MAIN RESEARCH ACTIVITIES

Butanol production by fermentation of Clostridium acetobutylicum

C1-Gas fermentation
Succinic acid production by fermentation
Microalgal biorefinery
Biosorption of dyes

Carbon capture and storage by biomimetic absorption

Butanol production by fermentation of Clostridium acetobutylicum

Acetone-Butanol-Ethanol (ABE) production by Clostridium acetobutylicum used to be a major bioprocess until the mid-20^thcentury when the petrochemical route to butanol made it cost-ineffective. The recent developments in several scientific/technological fields made the ABE fermentation process competitive with respect to the petrochemical routes for solvents production. Moreover, the biotechnological route to produce butanol is a sustainable solution to produce bifofuels from renewable resources.

Two pathways have been identified in the metabolism of clostridia strains: acidogenesis, characterized by substrate conversion into acids (acetic and butyric acids) by high motile cells (acidogenic cells); solventogenesis, characterized by substrate and acid conversion into solvents (ABE) by clostridial cells unable to grow (solventogenic cells). The shift between the two pathways strongly depends on pH and concentration of metabolites

Biofilm fixed bed reactor operated
under continuous conditions

Main results

ABE production by fermentation of sugar-rich streams (cheese whey, fruit residues, high sugar content beverages, lignocellulosic hudrolyzed, ....)
Assessment of the growth kinetics of Clostridium acetobutylicum DSM 79 and of butanol production using reference sugars and complex sugars
Butanol production process by immobilized Clostridium acetobutylicum continuous Packed Bed Biofilm Reactor (PBBR) systems.
Integration of the continuous PBBR system with solvent recovery.
Maximum butanol productivity 13 g/Lh @ 70 (average) g/L of butanol
Recovery and concentration of butanol (acetone and ethanol) by adsorption
Techno-economic assessment of the production process from agro-foof wastes
Life Cycle Assessment

Biofilm fixed bed reactor system operated under
continuous conditions

4 PBBR

Current research

Simulation of the fermentation process
Investigation of the C. acetobutylicum metabolism
Development of an advanced fermentation system

C1-gas fermentation

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Gas fermentation regards the conversion of C1-based species present in gasseous streams.
C1-gas may be from:

gasification of C-based mass
biogas
natural gas

Main results

Operation of a lab-scale fermenter fed continuously with synthetic syngas stream
Characterization of the growth kinetic of Clostridium carboxidivorans: CO as carbon/energy source at several operating pressure
Preliminary test to produce PHA

C1-gas fermenter

Current research

Simulation of the fermentation process
Development of an advanced fermentation system
Techno-economic assessment of the production process

Succinic acid production by fermentation

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Succinic acid may be produced via the biotechnological route by Actinobacillus succinogenes fermentation.
Feedstock for the fermentation may be sugars from hydrolysis of biomasses

Biofilm fixed bed reactor operated
under continuous conditions

Main results

Assessment of the growth kinetics of Actinobacillus succinogenes and of succinic acid production using reference sugars and complex sugars
Succinic acid production by fermentation of sugar-rich streams (high sugar content beverages, lignocellulosic hudrolyzed, ....)
Succinic acid production by immobilized cells in a continuous Packed Bed Biofilm Reactor (PBBR) system.

Current research

Succinic acid production in an advanced bioreactor.
Simulation of the fermentation process
Techno-economic assessment of the production process

Microalgal biorefinery

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Microalgae are a wonderful source of a wide spectrum of substances: carbohydrates, proteins, lipids, ..... Moreover, the production of this spectrum of substances may be coupled with carbon dioxide sequestration.

Microalgal biomass may be burned/gasified as crude dry matter in combustors/gasifiers or may be processed to produce liquid fuels. In the latter case, bio-oil is extracted from microalgae and it may be adopted either as crude fuel or transesterified to biodiesel.

The most promising microalgal exploitation process includes the valorization of all microalgal components according to the biorefinery approach.

Microalgae strains are from the ACUF collection of the Biological Science Department at the Università degli Studi di Napoli Federico II.

Lab-scale Photobioreactors

Main results

Microalagal strains have been screened to select the most promising for production of several products (just alone and in combined productions)
Photosynthetic efficiency of the process was assessed
Production of biodiesel by lipid estearification
Production of starch
Production of PHB
Techno-economic assessments of the micraoalgal production were carried out

Flat photobioreactors with irradiation led system

Current research

Characterization of microalgae growth, characterization of metabolites (lipid fraction) and their distribution as a function of the operating conditions
Development and characterization of photobioreactors
Development of multistep processes to recovery and valorise fractions of microalgae
Techno-economic assessment of microalgal exploitation processes

Biosorption of dyes

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Recently, biomasses form fungal cultures have been assessed as potential sorbent materials. Tests with Cunninghamella elegans biomass revealed large adsorption capacity against dyes commonly used in textile industries. Collaboration with Plant Biology Department at Università degli Studi di Torino started in 2010 for the assessment of biosorption of dyes on fungal biomasses having different pretreatment, particularly drying or lyophilisation.

Main results

Characterization of kinetics and equilibrium of adsorption on lyophilized biomass of Cunninghamella elegans MUT 2861 of reference dyes.
Characterization of kinetics and equilibrium of adsorption on lyophilized biomass of C. elegans MUT 2861 of wastewaters from textile industries.
Preliminary design of bio-adsorbers.
Preliminary assessment of biosorption in fluidized bed of lyophilized biomass of C. elegans MUT 2861.

Current research

Characterization of kinetics and equilibrium of dyes adsorption on dried biomass of C. elegans MUT 2861.
Preliminary assessment of biosorption in fluidized bed of dried biomass of C. elegans MUT 2861

Carbon capture and storage by biomimetic absorption

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In the framework of Carbon Capture and Storage (CCS) processes, the absorption into aqueous amine solutions is the most advanced process for post-combustion treatments. Drawback related with pollution issues due to amines use may be avoided using environmental friendly additives to enhance CO₂ absorption rate into aqueous phase. Carbonic anhydrase is an ubiquitous enzyme able to atalysed CO₂ hydration up to 106 times faster than the spontaneous reaction. Biomimetic approach to CO₂ capture is based on the adoption of carbonic anhydrase as catalyst into CCS plants.

Main results

Feasibility assessment of biomimetic absorption process to capture CO₂ from flue gas of thermal power plants (collaboration with ENEL Ingegneria & Innovazione)
Long term stability at high temperature of recombinant carbonic anhydrase from the thermophile bacterium Sulfurihydrogenibium sp. (collaboration with Istituto di Biochimica delle Proteine at CNR and Centro Interdipartimentale Biomateriali at Università degli Studi di Napoli Federico II)

Current research

Characterization of kinetics of recombinant anhydrase through CO₂ absorption tests into alkaline solutions
Immobilization of carbonic anhydrase on solid supports for CO₂ capture purposes

Hydrodynamics of gas-liquid units

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The research develops along two lines: experimental investigation and CFD simulation.
The experimental investigation regards the hydrodynamics of bubble columns (BCs) and internal loop airlifts (ILAs). The attention is focused on the effects of features of the liquid - superficial tension and viscosity for Newtonian fluids, and relaxation time for Non-Newtonian fluids – and unit design on the hydrodynamic regimes.
CFD simulation is focused on local flow structures of bubble columns.

Main results

Newtonian fluids: the superficial gas velocity at the transition between hydrodynamic regimes (homogenous regime – vortical-spiral regime – heterogeneous regime) as a function the liquid viscosity was characterized by a maximum.
Newtonian fluids: the maximum stable gas hold-up and gas-liquid mass transfer coefficient in BC as a function the liquid viscosity was characterized by a maximum.
Newtonian fluids: homogeneous regime stability enhances for viscosity < 4.25 mPa•s, in BC, and for viscosity < 7.68 mPa•s, in ILA.
Non-Newtonian fluids: the transition velocity the superficial gas velocity at the transition between hydrodynamic regimes (homogenous regime – vortical-spiral regime – heterogeneous regime) increases with liquid elasticity.

Current research

Combined effects of superficial tension and viscosity of Newtonian fluids on hydrodynamics of BC and ILA.
Systematic investigation of effects of liquid elasticity (Non-Newtonian fluids) on hydrodynamics of BC and ILA.
Simulation of liquid flow structures in a BC

Granulation in gas-fluidized beds

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Characterization of the particle size distribution in gas-fluidized bed.
Modelling of granulation in gas-fluidized bed.

Gas-solids fluidization

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The research develops along two lines: characterization of fluidized bed of assorted solids, and continuous separation of components of solid mixtures.
The characterization of fluidized bed of assorted solids regards: i) experimental investigation in both cylindrical columns and tapered columns; ii) CFD simulation of gas-solids behaviour.
The separation of components of solid mixtures is carried out in a tapered column operated under selected operating conditions.