| Electrolytic manganese residue(EMR)is produced in large quantities in the production process of manganese metal,and its harmless and resource recovery process is slow,resulting in large area of EMR accumulation.In the process of stacking,the untreated leachate of EMR will enter the surrounding environment,thus endangers the ecological safety and personal safety.In this paper,some electrolytic manganese enterprises and some EMR reservoirs were investigated firstly,and the basic physical and chemical characteristics of EMR and manganese ores in China were analyzed.Permeable reactive barrier groundwater remediation technology(PRB technology)has the advantages of sustainable in situ and simultaneous treatment of a variety of pollutants,convenient installation and construction,and low maintenance cost in later stage.Therefore,PRB technology is used to,aiming at EMR leachate pollution of groundwater,or aiming at the regional emergency environmental accidents caused by heavy rains,explore the single and mixed reactive medium removal of ammonia nitrogen,manganese in the simulated leachate,and adjust the performance of p H value,in order to block the migration of EMR reservior pollutants to provide theoretical basis.In this paper,clinoptilolite,modified clinoptilolite,bamboo charcoal,activated carbon,roseite,steel slag,blast furnace slag and manganese sand were used as a single reactive medium.The column experiment of single reactive medium was carried out for 15 days.The changes of ammonia nitrogen,manganese and p H in the sampling port and water outlet of each experimental group were characterized,so as to analyze the removal effect of each single reactive medium,and clarify the column dynamic changes of each single reactive medium over a long period of time.The results show that the modified clinoptilolite modified by salt and roasting has a lower interlayer force,a larger specific surface area and a larger total pore volume than clinoptilolite,and a better removal performance for ammonia nitrogen.H~+in the activated carbon column competes with ammonia nitrogen in the adsorption activity center of activated carbon,while manganese ion in the simulated leachate competes with H~+in the adsorption site continuously.Therefore,the activated carbon showed a more continuous removal effect on manganese ion,but the removal effect on ammonia nitrogen was poor.Because of its good adsorption,ion exchange and hydrolysis properties,steel slag has a good removal effect on manganese.However,the manganese concentration at the sampling outlet and outlet of the steel slag column fluctuates,which may be due to the influence of the adsorption and ion exchange properties of the steel slag during the hydrolysis process.Because of its physical and chemical adsorption properties,manganese sand has a better removal effect on manganese in the early stage of the experiment.The other four kinds of single reactive media have poor blocking performance.On this basis,four reactive media,including modified clinoptilolite,activated carbon,steel slag and manganese sand,were selected to form different mixed reactive media.The column experiment of mixed reactive medium for 20 days was carried out.The results showed that on the 20th day,the ammonia nitrogen removal rates were 98.5%,89.8%,91.7%and 93.6%,respectively,and the manganese removal rates were 79.2%,97.4%,92.0%and 81.0%,respectively.In this paper,combined with the removal rate of ammonia nitrogen and manganese,p H regulation ability and the concentration of heavy metals(Fe,Co,Ni and total Cr)at the outlet,the mixed reactive medium((mixed column 2)composed of steel slag-activated carbon mixed medium and modified clinoptilolite filled with 35 cm and 15 cm length respectively has the most feasible inhibiting performance of contaminants in the leachate of EMR. |
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