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The Desalination and Water Purification Research & Development Program Newsletter - No. 26 - Winter 2003

THE PROGRAM

Through the Desalination & Water Purification Research & Development (DWPR) Program, Reclamation has formed partnerships with private industry, universities, local communities, and others to address a broad range of desalting and water purification needs. The overall program objective is to reduce the cost of desalting and water purification technologies in order to augment U.S. water supplies. For more information, contact program manager, Tom Jennings, (303) 445-2130, or visit our website at http://www.usbr.gov/pmts/water/research/DWPR/.

NEW CONTRACTS

At the end of fiscal year 2003 (September 30), DWPR awarded 9 new financial assistance agreements - 5 research and studies and 4 pilot-scale systems. Abstracts of these agreements follow.

RESEARCH AND STUDIES (1 year agreements)

Menachem Elimelech (203-432-2789 or menachem.elimelech@yale.edu") and Yale University will study Chemical Cleaning of Fouled Reverse Osmosis Membranes (total project $117,258; Reclamation's contribution $89,000). Despite the vast efforts to reduce RO membrane fouling by improving membrane surface properties, optimizing operational conditions, or pretreatment of feed water, fouling is still inevitable. This research will:

  1. elucidate the mechanisms of chemical cleaning of RO membranes,
  2. evaluate the cleaning efficiency of membranes fouled under different physico-chemical conditions, and
  3. develop a methodology for screening and tailoring chemical agents for cleaning of fouled RO membranes.

This research will identify the controlling molecular-scale interaction forces during the foulant attachment (fouling) and detachment (cleaning) on the membrane surface under various solution chemistries, and will determine how the chemical cleaning agents affect these interactions and, hence, remove the foulant from the membrane surface.

Samer Adham (626-568-6005 or samer.adham@mwhglobal.com) and Montogomery-Watson-Harza will conduct an Evaluation of Biological Treatment of Perchlorate Impaired Waters (total project $406,825; Reclamation's contribution $100,000). Perchlorate contamination of soils and surface and groundwaters has become a significant new water treatment issue. The conventional water treatment systems that can be used to remove perchlorate concentrate but do not destroy the contaminant. This typically results in the reintroduction of this powerful endocrine disruptor back into the environment. The investigator proposes to design and construct a hydrogen-fed hollow-fiber membrane biofilm reactor, which will eventually be tested at pilot-scale, to provide quantifiable information on the enhancements in performance and ability of the system to treat perchlorate under a wide range of groundwater qualities.

John Pellegrino (303-579-9115 or jjp@boulder.nist.gov) and the University of Colorado will investigate Plant-Scale Engineering Design of Membrane Processes from Bench-Scale Measurements - Version 1 (total project $100,000, Reclamation's contribution $100,000). A self-contained software application will be created that provides material balances (permeate and retentate flowrates and compositions) and the pump energy for plant-scale RO, NF, UF, and MF membrane unit operations. This objective is unique in that the major input parameters can come from the data normally reported from bench-scale measurements performed in standard stirred-cell, crossflow (membrane swatch) apparatus, or small hollow-fiber modules. The purpose of the modeling software is to provide researchers, designers, and project managers with a tool to quantitatively assess the significance of technical advances that are often only described by reports of bench-scale measurements. The proposed software should, eventually, be integrated with the DWPR-sponsored WTCost© software (contact IMoch@aol.com or MChapman@usbr.gov).

Martin Peery (952-897-4277 or mhpeery@dow.com) and the Dow Chemical Company will collaborate with on manufacturers in an Industry Consortium Analysis of Large Reverse Osmosis/Nanofiltration Element Diameters: Designed for Manufacturability, System Capital Reduction, and Industry Acceptance (total project $253,385; Reclamation's contribution $100,000). The current industry standard size for RO and NF membrane packaging is an 8" diameter element with a 40" length. Pilot-studies conducted by Metropolitan Water District in Los Angeles have shown that larger diameter elements can result in substantial capital and operating cost savings for large scale systems. This project, through a consortium of membrane element suppliers, will create a new element diameter standard. By establishing a standard that has been agreed upon by several membrane element suppliers, the end users will be able to realize the maximum economic benefits of the use of larger diameter elements in their projects.

Robert Mace (512-936-0861 or robert.mace@twdb.state.tx.us) and the Texas Water Development Board will study Using Oil Fields for the Disposal of Concentrate from Desalination Plants, subtitled Please Pass the Salt, (total project $182,553; Reclamation's contribution $87,616). Communities interested in desalination as a means of meeting current and future water needs are concerned with what to do with the concentrate. One possibility in Texas and other oil-producing states is to inject the concentrate into oil fields. Because of the depth, geology, and depressurization of many oil fields, environmental impact would be minimal. In most cases, introduction of the concentrate would represent an improvement in the quality of water in the well fields. However, well injection permitting is a long and expensive process. This study will develop the scientific foundation upon which recommended policy changes can occur to allow an easier approval path for permitting of concentrate injection into oil wells.

PILOT-SCALE SYSTEMS (2 year agreements which are contingent upon successful completion of first year work)

Sing-Fong Cheah (303-285-5156 or scheah@itnes.com) and ITN Energy Systems, Inc. will test a Pilot Photovoltaic Reverse Osmosis Desalination System (total 2 year project $527,062; Reclamation's contribution $263,531). A portable, energy efficient solar desalination system can be the most cost effective and reliable solution for communities throughout the world with saline water and no access to electricity. Remote park lands, emergency relief efforts, and military operations could also benefit greatly from such a technology. This project is a follow-on of previously funded research work. ITN has developed and will perform a field test of a small scale PV/RO system. They will develop a research unit that will be field tested for 6 months to determine its effectiveness as a stand-alone unit with its own pretreatment. In addition, a pilot-scale unit will be developed and field tested for 3 months. Lastly, a number of modifications will be done to lower the capital cost of the system and make it more robust for treating natural waters. In addition to the technical tasks, an extensive economic and market analysis will be performed.

James Beckman (480-770-6023 or james.beckman@leau.org) and L'Eau LLC will test a Dewvaporation Desalination 10,000 GPD Pilot-Plant (total 2 year project $540,000; Reclamation's contribution $270,000). Dewvaporation technique is related to the humidification/dehumidification desalination technique but does not use water as a major heat source or sink. Rather dewvaporation uses air as a carrier-gas to evaporate water from saline feeds and dew forms pure condensate at constant atmospheric pressure in a single heat transferring tower. This project is a follow-on of previously funded research work. A 10,000 GPD dewvaporation pilot-plant will be installed and operated at the 23rd Avenue Wastewater Treatment Plant in Phoenix, AZ. RO effluent will be the feedwater for the dewvaporation unit. The 5,000 ppm TDS RO effluent will be concentrated to more than 200,000 ppm TDS, thereby reducing the brine stream volume to 2% of the RO effluent (98% recovery). The dewvaporation operating cost is $3.50/1,000 gal using natural gas as a heat source (compared to $12/1,000 gal for vapor compression evaporators). In this pilot-study, concentrate volume will be even further reduced resulting in wet salt solids being generated for disposal, at the same dewvaporation cost (compared to $30/1,000 gal for industrial crystallizers).

Steve Weitzel (609-683-0215 or weitzel@novaflux.com) and Novaflux Technologies will conduct Pilot-Scale Testing of Membrane Desalination System Using Novel Two-Phase Cleaning Technology (total 2 year project $563,639; Reclamation's contribution $268,635). The primary objective is to design, construct, test, and validate an integrated membrane-based water purification pilot-plant incorporating Novaflux's patented two-phase membrane cleaning and de-scaling technology to produce drinking water quality from otherwise impaired water sources. The proposed pilot-plant is capable of producing useable purified water, of at least drinking water quality, from brackish or other impaired sources and from industrial wastewater with high TDS (>5,000 ppm) and high organic content. The inclusion of this novel membrane cleaning technology is expected to permit the successful use of an RO separation stage with minimal pretreatment costs for use in applications that are otherwise impractical with current treatment technologies.

Tom Seacord (208-376-2288 or tseacord@carollo.com) and Carollo Engineers will investigate Reducing the Costs of Impaired Water Desalination While Providing Water Resources Management: An Evaluation of Horizontal Collector Wells for Acquiring Surface Water with Subsequent NF/RO Treatment (total 2 year project $1,000,890; Reclamation's contribution $270,000). Drinking water demands have begun to outpace the supplies of higher quality water sources. In addition, many water suppliers are required by law to manage water resources and the amount of water taken from various sources. This project will investigate the long-term ability of river bank filtration to provide cost-effective stand-alone pretreatment for membrane desalting. In addition, this research will determine the ability of horizontal collector wells to acquire low quality surface water through bank filtration as a means of managing surface water acquisition without impacting groundwater rights. The need for this research is highlighted by the lack of data currently available on bank filtration as a pretreatment for NF/RO.


CONTACT US

Water from Water is published by Reclamation's Water Treatment Engineering and Research Group - Susan Martella, Editor. For more information about the DWPR program, contact Kevin Price at: Bureau of Reclamation, 86-69000, PO Box 25007, Denver CO 80225; phone (303) 445-2260; or e-mail a message to MPrice@usbr.gov.