We used an innovative approach involving hot pressing, low energy consumption, and no adhesive to transform bamboo biomass into a natural sustainable fiber-based biocomposite for structural and furniture applications. Analyses showed strong internal bonding through mechanical "nail-like" nano substances, hydrogen, and ester and ether bonds. The biocomposite encompasses a 10-fold increase in internal bonding strength with improved water resistance, fire safety, and environmentally friendly properties as compared to existing furniture materials using hazardous formaldehyde-based adhesives. As compared to natural bamboo material, this new biocomposite has improved fire and water resistance, while there is no need for toxic adhesives (mostly made from formaldehyde-based resin), which eases the concern of harmful formaldehyde-based VOC emission and ensures better indoor air quality. This surpasses existing structural and furniture materials made by synthetic adhesives. Interestingly, our approach can 100% convert discarded bamboo biomass into this biocomposite, which represents a potentially cost reduction alternative with high revenue. The underlying fragment riveting and cell collapse binding are obviously a new technology approach that offers an economically and sustainable high-performance biocomposite that provides solutions to structural and furniture materials bound with synthetic adhesives.
A study was performed to determine the effect of Conway and f/2 media on the growth of microalgae genera. Genera of Chlorella sp., Dunaliella sp., Isochrysis sp., Chaetoceros sp., Pavlova sp. and Tetraselmis sp. were isolated from the South China Sea. During the cultivation period, the density of cells were determined using Syringe Liquid Sampler Particle Measuring System (SLS-PMS) that also generated the population distribution curve based on the size of the cells. The population of the microalgae genera is thought to consist of mother and daughter generations since these microalgae genera reproduce by releasing small non-motile reproductive cells (autospores). It was found that the reproduction of Tetraselmis sp., Dunaliella sp. and Pavlova sp. could be sustained longer in f/2 Medium. Higher cell density was achieved by genus Dunaliella, Chlorella and Isochrysis in Conway Medium. Different genera of microalgae had a preference for different types of cultivation media.
This study demonstrates the use of NMR techniques coupled with chemometric analysis as a high throughput data mining method to identify and examine the efficiency of different disruption techniques tested on microalgae (Chlorella variabilis, Scenedesmus regularis and Ankistrodesmus gracilis). The yield and chemical diversity from the disruptions together with the effects of pre-oven and pre-freeze drying prior to disruption techniques were discussed. HCl extraction showed the highest recovery of oil compounds from the disrupted microalgae (up to 90%). In contrast, NMR analysis showed the highest intensity of bioactive metabolites obtained for homogenized extracts pre-treated with freeze-drying, indicating that homogenizing is a more favorable approach to recover bioactive substances from the disrupted microalgae. The results show the potential of NMR as a useful metabolic fingerprinting tool for assessing compound diversity in complex microalgae extracts.
This study focuses on the evaluation of the performance of Chlorella sp. in removing nutrient in aquaculture wastewater and its correlation with the kinetic growth of Chlorella sp. The treatment was applied with various Chlorella sp. inoculation dosage ranging from 0% to 60% (v/v) of wastewater. The optimum inoculation dosage was recorded at 30% (v/v) with effluent concentration of ammonia and orthophosphate recording at 0.012mgL(-1) and 0.647mgL(-1), respectively on Day 11. The optimum dosage for bio-flocculation process was obtained at 30mgL(-1) of Aspergillus niger with a harvesting efficiency of 97%. This type of development of phytoremediation with continuous bio-harvesting could promote the use of sustainable green technology for effective wastewater treatment.
Steam and air gasification with 5 wt% Ni/Al2O3 eggshell (Ni-EG) and homo (Ni-H) catalysts were performed for the first time to produce biohydrogen from food waste. The steam gasification produced comparably higher gas yield than air gasification. In non-catalytic experiments, steam gasification generated a higher volume percent of H2, whereas more CO, CO2, CH4, and C2-C4 were produced in air gasification. Ni-EG demonstrated higher potential to obtain H2-rich gases with a low C2-C4 content compared to that obtained by Ni-H, particularly in steam gasification at 800 °C, which produced gaseous products with 59.48 vol% H2. The long-term activity of both catalysts in steam gasification was evaluated, and Ni-EG exhibited higher stability than Ni-H. The ideal distribution of Ni species on the outer region of γ-Al2O3 pellets in Ni-EG resulted in higher activity, stability, and selectivity than Ni-H in both steam and air gasification.
Hydrogen and gaseous fuel derived from wastes have opened up promising alternative pathways for the production of renewable and sustainable fuels to substitute classical fossil energy resources that cause global warming and pollution. Existing review articles focus mostly on gasification, reforming and pyrolysis processes, with limited information on particularly gaseous fuel production via pyrolysis of various waste products. This review provides an overview on the recent advanced pyrolysis technology used in hydrogen and gaseous fuel production. The key parameters to maximize the production of specific compounds were discussed. More studies are needed to optimize the process parameters and improve the understanding of reaction mechanisms and co-relationship between these advanced techniques. These advanced techniques provide novel environmentally sustainable and commercially procedures for waste-based production of hydrogen and gaseous fuels.
To valorize biomass waste, pyrolysis of orange peel was mainly investigated as a case study. In an effort to establish a more sustainable thermolytic platform for orange peel, this study particularly employed CO2 as reactive gas medium. Accordingly, this study laid great emphasis on elucidating the mechanistic role of CO2 in pyrolysis of orange peel. The thermo-gravimetric analysis (TGA) confirmed that no occurrence of the heterogeneous reactions between the solid sample and CO2. However, the gaseous effluents from pyrolysis of orange peel experimentally proved that CO2 effectively suppressed dehydrogenation of volatile matters (VMs) evolved from the thermolysis of orange peel by random bond scissions. Moreover, CO2 reacted VMs, thereby resulting in the formation of CO. Note that the formation of CO was being initiated at temperatures ≥550 °C. The two identified roles of CO2 led to the compositional modification of pyrolytic oil by means of lowering aromaticity.
The demands of energy sustainability drive efforts to bio-chemical conversion of biomass into biofuels through pretreatment, enzymatic hydrolysis, and microbial fermentation. Pretreatment leads to significant structural changes of the complex lignin polymer that affect yield and productivity of the enzymatic conversion of lignocellulosic biomass. Structural changes of lignin after pretreatment include functional groups, inter unit linkages and compositions. These changes influence non-productive adsorption of enzyme on lignin through hydrophobic interaction and electrostatic interaction as well as hydrogen bonding. This paper reviews the relationships between structural changes of lignin and enzymatic hydrolysis of pretreated lignocellulosic biomass. The formation of pseudo-lignin during dilute acid pretreatment is revealed, and their negative effect on enzymatic hydrolysis is discussed.
In this study, process optimization for the microalgae-based piggery wastewater treatment was carried out by growing Chlorella sorokiniana AK-1 on untreated piggery wastewater with efficient COD/BOD/TN/TP removal and high biomass/protein productivities. Integration of the immobilization carriers (sponge, activated carbon) and semi-batch cultivation resulted in the effective treatment of raw untreated piggery wastewater. With 100% wastewater, 0.2% sponge and 2% activated carbon, the semi-batch cultivation (90% media replacement every 6 days) exhibited a COD, BOD, TN and TP removal efficiency of 95.7%, 99.0%, 94.1% and 96.9%, respectively. The maximal protein content, protein productivity, lutein content, and lutein productivity of the obtained microalgal biomass was 61.1%, 0.48 g/L/d, 4.56 mg/g, and 3.56 mg/L/d, respectively. The characteristics of the treated effluent satisfied Taiwan Piggery Wastewater Discharge Standards (COD
In recent years, visualization and characterization of lignocellulose at different scales elucidate the modifications of its ultrastructural and chemical features during hydrothermal pretreatment which include degradation and dissolving of hemicelluloses, swelling and partial hydrolysis of cellulose, melting and redepositing a part of lignin in the surface. As a result, cell walls are swollen, deformed and de-laminated from the adjacent layer, lead to a range of revealed droplets that appear on and within cell walls. Moreover, the certain extent morphological changes significantly promote the downstream processing steps, especially for enzymatic hydrolysis and anaerobic fermentation to bioethanol by increasing the contact area with enzymes. However, the formation of pseudo-lignin hinders the accessibility of cellulase to cellulose, which decreases the efficiency of enzymatic hydrolysis. This review is intended to bridge the gap between the microstructure studies and value-added applications of lignocellulose while inspiring more research prospects to enhance the hydrothermal pretreatment process.
A micro-mesoporous activated carbon (AC) was produced via an innovative approach combining microwave pyrolysis and chemical activation using NaOH/KOH mixture. The pyrolysis was examined over different chemical impregnation ratio, microwave power, microwave irradiation time and types of activating agents for the yield, chemical composition, and porous characteristic of the AC obtained. The AC was then tested for its feasibility as textile dye adsorbent. About 29 wt% yield of AC was obtained from the banana peel with low ash and moisture (<5 wt%), and showed a micro-mesoporous structure with high BET surface area (≤1038 m2/g) and pore volume (≤0.80 cm3/g), indicating that it can be utilized as adsorbent to remove dye. Up to 90% adsorption of malachite green dye was achieved by the AC. Our results indicate that the microwave-activation approach represents a promising attempt to produce good quality AC for dye adsorption.
Microwave vacuum pyrolysis of palm kernel shell was examined to produce engineered biochar for application as additive in agriculture application. The pyrolysis approach, performed at 750 W of microwave power, produced higher yield of porous biochar (28 wt%) with high surface area (270 cm2/g) compared to the yield obtained by conventional approach (<23 wt%). Addition of the porous biochar in mushroom substrate showed increased moisture content (99%) compared to the substrate without biochar (96%). The mushroom substrate added with biochar (150 g) was optimal in shortening formation, growth, and full colonization of the mycelium within one month. Using 2.5% of the biochar in mushroom substrate desirably maintained the optimum pH level (6.8-7) during the mycelium colonization period, leading to high mycelium growth (up to 91%) and mushroom yield (up to 280 g). The engineered biochar shows great potential as moisture retention and neutralizing agent in mushroom cultivation.
The global economy is threatened by the depletion of fossil resources and fluctuations in fossil fuel prices, and thus it is necessary to exploit sustainable energy sources. Carbon-neutral fuels including bio-oil obtained from biomass pyrolysis can act as alternatives to fossil fuels. Co-pyrolysis of lignocellulosic biomass and plastic is efficient to upgrade the quality of bio-oil because plastic facilitates deoxygenation. However, catalysts are required to produce bio-oil that is suitable for potential use as transportation fuel. This review presents an overview of recent advances in catalytic co-pyrolysis of biomass and plastic from the perspective of chemistry, catalyst, and feedstock pretreatment. Additionally, this review introduces not only recent research results of acid catalysts for catalytic co-pyrolysis, but also recent approaches that utilize base catalysts. Future research directions are suggested for commercially feasible co-pyrolysis process.
An innovative approach was developed by incorporating high-pressure CO2 into the separate hydrolysis-fermentation of aspen leftover branches, aiming to enhance the bioethanol production efficiency. The high-pressure CO2 significantly increased the 72-h enzymatic hydrolysis yield of converting aspen into glucose from 53.8% to 82.9%. The hydrolysis process was performed with low enzyme loading (10 FPU g-1 glucan) with the aim of reducing the cost of fuel bioethanol production. The ethanol yield from fermentation of the hydrolyzed glucose using yeast (Saccharomyces cerevisiae) was 8.7 g L-1, showing increment of 10% compared with the glucose control. Techno-economic analysis indicated that the energy consumption of fuel bioethanol production from aspen branch chips was reduced by 35% and the production cost was cut 44% to 0.615 USD L-1, when 68 atm CO2 was introduced into the process. These results furtherly emphasized the low carbon footprint of this sustainable energy production approach.
Thermal co-processing of lignocellulosic and aquatic biomass, such as algae and shellfish waste, has shown synergistic effects in producing value-added energy products with higher process efficiency than the traditional method, highlighting the importance of scaling up to pilot-scale operations. This article discusses the design and operation of pilot-scale reactors for torrefaction, pyrolysis, and gasification, as well as the key parameters of co-processing biomass into targeted and improved quality products for use as fuel, agricultural application, and environmental remediation. Techno-economic analysis reveals that end product selling price, market dynamics, government policies, and biomass cost are crucial factors influencing the sustainability of thermal co-processing as a feasible approach to utilize the biomass. Because of its simplicity, pyrolysis allows greater energy recovery, while gasification has the highest net present value (profitability). Integration of liquefaction, hydrothermal, and fermentation pre-treatment technology has the potential to increase energy efficiency while reducing process residues.
Household food waste (FW) was converted into biohydrogen-rich gas via steam gasification over Ni and bimetallic Ni (Cu-Ni and Co-Ni) catalysts supported on mesoporous SBA-15. The effect of catalyst method on steam gasification efficiency of each catalyst was investigated using incipient wetness impregnation, deposition precipitation, and ethylenediaminetetraacetic acid metal complex impregnation methods. H2-TPR confirmed the synergistic interaction of the dopants (Co and Cu) and Ni. Furthermore, XRD and HR-TEM revealed that the size of the Ni particle varied depending on the method of catalyst synthesis, confirming the formation of solid solutions in Co- or Cu-doped Ni/SBA-15 catalysts due to dopant insertion into the Ni. Notably, the exceptional activity of the Cu-Ni/SBA-15-EMC catalyst in FW steam gasification was attributed to the fine distribution of the concise Ni nanoparticles (9 nm), which resulted in the highest hydrogen selectivity (62 vol%), gas yield (73.6 wt%). Likewise, Cu-Ni solid solution decreased coke to 0.08 wt%.
Recent studies show that fast hydropyrolysis (i.e., pyrolysis under hydrogen atmosphere operating at a rapid heating rate) is a promising technology for the conversion of biomass into liquid fuels (e.g., bio-oil and C4+ hydrocarbons). This pyrolysis approach is reported to be more effective than conventional fast pyrolysis in producing aromatic hydrocarbons and also lowering the oxygen content of the bio-oil obtained compared to hydrodeoxygenation (a common bio-oil upgrading method). Based on current literature, various non-catalytic and catalytic fast hydropyrolysis processes are reviewed and discussed. Efforts to combine fast hydropyrolysis and hydrotreatment process are also highlighted. Points to be considered for future research into fast hydropyrolysis and pending challenges are also discussed.
Biofuels have become an attractive energy source because of the growing energy demand and environmental issues faced by fossil fuel consumption. Algal biomass, particularly microalgae, has excellent potential as feedstock to be converted to bio-oil, biochar, and combustible syngas via thermochemical conversion processes. Third-generation biofuels from microalgal feedstock are the promising option, followed by the first-generation and second-generation biofuels. This paper provides a review of the applications of thermochemical conversion techniques for biofuel production from algal biomass, comprising pyrolysis, gasification, liquefaction, and combustion processes. The progress in the thermochemical conversion of algal biomass is summarized, emphasizing the application of pyrolysis for its benefits over other processes. The review also encompasses the challenges and perspectives associated with the valorization of microalgae to biofuels ascertaining the potential opportunities and possibilities of extending the research into this area.
Appropriate bioprocessing of lignocellulosic materials into ethanol could address the world's insatiable appetite for energy while mitigating greenhouse gases. Bioethanol is an ideal gasoline extender and is widely used in many countries in blended form with gasoline at specific ratios to improve fuel characteristics and engine performance. Although the bioethanol production industry has long been operational, finding a suitable microbial agent for the efficient conversion of lignocelluloses is still an active field of study. Among available microbial candidates, engineered bacteria may be promising ethanol producers while may show other desired traits such as thermophilic nature and high ethanol tolerance. This review provides the current knowledge on the introduction, overexpression, and deletion of the genes that have been performed in bacterial hosts to achieve higher ethanol yield, production rate and titer, and tolerance. The constraints and possible solutions and economic feasibility of the processes utilizing such engineered strains are also discussed.
Rapid growth of aquatic weeds in treatment pond poses undesirable challenge to shellfish aquaculture, requiring the farmers to dispose these weeds on a regular basis. This article reviews the potential and application of various aquatic weeds for generation of biofuels using recent thermochemical technologies (torrefaction, hydrothermal carbonization/liquefaction, pyrolysis, gasification). The influence of key operational parameters for optimising the aquatic weed conversion efficiency was discussed, including the advantages, drawbacks and techno-economic aspects of the thermochemical technologies, and their viability for large-scale application. Via extensive study in small and large scale operation, and the economic benefits derived, pyrolysis is identified as a promising thermochemical technology for aquatic weed conversion. The perspectives, challenges and future directions in thermochemical conversion of aquatic weeds to biofuels were also reviewed. This review provides useful information to promote circular economy by integrating shellfish aquaculture with thermochemical biorefinery of aquatic weeds rather than disposing them in landfills.