Treatment Of Nitrate-contaminated Water Using The Technology Of Intermittently Ion-exchange And Electro-regeneration

As one of the important sources of drinking water, groundwater is playing an increasingly important role in our life. In recent decades, the monitoring results indicated that nitrate pollution in groundwater is worsening. As closely related to human health, the problem has attracted widespread national attention.Compared with the traditional groundwater pollution treatment technologies, Electrodynamics (EK) and Permeable reactive wall (PRB) technology is able to realize continuously in-situ treatment and with the advantage of relatively inexpensive; also could reduce the surface treatment facilities, reduce exposure and pollutants disturbance to the environment. However, both EK and PRB used for nitrate removal showed that PRB filled with Fe⁰ as media during the removal of nitrate produces would produce more toxic NH4+, and EK governance cycle is very long, often take months or even longer.In order to achieve in-situ treatment, this study combined the respective advantages of EK and PRB technology to study the establishment of groundwater nitrate pollution control technology for in situ EK-PRB. According to take advartage of high adsorbed efficiency of PRB to NO₃^-, and EK accelerate the migration of NO₃^- on PRB in order to realize efficient and harmless nitrate treatment.To choose the most suitable adsorption media, firstly, strong base styrene anion exchange resin 201×7 and nitrate selective resin D407 in the water adsorption of NO₃^- , two anion and cation exchange resin (001×7 and D001) respectively with different mixed ratio under the condition of the water adsorption of NO₃^- and SO₄^2-, Cl^- and NO₃^- on the resin under the co-existence of NO₃^- adsorption were studied, the results showed: the adsorption capacity of 201×7 is better than D407, the adsorption capacity were 59 mg NO₃^-/mL resin and 25 mg NO₃^-/mL resin respectively; in the same experimental conditions, the results of dynamic adsorption illustrated that the volume ratio between 201×7 and 001×7 was 6:4, there was hardly NO₃^- existed of the effluent water and the conductivity of effluent was less than 5μs/cm. At the condition of some other ions existed except of NO₃^-, the resulted illustrated that the adsorption capacity of 201×7 is bigger than D407. Duo to there must be some other ions in the real environment, so as the adsorb material 201×7 is better than D407.According to a series of regeneration experiments, the resulted showed that after 10h's static and 80h's dynamic electro-regeneration, the NO₃^--N concentration of the effluent was less than 10mg/L and the regeneration rate of the resins was as high as 60%.The results of static and dynamic experiments illustrated that the intermittent technology of adsorption and electro-regeneration can realize the removal of NO₃^- in water and achieve the purpose of reducing the energy consumption and avoiding secondary pollution caused by chemical regeneration.