Effect Of Alkaline Pretreatment Research Articles

Effect of alkaline pretreatment on the characteristics of barley straw and modeling of methane production via codigestion of pretreated straw with sewage sludge

Straw pretreatment enhances the cellulose accessibility and increases the methane yield from anaerobic digestion. This study investigated the effects of alkali pretreatments with different chemical agents (NaOH, KOH, and Na2CO3) on the physicochemical and thermal characteristics of barley straw, as well as methane production from codigestion with sewage sludge. Artificial neural network modeling with a feedforward neural network (FFNN) and slime mold optimization (SMO) techniques were used to predict methane production. NaOH pretreatment was shown to be the best pretreatment for removing hemicellulose and lignin and for increasing the cellulose accessibility. Moreover, there was a 2.57-fold higher level of methane production compared to that from codigestion with untreated straw. The removal ratios for the total solids, volatile solids, and chemical oxygen demand reached 59.3, 67.2, and 73.4%, respectively. The modeling results showed that the FFNN-SMO method can be an effective tool for simulating the methane generation process, since training, validating, and testing produced very high correlation coefficients. The FFNN-SMO accurately predicted the amount of methane produced, with an R2 of 0.998 and a 3.1×10-5 root mean square error (RMSE).

Effect of alkaline pre-treatment on hydrolysis rate and methane production during anaerobic digestion of paunch solid waste

Paunch is comprised of the partially digested feed contained in cattle or sheep and contributes 20–50% of organic waste produced at red meat processing facilities. Anaerobic digestion has been identified as a promising technology for paunch treatment, however treatment times can be long and when combined with the moderate degradability of paunch this results in high treatment costs that need to be improved. Pre-treatment was investigated as a strategy to improve AD of paunch, alkaline treatment (NaOH or KOH) was selected due to the high lignin content. A range of alkaline loadings (1–20 g 100gTS−1) were tested with an equivalent hydroxide molar concentration of 9–250 mM [OH−]. Alkaline pre-treatment improved both the hydrolysis rate and the overall degradability of paunch solid by up to 4.4 times and 60%, respectively. The enhanced hydrolysis rate and methane yield was correlated to changes in material composition during pre-treatment. While alkaline concentration was an important factor, there were no significant improvements at alkaline concentrations above 12 g 100gTS−1 (150 mM [OH−]).

Chemical Compositions and Characteristics of Biocalcium from Asian Sea Bass (Lates calcarifer) Scales as Influenced by Pretreatment and Heating Processes.

Asian sea bass scales discarded from the fish processing industry contain collagen and calcium. The production of biocalcium can increase their value. The effect of alkaline pretreatment on non-collagenous protein removal from scales was investigated. The alkaline pretreatment of scales was optimal when 2 M NaOH solution was used for 10 min. The impacts of heating processes of varying times on chemical compositions and characteristics of biocalcium (BC) powder from alkali-pretreated scales were also studied. A lower loss of hydroxyproline (HYP) and decreased hardness of scales were obtained when the scales were treated with a boiling process. BC powders from the scales subjected to boiling (B-BC) had higher yield and HYP content than BC powders using a high-pressure heating (HP-BC) process. An augmented heating time (10-30 min) lowered yield, HYP, moisture, and protein contents in BC powder regardless of the heating processes. HP-BC powder had higher ash, calcium, and phosphorus contents than B-BC powder. A whiter color and larger mean particle size were attained for the B-BC powders. X-ray diffractograms revealed that all BC powders had hydroxyapatite, which had a crystallinity of 53.60-66.54%, as a major component. FTIR spectra confirmed that all BC powders comprised proteins and inorganic matter. BC powder from scales with high yield and satisfactory characteristics could be used in calcium supplements.

The effect of alkaline pretreatment on the anaerobic digestion of fruit and vegetable wastes from a central food distribution market

The effect of alkaline pretreatment on the anaerobic digestion of fruit and vegetable wastes from a central food distribution market

Effect of Alkaline Pretreatment on the Fuel Properties of Torrefied Biomass from Rice Husk

Lignocellulosic biomass from rice husk (RH) is a renewable resource for fuel production, but it could pose ash-related challenges. This work focused on investigating the effects of pretreatment at different sodium hydroxide (NaOH) concentrations (i.e., 0.0, 0.25, 0.50, 0.75 and 1.00 M) on the calorific values and ash contents of treated RH products, and also finding the optimal torrefaction conditions. The results showed that alkaline pretreatment by sodium hydroxide (NaOH) reduced the ash content in the RH samples by over 85 wt%. Due to its relatively excellent calorific values and low ash content, the RH sample with 0.25 M NaOH pretreatment (i.e., RH-25) was chosen as a starting feedstock in the subsequent torrefaction experiments as a function of 240–360 °C for holding time of 0–90 min. In addition, the surface properties by scanning electron microscopy—energy dispersive X-ray spectroscopy (SEM-EDS) and Fourier-transform infrared spectroscopy (FTIR) were also used to observe the elemental compositions preliminarily. Based on the fuel properties of the torrefied RH products, the optimal torrefaction conditions can be found at around 280 °C for holding 30 min. As compared to the calorific value of the RH-25 (i.e., 18.74 MJ/kg) and its mass yield (i.e., 0.588), the calorific value, enhancement factor and energy yield of the optimal product were 28.97 MJ/kg, 1.55 and 0.91, respectively. Although the resulting product has a high calorific value like coal, it could have slight potential for slagging and fouling tendency and particulate matter emissions due to the relatively high contents of silicon (Si) and sodium (Na), based on the results of EDS and FTIR.

Effect of alkaline pre-treatment and chemical additives on the performance of wood cement panels manufactured from sunflower stems

This research was performed to investigate the NaOH pre-treatment, chemical additives, and their combined effects on the properties of wood cement panels produced with sunflower stems. The experimental panels were produced with a target density of 1200 kg/m3, a wood/cement ratio of 1:3 and a dimension of 500 mm × 500 mm x 10 mm using the treated/untreated sunflower stem particles as a partial replacement of poplar wood and various chemical additives (CaCl2, AlCl3, MgCl3). The physical, mechanical, thermal, and morphological properties of sunflower stem-based cement panels were evaluated and compared with traditional wood cement panels. In general, the highest mechanical properties were obtained from the panels produced by using the CaCl2 additive and a mixture of pre-treated sunflower stems (40%) and aspen poplar (60%). The panels containing 100% sunflower stem particles-treated with NaOH reached mechanical properties above the minimum standard requirements when CaCl2 was added. The panels’ water resistance, dimensional stability, and mechanical performance were remarkably enhanced by the NaOH pre-treatment of sunflower stems and the chemical additives. Moreover, the addition of sunflower stems led to a marked decrease in the thermal conductivity of the panels. TGA results demonstrated that the sunflower stem adversely affected the cement hydration reaction, whereas the chemical additives and the pre-treatment improved it. In addition, the combined effect of NaOH pre-treatment and chemical additives resulted in more portlandite content in the WCPs compared to their separate use. The SEM observations revealed that the NaOH pre-treatment of sunflower stems and the chemical additives contributed to promoting cement hydration products. It was also observed that the honeycomb structure of sunflower stem pith was crushed and deformed due to the high pressure applied in the manufacture of WCPs.

Bio-Methane Potential (BMP) of Cassava Pulp Waste and Effect of Alkaline Pre-Treatment

Cassava starch processing industry produces cassava pulp as a by-product or waste. In the well-known Duong Lieu village, this waste is released in surrounding environment without treatment causing serious environmental problems. The study aimed to (1) determine the Biomethane Potential (BMP) of the waste and to (2) find out if alkaline pre-treatment would improve it. Different cassava pulp samples were going through BMP test: untreated sample; pre-treated samples at different NaOH doses of 2, 6, 8 wt.% (dry weight-based) and pre-treated samples at different NaHCO3 doses of 2, 4, 6, 8 wt.% (dry weight based). BMP assays were conducted in 590mL bottles at 37oC for 40 days. As the result, BMP of the untreated waste was 281 NmLCH4/gVS and alkaline pretreatment increased BMP of the waste up to 479 mLCH4/gVS by treatment with NaOH 6 wt.% and 450 mLCH4/gVS by treatment with NaHCO3 6 wt.%. In addition, there was a significant reduction of lignin content of the substrate after alkaline pre-treatment. The results show that cassava pulp waste has moderate potential for biogas recovery. In addition, alkaline pre-treatment by either NaOH or NaHCO3 would significantly improve its BMP, possibly thanks to the reduction of lignin content.

Challenges in Sustainable Degradability of Bio-Based and Oxo-Degradable Packaging Materials during Anaerobic Thermophilic Treatment

Although the manufacturers labelled commercially available bio-based products as biodegradable, there are discrepancies concerning the time frame for their sustainable biodegradation and methane production. Starch-based, polylactic acid-based and oxo-degradable foils were anaerobically treated in thermophilic condition (55 °C, 100 days). The effect of alkaline pretreatment on foils degradation was also investigated. To examine changes in their mechanical and physical properties, static tensile tests and microscopic analyses, FTIR and surface roughness analyses were conducted. Despite the thermophilic condition, and the longer retention time compared to that needed for biowaste, a small amount of methane was produced with bio-based foils, even after pretreatment (ca. 30 vs. 50 L/kg VS) and foils only lost functional and mechanical properties. The pieces of bio-based materials had only disintegrated, which means that digestate may become contaminated with fragments of these materials. Thus, providing guidelines for bio-based foil treatment remains a challenge in waste management.

The effect of alkaline pretreatment on surfactant-modified clinoptilolite for diclofenac adsorption: isotherm, kinetic, and thermodynamic studies

Abstract The elimination of diclofenac traces from aqueous environments is important. In this research, the effect of alkaline (NaOH) pretreatment on clinoptilolite before its modification with a surfactant (HDTMA) for diclofenac adsorption under the speculation of the sole presence of diclofenac in the aqueous solution is investigated. The results are compared through isotherm, kinetic, and thermodynamic studies and supplemented by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), and the zeta potential analyses. The contact time was investigated in a 0–180-min range. The pH effect was studied in a range of 5–10 because of diclofenac dissociation below pH = 5. The effect of the temperature on diclofenac adsorption was also considered by establishing the experiments at 25, 35, and 45 °C. For HDTMA-modified clinoptilolite, Temkin, and for NaOH-HDTMA-modified clinoptilolite, Dubinin–Radushkevich, and Freundlich isotherm models and in both cases, the pseudo-second-order kinetic model fitted the experimental data best. All the enthalpy and the entropy changes were negative, suggesting exothermic adsorption with a decrease in the degree of freedom of diclofenac anions after the adsorption. Furthermore, diclofenac physisorption was confirmed through isotherm and kinetic studies.

Sustainable valorization of water primrose with cow dung for enhanced biogas production

In this study, the effects of alkaline pretreatment (2% NaOH) of water primrose on its biogas production efficiency and anaerobic co-digestion of cow dung were investigated. A scanning electron microscope (SEM) was used to analyze the changes in main compositions and physico-chemical structure of water primrose after pretreatment and untreated biomass. Furthermore, the experiments evaluate the efficiency and optimization mixing ratio of co-digestion using water primrose and cow dung. The pretreatment of water primrose at different periods for the examination of the biodegradability matters in the substrate and biogas production. Among the three mixing ratios of co-substrate tested, the best performance in this study was achieved at mixing ratio 2:1 (water primrose to cow dung, w/w) for 2 weeks’ pretreatment time on grass, including all measurements as biogas production (8610 mL), methane concentration (68.2%), and percentage of total solids (70.84%), volatile solids (64.76%), and chemical oxygen demand (66.55%) removal efficiency.

The Effects of Alkaline Pretreatment on Agricultural Biomasses (Corn Cob and Sweet Sorghum Bagasse) and Their Hydrolysis by a Termite-Derived Enzyme Cocktail

Sweet sorghum bagasse (SSB) and corncob (CC) have been identified as promising feedstocks for the production of second-generation biofuels and other value-added chemicals. In this study, lime (Ca(OH)2) and NaOH pretreatment efficacy for decreasing recalcitrance from SSB and CC was investigated, and subsequently, the pretreated biomass was subjected to the hydrolytic action of an in-house formulated holocellulolytic enzyme cocktail (HEC-H). Compositional analysis revealed that SSB contained 29.34% lignin, 17.75% cellulose and 16.28% hemicellulose, while CC consisted of 22.51% lignin, 23.58% cellulose and 33.34% hemicellulose. Alkaline pretreatment was more effective in pretreating CC biomass compared to the SSB biomass. Both Ca(OH)2 and NaOH pretreatment removed lignin from the CC biomass, while only NaOH removed lignin from the SSB biomass. Biomass compositional analysis revealed that these agricultural feedstocks differed in their chemical composition because the CC biomass contained mainly hemicellulose (33–35%), while SSB biomass consisted mainly of cellulose (17–24%). The alkaline pretreated SSB and CC samples were subjected to the hydrolytic action of the holocellulolytic enzyme cocktail, formulated with termite derived multifunctional enzymes (referred to as MFE-5E, MFE-5H and MFE-45) and exoglucanase (Exg-D). The HEC-H hydrolysed NaOH pretreated SSB and CC more effectively than Ca(OH)2 pretreated feedstocks, revealing that NaOH was a more effective pretreatment. In conclusion, the HEC-H cocktail efficiently hydrolysed alkaline pretreated agricultural feedstocks, particularly those which are hemicellulose- and amorphous cellulose-rich, such as CC, making it attractive for use in the bioconversion process in the biorefinery industry.

Effect of alkaline pretreatment on photo-fermentative hydrogen production from giant reed: Comparison of NaOH and Ca(OH)2

Giant reed was the first time used for photo-fermentative hydrogen production with HAU-M1 bacteria. Effects of NaOH and Ca(OH)2 pretreatments of giant reed on structural changes, enzymatic digestibility, hydrogen production, and energy conversion efficiency were evaluated. Compared to Ca(OH)2 pretreatment, NaOH pretreatment removed more dry matter and lignin at the same loading. The highest glucose yield (44.9%) of NaOH pretreatment was 1.74-fold higher than that of Ca(OH)2 pretreatment. 20% NaOH pretreated giant reed biomass achieved the highest hydrogen yield (98.3 mL/g TS), which was 20% and 70% higher than the highest level of Ca(OH)2 pretreated (20% Ca(OH)2) and untreated giant reed, respectively. Only giant reed biomass pretreated with 20% NaOH resulted in a significant (p < 0.05) increase (25%) in energy conversion efficiency.

Comparative data on effects of alkaline pretreatments and enzymatic hydrolysis on bioemulsifier production from sugarcane straw by Cutaneotrichosporon mucoides

Bioemulsifiers are surface active compounds which could be potentially used in food processing, cosmetic sector and oil recovery. Sugarcane straw (SS), was used as the raw substrate for the production of bio-emulsifiers (BE) by Cutaneotrichosporon mucoides. Three different delignification strategies using dilute sodium hydroxide, sodium sulfite and ammonium hydroxide followed by enzymatic hydrolysis (Cellic CTec 2, 7.5% total solids, 15 FPU/g, 72 h) were studied. Enzyme hydrolysis of ammonium hydroxide pretreated SS showed a maximum of 62.19 ± 0.74 g/l total reducing sugars with 88.35% hydrolytic efficiency (HE) followed by sodium hydroxide (60.06 ± 0.33 g/l; 85.40% HE) and sodium sulfite pretreated SS (57.22 ± 0.52 g/l; 84.71% HE), respectively. The ultrastructure of SS (native and delignified) by fourier transform-infrared and near infrared spectroscopy, revealed notable structural differences. The fermentation of hydrolysates by C. mucoides into bioemulsifiers showing emulsification index (EI) of 54.33%, 48.66% and 32.66% from sodium sulfite, sodium hydroxide, and ammonium hydroxide pretreated SS, respectively.

Effect of alkaline pretreatments on the enzymatic hydrolysis of wheat straw.

Lignocellulosic materials are mainly consisted of lignin, cellulose, and hemicellulose. Lignin is recognized as the main obstacle for the enzymatic saccharification of cellulose towards the fermentable sugars' production. Hence, the removal of lignin from the lignocellulosic feedstock is beneficial for reducing the recalcitrance of lignocellulose for enzymatic attack. For this purpose, various different alkaline pretreatments were examined in order to study their effect on the enzymatic saccharification of wheat straw, as a typical lignocellulosic material. Results revealed that the alkaline pretreatments promoted delignification reactions. Regarding the removal of lignin, the most efficient pretreatments were alkaline treatment with hydrogen peroxide 10% and NaOH 2% autoclave with delignification efficiencies of 89.60% and 84.86% respectively. X-ray diffraction analysis was performed to enlighten the structural changes of raw and pretreated materials. The higher the delignification of the raw material, the higher the conversion of cellulose during enzymatic saccharification. In all cases after enzymatic saccharification, the cellulosic conversion was much higher (32-77%) than the untreated wheat straw (8.6%). After undergoing alkaline peroxide 10% pretreatment and cellulase treatment, 99% of the initial raw straw was eventually solubilized. Thus, wheat straw could be considered as an ideal material for the production of glucose with proper pretreatments and effective enzymatic hydrolysis.

Effects of Alkaline Pretreatment on the Characteristics of Collagen from Mangrove Conch (Telescopium telescopium)

The horn snail (Telescopium telescopium) is a gastropod living in mangrove forests and is considered as a pond pest. This study was aimed to determine the effects of alkaline and acetic acid pretreatment on the characteristics of collagen from the horn snail meat. The immersion of the meat in NaOH 0.20% for 10 hours gave a significant reduction in non-collagen protein content (α = 0.05). Further immersion with acetic acid 0.05% for 6 hours also significantly affected (α = 0.05) the swelling degree and the collagen solubility. The extraction yield was 1.08±0.21%, with 72.23% of brightness, and the viscosity was 16.34 cP. The proline content of the collagen was 9.21%.

Profiling of Catfish Swim Bladder Collagen (Pangasius sp.) Through Enzymatic Proses

Swim bladder is a marine byproduct and a potential source of collagen needed by food, cosmetical, biomedical and pharmaceutical industry. This study evaluated the effectiveness of alkaline pretreatment and papain enzyme on the characteristics of collagen from the catfish swim bladders. TThree concentrations of alkaline (0.05; 0.1 and 0.15 M) with were used to pretreat the swim bladders for 2; 4; 6; 8; 10 and 12 hours. The collagen was also treated by papain enzyme with concentrations of 0; 5,000; 10,000; 15,000 and 20,000 U/mg for 24 and 48 hours. The result showed that pretreatment using NaOH 0.05 M for 6 hours effectively reduced the noncollagen protein (p&lt;0.05). Meanwhile, the treatment using papain enzyme with concentration of 5.000 U/mg for 48 hours improved the collagen solubility. The FTIR of collagen showed the existence of a triple helix structure. Meanwhile, the thermal analysis showed collagen gelation transition temperature (Tg) was at 88oC.

Effect of Alkaline Pre-Treatment on Cassava Pulp for Optimum Biogas Production

(Being produced in vast quantity as one of by-product from cassava starch processing chains, cassava pulp has great potential for energy recovery by harnessing biogas through anaerobic digestion (AD). This study aims to enhance biogas production by comparative investigation in batch mode digestion. 5%TS w/v of cassava pulp mixed with mill effluent were pre-treated with 10 molar potassium hydroxide (KOH), sodium hydroxide (NaOH), and calcium hydroxide (Ca(OH)2) solution for 6 hours contact time. Effects of different alkaline pre-treatment on cassava substrate were assessed in total dissolved solid (TDS), soluble chemical oxygen demand (SCOD), Volatile Fatty Acids to Alkalinity ratio (VFA/TA), and reducing sugars. Daily accumulated biogas yield was taken as final indicator of the effect of different pre-treatment. KOH pre-treatment in pH 11 resulted highest dissolved solid 13.07 mg/L, and improved soluble chemical oxygen demand (SCOD) formation up to 75.61% (480,000 mg/L) than control substrate. The experiment revealed peak biogas production by KOH pre-treated substrate was found at day 6 after digestion executed, and achieved 546 ml. The finding proves out of different pre-treatment method applicable to cassava pulp, KOH pre-treatment could realistically increase biogas yield for cassava mills. Biogas production increased up to 101%, 92%, and 70% using KOH, Ca(OH)2 and NaOH respectively. However, when future provision to the technology for AD system and design is concerned, the choice of highly reactive alkali could lead to complication in the system.

Effect of alkaline pretreatment on the thermal behavior and chemical properties of rice husk varieties in relation to activated carbon production

Thermal behavior and chemical properties of selected raw and NaOH-pretreated rice husk varieties were investigated. NaOH-pretreatment process involved soaking 5 g rice husk samples in 40 mL of 2%w/v NaOH, shaking (400 rpm) and heating (50 °C) for 3 h. NaOH-pretreated samples were water-washed, oven-dried, and milled for use in the determination of their thermal behavior and surface functional groups. Alkaline wash-water was also analyzed for sugar components. Thermal decomposition temperatures, degradation rates, and the subsequent mass losses varied from one rice husk variety to another. These thermal properties increased after NaOH-pretreatment of the rice husk varieties, reducing their char yields (17.1–20.4% db). These changes mainly had to do with the lignin, hemicellulose, and ash removal from the rice husk varieties, as confirmed by their FTIR analysis, as well as by the sugar composition analysis of their alkaline wash-water. Consequently, the FTIR spectra differed between the raw and NaOH-pretreated rice husk varieties.

Fermentation of pineapple fruit peel wastes for bioethanol production

In the past few years, the global demand in bioethanol has been continuously rising due to its economic importance. Several countries have exerted considerable efforts in the production of bioethanol as a transport fuel from different feedstocks and started to practice consuming this environment-friendly fuel. Thailand is now one of the top consumers of bioethanol in South East Asia and belongs to the top 5 leading countries in producing pineapples. Production of bioethanol from pineapple wastes, especially the fruit peels, became possible. In this study, the effects of alkaline pretreatment and microbial hydrolysis through Trichoderma harzianum of pineapple fruit peel were evaluated. Among the four concentrations of NaOH, the 0% NaOH gave the highest total and reducing sugar (458.44 ± 13.6 g/L and 279.67 ± 21 g/L) than 1%, 3%, and 5% concentrations of NaOH. Samples pretreated with 0% NaOH were subjected to microbial hydrolysis which showed an increase in reducing sugar of the samples. At the end of the experiment, a bioethanol yield of 5.98 ± 1.01 g/L from pineapple fruit peel was successfully produced at 48 h of fermentation.

Effect of alkaline pre-treatment on the anaerobic biodegradability of coffee husk

The present paper deals with the mono-digestion of coffee husk during the operation of batch reactors and semi-continuous stirred tank reactor (S-CSTR) using both pre-treated residual at 3% Ca(OH)2 and without pre-treatment. The semi-continuous operation was carried out in 4 stages at different organic loading rate (OLR, [gVS L-1 d-1]) and hydraulic retention time (HRT, [d]) (OLR:HRT) ratios (0.1:90, 0.2:90, 0.2:45 and 0.2:30). As a result of the pre-treatment, up to 223% of the organic matter solubilisation was obtained. However, pre-treatment did not provide better results in biodegradability, observing a negative trend in methane yield when operating in S-CSTR, due to the accumulation of compounds from the fractionation of the lignin as is the case of polyphenols. The operation was further developed using the residual without pre-treatment. The highest methane yield was obtained at 45:0.2 when using the residual without pre-treatment being with 277 mLCH4 gVS -1, for a methane productivity of 1.1 L L-1 d-1. When implementing the 30:0.2 ratio, a biomass washout was observed in the system, so it is recommended to operate at low OLR and high HRT when treating solid coffee wastes.