In this study, Chlorella sp., Scenedesmus sp., and their consortium were used for the biorefinery approach. The algal consortium (Chlorella sp. + Scenedesmus sp.) grown well in 75% diluted ...wastewater, and obtained the highest biomass (1.78 g L−1), chlorophyll (27.03 μg mL−1), protein (175 μg mL−1) and lipid content (34.83% dry cell weight). Algal consortium showed mainly 51.75% of palmitic acid and 35.45% of oleic acid in the lipids. The removal of nitrate, ammonium, phosphate, chemical oxygen demand, total organic carbon and total nitrogen in 75% diluted wastewater by algal consortium were 96%, 98%, 95%, 83%, 86% and 94%, respectively. Moreover, deoiled algal biomass (DAB) waste used as a biofertilizer combined with inorganic fertilizer resulted in the grater improvement of Solanum lycopersicum shoot length (44%), root length (89%), fresh weight (95%), dry weight (53%), macro and micro-nutrients (N 61%, P 179%, K 71%, Ca 38%, Mg 26% and Fe 11%), and tomato yield (174%) as compared to control treatment. Our results indicate that the use of consortium is not only a potential bioresource for wastewater treatment and biodiesel production but also the DAB waste is an effective biofertilizer for sustainable agriculture production.
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•Chlorella sp. + Scenedesmus sp. produced 1.78 g L−1 of biomass in 75% wastewater.•Algal consortium obtained 78–98% nutrients removal rates in 25–100% wastewater.•Algal consortium had higher amount of C16:0 and C18:1 fatty acids in the lipids.•Wastewater grown algal biomass as a potential feedstock for biodiesel production.•Application of 50% DAB3 + 50% NPK fertilizers were improved the tomato plants yield.
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•Hydrothermal liquefaction is an effective method for the conversion of biomass into biofuel.•Selection of appropriate catalyst is important for achieving high bio-oil yields with ...high quality.•Catalytic hydrothermal liquefaction of biomass to biofuel are discussed in detail.
Hydrothermal liquefaction (HTL) is an effective method for the conversion of biomass into biofuel involving moderate temperature and high pressure. However, the yield and quality of bio-oil are not sufficient for commercialization under normal HTL conditions. In this regard, the review emphasizes the need to select the appropriate catalyst for achieving high bio-oil yields with improved quality. Besides, the factors influencing the catalytic HTL, including the types of catalyst used in HTL, the mechanism of catalytic-HTL reaction, the effect of the catalyst on other HTL products including biochar, aqueous phase extracts, and gas, are discussed in detail. This review also summarizes by mentioning the barriers to be overcome in catalytic HTL by focusing on promising approaches.
•Analyzing the recent developments in pyrolysis processes of microalgae.•Mechanism of the various types of pyrolysis was summarized.•Biochemical composition was discussed in detail.•Microwave ...assisted pyrolysis has achieved more significance than other process.•Quality of the bio-oil in catalytic pyrolysis was higher than thermal pyrolysis.
Algae become reasonable feedstock in recent times for biofuel production as they are environmentally benign, sustainable and renewable biomass. Biofuels are produced from algal biomass by chemical, biochemical, and thermochemical methods. Among the thermochemical techniques, pyrolysis is a well-known method involving high temperature and high pressure to produce biochar and bio-oil from numerous algal biomasses. Therefore, this review was undertaken to collate and discuss different pyrolytic processes employed for the conversion of algal biomass into biochar and bio-oil production. At the outset, different pyrolysis methods slow pyrolysis, fast/flash pyrolysis, catalytic pyrolysis, microwave assisted pyrolysis and hydropyrolysis operated for the conversion of various microalgae and cyanobacteria into biochar and bio-oil were reviewed using copious literature. Further, challenges arisen out of using above-said pyrolysis methods were critically highlighted to pave the way to choose an appropriate pyrolysis method for obtaining desirable quantity and quality of bio-oil from algae.
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•The present fossil fuel, energy demand and need for sustainable biofuels were reviewed.•Effect of light intensity, color and photoperiod on lipid content was discussed.•Effect of ...different pH and CO2 levels on microalgal growth and lipid were distinguished.•Mechanisms of photo-inhibition and photo damage to algal cells have been described.
This paper reviews the different cultivation conditions such as temperature, light intensity, and pH for enhancing lipid accumulation for green fuel production. The various levels of physical factors on the lipid yield and growth of algae with respect to biofuel production have been discussed in this review. Initially, the bottlenecks in microalgal biodiesel production have been highlighted and the need for optimal conditions for lipid accumulation have been analyzed. Further, the impact of the cultivation conditions such as light intensity/color, temperature, and CO2 concentration were comprehensively interpreted to understand how lipid accumulation in microalgae can be enhanced in the perspective of biofuel production. Besides, all the recent advancements and experimental works on biomass and lipid production in microalgae concerning the effect of different light intensities and color, temperature regimes, CO2 concentration and pH ranges are discussed and summarized.
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Lignocelluloses’ pretreatment is targeted for the improvement of hydrolysis of their carbohydrates, i.e., cellulose and hemicelluloses. Modification of the hardheaded structure of ...lignocelluloses is a fundamental stair in biofuels and biochemicals production. The high crystalline configurations of cellulose embed with hemicelluloses and lignin, give rise to recalcitrance structure. Second-generation biofuel production processes, using lignocellulosic biomass as a feedstock, is based on a three-stage process, including pretreatment, enzymatic hydrolysis, and fermentation. The pretreatment stage is the most critical, influencing, costly stage. The perfect pretreatment process is designated to provide minimum cellulosic crystallinity with remarkable low lignin content as well as inhibitory compounds through a sustainable economical process. In the present review, advances in lignocellulosic pretreatment technologies for biofuels production are reviewed and critically discussed. The article further discusses the pros and cons of the various pretreatment methodologies as well as addresses the role and impact of different process parameters associated with the pretreatment process.
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Thermochemical methods namely pyrolysis, gasification/hydrothermal gasification, combustion, hydrothermal liquefaction and hydrothermal carbonization are widely practiced to convert ...algal biomass into fuels. Among the methods, pyrolysis, and hydrothermal liquefaction are most commonly practised to convert numerous algal biomasses into bio-oil and/or biochar to substitute crude oil in petroleum refinery. In this regard, this review is focused on the conversion of various microalgal; and cyanobacterial biomasses into bio-oil, and solid char products through pyrolysis and hydrothermal liquefaction. Initially, pyrolysis and hydrothermal liquefaction of algal biomass on bio-oil and biochar yield have been reviewed. As the composition and yield of bio-oil from algae depends on the reaction temperature, detailed account of the impact of temperature on the quantity and quality of bio-oil and solid char obtained from pyrolysis and hydrothermal liquefaction were comprehensively presented in the review. Eventually, this article provides opportunities and scope in the pyrolysis and hydrothermal liquefaction of algae for further research.
•Fabrication of biomass skin derived carbon materials from biomass precursors.•The highly porous carbon network offers micro/mesoporous nature.•The chemical activation approach led to improved ...surface area and conductivity.•This structure showed high capacitance of 333 F/g at 0.5 A/g for supercapacitors.
The activated carbon was obtained from casuarina bark skin (CBS). CBS were carbonized by 9 M concentrated sulfuric acid (H2SO4) and activated by a chemical activation process by adjusting the concentration of KOH in simple microwave pyrolysis. Obtained activated carbon sample has a defined surface area of about 4588 m2/g. In this study, the activator was KOH solution, is used to synthesise activated carbon from biomass.The activated carbon is created from casuarina bark skin in a 3 wt% KOH solution, and the resulting activated carbon material had a high specific capacitance of 333 F/g and a current density of 0.5 A/g. After 5000 cycles of testing, the produced activated carbon show extreme durability. According to the findings, biomass such as casuarina bark may be utilized to produce activated carbon, which can be used as a substitute for traditional anode materials in supercapacitor applications.
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•Methanol-to-olefins (MTO) conversion process is one of the most preferentially selected routes to synthesize olefins.•Selectivity of olefins products remains a challenge due to lower ...catalysts lifetime.•SAPO-34, silicoaluminophosphate zeolite based catalysts proved to be the best commercial catalysts for MTO conversion.•Coke formation, crystal size, acid strength, and metal incorporation are crucial factors to control MTO products yield.•Higher the temperature lesser would be the olefins selectivity due to higher coke formation.
There is a rising demand for light olefins production to meet the increase in human population, burgeoning transportation network and rapid pace of industrialization. Methanol-to-olefins (MTO) conversion process is the most preferentially-selected route to synthesize olefins even though obtaining the high selectivity remains a challenge to this day. Methanol is industrially-produced via two-steps catalytic routes, viz. gasification of coal to syngas followed by syngas conversion. Due to the abundance of methanol, conversion of methanol to light olefins (ethylene and propylene) or polyolefins (polypropylene and high-density polyethylene) is most desired. Although, natural gas or syngas routes are well established and implemented at industrial level but still direct or indirect transformation of methanol to petrochemicals gained core interest. Significantly, the use of molecular sieves as a catalyst support or directly as a catalyst has been an area of active commercial developments for the past two decades. The engineered molecular sieves possess specialized topographical structure that can efficiently reduce the rate of coke deposition, enhance mass transport and improve the catalytic performance, viz. lifetime and olefins selectivity for methanol to olefins reaction. In this regard, the SAPOs molecular sieves are highly selective for the synthesis of ethylene and propylene. Among them, SAPO-34 molecular sieves exhibit the best performance for the MTO process. The current review highlights the importance of SAPO-34 supported catalysts in terms of lower chain hydrocarbon (C2–C4) selectivity, lower paraffinic and aromatic by-products ratio, catalyst stability, and renderability. In addition, the conditions causing the SAPO-34 catalysts deactivation such as coking, crystal size, water content, pressure metal incorporation, acid site strength, and influence of process conditions on triglyceride-based feeds are also thoroughly reviewed.
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•Global market and scope for Biobutanol as an alternative fuel is analysed.•Biobutanol formation from I, II and III generation Biomass is elaborated.•Different strategies used in ...Biobutanol synthesis of covered.•Hindrances in Biobutanol generation are focussed.•Properties of Biobutnaol vs biofuels and fossil fuels are compared.•Modifications demonstrated in application of Biobutanol are provided.
Biobutanol is considered to be the new generation fuel and it is reported to be an efficient fuel than the other known biofuels due to its both physical and chemical features. The anaerobic fermentation of lignocellulosic biomass is the possible route for the production of biobutanol. The hindrances faced in the production of biobutanol are the cost of production, time consumption, and sporulation stage, which blocks the solvent production. Several works have focused to reduce the difficulties and challenges in biobutanol production. The preparation methodology, reactor designs, and genetically engineered microbes have definitely shown the solution to the problems. In this connection, this review will detail the existing troubles faced during biobutanol production, and the overview of research activities proposed to solve the troubles were also presented. The comprehensive look of production methodologies is briefly explained and the recent genetic engineering approaches and computational ways to improve biobutanol production are covered. Further, the characteristics, engine compatibility of biobutanol, and difficulties towards its commercialization were also projected.
•Photobioreactor, open pond and flask cultivation of Chlorella sp. was compared.•Photobioreactor showed higher biomass yield, productivity and chlorophyll content.•All cultivation systems showed ...higher lipid & neutral lipids from stationary phase culture.•Similar fatty acids pattern from cultures grown in all cultivation systems was seen.•γ-Linolenic acid (14–15%) and palmitic acid (11–13%) are prevalent fatty acids.
Microalgae are the promising feedstock for biodiesel production than other first and second-generation feedstocks. Generating huge biomass sustainably per unit volume per day is vital to the continuous utilization of algal feedstock for sustainable biodiesel production. But, cultivation and harvesting of microalgae are the significant cost drivers and the commonly used cultivation systems for microalgae are outdoor pond and photobioreactor. In this study, small scale photobioreactor, outdoor open pond and Erlenmeyer flask based cultivation of Chlorella sp. and harvesting at log phase and stationary phase for biomass, lipids towards FAME (fatty acid methyl ester) production was investigated. Photobioreactor grown Chlorella sp. showed higher growth in terms of biomass yield, biomass productivity and chlorophyll content. In the case of lipid content, Chlorella sp. unveiled a similar percentage of lipid about 20% (log phase) and 24% (stationary phase) irrespective of the cultivation systems tested. Non-polar lipid percentage 46% in log phase, while in stationary phase, Chlorella sp. showed higher levels of non-polar lipids at about 66% in photobioreactor and open pond systems. A similar pattern of fatty acids was seen from cultures grown in all three cultivation systems and among identified fatty acids, γ-linolenic acid is prevalent in the range between 14 and 15% followed by palmitic acid in the range between 11 and 13%.
