USGS

Virus Fate and Transport During Recharge Using Recycled Water at a Research Field Site in the Montebello Forebay, Los Angeles County, California, 1997-2000

By Robert Anders, William A. Yanko, Roy A. Schroeder, and James L. Jackson

 

U.S. GEOLOGICAL SURVEY

Scientific Investigations Report 2004-5161

Sacramento, California 2004


In cooperation with the
Water Replenishment District of Southern California and the
County Sanitations Districts of Los Angeles County



Complete accessible text of report (3.15 MB PDF)
Complete accessible text of report cover (385 KB PDF)

To view PDF documents, you must have the Adobe Acrobat Reader (free from Adobe Systems) installed on your computer.
(download free copy of Acrobat Reader).

Abstract

     Total and fecal coliform bacteria distributions in subsurface water samples collected at a research field site in Los Angeles County were found to increase from nondetectable levels immediately before artificial recharge using tertiary-treated municipal wastewater (recycled water). This rapid increase indicates that bacteria can move through the soil with the percolating recycled water over intervals of a few days and vertical and horizontal distances of about 3 meters. This conclusion formed the basis for three field-scale experiments using bacterial viruses (bacteriophage) MS2 and PRD1 as surrogates for human enteric viruses and bromide as a conservative tracer to determine the fate and transport of viruses in recycled water during subsurface transport under actual recharge conditions. The research field site consists of a test basin constructed adjacent to a large recharge facility (spreading grounds) located in the Montebello Forebay of Los Angeles County, California. The soil beneath the test basin is predominantly medium to coarse, moderately sorted, grayish-brown sand.

    The three tracer experiments were conducted during August 1997, August-September 1998, and August 2000. For each experiment, prepared solutions of bacteriophage and bromide were sprayed on the surface of the water in the test basin and injected, using peristaltic pumps, directly into the feed pipe delivering the recycled water to the test basin. Extensive data were obtained for water samples collected from the test basin itself and from depths of 0.3, 0.6, 1.0, 1.5, 3.0, and 7.6 meters below the bottom of the test basin.

    The rate of bacteriophage inactivation in the recycled water, independent of any processes occurring in the subsurface, was determined from measurements on water samples from the test basin. Regression analysis of the ratios of bacteriophage to bromide was used to determine the attenuation rates for MS2 and PRD1, defined as the logarithmic reduction in the ratio during each experiment. Although the inactivation rates increased during the third tracer experiment, they were nearly two orders of magnitude less than the attenuation rates. Therefore, adsorption, not inactivation, is the predominant removal mechanism for viruses during artificial recharge.

    Using the colloid-filtration model, the collision efficiency was determined for both bacteriophage during the second and third field-scale tracer experiments. The collision efficiency confirms that more favorable attachment conditions existed for PRD1, especially during the third tracer experiment. The different collision efficiencies between the second and third tracer experiments possibly were due to changing hydraulic conditions at the research field site during each experiment. The field data suggest that an optimal management scenario might exist to maximize the amount of recycled water that can be applied to the spreading grounds while still maintaining favorable attachment conditions for virus removal and thereby ensuring protection of the ground-water supply.

Contents

 

Abstract

Introduction

Artificial Recharge Using Wastewater

Background

Prior Recharge Experiments

Purpose and Scope

Acknowledgments

Description of Study Area

Research Field Site

Site Characterization

Microbiological Changes During Recharge

Methods and Materials

Field Preparation

Bromide Analysis

Bacteriophage Assays

Model Development

Virus Fate and Transport During Recharge

Water Quality

Results from Tracer Experiments

First Tracer Experiment, August 1997

Second Tracer Experiment, August-September 1998

Third Tracer Experiment, August 2000

Inactivation Rates

Attenuation Rates

Collision Efficiency

Summary and Conclusions

References Cites

Appendixes


Document Accessibility: Adobe Systems Incorporated has information about PDFs and the visually impaired. This information provides tools to help make PDF files accessible. These tools convert Adobe PDF documents into HTML or ASCII text, which then can be read by a number of common screen-reading programs that synthesize text as audible speech. In addition, an accessible version of Acrobat Reader 5.0 for Windows (English only), which contains support for screen readers, is available. These tools and the accessible reader may be obtained free from Adobe at Adobe Access.

 



Water Resources of California



U.S. Department of the Interior, U.S. Geological Survey
Persistent URL:
Page Contact Information: Contact USGS
Last modified: Thursday, December 01 2016, 08:06:41 PM
FirstGov button  Take Pride in America button