Effect Of Biological Pretreatment Research Articles

Enhancement of Anaerobic Digestion of Corn Straw: Effect of Biological Pretreatment and Heating with Bio-Heat Recovery from Pretreatment

Biological pretreatment can promote the degradation of biomass and enhance methane production via the subsequent anaerobic digestion. In addition, a large amount of bio-heat can be generated during the pretreatment process to provide heat for the anaerobic digestion process. In this study, composite microorganisms were employed for pretreating corn straw. The impact of different pretreatment times and the heat generated by the pretreatment process on subsequent anaerobic digestion were studied. The results show that the maximum temperature of the pretreatment process was 56.2 °C, obtained on day 6. After 14 days of pretreatment, the degradation rate of the pretreatment group increased by 41% compared with the control group. As a consequence, straws with different pretreatment times were used for anaerobic digestion. The group that underwent 6 days of pretreatment and utilized bio-heat generated from pretreatment achieved the highest cumulative methane production of 401.58 mL/g VS, which was 60.13% higher than in the control group without pretreatment. After 6 days of composite microorganism pretreatment, the group that utilized bio-heat achieved a 29.08% increase in cumulative methane production compared to the group that did not utilize bio-heat. In conclusion, this study highlights the potential of biological pretreatment with composite microorganisms followed by anaerobic digestion using bio-heat as an effective method for treating corn straw.

Release of Fermentable Sugars from Corn Silage – The Effect of Biological Pretreatment

Release of Fermentable Sugars from Corn Silage – The Effect of Biological Pretreatment

Effect of Biological Pretreatment on Anaerobic Sewage Sludge Digestion: Using Growth Media for Methanogenic Bacteria and Kinetic Studies for Biogas Yield

Effect of Biological Pretreatment on Anaerobic Sewage Sludge Digestion: Using Growth Media for Methanogenic Bacteria and Kinetic Studies for Biogas Yield

Highly crystalline cotton spinning wastes utilization: Pretreatment, optimized hydrolysis and fermentation using Pleurotus florida for bioethanol production

Due to highly deleterious effects of physico-chemical pretreatment of lignocellulosic biomass to environment, the 2G biofuel production requires more sustainable and eco-friendly approach. During this study, the effect of biological pretreatment on fibrous cotton spinning waste mixture (CSWM) was investigated using solid-state cultivation of white-rot fungi, Pleurotus florida. The pretreatment with P. florida showed significant amount of lignin degradation (∼60 %w/w) and ∼80–85% of cellulose crystallinity reduction with the cellulose content of 80.7%w/w, after 14 days of pretreatment. This was also evidenced by Attenuated Total Resonance – Fourier Transform Infrared (ATR-FTIR) spectroscopy and Scanning Electron Microscopy (SEM). Optimization of hydrolysis conditions using Central Composite Design (CCD) resulted in the R-squared (R2) value and desirability of 0.97 and 0.95, respectively. The optimized conditions were biomass loading of 0.67%w/v and enzyme loading of 60 FPU/g of cellulose results in hydrolysis efficiency of ∼70% after 96 h. The hydrolysate, supplemented with mineral salts and 3 %v/v of inoculum, were maintained at anaerobic conditions with 32 ± 2℃ for 72 h. Optimum ethanol yield of 64 % (1.18 g/L) was obtained after 60 h of fermentation. This finding suggests that microbial pretreatment can effectively be employed for the sustainable and green production of bioethanol with more economical value.

Effect of biological pretreatment on metal extraction from flotation tailings for chloride leaching

This study focuses on investigating the extraction of gold, copper, iron, nickel, cobalt, and zinc present in the flotation tailings. The studied sample contained iron (3.56%), copper (0.09%), and gold (0.2 ppm) as major target elements, whereas cobalt (0.04%), nickel (0.03%) and zinc (0.04%) were trace elements of interest. Primarily, bioleaching with mixed acidophilic culture was applied as a pretreatment process for the recovery of nickel, cobalt, and zinc, as well as for iron removal. The effect of solid concentration (5–12.5%) in bioleaching was investigated at pH 1.8 and the temperature was kept at 32 °C. The highest extractions of nickel, cobalt, zinc, and iron at 5% and 7.5% solid concentrations in the bioleaching experiments were 90%, 60%, 86% and 67%, respectively. Dissolution of gold and copper was not observed. The residues from bioleaching pretreatment were applied for chemical chloride leaching to extract gold and copper into the solution. In chloride leaching, the highest extractions of copper and gold were 98% and 63%, respectively. In addition, residual nickel, cobalt, and zinc were dissolved into the solution with the extraction of 99%, 80%, and 90%, respectively. In all chloride leaching experiments, the highest extractions of iron, copper, gold, nickel, cobalt, and zinc were observed with biologically pretreated feed. Alternatively, residues from bioleaching were also subjected to conventional cyanide leaching. Dissolutions of copper, nickel, cobalt and zinc were shown to be higher in chloride solution, however, 7%-unit more of gold could be extracted by cyanidation. With these findings, it appears that the combination of biological pretreatment and chloride leaching can provide a non-toxic process for improved valuable metals extraction from low-grade tailings.

Analysis of biological pretreatment of rapeseed straw with white rot fungi for enzymatic hydrolysis

The effect of biological pretreatment on the rapeseed straw was evaluated by solid-state cultivation of white rot fungi Phanerochaete chrysosporium. P.chrysosporium degraded the lignin during the pretreatment, with enzymatic hydrolysis ratios increasing in the pretreated straw (3-fold after a 15 day pretreatment). The samples were identified by XRD, FTIR and SEM. X-ray analysis showed that pretreated samples had higher crystallinity than untreated samples (39.47% for a pretreated sample compared to 33.17% for untreated samples) and FTIR spectroscopy demonstrated that the content of lignocellulose also decreased during the biological pretreatment process. The surface characterization study showed morphological changes in pretreated samples. Moreover, the biological pretreatment slowed a plunge in hydrolysis rate during enzymatic hydrolysis.

Effect of biological pretreatment on flotation recovery of pyrolusite

Bacillus mucilaginosus was used in pretreatment of pyrolusite to facilitate the flotation removal of quartz from pyrolusite minerals. Quartz was activated by B. mucilaginosus, whereas pyrolusite was unaffected at pH 7 with laurylamine as collector. Flotation recovery of pyrolusite with B. mucilaginosus pretreatment is 73.62%, slightly lower than that of the process without biopretreament, namely 74.70%. The grade of concentrate of recovered pyrolusite is 19.44%, 2.18% higher than that of the recovered pyrolusite without B. mucilaginosus pretreatment (17.26%). The results of FTIR and SEM showed that no bacteria were adsorbed on the surface of quartz or pyrolusite, indicating that the better selectivity and collectability of flotation resulted from bacterial byproducts. And interaction of bacterial byproducts such as extracellular bacterial polysaccharide, extracellular bacterial protein and acetic acid, on minerals were studied by FTIR and adsorption.

Evaluation of Biological Pretreatment of Rubberwood with White Rot Fungi for Enzymatic Hydrolysis.

The effects of biological pretreatment on the rubberwood (Hevea brasiliensis), was evaluated after cultivation of white rot fungi Ceriporiopsis subvermispora, Trametes versicolor, and a mixed culture of C. subvermispora and T. versicolor. The analysis of chemical compositions indicated that C. subvermispora had greater selectivity for lignin degradation with the highest lignin and hemicellulose loss at 45.06% and 42.08%, respectively, and lowest cellulose loss (9.50%) after 90 days among the tested samples. X-ray analysis showed that pretreated samples had a higher crystallinity than untreated samples. The sample pretreated by C. subvermispora presented the highest crystallinity of all the samples which might be caused by the selective degradation of amorphous components. Fourier transform infrared (FT-IR) spectroscopy demonstrated that the content of lignin and hemicellulose decreased during the biological pretreatment process. A study on hydrolysis of rubberwood treated with C. subvermispora, T. versicolor, and mixed culture for 90 days resulted in an increased sugar yield of about 27.67%, 16.23%, and 14.20%, respectively, as compared with untreated rubberwood (2.88%). The results obtained demonstrate that rubberwood is a potential raw material for industrial applications and white rot fungus C. subevermispora provides an effective method for improving the enzymatic hydrolysis of rubberwood.

Structural change in wood by brown rot fungi and effect on enzymatic hydrolysis

The effects of biological pretreatment on Pinus radiata and Eucalyptus globulus, were evaluated after exposure to two brown rot fungi Gloephylum trabeum and Laetoporeus sulphureus. Changes in chemical composition, structural modification, and susceptibility to enzymatic hydrolysis in the degraded wood were analyzed. After eight weeks of biodegradation, the greatest loss of weight and hemicellulose were 13% and 31%, respectively, for P. radiata with G. trabeum. The content of glucan decreased slightly, being the highest loss of 20% for E. globulus with G. trabeum. Consistent with degradation mechanism of these fungi, lignin was essentially undegraded by both brown rot fungi. Both brown rot fungi cause a sharp reduction in the cellulose degree of polymerization (DP) in the range between 58% and 79%. G. trabeum depolymerized cellulose in both wood faster than L. sulphureus. Also, structural characteristic of crystalline cellulose were measured by using two different techniques – X-ray diffraction (XRD) and infrared spectroscopy (FT-IR). The biological pretreatments showed an effect on cellulose crystallinity structure, a decrease between 6% and 21% was obtained in the crystallinity index (CrI) calculated by IR, no changes were observed in the XRD. Material digestibility was evaluated by enzymatic hydrolysis, the conversion of cellulose to glucose increased with the biotreatment time. The highest enzymatic hydrolysis yields were obtained when saccharification was performed on wood biopretreated with G. trabeum (14% P. radiata and 13% E. globulus). Decreasing in DP and CrI, and hemicellulose removal result in an increase of enzymatic hydrolysis performance. Digestibility was better related to DP than with other properties. G. trabeum can be considered as a potential fungus for biological pretreatment, since it provides an effective process in breaking the wood structure, making it potentially useful in the development of combined pretreatments (biological–chemical). A viable alternative to pretreatment process that can be used is a bio-mimetic system, similar to low-molecular complexes generated by fungi such as G. trabeum combined pretreatments (biological–chemical).

Biological pretreatment of lignocelluloses with white-rot fungi and its applications: A review

Lignocellulosic carbohydrates, i.e. cellulose and hemicellulose, have abundant potential as feedstock for production of biofuels and chemicals. However, these carbohydrates are generally infiltrated by lignin. Breakdown of the lignin barrier will alter lignocelluloses structures and make the carbohydrates accessible for more efficient bioconversion. White-rot fungi produce ligninolytic enzymes (lignin peroxidase, manganese peroxidase, and laccase) and efficiently mineralise lignin into CO2 and H2O. Biological pretreatment of lignocelluloses using white-rot fungi has been used for decades for ruminant feed, enzymatic hydrolysis, and biopulping. Application of white-rot fungi capabilities can offer environmentally friendly processes for utilising lignocelluloses over physical or chemical pretreatment. This paper reviews white-rot fungi, ligninolytic enzymes, the effect of biological pretreatment on biomass characteristics, and factors affecting biological pretreatment. Application of biological pretreatment for enzymatic hydrolysis, biofuels (bioethanol, biogas and pyrolysis), biopulping, biobleaching, animal feed, and enzymes production are also discussed.

Biological pretreatment of lignocelluloses with white-rot fungi and its applications: A review

Lignocellulosic carbohydrates, i.e. cellulose and hemicellulose, have abundant potential as feedstock for production of biofuels and chemicals. However, these carbohydrates are generally infiltrated by lignin. Breakdown of the lignin barrier will alter lignocelluloses structures and make the carbohydrates accessible for more efficient bioconversion. White-rot fungi produce ligninolytic enzymes (lignin peroxidase, manganese peroxidase, and laccase) and efficiently mineralise lignin into CO2 and H2O. Biological pretreatment of lignocelluloses using white-rot fungi has been used for decades for ruminant feed, enzymatic hydrolysis, and biopulping. Application of white-rot fungi capabilities can offer environmentally friendly processes for utilising lignocelluloses over physical or chemical pretreatment. This paper reviews white-rot fungi, ligninolytic enzymes, the effect of biological pretreatment on biomass characteristics, and factors affecting biological pretreatment. Application of biological pretreatment for enzymatic hydrolysis, biofuels (bioethanol, biogas and pyrolysis), biopulping, biobleaching, animal feed, and enzymes production are also discussed.

Effect of biological pretreatment with Trametes hirsuta yj9 on enzymatic hydrolysis of corn stover

In this study, a newly isolated Trametes hirsuta yj9 was used to pretreat corn stover in order to enhance enzymatic digestibility. T. hirsuta yj9 preferentially degraded lignin to be as high as 71.49% after 42-day pretreatment. Laccase and xylanase was the major ligninolytic and hydrolytic enzyme, respectively and filter paper activity (FPA) increased gradually with prolonged pretreatment time. Sugar yields increased significantly after pretreatment with T. hirsuta yj9, reaching an enzymatic digestibility of 73.99% after 42 days of pretreatment. Scanning electron microscopy (SEM) showed significant structural changes in pretreated corn stover, the surface of pretreated corn stover became increasingly coarse, the gaps between cellulose fibers were visible, and many pores were developed. Correlation analysis showed that sugar yields were inversely proportional to the lignin contents, less related to cellulose and hemicellulose contents.

Effects of sterilization treatments on the analysis of TOC in water samples

Decomposition experiments conducted with and without microbial processes are commonly used to study the effects of environmental microorganisms on the degradation of organic pollutants. However, the effects of biological pretreatment (sterilization) on organic matter often have a negative impact on such experiments. Based on the principle of water total organic carbon (TOC) analysis, the effects of physical sterilization treatments on determination of TOC and other water quality parameters were investigated. The results revealed that two conventional physical sterilization treatments, autoclaving and 60Co γ-radiation sterilization, led to the direct decomposition of some organic pollutants, resulting in remarkable errors in the analysis of TOC in water samples. Furthermore, the extent of the errors varied with the intensity and the duration of sterilization treatments. Accordingly, a novel sterilization method for water samples, 0.45 μm micro-filtration coupled with ultraviolet radiation (MCUR), was developed in the present study. The results indicated that the MCUR method was capable of exerting a high bactericidal effect on the water sample while significantly decreasing the negative impact on the analysis of TOC and other water quality parameters. Before and after sterilization treatments, the relative errors of TOC determination could be controlled to lower than 3% for water samples with different categories and concentrations of organic pollutants by using MCUR.

Biomechanical Pulping of Agave sisalana

Summary The effect of biological pretreatment of sisal with several white rot fungi on the energy consumption in refining and on the mechanical properties of the pulps was evaluated in this investigation. Improvements were realized in all the mechanical properties (22–66 %) and a reduction in the energy consumption of > 39% was realized for the treated pulps with the different fungi. The best strength improvement and energy reduction results overall were obtained with the white-rot fungus, Ceriporiopsis subvermispora. The incubation time was optimized for this fungus with the optimum mechanical properties obtained with a two week treatment time.