Arsenate removal using a hybrid system of adsorbents and a microfiltration membrane

Abstract

Arsenate in drinking water is a serious concern to millions of people around the world. Although various technologies have been developed in recent years, one of the most sustainable technologies for removing arsenate from water in developing countries is the use of absorption in the treatment of drinking water. This study determined the surface characteristics and arsenic removal efficiency of a new adsorbent Fe–Mn–Si (FM-α) and compared the performance of a hybrid system using FM-α and a microfiltration membrane with a hybrid system using a traditional adsorbent (zero-valent iron, ZVI) and a microfiltration membrane. Surface area analyses employing electron microscopy and energy-dispersive X-ray spectroscopy obtained a specific surface area of FM-α (17.2 m²/g) that is 14 times that of ZVI (1.2 m²/g). The arsenate removal efficiency of FM-α was 51 and 14% at pH 4 and 7, respectively, in the presence of phosphate, and 89 and 94% at pH 4 and 7, respectively, in the presence of humic acid; all these values were higher than those of ZVI under the same treatment conditions. Hybrid systems using FM-α had a higher bed volume than hybrid systems using ZVI. For example, the hybrid system using FM-α fed with only As(V) had a bed volume of 7,600, which is more than 10 times that of the hybrid system using ZVI. In terms of flux and pressure, hybrid systems using FM-α had more stable flux and pressure during operation over 47 d than the hybrid systems using ZVI. Additionally, hybrid systems using FM-α tended to rapidly and almost completely return to initial flux levels after backwashing, compared with recovery of only ~25% of the initial flux in hybrid systems using ZVI. The hybrid systems using FM-α accumulated more arsenate than the hybrid systems using ZVI. Overall, hybrid systems using FM-α had a higher bed volume, more stable flux and pressure, and better arsenate removal efficiency even in the presence of competing substances. Thus, these systems are a promising sustainable solution for the removal of arsenate and organic matter from water in developing countries.

Keywords:

• Arsenate
• Organic matter
• Drinking water
• Adsorbent
• Microfiltration membrane

Acknowledgment

This research was supported by the National Research Foundation of Korea (NRF-2013K1A3A9A04043230) and partly funded by Korea Ministry of Environment (MOE) as “Advanced Technology Program for Environmental Industry” (E315-00015-0412-1).

Notes

Presented at the 8th International Conference on Challenges in Environmental Science & Engineering (CESE-2015) 28 September–2 October 2015, Sydney, Australia