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Shiv Nadar University

Food waste generation is a worldwide phenomenon and disposing off it in an environmentally benign way has been a challenge. Thermochemical processes have the potential for not only processing mixed food waste effectively from an environmental point of view but also producing bioenergy in all three forms: solid (biochar), liquid (bio-oil) and gas (syngas). In this study, two thermochemical processes – fast pyrolysis and steam gasification – aimed for producing syngas as main product were carried out at three different temperatures: 600°C, 700°C and 800°C, and resulting syngas was characterised and compared for syngas yield, syngas composition, hydrogen yield and high heating value (HHV). The steam flow rate (SFR) was maintained at 0.625 mL min−1 for all gasification experiments. The syngas yield obtained from steam gasification was higher (1.2 m3 kg−1) than the syngas yield from fast pyrolysis (0.81 m3 kg−1). In addition, the hydrogen fraction was much higher in syngas from steam gasification (63.58%) than that from fast pyrolysis (45.03%). Furthermore, carbon conversion efficiency (CCE) and apparent thermal efficiency (ATE) were determined to compare the performance of these two processes. CCE was higher (63.6%) for steam gasification than that for pyrolysis (52.3%) which suggested that steam gasification was much more effective than fast pyrolysis to produce syngas of higher quality. © The Author(s) 2022.

World University root node

Chemical Engineering

(SoE) School of Engineering

Waste Management and Research

Syngas production from fast pyrolysis and steam gasification of mixed food waste

This study introduced an integrated two-stage process (ITP) for treating the mixed food waste (MFW) and producing syngas with higher hydrogen fraction where in-situ steam gasification was conducted after fast pyrolysis at the same temperature. Characteristics of syngas (syngas yield, composition, H2 yield, and high heating value (HHV)) from the proposed approach was first compared with that from conventional overlapping process (COP) of steam gasification process at the same temperature of 700°C and then with that from ITP at a higher temperature of 850°C. Syngas yield from ITP at 700°C (0.91 m3/kg) was almost the same as the syngas yield from COP at 700°C (0.85 m3/kg); however, the hydrogen and CO fraction were much higher (H2: gasification part~ 63%, average ~ 57.8%; CO: gasification part ~ 25%, average ~ 24%) than that from COP at 700°C (H2: 52%, CO: 19%). The hydrogen fraction in syngas further increased to 68% (from the gasification part) on increasing the ITP temperature to 850. Moreover, the syngas yield increased significantly (1.51 m3/kg) at the higher temperature of 850°. Finally, change in HHV values and corresponding changes in cold gas efficiency (CGE) were also presented to evaluate the process performance. © 2022 Taylor & Francis Group, LLC.

Energy Sources, Part A: Recovery, Utilization and Environmental Effects

Hydrogen rich syngas production from food waste via an integrated two-stage process of in-situ steam gasification after fast pyrolysis

This study presents the utilization of paper mill sludge (PMS) as biomass for producing hydrogen from steam gasification. PMS is a wet waste and its utilization for hydrogen production would give a new direction to its management. In this work, the performance of PMS during steam gasification was studied by varying the steam flow rate (SFR) and by determining the various characteristics of product gas such as syngas yield, syngas composition, and its high heating value (HHV). The SFR was varied from 0.25 mL/min to 1.0 mL/min depending upon the steam to biomass ratio. The performance parameter, cold gas efficiency (CGE) was also determined to evaluate the performance of PMS during steam gasification and the highest CGE was found to be around 96% at optimal SFR. The optimal SFR was found to be 0.75 mL/min and the syngas characteristics at optimal SFR were found to be 1.4 m3/Kg (syngas yield), 58% (hydrogen fraction in syngas), and 11.92 MJ/m3 (HHV). The feasibility of the PMS management and its utilization using steam gasification methods can further be increased by using renewable sources of energy for heating the gasifier. © 2022 Informa UK Limited, trading as Taylor & Francis Group.

Biofuels

Utilization of paper mill sludge as a sustainable source of hydrogen production

In the present study, the composition of bio-oil was determined using various analysis techniques such as H-NMR, 13 C-NMR, DEPT 90 & 135, and GC-MS. The bio-oil was produced from torrefaction of mixed food waste at 300 °C with heating rate of 10 °C/min. The novelty in this study lies in two facts; (i) NMR has been used as a qualitative method in contrary to it being used a quantitative method in previous works on bio-oil from other biomass and the compounds identified via GC-MS were cross checked via NMR Spectra of the compounds that were present in large quantity in bio-oil sample (> 3%); (2) bio-oil from mixed food waste (MFW) as no study was there to determine the detailed composition of bio-oil from MFW. Characteristics of MFW is quite different from typical biomass as it has additional compounds such as starch, protein, and lipids and found to be generating bio-oil of different composition. © 2022 Informa UK Limited, trading as Taylor & Francis Group.

Compositional study of bio-oil obtained from torrefaction of mixed food waste using H-NMR, 13C-NMR, DEPT 90 &amp; 135, and GC-MS

In this work, food waste was treated using a novel method of in situ gasification after pyrolysis (IGP) at the same temperature of 700 °C. This was done with the expectation that IGP would result in a higher hydrogen fraction in syngas as opposed to hydrogen fraction from a more conventional approach of overlapping pyrolysis and gasification (OGP). Firstly, both IGP and OGP were carried out at the same steam flow rate (SFR) of 0.625 mL/min and then only IGP was carried out by changing the flow rate from 0.625 to 0.375 mL/min. Comparative data obtained from OGP and IGP was presented for syngas characteristics (syngas yield, syngas composition, hydrogen yield, high heating value (HHV)). The syngas yield from OGP and IGP at the same flow rate of 0.625 mL/min was found to be 1.31 Nm3/kg and 1.48 Nm3/kg, respectively. The hydrogen fraction in syngas from OGP was found to be 54.5%, which increased significantly to 66.7% in syngas from the gasification part of IGP. Consecutively, HHV increased with an increase in hydrogen fraction in syngas from 12.1 to 17.4 MJ/kg. Additionally, the syngas yield obtained from IGP did not change much on changing the SFR to 0.375 mL/min; however, the hydrogen fraction changed to a lower value of 61.04%. Furthermore, performance parameters such as carbon conversion efficiency (CCE) and cold gas efficiency (CGE) are also presented to evaluate the performance of proposed method. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.

Biomass Conversion and Biorefinery

Food waste treatment using in situ gasification after pyrolysis to produce hydrogen-rich syngas

CD4-mimetic HIV-1 entry inhibitors are small sized molecules which imitate similar conformational flexibility, in gp120, to the CD4 receptor. However, the mechanism of the conformational flexibility instigated by these small sized inhibitors is little known. Likewise, the effect of the antibody on the function of these inhibitors is also less studied. In this study, we present a thorough inspection of the mechanism of the conformational flexibility induced by a CD4-mimetic inhibitor, NBD-557, using Molecular Dynamics Simulations and free energy calculations. Our result shows the functional importance of Asn425 in substrate induced conformational dynamics in gp120. The MD simulations of Asn425Gly mutant provide a less dynamic gp120 in the presence of NBD-557 without incapacitating the binding enthalpy of NBD-557. The MD simulations of complexes with the antibody clearly show the enhanced affinity of NBD-557 due to the presence of the antibody, which is in good agreement with experimental Isothermal Titration Calorimetry results (Biochemistry2006, 45, 10973-10980).

Chemistry

(SoNS) School of Natural Sciences

Fulltext

Molecules (Basel, Switzerland)

Does Antibody Stabilize the Ligand Binding in GP120 of HIV-1 Envelope Protein? Evidence from MD Simulation

In this work, the steam gasification of mixed food waste was carried out with torrefaction as pretreatment. Torrefaction was carried out at various temperatures; 230 °C, 260 °C, and 290 °C and for one-hour residence time. Improvement in physico-chemical properties of food waste by torrefaction was studied using proximate, elemental, and compositional analysis. Additionally, the effect of torrefaction on mass yield, energy yield, mass density and energy density was presented. Gasification was then carried out using torrefied food waste as biomass with steam as a gasification agent at 700 °C. The steam flow rate was kept at 0.625 mL/min with a steam to biomass ratio of 1.25. The resulting syngas was characterized for syngas yield, syngas composition, H2yield, and high heating value (HHV). It was found that syngas yield and H2field varied from 0.95 to 3.49 m3/Kg and 0.6 to 2.15 m3/Kg respectively from gasification of food waste torrefied at different temperatures. The highest HHV of syngas was found to be 12.19 MJ/Nm3. Cold gas efficiency and carbon conversion efficiency were also determined to evaluate the performance of proposed pretreatment on steam gasification. © 2020 Georg Thieme Verlag. All rights reserved.

Journal of Environmental Chemical Engineering

Steam gasification with torrefaction as pretreatment to enhance syngas production from mixed food waste

Hydrogen production from food waste by biochemical and thermochemical methods is reviewed herein. Generally, fermentation, a biochemical method, is considered to be more suitable for hydrogen production from food waste, and the performance of fermentation units depends on many factors, e.g., substrate composition, type of pretreatment, reactor configuration, and operating parameters, e.g., organic loading rate, hydraulic retention time, pH, and temperature. Controlling so many factors is tedious, expensive, and results in a slow process. On the other hand, thermochemical methods involve fewer factors and steps, can be much faster and less costly, and can also be used for efficient hydrogen production from food waste. Steam gasification has produced good hydrogen yields from raw food waste. © 2021 Wiley-VCH GmbH

Chemical Engineering and Technology

Biochemical and Thermochemical Routes of H2 Production from Food Waste: A Comparative Review

Silica Nanoparticles (SiNPs), due to its tunable properties and composition, meets the needs in specified applications. Rice Husk (RH), an agricultural waste, abundant in amorphous silica has its extensive application in various industrial products. However, the presence of impurities in RHs makes the extraction process difficult and optimum experimental conditions are needed to achieve maximum yield with specific properties for its specified applications. In this work, Rice Husk Ash (RHA) is prepared from RH by acid leaching followed by silica gel extraction from RHA via controlled pyrolysis at three temperatures (700°C, 750°C and 800°C). Pyrolyzed RHA is then dried and pulverized to get SiNPs. Characterization of SiNPs is done using UV-Vis Spectroscopy, X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). UV-Vis Spectroscopy and XRD analysis shows that the SiNPs extracted from RHA at 750°C exhibited the highest peak at 260 nm and 2θ=26° respectively and XRD and SEM analysis show that crystallite and particle size is in close agreement with each other. The optimum temperature being 750°C, silica gel formed at a pH 6 is more stable, transparent and thicker in comparison to the silica gel formed at varied pH. Moreover, the sodium silicate sample exhibits a bright green fluorescence and the intensity of fluorescence is higher for the sodium silicate prepared at 750°C range than at any other temperature. © 2020 Scientific Publishers. All rights reserved.

Journal of Scientific and Industrial Research

Extraction of silica nanoparticles from Rice Husk Ash and its characterization

Pulp and paper industry generates large wastewater volumes containing recalcitrant and toxic compounds in various forms. These compounds are highly toxic and standard primary/secondary treatments are unable to filter heavy metal contaminants besides organic species. An emerging demand of advance level treatment is the motivation of current work that explores possibility of using thick sand of deep aquifers as an adsorbent to remove inorganic and organic contaminants simultaneously from wastewater besides desalination. Popular ultrasonic cavitation is used to accelerate degradation of toxic organic effluent into less toxic open ring structures besides curing heavy metals to form new bonds during adsorption. Because of extreme local environment due to cavitation, heavy metals coagulate in silicon-aluminum atomic meshes and carbon nano tubes for less toxic new crystalline structure. Significant changes in physico-chemical investigations like pH, chemical oxygen demand and colour towards drinkable water standards indicate effective adsorption resulting into wastewater purification. © 2019

Physics

Colloids and Surfaces A: Physicochemical and Engineering Aspects

Ultrasonic cavitation tailored wastewater purification and desalination using thick sand of highly permeable deep aquifer

Large amount of food waste is generated from Indian kitchens and disposing off such a large amount possesses a great challenge in terms of environmental degradation and viable food waste processing technology. In this work, steam gasification was tested as an alternative viable technology to process the kitchen food waste. Preliminary study was carried out at low temperature on steam gasification in a fixed bed reactor to study the influence of steam flow rate (SFR) and temperature on the syngas yield, syngas composition, hydrogen yield. Performance parameters such as carbon conversion efficiency (CCE), and apparent thermal efficiency (ATE) are also calculated. Steam flow rates are varied from 0.125 mL/min to 0.75 mL/min and the temperatures are varied from 700 °C to 800 °C. The highest hydrogen yield is obtained at 0.5 mL/min SFR and 800 °C temperature and its highest value is 1.2 m3/kg. The highest value of performance parameters, CCE and ATE are found to be 63\% and 1.8. © 2020 Hydrogen Energy Publications LLC

International Journal of Hydrogen Energy

Low temperature steam gasification to produce hydrogen rich gas from kitchen food waste: Influence of steam flow rate and temperature

This study evaluated the change in physical and chemical properties of sun-dried food waste, during torrefaction in a fixed bed reactor. Torrefaction was carried out at different temperatures 230 °C, 260 °C, and 290 °C, for different residence times of 15, 30, 45, 60, 75, and 90 min in a fixed bed reactor. The solid torrefied products were analyzed by elemental analysis, proximate analysis, compositional analysis, and thermogravimetric analysis (TGA), and it was found that most suitable residence time for torrefaction was 60 min as torrefaction beyond 60 min did not yield much improvement in changing the properties of kitchen food waste. Carbon content increased from 46.0 to 58.5\%, consecutively increasing higher heating value (HHV) from 16.1 to 21.9\%. Compositional analysis demonstrated that there was not much hemicellulose left in the raw food waste after cooking; however, it had cellulose in significant proportion which went through decomposition during torrefaction. Lignin was not affected much. Various process parameters such as mass yield, energy yield, and energy density were also studied, and it was found the mass and energy yield decreased by 65.0\% and 47.5\%, respectively, and energy density increased by 35\%. Van Krevelen indicated clearly that torrefied char had achieved coal characteristics. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.

Evaluation of the physico-chemical development of kitchen food wastes through torrefaction - a biodiversity case study

This work was focused on finding the groundnut shell (GNS) gasification performance in a fluidized bed gasifier with bubbling air as gasification medium. GNS in powder form (a mixture of different particle size as given in table 8 in the article) was gasified using naturally available river sand as bed material, top of the bed feeding, conventional charcoal as bed heating medium, and two cyclones for proper cleaning and cooling the product gas. Experiments were performed using different operating conditions such as equivalence ratio (ER) between 0.29 and 0.33, bed temperature between 650°C and 800°C, and feedstock feeding rate between 36 and 31.7 kg/h. Different parameters were evaluated to study the gasifier performance such as gas yield, cold gas efficiency, carbon conversion efficiency (CCE), and high heating value. The most suitable ER value was found to be 0.31, giving the most stable bed temperature profile at 714.4°C with 5–10\% fluctuation. Cold gas efficiency and CCE at optimal ER of 0.31 was found to be 71.8\% and 91\%, respectively. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group.

Environmental Technology (United Kingdom)

Groundnut shell gasification performance in a fluidized bed gasifier with bubbling air as gasification medium

In recent years, biodiesel, as a renewable and environment-friendly fuel has emerged as one of the most investigated bio-fuel with a goal to decrease our dependence on petroleum fuels and reduce environmental pollution. The current commercial technique of biodiesel production via transesterification is constrained by high operating cost and energy requirements, long residence time and limited conversion due to equilibrium limitations. On the other hand, the process intensification using the micro-reactor technology demonstrated an excellent performance ascribed to short diffusion distance and high surface area-to-volume ratio that can lead to high heat and mass transfer rates and improved mixing compared to the conventional reactors. This review provides an overview of the current status of biodiesel production in micro-reactors. It includes various types of micro-reactors used in the production of biodiesel, factors affecting the biodiesel production (i.e., temperature, residence time, alcohol to oil molar ratio, micro-channel size, inlet mixer type, internal geometries, co-solvent, catalyst type and concentration). This review also includes the factors affecting the liquid-liquid flow patterns and application of micro-reactor technology in the purification of biodiesel. Some of the critical observations from this review are, 1) inlet mixer type, channel size, and internal channel geometry (zig-zag, omega, and tesla shaped channels) have shown a significant effect on mixing in micro-channels. 2) In case of base-catalyzed transesterification, the biodiesel yield was found to increase up to the reaction temperature of 60–65 °C. 3) Homogeneous alkaline catalyst (NaOH, KOH, CH3ONa) was preferred for the feedstock with low free fatty acid content (&lt;1 wt\%). However, an acid catalyst with high concentration, a significant amount of methanol and long reaction time were required for high free fatty acid feedstock (&gt;1 wt\%). Therefore, the current research is more focused on the investigation of heterogeneous catalysts in micro-reactors to develop an ecologically friendly process for the production of biodiesel. 4) Also, the reaction temperature and inlet mixer type had shown a significant effect on liquid-liquid flow patterns. This review also addressed the following literature gaps; a numbering-up technique to increase the throughput; catalyst development for high free fatty acid feedstock; continuous production of biodiesel in micro-reactors with in-line purification step to meet the energy demand and quality standards. © 2018 International Energy Initiative

Energy for Sustainable Development

Biodiesel production in micro-reactors: A review

This work is focused on intermediate pyrolysis of sawdust in a 100. g batch reactor at 500. ±. 10. °C. The pyrolysis vapors coming from reactor were directly quenched with chilled biodiesel from jatropha oil at 4. ±. 2. °C to obtain a suitable blend for stationary engine application. Total bio-oil yield was found to be 37\% (wt.). After layer separation from the resultant mixture, biodiesel miscible bio-oil phase calorific value was found to be 39. ±. 0.5. MJ/kg, which indicated that the bio-oil/biodiesel mixture was stable within the conditions tested and hence suitable for engine applications. The overall process provides a platform for blended biofuel, biochar as substitute of sub-bituminous coal and pyro-gas for combined heating and power application. © 2015 Elsevier B.V.