Life Cycle Assessment of waste disposal from olive oil production: Anaerobic digestion and conventional disposal on soil

Recovery of Bioactive Constituents from Olive Leaf Pruning Waste of Five Different Cultivars: A Comparison of Green Extraction Techniques to Maximize Health Benefits

Sustainable agro-waste revaluation is critical to enhance the profitability and environmental footprint of the olive oil industry. Herein, the valorization of olive leaf pruning waste from five cultivars ('Caiazzana', 'Carolea', 'Itrana', 'Leccino', and 'Frantoio') employed green extraction methods to recover compounds with potential health benefits. Sequential ultrasound-assisted maceration (UAM) in n-hexane and ethanol was compared with a compressed fluid extraction strategy consisting of supercritical fluid extraction (SFE) and pressurized liquid extraction (PLE) for their efficiency in recovering distinct classes of bioactives. Chemical profiling by UHPLC-HR-MS/MS (ultra-high-performance liquid chromatography high-resolution tandem mass spectrometry) and GC-MS (gas chromatography mass spectrometry) showed that UAM-EtOH effectively extracted polyphenols (especially luteolin derivatives) and triterpenes (notably maslinic acid), while PLE yielded the highest amount of secoiridoids (e.g., secologanoside). PLE extracts showed better antiradical activities, putatively due to a higher content of flavonoids, secoiridoids, and HCA derivatives than UAM-EtOH ones, as these latter also contained 20-40% (cultivar-dependent) of triterpenes. SFE extracts with a higher concentration of fatty acids and triterpenes showed moderate antioxidant activities but very high AChE inhibition. This study highlights the importance of selecting appropriate extraction methodologies based on the target bioactive compounds and underscores the potential of olive leaf extracts for sustainable bio-products.

Methane production from anaerobic pre-treatment of municipal wastewater combined with olive mill wastewater: A demonstration study

The advanced anaerobic technology (AAT), developed based on an immobilized high-rate anaerobic reactor, was applied as a pretreatment of municipal wastewater (WW) at Karmiel's treatment plant in Israel. The demonstration-scale AAT (21 m3) system was operated at a flow rate of 100 m3day-1 municipal WW mixed with olive mill wastewater (OMW) (0.5 m3day-1) to simulate the scenario of illegal discharge of agro-industrial WW. The AAT provided a stable performance. Specifically, AAT enabled treating high organic loads (9.3 kg m-3day-1) resulting from OMW discharge by shaving the high peaks of organic content and protecting the subsequent activated sludge process. This system enabled the recovery of a significant part of the organic load by anaerobic biodegradation to produce biogas, shown to be highly dependent on temperature and partly on the organic loading rate. The outcomes indicate that the AAT could tolerate an addition of up to 0.5% OMW to municipal WW by removing more than 50% of the total chemical oxygen demand and 18-47% of polyphenols. This work shows that the AAT system has the potential of pretreating municipal WW, increasing the energy efficiency of the plant, and protecting small-medium WWTPs from sudden agro-industrial discharges.

Upcycling olive pomace into pectic elicitors for plant immunity and disease protection

Olive oil production generates substantial quantities of pomace, which are often disposed of in soil, leading to adverse effects on agriculture and the environment. Furthermore, climate change exacerbates plant diseases and promotes the use of toxic phytochemicals in agriculture. However, olive mill wastes can have high potential as reusable and valuable bioresources. Using diluted ethanol, an environmentally friendly solvent, we extracted a fraction containing short and long oligogalacturonides, short arabino-oligosaccharides and polysaccharides. The obtained extract elicited key features of plant innate immunity in Arabidopsis seedlings, including the phosphorylation of mitogen-activated protein kinases MPK3 and MPK6 and the upregulation of defence genes such as CYP81F2, WRKY33, WRKY53, and FRK1. Notably, pretreatment of adult Arabidopsis and tomato plants with the olive pomace extract primed defence responses and enhanced their resistance to the phytopathogens Botrytis cinerea and Pseudomonas syringae. Our results highlight the opportunity to upcycle the two-phase olive pomace collected at the late stage of olive oil campaign, in low-cost and sustainable glycan elicitors, contributing to reducing the use of chemically synthesized pesticides.

Accounting for circular economy principles in Life Cycle Assessments of extra-virgin olive oil supply chains - Findings from a systematic literature review

This study was conceived with the aim of exploring applications of the circular economy (CE) principles in the olive oil sector, with the lens of Life Cycle Assessment (LCA). To that end, the authors performed a systematic literature review (SLR), from a pre-determined set of keywords that were searched for in the two most comprehensive databases of peer-reviewed journals, namely Scopus and Web-of-Science. From the screening process provided by the PRISMA model, a total of fifteen papers were selected that formed the final review sample, most of which included research on production systems in the Mediterranean region. To facilitate a comparative analysis of the findings from those studies, the latter were grouped into clusters, considering their characteristics and methodological approaches. Five articles were classified as dealing with 'closed-loop' systems wherein the resources from the valorisation of by-products were reintegrated into the same production system. The remaining articles were categorised as related to 'open loop' systems since by-products were utilised in processes and systems outside olive oil production. Notably, the 'closed-loop' systems showed the best LCA outcomes. Identified hotspots within the sector included the agricultural and packaging phases. Although comparing LCA applications is challenging due to the inherent nature of the method and researcher autonomy in selecting basic characteristics, valuable best practices emerged from the analysis of the current state of the art. These practices included valorisation of olive pomace (OP) by converting it into biogas to meet the energy needs of the system processes themselves, the collection of waste cooking oil to convert it into biodiesel, and the use of organic farming techniques in olive production. OP oil extraction emerged as a widespread practice enhancing system sustainability. Moreover, increasing industrial symbiosis by promoting proximity amongst plants was documented by this SLR to be a key factor in strengthening system sustainability.

Measuring circular economy in olive oil mills: A review of circularity indicators and tools

Circularity assessment and monitoring have become a core research topic in academic societies, as well as a basis for developing economic development measures. Despite the circular economy (CE) being a game-changer for the agro-food sector, little effort has been made to identify its level of circularity. In order to achieve the transition to a CE, stakeholders and industry professionals must be provided with appropriate indicators, tools and methods. Due to the complexity of CE measurement, it is necessary to devise indicators, methods and tools that are tailored to each industry. The objective of this review article is to identify the indicators and tools required for assessing the level of circularity in olive oil mills. This research collected data regarding available CE indicators at the company and product levels, as well as those applicable to the agro-food industry. As a result, a list of indicators appropriate to the needs of olive mills has been developed that could be used to measure the level of implementation of circular practices in this industry. The main conclusion reached is that once indicators are defined, they should be compared or combined with life cycle assessment methodologies to determine their applicability and effectiveness. There is no doubt that olive oil plays a significant economic, environmental and social role throughout the Mediterranean region. Hence, evaluating the CE is essential to demonstrate the effectiveness of current policies.

Exploitation of Black Olive (Olea europaea L. cv. Piantone di Mogliano) Pomace for the Production of High-Value Bread

In this study, the morpho-textural features, total phenolic content (TPC), and antioxidant capacity (AOC) of bread fortified with olive (Olea europaea L.) pomace were evaluated. Fresh olive pomace was subjected to microbiological and chemical (TPC, AOC, and fiber) analyses; then, the same olive pomace was analyzed during 1 to 6 months of storage at 4 °C or -20 °C. All olive pomace samples were used in 10%, 15%, or 20% amounts to produce type 0 soft wheat (Triticum aestivum) and whole wheat bread samples. The volatile organic compounds (VOCs) in the bread samples were also analyzed to assess the effect of the addition of the olive pomace on the flavor profile of the baked products. The TPC and AOC evaluation of olive pomace showed no differences among the analyzed samples (fresh, refrigerated, or frozen). Regarding the bread containing olive pomace, the specific volume was not affected by the amount or the storage methods of the added pomace. Bread samples produced with soft wheat flour showed the lowest hardness values relative to those produced with whole wheat flour, irrespective of the amount or storage method of the olive pomace. Regarding color, the crust and crumb of the bread samples containing 20% olive pomace were significantly darker. The bread samples containing 20% olive pomace had the highest TPC. The bread samples with fresh olive pomace were characterized by terpenoids, ketones, and aldehydes, whereas the bread samples containing refrigerated olive pomace were characterized by alcohols (mainly ethanol), acids, esters, and acetate. Finally, the bread samples with frozen olive pomace showed a volatile profile similar to that of bread produced with fresh olive pomace. Olive pomace was shown to be a suitable ingredient for producing bread with high nutritional value.

Comparative life cycle assessment of anaerobic digestion, lagoon evaporation, and direct land application of olive mill wastewater

Olive mill wastewater is a prominent waste stream in the Mediterranean countries, with its uncontrolled disposal in water recipients causing significant environmental issues. Anaerobic digestion has been extensively studied for the treatment of various agricultural waste streams. The scope of the present study was the environmental evaluation of the anaerobic digestion of three-phase olive mill wastewater for energy production in an anaerobic bioreactor. Regarding the environmental assessment of the process, the results indicate a lead in the proposed process compared with the baseline scenarios. Moreover, several environmental issues in terrestrial acidification and water eutrophication midpoint categories were exhibited by the digestate utilization. The implementation of the anaerobic digestion method averts an overall environmental damage of 5 mPt per 1000 kg of waste treated. For this reason, the implementation of the proposed method could be a sustainable alternative for wastewater treatment in olive oil production regions, aiming to circular economy.

A Critical Review of Data Science Applications in Resource Recovery and Carbon Capture from Organic Waste

Municipal and agricultural organic waste can be treated to recover energy, nutrients, and carbon through resource recovery and carbon capture (RRCC) technologies such as anaerobic digestion, struvite precipitation, and pyrolysis. Data science could benefit such technologies by improving their efficiency through data-driven process modeling along with reducing environmental and economic burdens via life cycle assessment (LCA) and techno-economic analysis (TEA), respectively. We critically reviewed 616 peer-reviewed articles on the use of data science in RRCC published during 2002-2022. Although applications of machine learning (ML) methods have drastically increased over time for modeling RRCC technologies, the reviewed studies exhibited significant knowledge gaps at various model development stages. In terms of sustainability, an increasing number of studies included LCA with TEA to quantify both environmental and economic impacts of RRCC. Integration of ML methods with LCA and TEA has the potential to cost-effectively investigate the trade-off between efficiency and sustainability of RRCC, although the literature lacked such integration of techniques. Therefore, we propose an integrated data science framework to inform efficient and sustainable RRCC from organic waste based on the review. Overall, the findings from this review can inform practitioners about the effective utilization of various data science methods for real-world implementation of RRCC technologies.

Ultrasound-Assisted Extraction of Polyphenols from Olive Pomace: Scale Up from Laboratory to Pilot Scenario

Power ultrasound application has been proven to intensify the extraction of biocompounds from plant materials. In this work, the ultrasound-assisted extraction (UAE) of polyphenols from olive pomace (OP) has been studied at three different scales: laboratory (batch, 400 W, 0 barg), medium (continuous, 1000 W, 1.0 barg), and pilot (continuous, 2000 W, 1.0 barg) taking into consideration the influence of technological parameters: extraction time (s), solvent to solid ratio (mL/g), mixture pH, and acoustic parameters: amplitude (µm), intensity (W/cm2), and applied energy (Wh). A central composite design was used to optimize the UAE at laboratory scale (0.2 kg). The optimal conditions were: time: 490 s; ratio: 2.1 mL H2O/g OP; pH: 5.6 at an acoustic amplitude of 46 µm for a maximum extraction yield of 3.6 g GAE/L of extract. At medium scale (2.2 kg) the UAE was carried out using amplitudes from 41 to 57 µm. The effect of the pressure (1.0 barg) on the UAE was positive, in terms of higher extraction yield (2.9 g GAE/L) and faster extraction rates compared to the non-pressurized UAE (2.5 g GAE/L), however, the extraction yield was lower than the one observed at laboratory scale. At pilot scale (120 kg), the UAE involved different ultrasound constellations (booster + sonotrode) to deliver the ultrasound energy at different acoustic intensities from 23 to 57 W/cm2. The acoustic intensity (W/cm2) exerts an important effect on the extraction yield, and should be tailored to each process scale. The highest yield obtained at pilot-scale was 3.0 g GAE/L, and it was 58% higher than the one observed in the conventional extraction without ultrasound assistance (stirring and heating). In all tests, regardless of the scale, higher yields were observed between 80 and 85 °C. The application of this technology at the industrial scale to evaluate if the improvement of the extraction caused by the application of ultrasound could is still important when other operations like centrifugation, ultrafiltration, and reverse osmosis are included in the system and to evaluate its techno-economic feasibility.

Circular bioeconomy for olive oil waste and by-product valorisation: Actors' strategies and conditions in the Mediterranean area

The circular economy and bioeconomy can contribute to transitioning towards more sustainable production and consumption in the olive oil sector. This article is the first to analyse multi-actor strategies and multi-level socio-economic conditions for olive oil waste and by-product valorisation in the Mediterranean area using circular bioeconomy principles. Government policies, the strategies of corporations and farmers and consumers' perceptions are discussed, and various methods are applied, such as desk reviews, case studies and quantitative and qualitative surveys. The findings show strong aspirations for improved sustainability in the olive industry. Furthermore, waste and by-product valorisation strategies foster the creation of innovative practices. However, a common regulatory framework, public financial measures, new circular business models using innovative technologies, multi-actor collaboration and increased consumer awareness of the circular economy and new olive oil waste-based products are necessary for more efficient and sustainable use of olive resources. The policy and management recommendations presented in this study may aid in improving and innovating frameworks and practices for better sustainable management of valuable olive resources.

Luminescent Carbon Dots from Wet Olive Pomace: Structural Insights, Photophysical Properties and Cytotoxicity

Carbon nanomaterials endowed with significant luminescence have been synthesized for the first time from an abundant, highly localized waste, the wet pomace (WP), a semi-solid by-product of industrial olive oil production. Synthetic efforts were undertaken to outshine the photoluminescence (PL) of carbon nanoparticles through a systematic search of the best reaction conditions to convert the waste biomass, mainly consisting in holocellulose, lignin and proteins, into carbon dots (CDs) by hydrothermal carbonization processes. Blue-emitting CDs with high fluorescence quantum yields were obtained. Using a comprehensive set of spectroscopic tools (FTIR, Raman, XPS, and ¹H/¹³C NMR) in combination with steady-state and time-resolved fluorescence spectroscopy, a rational depiction of WP-CDs structures and their PL properties was reached. WP-CDs show the up-conversion of PL capabilities and negligible cytotoxicity against two mammalian cell lines (L929 and HeLa). Both properties are excellent indicators for their prospective application in biological imaging, biosensing, and dynamic therapies driven by light.

Producing volatile fatty acids and polyhydroxyalkanoates from foods by-products and waste: A review

Dairy products, extra virgin olive oil, red and white wines are excellent food products, appreciated all around the world. Their productions generate large amounts of by-products which urge for recycling and valorization. Moreover, another abundant waste stream produced in urban context is the Organic Fraction of Municipal Solid Wastes (OFMSW), whose global annual capita production is estimated at 85 kg. The recent environmental policies encourage their exploitation in a biorefinery loop to produce Volatile Fatty Acids (VFAs) and polyhydroxyalkanoates (PHAs). Typically, VFAs yields are high from cheese whey and OFMSW (0.55-0.90 g_{COD_VFAs}/g_COD), lower for Olive Mill and Winery Wastewaters. The VFAs conversion into PHAs can achieve values in the range 0.4-0.5 g_PHA/g_VSS for cheese whey and OFMSW, 0.6-0.7 g_PHA/g_VSS for winery wastewater, and 0.2-0.3 g_PHA/g_VSS for olive mill wastewaters. These conversion yields allowed to estimate a huge potential annual PHAs production of about 260 M tons.

The limitations of bioeconomy LCA studies for understanding the transition to sustainable bioeconomy

Purpose

Transition to bioeconomy requires all actors and stakeholders to measure the impact of systems that use bioresources and technologies to provision society. There are however some challenges with integrating LCA into business development and management, which have important implications for bioeconomy. There have been many LCA studies published in the twenty-first century, but the question must be answered: how useful are these LCA studies to help understand and manage transition to sustainable bioeconomy?

Method

This research used a structured literature review to identify 83 bioeconomy LCA studies published from January 2006 to June 2021 (excluding bioenergy). The studies were analysed for compliance with the ISO 14044 standard, with specific reference to the goal, commissioning perspective, system boundary, function and functional unit, impact methods and categories.

Results and discussions

It was found that more than 85% of the studies reviewed failed to present the required goal statement and a description of the function of the system. Nearly 13% of the studies did not define the system boundary, and only 17% included a full life cycle including raw material extraction, production, use and end-of-life stages. The majority of the LCA studies surveyed from 2006 to 2021 were either (i) not in compliance with the ISO standards or (ii) space and style limitations of the publication process prevented competent practitioners from properly conveying their work. This suggests that the value and integrity of the literature are undermined by not rigorously addressing the first and most important stage of an LCA study.

Conclusion

When interpreting the results, a major shortcoming noted was that most studies did not consider the industrial symbiosis needed between feedstock, technology, primary products, side streams, downstream valorisation and long-term circularity in order to properly understand the transition pathways required. Bioeconomy technologies were imagined as displacers for feedstocks and processes to adapt business as usual, rather than as transformers of the system to a sustainable footing.

Recommendation

If LCA studies are going to provide meaningful information for actors and stakeholders to assess whether a system will be able to operate sustainably, studies should include a full, integrated system, standards should be adhered to and approaches should perhaps go beyond mere eco-efficiency, or doing less harm, as these are not necessarily indicative of sustainability. Historical bioeconomy LCA studies do not provide great insight into the transition to sustainable bioeconomy.

Supplementary information

The online version contains supplementary material available at 10.1007/s11367-022-02053-w.

Bibliometric Mapping of Research on Life Cycle Assessment of Olive Oil Supply Chain

The olive oil supply chain and even its individual stages have been extensively investigated through life cycle assessment (LCA) in recent decades. Most practices of the olive oil supply chain have been associated with negative environmental effects, such as soil degradation, carbon dioxide emissions, air and ground pollution, and depletion of groundwater. The current work aimed to perform a bibliometric analysis, through a science mapping approach, coupled with a review on the life cycle assessment (LCA) studies of the olive oil sector, with relevance to the environmental impacts of agricultural and industrial practices of this food sector. A total of 110 documents published in 2008–2021 were analyzed and discussed. More than 78% of documents were released from 2015. The main Scopus categories relating to the topic analyzed were environmental sciences (25%), energy (18%), and engineering (17%). The most productive countries were Italy, Spain, and Greece. The cluster analysis identified three main research topics related to the “agricultural phase”, “oil extraction”, and “waste management and by-product valorization”. Most of the recent publications focused on the application of LCA to evaluate the environmental impact of innovative agricultural practices, sustainable control of parasites and weeds, wastes, and by-products valorization within a circular economy.

An analysis of design strategies for circular economy through life cycle assessment

The goal of pursuing the circular economy (CE) is spreading more and more in industry, also driven by the introduction of new regulations, considerably affecting product design. However, a quantitative and rigorous evaluation of the environmental impacts of the results obtained by different design strategies used to implementing CE is missing in the literature. Those available only evaluate certain aspects of the life cycle of few products, belonging to specific application fields, in a qualitative way or they refer only to the global warming potential. This study provides a quantitative assessment of the environmental impacts reductions arising from the application of some common design strategies for implementing different CE options (e.g. reuse, waste to energy, remanufacturing), by using some standard indicators. The results were obtained by manually analysing 156 selected case studies of comparative life cycle assessment (LCA), extracted from 136 scientific articles. In them, the environmental impacts of design solutions for CE are compared with those of other solutions were wastes are not exploited. The obtained results have been used to evaluate the different design strategies for CE and to hierarchize them based on environmental sustainability of the solutions associated with them. In addition, an economic evaluation of the strategies, based on the life cycle costing methodology and exploiting the data available in the same articles, was also provided. Among the main achievements, it was found that the hierarchy of the CE options, pursued by the design strategies, to improve environmental sustainability is different from that provided by other studies. In addition, the environmental benefits associated with the different CE options strictly depend by the applied design strategies and the considered products.

A Review on Life Cycle Assessment of the Olive Oil Production

Olive oil is one of the most globally recognized high-value products, with 4 million hectares cultivated in the Mediterranean area. The production process involves many stages: farming, extraction, packing, and waste treatment. Each one of these stages should present critical points for the environmental impacts, and for this reason, the entire sector is adopting mitigation strategies to begin to be more sustainable. The mitigation actions’ efficiency should be evaluated through environmental indicators or environmental impact assessment by Life Cycle Assessment (LCA). This review aimed to carry out an overview of recent papers (2011–2021) involving an LCA study in the olive oil supply chain by giving a framework of what is included in LCA studies and highlighting the main contributors to environmental impacts. The main scholarly literature databases have been exploited, highlighting a great increase in publications, especially from the producer countries. The review results reflect the heterogeneity of the production process. However, the use of pesticides, fertilizers, water, and fuel for machinery heavily weigh on the farming stage’s environmental impact. Finally, special focus was given to key elements of LCA studies in the olive oil supply chain, such as functional unit, system boundaries, impact categories, calculation method, and software widely used.

Alternative seagrass wrack management practices in the circular bioeconomy framework: A life cycle assessment approach

Despite providing important ecological functions, seagrass accumulation causes environmental and economic issues, including eutrophication and tourism reduction. Nowadays, seagrass wrack is commonly removed from the beaches and landfilled, which is considered the least desirable practice according to the European Union (EU) Waste Framework Directive. In this study, different management strategies for seagrass valorisation, including anaerobic digestion (AD), composting and ecological restoration, were considered using a life cycle assessment (LCA) perspective. The aim of the work was to evaluate more ecological and economic alternatives to landfill and to provide a robust evaluation method for public and private companies. An economic assessment was subsequently conducted, considering both direct and indirect impacts with a life cycle costing (LCC) approach. A selected beach located in the Northeast Mediterranean Sea was considered as a relevant case-study. The environmental impacts of the seagrass management scenarios were evaluated with the method ReCiPe 2016H, using both midpoint and endpoint levels. LCA results showed that ecological restoration and AD were the best alternatives in terms of environmental performances because of biogas production used as a renewable energy source. The impacts of the alternative management strategies were significantly lower than the current landfill strategy, -70% considering the categories of human health, ecosystems and resources, and -95% considering global warming potential category. The LCC analysis proved that composting was the best alternative (NPV > 1.27 M€), due to lower operating costs and higher fertilizer value. The obtained results can help beach management companies and public administrations to select the best operational strategies to reduce the environmental and economic impact of seagrass collection and treatment.

Life cycle assessment applied to waste management in Italy: A mini-review of characteristics and methodological perspectives for local assessment

Life cycle assessment (LCA) and related tools are commonly used to evaluate the potential environmental impacts of waste treatment scenarios. This manuscript presents a mini-review of studies published over the last 10 years in Italy and aims to investigate how life cycle thinking tools are applied to assess the environmental sustainability of local-level waste policies. Results reveal that different waste flows, technologies and policies have been investigated independently and in varying detail. Review suggests that boundary selection significantly affects LCA results; integration of different waste systems is therefore crucial to avoid spatial or temporal shifts of environmental impacts. Moreover, the description of methodological characteristics, limitations and transversal aspects of Italian waste management studies allows various stakeholders to assess the reliability of past and future research for waste policy planning and rebound effects prevention. This review also highlights the need to define minimum requirements of transparency and ease of reporting of the studies to private and public stakeholders. Finally, the paper investigates whether using both the organisational LCA and the life cycle sustainability approach for the overall waste management process may be useful to develop a standard method to address multi-functionalities and multiple sites.

Agri-Food Contexts in Mediterranean Regions: Contributions to Better Resources Management

The agri-food frameworks have specific characteristics (production units with small dimensions and in great number with implications in the respective markets) that call for adjusted approaches, even more so when they are considered in Mediterranean contexts (where global warming will have relevant impacts). In fact, the Mediterranean regions and countries have particular specificities (due to their climate conditions) that distinguish them from their neighbours. This is particularly true in Europe, for example, where the southern countries present socioeconomic dynamics (associated with the respective public debt) that are different from those identified in the northern regions. From this perspective, it seems pertinent to analyse the several dimensions of the agri-food systems in the Mediterranean area. To achieve these objectives, a search was carried out on 26 December 2020 on the scientific databases Web of Science Core Collection (WoS) and Scopus for the topics “agr*-food” and “Mediterranean”. These keywords were selected after a previous literature survey and to capture the agri-food contexts in Mediterranean regions. The keyword “agr*-food” was considered in this way to allow for a wider search (including “agri-food”, “agro-food”, etc.). Considering only articles (excluding proceeding papers, book chapters, and books, because in some cases it is difficult to access the entire content of the document), 100 and 117 documents were obtained from the WoS and Scopus, respectively. After removing the duplicated studies and taking into account the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) approach, 137 documents were surveyed through a literature review. As main insights, several dimensions embedded in the concept of agri-food were highlighted, from those related to heritage subjects to natural assets. On the other hand, the following subtopics were identified: agri-food dynamics and sustainability, agriculture and agri-food systems, agri-chains and food consumption, and food production and composition impact on agri-chains. Stressing the gaps in the scientific literature, related to the topics here addressed, there are possibilities to better explore the several dimensions and solutions offered by the new developments associated with smart agriculture and agriculture 4.0, specifically for the Mediterranean contexts and their challenges. Finally, to complement the PRISMA methodologies, an MB2MBA2 (Methodology Based on Benchmarking of Metadata, from scientific databases, and Bibliometric Assessment and Analysis) approach is suggested to carry out systematic literature reviews, based on bibliometric analysis.

Increasing the Content of Olive Mill Wastewater in Biogas Reactors for a Sustainable Recovery: Methane Productivity and Life Cycle Analyses of the Process

Anaerobic codigestion of olive mill wastewater for renewable energy production constitutes a promising process to overcome management and environmental issues due to their conventional disposal. The present study aims at assessing biogas and biomethane production from olive mill wastewater by performing biochemical methane potential tests. Hence, mixtures containing 0% (blank), 20% and 30% olive mill wastewater, in volume, were experimented on under mesophilic conditions. In addition, life cycle assessment and life cycle costing were performed for sustainability analysis. Particularly, life cycle assessment allowed assessing the potential environmental impact resulting from the tested process, while life cycle costing in conjunction with specific economic indicators allowed performing the economic feasibility analysis. The research highlighted reliable outcomes: higher amounts of biogas (80.22 ± 24.49 NL.kg_SV⁻¹) and methane (47.68 ± 17.55 NL.kg_SV⁻¹) were obtained when implementing a higher amount of olive mill wastewater (30%) (v/v) in the batch reactors. According to life cycle assessment, the biogas ecoprofile was better when using 20% (v/v) olive mill wastewater. Similarly, the economic results demonstrated the profitability of the process, with better performances when using 20% (v/v) olive mill wastewater. These findings confirm the advantages from using farm and food industry by-products for the production of renewable energy as well as organic fertilizers, which could be used in situ to enhance farm sustainability.

Environmental Impact of Food Preparations Enriched with Phenolic Extracts from Olive Oil Mill Waste

Reducing food waste as well as converting waste products into second-life products are global challenges to promote the circular economy business model. In this context, the aim of this study is to quantify the environmental impact of lab-scale food preparations enriched with phenolic extracts from olive oil mill waste, i.e., wastewater and olive leaves. Technological (oxidation induction time) and nutritional (total phenols content) parameters were considered to assess the environmental performance based on benefits deriving by adding the extracts in vegan mayonnaise, salad dressing, biscuits, and gluten-free breadsticks. Phenolic extraction, encapsulation, and addiction to the four food preparations were analyzed, and the input and output processes were identified in order to apply the life cycle assessment to quantify the potential environmental impact of the system analyzed. Extraction and encapsulation processes characterized by low production yields, energy-intensive and complex operations, and the partial use of chemical reagents have a non-negligible environmental impact contribution on the food preparation, ranging from 0.71% to 73.51%. Considering technological and nutritional aspects, the extraction/encapsulation process contributions tend to cancel out. Impacts could be reduced approaching to a scale-up process.

Life Cycle Assessment of Olive Pomace as a Reinforcement in Polypropylene and Polyethylene Biocomposite Materials: A New Perspective for the Valorization of This Agricultural By-Product

The main environmental impact of olive oil production is the disposal of residues such as pomace and water vegetation. During the olive oil extraction process, the olive stone is milled and discharged within the olive pomace. However, olive stone flour can be valorized as filler for polymeric composites. A life cycle assessment of the olive pomace valorization was carried out by focusing on the manufacturing process of a biocomposite made of two different thermoplastic matrices, i.e., polyethylene and polypropylene. The functional unit is the production of 1 m2 of a lath made of an olive pomace-based biocomposite. The analysis was carried out with the SimaPro PhD 9.1.1.1 software, and the database used for the modeling was Ecoinvent 3.6. The obtained results reveal that the hotspot of the whole process is the twin-screw compounding of the olive stone fraction, with the polymeric matrix and coupling agent, and that human health is the most affected damage category. It represents 89% for both scenarios studied: olive stone fraction/polypropylene (OSF/PP) and olive stone fraction/polyethylene (OSF/PE). Further research directions include the use of biosourced polymer matrices, which could reduce the impact of olive pomace-based composite manufacturing.

Oleaginous Yeasts as Cell Factories for the Sustainable Production of Microbial Lipids by the Valorization of Agri-Food Wastes

The agri-food industry annually produces huge amounts of crops residues and wastes, the suitable management of these products is important to increase the sustainability of agro-industrial production by optimizing the entire value chain. This is also in line with the driving principles of the circular economy, according to which residues can become feedstocks for novel processes. Oleaginous yeasts represent a versatile tool to produce biobased chemicals and intermediates. They are flexible microbial factories able to grow on different side-stream carbon sources such as those deriving from agri-food wastes, and this characteristic makes them excellent candidates for integrated biorefinery processes through the production of microbial lipids, known as single cell oils (SCOs), for different applications. This review aims to present an extensive overview of research progress on the production and use of oleaginous yeasts and present discussions on the current bottlenecks and perspectives of their exploitation in different sectors, such as foods, biofuels and fine chemicals.

Low-cost anaerobic digester to promote the circular bioeconomy in the non-centrifugal cane sugar sector: A life cycle assessment

This study aimed to assess the potential environmental benefits of implementing low-cost digesters to valorize agro-industrial waste in the non-centrifugal cane sugar (NCS) sector. Two scenarios were considered: i) the current scenario in which organic waste and wastewater were burned outdoor and discharged into a water body, respectively; ii) the anaerobic digestion (AD) scenario, in which low-cost biodigesters were used for organic waste and wastewater treatment on-site. Results showed that low-cost digesters were a sustainable alternative to mitigate environmental impacts, especially those associated with water source pollution. Indeed, in the AD scenario, the environmental impact categories of Freshwater Eutrophication and Marine Eutrophication showed a decrease of 87.6% and 99.4%, respectively, compared to the current scenario. Thus, by treating organic waste and wastewater on-site while producing bioproducts (i.e. biofuel and biofertilizer), low-cost digesters could contribute to boosting the circular bioeconomy in the NCS production sector.

Measuring Circularity in Food Supply Chain Using Life Cycle Assessment; Refining Oil from Olive Kernel

Valorization of food waste is a potential strategy toward a circular food supply chain. In this regard, measuring the circularity of food waste valorization systems is highly important to better understand multiple environmental impacts. Therefore, this study investigated the circularity of a food waste valorization system (refining oil from olive kernel) using a life cycle assessment methodology. An inventory of an industrial-based olive kernel oil production system is also provided in this study. The system boundary was the cradle to the factory gate of the production system. The results indicated that natural gas consumption was the highest contributor to most of the investigated impact categories. The global warming potential of one kg of oil produced from olive kernel was calculated to be 1.37 kg CO₂eq. Moreover, the calculated damages of 1 kg oil production from olive kernel to human health, ecosystem quality, and resource depletion were 5.29 × 10⁻⁷ DALY, 0.12 PDF∙m²∙yr., and 24.40 MJ, respectively.

Application of olive mill waste-based biochars in agriculture: Impact on soil properties, enzymatic activities and tomato growth

The olive oil industry is an important economic sector in Mediterranean countries. However, oil production is unfortunately accompanied by the generation of huge amounts of olive mill solid wastes (OMSW) and olive mill wastewater (OMWW). In the present study, a strategy is proposed for converting these olive mill wastes into biochar through pyrolysis, for their later use as an organic amendment in agriculture. Specifically, two biochars were prepared from the pyrolysis of OMSW at 500 °C, either alone or impregnated with OMWW (OMSW-B and I-OMSW-B). The characterization of the OMSW and I-OMSW samples and their derived biochars showed that the fixed carbon and ash contents in the feedstocks increased by 38% and 11% respectively for OMSW-B, and by 37% and 12% respectively for I-OMSW-B. Interestingly, the impregnation process significantly increased Na, P, K, Ca and Fe contents in the produced biochars. The effect of OMSW-B and I-OMSW-B amendments at different application dose (1%, 2.5% and 5% wt/wt) on the enzymatic activity of an agricultural soil was performed at laboratory scale with a pot test. The experimental results showed that phosphatase and urease activity increased with biochar application rate; amendment with I-OMSW-B at 1%, 2.5% and 5% enhanced the phosphatase activity by 63%, 142% and 285% and urease activity by 50%, 116% and 149%, respectively. On the other hand, dehydrogenase and protease activities were higher for the application rate of 2.5% biochar. Biochar amendment promoted tomatoes seedling growth after 10 weeks, which was highest in the application rates of 2.5% and 5% for both OMSW-B and I-OSMW-B. Thus, the produced biochars had great potential to be used as biofertilizers in agriculture.