SDOX-CS CONTROLS HYDROGEN SULFIDE FOR ODOR PREVENTION
MT. GARDENS LIFT STATION
Application: Odor Control
Owner: Pima County RWRD
- Control Hydrogen Sulfide
Eliminate Odor Complaints
The SDOX-CS® oxygen injection system at Mt. Gardens was originally designed to keep the wet well aerobic for treatment of odor at the lift station. At the time, BlueInGreen and Pima County collectively agreed that 13 lbs of oxygen per day would likely accomplish this and resolve the odor issue.
Due to this relatively low oxygen delivery rate, a small SDOX-CS system – which does not typically have the capacity to pass 3-inch solids – was required. At the 13-lbs/day delivery rate, this SDOX-CS unit only uses 6 gpm of carrier water. Additionally, the flow rates into the wet well were significantly below expectations of the original design which frequently resulted in long periods of time between pump cycles.
AFTER OPTIMIZATION, THE SDOX-CS WAS ABLE TO DELIVER 50 POUNDS OF OXYGEN PER DAY, NEARLY 4 TIMES THE AMOUNT ORIGINALLY SPECIFIED.
The Pima County staff suggested that potable water be used to minimize installation costs and to reduce time between pump cycles during low flow periods. However, after system startup, the 13-lbs/day delivery rate and wet well injection location proved to be ineffective at eliminating odor complaints downstream of the force main discharge. The oxygen injection location was then moved to the force main. However, 13 lbs/day was insufficient for keeping the entire forcemain aerobic. Therefore, this also proved ineffective at eliminating downstream odor complaints.
AS REQUESTED BY PIMA COUNTY OFFICIALS, THE SDOX-CS WAS ABLE TO CONTROL THE PPM OF HYDROGEN SULFIDE WITHIN AN ACCEPTABLE RANGE.
With the opportunity to optimize the system, BlueInGreen temporarily modified the SDOX-CS to maximize its delivery. With the new configuration, the system was able to deliver 50 lbs/day of oxygen, nearly 4 times the amount originally specified. However, the system utilized more carrier water to do so. With promising initial results, BlueInGreen decreased the oxygen delivery rate to 30 lbs/day. This delivery rate proved insufficient for odor elimination, and the system was returned to a 50 lbs/day delivery rate. The unit was operated at this rate for 9 days until the optimization plan period ended.
The SDOX-CS was able to control the ppm of hydrogen sulfide at the Discharge and Medlar Place within an acceptable range. In a typical installation, the unit would be designed to utilize the wastewater flow as the carrier stream. This would allow the facility to save on costs associated with chemical alternatives. The Mt. Gardens Lift Station was still able to capitalize on several other benefits of the BlueInGreen system, including zero chemical storage, handling and delivery, as well as reduced corrosion to infrastructure and no increase in chemical or solids loading to the wastewater treatment plant.