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Turbidity removal effect and surface charge shift for electrochemically treated retentate without coagulant addition
Toshiya Uchibori1, Takeshi Fujino, Takashi Asaeda
1Department of Environmental Science, Saitama University, Sakura-ku, Saitama 338-8570, Japan.
Summary
Electrolytic treatment quickly thickens suspensions by forming dense aggregates without coagulants. This method significantly enhances turbidity removal, offering a superior alternative to traditional coagulants like alum.
Area of Science:
- Water treatment technologies
- Electrochemistry
- Colloid science
Background:
- Thickening retentate and removing turbidity are crucial in water treatment.
- Conventional methods often rely on coagulant addition, which can leave undesirable residues.
- Kaolin suspensions present challenges due to their colloidal particle fraction.
Purpose of the Study:
- To develop an electrolytic treatment for rapid retentate thickening.
- To enhance turbidity removal without adding chemical coagulants.
- To investigate the mechanisms behind electrolytic treatment's effectiveness.
Main Methods:
- Electrolytic treatment of kaolin suspension (200 NTU).
- Comparative analysis with alum coagulation.
- Measurement of aggregate size, turbidity removal, Al ion concentration, and surface charge.
- Investigation of electrochemical charging behaviors.
Main Results:
- Electrolytic treatment promoted dense aggregate formation and rapid thickening.
- Turbidity removal reached up to 75% on average, increasing with retention time.
- Enhanced removal was observed even with low Al ion concentration and stabilized pH compared to alum.
- Electrochemical treatment generated polymeric aluminum hydroxide species, leading to more effective adsorption layers.
Conclusions:
- Electrolytic treatment is an effective coagulant-free method for retentate thickening and turbidity removal.
- The mechanism involves the formation of defect-minimized adsorption layers by polymeric aluminum hydroxide species.
- This approach offers a promising alternative to conventional coagulant-based water treatment processes.
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