Bonita Springs bioreactor key to nitrogen reduction

Creative Cost-Effective Solutions

In 2012, the Florida Department of Environmental Protection requested that Bonita Springs work to reduce the total maximum daily load of nitrogen in its waterways to 0.74 mg/L under what is referred to as the “Everglades West Coast Basin Management Action Plan”. This tasked the city of Bonita Springs to reduce the amount of nitrogen along the Imperial River to more closely reflect those of pre-development and agriculture levels.

The FDEP has projected a target reduction amount of 60,000 lbs. by the year 2027, of which Bonita Springs is required to remove 9,303 lbs. The city has already successfully removed around 3,301 lbs. of nitrogen from the waterways through various removal methods and has been developing a sustainable long-term solution for the remaining 6,000 lbs. of nitrogen.

Under the guidance of city council, construction began on phase 1 of its bioreactor project located in downtown Bonita Springs. The goal for phase one of this project was to capture nitrogen removal ratings data as a baseline for FDEP to review and approve a removal efficiency rating for the bioreactor systems to facilitate the achievement of clean water statewide.

What is a Bioreactor?

Bioreactors use an anaerobic (oxygen-starved) environment to leverage naturally occurring denitrification bacteria to remove nitrogen in the water. They work by running water through pipes into basins filled with carbon-based filtering materials (ie: wood chips) that are used to collect the nitrogen and expel a more natural quality of water into local waterways. The woodchips act as a carbon source for anaerobic bacteria to colonize. The bacteria, in turn, strip nitrogen entrained in the stormwater runoff and convert it into nitrogen gas.

This technology is proving to be highly effective at nitrogen removal, while at the same time being very cost-effective. Over the last 20 years state and local governments