Evaluation of iron-rich adsorbent to remove arsenic from groundwater in decentralized water supply treatment
Danh Quan Le, Thi Thuy Pham*, Hoang Giang Pham, Manh Khai Nguyen
University of Science, Vietnam National University (VNU), Hanoi
Received 14 August 2018; Accepted 23 October 2018
This paper evaluates the adsorption capacity of iron-rich adsorbent to remove arsenic from groundwater in decentralised water supply treatment; a pilot-scale with a capacity of 5 m3/day has been investigated at Cu Da Nursery School in Hanoi city, in which the concentration of arsenic in groundwater is abnormally high (175-400 µg/l). The pilot system was designed to include a series of processes, such as aeration, sedimentation, sand filtration, and adsorption, using the iron-rich adsorbent and activated carbon from coconut shells. The pilot system was tested with three operated modes. The results demonstrate that the treatment efficiency of the overall treatment processes was significantly higher than that of the traditional treatment system used by local people. After aeration, sedimentation, and sand filtration, the water quality was discovered to respond substantially in reducing iron by over 96% (from 8-12 mg/l to less than 0.3 mg/l) arsenic by 55 to 60%, but after iron-rich adsorbent, the concentration of arsenic decreased to less than 10 µg/l, which fulfils Vietnam National technical regulations concerning drinking water quality.
Keywords: adsorbent, arsenic, decentralised water supply groundwater.