Analysis of the characteristics of fat, oil, and grease (FOG) deposits in sewerage systems in the case of Korea

Abstract

Fat, oil, and grease (FOG) is the most common factor in sewer pipe blockage, and is the source of inundation and sanitary sewer overflows (SSOs). In the US and the UK, many inundation or SSO events occur each year, and a great deal of cost has been incurred to improve these situations. However in Korea, the database for sewer maintenance is still insufficient. In this study, FOG deposits collected in Korea were analyzed, and the characteristics of the FOG deposits were compared with the characteristics of the FOG deposits from places with different food cultures investigated in some of the major previous studies. Six FOG samples were collected from sewer mains and service laterals in the sewerage systems. The characteristics of the six samples were examined using FT-IR, Ca ion, and fatty acid composition analyses. The results of the FT-IR analysis indicated that the spectra defined in the previous studies of FOG were observed, and thus similarity to the samples of the previous studies was found. The proportions of the Ca ions included in the FOG of the six samples were 0.02–0.59%, and they are thought to be related with the maintenance of the discharging sources where the samples were collected. The results of the fatty acid composition analysis indicated that the proportions of total fat in the FOG ranged from 6 to 33%, and the proportion of total fat in the FOG decreased as the proportion of saturated fatty acid in the total fat increased. In some of the major studies performed previously in the US and the UK, saturated fatty acids accounted for a high proportion of the fatty acid compositions. However, the six FOG deposits analyzed in this study showed different compositions. It is thought that the fatty acid composition of FOG could vary with differences in the food culture, and the characteristics of FOG deposits could also vary. The data obtained from this study and future studies would be useful for the effective management of FOG deposits that are formed based on the food culture.