Millions of people worldwide are exposed to high levels of arsenic in water, increasing their risk of developing sores, gastrointestinal problems and various forms of cancer. A team from Heriot-Watt University has taken on the crisis by installing several chemical-free plants designed to safely remove arsenic from water.
A lack of drinkable water has led to at least 137 million people, across 70 countries, consuming arsenic-laced, potentially deadly groundwater. The global crisis has also seen millions of others contract dangerous conditions from consuming rice and vegetables prepared in polluted water. In response, an EU-India team – led by Heriot-Watt’s Professor in Water Technology, Bhaskar Sen Gupta OBE – installed the world’s first chemical and waste-free water treatment plant in the arsenic belt of India. Consequently, the operation has provided drinking water to the vast community of rural people in that area, most of which earn less than one US dollar per day. Since then, many other installations have been made, helping some of the world’s poorest people in the process.
The conventional technologies for arsenic remediation are based on a ‘pump and treat’ method, which is uneconomical to run and has problems associated with waste disposal. In contrast, the Subterranean Arsenic Removal (SAR) developed by Professor Sen Gupta and his co-researchers doesn’t use chemicals, or generate any waste, making it a uniquely low-cost operation.
SAR’s signature process encourages the growth of arsenic oxidising bacteria in the aquifer which converts arsenic – along with iron and manganese – into soluble masses that return safely to the soil. The underground aquifer is effectively turned into a natural biochemical absorber that removes the dangerous substances from groundwater, triggering a series of physical, chemical and biological processes which result in an oxygen-rich supply of water for local people.
The technology is considered world-leading and viewed among judging panels as setting the standard. The pioneering plants have won a clutch of prestigious awards, including the Institute of Chemical Engineers Outstanding Innovation Award for resource poor people (2009), the St Andrews Prize for the Environment (2010) and the Energy Globe World Award (2012).
Professor Sen Gupta, in collaboration with the Indian Institute of Engineering Science and Technology, has also opened an arsenic treatment plant at North 24 Parganas in West Bengal. The facility provides low-cost water to the local community through a rural entrepreneur, produces up to 6000 litres of clean water each day and benefits nearly 300 families.
A further 13 systems have now been unrolled worldwide. Meanwhile, a new model, which is flood-proof and runs on solar power, was designed and installed by Professor Sen Gupta and him team in the Mekong Delta of Cambodia during 2011-12. In 2017, even greater ambition followed with a remotely operated plant in Bangladesh. The facility, in the Comilla District, provides safe water to 200 school children and, within a year, it will serve an additional 800 members of the community.
The plant is operated from a mobile phone app and will have no running costs for the next quarter of a century. Three of these systems have been running successfully since installation, with virtually no operating or maintenance costs.