Eco-friendly Hydrophobic Epoxy - Fly Ash Coating to Prevent Fat, Oil and Grease Deposition in Sewers

The deposition of fat, oil, and grease (FOG) from food service and residential sources in sewer pipes causes frequent blockages, sanitary sewer overflows (SSOs), and high maintenance costs, mainly due to saponification reactions that create calcium-based, insoluble materials (fatbergs). The aim of this study is to create an eco-friendly and low-cost hydrophobic coating by mixing locally available biomass fly ash with epoxy resin to reduce FOG adhesion in concrete sewer pipes. The specific objectives are: (1) to develop and characterize a novel fly ash - epoxy coating focusing on reduction in FOG deposition, and (2) to evaluate the coatings’ performance by comparing FOG deposit formation in concrete sewer pipes before and after coating application. This study presents an innovative, environmentally friendly coating material made with locally-sourced biomass-based fly ash to mitigate deposition of FOG in sewer pipes. This fly ash contains high silica (SiO₂) content that can contribute to increased hydrophobicity, reducing the odds of deposition of FOG. The coating is made by mixing fly ash particles less than 63 µm with clear epoxy sealer and ethanol. Coatings were prepared by varying fly ash content from 1 to 30 % (w/w%). Prepared solutions were applied to concrete/mortar paste substrates to evaluate the performance of each coating. Selected coatings after preliminary inspection were characterized using contact angle, sliding angle, scanning electron microscopy (SEM) imaging and energy-dispersed X-ray (EDX) spectroscopy. The coatings were subjected to 21 days of synthetic FOG wastewater treatment to simulate sewer conditions. The 5% of fly ash coating showed the highest contact angle, at 101.10, and FOG deposition was decreased by 48.5% compared to the uncoated sample. The results indicated that mixing epoxy with a lower amount (1% - 5%) of fly ash enhanced the coating’s hydrophobicity and demonstrated lower adhesion to FOG. By repurposing high-SiO₂ biomass fly ash waste, this method provides a sustainable and economically viable alternative to traditional FOG disposal practices, which can be used to address environmental waste disposal issues as well as the challenges associated with sewer infrastructure.