Selection of Process Pathways for Biorefinery Design Using Optimization Tools: A Colombian Case for Conversion of Sugarcane Bagasse to Ethanol, Poly-3-hydroxybutyrate (PHB), and Energy

Opportunities in the microbial valorization of sugar industrial organic waste to biodegradable smart food packaging materials

Many petroleum-derived plastics, including food packaging materials are non-biodegradable and designed for single-use applications. Annually, around 175 Mt. of plastic enters the land and ocean ecosystems due to mismanagement and lack of techno economically feasible plastic waste recycling technologies. Renewable sourced, biodegradable polymer-based food packaging materials can reduce this environmental pollution. Sugar production from sugarcane or sugar beet generates organic waste streams that contain fermentable substrates, including sugars, acids, and aromatics. Microbial metabolism can be leveraged to funnel those molecules to platform chemicals or biopolymers to generate biodegradable food packaging materials that have active or sensing molecules embedded in biopolymer matrices. The smart package can real-time monitor food quality, assure health safety, and provide economic and environmental benefits. Active packaging materials display functional properties such as antimicrobial, antioxidant, and light or gas barrier. This article provides an overview of potential biodegradable smart/active polymer packages for food applications by valorizing sugar industry-generated organic waste. We highlight the potential microbial pathways and metabolic engineering strategies to biofunnel the waste carbon efficiently into the targeted platform chemicals such as lactic, succinate, muconate, and biopolymers, including polyhydroxyalkanoates, and bacterial cellulose. The obtained platform chemicals can be used to produce biodegradable polymers such as poly (butylene adipate-co-terephthalate) (PBAT) that could replace incumbent polyethylene and polypropylene food packaging materials. When nanomaterials are added, these polymers can be active/smart. The process can remarkably lower the greenhouse gas emission and energy used to produce food-packaging material via sugar industrial waste carbon relative to the petroleum-based production. The proposed green routes enable the valorization of sugar processing organic waste into biodegradable materials and enable the circular economy.

Sulfonated magnetic sugarcane bagasse as an efficient natural polymer-based catalyst for the synthesis of nitrogen-containing heterocyclic rings in water

A new species of catalysts that are prepared from biocompatible materials is demonstrated. Sulfonated magnetic sugarcane bagasse has been synthesized as a novel biodegradable and robust heterogeneous catalyst for organic transformations. The catalyst was characterized by different techniques. Next, the efficiency of this acid catalyst was examined with multi-component reactions for the synthesis of some biologically active scaffolds of heterocyclic organic compounds such 2,3-dihydroquinazolin-4(1H)-ones and pyrido[2,3-d]pyrimidin-4-one derivatives. A wide range of these heterocycles was synthesized with excellent yields in short reaction times under green conditions. In all cases, sulfonated magnetic sugarcane bagasse could be simply collected using an external magnet and reused for several runs without any significant loss of catalytic activity.

In vivo and Post-synthesis Strategies to Enhance the Properties of PHB-Based Materials: A Review

The transition toward "green" alternatives to petroleum-based plastics is driven by the need for "drop-in" replacement materials able to combine characteristics of existing plastics with biodegradability and renewability features. Promising alternatives are the polyhydroxyalkanoates (PHAs), microbial biodegradable polyesters produced by a wide range of microorganisms as carbon, energy, and redox storage material, displaying properties very close to fossil-fuel-derived polyolefins. Among PHAs, polyhydroxybutyrate (PHB) is by far the most well-studied polymer. PHB is a thermoplastic polyester, with very narrow processability window, due to very low resistance to thermal degradation. Since the melting temperature of PHB is around 170-180°C, the processing temperature should be at least 180-190°C. The thermal degradation of PHB at these temperatures proceeds very quickly, causing a rapid decrease in its molecular weight. Moreover, due to its high crystallinity, PHB is stiff and brittle resulting in very poor mechanical properties with low extension at break, which limits its range of application. A further limit to the effective exploitation of these polymers is related to their production costs, which is mostly affected by the costs of the starting feedstocks. Since the first identification of PHB, researchers have faced these issues, and several strategies to improve the processability and reduce brittleness of this polymer have been developed. These approaches range from the in vivo synthesis of PHA copolymers, to the enhancement of post-synthesis PHB-based material performances, thus the addition of additives and plasticizers, acting on the crystallization process as well as on polymer glass transition temperature. In addition, reactive polymer blending with other bio-based polymers represents a versatile approach to modulate polymer properties while preserving its biodegradability. This review examines the state of the art of PHA processing, shedding light on the green and cost-effective tailored strategies aimed at modulating and optimizing polymer performances. Pioneering examples in this field will be examined, and prospects and challenges for their exploitation will be presented. Furthermore, since the establishment of a PHA-based industry passes through the designing of cost-competitive production processes, this review will inspect reported examples assessing this economic aspect, examining the most recent progresses toward process sustainability.

Developing Process Designs for Biorefineries—Definitions, Categories, and Unit Operations

In this review, we focus on the literature that described the various unit operations in a process design flowsheet of biorefineries. We begin by establishing the accepted definitions of a biorefinery, go on to describe how to categorize biorefineries, and finally review the literature on biorefinery process designs by listing the unit operation in each process design. Distinguishing biorefineries based on feedstock, the types of processing units, and the products emanating from the biorefinery are discussed.

Recycling strategies for polyhydroxyalkanoate-based waste materials: An overview

The plastics market is dominated by fossil-based polymers, but their gradual replacement by bioplastics (e.g., polyhydroxyalkanoates) is occurring. However, recycling strategies need to be developed to truly unveil the impact of bioplastics on waste accumulation. This review provides a state of the art of recycling strategies investigated for polyhydroxyalkanoate-based polymers and proposes future research avenues. Research on mechanical and chemical recycling is dominated by the use of extrusion and pyrolysis, respectively, while that on biodegradation of polyhydroxyalkanoates is related to soil and aquatic samples, and to anaerobic digestion towards biogas production. Research gaps exist in the relationships between polymer composition and ease of use of all recycling strategies investigated. This is of utmost importance since it will influence the need for separation at the source. Therefore, research emphasis needs to be given to the area to follow the continuous improvement of the process economics towards widespread commercial production of polyhydroxyalkanoates.

Production of bioplastic through food waste valorization

The tremendous amount of food waste from diverse sources is an environmental burden if disposed of inappropriately. Thus, implementation of a biorefinery platform for food waste is an ideal option to pursue (e.g., production of value-added products while reducing the volume of waste). The adoption of such a process is expected to reduce the production cost of biodegradable plastics (e.g., compared to conventional routes of production using overpriced pure substrates (e.g., glucose)). This review focuses on current technologies for the production of polyhydroxyalkanoates (PHA) from food waste. Technical details were also described to offer clear insights into diverse pretreatments for preparation of raw materials for the actual production of bioplastic (from food wastes). In this respect, particular attention was paid to fermentation technologies based on pure and mixed cultures. A clear description on the chemical modification of starch, cellulose, chitin, and caprolactone is also provided with a number of case studies (covering PHA-based products) along with a discussion on the prospects of food waste valorization approaches and their economic/technical viability.

Energy Efficiency of Biorefinery Schemes Using Sugarcane Bagasse as Raw Material

The use of biomass to obtain value-added products has been a good alternative for reducing their environmental impacts. For this purpose, different studies have been carried out focused on the use of agro-industrial waste. One of the most commonly used raw materials has been bagasse obtained from the processing of sugarcane in high quantities in countries like Brazil, India, China, Thailand, Pakistan, Mexico, Colombia, Indonesia, Philippines, and the United States. From 1 ton of sugarcane, 280 kg of bagasse can be obtained. Sugarcane bagasse (SCB) is a waste that is rich in polysaccharides, which makes it a promising raw material for obtaining products under biorefinery concept. The objective of this work was to analyze from the energetic point of view, different biorefinery schemes in which SCB is employed as a raw material. The design and simulation of the different biorefinery schemes is performed in Aspen Plus software. From this software, it was possible to obtain the different mass and energy balances, which are used in the technical and energetic analysis. Exergy is used as a comparison tool for the energy analysis. These analyses allowed for the selection of the best biorefinery configuration from SCB.

Techno-economic and environmental assessment of biogas production from banana peel (Musa paradisiaca) in a biorefinery concept

Two scenarios for the biogas production using Banana Peel as raw material were evaluated. The first scenario involves the stand-alone production of biogas and the second scenario includes the biogas production together with other products under biorefinery concept. In both scenarios, the influence of the production scale on the process economy was assessed and feasibility limits were defined. For this purpose, the mass and energy balances were established using the software Aspen Plus along with kinetic models reported in the literature. The economic and environmental analysis of the process was performed considering Colombian economic conditions. As a result, it was found that different process scales showed great potential for biogas production. Thus, plants with greater capacity have a greater economic benefit than those with lower capacity. However, this benefit leads to high-energy consumption and greater environmental impact.

Stand-alone and biorefinery pathways to produce hydrogen through gasification and dark fermentation using Pinus Patula

New efforts in the search of alternative clean and renewable energy to replace the current energy precursors have been assessed in order to reduce emissions to the environment. Lignocellulosic Biomass (LB) can be used to produce bioenergy due to its high energy potential and availability. Different ways are proposed for the transformation of these residues into high added-value products. Thermochemical and biochemical technologies are the most interest concepts focusing on the use of biomass as source for energy production at positive net balances. This study presents the techno-economic, energy and environmental assessment of five scenarios for the hydrogen production through gasification and dark fermentation based on the biorefinery and stand-alone concepts. The results demonstrated that the production of hydrogen based on the concept of a biorefinery can improve the profitability, energy efficiency and reduce the emissions of the processes compared to that based on the stand-alone way. The selection of ethanol and electricity as valuable co-products of the biorefinery in the hydrogen production process confirmed that the process scale and products diversity makes possible a flexible and suitable process to produce hydrogen and other energy carriers from Pinus Patula.

Microbial production of poly(lactate-co-3-hydroxybutyrate) from hybrid Miscanthus-derived sugars

P[(R)-lactate-co-(R)-3-hydroxybutyrate] [P(LA-co-3HB)] was produced in engineered Escherichia coli using lignocellulose-derived hydrolysates from Miscanthus × giganteus (hybrid Miscanthus) and rice straw. Hybrid Miscanthus-derived hydrolysate exhibited no negative effect on polymer production, LA fraction, and molecular weight of the polymer, whereas rice straw-derived hydrolysate reduced LA fraction. These results revealed that P(LA-co-3HB) was successfully produced from hybrid Miscanthus-derived sugars.

Techno-economic analysis for brewer's spent grains use on a biorefinery concept: the Brazilian case

A techno-economic analysis for use of brewer's spent grains (BSG) on a biorefinery concept for the Brazilian case is presented. Four scenarios based on different levels of heat and mass integration for the production of xylitol, lactic acid, activated carbon and phenolic acids are shown. A simulation procedure using the software Aspen Plus and experimental yields was used. Such procedure served as basis for the techno-economic and environmental assessment according to the Brazilian conditions. Full mass integration on water and full energy integration was the configuration with the best economic and environmental performance. For this case, the obtained economic margin was 62.25%, the potential environmental impact was 0.012 PEI/kg products, and the carbon footprint of the processing stage represented 0.96 kg CO2-e/kg of BSG. This result served as basis to draw recommendations on the technological, economic and environmental feasibility for implementation of such type of biorefinery in Brazil.

Techno-economic analysis of bioethanol production from lignocellulosic residues in Colombia: a process simulation approach

In this study a techno-economic analysis of the production of bioethanol from four lignocellusic (Sugarcane bagasse, Coffee cut-stems, Rice Husk, and Empty Fruit Bunches) residues is presented for the Colombian case. The ethanol production was evaluated using Aspen Plus and Aspen Process Economic Analyzer carrying out the simulation and the economic evaluation, respectively. Simulations included the composition of lignocellulosic residues, which was determined experimentally. It was found that empty fruit bunches presents the highest ethanol yield from a dry basis point of view (313.83 L/t), while rice husk produced less ethanol (250.56 L/t). The ethanol production cost was assessed for the standalone ethanol plant and the ethanol plant coupled with a cogeneration system. Moreover, ethanol production cost using EFB was the lowest with (0.49 US$/L) and without (0.58 US$/L) cogeneration scheme.