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Determining the performance of lignin-based flocculants in improving biosludge dewaterability
Hamed Ghazisaidi1, Vincent Wang1, Pedram Fatehi2
1Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada.
Journal of Environmental Management
|October 29, 2022
Summary
Lignin-based flocculants (LBF) effectively dewater biosludge from pulp and paper mills, reducing costs and environmental impact. Combining LBF with anionic polyacrylamide (APAM) further optimizes performance, offering a sustainable alternative to synthetic polymers.
Area of Science:
- Environmental Science
- Chemical Engineering
- Materials Science
Background:
- Biosludge dewatering is crucial in pulp and paper mills to reduce handling and disposal costs.
- Synthetic polymers are commonly used but raise environmental concerns.
- There is a growing need for sustainable alternatives like biopolymers derived from industrial by-products.
Purpose of the Study:
- To evaluate the efficacy of lignin-based flocculants (LBF) in improving biosludge dewaterability.
- To compare LBF performance with conventional synthetic polymers.
- To explore synergistic effects of LBF with anionic polyacrylamide (APAM).
Main Methods:
- Biosludge dewatering was assessed using Capillary Suction Time (CST) and dry cake solids.
- Lignin-based flocculants (LBF) were tested as standalone and dual conditioning agents with anionic polyacrylamide (APAM).
- Performance was benchmarked against a commercial synthetic polymer (Zetag8165).
Main Results:
- LBF significantly improved dewaterability, reducing CST from 72.7s to 23.3s and increasing dry cake solids to 13.9%.
- Dual conditioning with LBF and 0.1% APAM achieved 13.8% dry cake solids using only 3% LBF.
- LBF addition reduced particle surface charge, promoting agglomeration and enhancing dewatering.
Conclusions:
- Lignin-based flocculants show significant promise for sustainable biosludge dewatering.
- Optimizing lignin modification and combining with anionic polymers can enhance efficiency.
- This approach offers a greener alternative to synthetic polymers in wastewater treatment.
