Yuma Area Office
The Water Quality Improvement Center
Research Facilities and Test Equipment - Chemistry Research Units
High Velocity Corrosion Test Unit
The desalination of brackish water presents frequent problems of corrosion to process piping, pumps, valves, and other fluid handling equipment. Although plastic and fiberglass can be used for low pressure applications, steel or other metallic materials must be used in high pressure applications. Three independent corrosion test units test the high velocity (dynamic) and static corrosion effects of metallic materials. In order to conduct this testing, a special impeller assembly and tank were fabricated by the Government. Past Water Quality Improvement Center (WQIC) studies evaluated the corrosion characteristics and costs of super-austenitic stainless steels in comparison to austenitic stainless steel, high nickel alloys, and other materials such as aluminum bronze.
Chlorine generation system - A safe and cost-effective alternative to gaseous chlorine is the chlorine equivalent, sodium hypochlorite, which is produced through electro-chlorination. On-site generation of sodium hypochlorite occurs through applying a direct current electrical field to brine solutions. Oxidation of the chlorine found in brine occurs with a simultaneous reduction of water to gaseous hydrogen. While still in the electrolytic cell, chlorine immediately reacts to form hypochlorous acid, which in turn, reacts with the sodium ions to form sodium hypochlorite. Three-and-one-half pounds of salt, fifteen gallons of water, and two-and-one-half kilowatt hours of electrical power are required to produce one pound of sodium hypochlorite.
The Chlor-Tec Electrochlorinator is capable of producing 12 pounds of sodium hypochlorite at 0.8% concentration per day while the Mixed Oxidant Electrochlorinator (MIOX) is capable of producing 4 pounds of sodium hpyochlorite at 0.6% per day. These concentrations are considerably less than what can be found in household bleach (5%) or industrial bleach (12.5%). The average chlorine dosage is about 10 mg/L to a maximum of 15 mg/L.
The Lamella Clarifier is an integrated flash/ flocculation tank consisting of a rapid mix and flocculation compartment, two variable speed drive mixers, and eleven 2x4-inch lamella plates. The lamella plates are set 2-inches apart and act like separate sedimentation basins by increasing the effective settling surfaces and directing settled material down the plates to the collection hopper. The unit includes an automatic sludge blow-down system, magnetic flow meter, and flow controller.
Portable Multi-Media Pressure Filter
The multi-media pressure filtration equipment is a portable system with a skid base and a frame designed to support the equipment in a mobile environment. The skid is also constructed of non-corrodible materials and contains suitable mounting provisions to allow securing to the floor of a trailer. It consists of a pressure filter 36 inches in diameter and 7.5 feet in height that can withstand a maximum of 30 gallons per minute.
Element Check Apparatus (ECA)
The ECA provides a means to check reverse osmosis membrane elements on an individual basis to evaluate their performance, conduct membrane studies, and perform chemical cleaning and treatments such as glycerine soaking. During performance checking, the ECA simulates the operation of the first element in a first-stage control block. It is individually tested for product flux and salt rejection under controlled conditions. The results can be compared with previous calculated standards and adjusted to reflect the current operating conditions.
Up to five 8.5-inch Hydranautics membranes or up to four 12-inch Fluid Systems membrane elements can be run at a time during performance testing. The ECA high-pressure feed pumps are operated from 300 to 350 gallons per minute with a pressure range of 60 to 500 psi. The ECA is designed to measure all product and reject flows, conductivities, pH, chlorine residuals, and feed and reject pressures on a single instrument panel. Although designed and built by the Bureau of Reclamation to support WQIC research, it can be easily reconfigured to meet individual water treatment needs.
Element Drying Apparatus
While the Yuma Desalting Plant remains in a ready-reserve, non-operational status, measures must be taken to prevent damage to the reverse osmosis elements during periods of unuse. Traditionally, these elements would be placed in cold storage at a considerable cost. As an alternative to this, a more economical and practical means of storage and preservation has been proposed to alleviate both the biocide and cold storage costs. This alternative involves drying the elements and storing them in ambient conditions. The process of drying reverse osmosis membranes includes treatment with a mixture of surfactant, isopropyl alcohol, and glycerin while varying mixture concentrations, temperatures, and treatment duration. The WQIC currently has 3 twenty-four element drying apparatus for the following membrane element sizes: 12-inch x 60-inch, 8 –to 8.5 x 40-inch, 3.25 x 40-inch.
For more information about the Research Facilities at the Water Quality Improvement Center, contact Angela Adams, Desalting Group, through email or by phone at 928-343-8114.
For Telecommunications Relay Services (TRS) Dial: 711