Project components
HDR subcontracted to New England Fertilizer Company (NEFCO) to complete facility design and construction of a biosolids processing facility for the Solid Waste Authority of Palm Beach County, Florida. HDR’s responsibilities included the overall management of the JV, permitting, design, procurement of engineered equipment, providing field staff during construction and holding an electrical subcontract and sub-consultant agreement for assistance with permitting and site development.
Highlights
- Design-build project
- Eliminates land application of biosolids
- Creates a useful product
- Utilizes landfill gas
- Serve multiple WWTPs
- A revenue generating project
The facility consists of biosolids receiving, storage, and processing areas along with electrical, mechanical and administrative areas, all of which are totally enclosed within a single 27,800 SF precast concrete building. Adjacent to the building are two 250 dry ton product storage silos, two Regenerative Thermal Oxidizers (RTO’s) with a 137’ tall by 7.5’ diameter steel stack, two cooling towers, two building odor control scrubbers, and standby generation equipment. The process consists of thermally drying the biosolids with the use of two triple bypass dryers and the appropriate supporting equipment. The dryer and RTO’s are fueled with landfill gas and backed up by natural gas.
Landfill gas fuels processing, reduces waste and air emissions
The $27.8M biosolids processing facility uses 100% landfill gas to process up to 600 wet tons per day of biosolids generated at five wastewater treatment plants in the county. The drying system uses two rotary drum dryers designed to utilize landfill gas, natural gas, or propane gas as fuel sources for heating the drying gas stream. A burner is employed with a smart valve system that employs multiple operational curves to ensure the correct air to fuel ratio is utilized depending on the fuel source selected. Landfill gas with methane concentrations between 50 and 60 percent is combusted in the burner generating the 30 to 40 million British thermal units (MMBTU)/hr per dryer of drying energy required. The process produces a high grade, marketable organic fertilizer for horticultural applications. The process is safe, sustainable, and can produce a revenue stream. Using the landfill gas makes use of a byproduct that was wasted as well as reducing air emissions at the landfill.
