Using light and sand to kill waterborne viruses
Basic sanitation is unfortunately still lacking in many parts of the world. Low-cost technology is the only way forward. Manmade wetlands employ natural methods to purify wastewater, but little is known about their ability to inactivate pathogens, particularly waterborne viruses. Important research in this area was carried out with the context of a Marie Curie fellowship. The EU-funded project Parvirdis used molecular biology techniques to determine the effects of different types of treatment on viruses. Specifically the method of quantitative polymerase chain reaction was employed to measure damage to the genome of a test virus following exposure to heat, ultraviolet (UV) light and a reactive oxygen species. UV light turned out to be the most effective at rendering the virus ineffective. Building on previous research showing that viruses readily attach themselves to metal oxides through a process called adsorption, an iron-oxide coated sand (IOCS) was tested during Parvirdis. While highly effective at trapping viruses in the laboratory, the IOCS did not fare as well in the wetland environment where pH and other water properties were not as ideal. However, when IOCS was combined with exposure to sunlight, the results were impressive. This is due to the local production of elevated concentrations of the highly reactive hydroxyl radical, which knock the viruses out of commission. These findings are being applied to the development of a new concept for constructed wetlands for the treatment of wastewater.
