Water Use and Reuse Stream Projects

Water Quality Changes during Aquifer Storage and Recovery - AWWARF Project 2974

Introduction

This is a sequel project to AWWARF project 2618 on Water Quality Improvements During ASR (final report published 2005) which quantified only beneficial effects on water quality of storage in aquifers. In completing that work several gaps were identified that warranted further work. These are :

• Development of a conceptual model of pathogen attenuation, accounting for indigenous microorganisms within the aquifer and environmental conditions affecting their activity
• Re-evaluation of attenuation of five selected endocrine disruptors, but this time in the presence of substrate which would allow co-metabolism to be an pathway for attenuation
• Quantification of DBP formation when chlorinated water is injected into aquifers

A major part of this new project is also to understand processes that result in mobilization of metals that may occur as a result of biogeochemical reactions during ASR. Changes in redox state, when aerobic waters are injected into anaerobic environments can lead to oxidation or acid-base dissolution of aquifer minerals, such as pyrite, arsenopyrite, calcite and dolomite as well as inducing cation exchange reactions. Both of these have potential to mobilize metals including arsenic, iron, manganese, calcium and magnesium, and to produce accompanying ions such as sulfate and bicarbonate. Of these reactions, the most serious from a public and environmental health perspective is mobilization of arsenic.

Objectives/Scope

To identify the following processes that occur during ASR and at selected sites where data are available, to quantify those processes and evaluate simple models:

• Metal mobilisation
• Prediction of microbial pathogen inactivation
• Endocrine disruptor attenuation in aquifers by co-metabolism
• DBP formation potential in aquifers

Activities

• Literature reviews and surveys of partners
• Construct a ‘decision tree’ to predict the potential for occurrence of metal mobilisation
• Explore kinetics of reactions at selected sites
• Construct a ‘decision tree’ on issues likely to be present at prospective ASR sites based on categories of aquifer type, native groundwater quality and injectant quality Technical workshop
• Conduct laboratory-based experiments to fill information gaps essential for development of a conceptual model of pathogen attenuation
• Test the predictive ability of the model at two field sites
• Undertake laboratory experiments of degradation of five endocrine disrupting chemicals in the presence of co-metabolite under aerobic and anaerobic conditions
• Evaluate a simple model of DBP growth in aquifers at selected field sites
• Write a final report and journal papers to cover all of the above

Key CSIRO Staff

Peter Dillon, Simon Toze, Elise Bekele, Jatinder Sidhu, Joanne Vanderzalm, Karen Barry

Partners

• WA Water Corporation
• Thames Water Utilities
• Memphis Light, Gas and Water Division
• Bolivar ASR Research Project Partners with CSIRO
• SA Dept of Water Land and Biodiversity Conservation
• United Water International Pty Ltd
• SA Water Corporation
• SA Dept of Administrative and Information Services

Timeline

Jan 05 - Dec 07

Links

• American Water Works Association Research Foundation

Pathogen attenuation may be measured under in-situ conditions as well as in laboratory conditions