AWWA MTC53686

In May 2000 the Marco Island Lime Softening Water Treatment Plant (LSWTP) wasexpanded from 5.0 to 6.67 million gallons per day (mgd) with the addition of a1.67 mgd immersed membrane ultrafiltration (UF) system. The Marco Island LSWTPwas previously limited to 5.0 mgd of production based on conventional sand filtercapacity. This facility provides treatment of surface water from the Marco Lakesin Collier County, Florida. Raw water from the Marco Lakes supply is pumped 9.5miles to the Marco Island LSWTP. The raw water source contains elevated color(>40 cpu), total organic carbon (TOC) (>12 mg/L), UV-254 (0.181), hardness (>350mg/L as CaCO3), and moderate total dissolved solids (TDS) (>900 mg/L).Implementation of a full-scale 1.67 mgd UF process downstream of the Marco Islandlime softening process demonstrated an average filtered turbidity of 0.05 NTUversus an average sand filtered finished water turbidity of 0.1 NTU. Includes 9 references, tables, figure.