Search results for: pretreatment

Authors: M. Ungurean, F. Fitigau, C. Paul, A. Ursoiu, F. Peter

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Pretreatment of lignocellulosic biomass materials from poplar, acacia, oak, and fir with different ionic liquids (ILs) containing 1-alkyl-3-methyl-imidazolium cations and various anions has been carried out. The dissolved cellulose from biomass was precipitated by adding anti-solvents into the solution and vigorous stirring. Commercial cellulases Celluclast 1.5L and Accelerase 1000 have been used for hydrolysis of untreated and pretreated lignocellulosic biomass. Among the tested ILs, [Emim]COOCH3 showed the best efficiency, resulting in highest amount of liberated reducing sugars. Pretreatment of lignocellulosic biomass using glycerol-ionic liquids combined pretreatment and dilute acid-ionic liquids combined pretreatment were evaluated and compared with glycerol pretreatment, ionic liquids pretreatment and dilute acid pretreatment.

Keywords: Cellulase, enzymatic hydrolysis, lignocellulosicbiomass, pretreatment.

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Authors: Sirikarn Satimanont, Apanee Luengnaruemitchai, Sujitra Wongkasemjit

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Lignocellulosic materials are new targeted source to produce second generation biofuels like biobutanol. However, this process is significantly resisted by the native structure of biomass. Therefore, pretreatment process is always essential to remove hemicelluloses and lignin prior to the enzymatic hydrolysis. The goals of pretreatment are removing hemicelluloses and lignin, increasing biomass porosity, and increasing the enzyme accessibility. The main goal of this research is to study the important variables such as pretreatment temperature and time, which can give the highest total sugar yield in pretreatment step by using dilute phosphoric acid. After pretreatment, the highest total sugar yield of 13.61 g/L was obtained under an optimal condition at 140°C for 10 min of pretreatment time by using 1.75% (w/w) H3PO4 and at 15:1 liquid to solid ratio. The total sugar yield of two-stage process (pretreatment+enzymatic hydrolysis) of 27.38 g/L was obtained.

Keywords: Butanol production, Corn cobs, Phosphoric acid, Pretreatment

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Authors: Jirakarn Nantapipat, Apanee Luengnaruemitchai, Sujitra Wongkasemjit

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Biofuels, like biobutanol, have been recognized for being renewable and sustainable fuels which can be produced from lignocellulosic biomass. To convert lignocellulosic biomass to biofuel, pretreatment process is an important step to remove hemicelluloses and lignin to improve enzymatic hydrolysis. Dilute acid pretreatment has been successful developed for pretreatment of corncobs and the optimum conditions of dilute sulfuric and phosphoric acid pretreatment were obtained at 120 °C for 5 min with 15:1 liquid to solid ratio and 140 °C for 10 min with 10:1 liquid to solid ratio, respectively. The result shows that both of acid pretreatments gave the content of total sugar approximately 34–35 g/l. In case of inhibitor content (furfural), phosphoric acid pretreatment gives higher than sulfuric acid pretreatment. Characterizations of corncobs after pretreatment indicate that both of acid pretreatments can improve enzymatic accessibility and the better results present in corncobs pretreated with sulfuric acid in term of surface area, crystallinity, and composition analysis.

Keywords: Corncobs, Pretreatment, Sulfuric acid, Phosphoric acid.

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Authors: Bakare Babatunde Femi

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Municipal solid waste (MSW) comprises of a wide range of heterogeneous materials generated by individual, household or organization and may include food waste, garden wastes, papers, textiles, rubbers, plastics, glass, ceramics, metals, wood wastes, construction wastes but it is not limited to the above mentioned fractions. The most common Municipal Solid Waste pretreatment method in use is thermal pretreatment (incineration) and Mechanical Biological pretreatment. This paper presents an overview of these two pretreatment methods describing their benefits and laboratory scale reactors that simulate landfill conditions were constructed in order to compare emissions in terms of biogas production and leachate contamination between untreated Municipal Solid Waste and Mechanical Biological Pretreated waste. The findings of this study showed that Mechanical Biological pretreatment of waste reduces the emission level of waste and the benefit over the landfilling of untreated waste is significant.

Keywords: emissions, mechanical biological pretreatment, MSW, thermal pretreatment

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Authors: Jidapa Manaso, Apanee Luengnaruemitchai, Sujitra Wongkasemjit

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Pretreatment is an essential step in the conversion of lignocellulosic biomass to fermentable sugar that used for biobutanol production. Among pretreatment processes, microwave is considered to improve pretreatment efficiency due to its high heating efficiency, easy operation, and easily to combine with chemical reaction. The main objectives of this work are to investigate the feasibility of microwave pretreatment to enhance enzymatic hydrolysis of corncobs and to determine the optimal conditions using response surface methodology. Corncobs were pretreated via two-stage pretreatment in dilute sodium hydroxide (2 %) followed by dilute sulfuric acid 1 %. Pretreated corncobs were subjected to enzymatic hydrolysis to produce reducing sugar. Statistical experimental design was used to optimize pretreatment parameters including temperature, residence time and solid-to-liquid ratio to achieve the highest amount of glucose. The results revealed that solid-to-liquid ratio and temperature had a significant effect on the amount of glucose.

Keywords: Corncobs, Microwave radiation, Pretreatment, Response Surface Methodology.

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Authors: Rotchanaphan Hengaroonprasan, Malinee Sriariyanun, Prapakorn Tantayotai, Supacharee Roddecha, Kraipat Cheenkachorn

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Lignocellolusic material is a substance that is resistant to be degraded by microorganisms or hydrolysis enzymes. To be used as materials for biofuel production, it needs pretreatment process to improve efficiency of hydrolysis. In this work, chemical pretreatments on rice straw using three diluted organic acids, including acetic acid, citric acid, oxalic acid, were optimized. Using Response Surface Methodology (RSM), the effect of three pretreatment parameters, acid concentration, treatment time, and reaction temperature, on pretreatment efficiency were statistically evaluated. The results indicated that dilute oxalic acid pretreatment led to the highest enhancement of enzymatic saccharification by commercial cellulase and yielded sugar up to 10.67 mg/ml when using 5.04% oxalic acid at 137.11 oC for 30.01 min. Compared to other acid pretreatment by acetic acid, citric acid, and hydrochloric acid, the maximum sugar yields are 7.07, 6.30, and 8.53 mg/ml, respectively. Here, it was demonstrated that organic acids can be used for pretreatment of lignocellulosic materials to enhance of hydrolysis process, which could be integrated to other applications for various biorefinery processes. 

Keywords: Lignocellolusic biomass, pretreatment, organic acid response surface methodology, biorefinery.

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Authors: Jhalique Jane R. Fojas, Ernesto J. Del Rosario

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The dilute acid pretreatment and enzymatic saccharification of lignocellulosic substrate, cogon grass (Imperata cylindrical, L.) was optimized prior ethanol fermentation using simultaneous saccharification and fermentation (SSF) method. The optimum pretreatment conditions, temperature, sulfuric acid concentration, and reaction time were evaluated by determining the maximum sugar yield at constant enzyme loading. Cogon grass, at 10% w/v substrate loading, has optimum pretreatment conditions of 126°C, 0.6% v/v H2SO4, and 20min reaction time. These pretreatment conditions were used to optimize enzymatic saccharification using different enzyme combinations. The maximum saccharification yield of 36.68mg/mL (71.29% reducing sugar) was obtained using 25FPU/g-cellulose cellulase complex combined with 1.1% w/w of cellobiase, ß-glucosidase, and 0.225% w/w of hemicellulase complex, after 96 hours of saccharification. Using the optimum pretreatment and saccharification conditions, SSF of treated substrates was done at 37°C for 120 hours using industrial yeast strain HBY3, Saccharomyces cerevisiae. The ethanol yield for cogon grass at 4% w/w loading was 9.11g/L with 5.74mg/mL total residual sugar.

Keywords: Acid pretreatment, bioethanol, biomass, cogon grass, fermentation, lignocellylose, SSF.

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Authors: U. A. Asli, H. Hamid, Z.A. Zakaria, A. N. Sadikin, R. Rasit

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This study investigated the effect of a dilute acid, lime and ammonia aqueous pretreatment on the fermentable sugars conversion from empty fruit bunch (EFB) biomass. The dilute acid treatment was carried out in an autoclave, at 121ºC with 4% of sulfuric acid. In the lime pretreatment, 3 wt % of calcium hydroxide was used, whereas the third method was done by soaking EFB with 28% ammonia solution. The EFB biomass was then subjected to a two-stage-acid hydrolysis process. Subsequently, the hydrolysate was fermented by using instant baker’s yeast to produce bioethanol. The highest glucose yield was 890 mg/g of biomass, obtained from the sample which underwent lime pretreatment. The highest bioethanol yield of 6.1mg/g of glucose was achieved from acid pretreatment. This showed that the acid pretreatment gave the most fermentable sugars compared to the other two pretreatments.

Keywords: Bioethanol, biomass, empty fruit bunch (EFB), fermentable sugars.

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Authors: Boonyisa Wanitwattanarumlug, Apanee Luengnaruemitchai, Sujitra Wongkasemjit

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The complexity of lignocellulosic biomass requires a pretreatment step to improve the yield of fermentable sugars. The efficient pretreatment of corn cobs using microwave and potassium hydroxide and enzymatic hydrolysis was investigated. The objective of this work was to characterize the optimal condition of pretreatment of corn cobs using microwave and potassium hydroxide enhance enzymatic hydrolysis. Corn cobs were submerged in different potassium hydroxide concentration at varies temperature and resident time. The pretreated corn cobs were hydrolyzed to produce the reducing sugar for analysis. The morphology and microstructure of samples were investigated by Thermal gravimetric analysis (TGA, scanning electron microscope (SEM), X-ray diffraction (XRD). The results showed that lignin and hemicellulose were removed by microwave/potassium hydroxide pretreatment. The crystallinity of the pretreated corn cobs was higher than the untreated. This method was compared with autoclave and conventional heating method. The results indicated that microwave-alkali treatment was an efficient way to improve the enzymatic hydrolysis rate by increasing its accessibility hydrolysis enzymes.

Keywords: Corn cobs, Enzymatic hydrolysis, Microwave, Potassium hydroxide, Pretreatment.

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Authors: Ria Millati, Fiametta A. Purwandari, Adhitya P. Sanjaya, Muhammad N. Cahyanto, I. Sarvari Horvath, Claes Niklasson, Mohammad J. Taherzadeh

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Pretreatment of oil palm empty fruit bunch (OPEFB) with N-Methylmorpholine-N-oxide (NMMO) to enhance biogas production was investigated. The pretreatments were performed at 90 and 120ºC for 1, 3, and 5 h using three different concentrations of NMMO of 73%, 79%, and 85%. The pretreated OPEFB was subsequently anaerobically digested to produce biogas. After pretreatment, there were no significant changes of the main composition of OPEFB and the maximum total solid recovery was 92%. The amorphous phase was increased up to 78% at pretreatment condition using 85% NMMO solution for 3 h at 120oC. In general, higher concentration of NMMO and higher temperature resulted in increased amorphous form and higher biogas production. The best results of biogas production reached enhancement of methane yield of 148% compared to the untreated OPEFB and increased in digestion of 94% compared to starch as reference.

Keywords: Oil palm empty fruit bunch, pretreatment, NMMO, biogas.

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Authors: H. Junoh, K. Palanisamy, C. H. Yip, F. L. Pua

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This study investigates the influence of low temperature thermo-chemical pretreatment of organic food waste on performance of COD solubilisation. Both temperature and alkaline agent were reported to have effect on solubilizing any possible biomass including organic food waste. The three independent variables considered in this pretreatment were temperature (50-90oC), pretreatment time (30-120 minutes) and alkaline concentration, sodium hydroxide, NaOH (0.7-15 g/L). The maximal condition obtained were 90oC, 15 g/L NaOH for 2 hours. Solubilisation has potential in enhancing methane production by providing high amount of soluble components at early stage during anaerobic digestion.

Keywords: Food waste, pretreatments, respond surface methodology, ANOVA, anaerobic digestion.

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Authors: Kessara Seneesrisakul, Erdogan Gulari, Sumaeth Chavadej

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The complex structure of lignocellulose leads to great difficulties in converting it to fermentable sugars for the ethanol production. The major hydrolysis impediments are the crystallinity of cellulose and the lignin content. To improve the efficiency of enzymatic hydrolysis, microbial pretreatment of corncob was investigated using two bacterial strains of Bacillus subtilis A 002 and Cellulomonas sp. TISTR 784 (expected to break open the crystalline part of cellulose) and lignin-degrading fungus, Phanerochaete sordida SK7 (expected to remove lignin from lignocellulose). The microbial pretreatment was carried out with each strain under its optimum conditions. The pretreated corncob samples were further hydrolyzed to produce reducing glucose with low amounts of commercial cellulase (25 U·g-1 corncob) from Aspergillus niger. The corncob samples were determined for composition change by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscope (SEM). According to the results, the microbial pretreatment with fungus, P. sordida SK7 was the most effective for enhancing enzymatic hydrolysis, approximately, 40% improvement.

Keywords: Corncob, Enzymatic hydrolysis, Microorganisms, Pretreatment.

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Authors: Achiraya Jiraprasertwong, Erdogan Gulari, Sumaeth Chavadej

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Among agricultural residues, sugarcane bagasse is one of the most convincing raw materials for the production of bioethanol due to its availability, and low cost through enzymatic hydrolysis and yeast fermentation. A pretreatment step is needed to enhance the enzymatic step. In this study, sugarcane bagasse (SCB), one of the most abundant agricultural residues in Thailand, was pretreated biologically with various microorganisms of white-rot fungus—Phanerochaete sordid (SK 7), Cellulomonas sp. (TISTR 784), and strain A 002 (Bacillus subtilis isolated from Thai higher termites). All samples with various microbial pretreatments were further hydrolyzed enzymatically by a commercial enzyme obtained from Aspergillus niger. The results showed that the pretreatment with the white-rot fungus gave the highest glucose concentration around two-fold higher when compared with the others.

Keywords: Sugarcane bagasse, Microorganisms, Pretreatment, Enzymatic hydrolysis.

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Authors: Kenza Aida Amara, Bachir Djebbar

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We treat the two-dimensional bin packing problem which involves packing a given set of rectangles into a minimum number of larger identical rectangles called bins. This combinatorial problem is NP-hard. We propose a pretreatment for the oriented version of the problem that allows the valorization of the lost areas in the bins and the reduction of the size problem. A heuristic method based on the strategy first-fit adapted to this problem is presented. We present an approach of resolution by bee colony optimization. Computational results express a comparison of the number of bins used with and without pretreatment.

Keywords: Bee colony optimization, bin packing, heuristic algorithm, pretreatment.

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Authors: S. Azadmard-Damirchi, K. Alirezalu, B. Fathi Achachlouei

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Microwave energy is a superior alternative to several other thermal treatments. Extraction techniques are widely employed for the isolation of bioactive compounds and vegetable oils from oil seeds. Among the different and new available techniques, microwave pretreatment of seeds is a simple and desirable method for production of high quality vegetable oils. Microwave pretreatment for oil extraction has many advantages as follow: improving oil extraction yield and quality, direct extraction capability, lower energy consumption, faster processing time and reduced solvent levels compared with conventional methods. It allows also for better retention and availability of desirable nutraceuticals, such as phytosterols and tocopherols, canolol and phenolic compounds in the extracted oil such as rapeseed oil. This can be a new step to produce nutritional vegetable oils with improved shelf life because of high antioxidant content.

Keywords: Microwave pretreatment, vegetable oil extraction, nutraceuticals, oil quality

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Authors: K. Aranyarat, S. Maksasithorn, K. Suriye, S. Kunjara Na Ayudhya, J. Panpranot

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The effect of N2 pretreatment on the catalytic activity of tungsten-based catalysts was investigated in the metathesis of ethylene and trans-2-butene at 450oC and atmospheric pressure. The presence of tungsten active species was confirmed by UV-Vis and Raman spectroscopy. Compared to the WO3-based catalysts treated in air, higher amount of WO4 2-tetrahedral species and lower amount of WO3 crystalline species were observed on the N2-treated ones. These contribute to the higher conversion of 2-butene and propylene selectivity during 10 h time-on-stream. Moreover, N2 treatment led to lower amount of coke formation as revealed by TPO of the spent catalysts.

Keywords: Metathesis, Pretreatment, Propylene, Tungsten.

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Authors: D.N Awang Sh'ri, E. Hamzah

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The deposition of diamond films on a Si3N4 substrate is an attractive technique for industrial applications because of the excellent properties of diamond. Pretreatment of substrate is very important prior to diamond deposition to promote nucleation and adhesion between coating and substrate. Deposition of nanocrystalline diamonds films on silicon nitride substrate have been carried out by HF-CVD technique using mixture of methane and hydrogen gases. Different pretreatment of substrate including chemical etching consists of hot acid etching and basic etching and mechanical etching were used to study the quality of diamond formed on the substrate. The structure and morphology of diamond coating have been studied using X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM) while diamond film quality has been characterized using Raman spectroscopy. AFM was used to investigate the effect of chemical etching and mechanical pretreatment on the surface roughness of the substrates and the resultant morphology of nanocrystalline diamond. It was found that diamond film deposited on as-received, basic etched and grinded substrate shows the morphology of cauliflower while blasted and acidic etched substrates produce smooth, continuous diamond film. However, the Raman investigation did not show any deviation in quality of diamond film for any pretreatment.

Keywords: Nanocrystalline diamond, Chemical VaporDeposition, Pretreatment, Silicon Nitride

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Authors: Candido. R.G., Godoy, G.G., Gonçalves, A.R

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To produce sugar and ethanol, sugarcane processing generates several agricultural residues, being straw and bagasse is considered as the main among them. And what to do with this residues has been subject of many studies and experiences in an industry that, in recent years, highlighted by the ability to transform waste into valuable products such as electric power. Cellulose is the main component of these materials. It is the most common organic polymer and represents about 1.5 x 1012 tons of total production of biomass per year and is considered an almost inexhaustible source of raw material. Pretreatment with mineral acids is one of the most widely used as stage of cellulose extraction from lignocellulosic materials for solubilizing most of the hemicellulose content. This study had as goal to find the best reaction time of sugarcane bagasse pretreatment with sulfuric acid in order to minimize the losses of cellulose concomitantly with the highest possible removal of hemicellulose and lignin. It was found that the best time for this reaction was 40 minutes, in which it was reached a loss of hemicelluloses around 70% and lignin and cellulose, around 15%. Over this time, it was verified that the cellulose loss increased and there was no loss of lignin and hemicellulose.

Keywords: cellulose, acid pretreatment, hemicellulose removal, sugarcane bagasse

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Authors: S. Gaewchingduang, P. Pengthemkeerati

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Cassava bagasse is one of major biomass wastes in Thailand from starch processing industry, which contains high starch content of about 60%. The object of this study was to investigate the optimal condition for hydrothermally pretreating cassava baggasses with or without acid addition. The pretreated samples were measured reducing sugar yield directly or after enzymatic hydrolysis (alpha-amylase). In enzymatic hydrolysis, the highest reducing sugar content was obtained under hydrothermal conditions for at 125oC for 30 min. The result shows that pretreating cassava baggasses increased the efficiency of enzymatic hydrolysis. For acid hydrolysis, pretreating cassava baggasses with sulfuric acid at 120oC for 60 min gave a maximum reducing sugar yield. In this study, sulfuric acid had a greater capacity for hydrolyzing cassava baggasses than phosphoric acid. In comparison, dilute acid hydrolysis to provide a higher yield of reducing sugar than the enzymatic hydrolysis combined hydrothermal pretreatment. However, enzymatic hydrolysis in a combination with hydrothermal pretreatment was an alternative to enhance efficiency reducing sugar production from cassava bagasse.

Keywords: Acid hydrolysis, cassava bagasse, enzymatic hydrolysis, hydrothermal pretreatment.

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Authors: K. Paradkar, S. N. Mudliar, A. Sharma, A. B. Pandit, R. A. Pandey

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The study explores the hybrid combination of Hydrodynamic Cavitation (HC) and Subcritical Wet Air Oxidation-based pretreatment of complex industrial effluent to enhance the biodegradability selectively (without major COD destruction) to facilitate subsequent enhanced downstream processing via anaerobic or aerobic biological treatment. Advanced oxidation based techniques can be less efficient as standalone options and a hybrid approach by combining Hydrodynamic Cavitation (HC), and Wet Air Oxidation (WAO) can lead to a synergistic effect since both the options are based on common free radical mechanism. The HC can be used for initial turbulence and generation of hotspots which can begin the free radical attack and this agitating mixture then can be subjected to less intense WAO since initial heat (to raise the activation energy) can be taken care by HC alone. Lab-scale venturi-based hydrodynamic cavitation and wet air oxidation reactor with biomethanated distillery wastewater (BMDWW) as a model effluent was examined for establishing the proof-of-concept. The results indicated that for a desirable biodegradability index (BOD: COD - BI) enhancement (up to 0.4), the Cavitation (standalone) pretreatment condition was: 5 bar and 88 min reaction time with a COD reduction of 36 % and BI enhancement of up to 0.27 (initial BI - 0.17). The optimum WAO condition (standalone) was: 150oC, 6 bar and 30 minutes with 31% COD reduction and 0.33 BI. The hybrid pretreatment (combined Cavitation + WAO) worked out to be 23.18 min HC (at 5 bar) followed by 30 min WAO at 150oC, 6 bar, at which around 50% COD was retained yielding a BI of 0.55. FTIR & NMR analysis of pretreated effluent indicated dissociation and/or reorientation of complex organic compounds in untreated effluent to simpler organic compounds post-pretreatment.

Keywords: BI, hybrid, hydrodynamic cavitation, wet air oxidation.

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Authors: Ruta Galoburda, Zanda Kruma, Karina Ruse

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Dill contains range of phytochemicals, such as vitamin C and polyphenols, which significantly contribute to their total antioxidant activity. The aim of the current research was to determine the best blanching method for processing of dill prior to microwave vacuum drying based on the content of phenolic compounds, vitamin C and free radical scavenging activity. Two blanching mediums were used – water and steam, and for part of the samples microwave pretreatment was additionally used. Evaluation of vitamin C, phenolic contents and scavenging of DPPH˙ radical in dried dill was performed. Blanching had an effect on all tested parameters and the blanching conditions are very important. After evaluation of the results, as the best method for dill pretreatment was established blanching at 90 °C for 30 seconds.

Keywords: blanching, microwave vacuum drying, TPC, vitamin C.

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Authors: M. N. Eshtiaghi, N. Yoswathana

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The aim of this study was to extract sugar from sugarcane using high electric field pulse (HELP) as a non-thermal cell permeabilization method. The result of this study showed that it is possible to permeablize sugar cane cells using HELP at very short times (less than 10 sec.) and at room temperature. Increasing the field strength (from 0.5kV/cm to 2kV/cm) and pulse number (1 to 12) led to increasing the permeabilization of sugar cane cells. The energy consumption during HELP treatment of sugar cane (2.4 kJ/kg) was about 100 times less compared to thermal cell disintegration at 85 <=C (about 271.7 kJ/kg). In addition, it was possible to extract sugar cane at a moderate temperature (45 <=C) using HELP pretreatment. With combination of HELP pretreatment followed by thermal extraction at 75 <=C, extraction resulted in up to 3% more sugar (on the basis of total extractable sugar) compared to samples without HELP pretreatment.

Keywords: Cell permeabilization, High electric field pulses, Non-thermal processing, Sugar cane extraction.

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Authors: Mário Silva, Filipa Gomes, Filipa Oliveira, Simone Morais, Cristina Delerue-Matos

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Brown seaweeds are abundant in Portuguese coastline and represent an almost unexploited marine economic resource. One of the most common species, easily available for harvesting in the northwest coast, is Saccorhiza polyschides grows in the lowest shore and costal rocky reefs. It is almost exclusively used by local farmers as natural fertilizer, but contains a substantial amount of valuable compounds, particularly alginates, natural biopolymers of high interest for many industrial applications. Alginates are natural polysaccharides present in cell walls of brown seaweed, highly biocompatible, with particular properties that make them of high interest for the food, biotechnology, cosmetics and pharmaceutical industries. Conventional extraction processes are based on thermal treatment. They are lengthy and consume high amounts of energy and solvents. In recent years, microwave-assisted extraction (MAE) has shown enormous potential to overcome major drawbacks that outcome from conventional plant material extraction (thermal and/or solvent based) techniques, being also successfully applied to the extraction of agar, fucoidans and alginates. In the present study, acid pretreatment of brown seaweed Saccorhiza polyschides for subsequent microwave-assisted extraction (MAE) of alginate was optimized. Seaweeds were collected in Northwest Portuguese coastal waters of the Atlantic Ocean between May and August, 2014. Experimental design was used to assess the effect of temperature and acid pretreatment time in alginate extraction. Response surface methodology allowed the determination of the optimum MAE conditions: 40 mL of HCl 0.1 M per g of dried seaweed with constant stirring at 20ºC during 14h. Optimal acid pretreatment conditions have enhanced significantly MAE of alginates from Saccorhiza polyschides, thus contributing for the development of a viable, more environmental friendly alternative to conventional processes.

Keywords: Acid pretreatment, Alginate, Brown seaweed, Microwave-assisted extraction, Response surface methodology.

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Authors: Tatsaporn Todhanakasem, Kamonchanok Areerat, Pornthap Thanonkeo, Roungdao KlinjapoandGlenn M. Young

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Rice bran has been abandoned as agricultural waste for million tonnes per year in Thailand, therefore they have been proposed to be utilized as a rich carbon source in the production of bioethanol. Many toxic compounds are possibly released during the pretreatment of rice bran prior the fermentation process. This study aims to analyze on the availability of toxic compounds and the amount of glucose obtained from 2 different pretreatments using sulfuric acid and mixed cellulase enzymes (without and with delignification/ activated charcoal). The concentration of furfural, 5- hydroxymethyl furfural (5-HMF), levulinic acid, vanillin, syringaldehyde and4-hydroxybenzaldehyde (4-HB) and the percent acetic acid were found to be 0.0517 ± 0.049 mg/L, 0.032 ± 0.06 mg/L, 21074 ± 1685.62 mg/L, 126.265 ± 6.005 mg/L, 2.89 ± 0.30 mg/L, 0.37 ± 0.031mg/L and 0.72% under the pretreatment process without delignification/ activated charcoal treatment and 384.47 ± 99.02 g/L, 0.068 mg/L, 142107.62 ± 8664.6 mg/L, 0.19 mg/L, 5.43 ± 3.29 mg/L, 4.80 ± 0.76 mg/L and 0.254% under the pretreatment process with delignification/ activated charcoal treatment respectively. The presence of high concentration of acetic acid was found to impede the growth of Zymomonas mobilis strain TISTR 551 despite the present of high concentration of levulinic acid. Z. mobilis strain TISTR 551 was found to produce 8.96 ± 4.06 g/L of ethanol under 4 days fementation period in biofilm stage in which represented 40% theoretical yield.

Keywords: Rice bran, Zymomonas mobilis, biofilm, ethanol.

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Authors: N. Boontian

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Biological conversion of biomass to methane has received increasing attention in recent years. Grasses have been explored for their potential anaerobic digestion to methane. In this review, extensive literature data have been tabulated and classified. The influences of several parameters on the potential of these feedstocks to produce methane are presented. Lignocellulosic biomass represents a mostly unused source for biogas and ethanol production. Many factors, including lignin content, crystallinity of cellulose, and particle size, limit the digestibility of the hemicellulose and cellulose present in the lignocellulosic biomass. Pretreatments have used to improve the digestibility of the lignocellulosic biomass. Each pretreatment has its own effects on cellulose, hemicellulose and lignin, the three main components of lignocellulosic biomass. Solidstate anaerobic digestion (SS-AD) generally occurs at solid concentrations higher than 15%. In contrast, liquid anaerobic digestion (AD) handles feedstocks with solid concentrations between 0.5% and 15%. Animal manure, sewage sludge, and food waste are generally treated by liquid AD, while organic fractions of municipal solid waste (OFMSW) and lignocellulosic biomass such as crop residues and energy crops can be processed through SS-AD. An increase in operating temperature can improve both the biogas yield and the production efficiency, other practices such as using AD digestate or leachate as an inoculant or decreasing the solid content may increase biogas yield but have negative impact on production efficiency. Focus is placed on substrate pretreatment in anaerobic digestion (AD) as a means of increasing biogas yields using today’s diversified substrate sources.

Keywords: Anaerobic digestion, Lignocellulosic biomass, Methane production, Optimization, Pretreatment.

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Authors: Pilanee Vaithanomsat, Sinsupha Chuichulcherm, Waraporn Apiwatanapiwat

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Sunflower stalks were analysed for chemical compositions: pentosan 15.84%, holocellulose 70.69%, alphacellulose 45.74%, glucose 27.10% and xylose 7.69% based on dry weight of 100-g raw material. The most optimum condition for steam explosion pretreatment was as follows. Sunflower stalks were cut into small pieces and soaked in 0.02 M H2SO4 for overnight. After that, they were steam exploded at 207 C and 21 kg/cm2 for 3 minutes to fractionate cellulose, hemicellulose and lignin. The resulting hydrolysate, containing hemicellulose, and cellulose pulp contained xylose sugar at 2.53% and 7.00%, respectively.The pulp was further subjected to enzymatic saccharification at 50 C, pH 4.8 citrate buffer) with pulp/buffer 6% (w/w)and Celluclast 1.5L/pulp 2.67% (w/w) to obtain single glucose with maximum yield 11.97%. After fixed-bed fermentation under optimum condition using conventional yeast mixtures to produce bioethanol, it indicated maximum ethanol yield of 0.028 g/100 g sunflower stalk.

Keywords: Enzymatic, steam explosion, sunflower stalk, ethanol production.

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Authors: M. Poveda, S. Lozecznik, J. Oleszkiewicz, Q. Yuan

Abstract:

The goal of this experiment is to evaluate the effectiveness of different leachate pre-treatment options in terms of COD and ammonia removal. This research focused on the evaluation of physical-chemical methods for pre-treatment of leachate that would be effective and rapid in order to satisfy the requirements of the sewer discharge by-laws. The four pre-treatment options evaluated were: air stripping, chemical coagulation, electrocoagulation and advanced oxidation with sodium ferrate. Chemical coagulation reported the best COD removal rate at 43%, compared to 18% for both air stripping and electro-coagulation, and 20% for oxidation with sodium ferrate. On the other hand, air stripping was far superior to the other treatment options in terms of ammonia removal with 86%. Oxidation with sodium ferrate reached only 16%, while chemical coagulation and electro-coagulation removed less than 10%. When combined, air stripping and chemical coagulation removed up to 50% COD and 85% ammonia.

Keywords: Leachate pretreatment, air stripping, chemical coagulation, electro-coagulation, oxidation.

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Authors: Evita Straumite, Zanda Kruma, Ruta Galoburda, Kaiva Saulite

Abstract:

Dill (Anethum graveolens L.) is a popular herb used in many regions, including Baltic countries. Dill is widely used for flavoring foods and beverages due to its pleasant spicy aroma. The aim of this work was to determine the best blanching method for processing of dill prior to microwave vacuum drying based on sensory properties, color and volatile compounds in dried product. Two blanching mediums were used – water and steam, and for part of samples microwave pretreatment was additionally used. Evaluation of dried dill volatile aroma compounds, color changes and sensory attributes was performed. Results showed that blanching significantly influences the quality of dried dill. After evaluation of volatile aroma compounds, color and sensory properties of microwave vacuum dried dill, as the best method for dill pretreatment was established blanching at 90 °C for 30 s.

Keywords: dried dill, sensory panel, sensory properties, aroma compounds, color

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Authors: E. Danso-Boateng

Abstract:

The effects of enzyme action and heat pretreatment on oil extraction yield from sunflower kernels were analysed using hexane extraction with Soxhlet, and aqueous extraction with incubator shaker. Ground kernels of raw and heat treated kernels, each with and without Viscozyme treatment were used. Microscopic images of the kernels were taken to analyse the visible effects of each treatment on the cotyledon cell structure of the kernels. Heat pretreated kernels before both extraction processes produced enhanced oil extraction yields than the control, with steam explosion the most efficient. In hexane extraction, applying a combination of steam explosion and Viscozyme treatments to the kernels before the extraction gave the maximum oil extractable in 1 hour; while for aqueous extraction, raw kernels treated with Viscozyme gave the highest oil extraction yield. Remarkable cotyledon cell disruption was evident in kernels treated with Viscozyme; whereas steam explosion and conventional heat treated kernels had similar effects.

Keywords: Enzyme-assisted aqueous and hexane extraction, heatpretreatment, sunflower cotyledon structure, sunflower oil extraction

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Authors: Ackmez Mudhoo, Pravish Rye Moorateeah, Romeela Mohee

Abstract:

This paper presents the results of the preliminary investigation of microwave (MW) irradiation pretreatments on the anaerobic digestion of food residues using biochemical methane potential (BMP) assays. Low solids systems with a total solids (TS) content ranging from 5.0-10.0% were analyzed. The inoculum to bulk mass of substrates to water ratio was 1:2:2 (mass basis). The experimental conditions for pretreatments were as follows: a control (no MW irradiation), two runs with MW irradiation for 15 and 30 minutes at 320 W, and another two runs with MW irradiation at 528 W for 30 and 60 minutes. The cumulative biogas production were 6.3 L and 8.7 L for 15min/320 W and 30min/320 W MW irradiation conditions, respectively, and 10.5 L and 11.4 L biogas for 30min/528 W and 60min/528 W, respectively, as compared to the control giving 5.8 L biogas. Both an increase in exposure time of irradiation and power of MW had increased the rate and yield of biogas. Singlefactor ANOVA tests (p<0.05) indicated that the variations in VS, TS, COD and cumulative biogas generation were significantly different for the pretreatment conditions. Results from this study indicated that MW irradiation had enhanced the biogas production and degradation of total solids with a significant improvement in VS and COD solubilization.

Keywords: microwave irradiation, pretreatment, anaerobic digestion, food residues.

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