According to a WHO report, 144 million people across the world are dependent on contaminated surface water for drinking. Meanwhile, in India, less than 50 per cent of the population has access to safe drinking water. Contaminants include chemical effluents or heavy metals discharged from industries.

One such contaminant is Hexavalent Chromium. “Hexavalent chromium is a highly toxic metal ion that has been detected in several water bodies across India. It causes several health problems including skin, lung and other cancers, as well as infertility and liver malfunctioning,” says Dr Vishal Mishra, a researcher at the School of Biochemical Engineering, Indian Institute of Technology, Banaras Hindu University(IIT-BHU).

Two years ago, along with a PhD student Veer Singh, he started working on a cost-effective method to remove the toxic hexavalent chromium metal from wastewater.

Bacteria to purify water

The duo’s research began with understanding the current processes available to treat wastewater. While several approaches were being deployed, the current technology was too expensive or time-consuming.

“So we started the research by identifying Bacteria which could separate the hexavalent chromium from highly toxic wastewater. Initially, we faced a few challenges to identify the correct bacteria. When we identified a few, they did not give us expected results during tests. However, after several trials, we landed on the correct bacteria,” says Veer.

Named ‘Microbacterium paraoxydans strain VSVM (IIT-BHU)’, this bacteria can tolerate high concentrations of hexavalent chromium, the duo says.

“Tests were conducted on bacteria strains isolated from wastewater containing hexavalent chromium, which was sourced from a coal mine in Singrauli, Madhya Pradesh. The bacteria showed a fast growth rate over the hexavalent chromium. Within 24 hours, this was converted to trivalent chromium, which is not harmful,” says Veer, adding that this treatment process can be introduced into existing wastewater treatment plants.

Further, the duo published a research paper on their findings and are focused on conducting more tests with the bacteria. They hope to identify other toxic metals it can remove from wastewater.

Veer says, “Currently, the bacteria has proved advantageous to remove other toxic metals like cadmium and lead.”