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Enaime G, Dababat S, Wichern M, Lübken M. Olive mill wastes: from wastes to resources. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2024; 31:20853-20880. [PMID: 38407704 PMCID: PMC10948480 DOI: 10.1007/s11356-024-32468-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Accepted: 02/09/2024] [Indexed: 02/27/2024]
Abstract
Olive oil extraction has recently experienced a continuous increase due to its related beneficial properties. Consequently, large amounts of olive mill wastes (OMWs) derived from the trituration process are annually produced, causing serious environmental problems. The limited financial capabilities of olive mills make them usually unable to bear the high costs required for the disposal of their wastes. Alternatively, the valorization of OMWs within the framework of the so-called waste-to-resource concept and their recycling can represent a successful strategy for the implementation of circular economy model in the olive industry, which could have significant socioeconomic impacts on low-income Mediterranean countries. There is, however, no unique solution for OMWs valorization, due to the wide variety of the wastes' composition and their seasonal production. In this review, the potential of OMWs for being reused and the recent technological advances in the field of OMWs valorization are assessed. Special focus is given to the analysis of the advantages and limitations of each technology and to reporting the most significant issues that still limiting its industrial scale-up. The information collected in this review shows that OMW could be effectively exploited in several sectors, including energy production and agriculture. OMWs potential seems, however, undervalued, and the implementation of sustainable valorization strategies in large-scale remains challenging. More efforts and policy actions, through collective actions, encouraging subsidies, and establishing public-private collaborations, are still needed to reconcile research progress with industrial practices and encourage the large-scale implementation of the waste-to-resource concept in the olive sector.
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Affiliation(s)
- Ghizlane Enaime
- Institute of Urban Water Management and Environmental Engineering, Ruhr-Universität Bochum, Universitätsstraße 150, 44780, Bochum, Germany.
| | - Salahaldeen Dababat
- Institute of Urban Water Management and Environmental Engineering, Ruhr-Universität Bochum, Universitätsstraße 150, 44780, Bochum, Germany
| | - Marc Wichern
- Institute of Urban Water Management and Environmental Engineering, Ruhr-Universität Bochum, Universitätsstraße 150, 44780, Bochum, Germany
| | - Manfred Lübken
- Institute of Urban Water Management and Environmental Engineering, Ruhr-Universität Bochum, Universitätsstraße 150, 44780, Bochum, Germany
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Lenzuni M, Converti A, Casazza AA. From laboratory- to industrial-scale plants: Future of anaerobic digestion of olive mill solid wastes. BIORESOURCE TECHNOLOGY 2024; 394:130317. [PMID: 38218408 DOI: 10.1016/j.biortech.2024.130317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 01/08/2024] [Accepted: 01/09/2024] [Indexed: 01/15/2024]
Abstract
In this review, the main properties of olive mill solid waste, the primary by-product of olive oil production, and its feasibility as a feedstock for anaerobic digesters operating at laboratory-, pilot- and industrial-scales are discussed in detail. Nutrient addition and thermal pretreatments were found to have the potential to address the challenges arising from the high carbon-to-nitrogen ratio, the low pH, and the high concentration of phenolic compounds. Furthermore, anaerobic co-digestion with different organic feedstocks has been identified as one of the most promising options to solve the aforementioned problems and the seasonality nature of olive waste, while improving the efficiency of anaerobic treatment plants that operate throughout the whole year. The insights generated from this study show co-digestion with wastes from animal farming to be the most environmentally and economically sustainable method for improving anaerobic digestion processes with olive mill solid waste.
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Affiliation(s)
- Martina Lenzuni
- Department of Civil, Chemical, and Environmental Engineering, University of Genoa, Italy; National Research Centre for Agricultural Technologies (CN AgriTech), Naples, Italy
| | - Attilio Converti
- Department of Civil, Chemical, and Environmental Engineering, University of Genoa, Italy; National Research Centre for Agricultural Technologies (CN AgriTech), Naples, Italy.
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Maamri S, Moussa A, Yacine M. Development of a Statistical Model to Predict Methane Production from Waste Activated Sludge Co-Digested with Olive Mill Wastewater and Cattle Dung by Response Surface Methodology. CHEMISTRY & CHEMICAL TECHNOLOGY 2023. [DOI: 10.23939/chcht17.01.141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
Abstract
Nowadays, population growth is likely to lead to a wide variety of biomass wastes generation from the diversified human, industrial, and agricultural activities. Anaerobic digestion is mostly applied to manage biomass wastes and mitigate a huge spectrum of environmental damages. This paper aims to enhance the anaerobic digestion efficiency of multicomponent substrates, using a mixture of waste activated sludge (WAS), olive mill wastewater (OMW), and cattle manure (CM). A Response Surface Methodology is employed in experimental design to determine individual and interactive effects on methane yield and chemical oxygen demand reduction. After numerical optimization using Design Expert®, the optimum values of the test factors in actual were as follows: initial pH = 8, COD/N ratio = 47, 42, CM/WAS-OMW ratio = 0.352, TS = 42.94 g/L. The obtained results indicate that anaerobic co-digestion performance could be achieved by optimising substrate composition to assure a larger microbial synergistic effect.
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Benavides V, Pinto-Ibieta F, Serrano A, Rubilar O, Ciudad G. Use of Anthracophyllum Discolor and Stereum Hirsutum as a Suitable Strategy for Delignification and Phenolic Removal of Olive Mill Solid Waste. Foods 2022; 11:foods11111587. [PMID: 35681337 PMCID: PMC9180551 DOI: 10.3390/foods11111587] [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: 03/21/2022] [Revised: 05/19/2022] [Accepted: 05/25/2022] [Indexed: 02/04/2023] Open
Abstract
This study evaluated the use of the white-rot fungi (WRF) Anthracophyllum discolor and Stereum hirsutum as a biological pretreatment for olive mill solid mill waste (OMSW). The WRF strains proposed were added directly to OMSW. The assays consisted of determining the need to add supplementary nutrients, an exogenous carbon source or use agitation systems, and evaluating WRF growth, enzyme activity, phenolic compound removal and lignin degradation. The highest ligninolytic enzyme activity was found at day 10, reaching 176.7 U/L of manganese-independent peroxidase (MniP) produced by A. discolor, and the highest phenolic removal (more than 80% with both strains) was reached after 24 days of incubation. The confocal laser scanning microscopy analysis (CLSM) confirmed lignin degradation through the drop in lignin relative fluorescence units (RFU) from 3967 for untreated OMSW to 235 and 221 RFU, showing a lignin relative degradation of 94.1% and 94.4% after 24 days of treatment by A. discolor and S. hirsutum, respectively. The results demonstrate for the first time that A. discolor and S. hirsutum were able to degrade lignin and remove phenolic compounds from OMSW using this as the sole substrate without adding other nutrients or using agitation systems. This work indicates that it could be possible to design an in situ pretreatment of the valorization of OMSW, avoiding complex systems or transportation. In this sense, future research under non-sterile conditions is needed to evaluate the competition of WRF with other microorganisms present in the OMSW. The main drawbacks of this work are associated with both the low reaction time and the water addition. However, OMSW is seasonal waste produced in one season per year, being stored for a long time. In terms of water addition, the necessary optimization will be addressed in future research.
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Affiliation(s)
- Viviana Benavides
- Programa de Doctorado en Ciencias de Recursos Naturales, Facultad de Ingeniería y Ciencias, Universidad de La Frontera, Casilla 54-D, Temuco 4780000, Chile;
| | - Fernanda Pinto-Ibieta
- Departamento de Ingeniería Química, Facultad de Ingeniería y Ciencias, Universidad de La Frontera, Avenida Francisco Salazar #01145, Casilla 54-D, Temuco 4780000, Chile; (F.P.-I.); (O.R.)
- Departamento de Procesos Industriales, Facultad de Ingeniería, Universidad Católica de Temuco, Casilla 15-D, Temuco 4780000, Chile
| | - Antonio Serrano
- Departamento de Microbiología, Facultad de Farmacia, Campus Universitario de Cartuja s/n, Universidad de Granada, 18011 Granada, Spain;
- Instituto de Investigación del Agua, Universidad de Granada, 18071 Granada, Spain
| | - Olga Rubilar
- Departamento de Ingeniería Química, Facultad de Ingeniería y Ciencias, Universidad de La Frontera, Avenida Francisco Salazar #01145, Casilla 54-D, Temuco 4780000, Chile; (F.P.-I.); (O.R.)
- Scientific and Technological Bioresources Nucleus (BIOREN), Universidad de La Frontera, Avenida Francisco Salazar #01145, Casilla 54-D, Temuco 4780000, Chile
| | - Gustavo Ciudad
- Departamento de Ingeniería Química, Facultad de Ingeniería y Ciencias, Universidad de La Frontera, Avenida Francisco Salazar #01145, Casilla 54-D, Temuco 4780000, Chile; (F.P.-I.); (O.R.)
- Scientific and Technological Bioresources Nucleus (BIOREN), Universidad de La Frontera, Avenida Francisco Salazar #01145, Casilla 54-D, Temuco 4780000, Chile
- Instituto del Medio Ambiente (IMA), Universidad de La Frontera, Avenida Francisco Salazar #01145, Casilla 54-D, Temuco 4780000, Chile
- Correspondence: ; Tel.: +56-45-2325556
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Poranek N, Łaźniewska-Piekarczyk B, Lombardi L, Czajkowski A, Bogacka M, Pikoń K. Green Deal and Circular Economy of Bottom Ash Waste Management in Building Industry-Alkali (NaOH) Pre-Treatment. MATERIALS (BASEL, SWITZERLAND) 2022; 15:3487. [PMID: 35629514 PMCID: PMC9148039 DOI: 10.3390/ma15103487] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 05/06/2022] [Accepted: 05/09/2022] [Indexed: 01/01/2023]
Abstract
This study aims to investigate the possibilities of municipal waste incineration bottom ash (MSWIBA) utilization in the construction sector. MSWIBA development fits into the European Green Deal, Sustainable Development Goals (SDGs), and the Circular Economy (CE). This manuscript describes current MSWIBA treatment such as solidification, ceramization, vitrification, chemical activation (NaOH, CaOH2, NA2SiO3 + NaOH, Na2CO3 + NaOH, NH4OH), acid treatment with diluted solutions (HCl, H2SO4), chemical stabilization (FeSO4, PO43-), chelation, etc. For the purpose of comparative research, MSWIBA before valorization, after valorization, and after NaOH pre-treatment was investigated. In terms of their physico-chemical properties, the tested samples were examined. Three kinds of MSWIBA were used as a substitute for 30% of cement in mortars. The mortars were tested for 28-day strength. Leachability tests were performed in acid, aggressive, alkali, and neutral water environments. Life Cycle Assessment (LCA) analysis was carried out, which presented the environmental benefits of MSWIBA management in construction.
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Affiliation(s)
- Nikolina Poranek
- Department of Technologies and Installations for Waste Management, Faculty of Energy and Environmental Engineering, The Silesian University of Technology, Konarskiego 18, 44-100 Gliwice, Poland; (M.B.); (K.P.)
- Department of Building Engineering and Building Physics, Faculty of Civil Engineering, The Silesian University of Technology, Akademicka 5, 44-100 Gliwice, Poland
- Doctoral School, The Silesian University of Technology, Akademicka 2A, 44-100 Gliwice, Poland
| | - Beata Łaźniewska-Piekarczyk
- Department of Building Engineering and Building Physics, Faculty of Civil Engineering, The Silesian University of Technology, Akademicka 5, 44-100 Gliwice, Poland
| | - Lidia Lombardi
- Faculty of Engineering, Niccolò Cusano University, Via Don Carlo Gnocchi, 3, 00166 Rome, Italy;
| | - Adrian Czajkowski
- Doctoral School, The Silesian University of Technology, Akademicka 2A, 44-100 Gliwice, Poland
- Department of Power Engineering and Turbomachinery, Faculty of Energy and Environmental Engineering, The Silesian University of Technology, Konarskiego 18, 44-100 Gliwice, Poland
- EnergySol s.c., Przepiórek 53, 43-100 Tychy, Poland
| | - Magdalena Bogacka
- Department of Technologies and Installations for Waste Management, Faculty of Energy and Environmental Engineering, The Silesian University of Technology, Konarskiego 18, 44-100 Gliwice, Poland; (M.B.); (K.P.)
| | - Krzysztof Pikoń
- Department of Technologies and Installations for Waste Management, Faculty of Energy and Environmental Engineering, The Silesian University of Technology, Konarskiego 18, 44-100 Gliwice, Poland; (M.B.); (K.P.)
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Elalami D, Carrere H, Abdelouahdi K, Garcia-Bernet D, Peydecastaing J, Vaca-Medina G, Oukarroum A, Zeroual Y, Barakat A. Mild microwaves, ultrasonic and alkaline pretreatments for improving methane production: Impact on biochemical and structural properties of olive pomace. BIORESOURCE TECHNOLOGY 2020; 299:122591. [PMID: 31918150 DOI: 10.1016/j.biortech.2019.122591] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 12/06/2019] [Accepted: 12/07/2019] [Indexed: 06/10/2023]
Abstract
This study aims to investigate the effects of microwaves, ultrasonic and alkaline pretreatments on olive pomace properties and its biomethane potential. Alkaline pretreatment was found to reduce lipid and fiber contents (especially lignin) and to increase soluble matter. The alkali pretreatment at a dose of 8% (w/w TS) under 25 °C and for 1 day removed 96% of initial lipids from the solid olive pomace. Unlike NaOH addition, mild microwaves and ultrasonic pretreatments had no impact on lignin. However, in the case of long microwaves pretreatment (450 W-10 min), cellulose and lignin contents were reduced by 50% and 26% respectively. Similarly, the combination of ultrasonic and alkali reagent showed a positive effect on fiber degradation and lipid solubilization as well as a positive impact on methane production. Statistical analysis highlighted the correlation between NaOH dose, solubilization and methane production. The alkaline pretreatment at ambient temperature appeared the most energetically efficient.
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Affiliation(s)
- Doha Elalami
- Montpellier University, INRAE, LBE, 102 Avenue des Etangs, 11100 Narbonne, France; LCME, Sciences and Techniques Faculty, Cadi Ayyad University, Marrakech, Morocco; Mohammed VI Polytechnic University,43,150 Benguerir, Morocco
| | - Helene Carrere
- Montpellier University, INRAE, LBE, 102 Avenue des Etangs, 11100 Narbonne, France.
| | - Karima Abdelouahdi
- LCME, Sciences and Techniques Faculty, Cadi Ayyad University, Marrakech, Morocco
| | - Diana Garcia-Bernet
- Montpellier University, INRAE, LBE, 102 Avenue des Etangs, 11100 Narbonne, France
| | - Jerome Peydecastaing
- Laboratoire de Chimie Agro-industrielle, Université de Toulouse, INRA, Toulouse, France
| | - Guadalupe Vaca-Medina
- Centre d'Application et de Traitement des Agroressources, Université de Toulouse, INPT, Toulouse, France
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Messineo A, Maniscalco MP, Volpe R. Biomethane recovery from olive mill residues through anaerobic digestion: A review of the state of the art technology. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 703:135508. [PMID: 31761373 DOI: 10.1016/j.scitotenv.2019.135508] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 11/11/2019] [Accepted: 11/12/2019] [Indexed: 06/10/2023]
Abstract
Residues from production of olive oil are generated yearly in great amounts, both in liquid and solid forms. Different waste treatment systems were proposed in literature, to minimize environmental pollution while raising the energy recovery. Anaerobic digestion is one of the available routes to recover energy from waste via production of biogas while reducing organic load and pollutants to the environment. The use of farming and agro industrial wastes as co-substrate in anaerobic digestion can induce benefits related to the simultaneous treatment of different wastes. In particular, co-digestion can significantly enhance the process stability as well as the bio-methane generation. This work aims at reviewing the latest achievements in anaerobic digestion of olive mill residues, focusing on the aspects that can mostly favor the process, principally from a technical but also from an economical point of view. For the mono-digestion processes, methane yields up to 419 LCH4 kgVS-1 were reported for olive mill wastewaters (Calabrò et al. 2018), while a production of 740 LCH4 kgVS-1 was achieved when digesting olive mill solid waste together with olive mill wastewater and milk whey (Battista et al. 2015). An increase up to 143% in the methane yield was also reported when the feedstock was subjected to a 5 days aeration before digesting it in a semi-continuous stirred tank reactor (González-González and Cuadros 2015).
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Affiliation(s)
- Antonio Messineo
- Faculty of Engineering and Architecture, Kore University of Enna, Cittadella Universitaria, Enna, Italy.
| | | | - Roberto Volpe
- School of Engineering and Materials Science, Queen Mary University, London, United Kingdom
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Long-Term Evaluation of Mesophilic Semi-Continuous Anaerobic Digestion of Olive Mill Solid Waste Pretreated with Steam-Explosion. ENERGIES 2019. [DOI: 10.3390/en12112222] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Steam-explosion is a promising technology for recovering phenolic compounds from olive mill solid waste (OMSW) due to its high impact on the structure of the fibre. Moreover, the recovery of the phenols, which are well-known microbial inhibitors, could improve the subsequent biomethanization of the dephenolized OMSW to produce energy. However, there is a considerable lack of knowledge about how the remaining phenolic compounds could affect a long-term biomethanization process of steam-exploded OMSW. This work evaluated a semi-continuous mesophilic anaerobic digestion of dephenolized steam-exploited OMSW during a long operational period (275 days), assessing different organic loading rates (OLRs). The process was stable at an OLR of 1 gVS/(L·d), with a specific production rate of 163 ± 28 mL CH4/(gVS·d). However, the increment of the OLR up to 2 gVS/(L·d) resulted in total exhaust of the methane production. The increment in the propionic acid concentration up to 1486 mg/L could be the main responsible factor for the inhibition. Regardless of the OLR, the concentration of phenolic compounds was always lower than the inhibition limits. Therefore, steam-exploited OMSW could be a suitable substrate for anaerobic digestion at a suitable OLR.
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Serrano A, Fermoso FG, Alonso-Fariñas B, Rodríguez-Gutiérrez G, López S, Fernandez-Bolaños J, Borja R. Performance evaluation of mesophilic semi-continuous anaerobic digestion of high-temperature thermally pre-treated olive mill solid waste. WASTE MANAGEMENT (NEW YORK, N.Y.) 2019; 87:250-257. [PMID: 31109524 DOI: 10.1016/j.wasman.2019.02.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 01/03/2019] [Accepted: 02/01/2019] [Indexed: 06/09/2023]
Abstract
The aim of the present work was to evaluate the effects of a thermal pre-treatment of olive mill solid waste (OMSW) and phenol extraction process on the semi-continuous anaerobic digestion of this pre-treated waste during a prolonged operational period (275 days) in order to assess the organic loading rates (OLR) of 1 ad 2 g Volatile Solids (VS)/(L·d). The anaerobic digestion of thermally pre-treated and de-phenolized OMSW was stable at an OLR of 1 g VS/(L·d), which permitted a specific production rate of 172 ± 60 mL CH4/(g VS·d). However, the system was not able to operate at an OLR of 2 g VS/(L·d), which resulted in the total failure of the process. Regardless of the applied OLR, the phenolic compounds were effectively degraded and the inhibition thresholds were not reached. The inhibition of the anaerobic digestion process at an OLR of 2 g VS/(L·d) was probably due to the overloading of the system, indicated by the accumulation of organic matter and volatile fatty acids. The operation of the anaerobic digester under stable conditions allowed for high profitability for the proposed bio-refinery concept, which would still be profitable at a phenol extract price above 51.8 €/kg, which is 90% lower than the current price of 520 €/kg.
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Affiliation(s)
- Antonio Serrano
- Instituto de la Grasa (CSIC), Campus Universitario Pablo de Olavide, Edificio 46, Ctra. de Utrera km 1, 41013 Sevilla, Spain; School of Civil Engineering, The University of Queensland, Campus St. Lucia - AEB Ed 49, St Lucia 4067, QLD, Australia
| | - Fernando G Fermoso
- Instituto de la Grasa (CSIC), Campus Universitario Pablo de Olavide, Edificio 46, Ctra. de Utrera km 1, 41013 Sevilla, Spain.
| | - Bernabé Alonso-Fariñas
- Department of Chemical and Environmental Engineering, University of Sevilla, Higher Technical School of Engineering, Camino de los Descubrimientos, s/n, Sevilla, Spain
| | - Guillermo Rodríguez-Gutiérrez
- Instituto de la Grasa (CSIC), Campus Universitario Pablo de Olavide, Edificio 46, Ctra. de Utrera km 1, 41013 Sevilla, Spain
| | - Sergio López
- Instituto de la Grasa (CSIC), Campus Universitario Pablo de Olavide, Edificio 46, Ctra. de Utrera km 1, 41013 Sevilla, Spain; Department of Cell Biology, University of Sevilla, Sevilla, Spain
| | - Juan Fernandez-Bolaños
- Instituto de la Grasa (CSIC), Campus Universitario Pablo de Olavide, Edificio 46, Ctra. de Utrera km 1, 41013 Sevilla, Spain
| | - Rafael Borja
- Instituto de la Grasa (CSIC), Campus Universitario Pablo de Olavide, Edificio 46, Ctra. de Utrera km 1, 41013 Sevilla, Spain
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Zhang L, Loh KC, Zhang J. Food waste enhanced anaerobic digestion of biologically pretreated yard waste: Analysis of cellulose crystallinity and microbial communities. WASTE MANAGEMENT (NEW YORK, N.Y.) 2018; 79:109-119. [PMID: 30343737 DOI: 10.1016/j.wasman.2018.07.036] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Revised: 07/12/2018] [Accepted: 07/17/2018] [Indexed: 06/08/2023]
Abstract
Solid waste treatment through anaerobic digestion (AD) technology contributes to energy recycling and reuse of various solid organic wastes. However, yard waste (YW) is generally recalcitrant to AD due to the presence of high cellulose and hemicellulose content, which are difficult to be hydrolyzed. In this study, to enhance hydrolysis efficiency, YW was biologically pretreated with digested sludge and supplemented with food waste (FW) before AD process. Effects of FW supplementation on pH, SCOD, cellulose and hemicellulose content and cellulose crystallinity were examined. The optimal amount of FW supplementation was determined to be 10 wt%. An increase of 6.5-20.3% in cellulose reduction and an increase of 14.8-53.1% in hemicellulose reduction in digesters was achieved within the optimal pretreatment time of 4 days. After hydrolysis, cellulose crystallinity decreased by 23% from 71% in the control digester, which was responsible for improved biodegradability of cellulose in YW. FT-IR analysis of hydrolysis mixture confirmed that partial hydrogen bonds were destroyed in digesters with supplementation of 10 wt% FW, leading to a higher extent of degradation of the feedstock. In the batch AD of FW supplemented YW, results indicated that methane yield was 35% higher than that of the control digester without FW supplementation. Pyrosequencing analysis indicated that the abundance of bacterial genus Sphaerochaeta and Cellulosibacter in subsequent digestion were enhanced by 10- and 5-folds by 10 wt% FW supplementation, respectively, and were deemed to be responsible for the enhanced anaerobic digestion performance.
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Affiliation(s)
- Le Zhang
- Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore
| | - Kai-Chee Loh
- Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore.
| | - Jingxin Zhang
- Environmental Research Institute, National University of Singapore, Singapore
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Christoforou E, Fokaides PA. A review of olive mill solid wastes to energy utilization techniques. WASTE MANAGEMENT (NEW YORK, N.Y.) 2016; 49:346-363. [PMID: 26810031 DOI: 10.1016/j.wasman.2016.01.012] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 12/23/2015] [Accepted: 01/14/2016] [Indexed: 06/05/2023]
Abstract
In recent years, the utilization of olive industry by-products for energy purposes has gained significant research interest and many studies have been conducted focused on the exploitation of olive mill solid waste (OMSW) derived from the discontinuous or continuous processing of olive fruits. In this review study, the primary characteristics of OMSW and the techniques used to define their thermal performance are described. The theoretical background of the main waste-to-energy conversion pathways of solid olive mill wastes, as well as the basic pre-treatment techniques for upgrading solid fuels, are presented. The study aims to present the main findings and major conclusions of previously published works undertaken in the last two decades focused on the characterization of olive mill solid wastes and the utilization of different types of solid olive mill residues for energy purposes. The study also aims to highlight the research challenges in this field.
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Affiliation(s)
- Elias Christoforou
- School of Engineering and Applied Sciences, Frederick University, Cyprus 7., Y. Friderickou Str., 1036 Nicosia, Cyprus
| | - Paris A Fokaides
- School of Engineering and Applied Sciences, Frederick University, Cyprus 7., Y. Friderickou Str., 1036 Nicosia, Cyprus.
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