Bioconversion of waste (water)/residues to bioplastics- A circular bioeconomy approach

Recent Advances in Food Waste Transformations into Essential Bioplastic Materials

Lignocellulose is a major biopolymer in plant biomass with a complex structure and composition. It consists of a significant amount of high molecular aromatic compounds, particularly vanillin, syringeal, ferulic acid, and muconic acid, that could be converted into intracellular metabolites such as polyhydroxyalkanoates (PHA) and hydroxybutyrate (PHB), a key component of bioplastic production. Several pre-treatment methods were utilized to release monosaccharides, which are the precursors of the relevant pathway. The consolidated bioprocessing of lignocellulose-capable microbes for biomass depolymerization was discussed in this study. Carbon can be stored in a variety of forms, including PHAs, PHBs, wax esters, and triacylglycerides. From a biotechnology standpoint, these compounds are quite adaptable due to their precursors' utilization of hydrogen energy. This study lays the groundwork for the idea of lignocellulose valorization into value-added products through several significant dominant pathways.

Exploring polyhydroxyalkanoates biosynthesis using hydrocarbons as carbon source: a comprehensive review

Environmental pollution caused by petrochemical hydrocarbons (HC) and plastic waste is a pressing global challenge. However, there is a promising solution in the form of bacteria that possess the ability to degrade HC, making them valuable tools for remediating contaminated environments and effluents. Moreover, some of these bacteria offer far-reaching potential beyond bioremediation, as they can also be utilized to produce polyhydroxyalkanoates (PHAs), a common type of bioplastics. The accumulation of PHAs in bacterial cells is facilitated in environments with high C/N or C/P ratio, which are often found in HC-contaminated environments and effluents. Consequently, some HC-degrading bacteria can be employed to simultaneously produce PHAs and conduct biodegradation processes. Although bacterial bioplastic production has been thoroughly studied, production costs are still too high compared to petroleum-derived plastics. This article aims to provide a comprehensive review of recent scientific advancements concerning the capacity of HC-degrading bacteria to produce PHAs. It will delve into the microbial strains involved and the types of bioplastics generated, as well as the primary pathways for HC biodegradation and PHAs production. In essence, we propose the potential utilization of HC-degrading bacteria as a versatile tool to tackle two major environmental challenges: HC pollution and the accumulation of plastic waste. Through a comprehensive analysis of strengths and weaknesses in this aspect, this review aims to pave the way for future research in this area, with the goal of facilitating and promoting investigation in a field where obtaining PHAs from HC remains a costly and challenging process.

Bioplastic Production from Agri-Food Waste through the Use of Haloferax mediterranei: A Comprehensive Initial Overview

The research on bioplastics (both biobased and biodegradable) is steadily growing and discovering environmentally friendly substitutes for conventional plastic. This review highlights the significance of bioplastics, analyzing, for the first time, the state of the art concerning the use of agri-food waste as an alternative substrate for biopolymer generation using Haloferax mediterranei. H. mediterranei is a highly researched strain able to produce polyhydroxybutyrate (PHB) since it can grow and produce bioplastic in high-salinity environments without requiring sterilization. Extensive research has been conducted on the genes and pathways responsible for PHB production using H. mediterranei to find out how fermentation parameters can be regulated to enhance cell growth and increase PHB accumulation. This review focuses on the current advancements in utilizing food waste as a substitute for costly substrates to reduce feedstock expenses. Specifically, it examines the production of biomass and the recovery of PHB from agri-food waste. Furthermore, it emphasizes the characterization of PHB and the significance of hydroxyvalerate (HV) abundance in the formation of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) copolymer. The downstream processing options are described, and the crucial factors associated with industrial scale-up are assessed, including substrates, bioreactors, process parameters, and bioplastic extraction and purification. Additionally, the economic implications of various options are discussed.

An investigation of the environmental implications of bioplastics: Recent advancements on the development of environmentally friendly bioplastics solutions

The production and utilization of plastics may prove beneficial, but the environmental impact suggests the opposite. The single-use plastics (SUP) and conventional plastics are harmful to the environment and need prompt disposal. Bioplastics are increasingly being considered as a viable alternative to conventional plastics due to their potential to alleviate environmental concerns such as greenhouse gas emissions and pollution. However, the previous reviews revealed a lack of consistency in the methodologies used in the Life Cycle Assessments (LCAs), making it difficult to compare the results across studies. The current study provides a systematic review of LCAs that assess the environmental impact of bioplastics. The different mechanical characteristics of bio plastics, like tensile strength, Young's modulus, flexural modulus, and elongation at break are reviewed which suggest that bio plastics are comparatively much better than synthetic plastics. Bioplastics have more efficient mechanical properties compared to synthetic plastics which signifies that bioplastics are more sustainable and reliable than synthetic plastics. The key challenges in bioplastic adoption and production include competition with food production for feedstock, high production costs, uncertainty in end-of-life management, limited biodegradability, lack of standardization, and technical performance limitations. Addressing these challenges requires collaboration among stakeholders to drive innovation, reduce costs, improve end-of-life management, and promote awareness and education. Overall, the study suggests that while bioplastics have the potential to reduce environmental impact, further research is needed to better understand their life cycle and optimize their end-of-life (EoL) management and production to maximize their environmental benefits.

Spatial separation of nitrifiers and denitrifiers promotes selection and enrichment of polyhydroxyalkanoates storing mixed cultures fed by crude glycerol and propionate wastewater

Polyhydroxyalkanoates (PHA) recovery from industrial wastewater has been highlighted as a promising strategy for a circular bioeconomy. However, the high and varying level of nitrogen in wastewater makes enrichment of mixed microbial culture (MMC) low efficiency. In this study, spatial separation of nitrifiers and denitrifiers was adopted by adding biocarriers in MMC and decreasing the sludge retention time (SRT) to accelerate the enrichment of PHA-storing MMC fed by mixed wastewater containing glycerol and propionate. Nitrifiers and denitrifiers were sustained on biocarriers, obtaining a high total inorganic nitrogen removal and allowing a more efficient selective pressure of a high carbon and nitrogen ratio (C/N) under low SRT conditions. The maximum PHA cell content and relative abundance of PHA-storing bacteria were increased to 60.51 % (SRT 6 d) and 49.62 % (SRT 6 d) with the decrease of SRT, respectively. This study demonstrates an efficient way to highly enrich PHA-storing MMC from crude glycerol, which provide a relevant technical support for high-efficiency enrichment of PHA-storing bacteria in low C/N wastewater.

Non-fuel applications of bio-oil for sustainability in management of bioresources

Biomass valorization by thermochemical conversion method is a promising and intriguing pathway due to the flexibility of utilizing a diverse group of biomass and biowastes, specific product delivery mechanism through manipulation of process parameters, and wide applicability of the products. Pyrolysis has been viewed as an effective valorization technique to transform biowastes into pyrolytic oil, solid char, and syngas. Syngas is generally fed to the pyrolysis process to generate heat necessary for the pyrolysis process to sustain. Pyrolysis may also be a subsidiary component in a biorefinery system where it draws feedstocks from refinery process residues or the side streams of the refinery operation. In recent times, pyrolysis products have been under intense research for their usability and diverse applicability. Bio-oil's rich chemical makeup has promising potential to be used as an advanced biofuel and is considered as a storehouse of diverse chemical species ranging from green solvents to bioactive chemicals. The current review provides a state of knowledge on non-fuel uses of bio-oil and concludes that the pyrolysis process and products could be a part of the future bioeconomy if designed in a manner that biowastes are transformed into value-added products which replace products of petroleum origin.

Pilot-scale production of mcl-PHA by Pseudomonas citronellolis using acetic acid as the sole carbon source

Medium-chain-length polyhydroxyalkanoates (mcl-PHA) are biobased materials with promising properties for environmentally friendly applications. Due to high production costs, which are related to the cost of the carbon sources combined with conversion insufficiencies, currently only small quantities are produced. This results in a lack of reliable data on properties and application potential for the variety of polymers from different types of production strains. This study investigated the potential for the production of mcl-PHA from volatile fatty acids (VFA) at a larger scale, given their potential as low-cost and sustainable raw material within a carboxylate-platform based biorefinery. Pseudomonas citronellolis (DSMZ 50332) was chosen as the production strain, and acetic acid was selected as the main carbon and energy source. Nitrogen was limited to trigger polymer production, and a fed-batch process using a pH-stat feeding regime with concentrated acid was established. We report successful production, extraction, and characterization of mcl PHA, obtaining a total of 1.76 kg from two 500-litre scale fermentations. The produced polymer was identified as a copolymer of 3-hydroxydecanoate (60.7%), 3-hydroxyoctanoate (37.3%), and 3-hydroxyhexanoate (2.0%) with a weight average molecular weight (Mw) of 536 kDa. NMR analysis indicates the presence of unsaturated side chains, which may offer additional possibilities for modification. The results confirm that there is a potential to produce significant amounts of mcl-PHA with interesting rubber-like properties from waste-derived VFA.

A comprehensive review of micro- and nano-plastics in the atmosphere: Occurrence, fate, toxicity, and strategies for risk reduction

Micro- and nano-plastics (MNPs) have received considerable attention over the past 10 years due to their environmental prevalence and potential toxic effects. With the increase in global plastic production and disposal, MNP pollution has become a topic of emerging concern. In this review, we describe MNPs in the atmospheric environment, and potential toxicological effects of exposure to MNPs. Studies have reported the occurrence of MNPs in outdoor and indoor air at concentrations ranging from 0.0065 items m-3 to 1583 items m-3. Findings have identified plastic fragments, fibers, and films in sizes predominantly <1000 μm with polyamide (PA), polyester (PES), polyethylene terephthalate (PET), polypropylene (PP), rayon, polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC), polyacrylonitrile (PAN), and ethyl vinyl acetate (EVA) as the major compounds. Exposure through indoor air and dust is an important pathway for humans. Airborne MNPs pose health risks to plants, animals, and humans. Atmospheric MNPs can enter organism bodies via inhalation and subsequent deposition in the lungs, which triggers inflammation and other adverse health effects. MNPs could be eliminated through source reduction, policy/regulation, environmental awareness and education, biodegradable materials, bioremediation, and efficient air-filtration systems. To achieve a sustainable society, it is crucial to implement effective strategies for reducing the usage of single-use plastics (SUPs). Further, governments play a pivotal role in addressing the pressing issue of MNPs pollution and must establish viable solutions to tackle this significant challenge.

Synthesis and commercialization of bioplastics: Organic waste as a sustainable feedstock

Substituting synthetic plastics with bioplastics, primarily due to their inherent biodegradable properties, represents a highly effective strategy to address the current global issue of plastic waste accumulation in the environment. Advances in bioplastic research have led to the development of materials with improved properties, enabling their use in a wide range of applications in major commercial sectors. Bioplastics are derived from various natural sources such as plants, animals, and microorganisms. Polyhydroxyalkanoate (PHA), a biopolymer synthesized by bacteria through microbial fermentation, exhibits physicochemical and mechanical characteristics comparable to those of synthetic plastics. In response to the growing demand for these environmentally friendly plastics, researchers are actively investigating various cleaner production methods, including modification or derivatization of existing molecules for enhanced properties and new-generation applications to expand their market share in the coming decades. By 2026, the commercial manufacturing capacity of bioplastics is projected to reach 7.6 million tonnes, with Europe currently holding a significant market share of 43.5 %. Bioplastics are predominantly utilized in the packaging industry, indicating a strong focus of their application in the sector. With the anticipated rise in bioplastic waste volume over the next few decades, it is crucial to comprehend their fate in various environments to evaluate the overall environmental impact. Ensuring their complete biodegradation involves optimizing waste management strategies and appropriate disposal within these facilities. Future research efforts should prioritize exploration of their end-of-life management and toxicity assessment of degradation products. These efforts are crucial to ensure the economic viability and environmental sustainability of bioplastics as alternatives to synthetic plastics.

Autotrophic production of polyhydroxyalkanoates using acidogenic-derived H2 and CO2 from fruit waste

The environmental concerns regarding fossil plastics call for alternative biopolymers such as polyhydroxyalkanoates (PHAs) whose manufacturing costs are however still too elevated. Autotrophic microbes like Cupriavidus necator, able to convert CO2 and H2 into PHAs, offer an additional strategy. Typically, the preferred source for CO2 and H2 are expensive pure gases or syngas, which has toxic compounds for most PHAs-accumulating strains. In this work, for the first time, H2 and CO2 originating from an acidogenic reactor were converted autotrophically into poly(3-hydroxybutyrate) P(3HB). During the first stage, a mixed microbial community continuously catabolized melon waste into H2 (26.7 %) and CO2 (49.2 %) that were then used in a second bioreactor by C. necator DSM 545 to accumulate 1.7 g/L P(3HB). Additionally, the VFAs (13 gCOD/L) produced during acidogenesis were processed into 2.7 g/L of P(3HB-co-3HV). This is the first proof-of-concept of using acidogenic-derived H2 and CO2 from fruit waste to produce PHAs.

Production of polyhydroxyalkanoates using sewage and cheese whey

Recently, polyhydroxyalkanoates (PHAs) have been produced using raw sewage in our laboratory; however, the production concentrations are low. Therefore, this study aimed to enhance PHA production by applying different strategies. PHA production was higher in sewage-containing medium than in mineral salt medium and was enhanced 22-fold after glucose supplementation. A relatively high degree of glucose consumption (83.6 ± 1.59 %) was also achieved. Bacteria incubated with cheese whey diluted with sewage showed higher PHA production than bacteria incubated with cheese whey diluted with distilled water did. The expression of the PHA synthase gene (phaC) was evaluated via real-time polymerase chain reaction using low- and high-carbon-containing sewage. Relatively higher phaC expression levels were observed in high-carbon-containing sewage but at lower nitrogen concentrations. The characteristics of the produced PHA were comparable to those of standard PHA. Therefore, this study revealed that the bacterium Bacillus sp. CYR1 can produce PHA from low- or high-carbon-containing wastewater.

Recent updates to microbial production and recovery of polyhydroxyalkanoates

The increasing use of synthetic polymers and their disposal has raised concern due to their adverse effects on the environment. Thus, other sustainable alternatives to synthetic plastics have been sought, such as polyhydroxyalkanoates (PHAs), which are promising microbial polyesters, mainly due to their compostable nature, biocompatibility, thermostability, and resilience, making this biopolymer acceptable in several applications in the global market. The large-scale production of PHAs by microorganisms is still limited by the high cost of production compared to conventional plastics. This review reports some strategies mentioned in the literature aimed at production and recovery, paving the way for the bio-based economy. For this, some aspects of PHAs are addressed, such as synthesis, production systems, process control using by-products from industries, and advances and challenges in the downstream. The bioplastics properties made them a prime candidate for food, pharmaceutical, and chemical industrial applications. With this paper, it is possible to see that biodegradable polymers are promising materials, mainly for reducing the pollution produced by polymers derived from petroleum.

Livestock and poultry farm wastewater treatment and its valorization for generating value-added products: Recent updates and way forward

Livestock and poultry wastewater poses a potent risk factor for environmental pollution accelerating disease load and premature deaths. It is characterized by high chemical oxygen demand, biological oxygen demand, suspended solids, heavy metals, pathogens, and antibiotics, among other contaminants. These contaminants have a negative impact on the quality of soil, groundwater, and air, and is a potential hazard to human health. Depending on the specific characteristics of wastewater, such as the type and concentration of pollutants present; several physical, chemical and biological strategies have been developed for wastewater treatment. This review aims at providing comprehensive overview of the profiling of livestock wastewater from the dairy, swine and poultry sub-sectors along with the biological (annamox and genetically modified bacteria) and physico-chemical treatment methodologies, and valorisation for the generation of value-added products such as bioplastics, biofertilizers, biohydrogen and microalgal-microbial fuel cells. Additionally, future perspectives for efficient and sustainable wastewater treatment are contemplated.

Environmental safety of second and third generation bioplastics in the context of the circular economy

Bioplastics derived from organic materials other than crude oil are often suggested as sustainable solutions for tackling end-of-life plastic waste, but little is known of their ecotoxicity to aquatic species. Here, we investigated the ecotoxicity of second and third generation bioplastics toward the freshwater zooplankton Daphnia magna. In acute toxicity tests (48 h), survival was impacted at high concentrations (g.L^-1 range), within the range of salinity-induced toxicity. Macroalgae-derived bioplastic induced hormetic responses under chronic exposure (21 d). Most biological traits were enhanced from 0.06 to 0.25 g.L^-1 (reproduction rate, body length, width, apical spine, protein concentration), while most of these traits returned to controls level at 0.5 g.L^-1. Phenol-oxidase activity, indicative of immune function, was enhanced only at the lowest concentration (0.06 g.L^-1). We hypothesise these suggested health benefits were due to assimilation of carbon derived from the macroalgae-based bioplastic as food. Polymer identity was confirmed by infra-red spectroscopy. Chemical analysis of each bioplastic revealed low metal abundance whilst non target exploration of organic compounds revealed trace amounts of phthalates and flame retardants. The macroalgae-bioplastic disintegrated completely in compost and biodegraded up to 86 % in aqueous medium. All bioplastics acidified the test medium. In conclusion, the tested bioplastics were classified as environmentally safe. Nonetheless, a reasonable end-of-life management of these safer-by-design materials is advised to ensure the absence of harmful effects at high concentrations, depending on the receiving environment.

Production of polyhydroxyalkanoates from renewable resources: a review on prospects, challenges and applications

Bioplastics replace synthetic plastics of petrochemical origin, which contributes challenge to both polymer quality and economics. Novel polyhydroxyalkanoates (PHA)-composite materials, with desirable product quality, could be developed, thus targeting the global plastics market, in the coming years. It is possible that PHA can be a greener substitute for their petroleum-based competitors since they are simply decomposed, which may lessen the pressure on municipal and industrial waste management systems. PHA production has proven to be the bottleneck in industrial application and commercialization because of the high price of carbon substrates and downstream processes required to achieve reliability. Bacterial PHA production by these municipal and industrial wastes, which act as a cheap, renewable carbon substrate, eliminates waste management hassles and acts as an efficient substitute for synthetic plastics. In the present review, challenges and opportunities related to the commercialization of polyhydroxyalkanoates are discussed and presented. Moreover, it discusses critical steps of their production process, feedstock evaluation, optimization strategies, and downstream processes. This information may provide us the complete utilization of bacterial PHA during possible applications in packaging, nutrition, medicine, and pharmaceuticals.

Trends and challenges in the valorization of kitchen waste to polyhydroxyalkanoates

Kitchen waste (KW) is frequently available for free or with a negative cost due to its huge production. It contains a large proportion of organic substances, especially fermentable sugars, which can be used for bioplastic (polyhydroxyalkanoates or PHA) synthesis. Nevertheless, due to the difficulties in processing, various pre-treatments of KW are being investigated to enhance the concentration of simple sugars released during its hydrolysis. The effective use of KW will help in minimizing the issues of its inappropriate disposal. However, the review on KW to bioplastic synthesis is rarely reported in the literature. Hence, this particular review provides a comprehensive summary of the updated research developments in KW valorization and its potency as a feedstock for PHAs synthesis. Additionally, the impacts of KW, its availability, the necessary pre-treatments for the biopolymerization process, as well as the prospects and challenges for industrially generating sustainable PHAs, are critically discussed.

Polyhydroxyalkanoate Production from Fruit and Vegetable Waste Processing

Traditional plastics represent a tremendous threat to the environment because of increases in polluting manufacturing as well as their very extended degradation time. Polyhydroxyalkanoates (PHAs) are polymers with similar performance to plastic but are compostable and synthesizable from renewable sources and therefore could be a replacement for fossil-based plastics. However, their production costs are still too high, thus demanding the investigation of new and cheap substrates. In this sense, agricultural wastes are attractive because they are inexpensive and largely available. Specifically, fruit and vegetables are rich in sugars that could be fermented into PHAs. In this work two strains, Cupriavidus necator DSM 545 and Hydrogenophaga pseudoflava DSM 1034, well-known PHA-producing microbes, were screened for their ability to grow and accumulate PHAs. Ten different fruit and vegetable processing waste streams, never before reported in combination with these strains, were tested. Residues from red apple and melon were found to be the most suitable feedstocks for PHA production. Under specific selected conditions, C. necator DSM 545 accumulated up to 7.4 and 4.3 g/L of 3-hydroxybutyrate (3HB) from red apple and melon, respectively. Copolymer production was also obtained from melon. These results confirm the attractiveness of food processing waste as a promising candidate for PHA production. Ultimately, these novel substrates draw attention for future studies on process optimization and upscaling with C. necator.

Production of polyhydroxyalkanoates containing monomers conferring amorphous and elastomeric properties from renewable resources: Current status and future perspectives

Petrochemical-based plastics cause environmental pollution and threaten humans and ecosystems. Polyhydroxyalkanoate (PHA) is considered a promising alternative to nondegradable plastics since it is eco-friendly and biodegradable polymer having similar properties to conventional plastics. PHA's material properties are generally determined by composition and type of monomers in PHA. PHA can be designed in tailor-made manner for their suitable application areas. Among many monomers in PHAs, ω-hydroxalkanoates such as 3-hydroxypropionate (3HP), 4-hydroxybutyrate (4HB), 5-hydroxyvalerate (5HV), and 6-hydroxyhexanoate (6HHx) and medium-chain-length 3-hydroxyalkanoate such as 3-hydroxyhexanoate (3HHx) and 4-hydroxyvalerate (4HV), have been examined as potential monomers able to confer amorphous and elastomer properties when these are incorporated as comonomer in poly(3-hydroxybutyrate) copolymer that has 3HB as main monomer along with comonomers in different monomer fraction. Herein, recent advances in production of PHAs designed to have amorphous and elastomeric properties from renewable sources such as lignocellulose, levulinic acid, crude glycerol, and waste oil are discussed.

Production and recovery of polyhydroxyalkanoates (PHA) from waste streams - A review

Polyhydroxyalkanoates (PHA) are the more attractive sustainable green plastic, and it has the potential to replace petroleum-based plastics (PBP) in the global market. Recently, most of the developed and developing countries have banned the use of traditional PBP. This increases the demand for green plastic production and positively impacts the global market. Producing green plastic from various waste streams such as whey, animal, and crude glycerol will be eco-friendly and cost-effective. However, the factors influencing the environmental sustainability of PHA production from different waste streams are still unclear. This review could be reinforced concrete to researchers to gather deep knowledge on techno-economic analysis, life-cycle assessment, environmental and ecological risks caused during PHA production from different waste streams.

Recent advances in biogas production using Agro-Industrial Waste: A comprehensive review outlook of Techno-Economic analysis

Agrowaste sources can be utilized to produce biogas by anaerobic digestion reaction. Fossil fuels have damaged the environment, while the biogas rectifies the issues related to the environment and climate change problems. Techno-economic analysis of biogas production is followed by nutrient recycling, reducing the greenhouse gas level, biorefinery purpose, and global warming effect. In addition, biogas production is mediated by different metabolic reactions, the usage of different microorganisms, purification process, upgrading process and removal of CO₂ from the gas mixture techniques. This review focuses on pre-treatment, usage of waste, production methods and application besides summarizing recent advancements in biogas production. Economical, technical, environmental properties and factors affecting biogas production as well as the future perspective of bioenergy are highlighted in the review. Among all agro-industrial wastes, sugarcane straw produced 94% of the biogas. In the future, to overcome all the problems related to biogas production and modify the production process.

Emerging challenges for the agro-industrial food waste utilization: A review on food waste biorefinery

Modernization and industrialization has undoubtedly revolutionized the food and agro-industrial sector leading to the drastic increase in their productivity and marketing thereby accelerating the amount of agro-industrial food waste generated. In the past few decades the potential of these agro-industrial food waste to serve as bio refineries for the extraction of commercially viable products like organic acids, biochemical and biofuels was largely discussed and explored over the conventional method of disposing in landfills. The sustainable development of such strategies largely depends on understanding the techno economic challenges and planning for future strategies to overcome these hurdles. This review work presents a comprehensive outlook on the complex nature of agro-industrial food waste and pretreatment methods for their valorization into commercially viable products along with the challenges in the commercialization of food waste bio refineries that need critical attention to popularize the concept of circular bio economy.

Pivotal role of municipal wastewater resource recovery facilities in urban agriculture: A review

Urban agriculture provides a promising, comprehensive solution to water, energy, and food scarcity challenges resulting from the population growth, urbanization, and the accelerating effects of anthropogenic climate change. Their close access to consumers, profitable business models, and important roles in educational, social, and physical entertainment benefit both developing and developed nations. In this sense, Urban Water Resource Reclamation Facilities (WRRFs) can play a pivotal role in the sustainable implementation of urban agriculture. Reclaimed water as a recovered resource has less supply variability and in certain cases can be of higher quality than other water sources used in agriculture. Another recovered resource, namely, biosolids, as byproduct from wastewater treatment can be put to beneficial use as fertilizers, soil amendments, and construction material additives. The renewable electricity, heat, CO2, and bioplastics produced from WRRFs can also serve as essential resources in support of urban agriculture operation with enhanced sustainability. In short, this review exhibits a holistic picture of the state-of-the-art of urban agriculture in which WRRFs can potentially play a pivotal role. PRACTITIONER POINTS: Reclaimed water can be of higher quality than other sources used in urban agriculture. Biosolids can be put to beneficial use as fertilizers, soil amendments, and construction material additives. The renewable electricity, heat, CO2, and bioplastics produced can also serve as essential resources in support of urban agriculture.

Review of the Developments of Bacterial Medium-Chain-Length Polyhydroxyalkanoates (mcl-PHAs)

Synthetic plastics derived from fossil fuels—such as polyethylene, polypropylene, polyvinyl chloride, and polystyrene—are non-degradable. A large amount of plastic waste enters landfills and pollutes the environment. Hence, there is an urgent need to produce biodegradable plastics such as polyhydroxyalkanoates (PHAs). PHAs have garnered increasing interest as replaceable materials to conventional plastics due to their broad applicability in various purposes such as food packaging, agriculture, tissue-engineering scaffolds, and drug delivery. Based on the chain length of 3-hydroxyalkanoate repeat units, there are three types PHAs, i.e., short-chain-length (scl-PHAs, 4 to 5 carbon atoms), medium-chain-length (mcl-PHAs, 6 to 14 carbon atoms), and long-chain-length (lcl-PHAs, more than 14 carbon atoms). Previous reviews discussed the recent developments in scl-PHAs, but there are limited reviews specifically focused on the developments of mcl-PHAs. Hence, this review focused on the mcl-PHA production, using various carbon (organic/inorganic) sources and at different operation modes (continuous, batch, fed-batch, and high-cell density). This review also focused on recent developments on extraction methods of mcl-PHAs (solvent, non-solvent, enzymatic, ultrasound); physical/thermal properties (Mw, Mn, PDI, Tm, Tg, and crystallinity); applications in various fields; and their production at pilot and industrial scales in Asia, Europe, North America, and South America.

The Determinants of the Growth of the European Bioplastics Sector—A Fuzzy Cognitive Maps Approach

The extensive use of plastics and the environmental burden associated with their disposal have attracted the attention of scientists, politicians and citizens in Europe. In this frame, the EU has adopted a European Strategy for Plastics aiming, on the one hand, at reducing the use of plastic and, on the other hand, promoting their reuse in the context of a circular economy directly linked with the recently adopted Bioeconomy Strategy. Bioplastics could be an alternative to the conventional plastics, but they still have a limited share in the market. In this paper, Fuzzy Cognitive Maps (FCMs), a soft computing technique for analysing complex decision-making problems, is applied to identify the factors acting as drivers or barriers towards a bio-based plastics industry, their relative importance and the interactions between them. Experts with diverse backgrounds (technical experts, policy makers, industry executives) were interviewed in order to capture their perceptions and create a collective FCM capturing the strong and the weak points of the system. The collective FCM has a total number of 38 factors, which reflect the different approaches and knowledge of the experts. Overall, the “bio-based plastics” system is influenced mainly by the following factors: “EU Legislation”, “Monomers purity”, “Properties of the product”, “Recycling potential”, “Research & Development”, “National Legislation” and “Production cost”. The effect of the most significant political, social and techno-economic factors on the potential growth of the bioplastics sector has also been examined via simulations. The analysis demonstrated that the model is affected more (is more sensitive) to shifts in technoeconomic factors.

The Use of Baikal Psychrophilic Actinobacteria for Synthesis of Biologically Active Natural Products from Sawdust Waste

One of the relevant areas in microbiology and biotechnology is the study of microorganisms that induce the destruction of different materials, buildings, and machines and lead to negative effects. At the same time, the positive ecological effects of degradation can be explained by the detoxication of industrial and agricultural wastes, chemical substances, petroleum products, xenobiotics, pesticides, and other chemical pollutants. Many of these industrial wastes include hard-to-degrade components, such as lignocellulose or plastics. The biosynthesis of natural products based on the transformation of lignocellulosic wastes is of particular interest. One of the world’s unique ecosystems is presented by Lake Baikal. This ecosystem is characterized by the highest level of biodiversity, low temperatures, and a high purity of the water. Here, we studied the ability of several psychrophilic representatives of Baikal Actinobacteria to grow on sawdust wastes and transform them into bioactive natural products. Different strains of both widely spread genus of Actinobacteria and rare genera of Actinobacteria were tested. We used the LC-MS methods to show that Actinobacteria living in sawmill wastes can produce both known and novel natural products with antibiotic activity. We demonstrated that the type of sawmill wastes and their concentration influence the Actinobacteria biosynthetic potential. We have shown for the first time that the use of Baikal psychrophilic microorganisms as a factory for biodegradation is applicable for the transformation of lignocellulosic wastes. Thus, the development of techniques for screening novel natural products leads to an elaboration on the active ingredients for novel drugs.

Promising Developments in Bio-Based Products as Alternatives to Conventional Plastics to Enable Circular Economy in Ukraine

Transforming the plastic industry toward producing more sustainable alternatives than conventional plastics, as an essential enabler of the bio-based circular economy (CE), requires reinforcing initiatives to drive solutions from the lab to the market. In this regard, startups and ideation and innovation events can potentially play significant roles in consolidating efforts and investments by academia and industry to foster bio-based and biodegradable plastic-related developments. This study aimed to present the current trends and challenges of bioplastics and bio-based materials as sustainable alternatives for plastics. On this basis, having conducted a systematic literature review, the seminal research themes of the bio-based materials and bioplastics literature were unfolded and discussed. Then, the most recent developments of bio-based sustainable products in Ukraine, as alternatives to petroleum-based plastics, that have gained publicity through local startup programs and hackathons were presented. The findings shed light on the potential of the bio-based sector to facilitate the CE transition through (i) rendering innovative solutions most of which have been less noticed in academia before; (ii) enhancing academic debate and bridging the gap between developers, scholars, and practitioners within the plastic industry toward creating circularity across the supply chain; (iii) identifying the main challenges and future perspectives for further investigations in the future.

Cell Retention as a Viable Strategy for PHA Production from Diluted VFAs with Bacillus megaterium

The production of biodegradable and biocompatible materials such as polyhydroxyalkanoates (PHAs) from waste-derived volatile fatty acids (VFAs) is a promising approach towards implementing a circular bioeconomy. However, VFA solutions obtained via acidification of organic wastes are usually too diluted for direct use in standard batch or fed-batch processes. To overcome these constraints, this study introduces a cell recycle fed-batch system using Bacillus megaterium uyuni S29 for poly(3-hydroxybutyrate) (P3HB) production from acetic acid. The concentrations of dry cell weight (DCW), P3HB, acetate, as well as nitrogen as the limiting substrate component, were monitored during the process. The produced polymer was characterized in terms of molecular weight and thermal properties after extraction with hypochlorite. The results show that an indirect pH-stat feeding regime successfully kept the strain fed without prompting inhibition, resulting in a dry cell weight concentration of up to 19.05 g/L containing 70.21% PHA. After appropriate adaptations the presented process could contribute to an efficient and sustainable production of biopolymers.

Trends in mitigation of industrial waste: Global health hazards, environmental implications and waste derived economy for environmental sustainability

Majority of industries, in order to meet the technological development and consumer demands generate waste. The untreated waste spreads out toxic and harmful substances in the environment which serves as a breeding ground for pathogenic microorganisms thus causing severe health hazards. The three industrial sectors namely food, agriculture, and oil industry are among the primary organic waste producers that affect urban health and economic growth. Conventional treatment generates a significant amount of greenhouse gases which further contributes to global warming. Thus, the use of microbes for utilization of this waste, liberating CO₂ offers an indispensable tool. The simultaneous production of value-added products such as bioplastics, biofuels, and biosurfactants increases the economics of the process and contributes to environmental sustainability. This review comprehensively summarized the composition of organic waste generated from the food, agriculture, and oil industry. The linkages between global health hazards of industrial waste and environmental implications have been uncovered. Stare-of-the-art information on their subsequent utilization as a substrate to produce value-added products through bio-routes has been elaborated. The research gaps, economical perspective(s), and future research directions have been identified and discussed to strengthen environmental sustainability.

Current application of algae derivatives for bioplastic production: A review

Improper use of conventional plastics poses challenges for sustainable energy and environmental protection. Algal derivatives have been considered as a potential renewable biomass source for bioplastic production. Algae derivatives include a multitude of valuable substances, especially starch from microalgae, short-chain length polyhydroxyalkanoates (PHAs) from cyanobacteria, polysaccharides from marine and freshwater macroalgae. The algae derivatives have the potential to be used as key ingredients for bioplastic production, such as starch and PHAs or only as an additive such as sulfated polysaccharides. The presence of distinctive functional groups in algae, such as carboxyl, hydroxyl, and sulfate, can be manipulated or tailored to provide desirable bioplastic quality, especially for food, pharmaceutical, and medical packaging. Standardizing strains, growing conditions, harvesting and extracting algae in an environmentally friendly manner would be a promising strategy for pollution control and bioplastic production.

Valorization of lipid-rich wastewaters: A theoretical analysis to tackle the competition between polyhydroxyalkanoate and triacylglyceride-storing populations

The lipid fraction of the effluents generated in several food-processing activities can be transformed into polyhydroxyalkanoates (PHAs) and triacylglycerides (TAGs), through open culture biotechnologies. Although competition between storing and non-storing populations in mixed microbial cultures (MMCs) has been widely studied, the right selective environment allowing for the robust enrichment of a community when different types of accumulators coexist is still not clear. In this research, comprehensive metabolic analyses of PHA and TAG synthesis and degradation, and concomitant respiration of external carbon, were used to understand and explain the changes observed in a laboratory-scale bioreactor fed with the lipid-rich fraction (mainly oleic acid) of a wastewater stream produced in the fish-canning industry. It was concluded that the mode of oxygen, carbon, and nitrogen supply determines the enrichment of the culture in specific populations, and hence the type of intracellular compounds preferentially accumulated. Coupled carbon and nitrogen feeding regime mainly selects for TAG producers whereas uncoupled feeding leads to PHA or TAG production function of the rate of carbon supply under specific aeration rates and feast and famine phases lengths.

Bioconversion of organic wastes into value-added products: A review

Rapid urbanization has increased the demand for food, feed, and chemicals that have in turn augmented the use of fossil-based resources and generation of organic waste. Owning to the characteristics like high abundance, renewability, and ease of accessibility, valorization of organic wastes serves as a potential solution for waste management issues. Several industrial wastes, due to their organic and nutrient-rich composition, have been utilized as a resource for the production of value-added products such as biofuels, biopesticides, biohydrogen, enzymes, and bioplastics via microbial fermentation processes. The process consists of pre-treatment of the waste biomass, production of value-added product in reactors and downstream processing for product's recovery. The integration of new comprehensive technologies for organic waste utilization will also stimulate the transition towards a circular economy. Therefore, the feasibility and sustainability of the production of various value-added products from biowastes and byproduct streams will be discussed in the present review.

Mechanical properties of fibre/ filler based poly(Lactic Acid) (Pla) composites : A brief review

Being a biodegradable polymer, poly(lactic acid) (PLA) based composites receive greater preference over non-biodegradable plastics. Poly(lactic acid) has to find its place in various applications such as polymer composites, agriculture, biomedical, etc. Polymer composites based on PLA possess comparable mechanical strength, endurance, flexibility and endures future opportunities. Several combinations of natural fibers and filler-based PLA composites have been fabricated and investigated for physical and mechanical changes. Moreover, several biopolymers and compatibilizers are added to PLA to provide rigidity. The paper presents a tabulated review of the various natural fiber/filter-based PLA composites and the preparation and outcomes. In addition, enhancement made by the reinforcement of nano filler in the PLA are also discussed in brief. The significance of PLA in the biomedical application has been discussed in brief. The paper also shed lights in the social and economic aspects of PLA.

A review on production of polyhydroxyalkanoate (PHA) biopolyesters by thermophilic microbes using waste feedstocks

Polyhydroxyalkanoates (PHAs) are produced by numerous microbes as a subcellular energy source. Despite of their diverse applications, exorbitant production cost limits their commercial synthesis. Apart from various cost determining factors such as cost-effective feedstocks or economic recovery methods, the use of appropriate bacteria holds the key to reduce the fermentation economics. Extremophiles, especially thermophilic PHA producers, could make the bioprocess economically viable by reducing the production cost in several aspects. Using variety of waste feedstocks as carbon substrates could open the way for the valorisation of industrial waste streams and cost-effective PHA production. Therefore, the article critically reviews the current knowledge of the synthesis of PHA polyesters in thermophilic conditions. Additionally, it summarises several studies on thermophilic PHA producing bacteria grown on various waste substrates. To conclude, the paper focuses on screening and recovery methods as well as technical challenges in thermophilic PHA production.

Exploring the feasibility of nitrous oxide reduction and polyhydroxyalkanoates production simultaneously by mixed microbial cultures

Nitrous oxide (N₂O), as a powerful greenhouse gas, has drawn increasing attention in recent years and different strategies for N₂O reduction were explored. In this study, a novel strategy for valuable polyhydroxyalkanoates (PHA) production coupling with N₂O reduction by mixed microbial cultures (MMC) using different substrates was evaluated. Results revealed that N₂O was an effective electron acceptor for PHA production. The highest PHA yield (0.35 Cmmol PHA/Cmmol S) and PHA synthesis rate (227.47 mg PHA/L/h) were obtained with acetic acid as substrate. Low temperature (15℃) and pH of 8.0 were beneficial for PHA accumulation. Results of the thermogravimetric analysis showed that PHA produced with N₂O as electron acceptor has better thermal stability (melting temperature of 99.4℃ and loss 5% weight temperature of 211.4℃). Our work opens up new avenues for simultaneously N₂O reduction and valuable bioplastic production, which is conducive to resource recovery and climate protection.

Burkholderia sacchari (synonym Paraburkholderia sacchari): An industrial and versatile bacterial chassis for sustainable biosynthesis of polyhydroxyalkanoates and other bioproducts

This is the first review presenting and discussing Burkholderia sacchari as a bacterial chassis. B. sacchari is a distinguished polyhydroxyalkanoates producer strain, with low biological risk, reaching high biopolymer yields from sucrose (0.29 g/g), and xylose (0.38 g/g). It has great potential for integration into a biorefinery using residues from biomass, achieving 146 g/L cell dry weight containing 72% polyhydroxyalkanoates. Xylitol (about 70 g/L) and xylonic acid [about 390 g/L, productivity 7.7 g/(L.h)] are produced by the wild-type B. sacchari. Recombinants were constructed to allow the production and monomer composition control of diverse tailor-made polyhydroxyalkanoates, and some applications have been tested. 3-hydroxyvalerate and 3-hydroxyhexanoate yields from substrate reached 80% and 50%, respectively. The genome-scale reconstruction of its metabolic network, associated with the improvement of tools for genetic modification, and metabolic fluxes understanding by future research, will consolidate its potential as a bioproduction chassis.

Concomitant production of value-added products with polyhydroxyalkanoate (PHA) synthesis: A review

The concern over the damaging effects of petrochemical plastics has inspired innumerable researchers to synthesize green plastics. Polyhydroxyalkanoates (PHAs) are promising candidates as they are biodegradable and possess characteristics similar to conventional plastics. However, their large-scale production and market application still have a long way to go due to the high production cost associated. Approaches like using industrial wastes as substrates and developing green strategies for PHA extraction during downstream processing have been investigated to make the process more economical. Recently, PHA production cost was minimized by concomitant synthesis of other valuable bioproducts with PHA. Investigating these co-products and recovering them can also make the process circular bioeconomic. Therefore, the paper attempts to review the recent strategies for the simultaneous synthesis of value-added bioproducts with PHA together with the challenges and opportunities for their large-scale production and applications.

Valorization of Dairy Wastes: Integrative Approaches for Value Added Products

The era of rapid industrialization succeeded by a shift in organizational focus on research and technology development which has fueled many industries along with the dairy industry to grow at an exponential rate. The dairy industry has achieved remarkable growth in the last decade in India. Waste produced by dairy industry consists of a high organic load thus cannot be discharged untreated. Even though treatment and management of waste are well documented, but the main problem is concerned with sludge produced after treatment. There is a gap in the application of various methods for effective treatment of the waste, hence there is a need for technology-oriented research in this area because of a paradigm shift in perspectives towards sustainable management of waste to recover value added products including energy as energy demand is also rising. Sludge which is generally land spread can also be used for energy generation. This paper discusses the environmental effects of waste generated due to dairy industrial activities; various methods used for the advanced treatment of dairy waste. This review article aims to present and discuss the state-of-art information for recovery of value-added products (single cell protein, biofertilizers, biopolymers and biosurfactants) from dairy waste with emphasis on integration of technologies for environmental sustainability. This paper also includes challenges and future perspectives in this field.

Strategies for the valorisation of a protein-rich saline waste stream into polyhydroxyalkanoates (PHA)

Saline Mussels Cooking Wastewater was valorised to produce PHA with Mixed Microbial Cultures (MMC). Due to the high protein content (1.8-5.7 g COD_PROT/L), PHA accumulating capacity was below 10%, so several strategies were tested. In the acidification unit, Na(HCO₃) was added, increasing protein conversion into Volatile Fatty Acids (VFA) from 10.3% to 69.2% and subsequent PHA accumulation from 6.9 to 14.7%. In the enrichment unit, the incorporation of a settling stage after the feast phase provoked a shift in the proteins' oxidation from the feast to the famine phase, where the nitrogen released in the famine is used by the MMC for growth. This increased the biomass concentration and the tolerated COD (from 1.6 to 4.2 g VSS/L and from 2.2 to 4.38 g COD/L). Finally, varying the proteins/VFA ratio for MMC acclimation to proteins allowed increasing PHA accumulation from 8.8 to 41.5%.

Anthocyanin Hybrid Nanopigments from Pomegranate Waste: Colour, Thermomechanical Stability and Environmental Impact of Polyester-Based Bionanocomposites

In the present work, anthocyanin (ACN) hybrid nanopigments were synthetized by using a natural pomegranate dye (PD) and calcined hydrotalcite (HT) and montmorillonite (MMT) nanoclays. A wide colour gamut was obtained with MMT-based nanopigments ranging from reddish to bluish hues caused by structural transformations of ACNs at different pH values. However, a buffer effect was observed with HT obtaining samples a similar final colour regardless of the synthesis conditions. Nanopigments added with a biomordant extracted from pomegranate peels showed a different colour compared to the incorporation of a commercial mordant due to the intrinsic colouring properties of the pomegranate bioadditive. The developed nanopigments were incorporated at 7 wt% loading to produce novel polyester-based bionanocomposites which were characterized in terms of thermal, mechanical and colour properties. The encapsulation of PD into the nanoclays improved its thermal stability, in particular for MMT-based nanopigments. The pH changes observed during the nanofillers synthesis affected the final colour of the MMT-based nanocomposites, inducing a general increase in ∆E* and a decrease in gloss values. Slight improvements were obtained in terms of elastic modulus for MMT-based polymer samples confirming the applicability of the developed bionanocomposites as colouring and reinforcement materials. A very similar environmental profile was obtained for MMT and HT-based nanofillers showing MMT-based nanopigments a slightly better general behaviour. The results of the LCA study evidenced the suitability of the processes used in this work to the circular bioeconomy approach through sustainable food waste management and the production of bioplastics using waste substrates.

Scaling-up microbial community-based polyhydroxyalkanoate production: status and challenges

Conversion of organic waste and wastewater to polyhydroxyalkanoates (PHAs) offers a potential to recover valuable resources from organic waste. Microbial community-based PHA production systems have been successfully applied in the last decade at lab- and pilot-scales, with a total of 19 pilot installations reported in the scientific literature. In this review, research at pilot-scale on microbial community-based PHA production is categorized and subsequently analyzed with focus on feedstocks, enrichment strategies, yields of PHA on substrate, biomass PHA content and polymer characterization. From this assessment, the challenges for further scaling-up of microbial community-based PHA production are identified.

An environmental and economic assessment of bioplastic from urban biowaste. The example of polyhydroxyalkanoate

Bio-based and biodegradable plastics promise considerable reductions in our dependency on fossil fuels and in the environmental impacts of plastic waste. This study quantifies the environmental and economic consequences of diverting municipal food waste and wastewater sewage sludge from traditional management to the biorefinery-based production of polyhydroxyalkanoates (PHA) in five geographical regions. The results show that PHA can outperform fossil polyurethane and PHA from first-generation biomass (sugarcane and maize) with respect to both environmental impacts and societal costs (four times lower impacts and eight times lower costs than polyurethane). To outperform other fossil polymers like low-density polyethylene (LDPE), biorefinery performance should be improved further by more efficient utilization of sodium hypochlorite during PHA extraction, minimization of methane leakage in biogas facilities, upgrading of biogas to biomethane, and more effective handling of the liquid fraction from digestate dewatering.

Apply DEMATEL to Analyzing Key Barriers to Implementing the Circular Economy: An Application for the Textile Sector

Continuous improvement and innovation are solid foundations for the textile sector to maintain excellent growth and active sustainability. As the limited resources possessed by textile companies generally result in the incapability of implementing circular economy (CE) strategies simultaneously, recently, researchers advocate that organizations should analyze the influential inter-relationship between key barriers to explore the more dominant determinants for designing improved actions for implementing CE in the textile sector. CE implementation in the textile sector appears to be in its infancy. Although much attention has been paid to CE implementation barriers, the present study tries to fill this research gap by analyzing the causal relationships among the CE barriers in the textile sector. Therefore, the twelve barriers are identified by an extensive literature review, and the application of the Fuzzy Delphi Method (FDM) based on the expert options from the textile sector. Subsequently, the causal inter-relationship among the key CE barriers is based on expert opinions using the decision-making trial and evaluation laboratory (DEMATEL). The results of this study indicate that three key barriers require quick action: “consumers lack knowledge and awareness about reused/recycle (B1)”, “lack of successful business models and frameworks to implement CE (B3)”, and “lack of an information exchange system between different stakeholders (B8)”. In addition, the results provide significant managerial implications, including implementations of CE in the textile sector. Not only should the government build regulations and friendly laws and encourage environmentally-friendly materials but the textile companies should also focus or monitor the recycling methods and quality to overcome the CE implementation issues. In addition, this study contributes to the textile sector transition toward CE by using the novel methodology for determining and prioritizing the key barriers. Finally, this work would help top management and the practitioners to better design effective infrastructural strategies for the textile sector transition towards CE.

A novel strategy for triacylglycerides and polyhydroxyalkanoates production using waste lipids

Lipids are one of the main components of the organic matter present in the effluents of the food-processing industry. These waste streams can be biotransformed into valuable triacylglycerides (TAGs) and polyhydroxyalkanoates (PHAs), precursors of biofuels and biomaterials alternative to petroleum-based products. These compounds are yielded by mixed microbial cultures, and considering that both TAG and PHA accumulators may coexist within the community, it seems crucial to define those operational strategies that might control the selection of the dominant metabolic pathways (TAG or PHA accumulation). In this work, residual fish-canning oil was used as a carbon source in a two-stage process (culture selection and intracellular compounds accumulation) in which the substrate was simultaneously hydrolyzed in these two stages without the need for a previous fermentation unit. It was pretended to maximize preferential TAG or PHA storage in the accumulation reactor by the imposition of certain selective pressures in the enrichment one. Uncoupling C and N feedings and limiting nitrogen availability in the medium, allowed to maximize PHA production (82.3 wt% of PHAs, 0.80 Cmmol_PHA/Cmmol_S). Besides, when low pH in the famine phase was considered as additional selective pressure, it was possible to shift the ratio TAG:PHA from 4:96 obtaining 43.0 wt% of TAGs (0.67 Cmmol_TAG/Cmmol_S). Therefore, this novel and simplified process demonstrated versatility and efficiency in the storage of TAGs and PHAs from a unique residual feedstock and using an open culture proving that product selection can be harnessed if choosing the right operational conditions in the enrichment stage.

Food Plastic Packaging Transition towards Circular Bioeconomy: A Systematic Review of Literature

Advancement in packaging technology has played an essential role in reducing food waste and losses; however, most of this technology relies mostly on the use of plastics. Thus, there is an imminent need to think seriously about the transition towards a circular bioeconomy of innovative biobased materials with biodegradability potentials. This paper examines the driving forces behind the changes in food plastic packaging regimes and specifically seeks to understand how socio-technical configurations may influence niches to transition to a circular bioeconomy, particularly biobased biodegradable plastic materials. By employing a systematic review of the literature, we find that coordination with other back-end socio-technical systems that provide valorization of packaging waste is crucial to enable the transition. The literature indicates that one possible transition path is that the biobased biodegradable materials serve as “carriers of food waste”. The paper contributes to the discussion on the dynamics of food packaging in the transition to a bioeconomy viewed through the lenses of a socio-technical system (niche–regime–landscape), which continues to reinforce future actions, leading to better management of packaging end-of-life.

Isolation of poly(3-hydroxybutyrate) from bacterial biomass using soap made of waste cooking oil

The aim of this work was to develop a soap-based method for the isolation of poly(3-hydroxybutyrate) from bacterial biomass. The method consisted of adding soap derived from waste cooking oil to a concentrated (25%) biomass suspension, heating and centrifugal separation. Purity above 95% could be achieved with soap:cell dry mass ratios at least 0.125 g/g, making the method comparable to other surfactant-based protocols. Molecular weights M_w of products from all experiments were between 350 and 450 kDa, being high enough for future material applications. Addition of hydrochloric acid to the wastewater led to the precipitation of soap and part of non-P3HB cell mass. The resulting precipitate was utilized as a carbon source in biomass production and increased substrate-to-P3HB conversion.

Biowaste-to-bioplastic (polyhydroxyalkanoates): Conversion technologies, strategies, challenges, and perspective

Biowaste management is a challenging job as it is high in nutrient content and its disposal in open may cause a serious environmental and health risk. Traditional technologies such as landfill, bio-composting, and incineration are used for biowaste management. To gain revenue from biowaste researchers around the world focusing on the integration of biowaste management with other commercial products such as volatile fatty acids (VFA), biohydrogen, and bioplastic (polyhydroxyalkanoates (PHA)), etc. PHA production from various biowastes such as lignocellulosic biomass, municipal waste, waste cooking oils, biodiesel industry waste, and syngas has been reported successfully. Various nutrient factors i.e., carbon and nitrogen source concentration and availability of dissolved oxygen are crucial factors for PHA production. This review is an attempt to summarize the recent advancements in PHA production from various biowaste, its downstream processing, and other challenges that need to overcome making bioplastic an alternate for synthetic plastic.