EPA1600/R-99/i 07 February 2000 Introduction to Phytoremediation National Risk Management Research Laboratory Office of Research and Development U.S. Environmental Protection Agency Cincinnati, Ohio 45266 Notice The EPA through its ORD produced this document. It has been subjected to the Agency’s peer and administrative review and has been approved for publication as an EPA document. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. Foreword The US. Environmental Protection Agency is charged by Congress with protecting the Nation’s land, air, and water resources. Under a mandate of national environmental laws, the Agency strives to formulate and implement actions leading to a compatible balance between human activities and the ability of natural systems to support and nurture life. To meet this mandate, EPA’s research program is providing data and technical support for solving environmental prob- lems today and building a science knowledge base necessary to manage our ecological re- sources wisely, understand how pollutants affect our health, and prevent or reduce environmen- tal risks in the future. The National Risk Management Research Laboratory is the Agency’s center for investigation of technicological and management approaches for reducing risks from threats to human health and the environment. The focus of the Laboratory’s research program is on methods for the prevention and control of pollution to air, land, water and subsurface resources: protection of water quality in public water systems; remediation of contaminated sites and ground water; and prevention and control of indoor air pollution. The goal of this research effort is to catalyze development and implementation of innovative, cost-effective environmental technologies; de- velop scientific and engineering information needed by EPA to support regulatory and policy decisions; and provide technical support and information transfer to ensure effective implemen- tation of environmental regulations and strategies. This publication has been produced as part of the Laboratory’s strategic long-term research plan. It is published and made available by EPA’s Office of Research and Development to assist the user community and to link researchers with their clients. E. Timothy Oppelt, Director National Risk Management Research Laboratory Abstract Phytoremediation is the name given to a set of technologies that use different plants as a containment, destruction, or an extraction technique. Phytoremediation as a remediation tech- nology that has been receiving attention lately as the results from field trials indicate a cost savings compared to conventional treatments. The U.S. EPA has a dual role in which it seeks to protect human health and the environment associated with hazardous waste sites, while encouraging development of innovative technolo- gies that might more efficiently clean up these sites. This Introduction is intended to provide a tool for site regulators, owners, neighbors, and man- agers to evaluate the applicability of phytoremediation to a site. This document defines terms and provides a framework to understand phytoremediation applications. It is a compilation of research and remediation work that has been done to date.The format is intended to be acces- sible to EPA RPMs, state regulators, and others who need to choose between alternate tech- nologies, as well for site owners, consultants, contractors, and students who are interested in basic information. It is not a design manual, and is not intended to provide enough information to choose, engineer, and install a phytoremediation application. This work may also be used to help guide research, development, and regulation. Areas of needed research have been identified. By compiling the published and unpublished work, re- search repetition can be avoided, and areas of opportunity that need attention should be clear. Table of Contents Foreword . ...........iii Acknowledgements __,___.__.._..__.__................................................................................................ xi Chapter 1 Introduction ............................................................................................................ 1 1.1 Objectives ....................................................................................................... 1 ........................................................................................................ 1 ........................................................................................ 1 Overview of Phytoremediation ............................................................................... 3 2.1 Background ..................................................................................................... 3 2.2 Technical Considerations ................................................................................. 7 2.3 Economic Considerations ................................................................................ 7 2.4 Regulatory Considerations.. ............................................................................. 9 2.5 Ecosystem Restoration ................................................................................. IO 2.6 Current Research ........................................................................................... 12 Chapter 3 Evaluation of Phytoremediation Technologies ...................................................... 14 3.1 Phytoextraction .............................................................................................. 14 3.2 Rhizofiltration ................................................................................................. 18 3.3 Phytostabilization .......................................................................................... 21 3.4 Rhizodegradation ........................................................................................... 23 3.5 Phytodegradation ........................................................................................... 28 3.6 Phytovolatilization ......................................................................................... 31 3.7 Hydraulic Control ........................................................................................... 34 3.8 Vegetative Cover Systems ............................................................................ 35 3.9 Riparian Corridors/Buffer Strips ..................................................................... 39 Chapter4 Phytoremediation System Selection and Design Considerations ......................... 41 4.1 Contaminated Media Considerations ............................................................. 42 4.2 Contaminant Considerations .......................................................................... 43 4.3 Plant Considerations ..................................................................................... 44 4.4 Site Considerations ....................................................................................... 48 4.5 Treatment Trains ............................................................................................ 51 4.6 Additional Information Sources ...................................................................... 51 Chapter 5 Remedial Objectives, Treatability, and Evaluation ................................................ 52 5.1 Remedial Objectives ...................................................................................... 52 5.2 Treatability Studies ........................................................................................ 53 5.3 Monitoring for Performance Evaluation .......................................................... 56 V Contents (continued) Chapter 6 Case Studies ....................................................................................................... 58 6.1 Edgewood Area J-Field Toxic Pits Site Aberdeen Proving Grounds Edgewood, Maryland ..................................................................................... 58 6.2 Carswell Site Fort Worth, Texas ..................................................................... 60 6.3 Edward Sears Properties Site New Gretna, New Jersey ............................... 64 6.4 Bioengineering Management: U.S. Nuclear Regulatory Commission Beltsville, MD ................................................................................................ 67 6.5 Lakeside Reclamation Landfill Beaverton, Oregon ...................................... 68 6.6 Alternative Landfill Cover Demonstration Sandia National Laboratories Albuquerque, NM ........................................................................................... 70 Appendix A Glossary ............................................................................................................. A-l Appendix B Phytoremediation Database ................................................................................ B-l Appendix C References .......................................................................................................... C-l Appendix D Common and Scientific Names of Referenced Plants.. ....................................... D-l vi Figures Figure 2-l. Mechanisms for phytoremediation. ........................................................................ 4 Figure 2-2. Example root depths. ............................................................................................. 6 Figure 3-l. Phytoextraction. ..................................................................................................