Special Issue "Advances in Biorefining of Biowaste"

A special issue of Sustainability (ISSN 2071-1050). This special issue belongs to the section "Environmental Sustainability and Applications".

Deadline for manuscript submissions: 31 January 2021.

Special Issue Editors

Dr. Dimitrios Komilis
Website
Guest Editor
Department of Environmental Engineering, Democritus University of Thrace, Kimmeria Campus, Xanthi, GR 671 00, Greece
Interests: compost quality and compost stability indices; landfill processes; solid waste characterization and decomposition processes; life cycle analysis and mathematical optimization in solid waste management
Special Issues and Collections in MDPI journals
Prof. Dr. Paolo S. Calabrò
Website
Guest Editor
Università degli Studi Mediterranea di Reggio Calabria, Italy
Interests: anaerobic digestion; biogas; environmental engineering; landfill; waste management
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

during the past decades, under the framework of sustainability and circular economy, there has been an intense legislative focus on the management of organic waste and biowaste. According to two key European directives (1999/31/EC and 2008/98/EC), organic waste needs to be diverted from landfilling and needs to be valorized. Low technology composting of organic waste at the community or household level (which is highly promoted lately by municipalities) could be considered as a re-use and even a prevention technique, instead of a recycling technique. Thus, it would automatically promote it to the highest position of the waste hierarchy; however, its potential application is limited to site specific cases. Much focus has been recently given on more complex valorization techniques that aim to recover useful products during organic waste biological processes using biorefining schemes (e.g. recovery of enzymes during solid state fermentation, hydrogen production during anaerobiosis, biomass derived bioethanol). Some of them are still performed only at the laboratory or pilot scale and industrial applications are still pending. The above techniques are in addition to the classical compost and methane recovery processes that are normally the final part of the overall refining process. Such novel refining techniques will certainly allow a fully sustainable biowaste management.

This special issue will focus on biorefining of organic (solid) waste, as viewed through the prism of circular economy, and will cover the following state of the art topics:

  • Organic waste source separation schemes: decentralized vs centralized schemes.
  • Characterization of municipal and industrial biowaste.
  • Valorization of organic waste and recovery of useful compounds/materials.
  • Home and community composting.
  • Waste-based bioethanol generation.
  • Hydrogen production via anaerobic digestion.
  • Biogas refining and upgrading.
  • Life cycle analysis of biorefining techniques in organic waste management.
  • State of the art in MBT technologies for municipal solid waste management.

Prof. Dimitrios Komilis
Prof. Paolo S. Calabrò
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Sustainability is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1900 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Anaerobic digestion
  • Biogas
  • Bio-waste
  • Composting
  • hydrogen production
  • life cycle analysis
  • MBT technology
  • organic waste collection
  • organic waste valorization
  • solid-state fermentation
  • waste valorization

Published Papers (9 papers)

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Research

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Open AccessArticle
In-Situ Yeast Fermentation to Enhance Bioconversion of Coconut Endosperm Waste into Larval Biomass of Hermetia illucens: Statistical Augmentation of Larval Lipid Content
Sustainability 2020, 12(4), 1558; https://doi.org/10.3390/su12041558 - 19 Feb 2020
Cited by 1
Abstract
The aim of this study was to spur the lipid accumulation by larvae of Hermetia illucens or black soldier fly (BSFL) via feeding with yeast fermented medium. The Saccharomyces cerevisiae, a single cell yeast, was introduced at different concentrations (0.02, 0.1, 0.5, [...] Read more.
The aim of this study was to spur the lipid accumulation by larvae of Hermetia illucens or black soldier fly (BSFL) via feeding with yeast fermented medium. The Saccharomyces cerevisiae, a single cell yeast, was introduced at different concentrations (0.02, 0.1, 0.5, 1.0, 2.5 wt %) to execute an in-situ fermentation on coconut endosperm waste. The rearing of BSFL was started simultaneously and the rearing was stopped once the BSFL reached the fifth instar. With the increasing of yeast concentration, the rearing duration of BSFL was shortened from 15.5 to 13.5 days. Moreover, it was found that at 0.5 to 1.0 wt % yeast concentration, the lipid yield and lipid productivity of BSFL were statistically enhanced to their highest peaks, namely, at 49.4% and 0.53 g/day, respectively. With regard to biodiesel composition, BSFL-derived biodiesel contained mainly C12:0, C14:0, C16:0 and C18:1. The higher amount of saturated fatty acids could strengthen the oxidative stability biodiesel produced as compared with non-edible oils or microalgal lipid. At last, the addition of yeast was also found to improve the waste reduction index of coconut endosperm waste (CEW) from 0.31 to 0.40 g/day, heralding the capability of BSFL to valorize organic waste via bioconversion into its biomass to serve as a feedstock for biodiesel production. Full article
(This article belongs to the Special Issue Advances in Biorefining of Biowaste)
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Open AccessArticle
Valorizing Waste Lignocellulose-Based Furniture Boards by Phosphoric Acid and Hydrogen Peroxide (Php) Pretreatment for Bioethanol Production and High-Value Lignin Recovery
Sustainability 2019, 11(21), 6175; https://doi.org/10.3390/su11216175 - 05 Nov 2019
Cited by 1
Abstract
Three typical waste furniture boards (fiberboard, chipboard, and blockboard) were pretreated with phosphoric acid and hydrogen peroxide (PHP). The fractionation process of these feedstocks was attempted in order to harvest the cellulose-rich fraction for enzymatic hydrolysis and bioethanol conversion; further, lignin recovery was [...] Read more.
Three typical waste furniture boards (fiberboard, chipboard, and blockboard) were pretreated with phosphoric acid and hydrogen peroxide (PHP). The fractionation process of these feedstocks was attempted in order to harvest the cellulose-rich fraction for enzymatic hydrolysis and bioethanol conversion; further, lignin recovery was also considered in this process. The results indicated that 78.9–91.2% of the cellulose was recovered in the cellulose-rich fraction. The decreased crystallinity, which promoted the water retention capacity and enzyme accessibility, contributed greatly to the excellent hydrolysis performance of the cellulose-rich fraction. Therefore, rather high cellulose–glucose conversions of 83.3–98.0% were achieved by hydrolyzing the pretreated furniture boards, which allowed for harvesting 208–241 g of glucose from 1.0 kg of feedstocks. Correspondingly, 8.1–10.4 g/L of ethanol were obtained after 120 h of simultaneous saccharification and fermentation. The harvested lignin exhibited abundant carboxyl –OH groups (0.61–0.67 mmol g−1). In addition, approximately 15–26 g of harvested oligosaccharides were integrated during PHP pretreatment. It was shown that PHP pretreatment is feasible for these highly recalcitrant biomass board materials, which can diversify the bioproducts used in the integrated biorefinery concept. Full article
(This article belongs to the Special Issue Advances in Biorefining of Biowaste)
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Open AccessEditor’s ChoiceArticle
Biowaste Management in Italy: Challenges and Perspectives
Sustainability 2019, 11(15), 4213; https://doi.org/10.3390/su11154213 - 04 Aug 2019
Cited by 10
Abstract
The aim of this work is the development of a methodology for the technical and environmental assessment of biowaste valorization in 2G biorefineries. Italy was chosen as case study, considering years 2016–2017. Approach: the Italian context was evaluated through the following key [...] Read more.
The aim of this work is the development of a methodology for the technical and environmental assessment of biowaste valorization in 2G biorefineries. Italy was chosen as case study, considering years 2016–2017. Approach: the Italian context was evaluated through the following key parameters: Gross domestic power, climate, demography, and population density distribution described the Italian framework. The four most abundant biowaste categories were defined through their amounts and geo-localization: wastewater and sewage sludge (WSS, 4.06 Mt/y), organic fraction of municipal solid waste (OFMSW, 1.7 Mt/y), agricultural livestock waste (ALW, 5.7 Mt/y), and waste deriving from the food industry (FIW, 2.6 Mt/y). The geo-localization and quantitative evaluations of the available biowaste amounts were aimed at defining the dimension and localization of the biorefinery plant and at optimizing supply and transport chains, while the qualitative characteristic were aimed to evaluate the most promising process among thermo-valorization (TH) and anaerobic digestion (AD). Results: All considered biowastes were appropriate for biorefinery processes, since carbon content exceeds 40% and the carbon–nitrogen ratio was between 10 and 30. All biowaste categories were evaluated as feedstocks for two biorefinery processes: anaerobic digestion (AD) and thermo-valorization (TH) with energy recovery. Compared to TH, AD achieved in all cases the best performances in terms of produced energy and avoided CO2 emissions. The primary energy production of AD and TH for WSS, OFMSW, ALW, and FIW were respectively: 7.89 vs. 2.4 kWh/kg; 8.7 vs. 2.6 kWh/kg; 10.85 vs. 5.5 kWh/kg; and 12.5 vs. 7.8 kWh/kg. The main findings of this work were: the adoption of AD was technically more suitable than TH; AD increased the avoided CO2 emissions of 10%–89.9% depending on biowaste category. Full article
(This article belongs to the Special Issue Advances in Biorefining of Biowaste)
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Open AccessEditor’s ChoiceArticle
Semi-Continuous Anaerobic Digestion of Orange Peel Waste: Effect of Activated Carbon Addition and Alkaline Pretreatment on the Process
Sustainability 2019, 11(12), 3386; https://doi.org/10.3390/su11123386 - 19 Jun 2019
Cited by 15
Abstract
The valorization of orange peel waste (OPW) is sought worldwide mainly via anaerobic digestion. A common problem encountered during the biological treatment is the seasonality of its production and the presence of d-Limonene. The latter is a typical anti-microbial compound. This work aims [...] Read more.
The valorization of orange peel waste (OPW) is sought worldwide mainly via anaerobic digestion. A common problem encountered during the biological treatment is the seasonality of its production and the presence of d-Limonene. The latter is a typical anti-microbial compound. This work aims to evaluate the effect of the use of granular activated carbon (GAC) combined with alkaline pretreatment to enhance methane generation during semi-continuous anaerobic digestion of OPW. The experimental design consisted of two groups of experiments, A and B. Experiment A was designed to verify the maximum OPW loading and to assess the effect of pH and nutrients on the process. Experiment B was designed to study the effect of alkaline pretreatment alone and of alkaline pretreatment aided by biochar addition to the process. Apart from the methane yields, the d-Limonene contents were measured in all experiments. The preliminary results showed that OPW alkaline pretreatment after the addition of a moderate amount of GAC can render anaerobic digestion of OPW sustainable as long as the organic loading does not exceed 2 gVS·L−1·day−1 and nutrients are supplemented. The experiment in which GAC was added after alkaline pretreatment resulted in the highest methane yield and reactor stability. Full article
(This article belongs to the Special Issue Advances in Biorefining of Biowaste)
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Open AccessArticle
Repeated-Batch Fermentation of Cheese Whey for Semi-Continuous Lactic Acid Production Using Mixed Cultures at Uncontrolled pH
Sustainability 2019, 11(12), 3330; https://doi.org/10.3390/su11123330 - 16 Jun 2019
Cited by 7
Abstract
The paper investigates mixed-culture lactate (LA) fermentation of cheese whey (CW) in order to verify the possibility of using waste materials as feedstock to produce a product with high economic potential. The fermentation performance of two reactors operating in repeated-batch mode under uncontrolled [...] Read more.
The paper investigates mixed-culture lactate (LA) fermentation of cheese whey (CW) in order to verify the possibility of using waste materials as feedstock to produce a product with high economic potential. The fermentation performance of two reactors operating in repeated-batch mode under uncontrolled pH conditions and various hydraulic retention time and feeding conditions was evaluated in terms of LA production. Five experimental phases were conducted. The hydraulic retention time (HRT) was varied from 1 to 4 days to verify its effect on the process performance. The best results, corresponding to the maximum LA concentration (20.1 g LA/L) and the maximum LA yield (0.37 g chemical oxygen demand (COD)(LA)/g COD(CW)), were reached by feeding the reactors with cheese whey alone and setting the HRT to 2 days. The maximum productivity of lactic acid (10.6 g LA/L/day) was observed when the HRT was decreased to 1 day. Full article
(This article belongs to the Special Issue Advances in Biorefining of Biowaste)
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Open AccessArticle
A New Approach to Assess the Effect of Various Humic Compounds on the Metabolic Activity of Cells Participating in Methanogenesis
Sustainability 2019, 11(11), 3158; https://doi.org/10.3390/su11113158 - 05 Jun 2019
Cited by 6
Abstract
The possible use of the concentration of intracellular adenosine triphosphate (ATP) as a parameter enabling quick and adequate evaluation of the metabolic activity of methanogenic cells was demonstrated in the work. This approach was used to analyze the effect of introducing potassium humate [...] Read more.
The possible use of the concentration of intracellular adenosine triphosphate (ATP) as a parameter enabling quick and adequate evaluation of the metabolic activity of methanogenic cells was demonstrated in the work. This approach was used to analyze the effect of introducing potassium humate and fulvic acids (1–10 g/L) into media with four different methanogenic consortia producing biogas. The ATP concentration was analyzed by the bioluminescent luciferin–luciferase method at the beginning and end of the process. During the entire process, the biogas composition, biogas efficiency, and the kinetics of methanogenesis in the presence of humic compounds were determined. The increase in the concentration of potassium humate led to a decrease in the overall energy status of the cells and reduced methanogenesis efficiency. However, fulvic acids introduced into the media stimulated methanogenesis in half of the tested consortia, which was accompanied by an increase in ATP concentration in cell samples. So, a positive correlation between the metabolic activity of cells in biogas formation and the concentration of ATP was observed. ATP concentration control appears to be an attractive tool for finding compounds that suppress methanogenesis in landfills. Full article
(This article belongs to the Special Issue Advances in Biorefining of Biowaste)
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Open AccessEditor’s ChoiceArticle
Biochemical Hydrogen Potential Tests Using Different Inocula
Sustainability 2019, 11(3), 622; https://doi.org/10.3390/su11030622 - 24 Jan 2019
Cited by 17
Abstract
Four inocula collected from different operating facilities were tested in their hydrogenic performances by means of two biochemical hydrogen potential test set-ups using sucrose and food waste as substrates, with the aim of evaluating the influence of inoculum media in batch fermentative assays. [...] Read more.
Four inocula collected from different operating facilities were tested in their hydrogenic performances by means of two biochemical hydrogen potential test set-ups using sucrose and food waste as substrates, with the aim of evaluating the influence of inoculum media in batch fermentative assays. The selected inocula were: activated sludge collected from the aerobic unit of a municipal wastewater treatment plant, digested sludge from an anaerobic reactor treating organic waste and cattle manure, digested sludge from an anaerobic reactor treating agroindustrial residues, and digested sludge from an anaerobic reactor of a municipal wastewater treatment plant. Test results, in terms of specific hydrogen production, hydrogen conversion efficiency, and volatile solids removal efficiency, were significantly dependent on the type of inoculum. Statistical analysis showed different results, indicating that findings were due to the different inocula used in the tests. In particular, assays performed with activated sludge showed the highest performances for both substrates and both experimental set-ups. Full article
(This article belongs to the Special Issue Advances in Biorefining of Biowaste)
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Open AccessEditor’s ChoiceArticle
Biofuel Production and Phosphorus Recovery through an Integrated Treatment of Agro-Industrial Waste
Sustainability 2019, 11(1), 52; https://doi.org/10.3390/su11010052 - 21 Dec 2018
Cited by 9
Abstract
The present study aimed to develop an integrated treatment of agro-industrial waste for biofuel (biogas and syngas) production and for phosphorus recovery. In the first step, an anaerobic digestion (AD) process was carried out on two different mixtures of raw agro-industrial residues. Specifically, [...] Read more.
The present study aimed to develop an integrated treatment of agro-industrial waste for biofuel (biogas and syngas) production and for phosphorus recovery. In the first step, an anaerobic digestion (AD) process was carried out on two different mixtures of raw agro-industrial residues. Specifically, a mixture of asparagus and tomato wastes (mixture-1) and a mixture of potatoes and kiwifruit residues (mixture-2) were investigated. The results proved that the properties of mixtures notably affect the evolution of the digestion process. Indeed, despite the lower organic load, the maximum biogas yield, of about 0.44 L/gCODremoved, was obtained for mixture-1. For mixture-2, the digestion process was hindered by the accumulation of acidity due to the lack of alkalinity in respect to the amount of volatile fatty acids. In the second step, the digestates from AD were utilized for syngas production using supercritical water gasification (SCWG) at 450 °C and 250 bar. Both the digestates were rapidly converted into syngas, which was mainly composed of H2, CO2, CH4, and CO. The maximum values of global gasification efficiency, equal to 56.5 g/kgCOD, and gas yield, equal to 1.8 mol/kgTS, were detected for mixture-2. The last step of the integrated treatment aimed to recover the phosphorus content, in the form of MgKPO4ˑ6H2O, from the residual liquid fraction of SCWG. The experimental results proved that at pH = 10 and Mg/P = 1 it is possible to obtain almost complete phosphorus removal. Moreover, by using the scanning electronic microscopy, it was demonstrated that the produced precipitate was effectively composed of magnesium potassium phosphate crystals. Full article
(This article belongs to the Special Issue Advances in Biorefining of Biowaste)
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Review

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Open AccessReview
Biodegradation of Wasted Bioplastics in Natural and Industrial Environments: A Review
Sustainability 2020, 12(15), 6030; https://doi.org/10.3390/su12156030 - 27 Jul 2020
Cited by 4
Abstract
The problems linked to plastic wastes have led to the development of biodegradable plastics. More specifically, biodegradable bioplastics are the polymers that are mineralized into carbon dioxide, methane, water, inorganic compounds, or biomass through the enzymatic action of specific microorganisms. They could, therefore, [...] Read more.
The problems linked to plastic wastes have led to the development of biodegradable plastics. More specifically, biodegradable bioplastics are the polymers that are mineralized into carbon dioxide, methane, water, inorganic compounds, or biomass through the enzymatic action of specific microorganisms. They could, therefore, be a suitable and environmentally friendly substitute to conventional petrochemical plastics. The physico-chemical structure of the biopolymers, the environmental conditions, as well as the microbial populations to which the bioplastics are exposed to are the most influential factors to biodegradation. This process can occur in both natural and industrial environments, in aerobic and anaerobic conditions, with the latter being the least researched. The examined aerobic environments include compost, soil, and some aquatic environments, whereas the anaerobic environments include anaerobic digestion plants and a few aquatic habitats. This review investigates both the extent and the biodegradation rates under different environments and explores the state-of-the-art knowledge of the environmental and biological factors involved in biodegradation. Moreover, the review demonstrates the need for more research on the long-term fate of bioplastics under natural and industrial (engineered) environments. However, bioplastics cannot be considered a panacea when dealing with the elimination of plastic pollution. Full article
(This article belongs to the Special Issue Advances in Biorefining of Biowaste)
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