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Fluoride and nitrate removal from brackish groundwaters by batch-mode capacitive deionization
Wangwang Tang1, Peter Kovalsky1, Di He1
1School of Civil and Environmental Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia.
Water Research
|August 18, 2015
Summary
Capacitive deionization effectively removes fluoride and nitrate from brackish groundwater. Competitive ion adsorption affects removal efficiency, but a predictive model aids process optimization.
Area of Science:
- Environmental Engineering
- Water Treatment Technologies
- Electrochemistry
Background:
- Capacitive deionization (CDI) is an emerging technology for water desalination and ion removal.
- Fluoride and nitrate are common contaminants in brackish groundwater, posing health risks.
- Understanding ion removal mechanisms in CDI is crucial for effective water treatment.
Purpose of the Study:
- To investigate the feasibility of fluoride and nitrate removal from brackish groundwater using batch-mode CDI.
- To analyze the impact of operating conditions (flow rate, initial concentrations) on fluoride removal.
- To develop and validate a transport model for predicting dual-anion removal in CDI.
Main Methods:
- Batch-mode capacitive deionization experiments were conducted.
- Systematic variation of flow rate, initial fluoride, and initial NaCl concentrations.
- Development of a simplified one-dimensional transport model for dual anions (fluoride, chloride, nitrate).
Main Results:
- Fluoride removal efficiency increased with lower initial fluoride concentrations.
- Higher initial chloride concentrations reduced fluoride removal due to competitive electrosorption.
- The developed transport model accurately described the dynamic removal of fluoride and chloride, and was extended to nitrate removal.
Conclusions:
- Batch-mode CDI is a feasible method for removing fluoride and nitrate from brackish groundwater.
- Ion competition significantly influences removal efficiency, particularly in the presence of high chloride concentrations.
- The validated transport model provides a robust tool for optimizing CDI design and operation for trace ion removal.
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