Applied Mechanics and Materials Vols. 409-410

Abstract: Spatial distributions of chlorophyll-a (Chl-a), secchi disc transparency (SD), and total nitrogen (TN) were estimated using Landset7 ETM+ SLC-OFF data before and after the connection project of Donghu Lake and Shahu Lake in Wuhan, China. Results show that water quality in the two lakes is improved in most area, especially in the joint connection. There are 23%, 19%, 18% in average improvement for Chl-a, SD, and TN respectively. This study suggests that besides controlling of point and non-point sources pollution, water network connection project is effective on water quality in lakes.

Abstract: Soil organic matter (SOM) is the most active material component in soil, whats more, it is significant for soil fertility evaluation and agricultural sustainable development. This paper tries to establish a regional SOM prediction model of Yang Jiaqiao town, Xiangtan county in Hunan province, which based on the data obtained in the field and SPOT-5 image with the help of remote sensing retrieval technique, and then get the regional distribution of SOM. The results show that the most SOM content in experimental area is higher than 3%, which indicates SOM plays an important role in spectral reflectance characteristics, then establish corresponding estimation model and test them after transferring the reflectivity spectral data. The paper analysis and comes to a conclusion that the most appropriate model is the second-order polynomial one of red band based on SPOT-5 image by comparing the models between SOM content and single band measured reflectance.

Abstract: With the two solvothermal and hydrothermal method, synthetize the bismuth phosphate catalyst with controllable morphology. And study the photocatalytic activity which use methylene blue and methylene orange as probe. By using X ray powder diffraction(XRD) and the scanning electron microscope(SEM) the products were characterized. Study found that glycerol content can affect the morphology and structure of bismuth phosphate. In the photocatalytic reaction, MB concentration will affect the rate of reaction, and the bismuth phosphate addition also significantly affect the MO reaction rate.

Abstract: With climate changes, soil may experience frequent drying-rewetting events. Water stress influences soil nitrogen transformation by affecting microbial growth and enzyme activities. The objective of this study was to determine effects of drying-rewetting cycles on soil N transformations and enzyme activities involved. The results show high correlations between soil inorganic N (NH₄⁺-N & NO₃^--N) concentrations and soil moisture. Drying and rewetting events contributed to the accumulation of NO₃^--N. There was a significant correlation between NH₄⁺-N/TDN and urease activities with a correlation coefficient of 0.88. Denitrifying enzyme activity showed a high positive correlation with soil moisture.

Abstract: Basing on meteorological data,vegetation distribution data,water resources condition data and so on as the background material,we calculated the minimum and appropriate eco-environment water requirement of existing forest in the central and southern Ningxia in growing season. Through the equilibrium analysis between the attrition eco-environment water demand and rainfall resource,the results show that Longde and Jingyuan county which locate in the southern,with an average rainfall of 350 ~ 550 mm,the minimum and appropriate eco-environment water demand both can be meet relying on precipitation,and the vegetation growth in good condition.. Pengyang and Yuanzhou county which locate in the southern,with an average annually rainfall of 350 mm or so,the minimum eco-environment water demand can be satisfied, but appropriate eco-environment water demand can not be satisfied. So reasonable forest planting structure should be considered in the area. Haiyuan,Yanchi and Tongxin county in the central arid area and Xiji in the south,with an average annually rainfall between 175 and 280, both minimum and appropriate eco-environment water demand can not be satisfied,it is unfavorable to develop forest in this area.

Abstract: The experiment retains the advantages of MBR and improves the inadequacies of the MBR .The following improvement has been made:Substituting traditional macromolecule strain membrane with biomembrane as the separate part of water terminal; Substituting the suspended microorganism with immobilized microorganism.which forms a biofilm - membrane bioreactor (BMBR). The trial results show that the removal efficiency of COD_CrNH₃-N reaches above 85%90% respectively in BMBR process under the stable conditions of gas-water ratio 8:1 to 10:1 and HRT3 ~ 4h. Meanwhile,BMBR is simple and convenient for process,microorganism is large and volume load is high,investment scale is rather low.Besides membrane fouling can be avoided effectively . Compared with the MBR , BMBR has better economic performance and application prospects.

Abstract: 15 water quality indicators of the deepwater layered Jinpen Reservoir were monitored from August 2011 to July 2012. The cluster analysis method was employed to explore the relationship between the outflowing water quality of the reservoir and the water quality of each longitudinal water layer to provide technical solutions for predicting the outflowing water quality of the reservoir and reducing the cost of water purification in the water plants effectively. The results indicate that by carrying out the K-means cluster analysis on the water quality of the longitudinal water strata according to the 3 cluster sets, the cluster centers of the cluster groups where the water strata of the withdrawal intake outlets are that are counted up can predict outflowing water quality of the water tower effectively; the degree of consistency of the predicted temperature, pH, ORP, conductivity, salinity, alkalinity with the actual test data is relatively higher, and the relative errors were within the-10% to 10%. Polynomial curve fitting was done for the upper and lower boundaries of the cluster group where the water strata of the withdrawal intake outlets are, and the outflow concentration obtained conformed to the theoretical derivation and the actual situation.

Abstract: Experimental observations of particle capturing through the biological aerated filter bed indicated that air flow rate plays an important role in head loss development by influencing the suspended solids distribution along the depth of the bed as well as the morphology of the deposits. The active height for the SS removal prolonged with the increasing of the air velocity based on the mechanism of first-order kinetics. With the increasing of the superficial air velocity, the effluent SS concentration and the time need to reach the stead-states after backwash both increased. The value of the SS spike in the effluent after backwash at superficial air velocity of 27 m/hr was nearly twice as much as that of 5.4m/hr. Distribution of the deposits at higher air velocity was more uniform. Deposits at lower velocity with air flow rate produced higher head loss gradient. The headloss increased with the increasing of deposits and the increase rate was faster when the deposits exceeded higher value.

Abstract: Aiming at the problem of concentrated water discharge amount is larger and the recovery rate is low in desert greenhouse for desalination of brackish water,Using reverse osmosis concentrated water circulation system.The results showed: With less dense water emissions, System desalinization rate decreases, system recovery rate increases, water flow in the system decreases, the system water pressure increases. In this test, when dense water emissions is 0.81m3/h, System desalinization rate reaches up to 91%, system recovery rate reached up to 81%, saving water above 20%. Major ion SO₄^2-, Cl^-, Ca²⁺ and Mg²⁺ removal rates are 96.2%, 92.7%,100% and 100%. The order of yield and benefit on Planting pepper are: wheel irrigation drip > water drip > mixed irrigation drip > raw water drip irrigation under different irrigation modes.Benefit-cost ratio of wheel irrigation drip ,water drip and mixed irrigation drip are 17.68,13.61 and 4.61.

Abstract: Refractory wastewater is characterized by high concentration of organic matter, high toxicity for biotic systems, bio-recalcitrant, complex component, and stable chemical structures. This paper studies effect of circular orifices plate with Venturi tube on degradation of hydrophilic pollutant and hydrophobic pollutant by considering the different sizes and numbers of circular orifices plate. Also, effects of initial concentration and operation time were considered. Degradation rate was analyzed by ultraviolet spectrophotometer and pressures at measuring points were measured by pressure data acquisition system. Variations of degradation rate with orifice number, orifice size, initial concentration and operation time were developed.