title: A hybrid cascade control scheme for the VFA and COD regulation in two-stage anaerobic digestion processes.
abstract: A hybrid (continuous-discrete) cascade control is proposed to regulate both, volatile fatty acids (VFA) and chemical oxygen demand (COD) concentrations in two-stage (acidogenic-methanogenic) anaerobic digestion (TSAD) processes. The outer loop is a discrete controller that regulates the COD concentration of the methanogenic bioreactor by using a daily off-line measurement and that modifies the set-point tracked by inner loop, which manipulates the dilution rate to regulate the VFA concentration of the acidogenic bioreactor, estimated by continuous on-line conductivity measurements, avoiding acidification. The experimental validation was conducted in a TSAD process for the treatment of tequila vinasses during 110days. Results showed that the proposed cascade control scheme was able to achieve the VFA and COD regulation by using conventional measurements under different set-point values in spite of adverse common scenarios in full-scale anaerobic digestion processes. Microbial composition analysis showed that the controller also favors the abundance and diversity toward methane production.
authors.affiliation: Departamento de Ingeniería Química, CUCEI-Universidad de Guadalajara, Blvd. M. García Barragán 1451, 44430 Guadalajara, Jal., Mexico.
authors.forename: H O
authors.initials: HO
authors.lastname: Méndez-Acosta
authors.affiliation: Departamento de Ingeniería Química, CUCEI-Universidad de Guadalajara, Blvd. M. García Barragán 1451, 44430 Guadalajara, Jal., Mexico.
authors.forename: A
authors.initials: A
authors.lastname: Campos-Rodríguez
authors.affiliation: Departamento de Ingeniería Química, CUCEI-Universidad de Guadalajara, Blvd. M. García Barragán 1451, 44430 Guadalajara, Jal., Mexico.
authors.forename: V
authors.initials: V
authors.lastname: González-Álvarez
authors.affiliation: Departamento de Ingeniería Química, CUCEI-Universidad de Guadalajara, Blvd. M. García Barragán 1451, 44430 Guadalajara, Jal., Mexico. Electronic address: paulo.garcia@cucei.udg.mx.
authors.forename: J P
authors.initials: JP
authors.lastname: García-Sandoval
authors.affiliation: Departamento de Ingeniería Química, CUCEI-Universidad de Guadalajara, Blvd. M. García Barragán 1451, 44430 Guadalajara, Jal., Mexico.
authors.forename: R
authors.initials: R
authors.lastname: Snell-Castro
authors.affiliation: INRA, UR050, Laboratoire de Biotechnologie de l'Environnement, Avenue des Etangs, F-11100 Narbonne, France.
authors.forename: E
authors.initials: E
authors.lastname: Latrille
mesh_terms: D000693:Anaerobiosis; D057919:Biological Oxygen Demand Analysis; D019149:Bioreactors / Q000382:microbiology; D005232:Fatty Acids, Volatile / Q000032:analysis / Q000737:chemistry*; D008697:Methane / Q000032:analysis
chemical_list: D005232:Fatty Acids, Volatile; D008697:Methane
keywords: Cascade control; Continuous and discrete measurements; Tequila vinasses; Two-stage anaerobic digestion