] - its power supply (continuous, semi-continuous),

[0038] - its withdrawal regime (continuous, semi-continuous),

[0039] - the number of stages (if reactors in series),

[0040] - the existence of one or more recirculation loops.

[0041] The reactor model represents its fluidics. Depending on its complexity, the resolution of the model can be explicit, i.e. obtained by inversion of a direct formula, or iterative, by calculation applied to successive time steps.

[0042] – As the maximum input degradation potential, which corresponds to the maximum capacity of the reactor to degrade the inputs in the absence of oxygen, any of the following quantities is used: maximum biochemical methane potential; maximum dry matter reduction potential; maximum volatile matter reduction potential; maximum chemical oxygen demand reduction potential.

[0043] Advantageously, to measure it, we use a biological method or an infrared measurement.

[0044] – As an indicator of effective input degradation in the reactor, the methane yield is used, i.e. the quantity of methane produced per unit mass of input, or the reduction efficiency of volatile matter, dry matter or chemical oxygen demand.

[0045] Advantageously, it is measured on site.

[0046] – In the case of a plug flow reactor, the reactor recycling rate is used as an additional parameter of the model, or as an additional measure.

[0047] Repeated implementation of the process is made possible by the absence of production disruption and the low cost of each repetition. Thanks to these advantages of the measuring process, it is possible to carry out real preventive monitoring of sand encroachment.

[0048] Thus, the invention also relates to a method for monitoring the evolution of the dead volume of an anaerobic reactor used to transform inputs comprising organic matter into biogas and digestate, consisting of repeating, at regular time intervals, the following steps: carrying out the measurement method described above; comparing the results obtained with a predetermined reference; reporting a deviation, if applicable.

[0049] In addition to providing a method for monitoring reactor silting, repeated implementation of the process makes it possible to compensate for production variations linked to changes in input quality. Indeed, the proposed method requires measuring again, at each application, the maximum degradation potential of the inputs and the characteristic parameter of the input degradation kinetics. It is then possible to decouple the performance share linked to a variation in inputs from that linked to the dead volume. Thus, even if the reactor performance increases due to a supply of inputs producing more methane than in the past, an increase in the dead volume remains detectable. The proposed method then becomes more advantageous than monitoring only the site performance. The monitoring method is therefore more independent of the stability of the inputs than any other known method.It is recalled that the stability of the inputs is understood, according to the invention, as satisfied when there is consistency between the maximum degradation potential of the inputs, the degradation kinetics of the inputs and the degradation indicator of the inputs. In the context of the monitoring method, this consistency results from the fact that the measurements are repeated at each application of the measurement method described above.

[0050] Furthermore, another advantage of this repeated implementation of the measurement process is that it allows to compensate for the lower precision, if we compare it to that of the lithium tracing process.

[0051] The present invention also relates to computer processing means for monitoring a methanization unit comprising an anaerobic reactor, said computer processing means comprising at least one memory and at least one processor, the memory containing instructions which, when read and executed by the processor, allow the processor to implement the method for measuring the dead volume of the reactor.

[0052] In a particular embodiment, the memory also contains instructions which, when read and executed by the processor, allow the processor to implement the method for monitoring the evolution of the dead volume of the reactor.

[0053] The present invention also relates to a methanization unit from organic materials, comprising an anaerobic reactor equipped with a reactor and computer processing means as described above.

[0054] The invention can also be expressed using a slightly different approach that achieves the same result, by modeling production and not residence time.

[0055] The invention thus also relates to a method for measuring the dead volume of an anaerobic reactor of a predetermined type, used to transform inputs comprising organic matter into biogas and digestate, comprising the following steps:

[0056] - model the reactor's production in the form of an indicator of degradation of inputs within the reactor as a function of at least the following parameters:

[0057] > residence time of materials in the reactor,

[0058] > maximum potential for degradation of inputs,

[0059] > characteristic parameter of the kinetics of degradation of inputs in the predetermined type of reactor, taking into account its operating conditions

[0060] - measure the following values:

[0061] > maximum potential for degradation of inputs,

[0062] > characteristic parameter of the kinetics of degradation of inputs in the predetermined type of reactor and its operating conditions,

[0063] > indicator of actual degradation of inputs in the reactor.

[0064] - solve the production model by injecting the measured values ​​into it to deduce the residence time of the materials in the reactor,

[0065] - deduce from the residence time the useful volume of the reactor according to the predetermined type of reactor,

[0066] - obtain the dead volume by subtracting the useful volume from the total volume of the reactor.

[0067] This measurement method according to an alternative approach can also be combined with the secondary characteristics of the measurement method described above, as well as with the other objects of the invention, namely the monitoring method, the computer processing means and the methanization unit. Brief description of the figures

[0068] The invention will be better understood on reading the following description, given solely by way of example and with reference to the appended drawings in which:

[0069] is a block diagram illustrating the steps of a measurement method according to an example of implementation,

[0070] is another block diagram illustrating the steps of a reactor monitoring process,

[0071] is a schematic view of a methanization unit according to a particular embodiment. Detailed description

[0072] The described example of the dead volume measurement method is illustrated by the, each block of which corresponds to a step of said method.

[0073] In a first step 1, we start by establishing the model to be used. The reactor performance is taken as an input variable to predict the residence time.

[0074] Since the microorganisms involved in the different phases of digestion have very different generation times (Table 1), the selected solids retention time must be greater than the generation time of the slowest-growing microbial group. In this case, these are the methanogens. Therefore, solids retention times greater than 5 days, typically 15-20 days for mesophilic digestion and 8-12 days for thermophilic digestion, are selected.ParameterHydrolysis / AcidogenesisMethanogenesisTemperature25 – 35°CMesophilic: 30 – 42°CThermophilic: 50 – 58°CpH5.2 – 6.36.7 – 7.5Redox Potential+400 to -300 mV<-250mVRatio C:N:P:S required500:15:5:3600:15:5:3Generation Time24 – 36 h5 – 16 daysElement in trace form-Ni, Co, Mo, Se

[0075] The reactor size chosen aims to maximize energy recovery and sludge stabilization to approximately 80-90% of the biochemical methane potential (BMP), while minimizing investment and washing of methanogenic biomass. Indeed, in anaerobic digestion of municipal sewage sludge, once methanogens have developed, hydrolysis is considered the rate-limiting step of the process and follows a first-order rate.

[0076] This phenomenon can be modeled using the relationship between methane production and solids retention time (SRT) in a continuous stirred tank reactor:

[0077]

[0078] Or :

[0079] Y CH4 , is the methane yield (NLCH4 / kgVS)

[0080] B0, is the maximum biochemical potential of methane -BMP- (NLCH4 / kgVS),

[0081] k hyd , is the apparent hydrolysis rate,

[0082] SRT is the retention time of solids in the reactor.

[0083] From the previous formula, the model of the solids residence time (SRT model ) can be established according to the following formula:

[0084]

[0085] In a second step 2, the variables necessary for the application of the model are measured, namely: the maximum potential for degradation of the inputs (B0), the indicator of the effective degradation of the inputs in the reactor (Y CH4 ) and kinetics (k hyd , which depends at least on the temperature).

[0086] Biochemical methane potential (BMP) tests are expensive and time-consuming (>30 days). Therefore, to determine B0 and advantageously k hyd, we aim to use any method aimed at predicting this parameter. For example, the person skilled in the art knows and will be able to choose from the following methods, which belong to the state of the art: Correlation tests with aerobic: R. Cossu, R. Raga, Test methods for assessing the biological stability of biodegradable waste, Waste Manag. 28 (2008) 381e388, https: / doi.org / 10.1016 / j.wasman.2007.01.014

[0087] S. Pons a, T. Gea, L. Alerm, J. Cerezo, A. Sanchez, Comparison of aerobic and anaerobic stability indices through a MSW biological treatment process, Waste Manag. 28 (2008) 2735e2742, https: / doi.org / 10.1016 / j.wasman.2007.12.002Regression models using physicochemical characteristics as input data: V. Dandikas, H. Heuwinkel, F. Lichti, JE Drewes, K. Koch, Predicting methane yield by linear regression models: a validation study for grassland biomass, Bioresour. Technol. 265 (2018) 372e379, https: / doi.org / 10.1016 / j.biortech.2018.06.030

[0088] L. Appels, J. Lauwers, G. Gins, J. Degreve, J. Van Impe, R. Dewil, Parameter identification and modeling of the biochemical methane potential of waste activated sludge, Environ. Sci. Technol. 45 (9) (2011) 4173e4178, https: / doi.org / 10.1021 / es1037113

[0089] A. Mottet, E. Francois, E. Latrille, J.P. Steyer, S. Deleris, F. Vedrenne, H. Carrere, Estimating anaerobic biodegradability indicators for waste activated sludge, Chem. Eng. J. 160 (2010) 488e496, https: / doi.org / 10.1016 / j.cej.2010.03.059

[0090] F. Xu, Z. Wang, Y. Li, Predicting the methane yield of lignocellulosic biomass in mesophilic solid-state anaerobic digestion based on feedstock characteristics and process parameters, Bioresour. Technol. 173 (2014) 168e176, https: / doi.org / 10.1016 / j.biortech.2014.09.090Techniques de spectroscopie, y compris la spectroscopie proche infrarouge :M. Lesteur, E. Latrille, V.B. Maurel, J.M. Roger, C. Gonzalez, G. Junqua, J.P. Steyer, First step towards a fast analytical method for the determination of Biochemical Methane Potential of solid wastes by near infrared spectroscopy, Bioresour. Technol. 102 (2011) 2280e2288, https: / doi.org / 10.1016 / j.biortech.2010.10.044

[0091] J.M. Triolo, A.J. Ward, L. Pedersen, M.M. Løkke, H. Qu, S.G. Sommer, Near Infrared Reflectance Spectroscopy (NIRS) for rapid determination of biochemical methane potential of plant biomass, Appl. Energy 116 (2014) 52e57, https: / doi.org / 10.1016 / j.apenergy.2013.11.006

[0092] All of these methods provide estimates of anaerobic biodegradability within reasonable time frames and margins of error.

[0093] The indicator of the effective degradation of inputs in the reactor, in the example describes the quantity of methane produced per unit mass of input Y CH4 , is determined from the site's production data.

[0094] The characteristic parameter of the degradation kinetics of inputs, in the example describes the hydrolysis rate k hyd , is determined by the above-mentioned rapid methods or using the following formula, available in the calculation according to ISO 19388:

[0095]

[0096] The measure of k hyd is therefore indirect, the direct measurement being that of temperature T.

[0097] Optionally, other parameters, not detailed here but known to the specialist in the field, can be integrated to represent the fluidics of the reactor.

[0098] Note that B0et k hyd (or their equivalents) are measured from samples of the inputs, while Y CH4 (or equivalent) comes from reactor monitoring measurements.

[0099] In a subsequent step 3, two residence time values ​​are calculated.

[0100] On the one hand, the residence time model is used by applying the formula [Math 2] with the measured variables. This gives a value of the estimated residence time, SRT model .

[0101] On the other hand, we calculate the nominal residence time, or nominal solids retention time (SRT nominal ) taking into account the predetermined reactor type.

[0102] Solids retention time (SRT) is defined as the average time solids spend in a reactor. Wet anaerobic digestion (<10% solids in feedstock) typically uses continuous stirred tank reactors, in which the solids retention time (SRT) and hydraulic retention time (HRT) are the same and calculated as the reactor volume (m 3 ) divided by the daily flow rate (m 3 / day). In this example, the predetermined type of reactor is taken into account.

[0103] Calculation of the nominal retention time of solids SRT nominal therefore results from the application of the following formula:

[0104]

[0105] Or:

[0106] V is the total volume of the reactor (m 3 ),

[0107] Q is the flow rate of the raw material introduced into the reactor (m 3 / day).

[0108] In a final step 4, the dead volume is calculated taking into account the nominal residence time SRT nominal and the estimated stay time SRT model , by the following formula:

[0109]

[0110] We see that the order of the steps is not restrictive, since a result necessary for a given step has been obtained by prior execution of a step to obtain this result.

[0111] Equation [Math 1] represents the simplest case, for which a direct formula can be obtained. This equation is theoretically valid only for a continuously stirred tank reactor in steady state. But the method can be extended to other configurations.

[0112] In another example, the reactor is of the steady-state plug flow type. The following formula must then be substituted for formula [Math 1]:

[0113]

[0114] Or :

[0115] Y CH4 , is the methane yield (NLCH4 / kgVS)

[0116] B0, is the maximum biochemical methane potential -BMP- (NLCH4 / kgVS),

[0117] k hyd , is the apparent hydrolysis rate,

[0118] SRT is the retention time of solids in the reactor,

[0119] R is the recycle rate of the plug flow reactor.

[0120] Using equation [Math 6], the estimated solids retention time SRT model can be estimated using the following equation:

[0121]

[0122] Alternatively, for non-ideal hydraulic fluidics or if the reactors have not reached a steady state, one can resort to two-parameter first-order dynamic models (k h yd, B0). In this case, the model aims to fit a time series of biomethane production instead of a single value of Y CH4 .

[0123] On the figure, a block diagram of the implementation of a method for monitoring the evolution of the dead volume of the reactor is shown.

[0124] A first step 5 represents a complete execution of the measurement process. At each execution, all measurements are renewed.

[0125] A second step 6 consists of comparing the results obtained during step 5 with a predetermined reference.

[0126] A third step 7 is to report a deviation, if applicable.

[0127] At the end of step 7, the process loops back to step 5, until it is forced to stop (not shown) by an operator.

[0128] On the, we see a methanization unit 8 which comprises a reactor 9, computer processing means 10 including a memory 11 and a processor 12. The memory contains instructions 13. When they are read and executed by the processor 12, these instructions 13 allow the processor 12 to implement the method for measuring the dead volume of the, as well as the method for monitoring the evolution of the dead volume of the.

[0129] The invention is not limited to the examples described, which are only intended to facilitate understanding. List of references

[0130] 1: …residence time modeling step2: …measurement step3: …nominal residence time calculation step4: …dead volume calculation step5: …measurement process execution step6: …results comparison step7: …deviation reporting step8: …methanization unit9: …reactor10: …computer processing resources11: …memory12: …processor13: …instructions

Claims

Method for measuring the dead volume of an anaerobic reactor of a predetermined type, used to transform inputs comprising organic matter into biogas and digestate, characterized in that it comprises the following steps: - modeling (1) the residence time of the materials in the reactor as a function of at least the following parameters: > maximum potential for degradation of the inputs, > degradation of the inputs effective in the reactor, > characteristic parameter of the kinetics of degradation of the inputs in the predetermined type of reactor, taking into account its operating conditions, - measuring (2) the following values: > maximum potential for degradation of the inputs, > indicator of degradation of the inputs within the reactor, > characteristic parameter of the kinetics of degradation of the inputs in the predetermined type of reactor and its operating conditions,- calculate (3) the estimated residence time of the materials in the reactor from the model and the measurements, and the nominal residence time of the materials in the reactor taking into account the predetermined reactor type,- calculate (4) the dead volume from the nominal residence time, the estimated residence time and the predetermined reactor type;process in which, as a characteristic parameter of the degradation kinetics of the inputs in the predetermined reactor type, taking into account its operating conditions, the hydrolysis rate (k, hyd ). Method according to claim 1, in which, as maximum input degradation potential, any one of the following quantities is used: maximum biochemical methane potential (BMP); maximum dry matter reduction potential; maximum volatile matter reduction potential; maximum chemical oxygen demand reduction potential. Method according to the preceding claim, in which the maximum degradation potential of the inputs is measured by biological method or by infrared measurement. A method according to any one of the preceding claims, wherein, as an indicator of effective input degradation in the reactor, the methane yield (Y CH4 ) , i.e. the amount of methane produced per unit mass of input, or the reduction efficiency of volatile matter, dry matter or chemical oxygen demand . Method according to any one of the preceding claims, to measure the characteristic parameter of the degradation kinetics of the inputs in the predetermined type of reactor, a biological method or an infrared measurement is used, or the formula available in the calculation according to the ISO 19388 standard, namely: k hyd = 0.045∙1.072 T-10 . Method according to any one of the preceding claims, adapted to a plug flow reactor, in which the reactor recycle rate (R) is used as an additional parameter of the model, respectively as an additional measure. Method for monitoring the evolution of the dead volume of an anaerobic reactor used to transform inputs comprising organic matter into biogas and digestate, characterized in that it consists of repeating, at regular time intervals, the following steps: carrying out (5) the measurement method according to any one of the preceding claims; comparing (6) the results obtained with a predetermined reference; signaling (7) a deviation, if applicable. Computer processing means for monitoring a methanization unit (8) comprising an anaerobic reactor (9), said computer processing means (10) comprising at least one memory (11) and at least one processor (12), characterized in that the memory (11) contains at least instructions (13) which, when read and executed by the processor (12), allow the processor (12) to implement the method for measuring the dead volume of the reactor according to any one of claims 1 to 6 and possibly instructions (13) which, when read and executed by the processor (12), allow the processor (12) to implement the method for monitoring the evolution of the dead volume of the reactor according to claim 7. Methanization unit (8) from organic materials, comprising an anaerobic reactor (9) and computer processing means according to claim 8.

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