Groundwater treatment using a pilot scale system of integrated electrodialysis and electrolysis

Abstract

Groundwater is an important source of freshwater worldwide; however, it could include severe contaminants such as lead, arsenic, and nitrate threatening human health. This study examined the practicability of a pilot-scale integrated electrodialysis (ED) and electrolysis (EL) system for ground-water treatment in Ho Chi Minh City, Vietnam. Under circulation of the influent, the ED process exhibited a sufficient removal of arsenic and common cat(an)ions, being above 95% within 30–45 min. With fixing each 35 min/cycle (electrical conductivity <10 µS/cm), the ED had a water recovery rate of up to 83%, which sustained high contaminant removal for 22 working days. Besides, the EL system is subsequently posed for eliminating nitrogen species from the concentrated flow of ED via the denitrification. Ammonium (40 mg/L) was effectively eliminated (~100%), while nitrate (225 mg/L) was removed by 50%. The nitrate remaining was accounted to the total nitrogen concentration, which indicates that the EL effectively oxidized/reduced nitrogen-based species to nitrogen gas. These findings suggest a potential use of the proposed system for groundwater treatment with a high recovery rate and efficiency.