Sodium alginate – Tween 20 dispersant for sustainable in-sewer control of fats, oils, and grease (FOG) accumulation

. Dispersion efficiency, assessed through particle size distribution and apparent viscosity measurements, revealed optimal performance at 8 % Tween 20 and alkaline conditions. For dispersants containing 8 % Tween 20, median particle sizes (D50) were determined as 1.17 ± 0.0 µm at pH 7, 0.24 ± 0.01 µm at pH 9, and 0.21 ± 0.01 µm at pH 12. In addition, apparent viscosity decreased drastically from 357.8 Pa·s to 0.46 Pa·s (99.87 %) at pH 7, 0.19 Pa·s (99.95 %) at pH 9, and 0.06 Pa·s (99.98 %) at pH 12. The dispersion mechanism involves interfacial tension reduction, electrostatic repulsion, and steric stabilisation, ensuring the stable suspension of FOG particles. The SAT dispersant containing 8 % Tween 20 at pH 9 is recommended for field application based on its dispersion efficiency, alignment with typical sewer operating pH, and with regulatory discharge pH limits. Validation using real FOG deposits from a grease interceptor confirmed significant particle size reduction and long-term stability of dispersed FOG. These results establish a proof-of-concept for the application of biopolymer dispersants as a scalable and environmentally friendly strategy for proactive FOG management in sewer systems.