World Health Organization (WHO) guidelines for arsenic stand at 50 micrograms per liter. Countries such as the Netherlands have gone further, mandating 10 micrograms per liter. In Argentina, current arsenic parameters settled by the WHO are accepted as valid and epidemiological studies are being carried out to verify if it is mandatory to be more demanding with the regulations.
The pilot projects in Argentina showed positive results during the first three months of implementation, reducing arsenic levels in the treated groundwater down to 10 micrograms per liter and lower, complying with the outlet concentration with Argentine regulations. Furthermore, significant energy and chemical savings were achieved.
Although the results obtained are encouraging, a longer period is required to draw conclusive conclusions.
“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,” says Ron Jong, a senior water treatment specialist and researcher from KWR. “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.”
By correctly dosing, the arsenic connects to the iron in the water as iron flocs, which can then be removed either using the sand filtration or ultrafiltration.
Jong believes the partnership will eventually help to disseminate knowledge and solutions to other parts of the world, with Argentina acting as a gateway into Latin America.
“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
KWR says 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.
“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,” Jong says. “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.”
