电絮凝法同步去除氨氮和磷的模拟试验

采用电絮凝法去除废水中的氨氮和磷,电极板采用铝板或不锈钢板,研究了电絮凝除磷热力学与动力学过程,考察了不同工艺参数对氨氮和磷去除效果的影响. 结果表明:相对于铝电极而言,不锈钢电极更适宜于电絮凝去除氨氮和磷；Redlich-Peterson方程能较好地描述电絮凝产生的絮凝体对磷的吸附行为,得到的Gibbs自由能变都在-20～0kJ/mol范围内,并且吸附是自发进行的吸热过程,升高温度有利于吸附；由于假二级动力学方程拟合时其相关系数(R2)均大于0.98,故假二级动力学方程更适宜描述电絮凝产生的絮凝体对磷的吸附动力学过程；随着电流密度的增加,氨氮和磷的去除率呈逐渐上升趋势；在强碱性条件下,氨氮的去除率相对降低,酸性条件下水中磷的去除率较高,随着溶液pH的增高,磷的去除率呈逐渐降低趋势. 去除氨氮和磷的能耗分别为0.15~0.50和0.02~0.04kW·h/g. 

Simultaneous Removal of Nitrogen and Phosphorus by Electrocoagulation Process

Electrocoagulation with stainless steel electrodes and aluminum electrodes were adopted for removal of ammonia nitrogen and phosphorus. The thermodynamics, kinetics and the effect of different parameters on ammonia nitrogen and phosphorus removal were studied. The results showed that stainless steel electrode were more suitable for removal of ammonia nitrogen and phosphorus from aqueous solutions compared with aluminum electrodes. The phosphorus adsorption process could be depicted primarily by Redlich-Peterson function and the higher temperature was helpful for its adsorption, which was a spontaneous and endothermal process. The changes of Gibbs free energy ranges from -20kJ/mol to 0kJ/mol. The correlation coefficient R2was greater than 0.98, and this indicated that the kinetic data of phosphorus adsorption were better fitted with the pseudo-second-order kinetic model. The removal efficiency of ammonia nitrogen and phosphorus increased with increasing electric current density. A lower ammonia nitrogen removal rate under strong alkaline conditions was also observed, and the removal efficiency of phosphorus was the best under acid conditions, while it decreased with the increasing pH. The power values were 0.15-0.50and 0.02-0.04kW·h/g respectively, which were required for ammonia nitrogen and phosphorus removal during electrochemical processes.