Microfibers in anaerobic digestion: Effect of ozone pretreatment.

Wastewater treatment plants receive significant microplastics, which are eventually discharged into the environment. Previous studies indicated that over 90% of microplastics, especially microfibers from laundry wastewater, are retained in primary sludge. The effect of microfibers from household laundry on anaerobic digestion has yet to be fully understood, which is the objective of the present study. The results in this study showed a positive correlation between methane production and the presence of microfibers. Compared to the control, the methane production increased by 2%, 27% and 43% with 20 mg/L, 100 mg/L and 1000 mg/L microfibers spiked into primary sludge, respectively. The present study suggests that microfibers at 20 mg/L insignificantly affected methane production in controlled anaerobic digestion. In contrast, ozone pretreatment of microfibers enhanced gas production by 12% in the same concentration level. Interestingly, ozone pretreatment at a higher concentration (100 mg/L-1000 mg/L) of microfibers did not affect methane production. SEM/EDX results imply that the ozone pretreatment has changed the surface characteristics of the microfibers, which provide more surface area for adsorption. The significant reduction of soluble phosphorus by 58% indicates that microfibers potentially act as a site for adsorption during anaerobic digestion. Overall, the presence of microfibers had a positive effect on anaerobic digestion. However, this work also indicated that the microfibers were not biodegraded during anaerobic digestion. Therefore, microfibers accumulate on biosolids, potentially affecting the final disposal of microfibers.

Effect of Alkaline Black Liquor Recycling on Alkali Combined with Ozone Pretreatment of Corn Stalk.

In the early stage, the best conditions for alkali-bound ozone pretreatment were studied. But after treatment, the alkaline black liquor was directly discarded due to the large amount of organic matter, resulting in environmental pollution and waste of resources. In this paper, the alkaline black liquor was recycled under the optimal pretreatment conditions. The results showed that the number of alkaline black liquor cycles had little effect on hemicellulose content, and had a great influence on cellulose content and lignin content. Through structural characterization of corn stover, it was found that the pretreatment caused structural changes of lignin in straw. However, when the alkaline black liquor was recycled for the fourth time, the ether bond in the side chain of lignin and the covalent bond between the components were not sufficiently destroyed, and the damage to the phenolic hydroxyl group was also weakened. It was indicated that when the alkaline black liquor was recycled for the fourth time, the destruction effect of the alkaline black liquor on the straw was significantly inhibited. Therefore, the optimal circulation time of alkaline black liquor was three times, and the cellulolytic conversion rate was 81.53%.

Ozone-activated lignocellulose films blended with chitosan for edible film production.

This work focuses on the influence of ozone pretreatment on the fractionation and solubilization of sugarcane bagasse and soda bagasse pulp fibers in sodium hydroxide/urea solution, as well as the application of regenerated cellulose for producing edible films. The methodology involved pretreating lignocelluloses with ozone for 20 to 120 min before dissolving in sodium hydroxide/urea solution. The influence of the pretreatment conditions on cellulose dissolution yield was investigated. Regenerated cellulose films were then formed, with and without the addition of 2 % chitosan. Mechanical, physical, structural, thermal, and antimicrobial attributes were determined as a function of ozonation conditions of raw materials and chitosan content. The findings exhibited positive effects of short ozonation on enhancing mechanical strength, cohesion, and hydrophobicity. The prolonged ozonation of 120 min demonstrated optimal improvements in continuity, swelling, and antibacterial resistance of obtained films. Incorporating chitosan enhanced tensile performance, stiffness, and vapor barriers but increased moisture absorption. Tailoring the activation of biomass through ozone pretreatment and chitosan addition resulted in renewable films with adjustable properties to meet diverse packaging requirements, particularly for fruit protective coatings, ensuring the preservation of post-harvest quality.

Freeze-Drying Processes Applied to Melon Peel: Assessment of Physicochemical Attributes and Intrinsic Microflora Survival during Storage.

Melon peel is recognized as a source of healthy nutrients and oxidant compounds. Being considered a non-edible part with no profit value, large amounts of melon rinds are discharged by fruit industries. Innovative food ingredients with potential health benefits may arise if these parts were conveniently transformed. The objective was to freeze-dry small melon peel cubes to attain a potential edible matrix. An ozone pre-treatment was applied seeking decontamination purposes and quality retention. The effect of these processes was assessed in terms of physicochemical parameters (moisture content, water activity and color), bioactive compounds (total phenolics, vitamin C and chlorophylls) and antioxidant capacity, during 7 weeks of storage at room temperature. Intrinsic microflora (mesophylls, yeasts and molds) were also monitored. Results showed that the freeze-drying process allowed retention of the most bioactive compounds analyzed, except for total phenolic content. In this case, the ozone pre-treatment was important for phenolics preservation. During the storage period, ozonated samples presented a higher content of bioactive compounds. In terms of microflora, the ozone and freeze-drying effects were not significant. Freeze-drying proved to be a suitable preservation method for melon peel. The ozone impact was not relevant in terms of decontamination.

Bioethanol production from pistachio (pistacia vera L.) shells applying ozone pretreatment and subsequent enzymatic hydrolysis.

Pistachio (pistacia vera L.) is a lignocellulosic raw material. One of the most pistachio produced three countries in the World is Turkey and Sanliurfa is the city that most pistachio production in Turkey. As a result of this production, a large amount of pistachio waste is generated. Therefore, this study was conducted considering the abundant pistachio waste and furthermore, the effects of ozone and combined (ozone and hot water) pretreatments for bioethanol production from pistachio shells were investigated. Initially, the ozone and combined pretreatments were applied to the pistachio shells. It has been observed that applying the combined pretreatment provides better lignin removal than only ozone pretreatment and on the other hand, the ozone pretreatment provides better lignin removal than the hot water pretreatment. Scanning electron microscopy (SEM) images of pretreated and untreated pistachio shells were compared. Enzyme activity was measured, and 30-60 FPU enzyme loading was applied in an enzymatic hydrolysis. The enzymatic hydrolysis was applied to obtain fermentable sugar from the pistachio shells after pretreatments. As a result of enzymatic hydrolysis, 2.34-8.24 g/L reducing sugar was obtained. On the other hand, 1.21-2.33 g/L ethanol concentration was obtained end of the fermentation process. Fermentation efficiency was calculated between 42% and 55%. As a result, this study showed that combined pretreatment was more effective than the single pretreatment in the ethanol production process.

Effects and Mechanisms of Alkali Recycling and Ozone Recycling on Enzymatic Conversion in Alkali Combined with Ozone Pretreatment of Corn Stover.

In order to minimize waste liquor, save resources, and reduce costs, the effects of alkali recycling and ozone recycling on enzymatic conversion in alkali combined with ozone pretreatment of corn stover and the mechanism were studied. The results showed that as the number of cycles of alkali/ozone filtrate increased, the enzymatic conversion and the loss of reducing sugars showed a downward trend. It was indicated that the ability of alkali to damage lignocellulosic decreased with an increasing number of alkali circulation and the accumulation of lignin degradation products generated during ozonolysis inhibited enzymatic conversion. When the ozone filtrate was recovered and used for hydrolysis directly, the enzymatic conversion rates were basically the same compared with the first self-circulation of ozone filtrate, and no sewage was discharged. In conclusion, the optimal circulating pretreatment was four times alkali circulation and ozone filtrate was used as an enzymolysis liquid directly, and the conversion rates of cellulose and hemicellulose were 85.96% and 34.26%, respectively, saving 44% alkali consumption at the same time. This paper provided the theoretical basis for the development of lignocellulose pretreatment technology with low cost, high efficiency, and high conversion rate.

Treatment of pharmaceutical industrial wastewater by nano-catalyzed ozonation in a semi-batch reactor for improved biodegradability.

The study reports the biodegradability enhancement of pharmaceutical wastewater along with COD (Chemical Oxygen Demand) color and toxicity removal via O3, O3/Fe2+, O3/nZVI (nano zero valent iron) processes. Nano catalytic ozonation process (O3/nZVI) showed the highest biodegradability (BI = BOD5/COD) enhancement of pharmaceutical wastewater up to 0.63 from 0.18 of control with a COD, color and toxicity removal of 62.3%, 93% and 82% respectively. The disappearance of the corresponding Fourier transform infrared (FTIR) and gas chromatography-mass spectrometry (GC-MS) peaks after pretreatment indicated the degradation or transformation of the refractory organic compounds to more biodegradable organic compounds. The subsequent aerobic degradation study of pretreated pharmaceutical wastewater resulted in biodegradation rate enhancement of 5.31, 2.97, and 1.22 times for O3/nZVI O3/Fe2+ and O3 processes respectively. Seed germination test using spinach (Spinacia oleracea) seeds established the toxicity removal of pretreated pharmaceutical wastewater.

Degradation of ozonized tire rubber by aniline - Degrading Candida methanosorbosa BP6 strain.

Aniline-degrading yeast strain - Candida methanosorbosa BP-6 was tested for its ability to degrade ground tire rubber, treated and non-treated with ozone. The protein content, respiratory activity, critical oxygen concentration (COC) and emulsifying activity of the yeast strain were monitored during 21 day degradation process. The effects of biodegradation were evaluated using aldehyde detection, Scanning Electrone Microscope (SEM) and Fourier-transform infrared spectroscopy (FTIR) analysis. Pre-treatment of ground tire rubber with ozone resulted in lower microbial growth. However, metabolic condition of the C. methanosorbosa BP-6 yeast strain was higher in sample with ozonized tire rubber. Furthermore, the COC values in the last days of the process were about 30% lower regarding non-ozonized polymer. Also, the ozonization of tire rubber resulted in higher biosurfactant production of the yeast strain. The roughness and visible gaps in rubber matrix (SEM analysis) confirmed the ability of Candida methanosorbosa BP-6 yeast strain for tire rubber biodegradation.

Catalytic ozone pretreatment of complex textile effluent using Fe2+ and zero valent iron nanoparticles.

The study investigates the effect of catalytic ozone pretreatment via Fe2+ and nZVI on biodegradability enhancement of complex textile effluent. The nZVI particles were synthesized and characterized by XRD, TEM and SEM analyses. Results showed that nano catalytic ozone pretreatment led to higher biodegradability index (BOD5/COD = BI) enhancement up to 0.61 (134.6%) along with COD, color and toxicity removal up to 73.5%, 87%, and 92% respectively. The disappearance of the corresponding GCMS & FTIR spectral peaks during catalyzed ozonation process indicated the cleavage of chromophore group and degradation of organic compounds present in the textile effluent. Subsequent aerobic biodegradation of nZVI pretreated textile effluent resulted in maximum COD and color reduction of 78% and 98.5% respectively, whereas the untreated effluent (BI = 0.26) indicated poor COD and color reduction of only 31% and 33% respectively. Bio-kinetic parameters also confirmed the increased rate of bio-oxidation at enhanced BIs. Seed germination test using seeds of Spinach (Spinacia oleracea), indicated the effectiveness of nano catalyzed ozone pretreatment in removing toxicity from contaminated textile effluent.

Synergetic effect of combined pretreatment for energy efficient biogas generation.

Physiochemical disintegration of waste activated biosolids (WAB) through thermochemical (TC) pretreatment requires high energy and cost for efficient energy generation. Therefore in the present study, an attempt has been made to enhance the biodegrdability and to minimize the operational cost of TC pretreatment by combining it with ozonation. A higher solubilization of about 30.4% was achieved at lesser energy input of about 141.02kJ/kgTS and a ozone dosage of about 0.0012mgO3/mgSS through this combined thermo chemo ozone (TCO3) pretreatment. The methane production potential (0.32gCOD/gCOD) of TCO3 pretreatment was comparatively higher than the (0.19gCOD/gCOD) TC pretreatment. The energetic analysis and economic assessment of the proposed method of pretreatment can possibly reduces the energy requirement of TC pretreatment with a positive net profit of about 35.49$/ton of biosolids.

Effects of ozone pretreatment on viability of random pattern skin flaps in rats.

BACKGROUND: Medical ozone is a chemical agent that consists of three oxygen atoms and has antioxidant, angiogenic and vasodilator effects. This study evaluated the effects of medical ozone pre-treatment on flap survival. MATERIALS AND METHODS: Rats were divided into four groups of 10 rats each and a 9 × 3 cm McFarlane flap was used. Sham group: Neither surgical nor ozone pretreatment was used. CONTROL GROUP: No pretreatment was used after surgery. Preoperative ozone group: Preoperative 1 mg/kg ozone was given intraperitoneally for 7 days. No pretreatment was used after surgery. Postoperative ozone Group: Postoperative 1 mg/kg ozone was given intraperitoneally for 7 days. After postoperative 1 week, all groups were evaluated by surface area measurement, histopathology and electron microscopy. RESULTS: With the experimental McFarlane flap model, the experimental groups had better surface area measurements, along with histopathological and electron microscopic results when compared with the control group. CONCLUSION: Medical ozone had positive effects on flap survival due to its antioxidant, angiogenic and vasodilator qualities.

Simulation of the ozone pretreatment of wheat straw.

Wheat straw is a potential feedstock in biorefinery for sugar production. However, the cellulose, which is the major source of sugar, is protected by lignin. Ozonolysis deconstructs the lignin and makes cellulose accessible to enzymatic digestion. In this study, the change in lignin concentration with different ozonolysis times (0, 1, 2, 3, 5, 7, 10, 15, 20, 30, 60min) was fit to two different kinetic models: one using the model developed by Garcia-Cubero et al. (2012) and another including an outer mass transfer barrier or "cuticle" region where ozone mass transport is reduced in proportion to the mass of unreacted insoluble lignin in the cuticle. The kinetic parameters of two mathematical models for predicting the soluble and insoluble lignin at different pretreatment time were determined. The results showed that parameters derived from the cuticle-based model provided a better fit to experimental results compared to a model without a cuticle layer.

Acetone-butanol-ethanol (ABE) production by Clostridium beijerinckii from wheat straw hydrolysates: efficient use of penta and hexa carbohydrates.

ABE fermentation by Clostridium beijerinckii of steam-exploded and ozonated wheat straw hydrolysates was investigated. In steam-exploded hydrolysates, highest yields of 0.40 g/g ABE yield and 127.71 g ABE/kg wheat straw were achieved when the whole slurry from the pretreatment was used. In ozonated hydrolysates, 0.32 g/g ABE yield and 79.65 g ABE/kg wheat straw were obtained from washed ozonated wheat straw. Diverse effects were observed in steam explosion and ozonolysis of wheat straw which resulted in hemicellulose removal and acid insoluble lignin solubilization, respectively. SEM analysis showed structural differences in untreated and pretreated biomass. Depending on the operational strategy, after pretreatment and enzymatic hydrolysis, the glucose recovery ranged between 65.73-66.49% and 63.22-65.23% and the xylose recovery ranged between 45.19-61.00% and 34.54-40.91% in steam-exploded and ozonated hydrolysates, respectively. The effect of the main inhibitory compounds found in hydrolysates (oxalic acid, acetic acid, 5-hydroxymethylfurfural and furfural) was studied through ABE fermentation in model media.

Effect of ozone pretreatment on hydrogen production from barley straw.

Application of ozone technology to lignocellulosic biohydrogen production was explored with a barley straw. Ozone pretreatment effectively degraded the straw lignin and increased reducing sugar yield. A simultaneous enzyme hydrolysis and dark fermentation experiment was conducted using a mixed anaerobic consortium together with saccharification enzymes. Both untreated and ozonated samples produced hydrogen. Compared to the untreated group, hydrogen produced by the groups ozonated for 15, 30, 45 and 90 min increased 99%, 133%, 166% and 94%, respectively. Some inhibitory effect on hydrogen production was observed with the samples ozonated for 90 min, and the inhibition was on the fermentative microorganisms, not the saccharification enzymes. These results demonstrate that production of biohydrogen from barley straw, a lignocellulosic biomass, can be significantly enhanced by ozone pretreatment.