EnviroMix provides low ORP mixing for RAS fermentation and anaerobic selectors with BioMix system

Water Reclamation Facility in Loveland, Colorado 

BioMix nozzles seamlessly integrate with diffused aeration. 

In 2018, the city of Loveland, CO, upgraded and expanded the Loveland Water Reclamation Facility (WRF). The biological nutrient removal (BNR) and digester improvements project was focused on three main objectives:

• Meeting regulatory requirements for the reduction of nitrogen and phosphorus released to the Big Thompson River. 
• Increasing capacity to meet population growth. The plant was re-rated from 10 million gallons per day (MGD) to 12 MGD allowing for an additional 15 to 20 years of growth. 
• Replacing aging infrastructure. 

The project utilized a Construction Manager-at-Risk (CMAR) process which permitted the construction managers to be an integral part of the design/bidding process and allowed them to preselect equipment. The CMAR process enabled them to make technology selections based on the highest quality equipment and lowest total cost of ownership, as opposed to simply being based on lowest initial cost. 

Challenge

The upgrade utilized side stream return activated sludge (RAS) fermentation to improve biological phosphorus removal efficiency and comply with permitted phosphorus discharge limits. Two factors that are critical for the RAS fermentation process are:

• An oxidation reduction potential (ORP) environment of less than -250 mV.  
• Low mixing energy to avoid air entrainment.  

The WRF needed an energy-efficient solution for multiple applications that could deliver complete mixing with proven negligible oxygen transfer.

Solution

EnviroMix’s BioMix Compressed Gas Mixing was selected for the RAS fermentation basin, anaerobic selector, and anoxic selector. BioMix systems can accommodate multiple applications, leveraging common compressors and controls. The technology provides very low mixing energy, minimizing air entrainment and consistently producing an ORP environment of -425 mV.  

Loveland’s custom control panels 

Additionally, BioMix offers unparalleled flexibility — the system is able to operate independently or concurrently with aeration in the anoxic swing zones, and it allows operators to adjust frequency and duration of mixing to produce optimal anaerobically mixed conditions in the RAS fermentation basins.

Results

Loveland’s BioMix system:

• Delivers annual energy savings of $45,000 versus submersible mixers. 
• Requires one duty and one standby compressor instead of up to 18 mechanical mixers. 
• Supports an ORP environment of less than -425 mV in the RAS fermentation process.
• Operates independently or concurrently with aeration in the anoxic swing zones. 

Since the upgrade, levels of nitrogen and phosphorus being released to the Big Thompson River have been significantly reduced. The quality of the treated water being discharged back into the river is now higher than the quality of the water removed upstream for the city’s drinking water. 

Easy to install press technology piping feeds air to the in-basin nozzle headers