Biorefinery System Research Articles

Review of recent advances in utilising aquaculture wastewater for algae cultivation and microalgae-based bioproduct recovery.

Aquaculture operations produce large amounts of wastewater contaminated with organic matter, nitrogenous compounds, and other emerging contaminants; when discharged into natural water bodies, it could result in ecological problems and severely threaten aquatic habitats and human health. However, using aquaculture wastewater in biorefinery systems is becoming increasingly crucial as advancements in valuable bioproduct production continue to improve economic feasibility. Research on utilisingmicroalgaeas an alternative to producing biomass and removing nutrients from aquaculture wastewater has been extensively studied over the past decades. Microalgae have the potential to use carbon dioxide (CO2) effectively and significantly reduce carbon footprint, and the harvested biomass can also be used as aquafeed. Furthermore, aquaculture wastewater enriched with phosphorus (P) is a potential resource for P recovery for the production of biofertiliser. This will reduce the P supply shortage and eliminate the environmental consequences of eutrophication. In this context, the present review aims to provide a comprehensive overview of the current state of the art in a generation, as well as the characteristics and environmental impact of aquaculture wastewater reported by the most recent research. Furthermore, the review synthesized recent developments in algal biomass cultivation using aquaculture wastewater and its utilisation as biorefinery feedstocks for producing value-added products, such as aquafeeds, bioethanol, biodiesel, biomethane, and bioenergy. This integrated process provides a sustainable method for recovering biomass and water, fully supporting the framework of a circular economy in aquaculture wastewater treatment via resource recovery.

Valorization of Residual Fractions from Defatted Rice Bran Protein Extraction: A Carbohydrate-Rich Source for Bioprocess Applications

Defatted rice bran (DRB) is the by-product of rice bran oil extraction and presents approximately 66% carbohydrates and 15% proteins, a composition with the potential to integrate biorefinery systems. This study aimed to investigate the feasibility of residual fractions from ultrasound-assisted protein extraction from DRB as sources of carbohydrates in bioprocesses. First, DRB was exposed to protein extraction in an alkaline medium assisted by ultrasound. The residual fractions, including the precipitate from the extraction process (P1) and the supernatant from protein precipitation (S2), were combined and autoclaved to gelatinize the starch. Enzyme activity tests showed that a temperature of 70 °C was optimal for the simultaneous application of α-amylase and amyloglucosidase (AMG). To study enzymatic hydrolysis, a Full Factorial Design (FFD) 22 was employed, with α-amylase and AMG concentrations ranging from 0.12 to 0.18 mL∙L−1 and a substrate concentration (P1/S2 ratio) between 30 and 70 g∙L−1, resulting in a maximum of 18 g∙L−1 of reducing sugars (RS). Fermentation assays with Saccharomyces cerevisiae demonstrated that the hydrolysate of the residual fractions was effective for ethanol production (8.84 g∙L−1 of ethanol; YP/S: 0.614 gethanol∙gRS−1; η: 120.24%), achieving results comparable to control media (with sucrose as the substrate), indicating its potential for application in bioprocesses. These outcomes highlight a promising technological approach for utilizing DRB in integrated biorefineries.

Integrating heterogenous robustness levels to the multi-objective target-oriented robust optimization of a microalgal biorefinery

Integrated biorefineries offer an efficient way to produce biofuels by enhancing profit through the generation of marketable by-products and by reducing environmental impact by reutilizing waste streams originating from different processes within the system. Employing a variety of conversion technologies, integrated biorefineries yield a wide range of products and byproducts, encompassing biofuels, biochemicals, and bioenergy, all derived from biomass feedstocks. Several mathematical methods have been developed in order to optimize the design of biorefineries with consideration for uncertainty, including the multi-objective target-oriented robust optimization (MOTORO) approach that enables target-seeking behavior while maximizing the tolerable deviation of parameters in the system. However, the phenomenon of heterogenous robustness levels that tradeoff risks with each other has not been investigated in both MOTORO and in wider robust optimization literature. The present study addresses this gap by applying multiple, potentially non-equal degrees of robustness to each customer's demand, allowing stakeholders to place unequal risks on each customer. As a result, limited resources may be more efficiently utilized in line with existing knowledge or preference regarding uncertainties. The proposed improvement was applied to an algal biorefinery system with two customers, where robustness successfully exhibited tradeoffs with each other while retaining inverse relationships with system underperformance and variation as evaluated from a Monte Carlo simulation.

Third-Generation L-Lactic Acid Biorefinery Approaches: Exploring the Viability of Macroalgae Detritus

AbstractRising concerns over fossil fuel depletion and plastic pollution have driven research into biodegradable alternatives, such as polylactic acid (PLA). Microbial fermentation is preferred for lactic acid production due to its ability to yield enantiomerically pure lactic acid, which is essential for PLA synthesis, unlike the racemic mixture from chemical synthesis. However, commercial lactic acid production using first-generation feedstocks faces challenges related to cost and sustainability. Macroalgae offer a promising alternative with their rapid growth rates and carbon capture capabilities. This review explores recent technological advancements in macroalgae physicochemical characterization, optimization of fermentation conditions, and innovative pretreatment methods to enhance sugar conversion rates for L-LA production. It also covers downstream processes for L-LA recovery, presenting a complete macroalgal biorefinery system. Environmental impacts and economic prospects are assessed through exergy and techno-economic analyses. By valorizing macroalgae detritus, this study underscores its potential to support a sustainable biorefinery industry, addressing economic feasibility and environmental impact.

Exploring Marine-Based Food Production: The Challenges for a Sustainable and Fast Biotechnology-Based Development

Marine-derived nutrients and bioactive compounds may offer a myriad of biological benefits, such as anticancer and anti-inflammatory properties, and technological potential, enhancing food quality as additives. Their role in the sustainable development of food technology is fundamental, especially in advancing the knowledge of functional foods and related technologies. Algae are considered one of the major sources of marine-derived ingredients and the subject of several recent studies. Despite their potential, the translation of marine ingredients’ potential into a marine-based competitiveness of the food industry faces hurdles in the extraction process and operational systems scale-up that the industry needs to tackle. The complexity of marine matrices with diverse compounds and solubilities adds complexity to extraction processes and may lead to low yields or bioactivity loss. Contaminants, like heavy metals and pesticide residues in marine organisms, require rigorous purification processes for product safety. The use of biorefinery systems in marine-based ingredients’ production, particularly cascade processes, offers zero-waste solutions, contributing to the blue economy and aligning with UN sustainability goals. Sustainability assessment tools are critical for evaluating marine-based food production’s environmental, social, and economic impacts. A continued exploration and collaboration are essential for the future, fostering innovation and sustainability to create a resilient, equitable, and eco-friendly food system.

Advancements in biomass valorization in integrated biorefinery systems

AbstractThe utilization of lignocellulosic biomass for the generation of diverse value‐added biochemicals and biofuels is crucial in modern biorefineries and bioenergy initiatives, contributing significantly to the pursuit of a climate‐neutral future. Agricultural, forest and industrial sources of lignocellulosic biomass serve as exceptionally renewable precursors in biorefinery processes. In spite of its abundance, the effective breakdown of biomass poses a significant challenge. Thus, it is essential to integrate various unit processes, including biochemical, thermochemical, physical, enzymatic and catalytic conversion, to generate a wide array of bio‐based products. Intensive integration of these processes not only enhances yield and reduces reaction time but also proves to be economically efficient. Furthermore, these process integration approaches may contribute to the establishment of a circular bioeconomy through biorefineries, effectively reducing both bioresource waste and greenhouse gas emissions. This review offers fundamental insights into biomass and its chemistry, with a detailed discussion on lignocellulosic conversion systems. It explores how integrating conversion processes can facilitate the transition toward a circular economy. Additionally, it summarizes the challenges and prospects associated with advancing integrated biorefineries and circular economy principles to achieve complete biomass valorization.

Advancing biorefinery technologies through transesterification and hydrothermal liquefaction for biodiesel and bioproducts production

BackgroundThe multicriteria assessment of advancing biorefinery to produce biodiesel (fatty acid methyl ester), glycerol, and torrefied pellets is a strategic approach towards sustainable development. MethodsA successive transesterification process was applied to separate lipids with alcohol, with a 1:7 mass-to-mass ratio in the presence of a heterogeneous catalyst of chitosan/polyvinyl alcohol-sodium hydroxide (CS/PVA-NaOH), to produce biodiesel and glycerol. Moreover, the remaining biomass is extracted to produce torrefied pellets by applying torrefaction through hydrothermal liquefication at 200–300 ℃ temperature. The biorefinery system using 613 kg organic fraction of municipal solid waste (OFMSW) produced 127.3 L of biodiesel, 14.5 kg of glycerol, and 387.5 kg of torrefied pellets. The whole systematic approach revealed two distinct areas with required characterized equipment such as dryer (A = 721.28m2), suspended in tank (V = 751.56m3), reactor (V = 721.56m3), cyclone (A = 743.48 m2), grinder (Q = 1352.31 m3/h), compactor (Q = 1367.31 m3/h), correspondingly. A gate-to-gate life cycle assessment (LCA) was performed for life cycle impact assessment (LCIA) through GaBi by using the ReCiPe 2016 Mid-point (H) and Endpoint (H) approach with a functional unit of 1000 kg municipal solid waste (MSW). Significant findingsThe economic assessment reveals the economic feasibility of the biorefinery project. The annual revenue determined the profitability index, which is $ 1.59 million annually, with a payback period of 1.8 years. The environmental analysis determined an eco-friendly production unit which can save 13.6% of carbon emissions by alternate use of photovoltaic energy. Conclusively, the calculated values and findings prove that biorefinery development using OFMSW is scientifically a win-win situation and notably assists in achieving circular bioeconomy and sustainable development goals (SDGs).

Advancing biohydrogen production from organic fraction of municipal solid waste through thermal liquefaction

The study aims to examine the sustainability assessment within the circular bioeconomy of biohydrogen production from separated biomass from municipal solid waste (MSW). Successive biohydrogen production from the organic fraction of municipal solid waste (OFMSW) was deployed using hydrothermal liquefication in an innovative small-scale biorefinery system. The biomass was separated by the municipal solid and was dried, shredded, grinded and chopped before conversion. The feedstock was mixed with nickel oxide (5 % w/w) and saturated in distilled water with an 85 % volume-to-mass ratio. Temperature (200–400 °C) and pressure (7–25 MPa) were provided for a retention time of about 60 min with regular agitation. The optimization of parameters produced 207.3 kg of biohydrogen and 17.5 L of bio-oil, respectively. The economic assessment results revealed the feasibility of biohydrogen production with a total revenue of 13,669.02 $ per day and 306,718.4 $ in a month of 22 working days in a single shift of 8 h. The internal cost, capital sum (5,374,575.5 $) and operation cost (169,680.5 $) were calculated to 848,022.7 $. Notably, the top environmental impact emissions were recorded, such as carbon dioxide (CO2), methane (CH4), nitrogen oxides (NOx), carbon monoxide (CO), Non-methane volatile organic compound (NMVOC), particulate matter (PM), and sulfur dioxide with total external cost of 9.15 $. Thus, the life cycle costing was calculated at 848,031.84 $. The economic assessment revealed that photovoltaic energy instead of grid-mix energy reduces the environmental dilemma as Fine particulate matter formation from 0.25 kg PM2.5 eq. to 0.05 kg PM2.5 eq., Terrestrial ecotoxicity from 75.8 kg 1,4-DB eq. to 17.2 kg 1,4-DB eq., and Ionization radiation from 0.22 kBq Co-60 eq. to air to 0.06 kBq Co-60 eq. to air. Thus, it is proven that biohydrogen production from organic fraction of municipal solid waste is a win-win-win situation.

Bioenergy and Biorefinery Potential of Residues: A Representative Case of the Sucre Region in Colombia

AbstractAgricultural and agroindustrial residues are produced worldwide but these residues do not have a specific use. Then, a high potential to produce bioenergy and value-added products has been wasted. Biomass conversion routes should be proposed based on regional needs, making different upgrading processes more reliable and feasible. Thus, bioenergy applications should be analyzed as potential solutions before analyzing prospective products based on the biomass chemical composition. The objective of this research is to provide an approach for defining potential energy-driven applications of lignocellulosic biomass in developing countries with high availability of biomass sources as a result of the agricultural vocation of a region/country. As a case study, this paper shows the Sucre region in Colombia. A methodological approach to define thermochemical, anaerobic digestion, and biorefining upgrading pathways is provided based on chemical characterization, proximate analysis, fuel properties, and biogas production potential. Corn cobs, rice husk, cassava stem, and subverified cassava stem were the most suitable feedstocks for thermochemical upgrading. Avocado seeds, peels, and cassava leaves were selected as the most suitable raw materials for biogas production. Finally, plantain peel, rachis, and organic food waste were selected as potential and prospective raw materials in biorefinery systems to produce high-value-added products. Graphical Abstract

Economic and environmental implications of carbon capture in an olive pruning tree biomass biorefinery

This study explores the integration of bioenergy with carbon capture and storage (BECCS) in a biorefinery system that converts olive tree prunings into bioethanol and antioxidants. With a capacity to process 1,500 tons of prunings daily, the biorefinery yields an annual production of around 12,000 tons of antioxidants (purity >60 %) and 78,000 tons of bioethanol. Utilizing a holistic approach involving process simulations and life cycle assessment, our analysis covers technical, economic, and environmental dimensions across two scenarios differing in design and heating source: natural gas or a BECCS system using olive prunings. Our findings reveal the potential for BECCS to drastically reduce the carbon footprint, potentially achieving net-negative emissions (−84.37 kg CO2eq per 1.00 kg of bioethanol and 0.15 kg antioxidants produced). However, these environmental gains are counterbalanced by economic and environmental challenges, with investment and operating costs nearly doubling and leading to complex environmental trade-offs related to eutrophication (+75 %), increased water consumption (+45 %), and expanded land use (+80 %). Nevertheless, the premium nature of carbon-negative products, coupled with growing awareness and supportive policy frameworks, may overcome these economic barriers. This study highlights the importance of holistic evaluation when integrating CCS into biorefineries facilitating informed decision-making to address unintended adverse effects and promoting sustainability.

Characterization and utilization of industrial wastewater in biorefinery systems: A comprehensive approach

AbstractThis review explores the innovative utilization of industrial effluents in biorefinery applications, addressing the environmental challenges posed by the complex mixture of pollutants in industrial wastewater. It emphasizes the transformation of these effluents into valuable resources, such as biofuels, biochemicals, and bioplastics, through advanced biotechnological processes including anaerobic digestion, fermentation, enzymatic conversion, and microbial biomass production. The study highlights the critical role of microbial biocatalysts in breaking down diverse pollutants and transforming waste into wealth, thereby contributing to sustainable industrial practices and a circular economy. Challenges such as variability in effluent composition, inhibitory substances, and the necessity for robust bioprocesses are discussed, along with suggestions for future research directions like effluent characterization, development of specialized microbial consortia, and effective monitoring and control strategies. The review underscores the importance of collaboration between industry, academia, and government to advance biorefinery technologies, ultimately advocating for a sustainable and resource‐efficient future through the innovative treatment of industrial wastewaters.

Review of biofuel production technologies in biorefinery systems

Review of biofuel production technologies in biorefinery systems

THE MAKING OF LIQUID ORGANIC FERTILIZER FROM GINGER WASTE BY HIGH SCHOOL STUDENTS AT AL HIDAYAH DLANGGU MOJOKERTO

Introduction: After the production of "Hidayah" ginger drinks, there has been a significant accumulation of ginger waste around AL Hidayah High School. This waste has led to unpleasant odors, attracting flies and creating an unsightly environment. This community service program aims to repurpose ginger waste into something beneficial, such as liquid organic fertilizer. Methods: The community service project employed an educational approach followed by practical sessions in producing organic liquid fertilizer through a biorefinery system. All students at AL Hidayah High School in Dlanggu Mojokerto were involved in this activity, which took place on May 25, 2023. Results: The outcome of this initiative was the production of organic liquid fertilizer using biorefinery methods. Conclusion: The liquid organic fertilizer derived from ginger waste through biorefinery methods has the potential to mitigate several associated issues. It proves to be advantageous for the local community, serving as a plant nutrient and potentially contributing to the school's economic growth if produced in sufficient quantities for market distribution. Furthermore, this endeavor nurtured creativity and entrepreneurial skills among the students.

Comparative techno-economic and life cycle assessments of single and intercropped-mixed feedstocks-based biorefineries for profitable and cleaner production of energy

The role of intercropped mixed feedstocks (IMF) in advancing biorefineries is rarely studied. However, as opposed to conventional single feedstocks (SF) from monocropping systems (MCS), IMFs could potentially enhance the economic profitability of biorefineries by reducing the cost of feedstock transportation and overall operations due to high feedstock yield/ha and fewer inputs e.g., diesel. In addition, IMFs could improve environmental performance by minimizing emissions associated with feedstock farming inputs (e.g., fertilizer), transportation (e.g., diesel, and tear & wear), and overall operational requirements. Furthermore, intercropping systems (ICS) could mitigate feedstock yield uncertainties and ensure stable feedstock supply because legumes (e.g., pigeon peas) are drought-resistant and inhibit pests & diseases when intercropped with maize. Nonetheless, the actual benefits of IMFs must be quantified. Therefore, techno-economic and life cycle assessments were done, using the Malawian economic context, to evaluate IMFs of maize stover (MS) and pigeon pea stalks and leaves (PPSL) for ethanol, electricity, and biogas production in varying biorefinery capacities of 156 000 and 2184 000 mt/y. Four scenarios were investigated; MS from MCS (S1), MS from ICS (S2), MS and PPSL from ICS (S3), where PPSL was dedicated for combined heat & power (CHP), and MS and PPSL from ICS where MS was dedicated to CHP (S4). The biorefinery systems were simulated in Aspen Plus ® to obtain mass and energy balances (MEB) which were used in assessing economic performance via biorefinery gate feedstock cost (BGFC), net present value (NPV), and minimum product selling price (MPSP). BGFC was evaluated by aggregating the cost of buying feedstocks, labor, milling, baling, and transportation. Transportation cost was computed via summation of the cost of fuel, driving labor, depreciation, and maintenance influenced by transportation distance and feedstock yield/ha. MEBs were also used as input and output data in SimaPro software to estimate emissions in terms of fossil resource depletion (FRD), global warming potential (GWP), terrestrial acidification (TA), and freshwater eutrophication (FWE). The IMFs improve biorefineries' economic performance by reducing feedstock logistical cost and MPSP, and environmental performance by reducing FRD, GWP, TA, and FWE. For example, BGFC, MPSP & FRD for IMF's S3 were $228 million/t, $2.28/L & 135 kg oil eq/mt, respectively, compared to $258 million/t, $2.37/L, and 146 kg oil eq/mt respectively for MSF's S1 at 2184 000 mt/y. Thus, IMF improved BGFC, MPSP, and FRD by 12, 5, and 8%, respectively. Therefore, utilization of the IMFs can boost the economic and environmental performances of biorefineries.

Design a reducing CO2 emission system using nonfermentable substrates for carbon-economic biosynthesis of poly-2-hydrobutanedioic acid

Reducing carbon dioxide (CO2) emissions in the aerobic biorefinery system is becoming a crucial effort for achieving carbon-economic biosynthesis of biomaterials and chemicals. Poly-2-hydrobutanedioic acid (P2HBD), a long-carbon chain polyester produced by the fungus Aureobasidium pullulans, has garnered significant attention in the biomaterials and chemical industries. In this study, we designed a CO2 emission reduction system using nonfermentable substrates to enable efficient biosynthesis of P2HBD. Based on the genome-scale model iZX637 of A. pullulans, glycerol and ethanol were stimulated to show the potential advantages over glucose in terms of reduced CO2 emission. Additionally, we employed an NADH/NAD+ fluorescent probe called SoNar to dynamically monitor the reductive power ratio during CO2 emission. Subsequently, glycerol metabolism and rTCA carbon fixation pathway were engineered, while implementing a modular assembly strategy to achieve balanced integration between these two modules through precise promoter engineering regulation. The optimal strain ZX-LM03 showed the advantages of less carbon emission with glycerol and ethanol as the co-substrates, and achieved the higher P2HBD titer and yield of 15.07 ± 0.18 g/L and 0.54 ± 0.01 g/g, with the lower carbon emission of 31.08 % compared to glucose in the 5 L fermenter. In conclusion, this study provides novel insights into achieving carbon neutrality using renewable substrates for reducing carbon emission in aerobic fermentation systems.

Enhanced biomass and lipid production from olive processing wastewater using Scenedesmus obliquus in a two-stage cultivation strategy under salt stress

The study enhanced Scenedesmus obliquus cultivation via optimization of C/N and C/P ratios in synthetic media and evaluation of a two-stage cultivation strategy through application of salinity stress in olive processing wastewater-based feedstocks. S. obliquus under 40/1 C/N ratio performed biomass and lipid productivity that reached 0.15 and 34.1 mg L−1 d−1 respectively, demonstrating high glucose removal efficiency. Application of a two-stage cultivation strategy employing 0, 10, 20 and 30 g L−1 NaCl during the second bioprocess segment resulted in elevated biomass productivity (0.14–0.19 g L−1 d−1), which was reduced under batch mode yielding 0.11 g L−1 d−1. Two-stage cultivation triggered higher lipid productivity (4.2%-156.9%) following 3 d and 6 d upon the onset of the second stage (42.7–55.2 mg L−1 d−1) as compared to batch conditions, while the utilization of reducing sugars in exhausted olive pomace hydrolysates and table olive processing wastewater reached 53.6%-61.2%. Proline, glycerol and reactive oxygen species accumulated at considerable levels employing 20 and 30 g L−1 NaCl, indicating that S. obliquus expressed cellular stress under elevated salinity content, which was not notably stimulated using 10 g L−1 NaCl. The use of olive processing wastewater in a two-stage cultivation strategy under stress conditions enables future development of algal biorefinery systems for production of S. obliquus biomass and polyunsaturated fatty acids as high added-value products from biowaste.

A plant-wide modelling framework to describe microalgae growth on liquid digestate in agro-zootechnical biomethane plants

Microalgae cultivation on liquid digestate from the anaerobic co-digestion of agricultural feedstocks is an interesting option for digestate nutrient removal and resource recovery coupled to biomass generation. Both the reactors considered in such a biorefinery system involve complex bioprocesses. Although different pilot-scale systems coupling anaerobic digestion and algae-based bioremediation processes have been described, no previous attempts to model the entire system are available to date. In this work, a plant-wide model, named ADAB (anaerobic digestion algae-bacteria), is presented, coupling two well-established models for anaerobic digestion (IWA – ADM1) and algae-based bioremediation processes (ALBA). The models were modified with necessary equations and extensions to develop a dedicated model interface. Phosphorous dynamics were integrated, including activity corrections and precipitation processes. The ALBA model was also integrated with thermal modelling to simulate outdoor raceway ponds and greenhouse-covered systems. Solid/liquid separation units for digestate pre-treatment were also included. The prediction consistency of the adopted physicochemical sub-model (PCM) was verified with results from both reference literature and Visual MINTEQ. The reduced complexity of the PCM limits the model field of application, but it results in better computational performance and seems to be particularly suitable to simulate agro-zootechnical digesters. A scenario analysis including different co-digester design and operating conditions was carried out to assess the impacts on microalgae cultivation. It highlighted the importance of a proper biorefinery design and yet a noteworthy robustness of the system performance. The use of the ADAB model can facilitate a more realistic assessment of the technical, environmental, and economic feasibility of full-scale microalgal biorefineries based on digestate.

Thermal performance analysis of optimized biomass conversion in developing organic waste biorefinery to achieve sustainable development goals

To make energy sector sustainable, waste to energy system should be used, as statistics of the International Energy Agency (IEA) shows that the lack of renewable energy and environmental degradation are the major pressing problems confronting the global community. However, in south Asian regions, the situation escalates as a result of severe dependency on conventional energy sources, coupled with the limitations and challenges involved in maintaining a green environment and Waste-to-Energy (WtE) strategies. In this region, energy majorly relies on imported conventional fuel. In addition to harming the environment, imported fossil fuel has also increased the risk of geopolitical unrest. In the current research, rice husk is used as a bio-organic waste that is produced in large volumes and a significant byproduct of agro-based biomass sector. In this research, sample composition of rice husk is demineralized in 5% hydro-chloric acid for different burning ratios and the modified thermo-chemical methodology was used to the acidified rice husk at three different heating rates (20 °C min−1, 30 °C min−1 and 40 °C min−1) respectively in thermogravimetric analyzer (TGA). Proximate, thermal and kinetic analysis was used for observing the degradation patterns of demineralized rice husk. Proximate analysis revealed that the leaching of rice husk has successfully infused HCl, resulting in substantial rise in fixed carbon (FC) and calorific value (CV) by 10.53 % and 10.82 % respectively, along with decrease in the carbon footprint of about 60.55%. Thermogravimetric (TG) and derivative thermogravimetric (DTG) curves have shown decreasing behavior of conversion efficiency to the increase in flow rate, with the maximum drop of 12.7 % observed at 40 °C. With the use of the TGA equipment, the conversion efficiency was evaluated based on the sample's peak weight loss. The current study has reported synergistic effect of flow and heating rate on the degradation temperatures, activation energy and reactivity of acidified rice husk. Lowest activation energy 180.46 kJ permole with highest reactivity of 0.01192345 %*min °C was observed at 40 ml and 20 °C combination. Accordingly, degradation temperatures of burning profiles increased due to lower convective cooling and higher temperature gradient within the particle of rice husk sample. In addition, pre-exponential data and slopes of TG curves have validated the results of activation energy obtained from TGA experimentation. The sustainable biomass conversion approach is envisioned to significantly refine the waste bio refinery system to achieve SDGs.

Structural and thermal investigation of lignocellulosic biomass conversion for enhancing sustainable imperative in progressive organic refinery paradigm for waste-to-energy applications

The depletion of finite fossil fuel reserves and the severe environmental degradation resulting from human activities have compelled the expeditious development and application of sustainable waste to energy technologies. To encapsulate energy and environment in sustainability paradigm, bio waste based energy production is need to be forged in organic bio refinery setup. According to world bioenergy association, biomass can cover 50 % of the primary energy demand of the world. Therefore, the present study focuses on reforming the energy mix for a clean energy generation, where, sample composition of cotton stalk was acidified in dilute (5% wt.) hydrochloric acid (HCL) for analyzing material burnout patterns in biomass conversion systems utilized in organic bio refinery sector. Advanced thermochemical burning technique, which includes pyrolysis and combustion was applied at four different leaching times from 0 to 180 min under nitrogen environment from 0 °C to 500 °C and air from 500 °C to 900 °C, respectively. Different analyses including proximate, ultimate, gross calorific value (GCV), thermos-gravimetric, kinetic, XRD, FTIR, SEM-EDS were used for analyzing the degradation of demineralized cotton stalk at different treatment rates. Proximate study demonstrated that cotton stalk leaching for 180 min has efficiently infused HCL, leading in a significant increase in fixed carbon and higher heating value of 20.23 % and 12.48%, respectively, as well as a reduction in carbon footprint of around 54.80%. The findings of proximate was validated by GCV analysis and CHNS analysis as value of carbon and hydrogen has shown increasing behavior with the time delay in demineralization Thermo-gravimetric and derivative thermo-gravimetric data analyses shows an increasing trend of conversion efficiency, with the maximum increase of 98 % reported for sample 3H.TT.DEM. XRD characterization has reported 23° to 25° angle for all the observed peaks. Sample 3H.TT.DEM has shown maximum angle inclination along with matured crystalline peak. The latter observations has been validated by FTIR spectroscopy as sample 3H.TT.DEM has reported maximum O–H group formation. Sample 3H.TT.DEM has reported lowest activation energy of 139.51 kJ*mole-1 and lowest reactivity of 0.000293649%*min 0C, due to moderate and stable reactiveness. In SEM examination, increment in pore size and number of pores within the structural matrix of cotton stalk was observed with the enhancement in acidulation process. Furthermore, in EDS analysis, 3H.TT.DEM has shown most balanced distribution of the elements. In this research, sustainable transformation of biomass is envisioned to improve the waste bio refinery system, significantly contributing to the achievement of Sustainable Development Goals 7, 12 and 13.

Sustainability assessment of biofuel and value-added product from organic fraction of municipal solid waste

The current study aims to examine the techno-economic and environmental assessment of biorefinery development within a circular bioeconomy context by using an organic fraction of municipal solid waste (OFMSW) by extraction of lipids, carbohydrates, and proteins with 98, 51 and 62 % by mass of conversion efficiency and yield recovery, and value-added fractions production as well. Fatty acid methyl ester (biodiesel) and glycerol (biofuel) were produced by applying transesterification process, and the remaining biomass was converted into biocrude oil by thermal liquefication. The biorefinery using 613 kg of OFMSW produced biodiesel, glycerol, and bioethanol with 126 litter, 14.3 kg, and 172 litter respectively, as well as value-added fractions, such as biocrude oil with 78 kg. The environmental impact was assessed using the life cycle assessment (LCA) framework, ReCiPe2016 Mid-point (H) approach, through 18 different environmental categories. The key findings elucidate that Terrestrial ecotoxicity, Climate change, Fossil depletion and Human toxicity were the main impact categories which are potentially contributed 9.81E+02 kg 1,4-DB eq., 1.43E+03 kg CO2 eq., 2.04E+02 kg oil eq., and 8.08E+01 kg 1,4-DB eq. The normalization (person per equivalent) analysis revealed that only categories of resource reduction (fossil and metal depletion) are the key contributors to environmental degradation. The biorefinery system's total revenue was estimated at USD 6.817,509 million annually. The calculated revenue was USD 0.026 million daily in a shift of 8 h. The Net present worth (NPW) was calculated at USD 499.97 million by assuming a discount factor of 10 % and inflation rate of 5 % for 15 years. The project is considered feasible by demonstrating 7.15 payback year. This research showcased the efficient portrayal of the biorefinery system and succinctly conveyed the significant circular bioeconomy for a greener future. Thus, it could be helpful to the stakeholder's context towards techno-economic and environmental evaluation.