Bioeconomy Approach Research Articles

Valorization of livestock waste through combined anaerobic digestion and microalgae-based treatment in México: A techno-economic analysis for distributed biogas generation, animal feed production, and carbon credits trading

A large percentage of world’s eutrophication is attributed to the livestock industry, which is responsible for producing over 14% of the global anthropogenic greenhouse gasses emissions (GHG). In Mexico, very few livestock producers have the necessary infrastructure to treat their livestock waste (LW) and most fail to comply with environmental regulations. The treatment of LW through a circular bioeconomy approach can mitigate these negative environmental impacts, while simultaneously producing value-added products. The present work aimed to characterize the spatial variation of the LW generated in cattle, swine, and poultry farms in Jalisco, México. Total nitrogen (TN), phosphorus (TP), and organic matter released from these production units were estimated, along with the associated GHG, considering the standard practice of uncontrolled release. An alternative management scenario using anaerobic digestion (AD) combined with microalgae-based wastewater treatment (MbWT) was evaluated by developing a software-based techno-economic analysis, showing that a centralized LW treatment system could represent a feasible solution to comply the legislation while generating high-protein biomass for animal feed. Besides, the reduction in GHG represents an opportunity for carbon credits trading in voluntary markets for livestock producers in México. Insights are provided regarding the economical, technical, and sociocultural challenges that must be overcome to transition towards more sustainable livestock production practices in Jalisco, México, and other developing regions around the globe.

Environmental sustainability of microalgae-based production systems: Roadmap and challenges towards the industrial implementation

Microalgae and cyanobacteria are a precious source for the production of biofuels/bioenergy, biomaterials and valuable biochemicals. Beyond photosynthetic CO2 conversion, microalgal systems can involve the valorisation of waste streams and the implementation of green chemistry, industrial symbiosis, and circular bioeconomy approaches. However, their sustainability is uncertain, thus their large-scale application is hindered. The numerous life cycle assessments (LCAs) performed so far are mostly based on data extrapolated from lab-scale experiments or the literature, leading to qualitative and controversial results. This paper reviews primary data-based LCA studies on microalgal pilot to industrial-scale plants. Sixteen studies satisfied the selection criteria, despite they used primary data almost exclusively for cultivation and harvesting. The outlined current status (methodology, inventory, energy performance and environmental impacts) highlighted the lack of uniformity in the applied methods and the presentation of results, as well as some lack of transparency. Nevertheless, the review concluded that electricity consumption and infrastructure are major hotspots. Therefore, the use of renewable energy for supplying the process and of sunlight for biomass photosynthesis should be preferred. The upstream processes produce large impacts. Thus, a suitable reactor, geographic location, and harvesting method should be selected. Biofuels are not competitive in most cases, but some promising multi-product biorefinery scenarios have been presented. To improve the environmental profile of microalgal high-value compounds (e.g., astaxanthin or biostimulants), co-product valorisation, waste stream utilization, renewable energy deployment, and compound productivity should be enhanced. More efforts on LCA of large-scale plants are required, especially looking at integrated biorefinery concepts, to take a crucial step towards the implementation of sustainable commercial systems.

Study of cast seaweed harvesting technologies used in the bay of Køge and their implications for effective biogas production: Applying a circular bio-economy approach

This paper focuses on the technical methods used to maximize the collection of cast seaweed from the Bay of Køge within Solrød Municipality in Denmark. The study assesses the efficiency of various seaweed harvesting technologies, as well as the pre-treatment of the seaweed (i.e. removal of sand) at the Solrød Biogas plant. As the digestate is utilized as fertilizer (N, P, K) on surrounding agricultural farmland, it is also crucial to minimize the presence of heavy metals in the digestate resulting from the use of seaweed as feedstock. The paper discusses the various ways in which sand-laden seaweed used as feedstock can contribute to energy production. It highlights the circularity and advantages of collecting cast seaweed and how this can produce nitrogen-rich fertilizer, thereby reducing CO₂ emissions. The theoretical framework employed in this study is based on the Circular Bio-Economy school of thought, which supports the cascading and reuse of biomass resources to boost and prolong their value and usefulness. Interviews with pertinent parties involved in the collection of cast seaweed and the operation of the biogas technology within Solrød Municipality serve as the basis for the research data. Moreover, data from Solrød evaluation reports and reviews of seaweed digestion data are utilized, as well as pertinent scientific literature. Among other outcomes, it is concluded that the seaweed harvesting technology now in use is useful in marine environments near to the shoreline, but less effective for collecting seaweed from further up the beach. However, it will be necessary to develop the technology, or utilize complementary harvesting technologies, in the future to improve collection efficiency and reduce the amount of sand collected with the seaweed. Problematic factors include the likelihood of sand accumulating in the biogas reactor tank, as well as damage to the cyclone stirrer and the macerator. To support the Circular Bio-Economy in terms of the collection and use of cast seaweed within Solrød Municipality, new technological methods should hence be promoted.

Integrated microalgae-based biorefinery for wastewater treatment, industrial CO2 sequestration and microalgal biomass valorization: A circular bioeconomy approach

Integrated microalgae-based biorefinery for wastewater treatment, industrial CO2 sequestration and microalgal biomass valorization: A circular bioeconomy approach

A cascaded biorefinery for the sustainable valorization of Arthrospira maxima biomass: A circular bioeconomy approach

In view of paucity of experimental data on the valorization of microalgae, this article explores the feasibility of cascaded biorefinery approach to obtain a spectrum of products having significant yield comparable to their dedicated individual extractions thereby develop a proof-of-concept for techno-economically sustainable biofuel production. Chemical-free biomass harvest was carried out by utilizing fast self-flocculation capability of A. maxima. We obtained 16.3 wt% yield of phycocyanin. Lipid and other pigments from the phycocyanin extracted biomass yielded 4.43 wt% and 3.0 wt%, respectively. Finally, bioethanol is derived through a process of continuous fermentation from the resulting carbohydrate rich residual biomass. Also, we show volumetric ethanol productivity in the continuous process to be 4.09 gL−1 h−1. The developed biorefinery shows a minimal waste generation and complete valorization of feedstock befitting a circular bioeconomy. The complexity index of the biorefinery was determined to be 39 with one feedstock, two platform molecules, nine products and eight processes.

Pyrolysis of post-methanated distillery effluent (PMDE) solid waste: Thermogravimetric degradation, kinetic and thermodynamic study with a circular bioeconomy approach

Post-methanated distillery effluent (PMDE) is a harmful dark brown to black color distillery effluent and is often released in open pond systems after anaerobic digestion by molasses-based distilleries. Due to the high standards imposed by Environmental Protection Acts, various methods of treating effluent were explored. However, pyrolysis showed excellent potential to treat it and recover energy. Hence, the present study explores the viability of producing energy from PMDE solid waste through pyrolysis. The reaction was performed at 900 °C with 20 °C min −1 heating rate in a fixed bed reactor, resulting in 36.12 wt% condensable volatiles, 22.6 wt% non-condensable gases, and 41.28 wt% solid biochar. The gas chromatographic (GC) analysis of the non-condensable gas revealed the presence of CO (17.83 vol%), H2 (8.10 vol%), and CH4 (4.30 vol%) in significant amounts, and C2H4, C2H6, C3H8, and C4H10 in minor quantities. Biochar obtained from the process has a microscopic surface area of 62.13 m2 g−1. A kinetic and thermodynamic study was performed using isoconversional methods to understand the reaction mechanism. Kinetic analysis showed the activation energy of PMDE solid waste pyrolysis to vary from 120 kJ mol −1 to 180 kJ mol −1 as conversion increases, and thermodynamic parameters (ΔH, ΔS, and ΔG) show the explanation for variation in activation energy. Additionally, the bio-circular economic approach of PMDE solid waste was presented.

Conversion of novel non-edible Bischofia javanica seed oil into methyl ester via recyclable zirconia-based phyto-nanocatalyst: A circular bioeconomy approach for eco-sustenance

Conversion of novel non-edible Bischofia javanica seed oil into methyl ester via recyclable zirconia-based phyto-nanocatalyst: A circular bioeconomy approach for eco-sustenance

Circular bioeconomy in palm oil industry: Current practices and future perspectives

Malaysia is presently ranked as the second top producer of crude palm oil in the world after Indonesia. The industry is serving as the economic backbone of the country. However, massive criticism and challenges are faced by the palm oil industry with the claims that the industry is causing environmental degradation and negative social impacts. Tremendous efforts have been taken to enhance the sustainability of the palm oil industry in environmental, social, and economic aspects including bioenergy, compost, animal feed production, and replanting of palm oil waste residues. Greener approach on circular bioeconomy is, at present, aimed to be transitioned to the palm oil industry. The concept emphasises on resource-efficient and waste minimisation, aiming to attain a lower production cost, to mitigate the negative environmental impacts, and to conserve the resources. This present review discusses the palm oil supply chain from plantation up to milling operations, current practices of palm oil industry in biomass waste reuse and recycling, and by-products productions including bioenergy generation. The potential and future prospects of full range of biowaste management and its refineries are highlighted comprehensively, including waste-to-energy, waste treatment, and waste valorisation for by-products productions. Challenges and potential technological applications are also discussed. To our best knowledge, much is lacking on the circular bioeconomy approach specifically dealt with Malaysian palm oil industry. Therefore, this review serves as a reference for the industrial stakeholders, engineers, environmentalists, researchers, and the government in decision making, policy making, future investment, and innovation advancement.

A sustainable bioeconomy approach for improved biodiesel production using photocatalytic GO@CN assisted cultivation of Chlorosarcinopsis sp. MAS04

Low biomass yield and lipid production limits the development of microalgae-derived biodiesel on a wide scale. However, the use of photo-responsive nanomaterials as a substrate for microalgae can resolve these issues and enhance its economic viability. The current investigation highlights the potential of graphene oxide; graphitic carbon nitride (GO@CN) as a photocatalytic material for Chlorosarcinopsis sp. MAS04. A suite of characterization techniques including Scanning electron microscope (SEM), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Zeta potential was used to perceive the structural, morphological, and stability insights of the synthesized nanocomposite. Cytotoxicity assay for 96 h was performed for testing microalgal viability. Subsequently, microalgae cultures were supplemented with 0–200 mg L−1 of synthesized nanocomposite for 30 days. The intracellular reactive oxygen species (ROS) concentration was estimated to determine the oxidative stress burden. The incurred cellular lipids were processed into fatty acid methyl esters (FAMEs) possessing suitable biodiesel characteristics. The 50 mg L−1 of the optimal supplement of GO@CN for microalgae cultivation results in the highest biomass and lipid production of 3.825 g L−1 and 38.5% respectively, that is a 1.5-fold increase in biomass and nearly a 1.9-fold rise in lipid content, compared to the control. Additionally, a cost-benefit analysis of the developed process inferred a 350% increase in FAME yield at an expense of 0.15 g/INR more than the cost estimated for the control. Thus, this amalgamation of nano-algal science could be a prospective approach for augmenting microalgae-based biodiesel as a sustainable bioeconomy.

Upgrading Major Waste Streams Derived from the Biodiesel Industry and Olive Mills via Microbial Bioprocessing with Non-Conventional Yarrowia lipolytica Strains

This study reports the development of a bioprocess involving the valorization of biodiesel-derived glycerol as the main carbon source for cell proliferation of Yarrowia lipolytica strains and production of metabolic compounds, i.e., citric acid (Cit), polyols, and other bio-metabolites, the substitution of process tap water with olive mill wastewater (OMW) in batch fermentations, and partial detoxification of OMW (up to 31.1% decolorization). Increasing initial phenolics (Phen) of OMW-glycerol blends led to substantial Cit secretion. Maximum Cit values, varying between 64.1–65.1 g/L, combined with high yield (YCit/S = 0.682–0.690 g Cit/g carbon sources) and productivity (0.335–0.344 g/L/h) were achieved in the presence of Phen = 3 g/L. The notable accumulation of endopolysaccharides (EPs) on the produced biomass was determined when Y. lipolytica LMBF Y-46 (51.9%) and ACA-YC 5033 (61.5%) were cultivated on glycerol-based media. Blending with various amounts of OMW negatively affected EPs and polyols biosynthesis. The ratio of mannitol:arabitol:erythritol was significantly affected (p < 0.05) by the fermentation media. Erythritol was the major polyol in the absence of OMW (53.5–62.32%), while blends of OMW-glycerol (with Phen = 1–3 g/L) promoted mannitol production (54.5–76.6%). Nitrogen-limited conditions did not favor the production of cellular lipids (up to 16.6%). This study addressed sustainable management and resource efficiency enabling the bioconversion of high-organic-load and toxic waste streams into valuable products within a circular bioeconomy approach.

Potential of Beekeeping to Support the Livelihood, Economy, Society, and Environment of Indonesia

The management of natural resources based on socio-economic and ecology development has led to a focus on the bioeconomy in the policy discourse of non-timber forest products (NTFPs). Honey is an important NTFP with high socio-economic value, and its production involves millions of Indonesians. This article reviews the current status of honey-producing bee management, cultivation and harvesting system, marketing and socio-economic values, and the industry’s environmental function in Indonesia. This research utilized a meta-narrative review method to collect data and information from Google Scholar, Scopus, Science Direct, ResearchGate, Sinta, and Garuda. The study showed that the four bee species, namely Apis mellifera, Apis cerana, Apis dorsata, and stingless bee, are the most common species in honey production in Indonesia. The four species have specific characteristics based on habitat, production capacity, derivative products, management intervention to meet honey product standards, and sustainable livelihoods. The value chain of bees’ major products, such as honey, propolis, pollen, royal jelly, wax, and other derivative products, involves the distribution of honey to all involved communities, including beekeepers, honey gatherers/hunters, intermediate traders, and the processing industry. This study also found a significant association between environmental sustainability statutes that affects functional sustainability and economic function. The finding parallels the global trends that put forward a forest-based bioeconomy approach to forest resource management. The policy must be strengthened in managing relationships among supporting actors for sustainable honey production.

Photosynthetic microbial fuel cell for bioenergy and valuable production: A review of circular bio-economy approach

Photosynthetic microbial fuel cells (PMFCs) are environmentally friendly fuel cells employed to produce renewable bioelectricity. These fuel cells require light to support their operation and are efficient to achieve high-power output. Depending upon the type of organism, they can be assisted by photosynthetic cell machinery in plants, bacteria, and algae. Algae assisted PMFCs are advantageous as they grow rapidly, require less space, produce free nascent oxygen and value-added products including bioelectricity. In this regard, this review elucidates the application and advantages of algae assisted PMFC over other PMFCs and their utility for recovery of bioelectricity and value-added products like polyunsaturated fatty acids, carotenoids, lutein, carbohydrates, proteins, polyhydroxyalkanoates, etc. Furthermore, the potential of generated bioelectricity and simultaneous resource recovery employing PMFCs are highlighted due to their low cost. Thus, this review can be a rapid guidebook for budding researchers in the field of PMFC's and possibly expedite the economical commercialization of PMFCs.

Production of phycobiliproteins, bioplastics and lipids by the cyanobacteria Synechocystis sp. treating secondary effluent in a biorefinery approach.

Cyanobacteria have been identified as promising organisms to reuse nutrients from waste effluents and produce valuable compounds such as lipids, polyhydroxyalkanoates (PHAs), and pigments. However, almost all studies on cyanobacterial biorefineries have been performed under lab scale and short cultivation periods. The present study evaluates the cultivation of the cyanobacterium Synechocystis sp. in a pilot scale 30 L semi-continuous photobioreactor fed with secondary effluent for a period of 120 days to produce phycobiliproteins, polyhydroxybutyrate (PHB) and lipids. To this end, the harvested biomass from the semi-continuous photobioreactor was transferred into 5 L vertical column batch photobioreactors to perform PHB and lipid accumulation under nutrient starvation. Three hydraulic retention times (HRT) (6, 8 and 10 days) were tested in the semi-continuous photobioreactor to evaluate its influence on biomass growth and microbial community. A maximum biomass concentration of 1.413 g L-1 and maximum productivity of 173 mg L-1 d-1 was reached under HRT of 8 days. Microscopy analysis revealed a shift from Synechocystis sp. to Leptolyngbya sp. and green algae when HRT of 6 days was used. Continuous, stable production of phycobiliproteins in the semi-continuous photobioreactor was obtained, reaching a maximum content of 7.4%dcw in the biomass. In the batch photobioreactors a PHB content of 4.8%dcw was reached under 7 days of nitrogen and phosphorus starvation, while a lipids content of 44.7%dcw was achieved under 30 days of nitrogen starvation. PHB and lipids production was strongly dependent on the amount of nutrients withdrawn from the grow phase. In the case of lipids, their production was stimulated when there was only phosphorus depletion. While Nitrogen and phosphorus limitation was needed to enhance the PHB production. In conclusion, this study demonstrates the feasibility of cultivating cyanobacteria in treated wastewater to produce bio-based valuable compounds within a circular bioeconomy approach.

Plastic futures and their CO2 emissions.

Plastics show the strongest production growth of all bulk materials and are already responsible for 4.5% of global greenhouse gas emissions1,2. If no new policies are implemented, we project a doubling of global plastic demand by 2050 and more than a tripling by 2100, with an almost equivalent increase in CO2 emissions. Here we analyse three alternative CO2 emission-mitigation pathways for the global plastics sector until 2100, covering the entire life cycle from production to waste management. Our results show that, through bio-based carbon sequestration in plastic products, a combination of biomass use and landfilling can achieve negative emissions in the long term; however, this involves continued reliance on primary feedstock. A circular economy approach without an additional bioeconomy push reduces resource consumption by 30% and achieves 10% greater emission reductions before 2050 while reducing the potential of negative emissions in the long term. A circular bioeconomy approach combining recycling with higher biomass use could ultimately turn the sector into a net carbon sink, while at the same time phasing out landfilling and reducing resource consumption. Our work improves the representation of material flows and the circular economy in global energy and emission models, and provides insight into long-term dynamics in the plastics sector.

Marine-Derived Actinomycetes: Biodegradation of Plastics and Formation of PHA Bioplastics-A Circular Bioeconomy Approach.

Plastics are present in the majority of daily-use products worldwide. Due to society's production and consumption patterns, plastics are accumulating in the environment, causing global pollution issues and intergenerational impacts. Our work aims to contribute to the development of solutions and sustainable methods to mitigate this pressing problem, focusing on the ability of marine-derived actinomycetes to accelerate plastics biodegradation and produce polyhydroxyalkanoates (PHAs), which are biodegradable bioplastics. The thin plastic films' biodegradation was monitored by weight loss, changes in the surface chemical structure (Infra-Red spectroscopy FTIR-ATR), and by mechanical properties (tensile strength tests). Thirty-six marine-derived actinomycete strains were screened for their plastic biodegradability potential. Among these, Streptomyces gougerotti, Micromonospora matsumotoense, and Nocardiopsis prasina revealed ability to degrade plastic films-low-density polyethylene (LDPE), polystyrene (PS) and polylactic acid (PLA) in varying conditions, namely upon the addition of yeast extract to the culture media and the use of UV pre-treated thin plastic films. Enhanced biodegradation by these bacteria was observed in both cases. S. gougerotti degraded 0.56% of LDPE films treated with UV radiation and 0.67% of PS films when inoculated with yeast extract. Additionally, N. prasina degraded 1.27% of PLA films when these were treated with UV radiation, and yeast extract was added to the culture medium. The main and most frequent differences observed in FTIR-ATR spectra during biodegradation occurred at 1740 cm-1, indicating the formation of carbonyl groups and an increase in the intensity of the bands, which indicates oxidation. Young Modulus decreased by 30% on average. In addition, S. gougerotti and M. matsumotoense, besides biodegrading conventional plastics (LDPE and PS), were also able to use these as a carbon source to produce degradable PHA bioplastics in a circular economy concept.

From Biorefinery to Food Product Design: Peach (Prunus persica) By-Products Deserve Attention.

There is an increasing demand for functional foods to attend the consumers preference for products with health benefits. Peach (Prunus persica), from Rosaceae family, is a worldwide well-known fruit, and its processing generates large amounts of by-products, consisting of peel, stone (seed shell + seed), and pomace, which represent about 10% of the annual global production, an equivalent of 2.4 million tons. Some studies have already evaluated the bioactive compounds from peach by-products, although, the few available reviews do not consider peach by-products as valuable materials for product design methodology. Thereby, a novelty of this review is related to the use of these mostly unexplored by-products as alternative sources of valuable components, encouraging the circular bioeconomy approach by designing new food products. Besides, this review presents recent peach production data, compiles briefly the extraction methods for the recovery of lipids, proteins, phenolics, and fiber from peach by-products, and also shows in vivo study reports on anti-inflammatory, anti-obesity, and anti-cerebral ischemia activities associated with peach components and by-product. Therefore, different proposals to recover bioactive fractions from peach by-products are provided, for further studies on food-product design.

Green bioprocessing and applications of microalgae-derived biopolymers as a renewable feedstock: Circular bioeconomy approach

An expeditious pace of expanding industrialization and urbanization is a global vulnerability which immediately requires utmost attention towards the replacement of prosaic petroleum-based polymer assimilation. Thus, greening the innovative route of microalgae derived biopolymers has attained significant interest as an improved and sustainable approach towards the worldwide circular bioeconomy. In this context, the use of as synthesized biopolymers from microalgae attributing as a potential feedstock has bestowed for a biodegradable solution to reduce the greenhouse gases emission and rapid biomass productivity with metabolic flexibility. However, the confront of high microalgae cultivation cost and low metabolites’ accumulation have triggered the advancement of microalgae metabolic cultivation strategy. Hence, the current review portrays to propose a novel multi-phasic fed batch light depleted low-cost wastewater cultivation approach and a clear mechanistic phenomenon for accelerating the biopolymer production. This review also provides a comprehensive summary on several microalgae strains which are capable for biopolymer synthesis and various effective extraction techniques to isolate the biopolymers. The future endeavour and challenges on the microalgae circular bioeconomy which involves the current issues regarding the cell harvesting method, scale up and bioprocessing cost of microalgae cultivation have been highlighted. The applications for microalgae derived biopolymer in industrial and nutraceutical sectors have also been emphasized. This review is expected to bring new insights to the industrial stakeholders for further advancement of microalgae-based biopolymer field economically, and eventually contributing towards environmental sustainability. • Bioprocessing of microalgae derived biopolymer via circular bioeconomy approach. • Multiphasic fed batch for enhancing the microalgae mediated biopolymer yield. • Green processing and scale up biopolymer production. • Applications of microalgae mediated biopolymers in the industry.

Valorization of spent coffee grounds for biogas production: A circular bioeconomy approach for a biorefinery

• Research on recycling spent coffee grounds (SCG) into biogas is relatively new. • Micronutrient supply and pH are key inputs for the successful anaerobic digestion. • The biogas yield from SCG was 0.500-0.598 m 3 /kg with CH 4 concentrations of 55–61%. • The methane yield form the SCG was 310 ± 2 CH 4 mL/g VS. • The methane yield from the defatted spent coffee grounds (DSCG) was 336 ± 7 mL CH 4 /g VS. • Co-digestion with other waste streams provided similar yields as obtained from SCG. • Research on the techno-economics of biogas production from SCG is recommended. As a by-product of coffee consumption, millions of tons of spent coffee grounds (SCG) are produced annually. SCG can be recycled in a biorefinery-based process to produce biofuels and value-added products, avoiding the environmental issues, hazardous emissions and costs associated with its disposal. The recycling potential of SCG into biogas by the anaerobic digestion (AD) and co-digestion was reviewed in this work. Such types of review papers are novel and not much work was done on this aspect. The AD of SCG produces 0.500–0.598 m 3 /kg dry organic matter of biogas with a methane (CH 4 ) concentration of 55–61 %. Nevertheless, the long-term mono-digestion of SCG has been linked with instability and volatile fatty acid (VFA) accumulation. Co-digestion with other waste streams, such as waste activated sludge, food waste and spent tea waste, resulted in the same or larger amounts of CH 4 emission. Additionally, the defatted spent coffee grounds (DSCG) have been reported to have advantage over the SCG as the average CH 4 yield was 336 ± 7 CH 4 mL/g vS compared to 310 ± 2 CH 4 mL/g vS from SCG. Additionally, the positive impact of the pretreatment process in increasing the CH 4 yield during the AD of the SCG has been observed. Based on the presented work, it is clear that recycling SCG and DSCG is a worthwhile option that can help taxpayers save money on landfill operations and maintenance besides protecting the environment from numerous hazardous emissions. Valorization of biogas products and approaches to enhance the economics of the SCG/DSCG-based biorefinery are indicated in this review as areas where future work in biogas generation from SCG and DSCG can be done. In conclusion, this paper suggests further investigation of the techno-economic analyses and life cycle assessment (LCA) of a biorefinery based on the AD of the SCG and DSCG with other organic waste streams.

The Sound of a Circular City: Towards a Circularity-Driven Quietness.

The circular economy paradigm can be beneficial for urban sustainability by eliminating waste and pollution, by circulating products and materials and by regenerating nature. Furthermore, under an urban circular development scheme, environmental noise can be designed out. The current noise control policies and actions, undertaken at a source–medium–receiver level, present a linearity with minimum sustainability co-benefits. A circular approach in noise control strategies and in soundscape design could offer numerous ecologically related co-benefits. The global literature documenting the advantages of the implementation of circular economy in cities has highlighted noise mitigation as a given benefit. Research involving circular economy actions such as urban green infrastructure, green walls, sustainable mobility systems and electro-mobility has acknowledged reduced noise levels as a major circularity outcome. In this research paper, we highlight the necessity of a circularity and bioeconomy approach in noise control. To this end, a preliminary experimental noise modeling study was conducted to showcase the acoustic benefits of green walls and electric vehicles in a medium-sized urban area of a Mediterranean island. The results indicate a noise level reduction at 4 dB(A) when simulating the introduction of urban circular development actions.

Yeast community composition impacts on tequila industry waste treatment for pollution control and waste-to-product synthesis

The Tequila industry is a major producer of wastewater in the state of Jalisco, Mexico. Tequila vinasses (TV) are a residue from the distillation of fermented agave wort during tequila production. TV are difficult to treat due their high organic content, high nutrient loads, acidic pH and high discharge temperature. TV are frequently released into waterbodies or soil without any treatment, leading to environmental degradation of soil and water sources. To reduce the environmental impact of the tequila industry, cost-effective TV revalorization approaches must be developed. The goals of the present study were to assess the treatment and revalorization potential of TV using mono and mixed yeast cultures to produce single-cell protein (SCP) and to analyze yeast community composition using high-throughput sequencing during the mixed-culture fermentation of TV. The fermentation process was performed using a mixed culture of three fodder yeast species (Candida utilis, Rhodotorula mucilaginosa and Kluyveromyces marxianus) during 48 h at benchtop-scale. High-throughput sequencing was performed to assess the relative abundance of the yeast communities. Additionally, a redundancy analysis was performed to analyze the bidirectional influence between yeast communities and pollutant removal (COD, nitrogen, phosphorus, proteins, and sugars). Mixed yeast cultures displayed overall higher pollutant removal rates than monocultures, where C. utilis and K. marxianus contributed the most to pollutant removal and protein accumulation. The R. mucilaginosa population declined rapidly in mixed culture, presumably due to TV acidity and phenolic composition. However, the presence of The R. mucilaginosa in the mixed culture enhanced pollutant removal and amino acid contents. Accordingly, the protein and amino acid content within mixed cultures were significantly higher than those of monocultures, indicating that mixed cultures have a strong potential to produce protein rich biomass from TV, aiding in the transition of both the tequila and the livestock industries to a sustainable circular bioeconomy model by the reintegration of organic material flows into productive processes, reducing raw resource intake and waste generation. The present circular bioeconomy approach could represent a potential to produce 45,664 tons of protein feed yearly, based on the current tequila vinasses generated in the state of Jalisco.