To help meet future water needs, a treatability study is being conducted by the St. Johns
River Water Management District in central Florida and CH2M HILL to quantify the treatment requirements and
costs for a potential surface water treatment facility to be located along the reach of the St. Johns
River between the southern end of Lake Monroe in Sanford and De Land. This pilot study will
identify the feasibility, appropriate use, treatment technologies and costs to use surface water to
offset groundwater demands.
Selecting treatment technologies for any water treatment system is driven primarily by drinking
water regulations and the meeting of consumer expectations. For surface water treatment, the
primary regulations are the Enhanced Surface Water Treatment Rules (ESWTR) and the
Disinfectant/Disinfection Byproduct (D/DBP) Rules. The planning process for any treatment
facility on the St. Johns River has a 5- to 10-year window. Therefore, upon construction of this
facility, compliance would likely be required for the Long Term 2 (LT2) ESWTR and Stage 2
D/DBP rules.
The approach to meeting these regulations is multibarrier treatment involving the following unit
processes:
coagulation and flocculation;
clarification;
filtration; and,
disinfection.
This approach requires each process to remove waterborne pathogens, with each process
operating at a high rate of efficiency. The effectiveness is cumulative, in that each unit process
helps the subsequent unit process work more effectively than if operated alone. The St. Johns River water has typical surface water characteristics for Florida. The characteristic
dark brown color of the water is due to the organics in the water. These organics are mostly
dissolved humic and fulvic matter. Total organic carbon concentrations are often in excess of 30
mg/L with colors exceeding 400 Pt-Co. Additionally, the St. Johns River has unique
characteristics due to the brackish content of the water. This brackish surface water has total
dissolved solids (TDS) concentrations ranging from 400 milligrams per liter (mg/L) to 1,060
mg/L and chloride concentrations ranging from 139 mg/L to 455 mg/L. Because of these unique
characteristics, partial desalting must be used along with conventional treatment. Includes tables.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 220 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 7 |
| Published : | 03/05/2003 |
