Field Characterization of External Grease Abatement Devices

Abstract

BSTRACT: This study characterized some of the physical and chemical features of large outside field grease abatement devices (GADs). 24-hour measurements of several food service establishments' (FSEs') influent GAD fiowrates indicated highly intermittent conditions with hydraulic retention times (HRTs) that exceeded the common recommendation (30 minutes) by two to five times. Investigation into the chemical characteristics of GADs indicated highly variable influent and effluent fat, oil, and grease (FOG) concentrations. Low pH and dissolved oxygen values were measured throughout the GAD, indicating the likely occurrence of anaerobic microbial processes. Detailed spatial and temporal observations of the accumulation of FOG and food solids were also discussed. Though the FOG layer remained relatively constant for all GAD configurations investigated, results indicated that commonly-used GAD configurations with a straight submerged inlet tee or no-inlet tee configuration may result in the transport of food solids into the second compartment. The present research showed increased accumulation of food solids in the first compartment with a retro-fit fiow distributive inlet. This retro-fit displays promise for potentially improving the separation characteristics of existing GADs. Water Environ. Res., 84, 237 (2012).

Longitudinal Study of Wastewater Greases and Their Potential for the Production of Biofuels

“…The variability of the GTW could also be due to the type of grease abatement device used at the restaurant or cooking facility. It was observed that FOG layers typically remained constant for different types of grease traps; however, food solids can accumulate in the first compartment or be transported depending on the inlet tee . The variability in inlet type at the various food services could explain some of the variability seen with the sediment layer.…”

Impact of microbial activities and hydraulic retention time on the production and profile of long chain fatty acids in grease interceptors: a laboratory study

“…All laboratory GI reactors in this study were operated with an intermittent flow pattern that involved pumping artificial wastewater through the reactors twice a day to simulate the two diurnal peak flows of real GIs. 12 The two pumping events lasted for one hour each and were separated from each other by five hours. All reactors were operated for 60 days in the dark and at room temperature (23-25 °C).…”

“…First of all, the sizing of GI for a given wastewater stream could result in different hydraulic retention times (HRTs), which in the field typically ranges from 0.3 to 4.4 days. 12 Different HRTs may affect the quantity of LCFAs produced by microbial activities within GIs, as the incubation time often controls the production of bacterial lipases that catalyze oil hydrolysis. 7,13 Different HRTs may also affect the LCFA composition in GIs, as faster biodegradation of unsaturated LCFAs than that of saturated LCFAs was previously observed in an activated sludge process.…”