Electronic nose on a drone sniffs out wastewater stink

Researchers have engineered a portable electronic nose almost as sharp as a human nose at sniffing out the stink of wastewater treatment plants with the help of artificial intelligence (AI). Coupled with a drone, the lightweight e-nose (1.3 kg) can measure the concentration of different smells, predict odour intensity, and produce a real-time odour map of the plant for management.

The team collected bags of air from a plant and trained the e-nose to sniff out pungent chemicals such as Hydrogen sulfide, ammonia, and Sulfur dioxide, which smell like rotten eggs, urine, and burnt matches, respectively. The e-nose is also equipped with a sensor for Carbon dioxide, an indicator of bacterial activity. In laboratory settings, the e-nose performed nearly as well as human noses.

Hovering over different facilities at the plant, the "sniffing drone" sucks in air via a ten-meter tube and analyses the air in a sensor chamber.

The results demonstrated that the e-nose on a drone was feasible for wastewater odour monitoring. When analysing the same air samples in a field test, 10 out of 13 measurements from the e-nose aligned with the human panel's assessments. Aided by the drone's mobility and the AI algorithm, the team also mapped out the temporal and spatial odour concentration and, for the first time, predicted the intensity of the scent from drone measurements.