EnviroMix achieves 90% O&M savings with BioMix Compressed Gas Mixing System

North Regional WRF in Manatee County, Florida 

Short duration bursts of compressed air mix an area of the tank 2–3 times per minute. 

Manatee County operates three regional wastewater treatment plants that offer reclaimed water for irrigation to farms, golf courses, and private residences in the region. In 2017, the county upgraded the North Regional Water Reclamation Facility (NRWRF) located in Palmetto, Florida.

Challenge

Equalization of flow and loading to the treatment process ensures consistent and efficient nutrient removal, and it guarantees the supply of reclaimed water for reuse. As part of the upgrade, NRWRF constructed three 1-million-gallon influent flow equalization tanks, enabling the plant to process wastewater more efficiently and at a higher quality.  

In the equalization tank system, return activated sludge is introduced to provide odor control and to facilitate anaerobic selector operation, thereby enhancing biological phosphorus removal. The WRF needed a solution for the equalization tanks that delivered complete mixing while maintaining an anaerobic environment.

Solution  

BioMix Compressed Gas Mixing was selected to provide high-efficiency, low-maintenance mixing in the equalization tanks. Ensuring optimal anaerobic conditions for biological nutrient removal (BNR), BioMix provides mixing without the introduction of measurable oxygen.  

One duty and one standby 30 HP compressor provide the mixing energy for all three equalization tanks. A traditional diffused aeration mixing system would require ten times the horsepower to provide equivalent mixing. A local control panel at each tank controls the mixing air from the compressor system and distributes it uniformly to each tank as necessary. Optimal mixing energy for each tank is automatically adjusted for the range of depth operation, ranging from a few feet of liquid depth to a maximum of 23 feet. 

Compressors under a canopy meet the process mixing air demands of the BioMix system for all three equalization tanks. 

Results

Manatee County selected the BioMix system based on its lowest total cost of ownership versus mechanical and diffused air mixing technologies. Use of the BioMix system in lieu of conventional diffused air mixing has resulted in annual energy cost savings of over $150,000 for the NRWRF.

Due to the efficiency of the BioMix system, the facility’s O&M costs will be reduced by 90% versus conventional diffused air mixing, saving Manatee County millions of dollars over the life the system.