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Industrial-scale upcycling of waste polyethylene terephthalate (PET) plastic into porous carbon globally for CO2 capture was verified as a multifunctional alternative to conventional CO2 absorption and plastic waste management technologies.

Microalgae-based antibiotic removal treatment has attracted attention because of its low carbon and sustainable advantages. The microalgal co-metabolism system with a suitable carbon source leads to enhanced performance of pollutant removal. However, currently, limited knowledge is available for the removal of fluoroquinolone using a microalgae-mediated co-metabolism system. In this study, we first investigated that the biotic processes by alga Haematococcus lacustris in the co-metabolism system by adding glycerol would be the main contributors responsible for the removal of 10 mg/L ofloxacin (OFL) with the efficiency of 79.73% and the removal of 10 mg/ L enrofloxacin (ENR) with the efficiency of 54.10%, respectively. Furthermore, we found that pyruvate from glycerol was converted into substrates and precursors, thereby resulting in the significant accumulations of microalgal astaxanthin and lipid. The astaxanthin content of H. lacustris was achieved at 4.81% and 4.69% treated with OFL and ENR in the presence of glycerol, with 16.04% and 14.55% of lipid content, respectively. The proposed metabolites and pathways were identified to plausibly explain the biodegradation of fluoroquinolone by H. lacustris. The molecular analyses demonstrated that cytochrome P450 (CYP450) enzymes are responsible for the biodegradation of fluoroquinolone, and it was further verified that fluoroquinolones might insert into CYP450 to finally form an efficient and tight binding conformation by molecular dynamic simulation. These findings provide a microalgae-based route for feasible and sustainable biodegradation of antibiotics using a co-metabolism strategy comprising glycerol as a carbon source, with the synergistic accumulation of valuable products., peer-reviewed

According to the US Department of Energy, succinic acid (SA) is a top platform chemical that can be produced from biomass. Bread waste, which has high starch content, is the second most wasted food in the UK and can serve as a potential low cost feedstock for the production of SA. This work evaluates the environmental performance of a proposed biorefinery concept for SA production by fermentation of waste bread using a cradle-to-factory gate life cycle assessment approach. The performance was assessed in terms of greenhouse gas (GHG) emissions and non-renewable energy use (NREU). Waste bread fermentation demonstrated a better environmental profile compared to the fossil-based system, however, GHG emissions were about 50% higher as compared to processes using other biomass feedstocks such as corn wet mill or sorghum grains. NREU for fermentative SA production using waste bread was significantly lower (~ 46%) than fossil-based system and about the same as that of established biomass-based processes, thus proving the great potential of waste bread as a valuable feedstock for bioproduction of useful chemicals. The results show that steam and heating oil used in the process were the biggest contributors to the NREU and GHG emissions. Sensitivity analyses highlighted the importance of the solid biomass waste generated in the process which can potentially be used as fish feed. The LCA analysis can be used for targeted optimization of SA production from bread waste, thereby enabling the utilization of an otherwise waste stream and leading to the establishment of a circular economy.

The current perspective presents an outlook on developing gut-like bioreactors with immobilized probiotic bacteria using cellulose hydrogels. The innovative concept of using hydrogels to simulate the human gut environment by generating and maintaining pH and oxygen gradients in the gut-like bioreactors is discussed. Fundamentally, this approach presents novel methods of production as well as delivery of multiple strains of probiotics using bioreactors. The relevant existing synthesis methods of cellulose hydrogels are discussed for producing porous hydrogels. Harvesting methods of multiple strains are discussed in the context of encapsulation of probiotic bacteria immobilized on cellulose hydrogels. Furthermore, we also discuss recent advances in using cellulose hydrogels for encapsulation of probiotic bacteria. This perspective also highlights the mechanism of probiotic protection by cellulose hydrogels. Such novel gut-like hydrogel bioreactors will have the potential to simulate the human gut ecosystem in the laboratory and stimulate new research on gut microbiota.

Bread is Europe's most wasted food, and the second most wasted food after potatoes in UK. Bread waste (BW) is a clean source of high-quality fermentable sugars. In this study, the potential of Enterobacter ludwigii to accumulate 2,3-butanediol (BDO) from BW was evaluated. Initially, the optimal inoculum size and yeast extract concentration were determined, followed by extraction of sugars from BW using acid and enzymatic hydrolysis. A glucose yield of 330-530 g/kg BW was obtained, and the sugars released were utilised for BDO production by E. ludwigii. The fed-batch cultivation using pure glucose and glucose rich hydrolysates from acid and enzymatic hydrolysis resulted in BDO titres of 144.5, 135.4, and 138.8 g/L, after 96 h, with yield of 0.47, 0.42 and 0.48 g/g yield, respectively. The innovation of the work is valorisation of BW to BDO with a circular biorefining approach and thus, reducing BW disposal and associated environmental burden.

Background Despite the great potential of marine diatoms in biofuel sector, commercially viable biofuel production from native diatom strain is impractical. Targeted engineering of TAG pathway represents a promising approach; however, recruitment of potential candidate has been regarded as critical. Here, we identified a glycerol-3-phosphate acyltransferase 2 (GPAT2) isoform and overexpressed in Phaeodactylum tricornutum. Results GPAT2 overexpression did not impair growth and photosynthesis. GPAT2 overexpression reduced carbohydrates and protein content, however, lipid content were significantly increased. Specifically, TAG content was notably increased by 2.9-fold than phospho- and glyco-lipids. GPAT2 overexpression elicited the push-and-pull strategy by increasing the abundance of substrates for the subsequent metabolic enzymes, thereby increased the expression of LPAAT and DGAT. Besides, GPAT2-mediated lipid overproduction coordinated the expression of NADPH biosynthetic genes. GPAT2 altered the fatty acid profile in TAGs with C16:0 as the predominant fatty acid moieties. We further investigated the impact of GPAT2 on conferring abiotic stress, which exhibited enhanced tolerance to hyposaline (70%) and chilling (10 ºC) conditions via altered fatty acid saturation level. Conclusions Collectively, our results exemplified the critical role of GPAT2 in hyperaccumulating TAGs with altered fatty acid profile, which in turn uphold resistance to abiotic stress conditions.

Secondary/waste streams have previously been used as feedstocks to produce sophorolipids (SLs), a biosurfactant with low eco-toxicity and high biodegradability, in order to reduce production costs and protect the environment. However, limited productivities and titres from these feedstocks remain as important challenges. Thus, the optimisation of fermentation medium using bakery waste oil (BWO) as a hydrophobic carbon source by Starmerella bombicola was investigated. The optimal conditions were determined by multiple linear regression. Inoculum concentration of 2% v v-1 and BWO and glucose concentrations of 60 g L-1 and 100 g L-1, respectively, resulted in an increase of 19.6% in the lactonic SL (67.8 +/- 11.5 g L-1). Further optimisation revealed the profound influence of KOH in pH regulation, i.e., compared with NaOH, KOH led to higher concentrations of biomass (p < 0.05), more BWO consumption, and thus, an increase of 42.2% in SL titre (96.4 +/- 9.1 g L-1) and corresponding volumetric and specific productivities of 0.446 g L- 1h- 1 and 0.027 g g CDW- 1h- 1, respectively. Multiple regression analysis demonstrated that pH and the concentration of BWO as the feeding medium were the most influential parameters in fermentative SL production. This study demonstrated that KOH offered additional benefit to improve SLs titre by maintaining high biomass during the bioprocess, displayed the importance of intracellular potassium in cell viability and improved the valorisation of BWO process.

Soil acidification is the main cause for aggravation of soil cadmium (Cd) pollution. Biochar treatment can increase the soil pH and decrease the Cd availability in soils. However, there is limited information in literature on the comprehensive assessment of the response of Cd fractions to biochar. Therefore, in the present meta-analysis study, we evaluate the response of Cd fractions to biochar application in soils with different pH and to further examine the effect of physicochemical properties of biochar on Cd. Results from the overall analysis indicated that biochar treatment increased the soil pH by 7.0%, thereby decreasing the amount of available Cd (37.3%). In acidic soil, biochar significantly reduced the acid-soluble fraction (Acid-Cd) of Cd by 36.8%, while Oxidizable fraction of Cd (Oxid-Cd, 20.9%) and Residual fraction of Cd (Resid-Cd, 22.2%) were significantly increased. In neutral soils, only Acid-Cd was significantly reduced (33.0%) in the presence of biochar. In alkaline soils, biochar caused significant reduction in Acid-Cd of 12.4% and an increase in Oxid-Cd and Resid-Cd of 26.6% and 47.8%, respectively. Further, our findings showed that biochar with cation exchange capacity100 cmol

Dependency on plastic commodities has led to a recurrent increase in their global production every year. Conventionally, plastic products are derived from fossil fuels, leading to severe environmental concerns. The recent coronavirus disease 2019 pandemic has triggered an increase in medical waste. Conversely, it has disrupted the supply chain of personal protective equipment (PPE). Valorisation of food waste was performed to cultivate C. necator for fermentative production of biopolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). The increase in biomass, PHBV yield and molar 3-hydroxy valerate (3HV) content was estimated after feeding volatile fatty acids. The fed-batch fermentation strategy reported in this study produced 15.65 ± 0.14 g/L of biomass with 5.32 g/L of PHBV with 50% molar 3HV content. This is a crucial finding, as molar concentration of 3HV can be modulated to suit the specification of biopolymer (film or fabric). The strategy applied in this study addresses the issue of global food waste burden and subsequently generates biopolymer PHBV, turning waste to wealth.

The replacement of fossil fuels with clean and renewable biofuels is of both research and market interest for realising a circular economy. However, microalgae-based biofuels have shown promise as alternative low-carbon biofuels to other crop-based biofuels, some key obstacles in their production remain to be addressed, such as high costs and low lipid productivity. In this study, a Chlorella sp. CSH4 was cultivated using a combined light regime and carbon supply regulation strategy to enhance sugar industrial wastewater bioremediation, biomass accumulation and lipid production. Blue light irradiance of 200 μmol photons m -2 s-1 together with 10 g/L glucose and 9.2 g/L glycerol supply was found to effectively enhance the biomass accumulation and pollutant-removal capacity of Chlorella sp. during the growth phase and its lipid production during the stationary phase. Furthermore, the biodiesel properties of the lipid retrieved from Chlorella sp., as demonstrated by its fatty acid profile, were found to be suitable for commercial application. Possible mechanisms were explored to explain how this combined strategy caused this microalga to exhibit highly efficient biomass and lipid production together with efficient pollutant removal. Moreover, upscaled semi-continuous treatment using both sugar industry wastewater and negligible carbon sources (e.g., food waste hydrolysate and crude glycerol) with a mass balance analysis was conducted to initially validate the feasibility of applying our combined strategy for microalgae based wastewater treatment. In sum, this study demonstrated the feasibility of cultivating a microalga using a combined strategy comprising a light regime and carbon supply regulation to achieve both wastewater treatment and low-carbon biofuel production., peer-reviewed

In their Editorial to the Special Issue on The Chemistry of Waste Plastics Upcycling, the Guest Editors Adam Guss, George Huber, Carol Lin, Xianzhi Meng, Hugh O'Neill, Arthur Ragauskas, Jia Wang, Yanqin Wang, and Frederik Wurm highlight some of the increasingly urgent efforts being made by chemists to address challenges related to the fate of plastics at the end of, their useful lives and the valorization of plastic waste.

International audience; Yarrowia lipolytica strains PGC01003 and PGC202 engineered for succinic acid production were studied and compared to the wild type strain W29. For the first time, these two strains were characterized in a chemically defined medium. Strain growth and organic acid production were investigated in fed-batch mode with glycerol as carbon and energy source. This study evaluated the impact of nitrogen deficiency strategy to redirect carbon flux toward succinic acid synthesis. Strain PGC01003 produced 19 g L−1 succinic acid with an overall yield of 0.23 g g−1 and an overall productivity of 0.23 g L−1 h−1, while strain PGC202 produced 33 g L−1 succinic acid with an overall yield of 0.12 g g−1 and a productivity of 0.57 g L−1 h−1. Nitrogen limitation effectively stopped biomass growth and increased succinic acid yield of PGC01003 and PGC202 by 18 % and 62 %, respectively. However, the specific succinic acid production rate was reduced by 77 % and 66 %, respectively.

Recent sustainable development goals of food security, environmental protection, material and energy efficiency are the key drivers of the valorization of food waste. In the present work, the production of biosurfactant sophorolipids from several (food) waste streams was investigated, using the non-pathogenic yeast Starmerella bombicola. From a preliminary screening, restaurant food waste emerged as the most suitable feedstock compared to bakery waste, textile waste, used corn oil, animal fat and lipid fraction of hydrolyzed food waste. Restaurant food waste was subsequently used for sophorolipids production in a laboratory-scale bioreactor. Food waste obtained from a local restaurant was subjected to enzymatic hydrolysis for 16 h, yielding a hydrolysate containing about 100 g/L glucose and 2.4 g/L free amino nitrogen. High SL process efficiency was achieved by fed-batch fermentation using the restaurant food waste hydrolysate as the complete batch medium, i.e. without any supplementation of additional medium components such as vitamins, salts, nitrogen or phosphate. Controlled feeding of glucose and oleic acid to the culture was performed after the batch phase. A sophorolipids titer of 115.2 g/L was obtained in a fermentation time of 92 h resulting in an overall volumetric productivity of 1.25 g/L.h. These results achieved for sophorolipids productivity using hydrolyzed food waste are in the same order of magnitude as the reported values using traditional (complex) fermentation media. This indicates the suitability of the developed process using food waste for the advancement of waste-based bio-processes for the production of sophorolipids.

This paper presents an efficient, green and sustainable approach for succinic acid (SA) fermentation, in which glucose-rich hydrolysates from various waste streams were used as the substrate for SA production by Yarrowia lipolytica without pH control for the first time. First, Y. lipolytica PGC202 was found to be able to consume glucose-rich mixed food waste (MFW) hydrolysate for SA production with high efficiency. After medium optimization, a SA titer at 31.7 g/L with a yield of 0.52 g/g and productivity of 0.60 g/L/h was obtained from isFBB fermentation when using 60 g/L glucose-containing MFW hydrolysate as the carbon source supplemented with 3% tryptone. When glucose-rich hydrolysate from other waste streams was used, the highest SA yield of 0.61 g/g via yeast fermentation at low pH was achieved, which demonstrated the extensive substrate adaptability and great potential of Y. lipolytica. By feeding concentrated MFW hydrolysate, SA titer up to 71.6 g/L was achieved from fed-batch fermentation with pH decreased naturally to 2.8. Finally, with the revised recovery method, 68.3% of the total SA with purity between 89.5% and 91.0% was recovered from the acidic fermentation broth with only low input of acid for acidification, which demonstrated the great advantages of SA production at low pH over that under neutral conditions in terms of economic improvement and environmental sustainability. In general, this study overcomes one of the major economic drawbacks for future feasible large-scale fermentative SA production, and it also illustrates a promising prospective for bio-SA production.

Biorefinery is an emerging strategy to progressively replace the conventional refinery. This technique aims to produce biofuels and value-added products from lignocellulosic biomass. With intensive research efforts, a number of innovative technologies have been developed to utilize the building block chemicals from biomass. However, application of the new technique needs to consider the three pillars of sustainable development, i.e., economic, social and environmental development. The concerns could be feedstock- or region-specific, resulting in completely different requirement of desired process under different circumstances. This study reviews the key design concepts and the strengths of the most promising techniques for biomass conversion. Particular attentions are paid to complete utilize all the building block components in the feedstock. Operational parameters such as energy, water, and chemicals are investigated to select desired processes for bioenergy production. The review aims to present the past, current and future research and process development for high efficiency biofuel production.

Carbamazepine (CBM), a widely occurring pharmaceutical, has been removed from water by upgrading a waste biomass char from a 300 MW biomass gasification power station plant operating in Indonesia. The fuel source is the waste residue palm kernel shell (PKS) after the palm oil extraction process constituting over one million tonnes per year. The resulting waste power station biomass char (CPKS) from the power station gasification process has been converted into high quality activated carbon by carbon dioxide activation as a sequestration opportunity, at different temperatures ranging from 700 to 900°C for 1 or 1.5 hours. The highest BET surface area was 711.5 m2/g and this activated carbon was able to adsorb 1.14 mmol/g or 268.7 mg CBM/g. Equilibrium and kinetic studies have been undertaken.

Although fossil-based plastic products have many attractive characteristics, their production has led to severe environmental burdens that require immediate solutions. Despite these plastics being non-natural chemical compounds, they can be degraded and metabolized by some microorganisms, which suggests the potential application of biotechnologies based on the mechanism of plastic biodegradation. In this context, microbe-based strategies for the degradation, recycling, and valorization of plastic waste offer a feasible approach for alleviating environmental challenges created by the accumulation of plastic waste. This Minireview highlights recent advances in the biotechnology-based biodegradation of both traditional polymers and bio-based plastics, focusing on the mechanisms of biodegradation. From an application perspective, this Minireview also summarizes recent progress in the recycling and valorization of plastic waste, which are feasible solutions for tackling the plastic waste dilemma.

Fast-changing fashion trends have resulted in increases in textile production and waste generation. The environmental impacts of the production, consumption and end-of-life of textiles are amply documented. Therefore, the industry has started to shift from the linear economy principle of ‘take-make-waste’ to the circular economy concept, where textiles can reenter the life cycle rather than being wasted and thus form a closed loop, resulting in resource savings and reduced environmental impacts. To this end, valorization of solid waste streams from the textile industry to recover fibers and marketable value-added products has gained increasing attention in recent years. Textile waste valorization involves three main steps: pretreatment, enzymatic hydrolysis and fiber regeneration. This review presents the main methodologies and the most recent technical developments in these valorization strategies, the value-added products obtained and their applications. Furthermore, the review describes fermentative products synthesized using cellulosic glucose from the cotton fraction of waste streams. Gaps and challenges in existing strategies are identified for potential future research. This review will help to apprize researchers and practitioners of important recent developments in effective textile valorization via upcycling and guide them in the design of efficient strategies for sustainable management of textile waste streams.

The recovery of waste cooking oil has long been known for second life uses without chemical modification. However, the concepts of bioeconomy and circular economy are much more recent and include a ranges of tasks such as recovery, storage, use, chemical modification. International research into the use of modified and unmodified waste cooking oil and their potential uses has been the subject of incessant research in both academia and industry. The main purpose of this review is to present the recent breakthroughs obtained in the field of recovery of used cooking oils for the last decade. The review discusses advances obtained in major production pathways recently explored splitting in the following categories: (i) transesterification of waste cooking oil including biodiesel production with heterogeneous/homogeneous base and acid catalysis, magnetic heterogeneous catalysis, biocatalysis and alternative technologies such as electrolysis, continuous flow, microwave irradiation, ultrasound irradiation; (ii) transesterification of waste cooking oil including catalytic biolubricant production; (iii) interesterification; (iv) hydrolysis and (v) hydrodeoxygenation, hydrocracking and hydrogenation. This review also briefly overviews current understanding of waste cooking oil valorization and the underpinning mechanism.