Advanced Materials Research Vols. 1010-1012

Abstract: The effects of carbohydrate/nitrogen ratio (C/N) and pH on hydrogen production from waste activated sludge (WAS) were investigated. Firstly, the optimal pH value for hydrogen production was influenced by the C/N ratio, which was pH 10, 9, 8, 8, 8, 6, and 5, at the C/N ratio of 7 (sole sludge), 10, 15, 20, 25, 30 and 40, respectively. The maximal hydrogen production (100.6 mL/g-COD) was achieved at C/N of 25 and pH 8, which was due to the synergistic effect of carbohydrate addition on hydrogen pro-duction, the enhancement of sludge protein degradation and protease and amylase activities, and the suitable fermentation pathway for hydrogen production.

Abstract: As nanotechnologies become more widely used, titania nanoparticles are being released to the subsurface environment via wastewater sludge applications. Titania nanoparticles are not only toxic to organisms in the environment, but recent studies revealed that they may also serve as carriers of hydrophobic organic contaminants and affect their fate and distribution in the subsurface environment. The mobility of titania nanoparticles varies depending on nanoparticle morphology characteristics, pH and the ionic strength of solutions, flow velocity, nanoparticle concentration, and the presence of surfactant or natural organic matter. Analogous to findings for natural and engineered carbonaceous nanoparticles, titania nanoparticles may enhance the transport of hydrophobic organic contaminants in porous media. However, to prove this hypothesis, further research is necessary. Thus experiments examining the impacts of titania nanoparticle on the hydrophobic organic matter transport in porous media were designed, which consist of three different sets of column experiments. These experimental sets will investigate the effects of the presence of titania nanoparticles, the size of nanoparticles and the organic carbon content in soil, respectively. Due to the estimation of the potential for the titania nanoparticles to facilitate organic contaminant transport, the experiment results are expected as: (a) the presence of titania nanoparticles will enhance the organic contaminant transport in porous media; (b) smaller nanoparticles will adsorb more organic contaminants and enhance their transport as the result of the increasing specific surface area; (c) soil containing higher organic matter content will compete for the adsorption of organic contaminants and retard their facilitated transport by titania nanoparticles.

Abstract: Members belonging to the genus Brevibacillus had potentials in the bioremediation of hydrocarbon-contaminated soils. However, little is known about the fermentation medium and culture conditions of Brevibacillus panacihumi. The effect of concentrations of glucose and (NH₄)₂SO₄, initial pH value and culture temperature on the biomass of B. panacihumi W25 was measured with single factor experiments, which was a hydrocarbon-degrading bacterium. Polynomial regression analysis showed optimal concentration of glucose and (NH₄)₂SO₄, initial pH value and culture temperature were 45.2 g/L, 0.6 g/L, pH 7.3 and 30.3°C, respectively. The optimization of fermentation of B. panacihumi was reported for the first time.

Abstract: How to control and remediate the radionuclides-contaminated soil is attracting increasing attention. Researches on microbial solubilization of traces of ²³⁸U or ¹³⁷Cs in contaminated soil with Acidithiobacillus thiooxidans were conducted. The results show that ²³⁸U or ¹³⁷Cs can be solubilized by the strain, which can produce sulfuric acid steadily in liquid medium. In the 5th and 7th day the removal rate of ²³⁸U and ¹³⁷Cs were up to 78.71% and 81.48%, respectively. At the same time, the destroying of soil nutrients can be neglected

Abstract: Rhizoctonia solani Kühn is the causal pathogen of tobacco target spot, a major soilborne fungal pathogen that severely impairs yield and quality of tobacco worldwide. It is difficult to identify and quality the pathogen in plant and soil using conventional methods. In the study we developed a real-time, quantification polymerase chain reaction (QPCR) assay to detect and quantify R. solani AG-3 DNA from infected tobacco tissue and soil. Using a specific primer pair based on the internal transcribed spacer region of the fungal DNA sequence, R. solani AG-3 DNA at quantities as low as 100 fg of purified pathogen DNA could be successfully detect.

Abstract: The effects of pH adjustment method, pH value, UV light, catalase and Fenton reagent on the degradation efficiency of enzyme-Fenton reagent for methyl orange (MO) were investigated, and the synergetic catalytic effects of catalase and Fenton reagent on the catalytic oxidation for methyl orange were found. When under no UV-light, the enzyme can enhance the degradation efficiency of Fenton reagent. The optimum conditions for degrading methyl orange simulated wastewater whose concentration is 0.1 g/L at room temperature are obtained as follows: the pH is tuned with H₂SO₄, pH is 3.0, concentration of catalase is 5 μg / mL, concentration of H₂O₂ is 0.01%, concentration of FeSO₄ is 1.8μmol / L. The degradation rate can reach 98% in 60min. When under UV light at the same condition, the degradation rate can reach 94% in only 15min.

Abstract: Both single pollution index and integrated pollution index methods were employed in the present research to assess the heavy metals pollution of soil in the three Rosa roxburghii Tratt Planting Bases (located in Qianxi County and Qixingguan region in Bijie, Longli County in Qiannan), the baseline values of heavy metals in soils in Guizhou Province, Environmental Quality Standard for Soils (GB15618-1995) and Conditions of Green Food-tech0.nical Environmental Quality for Production Area (NY/T391-2000 and GB/T18407.1-2001) were applied as references. National Food Safety Standard-Contaminants in foods was applied to evaluate Rosa roxburghii Tratt fruits. The results suggest that the studied soil samples conformed to Environmental Quality Second Level Standard for Soils and Green Food-technical Conditions. The overall quality of the soil conditions was uncontaminated, but point source pollution phenomenon existed. Hg, Pb and Cu pollution were the main factors contributing to the rise in comprehensive pollution index from the three Rosa roxburghii Tratt Planting bases. It was found that levels of As and Cu did not exceed the limited standard of the soil，while Hg, Cr, Cd and Pb exceeded the standard in different degrees in studied Rosa roxburghii Tratt planting bases. The rates of excessive quota of Hg, Cr, Cd and Pb in the studied Rosa roxburghii Tratt fruits was 6.67%, 13.33%, 73.33% and 100%, respectively. The mean accumulation coefficient of Cd for Rosa roxburghii Tratt fruits was up to 1.20. The mean accumulation coefficients for concerned heavy metals were in the order of Cd > Cu > Pb > Hg > As> Cr. The relationships between concentrations of heavy metals in soil, leaf and stem samples were weak. However, significant correlations were found between concentrations of As in soil and leaf samples (r = 0.928), and concentrations of Cr between in soil samples and Cr in leaf samples (r = 0.733).

Abstract: To understand the effects of arsenic on enzyme activity of soil microorganisms in mining area, 18 soil samples were taken from Xinqiu open-pit mining area. The mechanism of soil microorganisms in response the change of arsenic concentration was studied by a pot experiment. The effects of arsenic on the activity of invertase, urease and catalase in soil microorganisms were characterized by enzyme activity experiment. The results showed that the microbial biomass in soil decreased with continuous elevated arsenic concentration. However, no significant effect was observed on the composition of microflora with the change of arsenic concentration. In soil microbial community, the predominant microorganism was bacteria (about 80%), then followed by actinomycetes and fungi. Most importantly, high concentration of arsenic obviously inhibited the activities of enzymes in soil especially for invertase and urease. The results obtained in this study provide additional insights into the microbial metabolic mechanisms under different concentration of arsenic in soil microbial community.

Abstract: AE (Acridine ester) artificial antigens were obtained by acridine ester coupled with KLH (keyhole limpet hemocyanin) and BSA (bovine serum albumin) in weakly alkaline conditions, respectively. These two kinds of antigens were identified by the ultraviolet absorption method, which showed that they were synthesized successfully. Balb/c mice were immunized with the AE-KLH for producing the McAb (monoclonal antibody) against AE, and then cell fusion was used. Two monoclonal antibodies against AE were acquired according to traditional procedure. One of anti-AE antibodies produced from the 1E8 cell lines was the IgG₃ subclass with a kappa-type light chain. An indirect competitive ELISA assay was developed. A linear relationship was observed over the concentration range from 0.25 to 10 ng/mL, and the detection limit was 0.125 ng/mL. The 50% inhibition concentration was 2.3 ng/mL. The monoclonal antibody against AE was successfully obtained.

Abstract: As the basis for toxicological tests, the culture conditions of Scenedesmus obliquus affect the progress of the experiment. The paper discusses the cases using aquatic fourth medium, BG11 medium and SE medium for Scenedesmus obliquus culture. In the physiological mechanism of Scenedesmus obliquus toxicity, the discussion is focused on the current research status and prospect.