Treatment of Nitrate-contaminated groundwater using the Technology of intermittently Ion-exchange and Electro-regeneration

In this paper, the adsorption effects of two kinds of domestic anion exchange resins (201 × 7 and D407) to NO₃^- in water were compared, as well as the adsorption effects of the anion resins mixed with cation exchange resins (001 × 7and D001) to NO₃^- in water and performed the electro-regeneration experiment of the mixed resins were studied, in order to explore the feasibility of treating nitrate-contaminated groundwater by ionic exchange adsorption and electro-regeneration. The results of static adsorption showed that the adsorption quantum of 201 × 7 and D407 were 59 mg NO₃^-/mL resin and 25 mg NO₃^-/mL resin, respectively. 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 5 μs/cm. After the mixed resins were saturated, 10h´s static and 80h´s dynamic electro-regeneration experiment was performed, 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.