Fractionation of FOG (fat, oil, grease), wastewater and particulate solids based on low-temperature solidification and stirring

Abstract

Wastewater treatment plants commonly employ upstream processes to reduce the influx of FOG into the bioreactors. This study demonstrates a process to separate FOG from the wastewater and particulate solids (PS) based on the combination of crystallization properties of FOG and density-based separation due to stirring. Three different process parameters such as water temperature, rate of stirring, time period of stirring were optimized to enhance the crystallization of FOG leading to its separation from the wastewater and PS. This concept was applied to an agro-industrial, coconut industry (CI) wastewater containing agglomerates of FOG and PS at concentrations of 2−50 g/L and 3−90 g/L respectively. An optimum temperature of 17 °C, stirring speed of 1440 rpm for 10 min., extricated, 85 % FOG from the agglomerates leading to the sedimentation of PS at a velocity of 12 cm/hr. The proposed process breaks the agglomerates of FOG and PS, resulting in the coalescence of FOG particles and sedimentation of PS.