Biowaste Valorization Research Articles

Innovative Circular Biowaste Valorisation—State of the Art and Guidance for Cities and Regions

The management of the organic fraction of municipal solid waste (OFMSW), also called urban biowaste, and urban wastewater sludge (UWWS) represents a challenge for cities and regions, which want to adopt innovative urban bioeconomy approaches for their treatment and production of high-added-value products beyond the traditional anaerobic digestion (AD) and compost. This adoption is often restricted by the availability and maturity of technologies. The research object of this manuscript, based on the findings of EU Horizon 2020 project HOOP, is the identification of state-of-the-art circular technologies for material valorisation of OFMSW and UWWS, following a novel screening methodology based on the scale of implementation (tested at least at pilot scale). The screening resulted in 25 technologies, which have been compared and discussed under a multidisciplinary assessment approach, showing their enabling factors and challenges, their current or potential commercial status and their compatibility with the traditional technologies for urban biowaste treatment (composting and AD). The bioproducts cover market sectors such as agriculture, chemistry, nutrition, bioplastics, materials or cosmetics. Therefore, the results of this review help project promoters at city/region level to select innovative technologies for the conversion of OFMWS and UWWS into high value products.

Bio-waste valorization to formulate an eco-friendly reduced graphene oxide based bio-gel for clinical applications

Bio-waste valorization to formulate an eco-friendly reduced graphene oxide based bio-gel for clinical applications

Experimental and feasibility study of bio-waste valorization through pyrolysis for energy and materials production in the concept of circular economy

The pyrolysis and co-pyrolysis characteristics of large abundant bio-wastes, namely date pits (DP), peanut shells (PS), coffee grounds (CG), and tea waste (TW) were investigated in detail. The TG/DTG and pyrolysis procedures were used to examine the thermal pyrolysis behavior of these agro-wastes and their blends (50%CG/50%DP, 50%CG/50%PS, 50%DP/50%PS, 50%TW/50% DP,50%TW/50%PS and 50%CG/50% TW by weight). The characterization of these feedstock has shown their suitability for energy and material valorization. Experiments were carried out in a batch pyrolysis at a medium heating rate of 10 °C/min. The goal was to identify the best combination aiming to produce either char or hydrogen-rich gas, which can contribute to the development of the circular bio-economy. It was demonstrated that pyrolysis favored the liquid product, fluctuating from 34.31% (TW) to 50.92% (DP), while the co-pyrolysis greatly increased the gaseous product, which ranged between 42.02% (TW-DP) and 55.17% (PS-TW). The blending of CG and PS resulted in heightened reactivity, leading to an enhanced generation of H2 (34.44%). The optimal mixture was found to be CG-TW, showcasing superior performance in terms of gas quality (38.39% H2) and yield (53.74%). This outcome underscores the potential of CG and TW as a synergistic blend for efficient hydrogen-rich gas production. The FTIR findings revealed that the recovered biochars have the potential to serve as solid fuels, biofertilizers, or carbon materials. Additionally, they could be used as eco-friendly precursors for chemical and related industries. By analyzing various waste mixtures and their respective pyrolysis properties, this research aims to contribute to the development of sustainable waste management practices as well as efficient energy and material production methods.

To what extent do geopolitical conditions affect the environmental sustainability of the circular economy? A comparative LCA study of lactic acid production in Denmark and Iran

Transitioning to a circular economy is inevitable in well-developed and developing economies. Biowaste valorization into value-added products has shown a promising sustainable solution compared to its fossil-based counterparts. However, it has yet to be scientifically analyzed to what extent geopolitical conditions affect the environmental sustainability of the circular economy. To fill this gap, we conducted a consequential life cycle assessment of biorefining biowaste into lactic acid and bioenergy in Denmark and Iran as representative examples of developed and developing economies, respectively. Despite the notable environmental impacts associated with fossil-based energy consumption and infrastructural limitations, Iran could benefit more environmentally from the suggested biorefinery by 2030 than Denmark. This contrast arises from the fact that the existing dominant waste management solution in Iran consists of sanitized and unsanitized landfills, which appear likely to continue through 2030. Therefore, any alternative waste management scenario would help avoid the environmental impacts arising from landfills. In contrast, Denmark already has a well-established and sustainable waste management practice for biowaste, namely anaerobic digestion. Accordingly, the environmental impacts of the investigated scenarios in Denmark were, on average, 85 %, 855 %, 177 %, and 130 % higher than those in Iran regarding resource scarcity, ecosystem quality, human health, and climate change, respectively. In both countries, incineration, the culture medium, ion exchange, vacuum distillation, transportation, emissions from digestate applications on farmlands, and the inorganic waste landfilling process (only applied to IR scenarios) contributed most to the overall environmental impacts. Besides impacts arising from geopolitical conditions, our study revealed that abiotic augmentation and P. acidilactici bioaugmentation demonstrated superior environmental performance compared to other methods. The results also highlight the importance of international collaboration to implement circular economy approaches in developing countries and accelerating global environmental mitigation efforts. To comprehensively evaluate the environmental sustainability of circular bioeconomy, it is recommended to examine scenarios aligned with socio-economic pathways and various representative concentration pathways.

Understanding the interactions between biowaste valorisation and the Sustainable Development Goals: insights from an early transition stage

ABSTRACT The valorisation of urban biowaste can contribute to a circular and sustainable resource management. However, biowaste valorisation is not inherently sustainable. This study employs the Sustainable Development Goals (SDGs) to investigate the sustainability implications of biowaste valorisation. A narrative literature review provided an overview of the current scientific knowledge on interactions between biowaste valorisation and selected SDG targets. Then stakeholder interviews yielded insights into such interactions in a national context. Our findings show the potential for 19 synergies and 11 trade-offs between biowaste valorisation and 20 selected SDG targets that are addressed in detail. Although the synergies outnumber the trade-offs, different context-dependencies influence the nature and strength of the interactions. We highlight three types of context-dependencies relating to governance. This study informs the scientific community and decision-makers on planning for sustainable biowaste valorisation that addresses context-dependencies. The insights can guide countries and cities at early transition stages towards biowaste valorisation.

Exploring biorefinery alternatives for biowaste valorization: a techno-economic assessment of enzymatic hydrolysis coupled with anaerobic digestion or solid-state fermentation for high-value bioproducts

ABSTRACT Enzymatic hydrolysis of organic waste is gaining relevance as a complementary technology to conventional biological treatments. Moreover, biorefineries are emerging as a sustainable scenario to integrate waste valorization and high-value bioproducts production. However, their application on municipal solid waste is still limited. This study systematically evaluates the techno-economic feasibility of the conversion of the organic fraction of municipal solid waste (OFMSW) into high-value bioproducts through enzymatic hydrolysis. Two key variables are examined: (a) the source of the enzymes: commercial or on-site produced using OFMSW, and (b) the treatment of the solid hydrolyzate fraction: solid-state fermentation (SSF) for the production of biopesticides or anaerobic digestion for the production of energy. As a result, four different biorefinery scenarios are generated and compared in terms of profitability. Results showed that the most profitable scenario was to produce enzymes on-site and valorize the solid fraction via SSF, with an internal rate of return of 13%. This scenario led to higher profit margins (74%) and a reduced payback time (6 years), in contrast with commercial enzymes that led to an unprofitable biorefinery. Also, the simultaneous production of higher-value bioproducts and energy reduced the economic dependence of OFMSW treatment on policy instruments while remaining energetically self-sufficient. The profitability of the biorefinery scenarios evaluated was heavily dependent on the enzyme price and the efficiency of the anaerobic digestion process, highlighting the importance of cost-efficient enzyme production alternatives and high-quality OFMSW. This paper contributes to understanding the potential role of enzymes in future OFMSW biorefineries and offers economical insights on different configurations.

Multifunctional Pomegranate Peel Microparticles with Health-Promoting Effects for the Sustainable Development of Novel Nutraceuticals and Pharmaceuticals.

Recovering the bioactive components from pomegranate peel (PP) in the fruit-processing industry has attracted great attention in terms of minimizing the waste burden, as well as providing a new source of a multitude of functional compounds. The present study aimed to develop a feasible microencapsulation process of PP extract by using pectin and a pectin/2-hydroxypropyl-β-cyclodextrin (HP-β-CD) blend as coating materials. Microsized powders obtained by a spray drying technique were examined in terms of technological characteristics, exhibiting high powder yield and desirable moisture content, flowability, and cohesive properties. Assuming that the interactions with the used biopolymers occur on the surface hydrophobic domain, their presence significantly improved the thermal stability of the microencapsulated powders up to 200 °C. The health-promoting effects of PP have been associated with its high content in ellagitannins, particularly punicalagin. The obtained PP powders exhibited strong antioxidant and hypoglycemic potential, while an antimicrobial assay revealed their potent activity against Gram-positive bacteria. Additionally, an in vitro release study suggested that the used biopolymers can modify the release of target bioactive compounds, thus establishing a basis for developing an oral-controlled release system. Altogether, biowaste valorization from PP by the production of effective multifunctional microsized powders represents a sustainable way to obtain novel nutraceuticals and/or pharmaceuticals.

Optimizing continuous medium-chain fatty acid production from biohydrogenic palm oil mill effluent: Operational parameters and microbial dynamics

Palm oil mill effluent (POME) was dark fermented into biohydrogen for clean energy production with volatile fatty acids (VFAs) as a byproduct. The VFAs remaining 70% in hydrogenic POME offer potential substrate for conversion into valuable medium-chain fatty acids (MCFA), presenting an opportunity for resource recovery and environmental mitigation. This study investigated the influence of varying operating parameters on continuous MCFA production from biohydrogenic POME through a stirred tank reactor. Optimizing MCFA production necessitates a 5.4 g/L ethanol load supplemented with 2.6 g/L NaHCO3 and 1.5 L-CO2/L/d while maintaining a pH of 6.5 and a temperature of 35 °C. Under optimized conditions, a maximum MCFA production of 2.2 g-COD/L was achieved, consisting primarily of 1.8 g-COD/L caproic acid, 0.2 g-COD/L heptanoic acid, and 0.2 g-COD/L caprylic acid, translating to a total MCFA yield of 0.5 g-COD/g-COD and MCFA selectivity of 51% with Caproiciproducens sp. (45%), Lactobacillus sp. (21%), and Clostridium sp. (14%) as predominant bacteria. Notably, CO2 loading significantly enhances MCFA production, particularly caproic and heptanoic acids. Remarkably, the system maintained stable MCFA production for an impressive 220 days. The microbial community in the reactor effectively removed total solids, volatile solids, chemical oxygen demand (COD), suspended solids of 42%, 61%, 31%, and 95%, respectively. Key bacteria like Caproiciproducens sp., C. kluyveri, Clostridium sp., and Sporanaerobacter sp. possess most of the enzymes required for the reverse β-oxidation pathway, an energy-efficient pathway for MCFA generation. This study makes a significant contribution to the field of biowaste valorization, specifically focusing on anaerobic fermentation for bio-based chemical production. Despite challenges related to butyric acid accumulation and inhibition, these findings offer promising potential for scaling up the fermentation process.

Transforming oyster shell and rice husk biowaste into functional calcium silicate board with highly-efficient photo-enhanced antimicrobial activities

Green construction materials based on biomass waste are attracting tremendous research attention in recent years as a means to satisfy the low-cost and sustainable construction requirements in the modern building industry. In this work, the use of oyster shell and rice husk biowaste as raw materials for the environment-friendly preparation of calcium silicate boards is presented. To endow the calcium silicate boards with an antimicrobial functionality, CuSe/CaCO3 is incorporated. The antimicrobial effect is credited to the presence of CuSe nanoparticles, which are capable of inhibiting microbial growth through light-induced generation of radicals, release of copper ions, and photothermal heating. The fabrication process of the antimicrobial calcium silicate boards is optimized by studying the effect of different loading amounts and processing conditions. It was determined that the calcium silicate board that exhibits the most satisfying flexural strength and antimicrobial efficacy can be prepared using the following parameters: Ca/Si ratio of 0.83, molding pressure of 30 MPa, curing temperature of 180 ℃, curing time of 10 h, and 10 wt% of CuSe/CaCO3. Our work might shed light on the sustainable preparation of functional calcium silicate boards through valorization of biowaste. The utilization of biowaste as building materials can significantly aid in mitigating environmental pollution and in lowering the overall cost of construction.

Organic and Biogenic Nanocarriers as Bio-Friendly Systems for Bioactive Compounds' Delivery: State-of-the Art and Challenges.

"Green" strategies to build up novel organic nanocarriers with bioperformance are modern trends in nanotechnology. In this way, the valorization of bio-wastes and the use of living systems to develop multifunctional organic and biogenic nanocarriers (OBNs) have revolutionized the nanotechnological and biomedical fields. This paper is a comprehensive review related to OBNs for bioactives' delivery, providing an overview of the reports on the past two decades. In the first part, several classes of bioactive compounds and their therapeutic role are briefly presented. A broad section is dedicated to the main categories of organic and biogenic nanocarriers. The major challenges regarding the eco-design and the fate of OBNs are suggested to overcome some toxicity-related drawbacks. Future directions and opportunities, and finding "green" solutions for solving the problems related to nanocarriers, are outlined in the final of this paper. We believe that through this review, we will capture the attention of the readers and will open new perspectives for new solutions/ideas for the discovery of more efficient and "green" ways in developing novel bioperformant nanocarriers for transporting bioactive agents.

Biowaste valorization on pharmaceuticals and pesticides abatement in aqueous environments

This study focuses on the abatement of pharmaceuticals and pesticides in water using sustainable biosorbents. Adsorption kinetics and equilibrium measurements were performed to characterize the adsorption of fluoxetine hydrochloride (FLX), carbamazepine (CRB) and atrazine (ATZ) by raw pine bark. The amount of adsorbed pollutants by mass of adsorbent followed the order: FLX (0.652 mg/g) > ATZ (0.522 mg/g) > CRB (0.144 mg/g), explained by the different interactions between the untreated pine surface and the target pollutants, according to the adsorption mechanism proposed. The evaluation of chemically and thermically modified pine was also assessed. In terms of the overall entrapment capability, pine bark modified with HNO3 was shown to be the best biosorbent (1.95 mg/g). The economic feasibility of the biosorbents was evaluated through a detailed cost analysis. Among the performed modifications, the one with H2O2 was the most expensive procedure, 23.7 €/mmol (pollutants mixture) being the hydrochar production the less expensive, 1.1 €/mmol. Through desorption assays it was found that 100% of FLX, 98% of CRB and 30% of ATZ, respectively, can be recovered from raw pine, using 50% (v/v) acetonitrile solution. The recyclability of the natural biosorbent was evaluated by adsorption-desorption cycles. Pine bark can be regenerated and reused at least for two times, without losing its adsorption efficiency. A pre-pilot air-lift type reactor was investigated as an effective rehabilitation approach to treat contaminated water, for up-scale purpose. Using biowastes for emerging pollutants entrapment can be considered a sustainable water rehabilitation pathway, promoting a circular bioeconomy and environmental protection.

Dual valorization of coastal biowastes for tetracycline remediation and biomethane production: A composite assisted anaerobic digestion

Harnessing coastal biowaste for dual valorization in water treatment and biofuel production holds paramount importance for sustainability and resource challenges. This study investigated the potential of engineered composite (CABC) derived from coastal biowaste-based materials for tetracycline (TC) removal and biomethane production. High-yield calcium carbonate (CaCO3; 95.65%; bivalve shells) and biochar (GA-BC; 41.50%; green macroalgae) were produced and used as precursors for CABC. The characterization results revealed presence of β-CaCO3 and ν2-CO3 aragonite in CaCO3, and composite homogeneity was achieved. The CABC exhibited a maximum TC sorption capacity of 342.26 mg/g via synergistic sorption mechanisms (i.e., surface/pore filling, electrostatic attraction, calcium ion exchange, and chelation). Supplementation of anaerobic digestion process with GA-BC, CaCO3, and CABC was investigated via three consecutive cycles. Biochemical methane potential of glucose as a sole substrate was increased from 157.50 to 217.00, 187.00, and 259.00 mL-CH4, while dual substrate (glucose+TC) treatment was increased from 94.5 to 146.5, 129.0, and 153.00 mL-CH4 for GA-BC, CaCO3, and CABC, respectively. Moreover, system stability and TC removal were increased with the addition of GA-BC (40.90%), CaCO3 (16.30%), and CABC (53.70%). Therefore, this study exemplifies the circular bioeconomy approach, demonstrating the sustainable use of biowaste-derived composite for water treatment and biofuel production.

Valorization of Biowaste for Nanocomposite Synthesis and Its Application for the Environmental Remediation of Bisphenol A: Optimization, Model Evaluation and Docking Studies

Valorization of Biowaste for Nanocomposite Synthesis and Its Application for the Environmental Remediation of Bisphenol A: Optimization, Model Evaluation and Docking Studies

Polyphenol Composition by HPLC-DAD-(ESI-)MS/MS and Bioactivities of Extracts from Grape Agri-Food Wastes.

Grape agri-food wastes, such as skin, seeds, and other discarded by-products, contain phytochemical compounds that offer potential health benefits. This study aimed to investigate the polyphenol composition and bioactivities of different extracts obtained from grape marc and seeds, with the goal of exploring their potential for application as natural food additives. Regardless of the extraction method used (dynamic maceration, ultrasound-assisted extraction (UAE), and microwave-assisted extraction (MAE)), all extracts exhibited relatively high concentrations of phenolic compounds. The chemical characterization of the extracts revealed the presence of specific compounds and chemical groups associated with each extraction methodology. Moreover, the extracts displayed satisfactory antioxidant activities, especially in inhibiting lipoperoxidation as assessed by the TBARS assay. Additionally, the extracts demonstrated effective inhibition against different strains of bacteria and fungi known as food contaminants. Taken together, these findings indicate that those extracts have the potential to be tested as natural antioxidants and preservatives with sustainable origins in food and beverage systems. Among the extraction methods evaluated, traditional maceration and UAE provided extracts with the highest antioxidant and antimicrobial activities. Our results suggest the opportunity to explore grape marc and seeds discarded by the winery industry in Portugal as natural sources of bioactive compounds, which could be employed as functional food ingredients or technological additives. The valorization of grape biowastes offers a promising strategy to reduce waste and harness their potential health benefits.

Biowaste Valorization Based ZnO Nanoparticles as Vital Component for Multifaceted Applications: A Green Approach

Biowaste Valorization Based ZnO Nanoparticles as Vital Component for Multifaceted Applications: A Green Approach

Boosting Biowaste Valorisation—Do We Need an Accelerated Regional Implementation of the European Law for End-of-Waste?

The valorisation of municipal and household biowaste as a relevant component of the EU’s Circular Economy Strategy is currently under discussion. However, there are several legal, technical and economic challenges associated with biowaste valorisation. This paper aims to pinpoint factors affecting biowaste supply chains using the PESTEL+I method and stakeholder workshops. Our analysis focuses on the macro-environment of an integrated biowaste conversion and valorisation concept in the region of Wallonia, Belgium. One key influencing factor is the EU’s legal framework on waste, which describes the end-of-waste status and defines criteria for biowaste reuse. While the analysis shows that EU regulations support biowaste valorisation, its transposition into national and regional law is lagging behind. The technological development of biowaste concepts might be hampered and many questions related to the marketisation of bio-based products remain unanswered. We therefore suggest that legal procedures for biowaste management have to be facilitated at the regional level. The region of Wallonia should establish a category for biowaste that would include standardized procedures for biowaste valorisation and products. It is essential that such regional barriers be overcome to establish the necessary cooperation with local stakeholders and to transfer biowaste supply chains to the market.

Biowaste valorization into valuable nanomaterials: Synthesis of green carbon nanodots and anode material for lithium-ion batteries from watermelon seeds

In this study, a solid biowaste watermelon seed is introduced for the first time as an alternative precursor for the production of fluorescent carbon nanodots and nanostructured activated carbon. Firstly, the seeds are carburized and then activated by using KOH after the ball milling process. The activated carbon is used as anode material in lithium-ion batteries and exhibits ∼360 mAh g − 1 capacity after the 200th cycle, with a coulombic efficiency of 98%. Additionally, carbon dots are fabricated by hydrothermally treating carburized seeds at different conditions. The obtained carbon dots show a remarkable fluorescence effect at 458 nm (when excited at 365 nm) and have the potential to be used in biomedical applications. The results show that by means of proper material selection and process design, low carbon footprint nanomaterials suitable for use in various applications can be synthesized successfully from organic wastes.

Circular economy in the valorisation of food and other biowaste: case studies in small and medium-sized enterprises in the Belgian construction sector.

The construction sector has significant impacts on the environment due to the consumption of resources and the production of waste. The implementation of circular economy strategies can improve the environmental performance of the sector, optimising the current production and consumption patterns, slowing and closing material loops, and using waste as a source of raw materials. Biowaste represents a key waste flow at the European scale. However, research on its application in the construction sector is still limited and product-oriented, with little insights into the processes of valorisation undertaken at the company's level. This study presents eleven case studies of Belgian small and medium-sized enterprises involved in biowaste valorisation in the construction sector in order to tackle this research gap in the Belgian context. Semi-structured interviews were conducted to identify the enterprise's business profile and its current marketing practices, as well as to analyse opportunities and barriers for market expansion and highlight current research interests. Results show that the overall picture is extremely heterogeneous in terms of sourcing, production methods, and products, while the barriers and success factors that have been identified are recurrent. This study contributes to the circular economy research in the construction sector by providing insights into innovative waste-based materials and business models.

Promoting Sustainable Fruit and Vegetable Biowaste Management and Industrial Symbiosis through an Innovative Web Platform

Sustainable bioeconomy is a promising pathway towards the transition to a circular and climate-neutral economy. The valorization of biowaste is a key player in this direction. This paper presents the design and development of the AgriPLaCE Platform, which aims to promote synergies that enable the utilization of biowaste from the fruit and vegetable supply chain. The platform consists of the AgriPLaCE Waste Management Database, which provides users with an extended list of potential utilization methods for various types of fruit and vegetable biowaste streams, and the AgriPLaCE Synergies Tool, which facilitates synergies between different actors involved in the biowaste-to-resource value chain from agricultural waste production to waste treatment and new valuable products’ exploitation. Initially, the conceptual design of both tools took place based on analysis of user needs and services alongside the system architecture. Following this, the AgriPLaCE Platform was developed with the implementation of all the necessary subsystems. The results of the platform’s implementation demonstrated its potential to generate multiple collaborations and synergies while users can also deepen their knowledge about alternative and emerging treatment technologies and valuable products from a wide range of fruit and vegetable biowaste streams.

New Trends in Supercritical Fluid Technology and Pressurized Liquids for the Extraction and Recovery of Bioactive Compounds from Agro-Industrial and Marine Food Waste.

Growing consumer interest in healthy foods has led to an increased demand for bioactive compounds derived from eco-technologies. This review highlighted two emerging technologies, pressurized liquid extraction (PLE) and supercritical fluid extraction (SFE), which are based on clean processes aimed at recovering bioactive compounds from different food sources. We studied how the different processing conditions provide many advantages and a great opportunity to obtain compounds with antioxidant, antibacterial, antiviral, or antifungal activity from plant matrices and industrial biowaste, especially antioxidant compounds (anthocyanins and polyphenols) due to their important role in health promotion. Our research was conducted through a systematic search in different scientific databases related to the PLE and SFE topics. The review analyzed the optimal extraction conditions using these technologies, which lead to the efficient extraction of bioactive compounds, the use of different equipment, and recent combinations of SFE and PLE with other emerging technologies. This has given rise to the development of new technological innovations, new commercial applications, and the detailed recovery of various bioactive compounds extracted from different plant and marine life food matrices. These two environmentally friendly methodologies are fully valid and have great future application prospects in biowaste valorization. They represent a feasible technological tool that can promote the implementation of a circular economy model for the food industry. The underlying mechanisms of these techniques were discussed in detail and supported by current literature.