Speedway WWTP UNOX and Biosolids Upgrade
American Structurepoint led the design to rehabilitate the town of Speedway's wastewater treatment facility. The $4.6 million improvements included upgrading the PSA oxygen generation system, improving efficiency of the oxygen transfer system in the biological process (UNOX), structural repairs to the biological tank, adding blanket level detectors for the final clarifiers as a secondary control strategy, replacement of 50-year-old pipes and pumps that vibrate too much in the anaerobic digestion system, addition of a cake pump for the belt filter press system, and addition of a storage nitrification denitrification reactor (SNDR) for the anaerobically digested sludge to reduce the ammonia concentration in the filtrate.
The PSA, UNOX, and SNDR projects are designed to resolve plant performance issues that resulted in an agreed-upon order. The PSA and UNOX improvements are estimated to reduce power consumption by almost 40 percent due to high-efficiency motors, SCADA and control systems that will allow the main air compressor to unload when oxygen production is not required, and adjustable frequency drives on the mixers. The SNDR process will result in a more easily dewatered cake and requires less polymer to dewater. The savings in polymer and disposal alone yields a predicted return on investment of 14 years. The SNDR process removes ammonia from the recycle stream, providing less ammonia for the biological process to convert to nitrate and thereby allowing the plant to reach compliance with the permit limits. Construction began in early 2011 and was completed in early 2012.