Nearly 1,000 "dark discharges" of untreated sewage from two water company treatment plants in England have been detected by scientists using artificial intelligence to map spills. The use of machine learning to shine a light on the scale of pollution from untreated effluent being spilled into rivers could be a crucial tool in efforts to improve the quality of rivers, a paper says. Prof Peter Hammond, visiting scientist at the UK Centre for Ecology and Hydrology, who co-authored the paper published in the journal Clean Water, used artificial intelligence to analyse data from two unidentified water companies' waste treatment works from 2009 to 2018. The AI identified 926 "dark discharges" – or previously unknown spills – from the storm overflows at the two treatment plants. Discharges of untreated sewage from storm overflows, or CSOs, are permitted only in exceptional circumstances, such as extreme rainfall, the European commission has ruled.

Below the bustling streets of Cambridge, Massachusetts, Luigi is sifting through human waste and gathering data on some 107, 000 people. The smart bot is part of an MIT project to analyse human waste - and could track the health of a city. Luigi (pictured) is a robot in MIT's latest project that focuses on bacteria, viruses and chemical compounds found in the human stomach. Luigi spends about an hour or two inside each sewer and collects samples as the float by. The machine is fitted with ultrasonic sensors, which helps the cylindrical robot hover 40 centimeters above its target.

I've always had a thing for Mario's brother Luigi. So when I recently heard of another Luigi--also tall, thin, and willing to drop into sewers--I had to meet him. At MIT's Senseable City Lab, a team of researchers recently premiered a second-generation robot named Luigi who sifts through sewage as a way to improve public health. Luckily, I didn't have to brave the smells of the sewer to meet him. In a small campus makerspace stacked to the ceiling with batteries, wires, and glue, architects Newsha Ghaeli and Alaa AlRadwan introduce me to Luigi, then proceed to do what all good inventors do: repeatedly try to turn the robot on.