Advances in Biotechnology in the Circular Economy: A Path to the Sustainable Use of Resources

Abstract

This article analyzes the role of biotechnologies in supporting the circular economy in various productive sectors. It highlights innovative approaches that contribute to sustainability, resource regeneration, waste recovery, and reduced dependence on fossil fuels. The text brings together relevant examples of biotechnological applications aimed at the production of bioplastics, bioenergy, bioproducts, and bioremediation solutions, among others of interest. In addition, it highlights the potential of using agro-industrial waste as raw material in biotechnological processes, promoting more efficient production chains with less environmental impact. The methodology was based on a comprehensive review of recent advances in industrial biotechnology. The main results reveal successful applications in the production of polyhydroxyalkanoates (PHAs) from food waste, in the microbial bioleaching of metals from electronic waste, and in the bioconversion of agricultural byproducts into functional materials, among others. The article also discusses the regulatory and social factors that influence the integration of these solutions into circular value chains. It concludes that biotechnology is a key element for the circular bioeconomy, offering scalable and environmentally efficient alternatives to conventional linear models, although its large-scale adoption depends on overcoming technological and market challenges.

1. Introduction

The environmental emergency, which is mainly driven by natural resource depletion and pollution, has made it urgent to transition to more sustainable business models. The circular economy (CE) has been widely promoted as an alternative to the traditional linear model of relying only on reusing, recycling, and recovering of materials to minimize waste and maximize industrial efficiency [1,2].

Within this framework, biotechnology plays a critical role by offering innovative solutions to transform waste into value-added products like sustainable wastewater treatment, thus reducing dependence on fossil resources [3,4,5].

Among the most promising biotechnological applications in the CE is the production of biopolymers and bioplastics from renewable sources. Recent studies show that microorganisms like Bacillus thuringiensis and Halomonas species can convert agricultural and industrial residues such as algal biodiesel waste and asparagus waste into polyhydroxyalkanoates (PHAs) [3,6], biopolymers naturally produced by microorganisms under nutrient-limited conditions, offering a biodegradable alternative to petroleum-based plastics [5,7,8]. In addition, pilot-scale production of PHAs using pure cultures has demonstrated both technical and environmental viability, thereby reducing reliance on synthetic polymers [9].

Another key technology is anaerobic digestion (AD), which converts organic waste into biogas and organic fertilizers. Research indicates that AD can be applied to various waste streams, from activated sludge [10] to brewery waste [11], thereby promoting energy recovery and the valorization of byproducts. Moreover, dark fermentation processes are being explored for biohydrogen production from organic residues, utilizing specialized microorganisms to optimize energy conversion [12].

In the field of bioremediation, biotechnology has shown tremendous potential for environmental cleanup. Both microbial and fungal strategies are employed to remediate contaminated soils and waters by removing heavy metals and toxic organic compounds. Recent studies highlight the use of an organic amendment based on horse manure to remediate soils contaminated with hexachlorocyclohexane (HCH) [13], while specific microbial consortia are being used to treat hypersaline industrial effluents [14]. Additionally, biomineralization has proven effective in extracting metals from effluents and electronic waste, reducing the need for primary mining and promoting the recycling of strategic materials [3,6].

Another significant breakthrough is the use of microalgae in treating effluents and capturing CO₂, which enables the production of high-value biomass. Cultures of Chlorella vulgaris are being investigated for their ability to remove nutrients and organic compounds from industrial effluents [15] while simultaneously producing biomolecules beneficial for the food and cosmetic industries [16,17].

Furthermore, microalgae are also being studied as a raw material for producing biodiesel and biohydrogen, thus contributing to a sustainable energy transition [18]. Industrial biotechnology has also taken significant steps allowing for the development of more efficient biocatalysts and enzymatic processes across various industrial applications [19].

Enzymes derived from bacteria and fungi are widely used to convert biomass, thereby increasing the efficiency of biofuel production and the synthesis of renewable chemicals [20,21,22]. However, enzymes are typically unstable and their recovery after use is complex, drawbacks that can be overcome through enzyme immobilization, such as binding the enzyme to a solid carrier or entrapping/encapsulating it within a polymeric matrix [23]. Synthetic polymers, known for their mechanical stability, (bio)chemical resilience, and customizable composition based on the intended application, have been used often as enzyme carriers, yet they are typically non-biodegradable. Alternatively, biopolymers (e.g., alginate, cellulose, chitosan) and other organic biomaterials (e.g., biochar- and biomass-derived materials), although less mechanically robust and limited by seasonality and compositional heterogeneity, are biocompatible, nontoxic and biodegradable [24,25,26]. For instance, immobilizing enzymes on biodegradable supports has shown promise in wastewater treatment and other sustainable industrial processes [27].

Given the rapid advances in industrial biotechnology, this study aims to analyze key biotechnological innovations that contribute to waste valorization and sustainability. For this, a systematic literature review was conducted using Scopus. We included articles published between 2023 and 2024 that addressed biotechnological applications such as waste valorization, bioenergy, or bioplastics, among others.

Specifically, we categorize and discuss nine major application areas, evaluating their economic and environmental impact. To achieve this, 77 scientific articles were selected and categorized. The methodology for selecting these articles follows the criteria established by the PRISMA protocol [28], ensuring transparency and reproducibility in the research. The findings are discussed to highlight, for example, key technological advances, emerging trends, and remaining challenges considering their large scale.

2. Review and Contextualization

2.1. Bioplastics: Sustainable Alternatives to Conventional Plastics

The production of bioplastics highlights biotechnology’s transformative potential. By converting various waste into renewable and biodegradable materials, it offers sustainable alternatives to petroleum-based conventional plastics [29,30]. Technologies such as the production of PHAs have gained prominence since they use agricultural and industrial waste as raw materials. Examples include agricultural residues such as asparagus byproducts [5], chickpea starch waste [31], industrial and domestic food waste [32], the organic fraction of urban solid waste [33], paper waste [34], and industrial wastewater [35].

Another noteworthy technological advance is the use of genetically modified microorganisms (GMMs) specifically designed to enhance the biodegradation processes of polymers, which can directly address the global issue of plastic waste accumulation [36,37]. Pilot-scale studies have confirmed the technical and economic viability of PHAs, making use of pure cultures, directly tackling issues related to production costs and efficiency and the environmental sustainability of industrial processes [9,38].

In addition to pure cultures, the use of mixed microbial cultures (MMCs) has arisen as a promising strategy for industrial-scale bioplastic production. These cultures take advantage of the existing waste treatment infrastructure, enabling both economically and environmentally viable production processes. This approach significantly reduces operating costs and improves overall waste management efficiency, thus reinforcing the CE through the synergistic action of microorganisms that optimize the decomposition of complex wastes. The synergistic effects of MMCs also provide greater resilience to environmental fluctuations, ensuring stable and consistent production processes, which facilitates their application at various scales [38].

Currently, industrial capacities already exist for bioplastic production, especially for PHAs, with annual volumes reaching up to 2000 tons. These materials are primarily targeted at strategic sectors such as agriculture, medicine, and environmentally friendly packaging, underscoring the versatility and importance of this technological novelty [38,39].

Despite their great potential, bioplastics face several technical and economic challenges that limit their competitiveness compared with conventional plastics. Among the main obstacles are high production costs, variability in mechanical properties, but also limited process scalability [40,41]. In addition, the environmental benefits associated with the use of bioplastics depend heavily on the type of raw material used, production conditions, and their final destination—factors that are not always properly regulated or optimized [42,43].

Additional, later technologies, such as the optimized separation of biopolymers using three-phase partitioning systems, allow increased efficiency and the reduction in operating costs [44]. Similarly, the recovery of lignocellulosic residues for obtaining sustainable chemicals represents another crucial advance that broadens the potential applications of biotechnology [45]. These technologies add further value to waste, contributing directly to environmental, economic, and social issues.

2.2. Anaerobic Digestion: Closing Nutrient and Energy Cycles

Anaerobic digestion exemplifies biotechnology’s transformative role in nutrient recovery and renewable energy generation from organic waste, directly contributing to the promotion of the CE [46,47]. These biological systems convert various organic waste into biogas and biofertilizers, offering practical and sustainable applications in both agricultural and industrial contexts. Recent studies have shown significant improvements in using specific wastes, such as pruning residues [47] and brewery effluents [11], confirming the environmental and economic benefits provided by AD. Timm et al. (2024) [11] highlight how brewery wastes can be converted into β-glucans—high-value bioactive compounds—substantially expanding the economic potential of the process.

Beyond conventional applications, recent progress has explored innovative integrations such as the integration of AD with mobile bioreactors and photobioreactors, creating highly efficient hybrid systems capable of achieving carbon neutrality [48]. These systems capture CO₂, recover nutrients, and simultaneously produce lipid-rich biomass, aligning wastewater treatment with sustainability targets. The recovery of curdlan—a useful polysaccharide obtained from aerobic granular sludge—also illustrates how biotechnology can maximize waste valorization in existing industrial facilities [49].

Additional studies indicate that integrating AD with complementary technologies such as denitrification allows for the efficient removal of nutrients and transforms energy-intensive operations into energy-neutral processes, offering effective solutions for the sustainable treatment of leachates and complex effluents [10]. Furthermore, the application of mixed microbial cultures (MMCs) in AD offers notable advantages, including increased process stability and improved substrate degradation efficiency. MMCs are more resilient to environmental variations, ensuring stable and consistent operation [50,51].

Although these advances are promising, technical challenges remain, particularly regarding the costs associated with waste pretreatment and the potential toxicity of certain substrates, necessitating continuous technological optimization. Nevertheless, AD is progressively establishing itself as a versatile technology essential for achieving sustainability, closing nutrient and energy cycles and effectively contributing to the transition to a CE [10,11,46].

Notwithstanding its environmental advantages, AD faces several challenges that limit its large-scale application. The efficiency of the process depends heavily on the type and composition of the waste, often requiring pretreatment steps that increase operating costs [52,53]. In addition, the management of byproducts, such as the digestate, can become complex when there is no infrastructure for its agricultural or energy recovery. The stability of the process can also be affected by fluctuations in temperature, organic load, and the presence of inhibitors, especially in developing countries with limited infrastructure [54]. These factors require constant optimization and greater political and technical support to enable its widespread adoption. Nonetheless, challenges such as pretreatment costs, energy requirements, and regulatory uncertainty may limit its application in lower-income settings.

2.3. Industrial Biotechnology and Biorefineries

Biomining within industrial biotechnology and biorefineries has emerged as a sustainable and environmentally responsible approach for extracting valuable metals from electronic waste and mining tailings. Although biomining is a distinct approach to resource recovery, it aligns with industrial biotechnology and biorefineries, as it uses biological systems for extracting valuable metals, thereby contributing to the CE [3,55]. This technology harnesses the power of specific microorganisms to extract precious and critical metals through different recovery techniques, e.g., bioleaching, bioweathering, biosorption, bioaccumulation, bioprecipitation, and bioflotation. The former two essentially involve the solubilization of metals in solid form for their subsequent recovery from the lixiviates by one or several of the latter four techniques. These recovery methods can be used independently of bioleaching or bioweathering when the metals are already present in soluble form [56]. Biomining significantly minimizes the negative environmental impacts typically associated with traditional mining practices [57].

Recent studies have evidenced significant advances in this field. One such study was performed by Becci et al., who developed green hydrometallurgical processes for recovering precious metals, e.g., silver and gold, from printed circuit boards by leveraging the bioleaching capabilities of a Pseudomonas aeruginosa strain that produces cyanide, which solubilizes precious metals by forming metal–cyanide complexes [3]. Previously, Kumar et al. had established the potential of this approach by using bacterial isolates, e.g., Bacillus spp., retrieved from an abandoned goldmine to recover gold and copper from printed circuit boards [58]. GMMs have also been explored for enhancing the bioleaching of precious metals from printed circuit boards [59]. Genetic engineering is a promising innovation for optimizing biomining, increasing metal recovery efficiency while reducing hazardous waste and pollutant emissions [55]. Still, genetically engineered microorganisms are often restricted in biomining due to environmental and ethical concerns. However, their use is feasible in the bioleaching that often takes place in contained systems, e.g., bioreactors, minimizing the risk of environmental release. Oppositely, open-system biomining methods, e.g., heap leaching and in situ mining, present greater risks to natural ecosystems, making the use of genetically engineered microorganisms less viable in those settings [60,61].

In addition, biomining enables the effective integration of extractive activities with broader sustainable strategies, facilitating the recovery of the scarce and critical resources present in electronic and industrial wastes, and thus, contributing to the security and sustainability of production chains [57]. These technological advances in biomining not only offer practical and economically viable solutions for industries but also have strong potential to radically transform the traditional mining industry, aligning it more closely with the environmental sustainability and social responsibility goals inherent to the CE paradigm.

2.4. Bioremediation: Restoring Degraded Environments

Bioremediation is recognized as an effective and sustainable tool for degrading persistent pollutants and restoring degraded ecosystems. By utilizing microorganisms, plants, and other biological agents, this approach offers environmentally friendly solutions to mitigate environmental impacts and promote the recovery of contaminated areas [62,63,64]. Martínez-Espinosa highlighted the use of halophilic archaea in remediating saline environments contaminated with pollutants. These organisms have demonstrated high efficiency in removing heavy metals and hydrocarbons, standing out for their resilience under extreme conditions where traditional remediation techniques face significant limitations [65].

In parallel, fungal bioremediation approaches explored by Navina et al. have proven effective in transforming pollutants into bioactive materials [66]. In addition to degrading toxic substances, the fungi used also generate high-value bioactive compounds, further enhancing the relevance of these biotechnological approaches within the context of the CE. These bioactive compounds have potential applications in various industrial sectors, further emphasizing the importance of biotechnological strategies in waste valorization. Another important advancement was proposed by Serbent et al. [27] that involves using support derived from biological waste for immobilizing enzymes, such as laccases, aimed at treating organic pollutants, including complex organochlorine compounds. The use of residual materials such as biochar and peanut shells further reinforces the viability of CE-based solutions while simultaneously increasing the efficiency of degradation processes [27].

Checa-Fernández et al. [13] investigated the use of equine-derived additives for remediating soils contaminated with hexachlorocyclohexane (HCH). This study demonstrated a significant reduction in contaminant levels in the soil along with substantial improvements in biological activity and nutritional content, thereby enhancing the ecological health of the treated environment [13]. A key approach within bioremediation is the development of community microbial systems, which have shown promising results in microbial systems. For example, Wang et al. [14] developed an effective technology for the bioremediation of hypersaline, nutrient-rich industrial effluents. This technology not only effectively removed the pollutants but also generated biomass rich in valuable compounds, reinforcing the sustainable and economical nature of the biotechnological approach [14].

Despite the acknowledged ability of several microorganisms to clean up environmental contaminants, the complexity of pollutants, scarce bioavailability, and operational conditions, e.g., pH and temperature, can hinder microbial activity. Moreover, the adaptation and survival of microorganisms introduced at contaminated sites is challenging. Genetic engineering has again been used to enhance microbial degradation capabilities. Microorganisms can thus be tailored to synthesize enzymes that break down pollutants more efficiently [67,68,69,70].

Although recent advances in biotechnology have significantly expanded the applications of bioremediation, its large-scale implementation still faces several challenges. The effectiveness of these technologies depends on environmental factors such as temperature, pH, and nutrient availability, which directly affect microbial activity and degradation rates [71,72]. The introduction of microorganisms into contaminated ecosystems also poses ecological risks, especially in the case of GMMs, whose use is restricted by strict regulations in many regions [73,74]. In addition, the time required to achieve significant results can be long, which reduces its applicability in contexts that require immediate responses. These limitations reinforce the need for integrated strategies combining bioremediation with physical–chemical methods and supportive public policies to ensure long-term effectiveness and viability [64]. Despite promising results, bioremediation is often hindered by site-specific limitations, regulatory concerns related to GMMs, and the need for skilled personnel and controlled environments.

2.5. Microalgae: Carbon Capture and Sustainable Production

While microalgae are effective in bioremediation, this section focuses on their potential in bioenergy and CO₂ mitigation. In fact, their ability to transform waste into valuable resources positions microalgae as a central element in sustainable biotechnological applications. For instance, Policastro et al. demonstrated high lipid productivity in microalgae grown under controlled nitrogen and light conditions in continuous bioreactors, highlighting their sustainable potential for fuel and food applications [17]. Similarly, Oliva et al. investigated biodiesel production from microalgal lipids cultivated in integrated systems for gas emission treatment, effectively combining pollutant control with the simultaneous generation of biofuels [16].

Moreover, Wei et al. employed reprogrammed marine bacteria to valorize lignin derived from waste, underlining the potential of microorganisms in converting lignocellulosic byproducts into high-value chemical compounds [6]. Najar et al. studied the use of C. vulgaris for remediating effluents from the food and beverage industry, demonstrating significant pollutant reduction while concurrently generating pigments and proteins [15].

Microalgae also offer significant environmental benefits in bioremediation compared with traditional methods. Chemical techniques, such as reduction and oxidation, and physical methods, including soil excavation, vacuum extraction, and thermal desorption, have limitations. In contrast, microalgae have a high CO₂ fixation capacity during photosynthesis, making them a promising solution for mitigating climate change [75,76]. Unlike conventional chemical or physical remediation methods, which demand high energy inputs from fossil fuels and often generate secondary pollutants, microalgae-based systems provide a more energy-efficient and sustainable alternative, effectively reducing both environmental impact and resource consumption [77,78].

In addition to carbon capture, microalgae are effective at removing excess nutrients such as nitrogen and phosphorus from wastewater, thereby preventing environmental issues like eutrophication [79]. They also have the capacity to absorb and transform contaminants such as heavy metals and organic pollutants, making them highly efficient in the remediation of industrial effluents and contaminated water bodies. Microalgae-based remediation processes can further contribute to biodiversity conservation by significantly improving soil and water quality—unlike physical and chemical methods, which often negatively affect local biology. Additionally, cultivating microalgae for environmental remediation can be combined with the production of valuable biomass such as biofuels, animal feed, and other commercial bioproducts, thus fostering a sustainable bioeconomy [80,81].

In the context of wastewater treatment, systems based on microalgae—and even co-cultures of algae and bacteria—have demonstrated remarkable efficiency, achieving near to complete pollutant removal. Pilot- and industrial-scale studies reveal significant reductions in pollutant loads and greenhouse gas emissions. However, challenges remain, particularly in optimizing cultivation conditions, increasing biomass productivity, or reducing both operational and capital costs [75].

Ongoing research and technological advances are crucial to overcoming these challenges, making microalgae-based systems more accessible and viable on a large scale. Cultivation systems need to be designed to minimize both initial and maintenance costs by utilizing renewable energy sources and natural solar illumination. Additionally, effective control of pollution and interspecies competition on a large scale demands advanced monitoring and management technologies [82].

Ultimately, microalgae are celebrated for their versatility, not only as a biological resource for the sustainable production of biodiesel and hydrogen, but also for their rapid growth and high lipid content. Their potential applications in food production and the pharmaceutical industry are equally promising, owing to their rich protein content and beneficial health compounds such as lutein and zeaxanthin or astaxanthin. Moreover, using food waste efficiently as a substrate in their cultivation further expands economic opportunities and reduces the pollution associated with excessive chemical use [83]. Furthermore, biotechnological advancements in food waste valorization contribute to sustainability by transforming organic residues into bioactive compounds, creating synergies between microalgae-based solutions and food industry innovations.

2.6. The Food Industry: Waste Valorization and Sustainable Production

The application of biotechnologies in the food industry has shown significant potential to enhance CE practices, mainly through the valorization of waste and the generation of high-value bioactive compounds. For instance, Muñoz-Seijas et al. investigated the use of insect byproducts, such as waste from Tenebrio molitor (mealworms), to produce proteases through solid-state fermentation [84]. Previously, T. molitor frass from mealworms fed with rice bran (an underused agro-industrial byproduct) was used for the production of bio-oils through pyrolysis, intended for use as bio-insecticides [85]. These studies highlighted an innovative approach to converting agro-industrial and insect wastes into valuable goods applicable in food, household, pharmaceutical, and public health sectors [84,85].

Similarly, Eras-Muñoz et al. [86] emphasized the production of sophorolipids, a type of biosurfactant derived from hydrolysates obtained from agricultural byproducts. Their research underscored the effectiveness of residues like wheat bran and coconut husks as efficient nitrogen sources for biosynthesis, demonstrating how agro-industrial waste can be transformed into sustainable and high-value bioproducts [86]. Herrmann et al. examined the versatility of the Bacillus genus in the bioeconomy, highlighting its capacity to produce a wide range of products, including probiotics and enzymes [4].

Brewery byproducts present another relevant example of how nutrient-rich residues can be repurposed to improve food systems. Brewery waste, namely brewers’ spent grain, brewers’ spent yeast, and trub, are rich in fiber, proteins, B vitamins, and antioxidants, making them valuable resources for the food industry. These byproducts can be processed via different technologies, e.g., extraction and fermentation, among others, into functional ingredients for use in bakeries, snacks, supplements, and even packaging [87,88].

The use of Bacillus in agro-industrial waste significantly reinforces biotechnology’s role in reducing waste and creating additional economic value [4]. Manganda et al. [1] evaluated circular practices among agro-industrial startups, emphasizing how disruptive technologies—including biotechnology and precision agriculture—are driving efficiency and sustainability. Their study also stressed the importance of collaboration between startups and traditional industries to implement broader circular practices [1].

The global food industry currently faces deep and complex challenges driven by population growth, climate change, multiple crises, and shifting consumer preferences [89]. It is projected that the world’s population will reach approximately 9.7 billion by 2050, significantly increasing the demand for safe, nutritious, and sustainable food. This rapid rise in food demand, coupled with urbanization and agricultural expansion, creates additional environmental impacts and calls for more resilient and sustainable food systems [90].

2.7. Advances in Biotechnology for the CE: Converting Waste into Valuable Resources

Emerging technologies such as the use of microalgae for producing biodiesel and biomaterials while capturing CO₂ emissions are gaining prominence [16,17]. Integrated systems are showing promising results by converting biomass into valuable products, e.g., lipids [17]. However, Zhang et al. caution about the environmental and economic challenges related to the carbon footprint during operational stages, suggesting the use of renewable sources (e.g., solar energy) and low-cost nutrients such as municipal wastewater, to improve process sustainability [91]. In the field of nanotechnology, marine wastes are being transformed into carbon nanomaterials used for pollutant monitoring and food safety, thus highlighting the role of biotechnology in waste recovery [92].

In industrial sectors, enzymatic and microbial innovations have reduced the use of chemicals and improved energy efficiency, particularly in the pulp and paper industry, through processes such as bio-bleaching, refining, decolorization, and effluent bioremediation [78,93]. The use of agricultural residues for generating biofuels and biomaterials exemplifies how the circular bioeconomy can close resource cycles and reduce waste [94].

Biorefineries have emerged as central proposals for valorizing agro-industrial waste, promoting the conversion of biomass into bioenergy and bioplastics. Studies highlight both chemical and biological technologies to transform waste into renewable products [2], the use of lipid production from marine residues [91], and sustainable production from cocoa husks [95]. The adoption of circular strategies in agribusiness further emphasizes the importance of biorefineries in creating sustainable production chains [1].

Recycling and waste treatment play crucial roles in the CE by enabling material reuse and reducing environmental impacts. Solutions such as the cost-effective removal of chromium (VI) using modified vegetal biomass [96], brewery wastewater treatment with basidiomycete fungi for β-glucan production [11], and innovative plastic recycling techniques including photochemical and biotechnological processes [97], exemplify these approaches. Despite these advances, challenges such as waste collection logistics and process standardization still need to be addressed [98].

Industrial biotechnologies have been central in reducing the environmental impact of production processes and thereby promoting a more sustainable economy. Examples include enzymatic advances that lower energy and chemical consumption in the pulp and paper industry [78], the application of cellulose-degrading microorganisms in recycling and biofuel production [94], and the development of biocompatible melanin nanoparticles derived from food industry results for biosensors [99]. The circular bioeconomy emerges as a strategic model to integrate sustainability and innovation, as seen in studies on recovering peanut waste for bioenergy [100], sustainable phosphorus systems in agriculture [101], and transforming food waste into biochemicals and biomaterials [102]. However, overcoming financial and regulatory barriers will require concerted efforts from all stakeholders [101].

In the renewable energy sector, biotechnology is essential for mitigating climate change and reducing reliance on fossil fuels. Examples include CO₂ biofixation at wastewater treatment plants [48], the sustainable production of biodiesel and biolubricants from dairy effluents [103], and the green conversion of microalgal lipids into biodiesel [16]. The integration of biotechnology with nanotechnology offers new opportunities for sustainable materials, such as carbon nanomaterials derived from marine waste and functional melanin nanoparticles for biosensors and medical applications [92,99]. Sustainable water management also benefits significantly from biotechnology, with combined technologies for wastewater recycling and producing safe irrigation water [104] as well as bioenergetic processes for recovering organic resources from leachates [10]. Finally, biocatalysts have emerged as essential tools for waste valorization and biomaterial production, with examples including enzymes derived from Aspergillus fumigatus and the sustainable use of exhausted mushroom substrates. These innovations underscore the importance of biotechnological approaches in enhancing the economic viability and sustainability of the bioindustry [21,105].

3. Methodology

This study was conducted through a systematic literature review (SLR) structured according to the PRISMA 2020 (Supplementary Materials) (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) protocol [28]. The objective was to identify recent scientific contributions regarding the application of biotechnology to support circular economy (CE) systems in multiple industrial and environmental contexts.

3.1. Search Strategy and Information Source

The literature search was carried out in December 2024 using the Scopus database, selected for its comprehensive indexing of peer-reviewed scientific publications [106]. The following search string was applied to titles, abstracts, and keywords: “circular economy” AND “biotechnology”, which initially retrieved 495 documents.

Scopus was chosen for its multidisciplinary coverage, robust metadata, and integration with major repositories such as IEEE and Web of Science [106,107]. It is considered more effective than other platforms like Web of Science for bibliometric and interdisciplinary analyses [108], such as the case of sustainability and environmental issues [109]. Although some systematic reviews use multiple databases, studies have shown that using a single, curated database can ensure transparency, replicability, and methodological consistency without compromising quality or comprehensiveness [110,111].

Figure 1 illustrates the growth in academic publications combining circular economy and biotechnology. The number of documents has increased sharply since 2019, with 20.95% of total publications appearing in the last year alone. This trend supports the focus on the 2023–2024 period and underscores the need for an updated synthesis in this rapidly evolving field.

3.2. Inclusion and Exclusion Criteria

To ensure consistency, the following inclusion/exclusion criteria were applied:

• Inclusion criteria:

  o

  Articles written in English;

  o

  Published in 2023 or 2024;

  o

  Peer-reviewed original research;

  o

  Indexed under Environmental Sciences; Chemical Engineering; or Biochemistry, Genetics and Molecular Biology.

• Exclusion criteria:

  o

  Review articles, conference papers, book chapters, or non-peer-reviewed content;

  o

  Studies outside the defined timeframe;

  o

  Articles in other languages;

  o

  Irrelevant thematic focus (unrelated to the CE or biotechnology);

  o

  Duplicate records.

After filtering, 435 records were excluded, and 60 were retained for full-text screening.

3.3. Additional Sources

In addition to the Scopus results, 17 articles were manually selected by the authors based on academic expertise and citation tracking. These studies, although not retrieved by the initial search, were considered highly relevant due to their conceptual or methodological contributions. This brought the total to 77 included articles.

3.4. Selection and Screening Process

The screening was conducted in three stages:

• Title and abstract screening based on CE–biotechnology relevance.
• Full-text assessment for methodological and thematic adequacy.
• Expert validation and complementary search for literature not fully indexed.

All selected documents were organized and analyzed qualitatively.

3.5. Screening and Eligibility Summary

• Title and abstract review: 60 studies passed the initial filters.
• Full-text analysis: These 60 were evaluated in detail.
• Manual additions: 17 studies were added based on references and expert monitoring of the emerging literature. This process followed predefined criteria, ensuring objectivity.

In total, 77 documents were analyzed. The PRISMA 2020 flowchart (Figure 2) summarizes the identification, screening, eligibility, and inclusion stages.

3.6. Thematic Categorization Classification of Studies by Thematic Area

The 77 selected articles were classified into 9 thematic categories:

• Wastewater Treatment and Water Management—Biotechnological solutions for wastewater treatment and water recovery.
• Biopolymer and Bioplastic Production—Development of biodegradable plastics and polymers from renewable sources.
• Biofuel and Bioenergy Production—Conversion of biomass and organic waste into clean energy.
• Bioremediation and Environmental Recovery—Use of microorganisms to decontaminate and rehabilitate polluted environments.
• Circular Economy and Waste Valorization—Strategies for converting waste into high-value products.
• Enzymatic and Microbial Biotechnology—Application of enzymes and microorganisms to optimize industrial processes.
• Applications in the Food Industry and Agriculture—Use of biotechnology to promote sustainability in food production and agriculture.
• Nanotechnology and Advanced Materials—Development of nanomaterials derived from biomass for environmental and industrial applications.
• Industrial Biotechnology and Biorefineries—Integration of industrial bioprocesses for resource optimization.

This categorization supported a structured and comparative analysis identifying trends, challenges, and innovation opportunities.

4. Results

This section presents the main findings from the systematic literature review organized into nine thematic areas that reflect the applications of biotechnology in promoting the CE. The review demonstrates how various sectors have adopted innovative biotechnological solutions to valorize waste, develop materials, and use bioenergy in a more sustainable way.

Table 1. Summary of the 60 articles selected in the systematic review. Source: The authors.

Area	Reference	Title	Research Focus/Main Contributions
1. Wastewater treatment and water management	[49]	Potential for curdlan recovery from aerobic granular sludge	Overview of resource recovery from aerobic granular sludge (AGS) systems, focusing on curdlan biosynthesis.
	[15]	Bioremediation of food and beverage wastewater	Bioremediation of food and beverage wastewater using C. vulgaris.
	[48]	Carbon neutrality in wastewater treatment plants	Integrated biotechnological solution for carbon-neutral wastewater treatment.
	[96]	Development of a wastewater treatment system contaminated with Cr (VI) through vegetable biomass modified with TiO2	Development of a wastewater treatment system for chromium removal using TiO2-modified biomass.
	[104]	Second life of water and wastewater in the context of circular economy	Assessment of recycled water safety using membrane bioreactor technology and storage reservoirs.
	[14]	One-step bioremediation of hypersaline and nutrient-rich food industry process water	Bioremediation of hypersaline food industry process water using a microbial community.
	[10]	Organics recovery from waste activated sludge in-situ driving efficient nitrogen removal	Innovative biotechnology for organics recovery from sludge and nitrogen removal from landfill leachate.
2. Biopolymer and bioplastic production	[44]	Polymer- and alcohol-based three-phase partitioning systems	Development of three-phase partitioning systems for biopolymer separation and recyclability assessment.
	[8]	PHA is not just a bioplastic!	Review of PHA applications beyond bioplastics in various industries.
	[5]	Use of enzymatic hydrolysate from agro-industrial asparagus waste	Production of PHA from asparagus waste using B. thuringiensis.
	[9]	Pilot scale polyhydroxyalkanoates biopolymer production	Review of pilot-scale PHA production using pure cultures and future opportunities.
3. Biofuel and bioenergy production	[103]	Microbial biotechnologies to produce biodiesel and biolubricants	Production of biodiesel and biolubricants from dairy effluents using microbial fermentation.
	[12]	Efficient dark fermentation biohydrogen production	Biohydrogen production from biowaste-derived sugars using Shigella flexneri.
	[112]	Chemicals and fuels from lipid-containing biomass	Review of lipid valorization processes for producing chemicals and fuels from biomass.
	[16]	Microalgae to biodiesel: A novel green conversion method	Novel method for biodiesel production from microalgae using in situ transesterification.
	[47]	From grass to gas and beyond: Anaerobic digestion	Use of anaerobic digestion for biogas production from residual grass.
4. Bioremediation and environmental cleanup	[13]	Exploring the potential of horse amendment for the remediation of HCHs-polluted soils	Use of organic amendments for bioremediation of HCH-polluted soils.
	[113]	A critical review on bioremediation technologies of metal(loid) tailings	Review of bioremediation technologies for metal(loid) tailings and policy implications.
	[65]	Halophilic archaea as tools for bioremediation technologies	Use of halophilic archaea for the bioremediation of saline environments.
	[66]	Fungal bioremediation approaches for the removal of toxic pollutants	Review of fungal bioremediation for toxic pollutant removal and biorefinery applications.
	[27]	Immobilizing white-rot fungi laccase	Immobilization of laccase on bio-derived supports for organochlorine removal.
	[11]	Remediation of brewery wastewater and reuse for β-glucans production	Bioremediation of brewery wastewater and production of β-glucans using basidiomycete fungi.
5. Circular economy and waste valorization	[114]	Fungal behavior and recent developments in bio pulping technology	Advances in bio-pulping technology using fungi for sustainable pulp production.
	[45]	Exploring industrial lignocellulosic waste	Review of lignocellulosic waste sources and their potential for producing high-value molecules.
	[115]	The utilization of Industry 4.0 technologies to enhance the circular economy	Integration of Industry 4.0 technologies in Brazilian FoodTec startups to promote the circular economy.
	[102]	Bibliometric analysis and review of food waste management	Review of sustainable approaches for food waste management and valorization.
	[105]	Recent advances on environmentally sustainable valorization of spent mushroom substrate	Review of sustainable applications for spent mushroom substrate (SMS) in various industries.
	[100]	Biotechnological trends and optimization of Arachis hypogaea residues	Review of groundnut residue valorization for bioproducts and optimization techniques.
	[2]	Waste from the food industry: Innovations in biorefineries	Review of biorefinery innovations for valorizing food industry waste.
	[116]	Valorization of seafood waste: A review of life cycle assessment studies	Review of life cycle assessment studies for seafood waste valorization in biorefineries.
	[117]	Turning waste into resources: A comprehensive review on the valorization of Elodea nuttallii biomass	Review of valorization methods for Elodea nuttallii biomass in various applications.
6. Enzyme and microbial biotechnology	[118]	A review on cellulose degrading microbes and their applications	Review of cellulose-degrading microbes and their applications in biofuel production and bioremediation.
	[86]	Screening of alternative nitrogen sources for sophorolipid production	Optimization of sophorolipid production using agricultural byproducts as nitrogen sources.
	[20]	New biocatalyst produced from fermented biomass	Development of biocatalysts from fermented biomass for enzyme immobilization and aroma synthesis.
	[119]	Biotechnological potential of yeast cell wall	Overview of yeast cell wall components and their biotechnological applications.
	[21]	Bioprospecting CAZymes repertoire of Aspergillus fumigatus	Optimization of hydrolytic enzyme production from lignocellulosic waste using Aspergillus fumigatus.
	[120]	The use of Trichoderma spp. for the bioconversion of agro-industrial waste biomass	Review of Trichoderma spp. for bioconversion of agro-industrial waste via fermentation.
	[36]	Genetic modifications in bacteria for the degradation of synthetic polymers	Review of genetic modifications in bacteria for synthetic polymer degradation.
	[84]	Potential use of frass from edible insect Tenebrio molitor for proteases production	Production of proteases from frass of Tenebrio molitor using solid-state fermentation.
7. Food and agriculture applications	[121]	Potential role of sophorolipids in sustainable food systems	Exploration of sophorolipids as biosurfactants and bioactive agents in the food industry.
	[4]	Bacillus genus industrial applications and innovation	Review of Bacillus applications in various industries and their role in the circular bioeconomy.
	[122]	Significance and role of biotechnological applications in environmental and energy sustainability	Overview of biotechnological applications in the pulp and paper industry for sustainability.
	[1]	Transition to the circular economy: innovative and disruptive production technologies	Analysis of innovative technologies adopted by agribusiness startups for the circular economy transition.
	[123]	How to build a bioeconomic food system	Thematic review on building a bioeconomic food system for sustainability.
	[18]	Comparison of plant biostimulating properties of Chlorella sorokiniana biomass	Comparison of Chlorella sorokiniana biomass for plant biostimulant production.
8. Nanotechnology and advanced materials	[99]	Silane grafted biosourced melanin: a sustainable approach for nanobiosensing applications	Development of sustainable nanobiosensors using biosourced melanin for biomedical applications.
	[92]	Seafood waste derived carbon nanomaterials for removal and detection of food safety hazards	Use of seafood waste-derived carbon nanomaterials for food safety applications.
9. Industrial biotechnology and biorefineries	[3]	Optimization of sustainable processes for the extraction of precious metals from end-of-life printed circuit boards	Sustainable methods for recovering precious metals from electronic waste using biotechnology.
	[97]	Advancements and future directions in waste plastics recycling	Review of innovative chemical processes for plastic recycling and future directions.
	[101]	The phosphorus challenge: Biotechnology approaches for a sustainable phosphorus system	Biotechnological approaches for sustainable phosphorus recovery and management.
	[124]	From pollutants to products: Microbial cell factories driving sustainable biomanufacturing	Role of microbial cell factories in sustainable biomanufacturing and environmental conservation.
	[125]	A systematic review of innovations in tannery solid waste treatment	Review of thermochemical and biological methods for tannery waste treatment.
	[126]	Biocatalysts for biomethanol production	Review of biocatalytic pathways for biomethanol production and future prospects.
	[127]	From waste management to circular economy: Leveraging thermophiles for sustainable growth	Use of thermophilic microbes for waste management and resource optimization.
	[128]	Modern bioeconomy measurement in the green economy paradigm	Analysis of bioeconomy measurement and its integration with green economy principles.
	[17]	Selecting for a high lipid accumulating microalgae culture by dual growth limitation	Optimization of lipid accumulation in microalgae using dual-growth limitation in bioreactors.
	[98]	Biotechnological approach to treat textile dyeing effluents	Review of biotechnological methods for treating textile dyeing effluents.
	[6]	Blue valorization of lignin-derived monomers via reprogramming marine bacterium Roseovarius nubinhibens	Valorization of lignin-derived monomers using the marine bacterium Roseovarius nubinhibens.
	[95]	Synergistic microwave and acidic deep eutectic solvent (DES)-based pretreatment of Theobroma cacao pod husk biomass	Production of xylooligosaccharides from cocoa pod husks using microwave-assisted DES pretreatment.
	[91]	Turning waste into treasure: A new direction for low-cost production of lipid chemicals from Thraustochytrids	Low-cost production of lipid chemicals from Thraustochytrids using waste materials.

Note: Although some studies address multiple aspects, each article has been classified based on its primary focus.

provides an overview of the 60 reviewed articles categorized by their research focus, while

Table 2. Additional articles complementing the review. Source: The authors.

Area	Reference	Title	Research Focus/Main Contributions
Enzymatic and microbial biotechnology	[19]	From nature to industry: Harnessing enzymes for biocatalysis	Reviews the use of natural and engineered enzymes for industrial biocatalysis in sustainable applications.
	[23]	Enzyme Immobilization Technologies and Industrial Applications	Presents innovative methods and materials for enzyme immobilization in industrial environments.
	[37]	Engineered plastic-associated bacteria for biodegradation and bioremediation	Explores engineered bacteria associated with plastics to enhance biodegradation and bioremediation processes.
Wastewater treatment and water management	[75]	Microalgae-mediated bioremediation: Current trends and opportunities—A review	Describes genetically modified microalgae for the removal of industrial pollutants, including heavy metals and nitrates.
Bioremediation and environmental recovery	[129]	Phytoremediation strategies for mitigating environmental toxicants	Compares vermiremediation (earthworms) and phytoremediation (plants) for the degradation of toxic organic pollutants.
	[57]	A review on sustainable approach of bioleaching of precious metals from electronic wastes	Explores bioleaching techniques using microorganisms to extract valuable metals from electronic waste (e-waste) sustainably.
	[67]	Bioengineered microbial strains for detoxification of toxic environmental pollutants	Explores genetically modified microbial strains for the detoxification of various pollutants.
	[69]	Microbial remediation of polluted environment by using recombinant E. coli: a review	Evaluates the use of recombinant E. coli in the bioremediation of industrial contaminants.
Industrial biotechnology and biorefineries	[55]	Bio-Recovery of Metals through Biomining within Circularity-Based Solutions	Integrates biomining and circular economy strategies using GMMs for metal recovery from mining waste.
	[70]	Genetically Modified Organisms and Its Impact on the Enhancement of Bioremediation	Highlights the potential of GMMs to accelerate bioremediation processes.
Biopolymer and bioplastic production	[7]	Advances and challenges in polyhydroxyalkanoates (PHA) production using Halomonas species	Reviews the state of the art in PHA production using Halomonas species, emphasizing sustainable bioplastic alternatives.
	[32]	Waste to wealth: Polyhydroxyalkanoates (PHA) production from food waste for a sustainable packaging paradigm	Demonstrates fermentation routes to convert household food waste into PHAs, promoting the circular bioeconomy.
	[38]	Pilot-scale production of PHAs using pure cultures	Validates the technical and environmental viability of producing PHAs at a pilot scale using pure microbial cultures, thereby contributing to sustainable bioplastic production.
	[39]	Validates the technical and environmental viability of producing PHAs at a pilot scale using pure microbial cultures, thereby contributing to sustainable bioplastic production.	Analyzes industrial capacities and identifies strategic sectors such as agriculture, medicine, and sustainable packaging for the application of bioplastics in the global market.
	[31]	Utilization of chickpea starch waste for PHA production	Demonstrates fermentation routes to convert chickpea starch waste into polyhydroxyalkanoates (PHAs), offering a sustainable alternative to petroleum-based plastics.
Circular bioeconomy and waste valorization	[85]	From waste to food and bioinsecticides: An innovative system integrating Tenebrio molitor bioconversion	Presents an integrated system converting organic waste into food and bioinsecticides through insect bioconversion.
	[87]	Valorization of brewer’s spent grain for sustainable food packaging	Explores the use of spent grain from brewing as a sustainable raw material for food packaging.

complements the analysis with additional articles that explore more emerging and interdisciplinary aspects.

4.1. Characterization of the Results by Thematic Areas

From the systematic review and complementary studies presented in Table 1 and Table 2, it was possible to map the main advances of biotechnology in the promotion of the CE, distributed in several thematic areas. Each area addresses specific challenges and opportunities, highlighting how biotechnological processes can contribute to closing material cycles, recovering resources, and reducing environmental impacts. An integrated synthesis of these areas is presented below, incorporating the main and complementary studies.

4.1.1. Wastewater Treatment and Water Management

This area highlights the application of biotechnological solutions to improve water quality, recover valuable resources, and promote sustainable water reuse. Adekunle et al. provide an overview of resource recovery from aerobic granular sludge (AGS) systems, focusing on the biosynthesis of curdlan, a valuable biopolymer [49]. Najar-Almanzor et al. demonstrate the use of C. vulgaris for the bioremediation of food and beverage wastewater, illustrating the potential of microalgal systems in water treatment [15].

Pasquarelli et al. propose an integrated biotechnological approach to achieve carbon neutrality in wastewater treatment plants, thereby reducing the environmental footprint of these processes [48]. Meanwhile, Sayago & Ballesteros describe the development of a treatment system for wastewater contaminated with chromium (VI), utilizing TiO₂–modified biomass for effective removal [96]. Stankiewicz et al. (2024) assess the safety of recycled water using membrane bioreactor technology and storage reservoirs, emphasizing a second life for water within a CE [104].

Additionally, Wang et al. explore the one-step bioremediation of hypersaline and nutrient-rich wastewater from the food industry through the application of microbial communities [14]. Finally, Zhang et al. [10] introduce an innovative method for recovering organics from waste-activated sludge while achieving efficient nitrogen removal from landfill leachate. Together, these studies underscore the diverse ways in which biotechnology can enhance wastewater treatment and resource recovery, ultimately contributing to a more sustainable water management system [10].

4.1.2. Biopolymer and Bioplastic Production

This thematic area highlights the conversion of agricultural and industrial waste into renewable, biodegradable materials. The studies included in Table 1 demonstrate various approaches to producing PHAs, a class of bioplastics with growing industrial applications. For instance, Antunes et al. developed innovative polymer- and alcohol-based three-phase partitioning systems for the separation and recyclability assessment of biopolymers, emphasizing a process-oriented approach for efficient recovery [44].

In addition, Park et al. provided a comprehensive review of the diverse industrial applications of PHAs, illustrating that these biopolymers are not confined solely to packaging but have wider potential uses [8]. Tello-Cruzado et al. focused on the production of PHAs from asparagus waste using B. thuringiensis, thereby demonstrating a practical application of converting agricultural residues into value-added products [5].

Finally, Wongsirichot reviewed pilot-scale production processes using pure cultures, discussing both the technical and economic viability of PHA production and highlighting future opportunities for scaling up the technology. Together, these studies underscore the transformative potential of biotechnological processes in creating sustainable alternatives to conventional, petroleum-based plastics [9].

4.1.3. Production of Biofuels and Bioenergy

This area focuses on biotechnological innovations for converting various organic waste into renewable energy sources and chemical fuels. Bencresciuto et al. demonstrate the use of microbial biotechnologies to produce biodiesel and biolubricants from dairy effluents via fermentation, showcasing a practical route to generating sustainable fuel alternatives [103].

Chandekar et al. explore efficient dark-fermentation processes for biohydrogen production from biowaste-derived sugars using S. flexneri, highlighting a promising approach to hydrogen energy [12]. Kim et al. review lipid valorization processes for producing chemicals and fuels from lipid-containing biomass, emphasizing the conversion of fats into valuable energy carriers and chemical feedstocks [112].

Oliva et al. present an innovative green conversion method for biodiesel production from microalgae through in situ transesterification, illustrating a sustainable technique for converting algal lipids into biodiesel [16]. Also, Souza et al. report on the use of AD for producing biogas from residual grass, further expanding the spectrum of renewable bioenergy production [47]. Together, these studies underline the potential of biotechnological processes to create a diverse portfolio of renewable fuels and energy products, thereby contributing to a more sustainable energy future.

4.1.4. Bioremediation and Environmental Cleanup

This area focuses on employing biotechnological approaches to degrade persistent pollutants and restore contaminated environments. For instance, Checa-Fernández et al. demonstrate the use of organic amendments derived from equine waste for the remediation of soils contaminated with hexachlorocyclohexane (HCH) [13]. Liu et al. provide a critical review of bioremediation technologies for metal(loid) tailings, discussing both the practical applications and policy implications [113].

Martínez-Espinosa explores the use of halophilic archaea as effective tools for the bioremediation of saline environments [65]. Additionally, Navina et al. review fungal bioremediation strategies for the removal of toxic pollutants and their potential applications in biorefineries [66]. Finally, Serbent et al. discuss the immobilization of white-rot fungi laccase on bio-derived supports as a CE approach for the removal of complex organochlorine compounds [27]. Together, these studies underscore the potential of microbial and fungal systems in providing sustainable solutions for environmental cleanup.

Timm et al. (2024) investigate the bioremediation of brewery wastewater using basidiomycete fungi, demonstrating how this process can simultaneously remove pollutants and produce β-glucans—compounds with various industrial applications [11]. This approach exemplifies the potential of microbial and fungal processes in contributing to a circular bioeconomy by recovering resources and generating additional economic value from waste streams.

4.1.5. Circular Economy and Waste Recovery

This area focuses on converting various waste streams into value products, thereby supporting a CE. Bari et al. review advances in bio-pulping technology using fungi for sustainable pulp production, illustrating how fungal behavior can drive efficient biomass conversion [114]. Cazier et al. provide an extensive review of industrial lignocellulosic waste sources and their potential for producing high-value molecules [45]. da Silva & Sehnem discuss how the integration of Industry 4.0 technologies in Brazilian food tech startups can enhance CE practices [115].

Danya et al. present a bibliometric analysis and review sustainable approaches for food waste management and valorization [102]. Kousar et al. examine recent advances in the environmentally sustainable valorization of spent mushroom substrate across various industries [105], while Ogunkunle & Olusanya explore trends and optimization techniques for valorizing peanut residues [100]. Volpato Maroldi et al. review innovations in biorefineries that transform food industry waste into valuable bio-inputs [2].

Yusoff et al. (2024) assess the life cycle of seafood waste valorization [116], and Zoppi et al. provide a comprehensive review on the valorization methods for Elodea nuttallii biomass [117]. Together, these studies demonstrate that the CE can be significantly advanced through the sustainable recovery of resources from various waste streams, thus reducing environmental impacts and generating economic value.

4.1.6. Enzymatic and Microbial Biotechnology

This thematic area focuses on the development and optimization of biological catalysts and microbial processes for industrial applications. T. Bhatia et al. provide a comprehensive review of cellulose-degrading microbes and their applications in biofuel production and bioremediation [118]. Eras-Muñoz et al. investigate alternative nitrogen sources for sophorolipid production, highlighting the optimization of biosynthesis using agricultural byproducts [86].

Gonçalves et al. report on the development of new biocatalysts, produced from fermented biomass, which are employed for enzyme immobilization and aroma synthesis [20]. Jofre et al. explore the biotechnological potential of yeast cell walls, offering an overview of their components and applications [119]. Joshi et al. focus on bioprospecting the CAZymes repertoire of Aspergillus fumigatus to optimize hydrolytic enzyme production from lignocellulosic waste [21].

Lima et al. review the use of Trichoderma spp. for the bioconversion of agro-industrial waste via fermentation [120]. Martín-González et al. discuss genetic modifications in bacteria to enhance the degradation of synthetic polymers [36]. Finally, Muñoz-Seijas et al. evaluate the potential use of frass from the edible insect Tenebrio molitor for protease production through solid-state fermentation [84]. Collectively, these studies underscore the critical role of enzymes and microbial processes in driving sustainable and efficient industrial bioconversions.

4.1.7. Applications in Food and Agriculture

This thematic area focuses on leveraging biotechnological innovations to enhance sustainability and efficiency in the food and agriculture sectors. Bueno-Mancebo et al. explore the potential role of sophorolipids, a type of biosurfactant with applications in food preservation and emulsification that have gained attention due to their sustainable production from agricultural waste [121].

Herrmann et al. review the industrial applications of the Bacillus genus, highlighting its significant role in driving a circular bioeconomy [4]. Kumar et al. provide an overview of biotechnological applications in the pulp and paper industry, emphasizing their contributions to environmental and energy sustainability [122]. Manganda et al. analyze innovative and disruptive production technologies adopted by agribusiness startups that facilitate the transition to a CE [1].

Mühl et al. discuss strategies for building a sustainable bioeconomic food system [123], while Stirk et al. compare the plant biostimulating properties of Chlorella sorokiniana biomass, underscoring its potential to enhance crop growth [18]. Collectively, these studies demonstrate how biotechnology can transform food production and agricultural practices, reduce waste, and enhance resource efficiency.

4.1.8. Nanotechnology and Advanced Materials

This thematic area focuses on the development of sustainable nanomaterials and advanced sensing technologies with applications in environmental monitoring and food safety. Caldas et al. describe the development of silane-grafted biosourced melanin for nanobiosensing applications, offering a sustainable approach for biomedical uses [99]. Meanwhile, He et al. report on the use of carbon nanomaterials derived from seafood waste for the removal and detection of food safety hazards [92]. Together, these studies highlight how nanotechnology can transform waste into high-value materials that support both environmental and industrial applications.

4.1.9. Industrial Biotechnology and Biorefineries

This thematic area focuses on harnessing biotechnological processes to recover resources, minimize waste, and convert waste streams into valuable products. For instance, Becci et al. describe sustainable methods for extracting precious metals from end-of-life printed circuit boards, demonstrating how biotechnology can recover high-value resources from electronic waste [3].

Chen and Hu review innovative chemical processes for plastic recycling, outlining future directions for turning waste plastics into useful materials [97]. Elser et al. address sustainable phosphorus recovery and management through biotechnological approaches [101], while Gavrilescu explores the role of microbial cell factories in converting pollutants into products, thereby contributing to sustainable biomanufacturing [124]. Jaffari et al. provide a systematic review of innovations in tannery solid waste treatment, integrating thermochemical and biological methods [125].

Further, Kumar Srivastava et al. review biocatalytic pathways for biomethanol production, highlighting prospects for converting waste into fuel [126]. Najar et al. discuss leveraging thermophilic microbes for waste management and resource optimization [127], and Nifatova et al. analyze modern bioeconomy metrics within the green economy paradigm [128].

Policastro et al. focus on optimizing lipid accumulation in microalgae using dual growth limitation [17], while Rahman and Tabassum review biotechnological methods for treating textile dyeing effluents [98]. Additionally, Wei et al. demonstrate the valorization of lignin-derived monomers using genetically modified marine bacteria [6], and Yadav et al. present microwave-assisted deep eutectic solvent pretreatment of cocoa pod husk biomass for the production of xylooligosaccharides [95].

Lastly, Zhang et al. illustrate a low-cost approach to producing lipid chemicals from Thraustochytrids using waste materials. Together, these studies exemplify how industrial biotechnology and biorefineries can transform waste into valuable resources, supporting a sustainable CE [91].

4.1.10. General Summary

Collectively, these findings underscore that while individual technologies and approaches contribute unique benefits, their true potential is realized when integrated within a holistic framework that spans local innovations to industrial symbiosis and supportive policy frameworks.

This comprehensive integration is crucial to reducing dependency on virgin resources, minimizing environmental impacts, and fostering a resilient, sustainable CE. Complementary contributions [32,55,75,129] further reinforce the diversity and potential of biotechnology approaches, pointing to innovative ways that can overcome current and future challenges. This integrated analysis of the thematic areas provides a solid basis for the development of a conceptual framework that aims to drive a CE based on biotechnological solutions.

To enhance comparability and provide a structured synthesis of the biotechnological solutions discussed,

Table 3. Comparative summary of selected biotechnological approaches for the circular economy.

Biotechnological Strategy	Applications	Advantages	Limitations
Wastewater treatment and water management	Wastewater treatment, nutrient and water recovery	Pollution reduction, resource recovery, synergy with other biotechnologies	Requires proper infrastructure; sensitive to organic load variations
Biopolymer and bioplastic production	Packaging, agriculture, medical applications	Biodegradable fossil plastic alternative	High production cost, scalability challenges
Biofuel and bioenergy production	Biomass and waste conversion into biogas, bioethanol, biodiesel	Renewable energy and waste reduction; can integrate with AD	Variable efficiency, need for pretreatment
Bioremediation and environmental recovery	Soil and water decontamination, pollutant removal	Eco-friendly, low-cost, adaptable	Slow process, affected by environmental factors, scalability limitations
Circular economy and waste valorization	Conversion of waste into high-value products (e.g., bioactives)	Waste reduction, added economic value	Variable technical and economic feasibility
Enzymatic and microbial biotechnology	Pollutant degradation, bioproduct synthesis, food industry	High specificity, mild operational conditions	Cost and stability of enzymes, limited reuse
Applications in food industry and agriculture	Biofertilizers, biopesticides, crop enhancement	Sustainable agriculture, reduced agrochemical use	Market acceptance, complex regulatory pathways
Nanotechnology and advanced materials	Smart packaging, controlled release systems, remediation	High reactivity, technological innovation, cross-sector use	High cost, environmental risks not fully understood
Industrial biotechnology and biorefineries	Integrated processes for biomass utilization	Resource efficiency, reduced environmental impact	High technical complexity, investment needs

summarizes the main biotechnological strategies analyzed, highlighting applications, advantages, and limitations associated with each approach reviewed in this study.

As shown in the table, although each approach has specific benefits, its effective application depends on overcoming economic, regulatory, and technological barriers. The combined and context-adapted use of these solutions could accelerate the transition to a circular and sustainable bioeconomy.

5. Discussion

The results of this review reinforce the transformative role of biotechnology in promoting the CE. By integrating biological processes into production systems and waste management, biotechnology offers innovative solutions that close material cycles, optimize the use of resources, and reduce environmental impacts. The main thematic areas identified, their contributions, the challenges faced, and the implications for the future are discussed, culminating in the proposal of a conceptual framework for a biotechnology-driven CE.

5.1. Integration of Biotechnological Solutions

The studies show that biotechnology applications in areas such as wastewater treatment, biopolymer production, AD, and bioremediation are fundamental for creating circular flows of resources. For example, the recovery of curdlan from aerobic granular sludge [49] and the use of microbial communities to treat hypersaline effluents [14] demonstrate how it is possible to reuse water and recover nutrients.

In the production of bioplastics, the conversion of agricultural waste into PHAs [5] opens up new economic opportunities and offers biodegradable alternatives to conventional plastics. This integration not only contributes to the reduction in waste but also encourages innovation and the creation of new business models.

5.2. Sustainability and Innovation

Biotechnology plays a key role in sustainability by balancing economic feasibility with ecological impact. The recovery of precious metals from electronic waste using GMMs [55] and process optimization in the pulp and paper industry [126] are examples of how biotechnology can unite academic advances with industrial demands.

Furthermore, integrated wastewater treatment systems that enable energy recovery and extraction of compounds reinforce the synergy between environmental improvement and revenue generation.

5.3. Emerging Technologies and Their Potential

Among the emerging technologies, microalgae-based systems and nanobiotechnology stand out. Microalgae systems, with their ability to capture CO₂, produce biodiesel and biohydrogen, as well as generate nutraceutical compounds, demonstrate great potential to diversify the energy matrix and reduce the carbon footprint [17,18]. In turn, nanobiotechnology, which uses biological materials to develop biosensors and innovative filter media, improves resource recovery and environmental monitoring [92,99].

However, the scalability of these technologies still depends on technical challenges, such as maintaining ideal growing conditions and ensuring consistent product quality, in addition to the need for regulatory frameworks that stimulate their development.

5.4. Challenges and Barriers

Despite the potential identified, the wide adoption of biotechnological solutions faces significant challenges. Industrial scalability and the lack of clear regulation—especially for technologies involving genetically modified organisms—are obstacles that require strict supervision and public acceptance [98]. The high initial investment and slow adoption by industry and consumers point to the need for tangible benefits and standardized metrics. The implementation of life cycle assessment (LCA) becomes crucial to prove the real sustainability of these technologies [127].

5.5. Implications for the Future

To overcome the challenges and accelerate the adoption of biotechnological solutions, a coordinated effort between governments, industries, academic institutions, and other stakeholders is essential [130]. Clear guidelines, such as subsidies for pilot programs and the construction of specialized infrastructure, are key measures to foster innovation [131].

The integration of digital technologies such as artificial intelligence (AI) and the Internet of Things (IoT) can optimize process control, boosting efficiency in waste and resource management [132]. Strengthening collaboration between laboratories, startups, consolidated industries, and government agencies is essential to transforming pilot initiatives into large-scale industrial applications that bring significant environmental and economic benefits [133].

5.6. Conceptual Framework for a Biotechnology-Based Circular Economy

The proposed framework for a biotechnology-driven CE can be structured in three levels, as displayed in Figure 3:

• Micro Level: Encompasses individual innovations, such as the production of PHAs from agricultural byproducts, which offer alternatives to conventional plastics, and AD, which converts organic waste into biogas and biofertilizers, promoting energy and nutrient recovery [5,8,11,47]. In addition, multifunctional microalgal systems that capture CO₂ and generate bioenergy reinforce this level of innovation.
• Meso Level: Facilitates industrial symbiosis, allowing waste from one sector to be used as raw material in another. Biorefineries, for example, can fractionate residual biomass to produce bioenergy, chemicals, and biomaterials, ensuring the maximum use of available resources [2,10]. In the food sector, the use of biosurfactants and enzymes derived from agro-industrial byproducts can replace synthetic ingredients, reducing waste and increasing process efficiency [21,86].
• Macro Level: Establishes a structural basis for the adoption of biotechnology, incorporating economic guidelines and regulatory policies that encourage sustainable practices. Renewable energy solutions such as microbial biodiesel and carbon-neutral wastewater treatment systems exemplify the connection between biotechnology and climate policies [48,103]. Integration with nanotechnology improves pollutant detection and resource recovery, while mechanisms such as carbon pricing and incentives for waste recovery promote large-scale implementation [123,128].

In summary, the proposed framework (in Figure 3) shows that, although the production of bioplastics and AD is close to commercial adoption, advanced areas such as enzymology and nanotechnology still require significant investments and regulatory support. By aligning technological advances with policies and cross-sector collaboration, it is possible to reduce the dependence on virgin resources and create more resilient and sustainable production systems. This discussion highlights how biotechnology can drive the transition to a CE, providing a robust basis for innovations that promote environmental, economic, and social sustainability. While these innovations show great promise, successful implementation depends on policy support, investment in infrastructure, and societal acceptance, especially in regions with limited technological capacity [134,135].

Figure 3. Biotechnology-based circular economy proposed conceptual framework.

Figure 3. Biotechnology-based circular economy proposed conceptual framework.

6. Conclusions

This study highlights the transformative role of biotechnology in promoting the CE, demonstrating significant advances in areas such as bioplastics, AD, biomining, bioremediation, and microalgal systems, among others. The review shows that biotechnology not only closes resource cycles and reduces waste but also creates new business models and delivers substantial environmental benefits. Whether through the development of biodegradable plastics, the recovery of nutrients and energy, or the creation of innovative nanomaterials for pollution control, biotechnology is emerging as an essential pillar for sustainable transformation. However, the adoption of these biotechnological solutions faces significant challenges, including high initial costs, scalability issues, and fragmented regulatory frameworks.

Overcoming these barriers will require the implementation of political incentives and the sharing of best practices through strategic research and development collaborations. Adequate funding and regulatory harmonization could drive broader and deeper adoption of circular processes mediated by biotechnology. Effective integration of these solutions will necessitate robust governance, accessible financial mechanisms, and a broader acknowledgment of the long-term benefits of the CE. However, further research and stronger cross-sector coordination remain essential to overcoming the technical and sociopolitical implementation barriers. This strategic alignment paves the way for a circular economy driven by biotechnological processes, contributing to a more sustainable, climate-resilient, and socially inclusive economic model.

Limitations and Future Perspectives

Although this review has compiled recent studies to present an updated panorama of biotechnology’s role in the CE, several limitations should be acknowledged. Focusing solely on publications from 2023 and 2024 ensures a current perspective but may overlook earlier discoveries or emerging advances. Additionally, using only the Scopus database might have resulted in omitting relevant articles indexed in other sources. Another limitation lies in the scope of the thematic areas chosen—while key sectors were analyzed, some emerging domains of biotechnology may not have been fully explored.

Future research could expand our understanding of the relationship between biotechnology and the CE by broadening the temporal scope to include earlier studies and emerging innovations. Integrating additional databases would also offer a more comprehensive coverage of the relevant literature. Comparative studies across different regions and countries could help identify the best practices and specific challenges, while interdisciplinary evaluations that combine life cycle analyses, techno-economic studies, and sociopolitical dimensions may provide deeper insights into the viability and acceptance of biotechnological solutions.

Furthermore, investigating financing models and public–private partnerships can contribute to the development of robust frameworks to incentivize the global adoption of biotechnology-based solutions. The potential synergy between biotechnology, artificial intelligence (AI), and the Internet of Things (IoT) also merits exploration, as it may optimize circular processes by reducing operational costs and increasing the efficiency of waste and resource management. Continued research in these areas will help consolidate a truly circular model based on biotechnology, ensuring that this discipline remains central in the quest for sustainable solutions to global environmental and economic challenges.