title: Influence of hydraulic retention time on the psychrophilic hydrolysis/acidogenesis of proteins.
abstract: The influence of the hydraulic retention time (HRT) on the anaerobic hydrolysis of complex substrates has been studied under psychrophilic conditions. For this purpose, a continuous stirred tank reactor was operated at 15 °C and neutral pH and gelatin was considered as a model protein. Three HRTs have been tested: 12, 21 and 36 h. Gelatin hydrolysis was greatly dependent on HRT, increasing from 40% at 12 h-HRT to a maximum of 65% at 36 h-HRT. Molecular size distribution analyses of the effluent showed that hydrolysation of compounds larger than 10 kDa was poor at 12 h-HRT, whereas the fraction of 1-10 kDa was completely transformed into compounds smaller than 1 kDa. Higher HRT (36 h) improved the degradation of the recalcitrant fraction (>10 kDa), obtaining an effluent with around 95% of soluble molecules (<1 kDa). In that way, the use of membrane bioreactors for the treatment of this type of macromolecules could improve the degradation efficiencies by enabling to increase the residence time of the non-hydrolyzed molecules, with what would be possible to achieve higher organic loading rate operation.
authors.affiliation: School of Biochemical Engineering, Pontificia Universidad Católica de Valparaíso, Brasil 2085, Valparaíso, Chile E-mail: paola.poirrier@pucv.cl.
authors.forename: Paola
authors.initials: P
authors.lastname: Poirrier
authors.affiliation: School of Biochemical Engineering, Pontificia Universidad Católica de Valparaíso, Brasil 2085, Valparaíso, Chile E-mail: paola.poirrier@pucv.cl.
authors.forename: María Cristina
authors.initials: MC
authors.lastname: Schiappacasse
authors.affiliation: Department of Chemical Engineering, School of Engineering, University of Santiago de Compostela, E-15782 Santiago de Compostela, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Carballa
authors.affiliation: Department of Chemical Engineering, School of Engineering, University of Santiago de Compostela, E-15782 Santiago de Compostela, Spain.
authors.forename: Juan M
authors.initials: JM
authors.lastname: Lema
mesh_terms: D019149:Bioreactors; D005232:Fatty Acids, Volatile / Q000378:metabolism*; D005780:Gelatin / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D062065:Wastewater / Q000737:chemistry; D014873:Water Pollutants / Q000378:metabolism*
chemical_list: D005232:Fatty Acids, Volatile; D005780:Gelatin; D062065:Wastewater; D014873:Water Pollutants