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Basic Information
Active lime treatment of acid mine drainage.
Managers of Superfund and hazardous waste containment, cleanup, and removal ask Engineering Technical Support Center (ETSC) researchers to address problems from a scientific, methodological approach.
Table of Contents
What innovative treatment technologies do you evaluate? What is the sustainability of the treatment systems?What do your scientists do?
What innovative treatment technologies do you evaluate?
ETSC uses laboratory, bench-scale, and field-scale treatability tests to evaluate remedial options and alternatives. The cleanup methods researched are either in situ, meaning that the substances are treated where they are, or ex situ, meaning that hazardous substances are collected for treatment or disposal elsewhere. ETSC staff evaluates physical/chemical, biological, and thermal treatment technologies.What do you mean by cleanup?
Cleanup means safely removing, disposing of, storing of, or in situ treatment of hazardous substances— ensuring that those substances do not have a negative environmental impact.Scientists and engineers research the effectiveness of the following methods for cleanup prior to land redevelopment. The following are not endorsements of individual technologies, but general explanations of the basic principles.
What is the sustainability of the treatment systems?
A treatment system's design dictates its sustainability. The three basic class distinctions, active, semi-passive, and passive, describe the level of operative maintenance required for contaminant removal, degeneration, or destruction.
ETSC evaluated a passive biochemical system.
Active Treatment Systems
Active systems require continual input, upkeep, monitoring, or all three. For instance, a treatment that continuously adds chemical compounds to an area will require monitoring to ensure safety and efficacy. They may require continual mechanical operation, chemical intervention, and/or extended periods of monitoring and evaluation.Semi-Passive Treatment Systems
Semi-passive systems combine some elements of both active and passive systems. Cleaning up may start with critical chemical or mechanical intervention, while the maintenance burden is reduced gradually over time.Passive Treatment Systems
Passive systems require minimal monitoring, though they may involve hefty setup or installation costs. Observation may be necessary if chemicals are to be added at various stages of treatment, even if at infrequent intervals. Conceptually, all passive systems are ultimately self-sustaining because they are based on natural processes.What do your scientists do?
How ETSC assists:
- Calibrates and renovates treatment systems
- Oversees field and lab studies to select the best option for cleanup, known as remedial design or action ¹
- Scrutinizes work plans and reports
- Facilitates technical discussions for:
- consent agreements
- public meetings
- public documents explaining cleanup options known as a Record of Decision²
² Definition of a Record of Decision
Focus on Mine-Influenced Water
ETSC's experience is in the treatment of drainage from metal mining operations. This drainage may or may not be acidic, and treatments vary accordingly.Mining operations expose pyrite (iron disulfide FeS2) to air and water, which can oxidize and dissolve it into ferrous iron and sulfuric acid. The sulfuric acid may then dissolve minerals in neighboring rocks, which can release metals and sulfates into the water, carrying them to places they may not naturally belong. ETSC researches the ability of passive biological processes (e.g. sulfate-reduction by sulfate-reducing bacteria) to accelerate favorable reactions in contaminated water, which remove metals via precipitation as insoluble solids; with sulfate-reduction, metal sulfides are the solids formed. ETSC staff may recommend lime or other hydroxides to alter the water's pH and alkalinity, a biochemical reactor, or another treatment system specific to the mine-influenced water.
ETSC staff evaluated several treatment systems that reduce aluminum, arsenic, copper, iron and nickel in acid mine drainage at the Leviathan Mine from 2002-2003. Active and Semi-Passive Lime Treatment of Acid Mine Drainage at Leviathan Mine, California (PDF) (106 pp, 4.2M, EPA/540/R-05/015, Abstract) includes capital, operation and maintenance costs.
Publications from research at Leviathan Mine