Advanced Materials Research Vols. 610-613

Abstract: Vegetation is regarded as one of the most effective methods to improve the outdoor microclimate and pedestrian thermal comfort. Throughout numerical simulation experiments, the plant communities’ effect on outdoor wind environment and the relationship between them have been studied. The conclusions could be drawn as follows: 1) Ginkgo biloba community, Sophora japonica community and Magnolia denudata community have more obvious attenuation effect of wind velocity. Communities have poorer attenuation effect of wind velocity because of smaller size and crown diameter. 2) The reduction ratio of upstream wind velocity increases accompanying canopy closure, leaf area index, structure and height of dominant species of plant community.

Abstract: In order to investigate the effects of four heavy metal tolerant microorganisms, Staphylococcus pasteuri (X1), Agrobacterium tumefaciens (X2), Penicillium chrysogenum (Z1) and Paecilomyces lavender (Z2), on heavy metals uptake by the heavy metal tolerance plant-maize and the cadmium hyperaccumulator plant-Beta vulgaris var. cicla L., a pot experiment with sediments was conducted. Through comparing the overall situations of four microorganisms’ role in enhancing maize and Beta vulgaris var. cicla L. to gather cadmium, lead, copper and zinc, plant biomasses, and enrichment characteristics, the combination of bacterium X2, fungus Z2 and these two plants can effectively repair these four heavy metals in sediments.

Abstract: Mass extraction process of phenol from aqueous solution to a caustic solution through nonporous silicone rubber membrane was investigated. The effects of liquid flow status, pH of stripping solution, initial phenol concentration, transmembrane pressure, and system temperature on mass transfer coefficient were discussed. Based upon the resistance-in-series model, the overall mass transfer coefficient (OMTC) across membrane was calculated. The experiment results showed OMTCs presented logarithmic relation to the Reynolds number, while the changes of flow status had little effect on OMTCs at the higher Reynolds numbers (Ret>86.5 and Res>2000), which indicated that mass transfer of phenol was dominated by membrane resistance for nonporous membrane system (3.72×10-7m•s-1). The presence of transmembrane pressure went against permeability of phenol. Moreover, OMTC was linearly proportional to the initial phenol concentration in the range of 5,000-7,500 mg•l-1, and reached a plateau value at higher phenol initial concentration. OMTC was directly proportionate to the temperature in this process. Mass transfer of phenol through nonporous membrane was scarcely affected by pH value of the stripping solution.

Abstract: A 2,4-Dinitrotoluene degrading bacterium was isolated from sludge contaminated by DNT and identified as a member of Pseudomonas fluorescens sp. based on 16S rDNA sequence. Under growth substrates limited conditions, the strain was enriched with 2,4-DNT as its sole source of carbon and energy in the groundwater environment. Results indicate the isolate grew optimally at 12(±4)°C and initial pH 7.5 in the mineral salts medium supplemented 2,4-DNT with 40mg/L, thus showing potential for the remediation of 2,4-DNT contaminated groundwater.

Abstract: At present, the upper reach of the Deepwater Navigation Channel is silted heavily, which brings negative influences on navigation. A two-dimensional numerical model is set up to simulate the hydrodynamics of the Changjiang River Estuary with Delft3D-FLOW in this paper. This model has been validated with the observed tidal level, flow velocity magnitude and direction, and the computed results agree well with the observed data, which also shows the model can well simulate the hydrodynamics of the Changjiang River Estuary caused by the Deepwater Navigation Channel Project. Based on the analysis of computed results, especially the velocity along the South Passage and North Passage, the flood and ebb flow in the Hengsha Passage, and the flow spilt ratio of South Passage and North Passage, it presents that one fundamental reason for the sediment deposition in the upper reach of the Deepwater Navigation Channel is that the velocity along the North Passage is far less than that along South Passage, above all, the velocity in North Passage upstream of the Hengsha Passage is even smaller; another reason is that the flood and ebb flow of Hengsha Passage are large, which weakens the water exchange between the North Passage and South Channel.

Abstract: With growing concerns over clean environment and human health, water/wastewater treatment turns towards more restrictive objectives of water quality. In the past decade, a lot of research work has been focused on the water decontamination by magnetic assisted chemical separation (MACS) processes using iron oxide magnetic nanoparticles (MNPs) (mainly magnetite (Fe₃O₄) or maghemite (γ-Fe₂O₃)) as magnetic seeds. These particles are generally modified with various functional materials to increase their affinity or degradation capacity toward target compounds. In addition, these materials are relatively easy to be regenerated and recycled via magnetic separation, therefore are considered a great water purification media in practice. This paper offers a literature review of applications of these magnetic NMs in MACS processes for water/wastewater treatment.

Abstract: When oil spills in the coastal environment, the spilled oil may interact with the suspended particulate matter in the water column to form oil-SPM aggregates (OSAs). This process has been recognized to enhance natural cleansing of oiled shorelines. This laboratory study was conducted using SPM samples with different particle size distribution and mineral composition, two crude oil samples, filtered natural seawater, and a reciprocating shaker. The sediment-to-oil ratio was kept constant to 1 in all the experiments. The oil trapped in negatively buoyant OSAs was measured using an Infrared Oil Content Analyzer. Results showed that OSA formation increased with the decrease of the sediment size, the maximum oil trapped in settled OSAs was 182 mg oil/ g sediment when OSAs were formed with kaolinite and CST180 crude oil.

Abstract: Using pyrolysis-GC-MS and HPLC techniques, a series of studies were conducted on the effect of pre-oxidation on the structure of natural humic acids (HA) by ozone and hydrogen peroxide (H₂O₂). Both ozone and H₂O₂ could more or less result in direct removal of organic matter, but the removal of UV₂₅₄ was much higher than that of TOC, implying that an important function of the oxidants is to change the structure of the organic molecules rather than to decompose them into inorganic matters. The result of pyrolysis-GC-MS analysis showed that in the process of oxidation, the organic functional groups on the HA molecules underwent a significant change in their structure, mostly from cyclic to chain hydrocarbons and/or from aromatics to aliphatics. This process was also accompanied by a decrease in the molecular weight of the HA. With an apparent change in the structure and molecular weight of the HA molecules after pre-oxidation, a great improvement was seen on the overall removal of TOC as coagulation or GAC adsorption was subsequently applied. Additionally, in the case of H₂O₂, a small dose of O₃ showed much better catalysing effect than Mn²⁺, Cu²⁺ or Fe²⁺ ions.

Abstract: Enzymatic reaction kinetics for sugar factory wastewater biological treatment was investigated. A laboratory scale completely mixed reactor was used for the study. By using the Runge-Kutta method and modified simple, estimation of kinetic parameters was conducted. The kinetic parameters rmax (the maximum reaction velocity) and Km (Michaelis constant) were found to be 0.7952×10 mg/min.L and 0.2519×103mg/L for COD, and 0.1359×10 mg/min.L and 0.2062×103 mg/L for NH3-N, respectively. These parameters could be utilized for the design of the three phase biological fluidized bed reactor for sugar factory wastewater treatment.

Abstract: Rotary disc filter is widely used in industrial water treatment. There are two methods to improving the filtration efficiency, which are the higher filtration velocity and lower filtration pressure drop; while the type of the filter disc plays an important role on the performance of filtration, In order to know how the filter disc affect performance of filtration, simplified model was used. On this basis, rectangular and triangular type was numerically simulated with the CFD software Fluent, DPM model, then the flow field configuration, velocity magnitude, pressure drop through the filter medium and the distribution of the particles were obtained. Then, the simulation results were analyzed and the conclusion was achieved that was under the same operation condition and porous parameters. Filter disc with a triangular type has greater advantages than the one with a rectangular type in the aspects of lower pressure drop, velocity distribution uniformity and particle distribution, which can highly improve the filtration efficiency.