Sustainable lignocellulose fractionation by integrating p-toluenesulfonic acid/pentanol pretreatment with mannitol for efficient production of glucose, native-like lignin, and furfural.

A new cutting-edge lignocellulose fractionation technology for the co-production of glucose, native-like lignin, and furfural was introduced using mannitol (MT)-assisted p-toluenesulfonic acid/pentanol pretreatment, as an eco-friendly process. The addition of optimized 5% MT in pretreatment enhanced the delignification rate by 29% and enlarged the surface area and biomass porosity by 1.07-1.80 folds. This increased the glucose yield by 45% (from 65.34 to 94.54%) after enzymatic hydrolysis relative to those without MT. The extracted lignin in the organic phase of pretreatment exhibited ß-O-4 bonds (61.54/100 Ar) properties of native cellulosic enzyme lignin. Lignin characterization and molecular docking analyses revealed that the hydroxyl tails of MT were incorporated with lignin and formed etherified lignin, which preserved high lignin integrity. The solubilized hemicellulose (96%) in the liquid phase of pretreatment was converted into furfural with a yield of 83.99%. The MT-assisted pretreatment could contribute to a waste-free biorefinery pathway toward a circular bioeconomy.

One-step lignocellulose fractionation using acid/pentanol pretreatment for enhanced fermentable sugar and reactive lignin production with efficient pentanol retrievability.

To valorize whole lignocellulosic biomass, this study proposed a biphasic solvent system using dilute acid (DA)/pentanol pretreatment. Effects of the key factors, i.e., temperature and pentanol concentration, on aspen were evaluated. Under identified optimal pretreatment conditions (160 °C, 60% pentanol), 85% and 91% of lignin and hemicellulose were solubilized in separate organic and liquid phases, respectively, while 91.1% of cellulose was retained in solid fraction. Enzymatic digestibility efficiency of pretreated cellulose was âˆ¼ 6.4-times higher than that of untreated biomass. Notably, excellent pentanol recovery rates were obtained after four-times recycling (84%) with great cellulose digestibility (81%) and delignification (71%) performance. The recovered lignin contained low levels of contaminated sugars (<1%), while it could stabilize and protect high amounts of ß-O-4 bonds. Besides, high phenolic OH content was found in lignin, which could be utilized for lignin-based biomaterials. Therefore, DA/pentanol pretreatment is an innovative promising technology for lignocellulosic valorization towards biorefinery.

A new cutting-edge review on the bioremediation of anaerobic digestate for environmental applications and cleaner bioenergy.

Circular agriculture and economy systems have recently emerged around the world. It is a long-term environmental strategy that promotes economic growth and food security while reducing negative environmental consequences. Anaerobic digestion (AD) process has a high contribution and effective biodegradation route for bio-wastes valorization and reducing greenhouse gases (GHGs) emissions. However, the remaining massive digestate by-product contains non-fermented organic fractions, macro and/or micro-nutrients, heavy metals, and metalloids. Direct application of digestate in agriculture negatively affected the properties of the soil due to the high load of nutrients as well as the residuals of GHGs are emitted to the environment. Recycling and valorizing of anaerobic digestate is the main challenge for the sustainable biogas industry and nutrients recovery. To date, there is no global standard process for the safe digestate handling. This review described the biochemical composition and separation processes of anaerobic digestate. Further, advanced physical, chemical, and biological remediation's of the diverse digestate are comprehensively discussed. Moreover, recycling technologies such as phyco-remediation, bio-floc, and entomoremediation were reviewed as promising solutions to enhance energy and nutrient recovery, making the AD technology more sustainable with additional profits. Finally, this review gives an in-depth discussion of current biorefinery technologies, key roles of process parameters, and identifies challenges of nutrient recovery from digestate and prospects for future studies at large scale.

Sustainable microalgal biomass valorization to bioenergy: Key challenges and future perspectives.

The global trend is shifting toward circular economy systems. It is a sustainable environmental approach that sustains economic growth from the use of resources while minimizing environmental impacts. The multiple industrial use of microalgal biomass has received great attention due to its high content of essential nutrients and elements. Nevertheless, low biomass productivity, unbalanced carbon to nitrogen (C/N) ratio, resistant cellular constituents, and the high cost of microalgal harvesting represent the major obstacles for valorization of algal biomass. In recent years, microalgae biomass has been a candidate as a potential feedstock for different bioenergy generation processes with simultaneous treating wastewater and CO2 capture. An overview of the appealing features and needed advancements is urgently essential for microalgae-derived bioenergy generation. The present review provides a timely outlook and evaluation of biomethane production from microalgal biomass and related challenges. Moreover, the biogas recovery potential from microalgal biomass through different pretreatments and synergistic anaerobic co-digestion (AcoD) with other biowastes are evaluated. In addition, the removal of micropollutants and heavy metals by microalgal cells via adsorption and bioaccumulation in their biomass is discussed. Herein, a comprehensive review is presented about a successive high-throughput for anaerobic digestion (AD) of the microalgal biomass in order to achieve for sustainable energy source. Lastly, the valorization of the digestate from AD of microalgae for agricultural reuse is highlighted.

Enhancement of biodiesel yield from a halophilic green microalga isolated under extreme hypersaline conditions through stepwise salinity adaptation strategy.

In the present study, a halophilic microalgal species was isolated from a hypersaline lagoon with salinity average of 45.3‰ and identified as Dunaliella salina KSA-HS022. It was further cultivated at a salinity range of 50-250‰, applied directly to batch cultures or through stepwise increase in a semi-continuous culture. The later showed the highest biomass productivity of 0.191 g L-1 d-1 at 125‰, which represented 45.8% higher than the corresponding batch culture (control). Oxidative markers in the control cultures were significantly higher than those of the adapted culture, confirming reduction of oxidative stress by adaptation. In addition, stepwise adaptation showed the highest lipid productivity of 56.5 mg L-1 d-1 at 150‰ (39.9% higher than the corresponding control), which resulted in the highest fatty acid methyl esters productivity. Moreover, stepwise increase of salinity up to 150‰ enhanced the biodiesel characteristics, offering a new route for enhanced biodiesel production at extraordinary salinity levels.

Enhancement of biogas production from rape straw using different co-pretreatment techniques and anaerobic co-digestion with cattle manure.

The present study investigated the possibility of valorizing rape straw through anaerobic digestion and the possibility of improving biomethane yield by pretreatment with H2SO4, combined H2SO4 with steam explosion (SE) and SE combined with superfine grinding (SFG). To evaluate the pretreatment method efficiency, several analytical techniques were applied. Additionally, the performance of co-digesting of cattle manure (CM) with pretreated rape straw (PRS) at different ratios was evaluated. The results showed that combined pretreatment could dissolve the lignocellulosic fiber structure, which positively stimulated methane yield. The highest cumulative CH4 yield (CMY) of 305.7 mLg-1VS was achieved by combined SE at 180 °C for 5 min with SFG, which was 77.84% higher than the untreated. The CMY was further improved by 11.4-59% higher than the control (CM) using co-digestion. This study confirmed that, under optimal parameters of AD, pretreatment with SEG180 could significantly boost the CMY from co-digestion of CM and PRS.

Biomass briquetting reduces the energy loss during long-term ensiling and enhances anaerobic digestion: A case study on rice straw.

The present study evaluated the impact of briquetting prior to ensiling on rice straw characteristics and anaerobic digestion performance. Ensiling for 10 months significantly reduced cellulose, hemicellulose and lignin of the uncompressed straw by 50.3%, 61.6% and 34.6%, respectively. However, increase of briquetting ratio enhanced the cellulose and hemicellulose contents at different ensiling times. In addition, increasing of ensiling time significantly reduced the biogas yield, while the highest cumulative biogas yield of 313.8 L kg-1 VS was obtained from rice straw ensiled for 7 days at 1:6 briquetting ratio. Interestingly, the maximum biogas productivity of 1:6 briquetted straw after 10 months ensiling was 17.7% higher than that of the uncompressed straw ensiled for 7 days. Thus, briquetting prior to ensiling is a favorable approach to reduce the mass loss for enhanced biogas yield and energy recovery.

Different effects of ozone and aqueous ammonia in a combined pretreatment method on rice straw and dairy manure fiber for enhancing biomethane production.

Low digestibility of lignocellulosic feedstock is the most important limitation for biogas production. The synergistic effects of ozone and aqueous ammonia (OSAA) on different types of lignocelluloses including rice straw and dairy manure fiber were investigated. OSAA significantly increased biogas production of rice straw by 114.2%-172.8% when compared with using ozonation alone, while increased by 6.2%-8.8% with manure fiber. OSAA pretreatment increased biogas production of manure fiber by 55.3%-103.6% when compared with soaking aqueous ammonia (SAA) alone, while by 28.8%-39.9% with rice straw. The specific effects of pretreatment time on anaerobic digestion of manure fiber differed noticeably from those on rice straw. Ozonation time had a major function for pretreatment of manure fiber via the OSAA process, but SAA pretreatment time was more important than that for rice straw.

Biorefining of rice straw by sequential fermentation and anaerobic digestion for bioethanol and/or biomethane production: Comparison of structural properties and energy output.

Three routes; namely R1 representing direct anaerobic digestion (AD), R2 representing enzymatic hydrolysis followed by fermentation, distillation, then AD, and R3 representing AD of fermentation broth without distillation; of alkali pretreated rice straw were investigated. Results showed that sequential fermentation and AD effectively enhanced fibers degradation with significant changes in the composition. Fermentation through R2 resulted in ethanol yield of 87.4 g kg-1 dry straw. Maximum biogas yields of 286.9, 233.3 and 372.4 L kg-1 VS were recorded by AD for R1, R2 and R3 after reaching the steady state at 36, 24 and 33 days, respectively. However, biogas produced through R3 showed the highest significant biomethane content (79.3%) which represented 15 and 8% higher than that of R1 and R2, respectively. Therefore, the highest bioenergy output and energy conversion efficiency of 10.58 GJ ton-1 and 75.6%, respectively, were obtained through R3 demonstrating the positive effect of fermentation prior to AD.

Hesperidin attenuates brain biochemical changes of irradiated rats.

PURPOSE: The purpose of this study was to evaluate the efficacy of hesperidin (HES), a citrus flavonoid, against the severity of biochemical disorders in the cerebral hemispheres of irradiated rats. MATERIAL AND METHODS: Hesperidin (50 mg/kg body weight) was administered to male albino rats via gavages during 10 successive days before whole body exposure to gamma rays (5 Gy) and during 14 days after irradiation. The animals were sacrificed on the 14th day post-irradiation. RESULTS: The results demonstrated a significant increase of the levels of thiobarbituric acid reactive substances (TBARS), protein carbonyls (CO), and advanced oxidation protein products (AOPP), associated to significant decreases of total superoxide dismutase (tSOD) and catalase (CAT) activities, and reduced thiols content in the cerebral hemispheres of irradiated rats indicating oxidative stress. A significant decrease of the serotonin (5-HT), dopamine (DA), norepinephrine (NE) and epinephrine (EPI) contents and a significant increase of the activity of monoamine oxidase (MAO) were recorded, also, indicating alterations in the metabolism of monoamines. Moreover, a significant decrease of the activities of glutamate dehydrogenase (GDH) and creatine phophokinase (CPK), and a significant increase of calcium ions (Ca (+2)) levels were recorded in the mitochondria. Hesperidin treatment has significantly attenuated oxidative stress, monoamines alterations and mitochondrial damage in the cerebral hemispheres of irradiated rats. CONCLUSION: It could be concluded that hesperidin might attenuate the severity of radiation-induced biochemical disorders in brain tissues.