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A study on arsenic removal from household drinking water
Tao Yuan1, Qi-Fang Luo, Jiang-Yong Hu
1Centre for Water Research, Department of Civil Engineering, National University of Singapore, Singapore. cveyuant@nus.edu.sg
Summary
Optimizing household arsenic removal requires effective floc separation. Ferric sulfate coagulation followed by sand filtration proved acceptable and affordable for safe drinking water.
Area of Science:
- Water Supply Engineering
- Environmental Chemistry
Background:
- Arsenic contamination in household drinking water is a significant global health concern.
- Effective and affordable arsenic removal methods are crucial for public health, especially in resource-limited settings.
Purpose of the Study:
- To determine the optimal coagulation protocol for arsenic removal from household drinking water.
- To investigate the mechanisms of arsenic removal during household coagulation.
- To evaluate the effectiveness of various coagulants, aids, additives, and floc separation systems.
Main Methods:
- Orthogonal array experiments based on the Taguchi method were employed to optimize operational parameters.
- The study investigated coagulants (ferric sulfate, aluminum sulfate), coagulant aids (kaolin, powdered activated carbon), and novel coagulants (polymeric ferric silicate sulfate).
- Arsenic removal mechanisms and adsorption isotherms (Langmuir equation) were analyzed under household operation conditions.
Main Results:
- Addition of kaolin and powdered activated carbon (PAC) did not improve arsenic removal efficiency with ferric sulfate or aluminum sulfate.
- Mixed coagulants (MFA) and polymeric ferric silicate sulfate (PFSiS) also failed to enhance overall arsenic removal.
- Coprecipitation was identified as the primary mechanism for arsenic removal, differing from conventional processes.
- An efficient floc separation system was essential for effective arsenic removal.
- Field experiments confirmed ferric sulfate coagulation combined with sand filtration as an acceptable and affordable method.
Conclusions:
- Standard coagulants and additives are not universally effective for optimizing household arsenic removal.
- Coprecipitation and efficient floc separation are key to successful arsenic removal via coagulation.
- Ferric sulfate coagulation and sand filtration offer a practical and economical solution for arsenic removal in household drinking water.