中试规模动力波吹脱技术分离老龄化垃圾渗滤液中的高浓度氨氮

Separation of high concentration ammonia nitrogen from aged-landfill leachate by pilot-scale dynamic wave stripping

为解决老龄化垃圾渗滤液的脱氨难题,采用动力波吹脱技术对老龄化垃圾渗滤液进行氨氮吹脱分离,探究了吹脱时间、pH、气液比、温度和进水氨氮浓度对吹脱效能的影响。单因素实验结果表明:前3 h吹脱去除率增长最快,5 h后吹脱去除率变化较小;高pH下游离氨占比增大,对吹脱更为有利,pH为10.5左右时的工艺最为经济;动力波吹脱适用温度范围广,在10℃和25℃时,去除率可达72.62%和90.68%;增加气液比可提高吹脱效率,但当气液比超过129后,吹脱效果增幅不明显;氨氮浓度对吹脱去除率的影响较小。正交实验结果显示:温度方差最大,pH、气液比方差次之,进水氨氮浓度方差最小,即表明温度对动力波吹脱脱氨影响最为显著;pH、气液比也是重要影响因素;初始氨氮浓度对吹脱效率影响不显著。在25℃、pH=10.5、气液比为129时,吹脱5 h的最优条件下,氨氮去除率约91.25%~94.15%。相比传统吹脱工艺,动力波吹脱技术能大幅提高氨氮分离效率。

In order to solve the difficult problems of denitrification from aged-landfill leachate, a pilot experiment on stripping of ammonia from aged-landfill leachate was carried out by dynamic wave stripping technology. In this study, the effects of stripping time, pH, gas-liquid ratio, temperature and concentration of influent ammonia nitrogen concentration on stripping efficiency were investigated. The results of the single factor experiment showed that the stripping removal rate increased rapidly in the first 3 hours, and changed little after 5 hours. The proportion of free ammonia increased at high pH, which was more beneficial for stripping,and the most economical stripping result occurred a pH of around 10.5. The applicable temperature range of dynamic wave stripping was wide, the removel efficiencies could reach 72.62% and 90.68% at 10 ℃ and 25 ℃,respectively. The stripping efficiency could be improved by increasing the gas-liquid ratio, but when it was above 129, the insignificant increase of gas-liquid specific stripping effect occurred. The concentration of influent ammonia nitrogen concentration within the examined range had slight effect on ammonia stripping. The results of orthogonal test demonstrated that the temperature variance was the largest, the variances of pH and gas-liquid ratio were the second, and the variance of influent ammonia nitrogen concentration was the smallest.Therefore, the most influence factor on stripping was temperature, then the second ones were pH and gas-liquid ratio, and the final one was initial ammonia nitrogen concentration. Compared with traditional stripping process,the optimum conditions of stripping process were 25 ℃, pH 10.5, gas-liquid ratio of 129 and stripping time of 5 h,and the corresponding total removal rate of ammonia nitrogen could reach 91.25%~94.15% with enhanced separation efficiency of ammonia nitrogen.