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The Water Treatment Technology Program Newsletter - No. 5 - Summer 1996

PRINCIPAL OBJECTIVE

The principal objective of Reclamation's Water Treatment Technology Program (WTTP) is to develop lower cost alternatives for desalting and water treatment processes through research. This objective is addressed by using a combination of in-house applied research and demonstration; partnerships with the private sector and academia for basic and applied research projects; and piloting research projects with the private sector, academia, municipalities, and communities. Following are updates of projects within the various program tasks. For more information about the WTTP, contact Kevin Price at 303-445-2260.

TASK 2 - SMALL COMMUNITY WATER TREATMENT SYSTEMS

Reclamation has been working with small and Native American communities over the past several years to assist them in addressing their water quality problems. Many of these communities, and others around the world, rely on drinking water supplies containing high levels of dissolved salts and/or other contaminants that may present health risks. Recent estimates identify over 120 million people in the US alone which are utilizing drinking water which does not meet the Safe Drinking Water Act specifications. Most of these communities do not have the revenues to obtain the professional services of water treatment consultants for assistance in solving their water quality problems. Nor is there sufficient federal funds to assist these communities, even though simple, low-cost methods are often sufficient to bring the community within drinking water standard compliance. To address these water quality and funding issues, the WTTP is compiling a "Water Treatment Primer for Communities-In-Need" (Primer) which will include information on: the best available technologies for removal of specific contaminants; the health risks associated with these contaminants; and the required equipment and costs associated with the needed water treatment. The Primer information will enable the community-in-need to become proactive in solving their water quality problems, and move towards improving their drinking water quality. The Primer will be composed of removable "Fact Sheets" which will lead the community representative through treatment options relating to their community's specific contaminants. The Primer will be organized into five subject areas: contaminant data, contaminant removal techniques, listing of related WTTP publications, water treatment plant construction costs, and water treatment plant operation and maintenance data. Seventeen contaminants will be included in the Primer, including: lead, copper, iron, manganese, nitrates, fluoride, total dissolved solids (TDS), alkalinity, arsenic, volatile and non-volatile organics, radioactivity, turbidity, zinc, cadmium, mercury, and selenium. The American Water Works Association strongly supports this Primer technology transfer project, and will provide the Fact Sheets as a service to their members, as needed. The Primer will be marketed to communities-in-need, the private sector, municipal and county water districts, and academia, and will be made available through the Internet.

TASK 3 - MEMBRANE PROCESS DEVELOPMENT

Reclamation published the initial "Guide to Membranes for Municipal Water Treatment" (Guide) in 1993. This Guide provided then-current documentation on membranes utilized in municipal water treatment, including a complete listing of all available membrane products on the market and their performance data. This Guide is presently used throughout the world. Recently, however, there have been great strides in the development and availability of low-pressure, high rejection membranes; development of microfiltration membranes; and use of membrane applications for municipal and industrial wastewater. As a result of this tremendous growth and prosperity in the water treatment membrane industry, the initial Guide is outdated. To address these industry advancements, the WTTP is preparing an expanded and updated guide entitled, "Guide to Membranes for Water Purification." Like the initial Guide, the new Guide will be used by water treatment engineers, technicians, and consultants to assist them as they design, retrofit, modify, and expand water treatment facilities. In addition to including the newly developed membrane process applications, the updated Guide will provide a much-needed overview of membrane cleaning philosophy, which is used extensively but not well understood. The new Guide will also provide information on how to correctly choose the appropriate membrane type (reverse osmosis (RO), ultrafiltration, nanofiltration, and microfiltration) for the specific application, including municipal drinking water and industrial and municipal wastewater applications. The new Guide will include a current listing of all available membrane products on the market, and detailed performance data regarding each manufacturer's products. The new Guide will be marketed to water treatment professionals in the private sector or employed by municipal and county water districts, and academia, and will be made available through the Internet.

TASK 4 - WELLHEAD TREATMENT

A cost-shared Eastern Municipal Water District RO/saline vegetated wetlands pilot study has been completed and the results documented in a draft final report. The purpose of the study was two-fold: first, to demonstrate the performance of low-pressure RO for desalting brackish San Jacinto Basin groundwater for municipal and industrial applications; and second, to investigate the use of RO reject (concentrated waste stream) for the support of constructed saline wetlands. Two separate membrane elements were tested in a 2-stage, 6 gal/min RO pilot plant: Filmtec BW30-2540s for 1680 hours, and Desal SG2540s for 1000 hours. Permeate recovery was held at 75 percent for both tests. Some performance degradation occurred during the first test from biofouling. Ultraviolet (UV) disinfection alone proved ineffective and had to be augmented with periodic element flushings using a 1 percent solution of the biocide MinncareTM together with storage in a dilute sodium bisulfide solutions during periods of extended shutdown. Otherwise, the RO unit functioned well producing average product water TDSs of 14 and 21 mg/L, respectively, for the two test phases, which greatly exceeded the US Environmental Protection Agency's salinity standards for drinking water. Four salt-tolerant plant species, which are attractive to wildlife, were evaluated in the saline wetlands: alkali bulrush (Schoenoplectus [Scirpus] robustus), creeping spikerush (Eleocharis palustris), marsh smartweed (Polygonum muhlenbergii), and Pennsylvania smartweed (Polygonum pensylvanicum). Two of the four survived. Alkali bulrush quickly became the dominant species confining the creeping spikerush to cell edges. Cattail (Typha spp.) infested both cells and by the third growing season, it became the dominant species in the north cell (fresh water wetland) and the second most abundant, behind alkali bulrush, in the south cell (saline wetland). There were some trace metals detected that warrant concern (but not a serious threat) for the health and well-being of visiting wildlife and should continue to be monitored. The available data, however, are very limited so no definite conclusions can be drawn.

Visit the WTTP website at: http://www.usbr.gov/pmts/water/


CONTACT US

Water from Water is published by Reclamation's Water Treatment Engineering and Research Group - Susan Martella, Editor. For more information about the DesalR&D 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.