Papers by Keyword: Biodegradation

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Authors: Z.M.F Tajuddin, A. Rashid Azura
Abstract: Degradation for biodegradable natural rubber (NRL) films by Bacillus megaterium sp. is investigated. A common soil bacterium, Bacillus megaterium sp. is one of the largest eubacteria. This bacterium has large potential in degradation process for biodegradable natural rubber latex film. Specified method is used to cultivate the bacteria using suitable media. The growth of bacteria is studied through optical density and dry weight as a function of time. The optical density at specific wavelength with different stages of bacterial growth is used to determine their mid-log growth phase of the cell. The optimum time achieved to insert NRL films is between 17 to 20 hours of incubation period. Growth curve of Bacillus megaterium sp. gives an equation of Y=2.3401X. The biodegradation behaviour of Bacillus megaterium sp. is further investigated to access the viability as accelerating media for biodegradation of NRL films.
Authors: Xin De Cai, Dong Ying Wang, Hui Li, Shi Yin Li, Lai Guo Chen
Abstract: A static aeration biopile process was used to bioremediate polycyclic aromatic hydrocarbon (PAH)-contaminated soil using four different approaches for treating about 30 m3 of soil at a former oil-producing site. The four treatments investigated were as follows: (i) fertilizer plus bulking agent (FB); (ii) fertilizer, bulking agent, plus Tween 80 (FBT); (iii) fertilizer, bulking agent, Tween 80, plus fungi agent (FBTF); and (iv) fertilizer, bulking agent, bacterial inoculum, plus fungi agent (FBBF). After bioremediation for 320 days, the total amount of 16 PAHs ranged from 4.14 to 5.31 mg/kg in the final soil, removal rates ranging from 75.5% to 81.5%. The sum concentration of seven carcinogenic PAHs decreased down to 0.15 mg/kg. The values of the total toxicity equivalence concentrations for 16 PAHs ranged from 0.014 to 0.068 mg/kg. The removal rates of the 16 PAHs in these four different treatments decreased in order FBBF > FBT > FBTF > FB.
Authors: Iveta Štyriaková, R. Hampl, I. Jech
Abstract: To examine the effects of organic and inorganic amendments on the degradation of petroleum hydrocarbons, we conducted a pilot-scale experiment during the winter and summer periods. Soil samples were analyzed periodically to determine the soil gas amount of volatile organic compound, carbon dioxide flux, consumption of O2 and indigenous bacterial numbers during bioremediation. The initial level of the most contaminated site (10 070 mg hydrocarbon kg-1 soil) was reduced successively to 4 800 mg kg-1 after 4 months and to 1 400 mg kg -1 after 6 months in ex-situ amended soils. The hydrocarbon-degrading microbial populations increased during the treatment as also did soil respiration. Both aerobic and methanogenic conditions appeared to be important at these sites. Methane concentration (500-23 000 ppm) and CO2 production (800-17 000 ppm) varied with the extent of contamination. The bioventing system used in this study aerated a wide area of soil. It was concluded that N and P availability within the organic and inorganic nutrients limited the biodegradation of hydrocarbon contamination. By combination of organic and inorganic amendments a 86% removal efficiency was achieved. Nutrient diffusion varied within the 3 m high decontamination biopile but was sufficient to promote bacterial proliferation in all layers.
Authors: Paul Rosemann, Susanne Bender, Andreas Heyn, Jürgen Schmidt
Abstract: As bio-absorbable implant material the magnesium alloy Mg-1Ca is able to degrade in-vivo. The mechanical properties of this alloy are similar to those of human bone; both Mg and Ca are essential elements in human body. The main problem is the high corrosion rate of this alloy. Two coating systems based on plasma-chemical oxidation and an organic dip coating are applied onto MgCa1.0 magnesium alloy in order to slow down the corrosion rate. The corrosion behaviour of the coated alloys was investigated with electrochemical noise measurements. The influence of hydrogen evolution and increasing pH-value on the cytotoxicity was examined. The results of these investigations suggest that a combination of both coating systems leads to promising degradation properties.
Authors: Chun Lan Lu, He Yan Dong, Wei Wang, Gang Yang
Abstract: Magnesium alloys are very biocompatible and show promise for use in implant device. The focus of this article lies in the evaluation of the degradation performance and biological response of a paclitaxel-eluting biodegradable stent based on WE43 magnesium alloy by in vivo and in vitro studies. The corrosion characteristics analyzed by immersion testing in phosphate buffered solution (PBS) for 24h. Severe corrosion took place reveal fast degradation, lead to the stent strut easily fracture during expanding. The chemical nature of this conversion in vivo was investigated by scanning electron microscope (SEM) equipped with energy dispersive spectrum (EDS). For the endothelial surface coverage and the microstructure of the stent were also investigated by SEM. The results show that the deployment of the stent in arteries was safe, endothelial coverage occurred above stent struts and between struts after implanted 6 weeks, and more slowly than stainless steel stent and paclitaxel-eluting stainless steel stent. The grains boundaries of the stents are easily corroded in vivo environment, which should strongly affect the radial strength and mechanical integrity of the stent, leading early recoil contribute to restenosis.
Authors: Yang Liu, Kun Ming Dong, Li Miao, Xiao Jian Zhou, Cui Li Jin, Wei Yang Bao, Wei Jiang
Abstract: The 4-t-octylphenol (4-t-OP) biodegradation by alginate immobilized cells of Acinetobacter sp. was compared with its respective free cells in different media. The effects of different bead densities, pH values and practical applications of artificial seawater and wastewater on the biodegradation rate of 4-t-OP were investigated. Degradation kinetics of 4-t-OP by free and immobilized cells was well fitted with first order kinetic. The immobilized Acinetobacter sp. cells could enhance the efficiency of 4-t-OP degradation. The degradation rate and 4-t-OP half-life were 97.6% and 0.7 d, respectively. Increasing level of bead amount could also improve the degradation effects, when 400 beads per 100 mL were added, the degradation rate and 4-t-OP half-life were 96.5 % and 0.2 d respectively. The immobilized Acinetobacter sp. cells could degrade 4-t-OP both in artificial seawater and wastewater. The degradation rates were 87.7% and 84.3%, respectively, indicating its potential application of removing and biodegrading 4-t-OP under practical environment.
Authors: Bo Wu, Chang Lu Wang, Ya Qiong Liu, Dong He, Mian Hua Chen, Yu Rong Wang, Feng Juan Li
Abstract: . A castor oil-based detection method for the analysis of biological degradation was established on the base of CEC-L-33-A-93 test method and the domestic conventional experimental methods. Difference of the test samples between the experimental and published values was less then 0.50%. Maximum error of degradation rate was 1.92% in parallel experimental. Compared to the domestic conventional methods, degradation rate obtained by the improved analysis methods of castor oil-based is approximately higher than 5.0%. Meanwhile, analysis and detection method of DIOS with advantage of high accuracy, conveniency and good reproducibility is established and showed stability by studying the correlation of parallel samples that the coefficient of variation is less than 5%.
Authors: Ting Ting Yan, Si Yu Wu, Qing Hua Chen, Qing Mei Liu, Jia Rong Yang
Abstract: Mg and its alloys draw more and more attentions to be used as biodegradable medical materials. But the rapid degradation of those materials limits their clinical applications. In this article, a phosphate coating was prepared on AZ31B magnesium alloy to improve its anti-corrosion property. Morphology, composition and corrosion resistance of the coating were studied. The SEM research showed that the coating that composed of rod-like phosphates with small amount of random distributed micro-voids was approximately10-20μm in thickness. The XRD analysis indicated that the coating was mainly composed of MgO, Mg3(PO4)2and Zn3(PO4)2·xH2O. Electrochemical test showed the phosphate treatment could significant improve the corrosion resistance of AZ31B.
Authors: Yogesh Patil, Prakash Rao
Abstract: The key objective of present study was to find out a novel and innovative strategy to tackle problem of cyanide and metal-cyanide pollution thereby leading to indirect mitigation of global warming. Studies were performed to test the feasibility of treating aqueous waste containing free cyanide (CN-) and copper-cyanide {Tetracyanocuprate - TCC, [Cu (CN)4]-2} using microalgae Scenedesmus sp. that was isolated by enrichment culture technique under alkaline conditions. Results revealed that microalgae Scenedesmus sp. was capable of detoxifying cyanide and TCC (10-25 mg/l as CN-) with an efficiency of >99% under aerated, static and illuminated conditions within a period of 48-96 h. Process parameters like pH (7-11), temperature (20-45°C), initial cell density (103-106 cells/ml) and varying concentration of cyanide and TCC (5-50 mg/l as CN-) were optimized. Of the total copper ions released during biodegradation of TCC, 37% was adsorbed on the cells, while 67% was accumulated by Scenedesmus cells.
Authors: Duongruitai Nicomrat, Jirasak Tharajak
Abstract: Tensile strength test for paper has been regularly used in measurement of paper quality in the industry. In this study, changes in properties of paper during biodegradation were compared by measurement of the tensile strength cellulose activity. Samples of filter paper and polyethylene coated paper were digested with cellulose degrading Bacillus isolates. Treatment with water was used as a negative control. The paper samples were cut into precise shape according to the standard protocol of mechanical tensile strength test to measure the maximum tensile force. After removing bacterial biomass, reducing sugars were measured as a surrogate for callulase activity in the spent fermentation broth and the paper samples were subjected to the mechanical strength, breaking load and stretch tests. The results showed the amount of stretch in paper was critically reduced over longer contact time in bacterial culture. Changes in the mechanical strength were apparent within 3-7 days of contact time, whereas changes in reducing sugars were observed only after 7-10 days of incubation depending on the paper type. In filter paper samples, more reducing sugars and less mechanical strength indicated increased biodegradation of the cellulose matrix. Overall, the mechanical tensile strength test was deemed an early indicator for paper biodegradation that may have commercial application.
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