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The cuboid solution for CCR and mine water treatment

Liberty Hydro has developed ZVI Blue™ as a cuboid-shaped porous media to remove selenium, arsenic, mercury, chromium, thallium and other dissolved contaminants from discharge waters.

The media works together as a packed bed reactor in standard pressure tanks to provide water treatment solutions for CCR contact and drainage water, and discharge water from mining operations and industrial applications.

Description

• ZVI Blue™ media is manufactured in a cuboid shape and uses zero valent iron adhered throughout a porous foam substrate.
• The media can be loaded directly into standard reactor vessels and, when exhausted, can be removed by vacuum truck.
• ZVI Blue™ media works as a packed bed reactor allowing water, for a predetermined retention time, to come in direct contact with the zero valent iron incorporated into the media.
• Zero valent iron creates a chemical reaction / electron transfer which reduces oxidized contaminants, like selenate and selenite, absorbing and removing contaminants from the effluent
• ZVI Blue™ media has worked effectively for a duration of 2 years in a mining application
• For other waters, the media is expected to have an active life of 9 months to 1 year, depending on the effectiveness of the pre-treatment system and the concentration of contaminants.
• The exhausted media can be disposed of in a regular (non-hazardous waste) landfill.
• The chemical reaction process creates dissolved iron in the effluent which has further beneficial effects of removing trace contaminants when the iron is oxidized and removed from the water stream.

Applications

• Pilot testing has validated effective removal of selenium at coal ash ponds, FGD purge waters, and mine waters.
• The focused application is for removing contaminants from power plant and industrial discharge water and for re-using mine water for irrigation and agricultural purposes.
• Laboratory and field applications validate the removal of other dissolved metals, including chromium, while research has shown the removal of pathogens suggesting a future application for the pretreatment of contaminated drinking water.
• The water in a coal ash pond can be stratified, with simple rainwater and surface water occupying the top layer of the ponds.  Other technologies are reported to be struggling to treat simple surface waters with levels of 10 to 15 ppb of selenium, causing delays in the dewatering and treatment operation.  Liberty Hydro ZVI Blue™ has been shown to be most effective at treating higher levels of contamination, likely to be encountered at deeper levels of the pond when encountering interstitial and pore water.

Alternative or Supplement to Bio Treatment:

• ZVI Blue™ technology can be used in place of biological treatment or as a supplement when biological treatment is employed in a treatment system.
• Biological treatment can create hidden and harmful effects by converting selenium into hard-to-detect organo compounds that readily bio-accumulate and cause detrimental effects to aquatic life.
  • Source: The Role of Ultra-Trace Selenium Speciation Analyses and Ecological Risk Assessments. Brooks Applied Labs, posted January 12, 2107
• ZVI Blue™ media removes these potentially harmful forms of organo compounds, assuring better water quality in the receiving waters.

Representative Test Results for Selenium removal:

Note:  ppb = μg/L

Full-Scale System Design:

(showing design for mine water application, following pretreatment with chemically enhanced sand filtration)

ZVI Blue™ Product Characteristics:

• Size of individual cuboid media: 1 inch x 1 inch x ½ inch, or smaller
• Weight of media in packed bed: 35 pounds per cubic foot / 5 pounds per gallon volume
• Operating temperatures: effectiveness achieved at broad range of water temperatures
• Longevity will depend on concentration and water quality, but 6 months to 24 months has been achieved
• Retention time can be extrapolated from other field data and can be pre-determined from pilot testing
• Effect on pH: the chemical reaction will raise pH, justifying pH adjustment between reactor vessels.
  • Ideal inlet pH is 5.5 to 6; effluent prior to adjustment will be > 8.
• Media disposal: media is nonhazardous  and can be disposed of in a standard nonhazardous landfill
• Storage: in dry place; wet media / premature disposal can be exothermic, so proper handling  is required
• Side effects: reaction produces dissolved iron, meriting downstream iron removal which beneficially removes other trace contaminants

The information provides a guide to ZVI treatment. It is based on data and extrapolations and believed to be accurate, but does not constitute a guaranty or warranty. Liberty Hydro welcomes the opportunity to work with customers on solutions to their particular water quality. Together we can validate the suitability of the proposed treatment train.

Liberty Hydro, Inc.   1740 Union Carbide Drive, South Charleston, WV  25303

Technical Information

Liberty Hydro Phys Chem Optimization Services

For a number of years, elemental iron or zero valent iron (ZVI) has been used to treat ground water and surface water to remove a number of pollutants (e.g., mercury, arsenic, selenium, chromium (VI), chlorinated hydrocarbons, etc.). The methods for bringing the ZVI in contact with the contaminant have varied from direct addition of the iron to the water to the construction of underground permeable reactive barriers containing iron particles.

More recently, Liberty Hydro, Inc. has developed a unique ZVI delivery system for the removal of heavy metals and selenium from water. The ZVI Blue™ system is a patented process in which finely-divided ZVI is attached to an open-pore polymer foam. The foam media allows easy flow of the water while enabling adequate contact and reaction time with the ZVI.

In all ZVI applications, iron acts as a strong reducing agent and, when it is in the finely-divided form, is particularly effective at reacting with low levels of contaminants. In the case of selenium, the ZVI Blue™ system will effectively reduce all water-soluble forms of selenium and immobilize it as elemental selenium on the surface of the iron. The used ZVI Blue™ media can then be safely sent to the landfill.

Liberty Hydro has also developed customized blends of its reactive media and can install its proprietary technology within a properly-designed treatment train to assure compliance with applicable effluent discharge standards.

Optimization of chemical usage for primary (Phys Chem) treatment

Liberty Hydro’s laboratory is fully equipped to provide FGD treatment optimization.

1. Our technical professionals will evaluate Flue Gas Desulfurization (FGD) purge water to determine the constituents in the water and the effects of various operating condition on the resultant water quality over the course of a year.
2. Our Goal: determine the best “physical chemical” (phys/chem) treatment to remove the bulk of contamination from FGD purge water. The first step requires raising the pH by adding caustic soda or other lime softening solution, which will cause certain dissolved metals to precipitate from solution. This step is followed by adding certain coagulants and polymers, to enhance precipitation. The final steps are clarification and filtration. This is the basic means to remove the bulk of contaminants. Additional treatment, secondary and tertiary, can be added to remove specific targeted contaminants, like selenium, mercury and arsenic.
3. Liberty Hydro will test various pretreatment chemicals (including organosulfides from various suppliers) designed to provide the best solution for each specific type of FGD purge water. We will supply a fully detailed report on each step of the phys/chem process and provide a specific treatment train recommendation, designed to meet the upcoming Effluent Limitation Guidelines.
4. Liberty Hydro will collect FGD purge water in totes and provide off-site evaluation for phys/chem optimization. Testing can be done throughout the year to assess seasonal and operational variations. No need to run a pilot unit on site at this stage.
5. Each generating facility will benefit from a customized analysis of its FGD purge water and the establishment of an optimized phys /chem treatment protocol, so that the phys / chem system can be properly designed and operated prior to testing and installing downstream treatment technologies. This will save the generating facility time and money eliminating the need for costly trial and error evaluations onsite.
6. When a facility is ready to evaluate final compliance, Liberty Hydro can install an intermediate-sized pilot unit using Liberty Hydro’s ZVI Blue™ technology. This technology, when preceded by an optimized phys/chem system, has been proven in field trials at several major power generating facilities for removing selenium, mercury and arsenic.