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de Melo Quintela B, Hervas-Raluy S, Manuel Garcia Aznar J, Walker D, Wertheim KY, Viceconti M. A Theoretical Analysis of the Scale Separation in a Model to Predict Solid Tumour Growth. J Theor Biol 2022; 547:111173. [DOI: 10.1016/j.jtbi.2022.111173] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 03/27/2022] [Accepted: 05/19/2022] [Indexed: 11/27/2022]
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Wang Y, Tian F, Guo P, Fu D, Heeres HJ, Tang T, Yuan H, Wang B, Li J. Catalytic liquefaction of sewage sludge to small molecular weight chemicals. Sci Rep 2020; 10:18929. [PMID: 33144686 PMCID: PMC7609695 DOI: 10.1038/s41598-020-75980-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 10/19/2020] [Indexed: 11/09/2022] Open
Abstract
The catalytic hydrotreatment of sewage sludge, the wet solid byproducts from wastewater treatment plants, using supported Ir, Pt, Pd, Ru catalysts had been investigated with different solvent conditions. Reactions were carried out in a batch set-up at elevated temperatures (400 °C) using a hydrogen donor (formic acid (FA) in isopropanol (IPA) or hydrogen gas), with sewage sludge obtained from different sampling places. Sewage sludge conversions of up to 83.72% were achieved using Pt/C, whereas the performance for the others catalysts is different and solvent had a strong effect on the conversion rate and product constitution. The sewage sludge oils were characterised using a range of analytical techniques (GC, GC-MS, GCxGC, GPC) and were shown to consist of monomers, mainly alkanes and higher oligomers.
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Affiliation(s)
- Yuehu Wang
- College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China. .,Observation and Research Station for Guizhou Karst Environmental Ecosystems, Guiyang, 550025, China.
| | - Feihong Tian
- College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China.,Observation and Research Station for Guizhou Karst Environmental Ecosystems, Guiyang, 550025, China
| | - Peimei Guo
- College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China.,Observation and Research Station for Guizhou Karst Environmental Ecosystems, Guiyang, 550025, China
| | - Dazhen Fu
- College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China.,Observation and Research Station for Guizhou Karst Environmental Ecosystems, Guiyang, 550025, China
| | - Hero Jan Heeres
- Chemical Engineering Department, ENTEG, University of Groningen, Nijenborg 4, 9747 AG, Groningen, The Netherlands
| | - Taotao Tang
- College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China.,Observation and Research Station for Guizhou Karst Environmental Ecosystems, Guiyang, 550025, China
| | - Huayu Yuan
- College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China.,Observation and Research Station for Guizhou Karst Environmental Ecosystems, Guiyang, 550025, China
| | - Bing Wang
- College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China.,Observation and Research Station for Guizhou Karst Environmental Ecosystems, Guiyang, 550025, China
| | - Jiang Li
- College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China.,Observation and Research Station for Guizhou Karst Environmental Ecosystems, Guiyang, 550025, China
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Dutta SK, Chakraborty S. Mixing effects on the kinetics and the dynamics of two-phase enzymatic hydrolysis of hemicellulose for biofuel production. BIORESOURCE TECHNOLOGY 2018; 259:276-285. [PMID: 29571171 DOI: 10.1016/j.biortech.2018.03.042] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 03/07/2018] [Accepted: 03/08/2018] [Indexed: 06/08/2023]
Abstract
This work uses a coupled experimental and modeling approach to explore the effects of macro- and micro-mixing on the kinetics and the dynamics of two-phase enzymatic hydrolysis of hemicellulose. Reactor mixing does not alter the non-competitive nature of product inhibition in hemicellulose hydrolysis by endoxylanase, but produces stronger inhibition that reduces the soluble sugar yield by 8-14.5%, as the mixing speed increases from 0 to 200 rpm. The kinetic constants (Km, Vmax, Kx) assume mass-transfer disguised values at 0-200 rpm. An optimal mixing strategy, comprising of 55-70 min of initial rapid convective macromixing followed by diffusive micromixing (without any macromixing) for the rest of the hydrolysis, increases xylose and reducing sugar yields by 6.3-8% and 13-20%, respectively, over continuous mixing at 200 rpm, for 1-5 mg/ml substrate loading at an optimum enzyme to substrate ratio of 1:20, with an energy saving of 94-96% over 24 h.
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Affiliation(s)
- Sajal Kanti Dutta
- Department of Chemical Engineering, Indian Institute of Technology, Kharagpur 721302, India
| | - Saikat Chakraborty
- Department of Chemical Engineering, Indian Institute of Technology, Kharagpur 721302, India; School of Energy Science and Engineering, Indian Institute of Technology, Kharagpur 721302, India.
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Chakraborty S, Singh PK, Paramashetti P. Microreactor-based mixing strategy suppresses product inhibition to enhance sugar yields in enzymatic hydrolysis for cellulosic biofuel production. BIORESOURCE TECHNOLOGY 2017; 237:99-107. [PMID: 28389042 DOI: 10.1016/j.biortech.2017.03.152] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 03/23/2017] [Accepted: 03/24/2017] [Indexed: 06/07/2023]
Abstract
A novel microreactor-based energy-efficient process of using complete convective mixing in a macroreactor till an optimal mixing time followed by no mixing in 200-400μl microreactors enhances glucose and reducing sugar yields by upto 35% and 29%, respectively, while saving 72-90% of the energy incurred on reactor mixing in the enzymatic hydrolysis of cellulose. Empirical exponential relations are provided for determining the optimal mixing time, during which convective mixing in the macroreactor promotes mass transport of the cellulase enzyme to the solid Avicel substrate, while the latter phase of no mixing in the microreactor suppresses product inhibition by preventing the inhibitors (glucose and cellobiose) from homogenizing across the reactor. Sugar yield increases linearly with liquid to solid height ratio (rh), irrespective of substrate loading and microreactor size, since large rh allows the inhibitors to diffuse in the liquid away from the solids, thus reducing product inhibition.
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Affiliation(s)
- Saikat Chakraborty
- Department of Chemical Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302, India.
| | - Prasun Kumar Singh
- Department of Chemical Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Pawan Paramashetti
- Department of Chemical Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
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Dutta SK, Chakraborty S. Kinetic analysis of two-phase enzymatic hydrolysis of hemicellulose of xylan type. BIORESOURCE TECHNOLOGY 2015; 198:642-650. [PMID: 26433789 DOI: 10.1016/j.biortech.2015.09.066] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 09/17/2015] [Accepted: 09/18/2015] [Indexed: 06/05/2023]
Abstract
We present a coupled experimental and theoretical framework for quantifying the kinetics of two-phase enzymatic hydrolysis of hemicellulose. For xylan loading of 1-5mg/ml, the nature of inhibition by the product xylose (non-competitive), the kinetic constants (Km=3.93 mg/ml, Vmax=0.0252 mg/ml/min) and the xylose inhibition constant (Kx=0.122 mg/ml) are experimentally determined. Our multi-step two-phase kinetic model incorporating enzyme adsorption to the solid substrate and non-competitive product inhibition is simulated using our kinetic data and validated against our experimentally measured temporal dynamics of xylose and reducing sugars. Further experiments show that higher substrate loading reduces the specific adsorption of the endoxylanase to the solid xylan and the enzyme's solid-liquid distribution ratio, which decelerates the solid hydrolysis and accelerates the liquid phase reactions. Thus, the xylose yield increases with substrate loading, which increases product inhibition and decreases reducing sugar yields. An operating cost analysis gives 3mg/ml as the optimal substrate loading.
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Affiliation(s)
- Sajal Kanti Dutta
- Department of Chemical Engineering, Indian Institute of Technology, Kharagpur 721302, India
| | - Saikat Chakraborty
- Department of Chemical Engineering, Indian Institute of Technology, Kharagpur 721302, India; School of Energy Science and Engineering, Indian Institute of Technology, Kharagpur 721302, India.
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