Fractality in pH time series of continuous anaerobic bioreactors for tequila vinasses treatment

Hernández‐Martínez, Eliseo; Puebla, Héctor; Méndez‐Acosta, Hugo Oscar; Alvarez-Ramı́rez, José

doi:10.1016/j.ces.2014.01.025

Cited by 12 publications

(5 citation statements)

References 32 publications

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“…The presence of different values of the Hurst exponent suggests that the R/S analysis can identify three characteristic phenomena immersed in the fluctuations of the pH series. These zones correspond to those reported in the anaerobic digestion of whey [37] and tequila vinasse [35,36], where each region was attributed to a different anaerobic digestion stage. Based on the above observations, Zone 1 is related to hydrolysis, Zone 2 corresponds with the acidogenesis and acetogenesis stages, and Zone 3 is related to methanogenesis.…”

Section: R/s Analysissupporting

confidence: 86%

“…Méndez-Acosta et al [35] proposed the rescaled range (R/S) analysis of pH time series obtained from an up-flow reactor for the anaerobic digestion of tequila vinasses, where high correlations between the multiscale indices and critical variables of the process (i.e., COD, VFA, and biogas production) were determined. Similar results were found by Hernandez-Martinez et al [36] applying multiscale analysis in pH time series obtained from anaerobic treatment of tequila vinasses in continuous digesters (FBR and CSTR). They concluded that the R/S analysis could qualitatively estimate essential variables for the process evolution.…”

Section: Introductionsupporting

confidence: 88%

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Diagnosis and Monitoring of Volatile Fatty Acids Production from Raw Cheese Whey by Multiscale Time-Series Analysis

et al. 2021

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Anaerobic treatment is a viable alternative for the treatment of agro-industrial waste. Anaerobic digestion reduces organic load and produces volatile fatty acids (VFA), which are precursors of value-added products such as methane-rich biogas, biohydrogen, and biopolymers. Nowadays, there are no low-cost diagnosis and monitoring systems that analyze the dynamic behavior of key variables in real time, representing a significant limitation for its practical implementation. In this work, the feasibility of using the multiscale analysis to diagnose and monitor the key variables in VFA production by anaerobic treatment of raw cheese whey is presented. First, experiments were carried out to evaluate the performance of the proposed methodology under different operating conditions. Then, experimental pH time series were analyzed using rescaled range (R/S) techniques. Time-series analysis shows that the anaerobic VFA production exhibits a multiscale behavior, identifying three characteristic regions (i.e., three values of Hurst exponent). In addition, the dynamic Hurst exponents show satisfactory correlations with the chemical oxygen demand (COD) consumption and VFA production. The multiscale analysis of pH time series is easy to implement and inexpensive. Hence, it could be used as a diagnosis and indirect monitoring system of key variables in the anaerobic treatment of raw cheese whey.

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Section: R/s Analysissupporting

confidence: 86%

Section: Introductionsupporting

confidence: 88%

Diagnosis and Monitoring of Volatile Fatty Acids Production from Raw Cheese Whey by Multiscale Time-Series Analysis

et al. 2021

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“…Biogas was produced as a consequence of the anaerobic digestion of vinasse, biogas composition is mainly methane with 60-65% and carbon dioxide with 35-40% [20]. Methane A c c e p t e d M a n u s c r i p t 13 generation increased with OLR (Figure 3c), so it was directly proportional to the amount of organic matter removed in the UASB reactor; therefore, if organic matter removal efficiency diminishes, methane production also decreases; contrary, if the efficiency increases then it also increases.…”

Section: Methane Yieldmentioning

confidence: 99%

“…Automatic control of reactors is another important aspect developed to assess the effect of acidity and alkalinity in the anaerobic treatment of vinasse [7,14,20]. Mendez-Acosta et al Therefore, the high acidity of vinasses is associated to the VFAs concentration, especially…”

Section: Introductionmentioning

confidence: 99%

Influence of alkalinity and VFAs on the performance of an UASB reactor with recirculation for the treatment of Tequila vinasses

López-López

León-Becerril

Rosales-Contreras

et al. 2015

Environmental Technology

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The main problem linked to the stability of upflow anaerobic sludge blanket (UASB) reactors during the treatment of Tequila vinasse is the high acidity and the null alkalinity present in this effluent. This research evaluates the effect of alkalinity and volatile fatty acids (VFAs) concentration on the performance of an UASB reactor with recirculation of the effluent for removing organic matter and biogas production from Tequila vinasses. Recirculation of the effluent reduces the impact of VFAs and organic matter concentration present in the influent, inducing the stability of the reactor. The UASB reactor was operated during 235 days at organic loading rates from 2.5 to 20.0 kg m(-3) d(-1), attaining a removal efficiency of COD greater than 75% with a methane yield of 335 ml CH4 g(-1) COD at SPT, maintaining a ratio of VFAs/Alk ≤ 0.5. Therefore, an optimal ratio of VFAs/Alk was established for the system operating in stable conditions for the treatment of Tequila vinasses. Under these conditions, the alkalinity was recuperated by the system itself, without the addition of external alkalinity.

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“…[ 22 ] Furthermore, several authors have reported that these methodologies applied to process data can associate the multiscale indexes variation with different phenomena characteristics of a system at a specific time scale. [ 23,24 ] This because the fractal analysis permits the detection of long‐range correlations embedded in a time series by the presence of one or more power‐law behaviours. [ 25 ] Besides, it is easy to implement, with low computational cost, and due to its robustness to noise measurements it is suitable for operation in harsh environments, which makes it an attractive technique for flow‐pattern identification in comparison with other statistic methodologies.…”

Section: Introductionmentioning

confidence: 99%

Two‐phase flow‐patterns identification in oil/gas pipelines based on fractal analysis

et al. 2021

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Flow‐pattern identification in two‐phase pipelines is essential for energy reduction as well as for the selection of suitable operating conditions for effective flow transport. The flow pattern in conventional oil/gas pipelines exhibit different flow patterns due to the underlying complex interactions of transport processes at different time scales. Fractal analysis of complex time series has received significant attention in the past few years due to its ability to extract hidden useful information from underlying phenomena in the time‐series complexity. In this work, the potential of fractal analysis for flow‐pattern identification in oil/gas pipelines is investigated using voltage measurements. Experimental data from a downward‐inclined oil/gas pipeline system at different superficial velocities of gas were analyzed. Our results indicate that fractal parameters can be useful for flow‐pattern identification and to gain insights into the complex phenomena of multiphase systems.

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Fractality in pH time series of continuous anaerobic bioreactors for tequila vinasses treatment

Cited by 12 publications

References 32 publications

Diagnosis and Monitoring of Volatile Fatty Acids Production from Raw Cheese Whey by Multiscale Time-Series Analysis

Diagnosis and Monitoring of Volatile Fatty Acids Production from Raw Cheese Whey by Multiscale Time-Series Analysis

Influence of alkalinity and VFAs on the performance of an UASB reactor with recirculation for the treatment of Tequila vinasses

Two‐phase flow‐patterns identification in oil/gas pipelines based on fractal analysis

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