Kinetics of growth of Aspergillus niger during submerged, agar surface and solid state fermentations

Areca palm (ChrysalidoCarpus lutescenes) a widely used plant having feathery arching brands with 100 leaflets. All these plants produce much of waste in additions to greeny and nuts. This waste of spade is used for the production of various molecules that are used in industry and pharma sector. Fermentation techniques are used to generate economically important enzymes for industrial and pharmaceutical purposes. Cellulase enzyme degrades the cellulose in between β-1, 4 glucosidic link found in lignocellulosic complex which under physical treatment is slower to degrade. The present study of Aspergillus niger for cellulose production was carried in solid state (SS) and submerged (SM) fermentations for production of cellulase enzyme. Cellulase production in SSF after 72 h of fermentation was 8.02 and in SMF activity was 2.98 per ml of cultured broth at H 6 and temperature at 30°C. Both SMF and SSF were supplemented with lactose and lactobionic acid, which acted as cellulase P production inducers. The aim of the present work was to study the effect of Areca palm spade as substrate for Aspergillus niger and its cellulase production under SMF and SSF.

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Food Waste-Assisted Metal Extraction from Printed Circuit Boards: The Aspergillus niger Route

Microorganisms ◽

10.3390/microorganisms9050895 ◽

2021 ◽

Vol 9 (5) ◽

pp. 895

Author(s):

Carlotta Alias ◽

Daniela Bulgari ◽

Fabjola Bilo ◽

Laura Borgese ◽

Alessandra Gianoncelli ◽

...

Keyword(s):

Solid State ◽

Aspergillus Niger ◽

Food Waste ◽

Solid State Fermentation ◽

Printed Circuit Boards ◽

Electronic Waste ◽

Metal Extraction ◽

Circuit Boards ◽

Printed Circuit ◽

Waste Printed Circuit Boards

A low-energy paradigm was adopted for sustainable, affordable, and effective urban waste valorization. Here a new, eco-designed, solid-state fermentation process is presented to obtain some useful bio-products by recycling of different wastes. Urban food waste and scraps from trimmings were used as a substrate for the production of citric acid (CA) by solid state fermentation of Aspergillus niger NRRL 334, with a yield of 20.50 mg of CA per gram of substrate. The acid solution was used to extract metals from waste printed circuit boards (WPCBs), one of the most common electronic waste. The leaching activity of the biological solution is comparable to a commercial CA one. Sn and Fe were the most leached metals (404.09 and 67.99 mg/L, respectively), followed by Ni and Zn (4.55 and 1.92 mg/L) without any pre-treatments as usually performed. Commercial CA extracted Fe more efficiently than the organic one (123.46 vs. 67.99 mg/L); vice versa, biological organic CA recovered Ni better than commercial CA (4.55 vs. 1.54 mg/L). This is the first approach that allows the extraction of metals from WPCBs through CA produced by A. niger directly grown on waste material without any sugar supplement. This “green” process could be an alternative for the recovery of valuable metals such as Fe, Pb, and Ni from electronic waste.

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Solid-State Redox Kinetics of CeO2 in Two-Step Solar CH4 Partial Oxidation and Thermochemical CO2 Conversion

Catalysts ◽

10.3390/catal11060723 ◽

2021 ◽

Vol 11 (6) ◽

pp. 723

Author(s):

Mahesh Muraleedharan Nair ◽

Stéphane Abanades

Keyword(s):

Solid State ◽

Solar Energy ◽

Kinetic Models ◽

Oxygen Carrier ◽

Co2 Conversion ◽

Oxidation Reactions ◽

Redox Kinetics ◽

Concentrated Solar Energy ◽

Ceria Reduction ◽

Kinetics Of

The CeO2/CeO2−δ redox system occupies a unique position as an oxygen carrier in chemical looping processes for producing solar fuels, using concentrated solar energy. The two-step thermochemical ceria-based cycle for the production of synthesis gas from methane and solar energy, followed by CO2 splitting, was considered in this work. This topic concerns one of the emerging and most promising processes for the recycling and valorization of anthropogenic greenhouse gas emissions. The development of redox-active catalysts with enhanced efficiency for solar thermochemical fuel production and CO2 conversion is a highly demanding and challenging topic. The determination of redox reaction kinetics is crucial for process design and optimization. In this study, the solid-state redox kinetics of CeO2 in the two-step process with CH4 as the reducing agent and CO2 as the oxidizing agent was investigated in an original prototype solar thermogravimetric reactor equipped with a parabolic dish solar concentrator. In particular, the ceria reduction and re-oxidation reactions were carried out under isothermal conditions. Several solid-state kinetic models based on reaction order, nucleation, shrinking core, and diffusion were utilized for deducing the reaction mechanisms. It was observed that both ceria reduction with CH4 and re-oxidation with CO2 were best represented by a 2D nucleation and nuclei growth model under the applied conditions. The kinetic models exhibiting the best agreement with the experimental reaction data were used to estimate the kinetic parameters. The values of apparent activation energies (~80 kJ·mol−1 for reduction and ~10 kJ·mol−1 for re-oxidation) and pre-exponential factors (~2–9 s−1 for reduction and ~123–253 s−1 for re-oxidation) were obtained from the Arrhenius plots.

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