Physical and chemical characteristics of fat,oil and grease deposits in Chinese kitchen drainage systems

Abstract

The blockage of kitchen pipes seriously affects people’s normal life. Minimal research is reported on fat, oil and grease (FOG) deposits in kitchen drainage pipes in China. In this study, 16 collected kitchen pipe deposits from various pipe materials are tested using physical and chemical methods. Experimental results show that samples have rough surfaces with porosity between 7 and 20% and appear as milky white lumps with moisture content less than 30% and the density is less than 1.000 g/cm³. Larger diameter of pipes can short blockage period. The oil content varies in deposits. The frequency of restaurants using oil is eight times higher than the family kitchen and the number of oil using is four times. The types of all free fatty acids in the samples are C14–C20, and the content of C₁₆H₃₂O₂ is the highest. The highest metal content in the sample is calcium ion, up to 605.036 mg/L. Not only samples have a discontinuity formation process, but also characteristic absorption spectrum between 1300 and 1420, 1550 and 1610 and 1745 cm⁻¹ also draws that saponification reaction occurs during the formation of these samples. The composition and formation rules of FOG deposits analysed can provide reference to prevent and remove blockages in the pipes and develop the kitchen drainage system in China.