Yaakov Liss, MD, a nephrologist at CareMount Medical in New York. Yes, really. 'Some amount of bubbles in the urine is normal,' says Yaakov Liss, MD, a nephrologist at CareMount Medical in New York.

A more efficient way to extract fertiliser from human urine could help make better use of wastewater in cities and farms, without exacerbating global warming. Human urine is rich in compounds ...