John.taylor @libertyhydro.com Page 1 304.941.3020 Technical Explanation for the

Selenium Remover ZVI Blue TM system

The Problem : Coal

- burning power plants face an issue with tightening legislation concerning the amount of selenium that can be released from Flue Gas Desulfurization (FGD) waste waters. The industry has been investigating many other technologies with underwhelming results. The industry
needs a solution that is effective, economical and reliable.

The Solution: Liberty Hydro, Inc. has developed a solution for the removal of seleni um from

waste water. The Liberty Hydro ZVI Blue TM system is a patent ed technology in which finely

- divided

zero

- valent iron (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 wi th the ZVI. The selenium in solution is reduced by the ZVI to elemental selenium which is permanently absorbed by the foam media.

Background: The form of selenium usually found in natural water systems is either selenate ion (SeO 4 2

- ) or selen ite ion (SeO 3 2

- ) but other compounds can be present, such as selenide ion (Se 2

- ), selenocyanate (SeCN

- ) or organic selenium compounds. Selenium in surface water is a particular problem because it is bio

- accumulated by plants and animals. Selenium is an essential nutrient for
humans at low concentrations but is toxic to all mammals at higher levels.John.taylor @libertyhydro.com Page 2 304.941.3020 Technical Explanation for the

Selenium Remover ZVI Blue TM system

The United States Environmental Protection Agency (US EPA) has established a limit of 5 parts

- per

billion (ppb) of selenium in natural water systems, which is the limit normally associated with the discharge from coal mines. For coal

- fired power plants, the proposed technol ogy

- based limit is 10 ppb average, with an instantaneous maximum of 16 ppb.

In recent years, elemental iron or zero

- valent iron (ZVI) has been used to treat ground water and surface water systems to remove a number of pollutants (e.g., arsenic, selenium, chromium (VI), chlorinated hydrocarbons, etc.). The methods for bringing the ZVI in contact with the contaminant have varied from 1) direct addition of the metal to the water; to 2) the construction of underground permeable reactive barriers containing iron particles.

In all applications, ZVI acts as a strong reducing agent and, when it is in the finely

- divided form, is particularly effective in reacting with low levels of contaminants. ZVI will effectively reduce all water

soluble forms of selenium an d immobilize it as elemental selenium or selenide on the surface of the

iron. Previously, one of the challenges of reacting ZVI wit h low ppb levels of selenium was achieving an adequate contact time betw een the ZVI and the selenium while maintain a reas onable water flow

rate. Liberty Hydro has achieved this balance with its patent ed s ystem in which finely

- divided ZVI is
attach ed to an open

- pore polymer foam.

The ZVI Blue TM system can be operated by gravity feed of the influent water or by a pump if pow er is
available. As a minimum, i t is recommended that the influent water be filtered prior to the first ZVI
reactor vessel and this is usually accomplished with a back

- flushable sand filter but more recent pilot testing ha ve shown that primary treatment of the infl uent water will also be required in many cases (i.e., lime softening, coagulation, clarifying, etc.)

.
In the early stages of the Liberty Hydro technology, when applied at coal mines, the system was comprised of three steel totes in series (see picture b elow) with the water flow configured downwards in each tote. The pH of the water entering each tote is controlled by a carbon dioxide purge which adjusts the pH of the water to a target value of 6.2. Since soluble iron (II) is generated during the ZVI

re duction step, it is important to have a means of removing the iron from the stream exiting the ZVI system, especially if the outfall is environmentally sensitive to iron (e.g. entering a trout stream). Traditional techniques can be used to remove the iron , such as settling pond and/or aeration.John.taylor @libertyhydro.com Page 3 304.941.3020 Technical Explanation for the

Selenium Remover ZVI Blue TM system

Schematic of Early Pilot System :

Data from Coal Mine Installation:

Raw Water

Sand Filter

Treated Water ZVI Tote 1 ZVI Tote 2 ZVI Tote 3 Iron Treatment Carbon Dioxide CylindersJohn.taylor @libertyhydro.com Page 4 304.941.3020 Technical Explanation for the

Selenium Remover ZVI Blue TM system

The technology has now advanced to the point where it has been installed at various coal

- fired power plants, with successful results.

The configuration used for pilot testing involved a series of drum s filled with ZVI BlueTM media. The flow enters the drum through a pipe in the center of the drum so that the flow is upward through each drum, from the bottom of the pipe to the connections in the lid of the drum. It is, a gain, i mportant to
have a preceding filtration system because the advance d ZVI BlueTM media, designed for reducing metals and metalloids, is also

, unfortunately

, effective at removing mud, silt, algae and other metals that would otherwise properly be managed of by an effective primary treatment system ( power plants usually call primary treatment a physical chemical system or “phys chem” for short).

The pH adjustment of the influent water at the coal

- fired power plant pilots was accomplished by feed hydrochloric aci d (target pH 6.2).

The drum system installed at a power plant is show n in the following photograph:John.taylor @libertyhydro.com Page 5 304.941.3020 Technical Explanation for the

Selenium Remover ZVI Blue TM system

T ypical schematic configuration s are shown in the following diagrams (the lower right schematic shows the drum system):

T reatment results for selenium removal are shown below:John.taylor @libertyhydro.com Page 6 304.941.3020 Technical Explanation for the

Selenium Remover ZVI Blue TM system

Larger pilot units can be installed and Liberty Hydro has designed and prepared preliminary cost

est imates for full scale system s with a flow of 350 gallons per minute. The initial cost estimate was under $20 Million and further development work is likely to reduce that cost.

Now that Liberty Hydro’s ZVI BlueTM technology has been shown to work at power plants, the logical next step is to install larger units and enter joint development agreemen t s with major electric utilities to refine the technology for their particular use. This would be a much better arrangement than watching the power plants continue to test other technologies that have not worked in initial testing.

Liberty Hydro offers a cost

- effective technology that has been shown to work under the right conditions and the goal is to replicate those conditions on larger units so that the most promising technology is refined for final installation.

Chemistry:

At ppb levels of selenium in the influent water, the primary route of selenium removal is by direct reduction by the ZVI or by iron (II) hydroxide. Other mechanisms likely involved adsorption

, especially in iron oxide/hydroxides or green rust phases that de velop in the media.John.taylor @libertyhydro.com Page 7 304.941.3020 Technical Explanation for the

Selenium Remover ZVI Blue TM system

The reduction reaction is pH dependent with the reaction rate increasing at lower pH. The broad target pH range for the ZVI Blue TM system is 5.5 to 6.5 since low influent pH (pH<4)

- while increasing
the rate

- will dissolve too much iron. Based on the reduction reaction, t he pH increases through the bed and will eventually reach basic conditions (pH>8); this is an undesirable condition since it likely
mimic s lime softening and will tend to precipitate/coagulate an y remaining dissolved solids on the
media. A desirable design feature is pH control at the inlet to each bed.

It is quite well established in the literature that the kinetics of selenate reduction by ZVI is pseudo

- first
order

. R ecent data collected during pilot testing is consistent with pseudo

- first order kinetics (see below).

The first data point in the graph represents the influent concentration to the pilot system (5 drum sets in series each containing about 80 gallons of media each). Subse quent data points represent increments of 80 gallons of media through the system. At a constant flow rate of 3 gallons per minute (GPM), the x

- axis is equivalent to a time axis. The last data point at 400 gallons bed volume is 8 ppb as selenium

.

Liberty Hydro welcomes additional questions about its water treatment technology.