Alkaline Pretreatment Methods Research Articles

SURFACE FUNCTIONALIZATION OF KENAF FIBERS WITH LAUROYL CHLORIDE: EFFECTS OF ALKALINE PRETREATMENT METHOD

Surface functionalization of cellulose fibers is the current focus of research seeking to develop composite materials for various applications. One reason is the low compatibility of natural cellulose-based fibers with thermoplastic matrices for the production of wood-plastic composites. In this research, kenaf fibers (KF) were esterified with lauroyl chloride. Before the esterification reaction, two alkaline pretreatment methods were used: Bain-Marie at low temperature, and at high temperature and pressure in the digester. SEM results showed a smoother surface morphology after esterification. ATR-FTIR results confirmed the substitution of hydroxyl groups of cellulose with lauroylate functional groups. Increasing the carbon content in EDX spectroscopy further supported the successful esterification of kenaf fibers, which is in accordance with ATR-FTIR findings. Based on ATR-FTIR and EDX results, the Bain-Marie pretreatment method was more effective for the esterification reaction. According to the XRD results, the crystallinity index of the fibers slightly increased after esterification reaction. However, the fibers pretreated in the digester had a higher crystallinity index, which was related to efficient removal of amorphous regions due to higher temperature and pressure used in the digester process. This research showed that alkaline pretreatment in Bain-Marie was more effective for the surface functionalization of cellulose fibers than the digester process. These results can be applied in future research works for esterification of cellulose fibers.

Improving the dyeability of ramie fibre by sequential alkaline and alcohol pretreatments

The high crystallinity of ramie fibre poses challenges in achieving optimal dyeing performance, such as reduced dye exhaustion. To enhance the dyeing capabilities of ramie fibre, several alterations were experimented with, such as caustic mercerization using a NaOH solution. However, because of the high NaOH concentration, removing the NaOH residue from inside the fibre becomes challenging. Herein, the present research aims to enhance the dyeing efficiency of ramie fibre by using sequential alkaline and alcohol pretreatment methods to reduce NaOH usage, accordingly relieving the wash process stress. The preliminary screening findings have revealed that iso-butanol is the most suitable alcohol solvent for modifying ramie fibres after treating it with NaOH solution since it leads to higher dye exhaustion (E%, 95.7%), dye fixation rate (F%, 88.2%), total dye fixation efficiency (T%, 84.4%), and K/S values (41.4). After that, the orthogonal array experimental scheme (L16) was applied to optimize dyeing performance. The NaOH usage was decreased to 160 g/L, the treating time was reduced to 3 min, and the dyeing performance of ramie fibre treated under the optimum conditions was better than that of a caustically mercerized one. It was determined that the NaOH concentration factor had the most contribution, accounting for 75.34% of the observed effects. The NaOH solution temperature factor followed closely behind, contributing 22.69%. Additionally, using analytical methods such as XRD, FTIR, TG, and SEM confirmed that the sequential treatment with the optimum conditions altered the structural behaviour of the original ramie fibre, which performances were similar to the mercerized ramie fibre. The barium value of sequentially iso butanol solvent treated fibre showed a greater level (213) compared to caustic mercerized fibre (179), indicating a significant advantage of mercerization performance was achieved. This advantage may be linked to improved colourfastness and handling qualities. Furthermore, the breaking force of both ramie fabrics was increased after the alkaline treatment and the sequential alkaline and iso-butanol treatment.

Effect of Acids and Alkaline Pretreatment of Used Tea Waste Powder under Microwave-Assisted Pretreatment

There are numerous methods to enhance the quality of cellulose for efficient and sustainable fuel production, the acid and alkaline pretreatment methods have become increasingly popular due to their accessibility and affordability. These methods are typically used to eliminate lignin, disrupt the cellulose crystalline structure, and reduce its rigidity. This study focuses on the use of pretreatment with four different types of acids (Hydrochloric Acid, Phosphoric Acid, Acetic Acid, and Sulfuric Acid) and four types of alkaline (Calcium Hydroxide, Sodium hydroxide, Potassium Hydroxide, and Ammonium Hydroxide) were used to soak the used tea waste powder as a raw material under microwave-assisted pretreatment. The effectiveness of acid and alkaline pretreatment methods under microwave heating on used tea waste powder was evaluated through infrared analysis. The experiments were conducted at varying microwave temperatures (100–200 °C), reaction times (2–7 min), and with a 2 g doses of used tea waste powder in 100 mL of diluted acid, and 5% of alkaline solution. The weight loss of liquid and solid samples after acid and alkaline pretreatment under the aid of microwave pretreatment were calculated. FTIR analysis results showed a significant improvement in the characteristics of the treated samples compared to the untreated used tea waste powder.

Production of sustainable biodiesel from alkaline pretreated dairy effluent using Yarrowia lipolytica

AbstractBiodiesel (BD) has grown in popularity over the last few years due to the global energy crisis, in addition to the depletion of reserves and the shortage of oil. The current study investigates the utilization of dairy effluent as a substratum for Yarrowia lipolytica, an oily yeast employed in biofuel generation. The dairy effluent has high biochemical oxygen demand, dissolved solids and, low pH. In this study, based on carbon nitrogen ratio (C/N), the alkaline pretreatment method (KOH 5%) was adopted to grow Y. lipolytica in dairy effluent. After 5 days of growth at 29°C, pH 6.9 (initial pH of dairy effluent), and stirring speed 120 rpm, the growth of Y. lipolytica produced 42.3 g/L biomass. Utilizing an ex‐situ transesterification method, the biomass was metamorphosed into BD. Using a modified version of Folch, Bligh, and Dyer's approach, lipid removal was done as the initial step. Moreover, the lipid was transesterified in a KOH catalyst, yielding 61% BD. Utilizing Fourier transform infrared spectroscopy analysis, the produced fatty acid methyl ester was examined.

Physical and Spectroscopic Characterization of the Microcrystalline Cellulose Derivatives from Corn Cob and Daniella Oliveri Wastes

Cellulose was extracted from wood dust waste samples of Daniella oliveri and corn cobs by acetic acid and alkaline pretreatment methods, while microcrystalline cellulose (MCC) derivative was produced by acid hydrolysis in 2 M HCl. The samples were tested for pH, moisture content, swelling capacities and ash contents. The data obtained were compared with those of commercial MCCs found in the literature. The functional groups in the microcrystalline cellulose derivatives was confirmed by the Fourier transform infrared (FTIR) spectroscopic method with characteristic absorption bands of;–OH stretching at 3416 cm-1; C-H stretching at 2918 cm-1; -OH bending at 1377 cm-1; 1159 cm-1; and C-O-C pyranose ring skeletal vibrations at 1026-1033 cm-1. The crystallinity absorption bands appeared at 1436 and 850 cm-1. The characteristic morphological features were established by scanning electron microscopy (SEM). Furthermore, the crystallinity of the microcrystalline cellulose was further confirmed using the X-ray powder diffraction (X-RD) technique, which showed three main reflections at 2θ=14.70°, 22.09°, and 34.24°.These results supported that microcrystalline cellulose derivative as cellulose I type and the acid pretreatment did not affect the structure of the MCC. The crystallinity indices were 69.3 and 73.2%, respectively. Daniella Oliveri and corn cob microcrystalline cellulose are, therefore, potential materials for further processing.

Improved Sugar Recovery of Alkaline Pre-Treated Pineapple Leaf Fibres via Enzymatic Hydrolysis and Its Enzymatic Kinetics

The biofibre complex structure in pineapple leaf fibres (PALFs) can be disrupted using the alkaline pre-treatment method with sodium hydroxide (NaOH). Nonetheless, the pre-treated structures have an impact on the bioconversion of PALFs into sugar. Thus, the impact necessitates precise reaction conditions, which are required for the enzymatic hydrolysis of PALFs. In this study, the Box–Behnken design (BBD) was utilised to achieve maximum sugar yield from PALFs. The optimised enzymatic hydrolysis conditions were 229 µg/mL of cellulase, a reaction temperature of 45 °C, and a hydrolysis time of 69 h. Resultantly, an 84% increase in sugar yield was observed, from 17.26 mg/mL to 108.74 mg/mL after the optimisation process. Moreover, a significant influence (p = 0.0009) of the enzymatic hydrolysis on hydrolysis time and temperature was observed. Additionally, the kinetic study analysis of NaOH pre-treatment and the enzymatic hydrolysis process were investigated. The kinetics of enzyme concentrations on total reducing sugar (TRS) production using an insoluble substrate were investigated based on modified Michaelis–Menten and Chrastil models. The result of the models is in good agreement with the experimental data, as the PALF hydrolysis process was reasonably well predicted. This study provides valuable information for predicting the sugar yield of the PALF bioconversion.

Enhancement of Biogas Production from Sawdust through Sustainable Alkaline and Biological Pretreatment Methods

This study aims to enhance biogas production from sawdust fibers Quercus genus (oak) using sustainable pretreatment methods. Sawdust and poultry dung (substrates) were obtained in Ogbomoso and delignification of oak samples was carried out through gravimetric method on 5, 10, and 15 days before and after digestion. Physico-chemical parameters were analyzed according to American Public Health Association (APHA) (2018) standard. Anaerobic digestion on substrates was performed through alkaline and biological pretreatment processes, biogas samples were collected and analyzed using gas chromatograph mass spectrometer. Pretreatment results for delignification of raw sawdust, alkaline and biological pretreated at 5, 10 and 15 days were; 13.5, 2.0, 1.5, 1.0 and 1.0 in mg/l. Physico-chemical results of substrates before and after digestion respectively were; pH (7.38, 8.12); alkalinity (350, 475); Nitrogen (25.5, 38.2); Phosphorus (2.67, 2.43); Carbon (192.8, 342.1); Potassium (4.1, 3.5); Phosphate (56.0, 128); Sulphate (74.0; 69.0), Calcium (12, 44); Magnesium (65, 36); Manganese (0.010, 0.031), Iron (5.2, 6.1); Zinc (25.0, 17.4); Aluminium (0.35, 0.34); Copper (2.5, 2.5); Biochemical Oxygen Demand (110, 175); Chemical Oxygen Demand (964, 1440); Carbon/Nitrogen ratio (8:1, 9:1); Volatile Solids (1216, 4560); Moisture Content (25.8%, 63.1); Total Solids (66.2%, 17.8%) and Volume of Solids (58.2%, 77.7%) in mg/l. Biogas samples composition from biological and alkaline pretreatments were: Methane (65.05%, 62.27%); and Carbon Dioxide (17.51%, 13.28%). Both pretreatment methods produced enough methane percentages, but biological pretreatment performed better. This work is applicable in sustainable biogas production for environmental protection.

Alkali pretreatment and enzymatic saccharification of blue-green alga Nostochopsis lobatus for bioethanol production

Using various Sodium hydroxide (NaOH) concentrations (0, 1, 2, and 3%), we studied the alkaline pretreatment of microalgal biomass from the blue-green alga Nostochopsis lobatus in this work. In this pretreatment stage, the entrapped polysaccharides found within the microalgae cell walls are broken down to form fermentable subunits. The selected pretreatment procedure (2% NaOH) was then followed by enzymatic saccharification for the generation of bioethanol. This pretreatment step aims to release and break down entrapped polysaccharides in the microalgae cell walls into fermentable subunits. The best result of sugars after enzyme hydrolysis was obtained in total and reducing sugars 210.22 and 98.54 g/L, respectively. In addition, Saccharomyces cerevisiae was used to ferment the hydrolysate; the highest ethanol yield was 14 g/L by 48 hours of fermentation. The alkaline pretreatment method was a promising option for pretreating microalgal biomass for bioethanol production.

Preparation of ultra-conductive bamboo cellulose fiber via a facile pretreatment

The rise of smart textiles has increased the demand for conductive fibers and the common method to realize the conductivity of fibers is to add a layer of nano metal particles via electroless plating process. However, this conventional method often requires redundant pretreatment steps and chemical regents, which hinders the large-scale production of such conductive fibers. Here, we propose a facile one-step alkaline pretreatment to prepare ultra-conductive bamboo cellulose fibers (BCFs) via in-situ reduction of silver nanoparticles (Ag NPs). The Ag-coated BCF has a conductivity of 31,800 S m−1 and a tensile strength of 492 MPa. It also has outstanding flexibility, excellent mechanical stability and washing resistance, maintaining over 96% conductivity after 1000 bending cycles and over 96% Ag retention after 50 washing times. More importantly, this alkaline pretreatment method is suitable for various biomass materials such as wood fibers, and can realize the selective conductivity of materials. This facile, green and universal pretreatment method for preparing conductive biomass fibers is expected to achieve large-scale production and be widely used in the fabrication of smart textiles.

Study of Bio-Waste Anaerobic Digestion and its Membrane Purification Technologies in Oversea: I. Malaysian Biogas Scale-up Case

The palm oil mill industry in Malaysian generates 100 million ton of palm oil mill effluent (POME) and EFB (empty fruit bunch) as byproducts annually. This study identified the location, capacity and technology of biogas refinery plants for the production of biogas from the byproducts of the Malaysian palm oil mill plant. This study investigated the production of biogas via the anaerobic co-digestion of EFB under mesophilic anaerobic condition. The results revealed that subjecting EFB to an alkaline pretreatment method enabled a high-concentration methane yield. The raw biogas obtained from the anaerobic co-digestion of POME and EFB at 1.013 bar contained 61% CH₄, 33.5% CO₂ and 180 ppm H₂S and was produced at rate of 51 - 68㎥/h. The utilization of biomethane as a bio-CNG gas has been unexplored: hence, this study investigated the purification of POME biogas into bio-CNG gas. The pretreatment of raw biogas using chelate-iron (EDTA-iron solution) process, which is the most promising technique for the removal of 99% H₂S, was employed in this study. A pilot-scale separation plant with a capacity of 20㎥/hr that utilize cellulosic spiral wound membrane (MTR, USA) for upgrading biogas to CNG fuel quality was constructed and operated at the biogas plant. The result contained 99.1% CH₄, 1.8% CO₂, 0.004% H₂O and 0.9 ppm H₂S. These results indicate that the energy contents of biogas can be significantly enhanced by upgrading it to CNG fuel.

Development of microwave-assisted alkaline pretreatment methods for enhanced sugar recovery from bamboo and corn cobs: Process optimization, chemical recyclability and kinetics of bioethanol production

The present study optimized two microwave-assisted alkaline (Na3PO4.12H2O and NaOH) pretreatment methods for the enhancement of sugar recovery from different lignocellulosic substrates (bamboo and corn cobs) with varying structural compositions. Subsequently, the chemical recyclability of the optimized alkaline pretreatments were evaluated on corn cobs. Furthermore, kinetics of microbial cell growth and bioethanol production in simultaneous saccharification and fermentation (SSF) processes were assessed. The optimized Na3PO4.12H2O pretreatment conditions resulted in the maximum reducing sugar yield (0.512 g/g) from corn cobs. Interestingly, the recyclability studies demonstrated that the NaOH-based black liquor resulted in a slightly higher average sugar yield (0.37 g/g) compared to the Na3PO4.12H2O (0.31 g/g) over three pretreatment cycles. Kinetics showed a maximum specific growth rate and maximum potential bioethanol concentration of 0.175 h−1 and 16.928 g/L respectively for the optimized NaOH pretreated corn cobs. The findings from this study provide significant knowledge enhancements pertaining to the use of gold standard, well-known NaOH methods, in addition to the emerging Na3PO4.12H2O alkaline catalyst for the pretreatment of lignocellulosic substrates with varying structural compositions. Moreover, recyclability of Na3PO4.12H2O and NaOH black liquor demonstrated the potential to reduce costs associated with the application of chemicals and fresh water in pretreatment systems. Kinetics of cell growth and bioethanol production elucidates noteworthy indices such as the maximum specific growth rate of the cells, lag time and maximum bioethanol production for lignocellulosic process development and scale-up procedures.

Pretreatment and acid hydrolysis of Omani Prosopis Juliflora wood

The objective of this research is to investigate different chemical pretreatment methods to reduce the lignin and hemicellulose content of Omani Prosopis Juliflora. The pretreated wood will then be acid hydrolyzed to convert the cellulose content to sugar. Four types of pretreatment methods were employed, namely: Alkaline pretreatment (Method I), Alkaline + Hydrogen peroxide pretreatment (Method II), Alkaline + Hydrogen peroxide + acid-chlorite pretreatment (Method III) and Alkaline + H2O2 + Acid-chlorite + bicarbonate pretreatment (Method IV). The effectiveness of each pretreatment method was assessed by measuring lignin, hemicellulose, and cellulose contents and the crystallinity index (CrI) using X-ray diffraction (XRD) analysis. The results were further assessed by taking images of the wood samples after each pretreatment step using Scanning Electron Microscope (SEM). The results showed that the CrI increased from 51% for the untreated samples to 61%, 65%, 68% and 73.2% after treating with Method I, II, III and IV, respectively. Measuring the cellulose, hemicellulose and lignin contents showed that the effectiveness of the methods in ascending order was Method I < Method II < Method III < Method IV.The pretreated wood samples by method IV were acid hydrolyzed. The effect of acid type, namely: H2SO4, HNO3, HCl and H3PO4, concentration and hydrolysis time on the %conversion of cellulose to sugar was investigated. The results revealed that H2SO4 was the most effective acid, whereas H3PO4 was the weakest. The efficiency of the tested acids follows the following order: H2SO4 > HNO3 > HCL > H3PO4. For all acids tested, the %conversion of cellulose to reducing sugar as a function of time increases linearly till t = 90 min, after which no change in the %conversion was obtained. Investigating the effect of acid concentration showed that as the concentration increases, the %conversion increases too. Upon increasing acid concentration from 1% to 10%, the %conversion increases from 12% to 62% for H2SO4, from 5% to 43% for HNO3, from 0% to 47% for HCl, and from 5% to 34% for H3PO4.

Effects of NaOH, thermal, and combined NaOH-thermal pretreatments on the biomethane yields from the anaerobic digestion of walnut shells

Anaerobic digestion (AD) of walnut shells (WS) results in only a limited biomethane yield because of their high fibre content, which ultimately represents an essentially nonbiodegradable lignocellulosic biomass. In the present study, thermal (i.e. 50-250 °C), alkaline (i.e. 1-5% w/w NaOH) and combined alkaline-thermal (i.e. 4% w/w NaOH + 150 °C thermal) pretreatment methods have been applied to increase the anaerobic biodegradation of WS. The highest biomethane yields of 159.9 ± 6.8 mL CH4.g VS-1 and 169.8 ± 6.8 mL CH4.g VS-1 were achieved after pretreatment at both 250 °C and with 4% NaOH. After combined NaOH-thermal pretreatments, the AD process showed the largest total VFA concentration (i.e. 1280.1 mg Hac L-1) but a relatively high lag phase (i.e. 3.90 days) compared to thermal and NaOH pretreatments alone, from which the highest biomethane yield (i.e. 192.4 ± 8.2 mL CH4.g VS-1 ) was achieved at the end of the AD process. The highest biomethane yield from the combined NaOH-thermal pretreated WS was corroborated by the corresponding highest SCOD/TCOD ratio (i.e. 0.37 ± 0.02) and the highest lignocellulosic fibre removal (i.e. 41.1 ± 2.7% cellulose, 35.6 ± 1.8% hemicellulose, and 58.7 ± 3.2% lignin). The cumulative biomethane yields were further simulated via a modified Gompertz model. This study provides a promising strategy in the sense that the biomethane yield of WS containing large amounts of lignin can be significantly increased via thermal, NaOH, and combined NaOH-thermal pretreatment methods.

Simultaneous pretreatment and saccharification process for fermentable sugars production from Casuarina equisetifolia biomass using transgenic Trichoderma atroviride

ABSTRACT With the increase in the cognizance toward the wide and abundant lignocellulosic biomass, a great interest has been garnered toward the production of value-added products from the biomass. Hence, by capitalizing the Casuarina equisetifolia biomass, the current work developed a simultaneous pre-treatment and saccharification (SPS) process using transgenic Trichoderma atroviride. The ability of T. atroviride to produce lignolytic and cellulolytic enzymes was enhanced by optimizing key process parameters. Under the optimized conditions, a maximum of 1245.6 U/kg of cellulase and 1203.36 U/kg of xylanase, 183.2 U/kg of laccase along with 392.36 g/kg of fermentable sugars were obtained. On comparing with acid and alkaline pre-treatment methods, the T. atroviride -mediated SPS process exhibited trace formation of fermentative inhibitors, which resulted in a minimal inhibition of Escherichia coli. Overall, the current work implements the biorefinery concept on Casuarina equisetifolia biomass by advocating circular economy. Implications: Valorization of lignocellulosic waste biomass into value added compound and as biofuel is considered as a promising alternative resource, owing to its availability and low production cost. However, the presence of chemically resistant lignin demands an intensive treatment process, which sometimes leads to the formation of fermentative inhibitors. Casuarina equisetifolia is a deciduous commercial plant, and an average of 125 tonnes/hector of waste is generated annually in India. By considering the demerit of delignification and the wide availability of Casuarina equisetifolia biomass (CB), the current work aimed at the development of a single-pot simultaneous pre-treatment and saccharification (SPS) of CB by transgenic Trichoderma atroviride.

Development of sustainable approaches for converting the agro-weeds Ludwigia hyssopifolia to biogas production

This study aimed to evaluate potential biogas production from Ludwigia hyssopifolia (water primrose) and examine the effect of alkaline pretreatment on samples through biogas production efficiencies. The research was carried out for 45 days of operation from anaerobic mono-digestion of water primrose by using a batch experiment. Pretreatment was applied for substrate using sodium hydroxide (NaOH) solution (w/v) at different concentrations (0, 1, 2, 3, and 4%) with 10% of total solids (TS) based on dry matter. The scanning electron microscopy (SEM) images were captured to investigate the characteristics of the raw material and pretreated biomass. The results showed that the treatment with 2% NaOH has the highest performance in biogas yield (8072.00 mL) and methane content (64.72%). Notably, the increase (3, 4%) or decreasing (0, 1%) NaOH concentration in treating water primrose did not achieve a significant improvement. Further investigation in the power potential of produced biogas was calculated, and the result was 22,382.19 W/m3 power. Consequently, the feasibility of the alkaline pretreatment method for biogas production and achievable potential for energy efficiency indicates that water primrose is appropriate agro-weed biomass for bioenergy applications.

A comparative study of hemicellulose isolation with hot water, alkaline, and delignification methods from tea leaf brewing waste

Tea leaf brewing waste (TLBW) is a waste with high hemicellulose content. It is a valuable waste of the pharmaceutical and cosmetics industry especially the beverage industry. In this study, the extraction of hemicelluloses (HC) from tea leaf brewing waste using three different pretreatment methods were investigated. The isolation yield of the HC was determined depending on pretreatment methods and pretreatment parameters such as the isolation temperature (25–55 °C), alkaline concentration (NaOH, 5–20%), contact time (12–24 h), the oxidative component (H2O2), and the concentration of sodium chlorite (NaCIO2) in the solution (2–10%). It was observed that the yield of isolation of hemicellulose varied between about 1 and 36% on the basis of raw materials depending on the extraction parameters. The experimental results showed that the suitable conditions for isolation of hemicellulose by alkaline pretreatment method were 15% NaOH concentration, 12-h contact time, and 45 °C. As a result of the experiments performed with the most suitable conditions, approximately 96% of the total hemicellulose in the TLBW was isolated. The extraction yield of hemicellulose achieved by the delignification process was found to be lower about 3% compared with the alkaline methods. But, the hemicellulose color achieved by the delignification process was lighter in color than the alkaline method. The results of the FTIR and H-NMR analysis show that the purity of the hemicellulosic fraction, which was obtained using the delignification method, was higher than the alkaline method.

Comparative analysis of different chlorine-free extraction on oil palm mesocarp fiber

Biobased products are a growing trend in industrial crops, but the natural variation among the plant sources demands the development of efficient pretreatments for standardizing the raw material. This work aims to evaluate the characteristics of pressed oil palm mesocarp fiber after alkaline and multi-step pretreatment methods. Multi-step pretreatment procedure involved acetosolv extraction with a mixture of 93 % (w/w) of acetic acid and 0.3 % (v/v) of hydrochloride acid (a chlorine-free), followed by alkaline bleaching. Acetosolv extraction was also used aiming to allow a more effective delignification during the bleaching stage, and the possibility to recover the solvent that was used in the next extractions; this fact could not be obtained in alkaline extraction alone. The fibers were evaluated concerning the chemical composition, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, and Fourier-transform infrared spectroscopy. The combined multi-step resulted in higher alpha-cellulose content (66 %), crystallinity index (65.20 %), and lower mass loss up to the onset degradation step.

A comparative study on the use of palm bark as a supplementary carbon source in partially saturated vertical constructed wetland: Organic matter characterization, release-adsorption kinetics, and pilot-scale performance

In this study, a comparative investigation of palm bark and corncob (a well-investigated material) for enhancing nitrogen removal efficiency in partially saturated vertical constructed wetland (PSVCW) was performed to evaluate an effective and cost-effective supplementary carbon source. The characteristics of the released organic matter and the release processes were analyzed through optical property characterization and a first-order release-adsorption model, respectively, and the nitrogen removal performance was evaluated in a series of pilot-scale PSVCWs. Results showed that the amount of organic matter released per unit mass of corncob was larger than that released per unit mass of palm bark under the same pretreatment conditions (control, heat, and alkaline pretreatment). The organic matter released from corncob has a higher apparent molecular weight and a higher degree of aromatic condensation than those of the organic matter released from palm bark, whereas the organic matter released from palm bark has higher and more stable bioavailability. Moreover, palm bark showed a more significant improvement of release capacity with the heat and alkaline pretreatment methods. Pilot-scale studies revealed that PSVCW using palm bark as the supplementary carbon source has a longer replacement cycle and higher total nitrogen (TN) removal efficiency than that using corncob, indicating that palm bark can be considered an effective and inexpensive supplementary carbon source. This study provides initial guidance for the ongoing research on supplementary carbon sources for improving nitrogen removal efficiency in constructed wetlands.

Optimization of Pretreatment and Enzymatic Hydrolysis of Spent Coffee Ground for the Production of Fermentable Sugar

The aim of this work was to optimize the condition of pretreatment and enzymatic hydrolysis for high yield of sugar production of spent coffee ground (SCG). Acid and alkaline pretreatment method were compared and the method with more sugar produced was selected. Response surface methodology was use for the analysis of conditions such as concentration of alkali, temperature and weight of SCG. The optimized condition obtained was 0.5% (v/v) of alkali, temperature of 100°C and 5% (w/v) of SCG. Enzymatic hydrolysis was carried out after the optimized condition of alkaline pretreatment. The conditions were pH, temperature and enzyme dosage. The optimized condition obtained was at pH 4.8, 0.01 ml of enzyme and temperature of 55°C.

Impact of pretreatment methods on production of bioethanol and nanocrystalline cellulose

Cellulose, the most abundant terrestrial biopolymer, has immense potential for a range of applications, such as textiles, biomedical applications, and sustainable building components. Due to the recalcitrant nature of lignocellulosic materials, various alkaline and acid pretreatment methods have been developed to recover mono sugars for fermentation. Simultaneous production of bioethanol and nanocrystalline cellulose (NCC) from pretreated Formosan alder biomass was conducted in two stages. Formosan alder biomass was treated using unbleached kraft (UEK), acid steam explosion (SEP), and bleached acid steam explosion (BSEP) and hydrolyzed using cellulase. Filter paper (FP) and alpha-cellulose were used as positive controls. Bioethanol fermentation using E. coli Ko11 was conducted. Residual biomass was further recovered to produce NCC. After 96 h enzyme hydrolysis, the highest sugar yields were 383.4 and 329.84 mg glucose/g biomass for the FP and UEK samples. The highest bioethanol fermentation yields were 4.18 and 3.62 g bioethanol/g biomass for FP and UEK samples. During enzyme hydrolysis of the biomass, crystallinity increased. NCC yields were 613.93 nm (68%) and 1583 nm (73%) for the FP and UEK samples. The negative impact of lignin content was reflected in the particle length of the final NCC. Further lignin removal is required for optimal NCC production. This study showed that Formosan alder biomass could be used to produce both bioethanol and NCC.