Production of butanol and polyhydroxyalkanoate from industrial waste by Clostridium beijerinckii ASU10

This study demonstrated a biotechnological approach for simultaneous production of low‐cost H₂, liquid biofuels, and polyhydroxyalkanoates (PHAs) by solventogenic bacterium (Clostridium beijerinckii) from renewable industrial wastes such as molasses and crude glycerol. C beijerinckii ASU10 (KF372577) exhibited considerable performance for hydrogen production of 5.1 ± 0.84 and 11 ± 0.44 mL H₂ h^?1 on glycerol and sugarcane molasses, respectively. The total acetone‐butanol‐ethanol (ABE) generation from glycerol and molasses was 9.334 ± 2.98 and 10.831 ± 4.1 g L^?1, respectively. ABE productivity (g L^?1 h^?1) was 0.0486 and 0.0564 with a yield rate (g g^?1) up to 0.508 and 0.493 from glycerol and molasses fermentation, respectively. The PHA yields from glycerol and sugarcane molasses were 84.37% and 37.97% of the dried bacterial biomass, respectively. Additionally, the ultrathin section of C beijerinckii ASU10 showed that PHA granules were accumulated more densely on glycerol than molasses. Gas chromatography–mass spectrometry (GC‐MS) analysis confirmed that the PHAs obtained from molasses fermentation included 3‐hydroxybutyrate (47.3%) and 3‐hydroxyoctanoate (52.7%) as the main constituents. Meanwhile, 3‐hydroxybutyrate represented the sole monomer of PHA produced from glycerol fermentation. This study demonstrated that C beijerinckii ASU10 (KF372577) is a potent strain for low‐cost PHA production depending on its high potential to produce high‐energy biofuel and other valuable compounds from utilization of organic waste materials.     

Ultrasonic and Microwave Desulfurization of Coal in Tetrachloroethylene

Abstract

The extractive desulfurization of four high sulfur coals from China were promoted with ultrasonic and microwave in tetrachloroethylene organic solvents. It was shown that the joint promotion with ultrasonic and microwave had an active effect on extractive desulfurization. The rate of desulfurization increased with the increase of time in ultrasonic field as well as with the power of ultrasonic, but declined with the increase of the particle size of coal. The rate of desulfurization was not identical for different coal, which was perhaps related to the existed forms of organic sulfur in coal.     

Isolation of fermentative microbial isolates from sugar cane and beet molasses and evaluation for enhanced production of bioethanol

In an attempt to produce bioethanol as a renewable and natural energy resource and as a promising alternative/complement to conventional petrol (i.e., gasoline), 44 microbial isolates (12 yeast and 32 bacterial strains) were isolated from molasses samples obtained from some of the sugar factories in Egypt. Among the microbial isolates obtained, only two yeast isolates (HSC-22 and HSC-24) were selected from sugarcane molasses (SCM) for their high bioethanol fermentation capabilities, recording bioethanol production of ≈9.6 and 8.2 g/L with actual yield of 0.48 and 0.41 g ethanol/g SCM, respectively, within 48-h incubation period at 30°C. Phylogenetic identification of these isolates was performed based on the analysis of the nucleotide sequence of the 18S rDNA gene, which indicated that these isolates can be identified as Pichia veronae and Candida tropicalis, respectively, with similarity of 99%.     

Oxidative Desulfurization of Tufanbeyli Coal by Hydrogen Peroxide Solution

Abstract

It is becoming popular to use fossil fuels efficiently since the necessary energy is mostly supplied from fossil fuels. Altough there are high lignite reservoirs, high sulfur content limits the efficient use of them. In this article, we aimed to convert combustible sulfur in coal to non-combustible sulfate form in the ash by oxidizing it with a hydrogen peroxide solution. The parameters affecting the sulfur conversion were determined to be: hydrogen peroxide concentration, reaction time, mean particle size at constant room temperature and shaking rate. The maximum desulfurization efficiency reached was 74% of the original combustible sulfur with 15% (w/w) hydrogen peroxide solution, 12 hours of reaction time, and 0.25 mm mean particle size.     

Oxidative Desulfurization of Aşkale Coal by Nitric Acid Solution

Abstract

Efficient use of fossil fuels is of utmost importance in a world that depends on these for the greatest part of its energy needs. Although lignite is a widely used fossil fuel, its sulfur content limits its consumption. This study aims to capture combustible sulfur in the ash by oxidizing it with solution of nitric acid solution. Thus, the combustible sulfur in the coal was converted to sulfate form in the ash. Parameters affecting the conversion of sulfur were determined to be nitric acid concentration, reaction time and mean particle size at constant (near room) temperature and shaking rate. The maximum desulfurization efficiency reached was 38.7% of the original combustible sulfur with 0.3 M nitric acid solution, 16 h of reaction time and 0.1 mm mean particle size.     

Effect of Prussian Blue on Organic Sulfur of Coal in Aqueous Medium

Abstract

This study is an attempt to desulfurize organic sulfur from coal samples with ferric hexacyanoferrate (II), Fe₄ [Fe(CN)₆], as the desulfurization agent. Effect of temperature, particle size and concentration of ferrocyanide ion on desulfurization from the coal samples has been investigated. The temperature and stirring time are the most important parameters for the level of desulfurization of organic sulfur. Removal of organic sulfur content increased continuously with increasing temperature from 298 to 368 K. The organic sulfur removal rate sharply increases from 10 min to 30 min stirring time. After 30 min, it reaches a value of plateau. Particle size between ?100 mesh and ?200 mesh slightly affects the amount of organic sulfur removal. Gradual increase in the concentration of ferric hexacyanoferrate (II) raised the magnitude of desulfurization, but at higher concentration, the variation is not significant.     

Catalytic Effects of Minerals on NOx Emission from Coal Combustion

Abstract

The catalytic effects of inherent mineral matters on NO _x emissions from coal combustion have been investigated by a thermo-gravimetric analyzer (TGA) equipped with a gas analyzer. The effect of demineralization and the individual effect of Na, K, Ca, Mg, and Fe on the formation of NO _x are studied as well as the combined catalytic effects of Ca + Na and Ca + Ti. Demineralization causes more Fuel-N to retain in the char, and reduction of NO _x mostly. But the mechanistic effect on NO _x formation varies from coal to coal. Ca and Mg promote NO _x emission. Na, K, Fe suppress NO _x formation to different extents. The effect of transition element Fe is the most obvious. The combination of Ca + Na and Ca + Ti can realize the simultaneous control of sulfur dioxide and nitrogen oxides emissions.     

Dark fermentative hydrogen production from sucrose and molasses

There are many factors affecting the dark fermentative hydrogen production. The interaction of these factors, that is, their combined effects, should be investigated for better design of the systems with stable and higher hydrogen yields. This study aimed to investigate the combined effects of initial substrate, pH, and biomass (or initial substrate to biomass) values on hydrogen production from sucrose and sugar‐beet molasses. Therefore, optimum initial chemical oxygen demand (COD), pH, and volatile suspended solids (VSS) or initial substrate to biomass (VSS) ratio (S/X_o) values leading to the highest dark fermentative hydrogen production were investigated in batch reactors. An experimental design approach (response surface methodology) was used. Results revealed that when sucrose was the substrate, maximum hydrogen production yield (HY) of 2.3 mol H₂/mol sucrose_added was obtained at initial pH of 7 and COD of 10 g/L. Initial S/X_o values studied (4–20 g COD/g VSS) had no effect on HY, while the initial pH was found as the parameter mostly affecting both HY and hydrogen production rate (HPR). When substrate was molasses, initial COD concentration was the only variable affecting HY and HPR. Maximum of both was achieved at 10 g/L initial COD. Initial VSS values studied (2.5–7.5 g/L) had no effect on HPR and HY. This study also indicated that molasses leads to homoacetogenesis for potentially containing intrinsic microorganism and/or natural constituents; thus, sucrose is more advantageous for hydrogen production via fermentation. Homoacetogenesis should be prevented for effective optimization via response surface methodology, if substrate is a natural carbon source potential to have intrinsic microorganisms. Copyright © 2017 John Wiley & Sons, Ltd.     

Adsorption of Sulfur Dioxide from Coal Combustion Gases on Natural Zeolite

In this study, better efficiency of SO₂ removal in flue gas from lignite coal combustion by adding of NZ in the gas phase was achieved. Natural zeolite was exposed to flue gas containing sulfur dioxide at varying conditions of relative humidity and temperature. It was found that the amount of sulfate on the zeolite increased with increasing relative humidity and temperature. The percents of adsorbed sulfur dioxide were 86, 74, 56, and 35, while the values of relative humidity (RH) were 75, 60, 45, and 30% for 40 minutes, respectively. The percents of adsorbed sulfur dioxide sharply increased within the first 40 min for the values of RH were 75 and 60, and after 40 min, slightly increased, then reached a plateau. In general, as increasing the RH increased the amount of sulfur dioxide adsorbed by natural zeolite. The amounts of adsorbed sulfur dioxide increased with exposure time. It increased and reached 30.2 mg/g for 40 min. After 40 min, it slightly increased and then reached a plateau. The NZ adsorbs 35.1 mg SO₂ per gram adsorbent with 75% RH at 298 K from a simulated coal combustion flue gas. The amounts of adsorbed sulfur dioxide increased with increasing temperature. The NZ adsorbs 71.5 mg SO₂ per gram adsorbent with 75% RH for 100 min exposure time from the flue gas mixture.     

Further Investigation of the Impact of the Co-combustion of Tire-derived Fuel and Petroleum Coke on the Petrology and Chemistry of Coal Combustion Products

Abstract

A Kentucky cyclone-fired unit burns coal and tire-derived fuel, sometimes in combination with petroleum coke. A parallel pulverized combustion (pc) unit at the same plant burns the same coal, without the added fuels. The petrology, chemistry, and sulfur isotope distribution in the fuel and resulting combustion products was investigated for several configurations of the fuel blend. Zinc and Cd in the combustion products are primarily contributed from the tire-derived fuel, the V and Ni are primarily from the petroleum coke, and the As and Hg are probably largely from the coal. The sulfur isotope distribution in the cyclone unit is complicated due to the varying fuel sources. The electrostatic precipitator (ESP) array in the pc unit shows a subtle trend towards heavier S isotopic ratios in the cooler end of the ESP.     

Origin and Properties of Oltu Gemstone Coal

Abstract

This study focuses on the origin and properties of the Oltu gemstone or Oltustone. The Oltu gemstone known as ‘Black Amber’ is dull-bright black color, and is very low ash, high volatile matter, total sulfur and calorific value. Very high volatile matter content on a dry-ash free basis (66.52%) and non-agglomerating character imply that its coal rank is very low. The Oltu gemstone includes abundant organic (amorphous) matter and trace amounts of quartz and pyrite. Petrographic study indicated that pyrite and quartz generally finely disseminated the organic matter. Major and trace element data have low concentrations. The trace element concentrations fall within the range values for the most world coals, except for Bi that exceeds range values (0.1–0.5 μg/g) in most world coals. Petrographic observations on the polished briquette have shown that the gemstone was made of xylite including mainly textinite and corpohuminite, minor amounts of resinite and liptodetrinite. Mean values of random reflectance (%Rr) measurements on the textinite and corpohuminite are 0.23 and 0.30%Rr, respectively. These values indicate very low coal rank, in agreement with the volatile matter.     

Combustion behavior of low-rank coal impregnated with glycerol

The addition of biomass to an existing coal-fired boiler has emerged as a prospective option for reducing CO₂ emissions to mitigate the problems associated with excess global warming. However, the cost associated with retrofitting an injection system and the unstable combustion hinder the use of this option. Therefore, we propose the use of coal impregnated with glycerol as fuel that can be directly injected into an existing boiler. This is a two-in-one fuel that combines a low-rank coal (LRC) with bio-liquid matter extracted from biomass such as molasses or sugarcane juice. In this study, for the first time, we used glycerol, which is a low value co-product of biodiesel production, as the bio-liquid, because the use of molasses or sugar-cane juice raises food ethical issues. The aim of this study was to investigate the combustion behavior of coal impregnated with glycerol, using experimental and numerical methods. The results showed that the calorific value of coal impregnated with glycerol increased, and the combustibility at low and high temperatures was improved by impregnation of low-rank coal with up to 20% glycerol. We also confirmed that the combustion performance of coal impregnated with glycerol was unaffected and was identical to that of original coal. However, excess glycerol (more than 20%) led to oxygen deficiency near the burner and thermal expansion, which reduced the combustibility. The results of this study therefore suggest that less than 20% glycerol is the optimal condition for low-rank coal impregnated with glycerol.     

New experimental technique to determine coal self-ignition duration

An artificial neural network (ANN) model was adopted to simulate the relationship between self-ignition duration and sulfur content, ash content, oxygen consumption rate, carbon monoxide as well as carbon dioxide generation rate of coal at different temperatures of self heating process. The data from spontaneous combustion experiments were used for ANN training to obtain the connection strength between nerve cells. An oil-bath programmed temperature experiment device was designed and the experimental condition and the size of the test tube were determined for testing the oxygen consumption and the gases generation rate of coal during self-heating process. The sulfur content, the ash content and the data from the oil-bath experiment were taken as ANN inputs to calculate the experiment self-ignition duration of coal. Compared with spontaneous combustion experiment, less than 1% of coal sample and 10% of time are required with an error of less than 3 days to test self-ignition duration of coal. __________ Translated from Journal of Xi’an Jiao Tong University, 2006, 40(9): 1058–1061 [译自: 西安交通大学学报]     

Suitability of pineapple,Aloe vera,molasses, glycerol,and office paper as substrates in the MixAlco process?

The MixAlco? process biologically converts biomass to carboxylate salts that may be chemically converted to a wide variety of chemicals and fuels. This study looked at the viability of the following substrates: office paper, pineapple residue, Aloe vera rinds, wood molasses, sugar molasses, and glycerol. All agricultural substrates were initially tested to determine their carbohydrate and lignin content because lignin reduces substrate digestibility. Only pineapple residue had a high enough lignin content (18.3%) to necessitate pretreatment. Pineapple residue was treated with excess lime (300 g kg^?1 Ca(OH)₂ on dry biomass, t = 1 h) and then neutralized with CO₂, which reduced the lignin content to 4.89%. All substrates were anaerobically fermented in batch culture with marine microorganisms for 24 days. The acid concentrations (g mixed acid L^?1) were Aloe vera (25.5), office paper (24.0), glycerol (22.6), pineapple residue (17.2), wood molasses (19.4) and sugar molasses (18.9). The conversions (g volatile solids digested g^?1 volatile solids fed) were Aloe vera (0.59), office paper (0.50), glycerol (0.62), pineapple residue (0.52), wood molasses (0.42) and sugar molasses (0.82). The selectivities (g acetic acid equivalents g^?1 VS digested) were Aloe vera (0.64), office paper (0.62), glycerol (0.51), pineapple residue (0.39), wood molasses (0.61) and sugar molasses (0.33).     

Valorization of sugar beet molasses for the production of biohydrogen and 5-aminolevulinic acid by Rhodobacter sphaeroides O.U.001 in a biorefinery concept

The production of biohydrogen and 5-aminolevulinic acid (5-ALA) from sugar beet molasses was investigated within a biorefinery framework. A purple non-sulfur photosynthetic bacterium, Rhodobacter sphaeroides O.U.001, was used for this purpose. The suitability of the molasses for biohydrogen and 5-ALA production was assessed in certain aspects and then five different culture media with various sugar contents (3 g/L, 7 g/L, 14 g/L, 21 g/L and 28 g/L) were prepared. Results have shown that molasses is a promising substrate for the production of biohydrogen and 5-ALA in a biorefinery concept and increasing sugar content results in enhanced product accumulation. Specifically, the highest amount of biohydrogen and 5-ALA was observed in 28 g/L sugar-containing medium (1.01 L H₂/L culture, 23,337 μM). In conclusion, this paper presents the new findings about the enhanced accumulation of biohydrogen and 5-ALA within a biorefinery context.     

Biohydrogen production from pentose-rich oil palm empty fruit bunch molasses: A first trial

Oil palm empty fruit bunch (OPEFB) was pretreated by local plantation industry to increase the accessibility towards its fermentable sugars. This pretreatment process led to the formation of a dark sugar-rich molasses byproduct. The total carbohydrate content of the molasses was 9.7 g/L with 4.3 g/L xylose (C₅H₁₀O₅). This pentose-rich molasses was fed as substrate for biohydrogen production using locally isolated Clostridium butyricum KBH1. The effect of initial pH and substrate concentration on the yield and productivity of hydrogen production were investigated in this study. The best result for the fermentation performed in 70 mL working volume was obtained at the initial reaction condition of pH 9, 150 rpm, 37 °C and 5.9 g/L total carbohydrate. The maximum hydrogen yield was 1.24 mol H₂/mol pentose and the highest productivity rate achieved was 0.91 mmol H₂/L/h. The optimal pH at pH 9 was slightly unusual due to the presence of inhibitors, mainly furfural. The furfural content decreased proportionally as pH was increased. The optimal experiment condition was repeated and continued in fermentation volume of 200 mL. The maximum hydrogen yield found for this run was 1.21 mol H₂/mol pentose while the maximum productivity was 1.1 mmol H₂/L/h. The major soluble metabolites in the fermentation were n-butyric acid and acetic acid.     

Effects of temperature and limestone on sulfur release behaviors during fluidized bed gasification

Gaseous sulfur is released during fluidized bed coal gasification, and control the yield of gaseous sulfur or the conversion between gaseous organic sulfur and inorganic sulfur at source is necessary, because it can economically satisfy the requirements of industrial production and protect the environments. In this study, sulfur release behaviors of a middle-sulfur coal called Guizhou coal were quantitatively determined through controlled experiments in a lab-scale fluidized bed during oxygen rich-steam gasification. The measured gaseous sulfur species were H₂S, SO₂, COS and CS₂. The effects of temperature (850^OC-950^OC) and limestone (Ca/S = 2) on the sulfur release behaviors were investigated. Among the above four gaseous sulfur, the yield of H₂S is the highest, followed by COS, while only less than 1.5% of sulfur in coal is released as SO₂ and CS₂. With the increase in temperature, the yield of H₂S increases while that of SO₂ decreases, and the change of COS yield and CS₂ yield is not obvious. The molar ratio of H₂S/COS increases with increasing temperature, which is qualitatively matched by thermodynamic analysis. The addition of limestone reduces the released sulfur but not change the distribution of gaseous sulfur forms. Meanwhile, the molar ratio of H₂S/COS increases after adding limestone, while the trend with temperature of H₂S/COS does not change. The removal rate of H₂S is between 23% and 28%, which increases with temperature. The distributions of sulfur in bottom char and fly ash are similar. The main sulfur species in the bottom char is organic sulfur, and thiophene dominates the organic sulfur. The increase of temperature and the addition of limestone will both promote the increase of inorganic sulfur content, and the decrease of organic sulfur content.     

The characterization of coal quality from the Jining coalfield

The Jining coalfield in the west Shandong Province contains coal of Permian and Carboniferous age. The 3₁ and 3₂ seams of the Permian Shanxi Formation and seams 6, 10, 15, 16 and 17 of the Carboniferous Taiyuan Formation were analyzed for coal petrogrophy, mineralogy and geochemical parameters. The coal rank parameters indicate that the coal grade is a high volatile bituminous rank. The coal of the Taiyuan Formation is characterized by high vitrinite, low to medium inertinite and liptinite contents, lower ash yield and higher sulfur content than the Shanxi Formation. These properties may be related to the coal forming environment from more reducing conditions in a marine influenced lower delta plain environment for the early Taiyuan coals to more oxidizing paleoenvironmental conditions in an upper delta plain for the upper Shanxi coal seams. The major mineral phases present in the coal are quartz, kaolinite, pyrite and calcite. Sulfur is one of hazardous elements in coal. The major form of sulfur in coal is pyritic sulfur. The sulfur content of the Taiyuan coal seams is considerably higher than that of the Shanxi coals. The sulfur content is positively correlated with pyritic sulfur.     

Retention of SO2 Emission of Coal Combustion by Using Lime in Briquetting

In this study, the effect of lime on control of SO₂ emissions was investigated by briquetting of coal particles with various lime contents. The influence of the added lime was determined not only from the view of its contribution to environmental aspects but also in terms of effects on the thermal features and reaction kinetics of coal. The extent of improvement was determined by detailed sulfur analysis. Thermal qualification and reaction kinetics of the coal briquettes with varying lime contents were performed by evolved gas analysis and its complementing kinetic model based on Arrhenius principles. At the end of experiments, utilization of lime was seen to contribute considerably to desulfurization process. However, lime addition had an adverse effect both on the effectiveness of combustion and the liability of the coal briquettes to oxidize.     

Study on utilizing zinc and lead-bearing metallurgical dust as sulfur absorbent during briquette combustion

Zinc and lead-bearing metallurgical dust (ZLMD) exhibit strong desulfuration ability due to their higher content of metal oxides, such as Fe₂O₃, ZnO, PbO and CaO. In present work, their performances as a sulfur absorbent used in the combustion process of briquette, which is made up of coal and ZLMD, are investigated. Experimental results show that a large part of H₂S and a small part of COS, CS₂ are volatilized from briquette and react with ZnO and PbO to form ZnS and PbS at the earlier stage of combustion, and that O₂ oxidizes FeS₂ to form SO₂ at the later stage. The adsorption reaction of sulfur depends on the content of CaO. ZnO, ZnS and CaSO₄ are stable during the combustion process at temperatures lower than 1100 °C. When the weight percent of ZLMD in the briquette is kept at around 2.5%, and sulfur in coal at around 2.1%, the absorption efficiency of sulfur can reach 90%. These results suggest that utilizing ZLMD as a sulfur absorbent in the combustion process of briquette is a cheap and highly efficient method to treat both ZLMD and toxic emission such as H₂S/SO₂ released during briquette combustion processes.