Arsenic reduction

Quilicura, Chile

Quilicura is a municipality located in the Santiago Metropolitan Region in Chile. Well #3 has a flow of 1600 gallons per minute (100 liters per second). The well has a high concentration of arsenic that fluctuates between 0.040 mg/L and 0.060 mg/L, well above the World Health Organization’s standard of 0.010 mg/L. In addition to the high arsenic concentration, the site has challenges with pH that ranges from 7.0 to 9.5. AdEdge was contacted by EcoRiles in 2013 to design, manufacture, and commission an arsenic removal solution for the Quilicura municipality.

The AdEdge arsenic treatment solution consists of four WaterPOD containerized systems rated for a combined total of 1600 gpm (100 lps). Each WaterPOD contains six 48-inch carbon steel vessels in a parallel configuration. The vessels are loaded with AdEdge Bayoxide E33 granular ferric oxide media. The E33 binds the arsenic to the media structure and does not lose that bond during backwash. The system has an ADIN chemical feed dosing system that is mounted outside the WaterPODs.

The chemical feed dosing system consists of a sodium hypochlorite module that oxidizes the arsenic from trivalent to pentavalent. A second chemical feed module uses hydrochloric acid to lower the pH and improve media life.

Backwashing of the treatment vessels occurs every 45 – 60 days to prevent hydraulic channeling and to remove any suspended solids that may have accumulated in the bed. Backwash operations are automatically controlled by an AdEdge InGenius control panel that includes a PLC and a HMI.

The WaterPOD treatment units were shipped in 2013 to Chile and began operation in November 2013. The treatment units have consistently lowered the arsenic concentration to non-detectable levels since they started up.

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