Donax Wastewater Reclamation Facility Upgrades Improve Water Quality

by SC Publisher Shannen Hayes

The Donax Wastewater Reclamation Facility is the only active centralized wastewater treatment facility on Sanibel and an upgrade project began in 2016 to improve the quality of the reclaimed water, reduce nutrient loading and extend the life of the facility. It’s scheduled to be completed in March 2021.

“We are proud of our central sewer system and to continue protecting water quality,” said Director of Community Services Keith Williams. “The treatment facility is pretty standard for the industry, but this will be a better performing facility.”

The facility upgrades will help reduce the amount of nitrogen and phosphorus that is in the water by about 50 to 70 percent. This nutrient removal process is imperative to help protect and improve water quality in the Gulf of Mexico, San Carols Bay, Pine Island Sound and the Sanibel River. It will also improve the quality of water distributed across the island.

Specific upgrades include a new flow equalization basin, new pre-treatment screens, conversion of the treatment process from a Modified Lidzack-Ettinger (MLE) process to a four stage Bardenpho process, the addition of a Membrane Bioreactor (MBR) to the treatment process and the construction of a new electrical building.

The state-of-the-art facility works by receiving raw wastewater from across the island through a system of pipes and lift stations. The wastewater is then screened to remove large solids and sand, before being treated through a biological process to remove suspended solids, organic matter and inorganic nutrients.

Following treatment, the wastewater is finally disinfected before becoming reclaimed water and made available for irrigating three golf courses on the island and other properties along the distribution lines.

The upgrade project budget is $20,132,100 and the city has secured a total of $4.037 million in grants from the Florida Department of Environmental Protection and the Federal Emergency Management Agency. The remaining balance will be funded by the city’s utility revenue.

“It is great to have support from the city and the community on this project,” said Williams.

The original plant, which served a small portion of the island, was purchased by the city in the 1990s from a utility provider. After assuming operation and upgrading the facility, the city began systematically expanding the municipal centralized sewer system. Since then, 99 percent of private and commercial properties have been removed from septic.

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