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Enormous annual sewage sludge (SS) volumes pose global environmental challenges owing to contamination and significant greenhouse gas emissions. Here, we investigated the economic viability of co-pyrolyzing SS and biomass waste to produce biofuels (bio-oil and gas) and biochar. Net present worth (NPW) analysis, the sale product break-even price, and sludge handling price (SHP) were used to determine the profitability of co-pyrolysis compared with SS pyrolysis alone and conventional treatment methods. In this study, the sale prices of biochar based on quality (i.e., stability, carbon sequestration effectiveness, and heavy metal content) were estimated to be 2.24, 1.44, and 0.98 CAD/kg for high-, medium-, and low-grade biochar. The bio-oil prices, estimated based on the higher heating values of bio-oil and diesel, ranged from 0.80 to 1.22 CAD/kg. Sawdust (SD) and wheat straw (WS) were the chosen co-pyrolysis feedstocks, with four mixing ratios (20, 40, 60, and 80 wt%). Economically, SD (40 wt% mixing ratio) co-pyrolysis achieved the best performance, with a maximum NPW of 8.71 million CAD. SD single and co-pyrolysis were the only profitable scenarios. Moreover, SS single pyrolysis and WS co-pyrolysis exhibited higher profitability than conventional SS treatment methods, with SHPs of 65 and 40 CAD/1000 kg dry sludge, respectively. Sensitivity analysis highlighted the dependence of economic performance on biochar and bio-oil market value. This study offers the first economic analysis of this approach and enhances our understanding of the potential of co-pyrolysis for biofuel and biochar production, providing innovative solutions for the environmental challenges of SS disposal. [Display omitted] • Cost, operating expenses, and energy recovery of a pyrolysis plant were evaluated. • Co-pyrolyzing SS with sawdust SS showed the highest NPW of 8.71 million CAD. • All single and co-pyrolysis cases showed higher revenue than SS disposal methods. • Economic feasibility was dependent on bio-oil and biochar quality and sales price. [ABSTRACT FROM AUTHOR]

• CO 2 helps to modify properties of biochar made via pyrolysis. • Porosity of biochar can be improved when CO 2 is used in the pyrolysis. • The modification approach can be applied to precisely engineer biochar for various applications. Biochar is widely used for various environmental remediation strategies such as soil amendment because of its intrinsic carbon negativity and porosity. Biochar is a charcoal-like material produced via pyrolysis of biomass. To determine an effective method for modification of the porosity and morphology of biochar and establishment of a more sustainable pyrolysis platform for biomass valorization, this study used CO 2 as a reactive gas medium in the biomass pyrolysis process. This study placed emphasis on elucidating the role of CO 2 in the production of biochar from different types of biomass, such as cellulose, xylan, lignin, grass, and oak wood. The surface area and porosity of biochar were strongly related to the type of biomass. Under comparable pyrolysis conditions, the surface area of biochar decreased in the following order: cellulose > xylan > lignin ∼ oak wood > grass. The use of CO 2 as the gas medium in biomass pyrolysis affected the surface area and porosity of biochar samples derived from biomass feedstock. For instance, the surface area and total pore volume of the oak-wood-derived biochar produced in the CO 2 environment were twice those produced in the N 2 environment. Given that the increases in the biochar surface area and porosity were attributed to the enhanced release of volatile organic compounds (VOCs) from biomass, CO 2 may have enhanced VOC release (removal) during pyrolysis. Therefore, the use of CO 2 in a pyrolysis platform is expected to be a strategic approach for biomass valorization. [ABSTRACT FROM AUTHOR]

• A sulfonated biochar is prepared by sulfonation method of 4-chlorobenzenesulfonic acid. • The sulfonated biochar have a strong hydrophobic network and acid density. • The catalyst is highly active for the esterification reactions. • The catalyst is active and selective for alkylation reactions. • The catalyst is stable for five runs. Catalytic esterification of fatty acid with methanol, alkylation of 4-ethylphenol with benzyl alcohol as well as 2-methylfuran with cyclopentanone are of great significant for the production of biofuels. However, the in-situ produced water decreases the acidity of catalyst and induces side reaction, leading to an unsatisfactory catalytic activity and selectivity. Herein, a novel biochar-based hydrophobic benzenesulfonic acid is prepared for the first time by one-pot sulfonation method of biochar with 4-chlorobenzenesulfonic acid. It has a large specific surface area of 100-400 m2/g, a hydrophobicity with H 2 O contact angle higher than 110° and a high concentration of sulfonic acid over 1.0 mmol/g. In the esterification reaction of fatty acid with methanol for synthesis of biodiesel, it shows a higher conversion of 96.0% than sulfonic acid resin amberlyst-15 (86.7%) and traditional sulfonated biochar-SO 3 H (28.0%). In the alkylation reaction of 4-ethylphenol with phenylmethanol/2-methylfuran with cyclopentanone for high-density bicyclic/monocyclic biofuel, its catalytic efficiency with target product yields are 69.4% and 70.5% respectively, which are also higher than that of amberlyst-15 (74.3%, 49.4%) and biochar-SO 3 H (14.7%, 13.0%). Furthermore, the catalyst is more stable than biochar-SO 3 H. The preparation of hydrophobic biochar-based sulfonic acid catalysts not only opens a new way for high-value utilization of biochar, but also provides a novel efficient catalyst in many acid-catalyzed transformation reactions that the product H 2 O causes deleterious effects. [ABSTRACT FROM AUTHOR]

Abstract This work investigated the optimization of process parameters in the upgrading of the oil extracted from Scenedesmus obliquus microalgae using a novel nickel-impregnated biochar catalyst. The effects of temperature, dodecane-to-oil mass ratio and pressure on the upgraded liquid-phase biofuel yield were evaluated and optimized by central composite design of the response surface methodology (RSM). The model equation generated from RSM showed that dodecane-to-oil mass ratio and pressure, as well as the quadratic effects of all the three factors, were significant model terms in predicting the yield of upgraded liquid-phase biofuel. Maximum liquid biofuel yield was attained at 246.89 °C, 3.72 (w/w) dodecane-to-oil mass ratio, 3.84 MPa hydrogen pressure and 6 h processing time. Validation runs resulted in an upgraded biofuel yield of 69.4%, which was in close agreement with predicted values generated by RSM. The upgraded biofuel comprised of 100% green liquid hydrocarbons containing 94% alkanes and 6% alkenes. Its main fuel properties, such as heating value (43.78 MJ kg−1), elemental composition, density, and viscosity, exceeded those of the fatty acid methyl ester standard and were found comparable to those of petroleum diesel. More importantly, the results of the ultimate analysis and confirmed by the findings from Fourier transform infrared and gas chromatography – mass spectroscopy analyses, showed significantly low oxygen and nitrogen content and absence of sulfur in the upgraded biofuel. Graphical abstract Image Highlights • Novel catalyst was synthesized from rice hull biochar. • The catalyst was used to upgrade Scenedesmus obliquus oil to high-quality biofuel. • Response surface methodology was used to optimize biofuel yield. • High optimum biofuel yield at 69.4 wt. % was obtained. • The biofuel consisted of 100% green liquid hydrocarbons and HHV of 43.78 MJ kg−1. [ABSTRACT FROM AUTHOR]

Highlights • Uncertainty in market prices drives financial outcomes. • Monte Carlo simulation allows uncertainty to be quantified. • Biochar-only production offers a potentially profitable venture. • Biofuel-biochar coproduction requires RINs to achieve financial success. Abstract A comparative techno-economic analysis of two different thermochemical biomass conversion pathways was conducted to examine the effects of fuel price and other variables on project financial performance. Monte Carlo simulation was used to quantify the effects of uncertainty and volatility of ten critical variables: biofuel, biochar and feedstock prices, discount rate, capital investment, labor cost, loan terms, feedstock drying, and biofuel and biochar conversion rates. Market prices for biofuel and biochar have the largest impact on net present value (NPV) of any variable considered, due in part to the high levels of uncertainty associated with future prices of both. Across the ranges of input values for these variables in simulation analysis, hearth-based pyrolysis biochar production had the highest likelihood of profitability with a mean NPV of $41.5 million and only 20% of outcomes resulting in a net loss, while 68% of outcomes for auger-based biochar-biofuel coproduction represented a financial loss, including a mean NPV of -$24.2 million. However, when additional revenue from Renewable Identification Numbers (RINs) credits generated by biofuel production is considered, financial outcomes of biochar-biofuel coproduction improve to 50% likelihood of experiencing a net loss. Findings of the very strong impact of market prices on financial outcomes, relative to other important technical and economic variables, can inform effective targeting of future renewable energy policy, as well as the design of future techno-economic analyses, which do not currently focus on the effect of market prices on profitability. [ABSTRACT FROM AUTHOR]

• Microalgal tolerate heavy through different heavy metal uptake strategies. • Role of different transporters in the uptake and detoxification of heavy metals. • Microalgae based strategies for bioremediation of specific heavy metals. • Microalgae show elevated biomass and lipid production under metal stress. The proficiency of microalgae to resist heavy metals has potential to be beneficial in resolving various environmental challenges. Global situations such as the need for cost-effective and ecological ways of remediation of contaminated water and for the development of bioenergy sources could employ microalgae. In a medium with the presence of heavy metals, microalgae utilize different mechanisms to uptake the metal and further detoxify it. Biosorption and the next process of bioaccumulation are two such major steps and they also include the assistance of different transporters at different stages of heavy metal tolerance. This capability has also proved to be efficient in eradicating many heavy metals like Chromium, Copper, Lead, Arsenic, Mercury, Nickel and Cadmium from the environment they are present in. This indicates the possibility of the application of microalgae as a biological way of remediating contaminated water. Heavy metal resistance quality also allows various microalgal species to contribute in the generation of biofuels like biodiesel and biohydrogen. Many research works have also explored the capacity of microalgae in nanotechnology for the formation of nanoparticles due to its relevant characteristics. Various studies have also revealed that biochar deduced from microalgae or a combination of biochar and microalgae can have wide applications specially in deprivation of heavy metals from an environment. This review focuses on the strategies adopted by microalgae, various transporters involved in the process of tolerating heavy metals and the applications where microalgae can participate owing to its ability to resist metals. [ABSTRACT FROM AUTHOR]

Biochar derived from orchid tree leaves is utilised as the fuel of a direct carbon solid oxide fuel cell (DC-SOFC), with yttrium stabilized zirconia (YSZ) as electrolyte and cermet of silver and gadolinium doped ceria (Ag-GDC) as the material of both cathode and anode, operating without any liquid medium or feeding gas. The performance of the DC-SOFC operated on the leaf char is higher than that operated on the best reported carbon fuel for DC-SOFCs, Fe-loaded activated carbon. XRD, Raman spectroscopy, SEM and EDX are applied to characterize the leaf char. It turns out that the leaf char is with porous structure and there is much Ca along with some K and Mg uniformly distributing in the leaf char. The effects of the naturally existing alkaline earth metal and alkaline metal and their distribution on the performance of the DC-SOFCs operated on the leaf char are analyzed in detail. [ABSTRACT FROM AUTHOR]

[Display omitted] • Application of Fe-impregnated bentonite as a catalyst in pyrolysis of grass cut. • CO 2 gas was employed as a pyrolysis gas medium. • Fe-impregnated bentonite enhanced syngas production. • Fe-impregnated bentonite induced formation of methyl 1,1-methyl-dodecanoate (C 14 H 28 O 2). • Obtained biochar had good As(V) adsorption capability. Fe-impregnated bentonite was employed in CO 2 -assisted pyrolysis of grass cut as a catalyst to improve syngas production, bio-oil quality, and biochar sorptive property. The gas analysis revealed that H 2 and CO production was enhanced by 332 and 7,110%, respectively, by applying Fe-impregnated bentonite in pyrolysis of grass cut while untreated bentonite had a limited influence on syngas production. Bio-oil produced from Fe-impregnated bentonite and grass cut (Fe-BG) had more homogenized chemical species in bio-oil as compared to that produced from pyrolysis of grass cut, and contained methyl 1,1-methyl-dodecanoate (C 14 H 28 O 2), one of the major components in biodiesel. The produced biochar had high surface area (69.2 m2 g−1) and possessed Fe0 and graphitic carbon structure, which was deemed to arise from reduction of Fe-oxides by syngas. Biochar also showed high As(V) adsorption capacity. The overall results of this work demonstrated the beneficial utility of Fe-impregnated bentonite in pyrolysis of biomass to improve syngas production as well as the quality of pyrogenic products. [ABSTRACT FROM AUTHOR]

Two different pathways for utilizing Miscanthus giganteus biochar were evaluated, namely, for the production of sustainable solid biofuels and as a precursor of high surface area activated carbons. Biochars were produced through a simple thermochemical conversion method via pyrolysis at 400, 500, 600, and 800 °C. The obtained biochars and raw biomass were characterized in detailed by proximate and ultimate analyses. The thermal behaviour and structural and strength properties were evaluated. The chemical composition (cellulose, hemicellulose, and lignin content) of raw Miscanthus giganteus was investigated. The biochars afforded a sufficient higher heating value (HHV) of up to 32 MJ kg−1. Activated carbon was obtained via chemical activation with KOH at 800 °C. The effect of the pyrolysis temperature on the surface properties of the activated carbons was investigated over a wide temperature range. The resulting activated carbons were characterised by N 2 adsorption–desorption at −196 °C and by determining the pH of aqueous extracts. As a potential application, the obtained activated carbon series was used for the adsorptive removal of isoproturon from aqueous media. The adsorption capacity was as high as 384 mg g−1 and depended on the pore size distribution of the activated carbons. The conducted study follows the current trend of search for novel energy sources and water purification. [Display omitted] • Miscanthus giganteus biochar was produced by pyrolysis at 400–800 °C. • Pyrolysis temperature affected properties of biochar and activated carbon. • The higher heating value of biochar pyrolysed at 600 °C was 32.8 MJ kg−1. • Biochar was used as precursor of activated carbon with high specific surface area. • Activated carbon efficiently adsorbed isoproturon from aqueous solution. [ABSTRACT FROM AUTHOR]

Lignocellulosic model compounds and aspen wood are processed at supercritical hydrothermal conditions to study and understand feedstock impact on biocrude formation and characteristics. Glucose and xylose demonstrate similar yield of biocrude and biochar, similar biocrude characteristics, and it is hypothesized that reaction mechanisms for the two model compounds are indistinguishable. Glucose and xylose are main sources of substituted cyclopentenones and substantial contributors to oxygenated aromatics mainly in the range of C 6 –C 9 number of carbon atoms, and potential, sustainable biogasoline candidates. Lignin yields predominantly aromatic biocrudes having similar C 6 –C 9 number of carbon atoms. Model mixtures show good predictability in the distribution of substituted cyclopentenones and oxygenated aromatics, but aspen wood-derived biocrude is more aromatic than predicted by model mixtures. The work extends previous work on the understanding of the chemical mechanisms of lignocellulose liquefaction and the biocrude formation. Potential applications for the biocrudes are identified, where significant sustainability issues for the transport sector can be addressed. [ABSTRACT FROM AUTHOR]

Renewable energy sources such as biomass have been proven to be one of the promising sustainable alternatives to fossil fuels. However, using biomass directly as a fuel is less attractive due to its high moisture content, poor grindability, low bulk density, and low energy density nature. Hence biomass can be converted into biochar to overcome these challenges. In this study, biochar was derived from citrus peels biomass by slow pyrolysis over the temperature range of 300–700 °C. The effect of pyrolysis temperature on the quality of citrus peels-derived biochar was examined based on the physical and chemical properties obtained from various analyses. The citrus peels biomass and biochar were characterized by means of higher heating value (HHV) analysis, field emission scanning electron microscopy with energy dispersive X-ray spectroscopy (FESEM-EDX), Fourier transform infrared ray (FTIR) analysis, proximate and thermogravimetric analysis. Based on the characterization results, the potential usage of the derived biochar as a solid fuel was discussed. Results obtained from the pyrolysis experiments indicated that a lower pyrolysis temperature produced a higher char yield. The carbon content and energy content of biochar were found to be increasing with pyrolysis temperature. Biochar produced at 500 °C presented the best fuel properties by having the highest value of HHV and carbon content. The results from this study provided great insights into biomass waste reutilisation to generate value-added biochar for renewable energy production in Malaysia. [Display omitted] • Promising potential for citrus peels biomass to biochar for energy conversion. • Higher heating value of citrus peels biochar comparable to sub-bituminous coal. • Carbon and energy content increased with increasing pyrolysis temperature. • Better combustion stability for biochar of higher pyrolysis temperature. [ABSTRACT FROM AUTHOR]

The continuous development of the economy and the constant improvement of living standards have stimulated the development of animal husbandry. This development has been accompanied by the massive production of animal manure with various bad odors and high heavy metal content, constituting severe damage to ecological security and human health. Traditional disposal methods, including composting and anaerobic digestion, are difficult to achieve satisfactory results due to long processing time, water and soil eutrophication, and toxic gas emissions. However, converting animal manure into bioenergy through pyrolysis is a clean, safe, and promising technique to reduce the amount of waste and produce valuable products. Co-pyrolysis with other materials can decrease the content of heavy metals in biochar and ameliorate the properties of products. The application of catalysts influences the pyrolysis process and product properties positively. The objective of this review is to analyze the properties of animal manure and discuss the recovery of biofuel from harmful animal manure by pyrolysis. A comprehensive analysis of animal manure pyrolysis and related product characteristics will provide a foundation for the sustainable management and scientific disposal of hazardous manure waste. [Display omitted] • Biochar is the primary product of conventional pyrolysis of animal manure. • High temperature enhances the immobilization of heavy metals in biochar. • Co-pyrolysis promotes the reduction of heavy metal content. • The addition of co-feedstock or catalyst influences product properties greatly. [ABSTRACT FROM AUTHOR]

The Antarctic krill, referring to Euphausia superba , feeds phytoplankton, grown up with photosynthesis for CO 2 fixation. Therefore, the use of krill as a raw feedstock for energy production is a highly carbon negative approach, not disturbing the food supply chain of human. Although the krill has high lipid content (up to 40 wt%, dry basis), its use as a raw feedstock for biodiesel production has not been considered. In this study, the feasibility of Euphausia superba to be used as a biodiesel feedstock was scrutinized. Prior to biodiesel production, an annual biodiesel production potential from the krill without disruption of ecosystems was estimated (129% larger than current biodiesel production in Korea). Because krill oil contains high fraction impurities, (trans)esterification with acid catalyst resulted in low yield of biodiesel (6.5 wt%), while non-catalytic transesterification achieved 94.7 wt% of biodiesel yield. To maximize the utilization of krill, solid residue obtained after biodiesel production was synthesized to krill biochars, and they were used as sorptive materials for adsorption of toxic chemicals. Among different model pollutants (Cd(II), Cr(VI), and methylene blue), krill biochar had the best adsorption capacity for Cd(II) (13.7 mg g−1), which is comparable value with other studies. [Display omitted] Biodiesel production from transesterification of lipid in krill and conversion of krill solid residue into biochar, available for adsorption of environmental pollutants. [ABSTRACT FROM AUTHOR]

Abstract: A partial solution to problems associated with anthropogenic greenhouse gas (GHG) emissions could be the development and deployment of carbon-negative technologies, i.e., producing energy while reducing atmospheric carbon dioxide levels. Biofuels have been considered a possibility but have faced limitations due to competition with food production and GHG emissions through indirect land-use change (ILUC). In this article, we show how emissions from ILUC can potentially be reduced by producing food and bioenergy from biochar amended soils. The possibility of yield improvements from biochar would reduce the land requirement for crop production and thus, lead to a reduction in emissions from ILUC. In our application, biochar and bio-oil are produced via fast pyrolysis of corn stover. Bio-oil is subsequently upgraded into a fuel suitable for use in internal combustion engines. Applying the U.S. regulatory method used to determine biofuel life cycle emissions, our results show that a biochar-induced yield improvement in the U.S. Midwest ranging from 1% to 8% above trend can lead to an ILUC credit between 1.65 and 14.79 t CO2-equivalent ha−1 year−1 when future emissions are assessed over the next 30 years. The model is generalizable to other feedstocks and locations and illustrates the relationship between biochar and crop production. [Copyright &y& Elsevier]

Abstract: Biomass thermochemical decomposition products have been extensively studied as renewable substitutes of fossil fuel. The approach proposed in this work considers vegetal waste as a source of both energy and matter through the production of a vapor phase fuel, highly diluted in steam, suitable to be burned in non-conventional combustion systems and a char with soil amending and fertilizing properties. To demonstrate the feasibility of such a process an experimental set-up has been designed with the aim to investigate the effect of pressure, heating rate and final temperature in proper variation ranges (P =1–5×105 Pa, HR=5–40K/min, T =473–973K) on the yields and on the chemical and physical properties of gaseous and solid products. In this paper the effect of temperature at constant pressure (P =5×105 Pa) and heating rate (HR=5K/min) has been investigated in order to explore all the stages of the thermochemical degradation from torrefaction to mild gasification passing through devolatilization. For real biomasses a basic study on characterization of biomass components is needed. Knowledge of dependences on feedstock nature and process conditions is crucial for the comprehension of phenomena occurring during steam pyrolysis of real complex biomasses and for the optimization of the process operating variables. This study characterizes steam pyrolysis up to 873K (at pressure P =5×105 Pa and heating rate HR=5K/min) both of three single biomasses constituents (cellulose, hemicellulose and lignin) and of three binary mixtures in order to evaluate possible interactions between the biomass components. The results obtained highlight the importance of the interactions between components, mainly cellulose and lignin, on the yield and characteristics of solid and gaseous products. In particular, strong components interactions have been detected on the specific surface area of the solid product. [Copyright &y& Elsevier]