Full Description

Gwinnett County, in metropolitan Atlanta, Georgia is one of the fastest growingcounties in the nation. The County's new 20 million gallons per day (mgd)advanced water reclamation facility, named the F. Wayne Hill Water ResourcesCenter (F.W.H. WRC) became operational in late 2000 and treats municipalwastewater to near-potable water quality. Biological processes at the plant aredesigned for complete nitrification, partial denitrification, and phosphorusreduction. Tertiary treatment processes include high pH lime (two-stageclarification/recarbonation and granular media filters), granular activatedcarbon (GAC) with preozonation, and final ozonation. Initial membrane evaluationstudies were performed in 1996 and 1997. These studies included flat-sheetmembrane bench tests, single-element tests, and short-term multiple-elementpilot-scale tests using microfiltration (MF), ultrafiltration (UF), andnanofiltration (NF) membranes. Because the F.W.H. WRC was not constructed at thetime, the testing was conducted at a nearby reclamation plant. Membrane product(effluent) water quality was very good, but the membrane cleaning interval wasshorter than desired. Full-scale high pH lime and GAC processes were installed inthe initial plant construction as well as a parallel membrane demonstrationfacility. The County decided to consider full-scale membrane processes for theplant expansion if membranes are shown in future studies to be technicallyfeasible, reliable, and economically justified for this application. If membraneprocesses are used for tertiary treatment, the 20 mgd physical/chemical processeswill be used to treat membrane waste streams. Because of the rapid growth inGwinnett County and the anticipated difficult and time-consuming permittingprocess, the design of a 40 mgd expansion to the plant (tripling the capacity ofthe facility to 60 mgd) was begun in mid-2000, even before the initial 20 mgdfacility was fully-constructed and operational. The initial design included aMF/UF pilot test facility which operates in parallel with the membranedemonstration systems and allows evaluation of several additional membraneproducts, many of which were not available at the time the demonstration plantwas designed in 1996 and 1997. The pilot plant also evaluates chemical coagulantaddition prior to some of the MF/UF systems for increased phosphorus and organicremoval capability and potential membrane operational improvement. Process designfor expansion of preliminary and biological treatment processes is occurringsimultaneously with the membrane demonstration and pilot test program. After 6 to12 months of membrane testing at the plant (beginning January 2001), membranetreatment will be compared to full-scale high pH lime and GAC processes, and adecision on which tertiary treatment processes for use in the plant expansionwill be made. The plant design will then be completed using the selectedprocesses. Includes tables.

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Edition: Vol. - No. Published: 05/01/2001 Number of Pages: 7File Size: 1 file , 220 KB