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PROJECT OVERVIEW: This facility will be the second full-scale facility of its kind in Indian River County and the nation. Through engineered design and flow control, high levels of biomass productivity can be maintained. Predictable nitrogen and phosphorus removal results from the routine recovery of excess productivity. Several Best Management Practice(BMP)s are used for this project: primary screening using self-cleaning trash rakes; grit/sediment removal; biological nutrient removal using the algal nutrient removal facility;additional suspended solids removal using micro-screening or other highly efficient screens; final effluent polishing using high quality wetland systems; and disinfection of effluent used for irrigation reuse. Additionally, the harvested algal biomass is a useful byproduct. Recovered biomass is processed into marketable end products including high grade compost or livestock feed. An AGNRF system will remove dissolved nutrients from up to 10 million gallons per day of stormwater and canal water and from up to 1.5 million gallons per day of reverse osmosis reject water from the South County Reverse Osmosis (RO)Treatment Plant. The RO reject water(currently discharged into the South Relief Canal untreated)will be blended with the canal water and the ANRF will remove dissolved nitrogen and phosphorus from the blended water. Hydrogen sulfide present in the RO reject water will be dissipated into the atmosphere as the mixture flows over the ANRF surface.The treated water will be returned to the South Relief Canal where it will continue its journey to the IRL. The ANRF uses a patented water treatment technology developed specifically to enhance water quality of polluted waters through the active cultivation of attached algae upon an engineered surface. By cultivation is meant the production and periodic harvesting of the attached algae (epiphytic and periphytic) and the community of organisms that become established on and around the algae. This living community of plants and organisms is known as algal turf and includes not only the algal biomass, but also associated invertebrates, bacteria, fungi, organic residues, and inorganic precipitants. Through the community's biological and chemical dynamics, nutrient pollutants are removed from the water column, dissolved oxygen is increased, and oxidation of reduced substances is facilitated. The result is a treated effluent reduced in nutrients, high in dissolved oxygen, and relieved of many potentially biologically deleterious and toxic substances. One or more final polishing filters, similar to wastewater treatment type filters, will be included in the treatment train downstream of the ANRF to remove all remaining solid particles from the treated water and a linear wetland system will provide final polishing. The Algal Nutrient Removal Facility offers the advantage of high areal removal rates for both nitrogen and phosphorus, which result in reduced land area requirements and treatment costs.' Effluent from the ANRF process is highly oxygenated, often exceeding saturation during the daytime, and typically well above 5 mg/1 dissolved oxygen (DO) during the nighttime. ANRF units have relatively short hydraulic detention, and thereby avoid accumulation of heavy sediment loads. As algae rely heavily upon dissolved bicarbonate, carbon dioxide and carbonate as a carbon source,pH levels within the ANRF effluent can increase during the daytime as alkalinity shifts towards hydroxyl alkalinity. This change in water chemistry allows engineered ANRF systems to be optimized for the precipitation and recovery of pollutants including phosphorus. ANRF units have also been shown to be effective at removing ammonia and nitrate + nitrite nitrogen; and recovering trace metals and select organic compounds. The ANRF technology was specifically developed to offer low cost treatment even under low nitrogen and phosphorus conditions. PC South will greatly improve the IRL's health by significantly removing suspended solids and dissolved nitrogen and phosphorus from the waters of the IRFWCD South Relief Canal before the waters enter the IRL,while increasing oxygen levels. This will benefit and protect seagrasses and associated fauna, providing them with an environment suitable for their growth and reproduction. As seagrasses are preserved and proliferate, fish and wildlife populations will increase. The potential for dangerous IRL algal blooms, including macroalgae such as Gracilaria sp.,caused by high nutrient loadings will also be greatly reduced. A secondary(future)benefit will be the creation of a significant source of treated water for irrigation purposes for commercial, industrial, and residential users, thus lowering their consumption of water from the surficial and Floridian aquifiers, thereby promoting water conservation and preserving groundwater. This will also benefit the IRL by reducing the quantity of freshwater discharged into it on a daily basis. Another benefit is the creation of very high quality 1 For example,STA systems may achieve phosphorus removal rates of 1-4 g-P/m2-yr or less than 0.10 Ib-P/acre-day; WHSTm units at high nutrient concentrations may achieve as high as 25 g-P/m2-yr removal or about 0.62 lb-P/acre-day; ANRF systems at comparatively low nutrient concentrations have been documented as achieving well over 50 g-P/m2-yr or 1.24 lb- P/acre-day. The implication is that an ANRF unit may provide treatment in 1 acre equivalent to 50 acres of STA or treatment wetlands. DEP Agreement No.G0353,Attachment A-1,Page 2 of 14 134