EnviroMix enables enhanced BNR, reduced DO, and cost savings with BioMix system

Water Conserv II WRF in Orlando, Florida 

BioMix nozzles and nozzle headers seamlessly integrate with the existing diffused aeration system. 

In 2016, the City of Orlando completed facility improvements at the Water Conserv II Water Reclamation Facility (WCIIWRF) that enhanced the plant’s biological nutrient removal (BNR) capabilities. The primary goal of the upgrade was to install a mixing system in the first anoxic basin of each train in order to reduce dissolved oxygen (DO) concentrations and enhance denitrification.

Challenge

Prior to the project, a low level of diffused air was used to mix the anoxic zones. However, it was determined that even low levels of air increased the DO concentration enough to impact denitrification. To improve mixing within the basins and reduce DO levels, EnviroMix’s BioMix Compressed Gas Mixing System was evaluated against hyperboloid mixers.

Solution

After thorough analysis, BioMix was chosen as the solution with the lowest total cost of ownership — capital costs were similar between the two options, but O&M costs were significantly lower with BioMix. In a 20-year net-present-worth life cycle analysis, BioMix’s total cost was shown to be $218,000 lower than the hyperboloid mixers.

When compared to hyperboloid mixers, BioMix provides optimal mixing for solids suspension with a significant reduction in power consumption. In addition to energy savings, use of the system allowed the city to minimize structural modifications to the basins furthering the cost effectiveness of BioMix. All maintenance items of the BioMix system, including the compressors and control system, are installed out of the basins in easily accessible areas. 

The BioMix system uses only one operating compressor as opposed to multiple mechanical mixers, significantly reducing maintenance for the City of Orlando. 

Results

Since the facility improvements were completed, WCIIWRF has realized:   
Enhanced nutrient removal and treatment performance stability. 
Improved effluent quality and ease of operation — the BNR process was enhanced due to improved mixing and optimal anoxic conditions. 
Improved process recovery time following high-flow events, such as hurricanes — BioMix improved plant resiliency and allowed for a quicker recovery of effluent quality following periods of high inflow.

The BioMix Compressed Gas Mixing System enhanced denitrification within the biological process and improved overall plant performance. Implementation of the BioMix system played a vital role in this highly successful project for the City of Orlando.

Short-duration bursts of compressed air fired intermittently produce optimal anoxic mixed conditions with a coefficient of MLSS variation of less than 2%.