Activated Sludge Diffusion Provides Cost Effective Biological Odor Control at Two Texas Wastewater Treatment Facilities

During recent expansions of the Rowlett Creek Regional WWTP in Plano, Texas and the Wilson Creek Regional WWTP in Lucas, Texas, activated sludge diffusion (ASD) biological odor control systems were installed to treat hydrogen sulfide (H2S) and other gaseous compounds. The ASD systems treat foul air collected from various sources, including headworks and primary distribution structures, covered primary clarifiers and primary clarifier weirs, and a primary sludge holding tank. The foul air is conveyed to aeration basin blowers where it is mixed with ambient air and sent through fine-bubble diffusers in activated sludge basins. A previous paper evaluated the performance and cost effectiveness of the Rowlett Creek ASD system after one year of operation. The Rowlett Creek ASD system has now been in continuous operation for six years and inlet H2S has increased, so additional performance testing was conducted. At the same time, performance testing was also conducted for the Wilson Creek ASD system. In addition, an extensive visual inspection of the Rowlett Creek ASD system was conducted to evaluate the condition of the piping systems and aeration blowers. Based upon the high H2S removal efficiency, low operating cost, and condition of the piping and blowers demonstrated at these Texas WWTPs, the ASD process is worth considering as part of the overall odor control program at other facilities.