The Town of Taos, located in northern New Mexico and with a population of 8,000 was awarded an arsenic removal treatment system as part of the US EPA’s Arsenic Removal Demonstration Program in January, 2005. The town had a new well, storage tank and booster pump system that was scheduled to be connected to the Town’s distribution system and placed into service only after the arsenic removal system was ready. The Severn Trent Services’ SORB 33® arsenic removal system was selected, over two other competing technologies, for use at this demonstration site.
Taos’ Well No. 8 system had an existing building, shown below, to house the motor control center, chlorination unit
and booster pumps. The well pump has a capacity of 480 gallons per minute (gpm) and delivers water to a 50,000 gallon tank on a hill above the building. There is also enough room in the building to locate the arsenic removal system.
The well water has a slightly elevated arsenic level of 14 micrograms per liter (μg/L) and is low in TDS, but it has a very high pH of 9.5.
SORB 33® System Description
Severn Trent Services’ proposal to the EPA and Taos was for one of its automated package units, a SORB 33® APU-450, with a normal capacity to treat 450 gpm or all of the well pump’s capacity. The system was designed with no bypass at the request of the Town even though the arsenic level was low enough for bypass/blending. The 21’L x 7’W x 9’H skid-mounted unit consisting of three 5¼-Ø FRP adsorbers and 195 ft³ of Bayoxide® E33P iron oxide media was installed in four parts through the wall behind the system. The system included 15 automatic valves, 5 for each adsorber, which are controlled by a PLC in the control panel with a touch screen human machine interface (HMI).
System design data is summarized on the next page. It is configured for parallel flow. Piping is schedule 80 PVC
with PVC butterfly valves. The system was started up in February 2006.