In late 2011, Yukon Nevada Gold contacted AdEdge Water Technologies LLC to design, manufacture and start up an arsenic removal system for the Ketza River Mine in Yukon, Canada. The site required arsenic treatment of the discharge water from the mine’s tailings pond. The existing treatment plant was inoperable.
Arsenic levels in the tailings pond are approximately 54 ppb. The Canadian Metal Mining Effluent Regulations (MMER) set the standard at 50 ppb. The AdEdge system, which replaces the existing system, was designed for a flow rate of 250 gal per minute (gpm) with bypass and recirculation built into the system.
Treatment System
The AdEdge treatment system features a skid-mounted GS+ coagulation and filtration package unit enclosed in a WaterPod containerized building sized for a maximum design flow of 250 gpm.
The model AD26-4860CS-4-AVH utilizes AdEdge GS+ and anthracite media in a four-vessel carbon steel configuration in parallel. The arsenic removal system is housed in a 40 foot cargo container equipped with HVAC, pedestrian doors, ventilation vents, windows and lighting.
The WaterPod system sits on a concrete slab base and is pre-designed and pre-piped. The system is equipped with automated control valves and harness, central control panel with programmable logic controller and a color user interface screen.
A continuous feed of sodium hypochlorite is fed prior to the treatment system to optimize the removal of arsenic via the AdEdge ADIN chemical feed system. Ferric chloride is also injected into the raw water prior to the treatment vessels to promote the formation of pin floc and create larger particles that are easier to filter in the media bed.
Each 48-in. diameter treatment vessel contains 27 cu ft of AdEdge GS+ coagulation/filtration media. AdEdge GS+ is a NSF 61 certified black filter media used for the removal of arsenic, iron and manganese. The manganese dioxide coated surface of GS+ acts as a catalyst in the oxidation reduction reaction of iron and manganese.
In addition to the GS+ media, each treatment vessel contains approximately 9 cu ft of anthracite coal that acts as a pre-filter to the GS+ media. Backwashing of the treatment system occurs every day depending on the incoming levels of arsenic and the number of gallons processed.
Performance
The system was started up and commenced in June 2012. Since the system began operation, the arsenic levels in the mine’s tailings pond were reduced from 54 ppb to below the MMER of 50 ppb.
Richard J. Cavagnaro is marketing coordinator for AdEdge Water Technologies LLC. Cavagnaro can be reached at [email protected] or 678.835.0052.
