Evaluation of Odor Emissions from Solids Handling Processes

The South Central Regional Wastewater Treatment and Disposal Board (SCRWT&DB) owns and operates a 24 mgd wastewater treatment plant (WWTP) located in Delray Beach, Florida.This facility primarily serves the Cities of Delray Beach and Boynton Beach. The first phase ofthe WWTP was originally constructed in 1979, and was located in a rural area of Delray Beach. Since the WWTP's initial construction, growth and development expanded to the point wherehigh density residential units have been constructed within 100 feet of the facility's property line.Because of the proximity to businesses and residential areas, the Board has been continuouslycommitted to an aggressive odor control strategy. The strategy has proven to be very effectiveconsidering the WWTP's proximity to residences and business. There have been multiple odorcontrol units installed over the years to successfully manage odors emanating from theheadworks facilities, aeration basins and solids handling facilities. Although consistent odorcontrol has been achieved through the Board's productive efforts, rare unanticipated occurrences related to mechanical breakdown or adverse weather conditions have caused odors to exceed the treatment capacity of the odor control units resulting in odor complaints. The most recent occurrence of odor complaints has been associated with the solids handling process at the facility due to odors from the sludge tanks. The Board desires to continue its aggressive odor control strategy and requested assistance from Hazen and Sawyer to evaluate solutions to these issues which extend beyond normal operation.An investigation to pinpoint the specific odorant was first performed to identify treatment requirements. Results from the investigation were evaluated to isolate odorants and pilot test was implemented to test treatment options. Pilot testing of a carbon stage to polish odor constituents not captured by the existing wet chemical scrubber serving this area was selected to address the odorants detected.This paper presents the results of the pilot testing of a carbon stage to address odorants that were found and not treated by the existing wet chemical scrubber. Objectives of the study were to identify the proper treatment method (i.e., carbon product) that would effectively remove the odor constituents which were the source of odor complaints. A pilot unit containing a carbon product was installed on the existing solids handling odor control system to determine the product's performance in removing the suspect odorants. The pilot test occurred over a selected two day period representing a “worst case” scenario for odor compounds existing within the odor stream. Pre-and-post treatment odor samples were obtained and sent to certified labs for analysis to verify the inlet conditions and removal efficiencies achieved through the carbon unit. Results of the pilot testing demonstrated significant removal of odor compounds. It was also concluded that the odorants remaining after carbon scrubbing were minor and generally not considered a nuisance.