High Lignin Research Articles

The Effect of Ultrasonication and Delignification Treatment on the Sugar Released Value of Wood

The objective of these research was to study the impact of ultrasonication and delignification pretreatments in several wood species on their easiness for enzymatic hydrolysis, having the potential to be developed as the feedstocks for bioethanol production. Four different wood species from three botanical gardens in Indonesia have been selected, i.e., Gymnostoma sumatranum, Firmiana malayana, Pterocarpus indicus, and Alstonia scholaris, due to their higher sugar released values than a fast-grown tree, Sengon (Paraserianthes falcataria), when all were directly enzymatically hydrolyzed without pretreatment. The sugar released values after ultrasonication and enzymatic hydrolysis were between 3 – 5.5 mg/100 mg wood meal. When delignification pretreatment was performed, the sugar released values were higher than those with ultrasonication, ranging between 4 – 10.2 mg/100 mg wood meal. All the sugar released values after pretreatment were higher than those without pretreatment. Gymnostoma sumatranum was selected as the most potential wood species in this study due to its consistency among the species producing highest sugar released across different treatments. The SEM results showed that there was no significant changes in the morphological structure of the untreated fiber before and after enzymatic saccharification since it still had a complex structure due to the high lignin content. However, after the delignification treatment, the surface morphology of the fiber showed a decrease in the number of pits of the fiber, the surface residual of pits were reduced, parallel lines were more clearly visible, and the fiber structure was damaged with more small holes presented. The surface morphology of the fiber from the wood powder having delignification pretreatment supports the sugar released values which shows that the these values were higher than other treatments due to more recalcitrant substances were degraded, making it was easier for enzymes to break down cellulose. After ultrasonication, the SEM result showed less disrupted cell wall compared to after delignification which confirmed the higher sugar released data with delignification.

Removal of polystyrene microplastic from aqueous solutions with London Plane bark biochar: Pyrolysis temperature, performance and mechanism

The seasonally shed bark of London Plane tree is an ideal source for biochar due to its high lignin content. Microplastics derived from plastic wastes has become a hot topic due to its potential threats to ecosystems. The aim of this work is to convert the shed bark into efficient London Plane bark biochar (LBC) adsorbents and investigate its application in microplastics adsorption. The effects of pyrolysis temperature on LBC structure, surface properties and microplastic adsorption were investigated and the best adsorption performance of 60.05 mg/L was found at the 550 °C-pyrolyzed LBC. The wet sieve-weighing method was applied to assess the adsorption effect of LBC and verified with thermogravimetric analysis. The adsorption of polystyrene (PS) particles on LBC was in accordance with the Sips isothermal model and the second-order-kinetics model. The robustness of LBCs and the adsorption mechanism were investigated. With the analysis from pore size distribution, SEM images, FTIR and XPS spectra, physical trapping, surface complexation, hydrogen bonding and π-π interaction all play key roles in the adsorption of PS onto the LBC surface. This study not only provides a new approach for the removal of microplastics, but also offers a broad perspective on the treatment of biomass waste.

Production of High Purity Lignin from OPEFB: An Overview

Production of High Purity Lignin from OPEFB: An Overview

Sugarcane leaf litter biomass and its effects on increasing sugarcane drought stress tolerance and reducing CO₂ emissions

Burning biomass on sugarcane plantations can lead to pollution (CO₂ emissions) and degradation in soil properties. Adopting non-burning technology can increase the value of biomass by applying it directly to the soil, although this may result in nutrient immobilization, which can hinder optimal plant growth due to high lignin and cellulose content or high CN ratio. On the contrary, composting waste with a decomposer will boost plant nutrient availability and enhance other soil characteristics. This research was aimed to assess the effect of several types of sugarcane organic matter on improving soil characteristics, growth of sugarcane and the CO₂ emissions. The study was conducted using a Completely Randomized Factorial Design with two factors: type of organic matter (control, fresh litter and compost of sugarcane biomass) and level of drought stress (100, 75, 50 and 25%). Incubation occurred over 16 weeks, divided into two phases of 8 weeks each. The results showed that the application of organic materials in the form of compost could reduce water loss caused by environmental heat and sugarcane growing process. Furthermore, compost application improved soil chemical and biological properties by increasing soil pH, total nitrogen (N), total phosphate (P), total potassium (K), and the total microbial population, although differences were not significant compared to the control. Additionally, applying organic matter in the form of compost or litter helped suppress or reduce emissions, with compost treatment proving more effective than litter in reducing CO₂ emissions.

Green and Atom Economical Route to High Compressive Strength Lignin Oil-Sulfur Composites

Lignin is the most abundant natural source of aromatics but remains underutilized. Elemental sulfur is a plentiful by-product of fossil fuel refining. Herein we report a strategy for preparing a durable composite by the one-pot reaction of elemental sulfur and lignin oil comprising lower molecular weight lignin derivatives. A lignin oil-sulfur composite (LOS90) was prepared by reacting 10 wt. % lignin oil with 90 wt. % elemental sulfur. The composite could be remelted and reshaped over several cycles without loss of properties. Results from the study showed that LOS90 has properties competitive with or exceeding values for commercial ordinary Portland cement and brick formulations. For example, LOS90 displayed impressive compressive strength (22.1 MPa) and flexural strength (5.7 MPa). LOS90 is prepared entirely from waste materials with 98.5% atom economy of composite synthesis, a low E factor of 0.057, and lignin char as the only waste product of the process for its preparation. These results suggest the potential applications of lignin and waste sulfur in the continuous efforts to develop more recyclable and sustainable materials.

Ultraviolet Shielding Performance of Coconut Coir as a Filler in Low-Density Polyethylene (LDPE) Plastic Mulch

Plastic mulch is a layer of material applied to the soil surface to maintain moisture retention in the soil by preventing evaporation, reduce weed growth by blocking sunlight from reaching underlying weeds, and optimize fertilizer use by minimizing nutrient loss to the environment. However, the degradation of low-density polyethylene (LDPE), a thermoplastic commonly used for mulching, into microplastics due to exposure to UV radiation. This research explored the potential of coconut coir, a natural fiber with a high lignin content ranging from 30 to 46%, as a UV protective agent. The objective was to develop biodegradable plastic-based mulch composites that have better resistance to UV exposure by incorporating coir as a filler material in LDPE-based composites. Different ratios of coconut fiber were used (10%, 20%, 30%, and 40%), and Maleic anhydride grafted polyethylene (PE-g-MAH) was used as a binder at 2% of total weight mixed with LDPE in a rheomixer (80 rpm, 120°C for 10 min). The resulting plastic mulch bio-composites were evaluated for thermal, mechanical, UV resistance, and biodegradability properties. The results showed that the higher addition of coconut coir resulted in a decrease in the thermal and mechanical characteristics of the composite. However, the addition of higher coconut coir in the composite at 40% can provide an increase in the composite's resistance to ultraviolet light exposure, and the properties are easily degraded by the environment (biodegradable).

Blue light regulated lignin and cellulose content of soybean petioles and stems under low light intensity.

To improve light harvest and plant structural support under low light intensity, it is useful to investigate the effects of different ratios of blue light on petiole and stem growth. Two true leaves of soybean seedlings were exposed to a total light intensity of 200μmolm-2 s-1 , presented as either white light or three levels of blue light (40μmolm-2 s-1 , 67μmolm-2 s-1 and 100μmolm-2 s-1 ) for 15days. Soybean petioles under the low blue light treatment upregulated expression of genes relating to lignin metabolism, enhancing lignin content compared with the white light treatment. The low blue light treatment had high petiole length, increased plant height and improved petiole strength arising from high lignin content, thus significantly increasing leaf dry weight relative to the white light treatment. Compared with white light, the treatment with the highest blue light ratio reduced plant height and enhanced plant support through increased cellulose and hemicellulose content in the stem. Under low light intensity, 20% blue light enhanced petiole length and strength to improve photosynthate biomass; whereas 50% blue light lowered plants' centre of gravity, preventing lodging and conserving carbohydrate allocation.

Input of high-quality litter reduces soil carbon losses due to priming in a subtropical pine forest

To date, it is unclear how differences in litter quality affect soil organic matter (SOM) decomposition through a phenomenon called 'priming effects' (PEs), especially for low-fertility forest soils under field conditions. Here, the effects of low- and high-quality leaf litter on PE and microbial metabolism of litter-derived carbon (C) were explored in a low-fertility pine (Pinus massoniana) plantation. A 185-day in situ incubation experiment was carried out by adding two 13C-labeled leaf litters to the pine soil—a low-quality (high lignin: nitrogen ratio) litter sourced from pine and a broadleaved species Schima superba produced high-quality (low lignin: nitrogen ratio) litter. To determine the key microbial groups contributing to PEs, the abundance of 13C-labeled litter enrichment in soil phospholipid fatty acids (13C-PLFAs) was quantified. We found that high-quality litter decomposed more rapidly than low-quality litter, with both litter-derived CO2 efflux reaching a plateaued level during the experimental period. Low-quality litter induced net positive PEs, while high-quality litter induced net negative PEs during the litter decomposition processes. The 13C-PLFAs results showed that bacterial groups governed the negative PEs induced by high-quality litter, whereas fungal communities targeted the positive PEs induced by low-quality litter. Random forest model and variation partitioning analysis demonstrated that the direction and magnitude of PEs were driven by litter-induced changes in key microbial groups rather than the structure of the microbial community. Our results demonstrate that microorganisms preferentially utilized litter-derived C in high-quality litter treatment and SOM in low-quality litter treatment, respectively. In contrast to low-quality litter, adding high-quality litter promoted the microbial metabolism of litter-derived C, reducing SOM decomposition (strong negative PEs). Taken together, this study provides isotope-based suggestions for the improvement of degraded pine forests—introducing tree species that produce high-quality litter may benefit soil C sequestration by reducing soil C losses due to PE in nutrient-poor pine forests.

High extraction and excellent anti-UV and anti-oxidant proprieties of lignin from Reseda Luteola L. waste by organosolv process

Lignin is an abundant natural biopolymer found in plant cell walls. Lignin can come from tinctorial plants, whose residual biomass after dye extraction was typically discarded as waste. The main objective of this study was to extract lignin from the residual biomass of Reseda luteola L. using an organosolv process and to optimize the extraction conditions. The extracted lignin was characterized, and its potential applications as an antimicrobial, anti-oxidant, and anti-UV agent were investigated. Response surface methodology based on a Box-Behnken design was employed to optimize the lignin extraction conditions (organic acid concentration, material-to-liquid ratio, extraction time). The extracted lignin was comprehensively characterized using NMR, FTIR, XRD, SEM-EDX, TGA, DSC, and UV–Vis techniques. The optimal extraction conditions yielded a remarkably high lignin recovery of 62.41 % from the plant waste, which was rarely achieved for non-wood plants in previous works. The extracted lignin exhibited excellent thermal stability and radical scavenging anti-oxidant activity but no significant antimicrobial effects. Treating wool fabrics with lignin nanoparticles substantially enhanced UV protection from the “good” to “excellent” category based on the UPF rating. This sustainable valorization approach converted abundant tinctorial plant waste into high-purity lignin with promising anti-oxidant and UV-blocking properties suitable for various applications.

Lignin's complex role in lignocellulosic biomass Recalcitrance: A case study on bamboo

Lignin is widely recognized as a key factor influencing the recalcitrance of lignocellulosic biomass, yet the specifics of this relationship remain complex and not fully understood due to the complex interplay between lignin content variation and cell wall structure. Bamboo, which exhibits greater recalcitrance compared to wood in biorefinery processing, was chosen as the focus of investigation in this study. Three variants of Dendrocalamus farinosus with high, middle and low lignin contents were systematically analyzed and compared, in terms of molecular structure of lignin, hemicelluloses and cellulose, cell wall polymer spatial orientation, lignin-carbohydrate complex (LCC) linkages, cell wall geometrical size, as well as deconstruction efficiency, including delignification, alkaline extraction, and cellulose enzymatic hydrolysis efficiency. Findings reveal that an increase in lignin content generally lowers bamboo's deconstruction efficiency, but the mechanisms are more nuanced than previously thought. While lignin content variations do not significantly affect the molecular structure of xylan, cellulose and the chemical linkage type of LCC linkages, they do impact cellulose crystallinity, xylan orientation and notably, the thickness of fiber cell wall in the free fiber stands of bamboo. These findings highlight that lignin's role extends beyond mere physical protection of the cell wall, but also induces subtle variations in polymer structure and cell wall morphologies, which collectively influence the deconstruction efficiency of bamboo cell walls.

The comparison of hydrothermal, ultrasonication and microwave assisted alkalization of cellulose from Borassus flabellifer fruit husk

This study compares the effect of physical treatment to facilitate the alkalization of Borassus flabellifer fruit husk to produce microcrystalline cellulose. Alkalization using NaOH solution was combined with hydrothermal, ultrasonication, and microwave irradiation to achieve efficient lignin removal. Choosing the proper alkalization treatment is essential to enhance cellulose content and thermal stability while reducing surface corrugation of microcrystalline cellulose. High lignin separation was obtained using microwave-assisted alkalization followed by ultrasonication, conventional heating, and hydrothermal methods. Microwave irradiation offers rapid lignin removal from 11.8% to only 0.16 %, producing 74% cellulose content with the highest cellulose yield of 29.82%. Microcrystalline fibers with smooth morphology were produced at an estimated 51.42 μm diameter. The transition from cellulose I to cellulose II was evidenced by the shift of the FTIR band from 2924 cm−1 to 2895 cm−1 and the three characteristic peaks for cellulose II at 2θ = 12, 20.1 and 21.7° in XRD.

Optimization of banana fibers degumming by high temperature alkaline method and spinning

Banana fibers are a promising textile resource. However, due to their high gum and lignin content, the development of an efficient degumming method is crucial for their successful utilization. This article researches an improved traditional fiber degumming method using the high temperature alkali method, and the effects of sodium hydroxide concentration, time and temperature on the physical properties of banana fibers were investigated through a single factor experiment. The banana fibers were characterized with FTIR, XRD, SEM and chemical composition. The optimized process parameters of degumming can be achieved. The processing temperature was 140 °C and sodium hydroxide concentration was 10% for 1h. The weight loss and residual gum ratio of the fibers reached 51.84 and 4.13% respectively, the breaking strength was 5.57 cN/dtex, and the crystallinity was increased to 61.33%. These results demonstrate the effectiveness of this new degumming method. Additionally, the optimized banana fibers employed a softening process and were subsequently blended with cotton fibers at a 60/40 ratio for 60tex blended yarn. The breaking strength of the blended yarn was 6.22cN/tex, and the bacterial inhibition ratio was above 70%. This improved method is more suitable for mass production with a high degumming efficiency, and has great potential in the industry. Meanwhile, the excellent antimicrobial properties of banana fibers provide new ideas for development in bedding and clothing applications.

A sustainable synthesis of polyhydroxyalkanoate from stubble waste as a carbon source using Pseudomonas putida MTCC 2475.

Polyhydroxyalkanoates (PHAs) are biodegradable polymers that can be produced from lignocellulosic biomass by microorganisms. Cheap and readily available raw material, such as corn stover waste, has the potential to lessen the cost of PHA synthesis. In this research study, corn stover is pretreated with NaOH under conditions optimized for high cellulose and low lignin with central composite design (CCD) followed by characterization using Fourier-transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), and scanning electron microscopy (SEM). Design expert software performed further optimization of alkali pretreated corn stover for high total reducing sugar (TRS) enhancement using CCD using response surface methodology (RSM). The optimized condition by RSM produced a TRS yield of 707.19mg/g. Fermentation using corn stover hydrolysate by Pseudomonas putida MTCC 2475 gave mcl-PHA detected through gas c hromatography - t andem m ass s pectrometry (GC-MS/MS) and characterization of the PHA film by differential scanning calorimetry (DSC), FTIR, and nuclear magnetic resonance (NMR). Thus, this research paper focuses on using agriculture (stubble) waste as an alternative feedstock for PHA production.

Synergistic analysis of lignin degrading bacterial consortium and its application in rice straw fiber film

Fiber film have received widespread attention due to its green friendliness. We can use microorganisms to degrade lignin in straw to obtain cellulose and make fiber films. Herein, a group of high-temperature (50 °C) lignin degrading bacterial consortium (LDH) was enriched and culture conditions for lignin degradation were optimized. Combined with high-throughput sequencing technology, the synergistic effect of LDH-composited bacteria was analyzed. Then LDH was used to treat rice straw for the bio-pulping experiment. The results showed that the lignin of rice straw was degraded 32.4 % by LDH at 50 °C for 10 d, and after the optimization of culture conditions, lignin degradation rate increased by 9.05 % (P < 0.001). The bacteria that compose in LDH can synergistically degrade lignin. Paenibacillus can encode all lignin-degrading enzymes present in the LDH. Preliminary tests of LDH in the pulping industry have been completed. This study is the first to use high temperature lignin degrading bacteria to fabricate fiber film.

Assessment of Lignin Residues from Bioethanol Production of Olive Stones as Green Chemical Thickener of Epoxidized Linseed Oil

This work focused on the characterization of lignin residues from bioethanol production of olive stones (OS) and the use of these residues to chemically thicken epoxidized linseed oil (ELO). OS were processed by an acid/steam explosion pretreatment, followed by pre-saccharification, using different enzyme dosages, and simultaneous saccharification and fermentation. The chemical composition of the OS lignin residues was analysed, revealing a high lignin content (66.6–69.5%), and lower quantities of glucan (17.4–19.3%) and xylan (2.8–2.9%). Whereas, the structural properties of OS lignin residues were characterized by Fourier-transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR), thermogravimetric analysis and size exclusion chromatography (SEC). OS lignin residues displayed the main inter-unit linkages (β–β′ resinol (51.0–59.0%), followed by β-O-4′ alkyl aryl ethers (27.0–35.2%) and β-5′ phenylcoumaran (11.4–13.2%) substructures), high molecular weights (22,000–25900 Da), low S/G ratios (1.2–1.5) and phenolic groups content (48–55 mg GAE/g lignin). Moreover, OS lignin residues were dispersed in ELO to obtain thickened formulations, which were characterized by FTIR and NMR. Oil thickening was achieved by promoting the chemical crosslinking between lignocellulose hydroxyl groups and ELO epoxy groups, enabling the compatibilization of both components. Up to tenfold viscosity increment of the resulting thickened formulations in relation to ELO’s viscosity was observed. Besides, thickened formulations exhibited viscoelastic properties, evincing oil structuration to some extent.Graphical

Functional identification of CCR1 gene in apple (Malus halliana) demonstrates that it enhances saline-alkali stress tolerance

BackgroundLignin is a complex aromatic polymer that plays an important biological role in maintaining plant structure and defending plants against biotic and abiotic stresses. Cinnamoyl-CoA reductase (CCR) is a key enzyme involved in the lignin synthesis-specific pathway and regulates lignin biosynthesis and accumulation.MethodsBased on transcriptome data, MhCCR1, which was significantly induced by saline-alkali stress, was cloned from Malus halliana. The physicochemical properties, evolutionary relationships and cis-acting elements were analyzed. We obtained transgenic materials by heterologous transformation of MhCCR1 into Arabidopsis thaliana and tobacco, as well as homologous transformation into apple callus, and characterized their saline-alkali stress resistance by a series of physiological and biochemical experiments. And yeast two-hybridization technique was applied to screen and validate the interacting proteins.ResultsWe found that overexpression of MhCCR1 enhanced the tolerance of A. thaliana, tobacco and apple calli under saline-alkali stress, and caused a variety of physiological and biochemical changes. As compared to the wild type, the transgenic plants showed better growth, higher lignin, chlorophyll and proline contents, lower conductivity and MDA content, and significant increase in antioxidant enzyme activities (SOD, POD, CAT) in the transgenic lines under stress condition. In addition, expression of saline-alkali stress-related genes in overexpressed A. thaliana were also higher than in WT, including the antioxidant genes, the Na+ transporter genes, and the H+-ATPase genes, while expression of the K+ transporter genes displayed opposite changes. Meanwhile, the expression levels of genes related to lignin synthesis, AtPAL1, AtCOMT, AtC4H, At4CL1, and AtCCOAOMT, were also significantly up-regulated. At last, the Y2H experiment confirmed the interaction between MhCCR1 and MhMYB4, MhMYB1R1, MhHXK, and MhbZIP23 proteins.ConclusionsThese results suggest that MhCCR1 may play a positive regulatory role in saline-alkali tolerance of transgenic lines by regulating the lignin content, osmoregulatory substances, chlorophyll content, antioxidant enzyme activities, and genes related to saline-alkali stress, thus providing excellent resistance genes for the stress-responsive regulatory network of apples, and providing a theoretical basis for the cultivation of saline and alkali-resistant apple varieties.Graphical

The impact of different management on pine-based agroforestry system and litter accumulation on the population and activity of cellulolytic bacteria

Abstract. Arfarita N, Nuraini Y, Rinady MVP, Noerhayati E, Prayogo C. 2024. The impact of different management on pine-based agroforestry system and litter accumulation on the population and activity of cellulolytic bacteria. Biodiversitas 25: 924-936. Agroforestry leads to the accumulation of organic matter, and the environmental conditions, litter quality, and decomposing organisms influence the rate at which litter decomposes. Litter decomposition in agroforestry systems is slow due to the high lignin and phenolic substances content, low light intensity, and high humidity under the canopy's shading condition. Therefore, a study was carried out to address this issue to isolate cellulolytic bacteria capable of breaking down plant litter using a qualitative cellulase activity testing method. The complete randomized block design and Tukey's test were used to determine the treatment's significance. Six agroforestry systems were examined: pine-coffee, pine-banana, pine-cardamom, pine-cardamom, mixed garden, and citrus. The PK (Pine-Coffee) plot had the highest canopy cover, litter density, and cellulolytic bacteria. The study identified three cellulolytic bacteria isolates (PK1, PK13, and PK10) from the 50 isolated bacteria of PK plot, producing the largest clear zones on CMC media. These identified isolates belonging to the Bacillus genus were Gram-positive bacteria with rod-shaped cells. The different types of litter in agroforestry systems affect the content of lignin, polyphenols, cellulose, and C/N ratios, which can influence the abundance of cellulolytic bacteria and their potential cellulase activity.

Performance of castor oil polyurethane resin in composite with the piassava fibers residue from the Amazon

The use of castor oil in producing polyurethane resins has been identified as one of the most promising options for the industry. The piassava fibers waste generated by the industry on a large scale presents excellent properties as a reinforcing agent due to its high lignin content characterized by chemical tests and FTIR. Composite boards consisting of a higher content of mercerized piassava fibers (10 mm, 85 wt.%) reinforced polyurethane castor oil-based resin (prepolymer (PP) and polyol (OM)) exhibited excellent performance. Composites with these properties have strong potential for medium-density applications ranging from biomedical prosthetics to civil partition walls and insulation linings. Alkali treatment removed the superficial impurities of piassava fibers, activating polar groups, and physical characterization reported excellent performance for all composites. Among the composites, the CP3 sample (composite reinforced with piassava fibers (85 wt.% fibers; 1.2:1—PP:OM)) stood out with higher density and lower swelling and water absorption percentage than other composites. FTIR results indicated NCO traces after the resin cured in the PU3 (1.2:1—PP:OM), possibly contributing to the interaction with the fibers. DMA results reported relevant information about more flexibility to CP1 (composite reinforced with piassava fibers (85 wt.% fibers; 0.8:1—PP:OM)) and CP3 than CP2 (composite reinforced with piassava fibers (85 wt.% fibers; 1:1—PP:OM)). The results suggest that the proper combination with natural products must lead to composites with potential applications as engineering materials.

Can wood waste be a feedstock for anaerobic digestion? A machine learning assisted meta-analysis

Anaerobic digestion is widely employed to process various organic wastes while generating renewable energy and nutrient-rich digestate. However, lignocellulosic wastes, especially wood waste, suffer from the recalcitrance associated with high lignin content, thereby adversely impacting on biogas production. It remains unclear whether wood waste is suitable as a feedstock for anaerobic digestion and to what extent pretreatment techniques could affect its biochemical methane potential. In this paper, 769 datasets on methane production from wood waste were collected for meta-analysis. The results showed an average 146 % increase in methane production for other organic wastes compared to wood waste when pretreatment techniques were not applied, but this gap could be mitigated to 99 % when pretreatment techniques were considered, indicating that pretreatment techniques could be more effective for wood waste. A further analysis of different pretreatment techniques showed that pretreatment significantly increased the methane production of wood waste by 113 % and that a combination of pretreatment techniques was more effective than a single method. Finally, three machine learning algorithms were applied to explore the relationship between methane production and selected variables. The results showed that the random forest method yielded better predictive performance for methane production (R2 = 0.9643) than artificial neural networks and support vector regression. Feature importance analysis found that particle size had a higher influence than temperature or feedstock composition. Overall, this study gives insight into the potential of utilizing wood waste as a feedstock for anaerobic digestion and the importance of employing suitable pretreatment methods. This work also reveals correlations between methane production and critical variables, which could serve as a guide for optimizing operational adjustments during anaerobic digestion.

Experimental Investigations on the Effect of Pretreatment in Anaerobic Digestion of Coir Pith Agro Waste

The coir industry in India’s southern coastal regions, especially in the state of Kerala, is becoming increasingly concerned about the environmental impact of the accumulation and incremental increase of coir pith each year. The objective of this study was to assess the effect of pretreatment on the anaerobic digestion of coir pith. The characterization study of coir pith shows high organic content, which can be anaerobically digested to produce biogas. But, the high lignin content (30.91%) makes the process slow. To overcome this, a biological pretreatment method was tried using two microbial cultures belonging to fungal genera known to be lignin decomposers, viz., Trichoderma and Pleurotus. By using Trichoderma, lignin content was reduced by 3.7%, and the maximum gas production was obtained in a shorter time (19 days) in comparison with the sample without any pretreatment (24 days). When Pleurotus was used for lignin degradation, the lignin content was reduced by 6.78%, and the maximum gas production was obtained in a much shorter time period (14 days) in comparison with the former two methods. The gas produced comprises 74 ppm of methane, which has fuel value. The sludge after digestion was tested, which indicated a marginal increase in NPK value and hence can be used as fertilizer. The results of the study appear to be quite promising in the transition towards green energy by providing scope for the process of biomethanation, with the conclusion that further research can transform coir pith into a good renewable energy resource.