Researchers raise deironing efficiency with chamotte granules
A Russian-Belorussian research team has come up with a new method for underground water deironing. Their findings show that modified refractory chamotte granules increase the efficiency of water deironing up to 78 percent, making underground waters safe to drink. The study was published in the Journal of Environmental Chemical Engineering.
The iron content in underground water could reach 40 mg/L and even higher while in accordance with the requirements of the World Health Organization (WHO). The permissible content of iron in drinking water is 0.2 mg/L. Such water requires purification before it could be safely used.
Today, the most common method for removing naturally occurring iron from water is oxidation with oxygen or other agents, i.e. potassium, chlorine and ozone. The process involves the oxidation of the soluble forms of iron to their insoluble forms and then removal by filtration. It is carried out using deironing filters, filled with granulated quartz sand, different types of coals, granite crumbs and others. The efficiency of the deironing could also be increased by surface modification of the fillers. The most common method for fillers' surface modification is the soaking of the modified material in solutions of metal salts, followed by their drying and calcination within a long time. This approach is very energy- and time-consuming.
The research team considers using the solution combustion synthesis (SCS) approach to be a more efficient and faster alternative. The SCS is based on a combination of the homogeneous mixing of initial components in an aqueous solution and their self-propagated combustion in a high-exothermic redox reaction. The whole combustion synthesis process, including heating, reaction and cooling down, takes from several seconds to 10 min, depending on the system.
The scientists have come up with an innovative method for underground water deironing based on the SCS reaction. They used refractory chamotte as the main component of filter filler. The study found that the modification of the surface of chamotte granules increases the efficiency of water deironing by 45 to 78 percent, depending on modifiers’ concentrations.
"The materials obtained are up to three times more efficient than those currently used at drinking water treatment plants. The modification process is up to 30 times more time-efficient than other commonly used techniques, and up to 100 times less energy consuming due to the exothermic and self-sustaining nature of the combustion," said Valentin Romanovsky, Research Center for Structural Ceramic Nanomaterials at NUST MISIS.
Iron-rich waste (up to 60 percent by weight of iron) from water deferrization stations were used as a source of iron for the modification of the surface of chamotte granules. The researchers believe that these benefits could help create efficient water deironing filters with a high degree of recyclable secondary resources.
SOURCE: NUST MISIS, via PR Newswire