AWWA WQTC71489

The Central Arizona Project (CAP) is required to provide potable water at its eight pumping plants which are part of the CAP canal system to comply with state and federal Occupational Safety and Health (OSHA) requirements for plant personnel and visitor use. These plants are too remote to economically connect to a public water system. CAP decided to install a small package treatment system at the remote pumping plants to treat raw Colorado River water to potable standards, and connect to each plant's existing, though non-potable, domestic water system. Water treatment objectives consisted of the following: particulate (turbidity) removal; pathogen removal/inactivation; and, disinfection byproduct (DBP) control. Potable water turbidity standards have been established by the Surface Water Treatment Rules (SWTR), which require turbidity levels to be 0.3 NTU or less in 95 percent of all samples, with a maximum limit of 1.0 NTU in any sample. After considering three treatment technologies (pressurized granular media filters, cartridge filters, and ultrafiltration membranes), ultrafiltration technology was selected. Three commonly used package ultrafiltration systems, each with a target production rate of 50 gpm, were compared for potential use in the CAP pumping plants. These systems included the GE HomeSpring, the Siemens Memcor XP, and the WesTech AltaPac. Each system uses chlorine tolerant hollow fiber membranes and is operated in an outside-in mode with a flux range from 22 to 40 gfd. However, each ultrafiltration system has specific components and unique operating characteristics. The primary difference between the systems is the backwash/chemical cleaning mode. Site visits to three facilities, which have been treating surface water with each ultrafiltration system, were conducted to compile performance and operational experience of each facility/ultrafiltration system. Includes table, figures.