PECI was retained by the City of Lewisville to conduct emissions testing and dispersion modeling for prediction of off-site odor impact from odorous process units at the WWTP. The treatment processes found to cause the greatest off-site odor impact include the influent splitter boxes, fine screens and aerated grit basins.
PECI was also retained to provide design services for odor control improvements at the headworks processes. Foul air from the influent splitter boxes, fine screens and grit removal basins is combined and handled by a single biotrickling filter or bioscrubber.
The foul air flow to effectively capture odorous emissions from the grit removal system was reduced by converting the aerated grit basins to vortex grit removal basins. The vortex grit removal units are being constructed within the existing aerated grit basins, saving on inlet and outlet piping modifications.
Screenings from five existing drum screens were previously directly discharged into five large dumpsters. Screenings disposal was simplified with a dual washer/compactor system. Benefits include reducing the volume and weight of screenings by about 50- to 80-percent and a reduction of odors by removing organics from the screenings.
The project was completed in 2016 for the bid amount of $3.2 million.
Odor Control Isopleths Showing Offsite Odor Impact