PROJECTS

Our latest project involves phosphorus removal from Lake Jesup, an “impaired” Central Florida lake. AquaFiber responded to, and was awarded a contract on, an Invitation to Negotiate (a form of a Request for Proposal) a performance-based contract for phosphorus removal from Lake Jesup. The contract requires us to remove one metric ton of phosphorus from the Lake’s water column annually. Our customer, the St. John’s River Water Management District (SJRWMD), has an eventual goal to remove 15 – 21 metric tons of phosphorus per year from Lake Jesup. Here is how the District describes the challenge:

Lake Jesup, on average, is a 10,660-acre lake in the Middle St. Johns River Basin in Central Florida. The St. Johns River Management District’s Governing Board in 2002 designated this area as a priority basin for restoration of water quality and fish and wildlife habitats as part of Florida’s Surface Water Improvement and Management (SWIM) program. The lake’s watershed is highly urbanized and several tributaries deliver untreated stormwater from urban Orlando into the lake.

Lake Jesup is verified as an impaired water body by the Florida Department of Environmental Protection (FDEP) due to excess nutrients (nitrogen, phosphorus and unionized ammonia). FDEP recently adopted total maximum daily loads (TMDLs) for these pollutants for Lake Jesup. The District is developing pollution load reduction goals (PLRGs) for nitrogen and phosphorus that will assist FDEP in later refinements to their TMDLs. SJRWMD has defined target in-lake concentration for total nitrogen and phosphorus that would restore the lake to state water quality standards. The annual average Trophic State Index (TSI) values for Lake Jesup exceeded 60 every year from 1996 through 2002.

In the 1960s and 1970s, Lake Jesup and its tributaries received effluent from wastewater treatment plants, and an EPA study during that time found a TP concentration in the lake ranging from 0.485 – 0.500 mg/l. Lake Jesup no longer receives direct effluent, and the average TP concentration has significantly dropped (average of 0.166 mg/l from 1991 to 2002). Lake Jesup had a median annual TSI of 82 from 1992 to 2002, showing little change over that period.

There are several tributaries delivering significant TP loads to Lake Jesup – Howell Creek, Gee Creek, Soldier Creek on the western end of the lake, and several creeks on the eastern section of the lake delivering TP at high concentrations. Currently flows are monitored on the western creeks but not in the eastern creeks. Water quality models estimate that between 19.8 and 46.3 Ton/yr of TP enters Lake Jesup from the watershed (Jia 2005, FDEP 2005, Parsons 1995) at concentrations ranging from 0.007 mg/l to over 1.0 mg/l at different times of the year (SJRWMD). The average concentration range was from 0.062 – 0.595 mg/l.

While some tributaries have higher discharges and consequently larger annual loading rates, all tributaries would benefit from TP load reductions.

 

 

 

 

"Flowways" at our Lake Apoka proof of concept facility.