Pretreated Rice Straw Research Articles

Anaerobic digestion of lignocellulosic waste for enhanced methane production and biogas-digestate utilization

Lignocellulosic biomass is an important source for nutrient management in agricultural systems and has a largely unexploited potential for biogas production. The digestates from the anaerobic digestion (AD) process are widely used in agriculture systems due to their nutrient composition and organic matter, making them a valuable source for plants. As a result, methane (CH4) production from AD of lignocellulosic biomass waste, such as rice straw, corn stalk, and grape stalk, was determined in this study, and their anaerobic digester residues were studied at various concentrations to investigate their potential on tomato plant growth and fruit yield. The biogas and CH4 yields of the pretreated rice straw, corn stalk, and grape stalk were determined through the AD process for 72 days, and the results revealed a gradual increase in the cumulative biogas and CH4 production until the end of the AD process (72 days). The cumulative biogas from rice straw, corn stalk, and grape stalk was 359.3, 309.9, and 215.1 L/kg VS, respectively. However, the biogas production of rice straw was higher than that of corn stalk, and grape stalk by 15.6% and 67%, respectively. The cumulative CH4 yield of rice straw was higher than that of corn stalk, and grape stalk by 21.1% and 76.3%, respectively. The results also showed that tomato growth significantly increased under grape stem residue (GSR) more than under rice straw residue (RSR) and corn stalk residue (CSR), as well as under untreated control and control infected with Fusarium oxysporum f. sp. lycopersici (FOL). The increase in bioreactor residue concentration resulted in a significant increase in tomato growth parameters, crop yield, and tomato quality. The results confirmed that 20% of GSR increased the tomato's physical and chemical properties compared with control, RSR, and CSR. The soil content of total nitrogen, phosphorus, and potassium gradually increased with the increase in residue concentrations before and after AD, and the maximum concentration was obtained at 25% of GSR. Therefore, anaerobic digestate could be economically viable, which can be a good solution for sustainable lignocellulosic biomass waste management and plant growth.

Evaluation of Fermentative Xylitol Production Potential of Adapted Strains of Meyerozyma caribbica and Candida tropicalis from Rice Straw Hemicellulosic Hydrolysate

Dilute acid hydrolysis of lignocellulosic biomass generates inhibitors in the hydrolysate which hamper yeast metabolism and the fermentation process. Therefore, understanding the effect of these compounds on the performance of microorganisms becomes essential to achieve improved product yields. In this study, the effect of acetic acid, furfural, and hydroxymethylfurfural was evaluated on yeast growth and fermentation efficiency. Various parameters for the pretreatment of rice straw, such as an acid catalyst, and its concentration and residence time, were optimized for the maximum liberation of sugars in the hydrolysate. Further, the yeast strains Candida tropicalis and Meyerozyma caribbica were adapted for the tolerance of inhibitors at higher concentrations. A comparative analysis was carried out using un-adapted and adapted strains of Candida tropicalis and Meyerozyma caribbica for xylitol production. The findings of this study revealed that sulfuric acid (1.25% v/v) at 121 ரC for 30 min can efficiently convert rice straw xylan to xylose, with the release of 16.07 g/L xylose in the hydrolysate. Further, the adaptation results showed an increase of 76.42% and 69.33% in xylose assimilation by C. tropicalis and M. caribbica, respectively. The xylitol production with the adapted C. tropicalis was increased by 7.54% to 28.03 g/L xylitol. However, the xylitol production with the adapted M. caribbica was increased by 8.33%, yielding 26.02 g/L xylitol in the non-detoxified hydrolysate when compared to the un-adapted strains. Repeated batch fermentation was carried out for seven batches, and xylitol was found to be efficiently produced by the yeasts during five successive batches without any significant loss in the xylitol yield. Moreover, the results suggest that M. caribbica is a promising microorganism for the transformation of rice straw-derived xylose to xylitol.

Steam Explosion Pretreatment with Different Concentrations of Hydrogen Peroxide along with Citric Acid: A Former Step towards Bioethanol Production

The present paper focuses on the utilization of the steam explosion method for efficient pretreatment of rice straw, used as a prominent substrate for bioethanol production. Native rice straw contains abundant chemical compounds in the form of cellulose, hemicellulose, and lignin 32.4%, 57%, and 12.5%, respectively. Pretreatment with different concentrations of H2O2 (0.05%, 0.1%, 0.25%, 0.5%, 0.75%, and 1%) was used as efficient impregnating agents at an optimum temperature of 121°C at 130 kPa pressure. After pretreatment, cellulosic content increases up to 54.5% while there was a reduction in the hemicellulose and lignin content up to 46.5% and 6.7%, respectively. The morphological changes were analyzed both before and after pretreatment using FTIR, TGA, and XRD. The reducing sugar estimation was carried out using DNS reagent and the absorbance was measured using a UV spectrophotometer at 540 cm-1 wavelength. Estimated results show a reducing sugar yield of 220.05 g/l from 0.05% ( v / v ) H2O2 pretreated sample and 273.21 g/l from sample, pretreated with H2O2, citric acid in the ratio of 1 : 1 with the same previous concentration. The XRD data shows enhancement of cellulose accessibility upon pretreatment to 13.3% and thereafter reduction with an increase in the concentration of H2O2. While pretreatment with H2O2 combined with citric acid in 1 : 1 ratio shows enhanced accessibility of 19.6% than untreated rice straw. This work mainly focuses on the core objective of an efficient pretreatment method for sustainable bioethanol production through a novel approach to the production of fermentable sugar.

The utilization of black liquor from rice straw pretreatment stage on the syntheses of carbon-based materials using in anodes ion-lithium batteries production

The utilization of black liquor from rice straw pretreatment stage on the syntheses of carbon-based materials using in anodes ion-lithium batteries production

Physiochemical characteristics and methane yield of pretreated rice straw, canola straw, and banana plant substrate with buffalo dung by anaerobic co-digestion: sustainable future for Pakistan

Physiochemical characteristics and methane yield of pretreated rice straw, canola straw, and banana plant substrate with buffalo dung by anaerobic co-digestion: sustainable future for Pakistan

Life cycle assessment of bioethanol production by two methods of pretreatment of rice straw based on process simulation

Life cycle assessment of bioethanol production by two methods of pretreatment of rice straw based on process simulation

Bioethanol Production from Ammonia Pretreated Rice Straw

Rice straw is produced in large quantity throughout the world. Rice straw is a leading feedstock for bioethanol production. Diluted ammonia pretreatment for one week at room temperature was found to be effective pretreatment. This pretreated rice straw was acid hydrolyzed and subsequently fermented with Saccharomyces cerevisiae CP11 strain. 1.5% ammonia pretreatment at room temperature for one week resulted 82.4% delignification and 78.49% of acid hydrolysis. Acid hydrolysate was fermented with maximum ethanol concentration 5.70 % with an ethanol yield of 0.46g/g and fermentation efficiency of 90.6%. Diluted ammonia pretreatment at higher temperature has reduced delignification, saccharification and fermentation efficiency with more phenols and furfurals.

Enhancing ethylene glycol and ferric chloride pretreatment of rice straw by low-pressure carbon dioxide to improve enzymatic saccharification

Ethylene glycol and ferric chloride pretreatment assisted by low-pressure carbon dioxide (1 MPa CO2) realized the targeted deconstruction of lignocelluloses at 170 °C for 5 min, achieving 98 % cellulose recovery with removal of 92 % lignin and 90 % hemicellulose. After the pretreatment, the formation of stable platform mono-phenol components would be with the destruction of the lignin-carbohydrate complexes structure, and the surface of rice straw became rough, with a less negative charge and higher specific surface area, while the enzyme adsorption rate increased by 8.1 times. Furthermore, the glucose yield of pretreated straw was remarkably increased by 5.6 times that of the untreated straw, reaching 91 % after hydrolyzed for 48 h. With Tween 80 added in concentrated solid (12 %) hydrolysis at low cellulase loading (3 FPU/g dry substrate), half of the hydrolysis time was shortened than that without Tween 80, with 45 % higher glucose yield.

Maximization of biogas by minimal microwave and alkaline pretreatment of rice straw

Maximization of biogas by minimal microwave and alkaline pretreatment of rice straw

Efficient process for xylitol production from nitric acid pretreated rice straw derived pentosans by Candida tropicalis GS18

Valorization of agricultural residues has garnered worldwide interests due to their inexpensive, renewable and environment friendly nature. Among various lignocellulosic wastes, rice straw is the third-most abundantly available biomass rich in hemicelluloses and an easily accessible biomass for biological production of xylitol. In the present study, dilute nitric acid was employed for fractionation of hemicellulosic component of rice straw. Screening of various parameters such as solid to liquid ratio, acid concentration, residence temperature and time was carried out for maximal liberation of fermentable sugars. Xylose conversion was attained to the extent of 71.32% from the xylan of rice straw upon treating with 1% (v/v) dilute HNO3 at 121 °C for 30 min. In the process, complete removal of furfurals and HMF as well as partial removal of acetic acid was achieved by using 2% (w/v) activated carbon. Maximum xylitol titre of 25.15 g/L and 34.21 g/L was obtained during fermentation of non-detoxified and detoxified hydrolysate of rice straw biomass respectively by the newly isolated strain of Candida tropicalis GS18 at 30 °C, 150 rpm and pH 5.5 after 96 h of fermentation. This study suggested the use of dilute nitric acid as an effective and environment friendly catalyst for efficient recovery of xylose from rice straw and its subsequent use for xylitol production.

High-titer lactic acid production from pilot-scale pretreated non-detoxified rice straw hydrolysate at high-solid loading

Lignocellulosic biomasses are promising feedstocks for the production of high-value chemicals because they are abundant, inexpensive, renewable, sustainable, environmentally friendly, and can potentially reduce pollution. Furthermore, lignocellulose biomass is non-edible and a source of fermentable sugars, which makes it ideal for the fermentation of various biochemicals, such as bio-based lactic acid (LA). Furthermore, it contributes to the economic sustainability of biorefineries. LA is an industrially significant product with a large and rapidly growing market due to its attractive features and benefits. The current study demonstrates high-titer lactic acid (LA) fermentation from pretreated rice straw using co-fermenting (C5 & C6 sugars) Lactobacillus lactis 2369. Rice straw (RS) was chemically pretreated with mild acid additive in a pilot-scale (250 Kg day–1) steam-explosion unit. At first, the crude dilute acid pretreated slurry was enzymatically hydrolyzed using commercial cellulases (1.5–10 FPUg−1 residue) at 50 °C for 48 h followed by LA production for 96–140 h. In the current study high titer, LA production (82.2 gL−1) as well as higher conversion yield (87.2%) with the productivity of 0.61 gL−1h−1 were obtained with high substrate solid loading (20% wv−1) and low enzyme dose (5 FPU g−1) at 42 °C.

Bioethanol Production from Rice Straw and Cellulose Degradation using Aspergillus terreus and Trichoderma harzanium

On account of its minimal expense and a high potential for change into energy-producing products, lignocellulosic biomass is the future of bioenergy and energy. Notwithstanding, their true capacity is restricted by the utilization of inefficient and unstable enzymes. Therefore, the present work aim to investigate the cellulose degradation potential of two isolated fungal species Aspergillus terreus and Trichoderma harzanium followed by bioethanol production from acid-thermal pre-treated rice straw (RS). The experiments were conducted in two phases. In phase-I of experiments, the isolated cellulose-degrading fungal species (Aspergillus terreus and Trichoderma harzanium) were employed for enzymatic hydrolysis of pretreated RS which was separated into two fractions namely: (Hydrolysate liquid) HL and (Residual pulp) RP. In phase-II of experiments, the enzymatically hydrolyzed substrate was subjected to yeast fermentation for bioethanol production. Using 18S rRNA sequencing, the microbial diversity study of the isolated species is covered in detail. The results revealed that the isolated fungal species A. terreus and T. harzanium resulted in 80 % of cellulose degradation. The highest bioethanol yield of 0.38 and 0.42 g/g of glucose was obtained from HL using Aspergillus terreus and Trichoderma harzanium treatment followed by yeast fermentation. The bioethanol yield of 0.17 g/g of cellulose was obtained from HL using both the fungal species.

Efficient catalytic conversion of biomass derived cellulose to short chain polyols

In efforts to replace petro-derived polyethylene terephthalate (PET) with a ‘green’ equivalent, technologies are being developed and scaled up for biobased production of the two components of PET viz. monoethylene glycol (MEG) and terephthalic acid. Herein, we report work on single-pot catalytic hydrogenolysis of cellulose isolated from lignocellulosic biomass into polyols with the major fraction being monoethylene glycol. A combination of silica-alumina-supported nickel (NSA) and bulk tungsten-based catalyst (HW) was investigated for selective conversion of cellulose to MEG. While raw rice straw showed negligible conversion, the two-step pretreated rice straw performed similar to pure cellulose. Ethylene glycol in up to 60 % yield was obtained over 0.15%NSA-0.2%HW within minutes at a hydrogen pressure lower than reported thus far for similar catalysts. Product buildup was seen to have no effect on the catalyst activity and a fed-batch approach could generate product stream in high concentrations with MEG as a single major product.

Evaluation of fungal consortium lignozyme for biodelignification of agricultural residues

AbstractTwo fungal cultures Pleurotus ostreatus (PAU03) and Phanerochaete chrysosporium (MTCC 787) were investigated for their ability to produce ligninolytic enzymes – mainly laccase (Lacc), manganese peroxidase (MnP) and lignin peroxidase (LiP) – under solid‐state fermentation (SSF) conditions, using corn stover as a substrate. Crude LiP, MnP, and Lacc demonstrated specific activity of 11.65 U/mg, 14.9 U/mg and 9.84 U/mg, respectively. The precipitation of crude extract by 70% acetone and subsequent Diethyl amino ethyl (DEAE)‐cellulose ion exchange chromatography resulted in 2.24, 1.23 and 2.60‐fold purification of LiP, MnP and Lac activities, respectively with corresponding specific activities of 26.14 U/mg (LiP), 18.33 U/mg (MnP) and 25.67 U/mg (Lacc) in the partially purified ligninozymes. The latter showed three distinct bands of 40–56 kDA when resolved with sodium dodecyl‐sulfate polyacrylamide gel electrophoresis (SDS‐PAGE). The optimum pH was 6.5 for Lacc and LiP, and 3.0 for MnP, with an optimum temperature of 40 °C. The partially purified laccase had Km of 0.044 mmol L−1/min and Vmax of 222.22 U/mL. Ca2+ and Mn2+ ions increased ligninozyme activity with an increase in concentration from 0.5–5 mmol L−1. Cu2+ ions inhibited ligninozyme activity. The ligninozyme‐assisted pretreatment of wheat straw, rice straw, corn stover, and corn cobs revealed delignification in the range of 70 to 80.3%. The corresponding cellulose and hemicellulose recovery ranged between 58.5 to 65.4% and 38.4 to 47.6%, respectively. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd.

Effect of time and temperature of pretreatment and anaerobic co-digestion of rice straw and swine wastewater by domesticated paddy soil microbes

Rice straw and swine wastewater are abundant, easy to obtain, and inexpensive biomass materials. Anaerobic digestion of rice straw and swine wastewater effectively regulates the carbon-to-nitrogen ratio and also improves methane production efficiency. The dense lignocellulosic structure, unsuitable carbon-to-nitrogen ratio, and light texture of rice straw hinder its application in anaerobic digestion. Effective pretreatment technologies can improve degradation efficiency and methane production. Our study is the first to apply domesticated paddy soil microbes to enhance the efficiency of hydrolytic acidification of rice straw and swine wastewater at varying temperatures and times. The results show that the highest total organic carbon (1757.2 mg/L), soluble chemical oxygen demand (5341.7 mg/L), and organic acid concentration (4134.6 mg/L) appeared in the hydrolysate after five days of hydrolytic acidification at 37 °C. Moreover, the use of hydrolysate produced 13% more gas and reduced the anaerobic digestion period by ten days compared to the untreated control. This suggests that using domesticated paddy soil microbes as a pretreatment might be a sustainable and cost-effective strategy for improving the degradation efficacy and methane production from lignocellulosic materials.

Effect of Fiber Chemical Treatments on Rice Straw Fiber Reinforced Composite Properties

ABSTRACT This work reports the effect of alkali, enzyme, and their sequential combination treatment on rice straw fiber properties (fiber diameter, aspect ratio, fiber length, bundle strength and elongation). The change in fiber properties and its association with rice straw fibers reinforced epoxy biocomposites has been studied. Biocomposites, prepared using the hand lay-up technique, were characterized using FTIR, TGA and SEM. The mechanical properties viz. tensile, flexural, impact and compression were measured according to the ASTM standards. Sound transmission loss and noise reduction coefficient of the composites was also determined. Results showed that the alkali and enzyme treatment to the rice straw significantly reduced fiber length and fiber diameter by 50%. Enzyme treatment caused the highest reduction in fiber diameter which increased the aspect ratio. The sequential combination of alkali and enzyme yielded significant improvements in the tensile (20%), flexural (22%), impact (98%), and compression (328%) strength of the composites. The noise reduction coefficient (0.95) of all rice straw composites was found excellent. Thus, alkali-enzyme pretreated rice straw fiber composite product is a good choice for agro-residue valorization and industrial product development.

A novel fermentation strategy for efficient xylose utilization and microbial lipid production in lignocellulosic hydrolysate

The sugar utilization efficiency and the tolerance of microorganism to inhibitors are essential for lipid production from lignocellulosic biomass. In this study, the sugar consumption and inhibitor tolerance characteristics of Trichosporon dermatis 32,903 were investigated. The results showed that the lipid yield on xylose was much lower than that on glucose, while these substrates exhibited comparative efficiency for cell growth. High inoculum size improved the tolerance of T. dermatis 32,903 to inhibitors. Based on these characteristics, sugar-targeted-utilization and cyclic fermentation strategy was developed. The tolerance of high inoculum size to inhibitors was utilized, glucose was targeted for lipid fermentation and xylose was targeted for cell growth. As a result, the lipid production efficiency was greatly enhanced. The lipid titer in hydrolysate of DLCA (Densifying Lignocellulosic biomass with Chemicals followed by Autoclave) pretreated rice straw was improved to as high as 38.4 g/L with lipid yield of 0.207 g/g consumed sugar.

Removal of lignin and silica from rice straw for enhanced accessibility of holocellulose for the production of high-value chemicals

The intricate nature and rigidity of rice straw, particularly the presence of lignin and silica, hinders the catalytic valorization, consequently decreasing the yield of target products. This study reports the concurrent removal of lignin and silica from rice straw to obtain enriched holocellulose, then transforming it to furfural (FUR) and levulinic acid (LA). Interestingly, rice straw in the form of powder displays an improved removal of lignin (51.0%) and silica (92.0%) during ammonia treatment. Encouragingly, adding organic solvents, such as THF, to the aqueous system during the pretreatment of rice straw improves the lignin removal to 60.0%. Upon improving lignin removal to 60%, the obtained holocellulose enriched solid residue yields 71.0% FUR along with 52.0% LA, which is 8 and 4-fold higher than what is obtained with parent rice straw, signifying the importance and the prerequisite of lignin and silica removal from rice straw.

Effect of the Combining Corn Steep Liquor and Urea Pre-treatment on Biodegradation and Hydrolysis of Rice Straw

A novel pre-treatment using corn steep liquor (CSL) and urea was developed to enhance the enzymatic saccharification and degradability of rice straw (RS). We used RS (1) without (Con) or with additives of (2) 5% urea (U), (3) 9% CSL and 2.5% urea (CU), and (4) 9% CSL and 5% urea (C5U). The result showed that the water-soluble carbohydrate (WSC) conversion of RS reached 69.32% after C5U pre-treatment. Scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction analysis (XRD) confirmed that the surface of pre-treated RS exposed more cellulose and hemicellulose due to the disruption of the resistant structure of lignocellulose. Pre-treated RS significantly decreased neutral detergent fiber (NDF) and acid detergent fiber (ADF) contents and increased crude protein (CP) content, microbial colonization, and induction of Carnobacterium and Staphylococcus attachment. Altogether, we concluded that pre-treatment of a combination of CSL and urea has the potential to improve the nutritive value of RS.

Understanding the effects of low enzyme dosage and high solid loading on the enzyme inhibition and strategies to improve hydrolysis yields of pilot scale pretreated rice straw

The commercial viability of 2G bioethanol production is dependent on cost-effective and efficient enzymatic hydrolysis of biomass at low enzyme and high dry solid loadings. In the present study, rice straw was subjected to a dilute acid pretreatment in a continuous pilot plant (250 kg/day).It was observed that, the glucan conversion yields were reduced by 26% at high solid loading (20% w/w) with low enzyme dosage of 3 FPU/g w/w of in-house developed enzyme (MRJ16). Thus, multiple approaches were investigated to enhance the glucan conversion yields, a) fed batch approach (splitting biomass or enzyme dosage during process), b) additives supplementation (surfactants, metal ions, non-enzymatic proteins and activated charcoal) and c) enzyme blending with accessory enzymes. Results showed that, the 3-stage fed-batch approach enhanced the hydrolysis yield by 12% in comparison to 14.3% increase with the selected surfactant (0.5% w/w Ecosurf). The selected metal salt (NiCl2, 1 mM) increased the glucan conversion by 13.2%, while, the non-enzymatic proteins (5% w/w yeast hydrolysate and yeast extract) improved the yields to 14.8% and 14.4%, respectively. The activated charcoal at a concentration of 0.5% w/w enhanced the hydrolysis yields by 14.4%. Further, 15.1% increase in sugar yield was obtained by supplementing the in-house produced enzyme (MRJ16) with xylanase from Thermomyces lanuginosus and BGL from Penicillium janthinellum EMS-UV-8. Finally, a unique optimized strategy was developed on the basis of selected approaches and parameters which demonstrated 24.7% higher saccharification in comparison to control. To the best of our knowledge, this is the only study available in literature where; a wide range of strategies were studies on a single feedstock (i.e. rice straw) pretreated at pilot-scale and determine its effect for improved enzymatic hydrolysis. Furthermore, developed process helps us to save (almost 2X) expensive enzyme to achieve same level of glucan conversion (∼62.0%) to make the overall process cost effective by using cheap and easily available additives. The current study also provided an in-depth understanding of enzyme inhibition at low enzyme dosages and high solid loadings in an industrially relevant scenario.