Laterite as a low-cost adsorbent in a sustainable decentralized filtration system to remove arsenic from groundwater in Vietnam

Thi Hai Nguyen; Hai Nguyen Tran; Hai Anh Vu; Minh Viet Trinh; Tien Vinh Nguyen; Paripurnanda Loganathan; Saravanamuthu Vigneswaran; Tuan Minh Nguyen; Van Tuyen Trinh; Duc Loi Vu; Thi Hoang Ha Nguyen

doi:10.1016/j.scitotenv.2019.134267

Laterite as a low-cost adsorbent in a sustainable decentralized filtration system to remove arsenic from groundwater in Vietnam

Sci Total Environ. 2020 Jan 10:699:134267. doi: 10.1016/j.scitotenv.2019.134267. Epub 2019 Sep 5.

Affiliations

¹ Faculty of Engineering and IT, University of Technology Sydney (UTS), Sydney, Australia; Institute of Environmental Technology, Vietnam Academy of Science and Technology, Hanoi, Viet Nam.
² Institute of Fundamental and Applied Sciences, Duy Tan University, Ho Chi Minh City, Viet Nam.
³ Institute of Chemistry, Vietnam Academy of Science and Technology, Hanoi, Viet Nam.
⁴ Institute of Environmental Technology, Vietnam Academy of Science and Technology, Hanoi, Viet Nam.
⁵ Faculty of Engineering and IT, University of Technology Sydney (UTS), Sydney, Australia. Electronic address: Tien.Nguyen@uts.edu.au.
⁶ Faculty of Engineering and IT, University of Technology Sydney (UTS), Sydney, Australia.
⁷ Faculty of Engineering and IT, University of Technology Sydney (UTS), Sydney, Australia. Electronic address: s.vigneswaran@uts.edu.au.
⁸ VNU University of Science, Vietnam National University, Hanoi, Viet Nam.

PMID: 31677468
DOI: 10.1016/j.scitotenv.2019.134267

Abstract

In the Red River Delta, Vietnam, arsenic (As) contamination of groundwater is a serious problem where more than seventeen million people are affected. Millions of people in this area are unable to access clean water from the existing centralized water treatment systems. They also cannot afford to buy expensive household water filters. Similar dangerous situations exist in many other countries and for this reason there is an urgent need to develop a cost-effective decentralized filtration system using new low-cost adsorbents for removing arsenic. In this study, seven locally available low-cost materials were tested for arsenic removal by conducting batch adsorption experiments. Of these materials, a natural laterite (48.7% Fe₂O₃ and 18.2% Al₂O₃) from Thach That (NLTT) was deemed the most suitable adsorbent based on arsenic removal performance, local availability, stability/low risk and cost (US$ 0.10/kg). Results demonstrated that the adsorption process was less dependent on the solution pH from 2.0 to 10. The coexisting anions competed with As(III) and As(V) in the order, phosphate > silicate > bicarbonate > sulphate > chloride. The adsorption process reached a fast equilibrium at approximately 120-360 min, depending on the initial arsenic concentrations. The Langmuir maximum adsorption capacities of NLTT at 30 °C were 512 μg/g for As(III) and 580 μg/g for As(V), respectively. Thermodynamic study conducted at 10 °C, 30 °C, and 50 °C suggested that the adsorption process of As(III) and As(V) was spontaneous and endothermic in nature. A water filtration system packed with NLTT was tested in a childcare centre in the most disadvantaged community in Ha Nam province, Vietnam, to determine arsenic removal performance in an operation lasting six months. Findings showed that the system reduced total arsenic concentration in groundwater from 122 to 237 μg/L to below the Vietnam drinking water standard of 10 μg/L.

Keywords: Adsorption; Arsenic removal; Decentralized filter; Groundwater; Laterite; Low-cost adsorbent.

MeSH terms

Adsorption
Arsenic / analysis*
Filtration / economics*
Groundwater
Vietnam
Water Pollutants, Chemical / analysis*
Water Purification / methods*

Substances

Water Pollutants, Chemical
Arsenic