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Remediation Technologies Screening Matrix, Version 4.0 4.43 Adsorption/Absorption
(Ex Situ GW Remediation Technology)
  Description Synonyms Applicability Limitations Site Information Points of Contact
Data Needs Performance Cost References Vendor Info. Health & Safety
Table of Contents
Technology>>Ground Water, Surface Water, and Leachate

>>3.12 Ex Situ Physical/Chemical Treatment

      >>4.43 Adsorption/Absorption
Introduction>> In liquid adsorption, solutes concentrate at the surface of a sorbent, thereby reducing their concentration in the bulk liquid phase.


Figure 4-43: Typical Adsorption/Absorption System  

Adsorption mechanisms are generally categorized as either physical adsorption, chemisorption, or electrostatic adsorption. Weak molecular forces, such as Van der Waals forces, provide the driving force for physical adsorption, while a chemical reaction forms a chemical bond between the compound and the surface of the solid in chemisorption. Electrostatic adsorption involves the adsorption of ions through Coulombic forces, and is normally referred to as ion exchange, which is addressed separately in the ion exchange modules. In liquids, interactions between the solute and the solvent also play an important role in establishing the degree of adsorption.

The most common adsorbent is granulated activated carbon (GAC) (Technology Profile No. 4.46). Other natural and synthetic adsorbents include: activated alumina, forage sponge, lignin adsorption, sorption clays, and synthetic resins.

Activated Alumina

Activated alumina is a filter media made by treating aluminum ore so that it becomes porous and highly adsorptive. Activated alumina will remove variety of contaminants, including excessive fluoride, arsenic, and selenium. The medium requires periodic cleaning with an appropriate regenerant such as alum or acid in order to remain effective.

Forage Sponge

Forage sponge is an open-celled cellulose sponge incorporating an amine-containing chelating polymer that selectively absorbs dissolved heavy metals. The polymer is intimately bonded to the cellulose so as to minimize physical separation from the supporting matrix. The functional groups in the polymer (i.e. amine and carboxyl groups) provide selective affinity for heavy metals in both cationic and anionic states, preferentially forming complexes with transition-group heavy metals.

Lignin Adsorption/Sorptive Clay

Lignin adsorption/sorptive clays are used to treat aqueous waste streams with organic, inorganic and heavy metals contamination. The waste stream is treated due to the molecular adhesion of the contaminants to an adsorptive surface.

Synthetic Resins

Synthetic resins are more expensive than GAC, but can be designed to achieve higher degrees of selectivity and adsorption capacity for certain compounds than activated carbon. Resins are typically regenerated using acids, bases, or organic solvents, instead of thermal methods, so they are better suited for thermally unstable compounds such as explosives, and are resistant to deactivation due to the adsorption of dissolved solids. Additionally, resins tend to be more resistant to abrasion than activated carbon, increasing their service life.

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Liquid phase adsorption.

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The target contaminants groups for adsorption/absorption processes are most organic contaminants and selected inorganic contaminants from liquid and gas streams. Activated alumina can remove fluoride and heavy metals. The forager sponge is specifically used to remove heavy metals. Lignin adsorption/sorptive clays treat organic, inorganic and heavy metals contamination within aqueous waste streams. Synthetic resins are better suited for thermally unstable compounds such as explosives than GAC, due to the resins' non-thermal regeneration requirements.

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Factors that may limit the applicability and effectiveness of these processes include:
  • Water-soluble compounds and small molecules are not adsorbed well.
  • Costs are high if used as the primary treatment on waste streams with high contaminant concentration levels.
  • Not applicable to sites having high levels of oily substances.
  • Not practical where the content of the absorbable hazardous substance is so high that very frequent replacement of the absorbent unit is necessary.
  • Contaminated media often require treatment/disposal as hazardous wastes, if they can't be regenerated.

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Data Needs:

A detailed discussion of data elements is provided in Subsection 2.2.2 (Data Requirements for Ground Water, Surface Water, and Leachate).

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Performance Data:

Adsorption/absorption processes have a long history of use as treatment for municipal, industrial, and hazardous waste streams. The concepts, theory, and engineering aspects of the technologies are well developed. They are proven technologies with documented performance data.

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The cost to treat heavy metal contaminated ground water over a one year period with the Forager Sponge technology is estimated at $340/1000 gallons, assuming the sponges are not regenerated and are replaced upon saturation; or $238/1000 gallons, assuming the sponges are regenerated twice providing for three useful treatment cycles. Costs for other adsorbent processes are not available.

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Innovative Remediation Technologies:  Field Scale Demonstration Project in North America, 2nd Edition

Abstracts of Remediation Case Studies, Volume 4,  June, 2000, EPA 542-R-00-006

Guide to Documenting and Managing Cost and Performance Information for Remediation Projects - Revised Version, October, 1998, EPA 542-B-98-007

MTBE Treatment Case Studies
presented by the USEPA Office of Underground Storage Tanks.

Battelle Memorial Institute, 1995. "ReOpt V3.1 User Documentation", for DOE under contract DE/AC06/76RLO 1830.

Rainer, N., 1995. "Forager Sponge, Technology Description", Dynaphone, Inc.

Water Quality Association, 1994. "Treating the Water We Drink, When and Where We Drink It.", WaterReview Technical Brief, Vol. 9, No. 4.

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Site Information:

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Points of Contact:

General FRTR Agency Contacts

Technology Specific Web Site:

Government Web Sites

Non Government Web Sites

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Vendor Information:

A list of vendors offering Ex Situ Physical/Chemical Water Treatment is available from  EPA REACH IT which combines information from three established EPA databases, the Vendor Information System for Innovative Treatment Technologies (VISITT), the Vendor Field Analytical and Characterization Technologies System (Vendor FACTS), and the Innovative Treatment Technologies (ITT), to give users access to comprehensive information about treatment and characterization technologies and their applications.

Government Disclaimer

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Health and Safety:

Hazard Analysis

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