Applied Mechanics and Materials Vols. 260-261

Abstract: PM_2.5 and ionic components have been measured from summer 2009 to winter 2010 in the suburb of Shenzhen. Serious PM2.5 pollution was observed, especially in winter. SO42-, NO3- and NH4+ in winter were the predominant ions in PM2.5. In summer, the mean contributions of SO₄^2-, NO_3^- and NH4+ to PM2.5 decreased, while the contributions of Cl- and metal ions increased significantly. Furthermore, ion balance, ratio analysis and correlation analysis were conducted to identify the sources of ions in PM2.5.

Abstract: The Cavitation Air Flotation (CAF) process has been widely applied to the pretreatment of industrial wastewater and urban sewage. However, it has not been applied in the sludge treatment yet. In this paper, Nanchang Chaoyangzhou Sewage Treatment Plant is taken as the example that the CAF process is introduced to the concentration of miscible liquid in the aeration tank in urban sewage treatment plants. According to the optimization of the sludge conditioning agent and the study on the concentration of the miscible liquid in the aeration tank, it is concluded that CAF can be used to concentrate the leftover activated sludge in urban sewage treatment plant, especially that with low density.

Abstract: With the global climate continues warming, carbon emissions become the global focus. How to design the contract of low-carbon supply chain is an important research direction. Our goal in this paper is to construct supply chain decision model under carbon tax. And we build the demand distribution function including consumer characters which is more in line with the reality of the actual retailer operations. Through numerical analysis using Matlab software， we find that carbon emissions allocation coefficient does not affect the optimal profits of suppliers and retailer under wholesale price contract; Supply chain enterprise could gain more profit through the carbon emissions collaborative, choosing reasonable carbon emissions levels.

Abstract: Some azo dyes such as Acid Orange 7(AO7) could be reduced to produce aromatic amines with a hydroxy group in ortho-position to an amino group, which undergo easily the autoxidation, led to the generation of more recalcitrant compounds. Therefore AO7 biodegradation was explored in a membrane-aerated bioreactor (MABR) for the first time. The results indicated that, oxygen supply pressure showed obvious impact on the MABR performance with appropriate oxygen pressure of 0.03 MPa; under optimal conditions, AO7decolorization efficiency reached over 98 % in 6 h and the effluent COD kept stable with COD specific removal rate of 0.26 g/m2.h; whereas conventional anaerobic-aerobic process achieved only 57.8 % COD removal with yellow effluent; the used silicone membrane resist biofouling and kept high oxygen permeability after long term running, oxygen transfer coefficient KL decreased slightly from 0.031 to 0.029 m/h.

Abstract: Aeration was one of the common techniques which were focused in environmental engineering research. In this study, experiments were carried out to investigate the effect of aeration on nitrogen (N) fractions and its transformation in the sediment-water interface from urban lake. In addition, we measured the dehydrogenase (DHA) and Chla content in surface sediment to detect the changes of the microbial activity. The aim is to explore the regulation of N migration and transformation in the water-sediment interface during the treatment work of lake pollution. By mechanical aeration, we control the DO content of the overlying water at the range of 1.2-1.5 kg/L, 2.5-4.5 mg/L and 6.1-6.2 mg/L. Results showed that DO in overlying water play a role to the variation of N in water-sediment interface. NH₄⁺-N was the mainly N fraction released from sediment, the lower DO concentration (1.2-1.5 mg/L) in overlying water is favorable to the release of NH₄⁺-N from sediment. Whether under aerobic or anaerobic condition, the releasing of NH₄⁺-N from sediment were both higher than its consumption in the overlying water. The benthic microbial activity of the surface sediment (0-2 cm) was higher than that from bottom (6-8 cm). And the microbial activity in surface sediment was in optimum range when the overlying water DO content was about 2.5-4.5 mg/L.

Abstract: Acid rain pollution is a serious environmental problem in the world. This study investigated the impacts of simulated acid rain on yellow cinnamon soil planted with seedlings of Quercus variabilis. The results showed that the acidity of simulated acid rain had complex impacts on the organic matter content of the studied soil. With the decrease of the acidity, available K increased but soil pH reduced. Rainfall of simulated acid rain also had impacts on available K and the soil pH, and produced the same trend as the acidity. In conclusion, we estimated that high intensity and large rainfall of acid rain could affect soil properties.

Abstract: With the rapid economic development and the highlighting environmental issues, more attention has been paid to ecosystem health and ecological safety. Along with the development of the concept of sustainable development, people gradually realized the importance of natural ecosystems. Ecological safety is the basis of sustainable development. It is a necessary condition to build a harmonious and environment friendly society. A healthy ecosystem is the basic guarantee of the realization of human social and economic development. This paper analyzes the relationship between ecosystem health and ecological safety, and finds that there are many connections and differences between them.According to the comparison of indices in the same evaluation model, the differences are analyzed. The paper helps to avoid the confusion between this two terms, and aims to make the goal of environmental management clear.

Abstract: In the thesis, the pollution condition of heavy metals in the soil is evaluated by fuzzy comprehensive evaluation method through testing and analyzing content of heavy metals (As Cd Cr Cu Hg Ni Pb Zn) in 400 sampling points within 400km² near Baicheng City; and types and sources of pollutions of heavy metals in the soil in Baicheng City are analyzed and studied by factor analysis method. scientific proof for soil improvement and phytoremediation in this area can be provided. It is indicated through the integrated evaluation of the test result that the living quarter, the main road area and the green belt are polluted slightly; the industrial area is polluted moderately. It can be seen through comprehensive analysis that there are three main sources of heavy metal pollutions in the surface soil in Baicheng City: industrial pollution source, traffic pollution source and house pollution source. Therefore, effective measures shall be taken by the local people in the protection of the soil encountered with the various pollution status of the functional areas.

Abstract: Microwave strengthened Fenton process oxidation of organophosphorus pesticide wastewater was studied by microwave chemical technology. With the synergistic effect of microwave and Fenton, pesticide wastewater was treated by varying dosage of pH, n[FeSO₄•7H₂O]/n[H₂O₂], microwave power and microwave radiation time. Microwave strengthened Fenton process oxidation of organophosphorus pesticide wastewater could achieve good effect and the COD removal rate can be up to 82%.

Abstract: Soil erosion by water is affected by soil factor, rainfall erosivity, geographical factors, vegetation cover factor, and support practice factors. On the basis of quantitative estimation of soil erosion in the Upper Min River (UMR) watershed (located in the Upper Yangtze River basin, Sichuan, China) by applying the Revised Soil Loss Equation (RUSLE) model, Geographical Information System (GIS) software, and Remote Sensing (RS) technology, we explored the effects of topography and vegetation on soil loss for better erosion control measures, and analyzed ecological restoration approaches for the high soil erosion areas of this mountainous watershed. Totally 625 field plots were sampled for visually verifying soil erosion classification. Zonal statistics in ArcGIS software were used to assess the values of soil loss under different topographic and vegetation gradients. The results showed 58.1% of this watershed suffering moderate, high or extremely high erosion. The average soil erosion values substantially increased as the slope ranges rising. On the slopes of 7 categories (50 degrees), the percent of moderate, high and extreme risks accounted for 12.07%, 21.03%, 36.43%, 62.83%, 82.51%, 91.04%, and 94.02% respectively. The values of soil loss on sunny slopes were higher than those on shady slopes. The mean value was the greatest on the west-facing slope. On each similar slope, vegetation types showed different patterns to soil loss, and higher vegetation cover prevented more soil loss from erosion. In order to alleviate soil loss hazards, conservation measures to change micro-topography including terraces and contour tillage could be implemented in the watershed, and ecological restoration could be effective measure for controlling soil erosion in this degraded mountainous watershed.