AWWA ACE63062

The 2004 Florida Legislature directed the Florida Department of Environmental Protection (DEP) and the South Florida Water Management District (SFWMD) to evaluate the use of reclaimed water to augment groundwater using the canal systems of southeast Florida. The legislature recognized that the discharge of reclaimed water into canals may provide an environmentally acceptable means of supplementing water supplies and enhancing natural systems, but also that there are water quality and quantity issues that needed to be better understood. This part of the study involved the proposed recharge of the SFWMD regional canal system using highly treated reclaimed water to maintain canal levels and recharge the Biscayne aquifer during the dry season, thereby reducing demands on the Everglades and Lake Okeechobee. Eight wastewater treatment facilities (WWTF) were selected for evaluation primarily because of their location and large wastewater flows. In this study three different treatment alternatives for wastewater were evaluated for potential canal discharge of reclaimed water. First, the modified Bardenpho configuration (Alternative 1), a biological nutrient removal (BNR) process was evaluated to achieve advanced wastewater treatment (AWT) standards (5:5:3:1) (BOD5, TSS, TN, TP). Second, a membrane biological reactor (MBR) technology was evaluated to provide a higher effluent quality than AWT, and was configured to incorporate BNR (Alternative 2). And, third, reverse osmosis (RO) membranes were incorporated after MBR to provide the highest quality effluent (Alternative 3). The results of the evaluation showed that Alternative 2 provides slightly better removal of nitrogen and phosphorus than Alternative 1, but Alternative 3 involving the use of RO after AWT and MBR removes nitrogen and phosphorus down to extremely low levels important for avoiding canal water quality enrichment. The study also evaluated the use of the SFWMD's South Florida Water Management Model (SFWMM) to determine the affect of reclaimed water discharges and the ability of reclaimed water discharges to coastal canals to reduce discharges from the SFWMD's regional system, which includes Lake Okeechobee and the Water Conservation Areas. This study suggested that both water supply and environmental benefits were enhanced but that additional modeling would be necessary to confirm these benefits. Includes 2 references, tables, figures.