Experts in water treatment from Argentina and the Netherlands are collaborating to find a long-term way to remove arsenic from groundwater.
Arsenic, a naturally occurring chemical found in the air, water, and soil, has been discovered in significant quantities in numerous regions of Argentina.
According to KWR Project Manager Gerard van den Berg, two pilot projects are currently being carried out with the assistance of the Dutch Embassy in Buenos Aires by Argentina’s main water utility Agua y Saneamientos Argentinos S.A.
(AySA), partners Royal HaskoningDHV, TRAIDE, and KWR Water Research Institute (KWR), among others.
Co-precipitation followed by rapid sand filtration (C-RSF) is the basis for one pilot, and co-precipitation followed by ultrafiltration is the basis for the other.
Going above WHO arsenic limits
Currently, the World Health Organization (WHO) recommends no more than 50 micrograms of arsenic per litre. Some nations, like the Netherlands, have taken it a step further by requiring 10 micrograms per litre.
The WHO’s existing arsenic standards are recognised as legitimate in Argentina, and epidemiological studies are being conducted to determine whether stricter limitations are necessary.
Arsenic levels in the treated groundwater were reduced to 10 micrograms per litre or below within the first three months of the pilot projects’ deployment in Argentina, conforming with the outlet concentration requirements.
Although the results are positive, more time must pass before drawing firm conclusions. Additionally, significant chemical and energy savings were made.
Ron Jong, a senior water treatment specialist and researcher from KWR, said: “Many of the existing technologies, such as reverse osmosis membranes or absorption processes use a lot of energy and chemicals, respectively, and operational costs can be high. The new solution developed by KWR, together with the Dutch drinking water companies, requires minimal energy. We apply this process in the Netherlands but as there’s already iron in the water, it works naturally. In Argentina, as the water is iron-free, this iron has to be added.”
The iron in the water is connected to the arsenic by the proper dosage, forming iron flocs that may be removed using either sand filtration or ultrafiltration.
With Argentina serving as a portal into Latin America, Jong hopes that the cooperation will eventually aid in the dissemination of information and solutions to other regions of the world.
“Many other countries in Europe and the rest of the world have arsenic problems seriously affecting drinking water safety. For example, Bangladesh and Serbia, as well.”
Modifying existing processes
Cost calculations to date have shown that if AySA’s current adsorption processes are modified to the co-precipitation rapid sand filtration set-up, these costs would be recuperated in relatively short time.
Jong added: “After proving that arsenic can be removed at the location, we’re looking at adapting the process circumstances to apply it at the bigger water treatment plants.
This will further evaluate and test the ability to modify and operate the process, at a larger scale.”
He says that the challenge of processing the by-product remains with scaling the process in Argentina.
“Waste liquid streams from the current absorption processes can be disposed of into surface waters. However, the waste stream from this new process is an iron sludge containing arsenic.
As questions remain over the potential and reuse options in Argentina, this will require further research.”
AySA considered the partnership with KWR to be very valuable, going beyond knowledge exchange to include new ways of working. It has received support from company president, Malena Galmarini.
Christian Taylor, planning manager at AySA, said: “The technology is suitable for removing arsenic and is aligned with our energy efficiency strategy. It is necessary to continue studying this process at different scales, as it can be very useful for rural populations in Argentina.”
