School of Engineering, RMIT University, Melbourne, 3000, Australia.
School of Engineering, RMIT University, Melbourne, 3000, Australia.
Chemosphere. 2024 Jun;358:142183. doi: 10.1016/j.chemosphere.2024.142183. Epub 2024 Apr 27.
The accumulation of fat, oil and grease (FOG) deposits in sanitary sewer systems is a significant cause of sewer overflows, mainly due to their tendency to adhere to pipe walls. The aim of this study is to (i) develop laboratory-prepared FOG deposits using a mixture of iron (Fe) and aluminium (Al) metal ions, fatty acids, saccharides and cooked oils, in addition to various sanitary waste materials such as paper towels, wipes and pads and (ii) examine the characteristics of these FOG deposits. The goals of this study were to (i) gain a deeper understanding of the impact of sanitary waste on the formation of FOG deposits and (ii) discuss the detailed physiochemical properties of these FOG deposits. The findings revealed that FOG deposits can vary in nature, appearing as either a smooth, paste-like substance or a coarse, semi-solid material, depending on the types of waste present in the sewer. Analysis of the fatty acid profile indicated that the FOG deposits with wipes have the highest viscosity (3.2 × 10 Pa s) and larger composition of smaller chain saturated fatty acids (caprylic acid 0.64%, undecanoic acid 5.61%, lauric acid 4.65%, myristic acid 3.21% and palmitic 8.38%). In contrast, FOG deposits with Fe and Al metal impurities have higher heat resistance and thermal stability (melting point of 125 °C) and have larger composition of long chain fatty acids. Furthermore, FTIR analysis confirmed that these FOG deposits are composed of metallic salts of fatty acids, aligning with samples from sewer lines. Our results suggest that FOG deposit formation involves the aggregation of excess calcium, which compresses free fatty acid micelles, and a saponification reaction between the calcium aggregates and free fatty acids. This research illuminates the complex processes behind FOG deposit formation and their varied characteristics, providing valuable insights into potential strategies for preventing FOG-related sewer blockages.
脂肪、油和油脂 (FOG) 在污水系统中的积累是污水溢出的一个主要原因，主要是因为它们有附着在管壁上的趋势。本研究旨在：(i) 使用铁 (Fe) 和铝 (Al) 金属离子、脂肪酸、糖和烹饪油以及各种卫生废物材料（如纸巾、擦拭物和卫生护垫）的混合物，制备实验室制备的 FOG 沉积物；(ii) 研究这些 FOG 沉积物的特性。本研究的目的是：(i) 深入了解卫生废物对 FOG 沉积物形成的影响；(ii) 讨论这些 FOG 沉积物的详细物理化学性质。研究结果表明，FOG 沉积物的性质可能有所不同，根据污水中存在的废物类型，可能呈现出光滑的糊状物或粗糙的半固态物质。脂肪酸分析表明，含有擦拭物的 FOG 沉积物具有最高的粘度（3.2×10 Pa s）和较大比例的短链饱和脂肪酸（辛酸 0.64%、十一烷酸 5.61%、月桂酸 4.65%、肉豆蔻酸 3.21%和棕榈酸 8.38%）。相比之下，含有 Fe 和 Al 金属杂质的 FOG 沉积物具有更高的耐热性和热稳定性（熔点 125°C），并且具有更大比例的长链脂肪酸。此外，FTIR 分析证实这些 FOG 沉积物由脂肪酸的金属盐组成，与来自污水管道的样品一致。我们的研究结果表明，FOG 沉积物的形成涉及过量钙的聚集，这压缩了游离脂肪酸胶束，以及钙聚集体和游离脂肪酸之间的皂化反应。本研究阐明了 FOG 沉积物形成背后的复杂过程及其多变的特征，为预防 FOG 相关的污水堵塞提供了有价值的策略。
