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Environmental and Energetic Valorization of Renewable Resources

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "A: Sustainable Energy".

Deadline for manuscript submissions: closed (15 June 2021) | Viewed by 48591

Special Issue Editor

Dipartimento di Ingegneria Civile, Chimica e di Ambientale, Scuola Politecnica, Università degli Studi di Genova, via Opera Pia 15, 16145 Genova, Italy
Interests: green chemical products
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The serious environmental impact associated with human activities and the progressive depletion of fossil fuel resources are seriously affecting sustainable development, so in the absence of global political strategies for a change of course and effective technological therapies, the future of the next generations may be put at risk. The quantity of waste that is produced annually globally by various industrial segments and by normal human activities is huge, and often their treatment is either not carried out or is carried out inappropriately. Even when this happens, their energy value is often overlooked, forgetting that they are valuable alternative energy resources. Therefore, technologies capable of combining environmental and energy aspects should be further developed.

The purpose of this Special Issue of the international journal Energies (2018 IF = 2.707), as can be seen from its own title, is to provide an overview of the current technologies for the Environmental and Energetic Valorization of Renewable Resources, including the treatment of different types of waste and byproducts (biomass of various kinds , industrial wastes, urban solid wastes and agro-industrial wastes, etc.), the possible recycling of resources, and/or energy recovery. Also of particular interest are technologies devoted to the solution of energy and environmental problems such as, but not limited to, a) Gas to Power technologies, i.e., highly efficient and environmentally friendly energy production through fuel cells, b) Power to Gas technologies, i.e., production of hydrogen or other fuels through electrolytic cells, c) reduction of carbon dioxide emissions through microalgae or systems in which the two previous technological categories are combined with traditional systems and/or renewable sources, and d) traditional waste treatments including biogas production, soil remediation, gasification and pyrolysis. I invite you to submit to this Special Issue an original paper, in the form of a scientific article, review or communication, and look forward to receiving your valuable contribution.

Prof. Dr. Attilio Converti
Guest Editor

Manuscript Submission Information

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Keywords

  • Energy and environment
  • Valorization of waste
  • Reduction of CO2 emissions
  • Fuel and electrolytic cells
  • Biogas production
  • Wastye recycling
  • Microalgae growth
  • Gasification and pyrolysis
  • Alternative energy
  • Soil remediation
  • Biosurfactants

Published Papers (14 papers)

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Editorial

Jump to: Research, Review

5 pages, 175 KiB  
Editorial
Environmental and Energetic Valorization of Renewable Resources
by Attilio Converti
Energies 2021, 14(24), 8440; https://0-doi-org.brum.beds.ac.uk/10.3390/en14248440 - 14 Dec 2021
Cited by 1 | Viewed by 1463
Abstract
This Editorial provides an overview of the 13 papers published in the Special Issue Environmental and Energetic Valorization of RenewableResources belonging to Section B: Sustainable Energy of the Energies journal, five being review papers and the remaining being scientific articles. Full article
(This article belongs to the Special Issue Environmental and Energetic Valorization of Renewable Resources)

Research

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17 pages, 4284 KiB  
Article
Impact of Technogenic Saline Soils on Some Chemical Properties and on the Activity of Selected Enzymes
by Joanna Lemanowicz, Kinga Gawlińska and Anetta Siwik-Ziomek
Energies 2021, 14(16), 4882; https://0-doi-org.brum.beds.ac.uk/10.3390/en14164882 - 10 Aug 2021
Cited by 5 | Viewed by 1574
Abstract
The study was based on saline soils with surface mineral layers impacted by the waste produced by the soda plant in Poland. The activity of selected enzymes (catalase CAT, alkaline AlP, and acid phosphatase AcP), pH in KCl, content of the clay, total [...] Read more.
The study was based on saline soils with surface mineral layers impacted by the waste produced by the soda plant in Poland. The activity of selected enzymes (catalase CAT, alkaline AlP, and acid phosphatase AcP), pH in KCl, content of the clay, total organic carbon (TOC), total nitrogen (TN), total exchangeable bases (TEB), electrical conductivity (ECe), CaCO3, and concentration of available phosphorus AP were investigated in the soil next to the soda plant. Based on the enzyme activity, the following were calculated: enzymatic pH indicator AlP/AcP, the resistance index (RS), resilience index (RL), relative changes (RCh), and the time index (TI). The soil was sampled from the mineral horizon in spring and autumn from eight (S1–S8) soil sampling sites in the area of the soda plant and from the control point (C). Soil is characterized by alkaline reaction. Statistical analysis (ANOVA, η2 effect size) showed significant variation in parameters under the influence of different sites next to soda plant. The content of TOC ranged from 4.70 to 47.7 g kg−1, and TN from 19 to 4.36 g kg−1. ECe next to the soda plant ranged between 6.87 and 204 mS cm−1. The highest values were confirmed in the soil of S1 both in spring and autumn. Higher TEB values were noted in the soil in autumn. In the soil within the impact of the soda plant, the AP content decreased and in the soil from sites S1, S3, S6, and S8 (in spring), the lowest AP content was recorded at 1.20, 4.14, 5.98, and 0.99 mg kg−1, respectively. The highest activity of AlP in spring was noted at site S1 and in autumn at site S4. In the soil next to the soda plant, the activity of AcP decreased, as compared to the control which is seen from the negative values of the coefficient of relative changes (RCh). The analysis of RCh in the catalase activities showed that in the soil from sites S1, S2, S3, S4, and S5, the activity increased, as compared to the control. The lowest values of the resistance index (RS) for phosphatases were reported in the soil of S6. Research shows that the activity of enzymes and their indexes make it possible to conduct long-term monitoring and identify the processes in soil. Full article
(This article belongs to the Special Issue Environmental and Energetic Valorization of Renewable Resources)
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15 pages, 1880 KiB  
Article
Assessment on the Application of Facilitated Transport Membranes in Cement Plants for CO2 Capture
by Maria-Chiara Ferrari, Antonio Amelio, Giuseppe Marino Nardelli and Riccardo Costi
Energies 2021, 14(16), 4772; https://0-doi-org.brum.beds.ac.uk/10.3390/en14164772 - 05 Aug 2021
Cited by 9 | Viewed by 1854
Abstract
Carbon dioxide capture from cement plant flue gas can play an important role in mitigating CO2 emission that lead to climate change. Among all the technologies evaluated, membranes have potential to be one of the most energy-efficient and low-cost CO2 capture [...] Read more.
Carbon dioxide capture from cement plant flue gas can play an important role in mitigating CO2 emission that lead to climate change. Among all the technologies evaluated, membranes have potential to be one of the most energy-efficient and low-cost CO2 capture option. In this work, a novel membrane technology, Facilitated Transport Membranes (FTMs), is assessed to further reduce energy demand and cost for CO2 capture in a cement plant. A new process that employs FTMs is simulated and applied to a real clinker production plant in Italy (Colacem, Gubbio). The process is then compared with other carbon capture technologies. Results show that the FTM technology can be competitive with other technologies despite the need of steam to operate the membrane. Despite the benefit in terms of specific emission compared to more established absorption with liquid amines process, further improvements on membrane performances are needed to gain also an economic advantage for carbon capture in the cement industry. Full article
(This article belongs to the Special Issue Environmental and Energetic Valorization of Renewable Resources)
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13 pages, 2629 KiB  
Article
Structural and Catalytic Characterization of La0.6Sr0.4MnO3 Nanofibers for Application in Direct Methane Intermediate Temperature Solid Oxide Fuel Cell Anodes
by Enrico Squizzato, Caterina Sanna, Antonella Glisenti and Paola Costamagna
Energies 2021, 14(12), 3602; https://0-doi-org.brum.beds.ac.uk/10.3390/en14123602 - 17 Jun 2021
Cited by 10 | Viewed by 2122
Abstract
In the present work, structural and catalytic characterization was performed on La0.6Sr0.4MnO3 (LSM) nanofibers. The LSM nanofibers were obtained using the electrospinning technique. For comparison, LSM powders with identical composition were characterized as well. The LSM powders were [...] Read more.
In the present work, structural and catalytic characterization was performed on La0.6Sr0.4MnO3 (LSM) nanofibers. The LSM nanofibers were obtained using the electrospinning technique. For comparison, LSM powders with identical composition were characterized as well. The LSM powders were prepared through a self-combustion citrate-based procedure. SEM, EDX, XRD, and BET investigations were carried out on both LSM nanofibers and powders, pointing out the different structural features. The LSM nanofibers showed a higher surface area than the LSM powders and a lower presence of strontium oxide on the surface. Results of the H2-Temperature Programmed Reduction (TPR) tests showed evidence of a higher reactivity of the nanofibers compared to the powders. The catalytic characterization was performed utilizing a methane oxidation activity test, revealing a better catalytic performance of the LSM nanofibers: at 800 °C. The methane conversion achieved with the LSM nanofibers was 73%, which compared well with the 50% obtained with powders at 900 °C. Full article
(This article belongs to the Special Issue Environmental and Energetic Valorization of Renewable Resources)
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16 pages, 4111 KiB  
Article
Small-Scale Solar–Bio-Hybrid Power Generation Using Brayton and Rankine Cycles
by Mauricio Bustamante, Abraham Engeda and Wei Liao
Energies 2021, 14(2), 472; https://0-doi-org.brum.beds.ac.uk/10.3390/en14020472 - 17 Jan 2021
Cited by 7 | Viewed by 1762
Abstract
This study conducted a detailed technical analysis of small-scale solar–bio-hybrid power generation systems using Rankine (steam turbine) and Brayton (gas turbine) cycles. Thermodynamic models were developed to characterize the state of working fluid and select the most suitable solar collection technology for individual [...] Read more.
This study conducted a detailed technical analysis of small-scale solar–bio-hybrid power generation systems using Rankine (steam turbine) and Brayton (gas turbine) cycles. Thermodynamic models were developed to characterize the state of working fluid and select the most suitable solar collection technology for individual power generation systems. Net capacity factor of power generation and utilization efficiencies of solar and biogas energy were used as parameters to evaluate energy generation and conclude the preferred system configuration. The analysis concluded that the steam turbine system has better global efficiency (67.7%) than the gas turbine system (55.7%), while the gas turbine system has better electricity generation efficiency (27.0%) than that (5.6%) of the steam turbine system. The effects of different climates on the selection of suitable hybrid systems were also investigated to delineate suitability and feasibility of different hybrid systems. In addition, the method used in this study can also be applied to investigate and optimize other small-scale hybrid renewable energy generation systems. Full article
(This article belongs to the Special Issue Environmental and Energetic Valorization of Renewable Resources)
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18 pages, 3301 KiB  
Article
Enhanced Oil Removal by a Non-Toxic Biosurfactant Formulation
by Emília Mendes da Silva Santos, Isabela Regina Alvares da Silva Lira, Hugo Moraes Meira, Jaciana dos Santos Aguiar, Raquel Diniz Rufino, Darne Germano de Almeida, Alessandro Alberto Casazza, Attilio Converti, Leonie Asfora Sarubbo and Juliana Moura de Luna
Energies 2021, 14(2), 467; https://0-doi-org.brum.beds.ac.uk/10.3390/en14020467 - 17 Jan 2021
Cited by 11 | Viewed by 2013
Abstract
In this study, a new formulation of low-cost, biodegradable, and non-toxic biosurfactant by Candida sphaerica UCP 0995 was investigated. The study was conducted in a bioreactor on an industrial waste-based medium, and a central composite rotatable design was used for optimization. The best [...] Read more.
In this study, a new formulation of low-cost, biodegradable, and non-toxic biosurfactant by Candida sphaerica UCP 0995 was investigated. The study was conducted in a bioreactor on an industrial waste-based medium, and a central composite rotatable design was used for optimization. The best results, namely a 25.22 mN/m reduction in surface tension, a biosurfactant yield of 10.0 g/L, and a critical micelle concentration of 0.2 g/L, were achieved in 132 h at an agitation speed of 175 rpm and an aeration rate of 1.5 vvm. Compositional and spectroscopic analyses of the purified biosurfactant by chemical methods, Fourier transform infrared spectroscopy, and nuclear magnetic resonance suggested that it is a glycolipid-type biosurfactant, and it showed no cytotoxicity in the MTT assay. The biosurfactant, submitted to different formulation methods as a commercial additive, remained stable for 120 days at room temperature. Tensioactive properties and stability were evaluated at different pH values, temperatures, and salt concentrations. The biosurfactant obtained with all formulation methods demonstrated good stability, with tolerance to wide ranges of pH, temperature and salinity, enabling application under extreme environmental conditions. Bioremediation tests were performed to check the efficacy of the isolated biosurfactant and the selected microbial species in removing oil from soil. The results demonstrated that the biosurfactant produced has promising properties as an agent for the bioremediation of contaminated soil. Full article
(This article belongs to the Special Issue Environmental and Energetic Valorization of Renewable Resources)
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19 pages, 2552 KiB  
Article
Investigation of Non-Isothermal Kinetics and Thermodynamic Parameters for the Pyrolysis of Different Date Palm Parts
by Emmanuel Galiwango, Ali H. Al-Marzuoqi, Abbas A. Khaleel and Mahdi M. Abu-Omar
Energies 2020, 13(24), 6553; https://0-doi-org.brum.beds.ac.uk/10.3390/en13246553 - 11 Dec 2020
Cited by 11 | Viewed by 1924
Abstract
Using the thermalgravimetric technique, we investigated the non-isothermal combustion kinetics of abundant and low-cost date palm wastes (leaflet, rachis, fibers, and their composite) as potential biomass energy sources. The kinetic and thermodynamic parameters were determined by Flynn–Wall–Ozawa (FWO), Kissinger–Akahila–Sunose (KAS), and Starink methods. [...] Read more.
Using the thermalgravimetric technique, we investigated the non-isothermal combustion kinetics of abundant and low-cost date palm wastes (leaflet, rachis, fibers, and their composite) as potential biomass energy sources. The kinetic and thermodynamic parameters were determined by Flynn–Wall–Ozawa (FWO), Kissinger–Akahila–Sunose (KAS), and Starink methods. Thermogravimetric analysis results showed a major peak for the degradation of volatiles between 127–138 °C with average percentage mass loss of 68.04 ± 1.5, 65.57 ± 0.6, 62.97 ± 5.5, and 59.26 ± 3.2, for rachis, composite, leaflet, and fibers, respectively. The FWO model showed the lowest activation energy, Eα, of 157 ± 25.6, 158 ± 25.7, 164 ± 40.1, and 169 ± 51.8 kJ mol−1 for the composite, rachis, leaflet, and fibers, respectively. The positive enthalpy values confirmed an endothermic pyrolysis reaction. For all models, a minimal difference of 4.40, 5.57, 6.55, and 7.51 kJ mol−1 between activation energy and enthalpy for rachis, fibers, composite, and leaflet ensued, respectively. The KAS model was best suited to describe chemical equilibrium with average ΔG values of 90.3 ± 28.8, 99.3 ± 34.9, 178.9 ± 27.3, and 186.5 ± 38.2 kJ mol−1 for rachis, fibers, composite, and leaflet, respectively. The reaction mechanism by the Malek and Popescu methods was ((g(α)=[ln(1α)]14) across the conversion range of 0.1–0.9 for all heating rates. The high energy content and volatile matter combined with low energy barriers make date palm waste a potential candidate in a biorefinery. Full article
(This article belongs to the Special Issue Environmental and Energetic Valorization of Renewable Resources)
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18 pages, 3441 KiB  
Article
Characterization of Metallic Interconnects Extracted from Solid Oxide Fuel Cell Stacks Operated up to 20,000 h in Real Life Conditions: The Air Side
by Giorgia Ghiara, Paolo Piccardo, Valeria Bongiorno, Christian Geipel and Roberto Spotorno
Energies 2020, 13(24), 6487; https://0-doi-org.brum.beds.ac.uk/10.3390/en13246487 - 08 Dec 2020
Cited by 12 | Viewed by 2355
Abstract
Metallic interconnects represent the main component of a solid oxide fuel cell (SOFC) stack in terms of weight and volume. They are typically made of ferritic stainless steel (FSS) coated on the air side. At the stack operating conditions, the interconnect is exposed [...] Read more.
Metallic interconnects represent the main component of a solid oxide fuel cell (SOFC) stack in terms of weight and volume. They are typically made of ferritic stainless steel (FSS) coated on the air side. At the stack operating conditions, the interconnect is exposed to a dual atmosphere: air at the cathode side; fuel (a hydrogen-rich mixture) at the anode side. The stacks considered in this study were field operated in reformed natural gas for 5000, 9000 and 20,000 h respectively. The analyzed interconnects are made from CROFER22APU and coated on the air side with Co-Mn base spinel. One interconnect has been studied for each stack by sampling and preparing cross section the inlet and outlet positions. The samples were characterized by SEM-EDXS in order to investigate the evolution of the interconnect at the air side. The interaction between the metal substrate and the coating is investigated highlighting the formation of chromia based thermal grown oxide (at the FSS/coating interface) and the solid-state diffusion of Cr and Fe from the metal into the coating. The microstructural features evolving as a function of time are also quantified. Full article
(This article belongs to the Special Issue Environmental and Energetic Valorization of Renewable Resources)
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22 pages, 3468 KiB  
Article
Neural-Based Ensembles and Unorganized Machines to Predict Streamflow Series from Hydroelectric Plants
by Jônatas Belotti, Hugo Siqueira, Lilian Araujo, Sérgio L. Stevan, Jr., Paulo S.G. de Mattos Neto, Manoel H. N. Marinho, João Fausto L. de Oliveira, Fábio Usberti, Marcos de Almeida Leone Filho, Attilio Converti and Leonie Asfora Sarubbo
Energies 2020, 13(18), 4769; https://0-doi-org.brum.beds.ac.uk/10.3390/en13184769 - 12 Sep 2020
Cited by 25 | Viewed by 2095
Abstract
Estimating future streamflows is a key step in producing electricity for countries with hydroelectric plants. Accurate predictions are particularly important due to environmental and economic impact they lead. In order to analyze the forecasting capability of models regarding monthly seasonal streamflow series, we [...] Read more.
Estimating future streamflows is a key step in producing electricity for countries with hydroelectric plants. Accurate predictions are particularly important due to environmental and economic impact they lead. In order to analyze the forecasting capability of models regarding monthly seasonal streamflow series, we realized an extensive investigation considering: six versions of unorganized machines—extreme learning machines (ELM) with and without regularization coefficient (RC), and echo state network (ESN) using the reservoirs from Jaeger’s and Ozturk et al., with and without RC. Additionally, we addressed the ELM as the combiner of a neural-based ensemble, an investigation not yet accomplished in such context. A comparative analysis was performed utilizing two linear approaches (autoregressive model (AR) and autoregressive and moving average model (ARMA)), four artificial neural networks (multilayer perceptron, radial basis function, Elman network, and Jordan network), and four ensembles. The tests were conducted at five hydroelectric plants, using horizons of 1, 3, 6, and 12 steps ahead. The results indicated that the unorganized machines and the ELM ensembles performed better than the linear models in all simulations. Moreover, the errors showed that the unorganized machines and the ELM-based ensembles reached the best general performances. Full article
(This article belongs to the Special Issue Environmental and Energetic Valorization of Renewable Resources)
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Review

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21 pages, 3508 KiB  
Review
Current Status of Energy Production from Solid Biomass in Southern Italy
by Cristina Moliner, Elisabetta Arato and Filippo Marchelli
Energies 2021, 14(9), 2576; https://0-doi-org.brum.beds.ac.uk/10.3390/en14092576 - 30 Apr 2021
Cited by 10 | Viewed by 2636
Abstract
This work analyses and discusses data on thermochemical plants in Southern Italy that are fed with solid biomass. The analysis takes into account the biomass availability and potential together with the cost-benefit analysis using technology development and economic indicators (LCOE). A total of [...] Read more.
This work analyses and discusses data on thermochemical plants in Southern Italy that are fed with solid biomass. The analysis takes into account the biomass availability and potential together with the cost-benefit analysis using technology development and economic indicators (LCOE). A total of 63,762 units have been categorised according to the employed technology and produced energy: power plants for electricity production or cogeneration plants for combined heat and electricity production (53 plants) and thermal units for heat production (63,709 units). The eight regions of the area have noteworthy differences. In terms of electricity generated from solid biomass Calabria is by far the largest producer, followed by Apulia. Sicily, Sardinia and Molise provide lower amounts while Abruzzo, Basilicata and Campania generate almost negligible amounts. Regarding thermal production, Campania and Calabria are the largest producers, but Basilicata, Molise and Abruzzo generate the highest amount per capita. The area is far from fully exploiting its biomass potential, and there are also no district heating grids. Bioenergy can be remarkably competitive, provided that capital costs are relatively low and low-cost biomass is available, as it is the case of Italy. New applications and markets for sub-products (i.e., char, ash) would help in lowering the still not competitive economic indicators (LCOE). Full article
(This article belongs to the Special Issue Environmental and Energetic Valorization of Renewable Resources)
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26 pages, 17996 KiB  
Review
Enzymatic Biofuel Cells: A Review on Flow Designs
by Linda Barelli, Gianni Bidini, Dario Pelosi and Elena Sisani
Energies 2021, 14(4), 910; https://0-doi-org.brum.beds.ac.uk/10.3390/en14040910 - 09 Feb 2021
Cited by 20 | Viewed by 3568
Abstract
Because of environmental concerns, there is a growing interest in new ways to produce green energy. Among the several studied applications, enzymatic biofuel cells can be considered as a promising solution to generate electricity from biological catalytic reactions. Indeed, enzymes show very good [...] Read more.
Because of environmental concerns, there is a growing interest in new ways to produce green energy. Among the several studied applications, enzymatic biofuel cells can be considered as a promising solution to generate electricity from biological catalytic reactions. Indeed, enzymes show very good results as biocatalysts thanks to their excellent intrinsic properties, such as specificity toward substrate, high catalytic activity with low overvoltage for substrate conversion, mild operating conditions like ambient temperature and near-neutral pH. Furthermore, enzymes present low cost, renewability and biodegradability. The wide range of applications moves from miniaturized portable electronic equipment and sensors to integrated lab-on-chip power supplies, advanced in vivo diagnostic medical devices to wearable devices. Nevertheless, enzymatic biofuel cells show great concerns in terms of long-term stability and high power output nowadays, highlighting that this particular technology is still at early stage of development. The main aim of this review concerns the performance assessment of enzymatic biofuel cells based on flow designs, considered to be of great interest for powering biosensors and wearable devices. Different enzymatic flow cell designs are presented and analyzed highlighting the achieved performances in terms of power output and long-term stability and emphasizing new promising fabrication methods both for electrodes and cells. Full article
(This article belongs to the Special Issue Environmental and Energetic Valorization of Renewable Resources)
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15 pages, 2373 KiB  
Review
An Integrated Approach to Convert Lignocellulosic and Wool Residues into Balanced Fertilisers
by Filippo Marchelli, Giorgio Rovero, Massimo Curti, Elisabetta Arato, Barbara Bosio and Cristina Moliner
Energies 2021, 14(2), 497; https://0-doi-org.brum.beds.ac.uk/10.3390/en14020497 - 18 Jan 2021
Cited by 8 | Viewed by 3065
Abstract
Valorising biomass waste and producing renewable energy or materials is the aim of several conversion technologies. In this work, we consider two residues from different production chains: lignocellulosic residues from agriculture and wool residues from sheep husbandry. These materials are produced in large [...] Read more.
Valorising biomass waste and producing renewable energy or materials is the aim of several conversion technologies. In this work, we consider two residues from different production chains: lignocellulosic residues from agriculture and wool residues from sheep husbandry. These materials are produced in large quantities, and their disposal is often costly and challenging for farmers. For their valorisation, we focus on slow pyrolysis for the former and water hydrolysis for the latter, concisely presenting the main literature related to these two processes. Pyrolysis produces the C-rich biochar, suitable for soil amending. Hydrolysis produces a N-rich fertiliser. We demonstrate how these two processes could be fruitfully integrated, as their products can be flexibly mixed to produce fertilisers. This solution would allow the achievement of balanced and tuneable ratios between C and N and the enhancement of the mechanical properties. We propose scenarios for this combined valorisation and for its coupling with other industries. As a result, biomass waste would be returned to the field, following the principles of circular economy. Full article
(This article belongs to the Special Issue Environmental and Energetic Valorization of Renewable Resources)
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29 pages, 2251 KiB  
Review
Oriented Fermentation of Food Waste towards High-Value Products: A Review
by Qiao Wang, Huan Li, Kai Feng and Jianguo Liu
Energies 2020, 13(21), 5638; https://0-doi-org.brum.beds.ac.uk/10.3390/en13215638 - 28 Oct 2020
Cited by 29 | Viewed by 4452
Abstract
Food waste has a great potential for resource recovery due to its huge yield and high organic content. Oriented fermentation is a promising method with strong application prospects due to high efficiency, strong robustness, and high-value products. Different fermentation types lead to different [...] Read more.
Food waste has a great potential for resource recovery due to its huge yield and high organic content. Oriented fermentation is a promising method with strong application prospects due to high efficiency, strong robustness, and high-value products. Different fermentation types lead to different products, which can be shifted by adjusting fermentation conditions such as inoculum, pH, oxidation-reduction potential (ORP), organic loading rate (OLR), and nutrients. Compared with other types, lactic acid fermentation has the lowest reliance on artificial intervention. Lactic acid and volatile fatty acids are the common products, and high yield and high purity are the main targets of food waste fermentation. In addition to operational parameters, reactors and processes should be paid more attention to for industrial application. Currently, continuously stirred tank reactors and one-stage processes are used principally for scale-up continuous fermentation of food waste. Electro-fermentation and iron-based or carbon-based additives can improve food waste fermentation, but their mechanisms and application need further investigation. After fermentation, the recovery of target products is a key problem due to the lack of green and economic methods. Precipitation, distillation, extraction, adsorption, and membrane separation can be considered, but the recovery step is still the most expensive in the entire treatment chain. It is expected to develop more efficient fermentation processes and recovery strategies based on food waste composition and market demand. Full article
(This article belongs to the Special Issue Environmental and Energetic Valorization of Renewable Resources)
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25 pages, 3931 KiB  
Review
Soil Bioremediation: Overview of Technologies and Trends
by Israel Gonçalves Sales da Silva, Fabíola Carolina Gomes de Almeida, Nathália Maria Padilha da Rocha e Silva, Alessandro Alberto Casazza, Attilio Converti and Leonie Asfora Sarubbo
Energies 2020, 13(18), 4664; https://0-doi-org.brum.beds.ac.uk/10.3390/en13184664 - 08 Sep 2020
Cited by 81 | Viewed by 16546
Abstract
Petroleum hydrocarbons, heavy metals and agricultural pesticides have mutagenic, carcinogenic, immunotoxic and teratogenic effects and cause drastic changes in soil physicochemical and microbiological characteristics, thereby representing a serious danger to health and environment. Therefore, soil pollution urgently requires the application of a series [...] Read more.
Petroleum hydrocarbons, heavy metals and agricultural pesticides have mutagenic, carcinogenic, immunotoxic and teratogenic effects and cause drastic changes in soil physicochemical and microbiological characteristics, thereby representing a serious danger to health and environment. Therefore, soil pollution urgently requires the application of a series of physicochemical and biological techniques and treatments to minimize the extent of damage. Among them, bioremediation has been shown to be an alternative that can offer an economically viable way to restore polluted areas. Due to the difficulty in choosing the best bioremediation technique for each type of pollutant and the paucity of literature on soil bioremediation enhanced by the use of specific additives, we reviewed the main in situ and ex situ methods, their current properties and applications. The first section discusses the characteristics of each class of pollutants in detail, while the second section presents current bioremediation technologies and their main uses, followed by a comparative analysis showing their respective advantages and disadvantages. Finally, we address the application of surfactants and biosurfactants as well as the main trends in the bioremediation of contaminated soils. Full article
(This article belongs to the Special Issue Environmental and Energetic Valorization of Renewable Resources)
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