NaOH Pretreatment Research Articles

Mild chemical pretreatment of cassava pulp for enhancing high-load anaerobic digestion

Lignocellulosic components limit the potential of starch-rich cassava pulp for high-load anaerobic digestion. Mild chemical pretreatments using 0.1%–3.0% (w/v) of H2SO4, HCl, NaOH, and KOH were investigated at low temperature (30 °C) for enhancing organic solubilization and methane production. Alkalis solubilized up to 54% of the chemical oxygen demand, degraded 53% of hemicellulose, and thus increased 18–33% of methane yield. The maximum methane yield was 324 ± 5 mL/gVS achieved by 2.0% NaOH pretreatment. Modified fed-batch BMP constructively elucidated the enhancing and hindering effects of pretreatment on methane production at high organic loading. Suitable mild pretreatment is essential for developing a practical digestion process at higher organic loading rates.

Lignin removal, reducing sugar yield and photo-fermentative biohydrogen production capability of corn stover: Effects of different pretreatments

The effects of different pretreatment methods, including hydrothermal, acid, alkali, acid-heat and alkali-heat on lignin removal, reducing sugar (RS) yield and photo-fermentative biohydrogen production (PFHP) capability of corn stover (CS) were studied. NaOH-heat pretreatment was the most effective for lignin removal from CS, and the lignin removal rate reached 77%. All the studied pretreatment methods improved the total RS yield of CS, and the highest total RS yield (46.1 g/100 g raw material (RM)) was obtained from 2% NaOH-heat pretreated CS. 2% NaOH pretreatment realized the best PFHP of CS, which increased the hydrogen yield (HY), maximal hydrogen production rate (HPR) and highest hydrogen content (HC) by 31.9%, 50.9% and 20.1% respectively, and shortened hydrogen production lag time (HPLT) by 58.8% over that of untreated CS. However, NaOH-heat and 4% NaOH pretreatment weakened the PFHP capability of CS.

Use of Ionic Liquid Pretreated and Fermented Sugarcane Bagasse as an Adsorbent for Congo Red Removal

A large amount of industrial wastewater containing pollutants including toxic dyes needs to be processed prior to its discharge into the environment. Biological materials such as sugarcane bagasse (SB) have been reported for their role as adsorbents to remove the dyes from water. In this study, the residue SB after fermentation was utilized for the dye removal. A combined pretreatment of NaOH and methyltrioctylammonium chloride was given to SB for lignin removal, and the pretreated SB was utilized for cellulase production from Bacillus aestuarii UE25. The strain produced 118 IU mL−1 of endoglucanse and 70 IU mL−1 of β-glucosidase. Scanning electron microscopy and FTIR spectra showed lignin and cellulose removal in fermented SB. This residue was utilized for the adsorption of an azo dye, congo red (CR). The thermodynamic, isotherm and kinetics studies for the adsorption of CR revealed distinct adsorption features of SB. Untreated SB followed Langmuir isotherm, whereas pretreated SB and fermented SB obeyed the Freundlich isotherm model. The pseudo-second-order model fitted well for the studied adsorbents. The results of thermodynamic studies revealed spontaneous adsorption with negative standard free energy values. Untreated SB showed a 90.36% removal tendency at 303.15 K temperature, whereas the adsorbents comprised of pretreated and fermented SB removed about 98.35% and 97.70%, respectively. The study provided a strategy to utilize SB for cellulase production and its use as an adsorbent for toxic dyes removal.

Influence of alkaline pre-treatment on acid dissolution of cathode material of 18650 lithium battery

Lithium battery cathodes contain lithium, cobalt, nickel, and manganese. Recycling of spent lithium batteries aims to recover these elements for re-use. Liberation of cathode materials from other metals in the battery such as aluminium, copper, and iron, is essential to obtain a good leaching efficiency in the recovery of valuable metals from end-of-life lithium batteries. This study investigates the behaviour of cathode materials and other metals in spent 18650 lithium batteries during leaching in H2SO4 solution with and without NaOH pre-treatment. Dissolution of aluminium using NaOH is a selective method to separate the metal from other elements. The influence of a 2-hour NaOH pre-treatment on subsequent acid leaching of cathode materials was investigated at both room temperature and 80°C. The extraction of aluminium increased to 75% at a higher temperature. Lithium concentration in the pregnant leach solution from acid leaching also increases with NaOH pre-treatment. The pre-treatment had a negligible effect on nickel, manganese, iron, and copper extraction. However, the cobalt extraction with NaOH pre-treatment was significantly lower. The result was likely due to indirect impact of less hydrogen gas was generated from a lower Al amount. The lattice structure of the leach residue for the sample with NaOH pre-treatment was monoclinic rather than rhombohedral due to stronger delithiation.

Comparing chemical and plasma modification of stainless steel surfaces – Relevance for adsorption of adhesion promotor vinyltrimethoxysilane (VTMS)

Coated stainless steel surfaces with silane compound coupling agent are implemented in many industrial applications. For vinyltrimethoxysilane (VTMS) adsorption optimization, surface modification of stainless steel type V2A was performed with plasma, ozone and in sodium hydroxide (NaOH) solutions. Subsequent a systematic study of a central composite design of experiments (DoE) accomplished with X–ray photoelectron spectroscopy (XPS) data. Similar results in ozone, oxygen (O2)–, and water (H2O)–plasma treatment led to a detailed presentation of the results from the O2–plasma and NaOH treatment. Treatment effects on the surface roughness were determined using atomic force microscopy (AFM) and the functional groups of VTMS on the surface with surface enhanced Raman spectroscopy (SERS). All treatments resulted to a reduction of C and a higher oxidized surface whereas the Fe/Cr–ratio and OH-content were changing significantly after NaOH treatment. Only the root mean squared (RMS)–values calculated from the AFM images of NaOH treated V2A samples indicated an increased coverage of VTMS after longer treatment time in higher concentrated NaOH solutions. The results of this study enable setting the amount of VTMS bonding to the surface of V2A due to NaOH pretreatment.

Mesophilic aerobic digestion: An efficient and inexpensive biological pretreatment to improve biogas production from highly-recalcitrant pinewood

Biological pretreatments and their combination with chemical and physical pretreatments are among the inexpensive methods for the improvement of biogas production from lignocellulosic biomass. In this study, mesophilic aerobic digestion was studied as a biological pretreatment to improve biogas production from pinewood. Its effects in combination with other pretreatments, i.e., liquid hot water (LHW), sodium hydroxide (NaOH), and ultrasonic pretreatments, were also investigated. LHW and Alkali (using 8% w/w NaOH) pretreatments were performed at less severe conditions (100 °C for 10 min) to evaluate the synergistic effect of these thermochemical pretreatments on biogas production. The ultrasonic pretreatment was performed at 40 KHz for 30 min at 40 °C. Biological pretreatment was carried out using aerobic sludge at 37 °C for 10 days. The aerobic digestion was the only pretreatment that could individually improve the methane yield from pinewood by 7.3 folds. However, the highest methane yield (57.7 mL/g VS of pretreated pinewood) was obtained by the combination of NaOH, biological, and ultrasonic pretreatments, which was 11.2 folds higher than that of the untreated substrate. It was concluded that the pretreatment with aerobic digestion could significantly improve the biogas production yield, especially in combination with mild thermo-chemical pretreatments.

Optimizing cellulose microfibrillation with NaOH pretreatments for unbleached Eucalyptus pulp

Microfibrillated cellulose (MFC) is a form of biopolymer that stands out because of its versatile use. However, the process of obtaining MFC requires adjustments to provide the increase of microfibrillation in industrial scale. Thus, this study aimed to apply pretreatments with NaOH in unbleached Eucalyptus sp. fibers to optimize the microfibrilation process, in order to evaluate the effect of drying and not drying the fibers after pretreatments for reduction of energy consumption. Treatments of MFC with NaOH at 5% with 2 h of reaction and by 10 wt% were evaluated for the resulting morphology, chemical composition, and energy consumption. The length and width of the pulp fibers pretreated with NaOH decreased significantly, mainly with hasher pretreatments. Pretreating fibers with 5 wt% NaOH for 2 h increased the water retention value (WRV), in addition to presenting the lowest energy consumption for fibrillation, promoting energy savings of up to 48%. Pulps that were non-dried after the NaOH pretreatments resulted in easier microfibrillation and lower energy consumption when compared to dried pulp, which shows the negative impact of drying on the fibers to obtain MFC.

Effects of different lignocellulosic wastes on alleviating acidification of L-lactic acid production from food waste fermentation

In this study, the effects of different lignocellulosic wastes on alleviating acidification in the fermentation of lactic acid (LA) from food waste (FW) were studied. Amongst three lignocellulosic wastes, spent mushroom substance (SMS) could reach 95.22% lignin removal efficiency through simple NaOH pretreatment. Results showed pretreated SMS was best choice for FW co-fermentation, the maximum LA concentration could reach 46.12 g/L. And the NaOH solution as neutraliser could save 5.69 mL compared with the other two lignocellulosic wastes. The reason for alleviating acidification was 4.71% calcium salt in SMS and the porous structure of SMS. Then, 50% of pretreated liquid (PL) produced in SMS pretreatment was reused in the co-fermentation process. Compared with the group with 0% PL loading, that with 50% PL loading showed an increase in LA concentration and optical purity of L-LA, reaching 50.95 g/L and 96.28%, and NaOH consumption also further decreased by 24.65%.

Effect and optimization of NaOH combined with Fenton pretreatment conditions on enzymatic hydrolysis of poplar sawdust

In this study, the effects and mechanism of pretreatments of three types of chemical reagents combined with Fenton on poplar sawdust were studied and the optimization of enzymatic hydrolysis conditions was conducted using response surface methodology. The results showed that cellulase and hemicellulase had the best hydrolysis effect after NaOH-Fenton pretreatment, which were 63.73% and 29.29%, respectively. The optimal process of poplar substrate was to react in 1% NaOH at 100 ℃ for 1 h, then placed in the Fenton reaction system of 0.2 mmol Fe2+ and 25 mmol H2O2 for 7 h, and finally subjected to enzymatic hydrolysis for 72 h at 52 ℃, with a liquid-to-solid ratio of 33 wt/vol and 15 μL/g of β-glycosidase. Under this condition, the enzymatic hydrolysis rates of cellulase and hemicellulase reached 86.65% and 43.90%, respectively. In conclusion, the combination of NaOH and Fenton pretreatment can effectively promote the enzymatic hydrolysis of poplar sawdust, which has great potential in the production of cellulosic ethanol.

The effect of NaOH treatment of rice husk on its catalytic fast pyrolysis under decomposed methane for the production of aromatics

Here, catalytic fast pyrolysis (CFP) was studied as a method to valorize rice husk (RH). Specifically, the effects of RH pretreatment, i.e., NaOH treatment, on the CFP efficiency and selectivity over a Ga-loaded HZSM-5 (SiO2/Al2O3 ratio = 38) were investigated. In addition to NaOH pretreatment, it was investigated how pyrolysis medium (N2, CH4, or a gas stream evolved from ex-situ CH4 decomposition over a Ni/La2O3/CeO2/Al2O3 catalyst (Ni/La2O3/CeO2 = 2/1/1) at 923 K (d-CH4)) influences the CFP of pretreated RH. The NaOH treatment reduced the content of ash and increased the content of cellulose in the RH sample. Thus, the effect of pyrolysis medium on the CFP of cellulose was studied at first, followed by that on CFP of NaOH-treated RH. With regard to the pyrolysis medium, the yield of aromatic compounds such as benzene, toluene, ethylbenzene, and xylene (BTEX) achieved with both cellulose and the NaOH-treated RH enhanced in an order; d-CH4 > CH4 > N2. The removal of ash from RH with the NaOH pretreatment increased the BTEX yield up to 22.3 wt% as ash (mineral impurities) affects pyrolytic behavior of cellulose and lowers accessibility of pyrolytic volatiles to acid sites on zeolite. This study gives helpful information about how different parameters influence the conversion of RH into BTEX via CFP process.

Assessment of Coproduction of Ethanol and Methane from Pennisetum purpureum: Effects of Pretreatment, Process Performance, and Mass Balance.

To overcome the structural complexity and improve the bioconversion efficiency of Pennisetum purpureum into bioethanol or/and biomethane, the effects of ensiling pretreatment, NaOH pretreatment, and their combination on digestion performance and mass flow were comparatively investigated. The coproduction of bioethanol and biomethane showed that 65.2 g of ethanol and 102.6 g of methane could be obtained from 1 kg of untreated Pennisetum purpureum, and pretreatment had significant impacts on the production; however, there is no significant difference between the results of NaOH pretreatment and ensiling-NaOH pretreatment in terms of production improvement. Among them, 1 kg of ensiling-NaOH treated Pennisetum purpureum could yield 269.4 g of ethanol and 144.5 g of methane, with a respective increase of 313.2% and 40.8% compared to that from the untreated sample; this corresponded to the final energy production of 14.5 MJ, with the energy conversion efficiency of 46.8%. In addition, for the ensiling-NaOH treated Pennisetum purpureum, the energy recovery from coproduction (process III) was 98.9% higher than that from enzymatic hydrolysis and fermentation only (process I) and 53.6% higher than that from anaerobic digestion only (process II). This indicated that coproduction of bioethanol and biomethane from Pennisetum purpureum after ensiling and NaOH pretreatment is an effective method to improve its conversion efficiency and energy output.

Continuous anaerobic digestion of zucchini stem after pretreatment

Anaerobic digestion (AD) is a widely used technology for converting organic wastes into biomethane with the advantages of clean energy production and few environmental impacts. Zucchini stem (ZS), the main waste produced from zucchini cultivation, is a potential feedstock for AD due to its high moisture and organic contents. This study investigated the methane production performance and system stability of ZS in continuous AD mode with the increase of organic loading rate (OLR). Moreover, to improve the methane production efficiency, KOH, NaOH, and alkaline hydrogen peroxide (AHP) pretreatments were also performed. The results showed that raw ZS gave a daily methane yield (DMY) of 182.1 mL g VS − 1 d −1 and volumetric methane yield (VMY) of 0.546 L L −1 d −1 at an OLR of 3.0 g VS L −1 d −1 . At the same OLR, 2% KOH-pretreated ZS significantly enhanced the DMY to 236.0 mL g VS − 1 d −1 and the VMY to 0.708 L L −1 d −1 , with a biodegradability (B d ) of 56.3%, which was 29.7% higher than that of raw ZS. However, NaOH- and AHP-pretreated ZS could not achieve stable methane generation at an OLR of 2.0 g VS L −1 d −1 . This study forms a foundation for future industrial applications of ZS; the investigated approach not only utilizes this waste efficiently and reduces its environmental pollution but also produces renewable biomethane energy and may improve the energy structure in rural areas. • Continuous anaerobic digestion (AD) of pretreated zucchini stem (ZS) was explored. • 2% KOH pretreated ZS performed stably and efficiently continuous AD system. • The highest volumetric methane yield was 0.708 L L -1 d -1 after 2% KOH pretreatment.

Strong and highly flexible slivers prepared from natural bamboo culm using NaOH pretreatment

Slivers have been split from fast-growing bamboo to manufacture bamboo weaving products. However, the flexibility and strength of bamboo slivers, especially the bamboo slivers from the inner layer of bamboo, is inadequate for weaving products in various shapes. Herein, we developed a simple method using NaOH pretreatment with various concentrations to process bamboo slivers from natural Moso bamboo (Phyllostachys pubescens) into super-flexible bamboo slivers with improved tensile strength. The changes in the structure and chemical compositions were further indicated to elucidate the strength and toughness strengthening mechanisms behind the alkali treatment. The results showed that the 5% NaOH treatment increased the tensile strength by up to 35 % and 70 % for slivers from the outer- and inner layers of the bamboo culm, respectively. The flexibility of all treated bamboo slivers was significantly improved. The most excellent flexibility of bamboo slivers was found at the 15 % NaOH treatment and this alkali-treated bamboo sliver was able to be violently bent without fracture. The density of 5% NaOH treated sliver from the outer and inner layer of bamboo increased by 14 % and 80.18 % compared with the untreated ones. The parenchyma cells in bamboo slivers collapsed to form in an interlocking structure due to the removal of lignin and hemicellulose, which lead to high strength and flexibility.

Minimizing water consumption for sugar and lignin recovery via the integration of acid and alkali pretreated biomass and their mixed filtrate without post-washing

Excessive post-washing of pretreated biomass leads to huge water consumption and chemical loss. To address this issue, parallel HOAc and NaOH pretreatments of biomass followed by integration of their biomass and filtrate were investigated. Pretreatment effectiveness including morphology, crystallinity, and component recovery, were elucidated. Results showed that HOAc and NaOH in the mixed filtrate were neutralized to achieve a pH of around 4.80 prompting the alkali lignin precipitation. Lignin (46.01 and 48.38 g/kg-biomass for hemp and poplar, respectively) exhibiting comparable FTIR characteristics with the commercial alkali lignin was recovered. Compared to sodium acetate buffer as a control, integrating HOAc and NaOH pretreated biomass and their mixed filtrate for enzymatic hydrolysis boosted total sugar concentration (hemp: 42.90 vs. 38.27 g/L; poplar: 43.18 vs. 38.76 g/L) without compromising glucose yield (hemp: 70.86 vs. 70.69%; poplar: 66.48 vs. 69.48%) but improving xylose yield (hemp: 60.10 vs. 35.92%; poplar: 56.90 vs. 29.39%).

Optimization of alkali pretreatment to enhance rice straw conversion to butanol

The use of rice straw (RS) was enhanced to produce biobutanol as biofuel, for which the NaOH pretreatment was optimized by considering the butanol-biomass ratio that quantify the mass balance efficiency of the three sequential stages of the process: pretreatment, enzymatic hydrolysis and fermentation by Clostridium beijerinckii. The optimum point (solid loading of 5% w/v with 0.75% w/v NaOH at 134 °C for 20 min) of the best cost-wise option yielded an enhanced biomass use of 77.6 g kg RS−1. A maximum butanol titer of 10.1 g L−1 was reached after 72 h of fermentation with the complete uptake of glucose and nearly complete uptake of xylose. The NaOH concentration was the most influential parameter. The appropriate dosage to maximize fermentable sugars instead of the mass balance efficiency of the three stages underestimated the biomass use by 13%, showing the importance of correctly selecting the variable response during optimization.

Effect of Thermo-Chemical Pretreatment of Kenyan Market Waste on Mesophillic Biogas Production

Effects of pretreatment on the anaerobic digestion of waste fruit and vegetable market waste were investigated in biogas production by batch experiments. The pretreatment was NaOH and HCl thermochemical, thermal and chemical methods. The wastes were chopped and blended before loading to the digester. Acid hydrolysis was done by adding 20ml 0.1M HCl with thorough mixing before purging with CO2 and sealing. Alkaline pretreatment was done using 1M NaOH. In both cases, the setups were exposed to heat at 1000C for 12hours, after which they were allowed to cool for 3 hours. The pH was modified to 6.7 – 7.2 before loading the inoculum and studying biogas generation. The large-scale setups with 1.0l, 1.5l, 5l and 10l capacity were studied for biogas generation. The results obtained show that thermochemical pretreatment results in more cumulative biogas production at 6200ml, followed by thermal at 4900ml and then chemical pretreatments at 3750ml for 500g mixed fruits and vegetable market wastes. Alkaline pretreatment is more efficient compared to acidic hydrolysis though highly influenced by proximate properties of the wastes and operation pH. The large-scale pretreatment resulted in 34500ml and 31400ml cumulative biogas from HCl and NaOH pretreatment. In conclusion, thermochemical pretreatment of market waste results in increased biogas generation resulting from hemicellulose breakdown and disrupting lignin-hemicellulose ether bonds in acid hydrolysis. In contrast, alkaline pretreatment leads to swelling of lignocelluloses and partial lignin solubilization lignin breakdown. The overall biogas generation depends on proximate waste matter and digester operation pH.

Effects of Hydrodynamic Cavitation-Assisted NaOH Pretreatment on Biofuel Production from Cyanobacteria: Promising Approach

Eukaryotic microalgae and prokaryotic cyanobacteria can grow in various water and wastewater types, and both can grow biomass by taking nutrients and converting atmospheric CO2 into useful products. Biofuels obtained by processing this landless grown biomass are defined as “third-generation biofuels”. In this study, the effects of hydrodynamic cavitation (HC)-assisted NaOH pretreatment on methane production from cyanobacteria were investigated. Cyanobacterial biomass was isolated from thermal springs located in the southwest of Turkey (Denizli-Turkey) and identified as Desertifilum tharense. Desertifilum tharense biomass was grown on a laboratory scale, and along with its compositional characteristics, culture-specific parameters were determined. HC-assisted NaOH pretreatment was applied to evaluate optimum process conditions for enhancing methane production from D. tharense. In the experimental design, process parameters of cavitation number (Cv: 0.3-0.7), NaOH concentration (0–4%), solid content (1.5%), reaction time (4h), and reaction temperature (30°C) were combined to reveal the parameter-specific impact of HC pretreatment. The effect of the HC-assisted NaOH pretreatment was further investigated with molecular-bond and surface structure characterization. Along with the energy equivalent of obtained biofuel, energy requirements for cultivation, harvesting, pretreatment, and anaerobic digestion (AD) were calculated to determine the process’s overall energy efficiency. Kinetic parameters of raw and pretreated D. tharense were determined by first-order, cone, modified Gompertz, and reaction curve models. The results revealed that by the application of pretreatment, a 2-35.3% soluble COD increase was achieved, whereas methane production was increased from 241.5 to 290.6 mLCH4 gVS−1. Application of HC with a low Cv of 0.3 boosted methane production up to 20.3% compared to the raw D. tharense.

ENGINEERING STUDIES ON LEMON FRUIT DRYING WITHELECTRIC OVEN

The present study aimed to assess the drying kinetic usingan electric oven dryer for drying lemon fruits using thin layer models. The drying behavior was investigated and simulated using four different thin layer drying models (Newten, Page, Modified Page, Henderson and Pabis's equations). The experimental work was conducted under two different levels of oven temperature (80 and 110°C) and, whole fruit, whole fruit with (1% NaOH) pretreatment and three different thickness (4, 5 and 6 mm). The variations in lemon moisture content was recorded versus drying time until reaching of 14.28 and 8.10 (% d.b) for whole fruit without pretreatment at (80 and 110°C), respectively, whilst it reaches (14.15, 12.86 and 14.15% d.b) at 80°C and (12.86, 14.15 and 16.82% d.b) at 110°C for lemon slices of 4, 5 and 6 mm, respectively. The whole lemon fruit with NAOH pretreatment recorded higher percentages of total crude fats (from 1.599 to 1.622%), total soluble sugar(from 6.40 to 6.80%), citric acid (from 5.95 to 6.21%) and ascorbic acid, vitamin c, (from 44.21 to 44.98 mg/100g) in comparison with the whole lemon without pretreatment and sliced lemon. Allstudied models could describe the drying behavior of whole lemon fruits and slices satisfactorily. However, the Page and Modified page models considered more proper for describing the drying behavior and predicting the changes in moisture content of both forms of lemons due to the higher values of coefficient of determination R2 (0.9896).

Comparison of the effects of different pretreatments on the structure and enzymatic hydrolysis of Miscanthus.

Miscanthus is regarded as a desired bioenergy crop with enormous lignocellulose residues for biofuels and other chemical products. In this study, the effect of different pretreatments (including microwave, NaOH, CaO, and microwave+NaOH/CaO) on sugar yields was investigated, leading to largely varied hexose yields at 4.0-73.4% (% cellulose) released from enzymatic hydrolysis of pretreated Miscanthus residues. Among them, the highest yield of 73.4% for hexoses was obtained from 12% NaOH (w/v) solution pretreatment, whereas 1% CaO (w/w) and microwave pretreatment resulted in a lower hexose yield than the control (without pretreatment). The sugar yield from microwave followed with 1% NaOH pretreatment was 4.3 times higher than that of microwave followed with 1% CaO. However, the enzymatic hydrolysis efficiencies of the sample were 15.2% and 58.5% under microwave pretreatment followed by 12% NaOH or 12.5% CaO, respectively, which were lower than those of the same concentration of alkali (NaOH and CaO) pretreatments. To investigate the mechanism of varied enzymatic saccharification under different pretreatments, the changes in the surface structure and porosity of the Miscanthus-pretreated lignocelluses were studied by means of Fourier transform infrared, Congo red staining, and scanning electron microscopy analysis. The results show that the different pretreatments destroy the cell wall cladding structure and reduce the bonding force between cellulose, hemicellulose, and lignin to different degrees, therefore increasing the accessibility of cellulose and enhancing cellulose digestion.

Effect of Inoculum Concentration and Pretreatment on Biomethane Recovery From Cotton Gin Trash

The potential of cotton gin waste, a considerable challenge to the gin owners, has not been fully investigated as a renewable energy source via anaerobic digestion. The weathered cotton gin trash and inoculum for triplicate biomethane potential assays were obtained from a local cotton gin mill and a municipal wastewater treatment plant, respectively. The moisture, total solids, volatile solids, and C, H, N, S, hemicellulose + cellulose, and lignin contents of gin waste were determined in triplicates. The biomethane potential of untreated and pretreated (hot water and 6% NaOH (wet CGT weight basis) gin waste was determined at different inoculum to substrate ratios. The highest cumulative biomethane yield of 111.8 mL gvs-1 was observed in inoculum to substrate ratio of 2.3, and it was statistically similar to the values; 101.8, 104.7, 100.5, and 108.9 gvs-1, observed in 0.8, 1.2, 1.5, and 1.9, respectively. The biomethane yield at the inoculum to substrate ratio of 0.4 was significantly lower than all higher ratios. The T80-90 for biomethane production was 26-30 for the ISRs of 1.2, 1.5, and 2.3. The T80-90 for inoculum to substrate ratios of 0.4, 0.8, and 1.9 were 26-31, 27-32, and 27-31 d, respectively. The modified Gompertz equation fitted very well (R2 = 0.98-0.99) to the anaerobic digestion at all inoculum to substrate ratios and pretreatments as the observed and predicted biomethane values were similar. The model predicted a lag phase of 8-10 days for control and treatments compared to the observed of 10-15 days. The highest biodegradability of 24.8±2.6% was observed at inoculum to substrate ratio of 2.3, which was statistically similar to the values observed in ratios of 0.8, 1.2, 1.5, and 1.9, respectively. Among pretreatments, the highest biodegradability of 33.0±2.4 was observed in 6% NaOH pretreatment, and it was statistically similar to hot water treatment and non-pretreated or control. These research findings advance the knowledge in the anaerobic degradation of cotton gin trash, thus helping to maximize biomethane recovery from this agro-industrial waste.