Applied Mechanics and Materials Vols. 178-181

Abstract: A field pilot test was conducted on a macro-electrolysis/biological filter with immobilized microorganism system (ME/I-BF) in the Liaohe oilfield, China to treat super heavy oil wastewater with large amounts of dissolved recalcitrant organic compounds and low nutrients of nitrogen and phosphorus. By operating the system for 155 days (including the start-up of 28 days), the BOD/COD ratio of water increases from 0.13 to 0.22 and the COD removal rate is 47.46% after the ME treatment. Then, the COD decreases to 100 mg/L and the COD removal rate is 80.96% after I-BF treatment. When indigenous microorganisms inoculated, the effluent gets better, COD decreases to 70 mg/L and the removal rate of COD increases to 88.54%. Gas chromatography/mass spectrometry (GC/MS) indicated that the super heavy oil wastewater contains 11 organic compounds and most of them are removed after treatment. This integrated system is a useful option for the treatment of heavy oil wastewater.

Abstract: Lamellas important for micropores were well formed during extrusion and annealing process in melt-spinning and stretching method. This unusual crystalline structure and its changing during annealing and stretching process were well studied in term of lamellar size, lamellar crystallite orientation, degree of lamellar and observation of morphology. Lamellar and microfibril model was accepted as mechanism of making micropore for this process. Gas permeability and porosity testing experimental were used to characterize membrane properties.

Abstract: Microbial fuel cell (MFC) is a new technology that combines wastewater treatment and bioenergy production. Platinum, as a commonly used catalyst for oxygen reduction reaction (ORR) in MFC, has hindered the development of MFC as the result of its high-cost. Consequently, developing effective and low-cost catalysts for ORR has aroused extensive research interest. The particle size effect is known to play an important role for catalyst. Three kinds of carbon powders with different grain sizes were chosen to prepare nitrogen-doped carbon powder (NDCP) as a low-cost catalyst for oxygen reduction in MFCs. The result showed that particle-size effect might be attributed to morphological changes of the relative concentration of surface atoms and nitrogen functional groups. As a result, the power density of NDCP with carbon 8000 mesh (739.2 mW m^-2) was much higher than another two catalysts by 40% (carbon 10000 mesh, 413.1 mW m^-2) and 60% (carbon 3000 mesh, 248.5 mW m^-2). In addition, carbon 8000 mesh exhibited a bit higher coulombic efficiency than carbon 10000 mesh and carbon 3000 mesh.

Abstract: In this paper, the effects of the concentration, temperature, and run-time of ionic liquids solution, on the rejection capacity of home-made hollow fiber composite nanofiltration membrane were studied. Then the nanofiltration membrane was used to the recover ionic liquids by concentrating spinning wastewater. The results shows that: The rejection rate of the composite nanofiltration membranes and its water fluxes lightly down with the concentration of ionic liquids increase; with running-time and temperature of ionic liquid solution increase, the rejection rate of the composite nanofiltration membranes decreases, but its water flux increases; the nanofiltration membrane can be use for recovering ionic liquid from the spinning wastewater and get very good recovery effects.

Abstract: In order to evaluate the impacts of metals mobility from fly ashes on surface water quality, the dissolved metals concentrations in the stream and pond waters nearby fly ash piles were investigated at the thermal power plant regions in central Guizhou Province, and batch leaching or column leaching tests for the fly ashes were performed. The results shown that the most mobile of the metals leached were Cu, Cr, Pb and Cd from fly ashes and the concentrations of the metals in leachate solutions increased with the amount of fly ashes, and high concentrations of Pb (0.040~0.886 mg L−1), Cr (0.025~0.315 mg L−1) and Cd (0.007~0.052 mg L−1) in the leachates from fly ashes, and then there is an mobility of dissolved metals to the surface waters impacted by the runoff or leaching water. In thermal power plant areas, the concentrations of Pb, Cr and Cd in the stream waters and the pond waters nearby fly ash piles were 0.024~0.374 mg L−1, 0.030~0.212 mg L−1 and 0.014~0.035 mg L−1, respectively, as indicated by high concentrations of Pb, Cr and Cd, making it unsuitable for human drinking, suggesting a environmental problem of runoff or leaching water from fly ash pile in those areas.

Abstract: The concentration of heavy metals in excess sludge from municipal wastewater treatment plants has restricted its convertion to soil fertilizer, so it is necessary to remove the heavy metals from sludge. In this article, the effects of heavy metal removal by some mineral acids such as HCl, H2SO4, H3PO4, HNO3 were analysed, when treating excess sludge from a second sediment tank in municipal wastewater treatment plants. To improve the treatment, a combination of H2O2 and acid was also investigated. Consequently, the difference of heavy metal removal among those acids was showed. Its removal of Hg by HNO3 was better than by other acids. Lower pH enhanced the dissolving of heavy metal, yet the removal of Cr was insensitive to the pH. Aided by H2O2, the removal by the acid was enhanced. The suitable dosage of H2O2 was specially related to the solid content of sludge, pH and the acid kind.

Abstract: The C₃N₄ was synthesized by directly thermal decomposition melamine in N₂ atmosphere furnace. The products were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-Vis diffuse reflectance spectroscopy (DRS). The results show that C₃N₄ indicates the typical slate-like, stacked lamellar texture of about 1μm in diameter, and a band gap of about 2.78 eV. The photocatalytic experiment shows the good photocatalytic activity for the decomposition of methyl orange (MO) under visible-light irradiation, which is attributed to the strong visible-light absorption.

Abstract: Based on fillers theory and traditional A/O-MBR theory, anoxic/aerobic hybrid membrane bioreactor system (A/O-HMBR for short) was modified by adding suspended biological fillers in one of the aerobic tanks of the traditional A/O-MBR, in which the filling ratio of fillers was 8%. The thesis mainly studies the nitrogen removal effect in the A/O-HMBR system when the main influence parameters, such as influent C/N(5,7,10), aeration intensity(15m³/h,20m³/h,25m³/h) and HRT(5h,8h,11h), were changed.The experimental results show that when HRT was 8h, C/N was 7, and aeration intensity was 20m³/h, TN removal effect was best.

Abstract: Nonylphenol(NP) have endocrine disrupting effects and exist generally in drinking water source. Physical properties including surface area, average pore-diameter, and micro-pore volume and chemical structure of the activated carbon was characterized by N2 adsorption experiment and X-ray photoelectron spectroscopy (XPS). Pore volume could be the most important for adsorption. The high O content of carbon surface lead a negative effect to absorption capacity and low pH value, low temperature lead a positive effect to adsorption. The effect of humus in water to the removal was also studied and EDCs-humus bi-component adsorption model was established, it was found that there is strong competition between EDCs and humus. Due to the competition adsorption capacity of NP greatly decreased especially when the concentration of NP is very low. The adsorption kinetics test results indicated that the adsorption of NP followed the first-order kinetics and the smaller diameter GAC could increase adsorption velocity.

Abstract: The step feed model based on the Activated Sludge Model No.1 (ASM1) and the optimum model of the ammonia nitrogen (S_NH) removal in wastewater were established. Four aeration tanks under the different step feed ratios were simulated by Matlab Simulink. The results show that single-feeding is conducive to the removal of readily biodegradable substrate (S_S) and the growth of heterotrophic organisms (X_BH), and to lower the biodegradable substrate (X_S) at the same time. The S_S, X_S, and S_NH concentrations are 1.36, 5.98, and 3.02 mg/L respectively in effluent. However, the step-feeding is conducive to the S_NH removal, and the autotrophic bacteria (X_BA) growth. Under the step feed ratio (25/25/25/25%), the S_S, X_S, and S_NH concentrations are 2.64, 10.79, and 2.61 mg/L respectively. Under the optimum ratio (28.7/23.6/20.4/27.2%), step-feeding could further facilitate the removal of S_NH and hinder the removal of organic matter, their concentrations are 2.70, 10.98, and 2.47 mg/L respectively.