Advanced Materials Research Vols. 1073-1076

Abstract: Soil samples from 6 sampling sites along 5 depths (0, 10, 20, 30, 40cm) were collected from an rural dumpsite in Hebei Province. The heavy metal (As, Cr, Cd, Pb, Cu, Zn) concentration were measured by inductively coupled plasma atomic absorption spectrometry (ICP/AES) in order to study the spatial distribution and assess their risk by the geoaccumulation index and potential ecological risk index. It was found that the mean concentrations of Cd, Pb, Cu were higher than the elemental background values in Hebei Province. The spatial distribution show that the longer stacking area had heavier heavy metal pollution in deeper soil due to long-term penetration of leachate and new stacking area had heavier pollution in surface soil. However, the geoaccumulation index and potential ecological risk index values show that most sites of the studied soils is in uncontaminated or low contaminated level. The potential ecological risk index values in the dumpsite were, in descending order, Cd > Cu > Pb > As > Cr > Zn, respectively, implying that Cd, Cu, Pb posed a higher hazard to human and ecosystem health. It was recommended that some measures were required to reduce heavy metal contents in soils caused by garbage dump.

Abstract: To get more sensitive index for making scientific and objective judgment on heavy metal pollution in brown soil, the influence which heavy metals Cu, Cd, Pb and Zn exert on soil urease, catalase activity and microbial biomass carbon content were evaluated by means of laboratory simulation.Experiment results showed that urease activity firstly increased with the addition of Cu, Cd and Pb, then showed decline trends. But for Zn, the activity of urease was obviously decline with the increased Zn concentrations. Catalase activity firstly increased with the addition of Cu then showed decline trend. But for Cd, Pb and Zn, the activity of catalase obviously declined. Microbial biological carbon all showed decline trends with the addition of Cu, Cd, Pb and Zn.

Abstract: In order to solve the problem of serious dust and difficult to control in coal conveyer belt without tissue in a thermal power plant of Shanxi, this paper introduces the principle of dry fog dust suppression technology, apparatus components, advantages and disadvantages and the application in a thermal power plant. Determination of dust concentration when the dry fog dust suppression work or does not work. Data show that the rate of dry fog dust suppression is generally greater than 80%, the dust concentration is less than 10 mg/m³, especially the suppression effect on small particles of less than 10 μm dust is obvious. Practice shows that dust has been effectively suppressed and it has a good application prospect, when this technology and device are applied.

Abstract: Activated sludge systems operate at low DO concentration can save aeration energy and enhance the treatment performance. To explore the effect of DO control strategies on the settleability of activated sludge, different DO control strategies were carried out in a step-feed anoxic/oxic reactor treating domestic wastewater. The result shows that low DO concentration is not the single reason to filamentous bulking. To achieve long-term system stabilization and avoid serious filamentous bulking, feedforward-feedback DO control strategy may be a feasible and good choice.

Abstract: TiO₂ hollow sphere was synthesized by hydrothermal method using Trifluoroacetic acid (TFA) and Ti (SO₄)₂ as raw materials. The photocatalytic properties of TiO₂ hollow sphere were evaluated by the photocatalytic oxidization of elemental mercury (Hg⁰) in simulated flue gas. The as-prepared samples were well characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible diffuse reflectance spectroscopy and nitrogen sorption/desorption. The results show that only anatase phase for TiO₂ the hollow sphere is obtained. The average diameter is about 800nm and the shell thickness was about 200nm. The sample prepared with TFA has better photocatalytic properties than P25.

Abstract: Sagittaria sagittifolia was grown in nitrogen (N) stress monoculture to test the relative content of three pigments by the manipulative indoor experiment. The treatment consisted of one level of N (14 mg L^-1 N) of nutrient solution. The content changes of three pigments were studied in continuous 21days. Results showed that the content of pigments was significantly increased at the first 7 days. With N stress increasing in the medium, the content of pigments decreased slowly. After 21 d N-exposure, the content of pigments were still higher compared to the contol.

Abstract: The main objective of this study was to investigate membrane fouling caused by natural organic matter (NOM). Flux measurement, fourier transform spectroscopy (FTIR), scanning electron microscopy (SEM) were employed to compare the surface morphology of fouled membrane and chemically cleaned membrane. Sodium hypochlorite (NaClO), sodium hydroxide (NaOH), hydrochloric acid (HCl) were used as chemical cleaning agents respectively. Flux analysis demonstrated that chemical cleaning have little effect on flux recovery. FTIR spectrometry revealed that polysaccharide and protein took the major responsibility for membrane fouling. SEM showed that foulants filled the pores and blocked the membrane surface which led to the flux decline.

Abstract: By applying the technology of composite ecological floating bed, a research was conducted to compare the eutrophic pollutant removal effects in domestic sewage among different filler proportions under static conditions. The results of proportion comparison experiments showed that the proportion of Plant: Filler = 1:1 had the best effects on NH₄ ⁺-N with the average removal rates as 97.93%, while as Plants: Filler = 1:1/2 had the best effects on TN and TP with the average removal rates of 89.05% and 91.55% respectively.

Abstract: This paper introduced the fundamental principle of the simultaneous desulfurization and denitrification by combining ozone oxidation and the NaOH double alkali method. And the total chemical reaction equations were achieved by analyzing the process of the absorption of the productions of ozone oxidation by NaOH double alkali method. Then, based on thermodynamic principle, the partial pressure of SO_x, NO_x and CO₂ when reactions reached equilibrium were calculated respectively. This paper also studied the reaction mechanism of the absorption of SO_x and NO_x and analyzed the absorption characteristic of SO_x and NO_x in absorption solution. The results showed that the simultaneous desulfurization and denitrification by combining ozone oxidation and NaOH double alkali method was feasible. Not only the elimination ratio of SO_x and NO_x were almost up to 100%, but also CO₂ was removed on a considerable scale. The partial pressure of SO_x and NOx was very important to the pH value of the absorption solution which affected the elimination ratio of SO_x and NO_x greatly.

Abstract: There are variety of active substances in Fenton system, such as H₂O₂, HO₂^-, O₂^-·, ·OH and HO₂·. In this paper, the oxidation of H₂O₂, HO₂^-, O₂^-·, ·OH and HO₂· on NO gas was determined respectively with experimental methods. The results showed that direct oxidation of gaseous NO by H₂O₂, HO₂^- and O₂^-·was weak. ·OH and HO₂· had strong oxidizing capacity on gaseous NO, especially ·OH. With the acceleration of ·OH and HO₂· generation rate, the oxidizability of Fenton system on NO gas was stronger, but O₂ generation rate also accelerated. Rapid decomposition of H₂O₂ is the premise to realize high NO oxidation efficiency using H₂O₂, but how to avoid the invalid decomposition of H₂O₂ is the key to increase use ratio of H₂O₂.