Lampa is a rapidly developing neighborhood located just outside the capital city of Santiago in Chile. The community is served by two wells, each with a flow of 800 gallon per minute (or 50 liters per second), running one at a time. Both wells produce raw water with high arsenic concentrations that fluctuate between 0.015 and 0.030 mg/L, which is above the World Health Organization’s recommended level of 0.010 mg/L.
The system is managed by Aguas Andinas, which is the largest municipal water provider in Chile. In 2012 the project was awarded to EcoRiles, who then contracted AdEdge Water Technologies to supply and start up the treatment system equipment.
The AdEdge arsenic treatment approach consists of two WaterPOD containerized treatment units, each with five 48-inch diameter carbon steel vessels arranged in a parallel configuration. The vessels are loaded with AdEdge’s Bayoxide E33 granular ferric oxide (GFO) adsorption media, which allows the arsenic to remain bound to the media structure and does not become loose during backwash.
The system has chemical dosing and backwash recycle equipment built inside the WaterPODs. A section of WaterPOD #1 was partitioned to serve as a chemical room separated from the rest of the equipment, to avoid corrosion from chemical off-gassing. Inside the chemical room, there are separate partitions for the two chemicals (sodium hypochlorite and hydrochloric acid) to further segregate the chemicals and avoid unintentional mixing. Sodium hypochlorite is added to oxidize the arsenic from trivalent to pentavalent. Hydrochloric acid is added to lower the pH and improve media life. The WaterPOD #2 contains the equipment for the backwash recycle pump and bag filters. The backwash holding tank was situated outside of the WaterPODs. The system performs backwash of the vessels every 45 to 60 days to prevent hydraulic channeling and remove any suspended solids that may have accumulated in the bed. Backwash operations are automatically controlled by an AdEdge InGenius control panel with PLC and HMI.
The source of the water is treated water from the outlet of the distribution pumps. The system was successfully started up in early August 2013. Recent testing shows the treated water now having non-detectable concentrations of arsenic.
Case Study Fast Facts
Client: Aguas Andinas
Location: Lampa, Chile
Date: August 2013
Contaminant treated: Arsenic
Flow rate: 800 gpm