Advanced Materials Research Vols. 183-185

Abstract: Biosorption has been developed as an effective and economic method to treat wastewater containing low concentrations of metal pollutants. In this study, a bacterium, Citrobacter freudii, was used as a biosorbent to adsorb uraniumions. The factors which influence the adsorption of uranium by Citrobacter freudii were investigated, including pH, the strain dosage and the initial concentrate of uranium. The results showed that the adsorption efficiency increased with the increased of pH in the beginning of the adsorption and reached its maximum at pH 6; when the strain dosage and the initial concentrate of uranium were 6.0g/L and 20mg/L, respectively, the adsorption efficiency reached 93.89% and 94.68%, respectively. The authors investigated the active sites of bacteria for biosorption and the results proved that carboxyl in the cell wall played an important role in biosorption.

Abstract: Objective: A convenient PCR was used for site-directed mutagenesis to modify structure of proteins or peptides, For function-structure studies of proteins or peptides. Method: the one-step PCR site-directed mutagenesis strategy can introduce mutation of gene through 5^/-end of primer, which was applied on peptide Erabutoxin B (EB) to produce three mutants of EB, the activity of mutants was detected by LD50 value of mice. Result: S8Y, R33D, K47R three mutants of EB were obtained by one-step PCR, LD₅₀ of mutants indicated that the activity of mutants decreased in different degree, the activity of R33D was nearly deprived. Conclusion: one-step PCR site-directed mutagenesis was convenien and efficient, it can be applied on restructuring the primary structure of proteins or peptides.

Abstract: The combined process which consisted of a four-stage contact baffled reactor followed by a five-stage plant filter bed was used to treat domestic wastewater. The start-up of the four-stage contact baffled reactor was investigated, and the efficiency of the combined technology treating domestic wastewater was studied. The results indicated that the four-stage contact baffled reactor which inoculated with anaerobic sludge could be started up in 52 d, and the proper hydraulic residence time was 24 h; when the four-stage contact baffled reactor was running stably, its average COD_Cr removal efficiency was 57.0%, and in the four-stage contact baffled reactor, the average COD_Cr removal efficiency of each stage was decreased gradually, which were 45.8%, 11.1%, 6.8% and 3.3%, respectively; when the influent COD_Cr was 276-370 mg/L, the effluent COD_Cr of the combined technology was 73.0-90.7 mg/L and the average COD_Cr removal efficiency of the combined technology was 75.0%.

Abstract: The hydrated cerium oxide (CeH) was synthesized and it was loaded on amino methylene phosphonic acid resin (APAR) to form the hybrid adsorbent CeH-APAR. The structure and thermal properties of CeH-APAR were tested by FTIR and TGA. And then, it was investigated that pH values and temperatures affected the adsorption property of CeH and CeH-APAR for fluoride ion. The results showed that CeH-APAR hybrid sorbent formed by Ce⁴⁺ and APAR with coordination bond is relatively stable below 270°C. Its adsorption property is similar to that of CeH, i.e. it is less affected by pH value, so it can be used in a wide pH range. Besides, under a stable pH, adsorption capacity of CeH-APAR also increases along with increasing temperature. As a result, it is a temperature-controlled sorbent and belongs to chemical adsorption.

Abstract: Sulfate-reducing bacteria (SRB) was concentrated cultured and used to treat wastewater containing polyacrylimade. Viscosity loss was selected to indicate degradation of polyacrylimade. The experimental results show that SRB can be obtained from oil refinery wastewater. Suitable pH value, inoculation amount and polymer concentration for SRB were 7, 1% and 250mg/L to 400mg/L, respectively. The results also show that treatment of wastewater containing polymer by SRB is a perspective method.

Abstract: In order to investigate the feasibility of pre-treatment of drinking water treatment plant by the constructed wetland and provide the operation parameters for a full scale constructed wetland to improve the quality of raw water. The constructed wetland series process was used to pre-treat influent water of drinking water treatment plant based on raw water of the Song hua jiang River. The results showed that when the influent flux was 1m³/d, the average removal rates of Turbidity, COD, TN and NH₄⁺-N in the constructed wetland system were 94.27%, 56.77%, 2.37% and 55.65% , respectively. The wetland system has high treatment effect and run stably in the pretreatment process of the raw water. This system could lighten the load of the conventional water treatment processes effectively.

Abstract: Differences in physicochemical properties of starch isolated from red bean and mung bean, including chemical composition, amylose content, starch granule morphology, swelling power and solubility, thermal properties and freeze-thaw stability were compared. There was no significant difference on the chemical compositions between the two starches. Most of the granules of red bean starch was oval or elliptical, the diameter was between 9.54 μm-30.98μm, the granules from mung bean starch was round or oval, the diameter was between 10.50 μm-27.59μm; The extent of solubility in mung bean starch was significantly higher than red bean starch between 60 and 90°C, the temperature that the swelling power began to increase obviously of mung bean starch was higher than that of red starch at 60 to 90°C. T_o, T_p, T_c andΔH of red bean starch were higher than that of mung bean.

Abstract: It has been increasing the interest in the study of alternative pulping processes that conciliate high performance and protection to the environment. In the same way, the use of agricultural residues has been more and more reminded as promising raw material for production of bioethanol and chemical products. The wheat straw is a very abundant agricultural residue and it has been used in many countries for the production of cellulosic pulps. This work describes the effect of the pretreatment by steam explosion on the ethanol-water extraction of wheat straw. The samples of wheat straw were treated by steam explosion at 190°C and 210 °C for 4 minutes and later transferred to the treatment with ethanol-water (1:1, v:v) at different temperatures (140, 160 and 200 °C) and 60 minutes as reaction times. The pretreatment led to an increase in the amount of extracted lignin in the ethanol pulping. This effect was more pronounced in the pulping performed at lower temperatures. The use of higher temperatures in the treatment by steam explosion was more significant as shown by lower pulp yield and higher extractive extent.

Abstract: In order to evaluate its thermal aging properties, the volatile organic compounds of engineering smoked bamboo were adsorbed and determined by TD-GC-MS. The result were: (1) The main constituents of volatiles at 160°С were acetic acid(42.20%), benzofuran, 2,3-dihydro- (7.32%), 1,3-benzodioxole, 5-(2-propenyl)-(5.72%), etc. (2) The main constituents of volatiles at 180°С were acetic acid(41.69%), benzofuran, 2,3-dihydro- (7.32%), 3(5)-[[1,2-dihydroxy-3-propoxy]met hyl]-4-hydroxy- 1h-pyrazole-5(3)-ca rboxamide (6.75%), 1-phenanthrenecarboxaldehyde, 7-ethenyl- 1,2,3,4,4a,4b,5,6,7,9,10,10a- dodecahydro- 1,4a,7 - trimethyl- (3.46%),etc. So the engineering smoked bamboo was safe under 160-180°С.

Abstract: This paper studied treatment of sewage from channel discharge with biological accelerator-biofilm process, and investigated the promoting effect of biological accelerator on biofilm process during the sewage treatment process. Meanwhile, compared the difference between the laboratory developed compounded enzyme and the foreign composite enzyme. The research results indicated that using biofilm process, the composite enzyme-biofilm process and the compounded enzyme-biofilm process for treating sewage, the removal rate of COD_cr was separately 70.5%, 78.4% and 74.0% and that of ammonia nitrogen was separately 38.2%, 48.6% and 45.9%, which accounted for that under the strengthening action of biological accelerator, the treatment effect was remarkable for using biofilm process disposing channel disordered discharge sewage. Furthermore, the promoting effect of the compounded enzyme was equivalent to that of the composite enzyme for biofilm process, and the compounded enzyme could come into use instead of the composite enzyme.