Rice straw structure changes following green pretreatment with petha wastewater for economically viable bioethanol production

Strategies for processing and valorization of ash gourd byproducts: A comprehensive review

Ash gourd (Benincasa hispida) is cultivated for its medicinal benefits, with processing enhancing its health properties and shelf life. The processing industries generate significant byproducts, with peel and seeds common across all methods, along with lime (from petha sweet production), brine wastewater (from fermented foods), and pulp from juice processing. This review focuses on peel, seeds, and lime wastewater, which contain valuable compounds like polyphenols, terpenoids, essential oils, and ribosome-inactivating proteins known for their antioxidant and antibacterial properties. The review explores the bio-functionalities of these byproducts, highlighting applications in wastewater treatment, bioenergy production, edible coatings, prebiotics, medicinal products, and enzyme production. Rich in polyphenols, flavonoids, and essential oils, these byproducts offer versatile uses, such as biosorption, bio-coagulation, nanoparticle synthesis, bioenergy production, and medicinal formulations. Further research into their potential for functional foods and high-value applications is essential to maximize their benefits for human health, environmental sustainability, and economic growth.

Assessment the performance of chemical constituents of agro wastes in production safety alternative carbon black filler in rubber composite purpose

Recently, minimizing petroleum resources as well as safely disposing of agro-wastes are essential for the production process to comply with environmental legislation. Bio-filler as an alternative to non-safety carbon black (CB) from petroleum resources in the production of rubber composites is investigated by many researchers, but unfortunately it leads to deterioration of the properties of rubber composites. To avoid this drawback, different agro-wastes (rice straw, date palm fiber, and reed (Arundo donax L.) with different chemical constituents as precursors of biofillers (biochars) are assessed toward the performance of ethylene-propylene-diene terpolymer rubber (EPDM). The role of replacing parts of CB with biochar on the rheological characteristics, physico-mechanical properties, hardness, swelling, and crosslinking density of EPDM composites is studied. The results proved the efficient low replacing ratio of biochar towards increasing the minimum and maximum torque; this indicates a homogeneous filler structure and crosslinking interactions between the components matrix as emphasized from the morphological analysis of EPDM rubber. The reverse trend is noticed on increasing the replacement ratio over 25%, where it deteriorates the tensile strength in comparison to pristine CB. The data demonstrated the most efficient biochar, which is derived from RS. The formulation containing 75% CB and 25% RS-biochar provided EPDM with tensile strength (14.4 MPa), higher than the pure CB (12.45 MPa). Moreover, this optimum formulation provided high crosslinking density, high hardness shore A, and swelling resistance of motor oil and toluene when compared to EPDM with pure carbon black. This promising finding trend is not noticed in the literature on using biochars, which usually caused the deterioration in properties of rubber products.

Insight into carbon structural variation from steam gasification of rice straw on enhancing hydrogen generation

Converting biomass waste into hydrogen energy through gasification is a crucial pathway for producing "green hydrogen". In a fixed bed reactor, a representative biomass waste, rice straw (RS), was pyrolyzed at N2, H2O, CO2, and O2 atmospheres to generate hydrogen. Solid C-13 Nuclear Magnetic Resonance Spectroscopy (13C-NMR) and Fourier Transform infrared spectroscopy (FTIR) were employed to elucidate the carbon structure and functional groups of the samples. The hydrogen ratio in pyrolysis gas is monitored by gas chromatography (GC). The results show that hydrogen release from RS increases after 400 °C because of thermal polymerization occurrence shown in thermogravimetric(TG) analysis. Pyrolysis of RS at N2, H2O, CO2 and O2 atmosphere for H2 formation with the order is H2O > CO2>N2>O2. H2O is acted as catalyst, impregnant, and reactant for char forming reaction and gas rearrangement to facilitate H2 production which increases to 205.84 mL/g at 900 °C. The phenolic groups increase for forming the active intermediates to combines with H radical from H2O to form H2. Meanwhile, the H2O facilitates the rearrangement, condensation, and polymerization reaction of aromatic rings to form H2. The bridged aromatic carbon increases. H2 is also formed by gas rearrangement reaction from CH4 to H2 during steam gasification. These results are the guide for equipment development and industrialization for biomass waste to hydrogen energy.

Rice bran as a potent ingredient: unveiling its potential for value-added applications

Rice bran production significantly contributes to global environmental deterioration, yet its potential remains underutilized. This review discusses the nutritional composition, bioactive compounds, health benefits, limitations, and potential application of rice bran in both food and non-food sectors. While minor variations exist between pigmented and non-pigmented rice bran, the former is abundant in phytochemicals, which offer therapeutic benefits. The primary limitations hindering rice bran's food application include rancidity, toxic heavy metals, and antinutrients. Effective stabilization is crucial to extend rice bran's shelf life. Despite these challenges, rice bran holds significant potential for value-added products. Hence, its rich composition and diverse applications underscore its importance as a valuable resource for sustainable production practices.

Investigating the potential of delignified rice husk as a carbon-rich resource for extracting glucose and its utilization in biocement production through fungal isolates

Burning rice straw is now a significant issue faced by different regions in India, as its burning releases harmful gases, mainly carbon dioxide. Various techniques are now in trend to utilize the rice straw, e.g., producing compressed natural gas using rice straw, bioethanol, etc., as a substrate for various microorganisms. A high quantity of non-utilized rice husk generates more ideas for its proper utilization. The cellulose, hemicellulose, and lignin found in rice straws can be a fungi growth medium. In this research, the delignification of rice husk is done by acid (2% and 4% H2SO4) and alkali (2% and 4% NaOH) at 121 °C at 103 kPa for 1 h to obtain crude carbon source which is further utilized for biomineralization. The glucose is subjected to qualitative and quantitative analysis using Molisch's and Dinitro salicylic tests. The delignification process showed a positive outcome when 2% H2SO4 is utilized maximum yield of 5.9 ug/ml free sugar concentration. Representing the highest glucose yield compared to the experiment's other acid and base substances used. Various techniques such as field emission-scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and Fourier transformed infra-red (FTIR) spectroscopy are employed to examine surface and chemical alterations. The 2% H2SO4 pretreated rice husk is utilized for microbial-induced calcite precipitation using fungal isolates S1 (3), S1 (18), and S4 (1). The calcite and vaterite produced by biomineralization are confirmed using XRD for fungal isolates namely, S1 (3), S1 (18), and S4 (1) having percentage crystallinity of 59%, 46.428%, and 62.69% percentage crystallinity respectively.

Enhanced ethanol production using hydrophobic resin detoxified Pine forest litter hydrolysate and integrated fermentation process development supplementing molasses

Globally escalating ethanol demand necessitates the use of hybrid technologies integrating first- and second-generation biofuel feedstocks for achieving the futuristic targets of gasoline replacement with bioethanol. In present study, an optimized two-step sequential pre-treatment (first dilute alkali, then dilute acid) of Pine forest litter (PFL) was developed. Furthermore, the saccharification of pre-treated PFL was optimized through Response Surface Methodology using Box-Behnken Design, wherein 0.558 g/g of reducing sugar was released under the optimized conditions (12.5% w/v of biomass loading, 10 FPU/g of PFL enzyme loading, 0.15% v/v Tween-80 and 48 h incubation time). Moreover, during hydrolysate fermentation using Saccharomyces cerevisiae NCIM 3288 strain, 22.51 ± 1.02 g/L ethanol was produced. Remarkably, hydrophobic resin (XAD-4) treatment of PFL hydrolysate, significantly removed inhibitors (Furfural, 5-hydroxymethylfurfural and phenolics) and increased ethanol production to 27.38 ± 1.18 g/L. Furthermore, during fermentation of molasses supplemented PFL hydrolysate (total initial sugar: 100 ± 3.27 g/L), a maximum of 46.02 ± 2.08 g/L ethanol was produced with 0.482 g/g yield and 1.92 g/l/h productivity. These findings indicated that the integration of molasses to lignocellulosic hydrolysate, would be a promising hybrid technology for industrial ethanol production within existing bio-refinery infrastructure.

An enhanced productivity of pink oyster mushroom with improved nutritional profile, characterization and attempt for commercial exploitation

BACKGROUND

An attempt has been made to explore the nutritional profile of pink oyster mushrooms that have been grown in various agricultural residues, including sugarcane bagasse, rice straw, coconut coir and sawdust, along with other nutrient supplements such as defatted mustard and chickpea powder, for appropriate growth and fruiting body formation in a short span of time. The spawn production was experimented with five different grain varieties. The study became interesting when the observations differed slightly from the traditional practices, with the addition of defatted mustard supplements resulting in a positive correlation with respect to reducing the fruiting time, as well as improving yield and the nutritional profile of Pleurotus djamor.

RESULTS

An elevated yield of 651.93 g kg-1 was recorded in the medium where the RS and DM were used in the ratio of 1:0.01 (rice straw +1% w/w defatted mustard) bag, whereas, in terms of protein content, a maximum yield of 32.57 ± 0.79 mg g-1 was observed when SB:DM was in the same ratio (sugarcane bagasse +1% w/w defatted mustard) bag.

CONCLUSION

To confer the best outcomes from the screened substrates, a series of experiments were performed by varying the concentration of RS and SB, with 1% w/w DM. It is worth noting that the highest protein content of 32.76 ± 0.38 mg g-1 was obtained along with the total yield of 702.56 ± 2.9 g kg-1 of mushroom when the ratio of RS:SB was 0.7:0.3. © 2024 Society of Chemical Industry.

Microplastic and adhesive free, multifunctional, circular economy approach-based biomass-derived drinking straws

Generation of voluminous single-use plastic waste and byproducts from agricultural harvests such as rice straws (RSs) are major global challenges due to their disposal issues, contributing to greenhouse gas emissions, and affecting the ecological system with threats to human health. A scalable, low-cost, and eco-friendly strategy for fabricating cellulose-silica-based drinking straws, free from microplastics and adhesive, through strategic valorization of RS is reported. Functionalization by delignification-cum-crosslinking of RS leads to development of straws with high water stability (∼5 days), solvothermal stability (0°C-95°C), tensile strength (128 MPa), low migration values (<60 mg/kg), improved biodegradability (∼126 days) with reduced wettability and hydrophobicity. RS drinking straws show antibacterial, self-cleaning, self-healing, anti-fizzing, reusable, and generate significantly lower carbon footprint (<99.8% and <53.34% global warming potential than metal and polylactic acid straws). Repurposing of agro-wastes from farms to commercially viable drinking straws which biodegrades after its consumption achieves the goal of circular economy and sustainable development.

Co-densification of rice straw and cow dung in different food-to-microorganism ratios for biogas production

Agricultural residues such as rice straw (RS) are desirable raw materials for biogas generation. However, the recalcitrant nature of RS hinders biogas production, and its low bulk density increases storage space requirements, transportation needs, and overall costs. These challenges could be resolved by pretreatment and pelletization. In this study, various thermal pretreatments were performed, and the best conditions (temperature and time) were identified. Also, rice straw and cow dung pellets (RCP) at different food-to-microorganism (F/M) ratios (0.5-2.5) were prepared. Parameters such as bulk density, moisture absorption, and drop shatter tests were conducted to evaluate the physical properties. Finally, the biochemical methane potential (BMP) study of the best RCP with varying total solids (TS: 4-12%) content was investigated. The results indicate that hot air oven pretreatment (for 60 min at 120 °C) resulted in maximum solubilization. In physical characteristics, RCP with an F/M ratio of 2.5 pellets was ideal. The bulk density of RCP 2.5 was found to be around 25 times that of the raw. Also, the TS 8% yielded maximum biomethane (279 mL/g-VSconsumed) as compared to other TS contents. Overall, this study will propel the growth of bioenergy while simultaneously tackling the pressing issues related to RS management.

Enhancing Bioethanol Production from Rice Straw through Environmentally Friendly Delignification Using Versatile Peroxidase

Rice straw (RS), an agricultural residue rich in carbohydrates, has substantial potential for bioethanol production. However, the presence of lignin impedes access to these carbohydrates, hindering efficient carbohydrate-to-bioethanol conversion. Here, we expressed versatile peroxidase (VP), a lignin-degrading enzyme, in Pichia pastoris and used it to delignify RS at 30 °C using a membrane bioreactor that continuously discarded the degraded lignin. Klason lignin analysis revealed that VP-treatment led to 35% delignification of RS. We then investigated the delignified RS by SEC, FTIR, and SEM. The results revealed the changes of RS caused by VP-mediated delignification. Additionally, we compared the saccharification and fermentation yields between RSs treated with and without VP, VP-RS, and Ctrl-RS, respectively. This examination unveiled an improvement in glucose and bioethanol production, VP-RS exhibiting up to 1.5-fold and 1.4-fold production, respectively. These findings underscore the potential of VP for delignifying RS and enhancing bioethanol production through an eco-friendly approach.

Bioethanol production from alkali-pretreated rice straw: effects on fermentation yield, structural characterization, and ethanol analysis

Current ethanol production technology has a dire need for efficient conversion of lignocellulosic biomass to fermentable sugars. The conversion requires pretreatment of the biomass, one of the most expensive steps, and thus it is quite necessary to identify the most cost-effective and high-efficiency conversion method. In this study, rice straw (RS) biomass was pretreated using 4% NaOH alkali, soaked for 4 h, and autoclaved for 30 min. The structural and morphological changes were examined using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) analysis in both native and alkali-treated RS. The FTIR analysis revealed that native RS contains a considerable amount of lignin that was removed after the pretreatment process. The XRD pattern of the RS revealed an increasing crystallite size of the pretreated lignocellulosic biomass. The study of SEM clearly showed the distorted structure and surface porosity after the pretreatment process. Enzymatic hydrolysis efficiency was checked by comparing the commercial enzymes and microbial hydrolysis extracted from a fungal isolate. The best-reducing sugar yield obtained was 0.62 g/L, achieved at optimized conditions from the commercial enzymes. Fermentation efficiency was checked using the yeast isolate Saccharomyces cerevisiae in both the native and pretreated substrate, and the highest ethanol concentration (21.45%) was achieved using 20% w/v biomass loading, enzyme loading (2:1:1), and fermentation for a week at 30°C and pH 4.5. This concentration was higher than that of the untreated RS (3.67%). The ethanol thus produced was further checked for analysis by the 1H and 13C nuclear magnetic resonance (NMR) methods.

Enhancing of pretreatment on high solids enzymatic hydrolysis of food waste: Sugar yield, trimming of substrate structure

The development of high solids enzymatic hydrolysis (HSEH) technology is a promising way to improve the efficiency of bioenergy production from solid waste. Pretreatment methods such as ultrasound (USP), freeze-thaw (FTP), hydrothermal (HTP), and dried (DRD) were carried out to evaluate the effect and mechanism of the pretreatment methods on the HSEH of FW. The reducing sugar of HTP and DRD reached 94.75% and 94.92% of the theoretical value. HTP and DRD could reduce the crystallinity of FW. DRD resulted in lower alignment and the occurrence of fractures of the substrate and exposed the α-1,4 glycosidic bond of starch. The high destructive power of HTP and DRD reduced the obstacles caused by the high solid content. Moreover, DRD consumed only 27.62% of the total energy of HTP. DRD could be a promising pretreatment methods for glucose recovery for its high product yield, significant substrate destruction, and economic feasibility.