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Hydrophobically-associating cationic polymers as micro-bubble surface modifiers in dissolved air flotation for
R K L Yap1, M Whittaker2, M Diao3
1UNSW Water Research Centre, School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW 2052, Australia; Centre for Advanced Macromolecular Design, School of Chemical Engineering, The University of New South Wales, Sydney, NSW 2052, Australia.
Water Research
|June 18, 2014
Summary
Researchers developed a novel polymer for the PosiDAF process, enhancing dissolved air flotation (DAF) for algae removal without coagulation. This modified polymer improves bubble adherence and achieves over 90% cell removal, demonstrating a viable water treatment method.
Area of Science:
- Environmental Engineering
- Water Treatment Technologies
- Polymer Chemistry
Background:
- Dissolved air flotation (DAF) effectively clarifies algae-laden water but relies on coagulation-flocculation, which is problematic during algal blooms due to unpredictable coagulant demand.
- The PosiDAF process aims to eliminate coagulation-flocculation by using polymers or surfactants to modify bubble charge, but challenges remain with bubble adherence and residual polymer concentrations.
Purpose of the Study:
- To synthesize and evaluate functionalized cationic polymers for the PosiDAF process, combining polymer bridging ability with surfactant-like hydrophobicity for improved bubble adherence.
- To assess the performance of these novel polymers in removing algae without coagulation-flocculation, contrasting them with a commercial polymer (polyDADMAC).
Main Methods:
- Synthesized poly(dimethylaminoethyl methacrylate) (polyDMAEMA) with hydrophobic pendant groups of varying carbon chain lengths.
- Functionalized polymers were used to create positively charged micro-bubbles for the PosiDAF process, eliminating the need for coagulation-flocculation.
- Evaluated cell removal efficiency and residual polymer concentrations in the treated effluent.
Main Results:
- All synthesized polymers produced positively charged bubbles and achieved over 90% cell removal in the absence of coagulation-flocculation, with a maximum removal of 99%.
- The polymer with the largest hydrophobic functionality demonstrated superior adherence to bubble surfaces, indicated by a highly anionic treated effluent and reduced residual polymer concentrations.
- Positively charged bubbles generated using functionalized polymers proved effective for algae removal, showcasing the viability of the PosiDAF process.
Conclusions:
- Functionalized cationic polymers can significantly enhance the PosiDAF process for effective algae removal without coagulation-flocculation.
- Optimizing hydrophobic functionality on polymers improves their adherence to bubbles, leading to higher efficiency and lower residual polymer levels in treated water.
- This approach offers a promising alternative for treating algae-laden water, addressing the limitations of conventional DAF methods.
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