Feeding FOG to Thermal Oxidation Units It's All in the Presentation

The Hampton Roads Sanitation District (HRSD) has developed a simple and effective system for recovering the energy value of the fat, oil and grease (FOG) waste receipts at its Williamsburg Treatment Plant (WTP). The solids and FOG production at this treatment plant are thermally oxidized by multiple hearth incineration, with the energy recovered in the form of reduced natural gas consumption. The FOG waste received at this site is discharged into the septage receiving station, from which it is screened and enters the wet side of the treatment plant. There is no separate collection of FOG waste at present, but given the success of the program, such is anticipated as a future improvement that will increase the effectiveness of the energy recovery program.This paper will address the following topics from this program:FOG receipts.Process flow diagram for grease handling and incineration.Mass balances for the separate grease and solids streams and the blended incinerator feed stream.Sustainable rates of co-incineration.Energy recovery