Enhancement Ponds
The enhancement marshes of the Arcata Wastewater Treatment Plant are responsible for removing some of the pollutants that remain from the other secondary treatment systems. Biological processes remove some levels of nitrogen, phosphorous, and heavy metals. By using enhancement marshes, the Arcata Wastewater Treatment Plant is able to forgo the use of machines and chemicals that would normally have to be used to achieve the same result.
Update 2014
The Enhancement Marshes of the Arcata Wastewater Treatment Plant are all currently in working order. They also continue to hold aesthetic and recreational value to the community.
On two visits to the site I encountered several walkers, joggers and bird watchers. Additionally, there appears to be abundant wildlife and biodiversity within these marshes.
According to Julie Neander, the City of Arcata is still conducting research on whether UV radiation, rather than Sulfur dioxide, is an appropriate method of dechlorination for this system. Currently, effluent from the the chlorine contact basin is divided into two streams, one portion being discharged directly into Humboldt Bay and the other being discharged into the system of enhancement marshes (EPA 1993) (see flow diagram for more info).
