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With the recent revolution in the green economy, agricultural solid waste resource utilization has become an important project. A small-scale laboratory orthogonal experiment was set up to investigate the effects of C/N ratio, initial moisture content and fill ratio (vcassava residue: vgravel) on the maturity of cassava residue compost by adding Bacillus subtilis and Azotobacter chroococcum. The highest temperature in the thermophilic phase of the low C/N ratio treatment is significantly lower than the medium and high C/N ratios. The C/N ratio and moisture content have a significant impact on the results of cassava residue composting, while the filling ratio only has a significant impact on the pH value and phosphorus content. Based on comprehensive analysis, the recommended process parameters for pure cassava residue composting are a C/N ratio of 25, an initial moisture content of 60%, and a filling ratio of 5. Under these conditions, the high-temperature conditions can be reached and maintained quickly, the organic matter has been degraded by 36.1%, the pH value has dropped to 7.36, the E4/E6 ratio is 1.61, the conductivity value has dropped to 2.52 mS/cm, and the final germination index increased to 88%. The thermogravimetry, scanning electron microscope, and energy spectrum analysis also showed that the cassava residue was effectively biodegraded. Cassava residue composting with this process parameter has great reference significance for the actual production and application of agriculture. [ABSTRACT FROM AUTHOR]

The survival and performance of vegetables in the field production cycle depend on the seedling quality and, in turn, the substrate. Asparagus is not part of the vegetables cultivated in Boa Vista-RR, so basic studies, such as substrate preparation, are necessary. Thus, the present study aimed to evaluate the effect of six substrates on the initial development of asparagus seedlings in two growth phases. For this, an experiment was set up in an entirely randomized design, with treatments arranged in a factorial scheme (6 x 2). In the initial phase of the study, six compositions were evaluated with the following materials: (S - soil; M - goat manure; C - root and shoot of cassava) in two sowing seasons. The S40M30C30 substrate stands out by having better particle distribution, 79% ranging between 2 and 0.5 mm and 21% less than 0.5 mm, wet bulk density of 0.823 g cm-3 and dry of 0.726 g cm-3, relative humidity of 7.1% and particle density of 1.88 g cm-3. This substrate also provided higher growth variables than the others and is suitable for growing asparagus in its initial phase. Asparagus seeds should be sown in a substrate prepared with soil and organic waste (goat manure and residue from the shoot and roots of cassava) at least seven days before sowing.

The experiment aimed to explore the effect of different microorganisms on nutrient composition, fermentation quality and in vitro digestibility of fermented cassava residue. There are seven treatments in test, and each treatment has three replicates. CK (control group) was added with distilled water, and each test group was added with Lactobacillus brucelli (LAB), Candida tropicalis (CT), Bacillus subtilis (BS), Lactobacillus brucelli+Candida tropicalis (G1), Lactobacillus brucelli+Bacillus subtilis (G2), Candida tropicalis+Bacillus subtilis (G3) according to 5% of dry weight of cassava residue. Ferment for 15 d at room temperature and away from light. The results showed that compared with control group, the dry matter recovery rate, neutral detergent fiber and acid detergent fiber content of the cassava residue fermentation in each test group were significantly reduced (P<0.05), the crude protein content of each test group significantly increased (P<0.05). Compared with control group, the pH value wood of each test group significantly decreased (P<0.05), and the acetic acid content was significantly increased (P<0.05), and the pH value of G3 group was the lowest, the lactic acid content was the highest, and the sensory score was the highest. Compared with control group, the 24 h dry matter degradation rate and 24 h neutral detergent fiber degradation rate of each test group were significantly increased (P<0.05). The study indicates that the quality of cassava dregs can be improved effectively by using Candida tropicalis+Bacillus subtilis microbial combination to ferment cassava residue. [ABSTRACT FROM AUTHOR]

Lignocellulose (LC) is a natural polymer material that holds immense potential for various applications. However, extracting LC from biomass wastes with high-starch content has been challenging due to low selectivity and yield. In this study, LC was prepared from cassava residue (CR) via a combination of mechanical activation pretreatment and a citric acid (CA)-enhanced ternary deep eutectic solvent (TDES) consisting of choline chloride (ChCl), lactic acid (LA), and CA. The mechanical activation reduces the size of CR, greatly promoting the removal ability for starch, lignin and hemicellulose using TDES, and thus improving yield and selectivity of LC through this method. The CA esterified LC to prevent its excessive hydrolysis and increased a significantly higher LC content (82.52 wt%) compared to mechanical activation only and DES without CA, increasing by 6.97 times and 1.26 times, respectively. The extraction temperature significantly affected the structure, composition, thermal stability of LC and the properties of recovered TDES. The LC extracted at 90 °C (LC-90) had the highest cellulose content (82.52 wt%), crystallinity index (44.82 %), and higher degradation temperature (339.7 °C). The properties of the recovered TDES and extraction mechanism were analyzed. This study provides a strategy for the high-value utilization of biomass waste. [Display omitted] [ABSTRACT FROM AUTHOR]

The preparation of valuable chemicals by catalytic fast pyrolysis (CFP) is a promising and environmentally-friendly approach for the selective upgrading of waste cassava residue (CR). This work systematically investigated the conversion mechanism and kinetic characteristics of CR pyrolysis over Ga-modified hollow ZSM-5, for the purpose of enhancing aromatics production. The hollow configuration significantly regulated the structural characteristics of ZSM-5, thus facilitating the diffusion, deoxygenation, and aromatization of pyrolysis intermediates. The incorporation of Ga species and generated Brønsted acid sites remarkably accelerated the reaction rate and suppressed the carbonization at high temperatures, through enhancing the end scission of starch and cellulose components. With the aid of 5Ga/ZSM-H, the relative content of aromatics achieved 95.4% at 700 °C, and still maintained over 92.5% even after 5 cycles. The ring-opening and retro-aldol degradation were identified as crucial steps for the production of ketones and aldehydes separately, which were further transformed into hydrocarbon pools by deoxygenation and subsequently converted into aromatics via Diels-Alder reaction. Kinetic analysis demonstrated that the use of 5Ga/ZSM-H lowered the average activation energy of CR pyrolysis by 14.8%, particularly for the initial pyrolysis stage. Moreover, the plausible mechanism for aromatics formation from Ga-modified hollow ZSM-5 catalyzed CR pyrolysis was proposed. [Display omitted] • The hollow configuration effectively improved the mass transfer of intermediates. • 5Ga/ZSM-H gave aromatics content of 95.4% and exhibited good recyclability. • Ga species facilitated the CR decomposition via activating connection bonds. • 5Ga/ZSM-H remarkably lowered the activated energy at the initial stage. [ABSTRACT FROM AUTHOR]

The enzymatic hydrolysis of cassava residue treated by a hot water (HW) pretreatment, an extreme-low acid (ELA) pretreatment, and an alkaline hydrogen peroxide (AHP) pretreatment was investigated. The results showed that the ELA pretreatment dissolved greater xylan and glucose quantities than the HW pretreatment under the same conditions, and the xylan and glucan contents of the pretreated substrate affected the subsequent cellulase hydrolysis. The conversion to glucose by cellulase hydrolysis reached 81.4% after the HW pretreatment, while the glucose yields under the ELA and AHP pretreatment conditions were 78.3% and 71.0%, respectively. In addition, supplementation with xylanase improved cellulase efficiency. At an equal xylanase dosage, a higher glucose yield (i.e., 91.3%) was achieved for the ELA-pretreated substrates that contained a lower xylan content. Xylanase supplementation in the AHP pretreatment had little effect on the glucose conversion. Finally, X-ray diffraction studies showed that the HW and ELA pretreatments increased the cassava residue crystallinity, while the AHP pretreatment had little effect. [ABSTRACT FROM AUTHOR]

Cassava residue was liquefied by using ethylene glycol (EG), ethylene carbonate, propylene carbonate and polyethylene glycol (molecular weight: 400 g/mol) as the liquefaction reagent respectively at the temperature of 130–170 °C with sulfuric acid as the catalyst. The influences of liquefaction parameters, such as the type of liquefaction reagents, mass ratio of EG/cassava residue, liquefaction temperature and time on the properties of the products were discussed. The optimum liquefaction conditions were obtained when the mass ratio of EG/cassava residue was 6:1 (w/w), the liquefaction temperature was 150 °C, the liquefaction time was 3 h and the mass fraction of concentrated sulfuric acid/EG was 2.5wt%. The hydroxyl numbers and residue content of the liquefied products at optimal conditions were 1 137 mgKOH/g and 0.43%, respectively. FT-IR spectrum showed that the liquefaction product of cassava residue was polyether polyol and could be used to prepare polyurethane material or alkyd resins. [ABSTRACT FROM AUTHOR]

Abstract In order to maximize value and minimize waste, carboxymethyl cellulose (CMC) and carboxymethyl starch (CMS) was synthesized via solvent method using cassava residue as raw material. The alkalization time, etherification temperature, the amounts of reactants and the alkali boiling pretreatment which influence the carboxymethylation degree of cassava residue were investigated. Additionally, we studied the variation of Cobb values and ring crush index of the corrugated medium after surface sizing with the optimized carboxymethylated cassava residue. The optimum sample and starch with the mass ratio of 1:10 were mixed to prepare the sizing agent with a concentration of 6%, which was sized on the corrugated medium with a basis weight of 112 g/m2. The Cobb value and ring crush index of the sized-corrugated medium was 26.3 g/m2 and 8.1 N·m/g, which increased by 36.3% and 32.8% respectively compared with the reference one sized with pure starch solution. Highlights • The cellulose and starch in cassava residue are simultaneously modified by carboxymethylation. • The Cobb value of the paper sized with the modified carboxymethylated cassava residue increased by 36.3%. • The ring crush compression strength after sizing increased by 32.8%. [ABSTRACT FROM AUTHOR]

Large quantities of organic dyes are discharged into the environment, causing serious damage to the ecosystem. Therefore, it is urgent to develop inexpensive adsorbents to remove organic dyes. A novel cellulose-based aerogel (MPPA) with 3D porous structure was prepared by using cassava residue (cellulose) as basic construction blocks, doping ferroferric oxide (Fe 3 O 4) for magnetic separation, and applying polyethyleneimine (PEI) as functional material for highly efficient and selective capture of Congo red (CR). MPPA exhibited porous network structure, numerous active capture sites, nontoxicity, high hydrophilicity, and excellent thermal stability. MPPA showed superior adsorption property for CR, with an equilibrium adsorption capacity of 2018.14 mg/g, and still had an adsorption property of 1189.31 mg/g after five recycling procedures. In addition, MPPA has excellent selectivity for CR in four binary dye systems. The adsorption behavior of MPPA on CR was further explored using a multilayer adsorption model, EDR-IDR hybrid model and AOAS model. Electrostatic potential and independent gradient models were used to further verify the possible interaction between MPPA and CR molecules. In conclusion, MPPA is a promising adsorbent in the field of treating anionic dyes. [Display omitted] • A novel magnetic cassava pomace based aerogel was designed and synthesized. • MPPA can effectively removes Congo red from wastewater. • In vitro cytotoxicity tests were used to validate the safety of MPPA. • Density functional theory was applied to visualise the adsorption interactions. • The phenomenological models proposed new insights into sorption mass transfer. [ABSTRACT FROM AUTHOR]

In the present study, vanadium modified ZSM-5 catalysts (denoted as xV/ZSM-5) were applied for the fast pyrolysis of cassava residues. Systematical structural characterizations were carried out to reveal the basic characteristics of as-prepared xV/ZSM-5. Remarkably, the incorporation of vanadium species endowed the catalysts with large amounts of Brønsted and Lewis acid sites, thus facilitating the formation of aromatics via catalytic cleavage, dehydration, decarbonylation, decarboxylation, cyclization, and aromatization. Among the as-prepared xV/ZSM-5, 3V/ZSM-5 was found to be much more efficient in the fast pyrolysis of cassava residues into aromatics. The total yield of aromatics was up to 22.63 wt% at 750 ℃ with a heating rate of 10 ℃/ms, and the corresponding apparent activation energy of 211.9 kJ/mol was attained. The recycling experiments demonstrated that the vanadium modified ZSM-5 catalysts presented good thermal stability and could be reused for several cycles. Furthermore, plausible reaction mechanism for the fast pyrolysis of cassava residues over vanadium modified ZSM-5 was discussed in depth. • V-modified ZSM-5 were developed for cassava residues pyrolysis. • The yield and selectivity of aromatics achieved 22.63 % and 95.7 % respectively. • V-modified ZSM-5 zeolites sustained good activity after four cycles. [ABSTRACT FROM AUTHOR]

A mathematical description was developed for production of saccharides and fermentation inhibitors during the hot-compressed water pretreatment of cassava residue. Pretreatment was conducted at 150 °C, 160 °C, 170 °C, and 180 °C, and reaction times ranged from 0 to 70 min. The formation of saccharides and four main inhibitors (furfural (F), hydroxymethylfurfural (HMF), acetic acid, and formic acid) were studied. A model for predicting the concentrations of F and HMF (CF and CHMF, respectively) as functions of H+ concentration was established. Furthermore, kinetic models were built after introducing the hydrogen ion concentration index mi. Hydrogen ion concentration had a dramatic effect on the dissolution of pentosan but did not greatly affect the dissolution of hexosan or the degradation of hexose or pentose. Additionally, the activation energies for the formation of pentose or hexose were lower than the degradation energies. The coefficients of determination (R2) of the kinetic models for predicting the yield of the four compounds (pentose, hexose, furfural, and HMF) were higher than 0.923. These kinetic models provided a theoretical foundation and technical support for controlling the production of the main carbohydrates and fermentation inhibitors.

The feeding value of replacing concentrate with cassava (Manihot esculenta) residue in the feed of Holstein cows was confirmed using an in vitro gas test. The treatments consisted of 0% (control, CON), 5%, 10%, 15%, 20%, 25%, and 30% inclusion of cassava residue in fermentation culture medium composed of buffer solution (50 mL) and filtrated rumen fluid (25 mL). The parameters analyzed included the kinetics of gas production and fermentation indexes. Forty-eight hours later, there were no significant differences on in vitro dry matter disappearance (IVDMD), pH, and microbial crude protein (MCP) content among treatments (p > 0.05). However, the “cumulative gas production at 48 h” (GP48), the “asymptotic gas production” (A), and the “maximum gas production rate” (RmaxG) all increased linearly or quadratically (p < 0.01). The GP48 was significantly higher in the 25% treatment compared to the other treatments, except for the 30% (p < 0.01). The A was significantly larger in the 25% treatment compared to the other treatments, except for the 20% and 30% (p < 0.01). The RmaxG was distinctly larger in the 25% treatment compared to other treatments (p < 0.01); moreover, the “time at which RmaxG is reached” (TRmaxG) and the “time at which the maximum rate of substrate degradation is reached” (TRmaxS) were significantly higher in the 25% treatment than the CON, 20%, and 30% treatments (p < 0.01). Additionally, the content of ammonia-N (NH3-N) in all treatments showed linearly and quadratically decreases (p < 0.01), whereas total volatile fatty acid (VFA), iso-butyrate, butyrate, and iso-valerate contents changed quadratically (p = 0.02, p = 0.05, p = 0.01, and p = 0.02, respectively); all of these values peaked in the 25% treatment. In summary, the 25% treatment was associated with more in vitro gas and VFA production, indicating that this cassava residue inclusion level may be used to replace concentrate in the feed of Holstein cows. However, these results need to be verified in vivo.

This study was conducted to investigate the effect of using cassava residue to replace crushed maize on in vitro fermentation characteristics of dairy cows at mid-lactation and provide guidance for its utilization. The study included seven treatments with four replicates, which used 0% (control, CON), 5%, 10%, 15%, 20%, 25% and 30% cassava residue to replace crushed maize (air-dried matter basis), respectively. A China-patented automated trace gas recording system was used to perform in vitro gas tests; rumen fluids were collected from three dairy cows at mid-lactation. In vitro dry matter digestibility (IVDMD), gas production (GP), pH, ammonia–N (NH3-N) and microbial protein (MCP) content were analyzed after in vitro incubating for 3, 6, 12, 24 and 48 h, respectively; volatile fatty acid (VFA) content was analyzed after in vitro culturing for 48 h. The results showed that with the increase of substitution ratio of cassava residue, the asymptotic gas production (A) increased quadratically (p < 0.05), cumulative gas production at 48 h (GP48) and the maximum rate of substrate digestion (RmaxS) increased linearly and quadratically (p < 0.05), the time at which the maximum gas production rate is reached (TRmaxG) increases linearly (p < 0.05). In addition, asymptotic gas production in 30% was significantly higher than the other treatments (p < 0.05), RmaxS in 25% and 30% were significantly higher than CON, 5% and 10% (p < 0.05). In addition, with the increase of substitution ratio of cassava residue, when in vitro cultured for 6 h and 12 h, NH3–N content decreased linearly and quadratically (p < 0.05). NH3–N content in 30% was significantly lower than the other treatments except 20% and 25% (p < 0.05) after cultivating for 6 h. Moreover, the content of iso-butyrate, iso-valerate, valerate and total VFA (tVFA) decreased linearly and quadratically (p < 0.05), acetate decreased quadratically (p < 0.05) with the increase of substitution ratio of cassava residue. In conclusion, when the cassava residue substitution ratio for crushed maize was 25% or less, there were no negative effects on in vitro ruminal fermentation characteristics of dairy cows at mid-lactation.

Because of its non-toxic, pollution-free, and low-cost advantages, environmentally-friendly packaging is receiving widespread attention. However, using simple technology to prepare environmentally-friendly packaging with excellent comprehensive performance is a difficult problem faced by the world. This paper reports a very simple and environmentally-friendly method. The hydroxyl groups of cellulose nanofibrils (CNFs) were modified by introducing malic acid and the silane coupling agent KH-550, and the modified CNF were added to cassava starch as a reinforcing agent to prepare film with excellent mechanical, hydrophobic, and barrier properties. In addition, due to the addition of malic acid and a silane coupling agent, the dispersibility and thermal stability of the modified CNFs became significantly better. By adjusting the order of adding the modifiers, the hydrophobicity of the CNFs and thermal stability were increased by 53.5% and 36.9% ± 2.7%, respectively. At the same time, the addition of modified CNFs increased the tensile strength, hydrophobicity, and water vapor transmission coefficient of the starch-based composite films by 1034%, 129.4%, and 35.95%, respectively. This material can be widely used in the packaging of food, cosmetics, pharmaceuticals, and medical consumables.

Cassava starch factory residue (CSFR) is an attractive lignocellulosic material for bioethanol production because it is one of the most abundant renewable resources. The purpose of this work was to investigate the technical feasibility of converting CSFR into fermentable sugars using 12 different pretreatment methods. The yields of monosaccharides, oligosaccharides, and total sugars present in the hydrolysates obtained from the different pretreatment methods were examined by transferring the solid organic matter present to a liquid phase. We found that pretreatment with a dilute acid was superior to both alkaline and hot water pretreatment methods, while combined chemical‐enzymatic pretreatment was superior to single enzymatic pretreatment. More specifically, treatment with a dilute acid was conducive to the formation of monomeric sugars, whereas single enzyme pretreatment and high‐temperature alkaline pretreatment methods were conducive to the formation of oligomeric sugars. Pretreatment with 0.5% (w/v) HNO3 (160 °C, 10 min) gave the highest total monosaccharide concentration (i.e., 25,827 mg/L) with a yield of 30.99%, whereas hemicellulose (45 U/g CSFR) + cellulose (120 U/g CSFR) pretreatment gave the highest total oligosaccharide concentration (i.e., 22,152 mg/L) with a yield of 26.69%. Finally, pretreatment with 1% (w/v) H2SO4 (121 °C, 40 min) + hemicellulose (120 U/g CSFR) + cellulose (120 U/g CSFR) gave the highest total sugar concentration (i.e., 43,196 mg/L) with a yield of 51.84%. © 2018 American Institute of Chemical Engineers Environ Prog, 38: 624–629, 2019 [ABSTRACT FROM AUTHOR]

Highlights • Degradation performance of cellulose was about 2 time higher than hemicellulose by thermophiles. • The two-stage UASB process could provide high degradation performance of added cassava residue. • The H 2 UASB unit gave higher degradation performance than the CH 4 UASB unit. Abstract In this research, the separate production of hydrogen (H 2) and methane (CH 4) from cassava wastewater with added cassava residue was investigated using a two-stage upflow anaerobic sludge blanket (UASB) system under thermophilic temperature (55 °C) in a continuous mode of operation and steady state condition. The two-stage UASB system was operated under an optimum chemical oxygen demand (COD) loading rate of 10.29 kg/m3d (based on the total volume of both bioreactors) of the cassava wastewater with different concentrations of added cassava residue. The recycle ratio of the effluent from the second bioreactor to the feed flow rate was fixed at 1:1 (v/v). In addition, the solution pH in the first bioreactor was controlled at 5.5, while that in the second bioreactor was not controlled. Under the optimum cassava residue concentration of 1200 mg/L, the produced gas from the first bioreactor contained 42.3% H 2 , 55% carbon dioxide (CO 2) and 2.70% CH 4 , while that from the second bioreactor contained 70.5% CH 4 , 28% CO 2 and 1.5% H 2. Apart from a high H 2 and CH 4 production performance (45.2 and 150% improvement, respectively, as compared to the system without added cassava residue) under the optimum cassava residue concentration (1200 mg/L) and the controlled COD loading rate (10.29 kg/m3d) of the cassava wastewater, the degradation performance of cellulose and hemicellulose were 41% and 22%, respectively, for the first bioreactor and 23% and 11%, respectively, for the second bioreactor. The digestibility of the cassava residue at thermophilic operation was higher than that at mesophilic temperature. [ABSTRACT FROM AUTHOR]

Abstract: Cassava residue is the solid waste generated from the production of tapioca starch and has considerable reuse value. In this study, cassava residue was examined as a hydrolysate for ethanol production, and the effects of different liquid phase oxygen transfer coefficients (kLα) on the production of ethanol from cassava residue hydrolysates were studied. Based on analyses of dissolved oxygen and a set of optimal experimental schemes, dynamic models of cell growth and product synthesis were optimized, using MATLAB. When kLα was 85, fermentation was optimal; the ethanol titer reached 23.14 g L−1 at 72 h and cell growth reached 6.23 g L−1 at 96 h. Additionally, experiments were performed according to the dissolved oxygen curve obtained under these conditions. The resulting ethanol titer was 24.43 g L−1 (72 h) and the cell mass was 6.45 g L−1 (96 h). [ABSTRACT FROM AUTHOR]

Cellulose, hemicellulose, and lignin interweave to form a dense network structure that makes lignocellulosic biomass difficult to degrade. Tween-80 is a non-ionic surfactant that can be used to promote microbial growth and increase the rate of microbial metabolism in compost. In this study, different doses of Tween-80 were presented as additives in the composting process to reduce the composting time and improve the maturity of the compost. The composting trial was conducted in a 10 L reactor for 46 days. The results showed that the addition of the chemical surfactant Tween-80 increased the temperature in the composting process and could effectively promote the degradation of lignocellulose and reduce phytotoxicity. During the composting process, the microbial population showed exponential growth followed by a gradual decline. At the end of composting, Tween-80 added at 0.35% reduced the C/N ratio to 9.61, much lower than that of the CK group at 12.3. Meanwhile, the degradation rates of cellulose and hemicellulose increased by 2.76% and 7.86%, respectively. Toxicity experiments on compost products also proved that the seed germination index of compost with 0.35% Tween-80 addition increased to 98.57%, which is 17.33% higher than that without the addition. FT-IR and TG experiments showed that the addition of Tween-80 could effectively accelerate the composting process and promote the rapid maturation of the heap. In conclusion, the addition of 0.35% Tween-80 was most conducive to promoting the rapid decomposition of organic matter in cassava residue compost and improving the maturity of the heap. [Display omitted] • Surfactant additions ranging from 0.05% to 0.40% were able to promote humidity. • Decomposition of lignocellulose was promoted by the addition of 0.35% Tween-80. • Surfactants enhance the decomposition of organic matter by microorganism. [ABSTRACT FROM AUTHOR]

Simultaneous saccharification and fermentation (SSF) is an attractive process configuration for bio-ethanol production. Further reductions in process cost of SSF are expected with the use of waste agricultural or industrial materials as feedstock. In the current study, two industrial lignocellulosic wastes, cassava residues (CR) and furfural residues (FR), were combined during SSF for ethanol production due to their value-added applications and positive environmental impacts. After CR were liquefied and saccharified, saccharification liquid was added to SSF of FR. The effect of substrate fractions was investigated in terms of ethanol yield, byproduct concentration and the number of yeast cells. Besides, a natural surfactant, Gleditsia saponin, was added to investigate the effect of FR lignin on SSF with 20% substrate concentration. The results showed that increasing the ratio of CR/FR improved the ethanol yield and that the ethanol yield was also increased gradually by increasing the substrate concentration from 6% to 12%. A high ethanol concentration of 36.0 g/L was obtained under the condition of CR:FR = 2:1 with 12% substrate concentration, reaching 71.1% of the theoretical yield. However, Gleditsia saponin did not affect the ethanol yield, indicating the insignificant effect of lignin in SSF with low lignin content in the reaction system.

To investigate the removal of Congo red (CR) from an aqueous solution using cassava residue, a novel process incorporating adsorption and in vivo decolorization was proposed. The conditions and characteristics of CR adsorption on cassava residue were investigated by batch adsorption experiments. Langmuir and pseudo-second order models were found to fit well with the data of equilibrium adsorption and kinetics adsorption, respectively. The adsorption was affected considerably by the adsorbent (cassava residue) dosage and CR concentration. The maximum adsorptive capacity was 59.2 mg/g (mCR/mcassava residue), calculated by the Langmuir model. Then, CR-loaded cassava residue was further decolorized via an in vivo process by Trametes sp. SYBC-L4. The laccase produced by Trametes sp. SYBC-L4 effectively decolorized CR, which was revealed by native polyacrylamide gel electrophoresis. The moisture content affected the performance of in vivo decolorization considerably. Decolorization of 81.6 ± 2.4% was achieved under the conditions of pH 5.5, temperature 30 °C, and moisture content of 60% after 16 days of cultivation. Moreover, analyses of Fourier transform infrared spectroscopy and scanning electron microscopy indicated that the carbonyl (C=O), hydroxyl (-OH), and amino (-NH) groups in cassava residue were the potential adsorption sites for interaction with CR and that the structure of cassava residue was modified in the process of in vivo decolorization.

The two-stage hythane fermentation of cassava residue low in protein, rich in iron, and deficient in nickel and cobalt, resulted in failure after long-term operation, showing a radical decrease in methane production along with an increase in volatile fatty acids (VFAs) accumulation in the second stage. Based on the gap between theoretical demand and existing content of nutrients, the effect of their additions on hythane fermentation was validated in the repeated batch experiment and continuous experiment. The proliferation of hydrolysis bacteria, acidogens, and hydrogen producing bacteria and methanogens was guaranteed by sufficient N (0.7 g/L), S (30 mg/L), Ni (1.0 mg/L), and Co (1.0 mg/L), and the metabolism of a sustainable hythane fermentation was recovered. In this optimal nutrient combination of above trace elements, the highest hythane yield (426 m 3 hythane with 27.7% of hydrogen from 1 ton of cassava residue) was obtained. [ABSTRACT FROM AUTHOR]

Co-fermentation of carbon-rich and nitrogen-rich feedstocks with suitable carbon to nitrogen (C/N) ratios is commonly considered as a viable way to enhance biological hydrogen production. In this study, cassava residue (C/N ratio = 29.1) and swine manure (C/N ratio = 8.6) were mixed and subject to microwave-assisted acid hydrothermal pretreatment. The resulting hydrolysates were used for subsequent dark hydrogen fermentation. However, the mixture with a C/N ratio of 15.1 resulted in the lowest hydrogen yield potential of 107.8 mL/g volatile solid (VS). Comparatively, the mono-fermentation of cassava residue exhibited the highest hydrogen yield potential of 145.6 mL/g VS and a peak hydrogen production rate of 8.2 mL/g VS/h. The modified Gompertz model was employed for kinetic analysis, and suggested that the lag-phase time and peak time of hydrogen fermentation exhibited a significantly positive linear correlation with increased C/N ratios. Reducing sugars analysis indicated that pretreatment of mixed cassava residue and swine manure led to a decrease of total sugar yield by 7.2–10.5% due to the Maillard reactions between hydrolyzed sugars and amino acids. A reaction mechanism based on glucose and arginine was proposed to elucidate the Maillard interactions between carbonyl group ( C O) and amino group ( NH 2 ), which was responsible for the overall sugar loss. The findings of this study suggested that pretreatment for mixed carbohydrate-rich and protein-rich feedstocks needs to be optimised to avoid unexpected fermentable sugars loss. [ABSTRACT FROM AUTHOR]

Cassava residue was proposed as a raw material for the production of ethylene glycol (EG) via a one-pot hydrothermal reaction in the present study. Various mixed catalysts consisting of activated carbon supported Ru (Ru/AC) and a tungsten species were used for the conversion of cassava residues, and the effects of various reaction conditions on the catalytic performance were investigated. When the reaction was carried out at 245 °C for 60 min, the Ru/AC-HWO mixed catalyst showed a EG yield of 53.1 % with a total polyols yield of 80 %, which was confirmed to be the most active among the prepared catalysts. The excellent catalytic performance using cassava residue as the feedstock mainly resulted from a high content of carbohydrates and a low amount of lignin in cassava residues. Furthermore, the Ru/AC-HWO catalyst also showed reasonable stability during the hydrothermal conversion of cassava residues for EG production. [ABSTRACT FROM AUTHOR]

A novel adsorbent, magnetic cassava residue microspheres, was prepared by using an inverse emulsion method with cassava residue used as raw material, acrylic acid and acrylamide used as grafted monomer, and methyl methacrylate (MMA) used as dispersing agent; and characterized by scanning electron microscope, transmission electron microscope, particle size analyzer, Fourier transform infrared spectroscopy and vibrating sample magnetometer. The results showed that the acrylic acid and acrylamide was successfully introduced into the adsorbent, and exhibited a good dispersion with uniform particle size distribution. The average particle size of the magnetic cassava residue microspheres was 206 nm, and the saturation magnetization is 11.9 emu/g. The dispersing agent MMA formed a thin film on the microspheres surface, resulting in good sphere shape and promoting the dispersion of microspheres. When used to remove Cu (II) from an aqueous solution, the adsorption capacity of magnetic cassava residue microspheres was remained at 110.5 mg/g after 6 times used. The adsorption process was conformed to a Frundlich isotherm and a pseudo-second-kinetic-order model, which was spontaneous and endothermic in nature. [ABSTRACT FROM AUTHOR]

In the present study, selective transformation of waste cassava residues into aromatics via catalytic pyrolysis over as-prepared La and P modified ZSM-5 was systematically investigated, especially in the aspects of product regulation and kinetic analysis. Comprehensive physicochemical characterizations were undertaken for unveiling the essential structural properties of La and P modified ZSM-5. The introduction of La and P species significantly enriched the Lewis and Brønsted acid sites in ZSM-5, thus facilitating the directional pyrolysis of waste cassava residues into aromatics. Higher apparent activation energy for aromatics formation from waste cassava residues pyrolysis in the presence of La and P modified ZSM-5 might be due to the fact that the catalytic pyrolysis belonged to diffusion-controlled gas-solid reaction. In comparison with that of the parent ZSM-5, LaP 2 /ZSM exhibited better performance towards aromatics formation in waste cassava residues pyrolysis, wherein the relative content of aromatics reached 83.3% at a temperature of 650 °C. Gratifyingly, the relative content of aromatics was increased to 90.5% for the catalytic pyrolysis of acid pretreated cassava residue, in the case of LaP 1 /ZSM catalyst. [Display omitted] • Relative content of aromatics achieved 90.5% from cassava residue pyrolysis. • La and P modification of ZSM-5 promoted cassava residue pyrolysis into aromatics. • Cassava residue pyrolysis belonged to diffusion-controlled gas-solid reaction. [ABSTRACT FROM AUTHOR]

Cassava residue from breweries is being generated in large amounts in Guangxi Province of China, and this has potential to cause serious environmental problems if disposed of improperly. Two-stage anaerobic fermentation is a promising method for the treatment of such residue. In this study, the effect of feed to microbes ratio (F/M ratio) on the anaerobic acidogenic fermentation of cassava residue was studied to determine the optimal F/M ratio and to maximize the performance in a subsequent methanogenic stage. The experiments were carried out at the F/M ratios of 0.2, 0.61, 1.02, 2.05, 3.07, and 4.09 g cassava-TS/g sludge-VSS in six laboratory-scale, completely stirred, tank reactors (CSTR) at mesophilic temperature (35°C). An F/M ratio of 1.02 g cassava-TS/g sludge-VSS resulted in the highest solid removal efficiency and VFA/COD ratio, while starch removal efficiency was still near 100 percent, and acidification was relatively high. As a further benefit, the VFA distribution was more suitable for the subsequent methanogenic fermentation stage.

The long-term performance of the thermophilic hydrogen fermentation of cassava residue was studied in a continuous stirred tank reactor by mixed culture. The effect of different hydraulic retention times (30 days, 6 days and 3 days) on the three metabolic steps of hydrolysis, acidogenesis and hydrogen production was investigated. The highest hydrogen yield, 2.38 mmol H 2 /g dry cassava residue, was achieved at an HRT of 30 days, while acetic acid (2.14 g/L) and butyric acid (2.85 g/L) were the majority of liquid by-products. It was confirmed that the addition of a nitrogen supplement ensured the stable operation of the thermophilic dark fermentation of hydrogen. The energy recovery calculations indicated that it is possible to stably operate the hydrogen fermentation of cassava residue with positive energy recovery efficiency and the highest net energy was 540.5 MJ/ton at an HRT of 30 days. [ABSTRACT FROM AUTHOR]

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The physicochemical properties of cassava residues subjected to microwave (or steam)-heated acid pretreatment (MHAP or SHAP) were comparatively investigated to improve fermentative hydrogen and methane cogeneration. The hydrogen yield from cassava residues with MHAP and enzymolysis was higher (106.2 mL/g TVS) than that with SHAP and enzymolysis (102.1 mL/g TVS), whereas the subsequent methane yields showed opposite results (75.4 and 93.2 mL/g TVS). Total energy conversion efficiency increased to 24.7%. Scanning electron microscopy images revealed MHAP generated numerous regular micropores (∼6 μm) and SHAP generated irregular fragments (∼23 μm) in the destroyed lignocellulose matrix. Transmission electron microscopy images showed SHAP generated wider cracks (∼0.2 μm) in delaminated cell walls than MHAP (∼0.1 μm). X-ray diffraction patterns indicated MHAP caused a higher crystallinity index (33.00) than SHAP (25.88), due to the deconstruction of amorphous cellulose. Fourier transform infrared spectroscopy indicated MHAP caused a higher crystallinity coefficient (1.20) than SHAP (1.12). [ABSTRACT FROM AUTHOR]

[Display omitted] • PEI modified porous magnetic microspheres prepared from cassava residue were prepared. • Cd(II) adsorption amount was increased from 29.2 mg/g to 42.6 mg/g after PEG2000 addition. • It is easily separated after adsorption in aqueous solution and is recyclable. • Cd(II) adsorption process on PEI/HMPCR was controlled by chemical adsorption and diffusion. Polyethyleneimine modified magnetic porous cassava residue microspheres (PEI/HMPCR) were prepared by reverse emulsion polymerization with pretreated cassava residue (PCR) as raw material, modified by linear polyethyleneimine (PEI) and polyethylene glycol (PEG2000) as the porogen, which was applied for the adsorption remove of the cadmium ions (Cd(II)) from the simulated wastewater. The results showed the specific surface area increased from 8.08 m2/g to 17.06 m2/g for the magnetic microspheres of cassava residue (HMPCR) after the PEG2000 was added, and the PEI was successfully graft-modified onto the PCR surface. However, After the PEI was added, the specific surface area was reduced to 14.86 m2/g with a pore diameter size of 14.24 nm. X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FT-IR) analysis demonstrated the Cd(II) was adsorption mainly with the –NH and –NH 2 groups on the PEI/HMPCR surface, and the PEI/HMPCR adsorbent exhibited superparamagnetic with a saturation magnetic susceptibility of 9.5 emu/g. Furthermore, the effects of the pH, amounts of PEG2000 and PEI, and optimize conditions on the adsorption process were also studied. The adsorption results showed the adsorption capacity of Cd(II) on the PEI/HMPCR increased from 29.1 mg/g to 42.6 mg/g compared with the sample without porogen. The maximum adsorption capacity was 143.6 mg/g at the pH of 6.0, temperature of the 35 °C, and a Cd(II) initial concentration of 250 mg/L. The addition of PEI provided more –NH and –NH 2 groups as adsorption sites for Cd(II). The thermodynamics and kinetic studies showed the adsorption of Cd(II) on PEI/HMPCR could be fitted by a Langmuir isothermal and a pseudo-second-order model, and a possible reaction mechanism was proposed. [ABSTRACT FROM AUTHOR]

Simple Summary: Cassava (Manihot esculenta) residue is a by-product of cassava processing. Although it contains residual nutrients, it is highly perishable. Decayed cassava residue pollutes the environment and leads to major losses in feed. If cassava residue could be utilized as a dairy cow feedstuff, these problems could be solved. Our study showed that cassava residue is a good alternative to concentrate in the feed of Holstein cows. Furthermore, our data demonstrate the efficacy of the application of cassava residue as a feed for dairy cows and could help solve the shortage of feed resources in China. The feeding value of replacing concentrate with cassava (Manihot esculenta) residue in the feed of Holstein cows was confirmed using an in vitro gas test. The treatments consisted of 0% (control, CON), 5%, 10%, 15%, 20%, 25%, and 30% inclusion of cassava residue in fermentation culture medium composed of buffer solution (50 mL) and filtrated rumen fluid (25 mL). The parameters analyzed included the kinetics of gas production and fermentation indexes. Forty-eight hours later, there were no significant differences on in vitro dry matter disappearance (IVDMD), pH, and microbial crude protein (MCP) content among treatments (p > 0.05). However, the "cumulative gas production at 48 h" (GP48), the "asymptotic gas production" (A), and the "maximum gas production rate" (RmaxG) all increased linearly or quadratically (p < 0.01). The GP48 was significantly higher in the 25% treatment compared to the other treatments, except for the 30% (p < 0.01). The A was significantly larger in the 25% treatment compared to the other treatments, except for the 20% and 30% (p < 0.01). The RmaxG was distinctly larger in the 25% treatment compared to other treatments (p < 0.01); moreover, the "time at which RmaxG is reached" (TRmaxG) and the "time at which the maximum rate of substrate degradation is reached" (TRmaxS) were significantly higher in the 25% treatment than the CON, 20%, and 30% treatments (p < 0.01). Additionally, the content of ammonia-N (NH3-N) in all treatments showed linearly and quadratically decreases (p < 0.01), whereas total volatile fatty acid (VFA), iso-butyrate, butyrate, and iso-valerate contents changed quadratically (p = 0.02, p = 0.05, p = 0.01, and p = 0.02, respectively); all of these values peaked in the 25% treatment. In summary, the 25% treatment was associated with more in vitro gas and VFA production, indicating that this cassava residue inclusion level may be used to replace concentrate in the feed of Holstein cows. However, these results need to be verified in vivo. [ABSTRACT FROM AUTHOR]

In the present study, thermal decomposition behaviors and kinetics for fast pyrolysis of acid/alkali pretreated waste cassava residues were investigated. The results demonstrated that chemical pretreatments apparently loosened the compact structure of cassava residue and benefited to the sufficient contact with acid/alkali sites. Acid/alkali pretreatments enriched the product varieties and had remarkable influence on the adjustment of product formation. Particularly, the pyrolysis behavior obviously shifted to low-temperature zones for pretreated samples. Low heating rate significantly promoted the formation of anhydrosugars with 27% levoglucosan produced, while elevating heating rate contributed to furfural production. Some oxygenated-chemicals, such as acetic acid, hydroxyacetone and 4-hydroxydihydrofuran-2(3H)-one, were apparently formed in the presence of alkali metal. Noticeably, the generation of most gaseous products was restrained for those acid-impregnated cassava residues. Moreover, kinetic study suggested that the apparent activation energy for waste cassava residue pyrolysis was significantly lowered, further verifying the positive role of chemical pretreatments. • Pyrolysis behavior shifted to low-temperature zone for pretreated CR. • Activation energy was lowered to 30.4 kJ/mol for alkali treated CR. • Around 33.6% anhydrosugars were obtained for CR pyrolysis at low heating rate. [ABSTRACT FROM AUTHOR]

• A bolt-on cassava ethanol scenario was developed by cellulase addition. • The cellulase addition realized in-situ cassava cellulose conversion to ethanol. • The cellulase addition decreased glycerol biosynthesis in cassava ethanol process. • Slurry viscosity impacted substantially on ethanol fermentation. • Low slurry viscosity contributed to the decrease of glycerol titer. Cassava is a widely used raw material for bioethanol production. In addition to starch, there is about 4–5 % (w/w) cellulose in cassava tuber, which is not utilized in current cassava ethanol process. Here, a bolt-on cellulase-added ethanol process was developed to realize the in situ conversion of cellulose in cassava tuber. As a result, the final ethanol titer increased from 127.94 g/L to 131.84 g/L, with 57.17 % cellulose and some recalcitrant starch additionally hydrolyzed. Moreover, the titer of glycerol, a main by-product of ethanol fermentation, decreased from 10.78 g/L to 9.95 g/L and the ratio of ethanol/glycerol increased from 11.87 to 13.25. To investigate the reason for the decreased glycerol production in this cellulase-added cassava ethanol process, the effect of medium viscosity on glycerol production was extensively investigated, which indicated, for the first time, that the reduction of glycerol biosynthesis was due to decreased viscosity aroused by the cellulase addition. Overall, this cellulase-added cassava ethanol process not only realized the conversion of cassava cellulose and higher ethanol titer, but also reduced the production of glycerol. [ABSTRACT FROM AUTHOR]

Simple Summary: Cassava processing and utilization generates many byproducts, such as cassava residue. On one hand, this residue still contains many nutrients like starch, fiber and minerals. On the other hand, it pollutes the environment if not be utilized properly. Lactating dairy cows need to control the body weight for smooth calving, but too much high energy feed material like maize can influence their lipid metabolism. Cassava residue may be a good option for them since it can be used not only as roughage, but also can provide energy for dairy cows. Therefore, this study was conducted to investigate the effect replacing high energy feedstuff crushed maize with cassava residue on in vitro fermentation characteristics of dairy cows in mid-lactation. This may help provide further in vivo tests with data support, which finally, could alleviate feed shortages, reduce environmental pollution and improve economic benefits of dairy farming. This study was conducted to investigate the effect of using cassava residue to replace crushed maize on in vitro fermentation characteristics of dairy cows at mid-lactation and provide guidance for its utilization. The study included seven treatments with four replicates, which used 0% (control, CON), 5%, 10%, 15%, 20%, 25% and 30% cassava residue to replace crushed maize (air-dried matter basis), respectively. A China-patented automated trace gas recording system was used to perform in vitro gas tests; rumen fluids were collected from three dairy cows at mid-lactation. In vitro dry matter digestibility (IVDMD), gas production (GP), pH, ammonia–N (NH3-N) and microbial protein (MCP) content were analyzed after in vitro incubating for 3, 6, 12, 24 and 48 h, respectively; volatile fatty acid (VFA) content was analyzed after in vitro culturing for 48 h. The results showed that with the increase of substitution ratio of cassava residue, the asymptotic gas production (A) increased quadratically (p < 0.05), cumulative gas production at 48 h (GP48) and the maximum rate of substrate digestion (RmaxS) increased linearly and quadratically (p < 0.05), the time at which the maximum gas production rate is reached (TRmaxG) increases linearly (p < 0.05). In addition, asymptotic gas production in 30% was significantly higher than the other treatments (p < 0.05), RmaxS in 25% and 30% were significantly higher than CON, 5% and 10% (p < 0.05). In addition, with the increase of substitution ratio of cassava residue, when in vitro cultured for 6 h and 12 h, NH3–N content decreased linearly and quadratically (p < 0.05). NH3–N content in 30% was significantly lower than the other treatments except 20% and 25% (p < 0.05) after cultivating for 6 h. Moreover, the content of iso-butyrate, iso-valerate, valerate and total VFA (tVFA) decreased linearly and quadratically (p < 0.05), acetate decreased quadratically (p < 0.05) with the increase of substitution ratio of cassava residue. In conclusion, when the cassava residue substitution ratio for crushed maize was 25% or less, there were no negative effects on in vitro ruminal fermentation characteristics of dairy cows at mid-lactation. [ABSTRACT FROM AUTHOR]

Because of its non-toxic, pollution-free, and low-cost advantages, environmentally-friendly packaging is receiving widespread attention. However, using simple technology to prepare environmentally-friendly packaging with excellent comprehensive performance is a difficult problem faced by the world. This paper reports a very simple and environmentally-friendly method. The hydroxyl groups of cellulose nanofibrils (CNFs) were modified by introducing malic acid and the silane coupling agent KH-550, and the modified CNF were added to cassava starch as a reinforcing agent to prepare film with excellent mechanical, hydrophobic, and barrier properties. In addition, due to the addition of malic acid and a silane coupling agent, the dispersibility and thermal stability of the modified CNFs became significantly better. By adjusting the order of adding the modifiers, the hydrophobicity of the CNFs and thermal stability were increased by 53.5% and 36.9% ± 2.7%, respectively. At the same time, the addition of modified CNFs increased the tensile strength, hydrophobicity, and water vapor transmission coefficient of the starch-based composite films by 1034%, 129.4%, and 35.95%, respectively. This material can be widely used in the packaging of food, cosmetics, pharmaceuticals, and medical consumables. [ABSTRACT FROM AUTHOR]