[CPEO-MEF] PERCHLORATE: ITRC "Tech-Reg"

[Lenny Siegel <lennysiegel@gmail.com>]

Remediation Technologies for Perchlorate Contamination in Water and Soil

Prepared by
The Interstate Technology & Regulatory Council Perchlorate Team
March 2008


[To download or order the entire document, go to
http://www.itrcweb.org/guidancedocument.asp?TID=32]



EXECUTIVE SUMMARY

Perchlorate, an anion, consists of one chlorine atom bonded to four 
oxygen atoms (ClO4-) and is both naturally occurring and manmade. Highly 
soluble and mobile in water, perchlorate is generally very stable in the 
dissolved state. Most of the attention focused on perchlorate has 
concerned its presence in groundwater and surface water. However, 
perchlorate can also be found in soil and vegetation and has entered the 
human and environmental food chains. Perchlorate occurrence in drinking 
water and food supplies is a human health concern because it can 
interfere with iodide uptake by the thyroid gland and result in 
decreased thyroid hormone production.

Past management practices were not concerned with the release of 
perchlorate to the environment because it was not recognized or regarded 
as a contaminant of concern. Widespread perchlorate presence in the 
United States was observed after the spring of 1997 when an analytical 
method was developed with a quantitation level of 4 parts per billion. 
Subsequent advances in analytical chemistry have proven perchlorate to 
be more widespread in the environment than previously thought. Chapter 1 
provides an overview of perchlorate issues.

The success or failure of a treatment technology often depends on having 
a complete understanding of the nature and extent of the release. Site 
investigators start with a conceptual site model, which is gradually 
refined through sampling and other investigative techniques. Chapter 2 
discusses this and other site evaluation issues.

A variety of remediation technologies are currently commercially 
available and are being used for perchlorate remediation. Most of these 
remediation technologies fall into two broad categories: physical and 
biological treatment processes. Chapter 3 discusses considerations for 
the selection of a particular remedy.

Perchlorate remediation system installation and operation could involve 
various local, state, and federal government departments. These entities 
might require compliance to various rules or permits that directly or 
indirectly involve the operation of planned remedial systems. 
Information regarding compliance with local, state, federal or tribal 
regulations to install and operate a perchlorate treatment system should 
be researched and obtained at the outset of a project to prevent 
unforeseen delays to treatment projects. Chapter 4 discusses regulatory 
considerations.

Physical treatment processes remove perchlorate from impacted media but 
do not alter its chemical composition. Considerable progress has been 
made in developing innovative physical processes for removing 
perchlorate from drinking water, groundwater, and surface water. Some 
technologies are proven and commercially available, while others are 
still in the research and development phase. Chapter 5 discusses 
physical processes for treatment of perchlorate- impacted water, 
including ion exchange, granular activated carbon, reverse osmosis, 
nanofiltration/ultrafiltration, electrodialysis, capacitive 
deionization, and electrolysis.

Ion exchange, the most proven and widely accepted physical process 
technology for perchlorate treatment, is a process by which ions of a 
given species are displaced from an insoluble exchange material by ions 
of a different species in solution. Perchlorate selective ion exchange 
targets perchlorate using conventional ion exchange resin beds with 
specially designed resins that preferentially remove perchlorate anions.

Biological degradation of perchlorate involves reducing bacteria, which 
are widespread in the environment. Perchlorate-reducing bacteria have 
the ability to grow in either the presence or absence of air, provided 
proper nutrients are available in the environment. Both in situ and ex 
situ biological treatment systems have been applied at full scale to 
treat perchlorate. Chapters 6 and 7, respectively, discuss in situ and 
ex situ bioremediation technologies for perchlorate in water.

Soil impacted with perchlorate can be treated using in situ 
bioremediation, ex situ bioremediation, and ex situ thermal treatment. 
Shallow soil can generally be treated in place or excavated and treated 
on site by bioremediation methods such as composting or intrinsic 
bioremediation. Excavated soils may also be treated using thermal 
desorption. Chapter 8 discusses remediation technologies for soil. 
Phytoremediation shows promise to treat both vadose zone soils and 
groundwater. Chapter 9 discusses phytoremediation and constructed 
wetlands. Cost-effective treatment of deeper occurrences represents an 
important challenge.

Most environmental sites affect local communities at some level. The 
federal government, states, and sovereign tribal nations regulate and/or 
mandate the participation of stakeholders in the investigation and 
remediation process. Remediation concerns common to all stakeholders 
typically relate to health issues, economic or monetary issues, 
inconvenience, and natural resource issues. Chapter 10 discusses 
stakeholder issues such as these.

Chapter 11 provides a comprehensive listing of references, and 
appendices are included for case studies, team contacts, and acronyms. 
Case studies include the Aerojet site in Rancho Cordova, California; the 
American Pacific Corporation site near Henderson, Nevada; and the Naval 
Weapons Industrial Reserve Plant in McGregor, Texas. These case studies 
document the remediation of perchlorate in soil and groundwater using a 
variety of technologies.



--


Lenny Siegel
Executive Director, Center for Public Environmental Oversight
a project of the Pacific Studies Center
278-A Hope St., Mountain View, CA 94041
Voice: 650/961-8918 or 650/969-1545
Fax: 650/961-8918
<lsiegel@cpeo.org>
http://www.cpeo.org


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