Identifying surface formation and adhesion mechanisms of FOG deposits on sewer lines

Abstract

Fat, oil, and grease (FOG) deposits contribute to 25 % of Sanitary Sewer Overflows (SSOs) in the U.S. and is exacerbated by the aging sewer infrastructure. As the U.S. contemplates renovating its sewer systems, employing sustainable materials that inhibit FOG deposit adhesion could be crucial. This study delves into the saponified FOG deposit formation and adhesion mechanisms on various materials—concrete, Poly Vinyl Chloride (PVC), granite, limestone, and porous ceramic. Through extensive testing, these materials were evaluated for chemical composition, surface roughness, porosity, zeta potential, and calcium leaching potential. The findings indicate that materials with high calcium hydroxide leaching potential, high pore pH, and low zeta potential tend to adhere significant saponified FOG deposits. Conversely, reducing surface FOG deposit formation and adhesion on sewer lines requires materials to be engineered with low calcium hydroxide leaching and high zeta potential. Considering these factors, granite followed by PVC exhibited the best properties that demonstrated no FOG deposit adhesion. The outcomes of this study not only provide insight into the physical interactions governing FOG deposit adhesion but also suggest a targeted strategy for material selection and modification in sewer system renovations to mitigate Sanitary Sewer Overflows.