Advances in second‐generation biofuel production from rice straw and barley straw

The experimental work was carried out at Rice Mechanization Center, Meet Eldeebah village, Kafr Elsheikh governorate during harvesting session of 2013, to manufacture a new prototype for chopping rice and barley straw for producing the litter of poultry houses. The investigated variables were straw feed rate (0.15, 0.16, 0.17 and 0.18kg/s) and chaff cutting length (1.5, 2.5, 3.5 and 5cm). The effect of these variables on the prototype productivity, cutting efficiency and the energy consumed, ware investigated, the main results summarized as: At 0.16 kg/s feed rate, the productivity increased from 0.56 to 1.9t/h for rice, and from 0.41 to 1.39 t/h for barley when the cutting length increased from 1.5 to 5 cm. At 1.5cm cutting length, by increasing the feed rate from 0.15 to 0.18 kg/s, the prototype cutting efficiency decreased from 75 to 70 % for rice, and from 81 to 75.6 % for barley. The energy consumption rate of prototype decreased with increasing the feed rate of rice and barley straw. At 1.5cm cutting length, by increasing the feed rate from 0.15 to 0.18 kg/s, the energy consumption rate of prototype decreased from 9.84 to 8.36kw.h/t for rice, and from 8.36 to 7.1 kW.h/t for barley. Evaluation of using of two cutting methods (manufacture and normal) of shaving woods, barley and rice straw as bedding materials and mixture between barley + rice straw (1:1) on broiler performance, carcass yields, Bedding characteristics and chemical analysis of broiler meat, the body weight gain and feed intake, as well as, feed conversion ratio were improved (P<0.05) with the prototype cutting than normal cutting system.

The chemical composition, intake, digestibility, ultrastructure and microbial degradation of rice straw from Camargue were compared with barley straw. These variables were observed in two different herbivore digestive ecosystems: the sheep rumen and the donkey caecum. The two straws differed essentially in their ash content, which was three times higher in rice, owing to its silica content. Other chemical components were comparable, except a higher phenolic acids‐to‐lignin ratio in rice. Rice straw was better ingested than barley straw. Organic matter and neutral detergent fibre digestibilities were the same in both straws. Dry matter and cell wall disappearances could be adjusted to the exponential modelling equation with lag time, and differed between animals but not between straws. The sheep rumen had a higher extent of degradation, but the donkey caecum had a higher degradation rate. Statistical analysis revealed that cell‐wall components degradation was similar in the two straws except for ferulic acid, which was more degraded in rice straw. Scanning electron microscopy showed important differences in parenchyma degradation, which was much more effective in rice. Copyright © 2003 Society of Chemical Industry

Ethanol organosolv fractionation combined with ball milling was conducted on three major agricultural residues: Rice husk (RH), rice straw (RS), and barley straw (BS). The highest lignin extraction yields of RH, RS, and BS were 55.2%, 53.1%, and 59.4% and the purity of lignin recovered was 99.5% for RH and RS, and 96.8% for BS, with similar chemical characteristics, i.e., low molecular weight distributions (1453–1817 g/mol) and poly dispersity index (1.15–1.28). However, considering the simultaneous production of hemicellulose-derived sugars, distinctive fractionation behaviors were shown for the three agricultural residues. The highest hemicellulose-derived sugar yield was 73.8% when RH was fractionated at 170 °C for 30 min. Meanwhile, very low sugar yields of 31.9% and 35.7% were obtained from RS and BS, respectively. The highest glucan-to-glucose conversion yield from enzymatic hydrolysis of fractionated RH reached 85.2%. Meanwhile, the enzymatic digestibility of the fractionated RS and BS was 60.0% and 70.5%, respectively. Consequently, the fractionation efficiency for RH can be improved with fine refinement. For the case of RS, other fractionation process should be applied to achieve effective fractionation performance.

One of the most important aspects of mushroom cultivation is substrate disinfection. Steaming is usually adopted to kill harmful microorganisms that cause contamination on the substrates. This study was designed to assess the most cost-effective steaming duration for the production of mushrooms. A factorial experiment was used and arranged in Completely Randomized Design (CRD). The study was laid out to test the following treatments, which were replicated four (4) times. For Factor A (Main plot) A1 – 4 hours, A2 – 6 hours, A3 – 8 hours and A4 – 10 hours. Factor B (Subplot) B1 – 100% sawdust, B2 – 100% rice straw, B3 – 75% rice straw + 25% sawdust, B4- 50% rice straw + 50% sawdust and B5 – 25% rice straw + 75% sawdust. The steam or sterilization method with a longer period was found to be more efficient or productive since it had higher yield and higher biological efficiency than the short duration of sterilization time. The use of rice straw can be used as an alternative to sawdust as substrates for mushroom production. The 75% rice straw could be combined with sawdust at 25% on white oyster mushroom production to save money, time, and effort. The use of rice straw could reduce the use of sawdust and increase the productivity of white oyster mushrooms.

We investigated short- and long-term effects of rice straw application to paddy soils on crop growth, mineralization of straw N, and soil N supply under flooded and upland conditions. For investigating the short-term effects, pot and laboratory incubation experiments with 15N-labeled rice straw were conducted. In the incubation experiment over 90 days at 25 °C, 23–24% of N in the 15N-labeled rice straw was mineralized under upland and flooded conditions. In the pot experiment, 13–14% of N in the 15N-labeled rice straw was taken up by maize (Zea mays L.) and paddy rice (Oryza sativa L.). These values were greater than those with the 15N-labeled rice straw compost, however, N derived from the rice straw contributed to soil inorganic N and N uptake by crops only a small extent under flooded and upland conditions. Continuous application of rice straw (5 Mg ha−1 year−1 for 12 years) increased soil total N and total C. Nitrogen uptake by paddy rice, upland rice and maize in the field experiment, and inorganic N in the incubation experiment over 91 days at 25 °C increased in the soil with the continuous rice straw application compared with the soil without rice straw application. Gross rates of N mineralization under flooded conditions also increased by the continuous rice straw application. The degrees of increase in N uptake by paddy rice and upland crops and increase in gross rates of N mineralization by continuous rice straw application were higher than the degree of increase in total N in the soil. Continuous application of rice straw contributed to the improvement of soil fertility and the promotion of growth and N uptake by paddy rice and upland crops, while short-term effects on dry matter production and N uptake by crops were little. The appropriate timing of rice straw incorporation and combination use of rice straw and mineral fertilizer would improve the short-term effectiveness.

Biofuel production from lignocellulosic biomass such as rice straw becomes increasingly important in light of the needs for alternative fuels, sustainable economy, and environmental mitigation. This research is aimed at the development of new pretreatment technologies that will enable faster and more efficient degradation and conversion of lignocellulosic biomass into biofuel and other valuable products. Laboratory experiments were performed to investigate the pretreatment of rice straw with three alkali chemicals, including lime (Ca(OH)2), sodium hydroxide (NaOH), and potassium hydroxide (KOH). Orthogonal experimental design was used to determine the effects of three key factors (alkali chemical, alkali loading and temperature) that influence the pretreatment efficiencies. Alkali loading was tested at 2%, 6%, and 10% levels (based on dry biomass), and temperature was 20, 35, and 50C. The treatment time was 24 hours. The lignin removal, solids and sugar loss from the rice straw as a result of alkali pretreatment were measured. The pretreated straw was evaluated for biodegradability using enzymatic hydrolysis and anaerobic digestion. The results showed that NaOH treatment at 20C and with 10% chemical loading achieved the highest lignin removal of 35%. Statistical analysis showed that NaOH was the most effective chemical for lignin removal. Temperature ranging from 20C to 50C had no significant effect on lignin removal. With 23 day anaerobic digestion at mesophilic temperature of 35C, rice straw pretreated with 10% NaOH at 20C for 24 hours had the biogas yield of 0.6 L /g VS, 50% higher than the biogas yield from untreated straw. After enzymatic hydrolysis using cellulase from Trichoderma reesei ATCC 26921 and cellobiase from Aspergillus niger, the pretreated straw had the reducing sugar yield of 298 mg glucose/g VS, 185% higher than the untreated straw.

In Egypt rice cultivation in the river Nile Delta produces large amounts of rice straw as residue. Assuming that about 20% were used for other purposes about 2.8 Mt were left on the fields for burning within a period of 30 days to get quickly rid of leftover debris. The resulting emissions give a significant contribution to the air pollution called the Black Cloud. A suitable technology for the use of rice straw is an important contribution to reduce air pollution and gives a significant contribution to use biomass as renewable energy in Egypt. Based on that fact rice straw was studied as possible feedstock for the BIOLIQ process. The BIOLIQ process which is under development at the Forschungszentrum Karlsruhe (Germany) is a two-step process for the production of chemicals, fuels or electricity from lignocellulosic biomass with high ash content. In the first step the biomass is liquefied by fast pyrolysis. The pyrolysis char and the pyrolysis liquid are mixed to form a slurry. In the second step the pumpable slurry is used to produce syngas in a pressurised entrained flow gasifier. After gas cleaning and conditioning the syngas is used for the production of fuels, chemicals and electricity as by-product. In this work rice straw is studied as a possible feedstock for fast pyrolysis and slurry preparation. First the Egyptian rice straw was chemically characterised. Ultimate analysis of rice straw showed an elemental composition of 47,8% C, 6,0 %H and 45,3% O, (daf). According to the elemental composition the HHV was calculated to be about 18,1 MJ/Kg (Dulong) up to 20,5 MJ/kg (Ebeling). Based on the experimental HHV 15,3 MJ/kg (rice straw dry, 18% ash) the HHV on a moisture and ash free basis was calculated to be 18,7 MJ/kg. According to the literature the lignin, hemicellulose and cellulose contents of rice straw were about 12%, 28% and 60%, respectively. The rice straw was chopped and sieved (2 mm sieve) and most of the straw dust was separated before use. The pyrolysis process was studied on laboratory and PDU (process demonstration unit) scale. During pyrolysis lignin gave the main contribution to the char formation. TGA pyrolysis experiments showed about 60% of volatiles, 20% fixed carbon and 20% of ash on the average (dry). These results were very close to the results of fast pyrolysis experiments in a PDU with a twin-screw reactor. The chlorine was focussed in the pyrolysis char up to a temperature of ∼500°C. If the pyrolysis temperature exceeded 500°C the chlorine was released and its concentration in the chars decreased. The outside of the rice straw stems was completely covered with silica forming a close protection layer. SEM-studies show that the pyrolysis took place only at the inner sides of the stems. Therefore rice straw had to be chopped very carefully in order to brake up short stem pieces and to split them up. Additionally the SEM pictures confirmed the volatility of chlorine at temperatures above 500°C. Condensate viscosity, char porosity and the particle size spectrum as well as slurry production techniques play an essential role for slurry preparation and result in practicable condensate/char-weight ratio variations between about 3 to 1.3 for worse and unfavourable situations. With a special colloid mixer, a robust tool well known for the preparation of a very homogeneous cement grout it was possible to prepare a pumpable char/tar mixture with a high mixing ratio of almost 50% by weight.

This laboratory and field experiment were to assess the use of rice straw (RS); biochar rice straw- compost (BRS); rice straw- ammonium (RSN) and compost (ST) at 0, 12.5 and 25 Mg ha-1 on the development of wheat plants and improve a sandy soil's productivity. In winter seasons of 2017/2018 – 2018/2019 at the Ismailia Agricultural Research Station. In laboratory experiment soil treatments incubation and studied OC%, SP, FC, PWP and AW. In field experiment i.e. yield, yield components, N, K and P, pH, ECe and bulk density at ripeness's stage, times application before sowing (Ap1) and with sowing (Ap2) on wheat and study design a split block. Results the end of incubation period, losses of OC% about 21.2, 7, 20.6 and 32.1% due to 25 Mg ha-1 for RS, BRS, RSN and ST respectively, we found a positive effect of rice straw and compost on SP, FC, PWP and AW. In field experiment the highest relative increase over control due to 25 Mg ha-1 BRS, RSN and ST at Ap1 for plant height were 36.58, 68.95 and 74.73 % where dry weight/plant were 35.00 48.44 and 69.06 %, grain yield were 45.13, 58.70 and 69.32%. 100 seed weight and N K P content significant affected by BRS, RSN and ST respectively. Soil available N, K and P due to all organic treatments. Soil EC was improved by RSN and ST, addition of ST impact on pH and bulk density was slightly reduced, but BRS was due to a slight increase.

Environmental sustainability of bioethanol production from rice straw in India: A review

Biogas production can supplement the renewable energy target of the world. For this abundantly available agricultural waste like wheat and rice straw can be used. Biogas generation using this waste will curb the stubble burning incidences, reduce greenhouse gases, enhance farmer’s income, and strengthen the energy security of many countries. The recalcitrant nature of rice straw is a barrier to its hydrolysis, which is a prerequisite of the anaerobic digestion (AD) process. Alkaline, electro-hydrolysis, and a combination of both pretreatment (alkaline electrohydrolysis) methods are undertaken in the present study. Batch reactors at ambient temperature were used for AD of rice straw at different inoculums to substrate ratios (ISR) of 0.5, 0.75, and 1.0 to observe the effect on biogas/methane yield. Among these, a higher amount of biogas was obtained for ISR of 0.5 in all sets of experiments. The combined pretreatment method yielded biogas of 315.9 mL/gVS (equivalent to methane of 167.4 mL/gVS). For pretreat-ed rice straw by electro-hydrolysis, alkaline, and combined (alkaline and electro-hydrolysis) respectively, the methane yields were 7.03, 18.13, and 49.82% higher than untreated rice straw. The biogas had approximately 53% of methane content. The use of rice straw for biogas production may prove a viable alternative for clean and sustainable energy. In the studies, a first-order kinetic model is found to fit better the experimental results.

SUMMARY The decomposition of rice and barley straw saccharides under field conditions was well represented by the first‐order kinetics model of Y t = C 1 e − k 1 t + C 2 e − k 2 t , where Y t is the remaining amount at time t, k 1 and k 2 are the decomposition rate constants (time −1 ) for the labile fraction ( C 1 ) and the non‐labile fraction ( C 2 ), respectively. About 82% of the total saccharide content of the rice straw was in the labile fraction with a rate constant 0.64–0.81, the values for the barley straw being 70–92% and 0.50–0.61, respectively. The non‐labile fraction appeared to persist for a long time, with a half‐value period of 9–59 months. Barley straw and its saccharides decomposed at a slower rate than rice straw. Much more favourable initial decomposition was observed in a paddy field than in an upland field. Mannose, fucose, rhamnose and ribose were synthesized in parallel with the flush of decomposition of straw saccharides.

The effect of urease enzyme on treatment time and the nutritive value of straw treated with ammonia as urea

The efficacy of two low cost substrates viz., rice straw and sugarcane bagasse was evaluated in a periphyton-based semi-intensive carp polyculture system through 120 days growth trial in 80 m2 outdoor cemented tanks manured with biogas slurry @ 20, 000 L/ha/yr and stocked with catla, rohu, mrigal and common carp @ 10, 000 fry/ha where treatment without any substrate served as control. The fish were fed with formulated supplementary diet (rice bran and mustard meal in 1: 1 ratio @ 10, 5 and 1.5% of its body weight (BW) for the first, second and the following months, respectively. The water quality and plankton (phytoplankton and zooplankton) production were similar in all the treatments. Chlorophyceae was the dominant group followed by cyanophyceae, bacillariophyceae and euglenophyceae among the phytoplankton while rotifers and crustaceans (copepods and cladocerans) dominated among the zooplankton in both the substrate treatments. Though higher (P<0.05) periphyton DM per unit area was recorded in rice straw substrate but periphyton ash and ash free DM content was similar in both the substrates. Growth response of fish to both the substrates varied with species. Catla, rohu and common carp attained higher (P<0.05) final BW (66.0±1.20, 39.20±1.13 and 167.10±4.80 g, respectively) with sugarcane bagasse substrate as compared to control group (54.90±1.89, 33.70±0.63 and 137.90±6.38 g, respectively) reared in tanks without any substrate. However, use of rice straw as substrate showed higher (P<0.05) final body weight was recorded only in case of common carp (165.40±4.76 g). Flesh quality of fish also appeared to vary with species in different treatments. Among all the species, a higher (P<0.05) total protein and ash content (on wet basis) was found in case of rohu with both rice straw (13.90±0.48% and 1.40±0.04%, respectively) and sugarcane bagasse (13.57±0.45 and 1.31±0.07%, respectively) substrates as compared to control (11.62±0.17 and 0.94±0.09%, respectively). This study revealed potential of using sugarcane bagasse as periphytic substrate in carp culture.

Rising concern about environmental protection has demanded prompt researchers’ attention towards alternative renewable energy sources. Thus, biofuel production with biodegradation of crop straws through anaerobic digestion has attracted the attention of the scientific community. However, the lignocellulosic nature of rice straw poses resistance to its disintegration through anaerobic digestion. Aiming to optimize the concentration of sodium hydroxide pretreatment of rice straw for efficient biogas production this study was conducted. For this purpose, the pretreatment was done on rice straw with different concentrations of sodium hydroxide at about 25 °C temperature for 24 hours before subjecting it to anaerobic digestion for biogas production. The 6% sodium hydroxide pretreated rice straw was observed to be resulting in the highest cumulative biogas production which was found to be 56.3% higher than untreated rice straw. In the kinetic study of biogas production, 6% NaOH pretreated rice straw shows the highest biogas production potential at the highest rate of 15.8496 ml/day with a minimum lag period of 0.6758. The experimental study and kinetic study results represent that 6% NaOH pretreated rice straw has the highest biogas production.

The major drawbacks of biofuel production at the commercial level are its low yield, nonavailability of feedstock, feedback inhibition, presence of inhibitory pathways in various organisms, and biofuel intolerance of organisms. The present review focuses on the implications of the CRISPRCas9 mediated gene editing tool to alter the genome of bacteria, algae, fungi, and higher plants for efficient biofuel production. Gene knockout and gene cassette insertions employing CRISPR-Cas9 in Saccharomyces cerevisiae and Kluyveromyces marxianus have resulted in enhanced production of bioethanol and 2-Phenyl ethanol in these organisms, respectively. Genomes of several bacterial strains were also modified to enhance ethanol and butanol production in them. CRISPR-Cas9 modification of microalgae has demonstrated improved total lipid content, a prerequisite for biofuel production. All over, CRISPR-Cas9 has emerged as a tool of choice for engineering the genome and metabolic pathways of organisms for producing industrial biofuel. In plant-based biofuel production, the biosynthetic pathways of lignin interfere with the satisfactory release of fermentable sugars thus hampering efficient biofuel production. CRISPR-Cas9 has shown a promising role in reducing lignin content in various plants including barley, switchgrass, and rice straw.