NH_3-N Degradation Dynamics and Calculating Model of Filtration Bed Height in Constructed Soil Rapid Infiltration

The research on Constructed Soil Rapid Infiltration(CSRI) system is in its infancy at home and abroad.There are several details about the mechanism and application of CSRI system needed to be further studied.A major limitation in the current research is the absence of degradation dynamics of pollutants,and the height of filtration bed in CSRI system currently determined by empirical judgment lacks accuracy and logicality.To solve these two prob-lems,the soil column of CSRI system was utilized to treat domestic wastewater,meanwhile,the NH3-N degradation dynamics were studied according to the Monod equation,the research of Mann A T and the NH3-N degradation law.Then the mathematical model of filtration bed height was built based on NH3-N degradation dynamics equation in the soil column.It has been proven that within a limited range this model can calculate the appropriate height of filtration bed accurately in order to optimize technological parameters of hydraulic load and the concentration of influent NH3-N,improving the effluent quality of CSRI system.

双电源低温渗氮工艺在316不锈钢上的应用

通过正交试验研究了交流脉冲电压、直流脉冲偏压和温度对316不锈钢表面硬度和渗层厚度的影响,获得了双电源低温渗氮最佳工艺参数。通过光学显微镜(OM)、X射线衍射仪(XRD)、显微硬度计、电化学工作站以及摩擦磨损试验机等研究了最佳工艺下渗氮试样的性能。结果表明,影响渗氮试样性能因素的顺序为:交流脉冲电压>温度>直流脉冲偏压。最佳工艺参数为交流脉冲电压360 V,直流脉冲偏压270 V,温度380℃。对最佳工艺制备的试样与单电源进行对比:渗层厚度为43.4μm,是单电源的8.5倍;表面硬度为1350 HV0.025,是单电源的3.1倍;自腐蚀电位由-256 mV(vs SCE,下同)提高到-180 mV;自腐蚀电流密度从13.90μA/cm^(2)降低到0.45μA/cm^(2);摩擦因数从0.55降低到0.42。双电源渗氮速率的提高是由于高能离子轰击引起的表面结构缺陷和渗氮气体的高度离解。