A Low Cost Constructed Wetland Alternative for Improving the Effluent Quality of a Lagoon Wastewater Treatment Plant

Fisherman Bay Sewer District (FBSD) owns and operates an aerated lagoon wastewater treatment plant with a hypochlorite calcium tablet system for plant effluent disinfection. Highly varying level of solids in combination with nitrite in the lagoon effluent presented a significant challenge for the plant operator to maintain appropriate chlorine dosage for ensuring consistent compliance with plant effluent limits for total chlorine residuals (TRC) and fecal coliform. Study showed that solids in the lagoon effluent were products of the treatment process including old sludge, biomass and algae. Majority of the solids were erratically varying algae that were identified as the primary contributing cause for effluent chlorine residual noncompliance and occasional fecal coliform, TSS and CBOD5 violations for individual samples. A constructed wetland with shredded tire media was built for removing lagoon effluent solids. The performance of the wetland for CBOD5, TSS, fecal coliform removals is reviewed.