ADVANCED WASTEWATER TREATMENT AND WATER RECLAMATION USING MEMBRANE FILTRATION IN CHARLOTTE, NORTH CAROLINA

In mid-2000, Charlotte-Mecklenburg Utilities realized the need to expand the treatment capacity of the McDowell Creek Wastewater Treatment Plant (an existing high quality, tertiary treatment facility) in order to meet the demands presented by a rapidly growing population in northern Mecklenburg County. In addition to the need to meet growing treatment demands, interest was growing in the area with regard to the availability of reclaimed water for reuse applications. When selecting treatment alternatives for the 3.0 mgd expansion, it was necessary to meet several objectives which included: (1) provide very high level of treatment to meet strict local discharge ordinances, (2) include a new reuse system to provide reclaimed water for use in golf course irrigation, spray irrigation of county owned land, and other potential reuse applications, (3) provide advanced treatment technology and design to ensure a consistent, reliable high quality plant effluent and reuse water supplies and (4) automate the treatment process as much as possible to minimize additional staffing requirements. One of the technologies chosen to meet these requirements is membrane filtration (microfiltration).This paper will present an overview of the decision to provide membrane filtration technology at the McDowell Creek Wastewater Treatment Plant which was driven by the overall basin stakeholders. Therefore, the process that was implemented for the basin study, including the establishment of a stakeholders group, the alternatives that were evaluated, and the deciding factors for the final recommendations will be discussed. Second, this paper will present an indepth look at the design process and final design of one of the first membrane treatment systems for reuse in the Carolinas. Membrane filtration design elements that will be discussed include: (1) integration of membrane filtration into the overall plant treatment process, (2) procurement of membrane filtration equipment, (3) membrane filtration system design and automation. When constructed, the 3.0-5.0 mgd McDowell Creek Wastewater Treatment Plant membrane filtration system will be one of, if not the largest membrane filtration system in the Carolinas.