Research

The discharge of Fat, Oil, and Grease (FOG) into the environment by industry and domestic sewage continues to be a significant public health and environmental health concern worldwide. This discharge has led to sanitary sewer overflows (SSOs) due to the formation of FOG deposits that accumulate on pipe walls and restrict wastewater flow. Annually, 3 to 10 billion gallons of untreated wastewater are released due to the FOG deposit-related SSOs costing $25B in clean-up. Many research studies have been conducted that investigated the FOG deposit formation mechanism, factors affecting FOG deposit formation mechanism, and physicochemical properties of FOG deposits. Literature suggests that concrete corrosion is a process that can aid in FOG deposit formation; however, no research has been conducted to develop alternative concrete materials for sewer line construction that can potentially reduce FOG deposit formation and its adhesion inside the sewer collection system. Samrin's research aims to explore the development of alternative binder material for sewer line construction. Samrin also aims to understand the adhesion mechanism of the FOG deposit on sewer line surfaces.

The accumulation of fat, oil, and grease (FOG) in sewer pipes reduces its carrying capacity and results in Sanitary Sewer Overflows (SSOs). FOG deposits are formed from a saponification reaction between calcium and long-chain free fatty acids (LCFFA). Previous research has shown that concrete corrosion is a significant source for calcium ions and takes part in the FOG formation mechanism. Additionally, concrete made with blended Supplementary Cementitious Materials (SCMs) and cement has shown a significant decrease in calcium leaching under corrosive conditions. However, no laboratory studies have been performed to assess the effect of this reduced calcium leaching on FOG formation and deposition on sewer surfaces. Therefore, this study primarily aims to reduce the contribution of concrete corrosion on FOG deposit formation by using Fly Ash (FA) as an SCM. In this study, two High Volume Fly Ash (HVFA) concrete materials, CPC50FA and CPC75FA, were made using 50% and 75% replacement of cement by FA, respectively. After 90 days of leaching under corrosive conditions, 50% and 75% FA replaced sample showed 75% and 86% reduction in calcium leaching, respectively. Samples were also tested for FOG formation and deposition on concrete surfaces in synthetic wastewater. After 30 days of FOG deposition test without background calcium, CPC50FA and CPC75FA samples showed 55% and 80% reduction in FOG deposition on the sample surface, respectively. When background calcium was added in FOG formation test, CPC50FA and CPC75FA samples showed a 55% and 67% reduction in FOG deposition on concrete samples, respectively. The results of this study suggest that a significant decrease in calcium release can be achieved through the use of FA as a cement replacement which can eventually reduce the FOG deposit formation inside sewer lines. This strategy could be a sustainable solution for the reduction of FOG related SSOs, maintenance, and cleanup costs as well as reduce potential adverse environmental effects from coal-fired power plants by-products by recycling FA.

The adhesion of fat, oil, and grease (FOG) deposits in sewer pipes causes 25% of the Sanitary Sewer Overflow (SSOs) in the U.S. Additionally, the sewer collection system in the U.S is old and requires replacement or renovation. One potential solution to the FOG deposit accumulation challenges in the collection systems is to design new sustainable sewer line construction materials that reduces the adhesion of these deposits on sewer pipe walls. Previous research has only reported the FOG deposit formation mechanism and the factors affecting those formations. Yet, no research has been performed to understand the FOG deposits adhesion mechanism. This study will provide a complete understanding of the FOG deposit adhesion mechanism inside sewer lines by testing various materials, i.e., concrete, PVC, granite, limestone, and porous ceramic materials for a 30-day FOG deposit adhesion test. This project will be the first to evaluate the FOG deposit adhesion mechanism and the factors affecting the adhesion phenomena on different sewer line surfaces. Once the adhesion mechanism is understood, sanitary sewer materials surfaces can be altered accordingly to avoid FOG deposit-related SSOs. Therefore, this project will also provide North Carolina wastewater collection system utilities with strategies to develop new construction materials or potentially design future coatings that can enhance existing alternative materials to limit or reduce the FOG deposit accumulation on the sewer surface

1. Kusum, Samrin A., Mohammad Pour-Ghaz, and Joel J. Ducoste. "Reducing fat, oil, and grease (FOG) deposits formation and adhesion on sewer collection system structures through the use of fly ash replaced cement-based materials." Water Research 186 (2020): 116304.

2. Kusum, Samrin Ahmed, Mohammad Pour-Ghaz, and Joel Ducoste. "Evaluating Alternative Binder Materials for Sewer Collection System Concrete Structures to Reduce Fat, Oil, and Grease Related Sanitary Sewer Overflows." Proceedings of the Water Environment Federation 2018, no. 3 (2018): 258-266.

3. ZaferSiddik, Md Abu, Abu Sufian Mohammad Asib, and Samrin Ahmed Kusum. "Spatial distribution of the effect of temperature and rainfall on the production of boro rice in Bangladesh." Am. J. Remote Sens 1, no. 8895 (2013): 39.