| Title | Recirculation factor is a key parameter in continuous-flow biomass selection for PHA production |
| Abstract | The effectiveness of polyhydroxyalkanoates (PHA) production with mixed microbial cultures (MMC) largely depends on the selection of PHA-storing microorganisms, conventionally performed in sequencing batch reactors (SBR). These, although easily allow the establishment of the required feast and famine (FF) regime, can represent
a factor of cost increase when the process is scaled up. Here, a novel continuous-flow process for MMC selection under FF conditions has been developed by using two sequentially operated reactors. The feast reactor, having a tubular configuration, was continuously fed with a synthetic mixture of acetic and propionic acids (at an organic
loading rate of 2.12 gCOD/L d) and the effluent of this reactor was in part sent to the CSTR famine reactor. The recirculation factor (RC), that is the ratio between the recirculation flow rate and the feeding flow rate to the feast reactor, was the main parameter investigated. Four different runs were performed with the RC varying from 1 to
8 and the increase in its value caused a decrease of the biomass residence time in each reactor. The intracellular PHA content in the feast reactor almost linearly increased up to RC 4 (with a value of 34 ± 2 %, wt/wt) and dropped at the RC 8 condition that, however, showed the maximum PHA content (58 ± 5 %, wt/wt) during the accumulation tests. Indeed, the relative abundance of sequences affiliated with putative PHA-storing bacteria increased up to 90.5 % at RC 8 and were dominated by members of the Alphaproteobacteria class mostly represented by the genus Meganema (74 %) |
| Source | Chemical engineering journal ( Print) 455 |
| Keywords | PolyhydroxyalkanoatesMixed Microbial CulturesContinuous feedingFeast and famine reactorsRecirculation factorFluorescence In Situ Hybridization (FISH) |
| Journal | Chemical engineering journal ( Print) |
| Editor | Elsevier Sequoia, Lausanne, Svizzera |
| Year | 2023 |
| Type | Articolo in rivista |
| DOI | 10.1016/j.cej.2022.140208 |
| Authors | Nguemma L, Marzulli F, Scopetti F, Lorini L, Lauri R, Pietrangeli B, Crognale S, Rossetti S, Majone M, Villano M |
| Text | 481086 2023 10.1016/j.cej.2022.140208 Polyhydroxyalkanoates Mixed Microbial Cultures Continuous feeding Feast and famine reactors Recirculation factor Fluorescence In Situ Hybridization FISH Recirculation factor is a key parameter in continuous flow biomass selection for PHA production Nguemma L, Marzulli F, Scopetti F, Lorini L, Lauri R, Pietrangeli B, Crognale S, Rossetti S, Majone M, Villano M a. Department of Chemistry, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy b. Inail, Department of Technological Innovations and Safety of Plants, Products and Human Settlements, Via del Torraccio di Torrenova 7, 00133 Rome, Italy c. Water Research Institute, National Research Council CNR IRSA , Via Salaria Km 29.300, 00015 Monterotondo, Italy d. Research Center for Applied Sciences to the Safeguard of Environment and Cultural Heritage CIABC , Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy The effectiveness of polyhydroxyalkanoates PHA production with mixed microbial cultures MMC largely depends on the selection of PHA storing microorganisms, conventionally performed in sequencing batch reactors SBR . These, although easily allow the establishment of the required feast and famine FF regime, can represent a factor of cost increase when the process is scaled up. Here, a novel continuous flow process for MMC selection under FF conditions has been developed by using two sequentially operated reactors. The feast reactor, having a tubular configuration, was continuously fed with a synthetic mixture of acetic and propionic acids at an organic loading rate of 2.12 gCOD/L d and the effluent of this reactor was in part sent to the CSTR famine reactor. The recirculation factor RC , that is the ratio between the recirculation flow rate and the feeding flow rate to the feast reactor, was the main parameter investigated. Four different runs were performed with the RC varying from 1 to 8 and the increase in its value caused a decrease of the biomass residence time in each reactor. The intracellular PHA content in the feast reactor almost linearly increased up to RC 4 with a value of 34 ± 2 %, wt/wt and dropped at the RC 8 condition that, however, showed the maximum PHA content 58 ± 5 %, wt/wt during the accumulation tests. Indeed, the relative abundance of sequences affiliated with putative PHA storing bacteria increased up to 90.5 % at RC 8 and were dominated by members of the Alphaproteobacteria class mostly represented by the genus Meganema 74 % 455 Published version Articolo in rivista Elsevier Sequoia 1385 8947 Chemical engineering journal Print Chemical engineering journal Print Chem. eng. j. Print Chemical engineering journal. Print simona.rossetti ROSSETTI SIMONA simona.crognale CROGNALE SIMONA |
